WorldWideScience

Sample records for pion photoproduction process

  1. Near-threshold charged pion photoproduction from 13C

    International Nuclear Information System (INIS)

    LeRose, J.J.

    1981-01-01

    Differential cross sections to discrete final states have been measured for both positive and negative pion photo-production on 13 C at 90 0 in the lab at pion energies of 18, 29, and 41 MeV. Measurements were made using a fixed angle magnetic spectrometer located in the 14 0 area of the MIT Bates linear accelerator. Pions were detected using a 90 channel multi-wire proportional counter in the focal plane along with a backup array consisting of three 1/16'' thick plastic scintillator detectors and a 1/2'' thick Cerenkov detector. Positive pion photo-production cross sections were obtained for the excitation of the 3/2 - ground state and for the 3.45 MeV first excited state of 13 B. Negative pion photo-production cross sections were obtained for the excitation of the 1/2 - ground state, and the 3/2 to 3.51 MeV and 5/2 to 7.39 MeV excited states of 13 N. The measured positive pion photo-production ground state cross sections are in reasonable agreement wth theoretical calculations. However, there is a large discrepancy between the measured negative pion photoproduction ground state cross sections and the theoretical values. There are no theoretical calculations available for comparison with the excited state measurements in either positive or negative pion photoproduction on 13 C

  2. Soft and hard contributions to hard pion photoproduction

    International Nuclear Information System (INIS)

    Afanasev, Andrei; Carlson, Carl E.; Wahlquist, Christian

    2000-01-01

    Pion photoproduction at high transverse momentum supplements what can be learned in the standard probes of deep inelastic scattering and Drell-Yan processes. With polarized initial states there is sensitivity to the polarized gluon distribution, Δg, in leading order. This contrasts to other processes mentioned, which have no leading order gluon contribution. Additionally, in some kinematic regions the process occurs mainly due to pion production at short distances ('direct pion production', resulting in kinematically isolated pions), which gives sensitivity to the high-x valence quark distribution

  3. Energy-independent multiple analysis of one-pion photoproduction processes on protons

    Energy Technology Data Exchange (ETDEWEB)

    Get' man, V.A.; Sanin, V.M.; Telegin, Yu.N.; Shalatskij, S.V. (AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst.)

    1983-08-01

    For the first time unambiguous estimates are obtained for the multipole photoproduction amplitudes which are based upon the new experimental data on the pion photoproduction on protons combined with the new estiamtes of the ..pi..N-scattering phase shifts. The obtained estimates of the multipole amplitudes are compared with the results of the previous multipole analyses and with the predictions based uoon the dispersion relations.

  4. Pion photoproduction in the Skyrme model and low-energy theorem

    International Nuclear Information System (INIS)

    Saito, Sakae; Takeuchi, Fuminaka; Uehara, Masayuki

    1993-01-01

    We investigate pion photoproduction on the nucleon in the Skyrme model. We employ the formulation, which was recently developed by Hayashi et al., that the full pion field is treated as an interpolating field between asymptotic in and out fields. It is shown that the amplitude of the pion photoproduction is correctly given by the direct and the crossed baryon-pole terms, and the equal-time commutator terms between the axial-vector current and the electromagnetic current and between the pion field and the latter. We show that the lowest-order Kroll-Ruderman and the pion pole terms are reproduced, and that the seagull terms inherent to the Skyrme model are present. Further, the threshold behavior of the amplitude is discussed. (orig.)

  5. Backward pion photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Sibirtsev, A; Haidenbauer, J; Huang, F; Krewald, S; Meissner, U -G

    2009-04-01

    We present a systematic analysis of backward pion photoproduction for the reactions $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p and $ \\gamma$ p $ \\rightarrow$ $ \\pi^{+}_{}$ n . Regge phenomenology is applied at invariant collision energies above 3GeV in order to fix the reaction amplitude. A comparision with older data on $ \\pi^{0}_{}$ - and $ \\pi^{+}_{}$ -photoproduction at $ \\vartheta$ = 180° indicates that the high-energy limit as given by the Regge calculation could be reached possibly at energies of around $ \\sqrt{{s}}$ ≃ 3 GeV. In the energy region of $ \\sqrt{{s}}$ $ \\le$2.5 GeV, covered by the new measurements of $ \\gamma$ p $ \\rightarrow$ $ \\pi^{0}_{}$ p differential cross-sections at large angles at ELSA, JLab, and LEPS, we see no clear signal for a convergence towards the Regge results. The baryon trajectories obtained in our analysis are in good agreement with those given by the spectrum of excited baryons.

  6. Pion photoproduction on the nucleon at threshold

    International Nuclear Information System (INIS)

    Cheon, I.T.; Jeong, M.T.

    1989-08-01

    Electric dipole amplitudes of pion photoproduction on the nucleon at threshold have been calculated in the framework of the chiral bag model. Our results are in good agreement with the existing experimental data

  7. Learning about nucleon resonances with pion photoproduction

    International Nuclear Information System (INIS)

    Walker, R.L.

    1989-01-01

    This chapter charts the discovery of nucleon resonances from pion-nucleon interactions. It was not until after the Albuquerque meeting in 1953 the experimentalists were able to persuade physicists about the existence of this phenomenon with the discovery of the P 33 resonance. The second and third resonances to be discovered, D 13 and F 15 , were seen as peaks in the total cross section for pion plus photoproduction, from 1956 onwards. Knowledge of pion-nucleon scattering has played an important role in the development of quark models. (UK)

  8. Data compilation of single pion photoproduction below 2 GeV

    International Nuclear Information System (INIS)

    Ukai, K.; Nakamura, T.

    1984-09-01

    An updated data compilation on single pion photoproduction experiment below 2 GeV is presented. This data bank includes not only the data of single pion photoproduction processes but also those of the proton Compton scattering (γp → γp) and the inverse process of the γn → π - p (π - p → γn). The number of total data points are 6240 for γp → π + n, 5715 for γp → π 0 p, 2835 for γn → π - p, 177 for γn → π 0 n, 669 for γp → γp, and 112 for π - p → γn processes. The compiled data are stored in the central computer (FACOM M-380R) of the Institute of Nuclear Study, University of Tokyo, for direct use of this data bank and on magnetic tapes with the standard label for other laboratories. The FACOM computer is compatible with an IBM 370 series or IBM 303X or 308X series machines. The data on the magnetic tapes are available on request. (Kato, T.)

  9. Pion photoproduction in nucleons at low energies

    International Nuclear Information System (INIS)

    Carvalho, F.A.B.R. de.

    1983-01-01

    A new semiphenomenological analysis of the multipoles for pion photoproduction from nucleons, in the region of the first π-N resonance is presented. Through an energy dependent model, multipoles with isospin 1/2 and 3/2 and total angular momentum J [pt

  10. Energy-independent multipole analysis of single-pion photoproduction from protons

    Energy Technology Data Exchange (ETDEWEB)

    Get' man, V.A.; Sanin, V.M.; Telegin, Y.N.; Shalatskii, S.V.

    1983-08-01

    For the first time photoproduction multipole amplitudes are evaluated unambiguously on the basis of new experimental data on pion photoproduction from protons and the latest ..pi..N scattering phase shifts. The multipole amplitudes obtained are compared with the results of previous multipole analyses and dispersion-relation predictions.

  11. Energy-independent multipole analysis of single-pion photoproduction from protons

    International Nuclear Information System (INIS)

    Get'man, V.A.; Sanin, V.M.; Telegin, Y.N.; Shalatskii, S.V.

    1983-01-01

    For the first time photoproduction multipole amplitudes are evaluated unambiguously on the basis of new experimental data on pion photoproduction from protons and the latest πN scattering phase shifts. The multipole amplitudes obtained are compared with the results of previous multipole analyses and dispersion-relation predictions

  12. Photoproduction of neutral pions off protons

    NARCIS (Netherlands)

    Crede, V.; Sparks, N.; Wilson, A.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, R.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, Chr; Gregor, R.; Gridnev, A.; Gutz, E.; Hillert, W.; Hoffmeister, P.; Jaegle, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Klein, Frank; Klein, Friedrich; Klempt, E.; Kotulla, M.; Krusche, B.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, Ch

    2011-01-01

    Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction gamma p -> p pi(0) for photon energies between 0.85 and 2.50 GeV. The pi(0) mesons are observed in their dominant neutral decay mode: pi(0) -> gamma gamma. For the first time, the differential cross

  13. Connections between Compton scattering and pion photoproduction in the delta region

    International Nuclear Information System (INIS)

    Mukhopadhyay, N.C.; Benmerrouche, M.

    1992-01-01

    Using textbook tools like analyticity, unitarity and optical theorem, the authors discuss the relationship between pion-nucleon scattering, pion photoproduction and Compton scattering in the Δ(1232) resonance region. They review the relevant data and draw conclusions pertinent to the QCD-inspired models. 27 refs

  14. Off-shell form factors in the soft photon limit for pion photoproduction

    International Nuclear Information System (INIS)

    Chumbalov, A.A.; Kamalov, S.S.

    1991-01-01

    The low energy theorems for the pion photoproduction are considered on the basis of the Adler-Dothan procedure. It is shown that the soft photon limit necessarily leads to the Born approximation for the π 0 -photoproduction amplitude at the threshold. All additional terms, according to the Adler-Dothan recipe, are to be neglected in the derivation of the LET. 5 refs.; 2 figs

  15. Coherent pion photoproduction from deuterium at intermediate energies

    International Nuclear Information System (INIS)

    Osland, P.; Rej, A.K.

    1975-12-01

    The coherent photoproduction of neutral pions on deuterons is studied at energies around the (3,3) resonance and discuss the effects of the Fermi motion, rescattering and kinematical approximations. The results are very dependent upon what kinematical approximations one adopts for the impulse approximation term, which dominates up to very large angles. Allowing for this uncertainty in the kinematics, our results are in good agreement with the most recent experimental data

  16. Photoproduction of pions on low-energy protons

    International Nuclear Information System (INIS)

    Grushin, V.F.

    1989-01-01

    This paper reports that a study is made of the complete experiment problem and photoproduction of pions on protons. The problem of the volume and content of a complete experiment is solved in the area of photon energies up to 500 MeV for the channels γp-π + n and γp-π → π 0 p. Experimental data assuring a complete experiment are used for multipole analysis of the channels γp → π + n, π 0 p and the real and imaginary parts of s- and p-wave multipole amplitudes are obtained. Estimates are produced for the pole parameters (mass and width) of the Δ + 33 isobar. An electrical quadrupole amplitude of the transition γp → Δ + 33 was found which is significantly different form zero, indicating the existence of a tensor interaction between quarks in hadrons. Data on photoproduction on mesons are used to extract quantitative estimates of the vector and tensor constants of interaction of an ω meson with nucleons

  17. Study of the Two Pion Photoproduction on Deuterium

    Science.gov (United States)

    Gauss, Lewis P. Graham, Jr.

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the primary challenges in strong inter-action physics. This interaction is governed by Quantum Chromodynamics (QCD), which is a theory for understanding the dynamics of strong. QCD displays the asymptotic freedom of hadrons at very short distances and also the confinement of quarks and gluons inside hadrons. However, solutions of this QCD theory in the non-perturbative domain of the interaction are extremely difficult to achieve, mainly because confinement happens on the hadronic scale on which the coupling constant is large and prevents any perturbative approach. Thus leaving us with strategies such as lattice QCD or formulating QCD sum rules to get around this problem. In exclusive hadron production the γN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be investigated through the transition amplitudes to the N and Δ resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through meson photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of the nucleon and the photo-excited resonance decays through photon scattering off a deuteron producing two pions in the final state. This photoproduction process off the deuteron will be used to investigate known baryon resonances in the two pion channel. The two pion final state will be investigated for unraveling new information into the photo-coupling strengths. We want to explore final state interactions, search for properties of known resonances, and to explore the possibility of seeing missing states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large Acceptance

  18. Pion inelastic scattering, pion photoproduction and inelastic electron scattering on light nuclei

    International Nuclear Information System (INIS)

    Ehramzhyan, R.A.

    1985-01-01

    Partial transitions in pion photoproduction reaction on 6 Li, 10 B, 12 C nuclei are considered. Particular stress is paied to simultaneous analysis both of (γ, π) ad (e, e'), (π, π') reactions. Such analysis is concretely ixemplified with the use of both phenomenological and microscopic approaches. Microscopic analysis is shown to give correct representation of reaction mechanism (γ, π), (e, e') and (π, π') at intermediate energies. Spin-isospin dipole resonances in 1p-shell nuclei are considered. It is shown that nuclear system excitation spectrum gross-structure is a result of resonance configuration splitting

  19. Study of the Two-pion Photoproduction on the Deuteron

    Energy Technology Data Exchange (ETDEWEB)

    Graham, Lewis P. [Univ. of South Carolina, Columbia, SC (United States)

    2012-12-01

    Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the primary challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD), which is a theory for understanding the dynamics of strong. QCD displays the asymptotic freedom of hadrons at very short distances and also the confinement of quarks and gluons inside hadrons. However, solutions of this QCD theory in the non-perturbative domain of the interaction are extremely difficult to achieve, mainly because confinement happens on the hadronic scale on which the coupling constant is large and prevents any perturbative approach. Thus leaving us with strategies such as lattice QCD or formulating QCD sum rules to get around this problem. In exclusive hadron production the yN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be investigated through the transition amplitudes to the N and Delta resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through meson photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of the nucleon and the photo-excited resonance decays through photon scattering off a deuteron producing two pions in the final state. This photoproduction process off the deuteron will be used to investigate known baryon resonances in the two pion channel. The two pion final state will be investigated for unraveling new information into the photo-coupling strengths. We want to explore final state interactions, search for properties of known resonances, and to explore the possibility of seeing missing states that are predicted by quark models but have not yet been found experimentally. Using the CEBAF Large

  20. Isotensor electromagnetic current in low energy pion photoproduction

    International Nuclear Information System (INIS)

    Aznauryan, I.G.; Nagorskaya, I.A.; Zaslavskij, A.N.

    1974-01-01

    Recent experimental data on single pion photoproduction in the Δ (1236) resonance region are discussed. The role of the high energy contributions into the dispersion integrals are analyzed. Estimates for the magnitude of the isotensor contributions are obtained in the dispersion approach using the experimental data of various groups. In spite of the great number of the experiments the estimate is ambiguous yet since there are direct discrepancies between the data of various groups, besides, certain available data are incomplete. The data of some groups are compatible with 10% isotensor contribution

  1. Threshold pion photoproduction in A light-cone quark model

    International Nuclear Information System (INIS)

    Konen, W.; Drechsel, D.

    1991-01-01

    The instantaneous and seagull graphs are calculated for pion photoproduction in a relativistic light-cone model of the nucleon. In both pseudoscalar and pseudovector coupling we find the ratios A (-) :A (0) :A (+) =1:(-1/2μ):(-9/5 1/2μ) in the nonrelativistic limit. These results correspond to the sum of seagull and Z-graph in the nonrelativistic quark model. In pseudovector coupling also the numerical results for realistic-model parameters are close to those values. (orig.)

  2. The low-energy theorem of pion photoproduction using the Skyrme model

    International Nuclear Information System (INIS)

    Ikehashi, T.; Ohta, K.

    1995-01-01

    We reassess the validity of the current-algebra based low-energy theorem of pion photoproduction on the nucleon using the Skyrme model. We find that one of the off-shell electromagnetic form factors of the nucleon exhibits infrared divergence in the chiral limit. This contribution introduces an additional term to the threshold amplitude predicted by the low-energy theorem. The emergence of the additional term indicates an unavoidable necessity of off-shell form factors in deriving the low-energy theorem. In the case of neutral pion production, the new contribution to the threshold amplitude is found to be comparable in magnitude to the low-energy theorem's prediction and has the opposite sign. In the charged pion production channels, the correction to the theorem is shown to be relatively small. (orig.)

  3. Measurement of the G double-polarisation observable in pion photoproduction

    International Nuclear Information System (INIS)

    McAndrew, J.; Watts, D.; Pasyuk, E.

    2012-01-01

    The g9a experiment using the CLAS detector in Hall B of Jefferson Lab will measure double-polarization observables using a polarized energy-tagged photon beam in conjunction with the frozen spin target, FROST. This contribution describes the extraction of the G double polarization observable in the single pion photoproduction using a linearly polarized photon beam in the energy range 730-2300 MeV and the longitudinally polarized frozen spin target, FROST.

  4. Deuteron Compton scattering below pion photoproduction threshold

    Science.gov (United States)

    Levchuk, M. I.; L'vov, A. I.

    2000-07-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  5. Deuteron Compton scattering below pion photoproduction threshold

    International Nuclear Information System (INIS)

    Levchuk, M.I.; L'vov, A.I.

    2000-01-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data

  6. Deuteron Compton scattering below pion photoproduction threshold

    Energy Technology Data Exchange (ETDEWEB)

    Levchuk, M.I. E-mail: levchuk@dragon.bas-net.by; L' vov, A.I. E-mail: lvov@x4u.lebedev.ru

    2000-07-17

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  7. Double-polarization observable G in neutral-pion photoproduction off the proton

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, A.; Lang, M.; Afzal, F.; Beck, R.; Boese, S.; Funke, C.; Gottschall, M.; Gruener, M.; Hammann, C.; Hannappel, J.; Hartmann, J.; Hoffmeister, P.; Honisch, C.; Kaiser, D.; Kalinowsky, H.; Kalischewski, F.; Klassen, P.; Klempt, E.; Koop, K.; Kube, M.; Mahlberg, P.; Mueller, J.; Muellers, J.; Piontek, D.; Schmidt, C.; Seifen, T.; Sokhoyan, V.; Spieker, K.; Thoma, U.; Urban, M.; Pee, H. van; Walther, D.; Wendel, C.; Winnebeck, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Eberhardt, H.; Bantes, B.; Dutz, H.; Elsner, D.; Ewald, R.; Fornet-Ponse, K.; Frommberger, F.; Goertz, S.; Hammann, D.; Hillert, W.; Jude, T.; Kammer, S.; Kleber, V.; Klein, F.; Reeve, S.; Runkel, S.; Schmieden, H. [Universitaet Bonn, Physikalisches Institut, Bonn (Germany); Anisovich, A.V.; Bayadilov, D.; Nikonov, V.; Sarantsev, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Bichow, M.; Meyer, W.; Reicherz, G. [Ruhr-Universitaet Bochum, Institut fuer Experimentalphysik I, Bochum (Germany); Brinkmann, K.T.; Gutz, E. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen und Kernphysik, Bonn (Germany); Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Crede, V. [Florida State University, Department of Physics, Tallahassee, FL (United States); Dieterle, M.; Keshelashvili, I.; Krusche, B.; Witthauer, L. [Universitaet Basel, Institut fuer Physik, Basel (Switzerland); Friedrich, S.; Makonyi, K.; Metag, V.; Nanova, M. [Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Gridnev, A.; Lopatin, I. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Wilson, A. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Florida State University, Department of Physics, Tallahassee, FL (United States); Collaboration: The CBELSA/TAPS Collaboration

    2017-01-15

    This paper reports on a measurement of the double-polarization observable G in π{sup 0} photoproduction off the proton using the CBELSA/TAPS experiment at the ELSA accelerator in Bonn. The observable G is determined from reactions of linearly polarized photons with longitudinally polarized protons. The polarized photons are produced by bremsstrahlung off a diamond radiator of well-defined orientation. A frozen spin butanol target provides the polarized protons. The data cover the photon energy range from 617 to 1325 MeV and a wide angular range. The experimental results for G are compared to predictions by the Bonn-Gatchina (BnGa), Juelich-Bonn (JueBo), MAID and SAID partial wave analyses. Implications of the new data for the pion photoproduction multipoles are discussed. (orig.)

  8. Watson's theorem and resonant pion photoproduction amplitude in the delta channel

    International Nuclear Information System (INIS)

    Wittman, R.; Davidson, R.; Mukhopadhyay, N.C.

    1984-01-01

    The CGLN and BL theories of the pion photoproduction on nucleons, used in nuclear calculations, are examined regarding their predictions of the resonant M 1 + and E 1 + multipoles. The nonunitary BL approach violates Watson's theorem, and predicts these multipoles porly. In the static limit, the CGLN multipoles satisfy Watson's theorem and are in fine agreement with data. The unitarized BL multipoles agree with those from the Olsson theory and data. (orig.)

  9. Precise tests for the unitarized pion photoproduction impulse amplitude in exclusive nuclear reactions

    International Nuclear Information System (INIS)

    Wittman, R.

    1986-07-01

    An impulse amplitude for pion photoproduction, suitable for the nuclear problem, is constructed with improved background dynamics and unitarity. The superior features of the amplitude are demonstrated at energies between threshold (E/sub γ/ = 150 MeV) and the Δ(1232) resonance energy (E/sub γ/ = 320 MeV) by discussing their effects on partial cross sections relevant to exclusive transitions in the 1p-shell. The specific reactions of 13 C(γ,π - ) 13 N/sub g.s./ and 14 N(γ,π + ) 14 C/sub g.s./ are discussed in light of these more general partial cross sections. The nuclear structure of the A = 14 system helps to enhance the effects considered. At or near resonance, very sizable (20 to 30%) effects arise both from the unitarity and from the refined treatment of the pionic final state interaction generated in the Δ-hole approach. Other examples of charged pion photoproduction reactions for 1p-shell nuclei are discussed briefly. Future theoretical improvements and experimental possibilities are suggested. 61 refs., 58 figs

  10. Photoproduction of pions on nuclear in chiral bag model with account of motion effects of recoil nucleon

    International Nuclear Information System (INIS)

    Dorokhov, A.E.; Kanokov, Z.; Musakhanov, M.M.; Rakhimov, A.M.

    1989-01-01

    Pion production on a nucleon is studied in the chiral bag model (CBM). A CBM version is investigated in which the pions get into the bag and interact with quarks in a pseudovector way in the entire volume. Charged pion photoproduction amplitudes are found taking into account the recoil nucleon motion effects. Angular and energy distributions of charged pions, polarization of the recoil nucleon, multipoles are calculated. The recoil effects are shon to give an additional contribution to the static approximation of order of 10-20%. At bag radius value R=1 in the calculations are consistent with the experimental data

  11. Intermediate-energy nuclear photoabsorption and the pion optical potential

    International Nuclear Information System (INIS)

    Christillin, P.

    1984-01-01

    Nuclear photoabsorption around the pion threshold is schematised as photoproduction of a pion which undergoes final-stae interaction with the nucleus, accounted for by the pion optical potential. It is shown that real pion photoproduction and exchange effects are naturally described by the same mechanism with a non-static pion. The complementarity of photoabsorption to pion physics and its usefulness in gaining new information about pion-nucleus dynamics are stressed. (author)

  12. Total disintegration of three-nucleon nuclei in charged-pion photo-production

    International Nuclear Information System (INIS)

    Dzhibuti, R.I.; Kezerashvili, R.Y.

    1984-01-01

    The total disintegration of three-nucleon nuclei in charged-pion photo-production is studied within the framework of the microscopic approach based on the method of hyperspherical functions. The initial and final nuclear states are described using the same NN potentials. The differential and total cross sections are calculated using various NN potentials. It is shown that the cross sections are sensitive to the form of the NN interaction and to the final-state interaction of the three nucleons. It is found that the cross section for π - meson production is systematically larger than the cross section for π + meson production. The importance of an experimental investigation of these reactions is shown

  13. Two-pion production in photon-induced reactions

    Indian Academy of Sciences (India)

    A deeper understanding of the situation is anticipated from a detailed experimental study of meson photoproduction from nuclei in exclusive reactions. In the energy regime above the (1232) resonance, the dominant double pion production channels are of particular interest. Double pion photoproduction from nuclei is ...

  14. Reaction mechanisms in coherent nuclear photoproduction

    International Nuclear Information System (INIS)

    Lazard, C.

    Nuclear coherent pion photoproduction is studied. Pion rescattering and propagation effects inside nucleus and mesic exchange current effects are discussed. Influence of nuclear wave functions and Fermi motion is presented [fr

  15. Elastic and inelastic pion reactions on few nucleon systems

    International Nuclear Information System (INIS)

    Lensky, V.

    2007-01-01

    In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)

  16. Elastic and inelastic pion reactions on few nucleon systems

    Energy Technology Data Exchange (ETDEWEB)

    Lensky, V.

    2007-09-29

    In the present work, we are studying elastic and inelastic pion reactions on few-body systems within the framework of chiral effective theory. We consider two specific reactions involving pions on few-nucleon systems, namely pion production in nucleon-nucleon collisions, and incoherent pion photoproduction on the deuteron. These two reactions are closely related to the issue of dispersive and absorptive corrections to the pion-deuteron scattering length, which we also consider in our analysis. The incoherent pion photoproduction is also considered as the possible source for a high-precision determination of the neutron-neutron scattering length. (orig.)

  17. psi and excess leptons in photoproduction

    International Nuclear Information System (INIS)

    Ritson, D.M.

    1976-03-01

    The A-dependence of psi photoproduction was measured on beryllium and tantalum. From this it is found sigma/sub psi N/ = 2.75 +- 0.90 mb. A study was made of excess leptons relative to pion production in photoproduction. A μ/π ratio of 1.40 +- 0.25 x 10 -4 was found at 20 GeV incident photon energy. The energy dependence of psi photoproduction was determined and appeared to have a ''pseudo-threshold'' at 12 GeV

  18. Inclusive Photoproduction of Neutral Pions in the Photon Hemisphere at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Arkadov, V.; Astvatsatourov, A.; Ayyaz, I.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bassler, U.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Bernardi, G.; Berndt, T.; Bertrand-Coremans, G.; Bizot, J.C.; Borras, K.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruel, P.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burkhardt, H.; Burrage, A.; Buschhorn, G.; Campbell, A.J.; Cao, Jun; Carli, T.; Caron, S.; Chabert, E.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; David, M.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dixon, P.; Dodonov, V.; Donovan, K.T.; Dowell, J.D.; Droutskoi, A.; Duprel, C.; Ebert, J.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferrarotto, F.; Ferron, S.; Fleischer, M.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Ghazaryan, Samvel; Glazov, A.; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haustein, V.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hilgers, M.; Hiller, K.H.; Hilton, C.D.; Hladky, J.; Hoting, P.; Hoffmann, D.; Hoprich, W.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Jansen, D.M.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Kaufmann, O.; Kausch, M.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Knies, G.; Koblitz, B.; Kolanoski, H.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Krasny, M.W.; Krehbiel, H.; Kroseberg, J.; Krucker, D.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Kutuev, R.; Lachnit, W.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lebedev, A.; Leissner, B.; Lemaitre, V.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; Lobo, G.; Lobodzinska, E.; Lobodzinski, B.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Magnussen, N.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Mehta, A.; Meier, K.; Merkel, P.; Metlica, F.; Meyer, A.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, D.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Negri, I.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Nunnemann, T.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Passaggio, S.; Patel, G.D.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Riess, S.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Royon, C.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleif, S.; Schleper, P.; Schmidt, D.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Siegmon, G.; Sievers, P.; Sirois, Y.; Sloan, T.; Smirnov, P.; Smith, M.; Solochenko, V.; Solovev, Y.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Steinhart, J.; Stella, B.; Stellberger, A.; Stiewe, J.; Straumann, U.; Struczinski, W.; Sutton, J.P.; Swart, M.; Tasevsky, M.; Tchernyshov, V.; Tchetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vazdik, Y.; von Dombrowski, S.; Wacker, K.; Wallny, R.; Walter, T.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Wegner, A.; Wengler, T.; Werner, M.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wollatz, H.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

    2001-01-01

    The inclusive cross section for the photoproduction of neutral pions has been measured as a function of the transverse momentum, rapidity, and Feynman x of the pizero mesons at an average photon--proton centre-of-mass energy of 208 GeV and for photon virtualities below Q^2=0.01 GeV^2. The pizero measurement extends the range covered by previous charged particle measurements at HERA by two units of rapidity in the photon direction down to a value of -5.5 in the gamma p centre-of-mass frame. The pizero transverse momentum distribution is well described over the whole measured range by a power law ansatz, while an exponential fit falls below the data at transverse momentum values above 1.5 GeV/c. Good agreement with the predictions of the Monte Carlo models PYTHIA and PHOJET is found. In the context of the PYTHIA model the data are inconsistent with large intrinsic transverse momentum values in the photon.

  19. Features of πΔ photoproduction at high energies

    Science.gov (United States)

    Nys, J.; Mathieu, V.; Fernández-Ramírez, C.; Jackura, A.; Mikhasenko, M.; Pilloni, A.; Sherrill, N.; Ryckebusch, J.; Szczepaniak, A. P.; Fox, G.; Joint Physics Analysis Center

    2018-04-01

    Hybrid/exotic meson spectroscopy searches at Jefferson Lab require the accurate theoretical description of the production mechanism in peripheral photoproduction. We develop a model for πΔ photoproduction at high energies (5 ≤Elab ≤ 16 GeV) that incorporates both the absorbed pion and natural-parity cut contributions. We fit the available observables, providing a good description of the energy and angular dependencies of the experimental data. We also provide predictions for the photon beam asymmetry of charged pions at Elab = 9 GeV which is expected to be measured by GlueX and CLAS12 experiments in the near future.

  20. Determination of amplitudes in neutral pion photoproduction and comparison with partial waves analysis in the energy range of 1.3 to 2.1 GeV

    International Nuclear Information System (INIS)

    Forozani, G.

    2004-01-01

    The magnitude of four independent amplitudes are obtained pion photoproduction in the energy range of 1300 to 2100 MeV incident photon. Different cross section and three polarization parameters are required for such amplitudes reconstruction at different pion scattering angles. Results of the direct amplitudes reconstruction have been compared with the solution of partial wave analysis SM95 and SM00K at all energies. This analysis indicates that we have a fair agreement between the present work and the results of partial wave analysis at many angles

  1. Determination of amplitudes in neutral pion photoproduction and comparison with partial waves analysis in the energy range of 1.3 to 2.1 GeV

    International Nuclear Information System (INIS)

    Forozani, G.

    2004-01-01

    The magnitude of four independent amplitudes are obtained in neutral pion photoproduction in the energy range of 1300 to 2100 MeV incident photon. Differential gross section and three polarization parameters are required for such amplitudes reconstruction at different pion scattering angles. Results of the direct amplitudes reconstruction have been compared with the solution of partial wave analysis SM95 and SM00K at all energies. This analysis indicates that we have a fair agreement between the present work and the results of partial wave analysis at meny angles (Author)

  2. Data compilation of single pion photoproduction below 2 GeV

    International Nuclear Information System (INIS)

    Inagaki, Y.; Nakamura, T.; Ukai, K.

    1976-01-01

    The compilation of data of single pion photoproduction experiment below 2 GeV is presented with the keywords which specify the experiment. These data are written on a magnetic tape. Data format and the indices for the keywords are given. Various programs of using this tape are also presented. The results of the compilation are divided into two types. The one is the reference card on which the information of the experiment is given. The other is the data card. These reference and data cards are written using all A-type format on an original tape. The copy tapes are available, which are written by various types on request. There are two kinds of the copy tapes. The one is same as the original tape, and the other is the one different in the data card. Namely, this card is written by F-type following the data type. One experiment on this tape is represented by 3 kinds of the cards. One reference card with A-type format, many data cards with F-type format and one identifying card. Various programs which are written by FORTRAN are ready for these original and copy tapes. (Kato, T.)

  3. Neutral pion photoproduction off nucleons and nuclei near threshold

    International Nuclear Information System (INIS)

    Kamalov, S.S.; Chumbalov, A.A.

    1989-01-01

    The modern experimental data on the coherent photoproduction off 4 He, 6 Li, 12 C, 16 O, 40 Ca and 208 Pb are analyzed in terms of the DWIA in the momentum space. It is shown that the elaborated elementary amplitudes do not give a possibility of the simultaneous self-consistent description of the process on free nucleons and nuclei. 36 refs.; 11 figs.; 2 tabs

  4. Exclusive $\\rho^0$ Meson Photoproduction with a Leading Neutron at HERA

    CERN Document Server

    Andreev, V.; Begzsuren, K.; Belousov, A.; Bolz, A.; Boudry, V.; Brandt, G.; Brisson, V.; Britzger, D.; Buniatyan, A.; Bylinkin, A.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Chekelian, V.; Contreras, J.G.; Cvach, J.; Dainton, J.B.; Daum, K.; Diaconu, C.; Dobre, M.; Dodonov, V.; Eckerlin, G.; Egli, S.; Elsen, E.; Favart, L.; Fedotov, A.; Feltesse, J.; Ferencei, J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Grebenyuk, A.; Greenshaw, T.; Grindhammer, G.; Haidt, D.; Henderson, R.C.W.; Hladký, J.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Huber, F.; Jacquet, M.; Janssen, X.; Jung, H.; Kapichine, M.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kogler, R.; Kostka, P.; Kretzschmar, J.; Krüger, K.; Landon, M.P.J.; Lange, W.; Laycock, P.; Lebedev, A.; Levonian, S.; Lipka, K.; List, B.; List, J.; Lobodzinski, B.; Malinovski, E.; Martyn, H.-U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Morozov, A.; Müller, K.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Pascaud, C.; Patel, G.D.; Perez, E.; Petrukhin, A.; Picuric, I.; Pirumov, H.; Pitzl, D.; Plačakytė, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Raicevic, N.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Rusakov, S.; Šálek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schöning, A.; Sefkow, F.; Shushkevich, S.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Straumann, U.; Sykora, T.; Thompson, P.D.; Traynor, D.; Truöl, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Valkárová, A.; Vallée, C.; Van Mechelen, P.; Vazdik, Y.; Wegener, D.; Wünsch, E.; Žáček, J.; Zhang, Z.; Žlebčík, R.; Zohrabyan, H.; Zomer, F.

    2016-01-23

    A first measurement is presented of exclusive photoproduction of $\\rho^0$ mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years $2006$ and $2007$ at a centre-of-mass energy of $\\sqrt{s}=319$ GeV and correspond to an integrated luminosity of $1.16$ pb$^{-1}$. The $\\rho^0$ mesons with transverse momenta $p_T0.35$, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality $Q^2 < 2$ GeV$^2$, the total energy of the photon-proton system $20 < W_{\\gamma p} < 100$ GeV and the polar angle of the leading neutron $\\theta_n < 0.75$ mrad. The cross section of the reaction $\\gamma p \\to \\rho^0 n \\pi^+$ is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a $\\rho^0$ meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross se...

  5. πN scattering and γN → Nπ photoproduction within the unitary improved Born approximation

    Science.gov (United States)

    Mariano, A.

    2007-07-01

    Following the programme of describing consistently several processes where the isobar Δ(1232 MeV) nucleon resonance appears as an intermediate state, in this work we propose to unitarize our old improved Born approximation already used to describe successfully π+p elastic and radiative scattering, to treat pion photoproduction. First we add the effect of final state interactions and make a new determination of the mass, width and the coupling constant to the pion-nucleon state of the Δ resonance. Then extending the model for pion photoproduction and using the resonance parameters determined previously, we are able to define effective form factors (at k2γ = 0) for the γN → Δ vertex with values GM = 2.97 ± 0.08 and GE = 0.055 ± 0.010, by fitting the data for the M3/21+ and E3/21+ multipoles. These values are fully consistent with recent chiral effective field theory calculations, and using them we can predict satisfactorily the data for other multipoles and the photoproduction cross section. Finally, we intend a model-independent determination of the bare form factors making a dynamical dressing of the vertex, getting G0M = 1.69 ± 0.02, G0E = 0.028 ± 0.008 and R0EM = -1.67 ± 0.45%, which are compared with different quark models.

  6. Inelastic photoproduction of ω and rho+-mesons

    International Nuclear Information System (INIS)

    Nelson, C.A. Jr.; May, E.N.; Abramson, J.; Andrews, D.E.; Harvey, J.; Lobkowicz, F.; Singer, M.N.; Thorndike, E.H.; Nordberg, M.E. Jr.

    1978-01-01

    We report measurements of inelastic photoproduction of ω and rho +- mesons from hydrogen and deuterium at incident photon energies in the range 7.5-10.5 GeV. For ωΔ and rho - Δ ++ production differential cross sections dsigma/dt' and spin density matrices are presented. For higher missing masses the cross sections dsigma/dM/sub X/ 2 and invariant structure functions F(x) are also given. The data are compared to a one-pion-exchange model. We conclude that pion exchange is dominant for inelastic ω photoproduction, but unimportant for rho +- during annealing, even though the resistively determined transport scattering time increased by a factor of 7.8 during annealing. Orbital depairing was found to follow a relation zeta = zeta 0 + αH 2 and to increase with annealing in a manner expected from the change in mean free path determined from measurements of H/sub cnu/

  7. Inclusive charged and neutral pion photoproduction at 20 GeV

    International Nuclear Information System (INIS)

    Rickman O'Dell, V.

    1987-05-01

    The inclusive charged and neutral pion distributions from the interactions of 20 GeV photons on protons have been measured. The assumptions and analysis done to obtain these distributions are described, and the pion distributions are found to agree with general predictions of the quark-parton model. The quark-quark fusion model and the recombination model were compared to the inclusive pion distributions assuming the photon could be approximated by a superposition of rho and omega vector meson states - an assumption prompted by the Vector Meson Dominance Model of photon structure. Quark models applied to the difference in the charged pion cross sections are examined. The inclusive charge structure of the photoproduced charged pions and that of electroproduced and hadroproduced charged pions were compared

  8. Exclusive ρ{sup 0} meson photoproduction with a leading neutron at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, V.; Belousov, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Vazdik, Y. [Lebedev Physical Institute, Moscow (Russian Federation); Baghdasaryan, A.; Zohrabyan, H. [Yerevan Physics Institute, Yerevan (Armenia); Begzsuren, K.; Ravdandorj, T. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (Mongolia); Bolz, A.; Huber, F.; Radescu, V.; Sauter, M.; Schoening, A. [Universitaet Heidelberg, Physikalisches Institut, Heidelberg (Germany); Boudry, V.; Specka, A. [LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau (France); Brandt, G. [Universitaet Goettingen, II. Physikalisches Institut, Goettingen (Germany); Brisson, V.; Jacquet, M.; Pascaud, C.; Zhang, Z.; Zomer, F. [LAL, Universite Paris-Sud, CNRS/IN2P3, Orsay (France); Britzger, D.; Campbell, A.J.; Dodonov, V.; Eckerlin, G.; Elsen, E.; Fleischer, M.; Gayler, J.; Ghazaryan, S.; Haidt, D.; Kleinwort, C.; Krueger, K.; Levonian, S.; Lipka, K.; List, B.; List, J.; Meyer, A.B.; Meyer, J.; Niebuhr, C.; Olsson, J.E.; Ozerov, D.; Pirumov, H.; Pitzl, D.; Placakyte, R.; Schmitt, S.; Sefkow, F.; Shushkevich, S.; South, D.; Steder, M.; Wuensch, E. [DESY, Hamburg (Germany); Buniatyan, A.; Newman, P.R.; Thompson, P.D. [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Bylinkin, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Moscow Institute of Physics and Technology, Moscow (Russian Federation); Bystritskaya, L.; Fedotov, A. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Cantun Avila, K.B.; Contreras, J.G. [CINVESTAV, Departamento de Fisica Aplicada, Merida, Yucatan (Mexico); Cerny, K.; Pokorny, B.; Salek, D.; Valkarova, A.; Zacek, J.; Zlebcik, R. [Charles University, Faculty of Mathematics and Physics, Prague (Czech Republic); Chekelian, V.; Grindhammer, G.; Kiesling, C.; Lobodzinski, B. [Max-Planck-Institut fuer Physik, Munich (Germany); Cvach, J.; Hladka, J.; Reimer, P. [Academy of Sciences of the Czech Republic, Institute of Physics, Prague (Czech Republic); Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kostka, P.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D. [University of Liverpool, Department of Physics, Liverpool (United Kingdom); Daum, K. [Fachbereich C, Universitaet Wuppertal, Wuppertal (Germany); Universitaet Wuppertal, Rechenzentrum, Wuppertal (Germany); Diaconu, C.; Hoffmann, D.; Vallee, C. [Aix Marseille Universite, CNRS/IN2P3, CPPM UMR 7346, Marseille (France); Dobre, M.; Rotaru, M. [Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering (IFIN-HH), Bucharest (Romania); Egli, S.; Horisberger, R. [Paul Scherrer Institut, Villigen (Switzerland); Favart, L.; Grebenyuk, A.; Hreus, T.; Janssen, X.; Roosen, R.; Van Mechelen, P. [Inter-University Institute for High Energies ULB-VUB, Brussels and Universiteit Antwerpen, Antwerp (Belgium); Feltesse, J.; Schoeffel, L. [Irfu/SPP, CE Saclay, Gif-sur-Yvette Cedex (France); Ferencei, J. [Slovak Academy of Sciences, Institute of Experimental Physics, Kosice (Slovakia); Goerlich, L.; Mikocki, S.; Nowak, G.; Sopicki, P.; Turnau, J. [Institute of Nuclear Physics Polish Academy of Sciences, Krakow (Poland); Gouzevitch, M.; Petrukhin, A. [IPNL, Universite Claude Bernard Lyon 1, CNRS/IN2P3, Villeurbanne (France); Grab, C. [Institut fuer Teilchenphysik, ETH, Zurich (Switzerland); Henderson, R.C.W. [University of Lancaster, Department of Physics, Lancaster (United Kingdom); Jung, H. [Inter-University Institute for High Energies ULB-VUB, Brussels and Universiteit Antwerpen, Antwerp (Belgium); DESY, Hamburg (Germany); Kapichine, M.; Morozov, A.; Spaskov, V. [Joint Institute for Nuclear Research, Dubna (RU); Kogler, R. [Universitaet Hamburg, Institut fuer Experimentalphysik, Hamburg (DE); Landon, M.P.J.; Rizvi, E.; Traynor, D. [Queen Mary, University of London, School of Physics and Astronomy, London (GB); Lange, W.; Naumann, T. [DESY, Zeuthen (DE); Martyn, H.U. [I. Physikalisches Institut der RWTH, Aachen (DE); Meyer, H. [Fachbereich C, Universitaet Wuppertal, Wuppertal (DE); Mueller, K.; Robmann, P.; Straumann, U.; Truoel, P. [Physik-Institut der Universitaet Zuerich, Zurich (CH); Perez, E. [CERN, Geneva (CH); Picuric, I.; Raicevic, N. [University of Montenegro, Faculty of Science, Podgorica (ME); Polifka, R. [Charles University, Faculty of Mathematics and Physics, Prague (CZ); University of Toronto, Department of Physics, Toronto, ON (CA); Povh, B. [Max-Planck-Institut fuer Kernphysik, Heidelberg (DE); Rostovtsev, A. [Institute for Information Transmission Problems RAS, Moscow (RU); Sankey, D.P.C. [STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire (GB); Sauvan, E. [Aix Marseille Universite, CNRS/IN2P3, CPPM UMR 7346, Marseille (FR); Universite de Savoie, CNRS/IN2P3, LAPP, Annecy-le-Vieux (FR); Soloviev, Y. [DESY, Hamburg (DE); Lebedev Physical Institute, Moscow (RU); Stella, B. [Universita di Roma Tre, Dipartimento di Fisica, Rome (IT); INFN Roma 3 (IT); Sykora, T. [Inter-University Institute for High Energies ULB-VUB, Brussels and Universiteit Antwerpen, Antwerp (BE); Charles University, Faculty of Mathematics and Physics, Prague (CZ); Tsakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (BG); Tseepeldorj, B. [Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar (MN); Ulaanbaatar University, Ulaanbaatar (MN); Wegener, D. [TU Dortmund, Institut fuer Physik, Dortmund (DE); Collaboration: H1 Collaboration

    2016-01-15

    A first measurement is presented of exclusive photoproduction of ρ{sup 0} mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of √(s) = 319 GeV and correspond to an integrated luminosity of 1.16 pb{sup -1}. The ρ{sup 0} mesons with transverse momenta p{sub T} < 1 GeV are reconstructed from their decays to charged pions, while leading neutrons carrying a large fraction of the incoming proton momentum, x{sub L} > 0.35, are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality Q{sup 2} < 2 GeV{sup 2}, the total energy of the photon.proton system 20 < W{sub γp} < 100 GeV and the polar angle of the leading neutron θ{sub n} < 0.75 mrad. The cross section of the reaction γp → ρ{sup 0}nπ{sup +} is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a ρ{sup 0} meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, σ{sup el}(γπ{sup +} → ρ{sup 0}π{sup +}), is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction γp → ρ{sup 0}nπ{sup +}. (orig.)

  9. Scale of corrections to the t-pole approximation in the quasielastic knockout of pions from nucleon by high energy electrons

    CERN Document Server

    Neudachin, V G; Yudin, N P

    2002-01-01

    Investigation of the dominant role of the simplest t-pole diagrams is completed in the processes of pion electroproduction on nucleons at quasielastic knock out kinematics and electron energies of a few GeV. Competition role of pi- and rho-meson t-pole diagrams and s-pole diagram (tree diagram) is regarded. When virtual photon mass is large enough (Q sup 2 >= 2 (GeV/c) sup 2), the latter amplitude is not essential both for longitudinal (d sigma sub L /dt) and for transverse (d sigma sub T /dt) cross sections. At Q sup 2 = 0.7 (GeV/c) sup 2 in the longitudinal cross section the interference term between pion t-pole and s-pole amplitudes is still essential. Vertex functions g subrho sub N sub N (t), obtained from the cross sections of the quasielastic knockout of rho mesons and from cross section of pion photoproduction, are compared. Their discrepancy must give impulse to the development of gauge invariant theory of pion photoproduction

  10. Pion photoproduction cross section at large momentum transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sjoegren, Johan [Univ. of Glasgow, Scotland, United Kingdom

    2015-02-27

    The Real Compton Scattering experiment was performed in Hall A at the Thomas Jefferson National Accelerator Facility. It was designed to measure, for Compton scattering and π0-photoproduction, the differential cross section over a range of kinematic points and the polarisation transfer to the proton at a single kinematic point. The full range of the experiment in Mandelstam variables t and s was 1.6-6.46 GeV2 and 4.82-10.92 GeV2 respectively with beam energies of 2-6 GeV. The motivation for the experiment is to test the cross section and polarisation transfer predictions of perturbative QCD versus that of predictions from Generalised Parton Distribution models. This thesis will give an overview of the pertinent theory, experimental setup in Hall A and the extracting of the π0-photoproduction cross section.

  11. Measurement of elastic ω photoproduction at HERA

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1996-08-01

    The reaction γp→ωp (ω→π + π - π 0 and π 0 →γγ) has been studied in ep interactions using the ZEUS detector at photon-proton centre-of-mass energies between 70 and 90 GeV and vertical stroke t vertical stroke 2 , where t is the squared four momentum transferred at the proton vertex. The elastic ω photoproduction cross section has been measured to be σ γp→ωp =1.21±0.12±0.23 μb. The differential cross section dσ γp→ωp /d vertical stroke t vertical stroke has an exponential shape e -b vertical stroke t vertical stroke with a slope b=10.0±1.2±1.3 GeV -2 . The angular distributions of the decay pions are consistent with s-channel helicity conservation. When compared to low energy data, the features of ω photoproduction as measured at HERA energies are in agreement with those of a soft diffractive process. Previous measurements of the ρ 0 and φ photoproduction cross sections at HERA show a similar behaviour. (orig.)

  12. Strange Twists in Neutral Pion Photo/Electro-Production

    OpenAIRE

    Meißner, Ulf-G.

    1995-01-01

    I review the interesting tale of the electric dipole amplitude in neutral pion photoproduction and the resulting consequences. I also discuss why there is new life related to P--wave multipoles. Electroproduction is briefly touched upon.

  13. Photoproduction in the Energy Range 70-200 GeV

    CERN Multimedia

    2002-01-01

    This experiment continues the photoproduction studies of WA4 and WA57 up to the higher energies made available by the upgrading of the West Hall. An electron beam of energy 200 GeV is used to produce tagged photons in the range 65-180 GeV; The photon beam is incident on a 60 cm liquid hydrogen target in the Omega Spectrometer. A Ring Image Cherenkov detector provides pion/kaon separation up to 150 GeV/c. The Transition Radiation Detector extends the charged pion identification to the momentum range from about 80 GeV/c upwards. The large lead/liquid scintillator calorimeter built by the WA70 collaboration and the new lead/scintillating fibre det (Plug) are used for the detection of the $\\gamma$ rays produced by the interactions of the primary photons in the hydrogen target. \\\\ \\\\ The aim is to make a survey of photoproduction reactions up to photon energies of 200 GeV. The large aperture of the Omega Spectrometer will particularly enable study of fragmentation of the photon to states of high mass, up to @C 9 G...

  14. ϕ-meson photoproduction on hydrogen in the neutral decay mode

    Science.gov (United States)

    Seraydaryan, H.; Amaryan, M. J.; Gavalian, G.; Baghdasaryan, H.; Weinstein, L.; Adhikari, K. P.; Adikaram, D.; Aghasyan, M.; Anderson, M. D.; Pereira, S. Anefalos; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Collins, P.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dugger, M.; Dupre, R.; Fassi, L. El; Eugenio, P.; Fedotov, G.; Fegan, S.; Fersch, R.; Fleming, J. A.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, A.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, A.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lewis, S.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Martinez, D.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Moutarde, H.; Munevar, E.; Camacho, C. Munoz; Nadel-Turonski, P.; Nasseripour, R.; Niccolai, S.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Protopopescu, D.; Puckett, A. J. R.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rizzo, A.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Ungaro, M.; Vineyard, M. F.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; CLAS Collaboration

    2014-05-01

    We report the first measurement of the photoproduction cross section of the ϕ meson in its neutral decay mode in the reaction γp →pϕ(KSKL). The experiment was performed with a tagged photon beam of energy 1.6≤Eγ≤3.6 GeV incident on a liquid hydrogen target of the CLAS spectrometer at the Thomas Jefferson National Accelerator Facility. The pϕ final state is identified via reconstruction of KS in the invariant mass of two oppositely charged pions and by requiring the missing particle in the reaction γp →pKSX to be KL. The presented results significantly enlarge the existing data on ϕ photoproduction. These data, combined with the data from the charged decay mode, will help to constrain different mechanisms of ϕ photoproduction.

  15. Fast pion production in exclusive neutrino processes

    International Nuclear Information System (INIS)

    Gershtein, S.S.; Komachenko, Yu.Ya.; Khlopov, M.Yu.

    1980-01-01

    Single pion production in exclusive neutrino reactions with small momentum transfer to nucleon, induced by neutrino scattering on virtual mesons (reggeons), is considered. The estimation of the contributions to process νA → μπA where A is a nucleon or the target nucleus made by various virtual mesons is presented. In the experimental investigation of such processes the contributions of different mesons may be singled out, thus providing information on the weak; meson-pion (reggeon-pion) transitions

  16. Measurement of dijet photoproduction for events with a leading neutron at HERA

    International Nuclear Information System (INIS)

    Chekanov, S.; Derrick, M.; Magill, B.

    2009-09-01

    Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e + +p→e + +jet+jet+X(+n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb -1 . The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, x L , and of its transverse momentum squared, p T 2 . The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of x L was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects. (orig)

  17. SAID analysis of meson photoproduction: Determination of neutron and proton EM couplings

    Directory of Open Access Journals (Sweden)

    Strakovsky Igor

    2014-06-01

    Full Text Available We present an overview of the GW SAID group effort to analyze on new pion photoproduction on both proton- and neutron-targets. The main database contribution came from the recent CLAS and MAMI unpolarized and polarized measurements. The differential cross section for the processes γn → π−p was extracted from new measurements accounting for Fermi motion effects in the impulse approximation (IA as well as NN- and πN effects beyond the IA. The electromagnetic coupling results are compared to other recent studies.

  18. Interaction of slow pions with atomic nuclei

    International Nuclear Information System (INIS)

    Troitskij, M.A.; Tsybul'nikov, A.V.; Chekunaev, N.I.

    1984-01-01

    Interactions of slow pions with atomic nuclei near to pion condensation are investigated. From comparison of experimental data with the theoretical calculation results on the basis of precise microscopic approach not bound with the random phase approximation (RPA) nuclear matter fundamental parameters near a critical point can be found. Optical potential of slow pions in nuclei, πN-scattering amplitudes and lengths, π-atom level isotopic shift, phenomenon of single-nucleon pion absorption by nucleus, phenomenon of nuclear critical opalescence are considered. The results of πN-scattering lengths calculation, sup(40-44)Ca, sup(24-29)Mg, sup(16-18)O π-atom level shift are presented. It is shown that the presence of π-condensate in nuclei can explain the observed suppression of p-wave potential terms. The phenomenon of single-nucleon pion absorption by nucleus is one of direct experiments which permits to reveal the π-condensate. The nuclear opalescence phenomenon is manifested in increase of pion photoproduction reaction cross section for account of nucleus proximity to π-condensation as compared with the calculated in the Fermi-gas model. The suggested method for calculating precondensate phenomena operates the better, the nearer is the system to the condensation threshold whereas the RPA method in this region is inapplicable

  19. Measurement of the helium-3 Panofsky ratio and of π+ photoproduction near the threshold for deuterium and helium-3

    International Nuclear Information System (INIS)

    Botton, Nico de.

    1979-01-01

    Photoproduction measurements near the threshold are described for two and three-nucleon systems. The experimental techniques used gave the photoproduction cross section value with a precision of a few percent. This accuracy is essential when observing the contribution of multi-nucleon effects which represents a correction to the dominant contribution foreseen by the operator of one-body photoproduction. The method of relative measurement with respect to the elementary process of photoproduction on the proton gives a direct comparison of the experimental result with the momentum approximation at the +-1.5% precision level. No coherent description of multi-nucleon contributions, the overall effect of which should be relatively small in view of the above observation, exists at present. Only the part of these contributions corresponding to the rescattering of the pion has been estimated using a simple model of multiple scattering by fixed nucleons, but more detailed calculations would be needed to confirm these results. The other exchange current terms would also have to be evaluated in order to situate the interpretation of photoproduction results at the same level as that of electron scattering data [fr

  20. Helicity Asymmetry Measurement for π0 Photoproduction with FROST

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, Hideko [George Washington Univ., Washington, DC (United States)

    2011-08-15

    This thesis reports on the first helicity asymmetry measurement for single neutral pion photoproduction using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This measurement used longitudinally polarized protons and circularly polarized photons at energies between 350 MeV and 2400 MeV. The experimental results are compared to three available model calculations.

  1. Helicity Asymmetry Measurement for pi0 Photoproduction with FROST

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, Hideko [George Washington Univ., Washington, DC (United States)

    2011-08-15

    This thesis reports on the first helicity asymmetry measurement for single neutral pion photoproduction using the CLAS detector in Hall B at the Thomas Jefferson National Accelerator Facility (JLab). This measurement used longitudinally polarized protons and circularly polarized photons at energies between 350 MeV and 2400 MeV. The experimental results are compared to three available model calculations.

  2. Measurement of coherent π0 photoproduction on 3He and 3H in the resonance region

    International Nuclear Information System (INIS)

    Bellinghausen, B.; Gassen, H.J.; Reese, E.; Reichelt, T.; Stipp, P.

    1984-01-01

    Neutral pion photoproduction has been measured on 3 He and 3 H nuclei in the Δ(1,232) resonance region. Resonance averaged cross-sections are presented as a function of momentum transfer and compared to theoretical calculations. (orig.)

  3. Measurement of dijet photoproduction for events with a leading neutron at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, B. [Argonne National Lab., Argonne, IL (US)] (and others)

    2009-09-15

    Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e{sup +}+p{yields}e{sup +}+jet+jet+X(+n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb{sup -1}. The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, x{sub L}, and of its transverse momentum squared, p{sub T}{sup 2}. The dijet data are compared to inclusive DIS and photoproduction results; they are all consistent with a simple pion-exchange model. The neutron yield as a function of x{sub L} was found to depend only on the fraction of the proton beam energy going into the forward region, independent of the hard process. No firm conclusion can be drawn on the presence of rescattering effects. (orig)

  4. Study ω and φ photoproduction in the nucleon isotopic channels

    International Nuclear Information System (INIS)

    Zhao, Q.

    2002-01-01

    We present results for the photoproduction of ω and φ meson in the nucleon isotopic channels. A recently developed quark model with an effective Lagrangian is employed to account for the non-diffractive s- and u-channel processes; the diffractive feature arising from the natural parity exchange is accounted for by the t-channel pomeron exchange, while the unnatural parity exchange is accounted for by the t-channel pion exchange. In the ω production, the isotopic effects could provide more information concerning the search of 'missing resonances', while in the φ production, the isotopic effects could highlight non-diffractive resonance excitation mechanisms at large angles. (author)

  5. Processes involved in pion capture in hydrogen-containing molecules

    International Nuclear Information System (INIS)

    Horvath, D.

    1983-03-01

    A systematic analysis is presented of the possible elementary processes determining the fate of negative pions stopped in hydrogen-containing samples. Using a phenomenological description in comparison with the available experimental information on pion capture in hydrogen, it is shown that the formation and decay of pπ - atoms in compounds Zsub(m)Hsub(n) are determined mainly by the processes of Auger capture in a molecular orbit ZHπ - , transition from molecular to atomic orbit, transfer of pions to atoms Z in collisions pπ - +Z, and nuclear capture in collisions pπ - +H. The recent assumption of a considerable role of the processes of radiative atomic capture in bound hydrogen atoms, nuclear capture of pions by protons from the molecular state ZHπ - , or 'inner' transfer of the pion via tunnelling through the bond Z-H is not supported by the theory and contradicts the experimental data

  6. Radiation-accompanied pion photoproduction on the proton

    International Nuclear Information System (INIS)

    Rost, M.

    2004-01-01

    In the year 1997, Tatischeff et al. found resonance-like states in the invariant mass spectrum of the missing particle X at M=1004, 1044 and 1094 MeV, utilizing the reaction pp→Xpπ + . Investigating the reaction pd→ppX, resonance structures have been observed at M=966, 986 and 1003 MeV in a further experiment by Filkov et al. Such kinds of exotic states contradict various nucleon models which describe the Δ(1232) resonance as the first excited state. Instead, quark cluster models with and without color-magnetic interactions have been formulated to explain these resonance structures. Lvov et al. argued that no such structure had been reported in real Compton scattering data. As a counter argument, Kobushkin suggested that these resonances have a total anti-symmetric spin-flavour wave function and therefore only the N-2γ decay channel is allowed. In this work, the reaction γp→X 0 π + →nγγπ + is utilized for the search of these exotic resonances. Data were taken in parallel with the pion polarizability experiment at the MAMI accelerator facility in Mainz. Real photons are created by the bremsstrahlung process of the electrons in a thin radiator foil. Their energy is determined by the A2 photon tagging facility (Glasgow tagger). A 10 cm long liquid hydrogen target was used as a proton target. Charged reaction products are detected in a multi wire proportional chamber in forward direction, at theta 2 crystals containing TAPS spectrometer at polar angles of theta >60 . For neutron detection, a time of flight detector with 111 single modules was used. Additionally, the reaction channels γp→pπ 0 and γp→nπ 0 π + are analysed to test the apparatuses. For single pion production, differential cross sections are obtained and compared with theoretical models as well as experimental data. For the γp→nπ 0 π + channel, invariant mass spectra of particles in the final state are determined and compared with simulation. The data indicate that the main

  7. Polarisation observables F and T in double π{sup 0} photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Garni, Stefanie [Departement of Physics, University of Basel, CH-4056 Basel (Switzerland); Collaboration: A2-Collaboration

    2013-07-01

    The measurement of single and double polarization observables gives information about the different resonance contributions to the cross section and hence leads to a better understanding of the nucleon and it's excited states. Double π{sup 0} photo-production is a very interesting reaction for the investigation of nuclear resonances. Photo-production of pion pairs allows to study states which decay preferentially via intermediate resonances. The double neutral channel has the additional advantage of only small non-resonant background contributions. Double π{sup 0}-photo-production off a transversally polarized H-butanol target has been measured using circularly polarized bremsstrahlung photons produced by MAMI-C with incident energies up to 1.5 GeV. The double π{sup 0} reaction was identified using a combined setup of the Crystal Ball colorimeter and a TAPS forward wall which results in an almost 4π acceptance. Preliminary results on the single polarization observable T and double polarization observable F are presented.

  8. Pion-pion interactions in particle physics

    Energy Technology Data Exchange (ETDEWEB)

    Martin, B R; Morgan, D; Shaw, G

    1976-01-01

    The aim of the book is to review the experimental and theoretical work on the processes involving pion-pion interactions. Sources of information on pion-pion scattering are examined, including pion production, dipion exchange, and weak and electromagnetic interactions. The theory and models of pion-pion scattering are discussed with reference to fixed momentum transfer, partial wave amplitudes, models and phenomenology, dynamical and field theoretic models, finite-energy sum rules, duality and the Veneziano model, resonance spectra and lastly, predictions from current algebra.

  9. Meson Spectroscopy in Photo-production at CLAS

    OpenAIRE

    Nozar, Mina

    2003-01-01

    Photo-production of excited mesons in the 1-2 GeV mass range decaying via multi-pion or multi-kaon emission has been investigated at the TJNAF\\thanks{This work was supported by the U.S. Department of Energy and The U.S. National Science Foundation.} experiment E01-017 (g6c) in the $4.8-5.4$ GeV photon beam energy range. The main objective of the experiment is to extract resonance parameters of the produced states by way of a Partial Wave Analysis (PWA) technique. In this paper, we will focus ...

  10. Exclusive ρ.sup.0./sup. meson photoproduction with a leading neutron at HERA

    Czech Academy of Sciences Publication Activity Database

    Andreev, V.; Baghdasaryan, A.; Begzsuren, K.; Cvach, Jaroslav; Hladký, Jan; Reimer, Petr

    2016-01-01

    Roč. 76, č. 1 (2016), 1-21, č. článku 41. ISSN 1434-6044 R&D Projects: GA MŠk LG14033 Institutional support: RVO:68378271 Keywords : deep-inelastic scattering * vector meson production * pion exchange model * elastic photoproduction Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.331, year: 2016

  11. Study on Charged Top-Pion Decay Processes

    Institute of Scientific and Technical Information of China (English)

    WANG Xue-Lei; XU Wen-Na; DU Lin-Lin

    2004-01-01

    In the framework of top-color assisted technicolor (TC2) theory, we study the four decay processes of charged top-pion, i.e., П+t → t-b, П+t → c-b, П+t → W+γ П+t → W+ Z0. The decay branching ratio of these modes are calculated. The results show that the main decay channels of charged top-pion are the tree level modes: П+t → t-b and П+t → c-b. Light П+t is easier to be detected than heavy one at future coliders. So, the study provides us with some useful informations to search for charged top-pion.

  12. Measurement of inverse pion photoproduction at energies spanning the N(1440) resonance

    International Nuclear Information System (INIS)

    Shafi, A.; Strakovsky, I.I.; Briscoe, W.J.; Arndt, R.A.; Bennhold, C.; Workman, R.L.; Prakhov, S.; Nefkens, B.M.K.; Clajus, M.; Marusic, A.; McDonald, S.; Phaisangittisakul, N.; Price, J.W.; Tippens, W.B.; Allgower, C.E.; Spinka, H.; Bekrenev, V.; Kulbardis, A.; Kozlenko, N.; Kruglov, S.

    2004-01-01

    Differential cross sections for the process π - p→γn have been measured at Brookhaven National Laboratory's Alternating Gradient Synchrotron with the Crystal Ball multiphoton spectrometer. Measurements were made at 18 pion momenta from 238 to 748 MeV/c, corresponding to E γ for the inverse reaction from 285 to 769 MeV. The data have been used to evaluate the γn multipoles in the vicinity of the N(1440) resonance. We compare our data and multipoles to previous determinations

  13. F observable in double π{sup 0}-photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Garni, Stefanie [Department of Physics, University of Basel, CH-4056 Basel (Switzerland); Collaboration: A2-Collaboration

    2014-07-01

    The measurement of single and double polarization observables gives information about the different resonance contributions in the cross section and hence leads to a better understanding of the nucleon and its excited states. The double π{sup 0}-photoproduction is one of the most interesting reaction for the measurement of these observables. It allows to search for excited nucleon states which decay preferentially via cascades involving intermediate excited states. Furthermore, the background from non-resonant terms is small since the photon does not couple directly to neutral pions. Double π{sup 0}-photoproduction off a transversally polarized H-Butanol target has been measured using circularly polarized bremsstrahlung photons produced by MAMI-C with incident energies up to 1.5 GeV. The double π{sup 0} reaction was identified using a combined setup of the Crystal Ball colorimeter and a TAPS forward wall which results in an almost 4π acceptance. Preliminary results on the single polarization observable T and double polarization observable F are presented.

  14. Exclusive Meson Photoproduction off Bound Nucleons

    Science.gov (United States)

    Strakovsky, Igor; Briscoe, William

    2017-09-01

    An overview of the GW SAID group effort to analyze pion photoproduction on the neutron-target will be given. The disentangling of the isoscalar and isovector EM couplings of N * and Δ * resonances does require compatible data on both proton and neutron targets. The final-state interactions play a critical role in the state-of-the-art analysis in extraction of the γn -> π N data from the deuteron target experiments. Then resonance couplings determined by the SAID PWA technique are compared to previous findings. The neutron program is an important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH studies. DOE Research Grant DE``SC0016583.

  15. Recent results in photoproduction with real and virtual photons

    International Nuclear Information System (INIS)

    Diekmann, B.

    1984-10-01

    An overview of recent experimental results on soft photon-hadron-interactions is given. It contains results on inclusive photoproduction of rho and ω-mesons, hyperons and the totally inclusive reaction: γp -> Xp. Results on the search for radially excited vectormesons and on the determination of the radiative width of the rho- meson are updated. An improved measurement of the pion form factor and a test of Vector-Meson-Dominance in case of virtual photons (vertical strokeq 2 vertical stroke 2 ) will be presented. (orig.)

  16. Application of a Regge model to the photoproduction of pion pairs

    Energy Technology Data Exchange (ETDEWEB)

    Bolz, Arthur; Sauter, Michel; Schoening, Andre [Physikalisches Institut, Universitaet Heidelberg, Im Neuenheimer Feld 226, D-69120 Heidelberg (Germany); Ewerz, Carlo [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany); ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fuer Schwerionenforschung, Planckstrasse 1, D-64291 Darmstadt (Germany); Maniatis, Markos [Departamento de Ciencias Basicas, Universidad del Bio-Bio, Avda. Andres Bello s/n, Casilla 447, Chillan 3780000 (Chile); Nachtmann, Otto [Institut fuer Theoretische Physik, Universitaet Heidelberg, Philosophenweg 16, D-69120 Heidelberg (Germany)

    2015-07-01

    In a recent publication (arXiv:1409.8483) a model in the spirit of Regge theory is used to describe the reaction γp → π{sup +}π{sup -} p at high energies. Both resonant pion-pion production via the meson resonances ρ(770), ω(782), ρ(1450) and f{sub 2}(1270) as well as non-resonant amplitudes are considered. Photon and proton interact by the exchange of the photon, the pomeron and reggeons as well as by a yet unobserved but possible odderon. Cross sections calculated from this model and their dependencies on various kinematic quantities are discussed and compared to experimental data. The focus is on angular distributions which feature asymmetries that could be used for an odderon discovery.

  17. Role of delta excitations in pion-, photon- and nucleon-nucleus reactions studied with microscopic models

    International Nuclear Information System (INIS)

    Engel, A.

    1995-01-01

    Delta excitation plays a prominent role in intermediate heavy reactions. In this paper, comment is made on the calculations done for pion-, photon- and nucleon-nucleus reactions using the Boltzmann-Uehling-Uhlenbeck (BUU) model and the antisymmetrized molecular dynamics (AMD) model. First, it is recalled how to include delta degrees in microscopic models in general. Then, the comparison of the microscopic calculation performed by the author with the experimental data is presented. Deltas in microscopic models are discussed. Pion-nucleus reactions have been studied since pion beams became available, especially for exploring the delta resonance in a nuclear medium. The dependence of pion absorption cross section on incident pion energy is shown. The photon-induced pion production in the resonance energy region was studied with the BUU model. The calculated results of neutral pion photo-production are shown. In both inelastic proton scattering and (p,n) charge exchange reaction, the excitation of delta resonance can be observed clearly in the experimental data. The results of the AMD calculation for 12 C(p,p') reaction are shown. (K.I.)

  18. Photoproduction de Mesons sur le Nucleon aux Energies Intermediaire (in French) [Photoproduction of mesons on the nucleon at intermediate energies

    Energy Technology Data Exchange (ETDEWEB)

    Guidal, Michel [Univ. of Paris, Orsay (France)

    1996-12-13

    One object of this thesis is to propose a model taking account of low transfer reaction mechanisms for a series of photoproduction reactions on nucleons for photon energies ≳4 GeV. If our comprehension of processes with low transfers is correct, then extrapolating our model in the domain of large transfers and the comparison with data supplied will give us information on the domains in energy and transfers from which an interpretation of reactions in terms of the "soft" process ceases to be valid. In the domain of large transfers, only one approach in terms of "hard" process can then explain the data. We are interested in electromagnetic photoproduction reactions because the probe, firstly, interacts with the target via an exact and well known mechanism (described by the QED theory) and also eliminates the interaction phenomena in the initial state. No probe is as well known as the photon. The extraction of reaction mechanisms, amplitudes and coupling constants match is made easier than in the case of hadronic probes. The energy domain Eγ >4 GeV studied is particularly interesting because it is from this energy of incident photons that can be expected to achieve large enough pulse transfers to hope for emergence of hard processes and therefore see the cessation of validity of interpretation of hadron models. Also, resonance effects are minor and do not interfere with our interpretations. Experimentally, this area is widely unexplored and the new generation accelerators of a large duty cycle (CEBAF, MAMI, ESRF, ELF, ...) combined with 4π detectors will allow to precisely measure low cross sections reactions of a large transfer. We first study pion photoproduction reactions on nucleon because they are the most experimentally accessible reactions and many data of high energy and low transfers exist. This will require strong constraints on the model parameters of the numerous analyses performed previously. Then we'll move on to kaon photoproduction

  19. Pion, pion-pion, and pion-nucleus interactions

    CERN Document Server

    Mukhin, K N; Tikhonov, V N

    2002-01-01

    This survey is devoted to describing the early studies of 1.1. Gurevich on pion physics that were performed by the photoemulsion method and the studies of the pion-pion interaction that were made by his colleagues on the basis of the hydrogen-bubble-chamber and the magnetic-spectrometer method (as well-as on the basis of the photoemulsion method). Two approaches-an extrapolation of experimental data from the physical region to the pion pole and a theoretical calculation based on the Roy integral equations-are used to deduce information about the pion-pion interaction. The first results obtained for pion-pion and pion-nucleus interactions in the experiments that are being currently performed in Brookhaven and at CERN ( pi pi interaction) and at TRIUMF (Canada) and in Brookhaven (pion-nucleus interaction) are presented, along with the existing theoretical concepts in these realms of physics. (80 refs).

  20. Off-shell effects in the coherent π0 photoproduction off nuclei

    International Nuclear Information System (INIS)

    Chumbalov, A.A.; Kamalov, S.S.

    1987-01-01

    A strong sensitivity of coherent π 0 -meson photoproduction on nuclei to different ω reaction energy change in elementary amplitude t πγ (ω) is demonstrated. Various assumptions concerning ω behaviour in the extraenergy area can change differential cross sections 1.5-2 times. The best agreement of the DWIA-results with experimental data is obtained at ω being equal to its own value of pion-nucleon system free relativistic Hamiltonian. Such a result agrees with relativistic potential theory effects

  1. Separation of minimum and higher twist in the photoproduction of mesons with large transverse momenta

    International Nuclear Information System (INIS)

    Hoeger, K.C.

    1990-10-01

    Higher-twist effects in point-like photon interactions on hydrogen have been studied in xF-distributions of charged particles for -0.2 2.0 GeV/c. Data were taken with a tagged photon beam with energies between 70 and 170 GeV and a pion/kaon beam at fixed energies of 80 and 140 GeV using the same setup of detectors at the CERN-Ω-spectrometer (WA69 experiment). The pion and kaon interactions were used to obtain an estimate of the hadron-like photon component. A first estimation of Higher-Twist cross sections in photoproduction of mesons at high pT has been obtained that is consistent with QCD-expectations. (orig.) [de

  2. Photoproduction of positive pions from polarized protons in the region of the first resonance

    Energy Technology Data Exchange (ETDEWEB)

    Get' man, V.A.; Gorbenko, V.G.; Derkach, A.Y.; Zhebrovskii, Y.V.; Karnaukhov, I.M.; Kolesnikov, L.Y.; Kuz' menko, V.S.; Lukhanin, A.A.; Ranyuk, Y.N.; Rubashkin, A.L.; Sanin, V.M.; Sorokin, P.V.; Sporov, E.A.; Telegin, Y.N.; Shalatskii, S.V.; Grushin, V.F.

    1980-04-01

    A technique for measuring the T asymmetry for the process ..gamma..p ..-->.. n..pi../sup +/ using a polarized proton target and a quasimonochromatic beam of photons is described. The results of measuring T in the range of pion-emission angles theta(/sub ..pi../ = 3 to 150/sup 0/ at a photon energy of 340 MeV are presented and discussed. It is shown that the results obtained allow a more reliable selection of the solutions of the energy-independent multipole analysis.

  3. Pseudoscalar meson photoproduction. Two {pi}{sup o} production on proton at GRAAL; Photoproduction de mesons pseudoscalaires. Production de deux {pi}{sup o} sur le proton a GRAAL

    Energy Technology Data Exchange (ETDEWEB)

    Guinault, Emmanuelle [Institut National de Physique Nucleaire et de Physique des Particules (India2P3), 75 - Paris (France)

    1997-09-30

    The GRAAL experiment is located at the ESRF synchrotron in Grenoble. It consists of a detection system with a large angle and a gamma beam obtained by Compton backscattering of a laser beam on the electrons of the ESRF`s storage ring. This experimental setup is devoted to the study of pseudoscalar meson photoproduction between 600 MeV and 1100 MeV. The optical setup used for the Compton backscattering is described. Beam polarization is an important parameter and two systems have been developed to analyse the polarization state of the laser beam. Preliminary measurements have been performed on the two neutral pions channel and beam asymmetry observable {Sigma} have been obtained. Invariant mass distributions of the systems (p, {pi}{sup o}) and ({pi}, {pi}) have also been calculated. Moreover, a simulation of strangeness photoproduction has been done. It shows that it is possible to study it with the GRAAL detector and a gamma beam of a larger energy. (author) 71 refs., 83 figs., 11 tabs.

  4. Leading neutron energy and pT distributions in deep inelastic scattering and photoproduction at HERA

    International Nuclear Information System (INIS)

    Chekanov, S.; Derrick, M.; Magill, S.

    2007-02-01

    The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and p T 2 distributions were measured with a forward neutron calorimeter and tracker in a 40 pb -1 sample of inclusive deep inelastic scattering (DIS) data and a 6 pb -1 sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper p T 2 distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. (orig.)

  5. Inelastic J/ψphotoproduction

    International Nuclear Information System (INIS)

    Kraemer, M.; Steegborn, J.; Zerwas, P.M.

    1994-11-01

    Inelastic photoproduction of J/ψ particles at high energies is one of the processes to determine the gluon distribution in the nucleon. We have calculated the QCD radiative corrections to the color-singlet model of this reaction. They are large at moderate photon energies, but decrease with increasing energies. The cross section and the J/ψ energy spectrum are compared with the available fixed-target photoproduction data and predictions are given for the HERA energy range. (orig.)

  6. Transverse polarization of Σ+(1189) in photoproduction on a hydrogen target in CLAS

    Science.gov (United States)

    Nepali, C. S.; Amaryan, M.; Adhikari, K. P.; Aghasyan, M.; Anefalos Pereira, S.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Charles, G.; Cole, P. L.; Collins, P.; Contalbrigo, M.; Crede, V.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; Alaoui, A. El; Fassi, L. El; Fedotov, G.; Fegan, S.; Fersch, R.; Fleming, J. A.; Gabrielyan, M. Y.; Gevorgyan, N.; Giovanetti, K. L.; Girod, F. X.; Glazier, D. I.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guler, N.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Heddle, D.; Hicks, K.; Ho, D.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Keller, D.; Khandaker, M.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Kvaltine, N. D.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Pappalardo, L. L.; Paremuzyan, R.; Park, K.; Park, S.; Pasyuk, E.; Phelps, E.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Puckett, A. J. R.; Raue, B. A.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tian, Ye; Tkachenko, S.; Torayev, B.; Vernarsky, B.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Zachariou, N.; Zana, L.; Zhang, J.; Zhao, Z. W.; Zonta, I.

    2013-04-01

    Experimental results on the Σ+(1189) hyperon transverse polarization in photoproduction on a hydrogen target using the CLAS detector at Jefferson Laboratory are presented. The Σ+(1189) was reconstructed in the exclusive reaction γ+p→KS0+Σ+(1189) via the Σ+→pπ0 decay mode. The KS0 was reconstructed in the invariant mass of two oppositely charged pions with the π0 identified in the missing mass of the detected pπ+π- final state. Experimental data were collected in the photon energy range Eγ=1.0-3.5 GeV (s range 1.66-2.73 GeV). We observe a large negative polarization of up to 95%. As the mechanism of transverse polarization of hyperons produced in unpolarized photoproduction experiments is still not well understood, these results will help to distinguish between different theoretical models on hyperon production and provide valuable information for the searches of missing baryon resonances.

  7. Structure function of off-mass-shell pions and the calculation of the Sullivan process

    International Nuclear Information System (INIS)

    Shakin, C.M.; Sun, W.

    1994-01-01

    We construct a model for the pion (valence) structure function that fits the experimental data obtained in the study of the Drell-Yan process. The model may also be used to calculate the structure function of off-mass-shell pions. We apply our model in the study of deep-inelastic scattering from off-mass-shell pions found in the nucleon and are thus able to resolve a problem encountered in the standard analysis of such processes. The usual analysis is made using the structure function of on-mass-shell pions and requires the use of a soft πNN form factor that is inconsistent with standard nuclear physics phenomenology. The use of our off-mass-shell structure functions allows for a fit to the data for nonperturbative aspects of the nucleon ''sea'' with a pion-nucleon form factor of the standard form

  8. Quasifree pion electroproduction from nuclei in the Δ region

    International Nuclear Information System (INIS)

    Lee, F.X.; Wright, L.E.; Bennhold, C.

    1995-10-01

    We present calculations of the reaction Α (e, e 1 π N)B in the distorted wave impulse approximation. The reaction allows for the study of the production process in the nuclear medium without being obscured by the details of nuclear transition densities. First, a pion electroproduction operator suitable for nuclear calculations is obtained by extending the Blomqvist-Laget photoproduction operator to the virtual photon case. The operator is gauge invariant, unitary, reference frame independent, and describes the existing data reasonably well. Then it is applied in nuclei to predict nuclear cross sections under a variety of kinematic arrangements. Issues such as the effects of gauge-fixing, the interference of the Δ resonance with the background, sensitivities to be guadrupole component of the Δ excitation and to the electromagnetic form factors, the role of final-state interactions, are studied in detail. Methods on how to experimentally separate the various pieces in the coincidence cross section are suggested. Finally, the model is compared to recent SLAC experiment. (authors)

  9. Leading neutron energy and p{sub T} distributions in deep inelastic scattering and photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2007-02-15

    The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and p{sub T}{sup 2} distributions were measured with a forward neutron calorimeter and tracker in a 40 pb{sup -1} sample of inclusive deep inelastic scattering (DIS) data and a 6 pb{sup -1} sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper p{sub T}{sup 2} distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. (orig.)

  10. Measurement of elastic ρ0 photoproduction at HERA

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1995-01-01

    Elastic ρ 0 photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from ep interactions were used to measure the reaction γp→ρ 0 p (ρ 0 →π + π - )at photon-proton centre-of-mass energies between 60 and 80 GeV and vertical stroke t vertical stroke 2 , where t is the square of the four-momentum transferred at the proton vertex. The differential cross section dσ/dM ππ , where M ππ is the invariant mass of the two pions, and the integrated cross section, σ γp →ρ 0 p , are presented; the latter was measured to be 14.7 ±0.4(stat.)±2.4(syst.) μb. The differential cross section dσ/dt has an approximately exponential shape; a fit of the type A' t exp(-b' t vertical stroke t vertical stroke +c' t t 2 ) yields a t-slope b' t =9.9±1.2(stat.)±1.4(syst.) GeV -2 . The results, when compared to low energy data, show a weak energy dependence of both σ γp→ρ 0 p and of the t-slope. The ρ 0 is produced predominantly with transverse polarisation, demostrating that s-channel helicity conservation holds at these energies. (orig.)

  11. Measurement of elastic ρ0 photoproduction at HERA

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1995-07-01

    Elastic ρ 0 photoproduction has been measured using the ZEUS detector at HERA. Untagged photoproduction events from ep interactions were used to measure the reaction γp→ρ 0 p (ρ 0 →π + π - ) at photon-proton centre-of-mass energies between 60 and 80 GeV and vertical stroke tvertical stroke 2 , where t is the square of the four-momentum transferred at the proton vertex. The differential cross section dσ/dM ππ , where M ππ is the invariant mass of the two pions, and the integrated cross section, σsub(γp→ρ 0 p), are presented; the latter was measured to be 14.7±0.4(stat.)±2.4(syst.) μb. The differential cross section dσ/dt has an approximately exponential shape; a fit of the type A' t exp(-b' t vertical stroke tvertical stroke +c' t t 2 ) yields a t-slope b' t =9.9±1.2(stat.)±1.4(syst.) μb. The results, when compared to low energy data, show a weak energy dependence of both σsub(γp→ρ 0 p) and of the t-slope. The ρ 0 is produced predominantly with transverse polarisation, demonstrating that s-channel helicity conservation holds at these energies. (orig.)

  12. Inelastic J/ψphotoproduction

    International Nuclear Information System (INIS)

    Kraemer, M.

    1995-04-01

    Inelastic photoproduction of J/ψ particles at high energies is one of the processes to determine the gluon distribution in the nucleon. The QCD radiative corrections to the color-singlet model of this reaction have recently been calculated. They are large at moderate photon energies, but decrease with increasing energies. I compare the cross section and the J/ψ energy spectrum with the available fixed-target photoproduction data. Predictions for the HERA energy range are given which demonstrate the sensitivity of the result to the parametrization of the gluon distribution in the small-x region. (orig.)

  13. Photoproduction of mesons on the nucleon at intermediate energies; Photoproduction de mesons sur le nucleon aux energies intermediaires

    Energy Technology Data Exchange (ETDEWEB)

    Guidal, M

    1997-01-01

    In this work a model is proposed to simulate the photoproduction of pseudoscalar mesons ('PI' and K) on the nucleon at high energy. This model is based on the exchange of mesonic or baryonic Regge trajectories, it is gauge invariant and it uses a Feynman diagram formalism inspired from isobaric models. The measurements concerning the following reactions {gamma}p {yields} n{pi}{sup +}, {gamma}n {yields} p{pi}{sup -}, {gamma}p {yields} p{pi}{sup 0} and {gamma}n {yields} n{pi}{sup 0} are reviewed and the new model is confronted to the experimental results. The model gives a reasonable and coherent description of these 4 reactions. The model has also been applied to the photoproduction of strange mesons and of {lambda} and {sigma} baryons and has been extrapolated at low energy to the threshold of the reaction, the model matches the results even up to E{sub {gamma}} = 2 GeV for differential cross-sections and recoil polarization. An attempt has been made to associate a Regge based description, which is valid with low transfers, with perturbative quantum chromodynamics which is valid with high transfers. The model relies on the saturation of trajectories in the high transfer region and on the counting laws that give the right variation of the cross-section. It seems that a model based on linear trajectories can be reliable up to 4 GeV. The domain of high transfer has been too little investigated to provide enough experimental data to validate the model. An experiment whose purpose is to study the photoproduction of {phi} at high transfer, is proposed. This experiment requires an accelerator with high useful cycle because of the smallness of the expected cross-section. The CEBAF (continuous electron beam accelerator facility) as well as the CLAS 4{pi} detector is presented. The study of {gamma}p {yields} p{phi} and {gamma}p {yields} K{lambda}{sup *} (1520) requires the discrimination of kaons from pions so the measurement of 180 ps as time resolution allows the

  14. Isospin breaking in pion-nucleon scattering at threshold by radiative processes

    CERN Document Server

    Ericson, Torleif Eric Oskar

    2006-01-01

    We investigate the dispersive contribution by radiative processes such as (pi- proton to neutron gamma) and (pi- proton to Delta gamma) to the pion-nucleon scattering lengths of charged pions in the heavy baryon limit. They give a large isospin violating contribution in the corresponding isoscalar scattering length, but only a small violation in the isovector one. These terms contribute 6.3(3)% to the 1s level shift of pionic hydrogen and give a chiral constant F_pi^2f_1=-25.8(8) MeV.

  15. Workshop on hadron structure from photo-reactions at intermediate energies: Proceedings

    International Nuclear Information System (INIS)

    Nathan, A.M.; Sandorfi, A.M.

    1992-01-01

    This report contains papers on the following topics: The proton compton effect: Recent measurements of the electric and magnetic polorizabilities of the proton; experiments on the electric polarizability of the neutron; chiral symmetry and nucleon polarizabilities; chiral model predictions for electromagnetic polarizabilities of the nucleon, a consumer report; the polarizabilities of bound nucleons; nucleon polarizability in free space and in nuclear matter; mechanisms of photon scattering on nucleons at intermediate energies; pion polarizabilities in chiral perturbation theory; pion polarizabilities and the shielding of σ(700)-meson exchange in γγ→ππ processes; pion and kaon polarizabilities in the quark confinement model; radiative pion photoproduction and pion polarizabilities; pion and sigma polarizabilities and radiative transitions; the quadrupole amplitude in the γΝ-Δ transition; pion photoproduction and the γΝ-Δ amplitudes; effective- lagrangians, Watson's theorem, and the E2/M1 mixing ratio in the excitation of the delta resonance; new measurements of the p(rvec γ, π o ) reaction; multipole analyses and photo-decay couplings at intermediate energies; compton scattering off the proton; connections between compton scattering and pion photoproduction in the delta region; single-pion electroproduction and the transverse one-half and scalar helicity transition form factors; relativistic effects, QCD mixing angles, and Ν → Νγ and Δ → γΝ transition form factors; electroproduction studies of the Ν → Δ transition at bates and CEBAF

  16. Quasifree pion electroproduction from nuclei in the {Delta} region

    Energy Technology Data Exchange (ETDEWEB)

    Lee, F X [TRIUMF, Vancouver, BC (Canada); Wright, L E [Ohio Univ., Inst. of Nuclear and Particle Physics, Dept. of Physics, Athens, OH (United States); Bennhold, C [George Washington Univ., Center for Nuclear Studies, Dept. of Physics, Washington, DC (United States)

    1995-10-01

    We present calculations of the reaction {Alpha} (e, e{sup 1}{pi} N)B in the distorted wave impulse approximation. The reaction allows for the study of the production process in the nuclear medium without being obscured by the details of nuclear transition densities. First, a pion electroproduction operator suitable for nuclear calculations is obtained by extending the Blomqvist-Laget photoproduction operator to the virtual photon case. The operator is gauge invariant, unitary, reference frame independent, and describes the existing data reasonably well. Then it is applied in nuclei to predict nuclear cross sections under a variety of kinematic arrangements. Issues such as the effects of gauge-fixing, the interference of the {Delta} resonance with the background, sensitivities to be guadrupole component of the {Delta} excitation and to the electromagnetic form factors, the role of final-state interactions, are studied in detail. Methods on how to experimentally separate the various pieces in the coincidence cross section are suggested. Finally, the model is compared to recent SLAC experiment. (authors) 35 refs., 22 figs.

  17. Photoproduction within the two-component Dual Parton Model: amplitudes and cross sections

    International Nuclear Information System (INIS)

    Engel, R.; Siegen Univ.

    1995-01-01

    In the framework of the Dual Parton Model an approximation scheme to describe high energy photoproduction processes is presented. Based on the distinction between direct, resolved soft, and resolved hard interaction processes we construct effective impact parameter amplitudes. In order to treat low mass diffraction within the eikonal formalism in a consistent way a phenomenological ansatz is proposed. The free parameters of the model are determined by fits to high energy hadro- and photoproduction cross sections. We calculate the partial photoproduction cross sections and discuss predictions of the model at HERA energies. Using hadro- and photoproduction data together, the uncertainties of the model predictions are strongly reduced. (orig.)

  18. Workshop on hadron structure from photo-reactions at intermediate energies: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Nathan, A.M.; Sandorfi, A.M. (eds.)

    1992-01-01

    This report contains papers on the following topics: The proton compton effect: Recent measurements of the electric and magnetic polorizabilities of the proton; experiments on the electric polarizability of the neutron; chiral symmetry and nucleon polarizabilities; chiral model predictions for electromagnetic polarizabilities of the nucleon, a consumer report; the polarizabilities of bound nucleons; nucleon polarizability in free space and in nuclear matter; mechanisms of photon scattering on nucleons at intermediate energies; pion polarizabilities in chiral perturbation theory; pion polarizabilities and the shielding of [sigma](700)-meson exchange in [gamma][gamma][yields][pi][pi] processes; pion and kaon polarizabilities in the quark confinement model; radiative pion photoproduction and pion polarizabilities; pion and sigma polarizabilities and radiative transitions; the quadrupole amplitude in the [gamma][Nu]-[Delta] transition; pion photoproduction and the [gamma][Nu]-[Delta] amplitudes; effective- lagrangians, Watson's theorem, and the E2/M1 mixing ratio in the excitation of the delta resonance; new measurements of the p([rvec [gamma

  19. Pion-nuclear many body problems

    International Nuclear Information System (INIS)

    Weise, W.

    1981-01-01

    This chapter examines pion-nucleus scattering data produced at the meson factories in order to gain information about the ''optical'' branches of the pion-nuclear excitation spectrum. Discusses basic meson-baryon effective Lagrangians and elementary processes; pion-baryon vertex form factors; the spin-isospin dependent baryon-baryon interaction; pions in nuclear matter; nuclear spin-isospin correlations; the baryon-hole model; photon-induced excitation of baryon-hole states; high momentum transfer properties of pion-like nuclear states; a response function for pionic low-frequency modes in finite nuclei; and applications. Finds that there is no clear evidence for pionic critical opalescence, as in agreement with the expectation that the minimal density for the appearance of a pion condensate is certainly not lower than two or three times nuclear matter density

  20. Photoproduction of Neutral Kaons on Deuterons

    Science.gov (United States)

    Beckford, Brian

    2006-11-01

    Experimentation to greater understand the strangeness production mechanism can be performed by observing the electromagnetic interaction that leads to Kaon photoproduction. The n (γ, K^0) λ reaction may assist in answering questions about the strangeness photo-production process. An experiment into the elementary Kaon photoproduction process was investigated in an experiment conducted at the Laboratory of Nuclear Science of Tohoku University (LNS) using the Neutral Kaon Spectrometer. (NKS). The experiment was conducted by the d (γ, K^0) reaction. K^0 will be measured in the K^0->π^+π^- decay chain by the NKS. The NKS implements many detectors working in coincidence: These ranging from the Tagged Photon Beam generated by the 1.2 GeV Electron beam via bremsstrahlung, an Inner Plastic Scintillator Hodoscope (IH), a Straw Drift Chamber (SDC), a Cylindrical Drift Chamber (CDC), and an Outer Plastic Scintillator Hodoscope. Due to the background produced through the γ-> e+e- process, electron veto counters (EV) were placed in the middle of the OH to reject charged particles in the horizontal plane of the beam line. Preliminary analysis of the data indicates the need for pulse height correction. This was achieved by analysis of the Inner and Outer hodoscopes, and determining the energy deposit in the scintillators.

  1. Pions in nuclei, from virtual-pion exchange to real-pion transfer

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu.

    1988-07-01

    Tracing the work of Miyazawa on nuclear magnetic moments, we discuss possible experimental ways to see whether a real pion exists in nuclei or not. While virtual pions are known to play an important role in nuclei, as clarified experimentally from anomalous orbital g factors of nucleons in nuclei, nearly nothing is known for the behavior of real pions in nuclei. We have shown that deeply bound hybrid states of π - are expected to exist in heavy nuclei, which can be populated by ''pion transfer'' reactions. (author)

  2. Photoproduction experiments

    International Nuclear Information System (INIS)

    Wattenberg, A.

    1977-01-01

    Results of some experimental collaborations to search for new particles through photoproduction are briefly surveyed. The J/psi photoproduction on protons has been observed to rise slowly till above 12 GeV and then very steeply up to 55 GeV, exhibiting a pseudo-threshold behaviour. The psi production on Be and Ta is obtained to be sigmasub(psiN)=3.5+-0.8 mb at 20 GeV, which is somewhat higher than the vector dominance photoproduction value. A mass spectrum is shown for the γ+Be → μμ reaction at 90-200 GeV exhibiting a psi-like peak. Another mass spectrum for the γ+p → e + e - +p reaction shows very prominent rho/ω and phi peaks on top of Bethe-Heitler background. More data is needed to determine whether these events are due to very improbable statistical fluctuations or due to new narrow resonances

  3. Workshop on hadron structure from photo-reactions at intermediate energies: Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Nathan, A.M.; Sandorfi, A.M. [eds.

    1992-10-01

    This report contains papers on the following topics: The proton compton effect: Recent measurements of the electric and magnetic polorizabilities of the proton; experiments on the electric polarizability of the neutron; chiral symmetry and nucleon polarizabilities; chiral model predictions for electromagnetic polarizabilities of the nucleon, a consumer report; the polarizabilities of bound nucleons; nucleon polarizability in free space and in nuclear matter; mechanisms of photon scattering on nucleons at intermediate energies; pion polarizabilities in chiral perturbation theory; pion polarizabilities and the shielding of {sigma}(700)-meson exchange in {gamma}{gamma}{yields}{pi}{pi} processes; pion and kaon polarizabilities in the quark confinement model; radiative pion photoproduction and pion polarizabilities; pion and sigma polarizabilities and radiative transitions; the quadrupole amplitude in the {gamma}{Nu}-{Delta} transition; pion photoproduction and the {gamma}{Nu}-{Delta} amplitudes; effective- lagrangians, Watson`s theorem, and the E2/M1 mixing ratio in the excitation of the delta resonance; new measurements of the p({rvec {gamma}}, {pi}{sup o}) reaction; multipole analyses and photo-decay couplings at intermediate energies; compton scattering off the proton; connections between compton scattering and pion photoproduction in the delta region; single-pion electroproduction and the transverse one-half and scalar helicity transition form factors; relativistic effects, QCD mixing angles, and {Nu} {yields} {Nu}{gamma} and {Delta} {yields} {gamma}{Nu} transition form factors; electroproduction studies of the {Nu} {yields} {Delta} transition at bates and CEBAF.

  4. Photoproduction and Radiative Decay of eta' Meson in CLAS at Jlab

    Energy Technology Data Exchange (ETDEWEB)

    Mbianda Njencheu, Georgie [Old Dominion Univ., Norfolk, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2017-05-01

    In this work the η' meson photoproduction cross sections as well as the distribution of the di-pion invariant mass, m(π+π-), in the radiative decay mode n' -> π+π-γ have been measured using the CLAS detector at the Thomas Jefferson National Accelerator Facility using tagged incident photons in the center-of-mass energy range 1.96 GeV - 2.72 GeV. The measurements are performed on a liquid hydrogen target in the reaction γ π -> π η'(η'-> π+π-γ). The analysis is based on the highest statistics collected in this decay channel in comparison to other experiments reported so far. The n' photoproduction cross sections measured with radiative decay are in a good agreement with results of previous publication from the same data set in CLAS obtained through η' -> π+π-γ decay mode. Two free parameters, α and Β, are extracted from a model-independent fit to the m(π+π-) distribution and their values are found to agree well with recent theoretical expectations. The results of both parameters confirm the existence of the box anomaly, ρ-ω mixing and effects of the a2(1320) tensor meson in the radiative decay of η'.

  5. Exclusive electroproduction of pion pairs

    International Nuclear Information System (INIS)

    Warkentin, N.; Schaefer, A.; Diehl, M.; Ivanov, D. Yu.

    2007-01-01

    We investigate electroproduction of pion pairs on the nucleon in the framework of QCD factorization for hard exclusive processes. We extend previous analyses by taking the hard-scattering coefficients at next-to-leading order in α s . The dynamics of the produced pion pair is described by two-pion distribution amplitudes, for which we perform a detailed theoretical and phenomenological analysis. In particular, we obtain constraints on these quantities by comparing our results with measurements of angular observables that are sensitive to the interference between two-pion production in the isoscalar and isovector channels. (orig.)

  6. Virtual-pion and two-photon production in pp scattering

    International Nuclear Information System (INIS)

    Scholten, O.; Korchin, A.Yu.

    2002-01-01

    Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contributions. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

  7. J/Psi and Gamma Photoproduction in Pb-Pb Collisions at LHC

    CERN Document Server

    Li Yun De; CERN. Geneva

    1996-01-01

    abstractINT-96-01 Hard photoproduction of J/psi and upsilon at LHC Pb-Pb collisions with cms energy 6300 AGeV, is discussed in the process Pb+Pb--Pb + J/psi (upsilon) + X with three types of equivalent photon spectrum function. It turns out that in hard photoproduction the J/psi cross section is dominated by the gluon and heavy quark fragmentation, especially the gluon fragmentation is very important at large pt; while the Upsilon cross section is dominated by the leading order process. It may be concluded from the result that the hard photoproduction processes can be used to test several important problems such as the gluon distribution in nucleus, gluon and heavy quark fragmentation of J/psi , etc. In addition, these processes also provide a new way of testing the EMC effects.

  8. Pion-pair formation and the pion dispersion relation in a hot pion gas

    Energy Technology Data Exchange (ETDEWEB)

    Chanfay, G. [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Alm, T. [Rostock Univ. (Germany); Schuck, P. [Grenoble-1 Univ., 38 (France). Inst. des Sciences Nucleaires; Welke, G. [Wayne State Univ., Detroit, MI (United States). Dept. of Physics and Astronomy

    1996-09-01

    The possibility of pion-pair formation in a hot pion gas, based on the bosonic gap equation, is pointed out and discussed in detail. The critical temperature for condensation of pion pairs (Evans-Rashind transition) is determined as a function of the pion density. As for fermions, this phase transition is signaled by the appearance of a pole in the two-particle propagator. In Bose systems there exists a second, lower critical temperature, associated with the appearance of the single-particle condensate. Between the two critical temperatures the pion dispersion relation changes from the usual quasiparticle dispersion to a Bogoliubov-like dispersion relation at low momenta. This generalizes the non-relativistic results for an attractive Bose gas by Evans et al. Possible consequences for the inclusive pion spectra measured in heavy-ion collisions at ultra-relativistic energies are discussed. 21 refs.

  9. Chiral Dynamics in Pion-Photon Reactions Habilitation

    CERN Document Server

    Friedrich, Jan Michael

    As the lightest particle of the strong force, the pion plays a central role in the field of strong interactions, and understanding its properties is of prime relevance for understanding the strong interaction in general. The low-energy behaviour of pions is of particular interest. Although the quark-gluon substructure and their quantum chromodynamics is not apparent then, this specific inner structure causes the presence of approximate symmetries in pion-pion interactions and in pion decays, which gives rise to the systematic description of processes involving pions in terms of few low-energy constants. Specifically, the chiral symmetry and its spontaneous and explicit breaking, treated in chiral perturbation theory (ChPT), leads to firm predictions for low-energy properties of the pion. To those belong the electromagnetic polarisabilities of the pion, describing the leading-order structure effect in pion Compton scattering. The research presented in this work is concerned with the interaction of pions and ph...

  10. Relating inclusive and exclusive meson photoproduction at large transverse momentum

    International Nuclear Information System (INIS)

    Scott, D.M.

    1975-01-01

    Inclusive and exclusive meson photoproduction at large transverse momentum are related by a local application of the correspondence principle of Bjorken and Kogut. The recent predictions for the inclusive process by Escobar are thus compared with wide angle exclusive data. The inclusive photoproduction of (rho 0 +ω) at large transverse momentum is discussed. (Auth.)

  11. Photo- and pion electroproduction in chiral effective field theory; Photo- und Elektropionproduktion in chiraler effektiver Feldtheorie

    Energy Technology Data Exchange (ETDEWEB)

    Hilt, Marius

    2011-12-13

    This thesis is concerned with pion photoproduction (PPP) and pion electroproduction (PEP) in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory. For that purpose two different approaches are used. Firstly, a one-loop-order calculation up to chiral order O(q{sup 4}) including pions and nucleons as degrees of freedom, is performed to describe the energy dependence of the reactions over a large range. To improve the dependence on the virtuality of the photon in PEP, in a second approach vector mesons are included as explicit degrees of freedom. The latter calculation includes one-loop contributions up to chiral order O(q{sup 3}). Only three of the four physical processes of PPP and PEP can be accessed experimentally. These reactions are measured at several different facilities, e.g. Mainz, Bonn, or Saskatoon. The data obtained there are used to explore the limits of chiral perturbation theory. This thesis is the first complete manifestly Lorentz-invariant calculation up to order O(q{sup 4}) for PPP and PEP, and the first calculation ever for these processes including vector mesons explicitly. Beside the calculation of physical observables, a partial wave decomposition is performed and the most important multipoles are analyzed. They may be extracted from the calculated amplitudes and allow one to examine the nucleon and {delta} resonances. The number of diagrams one has to calculate is very large. In order to handle these expressions, several routines were developed for the computer algebra system Mathematica. For the multipole decomposition, two different programs are used. On the one hand, a modified version of the so-called {chi}MAID has been employed. On the other hand, similar routines were developed for Mathematica. In the end, the different calculations are compared with respect to their applicability to PPP and PEP.

  12. Helicity asymmetry of the single π{sup 0} photoproduction on neutron

    Energy Technology Data Exchange (ETDEWEB)

    Cividini, Federico [Institut fuer Kernphysik, Universitaet Mainz (Germany); Collaboration: A2-Collaboration

    2016-07-01

    During the pion production reaction, the nucleon is excited to an intermediate resonant state, and a systematic analysis of the experimental data allows a determination of the main properties of the baryon resonances. A detailed knowledge of the spectrum of nucleon excited states gives essential constraints on models of nucleon structure. The data for the observables accessible using a polarised photon beam and/or polarised nucleon targets are scarce in many channels, especially in those induced on the neutron. A measurement is performed at the Mainz Microtron, using a circularly polarised photon beam and longitudinally polarised proton and deuteron targets. The detector is the large acceptance Crystal Ball/TAPS setup. The talk gives an overview of the status of the experiment and the preliminary results of the helicity asymmetry of the single π{sup 0} photoproduction reaction from the deuteron target.

  13. Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

    International Nuclear Information System (INIS)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coboeken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Weber, A.; Wieber, H.; Bailey, D.S.; Barret, O.; Brook, N.H.; Foster, B.; Heath, G.P.; Heath, H.F.; Rodrigues, E.; Scott, J.; Tapper, R.J.; Capua, M.; Schioppa, M.; Susinno, G.; Jeoung, H.Y.; Kim, J.Y.; Lee, J.H.; Lim, I.T.; Ma, K.J.; Pac, M.Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycien, M.B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jelen, K.; Kisielewska, D.; Kowal, A.M.; Kowalski, T.; Przybycien, M.; Rulikowska-Zarebska, E.; Suszycki, L.; Szuba, D.; Kotanski, A.; Bauerdick, L.A.T.; Behrens, U.; Bienlein, J.K.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Goers, S.; Goettlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G.F.; Hebbel, K.; Hillert, S.; Koch, W.; Koetz, U.; Kowalski, H.; Labes, H.; Loehr, B.; Mankel, R.; Martens, J.; Martinez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Rohde, M.; Savin, A.A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.; Straub, P.B.; Barbagli, G.; Gallo, E.; Parenti, A.; Pelfer, P.G.; Bamberger, A.; Benen, A.; Coppola, N.; Eisenhardt, S.; Markun, P.; Raach, H.; Woelfle, S.; Bussey, P.J.; Bell, M.; Doyle, A.T.; Glasman, C.; Lee, S.W.; Lupi, A.; Macdonald, N.; McCance, G.J.; Saxon, D.H.; Sinclair, L.E.; Skillicorn, I.O.; Waugh, R.; Bohnet, I.; Gendner, N.; Holm, U.; Meyer-Larsen, A.; Salehi, H.; Wick, K.; Carli, T.; Garfagnini, A.; Gialas, I.; Gladilin, L.K.; Kcira, D.; Klanner, R.; Lohrmann, E.; Goncalo, R.; Long, K.R.; Miller, D.B.; Tapper, A.D.; Walker, R.; Cloth, P.; Filges, D.; Ishii, T.; Kuze, M.; Nagano, K.; Tokushuku, K.; Yamada, S.; Yamazaki, Y.; Ahn, S.H.; Lee, S.B.; Park, S.K.; Lim, H.; Son, D.; Barreiro, F.; Garcia, G.; Gonzalez, O.; Labarga, L.; del Peso, J.; Redondo, I.; Terron, J.; Vazquez, M.; Barbi, M.; Corriveau, F.; Hanna, D.S.; Ochs, A.; Padhi, S.; Stairs, D.G.; Wing, M.; Tsurugai, T.; Antonov, A.; Bashkirov, V.; Danilov, M.; Dolgoshein, B.A.; Gladkov, D.; Sosnovtsev, V.; Suchkov, S.; Dementiev, R.K.; Ermolov, P.F.; Golubkov, Yu.A.; Katkov, I.I.; Khein, L.A.; Korotkova, N.A.; Korzhavina, I.A.; Kuzmin, V.A.; Lukina, O.Yu.; Proskuryakov, A.S.; Shcheglova, L.M.; Solomin, A.N.; Vlasov, N.N.; Zotkin, S.A.; Bokel, C.; Botje, M.; Bruemmer, N.; Engelen, J.; Grijpink, S.; Koffeman, E.; Kooijman, P.; Schagen, S.; van Sighem, A.; Tassi, E.; Tiecke, H.; Tuning, N.; Velthuis, J.J.; Vossebeld, J.; Wiggers, L.; de Wolf, E.; Bylsma, B.; Durkin, L.S.; Gilmore, J.; Ginsburg, C.M.; Kim, C.L.; Ling, T.Y.; Boogert, S.; Cooper-Sarkar, A.M.; Devenish, R.C.E.; Grosse-Knetter, J.; Matsushita, T.; Ruske, O.; Sutton, M.R.; Walczak, R.; Bertolin, A.; Brugnera, R.; Carlin, R.; Dal Corso, F.; Dusini, S.; Limentani, S.; Longhin, A.; Posocco, M.; Stanco, L.; Turcato, M.; Adamczyk, L.; Iannotti, L.; Oh, B.Y.; Okrasinski, J.R.; Saull, P.R.B.; Toothacker, W.S.; Whitmore, J.J.; Iga, Y.; D'Agostini, G.; Marini, G.; Nigro, A.; Cormack, C.; Hart, J.C.; McCubbin, N.A.; Shah, T.P.; Epperson, D.; Heusch, C.; Sadrozinski, H.F.-W.; Seiden, A.; Wichmann, R.; Williams, D.C.; Park, I.H.; Pavel, N.; Abramowicz , H.; Dagan, S.; Kananov, S.; Kreisel, A.; Levy, A.; Abe, T.; Fusayasu, T.; Kohno, T.; Umemori, K.; Yamashita, T.; Hamatsu, R.; Hirose, T.; Inuzuka, M.; Kitamura, S.; Matsuzawa, K.; Nishimura, T.; Arneodo, M.; Cartiglia, N.; Cirio, R.; Costa, M.; Ferrero, M.I.; Maselli, S.; Monaco, V.; Peroni, C.; Ruspa, M.; Sacchi, R.; Solano, A.; Staiano, A.; Bailey, D.C.; Fagerstroem, C.-P.; Galea, R.; Koop, T.; Levman, G.M.; Martin, J.F.; Mirea, A.; Sabetfakhri, A.; Butterworth, J.M.; Hayes, M.E.; Heaphy, E.A.; Jones, T.W.; Lane, J.B.; West, B.J.; Ciborowski, J.; Ciesielski, R.; Grzelak, G.; Nowak, R.J.; Pawlak, J.M.; Pawlak, R.; Smalska, B.; Tymieniecka, T.; Wroblewski, A.K.; Zakrzewski, J.A.; Zarnecki, A.F.; Adamus, M.; Gadaj, T.; Deppe, O.; Eisenberg, Y.; Hochman, D.; Karshon, U.; Badgett, W.F.; Chapin, D.; Cross, R.; Foudas, C.; Mattingly, S.; Reeder, D.D.; Smith, W.H.; Vaiciulis, A.; Wildschek, T.; Wodarczyk, M.; Deshpande, A.; Dhawan, S.; Hughes, V.W.; Bhadra, S.; Catterall, C.; Cole, J.E.; Frisken, W.R.; Hall-Wilton, R.; Khakzad, M.; Menary, S.

    2001-01-01

    Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e + +p→e + +n+jet+jet+X r have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb -1 . The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E T jet >6 GeV, neutron energy E n >400 GeV, and neutron production angle θ n <0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model

  14. From meson-baryon scattering to meson photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Mai, Maxim

    2013-09-01

    iteration of local terms of second chiral order allows to reproduce the s-wave resonances N{sup *}(1535)S{sub 11} and N{sup *}(1650)S{sub 11}. Then in chapter 5 we will adopt this hadronic amplitude as a part of a gauge invariant framework to address pion and eta photoproduction in a combined analysis. There all terms of the next-to-leading chiral order are included reproducing the scattering data very well in both channels. After that we calculate the photoproduction multipoles in a parameter-free prediction which are then compared with more phenomenological analyses by the MAID, ETAMAID, SAID and Bonn-Gatchina groups.

  15. On two-particle correlations of identical pions

    International Nuclear Information System (INIS)

    Podgoretskij, M.I.

    1991-01-01

    The pion generation processes, in which the interference term describing the correlations of identical pions seems to be negative, have been analyzed. It is shown that similar processes can take place, in particular, in nuclear collisions at intermediate energies

  16. The expanding pion liquid and the pion spectra

    International Nuclear Information System (INIS)

    Ayala, A.

    1999-01-01

    We compute the pion inclusive momentum distribution in heavy-ion collisions for energies at the Alternating Gradient Synchrotron (AGS), assuming thermal equilibrium and accounting for density and expansion effects at freeze out. We compare to data on mid-rapidity charged pions produced in central Au + Au collisions and find a very good agreement. The shape of the distribution at low transverse mass is explained in part as an effect arising from the high mean pion density achieved in these reactions. The difference between the positive and negative pion distributions in the same region is attributed in part to the different average yields of each kind of charged pions. (Author)

  17. Characteristics of the pion production and nucleon emission processes in pion-carbon nuclear collisions at 40 GeV/.c

    International Nuclear Information System (INIS)

    Strugalski, Z.; Sultanov, M.

    1992-01-01

    Experimental data on pion-carbon nucleus collisions are presented. The momentum and energy spectra of protons emitted from the target nucleus do not depend on the intensity of the pion production in the collisions. 6 refs.; 12 figs.; 12 tabs

  18. Production of positive pions from polarized protons by linearly polarized photons in the energy region 300--420 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Get' man, V.A.; Gorbenko, V.G.; Grushin, V.F.; Derkach, A.Y.; Zhebrovskii, Y.V.; Karnaukhov, I.M.; Kolesnikov, L.Y.; Luchanin, A.A.; Rubashkin, A.L.; Sanin, V.M.; Sorokin, P.V.; Sporov, E.A.; Telegin, Y.N.; Shalatskii, S.V.

    1980-10-01

    A technique for measurement of the polarization observables ..sigma.., P, and T for the reaction ..gamma..p..-->..n..pi../sup +/ in a doubly polarized experiment (polarized proton target + linearly polarized photon beam) is described. Measurements of the angular distributions of these observables in the range of pion emission angles 30--150/sup 0/ are presented for four photon energies from 300 to 420 MeV. Inclusion of the new experimental data in an energy-independent multipole analysis of photoproduction from protons permits a more reliable selection of solutions to be made.

  19. Drell-Yan lepton pair photoproduction

    International Nuclear Information System (INIS)

    Badalyan, R.G.; Grabskij, V.O.; Matinyan, S.G.

    1989-01-01

    The study of photon structure functions by spectra of massive lepton pairs (M l + l - ≥ 2 GeV) in photon fragmentation region in γp-interactions at high energies is suggested. In calculations of Drell-Yan lepton pair inclusive spectra in γp-interactions for photon structure functions there are used results obtained within QCD, data on γγ-interactions in e + e - → e + e - X on colliders as well as results from the analysis of vector meson non-diffractive photoproduction at high energies. It is shown that there exists a sufficienly wide kinematic region over variables X l + l - and M l + l - , wherein photon structure functions can be studied by spectra of Grell-Yan lepton pairs in the processes of their photoproduction. 31 refs.; 6 figs.; 1 tab

  20. Gravitational wave from dark sector with dark pion

    Energy Technology Data Exchange (ETDEWEB)

    Tsumura, Koji [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Yamada, Masatoshi [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg (Germany); Yamaguchi, Yuya, E-mail: ko2@gauge.scphys.kyoto-u.ac.jp, E-mail: m.yamada@thphys.uni-heidelberg.de, E-mail: yy@particle.sci.hokudai.ac.jp [Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2017-07-01

    In this work, we investigate the spectra of gravitational waves produced by chiral symmetry breaking in dark quantum chromodynamics (dQCD) sector. The dark pion (π) can be a dark matter candidate as weakly interacting massive particle (WIMP) or strongly interacting massive particle (SIMP). For a WIMP scenario, we introduce the dQCD sector coupled to the standard model (SM) sector with classical scale invariance and investigate the annihilation process of the dark pion via the 2π → 2 SM process. For a SIMP scenario, we investigate the 3π → 2π annihilation process of the dark pion as a SIMP using chiral perturbation theory. We find that in the WIMP scenario the gravitational wave background spectra can be observed by future space gravitational wave antennas. On the other hand, when the dark pion is the SIMP dark matter with the constraints for the chiral perturbative limit and pion-pion scattering cross section, the chiral phase transition becomes crossover and then the gravitational waves are not produced.

  1. Joint resummation for pion wave function and pion transition form factor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hsiang-nan [Institute of Physics, Academia Sinica,Academia Rd., Taipei, Taiwan 115 (China); Department of Physics, National Cheng-Kung University,University Rd., Tainan, Taiwan 701 (China); Department of Physics, National Tsing-Hua University,Kuang-Fu Rd., Hsinchu, Taiwan 300 (China); Shen, Yue-Long [College of Information Science and Engineering, Ocean University of China,Songling Rd, Qingdao, Shandong 266100 (China); Wang, Yu-Ming [Institut für Theoretische Teilchenphysik und Kosmologie RWTH Aachen,Physikzentrum Otto-Blumenthal-Straße, D-52056 Aachen (Germany); Physik Department T31, Technische Universität München,James-Franck-Straße, D-85748 Garching (Germany)

    2014-01-03

    We construct an evolution equation for the pion wave function in the k{sub T} factorization formalism, whose solution sums the mixed logarithm ln xln k{sub T} to all orders, with x (k{sub T}) being a parton momentum fraction (transverse momentum). This joint resummation induces strong suppression of the pion wave function in the small x and large b regions, b being the impact parameter conjugate to k{sub T}, and improves the applicability of perturbative QCD to hard exclusive processes. The above effect is similar to those from the conventional threshold resummation for the double logarithm ln{sup 2} x and the conventional k{sub T} resummation for ln{sup 2} k{sub T}. Combining the evolution equation for the hard kernel, we are able to organize all large logarithms in the γ{sup ∗}π{sup 0}→γ scattering, and to establish a scheme-independent k{sub T} factorization formula. It will be shown that the significance of next-to-leading-order contributions and saturation behaviors of this process at high energy differ from those under the conventional resummations. It implies that QCD logarithmic corrections to a process must be handled appropriately, before its data are used to extract a hadron wave function. Our predictions for the involved pion transition form factor, derived under the joint resummation and the input of a non-asymptotic pion wave function with the second Gegenbauer moment a{sub 2}=0.05, match reasonably well the CLEO, BaBar, and Belle data.

  2. Corrections to the quasi-free process

    International Nuclear Information System (INIS)

    Laget, J.M.

    1978-01-01

    At intermediate energy the photon-nucleus interaction is dominated by the quasi-free process: the photon interacts with one nucleon moving in a mean potential. The other nucleons are spectator in the sense that their overall effects is to create a mean optical potential in which the outgoing particles move (Distorted Wave Impulse Approximation). The limits of the validity of this process will be discussed on the basis of the results of the analysis of the two following kinds of reactions: 1. The A(γ,π)B reactions induced by a monochromatic photon beam. Here the spectrum of pions emitted at a given angle is measured. 2. The A(γ,pπ)B reactions induced by a bremsstrahlung beam. Here the proton and the pion are detected in coincidence. The dominance of this mechanism decreases quickly when the momentum of the spectator system increases, and strong deviations appear. They are understood in terms of the onset of two nucleon mechanisms. Two of them are of dominating importance: the Δ-N interaction and the meson exchange corrections to the γN→Nπ vertex. We shall put the emphasis on their consequences on the yield of pion photoproduction reactions induced on few body systems

  3. Invariant potential for elastic pion--nucleus scattering

    International Nuclear Information System (INIS)

    Cammarata, J.B.; Banerjee, M.K.

    1976-01-01

    From the Wick-Dyson expansion of the exact propagator of a pion in the presence of a nucleus, an invariant potential for crossing symmetric elastic pion-nucleus scattering is obtained in terms of a series of pion-nucleon diagrams. The Chew-Low theory is used to develop a model in which the most important class of diagrams is effectively summed. Included in this model is the exclusion principle restriction on the pion-bound nucleon interaction, the effects of the binding of nucleons, a kinematic transformation of energy from the lab to the πN center of mass frame, and the Fermi motion and recoil of the target nucleons. From a numerical study of the effects of these processes on the π- 12 C total cross section, the relative importance of each is determined. Other processes contributing to the elastic scattering of pions not included in the present model are also discussed

  4. Pion-nucleus scattering in the isobar formalism

    International Nuclear Information System (INIS)

    Moniz, E.J.

    1978-06-01

    Lectures on the isobar-hole model for pion reactions include the isobar as an explicit degree of freedom and the connection with a purely pion and nucleon system, the formalism and its relation to the pion optical potential, the extended schematic model for pion scattering, a simple spinless s-wave model, application to pion-oxygen 16 scattering and comparison with elastic scattering data. In this way the extent is shown to which microscopic treatment of the many-body dynamics explains the data and the extent to which additional physical input is required. Another test is the various inelastic processes. Inclusive reactions are briefly discussed. 37 references

  5. Quasi-free K+ photo-production in 12C

    International Nuclear Information System (INIS)

    Maeda, K.; Yamazaki, H.; Asano, S.; Emura, T.; Endo, I.; Endo, S.; Ito, S.; Itoh, H.; Ifuku, K.; Konno, O.; Koike, M.; Maruyama, K.; Niki, K.; Niwa, K.; Okuno, H.; Sakaguchi, A.; Sasaki, T.; Suda, T.; Sumi, Y.; Takeya, M.; Terasawa, T.; Uchida, H.; Yamashita, H.; Yoshida, K.

    1994-01-01

    Quasi-free K + photo-production in the 12 C(γ,K + ) reaction has been investigated in a photon energy range of 0.7-1.1GeV. Differential cross sections for the quasi-free process of the 12 C(γ,K + ) reaction have been obtained and they are compared with a calculation of a quasi-free K + photo-production. The effective proton number Z eff =4.2±0.6 obtained from the experiment was in good agreement with a calculation of a semi-classical attenuation model. ((orig.))

  6. Detecting the neutral top-pion at e+e- colliders

    International Nuclear Information System (INIS)

    Wang Xuelei; Yang Yueling; Li Bingzhong

    2004-01-01

    We investigate some processes of the associated production of a neutral top-pion Π t 0 with a pair of fermions (e + e - →ff-barΠ t 0 ) in the context of top-color-assisted technicolor (TC2) theory in the future e + e - colliders. The studies show that the largest cross sections of the processes e + e - →f ' f ' Π t 0 (f ' =u,d,c,s,μ,τ) could only reach the level of 0.01 fb; we can hardly detect a neutral top-pion through these processes. For the processes e + e - →e + e - Π t 0 , e + e - →tt-barΠ t 0 , and e + e - →bb-barΠ t 0 , the cross sections of these processes are at the level of a few fb for the favorable parameters, and a few tens, even hundreds, of neutral top-pion events can be produced at future e + e - colliders each year through these processes. With the clean background of the flavor-changing tc-bar channel, the top-pion events can possibly be detected at the planned high luminosity e + e - colliders. Therefore, such neutral top-pion production processes provide a useful way to detect a neutral top-pion and test the TC2 model directly

  7. Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Breitweg, J.; Chekanov, S.; Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Pellegrino, A.; Repond, J.; Stanek, R.; Yoshida, R.; Mattingly, M.C.K.; Antonioli, P.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, A.; Bruni, G.; Cara Romeo, G.; Cifarelli, L.; Cindolo, F.; Contin, A.; Corradi, M.; De Pasquale, S.; Giusti, P.; Iacobucci, G.; Levi, G.; Margotti, A.; Massam, T.; Nania, R.; Palmonari, F.; Pesci, A.; Sartorelli, G.; Zichichi, A.; Amelung, C.; Bornheim, A.; Brock, I.; Coboeken, K.; Crittenden, J.; Deffner, R.; Hartmann, H.; Heinloth, K.; Hilger, E.; Irrgang, P.; Jakob, H.-P.; Kappes, A.; Katz, U.F.; Kerger, R.; Paul, E.; Rautenberg, J.; Schnurbusch, H.; Stifutkin, A.; Tandler, J.; Voss, K.C.; Weber, A.; Wieber, H.; Bailey, D.S.; Barret, O.; Brook, N.H.; Foster, B. E-mail: b.foster@bristol.ac.uk; Heath, G.P.; Heath, H.F.; Rodrigues, E.; Scott, J.; Tapper, R.J.; Capua, M.; Schioppa, M.; Susinno, G.; Jeoung, H.Y.; Kim, J.Y.; Lee, J.H.; Lim, I.T.; Ma, K.J.; Pac, M.Y.; Caldwell, A.; Liu, W.; Liu, X.; Mellado, B.; Paganis, S.; Sampson, S.; Schmidke, W.B.; Sciulli, F.; Chwastowski, J.; Eskreys, A.; Figiel, J.; Klimek, K.; Olkiewicz, K.; Piotrzkowski, K.; Przybycien, M.B.; Stopa, P.; Zawiejski, L.; Bednarek, B.; Jelen, K.; Kisielewska, D.; Kowal, A.M.; Kowalski, T.; Przybycien, M.; Rulikowska-Zarebska, E.; Suszycki, L.; Szuba, D.; Kotanski, A.; Bauerdick, L.A.T.; Behrens, U.; Bienlein, J.K.; Borras, K.; Chiochia, V.; Dannheim, D.; Desler, K.; Drews, G.; Fox-Murphy, A.; Fricke, U.; Goebel, F.; Goers, S.; Goettlicher, P.; Graciani, R.; Haas, T.; Hain, W.; Hartner, G.F.; Hebbel, K.; Hillert, S.; Koch, W.; Koetz, U.; Kowalski, H.; Labes, H.; Loehr, B.; Mankel, R.; Martens, J.; Martinez, M.; Milite, M.; Moritz, M.; Notz, D.; Petrucci, M.C.; Polini, A.; Rohde, M.; Savin, A.A.; Schneekloth, U.; Selonke, F.; Sievers, M.; Stonjek, S.; Wolf, G.; Wollmer, U.; Youngman, C.; Zeuner, W.; Coldewey, C.; Lopez-Duran Viani, A.; Meyer, A.; Schlenstedt, S.[and others

    2001-02-26

    Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e{sup +}+p{yields}e{sup +}+n+jet+jet+X{sub r} have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb{sup -1}. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies E{sub T}{sup jet}>6 GeV, neutron energy E{sub n}>400 GeV, and neutron production angle {theta}{sub n}<0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model.

  8. Hadronic form factors in kaon photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Syukurilla, L., E-mail: tmart@fisika.ui.ac.id; Mart, T., E-mail: tmart@fisika.ui.ac.id [Department Fisika, FMIPA, Universitas Indonesia, Depok, 164242 (Indonesia)

    2014-09-25

    We have revisited the effect of hadronic form factors in kaon photoproduction process by utilizing an isobaric model developed for kaon photoproduction off the proton. The model is able to reproduce the available experimental data nicely as well as to reveal the origin of the second peak in the total cross section, which was the main source of confusion for decades. Different from our previous study, in the present work we explore the possibility of using different hadronic form factors in each of the KΛN vertices. The use of different hadronic form factors, e.g. dipole, Gaussian, and generalized dipole, has been found to produce a more flexible isobar model, which can provide a significant improvement in the model.

  9. Organizational procedure for the study of pion production and absorption processes on nuclei

    International Nuclear Information System (INIS)

    Banerjee, M.K.; Walker, G.E.

    1983-01-01

    For nuclear processes involving pions, such as pion production/absorption or exchange currents, it is shown that a natural organization involves adoption of the πNN vertex function g/sub π/(q 2 )#betta# 5 tau/sub α/, where q is the pion four-momentum and g/sub π/(m/sub π/ 2 )approx. =13.4 is the renormalized pion-nucleon coupling constant. The result is independent of the form and details of any fundamental interaction Lagrangian. The difference between g/sub π/(q 2 )#betta# 5 tau/sub α/ and the fully-dressed πNN vertex function contributes to amplitudes involving more bosons, e.g., scattering amplitudes (πN→πN), production amplitudes (πN→ππN), etc. Such contributions are mediated through either seagull-like terms or P11 intermediate states. It is pointed out that it is neither necessary nor practical to calculate these partial contributions to scattering and production amplitudes. One can always exploit other approaches, theoretical and phenomenological, to make reasonably good models for the full amplitudes. The usual procedure of including the effects of negative energy parts of the nucleon propagator in interaction potentials, exchange currents, etc., is easily included in the present organization. The result is that from scattering amplitudes, etc; the positive energy nucleon poles are deleted but Z graphs are included

  10. Strangeness photoproduction at the BGO-OD experiment

    Energy Technology Data Exchange (ETDEWEB)

    Jude, Thomas [Physikalisches Institut, Bonn University (Germany); Collaboration: BGO-OD-Collaboration

    2016-07-01

    The BGO-OD experiment at the ELSA accelerator facility uses an energy tagged bremstrahlung photon beam to investigate the internal structure of the nucleon. The setup consists of a highly segmented BGO calorimeter surrounding the target, with a particle tracking magnetic spectrometer at forward angles. Compared to constituent quark models (CQMs), models including psuedoscalar meson-baryon interactions have had improved success in describing baryon excitation spectra. For example, the Λ(1405) appears to be dynamically generated from meson-baryon interactions at least to some extent. Vector-meson baryon interactions have also been predicted to dynamically generate states, which may have been observed in photoproduction reactions. BGO-OD is ideal for investigating low momentum transfer processes due to the acceptance and high momentum resolution at forward angles. This enables the investigation of degrees of freedom not derived from CQMs, and in particular, strangeness photoproduction where t-channel exchange mechanisms play a dominant role. With the first major data taking periods for BGO-OD complete, an extensive programme for the investigation of associated strangeness photoproduction has begun.

  11. Dijet photoproduction

    CERN Document Server

    Butterworth, J M

    2001-01-01

    Recent jet photoproduction measurements are presented, including measurements of jet substructure which are sensitive to parton types. The implications for real and virtual photon structure are discussed. (11 refs).

  12. Pion interferometry theory for the hydrodynamic stage of multiple processes

    International Nuclear Information System (INIS)

    Makhlin, A.N.; Sinyukov, Yu.M.

    1986-01-01

    The double pion inclusive cross section for identical particles is described in hydrodynamical theory of multiparticle production. The pion interferometry theory is developed for the case when secondary particles are generated against the background of internal relativistic motion of radiative hadron matter. The connection between correlation functions in various schemes of experiment is found within the framework of relativistic Wigner functions formalism

  13. Quantum signature in heavy-ion pion production

    International Nuclear Information System (INIS)

    Buvel, R.L.

    1985-01-01

    A revised model for pion production in heavy-ion peripheral collisions is presented. The pion-production mechanism investigated here is a two step process involving the formation and subsequent decay of an isobar resonance in the projectile nucleus. The independent-particle shell model with harmonic oscillator states is used to approximate the internal structure of the nucleus. The inclusion of the internal structure of the projectile nucleus led to the discovery of a quantum signature in the pion-production differential cross section. The quantum signature involves a matching condition where the pion-production differential cross section goes to zero for a particular value of the pion kinetic energy. The theory is compared to a recent experiment, but the results of this comparison are inconclusive

  14. Longitudinal Electroproduction of Charged Pions from

    International Nuclear Information System (INIS)

    David Gaskell; Abdellah Ahmidouch; Pawel Ambrozewicz; H. Anklin; John Arrington; K. Assamagan; Steven Avery; Kevin Bailey; Oliver K. Baker; Shelton Beedoe; Elizabeth Beise; Herbert Breuer; D. S. Brown; Roger Carlini; Jinseok Cha; Nicholas Chant; Anthony Cowley; Samuel Danagoulian; D. De Schepper; Jim Dunne; Dipangkar Dutta; Rolf Ent; Liping Gan; Ashot Gasparian; Donald Geesaman; Ron Gilman; Charles Glashausser; Paul Gueye; M. Harvey; O. Hashimoto; Wendy Hinton; G. Hofman; Ceasar Jackson; Hal Jackson; Cynthia Keppel; Ed Kinney; Doug Koltenuk; G. Kyle; Allison Lung; David Mack; D. McKee; Joseph Mitchell; Hamlet Mkrtchyan; B. Mueller; Gabriel Niculescu; Ioana Niculescu; Tom O'Neill; V. Papavassiliou; Dave Potterveld; Juerg Reinhold; Philip Roos; Reyad Sawafta; Ralph Segel; Stepan Stepanyan; Vardan Tadevosyan; T. Takahashi; Liguang Tang; B. Terburg; D. Van Westrum; J. Volmer; T. P. Welch; Stephen Wood; Lulin Yuan; Ben Zeidman; Beni Zihlmann

    2001-01-01

    Separated longitudinal and transverse cross sections for charged pion electroproduction from 1 H, 2 H, and 3 He were measured at Q 2 = 0.4 (GeV/c) 2 for two values of the invariant mass, (bar W) = 1.15 GeV and (bar W) = 1.60 GeV, in a search for a mass dependence which would signal the effect of nuclear pions. This is the first such study that includes recoil momenta significantly above the Fermi surface. The longitudinal cross section, if dominated by the pion-pole process, should be sensitive to nuclear pion currents. Comparisons of the longitudinal cross section target ratios to a quasifree calculation reveal a significant suppression in 3> He at (bar W) = 1.60 GeV. The (bar W) = 1.15 GeV results are consistent with simple estimates of the effect of nuclear pion currents, but are also consistent with pure quasifree production

  15. Capture and transfer of pions in hydrogenous materials

    International Nuclear Information System (INIS)

    Armstrong, D.S.

    1990-05-01

    Pionic hydrogen is a short-lived exotic hydrogen isotope in which a negative pion replaces the atomic electron. The formation and subsequent interactions of pionic hydrogen are discussed, with emphasis on the process of pion transfer. Recent results using the pion charge-exchange reaction (π - , π 0 ) obtained at TRIUMF are reviewed. (Author) (35 refs., 3 tabs., 9 figs.)

  16. Reggeon and pion contributions in exclusive diffractive processes at HERA

    International Nuclear Information System (INIS)

    Golec-Biernat, K.; Kwiecinski, J.; Szczurek, A.

    1997-01-01

    The contribution of subleading f 2 , ω, a 2 and ρ reggeons to the diffractive structure function F 2 D(3) (x P , β, Q 2 )are estimated. In addition we include the pion exchange which was recently found to be responsible for the violation of the Gottfried Sum Rule. The reggeon and pion contribution lead to a violation of the factorization of the diffractive structure function. The diffractive structure function is separated into the contributions with leading proton Δ (n) F 2 D /Δ (p) F 2 D as a function ox x P in the interval 10 -2 P -1 . The effect is due to the exchange of the isovector a 2 and ρ reggeons at smaller x P and the pion exchange at x P > 10 -2 . (author). 27 refs, 4 figs

  17. Multi-pion production

    International Nuclear Information System (INIS)

    Beavis, D.; Fung, S.Y.; Gorn, W.; Keane, D.; Liu, Y.M.; Poe, R.T.; VanDalen, G.; Vient, M.

    1984-01-01

    Preliminary analysis of pion production in 1.2 GeV/nucleon Kr-RbBr collisions is presented. The negative pion multiplicity is consistent with a convolution of Poisson distributions and a freeze-out density between 1/3 and 1/2 normal nuclear density is extracted. Global negative pion kinematic variables are used to search for possible structure in the multi-pion emission. No evidence for structured emission or conservation constraints is found. Pion interferometry analysis gives a source radius of 5.4 +- 1.2 Fermi and a freeze-out density of .3 +- .2 times normal nuclear density. 10 refs., 5 figs

  18. Low energy pion--nucleon and pion--deuteron interactions

    International Nuclear Information System (INIS)

    Burman, R.L.

    1975-01-01

    This survey concentrates upon current experiments in the fields of pion-nucleon and pion-deuteron interactions, for low-energy incident pions--below 300 MeV. The discussion is restricted to very recent work. The topics to be covered are: π +- p → π +- p, Elastic Scattering; π +- p → π +- pγ, Bremsstrahlung; π + d → pp, Absorption; π d → π + d, Elastic Scattering; and π + d → π + pn, Breakup. (14 figures) (U.S.)

  19. Low energy pion-pion phase shifts from chiral perturbation theory

    International Nuclear Information System (INIS)

    Borges, J. Sa; Barbosa, J. Soares; Oguri, V.

    1997-01-01

    The low energy pion-pion S- and P- experimental phase-shifts are fitted with chiral perturbation theory (Ch PT) amplitude. The low energy pion-pion S- and P- experimental phase-shifts. The parameters l 1 and l 2 of the one loop corrected amplitude are fixed and the corresponding values of the scattering lengths are calculated. We propose that the present method is the best way to fix Ch P T parameters. The unitarization program of current algebra is also discussed. (author)

  20. Strangeness photoproduction and hadronic resonances; Photoproduction d`etrangete et resonances hadroniques

    Energy Technology Data Exchange (ETDEWEB)

    David, J C

    1994-09-01

    The purpose of this thesis is to study the kaon photoproduction off a proton ({gamma}p {yields} K{sup +}{Lambda},{gamma}p {yields} K{sup +}{Sigma}{sup 0}, {gamma}p {yields} K{sup 0}{Sigma}{sup +}), with a photon energy between 0.9 and 2.1 GeV. We use an isobaric model where the amplitudes are computed with Feynman diagrams. The insertion of nucleonic resonances with spin 3/2 and 5/2 is necessary to improve the existing models beyond 1.5 GeV. This step is also necessary to extend the elementary process of photoproduction to electroproduction where the data have been taken with photon energies above 2.0 GeV. The parameters of our models are the coupling constants which appear at each Feynman diagram vertex. They are determined by fitting our models to the experimental data (cross sections, polarization asymmetries). Before performing the minimization we drew some informations about coupling constants from mesonic and electromagnetic decays, and from SU(3) and SU(6) symmetries. In conclusion, the models developed here reproduce the experimental data (E{sub {gamma}} {<=} 2.0 GeV) and the two main coupling constants are in good agreement with broken SU(3)-symmetry predictions. (author). 47 refs.

  1. Pionic retardation effects in two-pion-exchange three-nucleon forces

    International Nuclear Information System (INIS)

    Coon, S.A.; Friar, J.L.

    1986-01-01

    Those two-pion-exchange three-nucleon forces which arise from nuclear processes that involve only pions and nucleons are calculated. Among the processes which contribute are pion seagulls (e.g., nucleon-antinucleon pair terms) and overlapping, retarded pion exchanges. The resulting potential is shown to be a (v/c) 2 relativistic correction, and satisfies nontrivial constraints from special relativity. The relativistic ambiguities found before in treatments of relativistic corrections to the one-pion-exchange nuclear charge operator and two-body potential are also present in the three-nucleon potential. The resulting three-nucleon force differs from the original Tucson-Melbourne potential only in the presence of several new nonlocal terms, and in the specification of the choice of ambiguity parameters in the latter potential

  2. Pionic retardation effects in two-pion-exchange three-nucleon forces

    Science.gov (United States)

    Coon, S. A.; Friar, J. L.

    1986-09-01

    Those two-pion-exchange three-nucleon forces which arise from nuclear processes that involve only pions and nucleons are calculated. Among the processes which contribute are pion seagulls (e.g., nucleon-antinucleon pair terms) and overlapping, retarded pion exchanges. The resulting potential is shown to be a (v/c)2 relativistic correction, and satisfies nontrivial constraints from special relativity. The relativistic ambiguities found before in treatments of relativistic corrections to the one-pion-exchange nuclear charge operator and two-body potential are also present in the three-nucleon potential. The resulting three-nucleon force differs from the original Tucson-Melbourne potential only in the presence of several new nonlocal terms, and in the specification of the choice of ambiguity parameters in the latter potential.

  3. Pionic retardation effects in two-pion-exchange three-nucleon forces

    Energy Technology Data Exchange (ETDEWEB)

    Coon, S.A.; Friar, J.L.

    1986-09-01

    Those two-pion-exchange three-nucleon forces which arise from nuclear processes that involve only pions and nucleons are calculated. Among the processes which contribute are pion seagulls (e.g., nucleon-antinucleon pair terms) and overlapping, retarded pion exchanges. The resulting potential is shown to be a (v-italic/c-italic)/sup 2/ relativistic correction, and satisfies nontrivial constraints from special relativity. The relativistic ambiguities found before in treatments of relativistic corrections to the one-pion-exchange nuclear charge operator and two-body potential are also present in the three-nucleon potential. The resulting three-nucleon force differs from the original Tucson-Melbourne potential only in the presence of several new nonlocal terms, and in the specification of the choice of ambiguity parameters in the latter potential.

  4. Photoproduction of the K= K0-(1750)

    International Nuclear Information System (INIS)

    Mitchell, Ryan Edward

    2003-01-01

    While photoproduction has often been advertised as an important environment in which to study light meson spectroscopy, solid experimental results are sparse. In fact, beyond the relatively straightforward photoproduction of the ρ, ω, and ψ mesons, the few results of exclusive photoproduction that do exist are poorly understood, and several, perhaps, have even been misinterpreted. After extensively reviewing the sometimes tenuous history of the exclusive photoproduction of the ''p'(1600),'' the ''ωπ 0 (1250),'' the ''ω(1650),'' and the ''K + K - (1750),'' new results from the E831/FOCUS photoproduction experiment at Fermilab are presented which address the interpretation of the K + K - (1750). This enhancement in low-p T K + K - pairs at a mass near 1750 MeV/c 2 has been observed by several previous photoproduction experiments, but, despite several apparent inconsistencies, it has always been interpreted as the J PC = 1 -- ψ(1680) meson. With nearly two orders of magnitude more events than any previous observation of the K + K - (1750), and based on precise measurements of its mass and width, and its absence from the K*K final state, the FOCUS data can finally render this interpretation implausible. In addition, several steps have been taken towards establishing a new interpretation. Based on limited angular analyses of its decay and the beam energy dependence of its production, they argue that, in the absence of any wild interference scenarios, the K + K - (1750) has J PC ≠ 1 -- , and, in fact, the most likely assignment appears to be 2 ++ . It is hoped that this work can help set the stage for future reevaluations and new insights in photoproduction

  5. Single meson photoproduction and IR renormalons

    International Nuclear Information System (INIS)

    Agaev, S.S.

    1996-10-01

    Single pseudoscalar and vector mesons inclusive photoproduction γh → MX via higher twist mechanism is calculated using the QCD running coupling constant method. It is proved that in the context of this method a higher twist contribution to the photoproduction cross section cannot be normalized in terms of the meson electromagnetic form factor. The structure of infrared renormalon singularities of the higher twist subprocess cross section and the resumed expression (the Borel sum) for it are found. Comparisons are made with earlier results, as well as with leading twist cross section. Phenomenological effects of studied contributions for π, K, ρ-meson photoproduction are discussed. (author). 21 refs, 8 figs

  6. Connected and disconnected contractions in pion-pion scattering

    Science.gov (United States)

    Acharya, Neramballi Ripunjay; Guo, Feng-Kun; Meißner, Ulf-G.; Seng, Chien-Yeah

    2017-09-01

    We show that the interplay of chiral effective field theory and lattice QCD can be used in the evaluation of so-called disconnected diagrams, which appear in the study of the isoscalar and isovector channels of pion-pion scattering and have long been a major challenge for the lattice community. By means of partially-quenched chiral perturbation theory, we distinguish and analyze the effects from different types of contraction diagrams to the pion-pion scattering amplitude, including its scattering lengths and the energy-dependence of its imaginary part. Our results may be used to test the current degree of accuracy of lattice calculation in the handling of disconnected diagrams, as well as to set criteria for the future improvement of relevant lattice computational techniques that may play a critical role in the study of other interesting QCD matrix elements.

  7. Final-state interaction in spin asymmetry and GDH sum rule for incoherent pion production on the deuteron

    International Nuclear Information System (INIS)

    Darwish, E.M.; Arenhoevel, H.; Schwamb, M.

    2003-01-01

    The contribution of incoherent single-pion photoproduction to the spin response of the deuteron, i.e., the asymmetry of the total photoabsorption cross-section with respect to parallel and antiparallel spins of photon and deuteron, is calculated over the region of the Δ-resonance with inclusion of final-state NN and πN rescattering. Sizeable effects, mainly from NN rescattering, are found leading to an appreciable reduction of the spin asymmetry. Furthermore, the contribution to the Gerasimov-Drell-Hearn integral is explicitly evaluated by integration up to a photon energy of 550 MeV. Final-state interaction reduces the value of the integral to about half of the value obtained for the pure impulse approximation. (orig.)

  8. Low-energy photoproduction of PHI-mesons

    CERN Document Server

    Barth, J; Glander, K H; Hannappel, J; Jöpen, N; Klein, F J; Klein, F; Lawall, R; Menze, D; Neuerburg, W; Ostrick, M; Paul, E; Schulday, I; Schwille, W J; Wiegers, B; Ernst, J; Kalinowsky, H; Klempt, E; Link, J; Pee, H V; Wieland, F W; Wisskirchen, J; Wu, C

    2003-01-01

    Photoproduction of PHI-vector-mesons has been studied from reaction threshold up to W=2.4 GeV with the SAPHIR spectrometer at the Bonn electron stretcher ring ELSA. Total cross-sections, differential cross-sections and decay angular distributions were measured. We find evidence for strong non-diffractive contributions to PHI photoproduction. (orig.)

  9. A new determination of the pion mass

    International Nuclear Information System (INIS)

    Anagnastopoulos, D.; Belmiloud, D.; El-Khoury, P.; Indelicato, P.; Borchert, G.; Gorke, H.; Gotta, D.; Lenz, S.; Siems, T.; Daum, M.; Frosch, R.; Hauser, P.; Kirch, K.; Simons, L.M.

    1996-01-01

    Initial measurements concerning the feasibility of a new pion mass determination are described. In a first step, a high-resolution crystal spectrometer was coupled to a cyclotron trap which provides a high pion stopping density, sufficient to check predictions for the cascade process and to measure the stability of the apparatus. A comparison with the measured Cu K α fluorescence line resolves an ambiguity in the value of the pion mass. The preliminary result from this experiment is m π -=(139.57040±0.00045) MeV/c 2 . (orig.)

  10. Pion condensation and neutron star dynamics

    International Nuclear Information System (INIS)

    Kaempfer, B.

    1983-01-01

    The question of formation of pion condensate via a phase transition in nuclear matter, especially in the core of neutron stars is reviewed. The possible mechanisms and the theoretical restrictions of pion condensation are summarized. The effects of ultradense equation of state and density jumps on the possible condensation phase transition are investigated. The possibilities of observation of condensation process are described. (D.Gy.)

  11. Beam Spin Asymmetry Measurements for Two Pion Photoproduction at CLAS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Mark D. [Univ. of Glasgow, Scotland (United Kingdom)

    2015-09-01

    The overarching goal of this analysis, and many like it, is to develop our understanding of the strong force interactions within the nucleon by examining the nature of their excitation spectra. As the resonances of these spectra have very short lifetimes (tau = 1x10-23 s) and often have very similar masses, it is often impossible to directly observe resonances in the excitation spectra of nucleons. Polarization observables allow us to study the resonances by looking at how they affect the spin state of final state particles. The beam asymmetry is a polarization observable that allows us to detect the sensitivity of these resonances, and other transition mechanisms, to the electric vector orientation of incident photons. Presented in this thesis are first measurements of the beam asymmetries in the resonant region for the reaction channel pgamma p --> p π+ π-focusing on the intermediate mesonic states rho^0 and f^0, and the final state pions. The analysis used data from the g8b experiment undertaken at the Thomas Jefferson National Accelerator Facility (JLab), the first experiment at JLab to use a linearly polarized photon beam. Using the coherent Bremsstrahlung facility and the CLAS detector of Hall B at JLab allowed for many multi-channel reactions to be detected and the first measurements of many polarization observables including those presented here. A brief overview of the theoretical framework used to undertake this analysis is given, followed by a description of the experimental details of the facilities used, then a description of the calibration of the Bremsstrahlung tagging facility which the author undertook, and finally the analysis is presented and the resulting measurements.

  12. Effects of the pion string at heavy ion collisions

    International Nuclear Information System (INIS)

    Mao Hong; Li Yunde; East China Normal Univ., Shanghai

    2005-01-01

    The authors study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy √s=5.5 TeV. The authors follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. The authors will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p-143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p-21 MeV. (authors)

  13. Effects of the pion string at heavy ion collisions

    CERN Document Server

    Mao, Hong

    2005-01-01

    We study the possible signals of the pion string associated with the QCD chiral phase transition in LHC Pb-Pb collision at energy square root s=5.5 TeV. We follow the Kibble-Zurek mechanism to discuss the production and evolution of the pion string. We will show that if the QCD chiral phase transition really takes place in the LHC Pb-Pb collision process and the phase transition is in the second order, the pion string will be inevitably produced and subsequently decay. The main effect of this phenomenon is that there is a generation of a large number of pions in the final state produced by the decay of the pion string, and these pions are mostly distributed in a low momentum region with p143 MeV; also there are lots of neutral pions distributed in a low momentum region with the mean momentum at p21 Me V.

  14. The pion structure function and scale breaking in Drell-Yan processes

    International Nuclear Information System (INIS)

    Moore, R.

    1979-01-01

    By use of the formalism of QCD, the structure functions of the nucleon and the pion obtained at Q 2 = m 2 sub(psi) is extended to higher values of Q 2 . These structure functions are then used to obtain predictions of scale-breaking effects in Drell-Yan lepton-pair production for both nucleon-nucleon and pion-nucleon cases. A comparison with recent experimental data is also presented. (author)

  15. Ultraviolet-induced mutations in Cockayne syndrome cells are primarily caused by cyclobutane dimer photoproducts while repair of other photoproducts is normal

    International Nuclear Information System (INIS)

    Parris, C.N.; Kraemer, K.H.

    1993-01-01

    The authors compared the contribution to mutagenesis on Cockayne syndrome (CS) cells of the major class of UV photoproducts, the cyclobutane pyrimidine dimer, to that of other DNA photoproducts by using the mutagenesis shuttle vector pZ189. Lymphoblastoid cell lines from the DNA repair-deficient disorders CS and xeroderma pigmentosum (XP) and a normal line were transfected with UV-treated pZ189. Cyclobutane dimers were selectively removed before transfection by photoreactivation (PR), leaving nondimer photoproducts intact. After UV exposure and replication in CS and XP cells, plasmid survival was abnormally elevated. After PR, plasmid survival increased and mutation frequency in CS cells decreased to normal levels but remained abnormal in XP cells. Sequence analysis of >200 mutant plasmids showed that with CS cells a major mutational hot spot was caused by unrepaired cyclobutane dimers. These data indicate that with both CS and XP cyclobutane dimers are major photoproducts generating reduced plasmid survival and increased mutation frequency. However, unlike XP, CS cells are proficient in repair of nondimer photoproducts. Since XP but not CS patients have a high frequency of UV-induced skin cancers, the data suggest that prevention of UV-induced skin cancers is associated with proficient repair of nondimer photoproducts. 38 refs., 3 figs., 2 tabs

  16. Structure function of carbon nucleus in cumulative π-meson photoproduction processes

    International Nuclear Information System (INIS)

    Egiyan, K.Sh.; Ohandjanyan, M.S.

    1992-01-01

    The results of data analysis (10,11) on π meson photoproduction on nucleus 1 2C at E γ m ax = 4,5 GeV from the point of obtaining information about factorization of invariant cross section f π (α,P l 2 ) are presented. It is shown that in the representation f π (α,P l 2 ) ∼ f 1π (α )

  17. Strangeness photoproduction

    International Nuclear Information System (INIS)

    Berthot, J.; Saghai, B.

    1989-01-01

    A non exhaustive review, about the strangeness photo-production is presented here in relation with the new electrons machines. Accent is put on the elementary reaction γp → K + Λ. The experiments on electroproduction and the study of hypernuclei with the electromagnetic probe are also discussed [fr

  18. Role of nucleon resonance excitation in φ meson photoproduction

    International Nuclear Information System (INIS)

    Zhao, Q.; Didelez, J.P.; Guidal, M.; Saghai, B.

    2000-01-01

    The resonance effects are investigated in the φ meson photoproduction near threshold through a quark model approach with an effective Lagrangian. The diffractive contribution is consistently estimated by the t-channel Pomeron exchange. Another non-diffractive process, t-channel π 0 exchange is also included. The numerical result shows that the Pomeron exchange plays dominant role in the φ meson photoproduction, while the cross sections of the non-diffractive processes, i.e., s- and u-channel excitations, and t-channel π 0 exchange, are quite small. In the polarization observables, we find that large asymmetries are produced in the backward direction by the interferences from the s- and u-channel resonances, while in the forward direction, only very small asymmetries are generated. Meanwhile, we find that the effects from the π 0 exchange are generally negligible. (author)

  19. Pions scatter by nuclei

    International Nuclear Information System (INIS)

    Huefner, J.

    1975-01-01

    Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties

  20. Low and intermediate energy pion-nucleus interactions in the cascade-exciton model

    International Nuclear Information System (INIS)

    Mashnik, S.G.

    1993-01-01

    A large variety of experimental data on pion-nucleus interactions in the bombarding energy range of 0-3000 MeV, on nucleon-induced pion production and on cumulative nucleon production, when a two-step process of pion production followed by absorption on nucleon pairs within a target is taken into account, are analyzed with the Cascade-Exciton Model of nuclear reactions.Comparison is made with other up-to-date models of these processes. The contributions of different pion absorption mechanisms and the relative role of different particle production mechanisms in these reactions are discussed

  1. Effect of pion mean-field on properties of pions and kaons from heavy-ion collisions

    International Nuclear Information System (INIS)

    Zheng Yuming; Chu Zili; Wang Hui; Sa Benhao

    1996-01-01

    The Relativistic Vlasov-Uehling-Uhlenbeck (RVUU) model is used to study the properties of pions and kaons produced in heavy ion collisions. We include the nuclear medium effect on kaon and pion in the model, and simulate pion production and subthreshold kaon production in Kr + Zr reactions at 1 GeV/u. The calculated results show that the attractive pion optical potential changes the final-state pion momentum spectrum, enhancing the yield of pions with low transverse momenta. At the same time it also increases the kaon abundance and modifies the kaon momentum distribution

  2. Microscopic approach to subthreshold pion production in heavy-ion collisions

    International Nuclear Information System (INIS)

    Tohyama, M.; Kaps, R.; Masak, D.; Mosel, U.

    1985-01-01

    A microscopic approach to subthreshold pion production in heavy-ion collisions is proposed, in which the wave function of the nucleon system is approximated in the time-dependent Hartree-Fock theory and an effective interaction for the pion-production process is taken from (p,π) reaction theories. The model is applied to pion production in 16 O + 16 O collisions. (orig.)

  3. Measurement of the charged-pion polarizability.

    Science.gov (United States)

    Adolph, C; Akhunzyanov, R; Alexeev, M G; Alexeev, G D; Amoroso, A; Andrieux, V; Anosov, V; Austregesilo, A; Badełek, B; Balestra, F; Barth, J; Baum, G; Beck, R; Bedfer, Y; Berlin, A; Bernhard, J; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bodlak, M; Boer, M; Bordalo, P; Bradamante, F; Braun, C; Bressan, A; Büchele, M; Burtin, E; Capozza, L; Chiosso, M; Chung, S U; Cicuttin, A; Colantoni, M; Crespo, M L; Curiel, Q; Dalla Torre, S; Dasgupta, S S; Dasgupta, S; Denisov, O Yu; Dinkelbach, A M; Donskov, S V; Doshita, N; Duic, V; Dünnweber, W; Dziewiecki, M; Efremov, A; Elia, C; Eversheim, P D; Eyrich, W; Faessler, M; Ferrero, A; Filin, A; Finger, M; Finger, M; Fischer, H; Franco, C; du Fresne von Hohenesche, N; Friedrich, J M; Frolov, V; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S; Geyer, R; Gnesi, I; Gobbo, B; Goertz, S; Gorzellik, M; Grabmüller, S; Grasso, A; Grube, B; Grussenmeyer, T; Guskov, A; Guthörl, T; Haas, F; von Harrach, D; Hahne, D; Hashimoto, R; Heinsius, F H; Herrmann, F; Hinterberger, F; Höppner, Ch; Horikawa, N; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, A; Ivanshin, Yu; Iwata, T; Jahn, R; Jary, V; Jasinski, P; Jörg, P; Joosten, R; Kabuss, E; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koivuniemi, J H; Kolosov, V N; Kondo, K; Königsmann, K; Konorov, I; Konstantinov, V F; Kotzinian, A M; Kouznetsov, O; Krämer, M; Kroumchtein, Z V; Kuchinski, N; Kuhn, R; Kunne, F; Kurek, K; Kurjata, R P; Lednev, A A; Lehmann, A; Levillain, M; Levorato, S; Lichtenstadt, J; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Marchand, C; Martin, A; Marzec, J; Matousek, J; Matsuda, H; Matsuda, T; Meshcheryakov, G; Meyer, W; Michigami, T; Mikhailov, Yu V; Miyachi, Y; Moinester, M A; Nagaytsev, A; Nagel, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Novy, J; Nowak, W-D; Nunes, A S; Olshevsky, A G; Orlov, I; Ostrick, M; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Peshekhonov, D; Platchkov, S; Pochodzalla, J; Polyakov, V A; Pretz, J; Quaresma, M; Quintans, C; Ramos, S; Regali, C; Reicherz, G; Rocco, E; Rossiyskaya, N S; Ryabchikov, D I; Rychter, A; Samoylenko, V D; Sandacz, A; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schlüter, T; Schmidt, K; Schmieden, H; Schönning, K; Schopferer, S; Schott, M; Shevchenko, O Yu; Silva, L; Sinha, L; Sirtl, S; Slunecka, M; Sosio, S; Sozzi, F; Srnka, A; Steiger, L; Stolarski, M; Sulc, M; Sulej, R; Suzuki, H; Szabelski, A; Szameitat, T; Sznajder, P; Takekawa, S; ter Wolbeek, J; Tessaro, S; Tessarotto, F; Thibaud, F; Uhl, S; Uman, I; Virius, M; Wang, L; Weisrock, T; Wilfert, M; Windmolders, R; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zink, A

    2015-02-13

    The COMPASS collaboration at CERN has investigated pion Compton scattering, π(-)γ→π(-)γ, at center-of-mass energy below 3.5 pion masses. The process is embedded in the reaction π(-)Ni→π(-)γNi, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasireal photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, Q(2)<0.0015  (GeV/c)(2). From a sample of 63,000 events, the pion electric polarizability is determined to be α(π)=(2.0±0.6(stat)±0.7(syst))×10(-4)  fm(3) under the assumption α(π)=-β(π), which relates the electric and magnetic dipole polarizabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is found in agreement with the expectation from chiral perturbation theory. An additional measurement replacing pions by muons, for which the cross-section behavior is unambiguously known, was performed for an independent estimate of the systematic uncertainty.

  4. Measurement of elastic φ photoproduction at HERA

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1996-01-01

    The production of φ mesons in the reaction e + p→e + φp(φ→K + K - ) at a median Q 2 of 10 -4 GeV 2 has been studied with the ZEUS detector at HERA. The differential φ photoproduction cross section dσ/dt has an exponential shape and has been determined in the kinematic range 0.1 2 and 60 γp→φp 0.96±0.19 -0.18 +0.21 μb has been obtained by extrapolating to t=0. When compared to lower energy data, the results show a weak energy dependence of both σ γp→φp and the slope of the t distribution. The φ decay angular distributions are consistent with s-channel helicity conservation. From lower energies to HERA energies, the features of φ photoproduction are compatible with those of a soft diffractive process. (orig.)

  5. CLAS+FROST: new generation of photoproduction experiments at jefferson lab

    International Nuclear Information System (INIS)

    Pasyuk, E.

    2009-01-01

    A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target (FROST) gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented. (author)

  6. Strangeness photoproduction and hadronic resonances

    International Nuclear Information System (INIS)

    David, J.C.

    1994-09-01

    The purpose of this thesis is to study the kaon photoproduction off a proton (γp → K + Λ,γp → K + Σ 0 , γp → K 0 Σ + ), with a photon energy between 0.9 and 2.1 GeV. We use an isobaric model where the amplitudes are computed with Feynman diagrams. The insertion of nucleonic resonances with spin 3/2 and 5/2 is necessary to improve the existing models beyond 1.5 GeV. This step is also necessary to extend the elementary process of photoproduction to electroproduction where the data have been taken with photon energies above 2.0 GeV. The parameters of our models are the coupling constants which appear at each Feynman diagram vertex. They are determined by fitting our models to the experimental data (cross sections, polarization asymmetries). Before performing the minimization we drew some informations about coupling constants from mesonic and electromagnetic decays, and from SU(3) and SU(6) symmetries. In conclusion, the models developed here reproduce the experimental data (E γ ≤ 2.0 GeV) and the two main coupling constants are in good agreement with broken SU(3)-symmetry predictions. (author)

  7. Measurement of the Charged-Pion Polarizability

    CERN Document Server

    Adolph, C.; Alexeev, M.G.; Alexeev, G.D.; Amoroso, A.; Andrieux, V.; Anosov, V.; Austregesilo, A.; Badelek, B.; Balestra, F.; Barth, J.; Baum, G.; Beck, R.; Bedfer, Y.; Berlin, A.; Bernhard, J.; Bicker, K.; Bieling, J.; Birsa, R.; Bisplinghoff, J.; Bodlak, M.; Boer, M.; Bordalo, P.; Bradamante, F.; Braun, C.; Bressan, A.; Buchele, M.; Burtin, E.; Capozza, L.; Chiosso, M.; Chung, S.U.; Cicuttin, A.; Colantoni, M.; Crespo, M.L.; Curiel, Q.; Dalla Torre, S.; Dasgupta, S.S.; Dasgupta, S.; Denisov, O.Yu.; Dinkelbach, A.M.; Donskov, S.V.; Doshita, N.; Duic, V.; Dunnweber, W.; Dziewiecki, M.; Efremov, A.; Elia, C.; Eversheim, P.D.; Eyrich, W.; Faessler, M.; Ferrero, A.; Filin, A.; Finger, M.; Finger, M., Jr.; Fischer, H.; Franco, C.; von Hohenesche, N. du Fresne; Friedrich, J.M.; Frolov, V.; Gautheron, F.; Gavrichtchouk, O.P.; Gerassimov, S.; Geyer, R.; Gnesi, I.; Gobbo, B.; Goertz, S.; Gorzellik, M.; Grabmuller, S.; Grasso, A.; Grube, B.; Grussenmeyer, T.; Guskov, A.; Guthorl, T.; Haas, F.; von Harrach, D.; Hahne, D.; Hashimoto, R.; Heinsius, F.H.; Herrmann, F.; Hinterberger, F.; Hoppner, Ch.; Horikawa, N.; d'Hose, N.; Huber, S.; Ishimoto, S.; Ivanov, A.; Ivanshin, Yu.; Iwata, T.; Jahn, R.; Jary, V.; Jasinski, P.; Jorg, P.; Joosten, R.; Kabuss, E.; Ketzer, B.; Khaustov, G.V.; Khokhlov, Yu. A.; Kisselev, Yu.; Klein, F.; Klimaszewski, K.; Koivuniemi, J.H.; Kolosov, V.N.; Kondo, K.; Konigsmann, K.; Konorov, I.; Konstantinov, V.F.; Kotzinian, A.M.; Kouznetsov, O.; Kramer, M.; Kroumchtein, Z.V.; Kuchinski, N.; Kuhn, R.; Kunne, F.; Kurek, K.; Kurjata, R.P.; Lednev, A.A.; Lehmann, A.; Levillain, M.; Levorato, S.; Lichtenstadt, J.; Maggiora, A.; Magnon, A.; Makke, N.; Mallot, G.K.; Marchand, C.; Martin, A.; Marzec, J.; Matousek, J.; Matsuda, H.; Matsuda, T.; Meshcheryakov, G.; Meyer, W.; Michigami, T.; Mikhailov, Yu. V.; Miyachi, Y.; Moinester, M.A.; Nagaytsev, A.; Nagel, T.; Nerling, F.; Neubert, S.; Neyret, D.; Nikolaenko, V.I.; Novy, J.; Nowak, W.D.; Nunes, A.S.; Olshevsky, A.G.; Orlov, I.; Ostrick, M.; Panknin, R.; Panzieri, D.; Parsamyan, B.; Paul, S.; Peshekhonov, D.; Platchkov, S.; Pochodzalla, J.; Polyakov, V.A.; Pretz, J.; Quaresma, M.; Quintans, C.; Ramos, S.; Regali, C.; Reicherz, G.; Rocco, E.; Rossiyskaya, N.S.; Ryabchikov, D.I.; Rychter, A.; Samoylenko, V.D.; Sandacz, A.; Sarkar, S.; Savin, I.A.; Sbrizzai, G.; Schiavon, P.; Schill, C.; Schluter, T.; Schmidt, K.; Schmieden, H.; Schonning, K.; Schopferer, S.; Schott, M.; Shevchenko, O.Yu.; Silva, L.; Sinha, L.; Sirtl, S.; Slunecka, M.; Sosio, S.; Sozzi, F.; Srnka, A.; Steiger, L.; Stolarski, M.; Sulc, M.; Sulej, R.; Suzuki, H.; Szabelski, A.; Szameitat, T.; Sznajder, P.; Takekawa, S.; Wolbeek, J. ter; Tessaro, S.; Tessarotto, F.; Thibaud, F.; Uhl, S.; Uman, I.; Virius, M.; Wang, L.; Weisrock, T.; Wilfert, M.; Windmolders, R.; Wollny, H.; Zaremba, K.; Zavertyaev, M.; Zemlyanichkina, E.; Ziembicki, M.; Zink, A.

    2015-02-10

    The COMPASS collaboration at CERN has investigated pion Compton scattering, $\\pi^-\\gamma\\rightarrow \\pi^-\\gamma$, at centre-of-mass energy below 3.5 pion masses. The process is embedded in the reaction $\\pi^-\\mathrm{Ni}\\rightarrow\\pi^-\\gamma\\;\\mathrm{Ni}$, which is initiated by 190 GeV pions impinging on a nickel target. The exchange of quasi-real photons is selected by isolating the sharp Coulomb peak observed at smallest momentum transfers, $Q^2<0.0015$ (GeV/$c$)$^2$. From a sample of 63 000 events the pion electric polarisability is determined to be $\\alpha_\\pi = (2.0 \\pm 0.6_{\\mbox{stat}} \\pm 0.7_{\\mbox{syst}}) \\times 10^{-4} \\mbox{fm}^3$ under the assumption $\\alpha_\\pi=-\\beta_\\pi$, which relates the electric and magnetic dipole polarisabilities. It is the most precise measurement of this fundamental low-energy parameter of strong interaction, that has been addressed since long by various methods with conflicting outcomes. While this result is in tension with previous dedicated measurements, it is fou...

  8. The pion pole term in electroproduction of off-mass-shell pions

    International Nuclear Information System (INIS)

    McKellar, B.H.; Ellis, R.G.

    1983-01-01

    The dependence of the invariant amplitudes for electroproduction of off-mass-shell pions on the pion Born term is investigated when current algebra Ward identities and PCAC are used to determine pion electroproduction invariant amplitudes. The authors show that an amplitude satisfying the Ward identities can be constructed starting from the usual Born terms which do not satisfy them and that this same amplitude will be obtained for a large class of input Born terms

  9. Dosimetry of pion beams

    International Nuclear Information System (INIS)

    Dicello, J.F.

    1975-01-01

    Negative pion beams are probably the most esoteric and most complicated type of radiation which has been suggested for use in clinical radiotherapy. Because of the limited availability of pion beams in the past, even to nuclear physicists, there exist relatively fewer basic data for this modality. Pion dosimetry is discussed

  10. Autumn photoproduction of carbon monoxide in Jiaozhou Bay, China

    Science.gov (United States)

    Ren, Chunyan; Yang, Guipeng; Lu, Xiaolan

    2014-06-01

    Carbon monoxide (CO) plays a significant role in global warming and atmospheric chemistry. Global oceans are net natural sources of atmospheric CO. CO at surface ocean is primarily produced from the photochemical degradation of chromophoric dissolved organic matter (CDOM). In this study, the effects of photobleaching, temperature and the origin (terrestrial or marine) of CDOM on the apparent quantum yields (AQY) of CO were studied for seawater samples collected from Jiaozhou Bay. Our results demonstrat that photobleaching, temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The concentration, absorbance and fluorescence of CDOM exponentially decreased with increasing light dose. Terrestrial riverine organic matter could be more prone to photodegradation than the marine algae-derived one. The relationships between CO AQY and the dissolved organic carbon-specific absorption coefficient at 254 nm for the photobleaching study were nonlinear, whereas those of the original samples were strongly linear. This suggests that: 1) terrestrial riverine CDOM was more efficient than marine algae-derived CDOM for CO photoproduction; 2) aromatic and olefinic moieties of the CDOM pool were affected more strongly by degradation processes than by aliphatic ones. Water temperature and the origin of CDOM strongly affected the efficiency of CO photoproduction. The photoproduction rate of CO in autumn was estimated to be 31.98 μmol m-2 d-1 and the total DOC photomineralization was equivalent to 3.25%-6.35% of primary production in Jiaozhou Bay. Our results indicate that CO photochemistry in coastal areas is important for oceanic carbon cycle.

  11. Quarkonia Photoproduction at Nucleus Colliders

    International Nuclear Information System (INIS)

    D'Enterria, David

    2008-01-01

    Exclusive photoproduction of heavy quarkonia in high-energy ultraperipheral ion-ion interactions (γ A →V A, where V = J/ψ, Y and the nucleus A remains intact) offers a useful means to constrain the small-x nuclear gluon density. We discuss preliminary results on J/ψ photoproduction in Au-Au collisions at RHIC [D. d'Enterria [PHENIX Collaboration], Proceeds. Quark Matter'05, (arXiv:nucl-ex/0601001)], as well as full simulation-reconstruction studies of photo-produced Y in Pb-Pb interactions at the LHC [D. d'Enterria (ed.) et al. [CMS Collaboration], J. Phys. G. 34 2307 (2007)

  12. Fixed poles in electromagnetic processes and modification of Adler's neutrino sum rule due to quark anomalous magnetic moment

    International Nuclear Information System (INIS)

    Khare, A.

    1975-01-01

    We show that Adler's sum rule for neutrino scattering and Bjorken's inequality for electron-proton scattering are modified if quark has finite anomalous magnetic moment ksub(q). We also show that if ksub(q) is nonzero, there exist fixed poles in spin-flip Compton scattering as well as in charged pion photoproduction. (auth.)

  13. Pion polarizabilities measurement at COMPASS

    CERN Document Server

    Guskov, Alexey

    2008-01-01

    The electromagnetic structure of pions is probed in $\\pi^{−} + (A,Z)\\rightarrow\\pi^{−} + (A,Z) +\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\bar{\\alpha_{\\pi}})$ and the magnetic $(\\bar{\\beta_{\\pi}})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of pointlike pions with the measured cross section. The pion polarizability measurement was performed with $a \\pi^{−}$ beam of 190 GeV. The high beam intensity, the good spectrometer resolution, the high rate capability, the high acceptance and the possibility to use pion and muon beams, unique to the COMPASS experiment, provide the tools to measure precisely the pion polarizabilities in the Primakoff reaction. The preliminary result for pion polarizabilities under the assumption of $\\bar{\\alpha_{\\pi}} + \\bar{\\beta_{\\pi}} =$ 0 is $\\ba...

  14. Pion nucleus scattering lengths

    International Nuclear Information System (INIS)

    Huang, W.T.; Levinson, C.A.; Banerjee, M.K.

    1971-09-01

    Soft pion theory and the Fubini-Furlan mass dispersion relations have been used to analyze the pion nucleon scattering lengths and obtain a value for the sigma commutator term. With this value and using the same principles, scattering lengths have been predicted for nuclei with mass number ranging from 6 to 23. Agreement with experiment is very good. For those who believe in the Gell-Mann-Levy sigma model, the evaluation of the commutator yields the value 0.26(m/sub σ//m/sub π/) 2 for the sigma nucleon coupling constant. The large dispersive corrections for the isosymmetric case implies that the basic idea behind many of the soft pion calculations, namely, slow variation of matrix elements from the soft pion limit to the physical pion mass, is not correct. 11 refs., 1 fig., 3 tabs

  15. Far-UV-induced dimeric photoproducts in short oligonucleotides: sequence effects

    International Nuclear Information System (INIS)

    Douki, T.; Zalizniak, T.; Cadet, J.

    1997-01-01

    Cyclobutane pyrimidine dimers and pyrimidine (6-4)pyrimidone adducts represent the two major classes of far-UV-induced DNA photoproducts. Because of the lack of appropriate detection methods for each individual photoproduct, little is known about the effect of the sequence on their formaiton. In the present work, the photoproduct distribution obtained upon exposure of a series of dinucleoside monophosphate to 254 nm light was determined. (author)

  16. Pion polarizabilities measurement at COMPASS

    CERN Document Server

    Guskov, Alexey

    2008-01-01

    The electromagnetic structure of pions is probed in $\\pi^{−}+(A,Z) \\rightarrow\\pi^{−}+(A,Z)+\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric ($\\bar{\\alpha_{\\pi}}$) and the magnetic ($\\bar{\\beta_{\\pi}}$) polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of pointlike pions with the measured cross section. The pion polarizability measurement was performed with a $\\pi^{-}$ beam of 190 GeV. The high beam intensity, the good spectrometer resolution, the high rate capability, the high acceptance and the possibility to use pion and muon beams, unique to the COMPASS experiment, provide the tools to measure precisely the pion polarizabilities in the Primakoff reaction.

  17. Experimental study of the pion-xenon nucleus collisions at 3.5 GeV/c. Neutral pion production

    International Nuclear Information System (INIS)

    Strugalski, Z.; Abrosimov, A.T.; Wosinska, K.; Pawlak, T.; Nluta, J.; Sredniawa, B.; Il'ina, A.N.; Okhrimenko, L.S.; Peryt, W.; Miller, K.

    1983-01-01

    Experimental investigations of the neutral pion production are performed in pion-xenon collisions at 3.5 GeV/c. It is obtained that: 1) the average neutral pion multiplicity changes with the multiplicity of the protons emitted; 2) nearly 20% of the pions produced are emitted into the backward hemisphere; 3) the energy spectrum of the neutral pions is smooth; 4) the longitudinal component of the neutral pion momentum changes within the limits from -600 MeV/c to +1800 MeV/c; 5) the average value of the transversal component of the neutral pion momentum changes with the multiplicity of the protons emitted from approximately 270 to approximately 170 MeV/c; 6) the average value of the cosine of the neutral pion emission angle decreases with the multiplicity of the protons emitted

  18. Analytic coupling and Sudakov effects in exclusive processes: pion and γ*γ→π0 form factors

    International Nuclear Information System (INIS)

    Stefanis, N.G.

    2000-01-01

    We develop and discuss in technical detail an infrared-finite factorization and optimized renormalization scheme for calculating exclusive processes, which enables the inclusion of transverse degrees of freedom without entailing suppression of calculated observables, like form factors. This is achieved by employing an analytic, i.e., infrared stable, running strong-coupling α s (Q 2 ) which removes the Landau singularity at Q 2 =Λ QCD 2 by a minimum power-behaved correction. The ensuing contributions to the cusp anomalous dimension - related to the Sudakov form factor - and to the quark anomalous dimension - which controls evolution - lead to an enhancement at high Q 2 of the hard part of exclusive amplitudes, calculated in perturbative QCD, while simultaneously improving its scaling behavior. The phenomenological implications of this framework are analyzed by applying it to the pion's electromagnetic form factor, including the NLO contribution to the hard-scattering amplitude, and also to the pion-photon transition at LO. For the pion wave function, an improved ansatz of the Brodsky-Huang-Lepage type is employed, which includes an effective (constituent-like) quark mass, m q =0.33 GeV. Predictions for both form factors are presented and compared to the experimental data, applying Brodsky-Lepage-Mackenzie commensurate scale setting. We find that the perturbative hard part prevails at momentum transfers above about 20 GeV 2 , while at lower Q 2 values the pion form factor is dominated by Feynman-type contributions. The theoretical prediction for the γ * γ→π 0 form factor indicates that the true pion distribution amplitude may be somewhat broader than the asymptotic one. (orig.)

  19. Fermi motion versus co-operative effects in subthreshold pion and energetic gamma production

    International Nuclear Information System (INIS)

    Knoll, J.

    1986-06-01

    Various reaction mechanisms proposed to explain the production of pions at 'sub-threshold' energies and of energetic gammas are examined. They range from the nucleon-nucleon single collision mechanism to a co-operative multi-nucleon process. With a shell model prescription for the initial state energies the single collision picture cannot explain the data. The participation of many nucleons in the pion production process appears to be necessary. We present a statistical model which demands the co-operative action of several of the target and projectile nucleons in the pion production process. The formation of composite fragments alongside with the produced pion is seen to be vital to understand the experimental data within this model. (orig.)

  20. The pion polarisability and more measurements on chiral dynamics at COMPASS

    CERN Document Server

    Friedrich, Jan

    2016-01-01

    Within the physics program of the COMPASS experiment at CERN pion-photon reactions are measured via the Primakoff effect, referring to processes in which high-energetic pions react with the quasi-real photon field that surrounds the target nuclei. The production of a single hard photon in such a pion scattering at lowest momentum transfer to the nucleus is related to pion Compton scattering. From the measured cross-section shape, the pion polarisability has been determined, a result that has been published meanwhile as a Physical Review Letter [ 1 ]. The COMPASS measurement is in tension with the earlier dedicated measurements, and rather in agreement with the theoretical expectation from chiral perturbation theory. The analysis of a more recent high-statistics data taking is underway. Reactions with neutral and more charged pions in the final state are measured and analyzed as well. At low energy in the pion-photon centre-of-momentum system, these reactions are governed by chiral dynamics and contain informa...

  1. Improved pion pion scattering amplitude from dispersion relation formalism

    International Nuclear Information System (INIS)

    Cavalcante, I.P.; Coutinho, Y.A.; Borges, J. Sa

    2005-01-01

    Pion-pion scattering amplitude is obtained from Chiral Perturbation Theory at one- and two-loop approximations. Dispersion relation formalism provides a more economic method, which was proved to reproduce the analytical structure of that amplitude at both approximation levels. This work extends the use of the formalism in order to compute further unitarity corrections to partial waves, including the D-wave amplitude. (author)

  2. Coupled-channel analysis for phi photoproduction with Lambda

    NARCIS (Netherlands)

    Ozaki, S.; Hosaka, A.; Nagahiro, H.; Scholten, O.

    We investigate photoproduction of phi mesons off protons within a coupled-channel effective-Lagrangian method which is based on the K-matrix approach. Since the threshold energy of the K Lambda(1520) channel is close to that of phi N, the contribution of this channel to f photoproduction near the

  3. Heavy quarks photoproduction

    International Nuclear Information System (INIS)

    Cacciari, M.

    1996-08-01

    The state of the art of the theoretical calculations for heavy quarks photoproduction is reviewed. The full next-to-leading order calculation and two possible resummations, the high energy one for total cross sections and the large p T one for differential cross sections, are described. (orig.)

  4. Pion production in nuclei

    International Nuclear Information System (INIS)

    Afnan, I.R.; Thomas, A.W.

    1976-01-01

    A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)

  5. Coherent diffractive photoproduction of ρ0 mesons on gold nuclei at 200 GeV/nucleon-pair at the Relativistic Heavy Ion Collider

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Ajitanand, N. N.; Alekseev, I.; Anderson, D. M.; Aoyama, R.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Ashraf, M. U.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Behera, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Brown, D.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chankova-Bunzarova, N.; Chatterjee, A.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elsey, N.; Engelage, J.; Eppley, G.; Esha, R.; Esumi, S.; Evdokimov, O.; Ewigleben, J.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Federicova, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A. I.; Hamed, A.; Harlenderova, A.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, B.; Huang, X.; Huang, H. Z.; Humanic, T. J.; Huo, P.; Igo, G.; Jacobs, W. W.; Jentsch, A.; Jia, J.; Jiang, K.; Jowzaee, S.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Klein, S. R.; Kochenda, L.; Kocmanek, M.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulathunga, N.; Kumar, L.; Kvapil, J.; Kwasizur, J. H.; Lacey, R.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, W.; Li, Y.; Lidrych, J.; Lin, T.; Lisa, M. A.; Liu, H.; Liu, P.; Liu, Y.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, S.; Luo, X.; Ma, G. L.; Ma, L.; Ma, Y. G.; Ma, R.; Magdy, N.; Majka, R.; Mallick, D.; Margetis, S.; Markert, C.; Matis, H. S.; Meehan, K.; Mei, J. C.; Miller, Z. W.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mizuno, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nie, M.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Nonaka, T.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Ray, R. L.; Reed, R.; Rehbein, M. J.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roth, J. D.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Saur, M.; Schambach, J.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Schweid, B. R.; Seger, J.; Sergeeva, M.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, A.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Strikhanov, M.; Stringfellow, B.; Sugiura, T.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Tang, A. H.; Tang, Z.; Taranenko, A.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vasiliev, A. N.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, G.; Wang, Y.; Wang, F.; Wang, Y.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y. F.; Xu, Z.; Yang, Y.; Yang, Q.; Yang, C.; Yang, S.; Ye, Z.; Ye, Z.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Z.; Zhang, X. P.; Zhang, J. B.; Zhang, S.; Zhang, J.; Zhang, Y.; Zhang, J.; Zhang, S.; Zhao, J.; Zhong, C.; Zhou, L.; Zhou, C.; Zhu, X.; Zhu, Z.; Zyzak, M.; STAR Collaboration

    2017-11-01

    The STAR Collaboration reports on the photoproduction of π+π- pairs in gold-gold collisions at a center-of-mass energy of 200 GeV/nucleon-pair. These pion pairs are produced when a nearly real photon emitted by one ion scatters from the other ion. We fit the π+π- invariant-mass spectrum with a combination of ρ0 and ω resonances and a direct π+π- continuum. This is the first observation of the ω in ultraperipheral collisions, and the first measurement of ρ -ω interference at energies where photoproduction is dominated by Pomeron exchange. The ω amplitude is consistent with the measured γ p →ω p cross section, a classical Glauber calculation, and the ω →π+π- branching ratio. The ω phase angle is similar to that observed at much lower energies, showing that the ρ -ω phase difference does not depend significantly on photon energy. The ρ0 differential cross section d σ /d t exhibits a clear diffraction pattern, compatible with scattering from a gold nucleus, with two minima visible. The positions of the diffractive minima agree better with the predictions of a quantum Glauber calculation that does not include nuclear shadowing than with a calculation that does include shadowing.

  6. Evidence for the monomerization of spore photoproduct to two thymines by the light-independent 'spore repair' process in Bacillus subtilis

    International Nuclear Information System (INIS)

    Van Wang, T.-C.; Rupert, C.S.

    1977-01-01

    Ultraviolet irradiation of bacterial spores induces a unique DNA photoproduct, which yields mostly 5-thyminyl-5,6-dihydrothymine (Thy(α-5)hThy, or TDHT) on acid hydrolysis. One of the possible mechanisms for the observed removal of the photoproduct on spore germination ivolves its direct conversion back to two adjacent thymine residues, and additional evidence is presented in support of this theory. Studies were made of the fate of the TDHT radioactivity in irradiated, germinated B. subtilis spores labelled with 3 H-thymine or 14 C-thymine, and of the homogeneity of the thymine-peak radioactivity. The radioactivity disappearing from the TDHT peak on germination seemed to be stoichiometrically recovered in the thymine peak, and no new materials were detected under the thymine-peak radioactivity. No intermediates were detected in B. subtilis mutant 25D4 (hcr 42 - recA 1 - ), a strain which had given some promise of accumulating intermediates from an incomplete repair process. (U.K.)

  7. Meson photoproduction (CLAS)

    Energy Technology Data Exchange (ETDEWEB)

    Steffen Strauch

    2009-10-01

    This is a brief and selective discussion of meson photoproduction measurements with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Meson photo- production is being used as a tool for various investigations, including the spectroscopy of baryons and mesons and the search for vector-meson medium modifications.

  8. Study of subthreshold pion mesons of 86Kr + 197Au reaction

    International Nuclear Information System (INIS)

    Ma Yugang; Shen Wenqing; Ge Lingxiao; Zhan Wenlong; Wang Bing; Zhu Yongtai; Feng Jun; Zeng Yaowu; Guo Zhongyan; Zhou Jianqun

    1991-01-01

    Authors investigated the subthreshold pions multiplicity for 86 Kr + 197 Au system in non-relativistic BUU frame. The aims were to obtain some qualitative conclusions about pions production and absorption process. Because the production of pions and other energetic particles are a very complicated problem in HIC, nowadays a full self-consistent and effective theoretical approach has not yet been presented, the more detail and further research work must be done

  9. Low energy scattering with a nontrivial pion

    International Nuclear Information System (INIS)

    Fariborz, Amir H.; Jora, Renata; Schechter, Joseph

    2007-01-01

    An earlier calculation in a generalized linear sigma model showed that the well-known current algebra formula for low energy pion-pion scattering held even though the massless Nambu Goldstone pion contained a small admixture of a two-quark two-antiquark field. Here we turn on the pion mass and note that the current algebra formula no longer holds exactly. We discuss this small deviation and also study the effects of a SU(3) symmetric quark mass type term on the masses and mixings of the eight SU(3) multiplets in the model. We calculate the s-wave scattering lengths, including the beyond current algebra theorem corrections due to the scalar mesons, and observe that the effect of the scalar mesons is to improve the agreement with experiment. In the process, we uncover the way in which linear sigma models give controlled corrections (due to the presence of scalar mesons) to the current algebra scattering formula. Such a feature is commonly thought to exist only in the nonlinear sigma model approach

  10. Pion condensation in symmetric nuclear matter

    International Nuclear Information System (INIS)

    Shamsunnahar, T.; Saha, S.; Kabir, K.; Nath, L.M.

    1991-01-01

    We have investigated the possibility of pion condensation in symmetric nuclear matter using a model of pion-nucleon interaction based essentially on chiral SU(2) x SU(2) symmetry. We have found that pion condensation is not possible for any finite value of the density. Consequently, no critical opalescence phenomenon is likely to be seen in pion-nucleus scattering nor is it likely to be possible to explain the EMC effect in terms of an increased number of pions in the nucleus. (author)

  11. Invariant potential for elastic pion--nucleus scattering. Technical report No. 75-075

    International Nuclear Information System (INIS)

    Cammarata, J.B.; Banerjee, M.K.

    1975-04-01

    From the Wick-Dyson expansion of the exact propagator of a pion in the presence of a nucleus an invariant potential for crossing symmetric, elastic pion-nucleus scattering is obtained in terms of a series of pion-nucleon diagrams. The Chew-Low theory is used to develop a model in which the most important class of diagrams is effectively summed. Included in this model is the Exclusion Principle restriction on the pion-bound nucleon interaction, the effects of the binding of nucleons, a kinematic transformation of energy from the lab to the πN center of mass frames, and the Fermi motion and recoil of the target nucleons. From a numerical study of the effects of these processes on the π- 12 C total cross section, the relative importance of each is determined. Other processes contributing to the elastic scattering of pions not included in the present model are also discussed. (9 figures) (U.S.)

  12. Pion-induced knock-out reactions

    International Nuclear Information System (INIS)

    Jain, B.K.; Phatak, S.C.

    1977-01-01

    A strong absorption model for pion-induced Knock-out reactions is proposed. The distortion of the in-coming and out-going pions has been included by (1) computing pion wave number in nuclear medium (dispersive effect) and (2) excluding the central region of the nucleus where the real pion-absorption is dominant (absorption effect). In order to study the dependence of the (π + π + p) reaction on the off-shell pion-nucleon t-matrix, different off-shell extrapolations are used. The magnitude of the cross-sections seems to be sensitive to the type of off-shell extrapolation; their shapes, however, are similar. The theoretical results are compared with experimental data. The agreement between the theoretical results for separable off-shell extrapolation and the data is good. (author)

  13. Real and virtual pions in nuclei

    International Nuclear Information System (INIS)

    Giraud, N.

    1984-02-01

    The thesis first part is concerned with physical pion interaction with deuton, studied in a three-body problem frame. The elastic cross-section in the energy range near the resonance (3-3), has been deduced taking in account the pion virtual absorption. The second part is concerned with virtual pion in nuclei. In particular the virtual pion cloud around the nucleus has been studied and the effective constant coupling pion-nucleus has been deduced. This one is strongly reduced by polorazation effects of the nuclear medium (essentially by virtual excitation of the Δ isobar), in relation to its value for free nucleon collection. In the frame of the same polarization model, the pion field inside the nucleus has been studied also. This field is lowered for small momentum transfer. It is increased for large momentum transfer. This last phenomenon corresponds to critical opalescence related to phase transition of pion condensation [fr

  14. Quarkonium momentum distributions in photoproduction and B decay

    CERN Document Server

    Beneke, Martin; Wolf, S

    2000-01-01

    According to our present understanding many $J/\\psi$ production processes proceed through a coloured $c\\bar{c}$ state followed by the emission of soft particles in the quarkonium rest frame. The kinematic effect of soft particle emission is usually a higher-order effect in the non-relativistic expansion, but becomes important near the kinematic endpoint of quarkonium energy (momentum) distributions. In an intermediate region a systematic resummation of the non-relativistic expansion leads to the introduction of so-called `shape functions'. In this paper we provide an implementation of the kinematic effect of soft gluon emission which is consistent with the non-relativistic shape function formalism in the region where it is applicable and which models the extreme endpoint region. We then apply the model to photoproduction of $J/\\psi$ and $J/\\psi$ production in $B$ meson decay. A satisfactory description of $B$ decay data is obtained. For inelastic charmonium photoproduction we conclude that a sensible comparis...

  15. Analyses of multi-pion Hanbury Brown–Twiss correlations for the pion-emitting sources with Bose–Einstein condensation

    Science.gov (United States)

    Bary, Ghulam; Ru, Peng; Zhang, Wei-Ning

    2018-06-01

    We calculate the three- and four-particle correlations of identical pions in an evolving pion gas (EPG) model with Bose–Einstein condensation. The multi-pion correlation functions in the EPG model are analyzed in different momentum intervals and compared with the experimental data for Pb–Pb collisions at \\sqrt{{s}{NN}}=2.76 {TeV}. It is found that the multi-pion correlation functions and cumulant correlation functions are sensitive to the condensation fraction of the EPG sources in the low average transverse-momentum intervals of the three and four pions. The model results of the multi-pion correlations are consistent with the experimental data in a considerable degree, which gives a source condensation fraction between 16% and 47%.

  16. Measurement of the pion form factor

    International Nuclear Information System (INIS)

    Dally, E.; Hauptman, J.; May, C.

    1977-01-01

    The pion form factor has been measured in the momentum transfer range of 0.03( 2 by scattering pions from atomic electrons in a liquid hydrogen target. The pion form factor is defined to be the elastic scattering cross section divided by that predicted for a point pion. The experiment has been performed in a 100 GeV/c negative pion beam incident on a 50 cm liquid hydrogen target at Fermi laboratory. The corrected form factor equals 0.33+-0.06 f 2 . Vector dominance predicts 0.40 f 2

  17. Vector meson photoproduction with a linearly polarized beam

    Science.gov (United States)

    Mathieu, V.; Nys, J.; Fernández-Ramírez, C.; Jackura, A.; Pilloni, A.; Sherrill, N.; Szczepaniak, A. P.; Fox, G.; Joint Physics Analysis Center

    2018-05-01

    We propose a model based on Regge theory to describe photoproduction of light vector mesons. We fit the SLAC data and make predictions for the energy and momentum-transfer dependence of the spin-density matrix elements in photoproduction of ω , ρ0 and ϕ mesons at Eγ˜8.5 GeV , which are soon to be measured at Jefferson Lab.

  18. Spectator-velocity pions from heavy ions

    International Nuclear Information System (INIS)

    Rasmussen, J.; Ridout, J.; Murphy, D.; Radi, H.M.A.

    1982-11-01

    The discussion centers on pions in the velocity regions of target and projectile, where strong spectral features appear. The topics covered include stopped-pion studies, and convoy pions in the projectile frame

  19. Can one distinguish T-neutrinos from antineutrinos in neutral-current pion production processes?

    OpenAIRE

    Hernández Gajate, Eliecer; Nieves Pamplona, Juan Miguel; Valverde Hermosilla, Manuel

    2007-01-01

    A potential way to distinguish tau-neutrinos from antineutrinos, below the tau-production threshold, but above the pion production one, is presented. It is based on the different behavior of the neutral-current pion production off the nucleon, depending on whether it is induced by neutrinos or antineutrinos. This procedure for distinguishing tau-neutrinos from antineutrinos neither relies on any nuclear model, nor it is affected by any nuclear effect (distortion of the outgoing nucleon waves,...

  20. Photoproduction at collider energies: from RHIC and HERA to the LHC

    CERN Document Server

    Baltz, A; Brodsky, S J; D'Enterria, D G; Dreyer, U; Engel, R; Frankfurt, L; Gorbunov, Y; Guzey, V; Hamilton, A; Klasen, M; Klein, S R; Kowalski, H; Levonian, S; Lourenço, C; Machado, M V T; Nachtmann, O; Nagy, Z; Nystrand, J; Piotrzkowski, K; Ramalhete, P; Savin, A; Scapparone, E; Schicker, R; Silvermyr, D; Strikman, M I; Valkárová, A; Vogt, R; Yilmaz, M; Enterria, David d'

    2007-01-01

    We present the mini-proceedings of the workshop on "Photoproduction at collider energies: from RHIC and HERA to the LHC" held at the European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*, Trento) from January 15 to 19, 2007. The workshop gathered both theorists and experimentalists to discuss the current status of investigations of high-energy photon-induced processes at different colliders (HERA, RHIC, and Tevatron) as well as preparations for extension of these studies at the LHC. The main physics topics covered were: (i) small-$x$ QCD in photoproduction studies with protons and in electromagnetic (aka. ultraperipheral) nucleus-nucleus collisions, (ii) hard diffraction physics at hadron colliders, and (iii) photon-photon collisions at very high energies: electroweak and beyond the Standard Model processes. These mini-proceedings consist of an introduction and short summaries of the talks presented at the meeting.

  1. J/ψ photoproduction in ultra-peripheral Pb-Pb and p-Pb collisions with the ALICE detector

    Directory of Open Access Journals (Sweden)

    Adam Jaroslav

    2014-04-01

    Full Text Available Ultra-relativistic heavy ions generate strong electromagnetic fields which offer the possibility to study gamma-gamma, gamma-nucleus and gamma-proton processes at the LHC in ultra-peripheral Pb-Pb and p-Pb collisions. Exclusive photoproduction of J/ψ vector mesons is sensitive to the gluon distribution of the target. Here we report on the ALICE measurement of J/ψ coherent photoproduction in Pb-Pb ultra-peripheral collisions at √sNN = 2.76 TeV for the rapidity ranges -3.6 < y < -2.6 and |y| < 0.9, and on preliminary results on the J/ψ photoproduction in p-Pb at √sNN = 5.02 TeV. The J/ψ mesons have been identified through their leptonic decays.

  2. Photoproduction of hydroxyl radicals in aqueous solution with algae under high-pressure mercury lamp.

    Science.gov (United States)

    Liu, Xianli; Wu, Feng; Deng, Nansheng

    2004-01-01

    Photoproduction of hydroxyl radicals (*OH) could be induced in aqueous solution with algae (Nitzschia hantzschiana, etc.) and (or not) Fe3+ under high-pressure mercury lamp with an exposure time of 4 h. *OH was determined by HPLC using benzene as a probe. The photoproduction of *OH increased with increasing algae concentration. Fe3+ could enhance the photoproduction of *OH in aqueous solution with algae. The results showed that the photoproduction of *OH in algal solution with Fe3+ was greater than that in algal solution without Fe3+. The light intensity and pH affected the photoproduction of *OH in aqueous solution with algae with/without Fe3+. The photoproduction of *OH in aqueous solution with algae and Fe3+ under 250 W was greater than that under 125 W HPML. The photoproduction of *OH in algal solution (pH ranged from 4.0 to 7.0) with (or not) Fe3+ at pH 4 was the greatest.

  3. Pion condensation in symmetric nuclear matter

    Science.gov (United States)

    Kabir, K.; Saha, S.; Nath, L. M.

    1988-01-01

    Using a model which is based essentially on the chiral SU(2)×SU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenom is expected to be seen in the pion-nucleus interaction.

  4. Pion-nucleon scattering: from chiral perturbation theory to Roy-Steiner equations

    Science.gov (United States)

    Kubis, Bastian; Hoferichter, Martin; de Elvira, Jacobo Ruiz; Meißner, Ulf-G.

    2016-11-01

    Ever since Weinberg's seminal predictions of the pion-nucleon scattering amplitudes at threshold, this process has been of central interest for the study of chiral dynamics involving nucleons. The scattering lengths or the pion-nucleon σ-term are fundamental quantities characterizing the explicit breaking of chiral symmetry by means of the light quark masses. On the other hand, pion-nucleon dynamics also strongly affects the long-range part of nucleon-nucleon potentials, and hence has a far-reaching impact on nuclear physics. We discuss the fruitful combination of dispersion-theoretical methods, in the form of Roy-Steiner equations, with chiral dynamics to determine pion-nucleon scattering amplitudes at low energies with high precision.*

  5. Pion production in nucleus--nucleus collisions

    International Nuclear Information System (INIS)

    Schroeder, L.S.

    1975-06-01

    Current work on pion production in high-energy nucleus-nucleus collisions is reviewed. The majority of existing data are of the inclusive variety in which a single final state pion is detected. Experimental data are compared and their possible contributions to obtaining new information on nuclear structure is discussed. Various models which attempt to explain the observed single-inclusive-pion spectra either on the basis of a nucleon-nucleus interaction in which Fermi motion is included or on some type of cooperative model are examined. Other areas of interest involving pion production include tests of charge symmetry and pion multiplicities. (9 figures, 1 table) (U.S.)

  6. Pion condensation in symmetric nuclear matter

    International Nuclear Information System (INIS)

    Kabir, K.; Saha, S.; Nath, L.M.

    1987-09-01

    Using a model which is based essentially on the chiral SU(2)xSU(2) symmetry of the pion-nucleon interaction, we examine the possibility of pion condensation in symmetric nucleon matter. We find that the pion condensation is not likely to occur in symmetric nuclear matter for any finite value of the nuclear density. Consequently, no critical opalescence phenomenon is expected to be seen in the pion-nucleus interaction. (author). 20 refs

  7. Measurement of Charged Current Coherent Pion Production by Neutrinos on Carbon at MINER$\

    Energy Technology Data Exchange (ETDEWEB)

    Mislivec, Aaron Robert [Univ. of Rochester, NY (United States)

    2017-01-01

    Neutrino-nucleus coherent pion production is a rare neutrino scattering process where the squared four-momentum transferred to the nucleus is small, a lepton and pion are produced in the forward direction, and the nucleus remains in its initial state. This process is an important background in neutrino oscillation experiments. Measurements of coherent pion production are needed to constrain models which are used to predict coherent pion production in oscillation experiments. This thesis reports measurements of νµ and νµ charged current coherent pion production on carbon for neutrino energies in the range 2 < Eν < 20 GeV. The measurements were made using data from MINERνA, which is a dedicated neutrino-nucleus scattering experiment that uses a fi scintillator tracking detector in the high-intensity NuMI neutrino beam at Fermilab. Coherent interactions were isolated from the data using only model-independent signatures of the reaction, which are a forward muon and pion, no evidence of nuclear breakup, and small four-momentum transfer to the nucleus. The measurements were compared to the coherent pion production model used by oscillation experiments. The data and model agree in the total interaction rate and are similar in the dependence of the interaction rate on the squared four- momentum transferred from the neutrino. The data and model disagree significantly in the pion kinematics. The measured νµ and νµ interaction rates are consistent, which supports model predictions that the neutrino and antineutrino interaction rates are equal.

  8. Quark bag coupling to finite size pions

    International Nuclear Information System (INIS)

    De Kam, J.; Pirner, H.J.

    1982-01-01

    A standard approximation in theories of quark bags coupled to a pion field is to treat the pion as an elementary field ignoring its substructure and finite size. A difficulty associated with these treatments in the lack of stability of the quark bag due to the rapid increase of the pion pressure on the bad as the bag size diminishes. We investigate the effects of the finite size of the qanti q pion on the pion quark bag coupling by means of a simple nonlocal pion quark interaction. With this amendment the pion pressure on the bag vanishes if the bag size goes to zero. No stability problems are encountered in this description. Furthermore, for extended pions, no longer a maximum is set to the bag parameter B. Therefore 'little bag' solutions may be found provided that B is large enough. We also discuss the possibility of a second minimum in the bag energy function. (orig.)

  9. Measurement of the charged pion polarizability at COMPASS

    International Nuclear Information System (INIS)

    Nagel, Thiemo Christian Ingo

    2012-01-01

    The reaction π - +Z→π - +γ+Z in which a photon is produced by a beam pion scattering off a quasi-real photon of the Coulomb field of the target nucleus is identified experimentally by the tiny magnitude of the momentum transfer to the nucleus. This process gives access to the charged pion polarizabilities α π and β π whose experimental determination constitutes an important test of Chiral Perturbation Theory. In this work, the pion polarizability is obtained as α π =(1.9±0.7 stat. ±0.8 syst. ) x 10 -4 fm 3 from data taken with 190 GeV/c hadron beam provided by SPS to the COMPASS experiment at CERN in November 2009 and under the assumption of α π +β π =0.

  10. Correlations and self-consistency in pion scattering. II

    International Nuclear Information System (INIS)

    Johnson, M.B.; Keister, B.D.

    1978-01-01

    In an attempt to overcome certain difficulties of summing higher order processes in pion multiple scattering theories, a new, systematic expansion for the interaction of a pion in nuclear matter is derived within the context of the Foldy-Walecka theory, incorporating nucleon-nucleon correlations and an idea of self-consistency. The first two orders in the expansion are evaluated as a function of the nonlocality range; the expansion appears to be rapidly converging, in contrast to expansion schemes previously examined. (Auth.)

  11. Twist-2 Light-Cone Pion Wave Function

    OpenAIRE

    Belyaev, V. M.; Johnson, Mikkel B.

    1997-01-01

    We present an analysis of the existing constraints for the twist-2 light-cone pion wave function. We find that existing information on the pion wave function does not exclude the possibility that the pion wave function attains its asymptotic form. New bounds on the parameters of the pion wave function are presented.

  12. Pion inelastic scattering and the pion-nucleus effective interaction

    International Nuclear Information System (INIS)

    Carr, J.A.

    1983-01-01

    This work examines pion inelastic scattering with the primary purpose of gaining a better understanding of the properties of the pion-nucleus interaction. The main conclusion of the work is that an effective interaction which incorporates the most obvious theoretical corrections to the impulse approximation does a good job of explaining pion elastic and inelastic scattering from zero to 200 MeV without significant adjustments to the strength parameters of the force. Watson's multiple scattering theory is used to develop a theoretical interaction starting from the free pion-nucleon interaction. Elastic scattering was used to calibrate the isoscalar central interaction. It was found that the impulse approximation did poorly at low energy, while the multiple scattering corrections gave good agreement with all of the data after a few minor adjustments in the force. The distorted wave approximation for the inelastic transition matrix elements are evaluated for both natural and unnatural parity excitations. The isoscalar natural parity transitions are used to test the reaction theory, and it is found that the effective interaction calibrated by elastic scattering produces good agreement with the inelastic data. Calculations are also shown for other inelastic and charge exchange reactions. It appears that the isovector central interaction is reasonable, but the importance of medium corrections cannot be determined. The unnatural parity transitions are also reasonably described by the theoretical estimate of the spin-orbit interaction, but not enough systematic data exists to reach a firm conclusion

  13. Pion observables and QCD

    International Nuclear Information System (INIS)

    Roberts, C.D.

    1995-01-01

    Herein the application of the DSE approach to the calculation of pion observables is described using: the π-π scattering lengths (a 0 0 , a 2 0 , a 1 1 , a 0 2 , a 2 2 ) and associated partial wave amplitudes; the π 0 → γγ decay width; and the charged pion form factor, F π (q 2 ), as illustrative examples. Since this approach provides a straightforward, microscopic description of dynamical chiral symmetry breaking (DχSB) and confinement, the calculation of pion observables is a simple and elegant illustrative example of its power and efficacy. (orig.)

  14. MEASUREMENT OF POLARIZATION OBSERVABLES IN VECTOR MESON PHOTOPRODUCTION USING A TRANSVERSELY-POLARIZED FROZEN-SPIN TARGET AND POLARIZED PHOTONS AT CLAS, JEFFERSON LAB

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Priyashree [Florida State Univ., Tallahassee, FL (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-11-30

    The study of baryon resonances provides a deeper understanding of the strong interaction because the dynamics and relevant degrees of freedom hidden within them are re ected by the properties of the excited states of baryons. Higher-lying excited states at and above 1.7 GeV/c2 are generally predicted to have strong couplings to final states involving a heavier meson, e. g. one of the vector mesons, ρ, ω φ, as compared to a lighter pseudoscalar meson, e. g. π and η. Decays to the ππΝ final states via πΔ also become more important through the population of intermediate resonances. We observe that nature invests in mass rather than momentum. The excited states of the nucleon are usually found as broadly overlapping resonances which may decay into a multitude of final states involving mesons and baryons. Polarization observables make it possible to isolate single resonance contributions from other interference terms. The CLAS g9 (FROST) experiment, as part of the N* spectroscopy program at Je?erson Laboratory, accumulated photoproduction data using circularly- & linearly-polarized photons incident on a transversely-polarized butanol target (g9b experiment) in the photon energy range 0:3-2:4 GeV & 0:7-2:1 GeV, respectively. In this work, the analysis of reactions and polarization observables which involve two charged pions, either in the fully exclusive reaction γρ -> ρπ+π- or in the semi-exclusive reaction with a missing neutral pion, γρ -> ρπ+π-(π0) will be presented. For the reaction ρπ+π-, eight polarization observables (Is, Ic, Px, Py, Psx; y, Pcx; y) have been extracted. The high statistics data rendered it possible to extract these observables in three dimensions. All of them are first-time measurements. The fairly good agreement of Is, Ic obtained from this analysis with the experimental results from a previous CLAS experiment provides support for the first-time measurements. For the reaction γρ -> ρω -> ρπ+π(π0, five polarization

  15. Search for Odderon induced contributions to exclusive Meson Photoproduction at HERA

    International Nuclear Information System (INIS)

    Olsson, J.

    2001-01-01

    A search for exclusive photoproduction of π 0 , f 2 (1270) and a 2 (1320), induced by Odderon exchange, was performed using multi-photon final states. No signal was found. Upper limits for the cross sections are below the predictions of a model based on non-perturbative QCD. Exclusive ω and ωπ 0 photoproduction is observed in three and five photon final states, at levels consistent with the expectations from Pomeron exchange and consistent with other observations of exclusive vector and axial vector meson photoproduction

  16. Reaction mechanism and nuclear correlations study by low energy pion double charge exchange

    International Nuclear Information System (INIS)

    Weinfeld, Z.

    1993-06-01

    In pion double-charge-exchange (DCX) reactions, a positive (negative) pion is incident on a nucleus and a negative (positive) pion emerges. These reactions are of fundamental interest since the process must involve at least two nucleons in order to conserve charge. Although two nucleon processes are present in many reactions they are usually masked by the dominant single nucleon processes. DCX is unique in that respect since it is a two nucleon process in lowest order and thus may be sensitive to two-nucleon correlations. Measurements of low energy pion double-charge-exchange reactions to the double-isobaric-analog-state (DIAS) and ground-state (GS) of the residual nucleus provide new means for studying nucleon-nucleon correlations in nuclei. At low energies (T π 7/2 shell at energies ranging from 25 to 65 MeV. Cross sections were measured on 42,44,48 Ca, 46,50 Ti and 54 Fe. The calcium isotopes make a good set of nuclei on which to study the effects of correlations in DCX reactions

  17. Measurement of the charged pion polarizability at COMPASS

    Energy Technology Data Exchange (ETDEWEB)

    Nagel, Thiemo Christian Ingo

    2012-09-26

    The reaction {pi}{sup -}+Z{yields}{pi}{sup -}+{gamma}+Z in which a photon is produced by a beam pion scattering off a quasi-real photon of the Coulomb field of the target nucleus is identified experimentally by the tiny magnitude of the momentum transfer to the nucleus. This process gives access to the charged pion polarizabilities {alpha}{sub {pi}} and {beta}{sub {pi}} whose experimental determination constitutes an important test of Chiral Perturbation Theory. In this work, the pion polarizability is obtained as {alpha}{sub {pi}}=(1.9{+-}0.7{sub stat.}{+-}0.8{sub syst.}) x 10{sup -4} fm{sup 3} from data taken with 190 GeV/c hadron beam provided by SPS to the COMPASS experiment at CERN in November 2009 and under the assumption of {alpha}{sub {pi}}+{beta}{sub {pi}}=0.

  18. Characteristic aspects of pion-condensed phases

    International Nuclear Information System (INIS)

    Takatsuka, Tatsuyuki; Tamagaki, Ryozo; Tatsumi, Toshitaka.

    1993-01-01

    Characteristic aspects of pion-condensed phases are described in a simple model, for the system involving only nucleons and pions which interact through the π-N P-wave interaction. We consider one typical version in each of three kinds of pion condensation; the one of neutral pions (π 0 ), the one of charged pions (π C ) and the combined one in which both the π 0 and π C condensations are coexistent. Emphasis is put on the description to clarify the novel structures of the nucleon system which are realized in the pion-condensed phases. At first, it is shown that the π 0 condensation is equivalent to the particular nucleonic phase realized by a structure change of the nucleon system, where the attractive first-order effect of the one-pion-exchange (OPE) tensor force is brought about coherently. The aspects of this phase are characterized by the layered structure with a specific spin-isospin order with one-dimensional localization (named the ALS structure in short), which provides the source function for the condensed π 0 field. We utilize both descriptions with use of fields and potentials for the π 0 condensation. Next, the π C condensation realized in neutron-rich matter is described by adopting a version of the traveling condensed wave. In this phase, the nucleonic structure becomes the Fermi gas consisting of quasi-neutrons described by a superposition of neutron and proton. In this sense the structure change of the nucleon system for the π C condensation is moderate, and the field description is suitable. Finally, we describe a coexistent pion condensation, in which both the π 0 and π C condensations coexist without interference in such a manner that the π C condensation develops in the ALS structure. The model adopted here provides us with the characteristic aspects of the pion-condensed phases persisting in the realistic situation, where other ingredients affecting the pion condensation are taken into account. (author)

  19. The pion: an enigma within the Standard Model

    Energy Technology Data Exchange (ETDEWEB)

    Horn, Tanja; Roberts, Craig D.

    2016-05-27

    Almost 50 years after the discovery of gluons & quarks, we are only just beginning to understand how QCD builds the basic bricks for nuclei: neutrons, protons, and the pions that bind them. QCD is characterised by two emergent phenomena: confinement & dynamical chiral symmetry breaking (DCSB). They are expressed with great force in the character of the pion. In turn, pion properties suggest that confinement & DCSB are closely connected. As both a Nambu-Goldstone boson and a quark-antiquark bound-state, the pion is unique in Nature. Developing an understanding of its properties is thus critical to revealing basic features of the Standard Model. We describe experimental progress in this direction, made using electromagnetic probes, highlighting both improvements in the precision of charged-pion form factor data, achieved in the past decade, and new results on the neutral-pion transition form factor. Both challenge existing notions of pion structure. We also provide a theoretical context for these empirical advances, first explaining how DCSB works to guarantee that the pion is unnaturally light; but also, nevertheless, ensures the pion is key to revealing the mechanisms that generate nearly all the mass of hadrons. Our discussion unifies the charged-pion elastic and neutral-pion transition form factors, and the pion's twist-2 parton distribution amplitude. It also indicates how studies of the charged-kaon form factor can provide significant contributions. Importantly, recent predictions for the large-$Q^2$ behaviour of the pion form factor can be tested by experiments planned at JLab 12. Those experiments will extend precise charged-pion form factor data to momenta that can potentially serve in validating factorisation theorems in QCD, exposing the transition between the nonperturbative and perturbative domains, and thereby reaching a goal that has long driven hadro-particle physics.

  20. Prompt photons in photoproduction at HERA

    International Nuclear Information System (INIS)

    Aaron, F.D.; Alexa, C.; Rotaru, M.; Stoicea, G.; Zus, R.; Aldaya Martin, M.; Antunovic, B.; Bartel, W.; Brandt, G.; Campbell, A.J.; Cholewa, A.; Deak, M.; Boer, Y. de; Eckerlin, G.; Elsen, E.; Felst, R.; Fischer, D.J.; Fleischer, M.; Gayler, J.; Glazov, A.; Gouzevitch, M.; Grell, B.R.; Haidt, D.; Helebrant, C.; Jung, H.; Katzy, J.; Kleinwort, C.; Knutsson, A.; Kraemer, M.; Krastev, K.; Kutak, K.; Levonian, S.; Lipka, K.; List, J.; Marti, Ll.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michels, V.; Niebuhr, C.; Nikiforov, A.; Nozicka, M.; Olsson, J.E.; Panagoulias, I.; Papadopoulou, T.; Pitzl, D.; Placakyte, R.; Radescu, V.; Rurikova, Z.; Schmitt, S.; Sefkow, F.; Staykova, Z.; Steder, M.; Vargas Trevino, A.; Vinokurova, S.; Driesch, M. von den; Wissing, C.; Wuensch, E.; Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Loktionova, N.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Soloviev, Y.; Vazdik, Y.; Backovic, S.; Dubak, A.; Lastovicka-Medin, G.; Picuric, I.; Raicevic, N.; Baghdasaryan, A.; Ghazaryan, S.; Volchinski, V.; Zohrabyan, H.; Barrelet, E.; Begzsuren, K.; Ravdandorj, T.; Tseepeldorj, B.; Bizot, J.C.; Brisson, V.; Delcourt, B.; Jacquet, M.; Li, G.; Pascaud, C.; Tran, T.H.; Zhang, Z.; Zomer, F.; Boudry, V.; Moreau, F.; Specka, A.; Bozovic-Jelisavcic, I.; Mudrinic, M.; Pandurovic, M.; Smiljanic, I.; Bracinik, J.; Kenyon, I.R.; Newman, P.R.; Shaw-West, R.N.; Thompson, P.D.; Brinkmann, M.; Habib, S.; List, B.; Pokorny, B.; Toll, T.; Bruncko, D.; Cerny, V.; Ferencei, J.; Murin, P.; Tomasz, F.; Bunyatyan, A.; Buschhorn, G.; Chekelian, V.; Dossanov, A.; Grindhammer, G.; Kiesling, C.; Kogler, R.; Liptaj, A.; Olivier, B.; Raspiareza, A.; Shushkevich, S.; Bystritskaya, L.; Efremenko, V.; Fedotov, A.; Kropivnitskaya, A.; Lubimov, V.; Ozerov, D.; Petrukhin, A.; Rostovtsev, A.; Zhokin, A.; Cantun Avila, K.B.; Contreras, J.G.; Ruiz Tabasco, J.E.; Cerny, K.; Pejchal, O.; Polifka, R.; Salek, D.; Valkarova, A.; Zacek, J.; Coughlan, J.A.; Morris, J.V.; Sankey, D.P.C.; Cozzika, G.; Feltesse, J.; Perez, E.; Schoeffel, L.; Cvach, J.; Reimer, P.; Zalesak, J.; Dainton, J.B.; Gabathuler, E.; Greenshaw, T.; Klein, M.; Kluge, T.; Kretzschmar, J.; Laycock, P.; Maxfield, S.J.; Mehta, A.; Patel, G.D.; Rahmat, A.J.; Daum, K.; Meyer, H.; Del Degan, M.; Grab, C.; Leibenguth, G.; Sauter, M.; Zimmermann, T.; Delvax, J.; Wolf, E.A. de; Favart, L.; Hreus, T.; Janssen, X.; Marage, P.; Mozer, M.U.; Roland, B.; Roosen, R.; Sunar, D.; Sykora, T.; Mechelen, P. van; Diaconu, C.; Hoffmann, D.; Sauvan, E.; Trinh, T.N.; Vallee, C.; Dodonov, V.; Povh, B.; Egli, S.; Hildebrandt, M.; Horisberger, R.; Falkiewicz, A.; Goerlich, L.; Mikocki, S.; Milcewicz-Mika, I.; Nowak, G.; Sopicki, P.; Turnau, J.; Glushkov, I.; Henschel, H.; Hiller, K.H.; Kostka, P.; Lange, W.; Naumann, T.; Piec, S.; Henderson, R.C.W.; Sloan, T.; Hennekemper, E.; Herbst, M.; Jung, A.W.; Krueger, K.; Lendermann, V.; Schultz-Coulon, H.C.; Urban, K.; Herrera, G.; Lopez-Fernandez, R.; Joensson, L.; Osman, S.; Kapichine, M.; Makankine, A.; Morozov, A.; Nikitin, D.; Palichik, V.; Spaskov, V.; Tchoulakov, V.; Landon, M.P.J.; Rizvi, E.; Thompson, G.; Traynor, D.; Martyn, H.U.; Mueller, K.; Nowak, K.; Robmann, P.; Straumann, U.; Truoel, P.; Schoening, A.; South, D.; Wegener, D.; Stella, B.; Tsakov, I.

    2010-01-01

    The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb -1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 T γ γ γ and x p carried by the partons entering the hard scattering process. The correlation between the photon and the jet is also studied. The results are compared with QCD predictions based on the collinear and on the k T factorization approaches. (orig.) 7

  1. Optimal sum-rule inequalities for spin 1/2 Compton scattering. III

    International Nuclear Information System (INIS)

    Filkov, L.V.

    1980-10-01

    The analyticity (optimal) bounds for proton Compton scattering presented in the preceding paper are herewith considered from the point of view of experimental tests. An essential function occuring in this new dispersion framework is constructed numerically making use of existing cross-section data above the pion photoproduction threshold. To secure a safer construction new measurements in the photon laboratory energy region 150 MeV - 240 MeV and at small momentum transfers are necessary. The bounds on the scattering amplitudes in the low energy region below the pion photoproduction threshold are in general sufficiently restrictive so as to be useful in discriminating among variants of theoretical phenomenological analyses but subsequent extremizations needed in bounding only one combination of the amplitudes (the unpolarized differential cross-section) are weakening much the results. The question of strengthening the bounds by means of the combined use of analyticity and unitarity is discussed within a very crude example which nonetheless illustrates that the inclusion of the pion photoproduction data through more elaborate mathematical procedures would deserve the effort. (author)

  2. A Precision Measurement of the Neutral Pion Lifetime via the Primakoff Effect

    Energy Technology Data Exchange (ETDEWEB)

    Clinton, Eric [Univ. of Massachusetts, Amherst, MA (United States)

    2007-09-01

    The neutral pion radiative width has been measured to 8.411 eV ± 1.8% + 1.13% - 1.70% (lifetime = 7.826 ± 0.14 + 0.088 - 0.133 x 10-17 s) utilizing the Primakoff effect and roughly 4.9 to 5.5 GeV photons at the Thomas Jefferson National Accelerator Facility in Newport News, VA. The Hall B Photon Tagger, the Hall B Pair Spectrometer, a state of the art Hybrid Calorimter enabled precision incident photon energy measurement, photon flux measurement, and neutral pion identification, respectively. With these and other hardware and software tools, elastic neutral pion yields were extracted from the data. A well developed and understood simulation calculated geometric and software cut efficiency curves. The simulation also provided photo-pion production response functions to fit the experimental cross sections and extract the Primakoff cross section and thus the neutral pion radiative width and lifetime. Future work includes improving understanding of the nuclear incoherent process and any other background sources of elastic neutral pions in this data.

  3. Charge dependence of the pion-nucleon coupling constant

    Directory of Open Access Journals (Sweden)

    V. A. Babenko

    2015-07-01

    Full Text Available On the basis of the Yukawa potential we study the pion-nucleon coupling constants for the neutral and charged pions assuming that nuclear forces at low energies are mainly determined by the exchange of virtual pions. We obtain the charged pseudovector pion-nucleon coupling constant f2π± = 0.0804(7 by making the use of experimental low-energy scattering parameters for the singlet pp- and np-scattering, and also by use of the neutral pseudovector pion-nucleon coupling constant f2π0 = 0.0749(7. Corresponding value of the charged pseudoscalar pion-nucleon coupling constant g2π0 / 4π = 14.55(13 is also determined. This calculated value of the charged pseudoscalar pion-nucleon coupling constant is in fully agreement with the experimental constant g2π0 / 4π = 14.52(26 obtained by the Uppsala Neutron Research Group. Our results show considerable charge splitting of the pion-nucleon coupling constant.

  4. Pion Photo- and Electroproduction and the Partially Conserved Axial Current

    International Nuclear Information System (INIS)

    Haberzettl, Helmut

    2000-01-01

    The relevance of the axial current for pion production processes off the nucleon with real or virtual photons is revisited. Employing the hypothesis of a partially conserved axial current (PCAC), it is shown that, when all of the relevant contributions are taken into account, PCAC does not provide any additional constraint for threshold production processes that goes beyond the Goldberger-Treiman relation. In particular, it is shown that pion electroproduction processes at threshold cannot be used to extract any information regarding the weak axial form factor. The relationships found in previous investigations are seen to be an accident of the approximations usually made in this context

  5. Observation of hard scattering in photoproduction at HERA

    Science.gov (United States)

    Derrick, M.; Krakauer, D.; Magill, S.; Musgrave, B.; Repond, J.; Sugano, K.; Stanek, R.; Talaga, R. L.; Thron, J.; Arzarello, F.; Ayed, R.; Barbagli, G.; Bari, G.; Basile, M.; Bellagamba, L.; Boscherini, D.; Bruni, G.; Bruni, P.; Cara Romeo, G.; Castellini, G.; Chiarini, M.; Cifarelli, L.; Cindolo, F.; Ciralli, F.; Contin, A.; D'Auria, S.; Del Papa, C.; Frasconi, F.; Giusti, P.; Iacobucci, G.; Laurenti, G.; Levi, G.; Lin, Q.; Lisowski, B.; Maccarrone, G.; Margotti, A.; Massam, T.; Nania, R.; Nemoz, C.; Palmonari, F.; Sartorelli, G.; Timellini, R.; Zamora Garcia, Y.; Zichichi, A.; Bargende, A.; Barreiro, F.; Crittenden, J.; Dabbous, H.; Desch, K.; Diekmann, B.; Geerts, M.; Geitz, G.; Gutjahr, B.; Hartmann, H.; Hartmann, J.; Haun, D.; Heinloth, K.; Hilger, E.; Jakob, H.-P.; Kramarczyk, S.; Kückes, M.; Mass, A.; Mengel, S.; Mollen, J.; Müsch, H.; Paul, E.; Schattevoy, R.; Schneider, B.; Schneider, J.-L.; Wedemeyer, R.; Cassidy, A.; Cussans, D. G.; Dyce, N.; Fawcett, H. F.; Foster, B.; Gilmore, R.; Heath, G. P.; Lancaster, M.; Llewellyn, T. J.; Malos, J.; Morgado, C. J. S.; Tapper, R. J.; Wilson, S. S.; Rau, R. R.; Bernstein, A.; Caldwell, A.; Gialas, I.; Parsons, J. A.; Ritz, S.; Sciulli, F.; Straub, P. B.; Wai, L.; Yang, S.; Barillari, T.; Schioppa, M.; Susinno, G.; Burkot, W.; Chwastowski, J.; Dwuraźny, A.; Eskreys, A.; Nizioł, B.; Jakubowski, Z.; Piotrzkowski, K.; Zachara, M.; Zawiejski, L.; Borzemski, P.; Eskreys, K.; Jeleń, K.; Kisielewska, D.; Kowalski, T.; Kulka, J.; Rulikowska-Zarȩbska, E.; Suszycki, L.; Zajaç, J.; Kȩdzierski, T.; Kotański, A.; Przybycień, M.; Bauerdick, L. A. T.; Behrens, U.; Bienlein, J. K.; Coldewey, C.; Dannemann, A.; Dierks, K.; Dorth, W.; Drews, G.; Erhard, P.; Flasiński, M.; Fleck, I.; Fürtjes, A.; Gläser, R.; Göttlicher, P.; Haas, T.; Hagge, L.; Hain, W.; Hasell, D.; Hultschig, H.; Jahnen, G.; Joos, P.; Kasemann, M.; Klanner, R.; Koch, W.; Kötz, U.; Kowalski, H.; Labs, J.; Ladage, A.; Löhr, B.; Löwe, M.; Lüke, D.; Mainusch, J.; Manczak, O.; Momayezi, M.; Nickel, S.; Notz, D.; Park, I.; Pösnecker, K.-U.; Rohde, M.; Ros, E.; Schneekloth, U.; Schroeder, J.; Schulz, W.; Selonke, F.; Tscheslog, E.; Tsurugai, T.; Turkot, F.; Vogel, W.; Woeniger, T.; Wolf, G.; Youngman, C.; Grabosch, H. J.; Leich, A.; Meyer, A.; Rethfeldt, C.; Schlenstedt, S.; Casalbuoni, R.; De Curtis, S.; Dominici, D.; Francescato, A.; Nuti, M.; Pelfer, P.; Anzivino, G.; Casaccia, R.; Laakso, I.; De Pasquale, S.; Qian, S.; Votano, L.; Bamberger, A.; Freidhof, A.; Poser, T.; Söldner-Rembold, S.; Theisen, G.; Trefzger, T.; Brook, N. H.; Bussey, P. J.; Doyle, A. T.; Forbes, J. R.; Jamieson, V. A.; Raine, C.; Saxon, D. H.; Gloth, G.; Holm, U.; Kammerlocher, H.; Krebs, B.; Neumann, T.; Wick, K.; Hofmann, A.; Kröger, W.; Krüger, J.; Lohrmann, E.; Milewski, J.; Nakahata, M.; Pavel, N.; Poelz, G.; Salomon, R.; Seidman, A.; Schott, W.; Wiik, B. H.; Zetsche, F.; Bacon, T. C.; Butterworth, I.; Markou, C.; McQuillan, D.; Miller, D. B.; Mobayyen, M. M.; Prinias, A.; Vorvolakos, A.; Bienz, T.; Kreutzmann, H.; Mallik, U.; McCliment, E.; Roco, M.; Wang, M. Z.; Cloth, P.; Filges, D.; Chen, L.; Imlay, R.; Kartik, S.; Kim, H.-J.; McNeil, R. R.; Metcalf, W.; Cases, G.; Hervás, L.; Labarga, L.; del Peso, J.; Roldán, J.; Terrón, J.; de Trocóniz, J. F.; Ikraiam, F.; Mayer, J. K.; Smith, G. R.; Corriveau, F.; Gilkinson, D. J.; Hanna, D. S.; Hung, L. W.; Mitchell, J. W.; Patel, P. M.; Sinclair, L. E.; Stairs, D. G.; Ullmann, R.; Bashindzhagyan, G. L.; Ermolov, P. F.; Golubkov, Y. A.; Kuzmin, V. A.; Kuznetsov, E. N.; Savin, A. A.; Voronin, A. G.; Zotov, N. P.; Bentvelsen, S.; Dake, A.; Engelen, J.; de Jong, P.; de Jong, S.; de Kamps, M.; Kooijman, P.; Kruse, A.; van der Lugt, H.; O'Dell, V.; Straver, J.; Tenner, A.; Tiecke, H.; Uijterwaal, H.; Vermeulen, J.; Wiggers, L.; de Wolf, E.; van Woudenberg, R.; Yoshida, R.; Bylsma, B.; Durkin, L. S.; Li, C.; Ling, T. Y.; McLean, K. W.; Murray, W. N.; Park, S. K.; Romanowski, T. A.; Seidlein, R.; Blair, G. A.; Butterworth, J. M.; Byrne, A.; Cashmore, R. J.; Cooper-Sarkar, A. M.; Devenish, R. C. E.; Gingrich, D. M.; Hallam-Baker, P. M.; Harnew, N.; Khatri, T.; Long, K. R.; Luffman, P.; McArthur, I.; Morawitz, P.; Nash, J.; Smith, S. J. P.; Roocroft, N. C.; Wilson, F. F.; Abbiendi, G.; Brugnera, R.; Carlin, R.; Dal Corso, F.; De Giorgi, M.; Dosselli, U.; Fanin, C.; Gasparini, F.; Limentani, S.; Morandin, M.; Posocco, M.; Stanco, L.; Stroili, R.; Voci, C.; Lim, J. N.; Oh, B. Y.; Whitmore, J.; Bonori, M.; Contino, U.; D'Agostini, G.; Guida, M.; Iori, M.; Mari, S.; Marini, G.; Mattioli, M.; Monaldi, D.; Nigro, A.; Hart, J. C.; McCubbin, N. A.; Shah, T. P.; Short, T. L.; Barberis, E.; Cartiglia, N.; Heusch, C.; Hubbard, B.; Leslie, J.; Ng, J. S. T.; O'Shaughnessy, K.; Sadrozinski, H. F.; Seiden, A.; Badura, E.; Biltzinger, J.; Chaves, H.; Rost, M.; Seifert, R. J.; Walenta, A. H.; Weihs, W.; Zech, G.; Dagan, S.; Heifetz, R.; Levy, A.; Zer-Zion, D.; Hasegawa, T.; Hazumi, M.; Ishii, T.; Kasai, S.; Kuze, M.; Nagasawa, Y.; Nakao, M.; Okuno, H.; Tokushuku, K.; Watanabe, T.; Yamada, S.; Chiba, M.; Hamatsu, R.; Hirose, T.; Kitamura, S.; Nagayama, S.; Nakamitsu, Y.; Arneodo, M.; Costa, M.; Ferrero, M. I.; Lamberti, L.; Maselli, S.; Peroni, C.; Solano, A.; Staiano, A.; Dardo, M.; Bailey, D. C.; Bandyopadhyay, D.; Benard, F.; Bhadra, S.; Brkic, M.; Burow, B. D.; Chlebana, F. S.; Crombie, M. B.; Hartner, G. F.; Levman, G. M.; Martin, J. F.; Orr, R. S.; Prentice, J. D.; Sampson, C. R.; Stairs, G. G.; Teuscher, R. J.; Yoon, T.-S.; Bullock, F. W.; Catterall, C. D.; Giddings, J. C.; Jones, T. W.; Khan, A. M.; Lane, J. B.; Makkar, P. L.; Shaw, D.; Shulman, J.; Blankenship, K.; Kochocki, J.; Lu, B.; Mo, L. W.; Charchuła, K.; Ciborowski, J.; Gajewski, J.; Grzelak, G.; Kasprzak, M.; Krzyżanowski, M.; Muchorowski, K.; Nowak, R. J.; Pawlak, J. M.; Stojda, K.; Stopczyński, A.; Szwed, R.; Tymieniecka, T.; Walczak, R.; Wróblewski, A. K.; Zakrzewski, J. A.; Żarnecki, A. F.; Adamus, M.; Abramowicz, H.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Revel, D.; Shapira, A.; Ali, I.; Behrens, B.; Camerini, U.; Dasu, S.; Fordham, C.; Foudas, C.; Goussiou, A.; Lomperski, M.; Loveless, R. J.; Nylander, P.; Ptacek, M.; Reeder, D. D.; Smith, W. H.; Silverstein, S.; Frisken, W. R.; Furutani, K. M.; Iga, Y.; ZEUS Collaboration

    1992-12-01

    We report a study of electron proton collisions at very low Q2, corresponding to virtual photoproduction at centre of mass energies in the range 100-295 GeV. The distribution in transverse energy of the observed hadrons is much harder than can be explained by soft processes. Some of the events show back-to-back two-jet production at the rate and with the characteristics expected from hard two-body scattering. A subset of the two-jet events have energy in the electron direction consistent with that expected from the photon remnant in resolved photon processes.

  6. Magnetic polarizability of pion

    Energy Technology Data Exchange (ETDEWEB)

    Luschevskaya, E.V., E-mail: luschevskaya@itep.ru [Institute for Theoretical and Experimental Physics, Bolshaia Cheremushkinskaia 25, 117218 Moscow (Russian Federation); School of Biomedicine, Far Eastern Federal University, 690950 Vladivostok (Russian Federation); Solovjeva, O.E., E-mail: olga.solovjeva@itep.ru [Institute for Theoretical and Experimental Physics, Bolshaia Cheremushkinskaia 25, 117218 Moscow (Russian Federation); Teryaev, O.V., E-mail: teryaev@theor.jinr.ru [Joint Institute for Nuclear Research, Dubna, 141980 (Russian Federation); National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute), Kashirskoe highway, 31, 115409 Moscow (Russian Federation)

    2016-10-10

    We explore the energy dependence of π mesons off the background Abelian magnetic field on the base of quenched SU(3) lattice gauge theory and calculate the magnetic dipole polarizability of charged and neutral pions for various lattice volumes and lattice spacings. The contribution of the magnetic hyperpolarizability to the neutral pion energy has been also found.

  7. Hard photoproduction of multiparticle hadronic final states

    International Nuclear Information System (INIS)

    Paul, E.

    1992-02-01

    Recent results from fixed-target experiments on the photoproduction of hadrons have shown that pointlike photon interaction processes of lowest order in QCD can be studied. These are the flavour-dependent γg-fusion process which is the keyprocess to explore the gluon structure function of the nucleon at small x g and the QCD-Compton process which is a tool to study gluon fragmentation. The status of experimental results and comparison to QCD prediction is reviewed. The γg-fusion process will be measured in ep scatterings with almost real photons at HERA photon energies (equivalent to up to 50 TeV in the rest frame of the proton) down to x g > or approx. 10 -4 . Resolved (partonlike) photon interactions are predicted to be measurable at these high energies, too. (orig.)

  8. Charm photoproduction and quantum chromodynamics

    International Nuclear Information System (INIS)

    Novikov, V.A.; Shifman, M.A.; Vainshtein, A.I.; Zakharov, V.I.

    1977-01-01

    It is shown that charm photoproduction can be consistently described within asymptotically free field theory. Quantum chromodynamics is used to derive sum rules for the total cross section sigmasub(c)sup(γ) which includes both production of mesons with hidden charm (J/PIS, PIS' and so on) and of charmed particles (pairs DantiD, FantiF and so on). An estimate of sigmasub(c)sup(γ) as a function of energy is given and fast growth is discovered up to energies approximately 1000 GeV. In this energy range sigmasub(c)sup(γ) turns out to be equal to several microbarns. It is argued that measurements of charm photoproduction would give the most direct information on the gluon distribution within a nucleon. All the results are generalized to production of heavier particles containing new quarks. In particular, a simple rescaling law is derived connecting the cross sections for charm and beauty

  9. To the calculation of differential and total cross sections of γπ interactions

    International Nuclear Information System (INIS)

    Duplij, S.A.

    1980-01-01

    The differential and total cross sections of different charge channels of the γπ→ππ process are calculated. At the threshold energies the vector dominance model predicts twice as large values of the total cross sections than the current algebra. In resonance the total cross section of photoproduction on a neutral pion is 10-50 μb, on a charged pion - 5-10μb, at near-threshold energies (Esub(γ)=300-600 MeV) both cross sections are of the 20-40 nb order. For the γπ→ππ process the differential cross sections according to the invariant mass of two pions are obtained for different charge channels. At the threshold energies the total cross sections of the γπ→ππ process is of the 0.1-1 nb order

  10. Pions in the nuclear medium

    International Nuclear Information System (INIS)

    Chanfray, G.

    1996-07-01

    We discuss various aspects of pion physics in the nuclear medium. We first study s-wave pion-nucleus interaction in connection with chiral symmetry restoration and quark condensate in the nuclear medium. We then address the question of p-wave pion-nucleus interaction and collective pionic modes in nuclei and draw the consequences for in medium ππ correlations especially in the scalar-isoscalar channel. We finally discuss the modification of the rho meson mass spectrum at finite density and/or temperature in connection with relativistic heavy ion collisions

  11. Can one distinguish τ-neutrinos from antineutrinos in neutral-current pion production processes?

    International Nuclear Information System (INIS)

    Hernandez, E.; Nieves, J.; Valverde, M.

    2007-01-01

    A potential way to distinguish τ-neutrinos from antineutrinos, below the τ-production threshold, but above the pion production one, is presented. It is based on the different behavior of the neutral-current pion production off the nucleon, depending on whether it is induced by neutrinos or antineutrinos. This procedure for distinguishing τ-neutrinos from antineutrinos neither relies on any nuclear model, nor it is affected by any nuclear effect (distortion of the outgoing nucleon waves, etc.). We show that neutrino-antineutrino asymmetries occur both in the totally integrated cross sections and in the pion azimuthal differential distributions. To define the asymmetries for the latter distributions we just rely on Lorentz-invariance. All these asymmetries are independent of the lepton family and can be experimentally measured by using electron or muon neutrinos, due to the lepton family universality of the neutral-current neutrino interaction. Nevertheless and to estimate their size, we have also used the chiral model of [E. Hernandez, J. Nieves, M. Valverde, hep-ph/0701149] at intermediate energies. Results are really significant since the differences between neutrino and antineutrino induced reactions are always large in all physical channels

  12. Two-pion correlations in heavy ion collisions

    International Nuclear Information System (INIS)

    Zajc, W.A.

    1982-08-01

    An application of intensity interferometry to relativistic heavy ion collisions is reported. Specifically, the correlation between two like-charged pions is used to study the reactions Ar+KCl→2π/sup +-/+X and Ne+NaF→2π - +X. Source sizes are obtained that are consistent with a simple geometric interpretation. Lifetimes are less well determined but are indicative of a faster pion production process than predicted by Monte Carlo cascade calculations. There appears to be a substantial coherent component of the pion source, although measurement is complicated by the presence of final state interactions. Additionally, the generation of spectra of uncorrelated events is discussed. In particular, the influence of the correlation function on the background spectrum is analyzed, and a prescription for removal of this influence is given. A formulation to describe the statistical errors in the background is also presented. Finally, drawing from the available literature, a self-contained introduction to Bose-Einstein correlations and the Hanbury-Brown - Twiss effect is provided, with an emphasis on points of contact between classical and quantum mechanical descriptions

  13. Three- and four-jet final states in photoproduction at HERA

    International Nuclear Information System (INIS)

    Chekanov, S.; Derrick, M.; Magill, S.

    2007-08-01

    Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb -1 . The results are presented for jets with transverse energy E jet T >6 GeV and pseudorapidity vertical stroke η jet vertical stroke 2 2 and the inelasticity 0.2≤y≤0.85 and in two mass regions defined as 25≤M nj nj ≥50 GeV, where M nj is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O(αα 2 s ) perturbative QCD calculation. (orig.)

  14. Phototransformation of amlodipine: degradation kinetics and identification of its photoproducts.

    Directory of Open Access Journals (Sweden)

    Anna Jakimska

    Full Text Available Nowadays, monitoring focuses on the primary compounds and does not include degradation products formed during various biological and chemical processes. Transformation products may have the same effects to human health and the environment or sometimes they can be more toxic than the parent compound. Unfortunately, knowledge about the formation of degradation products is still limited, however, can be very important for the environmental risk assessment. Firstly, the photodegradation kinetic of amlodipine was investigated in two experimental conditions: during the exposure to solar radiation and during the exposure to the light emitted by the xenon lamp. In all cases degradation of amlodipine followed a pseudo-first-order kinetics. In the next step, identification of transformation products of amlodipine formed during the exposure to xenon lamp irradiation was performed using ultra high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS. As a result sixteen photoproducts were identified, their structures were elucidated and ultimately the transformation pathway was proposed. Fifteen compounds (out of 16 photoproducts were newly identified and reported here for the first time; some of those compounds were formed from the first photoproduct, amlodipine pyridine derivative. Several analytes were formed only in acidic or basic conditions. Furthermore, the occurrence of amlodipine and its identified degradation products was investigated in environmental waters. Only one out of 16 compounds was found in wastewater effluent. The possibility of the sorption of examined analytes to sewage sludge particles was discussed based on QSAR.

  15. The pion form factor from first principles

    International Nuclear Information System (INIS)

    Heide, J. van der

    2004-01-01

    We calculate the electromagnetic form factor of the pion in quenched lattice QCD. The non-perturbatively improved Sheikoleslami-Wohlert lattice action is used together with the O(a) improved current. We calculate form factor for pion masses down to mπ = 380 MeV. We compare the mean square radius for the pion extracted from our form factors to the value obtained from the 'Bethe Salpeter amplitude'. Using (quenched) chiral perturbation theory, we extrapolate our results towards the physical pion mass

  16. Radiation quality of beams of negative pions

    International Nuclear Information System (INIS)

    Dicello, J.F.; Brenner, D.J.

    1981-01-01

    As a negative pion stops in tissue, it attaches itself to an adjacent atom to form a mesonic atom. Subsequently, the wave function of the pion interacts with that of the nucleus and the pion is absorbed. Because the energy associated with the rest mass of the pion is greater than the separation energy of the nuclear particles, the nucleus disintegrates (pion star). In tissue, approximately 40 MeV goes into overcoming the binding energies; 20 MeV goes into kinetic energy of charged particles; 80 MeV goes into kinetic energy of neutrons. In cases where biological studies are performed with beams of negative pions, as much as 20% of the total absorbed dose in the treatment volume and about 50% of the high-LET dose (> 100 keV/μm) can result from neutrons. The degree of biological response and the variation of that response throughout the treatment volume can be altered by the neutron dose

  17. Scrutinizing the pion condensed phase

    Energy Technology Data Exchange (ETDEWEB)

    Carignano, Stefano; Mammarella, Andrea; Mannarelli, Massimo [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Lepori, Luca [Universita di Padova, Dipartimento di Fisica e Astronomia, Padova (Italy); Universita dell' Aquila, Dipartimento di Scienze Fisiche e Chimiche, Coppito-L' Aquila (Italy); Pagliaroli, Giulia [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Gran Sasso Science Institute, L' Aquila (Italy)

    2017-02-15

    When the isospin chemical potential exceeds the pion mass, charged pions condense in the zero-momentum state forming a superfluid. Chiral perturbation theory provides a very powerful tool for studying this phase. However, the formalism that is usually employed in this context does not clarify various aspects of the condensation mechanism and makes the identification of the soft modes problematic. We re-examine the pion condensed phase using different approaches within the chiral perturbation theory framework. As a first step, we perform a low-density expansion of the chiral Lagrangian valid close to the onset of the Bose-Einstein condensation. We obtain an effective theory that can be mapped to a Gross-Pitaevskii Lagrangian in which, remarkably, all the coefficients depend on the isospin chemical potential. The low-density expansion becomes unreliable deep in the pion condensed phase. For this reason, we develop an alternative field expansion deriving a low-energy Lagrangian analog to that of quantum magnets. By integrating out the ''radial'' fluctuations we obtain a soft Lagrangian in terms of the Nambu-Goldstone bosons arising from the breaking of the pion number symmetry. Finally, we test the robustness of the second-order transition between the normal and the pion condensed phase when next-to-leading-order chiral corrections are included. We determine the range of parameters for turning the second-order phase transition into a first-order one, finding that the currently accepted values of these corrections are unlikely to change the order of the phase transition. (orig.)

  18. Pion production differential cross section of heavy-ion collisions at subthreshold energies

    International Nuclear Information System (INIS)

    Abumurad, K.M.

    1987-01-01

    A revised model for pion production in heavy-ion peripheral collisions at subthreshold energies is presented. The pion-production mechanism investigated here is a two step process involving the formation and subsequent decay of an isobar resonance in the projectile nucleus. The independent-particle shell model with harmonic oscillator states is used to approximate the internal structure of the nucleus. The pion production cross section shows a definite angular distribution characteristic of coherent production. It also gives an indication of the quantum signature of the emitted pions. The results show the disappearance of the quantum signature from the energy spectra because of the inclusion of higher order multipoles. The theory is compared to recent experimental data. The comparison reveals that the general trend is reproduced, which is encouraging

  19. Physics of the pion liquid

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1990-01-01

    Excited hadronic matter in the temperature interval T = 100-200 MeV is not an ideal pion gas, but ratehr a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the quasipion comes to the boundary of the system. The author shows that these effects can provide an explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions

  20. Physics of the pion liquid

    International Nuclear Information System (INIS)

    Shuryak, E.V.

    1990-04-01

    Excited hadronic matter in the temperature interval T = 100--200 MeV is not an ideal pion gas, but rather a liquid, in which attractive interaction among particles plays an important role. Pion dispersion curve is in this case essentially modified by a kind of collective momentum-dependent potential, which becomes important as the ''quasipion'' comes to the boundary of the system. We show that effects can provide and explanation for a number of recent experimental puzzles, in particular, for the observed copious production of soft pions and soft photons in high energy hadronic reactions. 31 refs., 13 figs

  1. Modification of pion pairs in nuclear matter; Modifikationen von Pionenpaaren in Kernmaterie

    Energy Technology Data Exchange (ETDEWEB)

    Gregor, Ralf

    2007-07-18

    In this work the quasifree photoproduction of pion pairs on bound nucleons is analyzed for the solid targets carbon, calcium and lead. These measurements allow an isospin dependent determination of the in medium properties of pion pairs. The invariant mass distributions showed a shift in strength towards the threshold region with increasing atomic number of the targets in case of an isoscalar {pi}{pi} meson system. According to theoretical predictions this effect was interpreted as a positive signature of a partial restoration of chiral symmetry. A pioneering experiment with photon beams was performed by the TAPS collaboration at the accelerator facility MAMI-B in Mainz in 1995. This measurement observed an invariant mass shift of the isoscalar {pi}{sup 0}{pi}{sup 0} channel with increasing atomic number. In the {pi}{sup {+-}}{pi}{sup 0} channel this effect was not observed. This observation confirmed the former experiments, since final state interactions of the pions would affect in first order both isospin channels in a similar way. Due to the poor statistics, the significance of the data was however limited. The experiment described in this work reached a much higher statistical significance, allowing a review of the old data and a study of the dependence of the signal from parameters like the momenta of the {pi}{pi} system or the single pions. In this experiment, the TAPS detector was used as a forward wall in combination with the Crystal Ball detector to achieve a 4{pi} solid angle coverage for photon detection at the MAMI accelerator facility. The new readout electronics for the BaF{sub 2} crystals was used for the first time. The new data analysis confirms the previously measured and published data. However, the shift of the invariant {pi}{sup 0}{pi}{sup 0} mass to the threshold region is less pronounced than in the published data. By performing cuts on the individual pion momenta, resulting in a maximum mean free path of the pions, the shift towards lower

  2. Pion distribution in the nucleon

    International Nuclear Information System (INIS)

    Lee, T.-S.H.

    1989-01-01

    A model is presented for calculating the pion wave function inside the nucleon. By assuming that all pions around a core of the nucleon are in the lowest eigenstate of the system, it is shown that both the bound state and πN scattering amplitude can be consistently described by an exactly soluble model defined in the subspace spanned by the core state and the physical πN state. The parameters of the model are determined by fitting the data of the nucleon mass, πNN coupling constant and low energy πN scattering phase shifts. The model predicts that the probability of finding the pion component inside the nucleon is about 20%. The calculated πNN form factor differs significantly from the conventional monopole form. The dynamical consequences of the differences are demonstrated in a calculation of electromagnetic production of pions from the nucleon and the deuteron. 7 refs., 4 figs., 1 tab

  3. Development of a user-friendly system for image processing of electron microscopy by integrating a web browser and PIONE with Eos.

    Science.gov (United States)

    Tsukamoto, Takafumi; Yasunaga, Takuo

    2014-11-01

    need to provide common workspace for analysis because the client is physically separated from a server. We solved the file format problem by extension of rules of OptionControlFile of Eos. Furthermore, to solve workspace problems, we have developed two type of system. The first system is to use only local environments. The user runs a web server provided by Eos, access to a web client through a web browser, and manipulate the local files with GUI on the web browser. The second system is employing PIONE (Process-rule for Input/Output Negotiation Environment), which is our developing platform that works under heterogenic distributed environment. The users can put their resources, such as microscopic images, text files and so on, into the server-side environment supported by PIONE, and so experts can write PIONE rule definition, which defines a workflow of image processing. PIONE run each image processing on suitable computers, following the defined rule. PIONE has the ability of interactive manipulation, and user is able to try a command with various setting values. In this situation, we contribute to auto-generation of GUI for a PIONE workflow.As advanced functions, we have developed a module to log user actions. The logs include information such as setting values in image processing, procedure of commands and so on. If we use the logs effectively, we can get a lot of advantages. For example, when an expert may discover some know-how of image processing, other users can also share logs including his know-hows and so we may obtain recommendation workflow of image analysis, if we analyze logs. To implement social platform of image processing for electron microscopists, we have developed system infrastructure, as well. © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. Measuring pion beta decay with high-energy pion beams

    International Nuclear Information System (INIS)

    McFarlane, W.K.; Hoffman, C.M.

    1993-01-01

    Improved measurements of the pion beta decay rate are possible with an intense high-energy pion beam. The rate for the decay π + → π 0 e + vε is predicted by the Standard Model (SM) to be R(π + → π 0 e + vε) = 0.3999±0.0005 s -1 . The best experimental number, obtained using in-flight decays, is R(π + → π 0 e + vε) = 0.394 ± 0.015 s -1 . A precise measurement would test the SM by testing the unitarity of the Cabibbo-Kobayashi-Maskawa matrix for which one analysis of the nuclear beta decay data has shown a 0.4% discrepancy. Several nuclear correction factors, needed for nuclear decay, are not present for pion beta decay, so that an experiment at the 0.2% level would be a significant one. Detailed study of possible designs will be needed, as well as extensive testing of components. The reduction of systematic errors to the 0.1% level can only be done over a period of years with a highly stable apparatus and beam. At a minimum, three years of occupancy of a beam line, with 800 hours per year, would be required

  5. Sivers asymmetry in the pion induced Drell-Yan process at COMPASS within transverse momentum dependent factorization

    Science.gov (United States)

    Wang, Xiaoyu; Lu, Zhun

    2018-03-01

    We investigate the Sivers asymmetry in the pion-induced single polarized Drell-Yan process in the theoretical framework of the transverse momentum dependent factorization up to next-to-leading logarithmic order of QCD. Within the TMD evolution formalism of parton distribution functions, the recently extracted nonperturbative Sudakov form factor for the pion distribution functions as well as the one for the Sivers function of the proton are applied to numerically estimate the Sivers asymmetry in the π-p Drell-Yan at the kinematics of the COMPASS at CERN. In the low b region, the Sivers function in b -space can be expressed as the convolution of the perturbatively calculable hard coefficients and the corresponding collinear correlation function, of which the Qiu-Sterman function is the most relevant one. The effect of the energy-scale dependence of the Qiu-Sterman function to the asymmetry is also studied. We find that our prediction on the Sivers asymmetries as functions of xp, xπ, xF and q⊥ is consistent with the recent COMPASS measurement.

  6. Design and simulation of the nuSTORM pion beamline

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A., E-mail: aoliu@fnal.gov; Neuffer, D.; Bross, A.

    2015-11-21

    The nuSTORM (neutrinos from STORed Muons) proposal presents a detailed design for a neutrino facility based on a muon storage ring, with muon decay in the production straight section of the ring providing well defined neutrino beams. The facility includes a primary high-energy proton beam line, a target station with pion production and collection, and a pion beamline for pion transportation and injection into a muon decay ring. The nuSTORM design uses “stochastic injection”, in which pions are directed by a chicane, referred to as the Orbit Combination Section (OCS), into the production straight section of the storage ring. Pions that decay within that straight section provide muons within the circulating acceptance of the ring. The design enables injection without kickers or a separate pion decay transport line. The beam line that the pions traverse before being extracted from the decay ring is referred to as the pion beamline. This paper describes the design and simulation of the pion beamline, and includes full beam dynamics simulations of the system.

  7. Nucleon multiplicities after pion absorption in 160

    International Nuclear Information System (INIS)

    Hamers, R.

    1989-01-01

    The experiment described in this thesis concerns a simultaneous measurement of two- and higher-fold coincidences following positive and negative pion absorption in 16 0. The detected particles are protons, neutrons and deuterons. The detection and analysis of charged particles is discussed. The incident pion energy was 65 MeV, thus well below the delta resonance. The low pion energy was 65 MeV, thus well below the delta resonance. The low pion energy ensures that contributions of initial state interactions, i.e. pion-nucleon scattering preceding absorption, are minimized. The following reaction channels were selected and analyzed: π + ,pp), (π + ,pd). Evidence for quasifree reaction precessed has been investigated by comparing the data with phase-space calculations incorporating the geometry of the experimental setup. (author). 36 refs.; 1 figs.; 3 tabs

  8. Effective pion--nucleon interaction in nuclear matter

    International Nuclear Information System (INIS)

    Celenza, L.S.; Liu, L.C.; Nutt, W.; Shakin, C.M.

    1976-01-01

    We discuss the modification of the interaction between a pion and a nucleon in the presence of an infinite medium of nucleons (nuclear matter). The theory presented here is covariant and is relevant to the calculation of the pion--nucleus optical potential. The specific effects considered are the modifications of the nucleon propagator due to the Pauli principle and the modification of the pion and nucleon propagators due to collisions with nucleons of the medium. We also discuss in detail the pion self-energy in the medium, paying close attention to off-shell effects. These latter effects are particularly important because of the rapid variation with energy of the fundamental pion--nucleon interaction. Numerical results are presented, the main feature being the appearance of a significant damping width for the (3, 3) resonance

  9. Electron linac design for pion radiotherapy

    International Nuclear Information System (INIS)

    Loew, G.A.; Brown, K.L.; Miller, R.H.; Walz, D.R.

    1977-03-01

    The electron linac provides a straightforward, state-of-the-art method of producing the primary beam required for a hospital-based multiport pion radiotherapy facility for cancer treatment. The accelerator and associated beam transport system described are capable of generating an electron beam of about 250 kW and delivering it alternately to one of several pion generators and treatment areas. Each pion generator, a prototype of which now exists at the Stanford W. W. Hansen Laboratory, would contain a target for the electron beam and sixty separate superconducting magnet channels which focus the pions in the patient. The considerations which enter the design of a practical linac are presented together with a possible layout of a flexible beam transport system

  10. Charged pions polarizability measurement at COMPASS

    CERN Document Server

    Guskov, A

    2010-01-01

    The pion electromagnetic structure can be probed in $\\pi^{−}+(A,Z)\\rightarrow\\pi^{-}+(A,Z)+\\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\alpha_{\\pi})$ and the magnetic $(\\beta_{\\pi})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of point-like pions with the measured cross section. The opportunity to measure pion polarizability via the Primakoff reaction at the COMPASS experiment was studied with $a$ $\\pi^{-}$ beam of 190 GeV during pilot run 2004. The obtained results were used for preparation of the new data taking which was performed in 2009.

  11. Fluctuations in non-ideal pion gas with dynamically fixed particle number

    Science.gov (United States)

    Kolomeitsev, E. E.; Voskresensky, D. N.

    2018-05-01

    We consider a non-ideal hot pion gas with the dynamically fixed number of particles in the model with the λϕ4 interaction. The effective Lagrangian for the description of such a system is obtained after dropping the terms responsible for the change of the total particle number. Reactions π+π- ↔π0π0, which determine the isospin balance of the medium, are permitted. Within the self-consistent Hartree approximation we compute the effective pion mass, thermodynamic characteristics of the system and the variance of the particle number at temperatures above the critical point of the induced Bose-Einstein condensation when the pion chemical potential reaches the value of the effective pion mass. We analyze conditions for the condensate formation in the process of thermalization of an initially non-equilibrium pion gas. The normalized variance of the particle number increases with a temperature decrease but remains finite in the critical point of the Bose-Einstein condensation. This is due to the non-perturbative account of the interaction and is in contrast to the ideal-gas case. In the kinetic regime of the condensate formation the variance is shown to stay finite also.

  12. Upper limits for the photoproduction cross section for the Φ--(1860) pentaquark state off the deuteron

    Science.gov (United States)

    Egiyan, H.; Langheinrich, J.; Gothe, R. W.; Graham, L.; Holtrop, M.; Lu, H.; Mattione, P.; Mutchler, G.; Park, K.; Smith, E. S.; Stepanyan, S.; Zhao, Z. W.; Adhikari, K. P.; Aghasyan, M.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Bedlinskiy, I.; Bennett, R. P.; Biselli, A. S.; Bookwalter, C.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Carman, D. S.; Celentano, A.; Chandavar, S.; Contalbrigo, M.; D'Angelo, A.; Daniel, A.; Dashyan, N.; de Vita, R.; de Sanctis, E.; Deur, A.; Dey, B.; Dickson, R.; Djalali, C.; Doughty, D.; Dupre, R.; El Alaoui, A.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fradi, A.; Gabrielyan, M. Y.; Gevorgyan, N.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Golovatch, E.; Griffioen, K. A.; Guidal, M.; Guler, N.; Guo, L.; Gyurjyan, V.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Heddle, D.; Hicks, K.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jo, H. S.; Joo, K.; Khetarpal, P.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Kubarovsky, V.; Kuleshov, S. V.; Livingston, K.; MacGregor, I. J. D.; Mao, Y.; Mayer, M.; McKinnon, B.; Mokeev, V.; Munevar, E.; Nadel-Turonski, P.; Ni, A.; Niculescu, G.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L.; Paremuzyan, R.; Park, S.; Pasyuk, E.; Anefalos Pereira, S.; Phelps, E.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Raue, B. A.; Ricco, G.; Rimal, D.; Ripani, M.; Ritchie, B. G.; Rosner, G.; Rossi, P.; Sabatié, F.; Saini, M. S.; Salgado, C.; Schott, D.; Schumacher, R. A.; Seder, E.; Seraydaryan, H.; Sharabian, Y. G.; Smith, G. D.; Sober, D. I.; Stepanyan, S. S.; Strauch, S.; Taiuti, M.; Tang, W.; Taylor, C. E.; Tedeschi, D. J.; Ungaro, M.; Voutier, E.; Watts, D. P.; Weinstein, L. B.; Weygand, D. P.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhao, B.

    2012-01-01

    We searched for the Φ--(1860) pentaquark in the photoproduction process off the deuteron in the Ξ-π--decay channel using CLAS. The invariant-mass spectrum of the Ξ-π- system does not indicate any statistically significant enhancement near the reported mass M=1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of Φ--(1860) with a consecutive decay into Ξ-π- in the photon-energy range 4.5GeV

  13. Off-shell sensitivity, repulsive correlations and the pion-nucleus optical potential

    Energy Technology Data Exchange (ETDEWEB)

    Keister, B D [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA). Dept. of Physics

    1977-07-01

    Repulsive nucleon-nucleon correlations tend to reduce the dependence of pion-nucleus elastic scattering upon the off-shell pion-nucleon dynamics. However, optical potential calculations can in practice be quite sensitive to the particular choice of off-shell model parameters. It is argued that this sensitivity results from the nature of the optical potential as a one-body operator which introduces extra off-shell dependence not found in physical many-body process itself. Thus, one must be very careful in any attempt to extract correlation or off-shell information, or to predict pion-nucleus phase shifts, by means of an optical potential theory. Results of model calculations are presented for purposes of illustration.

  14. NNLO contributions to jet photoproduction and determination of {alpha}{sub s}

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, Michael; Michael, Markus [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Kramer, Gustav [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2013-10-15

    We present the first calculation of inclusive jet photoproduction with next-to-next-to-leading order (NNLO) contributions, obtained from a unified threshold resummation formalism. The leading coefficients for direct photoproduction are computed analytically. Together with the coefficients pertinent to parton-parton scattering, they are shown to agree with those appearing in our full next-to-leading order calculations. For hadron-hadron scattering, numerical agreement is found with a previous calculation of jet production at the Tevatron. We show that the direct and resolved NNLO contributions considerably improve the description of final ZEUS data on jet photoproduction and that the error on the determination of the strong coupling constant is significantly reduced.

  15. Pion-nucleus scatter and the Pauli principle

    International Nuclear Information System (INIS)

    Dover, C.B.; Lemmer, R.H.

    1976-01-01

    A density expansion of the pion self-energy for pions in nuclear matter is reexamined. It is shown that a single hole-line expansion of the self-energy (i) is equivalent to using a strongly quenched πN scattering amplitude in the medium, and (ii) results in an inconsistent treatment of the virtual pions necessarily present in a field-theoretic description of the problem. Exchange of intermediate pions gives rise to nucleon-nucleon, as well as pion-nucleon scattering diagrams that both contribute to the pion self-energy in an essential way. The nucleon-nucleon scattering proceeds, for instance, via a one-pion-exchange potential that is, however, highly nonstatic for energy transfers between nucleons close to the incident energy. Such interactions are singled out automatically for special treatment in a field-theory approach to the problem, and should not be introduced in an ad hoc manner as part of an empirical NN interaction in nuclear matter. We evaluate the coherent and charge exchange contributions to the pion-nucleus optical potential, proportional to the total density and the neutron-proton density difference, respectively. The Pauli principle is found to provide a small correction to the coherent part, both in the hole-line and density expansion formalisms. However, the charge exchange part of the potential is almost completely damped at low energies in the hole-line expansion, while the inclusion of backward-going graphs (random-phase-approximation-type correlations) restores it to its value based on free space πN charge exchange amplitudes (i.e., no net Pauli effect)

  16. Pion structure from lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Javadi Motaghi, Narjes

    2015-05-12

    In this thesis we use lattice QCD to compute the second Mellin moments of pion generalized parton distributions and pion electromagnetic form factors. For our calculations we are able to analyze a large set of gauge configurations with 2 dynamical flavours using non-perturbatively the improved Wilson-Sheikholeslami-Wohlert fermionic action pion masses ranging down to 151 MeV. By employing improved smearing we were able to suppress excited state contamination. However, our data in the physical quark mass limit show that some excited state contamination remains. We show the non-zero sink momentum is optimal for the computation of the electromagnetic form factors and generalized form factors at finite momenta.

  17. Charge-odd and single-spin effects in two pion production in ep bar collisions

    International Nuclear Information System (INIS)

    Galynskij, M.V.; Kuraev, E.A.; Shajkhatdenov, B.G.; Ratcliffe, P.G.

    2000-01-01

    We consider two-photon and Bremsstrahlung mechanisms for the production of two charged pions in high-energy electron (proton) scattering off a transversely polarised proton. Interference between the relevant amplitudes generates a charge-odd contribution to the cross section for the process. In a kinematics with a jet moving along electron spin-independent part may be used for determination of phase differences for pion-pion scattering in the states with orbital momentum 0 or 2 and 1 whereas in a kinematics with a jet moving along proton spin-dependent part may be used to explain the experimental data for single-spin correlations in the production of negatively charged pions. We also discuss the backgrounds and estimate the accuracy of the results at less than 10% level. In addition simplified formulae derived for specific kinematics, with small total transverse pion momentum, are given

  18. Pion radiation therapy

    International Nuclear Information System (INIS)

    Kligerman, M.M.

    1975-01-01

    Results are summarized from studies on the relative biological effects as compared with x or γ radiation and OER of negative pi mesons produced by the Berkeley 184-inch synchrocyclotron or the NIMROD 7-GeV proton synchrocyclotron at the Rutherford High Energy Laboratory in England using cultured animal cells or Vicia faba cells as the test system. Preliminary results are reported from similar radiobiological studies at the Los Alamos Meson Physics Facility. The relative response of human tissues to peak pion irradiation was compared with 140 kV x rays in a single patient with multiple malignant melanoma by observing the acute response of the skin surrounding metastatic modules following exposure to either pions or x radiation. Color photographs of the irradiated areas made at least twice weekly and densitometry measurements and observations by radiation therapists indicated that maximum erythemia occurred during the fifth, sixth, or seventh week after the start of a schedule of fractionated exposure to 15 fractions over 19 elapsed days. X irradiation was delivered at a dose rate of 500 rads/min to modules to deliver 55, 66, or 75 percent of a skin surface dose of 5,200 rads and pion irradiation, at doses numerically 50 percent of the x ray dose, was delivered at a dose rate of 5 to 7 rads/min. Dose response curves were plotted. Results of histological examinations of skin samples taken 24 weeks following irradiation are reported. Results are discussed relative to the destruction of melanoma cells following pion or x ray treatment

  19. Exclusive vector meson production at HERA

    International Nuclear Information System (INIS)

    Szuba, Dorota

    2013-01-01

    The exclusive photoproduction of Υ has been studied with the ZEUS detector in ep collisions at HERA. The exponential slope, b, of the |t|-dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured. This constitutes the first measurement of the |t|-dependence of the γp→Υp cross section. The differential crosssections as a function of t at lower energies of γp centre-of-mass has been studied in exclusive diffractive photoproduction of J/ψ mesons with the H1 detector. The exclusive electroproduction of two pions has been measured by the ZEUS experiment. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, assuming that the studied mass range includes the contributions of the ρ, ρ′ and . ρ'' vector-meson states.

  20. Measurement of the charged-pion polarisability at COMPASS

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    For more than a decade, COMPASS has been tackling the measurement of the electromagnetic polarizability of the charged pion, which describes the stiffness of the pion against deformation in electromagnetic fields. Previous experiments date back to the 1980's in Serpukhov (Russia), where the Primakoff method for realizing interactions of charged pions with quasi-real photons was first employed. Later also other techniques in photon-nucleon and photon-photon collisions were carried out at different machines. The COMPASS measurement demonstrates that the charged-pion polarizability is significantly smaller than the previous results, roughly by a factor two, with the smallest uncertainties realized so far. The pion polarisability is of fundamental interest in the low-energy sector of quantum chromodynamics. It is directly linked to the quark-gluon substructure and dynamics of the pion, the lightest bound system of strong interaction.

  1. Mechanism of the alkali degradation of (6-4) photoproduct-containing DNA.

    Science.gov (United States)

    Arichi, Norihito; Inase, Aki; Eto, Sachise; Mizukoshi, Toshimi; Yamamoto, Junpei; Iwai, Shigenori

    2012-03-21

    The (6-4) photoproduct is one of the major damaged bases produced by ultraviolet light in DNA. This lesion is known to be alkali-labile, and strand breaks occur at its sites when UV-irradiated DNA is treated with hot alkali. We have analyzed the product obtained by the alkali treatment of a dinucleoside monophosphate containing the (6-4) photoproduct, by HPLC, NMR spectroscopy, and mass spectrometry. We previously found that the N3-C4 bond of the 5' component was hydrolyzed by a mild alkali treatment, and the present study revealed that the following reaction was the hydrolysis of the glycosidic bond at the 3' component. The sugar moiety of this component was lost, even when a 3'-flanking nucleotide was not present. Glycosidic bond hydrolysis was also observed for a dimer and a trimer containing 5-methyl-2-pyrimidinone, which was used as an analog of the 3' component of the (6-4) photoproduct, and its mechanism was elucidated. Finally, the alkali treatment of a tetramer, d(GT(6-4)TC), yielded 2'-deoxycytidine 5'-monophosphate, while 2'-deoxyguanosine 3'-monophosphate was not detected. This result demonstrated the hydrolysis of the glycosidic bond at the 3' component of the (6-4) photoproduct and the subsequent strand break by β-elimination. It was also shown that the glycosidic bond at the 3' component of the Dewar valence isomer was more alkali-labile than that of the (6-4) photoproduct.

  2. Photoproduction of the vector mesons ω(782) and φ(1020) on the proton from the production threshold up to a photon energy of 2. 6 GeV

    International Nuclear Information System (INIS)

    Barth, J.

    2002-05-01

    This paper reports on a measurement of the photoproduction of ω(782) and Φ(1020) vector mesons with the SAPHIR detector at the electron accelerator facility ELSA. The incident photons were tagged in an energy range from reaction threshold up to 2.6 GeV. ω and Φ events were selected by separating their signal in the invariant mass spectrum of their decay products, i.e. in the π + π - π 0 and the K + K - system, respectively. As a cross check for normalization the inclusive two and three pion production was evaluated. The results agree with earlier experiments. From the experimental data total cross sections σ tot , differential cross sections dσ/dt as well as decay angular distributions in both, Gottfried Jackson and helicity frames, were extracted. For the ω production they show that diffractive processes play an important role as expected from higher energy data. However, at threshold s-channel resonances significantly contribute. In the region of large four-momentum transfers (vertical stroke t vertical stroke > 1 GeV 2 ) significant deviations from t-channel exchange mechanisms are observed. The Φ production can be described mainly by diffraction, but also other t-channel exchange processes seem to contribute. (orig.)

  3. Pion production in relativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Norbury, J.W.

    1983-01-01

    A Lorentz-invariant differential cross section for pion production in peripheral, relativistic, heavy ion collisions is calculated for the collisions of an 16 O projectile onto a 12 C target. The pions are produced via excitations of a Δ(3,3) resonant state in the projectile with simultaneous excitation of an M1 giant resonance in the target. A second order amplitude describing resonance formation and decay is derived within the context of second order, time-dependent perturbation theory and a corresponding transition rate is evaluated. This is then applied to the problem of pion production and a differential cross section is calculated using a simple product-of-states model. The whole theory is then re-formulated within a second quantized particle-hole model which describes the basic process of M1 giant resonance formation as well as the formation and decay of the intermediate Δ(3,3) resonance. Subsequently, a new Lorentz-invariant differential cross section is calculated from the particle-hole amplitude. The theoretical cross section is compared with some experimental data and the agreement is found to be satisfactory given the nature of the data and the assumptions of the theory

  4. Mechanism of pion absorption in complex nuclei

    International Nuclear Information System (INIS)

    Doss, K.G.N.; Wharton, W.R.

    Basic geometrical arguments are used to analyze the A dependence of the total pion absorption cross section, the effective number of nucleons sharing the pion momentum and energy, and the proton yields from π + - and π - -induced reactions. The results are consistent with the pions penetrating some distance through the nuclear volume and annihilating on a pair of nucleons. 3 figures

  5. Real-pion states formed by virtual-pion beam

    International Nuclear Information System (INIS)

    Yamazaki, Toshimitsu.

    1990-04-01

    Deeply bound pionic states are discussed from various points of view; highly excited nuclear states as a cluster family of pionic bound states, Σ atom/Σ hypernuclei, halo-like density distributions, virtual pion beam to produce pionic states, etc. (author)

  6. Pion production cross sections and associated parameters

    International Nuclear Information System (INIS)

    Bradbury, J.N.

    1985-01-01

    Negative pions have been used for radiotherapy at the meson factories LAMPF (USA), SIN (Switzerland), and TRIUMF (Canada) and have been planned for use at new meson facilities under construction (USSR) and at proposed dedicated medical facilities. Providing therapeutically useful dose rates of pions requires a knowledge of the pion production cross sections as a function of primary proton energy (500 to 1000 MeV), pion energy (less than or equal to100 MeV), production angle, and target material. The current status of the data base in this area is presented including theoretical guidelines for extrapolation purposes. The target material and geometry, as well as the proton and pion beam parameters, will affect the electron (and muon) contamination in the beam which may have an important effect on both the LET characteristics of the dose and the dose distribution. In addition to cross-section data, channel characteristics such as length of pion trajectory, solid-angle acceptance, and momentum analysis will affect dose rate, distribution, and quality. Such considerations are briefly addressed in terms of existing facilities and proposed systems. 16 refs., 6 figs

  7. The two-nucleon system above pion threshold

    International Nuclear Information System (INIS)

    Poepping, H.; Sauer, P.U.; Zhang Xizhen

    1987-01-01

    A force model is presented for the description of the two-nucleon system below and above pion threshold and its coupled inelastic channels with one pion. It uses Δ-isobar and pion degrees of freedom in addition to the nucleonic one. The force model is based on a hamiltonian approach within the framework of noncovariant quantum mechanics. It extends the traditional approach with purely nucleonic potentials in isospin-triplet partial waves. It is constructed to remain valid up to 500 MeV c.m. energy. The characteristics of the force model is its mechanism for pion production and pion absorption which is mediated by the Δ-isobar. Even without any fit of phenomenological parameters the force model is able to account for the experimental data of elastic nucleon-nucleon scattering' of the inelastic reactions pp ↔ π + d and of elastic pion-deuteron scattering with satisfactory accuracy. No need for the introduction of dibaryon degrees of freedom has been found yet. The force model is a realistic one in the two-nucleon system. In many-nucleon systems it forms the unifying basis for a microscopic description of nuclear structure and nuclear reactions at low and intermediate energies. (orig.)

  8. Inelastic J/Ψ photoproduction off nuclei: Gluon enhancement or double color exchange?

    International Nuclear Information System (INIS)

    Huefner, J.; Zamolodchikov, A.

    1996-01-01

    The nuclear enhancement observed in inelastic photoproduction of J/Ψ should not be interpreted as evidence for an increased gluon density in nuclei. The nuclear suppression of the production rate due to initial and final state interactions is calculated and a novel two-step color exchange process is proposed, which is able to explain the data. (orig.)

  9. Evidence for a ωrhosup(+-)πsup(+-) state in diffractive photoproduction

    International Nuclear Information System (INIS)

    Atkinson, M.; Davenport, M.; Flower, P.; Hutton, J.S.; Kumar, B.R.; Morris, J.A.G.; Morris, J.V.; Sharp, P.H.; Brodbeck, T.J.; Clegg, A.B.; Flynn, P.J.; Henderson, R.C.W.; Newton, D.; Brookes, G.R.; Bunn, J.J.; Galbraith, W.; McClatchey, R.H.; Bussey, P.J.; Dainton, J.B.; Paterson, C.; Raine, C.; Skillicorn, I.O.; Smith, K.M.; Diekmann, B.; Heinloth, K.; Jakob, H.P.; Jung, M.; Liebenau, V.; Paul, E.; Reidenbach, M.; Rotscheidt, H.; Schloesser, A.; Laberrigue, J.; La Vaissilere, C. de; Yiou, T.P.

    1985-01-01

    The photoproduction of the final state ωπ + π - π 0 has been studied as part of a survey of photoproduction in the energy range 20-70 GeV in the Omega spectrometer at CERN. The π + π - π 0 system produced with the ω meson has a strong rhosup(+-)πsup(+-) component which is predominantly I=1 and Jsup(π)=1+. For the ωrhosup(+-)π + state a spin-parity analysis favours Jsup(π)=1-, and the mass spectrum peaks at 2.28+-0.05 GeV. The fitted width is GAMMA=0.44+-0.11 GeV. The photoproduction cross-section of the ωrhosup(+-)rhosup(+-) state, averaged over the energy range 25-60 GeV, is 150+-50 nb. (orig.)

  10. Radiative corrections to the charged pion-pair production process {pi}{sup -}{gamma} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup -} at low energies

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, N.; Petschauer, S. [Technische Universitaet Muenchen, Physik-Department T39, Garching (Germany)

    2013-12-15

    We calculate the one-photon loop radiative corrections to the charged pion-pair production process {pi}{sup -}{gamma} {yields} {pi}{sup +}{pi}{sup -}{pi}{sup -}. In the low-energy region this reaction is governed by the chiral pion-pion interaction. The pertinent set of 42 irreducible photon-loop diagrams is calculated by using the package FeynCalc. Electromagnetic counterterms with two independent low-energy constants k{sub 1} and k{sub 2} are included in order to remove the ultraviolet divergences generated by the photon loops. Infrared finiteness of the virtual radiative corrections is achieved by including soft photon radiation below an energy cut-off {Lambda}. The purely electromagnetic interaction of the charged pions mediated by one-photon exchange is also taken into account. The radiative corrections to the total cross section (in the isospin limit) vary between +10% close to threshold and about -1% at a center-of-mass energy of 7m{sub {pi}}. The largest contribution comes from the simple one-photon exchange. Radiative corrections to the {pi}{sup +}{pi}{sup -} and {pi}{sup -}{pi}{sup -} mass spectra are studied as well. The Coulomb singularity of the final-state interaction produces a kink in the dipion mass spectra. The virtual radiative corrections to elastic {pi}{sup -}{pi}{sup -} scattering are derived additionally. (orig.)

  11. Can we get deeper inside the pion at the LHC?

    Energy Technology Data Exchange (ETDEWEB)

    Petrov, V.A.; Ryutin, R.A.; Sobol, A.E. [Institute for High Energy Physics, Protvino (Russian Federation); Murray, M.J. [University of Kansas, Kansas City, KS (United States)

    2012-02-15

    We propose a measurement of leading neutrons spectra at LHC in order to extract inclusive {pi}{sup +} p and {pi}{sup +}{pi} {sup +} cross-sections with high p{sub T} jets production. The cross-sections for these processes are simulated with the use of parton distributions in hadrons. In this work we estimate the possibility to extract parton distributions in the pion from the data on these cross-sections and also search for signatures of fundamental differences in the pion and proton structure. (orig.)

  12. Pion broadening and low-mass dilepton production

    International Nuclear Information System (INIS)

    Schulze, H.-J.; Blaschke, D.

    2002-01-01

    Mass and transverse momentum spectra of dileptons produced in Pb + Au (158 GeV/u) collisions within a pion annihilation model are determined. A fit to the data requires simultaneous mass reduction and broadening of the in-medium rho propagator. The introduction of a finite pion width, as required within self-consistent approaches to the interacting pion gas, further improves the agreement with the data

  13. Jet shapes in charm photoproduction and deeply inelastic scattering at HERA

    International Nuclear Information System (INIS)

    Grell, Brian Rosenvold

    2010-09-01

    This analysis investigates charm production processes in photoproduction and deeply inelastic scattering. The analysed data was collected with the H1 detector at the HERA accelerator in the years 1999-2000 for photoproduction and 2004-2007 for deeply inelastic scattering, corresponding to integrated luminosities of 83 pb -1 , respectively 348 pb -1 . Dijet events are selected with jet transverse momenta of at least 5 GeV, respectively 4 GeV, in the central rapidity region. One jet is tagged by a D * meson to be initiated by a charm quark. The other is studied with respect to its mean integrated jet shape in order to deduce to which fraction it is initiated by a quark or a gluon. The jet shape is described by the fraction ψ(r) of the jet energy inside a cone of radius r around the jet axis; it is found that for r=0:6, ψ(r) is most sensitive to differences between charm and light quark or gluon jets. The shape is measured as a function of various kinematic variables such as the jet energy and pseudorapidity, photon virtuality and x γ obs , the fraction of the photon momentum entering the hard interaction. The photoproduction data is compared to Pythia, the DIS data to RapGap Monte Carlo simulations. In the Monte Carlo calculation, direct and resolved photon processes are simulated separately to compare samples with an enriched fraction of quark, respectively gluon initiated jets. Deviations at low x γ obs are observed for higher values of Q 2 , where direct and resolved expectations are nearly identical, hinting at an overestimation of gluon initiated jets. In most regions of phase space though, the resolution of the measurement excels the difference between direct and resolved predictions, allowing a distinction of such event samples. (orig.)

  14. Jet shapes in charm photoproduction and deeply inelastic scattering at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Grell, Brian Rosenvold

    2010-09-15

    This analysis investigates charm production processes in photoproduction and deeply inelastic scattering. The analysed data was collected with the H1 detector at the HERA accelerator in the years 1999-2000 for photoproduction and 2004-2007 for deeply inelastic scattering, corresponding to integrated luminosities of 83 pb{sup -1}, respectively 348 pb{sup -1}. Dijet events are selected with jet transverse momenta of at least 5 GeV, respectively 4 GeV, in the central rapidity region. One jet is tagged by a D{sup *} meson to be initiated by a charm quark. The other is studied with respect to its mean integrated jet shape in order to deduce to which fraction it is initiated by a quark or a gluon. The jet shape is described by the fraction {psi}(r) of the jet energy inside a cone of radius r around the jet axis; it is found that for r=0:6, {psi}(r) is most sensitive to differences between charm and light quark or gluon jets. The shape is measured as a function of various kinematic variables such as the jet energy and pseudorapidity, photon virtuality and x{sub {gamma}}{sup obs}, the fraction of the photon momentum entering the hard interaction. The photoproduction data is compared to Pythia, the DIS data to RapGap Monte Carlo simulations. In the Monte Carlo calculation, direct and resolved photon processes are simulated separately to compare samples with an enriched fraction of quark, respectively gluon initiated jets. Deviations at low x{sub {gamma}}{sup obs} are observed for higher values of Q{sup 2}, where direct and resolved expectations are nearly identical, hinting at an overestimation of gluon initiated jets. In most regions of phase space though, the resolution of the measurement excels the difference between direct and resolved predictions, allowing a distinction of such event samples. (orig.)

  15. DWIA in the momentum space for (γ,π0) reaction near threshold

    International Nuclear Information System (INIS)

    Chumbalov, A.A.; Eramzhyan, R.A.; Kamalov, S.S.

    1987-01-01

    Differential cross sections and total cross sections of coherent photoproduction of neutral pions on 4 He, 12 C and 40 Ca nuclei using impulse approximation and the method of distorted waves in impulse representation are calculated. Pion distortion wave effects near threshold of photon energy are shown not to exceed 25%. Good agreement with the experiment is reached due to the application of total elementary amplitude, which takes into account both nonlinear terms in a pion momentum and the terms, which depends on the pion momentum

  16. Pion interferometric tests of transport models

    Energy Technology Data Exchange (ETDEWEB)

    Padula, S.S.; Gyulassy, M.; Gavin, S. (Lawrence Berkeley Lab., CA (USA). Nuclear Science Div.)

    1990-01-08

    In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.).

  17. Pion interferometric tests of transport models

    International Nuclear Information System (INIS)

    Padula, S.S.; Gyulassy, M.; Gavin, S.

    1990-01-01

    In hadronic reactions, the usual space-time interpretation of pion interferometry often breaks down due to strong correlations between spatial and momentum coordinates. We derive a general interferometry formula based on the Wigner density formalism that allows for arbitrary phase space and multiparticle correlations. Correction terms due to intermediate state pion cascading are derived using semiclassical hadronic transport theory. Finite wave packets are used to reveal the sensitivity of pion interference effects on the details of the production dynamics. The covariant generalization of the formula is shown to be equivalent to the formula derived via an alternate current ensemble formalism for minimal wave packets and reduces in the nonrelativistic limit to a formula derived by Pratt. The final expression is ideally suited for pion interferometric tests of Monte Carlo transport models. Examples involving gaussian and inside-outside phase space distributions are considered. (orig.)

  18. Hadron photoproduction at medium energy

    International Nuclear Information System (INIS)

    Dainton, J.B.

    1985-04-01

    Results from measurements of multibody photoproduction at medium incident photon energy (2.8 to 4.8 GeV) are presented and discussed. Particular emphasis is placed on topics which are not well understood and which therefore motivate experiments with the upgraded electron accelerator and storage ring ELSA at the University of Bonn, FR Germany. (author)

  19. Three- and four-jet final states in photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2007-08-15

    Three- and four-jet final states have been measured in photoproduction at HERA using the ZEUS detector with an integrated luminosity of 121 pb{sup -1}. The results are presented for jets with transverse energy E{sup jet}{sub T}>6 GeV and pseudorapidity vertical stroke {eta}{sup jet} vertical stroke <2.4, in the kinematic region given by the virtuality of the photon Q{sup 2}<1 GeV{sup 2} and the inelasticity 0.2{<=}y{<=}0.85 and in two mass regions defined as 25{<=}M{sub nj}<50 GeV and M{sub nj}{>=}50 GeV, where M{sub nj} is the invariant mass of the n-jet system. The four-jet photoproduction cross section has been measured for the first time and represents the highest-order process studied at HERA. Both the three- and four-jet cross sections have been compared with leading-logarithmic parton-shower Monte Carlo models, with and without multi-parton interactions. The three-jet cross sections have been compared to an O({alpha}{alpha}{sup 2}{sub s}) perturbative QCD calculation. (orig.)

  20. Landau-Migdal parameters and pion condensation

    Energy Technology Data Exchange (ETDEWEB)

    Tatsumi, Toshitaka [Department of Physics, Kyoto Univ., Kyoto (Japan)

    1999-08-01

    The possibility of pion condensation, one of the long-standing issues in nuclear physics, is reexamined in the light of the recent experimental data on the giant Gamow-Teller resonance. The experimental result tells that the coupling of nucleon particle-hole states with {delta} isobar-hole states in the spin-isospin channel should be weaker than that previously believed. It, in turn, implies that nuclear matter has the making of pion condensation at low densities. The possibility and implications of pion condensation in the heavy-ion collisions and neutron stars should be seriously reconsidered. (author)

  1. Strangeness photoproduction with the SAPHIR-detector

    International Nuclear Information System (INIS)

    Merkel, H.

    1993-12-01

    At the ELSA facility at Bonn a photon beam with a high duty cycle up to energies of 3.3 GeV is available. In this energy range the large solid angle detector SAPHIR enables us to investigate the strangeness photoproduction starting from threshold. SAPHIR has already achieved results for the reactions γ+p→K + +Λ and γ+p→K + +Σ 0 . This work investigates the possibilities to measure the related reactions γ+n→K 0 +Λ and γ+n→K 0 +Σ 0 at a deuteron target and to measure the reaction γ+p→K 0 +Σ + at a proton target. For the first time the Σ + polarisation has been measured. With an cross section 10 times smaller compared to the kaon hyperon reactions, the photoproduction of the Φ(1020) meson can be investigated with the SAPHIR detector too. First reconstructed events are shown. (orig.)

  2. RAYPHOTON version 2. 0 - an interface for HERA photoproduction physics

    Energy Technology Data Exchange (ETDEWEB)

    Brook, N.H.; Doyle, A.T. (Glasgow Univ. (United Kingdom). Dept. of Physics and Astronomy); DeRoeck, A. (Max-Planck-Institut fuer Physik, Muenchen (Germany). Werner-Heisenberg Inst.)

    1992-04-01

    RAYPHOTON allows photoproduction of both light and heavy quarks for the direct and resolved photon. It is a convolution of the Weiszaecker-Williams approximation with the cross section for the hard interaction. The hard interaction cross sections and colour flows are set up using the generators for real photoproduction LUCIFER, for the direct photon, and TWISTER, for the resolved photon. It includes QCD cascades in the colour dipole formalism, via an interface, RADIATE, to the ARIADNE package. (orig.).

  3. In vitro residual anti-bacterial activity of difloxacin, sarafloxacin and their photoproducts after photolysis in water

    International Nuclear Information System (INIS)

    Kusari, Souvik; Prabhakaran, Deivasigamani; Lamshoeft, Marc; Spiteller, Michael

    2009-01-01

    Fluoroquinolones like difloxacin (DIF) and sarafloxacin (SARA) are adsorbed in soil and enter the aquatic environment wherein they are subjected to photolytic degradation. To evaluate the fate of DIF and SARA, their photolysis was performed in water under stimulated natural sunlight conditions. DIF primarily degrades to SARA. On prolonged photodegradation, seven photoproducts were elucidated by HR-LC-MS/MS, three of which were entirely novel. The residual anti-bacterial activities of DIF, SARA and their photoproducts were studied against a group of pathogenic strains. DIF and SARA revealed potency against both Gram-positive and -negative bacteria. The photoproducts also exhibited varying degrees of efficacies against the tested bacteria. Even without isolating the individual photoproducts, their impact on the aquatic environment could be assessed. Therefore, the present results call for prudence in estimating the fate of these compounds in water and in avoiding emergence of resistance in bacteria caused by the photoproducts of DIF and SARA. - Assessment of the residual anti-bacterial efficacies of difloxacin, sarafloxacin and their photoproducts in water, and estimating their impact on the aquatic environment in inducing resistance to microorganisms.

  4. Study of the Production of Single Pions in Pion-proton Collisions near Threshold

    CERN Multimedia

    2002-01-01

    This experiment aims at a complete-kinematics measurement of the processes @p|-p @A @p|-@p|+n and @p|+p @A @p|+@p|+n in the region of incident momenta between 300 MeV/c and 460 MeV/c. It uses the Omicron Spectrometer with detectors placed in the magnetic field close to a 12 atm. hydrogen gas target. The apparatus has an acceptance of 4\\% for the processes to be studied. \\\\ \\\\ Their threshold is at 279 MeV/c and pion production in this region is interesting from the point of view of the determination of transformation properties of the chiral-symmetry-breaking part of the Lagrangian.

  5. Factorization and pion form factor in QCD

    International Nuclear Information System (INIS)

    Efremov, A.V.; Radyushkin, A.V.

    1979-01-01

    The behaviour of the pion electromagnetic form factor (EMFF) in the framework of quantum chromodynamics (QCD) is discussed. Pion is considered to be a quark-antiquark bound state. It is proposed to use an OPE description of the bound state structure by matrix elements of certain local gauge-invariant operators. Short-distance quark interactions is proved using a direct analysis of perturbation theory in the α-parametric representation of the Feynman diagrams. It is shown that the short-distance parton picture privides a self-consistent description of the large Q 2 momentum behaviour of the pion EMFF in QCD. Pion EMFF asymptotics is expressed in terms of fu fundamental constants of the theory

  6. Isospin violation in pion-kaon scattering

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meissner, Ulf-G.

    2002-01-01

    We consider strong and electromagnetic isospin violation in near-threshold pion-kaon scattering. At tree level, such effects are small for all physical channels. We work out the complete one-loop corrections to the process π - K + →π 0 K 0 . They come out rather small. We also show that the corresponding radiative cross section is highly suppressed at threshold

  7. The future IKO-PION-MUON-facility

    International Nuclear Information System (INIS)

    Goudsmit, P.F.A.; Arnold, H.; Dantzig, R. van; Konijn, J.

    1975-09-01

    Information is given on the pion and muon physics facility planned at the Institute for Nuclear Physics Research (IKO) with special notice of the fluxes of pions and muons expected at this facility, as well as on the structure of these secondary beams

  8. Studies on the charge asymmetry in inclusive photoproduction of mesons in forward direction in the momentum range of 60-170 GeV/c at the CERN Ω-spectrometer

    International Nuclear Information System (INIS)

    Koersgen, G.

    1988-09-01

    This thesis describes in its first part the construction and the calibration of a Transition Radiation Detector (TRD) which was used in the photoproduction experiment WA69 at CERN (Geneva). The energy range of the incident photons was 65 GeV to 170 GeV. The detector consisted of 12 radiator-chamber systems. The radiators are of irregular radiator type, made of polypropylen fibres. The chambers are multiwire proportional chambers of thickness 1 cm and driven with a Xe/methane mixture of 90/10. The analysis of hadronic test beams has shown that the pion contamination of a data sample identified as kaons is 20% (8%) at 100 (150) GeV, both numbers given for a kaon efficiency of 80%. This is in agreement with theoretical expectation. The physics analysis deals with charge asymmetries in photoproduction of mesons in the beam fragmentation region. A positive excess has been found of the size 2.2±0.3% overall and 6.0±0.6% for strange particles. The dependence of the charge asymmetry upon the energy of the incident photons and on x F has been examined. It is in agreement with the assumption that the asymmetry found is caused by the annihilation reaction mentioned above. The same tendency occurs in a comparison with SLAC data taken at 20 GeV photon energy. (orig./HSI) [de

  9. CLEO and E791 Data A Smoking Gun for the Pion Distribution Amplitude?

    CERN Document Server

    Bakulev, A P; Stefanis, N G

    2003-01-01

    The CLEO experimental data on the \\pi\\gamma transition are analyzed to NLO in QCD perturbation theory using light-cone QCD sum rules. By processing the data along the lines proposed by Khodjamiryan, Schmedding and Yakovlev, and recently revised by us, we obtain new constraints for the Gegenbauer coefficients a_2 and a_4, as well as for the inverse moment \\langle{x^{-1}\\rangle of the pion distribution amplitude (DA). The former determine the pion DA at low momentum scale, the latter is crucial in calculating pion form factors. From the results of our analysis we conclude that the data confirm the shape of the pion DA we previously obtained with QCD sum rules and nonlocal condensates, while the exclusion of the asymptotic and the Chernyak-Zhitnitsky DA is reinforced. We also investigate the sensitivity of the calculated coefficients in this analysis to the twist-4 contribution and check out pion DA against the di-jets data of the E791 experiment, providing credible evidence for our results far more broadly. Thu...

  10. In-medium pion valence distributions in a light-front model

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de, E-mail: joao.mello@cruzeirodosul.edu.br [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Tsushima, K. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Ahmed, I. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); National Center for Physics, Quaidi-i-Azam University Campus, Islamabad 45320 (Pakistan)

    2017-03-10

    Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  11. Multipole analyses and photo-decay couplings at intermediate energies

    International Nuclear Information System (INIS)

    Workman, R.L.; Arndt, R.A.; Zhujun Li

    1992-01-01

    The authors describe the results of several multipole analyses of pion-photoproduction data to 2 GeV in the lab photon energy. Comparisons are made with previous analyses. The photo-decay couplings for the delta are examined in detail. Problems in the representation of photoproduction data are discussed, with an emphasis on the recent LEGS data. 16 refs., 4 tabs

  12. Anisotropy of the pion emission in relativistic nucleus-nucleus collisions

    International Nuclear Information System (INIS)

    Babinet, R.; Cavata, C.; Demoulins, M.; Fanet, H.; Gosset, J.; Lemaire, M.C.; Le Merdy, A.; L'Hote, D.; Lucas, B.; Poitou, J.; Alard, J.P.; Augerat, J.; Bastid, N.; Charmensat, P.; Dupieux, P.; Fraysse, L.; Marroncle, J.; Montarou, G.; Parizet, M.J.; Ramani, A.; Brochard, F.; Gorodetzky, P.; Racca, C.

    1990-01-01

    The production of pions and baryons from Ne and Ar induced reactions on Ca, NaF, Nb and Pb targets, in the range of .2 to 1 GeV per nucleon, is discussed. The 4π detector Diogenes at the Saturne accelerator facility is applied. The reaction plane is determined from the baryon momenta distribution and used as a reference for the pion triple differential cross-sections. A transverse momentum analysis is carried out for baryons and pions. The pion squared reduced impact parameter and the flow characteristics are given. The results show that the azimuthal anisotropy of pion emission increases with the asymmetry of the system. The evidence that pion absorption effects may be responsible for the azimuthal anisotropy of the pion emission is provided

  13. The pion mass: Looking for its origins

    International Nuclear Information System (INIS)

    Peccei, R.D.

    1985-10-01

    After explaining why pions are special excitations in QCD, I discuss how the pion mass reflects directly the dynamical scale of the strong interactions (Λsub(QCD)) and the scale of breaking of the weak interactions (Λsub(F)). To actually calculate the pion mass, however, requires understanding the origin of the quark masses and so I compare and contrast approaches to this latter problem, based on composite models and on superstrings. (orig.)

  14. Funny hills in pion spectra from heavy-ion collisions

    International Nuclear Information System (INIS)

    Rasmussen, J.O.

    1982-03-01

    A discussion of some of the systematic features of the pion spectra in heavy-ions reactions is given. A discussion of the hills and valleys in heavy ion pion spectra that show up at the lower pion energies is given. The following topics are discussed: (1) three kinds of funny hills; (2) π - / + ratios near center of mass; (3) new Monte Carlo studies of charged pion spectra; and (4) pion orbiting about fireballs and Bose-Einstein behavior as explanation for the mid-rapidity P/sub perpendicular to/ approx. = 0.4 to 0.5 m/sub π/c hill

  15. Negative pion irradiation of mammalian cells

    International Nuclear Information System (INIS)

    Dertinger, H.; Luecke-Huhle, C.; Schlag, H.; Weibezahn, K.F.

    1976-01-01

    Monolayers and spheroids of Chinese hamster cells (V79) were subjected to negative pion irradiation under aerobic conditions. R.b.e. values in the pion peak of 1.8 and 1.5 were obtained for monolayers and spheroids, respectively, whereas the r.b.e. for the plateau was found to be slightly higher than 1. In addition, it was observed that the higher resistance of the V79 spheroid cells than the monolayers to γ-irradiation is not diminished in the pion peak, suggesting that the underlying phenomenon of intercellular communication influences cell survival even after high-LET irradiation. (author)

  16. Beauty Photoproduction

    International Nuclear Information System (INIS)

    Turcato, M.

    2002-01-01

    Beauty photoproduction in ep collisions has been studied with the ZEUS detector at HERA, at a center-of-mass energy of 300 GeV. Beauty quarks are tagged via their semi-leptonic decay into a muon or an electron. Events are selected by requiring the presence of two high-transverse energy jets and one high - p T lepton in the final state. The discrimination between beauty and background events is done by a fit to the p rel T variable, the transverse momentum of the lepton with respect to the jet axis. Total and differential cross sections are presented and compared to leading order Monte Carlo simulations and next-to-leading order QCD predictions. (author)

  17. Covariant density functional theory: The role of the pion

    International Nuclear Information System (INIS)

    Lalazissis, G. A.; Karatzikos, S.; Serra, M.; Otsuka, T.; Ring, P.

    2009-01-01

    We investigate the role of the pion in covariant density functional theory. Starting from conventional relativistic mean field (RMF) theory with a nonlinear coupling of the σ meson and without exchange terms we add pions with a pseudovector coupling to the nucleons in relativistic Hartree-Fock approximation. In order to take into account the change of the pion field in the nuclear medium the effective coupling constant of the pion is treated as a free parameter. It is found that the inclusion of the pion to this sort of density functionals does not destroy the overall description of the bulk properties by RMF. On the other hand, the noncentral contribution of the pion (tensor coupling) does have effects on single particle energies and on binding energies of certain nuclei.

  18. Exclusive vector meson production at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Szuba, Dorota [Hamburg University, Hamburg (Germany); Collaboration: H1 Collaboration; ZEUS Collaboration

    2013-04-15

    The exclusive photoproduction of {Upsilon} has been studied with the ZEUS detector in ep collisions at HERA. The exponential slope, b, of the |t|-dependence of the cross section, where t is the squared four-momentum transfer at the proton vertex, has been measured. This constitutes the first measurement of the |t|-dependence of the {gamma}p{yields}{Upsilon}p cross section. The differential crosssections as a function of t at lower energies of {gamma}p centre-of-mass has been studied in exclusive diffractive photoproduction of J/{psi} mesons with the H1 detector. The exclusive electroproduction of two pions has been measured by the ZEUS experiment. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, assuming that the studied mass range includes the contributions of the {rho}, {rho} Prime and . {rho}'' vector-meson states.

  19. Strangeness photoproduction on the deuterium target

    NARCIS (Netherlands)

    Shende, Sugat Vyankatesh

    2007-01-01

    More information on the nucleon excitation function can be gained by studying the photoproduction experiments. In these experiments, the nucleon inside the nucleous is excited by shooting a high energy photon beam. The excited spectrum of the nucleon is then studied by measuring the energy and

  20. High-energy photoproduction of neutral mesons

    CERN Document Server

    Charity, Tim

    1987-01-01

    This thesis presents results from the first full period of data-taking of the experiment WA69 at the Omega^'^ectrometer, CERN, Geneva. The experiment used a tagged photon beam of energy 60-180 GeV incident on a liquid hydrogen target to study photoproduction of hadronic states. The various components of the experiment are described, with particular emphasis on the electromagnetic calorimeters, and the associated offline software for event reconstruction and acceptance calculation. The performance of the outer calorimeter is discussed, and the pi^0 detection and reconstruction efficiency is examined by comparison with pi^{+/- } production. Searches for photoproduction of neutral meson states reveal a clear signal for the pi^0, eta^0 , and omega^0 mesons. The cross-section for elastic omega^0 production is estimated, and found to be consistent with the established value of 1 mub. The cross-section for inclusive pi^0 and eta^0 production is studied using the variable Feynman-x (x_{F }), and pi^0 production as a ...

  1. Inelastic quarkonium photoproduction in hadron-hadron interactions at LHC energies

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, V.P. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Pelotas, RS (Brazil); Machado, M.M. [Ciencia e Tecnologia, IF - Farroupilha, Instituto Federal de Educacao, Sao Borja, RS (Brazil)

    2014-04-15

    In this paper we study the inelastic quarkonium photoproduction in coherent pp/p Pb/PbPb interactions. Considering the ultra-relativistic hadrons as a source of photons, we estimate the total h{sub 1}+h{sub 2} → h x V+X (V=J/Ψ and Υ) cross sections and rapidity distributions at LHC energies. Our results demonstrate that the experimental analysis of this process can be used to understand the underlying mechanism governing heavy quarkonium production. (orig.)

  2. Pion-nucleon vertex function and the Chew-Low model

    International Nuclear Information System (INIS)

    Nutt, W.T.

    1977-01-01

    We provide an interpretation of the cutoff function used in the Chew-Low theory of pion-nucleon scattering. It is shown that this function may be related to the pion-pion interaction which is not explicitly considered in the Chew-Low approach. Using a previously developed model for the pion-nucleon vertex function, we then perform a ''parameter-free'' Chew-Low calculation which predicts the P 33 resonance quite well

  3. Pion nucleus optical potential

    International Nuclear Information System (INIS)

    Kam, J. de.

    1981-01-01

    The main goal of the investigations, presented is to establish the contributions to the optical potential, coming from scattering processes which involve 1p-1h nuclear states in the intermediate scattering system. The effects of the Pauli principle corrections and the binding corrections are studied in detail. A phenomenological study of pion absorption effects is also presented. The calculations all concern π- 4 He scattering. The simplicity of the 4 He structure makes the π- 4 He system quite an ideal tool for studying the reaction mechanism. (Auth.)

  4. A measurement of the pion charge radius

    International Nuclear Information System (INIS)

    Amendolia, S.R.; Badelek, B.; Batignani, G.; Bedeschi, F.; Bertolucci, E.; Bettoni, D.; Bosisio, L.; Bradaschia, C.; Dell'Orso, M.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Scribano, A.; Tonelli, G.; Codino, A.; Fabbri, F.L.; Laurelli, P.; Satta, L.; Spillantini, P.; Zallo, A.; Counihan, M.J.; Frank, S.G.F.; Harvey, J.; Storey, D.; Menasce, D.; Meroni, E.; Moroni, L.

    1984-01-01

    We report a measurement of the negative pion electromagnetic form factor in the range of space-like four-momentum transfer 0.014 2 2 . The measurement was made by the NA7 collaboration at the CERN SPS, by observing the interaction of 300 GeV pions with the electrons of a liquid hydrogen target. The form factor is fitted by a pole form with a pion radius of (rho 2 )sup(1/2) = 0.657 +- 0.012 fm. (orig.)

  5. Experiments at INS electron synchrotron

    International Nuclear Information System (INIS)

    Kato, Sadayuki

    1982-01-01

    Photoproduction of pion and proton on nuclei in 1 GeV energies region are discussed in order to study the nuclear structure. We illustrate how those reactions can be used to obtain information on short range nature of the pion wave function and on nuclear wave functions. Also we discuss about the dibaryon resonances and the deutron wave function

  6. Isospin violation in pion-kaon scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, Bastian E-mail: b.kubis@fz-juelich.de; Meissner, Ulf-G. E-mail: ulf-g.meissner@fz-juelich.de

    2002-03-11

    We consider strong and electromagnetic isospin violation in near-threshold pion-kaon scattering. At tree level, such effects are small for all physical channels. We work out the complete one-loop corrections to the process {pi}{sup -}K{sup +}{yields}{pi}{sup 0}K{sup 0}. They come out rather small. We also show that the corresponding radiative cross section is highly suppressed at threshold.

  7. The relative cytotoxicity and mutagenicity of cyclobutane pyrimidine dimers and photoproducts in Escherichia coli cells

    International Nuclear Information System (INIS)

    Tang, Moon-shong; Hrncir, J.; Mitchell, D.; Ross, J.; Clarkson, J.

    1986-01-01

    In order to calculate the relative cytotoxicity and mutagenicity of cyclobutane pyrimidine dimers and photoproducts, the authors have measured survival and mutation induction in UV-irradiated excision-deficient E. coli uvrA cells, with or without complete photoreactivation of the dimers. Radioimmunoassays with specificity for dimers or photoproducts have shown that maximum photoreactivation eliminates all of the dimers produce up to 10 Jm -2 254-nm light, while it has no effect on photoproducts. These results were confirmed by measuring the frequency of T4 endonuclease V-sensitive sites. Based on the best fit equations for survival and mutation induction, the authors have found that the calculated cytotoxicity of photoproducts is similar to that of dimers; however, the former is much more mutagenic than the latter. (Auth.)

  8. MC rate at NLO for heavy flavour photoproduction at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Toll, Tobias

    2010-02-15

    A Monte Carlo at next-to-leading order (MC rate at NLO) has been constructed for the production of heavy quark flavours in photoproduction. As such, it is the rst Monte Carlo event generator with next-to-leading order (NLO) accuracy for a process in lepton hadron scattering. In order to construct such an MC rate at NLO, the matrix element for the process has to be calculated at NLO and then be matched with a parton shower. When doing this, it is important that none of the parton configurations produced are doubly counted. In this thesis, the concept of a Monte Carlo event generator will be explained, with emphasis on the HERWIG parton shower. Also, different techniques of calculating matrix elements at NLO accuracy will be explained. It will then be shown how the NLO calculation can be matched with the HERWIG parton shower in an MC rate at NLO without double counting, producing unweighted events at NLO-accuracy. Many comparisons are made between the MC rate at NLO here constructed, the HERWIG Monte Carlo and the FMNR NLO calculation. Also many comparisons are made to HERA data from the H1 and ZEUS experiments. It is shown that all HERA data with heavy quarks produced in photoproduction can be described by the MC rate at NLO program constructed in this thesis. (orig.)

  9. MC rate at NLO for heavy flavour photoproduction at HERA

    International Nuclear Information System (INIS)

    Toll, Tobias

    2010-02-01

    A Monte Carlo at next-to-leading order (MC rate at NLO) has been constructed for the production of heavy quark flavours in photoproduction. As such, it is the rst Monte Carlo event generator with next-to-leading order (NLO) accuracy for a process in lepton hadron scattering. In order to construct such an MC rate at NLO, the matrix element for the process has to be calculated at NLO and then be matched with a parton shower. When doing this, it is important that none of the parton configurations produced are doubly counted. In this thesis, the concept of a Monte Carlo event generator will be explained, with emphasis on the HERWIG parton shower. Also, different techniques of calculating matrix elements at NLO accuracy will be explained. It will then be shown how the NLO calculation can be matched with the HERWIG parton shower in an MC rate at NLO without double counting, producing unweighted events at NLO-accuracy. Many comparisons are made between the MC rate at NLO here constructed, the HERWIG Monte Carlo and the FMNR NLO calculation. Also many comparisons are made to HERA data from the H1 and ZEUS experiments. It is shown that all HERA data with heavy quarks produced in photoproduction can be described by the MC rate at NLO program constructed in this thesis. (orig.)

  10. Remarks on the pion-nucleon σ-term

    Science.gov (United States)

    Hoferichter, Martin; Ruiz de Elvira, Jacobo; Kubis, Bastian; Meißner, Ulf-G.

    2016-09-01

    The pion-nucleon σ-term can be stringently constrained by the combination of analyticity, unitarity, and crossing symmetry with phenomenological information on the pion-nucleon scattering lengths. Recently, lattice calculations at the physical point have been reported that find lower values by about 3σ with respect to the phenomenological determination. We point out that a lattice measurement of the pion-nucleon scattering lengths could help resolve the situation by testing the values extracted from spectroscopy measurements in pionic atoms.

  11. Goldberger-Treiman discrepancy and the momentum variation of the pion-nucleon form factor and pion decay constant

    International Nuclear Information System (INIS)

    Coon, S.A.; Scadron, M.D.

    1981-01-01

    We suggest that the observed 6% Goldberger-Treiman discrepancy is due in part to a 3% variation in the pion-nucleon form factor and in part due to a 3% variation in the pion decay form factor from q 2 =m/sub π/ 2 to q 2 =0

  12. Proton compton scattering in the resonance region

    International Nuclear Information System (INIS)

    Ishii, Takanobu.

    1979-12-01

    Differential cross sections of the proton Compton scattering have been measured in the energy range between 400 and 1150 MeV at CMS angles of 130 0 , 100 0 and 70 0 . The recoil proton was detected with a magnetic spectrometer using multi-wire proportional chambers and wire spark chambers. In coincidence with the proton, the scattered photon was detected with a lead glass Cerenkov counter of the total absorption type with a lead plate converter, and horizontal and vertical scintillation counter hodoscopes. The background due to the neutral pion photoproduction, was subtracted by using the kinematic relations between the scattered photon and the recoil proton. Theoretical calculations based on an isobar model with two components, that is, the resonance plus background, were done, and the photon couplings of the second resonance region were determined firstly from the proton Compton data. The results are that the helicity 1/2 photon couplings of P 11 (1470) and S 11 (1535), and the helicity 3/2 photon coupling of D 13 (1520) are consistent with those determined from the single pion photoproduction data, but the helicity 1/2 photon coupling of D 13 (1520) has a somewhat larger value than that from the single pion photoproduction data. (author)

  13. High resolution studies of pion-nucleus reaction mechanism

    International Nuclear Information System (INIS)

    Morris, C.L.

    1983-01-01

    Pion inelastic scattering is generally well described as a first order process using the DWIA. This is especially true for a large body of inelastic scattering data to low-lying collective states which is well-described by form factors obtained in (e,e') and the DWIA. Some data for which this model does not work are presented. Higher order reaction mechanisms have been invoked to explain some of these data. However, no model of these second order processes gives a satisfactory explanation of the entire data set. Experimentally, more data for pion-induced transitions to low-spin unnatural-parity states which have been studied by other probes would be useful in sorting out the reaction mechanisms responsible for the anomalous cross sections observed for the 1 + states in 12 C. Theoretically, a consistent evaluation of possible second-order diagrams in inelastic scattering, such as is being attempted for DCX 22 , would be useful

  14. Study of the incident pion deflection in passing through atomic nucleus

    International Nuclear Information System (INIS)

    Strugalski, Z.; Pawlak, T.; Pluta, J.

    1982-01-01

    Pion-xenon nucleus collision events at 3.5 GeV/c momentum are studied in which the incident pion is deflected only, without particle production; the deflection is accompanied by emission of nucleons. The multiplicity of the protons emitted is a measure of the nuclear matter layer thickness passed by the pion. It can be concluded that: a) a definite simple relation exists between the pion deflection angle and the thickness of the nuclear matter layer traversed by this pion; b) the deflection angle of the incident pion increases in a definite manner with increasing the thickness of the nuclear matter layer traversed by this pion; c) the average kinetic energy, average longitudinal momentum and average transverse momentum of the protons emitted do not depend on the pion deflection angle

  15. Investigation of pion-nucleus interactions

    International Nuclear Information System (INIS)

    Moore, C.F.

    1992-09-01

    This report summarizes the work carried out by personnel from the University of Texas at Austin at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). The research activities involved experiments done with the Energetic Pion Channel and Spectrometer (EPICS), the Low Energy Pion Channel (LEP), the Pion and Particle Physics Channel (P 3 ), the High Resolution Spectrometer (HRS), and planning a new experimental program associated with the new high-resolution Neutral Meson Spectrometer (NMS) at LAMPF. A brief overview of work supported by this grant is given followed by an account of the study of the double giant resonances in pion double charge exchange on 51 V, 115 In, and 197 Au. This report contains a list of published papers and preprints, abstracts, and invited talks. These papers summarize experiments involving participants supported by this grant and indicate the work accomplished by these participants in this program of medium energy nuclear physics research. Lists of the most recent proposals on which we have participation at LAMPF, proposals which have been approved this past year to run as experiments, personnel who have participated in this research program are included. The research cited in this report is, in many cases, the collaborative effort of many groups associated with research at LAMPF

  16. Experimental studies of pion-nucleus interactions at intermediate energies

    International Nuclear Information System (INIS)

    1991-01-01

    This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991 under a great from the US Department of Energy. Most of these studies have involved investigations of various pion-nucleus interactions. The work has been carried out both with the LAMPF accelerator at the Los Alamos National Laboratory and with the cyclotron at the Paul Scherrer Institute (PSI) near Zurich, Switzerland. Part of the experimental work involves measurements of new data on double-charge-exchange scattering, using facilities at LAMPF which we helped modify, and on pion absorption, using a new detector system at PSI that covers nearly the full solid-angle region which we helped construct. Other work involved preparation for future experiments using polarized nuclear targets and a new high-resolution spectrometer system for detecting π 0 mesons. We also presented several proposals for works to be done in future years, involving studies related to pi-mesonic atoms, fundamental pion-nucleon interactions, studies of the difference between charged and neutral pion interactions with the nucleon, studies of the isospin structure of pion-nucleus interactions, and pion scattering from polarized 3 He targets. This work is aimed at improving our understanding of the pion-nucleon interaction, of the pion-nucleus interaction mechanism, and of nuclear structure

  17. Rho0 Photoproduction in Ultra-Peripheral Relativistic Heavy Ion Collisions with STAR

    Energy Technology Data Exchange (ETDEWEB)

    STAR Coll

    2007-12-20

    Photoproduction reactions occur when the electromagnetic field of a relativistic heavy ion interacts with another heavy ion. The STAR collaboration presents a measurement of {rho}{sup 0} and direct {pi}{sup +}{pi}{sup -} photoproduction in ultra-peripheral relativistic heavy ion collisions at {radical}s{sub NN} = 200 GeV. We observe both exclusive photoproduction and photoproduction accompanied by mutual Coulomb excitation. We find a coherent cross-section of {sigma}(AuAu {yields} Au*Au* {rho}{sup 0}) = 530 {+-} 19 (stat.) {+-} 57 (syst.) mb, in accord with theoretical calculations based on a Glauber approach, but considerably below the predictions of a color dipole model. The {rho}{sup 0} transverse momentum spectrum (p{sub T}{sup 2}) is fit by a double exponential curve including both coherent and incoherent coupling to the target nucleus; we find {sigma}{sub inc}/{sigma}{sub coh} = 0.29 {+-} 0.03 (stat.) {+-} 0.08 (syst.). The ratio of direct {pi}{sup +}{pi}{sup -} production is comparable to that observed in {gamma}p collisions at HERA, and appears to be independent of photon energy. Finally, the measured {rho}{sup 0} spin helicity matrix elements agree within errors with the expected s-channel helicity conservation.

  18. CLEO and E791 data: a smoking gun for the pion distribution amplitude?

    Energy Technology Data Exchange (ETDEWEB)

    Bakulev, A.P.; Mikhailov, S.V.; Stefanis, N.G

    2004-01-01

    The CLEO experimental data on the {pi}{gamma} transition are analyzed to next-to-leading order accuracy in QCD perturbation theory using light-cone QCD sum rules. By processing these data along the lines proposed by Schmedding and Yakovlev, and recently revised by us, we obtain new constraints for the Gegenbauer coefficients a{sub 2} and a{sub 4}, as well as for the inverse moment {sub {pi}} of the pion distribution amplitude (DA). The former determine the pion DA at low momentum scale, the latter is crucial in calculating pion form factors. From the results of our analysis we conclude that the data confirm the end-point suppressed shape of the pion DA we previously obtained with QCD sum rules and nonlocal condensates, while the exclusion of both the asymptotic and the Chernyak-Zhitnitsky DAs is reinforced at the 3{sigma}- and 4{sigma}-level, respectively. The reliability of the main results of our updated CLEO data analysis is demonstrated. Our pion DA is checked against the di-jets data from the E791 experiment, providing credible evidence for our results far more broadly.

  19. Disoriented chiral condensates and anomalous production of pions

    International Nuclear Information System (INIS)

    Martinis, M.; Mikuta-Martinis, V.; Crnugelj, J.

    1999-01-01

    The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to study semiclassical production of pions in the central region. The mechanism is related to the isospin-uniform solution of the nonlinear σ-model coupled to quark degrees of freedom. The multipion exchange potential between two quarks is derived. It is shown that the soft chiral pion Bremsstrahlung also leads to anomalously large fluctuations in the ratio of neutral to charged pion.. We show that only direct production of pions in the form of an isoscalar coherent pulse without isovector pairs can lead to large neutral-charged fluctuations. (Authors)

  20. Near-threshold photoproduction of {phi} mesons from deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Qian, X., E-mail: xqian@caltech.ed [Duke University, Durham, NC 27708 (United States); Kellogg Radiation Laboratory, California Institute of Technology, CA 91125 (United States); Chen, W.; Gao, H. [Duke University, Durham, NC 27708 (United States); Hicks, K. [Ohio University, Athens, OH 45701 (United States); Kramer, K. [Duke University, Durham, NC 27708 (United States); Laget, J.M. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Mibe, T. [Ohio University, Athens, OH 45701 (United States); Qiang, Y. [Duke University, Durham, NC 27708 (United States); Stepanyan, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Tedeschi, D.J. [University of South Carolina, Columbia, SC 29208 (United States); Xu, W. [Massachusetts Institute of Technology, Cambridge, MA 02139-4307 (United States); Adhikari, K.P.; Amaryan, M. [Old Dominion University, Norfolk, VA 23529 (United States); Anghinolfi, M. [INFN, Sezione di Genova, 16146 Genova (Italy); Ball, J. [CEA, Centre de Saclay, Irfu/Service de Physique Nucleaire, 91191 Gif-sur-Yvette (France); Battaglieri, M. [INFN, Sezione di Genova, 16146 Genova (Italy); Batourine, V. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Bedlinskiy, I. [Institute of Theoretical and Experimental Physics, Moscow 117259 (Russian Federation); Bellis, M. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Biselli, A.S. [Fairfield University, Fairfield, CT 06824 (United States); Carnegie Mellon University, Pittsburgh, PA 15213 (United States)

    2011-02-07

    We report the first, kinematically-complete measurement of the differential cross section of {phi}-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, K{sup +} and K{sup -} near the theoretical production threshold of 1.57 GeV. The extracted differential cross sections (d{sigma})/(dt) for the initial photon energy range of 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Our finding is different from recent LEPS results on {phi}-meson photoproduction from deuterium in a similar incident photon energy range, but in a different momentum transfer region.

  1. Galileo-invariant theory of low energy pion-nucleus scattering

    International Nuclear Information System (INIS)

    Mach, R.

    1980-01-01

    Two classes of Galileo-invariant optical models are constructed for pion elastic scattering by nuclei. The first, the two-body model, has been obtained assuming that the pion-bound nucleon dynamics is determined by the pion-nucleon kinetic energy. In deriving the second model, the (A+1)-body dynamics has been taken into account. The technique of effective nucleon momenta maintains the nonlocal propagation of the pion-target nucleon subsystem through the nucleus in contrast with the standard static approximation

  2. A Study of Charged Current Single Charged Pion Productions on Carbon in a Few-GeV Neutrino Beam

    Energy Technology Data Exchange (ETDEWEB)

    Hiraide, Katsuki [Kyoto Univ. (Japan)

    2009-01-01

    Understanding single charged pion production via neutrino-nucleus charged current interaction in the neutrino energy region of a few GeV is essential for future neutrino oscillation experiments since this process is a dominant background for vμ → vx oscillation measurements. There are two contributions to this process: single pion production via baryonic resonance (vμN → μ-+) and coherent pion production interacting with the entire nucleus (vμA → μ-+), where N is nucleon in the nucleus and A is the nucleus. The purpose of the study presented in this thesis is a precise measurement of charged current single charged pion productions, resonant and coherent pion productions, with a good final state separation in the neutrino energy region of a few GeV. In this thesis, we focus on the study of charged current coherent pion production from muon neutrinos scattering on carbon, vμ 12C → μ-12+, in the SciBooNE experiment. This is motivated by the fact that without measuring this component first, the precise determination of resonant pion production cross section can not be achieved since the contribution of coherent pion production in the region of small muon scattering angle is not small. Furthermore, the coherent process is particularly interesting because it is deeply rooted in fundamental physics via Adler's partially conserved axial-vector current theorem. We took data from June 2007 until August 2008, in both the neutrino and antineutrino beam. In total, 2.52 x 1020 protons on target were collected. We have performed a search for charged current coherent pion production by using SciBooNE's full neutrino data set, corresponding to 0.99 x 1020 protons on target. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio

  3. Low-energy photoproduction of omega-mesons

    CERN Document Server

    Barth, J; Glander, K H; Hannappel, J; Jöpen, N; Klein, F; Lawall, R; Menze, D; Neuerburg, W; Ostrick, M; Paul, E; Schulday, I; Schwille, W J; Wiegers, B; Ernst, J; Kalinowsky, H; Klempt, E; Link, J; Pee, H V; Klein, F J; Wieland, F W; Wisskirchen, J; Wu, C

    2003-01-01

    The photoproduction of the vector meson omega has been studied between threshold and W=2.4 GeV with the SAPHIR detector at the Bonn electron stretcher ring ELSA. Besides, the total cross-sections angular distributions in the CMS and decay angular distributions in the helicity and Gottfried-Jackson systems have been measured.

  4. High-energy pion beams: Problems and prospects

    International Nuclear Information System (INIS)

    Chrien, R.E.

    1992-01-01

    The investigation of relatively unexplored research areas with high energy pion beams requires new facilities. Presently existing meson factories such as LAMPF, TRIUMF and PSI provide insufficient pion fluxes above the 3,3 resonance region for access to topics such as strangeness production with the (π, K) reaction, baryon resonances, rare meson decays, and nuclear studies with penetrating pion beams. The problems and prospects of useful beams for these studies will be reviewed, both for existing facilities such as the AGS and KEK, and for possible future facilities like KAON and PILAC

  5. Incorporating pion effects into the naive quark model

    International Nuclear Information System (INIS)

    Nogami, Y.; Ohtuska, N.

    1982-01-01

    A hybrid of the naive nonrelativistic quark model and the Chew-Low model is proposed. The pion is treated as an elementary particle which interacts with the ''bare baryon'' or ''baryon core'' via the Chew-Low interaction. The baryon core, which is the source of the pion interaction, is described by the naive nonrelativistic quark model. It turns out that the baryon-core radius has to be as large as 0.8 fm, and consequently the cutoff momentum Λ for the pion interaction is < or approx. =3m/sub π/, m/sub π/ being the pion mass. Because of this small Λ (as compared with Λapprox. nucleon mass in the old Chew-Low model) the effects of the pion cloud are strongly suppressed. The baryon masses, baryon magnetic moments, and the nucleon charge radii can be reproduced quite well. However, we found it singularly difficult to fit the axial-vector weak decay constant g/sub A/

  6. Charged-Current Neutral Pion production at SciBooNE

    International Nuclear Information System (INIS)

    Catala-Perez, J.

    2009-01-01

    SciBooNE, located in the Booster Neutrino Beam at Fermilab, collected data from June 2007 to August 2008 to accurately measure muon neutrino and anti-neutrino cross sections on carbon below 1 GeV neutrino energy. SciBooNE is studying charged current interactions. Among them, neutral pion production interactions will be the focus of this poster. The experimental signature of neutrino-induced neutral pion production is constituted by two electromagnetic cascades initiated by the conversion of the π 0 decay photons, with an additional muon in the final state for CC processes. In this poster, I will present how we reconstruct and select charged-current muon neutrino interactions producing π 0 's in SciBooNE.

  7. Inclusive production of ρ0 mesons on protons with photons, pion and kaon beams in the energy range from 65 to 175 GeV

    International Nuclear Information System (INIS)

    Hofmann, R.P.

    1991-03-01

    Cross sections of the inclusive photoproduction and hadroproduction of the ρ 0 (770) meson on a liquid hydrogen target are given as functions of p perpendicular to (varying from 0 to 2 GeV) and x F (-0.1 to 1.0) where the photon energy range is 65 to 175 GeV and the hadrons are charged π and K of the energies 80 and 140 GeV. The ρ-signal is quantified in fits to the π + π - -mass distributions accounting for a downward mass shift of the ρ 0 peak known from the diffractive ρ 0 -production. This mass shift is shown to be significantly different from zero also in the low-x F -low-p perpendicular to region in both photon and hadron data. The ratios d 2 σ/dp perpendicular to dx F (γp→ρ 0 X)/d 2 σ/dp perpendicular to dx F (π/Kp→ρ 0 X) give an x F - and π perpendicular to - dependent VMD-factor. Comparison of hadron and photon cross sections shows a difference due to the pointlike photon-hadron-coupling at large p perpendicular to . This onset is in good quantitative agreement with the predictions of the LUCIFER-Monte-Carlo. The low and medium x F -range can be described by a quark-antiquark-fusion-model. The high x F -regions show distinct decay angular distributions matching the predictions for diffractive photoproduction and the one-pion-exchange model respectively. (orig.) [de

  8. Low energy pion detection by a silicon surface barrier telescope

    International Nuclear Information System (INIS)

    Sealock, R.M.; Caplan, H.S.; Leung, M.K.

    1978-01-01

    Four telescopes of three (2-ΔE, 1-E) silicon surface barrier detectors each, mounted in the focal plane of a magnetic spectrometer, have been used to detect positive pions in the energy range from 4.7-17.9 MeV and negative pions from 14.1-17.9 MeV. Positive pions from 4.7-12.7 MeV were stopped in the third detector while positive and negative pions from 14.1-17.9 MeV were detected in transmission. For energies greater than 7.4 MeV aluminum moderators were placed in front of the first detector to degrade the pion energy. Energy spectra show well resolved pion peaks with extremely low background. Double differential cross sections for the 12 C(e,π + ) 12 B,e' reaction have been measured. (Auth.)

  9. Tests of the single-pion exchange model

    International Nuclear Information System (INIS)

    Treiman, S.B.; Yang, C.N.

    1983-01-01

    The single-pion exchange model (SPEM) of high-energy particle reactions provides an attractively simple picture of seemingly complex processes and has accordingly been much discussed in recent times. The purpose of this note is to call attention to the possibility of subjecting the model to certain tests precisely in the domain where the model stands the best chance of making sense

  10. Investigation of Compton effect on π-meson and charged pion polarizability

    International Nuclear Information System (INIS)

    Antipov, Yu.M.; Batarin, V.A.; Bezzubov, V.A.

    1986-01-01

    The results of an experiment aimed at the study of the 40 GeV/c pion radiative scattering on nuclei at small momentum transfers are presented. Compton effect on the pion was investigated and the charged pion polarizability was measured. The pion Compton-effect cross section dependence on the incident photon energy ω' 1 (rest pion frame) was measured in the 100 - 600 MeV range. The polarizability of charged pion from the analysis of Compton-effect events has been found to be β π =-α π =(-6.9 ± 1.4 stat. ± 1.2 syst. )x10 -43 cm 3 and the sun of pion electrical α π and magnetic β π polarizability has been estimated to be in agreement with theoretical predictions: α π +β π ≅ 0

  11. Status of PILAC: A pion linac facility for 1-GeV pion physics at LAMPF

    International Nuclear Information System (INIS)

    Thiessen, H.A.

    1990-01-01

    A Pion Linac (PILAC) is being designed for LAMPF. Together with its high resolution beam line and spectrometer, the system is optimized to provide 10 9 pions per second on target and 200-keV resolution for the (π + ,K + ) reaction at 920, MeV. There will also be an achromatic beam line capable of utilizing the maximum energy available, thus opening up the possibility of a broad experimental program as is being discussed at this workshop. 12 figs

  12. Chiral pion dynamics for spherical nucleon bags

    International Nuclear Information System (INIS)

    Vento, V.; Rho, M.; Nyman, E.M.; Jun, J.H.; Brown, G.E.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1980-01-01

    A chirally symmetric quark-bag model for the nucleon is obtained by introducing an explicit, classical, pion field exterior to the bag. The coupling at the bag surface is determined by the requirement of a conserved axial-vector current. The pion field satisfies equations of motion corresponding to the non-linear sigma-model. We study on this paper the simplified case where the bag and the pion field are spherically symmetric. Corrections due to gluon exchange between the quarks are ignored along with other interactions which split the N- and Δ-masses. The equations of motion for the pion field are solved and we find a substantial pion pressure at the bag surface, along with an attractive contribution to the nucleon self-energy. The total energy of the system, bag plus meson cloud, turns out to be approximately Msub(n)c 2 for a wide range of bag radii, from 1.5 fm down to about 0.5 fm. Introduction of a form factor for the pion would extend the range of possible radii to even smaller values. We propose that the bag with the smallest allowed radius be identified with the 'little bag' discussed before. One surprising result of the paper is that as long as one restricts to spherically symmetric bags, restoring chiral symmetry to the bag model makes the axial-vector current coupling constant gsub(A) to be always too large compared with the experimental value for any bag radius, suggesting a deviation from spherical symmetry for the intrinsic bag wave functions of the 'ground-state' hadrons. (orig.)

  13. Strangeness production with protons and pions

    International Nuclear Information System (INIS)

    Dover, C.B.

    1993-01-01

    We discuss the spectrum of physics questions related to strangeness which could be addressed with intense beams of protons and pions in the few GeV region. We focus on various aspects of strangeness production, including hyperon production in pp collisions, studies of hyperon-nucleon scattering, production of hypernuclei in proton and pion-nucleus collisions, and spin phenomena in hypernuclei

  14. Coherent and chaotic generation of pions from relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Nakamura, Hiroki; Seki, Ryoichi

    2002-01-01

    Based on the recent NA44 and WA98 two- and three-pion interferometry data together with the WA98 pion multiplicity information, we observe that the pions may be mostly emitted from chaotic sources in the peripheral events and coherent pions are mostly generated in the central events. A more refined analysis would be needed, however, to make our observation conclusive by quantifying various effects such as resonance formation of the emerging pions and also experimental uncertainties

  15. Quantum effects and colour transparency in charmonium photoproduction on nuclei

    International Nuclear Information System (INIS)

    Kopeliovich, B.Z.; Zakharov, B.G.

    1991-01-01

    A rigorous quantum-mechanical treatment of colour transparency effects in diffractive photoproduction of c-barc-pairs on nuclei was developed. The evolution of the c-barc wave function during propagating through a nucleus is rather a considerable distortion of its form, than a trivial attenuation. One of the manifestations of the quantum effects is a nuclear antishadowing of Ψ' yield, i.e. transparency above one. On the contrary, a considerable nuclear shadowing is predicted for the photoproduction of J/Ψ, which has a much smaller absorption cross section than Ψ'. 26 refs.; 5 figs.; 1 tab

  16. Tensor polarization in pion-deuteron elastic scattering

    International Nuclear Information System (INIS)

    Holt, R.J.; Freeman, W.S.; Geesaman, D.F.

    1985-01-01

    During this year the analysis of measurements of t 20 in π-d elastic scattering was completed and a final summary manuscript was prepared for publication. The results consists of angular distributions of the deuteron tensor polarization in π-d elastic scattering at pion energies of 140, 180, 220 and 256 MeV. Theoretical calculations in which the effects of pion absorption on the elastic channel are small reproduce the data. No rapid angular or energy dependence was found near a pion energy of 134 MeV, where another experiment at SIN has suggested the existence of dibaryon resonances

  17. Single pion production in neutrino-nucleon interactions

    Science.gov (United States)

    Kabirnezhad, M.

    2018-01-01

    This work represents an extension of the single pion production model proposed by Rein [Z. Phys. C 35, 43 (1987)., 10.1007/BF01561054]. The model consists of resonant pion production and nonresonant background contributions coming from three Born diagrams in the helicity basis. The new work includes lepton mass effects, and nonresonance interaction is described by five diagrams based on a nonlinear σ model. This work provides a full kinematic description of single pion production in the neutrino-nucleon interactions, including resonant and nonresonant interactions in the helicity basis, in order to study the interference effect.

  18. Induction of UV photoproducts and DNA damage by solar simulator UV irradiation

    International Nuclear Information System (INIS)

    Wolfreys, A.; Henderson, L.; Clingen, P.

    1997-01-01

    The recent increased incidence of skin cancer and the depletion of the ozone layer has increased interest in the ultraviolet (UV) component of natural sunlight and its role in the induction of skin cancer. Previous research on UV radiation has concentrated on UVC (254nm) but, as only UVB and UVA are present in natural sunlight, its relevance is unknown. We have investigated the induction of two forms of direct DNA damage - the pyrimidine dimer and the (6-4) photoproduct - in human DNA repair deficient XP-G (Xeroderma pigmentosum group G) lymphoblastoid cells following exposure to simulated sunlight. As exposure to natural sunlight is highly variable, a solar simulator lamp was used which is known to mimic natural sunlight at midday in Central Europe. Cells were irradiated on ice to minimise DNA repair and the relative induction of pyrimidine dimers and (6-4) photoproducts was measured using specific monoclonal antibodies and a computer assisted image analysis system. A time dependent increase in both cyclobutane dimer and (6-4) photoproduct antibody binding sites was seen. The increases in pyrimidine dimer and (6-4) photoproduct antibody binding sites differed to that reported with natural sunlight in the UK but was similar to that seen with a similar solar simulator lamp

  19. High-energy photoproduction and electroproduction of π+ on nuclei

    International Nuclear Information System (INIS)

    Kuz'menko, V.S.; Mitrofanova, A.V.; Noga, V.I.; Ranyuk, Y.N.; Sorokin, P.V.; Telegin, Y.N.; Blomqvist, I.; Jonsson, G.G.; Freed, N.

    1977-01-01

    Cross sections for photoproduction and electroproduction of π + on 27 Al and 51 V leading to bound states in the daughter nuclei have been measured at Kharkov in the energy range 600--1200 MeV by use of the activation method. Careful comparison is made to other recent results obtained at intermediate and high energies. Agreement is found between the present data and results of earlier work carried out at Lund and DESY. Discrepancies between photoproduction data taken at different laboratories are attributed to differences between methods of background subtraction. Relative bremsstrahlung-induced to electron-induced yield ratios are compared with predictions based on the Dalitz-Yennie formalism for virtual-photon spectra

  20. Roy-Steiner-equation analysis of pion-nucleon scattering

    Science.gov (United States)

    Meißner, U.-G.; Ruiz de Elvira, J.; Hoferichter, M.; Kubis, B.

    2017-03-01

    Low-energy pion-nucleon scattering is relevant for many areas in nuclear and hadronic physics, ranging from the scalar couplings of the nucleon to the long-range part of two-pion-exchange potentials and three-nucleon forces in Chiral Effective Field Theory. In this talk, we show how the fruitful combination of dispersion-theoretical methods, in particular in the form of Roy-Steiner equations, with modern high-precision data on hadronic atoms allows one to determine the pion-nucleon scattering amplitudes at low energies with unprecedented accuracy. Special attention will be paid to the extraction of the pion-nucleon σ-term, and we discuss in detail the current tension with recent lattice results, as well as the determination of the low-energy constants of chiral perturbation theory.

  1. Mechanisms for pion production in heavy ion collisions

    International Nuclear Information System (INIS)

    Pfeiffer, M.

    1991-01-01

    In the following contribution some aspects concerning pion production in heavy ion collisions will be discussed. After a general introduction the properties of pions and the Δ-resonance will be briefly mentioned. In the following section some points refering to the pion production in a relativistic heavy ion collision will be discussed. In addition, the basic ideas of the applied models will be shown. In the last part results from existing experiments and possible interpretations will be presented. (orig.)

  2. A possible form of the pion's structure function

    International Nuclear Information System (INIS)

    Long Ming; Huang Tao

    1986-01-01

    The pion's structure function behaviour is discussed by using the Fock state expansion of the hadronic wave function in QCD in this paper. As an example, we employ a model wave function of the Fock state in the light-cone and assume a Regge behaviour of a weight function for higher Fock states, and we get a possible form of the pion's structure function. This form is consistent with experimental data of the pion's structure function

  3. Pion condensation and instabilities: current theory and experiment

    International Nuclear Information System (INIS)

    Gyulassy, M.

    1980-05-01

    Current calculations of pion condensation phenomena in symmetric nuclear matter are reviewed. The RPA and MFA methods are compared. Latest results [LBL-10572] with a relativistic MFA theory constrained by bulk nuclear properties are presented. The differences between equilibrium (condensation) and nonequilibrium (dynamic) instabilities are discussed. Finally, two-proton correlation experiments aimed at looking for critical scattering phenomena and two-pion correlation experiments aimed at looking for pion field coherence are analyzed. 10 figures, 2 tables

  4. Radiative pion-proton scattering

    International Nuclear Information System (INIS)

    Ho-Kim, Q.; Lavine, J.P.

    1977-01-01

    The results are presented of a non-relativistic calculation of the π +- proton bremsstrahlung cross section at the pion kinetic energy of 298 MeV for backward photon angles. The pion-nucleon interaction is given by models that are based on the p-wave Chew-Low theory. An interaction current is included in an attempt to make the overall bremsstrahlung amplitude gauge-invariant. The predicted cross sections show little of the expected resonance, and are in fair agreement with the data. The authors have also calculated the cross sections at other kinetic energies, and have studied effects of the off-mass-shell electromagnetic vertex. (Auth.)

  5. Pion scattering and nuclear dynamics

    International Nuclear Information System (INIS)

    Johnson, M.B.

    1988-01-01

    A phenomenological optical-model analysis of pion elastic scattering and single- and double-charge-exchange scattering to isobaric-analog states is reviewed. Interpretation of the optical-model parameters is briefly discussed, and several applications and extensions are considered. The applications include the study of various nuclear properties, including neutron deformation and surface-fluctuation contributions to the density. One promising extension for the near future would be to develop a microscopic approach based on powerful momentum-space methods brought to existence over the last decade. In this, the lowest-order optical potential as well as specific higher-order pieces would be worked out in terms of microscopic pion-nucleon and delta-nucleon interactions that can be determined within modern meson-theoretical frameworks. A second extension, of a more phenomenological nature, would use coupled-channel methods and shell-model wave functions to study dynamical nuclear correlations in pion double charge exchange. 35 refs., 11 figs., 1 tab

  6. Exclusive photoproduction of Upsilon in pPb collisions at LHC energies

    International Nuclear Information System (INIS)

    Dutta, Dipanwita; Chudasama, Ruchi; Mohanty, A.K.

    2014-01-01

    Recent results of exclusive photoproduction of heavy vector mesons at LHC energies by ALICE and LHCb in pp, pPb and PbPb Ultraperipheral collisions (UPC) confirmed the expectations that UPCs are a very promising probe to study the gluon distributions in nucleons and in nuclei at small x. In this work, we have estimated the photoproduction of γ in pPb collisions at √s NN = 5.02 TeV in the framework of perturbative two-gluon exchange formalism employing various parametrization of gluon distributions functions

  7. First time measurements of polarization observables for the charged cascade hyperon in photoproduction

    Energy Technology Data Exchange (ETDEWEB)

    Bono, Jason [Florida Intl Univ., Miami, FL (United States)

    2014-08-31

    The parity violating weak decay of hyperons offers a valuable means of measuring their polarization, providing insight into the production of strange quarks and the matter they compose. Jefferson Lab's CLAS collaboration has utilized this property of hyperons, publishing the most precise polarization measurements for the Lambda and Sigma in both photoproduction and electroproduction to date. In contrast, cascades, which contain two strange quarks, can only be produced through indirect processes and as a result, exhibit low cross sections thus remaining experimentally elusive.

    At present, there are two aspects in cascade physics where progress has been minimal: characterizing their production mechanism, which lacks theoretical and experimental developments, and observation of the numerous excited cascade resonances that are required to exist by flavor SU(3)F symmetry. However, CLAS data were collected in 2008 with a luminosity of 68 pb^-1 using a circularly polarized photon beam with energies up to 5.45 GeV, incident on a liquid hydrogen target. This dataset is, at present, the world's largest for meson photoproduction in its energy range and provides a unique opportunity to study cascade physics with polarization measurements.

    The current analysis explores hyperon production through the yp -> K^+ K^+ Xi^- reaction by providing the first ever determination of spin observables P, Cx and Cz for the cascade. Three of our primary goals are to test the only cascade photoproduction model in existence, examine the underlying processes that give rise to hyperon polarization, and to stimulate future theoretical developments while providing constraints for their parameters. Our research is part of a broader program to understand the production of strange quarks and hadrons with strangeness. The remainder of this document discusses the motivation behind such research, the method of data collection, details of their analysis, and the significance of

  8. Probing nuclear correlations with pion-nucleus double charge exchange

    International Nuclear Information System (INIS)

    Ginocchio, J.N.

    1988-01-01

    In this paper we have calculated the lowest order pion double charge reaction mechanism using shell model wavefunctions of medium weight nuclei. We have the sequential reaction mechanism in which the pion undergoes two single-charge exchange scatterings on the valence neutrons. The distortion of the incoming, intermediate, and outgoing pion are included. The closure approximation is made for the intermediate states with an average excitation energy used in the pion propagator. The double-charge exchange is assumed to take place on the valence nucleons which are assumed to be in one spherical shell model orbital. 34 refs., 5 figs., 3 tabs

  9. Pion double charge exchange and nuclear structure

    International Nuclear Information System (INIS)

    Ginocchio, J.N.

    1987-01-01

    Pion double charge exchange to both the double-analog state and the ground state is studied for medium weight nuclei. The relative cross section of these two transitions and the importance of nuclear structure as a function of pion kinetic energy is examined. 16 figs., 5 tabs

  10. The bag model and the Nambu-Goldstone pion

    International Nuclear Information System (INIS)

    Lee, H.C.; Ho-Kim, Q.

    1983-01-01

    The MIT bag model for the pion is improved and extended in such a way that the pion does not have spurious center-of-mass motions; perturbative gluon contributions to the pion mass msub(π) and decay constant fsub(π) are both calculated to lowest order in αsub(s). The pion is a Nambu-Goldstone boson in the sense that the vacuum in the bag refers to massive constituent quarks, but not so massless current quarks. The transformation of Nambu and Jona-Lasinio between massive and massless quarks is utilized in the computation of fsub(π), the result of which strongly suggests that quarks in the pion are correlated, characterized by a correlation momentum which is proportional 300 MeV/c. The vacuum expectation value for the massless quark condensate is calculated to be proportional0.04 GeV 3 , corresponding to a current quark mass of proportional4 MeV. The requirement that msub(π) approaches zero in a manner consistent with PCAC constrains the bag energy to be msub(π)/4. (orig.)

  11. Distortion of two-pion interferometry by multipion correlations

    International Nuclear Information System (INIS)

    Zhang, W.N.; Liu, Y.M.; Wang, S.; Liu, Q.J.; Jiang, J.; Keane, D.; Shao, Y.; Chu, S.Y.; Fung, S.Y.

    1993-01-01

    Multipion correlations arising from the symmetrization of the n-pion wave function affect the extracted information from two-pion correlation measurements. The influence of multipion correlations on a sample of like-pion pairs can be expressed as a multipion correlation factor, the distribution of which offers good sensitivity to the multipion correlation effect. Analyses of the multipion correlation factor for two Bevalac streamer chamber data samples of 2.1A GeV Ne+Pb and 1.8A GeV Ar+Pb collisions show that the multipion correlation effect in the former sample is greater than in the latter. This result mainly arises from the fact that the pion source for Ne projectiles is smaller than for Ar projectiles. The residual correlations in the reference sample are related to the multipion correlation factor in multipion events, which can be expressed as a residual correlation factor. The influence of multipion correlations on two-pion interferometry analyses arises from the ratio of the residual correlation factor to the multipion correlation factor

  12. Exclusive electroproduction of two pions at HERA

    International Nuclear Information System (INIS)

    Abramowicz, H.; Ashery, D.; Gueta, O.; Gurvich, E.; Ingbir, R.; Kananov, S.; Levy, A.; Stern, A.

    2012-01-01

    The exclusive electroproduction of two pions in the mass range 0.4 ππ -1 . The analysis was carried out in the kinematic range of 2 2 2 , 32 2 , where Q 2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, vertical stroke F(M ππ ) vertical stroke, assuming that the studied mass range includes the contributions of the ρ, ρ' and ρ'' vector-meson states. The masses and widths of the resonances were obtained and the Q 2 dependence of the cross-section ratios σ(ρ'→ππ)/ σ(ρ) and σ(ρ''→ππ)/ σ(ρ) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e + e - →π + π - . (orig.)

  13. Antiquark distributions in pion and nucleon

    International Nuclear Information System (INIS)

    Arakelian, G.G.; Boreskov, K.G.; Kaidalov, A.B.

    1980-01-01

    Relation between the antiquark distributions in pion and nucleon, based on the π-exchange hypothesis, is derived. The antiquark distributions in proton are calculated with the data on the valence antiquark distribution in pion as input. Results of the calculation agree with the experimental data. The role of the peripheral mechanism in formulation of the initial conditions for the chromodynamical evolution equations is discussed

  14. Galileo-invariant theory of low energy pion-nucleus scattering. II

    International Nuclear Information System (INIS)

    Mach, R.

    1983-01-01

    Two classes of Galileo-invariant optical models are constructed for pion elastic scattering by nuclei. The former, the two-body model, was obtained assuming that the pion-bound nucleon dynamics is determined by the pion-nucleon kinetic energy. In deriving the latter model, the (A+1)-body dynamics was taken into account. The technique of effective nucleon momenta maintains the nonlocal propagation of the pion-target nucleon subsystem through the nucleus in contrast with the standard static approximation. (author)

  15. Prompt Photons in Photoproduction at HERA

    CERN Document Server

    Aaron, F.D.; Alexa, C.; Andreev, V.; Antunovic, B.; Backovic, S.; Baghdasaryan, A.; Barrelet, E.; Bartel, W.; Begzsuren, K.; Belousov, A.; Bizot, J.C.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cantun Avila, K.B.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J.G.; Coughlan, J.A.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Daum, K.; Deak, M.; de Boer, Y.; Delcourt, B.; Del Degan, M.; Delvax, J.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dossanov, A.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eliseev, A.; Elsen, E.; Falkiewicz, A.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Fischer, D.J.; Fleischer, M.; Fomenko, A.; Gabathuler, E.; Gayler, J.; Ghazaryan, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Gogitidze, N.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Grell, B.R.; Grindhammer, G.; Habib, S.; Haidt, D.; Helebrant, C.; Henderson, R.C.W.; Hennekemper, E.; Henschel, H.; Herbst, M.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hreus, T.; Jacquet, M.; Janssen, X.; Jonsson, L.; Jung, A.W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I.R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Kluge, T.; Knutsson, A.; Kogler, R.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kutak, K.; Landon, M.P.J.; Lange, W.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Li, G.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, Ll.; Martyn, H.U.; Maxfield, S.J.; Mehta, A.; Meyer, A.B.; Meyer, H.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, M.U.; Mudrinic, M.; Muller, K.; Murin, P.; Naumann, Th.; Newman, P.R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nowak, K.; Nozicka, M.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, Th.; Pascaud, C.; Patel, G.D.; Pejchal, O.; Perez, E.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Placakyte, R.; Pokorny, B.; Polifka, R.; Povh, B.; Radescu, V.; Rahmat, A.J.; Raicevic, N.; Raspiareza, A.; Ravdandorj, T.; Reimer, P.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rotaru, M.; Ruiz Tabasco, J.E.; Rurikova, Z.; Rusakov, S.; Salek, D.; Sankey, D.P.C.; Sauter, M.; Sauvan, E.; Schmitt, S.; Schoeffel, L.; Schoning, A.; Schultz-Coulon, H.C.; Sefkow, F.; Shaw-West, R.N.; Shtarkov, L.N.; Shushkevich, S.; Sloan, T.; Smiljanic, I.; Soloviev, Y.; Sopicki, P.; South, D.; Spaskov, V.; Specka, A.; Staykova, Z.; Steder, M.; Stella, B.; Stoicea, G.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P.D.; Toll, T.; Tomasz, F.; Tran, T.H.; Traynor, D.; Trinh, T.N.; Truol, P.; Tsakov, I.; Tseepeldorj, B.; Turnau, J.; Urban, K.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; von den Driesch, M.; Wegener, D.; Wissing, Ch.; Wunsch, E.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.; Zus, R.

    2010-01-01

    The production of prompt photons is measured in the photoproduction regime of electron-proton scattering at HERA. The analysis is based on a data sample corresponding to a total integrated luminosity of 340 pb^-1 collected by the H1 experiment. Cross sections are measured for photons with transverse momentum and pseudorapidity in the range 6 < Et < 15 GeV and -1.0 < eta < 2.4, respectively. Cross sections for events with an additional jet are measured as a function of the transverse energy and pseudorapidity of the jet, and as a function of the fractional momenta x_gamma and x_p carried by the partons entering the hard scattering process. The correlation between the photon and the jet is also studied. The results are compared with QCD predictions based on the collinear and on the k_T factorisation approaches.

  16. Inclusive photoproduction of delta(980) and B(1235) at high xsub(F)

    International Nuclear Information System (INIS)

    Lassalle, J.C.; Patrick, G.N.; Storr, K.M.; Atkinson, M.; Axon, T.J.; Barberis, D.; Brodbeck, T.J.; Brookes, G.R.; Bunn, J.J.; Bussey, P.J.; Clegg, A.B.; Dainton, J.B.; Davenport, M.; Dickinson, B.; Diekmann, B.; Donnachie, A.; Ellison, R.J.; Flower, P.; Flynn, P.J.; Galbraith, W.; Heinloth, K.; Henderson, R.C.W.; Hughes-Jones, R.E.; Hutton, J.S.; Ibbotson, M.; Jakob, H.P.; Jung, M.; Kumar, B.R.; Laberrigue, J.; Lafferty, G.D.; Lane, J.B.; Levy, J.M.; Liebenau, V.; McClatchey, R.; Mercer, D.; Morris, J.A.G.; Morris, J.V.; Newton, D.; Paterson, C.; Paul, E.; Raine, C.; Reidenbach, M.; Rotscheidt, H.; Schloesser, A.; Sharp, P.H.; Skillicorn, I.O.; Smith, K.M.; Thompson, R.J.; Vaissiere, C. de la; Waite, A.P.; Worsell, M.F.; Yiou, T.P.

    1984-01-01

    Inclusive photoproduction of deltasup(+-)(980) and Bsup(+-0) (1235) at high xsub(F) is reported. Production of B 0 is largely due to double diffractive dissociation. The charged states are produced as leading particles, their production being described by the quark recombination picture. The relatively strong production of the delta(980) by this process is evidence that it is a anti qanti q state rather than a qqanti qanti q state. (orig.)

  17. Virtual photons in the pion form factors and the energy-momentum tensor

    Energy Technology Data Exchange (ETDEWEB)

    Kubis, Bastian E-mail: b.kubis@fz-juelich.de; Meissner, Ulf-G. E-mail: ulf-g.meissner@fz-juelich.de

    2000-05-22

    We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next-to-leading order in two-flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy-momentum tensor. We find that the intrinsic electromagnetic corrections are very small for the vector as well as the charged pion scalar form factor. The scalar radius of the neutral pion is reduced by two percent. We perform infrared regularization by considering electron-positron annihilation into pions and the decay of a light Higgs boson into a pion pair. We discuss the detector resolution dependent contributions to the various form factors and pion radii.

  18. Virtual photons in the pion form factors and the energy-momentum tensor

    International Nuclear Information System (INIS)

    Kubis, Bastian; Meissner, Ulf-G.

    2000-01-01

    We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next-to-leading order in two-flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy-momentum tensor. We find that the intrinsic electromagnetic corrections are very small for the vector as well as the charged pion scalar form factor. The scalar radius of the neutral pion is reduced by two percent. We perform infrared regularization by considering electron-positron annihilation into pions and the decay of a light Higgs boson into a pion pair. We discuss the detector resolution dependent contributions to the various form factors and pion radii

  19. Inclusive particle production at forward angles from collisions of light relativistic nuclei: Negative pions

    International Nuclear Information System (INIS)

    Moeller, E.; Anderson, L.; Brueckner, W.; Nagamiya, S.; Nissen-Meyer, S.; Schroeder, L.; Shapiro, G.; Steiner, H.

    1983-01-01

    We have measured single particle inclusive spectra of negative pions produced at angles from 0 0 to 12 0 (lab) in collisions of 1.05 and 2.1 GeV/nucleon protons, deuterons, alpha particles, and carbon nuclei with targets of C, Cu, Pb, and H (from a CH 2 -C subtraction). Most of the pions are produced in the kinematical domains allowed in free nucleon-nucleon collisions, but for alpha and carbon projectiles we have also observed pions whose energies range up to nearly twice the kinetic energy of a nucleon in the projectile. Our results suggest that processes involving more than two colliding nucleons and/or high internal momentum components are involved in the production of these high energy pions. Comparison is made with several hypotheses of scaling including specific dynamical models, and some disagreement is observed. We present fits to the kinetic energy dependence of the data, and the target and projectile mass dependence. We also show transverse momentum distributions

  20. Various models for pion probability distributions from heavy-ion collisions

    International Nuclear Information System (INIS)

    Mekjian, A.Z.; Mekjian, A.Z.; Schlei, B.R.; Strottman, D.; Schlei, B.R.

    1998-01-01

    Various models for pion multiplicity distributions produced in relativistic heavy ion collisions are discussed. The models include a relativistic hydrodynamic model, a thermodynamic description, an emitting source pion laser model, and a description which generates a negative binomial description. The approach developed can be used to discuss other cases which will be mentioned. The pion probability distributions for these various cases are compared. Comparison of the pion laser model and Bose-Einstein condensation in a laser trap and with the thermal model are made. The thermal model and hydrodynamic model are also used to illustrate why the number of pions never diverges and why the Bose-Einstein correction effects are relatively small. The pion emission strength η of a Poisson emitter and a critical density η c are connected in a thermal model by η/n c =e -m/T <1, and this fact reduces any Bose-Einstein correction effects in the number and number fluctuation of pions. Fluctuations can be much larger than Poisson in the pion laser model and for a negative binomial description. The clan representation of the negative binomial distribution due to Van Hove and Giovannini is discussed using the present description. Applications to CERN/NA44 and CERN/NA49 data are discussed in terms of the relativistic hydrodynamic model. copyright 1998 The American Physical Society

  1. Carbon Monoxide Photoproduction from Particles and Solutes in the Delaware Estuary under Contrasting Hydrological Conditions.

    Science.gov (United States)

    Song, Guisheng; Richardson, John D; Werner, James P; Xie, Huixiang; Kieber, David J

    2015-12-15

    Full-spectrum, ultraviolet (UV), and visible broadband apparent quantum yields (AQYs) for carbon monoxide (CO) photoproduction from chromophoric dissolved organic matter (CDOM) and particulate organic matter (POM) were determined in the Delaware Estuary in two hydrologically contrasting seasons in 2012: an unusually low flow in August and a storm-driven high flow in November. Average AQYs for CDOM and POM in November were 10 and 16 times the corresponding AQYs in August. Maximum AQYs in November occurred in a midestuary particle absorption maximum zone. Although POM AQYs were generally smaller than CDOM AQYs, the ratio of the former to the latter increased substantially from the UV to the visible. In both seasons, UV solar radiation was the primary driver for CO photoproduction from CDOM whereas visible light was the principal contributor to POM-based CO photoproduction. CDOM dominated CO photoproduction in the uppermost water layer while POM prevailed at deeper depths. On a depth-integrated basis, the Delaware Estuary shifted from a CDOM-dominated system in August to a POM-dominated system in November with respect to CO photoproduction. This study reveals that flood events may enhance photochemical cycling of terrigenous organic matter and switch the primary photochemical driver from CDOM to POM.

  2. Exclusive photoproduction of quarkonium at the LHC energies within the color dipole approach

    Energy Technology Data Exchange (ETDEWEB)

    Ducati, M. B. Gay; Griep, M. T.; Machado, M. V. T. [High Energy Physics Phenomenology Group, GFPAE IF-UFRGS, Caixa Postal 15051, CEP 91501-970, Porto Alegre, RS (Brazil)

    2015-04-10

    The exclusive photoproduction of ψ(2S) meson was investigated and the coherent and the incoherent contributions were evaluated. The light-cone dipole formalism was considered in this analysis and predictions are done for PbPb collisions at the CERN-LHC energy of 2.76 TeV. A comparison is done to the recent ALICE Collaboration data for the ψ(1S) state photoproduction with good agreement.

  3. Pion form factor

    Energy Technology Data Exchange (ETDEWEB)

    Ryong Ji, C.; Pang, A.; Szczepaniak, A. [North Carolina State Univ., Raleigh, NC (United States)

    1994-04-01

    It is pointed out that the correct criterion to define the legal PQCD contribution to the exclusive processes in the lightcone perturbative expansion should be based on the large off-shellness of the lightcone energy in the intermediate states. In the lightcone perturbative QCD calculation of the pion form factor, the authors find that the legal PQCD contribution defined by the lightcone energy cut saturates in the smaller Q{sup 2} region compared to that defined by the gluon four-momentum square cut. This is due to the contribution by the highly off-energy-shell gluons in the end point regions of the phase space, indicating that the gluon four-momentum-square cut may have cut too much to define the legal PQCD.

  4. On the use of distributions of stopping pions as an indicator of the spatial distribution of the high-LET dose in negative pion radiotherapy

    International Nuclear Information System (INIS)

    Brenner, D.J.

    1991-01-01

    A semi-empirical across the treatment volume of a therapeutic negative pion beam. Such beams deliver dose partially at high LET (through alphas and heavier particles produced both directly in pion stars and via intermediate star-produced neutrons), and partially at low LET (through scattering of pions, electrons and muons, as well as protons produced directly from pion stars and via intermediate neutrons). The problem is how to understand the spatial distribution of the high-LET dose, which is responsible for the potentially improved biological response in the treatment volume

  5. Data on the electromagnetic pion form factor and p-wave

    International Nuclear Information System (INIS)

    Dubnicka, S.; Meshcheryakov, V.A.; Milko, J.

    1980-01-01

    The pion form factor absolute value data (free of the omega meson contribution) are unified with the P-wave isovector ππ phase shift. The resultant real and imaginary parts of the pion form factor are described by means of the Pade approximation. All the data, which involve the pion form factor experimental points from the range of momenta - 0.8432 GeV 2 2 , the pion charge radius, and the P-wave isovector ππ phase shift in the elastic region (including also the generally accepted value of the scattering length) are mutually consistent. The data themselves through the Pade approximation reveal that the aforementioned consistency can be achieved only if the pion form factor left-hand cut from the second Riemann sheet is taken into account. Almost in all of the considered Pade approximations one stable pion form factor zero is found in the space-like region, which might indicate the existence of a diffraction minimum in the differential cross section for elastic e - π scattering as a consequence of the constituent structure of the pion like in the case of the electron elastic scattering on nuclei

  6. Measurement of antideuteron photoproduction and a search for heavy stable charged particles at HERA

    CERN Document Server

    Aktas, A; Anthonis, T; Asmone, A; Babaev, A; Backovic, S; Bähr, J; Baranov, P; Barrelet, E; Bartel, Wulfrin; Baumgartner, S; Becker, J; Beckingham, M; Behnke, O; Behrendt, O; Belousov, A; Berger, Christoph; Berndt, T; Bizot, J C; Boenig, M O; Böhme, J; Boudry, V; Bracinik, J; Brisson, V; Broker, H B; Brown, D P; Bruncko, Dusan; Bunyatyan, A; Buschhorn, G; Büsser, F W; Bystritskaya, L; Campbell, A J; Caron, S; Cassol-Brunner, F; Cerny, K; Chekelian, V; Collard, Caroline; Contreras, J G; Coppens, Y R; Coughlan, J A; Cox, B E; Cozzika, G; Cvach, J; Dainton, J B; Dau, W D; Daum, K; de Roeck, A; De Wolf, E A; Delcourt, B; Demirchyan, R; Desch, Klaus; Diaconu, C; Dingfelder, J; Dodonov, V; Dubak, A; Duprel, C; Eckerlin, G; Efremenko, V; Egli, S; Eichler, R; Eisele, F; Ellerbrock, M; Elsen, E; Erdmann, M; Erdmann, W; Faulkner, P J W; Favart, L; Fedotov, A; Felst, R; Ferencei, J; Fleischer, M; Fleischmann, P; Fleming, Y H; Flucke, G; Flügge, G; Fomenko, A; Foresti, I; Formánek, J; Franke, G; Frising, G; Gabathuler, E; Gabathuler, K; Garutti, E; Garvey, J; Gayler, J; Gerhards, R; Gerlich, C; Ghazaryan, S; Görlich, L; Gogitidze, N; Gorbounov, S; Grab, C; Grassler, J; Greenshaw, T; Gregori, M; Grindhammer, G; Gwilliam, C; Haidt, D; Hajduk, L; Haller, J; Hansson, M; Heinzelmann, G; Henderson, R C W; Henschel, H; Henshaw, O; Heremans, R; Herrera-Corral, G; Herynek, I; Heuer, R D; Hildebrandt, M; Hiller, K H; Hoffmann, D; Horisberger, R P; Hoting, P; Hovhannisyan, A; Ibbotson, M; Ismail, M; Jacquet, M; Janauschek, L; Janssen, X; Jemanov, V; Johnson, D P; Jönsson, L B; Jung, H; Kant, D; Kapichine, M; Karlsson, M; Katzy, J; Keller, N; Kennedy, J; Kenyon, I R; Kiesling, C; Klein, M; Kleinwort, C; Klimkovich, T; Kluge, T; Knies, G; Knutsson, A; Koblitz, B; Korbel, V; Kostka, P; Koutouev, R; Kropivnitskaya, A; Kroseberg, J; Kuckens, J; Kuhr, T; Landon, M P J; Lange, W; Lastoviicka, T; Laycock, P; Lebedev, A; Leissner, B; Lemrani, R; Lendermann, V; Levonian, S; Lindfeld, L; Lipka, K; List, B; Lobodzinska, E; Loktionova, N; López-Fernandez, R; Lubimov, V; Lüders, H; Lüke, D; Lux, T; Lytkin, L; Makankine, A; Malden, N; Malinovski, E; Mangano, S; Marage, P; Marks, J; Marshall, R; Martisikova, M; Martyn, H U; Maxfield, S J; Meer, D; Mehta, A; Meier, K; Meyer, A B; Meyer, H; Meyer, J; Michine, S; Mikocki, S; Milcewicz, I; Milstead, D; Mohamed, A; Moreau, F; Morozov, A; Morozov, I; Morris, J V; Mozer, M U; Müller, K; Murín, P; Nagovizin, V; Naroska, Beate; Naumann, J; Naumann, Th; Newman, P R; Niebuhr, C; Nikiforov, A; Nikitin, D; Nowak, G; Nozicka, M; Oganezov, R; Olivier, B; Olsson, J E; Ossoskov, G; Ozerov, D; Pascaud, C; Patel, G D; Peez, M; Pérez, E; Perieanu, A; Petrukhin, A; Pitzl, D; Placakyte, R; Portheault, B; Pöschl, R; Povh, B; Raicevic, N; Ratiani, Z; Reimer, P; Reisert, B; Rimmer, A; Risler, C; Rizvi, E; Robmann, P; Roland, B; Roosen, R; Rostovtsev, A; Rurikova, Z; Rusakov, S; Rybicki, K; Sankey, D P C; Sauvan, E; Schatzel, S; Scheins, J; Schilling, F P; Schleper, P; Schmidt, S; Schmitt, S; Schneider, M; Schoeffel, L; Schöning, A; Schröder, V; Schultz Coulon, H C; Schwanenberger, C; Sedlak, K; Sefkow, F; Shevyakov, I; Shtarkov, L N; Sirois, Y; Sloan, T; Smirnov, P; Soloviev, Yu V; South, D; Spaskov, V; Specka, A; Spitzer, H; Stamen, R; Stella, B; Stiewe, J; Strauch, I; Straumann, U; Tchoulakov, V; Thompson, G; Thompson, P D; Tomasz, F; Traynor, D; Trevino, A V; Truöl, P; Tsipolitis, G; Tsuri, I; Turnau, J; Tzamariudaki, E; Uraev, A; Urban, M; Usik, A; Utkin, D; Valkár, S; Valkárová, A; Vallée, C; Van Mechelen, P; Van Remortel, N; Vazdik, Ya A; Veelken, C; Vest, A; Vinokurova, S; Volchinski, V; Wacker, K; Wagner, J; Weber, G; Weber, R; Wegener, D; Werner, C; Werner, N; Wessels, M; Wessling, B; Winter, G G; Wissing, C; Woerling, E E; Wolf, R; Wünsch, E; Xella, S M; Yan, W; Yeganov, V; Zácek, J; Zaleisak, J; Zhang, Z; Zhokin, A; Zohrabyan, H; Zomer, F; 10.1140/epjc/s2004-01978-x

    2004-01-01

    The cross section for antideuteron photoproduction is measured at HERA at a mean centre-of-mass energy of W/sub gamma p/=200 GeV in the range 0.2

    photoproduction to those in central proton-proton collisions at the CERN ISR but much lower than those in central Au-Au collisions at RHIC. The coalescence parameter B/sub 2/, which characterizes the likelihood of antideuteron production, is measured in photoproduction to be 0.010+or-0.002+or-0.001, which is much higher than in Au-Au collisions at a similar nucleon-nucleon centre-of-mass energy. No significant production of particles heavier than deuterons is observed and upper limits are set on the photoproduction cross sections for such particles.

  7. Beauty in photoproduction at HERA II with the ZEUS detector

    International Nuclear Information System (INIS)

    Boutle, Sarah

    2010-02-01

    The production of beauty quarks in ep collisions should be accurately calculable in perturbative Quantum Chromodynamics (QCD) since the large mass of the b quark provides a hard scale. Therefore it is interesting to compare such predictions to results using photoproduction events where a low-virtuality photon, emitted by the incoming lepton, collides with a parton from the incoming proton. A measurement of beauty in photoproduction has been made at HERA with the ZEUS detector using an integrated luminosity of 126 pb - 1. Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables were measured and compared to QCD predictions and to previous measurements. The data were found to be well described by the predictions from next-to-leading-order QCD. The dijet sample of beauty photoproduction events was also used to study higher-order QCD topologies. At leading order, the two jets in the event are produced back-to-back in azimuthal angle, such that Δφ jj =φ j1 -φ j2 =π. Additional soft radiation causes small azimuthal decorrelations, whilst Δφ jj significantly lower than π is evidence of additional hard radiation. In this thesis, the cross section versus Δφ jj for beauty photoproduction and the comparison to NLO QCD predictions and Monte Carlo models are presented. (orig.)

  8. Tests of QCD factorisation in the diffractive production of dijets in deep-inelastic scattering and photoproduction at HERA

    Science.gov (United States)

    Aktas, A.; Andreev, V.; Anthonis, T.; Antunovic, B.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Beckingham, M.; Begzsuren, K.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, N.; Bizot, J. C.; Boenig, M.-O.; Boudry, V.; Bozovic-Jelisavcic, I.; Bracinik, J.; Brandt, G.; Brinkmann, M.; Brisson, V.; Bruncko, D.; Büsser, F. W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A. J.; Cantun Avila, K. B.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Cholewa, A.; Contreras, J. G.; Coughlan, J. A.; Cozzika, G.; Cvach, J.; Dainton, J. B.; Daum, K.; de Boer, Y.; Delcourt, B.; Del Degan, M.; de Roeck, A.; de Wolf, E. A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, G.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eliseev, A.; Elsen, E.; Essenov, S.; Falkewicz, A.; Faulkner, P. J. W.; Favart, L.; Fedotov, A.; Felst, R.; Feltesse, J.; Ferencei, J.; Finke, L.; Fleischer, M.; Flucke, G.; Fomenko, A.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Ghazaryan, S.; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Gouzevitch, M.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B. R.; Grindhammer, G.; Habib, S.; Haidt, D.; Hansson, M.; Heinzelmann, G.; Helebrant, C.; Henderson, R. C. W.; Henschel, H.; Herrera, G.; Hildebrandt, M.; Hiller, K. H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Hreus, T.; Hussain, S.; Jacquet, M.; Janssen, X.; Jemanov, V.; Jönsson, L.; Johnson, D. P.; Jung, A. W.; Jung, H.; Kapichine, M.; Katzy, J.; Kenyon, I. R.; Kiesling, C.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Kraemer, M.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Krüger, K.; Landon, M. P. J.; Lange, W.; Laštovička-Medin, G.; Laycock, P.; Lebedev, A.; Leibenguth, G.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; Liptaj, A.; List, B.; List, J.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Lytkin, L.; Makankine, A.; Malinovski, E.; Marage, P.; Marti, L.; Martisikova, M.; Martyn, H.-U.; Maxfield, S. J.; Mehta, A.; Meier, K.; Meyer, A. B.; Meyer, H.; Meyer, J.; Michels, V.; Mikocki, S.; Milcewicz-Mika, I.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J. V.; Mozer, M. U.; Müller, K.; Murín, P.; Nankov, K.; Naroska, B.; Naumann, T.; Newman, P. R.; Niebuhr, C.; Nikiforov, A.; Nowak, G.; Nowak, K.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J. E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Pandurovic, M.; Papadopoulou, T.; Pascaud, C.; Patel, G. D.; Peng, H.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Picuric, I.; Piec, S.; Pitzl, D.; Plačakytė, R.; Povh, B.; Prideaux, P.; Rahmat, A. J.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D. P. C.; Sauter, M.; Sauvan, E.; Schätzel, S.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schöning, A.; Schultz-Coulon, H.-C.; Sefkow, F.; Shaw-West, R. N.; Sheviakov, I.; Shtarkov, L. N.; Sloan, T.; Smiljanic, I.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, A.; Steder, M.; Stella, B.; Stiewe, J.; Stoilov, A.; Straumann, U.; Sunar, D.; Sykora, T.; Tchoulakov, V.; Thompson, G.; Thompson, P. D.; Toll, T.; Tomasz, F.; Traynor, D.; Trinh, T. N.; Truöl, P.; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, K.; Usik, A.; Utkin, D.; Valkárová, A.; Vallée, C.; van Mechelen, P.; Vargas Trevino, A.; Vazdik, Y.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Wessels, M.; Wissing, C.; Wolf, R.; Wünsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Žáček, J.; Zálešák, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zhu, Y. C.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2007-08-01

    Measurements are presented of differential dijet cross sections in diffractive photoproduction (Q2<0.01 GeV2) and deep-inelastic scattering processes (DIS, 4photoproduction, the predicted dijet cross section has to be multiplied by a factor of approximately 0.5 for both direct and resolved photon interactions to describe the measurements. The ratio of measured dijet cross section to NLO prediction in photoproduction is a factor 0.5±0.1 smaller than the same ratio in DIS. This suppression is the first clear observation of QCD hard scattering factorisation breaking at HERA. The measurements are also compared to the two soft colour neutralisation models SCI and GAL. The SCI model describes diffractive dijet production in DIS but not in photoproduction. The GAL model fails in both kinematic regions.

  9. An unusual diphosphatase from the PhnP family cleaves reactive FAD photoproducts.

    Science.gov (United States)

    Beaudoin, Guillaume A W; Li, Qiang; Bruner, Steven D; Hanson, Andrew D

    2018-01-11

    Flavins are notoriously photolabile, but while the photoproducts derived from the iso -alloxazine ring are well known the other photoproducts are not. In the case of FAD, typically the main cellular flavin, the other photoproducts are predicted to include four- and five-carbon sugars linked to ADP. These FAD photoproducts were shown to be potent glycating agents, more so than ADP-ribose. Such toxic compounds would require disposal via an ADP-sugar diphosphatase or other route. Comparative analysis of bacterial genomes uncovered a candidate disposal gene that is chromosomally clustered with genes for FAD synthesis or transport and is predicted to encode a protein of the PhnP cyclic phosphodiesterase family. The representative PhnP family enzyme from Koribacter versatilis (here named Fpd, F AD p hotoproduct d iphosphatase) was found to have high, Mn 2+ -dependent diphosphatase activity against FAD photoproducts, FAD, and ADP-ribose, but almost no phosphodiesterase activity against riboflavin 4',5'-cyclic phosphate, a chemical breakdown product of FAD. To provide a structural basis of the unique Fpd activity, the crystal structure of K. versatilis Fpd was determined. The results place Fpd in the broad metallo-β-lactamase-like family of hydrolases, a diverse family commonly using two metals for hydrolytic catalysis. The active site of Fpd contains two Mn 2+ ions and a bound phosphate, consistent with a diphosphatase mechanism. Our results characterize the first PhnP family member that is a diphosphatase rather than a cyclic phosphodiesterase and suggest its involvement in a cellular damage-control system that efficiently hydrolyzes the reactive, ADP-ribose-like products of FAD photodegradation. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  10. Determination of the pion-nucleon coupling constant and scattering lengths

    CERN Document Server

    Ericson, Torleif Eric Oskar; Thomas, A W

    2002-01-01

    We critically evaluate the isovector GMO sum rule for forward pion-nucleon scattering using the recent precision measurements of negatively charged pion-proton and pion-deuteron scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data a pseudoscalar coupling constant of 14.17+-0.05(statistical)+-0.19(systematic) or a pseudovector one of 0.0786(11). This value is intermediate between that of indirect methods and the direct determination from backward neutron-proton differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the negatively charged pion-proton and pion-neutron scattering lengths with high precision. The symmetric sum gives 0.0017+-0.0002(statistical)+-0.0008 (systematic) and the antisymmetric one 0.0900+-0.0003(statistical)+-0.0013(systematic), both in units of inverse charged pi...

  11. Low-energy photo- and electroproduction for physical pions

    International Nuclear Information System (INIS)

    MacMullen, J.T.

    1979-02-01

    The Ward identities of current algebra are combined with gauge invariance constraints, on-shell PCAC and the Bjorken limit to obtain the low-energy expressions of the pion photo- and electroproduction invariant amplitudes for physical pions

  12. [Measurements of observables of pion-nucleon reactions]. Progress report

    International Nuclear Information System (INIS)

    Sadler, M.E.

    1985-01-01

    This document reports the progress of the research of pion reactions. These include (1) a study to measure observables in the pion-nucleon system in the momentum interval 400 to 700 MeV/c, (2) differential cross section measurements at low energy for pion-nucleon charge exchange, and (3) elastic and inelastic scattering of π +- on 3 H and 3 He. Individual experiments will be indexed separately

  13. Crystal physics with positive pions

    International Nuclear Information System (INIS)

    Flik, G.

    1983-01-01

    The π + /μ + lattice channeling is a new method of investigation in solid state physics. In the present thesis axial and planar channeling effects could be observed for the first time in monocrystalline Tantalum for 4, 12 MeV Muons generated by the decay of implanted positive pions. It is found that pions for T + /μ + channeling is investigated in Germanium for low temperatures. For T > 80 K tetrahedral sites are found, but for T < 80 K hexaedral sites or sites in the middle of the Ge-Ge bond are preferred. (BHO)

  14. Measurement of Anti-Deuteron Photoproduction and a Search for Heavy Stable Charged Particles at HERA

    CERN Document Server

    Aktas, A.; Anthonis, T.; Asmone, A.; Babaev, A.; Backovic, S.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Berndt, T.; Bizot, J.C.; Bohme, J.; Boenig, M.O.; Boudry, V.; Bracinik, J.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Chekelian, V.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dodonov, V.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flucke, G.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Franke, G.; Frising, G.; Gabathuler, E.; Gabathuler, K.; Garutti, E.; Garvey, J.; Gayler, J.; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Gorbounov, S.; Grab, C.; Grassler, H.; Greenshaw, T.; Gregori, M.; Grindhammer, Guenter; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R.C.W.; Henschel, H.; Henshaw, O.; Heremans, R.; Herrera, G.; Herynek, I.; Heuer, R.D.; Hildebrandt, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, H.; Kant, D.; Kapichine, M.; Karlsson, M.; Katzy, J.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Knutsson, A.; Koblitz, B.; Korbel, V.; Kostka, P.; Koutouev, R.; Kropivnitskaya, A.; Kroseberg, J.; Kuckens, J.; Kuhr, T.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebedev, A.; Leiner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lueders, H.; Luke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marks, J.; Marshall, R.; Martisikova, M.; Martyn, H.U.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Michine, S.; Mikocki, S.; Milcewicz, I.; Milstead, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morozov, I.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Ossoskov, G.; Ozerov, D.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Poschl, R.; Portheault, B.; Povh, B.; Raicevic, N.; Ratiani, Z.; Reimer, P.; Reisert, B.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Sauvan, E.; Schatzel, S.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Uraev, A.; Urban, Marcel; Usik, A.; Utkin, D.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vargas Trevino, A.; Vassiliev, S.; Vazdik, Y.; Veelken, C.; Vest, A.; Vichnevski, A.; Vinokurova, S.; Volchinski, V.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Winter, G.G.; Wissing, Ch.; Woehrling, E.E.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zohrabyan, H.; Zomer, F.

    2004-01-01

    The cross section for anti-deuteron photoproduction is measured at HERA at a mean centre-of-mass energy of W_{\\gamma p} = 200 GeV in the range 0.2 < p_T/M < 0.7 and |y| < 0.4, where M, p_T and y are the mass, transverse momentum and rapidity in the laboratory frame of the anti-deuteron, respectively. The numbers of anti-deuterons per event are found to be similar in photoproduction to those in central proton-proton collisions at the CERN ISR but much lower than those in central Au-Au collisions at RHIC. The coalescence parameter B_2, which characterizes the likelihood of anti-deuteron production, is measured in photoproduction to be 0.010 \\pm 0.002 \\pm 0.001, which is much higher than in Au-Au collisions at a similar nucleon-nucleon centre-of-mass energy. No significant production of particles heavier than deuterons is observed and upper limits are set on the photoproduction cross sections for such particles.

  15. Multi-pion production in deuteron-proton collisions at COSY-ANKE

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, Malte Marius

    2014-07-01

    The presented work is a contribution to the research on two- and three pion production in deuteron-proton collisions. Whereas the latter has received very little attention so far, the former is attracting the interest of particle physicists since several decades. An important reason for this is the appearance of the so-called ABC effect, a striking enhancement in the two-pion invariant mass spectrum near its threshold. There is strong evidence that this is related to the presence of nucleons and in the context of recent investigations it is even linked to an excitation of dibaryon resonances. The here presented results from an exclusive measurement of the dp→{sup 3}Heπ{sup +}π{sup -} reaction with the COSY-ANKE facility at an excess energy of 265 MeV benefit from high statistics as well as a good momentum resolution. Events with coincidentally detected {sup 3}Heπ{sup ±} and {sup 3}Heπ{sup +}π{sup -} combinations were used for the analysis. Various selection steps led to a very clean data sample. The limited geometrical acceptance of the ANKE detector was studied in detail in order to successfully elaborate a reliable correction method. Based on this, it was possible to determine differential and double differential cross sections for a large fraction of the backward {sup 3}He hemisphere. The derived invariant mass distributions do allow to illuminate further details of the two-pion production processes. Besides the prominent ABC enhancement, they reveal a significant difference in the behaviour of the positively and negatively charged pions, which is interpreted to be caused by π{sup +}π{sup -} isovector contributions. The total results are successfully described in terms of a N{sup *}(1440)→Δ(1232)→N decay chain. However, the isobar model surprisingly underestimates the charge difference at low two-pion invariant masses, indicating further contribution to the isovector channel. Investigations on the simultaneously measured dp→{sup 3}Heπ{sup +}

  16. Pion correlation from Skyrmion--anti-Skyrmion annihilation

    International Nuclear Information System (INIS)

    Lu, Y.; Amado, R.D.

    1995-01-01

    We study two pion correlations from Skyrmion and anti-Skyrmion collision, using the product ansatz and an approximate random grooming method for nucleon projection. The spatial-isospin coupling inherent in the Skyrme model, along with empirical averages, leads to correlations not only among pions of like charges but also among unlike charge types

  17. Charged pion photoproduction from 10B

    International Nuclear Information System (INIS)

    Rowley, D.; LeRose, J.; Min, K.; Sapp, B.O.; Stoler, P.; Winhold, E.J.; Yergin, P.F.; Bernstein, A.M.; Blomqvist, K.I.; Caplan, H.S.; Dytman, S.A.; Franklin, G.; Pauli, M.

    1982-01-01

    Measurements were made of dsigma/dΩ [theta/sub π/ = 90 0 (lab)] for 10 B(γ,π + ) 10 Be(g.s.) at T/sub π/ = 17, 29, and 42 MeV, for 10 B(γ,π + ) 10 Be(E/sub x/ = 3.37 MeV) at T/sub π/ = 29 and 42 MeV, and for 10 B(γ,π - ) 10 C(g.s.) at T/sub π/ = 29 MeV. The results disagree significantly with several recent distorted-wave impulse approximation calculations

  18. Polarization Measurements in Neutral Pion Photoproduction

    International Nuclear Information System (INIS)

    C. Jones; Krishni Wijesooriya; B. Fox; Andrei Afanasev; Moscov Amaryan; Konrad Aniol; Stephen Becher; Kamal Benslama; Louis Bimbot; Peter Bosted; Edward Brash; John Calarco; Zhengwei Chai; C. Chang; Ting Chang; Jian-Ping Chen; Seonho Choi; Eugene Chudakov; Steve Churchwell; Domenick Crovelli; Sonja Dieterich; Scott Dumalski; Dipangkar Dutta; Martin Epstein; Kevin Fissum; Salvatore Frullani; Haiyan Gao; Juncai Gao; Franco Garibaldi; Olivier Gayou; Ronald Gilman; Oleksandr Glamazdin; Charles Glashausser; Javier Gomez; Viktor Gorbenko; Ole Hansen; Roy Holt; Jordan Hovdebo; Garth Huber; Kees de Jager; Xiaodong Jiang; Mark Jones; Jim Kelly; Edward Kinney; Edgar Kooijman; Gerfried Kumbartzki; Michael Kuss; John LeRose; Meme Liang; Richard Lindgren; Nilanga Liyanage; Sergey Malov; Demetrius Margaziotis; Pete Markowitz; Kathy McCormick; Dave Meekins; Zein-Eddine Meziani; Robert Michaels; Joe Mitchell; Ludyvine Morand; Charles Perdrisat

    2002-01-01

    We present measurements of the recoil proton polarization for the 1 H(gamma-vector,p-vector)pi 0 reaction for theta c.m. pi = 60 o -135 o and for photon energies up to 4.1 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. Various theoretical models are compared with the results. No evidence for hadron helicity conservation is observed. Models that employ factorization are not favored. It appears from the strong angular dependence of the induced polarization at photon energies of 2.5 and 3.1 GeV that a relatively high spin resonance or background amplitude might exist in this energy region

  19. Chiral symmetry breaking and the pion quark structure

    International Nuclear Information System (INIS)

    Bernard, V.

    1986-01-01

    The mechanism of dynamical breaking of chiral symmetry in hadronic matter is first studied in the framework of the Nambu and Jona-Lasinio model on one hand and its generalisation to finite hadron size on the other hand. The analysis uses a variational procedure modelled after the BCS superconductor. Our study indicates for example, a great sensitivity of various quantities characterizing the breaking of symmetry to the shape of the interaction. Also the mechanism of breaking of chiral symmetry is essentially related to the mechanism of confinement. When a symmetry is spontaneously broken, there exists a Goldstone particle of zero mass. This is true in our model. This particle, the pion, is obtained as solution of a Bethe Salpeter equation for a qantiq bound state. This enables us to establish a connection between the pion as a Goldstone boson related to spontaneous symmetry breaking and the quark-antiquark structure of the pion. The finite mass of the physical pion is obtained with non zero current quark mass. Various properties of this particle are then studied in the RPA formalism. One important point of our model is the highly collective character of the pion. 85 refs [fr

  20. Separation of minimum and higher twist in photoproduction of high-pT mesons

    International Nuclear Information System (INIS)

    Apsimon, R.J.; Flower, P.S.; Hallewell, G.; Morris, J.A.G.; Morris, J.V.; Paterson, C.N.; Sharp, P.H.; Atkinson, M.; Brook, N.; Coyle, P.; Dickinson, B.; Donnachie, A.; Doyle, A.T.; Ellison, R.J.; Foster, J.M.; Hughes-Jones, R.E.; Ibbotson, M.; Kolya, S.D.; Lafferty, G.D.; McCann, H.; McManus, C.; Mercer, D.; Ottewell, P.J.; Reid, D.; Thompson, R.J.; Waterhouse, J.; Barberis, D.; Davenport, M.; Eades, J.; Ingelman, G.; McClatchey, R.; Brodbeck, T.J.; Charity, T.; Clegg, A.B.; Henderson, R.C.W.; Hickman, M.T.; Keemer, N.R.; Newton, D.; O'Connor, A.; Wilson, G.W.; Danaher, S.; Galbraith, W.; Thacker, N.A.; Thompson, L.; Diekmann, B.; Gapp, C.; Gebert, F.; Heinloth, K.; Hoeger, K.C.; Holzkamp, A.; Holzkamp, S.; Jakob, H.P.; Joseph, D.; Kingler, J.; Koersgen, G.; Oedingen, R.; Paul, E.; Rotscheidt, H.; Soeldner-Rembold, S.; Weigend, A.S.

    1991-01-01

    Photo- and hadroproduction data in the beam energy range 65-175 GeV have been studied with a view to isolating higher-twist processes in photoproduction from other point-like and hadron-like contributions. With selection of charged tracks having p T >2 GeV/c and 0.28 F <0.84 indications of a higher twist contribution have been found at a level that is consistent with QCD expectations. (orig.)

  1. Collective flow of pions in relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Russkikh, V.N.; Ivanov, Yu.B.

    1995-02-01

    The transverse-momentum distributions of pions in the Au(1 GeV/nucleon)+Au collisions are analyzed. The calculations are carried out within relativistic meanfield one- and two-fluid models. The rapidity distributions of the mean transverse momentum of pions are found to be fairly sensitive to the nuclear equation of state and, especially, to the stopping power. It is shown that the collective flow of pions in the reaction plane always correlates with the 'hot' flow of nucleons (i.e. those emitted from hot regions of nuclear system), while not always, with the total nucleon flow. This 'hot' nucleon flow can be experimentally singled out by selecting nucleons with sufficiently high transverse momenta. We predict that the 'hot' nucleon flow selected in this way will always correlate with the pion flow. Available experimental data on transverse-momentum spectra of pions are compared with calculations employing various equations of state and stopping power. (orig.)

  2. A coupled-channels analysis of pion scattering and pion-induced eta production on the nucleon

    International Nuclear Information System (INIS)

    Pratt, R.K.; Bennhold, C.; Surya, Y.

    1995-01-01

    Motivated by new, upcoming Brookhaven data, pion scattering and pion-induced eta production on the nucleon in the S 11 (1535) resonance region is studied in an extension of the unitary, relativistic resonance model by Surya and Gross. The Kernel of the relativistic wave equation includes the nucleon, Roper, δ(1232), D 13 (1520) and S 11 (1535) pole terms along with contact σ- and ρ-like exchange terms. The formalism includes a coupling between the πN and ηN channels. The resonance parameters are adjusted to reproduce the experimental πN phase shifts

  3. Pion condensation and density isomerism in nuclear matter

    International Nuclear Information System (INIS)

    Hecking, P.; Weise, W.

    1979-01-01

    The possible existence of density isomers in nuclear matter, induced by pion condensation, is discussed; the nuclear equation of state is treated within the framework of the sigma model. Repulsive short-range baryon-baryon correlations, the admixture of Δ (1232) isobars and finite-range pion-baryon vertex form factors are taken into account. The strong dependence of density isomerism on the high density extrapolation of the equation of state for normal nuclear matter is also investigated. We find that, once finite range pion-baryon vertices are introduced, the appearance of density isomers becomes unlikely

  4. Universal pion freeze-out in heavy-ion collisions.

    Science.gov (United States)

    Adamová, D; Agakichiev, G; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanović, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Milov, A; Miśkowiec, D; Panebrattsev, Yu; Petchenova, O; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Slívová, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V

    2003-01-17

    Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.

  5. Use of reiterative primer extension methodology to map UV-induced photoproducts at the nucleotide level in the laci gene from genomic DNA

    International Nuclear Information System (INIS)

    Chandrasekhar, D.; Houten, B. Van

    1994-01-01

    A newly developed reiterative primer extension assay has been employed to examine photoproduct formation and repair at the nucleotide level. Analysis of UV-induced DNA photoproduct hotspots in the first 184 base pairs of the laci genes of genomic E. coli DNA has revealed that photoproducts are formed linearly with dose and display a sequence-dependent increase. Generally, pyrimdine dimers were twice as frequent as all other UV-induced photoproducts. However, specific sites showed differing distributions. A post-irradiation recovery period revealed differences in the repair efficiency at individual nucleotides. Repair of photoproducts on the transcribed strand was generally twice as efficient as repair of photoproducts on the nontranscribed strand, indicating that strand-specific DNA repair occurs in the constitutively transcribed laci gene of E. coli. The UV-induced DNA photoproduct distribution following repair was well correlated with an established UV-induced mutation spectrum for wild-type E. coli cells. This analysis revealed that photoproduct hotspots on the efficiently repaired transcribed strand did not correlate with mutagenic hotspots. These data strongly support the hypothesis that mutations arise at inefficiently repaired sites on the nontranscribed strand

  6. Electro- and Photoproduction of Omega(783) Mesons using CLAS at Jefferson Lab

    International Nuclear Information System (INIS)

    Manak, J.J.; Volker Burkert; Franz Klein; Bernhard Mecking; Alan Coleman; Herb Funsten

    2000-01-01

    Electro- and photoproduction of w(783) from a proton target have been measured in the CLAS detector at the Thomas Jefferson National Accelerator Facility in Newport News VA. The photoproduction data were taken over a photon energy range from 0.5 to 2.3 GeV, while the electroproduction data was obtained over a W range of 1.8-2.5 GeV/c2. Preliminary acceptance corrected center-of-mass angular distributions have been examined for both data sets

  7. Exclusive electroproduction of two pions at HERA

    CERN Document Server

    Abramowicz, H.

    2012-01-25

    The exclusive electroproduction of two pions in the mass range 0.4 < M{\\pi}{\\pi} < 2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. The analysis was carried out in the kinematic range of 2 < Q2 < 80 GeV2, 32 < W < 180 GeV and |t| < 0.6 GeV2, where Q2 is the photon virtuality, W is the photon-proton centre-of-mass energy and t is the squared four-momentum transfer at the proton vertex. The two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, |F(M{\\pi}{\\pi})|, assuming that the studied mass range includes the contributions of the {\\rho}, {\\rho}' and {\\rho}" vector-meson states. The masses and widths of the resonances were obtained and the Q2 dependence of the cross-section ratios {\\sigma}({\\rho}' \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) and {\\sigma}({\\rho}" \\rightarrow {\\pi}{\\pi})/{\\sigma}({\\rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained...

  8. Pion-nucleon scattering and isospin violation

    International Nuclear Information System (INIS)

    Meissner, U.G.

    1999-01-01

    The paper discusses low-energy pion-nucleon scattering in the framework of chiral perturbation theory. It is argued that using this theoretical method one is able to match the in some cases impressive experimental accuracy (for the low partial waves). It is also shown how strong and electromagnetic isospin violation can be treated simultaneously. Some first results for neutral pion scattering and the σ-term are given. Copyright (1999) World Scientific Publishing Co. Pte. Ltd

  9. The possibility for a pion polarizability measurement at COMPASS

    CERN Document Server

    Guskov, A

    2010-01-01

    The pion electromagnetic structure can be probed in $\\pi^{−}+(A,Z)\\rightarrow\\pi^{-}+(A,Z) + \\gamma$ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric $(\\alpha_{\\pi})$ and the magnetic $(\\beta_{\\pi})$ polarizabilities that depend on the rigidity of pion’s internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of point-like pions with the measured cross section. The opportunity to measure pion polarizability via the Primakoff reaction at the COMPASS experiment was studied with a $\\pi^{−}$ beam of 190 GeV. The obtained results are used for preparation of the new measurement.

  10. On the role of secondary pions in spallation targets

    Energy Technology Data Exchange (ETDEWEB)

    Mancusi, Davide [Paris-Saclay Univ., Gif-sur-Yvette (France). Den-Service d' Etude des Reacteurs et de Mathematiques Appliquees (SERMA); Lo Meo, Sergio [ENEA, Research Centre ' ' Ezio Clementel' ' , Bologna (Italy); INFN, Bologna (Italy); Colonna, Nicola [INFN, Bari (Italy); Boudard, Alain; David, Jean-Christophe; Leray, Sylvie [Paris-Saclay Univ., Gif-sur-Yvette (France). IRFU, CEA; Cortes-Giraldo, Miguel Antonio; Lerendegui-Marco, Jorge [Sevilla Univ. (Spain). Facultad de Fisica; Cugnon, Joseph [Liege Univ. (Belgium). AGO Dept.; Massimi, Cristian [INFN, Bologna (Italy); Bologna Univ. (Italy). Physics and Astronomy Dept.; Vlachoudis, Vasilis [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2017-05-15

    We use particle-transport simulations to show that secondary pions play a crucial role for the development of the hadronic cascade and therefore for the production of neutrons and photons from thick spallation targets. In particular, for the nTOF lead spallation target, irradiated with 20 GeV/c protons, neutral pions are involved in the production of ∝ 90% of the high-energy photons; charged pions participate in ∝ 40% of the integral neutron yield. Nevertheless, photon and neutron yields are shown to be relatively insensitive to large changes of the average pion multiplicity in the individual spallation reactions. We characterize this robustness as a peculiar property of hadronic cascades in thick targets. (orig.)

  11. On the role of secondary pions in spallation targets

    CERN Document Server

    Mancusi, Davide; Colonna, Nicola; Boudard, Alain; Cortés-Giraldo, Miguel Antonio; Cugnon, Joseph; David, Jean-Christophe; Leray, Sylvie; Lerendegui-Marco, Jorge; Massimi, Cristian; Vlachoudis, Vasilis

    2017-01-01

    We use particle-transport simulations to show that secondary pions play a crucial role for the development of the hadronic cascade and therefore for the production of neutrons and photons from thick spallation targets. In particular, for the n_TOF lead spallation target, irradiated with 20-GeV/c protons, neutral pions are involved in the production of ~90% of the high-energy photons; charged pions participate in ~40% of the integral neutron yield. Nevertheless, photon and neutron yields are shown to be relatively insensitive to large changes of the average pion multiplicity in the individual spallation reactions. We characterize this robustness as a peculiar property of hadronic cascades in thick targets.

  12. Relativistic generalizations of simple pion-nucleon models

    International Nuclear Information System (INIS)

    McLeod, R.J.; Ernst, D.J.

    1981-01-01

    A relativistic, partial wave N/D dispersion theory is developed for low energy pion-nucleon elastic scattering. The theory is simplified by treating crossing symmetry only to lowest order in the inverse nucleon mass. The coupling of elastic scattering to inelastic channels is included by taking the necessary inelasticity from experimental data. Three models are examined: pseudoscalar coupling of pions and nucleons, pseudovector coupling, and a model in which all intermediate antinucleons are projected out of the amplitude. The phase shifts in the dominant P 33 channel are quantitatively reproduced for P/sub lab/ 33 phase shifts. Thus a model of the pion-nucleon interaction which does not include antinucleon degrees of freedom is found to be unphysical

  13. Exclusive photoproduction of a γ ρ pair with a large invariant mass

    International Nuclear Information System (INIS)

    Boussarie, R.; Pire, B.; Szymanowski, L.; Wallon, S.

    2017-01-01

    Exclusive photoproduction of a γ ρ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in α s and the differential cross sections for the process where the ρ−meson is either longitudinally or transversely polarized are estimated in the kinematics of the JLab 12-GeV experiments.

  14. Exclusive photoproduction of a γ ρ pair with a large invariant mass

    Energy Technology Data Exchange (ETDEWEB)

    Boussarie, R. [LPT, Université Paris-Sud, CNRS, Université Paris-Saclay,91405, Orsay (France); Pire, B. [Centre de Physique Théorique, Ecole polytechnique, CNRS, Université Paris-Saclay,91128 Palaiseau (France); Szymanowski, L. [National Center for Nuclear Research (NCBJ),00681 Warsaw (Poland); Wallon, S. [LPT, Université Paris-Sud, CNRS, Université Paris-Saclay,91405, Orsay (France); UPMC University Paris 06, Faculté de physique,4 place Jussieu, 75252 Paris Cedex 05 (France)

    2017-02-09

    Exclusive photoproduction of a γ ρ pair in the kinematics where the pair has a large invariant mass and the final nucleon has a small transverse momentum is described in the collinear factorization framework. The scattering amplitude is calculated at leading order in α{sub s} and the differential cross sections for the process where the ρ−meson is either longitudinally or transversely polarized are estimated in the kinematics of the JLab 12-GeV experiments.

  15. Phi Photoproduction in a Coupled-Channel Approach

    NARCIS (Netherlands)

    Ozaki, S.; Nagahiro, H.; Hosaka, A.; Scholten, O.

    2010-01-01

    We investigate photoproduction of phi-mesons off protons within a coupled-channel effective-Lagrangian method which is based on the K-matrix approach. We take into account pi N, rho N, eta N, K Lambda, K Sigma, K Lambda (1520) and phi N channels. Especially we focus on K Lambda(1520) channel. We

  16. Total and differential cross sections for pion production via coherent isobar and giant resonance formation in heavy-ion collisions

    International Nuclear Information System (INIS)

    Deutchman, P.A.; Norbury, J.W.; Townsend, L.W.

    1985-01-01

    A quantal many-body formalism is presented that investigates pion production through the coherent formation of a nucleonic isobar in the projectile and its subsequent decay to various pion charge states along with concomitant excitation of the target to a coherent spin-isospin giant resonance via a peripheral collision of relativistic heavy ions. Total cross sections as a function of the incident energy per nucleon and Lorentz-invariant differential cross sections as a function of pion energy and angle are calculated. It is shown that the pion angular distributions, in coincidence with the target giant resonance excitations, might provide a well-defined signature for these coherent processes

  17. Possibility of investigation of pion degrees of freedom in atomic nuclei with the help of quasielastic pions knocking out by high energy electrons

    CERN Document Server

    Neudachin, V G; Sviridova, L L

    2002-01-01

    The attention is paid to the interesting possibilities of studying the pion degrees of freedom in the atomic nuclei by means of the quasielastic knocking out of pion (e, ep) from the nuclei by the electrons with the energy of several GeV. It appears, that the pulse distribution of the pions, knocked out from the separate nucleons and the nuclei, is in the whole differ essentially different

  18. Photoproduction at high energy and high intensity

    CERN Multimedia

    2002-01-01

    The photon beam used for this programme is tagged and provides a large flux up to very high energies (150-200 GeV). It is also hadron-free, since it is obtained by a two-step conversion method. A spectrometer is designed to exploit this beam and to perform a programme of photoproduction with a high level of sensitivity (5-50 events/picobarn).\\\\ \\\\ Priority will be given to the study of processes exhibiting the point-like behaviour of the photon, especially deep inelastic Compton scattering. The spectrometer has two magnets. Charged tracks are measured by MWPC's located only in field-free regions. Three calorimeters provide a large coverage for identifying and measuring electrons and photons. An iron filter downstream identifies muons. Most of the equipment is existing and recuperated from previous experiments.

  19. Diffractive photoproduction of D*±(2010) at HERA

    International Nuclear Information System (INIS)

    Chekanov, S.; Derrick, M.; Magill, S.

    2007-03-01

    Diffractive photoproduction of D *± (2010) mesons was measured with the ZEUS detector at the ep collider HERA, using an integrated luminosity of 78.6 pb -1 . The D * mesons were reconstructed in the kinematic range: transverse momentum p T (D * )>1.9 GeV and pseudorapidity vertical stroke η(D * ) vertical stroke *+ → D 0 π + s followed by D 0 → K - π + (+c.c.). Diffractive events were identified by a large gap in pseudorapidity between the produced hadronic state and the outgoing proton. Cross sections are reported for photon-proton centre-of-mass energies in the range 130 2 2 , in two ranges of the Pomeron fractional momentum x P P *± (2010) photoproduction cross section is about 6%. The data are in agree- ment with perturbative QCD calculations based on various parameterisations of diffractive parton distribution functions. The results are consistent with diffractive QCD factorisation. (orig.)

  20. Hard photoproduction: An analysis of the first ZEUS data

    International Nuclear Information System (INIS)

    Feld, L.W.

    1993-10-01

    The electron-proton storage ring HERA gives the unique opportunity to study photon-proton collisions at center of mass energies around 200 GeV. This analysis covers the extraction of hard photoproduction events from the data taken by the ZEUS-detector in its first year of operation. It is shown, that these events are well described by the Monte Carlo generators PYTHIA and HERWIG. A jet analysis allows to measure the kinematics of the hard subprocess. Clear evidence for both direct and resolved photon processes is seen in the data. In detailed Monte Carlo studies different photon structure functions are compared to the data. (orig.)

  1. Production and decay of baryonic resonances in pion induced reactions

    Directory of Open Access Journals (Sweden)

    Przygoda Witold

    2016-01-01

    Full Text Available Pion induced reactions give unique opportunities for an unambiguous description of baryonic resonances and their coupling channels. A systematic energy scan and high precision data, in conjunction with a partial wave analysis, allow for the study of the excitation function of the various contributions. A review of available world data unravels strong need for modern facilities delivering measurements with a pion beam. Recently, HADES collaboration collected data in pion-induced reactions on light (12C and heavy (74W nuclei at a beam momentum of 1.7 GeV/c dedicated to strangeness production. It was followed by a systematic scan at four different pion beam momenta (0.656, 0.69, 0.748 and 0.8 GeV/c in π− − p reaction in order to tackle the role of N(1520 resonance in conjunction with the intermediate ρ production. First results on exclusive channels with one pion (π− p and two pions (nπ+π−, pπ−π0 in the final state are discussed.

  2. Relativistic quantum kinetic analysis of a pion--nucleon system

    International Nuclear Information System (INIS)

    Alonso, J.D.

    1985-01-01

    A relativistic plasma of nucleons interacting through pions via the usual isospin-invariant Yukawa coupling is analyzed in the framework of the covariant Wigner function technique. The method is manifestly covariant and the temperature effects are considered. The relativistic quantum BBGKY hierarchy for the pion--nucleon system is derived. By generalizing the Bogolioubov analysis of the classical BBGKY hierarchy a non-perturbative renormalizable method is elaborated which allows the solution of the kinetic problem in form of power series of two cluster parameters which measure the importance of correlations. In the lowest order of the cluster expansion (Hartree approximation of zero-order approximation) the quasi-nucleon Fock space is introduced, the fermion Wigner function in the thermodynamic equilibrium is obtained and the vacuum effects are renormalized. In this approximation the plasma behaves as a perfect Fermi gas of nucleons and antinucleons, but there exists an abnormal configuration with a uniform pion condensate which is unstable. In the next approximation (quadratic in the small parameters) the quasi-pion dispersion relation is obtained and the vacuum polarization tensor is renormalized. The quasi-pion rest-mass spectra (''plasma frequency'') and the effective-coupling behaviour as functions of the thermodynamic state are given. By estimating the size of the cluster parameters the self-consistency of the approximation scheme is proved. The quasi-pion Fock space is introduced and the quasi-pion equilibrium Wigner function is obtained. From these results the problem of the higher-order corrections to the Hartree thermodynamics is outlined

  3. Bose-Einstein correlations of three charged pions in hadronic $Z^{0}$ decays

    CERN Document Server

    Ackerstaff, K; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Ashby, S F; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Bartoldus, R; Batley, J Richard; Baumann, S; Bechtluft, J; Behnke, T; Bell, K W; Bella, G; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Betts, S; Biebel, O; Biguzzi, A; Bird, S D; Blobel, Volker; Bloodworth, Ian J; Bobinski, M; Bock, P; Böhme, J; Boutemeur, M; Braibant, S; Bright-Thomas, P G; Brown, R M; Burckhart, Helfried J; Burgard, C; Bürgin, R; Capiluppi, P; Carnegie, R K; Carter, A A; Carter, J R; Chang, C Y; Charlton, D G; Chrisman, D; Ciocca, C; Clarke, P E L; Clay, E; Cohen, I; Conboy, J E; Cooke, O C; Couyoumtzelis, C; Coxe, R L; Cuffiani, M; Dado, S; Dallavalle, G M; Davis, R; De Jong, S; del Pozo, L A; de Roeck, A; Desch, Klaus; Dienes, B; Dixit, M S; Doucet, M; Dubbert, J; Duchovni, E; Duckeck, G; Duerdoth, I P; Eatough, D; Estabrooks, P G; Etzion, E; Evans, H G; Fabbri, Franco Luigi; Fanfani, A; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fischer, H M; Fleck, I; Folman, R; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Geich-Gimbel, C; Geralis, T; Giacomelli, G; Giacomelli, P; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Gorn, W; Grandi, C; Gross, E; Grunhaus, Jacob; Gruwé, M; Hanson, G G; Hansroul, M; Hapke, M; Hargrove, C K; Hartmann, C; Hauschild, M; Hawkes, C M; Hawkings, R; Hemingway, Richard J; Herndon, M; Herten, G; Heuer, R D; Hildreth, M D; Hill, J C; Hillier, S J; Hobson, P R; Höcker, Andreas; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Igo-Kemenes, P; Imrie, D C; Ishii, K; Jacob, F R; Jawahery, A; Jeremie, H; Jimack, Martin Paul; Joly, A; Jones, C R; Jovanovic, P; Junk, T R; Karlen, D A; Kartvelishvili, V G; Kawagoe, K; Kawamoto, T; Kayal, P I; Keeler, Richard K; Kellogg, R G; Kennedy, B W; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Koetke, D S; Kokott, T P; Kolrep, M; Komamiya, S; Kowalewski, R V; Kress, T; Krieger, P; Von Krogh, J; Kyberd, P; Lafferty, G D; Lanske, D; Lauber, J; Lautenschlager, S R; Lawson, I; Layter, J G; Lazic, D; Lee, A M; Lefebvre, E; Lellouch, Daniel; Letts, J; Levinson, L; Liebisch, R; List, B; Littlewood, C; Lloyd, A W; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Ludwig, J; Liu, D; Macchiolo, A; MacPherson, A L; Mannelli, M; Marcellini, S; Markopoulos, C; Martin, A J; Martin, J P; Martínez, G; Mashimo, T; Mättig, P; McDonald, W J; McKenna, J A; McKigney, E A; McMahon, T J; McPherson, R A; Meijers, F; Menke, S; Merritt, F S; Mes, H; Meyer, J; Michelini, Aldo; Mihara, S; Mikenberg, G; Miller, D J; Mir, R; Mohr, W; Montanari, A; Mori, T; Nagai, K; Nakamura, I; Neal, H A; Nellen, B; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, James L; Plane, D E; Poffenberger, P R; Poli, B; Polok, J; Przybycien, M B; Rembser, C; Rick, Hartmut; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Roscoe, K; Rossi, A M; Rozen, Y; Runge, K; Runólfsson, O; Rust, D R; Sachs, K; Saeki, T; Sahr, O; Sang, W M; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharf, F; Scharff-Hansen, P; Schieck, J; Schmitt, B; Schmitt, S; Schöning, A; Schörner-Sadenius, T; Schröder, M; Schumacher, M; Schwick, C; Scott, W G; Seuster, R; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Sproston, M; Stahl, A; Stephens, K; Steuerer, J; Stoll, K; Strom, D; Ströhmer, R; Tafirout, R; Talbot, S D; Tanaka, S; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomson, M A; Von Törne, E; Torrence, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Van Kooten, R; Vannerem, P; Verzocchi, M; Vikas, P; Voss, H; Wäckerle, F; Wagner, A; Ward, C P; Ward, D R; Watkins, P M; Watson, A T; Watson, N K; Wells, P S; Wermes, N; White, J S; Wilson, G W; Wilson, J A; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D

    1998-01-01

    Bose-Einstein Correlations (BEC) of three identical charged pions were studied in 4 x 10^6 hadronic Z^0 decays recorded with the OPAL detector at LEP. The genuine three-pion correlations, corrected for the Coulomb effect, were separated from the known two-pion correlations by a new subtraction procedure. A significant genuine three-pion BEC enhancement near threshold was observed having an emitter source radius of r_3 = 0.580 +/- 0.004 (stat.) +/- 0.029 (syst.) fm and a strength of \\lambda_3 = 0.504 +/- 0.010 (stat.) +/- 0.041 (syst.). The Coulomb correction was found to increase the \\lambda_3 value by 0.707 +/- 0.014 (stat.) +/- 0.078 (syst.) when one takes into account the three-pion sample purity. A relation between the two-pion and the three-pion source parameters is discussed.

  4. Beauty in photoproduction at HERA II with the ZEUS detector

    Energy Technology Data Exchange (ETDEWEB)

    Boutle, Sarah

    2010-02-15

    The production of beauty quarks in ep collisions should be accurately calculable in perturbative Quantum Chromodynamics (QCD) since the large mass of the b quark provides a hard scale. Therefore it is interesting to compare such predictions to results using photoproduction events where a low-virtuality photon, emitted by the incoming lepton, collides with a parton from the incoming proton. A measurement of beauty in photoproduction has been made at HERA with the ZEUS detector using an integrated luminosity of 126 pb{sup -}1. Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables were measured and compared to QCD predictions and to previous measurements. The data were found to be well described by the predictions from next-to-leading-order QCD. The dijet sample of beauty photoproduction events was also used to study higher-order QCD topologies. At leading order, the two jets in the event are produced back-to-back in azimuthal angle, such that {delta}{phi}{sup jj}={phi}{sup j1}-{phi}{sup j2}={pi}. Additional soft radiation causes small azimuthal decorrelations, whilst {delta}{phi}{sup jj} significantly lower than {pi} is evidence of additional hard radiation. In this thesis, the cross section versus {delta}{phi}{sup jj} for beauty photoproduction and the comparison to NLO QCD predictions and Monte Carlo models are presented. (orig.)

  5. High pT charm photoproduction

    International Nuclear Information System (INIS)

    Abbiendi, G.; Butterworth, J.M.

    1996-09-01

    The expected rates for charm-tagged jet photoproduction are evaluated for a number of tagging procedures, and some of the physics potential is discussed. Charm in jets is tagged using D * 's, μ's, or tracks from secondary vertices which might be identified in a microvertex detector. We find high expected event rates, leading to the possibility of placing strong constraints on the kinematics of charm production and on the gluon content of the proton and the charm content of the photon. (orig.)

  6. Virtual reality: electromagnetic decays and new hadrons

    International Nuclear Information System (INIS)

    Landsberg, L.G.

    1998-01-01

    The electromagnetic Coulomb processes and their application to study of radiative decays of hadrons and to the search for some exotic states are discussed. The Coulomb processes h + (Z, A) → (Z, A) involving collisions with virtual photons are photoproduction reactions on primary hadrons h. With pion, kaon or hyperon beams it is possible to study photoproduction on unstable targets (π, Κ, Υ). The results of several experiments for direct study of rare radiation decays of mesons are presented. The main features of the Coulomb production and coherent background reactions governed by strong interactions are considered. The main results of the Primakoff production study are summarized with some recent data in the SELEX experiment at E L = 600 eV obtained by means of Fermilab Tevatron. The SPHINX experiment allows to obtain new information on exotic baryons and other states [ru

  7. Two pion correlation from SPACER

    International Nuclear Information System (INIS)

    Csoergoe, T.; Zimanyi, J.; Pratt, S.

    1989-12-01

    The correlation function for neutral and negative pions produced in ultrarelativistic heavy ion collisions was calculated without free parameters based on a space-time version of the LUND model, called SPACER: Simulation of Phase space distribution of Atomic nuclear Collisions in Energetic Reactions. This method includes the effect of Bose correlations for the emitted pion pair. Effects arising from correlations between space-time and momentum space distributions are investigated. The results are compared to the data of two different experiments. The role and interpretation of the chaocity parameter are discussed. (D.G.) 14 refs.; 4 figs

  8. Phi photoproduction near threshold with Okubo-Zweig-Iizuka evading phi NN interactions

    CERN Document Server

    William, R A

    1998-01-01

    Existing intermediate and high energy phi-photoproduction data is consistent with purely diffractive production (i.e., Pomeron exchange). However, near threshold (1.574 GeV K sup + K sup - decay angular distribution. We stress the importance of measurements with linearly polarized photons near the phi threshold to separate natural and unnatural parity exchange mechanisms. Approved and planned phi photoproduction and electroproduction experiments at Jefferson Lab will help establish the relative dynamical contributions near threshold and clarify outstanding theoretical issues related to apparent Okubo-Zweig-Iizuka violations.

  9. Photoproduction of events with rapidity gaps between jets at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Chekanov, S.; Derrick, M.; Magill, S. [Argonne National Laboratory, Argonne, IL (US)] (and others)

    2006-12-15

    The photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 39 pb{sup -1}. Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E{sub T}{sup C}UT. The data show a clear excess over the predictions of standard photoproduction models. This is interpreted as evidence for a strongly interacting exchange of a color-singlet object. Monte Carlo models which include such a color-singlet exchange are able to describe the data. (orig.)

  10. Photoproduction of events with rapidity gaps between jets at HERA

    International Nuclear Information System (INIS)

    Chekanov, S.; Derrick, M.; Magill, S.

    2006-12-01

    The photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 39 pb -1 . Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E T C UT. The data show a clear excess over the predictions of standard photoproduction models. This is interpreted as evidence for a strongly interacting exchange of a color-singlet object. Monte Carlo models which include such a color-singlet exchange are able to describe the data. (orig.)

  11. Dijet angular distributions in direct and resolved photoproduction at HERA

    International Nuclear Information System (INIS)

    Derrick, M.; Krakauer, D.; Magill, S.

    1996-05-01

    Jet photoproduction, where the two highest transverse energy (E T jet ) jets have E T jet above 6 GeV and a jet-jet invariant mass above 23 GeV, has been studied with the ZEUS detector at the HERA ep collider. Resolved and direct photoproduction samples have been separated. The cross section as a function of the angle between the jet-jet axis and the beam direction in the dijet rest frame has been measured for the two samples. The measured angular distributions differ markedly from each other. They agree with the predictions of QCD calculations, where the different angular distributions reflect the different spins of the quark and gluon exchanged in the hard subprocess. (orig.)

  12. Pion interactions with light nuclei and applications to radiotherapy

    International Nuclear Information System (INIS)

    Brenner, D.J.

    1979-02-01

    In the light of the current interest in negative pion radiotherapy particle spectra have been obtained after negative pion absorption in oxygen. Using a multiple foil activation technique, measurements were made of neutron spectra from the pion interactions and also from background sources from which it appears that the technique is a potentially useful tool for routine dosimetry. Theoretical predictions are made of the energy spectra of particles emitted after stopped pion absorption on oxygen based on an alpha cluster model and using a plane-wave impulse approximation. A method of considering residual interactions with the nucleus is described which has the potential to treat the low energy particles and also final channels not expected as a result of a single interaction. (UK)

  13. Deeply virtual compton scattering on a virtual pion target

    International Nuclear Information System (INIS)

    Amrath, D.; Diehl, M.; Lansberg, J.P.; Heidelberg Univ.

    2008-07-01

    We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge asymmetries in the leading-twist approximation. Studying Compton scattering on the pion in suitable kinematics puts high demands on both beam energy and luminosity, and we find that the corresponding requirements will first be met after the energy upgrade at Jefferson Laboratory. As a by-product of our study, we construct a parameterization of pion generalized parton distributions that has a non-trivial interplay between the x and t dependence and is in good agreement with form factor data and lattice calculations. (orig.)

  14. Universal pion freeze-out in heavy-ion collisions

    CERN Document Server

    Adamova, D; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanovic, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Zeev; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B C; Ludolphs, W; Maas, A; Marin, A; Milosevic, J; Milov, A; Miskowiec, D; Panebratsev, Yu A; Petchenova, O Yu; Petracek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schükraft, Jürgen; Sedykh, S; Shimansky, S S; Slivova, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, Itzhak; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V; Schmitz, W

    2003-01-01

    Based on an evaluation of recent systematic data on two-pion interferometry and on measured particle yields at mid-rapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda_f reaches a value of approximately 2.5 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and its value is constant at all currently available beam energies from AGS to RHIC.

  15. Photonuclear physics at the Bonn synchrotrons. Present status and future plans at the Bonn synchrotron

    International Nuclear Information System (INIS)

    Mecking, B.A.

    1983-11-01

    The activities in the field of photonuclear physics at the Bonn 500 MeV and 2.5 GeV synchrotrons are reviewed. The experiments concentrate on photodisintegration and pion-photoproduction reactions on light nuclei. (orig.)

  16. Scattering of low-energy pions by p-shell nuclei

    International Nuclear Information System (INIS)

    Khankhasaev, M.Kh.

    1987-01-01

    Low-energy pion-carbon scattering (up to 50 MeV) is analysed in the framework of the unitary approach based on the method of evolution in the coupling constant. It is shown that at pion energy ∼ 50 MeV the differential cross section arises as a result of the strong interference between the pure potential scattering and absorption channels. In this energy region the scattering data are very sensitive to the dynamics of the pion-nucleus interaction

  17. Pion-Skyrmion scattering: collective coordinates at work

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1985-06-01

    It is argued that the Skryme model, and more generally, the picture of the nucleon as a chiral soliton, can give a qualitatively correct picture of pion-nucleon scattering, considering both group-theoretic and more scheme-dependent results. The properties of the nucleon and its excited states in large-N quantum chromodynamics are discussed qualitatively. Then the pion-nucleon S-matrix is reduced. It is found that the model succeeds at the first level of calculation in producing many of the features of pion-nucleon scattering which are revealed by experiment, but that many aspects of the description need to be better understood, including the treatment of nonleading corrections near threshold and the inclusion of inelastic channels. 22 refs., 8 figs

  18. Coupled channel analysis of s-wave ππ and K anti-K photoproduction

    International Nuclear Information System (INIS)

    Chueng-Ryong Ji; Szczepaniak, A.; Kaminski, R.; Lesniak, L.; Williams, R.

    1997-10-01

    We present a coupled channel partial wave analysis of non-diffractive S-wave π + π - and K + K - photoproduction focusing on the K anti-K threshold. Final state interactions are included. We calculate total cross sections, angular and effective mass distributions in both ππ and K anti-K channels. Our results indicate that these processes are experimentally measurable and valuable information on the f 0 (980) resonance structure can be obtained. (author)

  19. Basic features of the pion valence-quark distribution function

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Lei [CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005 (Australia); Mezrag, Cédric; Moutarde, Hervé [Centre de Saclay, IRFU/Service de Physique Nucléaire, F-91191 Gif-sur-Yvette (France); Roberts, Craig D. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Rodríguez-Quintero, Jose [Departamento de Física Aplicada, Facultad de Ciencias Experimentales, Universidad de Huelva, Huelva E-21071 (Spain); Tandy, Peter C. [Center for Nuclear Research, Department of Physics, Kent State University, Kent, OH 44242 (United States)

    2014-10-07

    The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow–ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q{sup π}(x); namely, at a characteristic hadronic scale, q{sup π}(x)∼(1−x){sup 2} for x≳0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.

  20. THE ETA-MESON PHOTOPRODUCTION ON PROTON

    Czech Academy of Sciences Publication Activity Database

    Donoval, Jan; Bydžovský, Petr

    2011-01-01

    Roč. 26, 3-4 (2011), s. 645-646 ISSN 0217-751X. [11th International Workshop on Meson Production , Properties and Interaction. Krakow, 10.06.2010-15.06.2010] R&D Projects: GA ČR GA202/08/0984 Institutional research plan: CEZ:AV0Z10480505 Keywords : Eta-meson photoproduction * form factors * nucleon resonances Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.053, year: 2011

  1. Photoproduction of π{sup 0} -pairs off protons and off neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Dieterle, M.; Oberle, M.; Garni, S.; Kaeser, A.; Keshelashvili, I.; Krusche, B.; Maghrbi, Y.; Pheron, F.; Rostomyan, T.; Strub, T.; Walford, N.K.; Werthmueller, D.; Witthauer, L. [University of Basel, Department of Physics, Basel (Switzerland); Ahrens, J.; Arends, H.J.; Bartolome, P.A.; Heid, E.; Jahn, O.; Ostrick, M.; Otte, P.; Schumann, S.; Thomas, A. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Annand, J.R.M.; Glazier, D.I.; Hamilton, D.; Howdle, D.; Livingston, K.; MacGregor, I.J.D.; Mancell, J.; McGeorge, J.C.; McNicoll, E.; Robinson, J. [University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); Bantawa, K.; Manley, D.M. [Kent State University, Kent, Ohio (United States); Beck, R.; Nikolaev, A. [University of Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Bekrenev, V. [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Berghaeuser, H.; Drexler, P.; Metag, V.; Novotny, R.; Thiel, M. [University of Giessen, II. Physikalisches Institut, Giessen (Germany); Braghieri, A.; Costanza, S.; Mushkarenkov, A.; Pedroni, P. [INFN Sezione di Pavia, Pavia (Italy); Branford, D.; Jude, T.C.; Sikora, M.H.; Watts, D.P. [University of Edinburgh, SUPA School of Physics, Edinburgh (United Kingdom); Briscoe, W.J.; Demissie, B.; Marinides, Z. [The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Brudvik, J.; Starostin, A. [University of California Los Angeles, Los Angeles, California (United States); Cherepnya, S.; Fil' kov, L.V. [Lebedev Physical Institute, Moscow (Russian Federation); Downie, E.J. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Glasgow, SUPA School of Physics and Astronomy, Glasgow (United Kingdom); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Fix, A. [Tomsk Polytechnic University, Laboratory of Mathematical Physics, Tomsk (Russian Federation); Hornidge, D.; Middleton, D.G. [Mount Allison University, New Brunswick (Canada); Huber, G.M. [University of Regina, Regina (Canada); Kashevarov, V.L. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); Lebedev Physical Institute, Moscow (Russian Federation); Kondratiev, R.; Lisin, V.; Polonski, A. [Institute for Nuclear Research, Moscow (Russian Federation); Korolija, M.; Mekterovic, D.; Micanovic, S.; Supek, I. [Rudjer Boskovic Institute, Zagreb (Croatia); Oussena, B. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); Prakhov, S. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); The George Washington University, Center for Nuclear Studies, Washington, DC (United States); University of California Los Angeles, Los Angeles, California (United States); Sober, D.I. [The Catholic University of America, Washington, DC (United States); Unverzagt, M. [University of Mainz, Institut fuer Kernphysik, Mainz (Germany); University of Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany); Collaboration: The A2 Collaboration

    2015-11-15

    Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π{sup 0}π{sup 0} pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400 MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ∼ 1550 MeV), where both reactions are dominated by the N(1520)3/2{sup -} → Δ(1232)3/2{sup +}π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N{sup *} → Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis. (orig.)

  2. Pion form factor within QCD instanton vacuum model

    International Nuclear Information System (INIS)

    Dorokhov, A.E.

    1997-01-01

    Instanton induced pion wave function is constructed. It provides an intrinsic k 1 dependence which suppress soft virtual one-gluon exchanges and thus legitimate the perturbative QCD (pQCD) calculations of the pion electromagnetic form factor in the region of momentum transfers above the scale. (author)

  3. Electromagnetic properties of the pion as a composite Nambu-Goldstone boson

    International Nuclear Information System (INIS)

    Ito, H.; Buck, W.W.; Gross, F.

    1992-01-01

    Motivated by the Nambu--Jona-Lasinio model of light mesons, we introduce a covariant separable interaction to model the structure of relativistic quark-antiquark systems. The Schwinger-Dyson equation for the quark self-energy is solved analytically, generating a dynamical quark mass through spontaneous breaking of chiral symmetry, and yielding a pion which has zero mass in the chiral limit. The Bethe-Salpeter vertex function for this q bar q pion, which has a momentum distribution and composite structure associated with the interaction, is obtained analytically. Using this vertex function, and a similar one for the ρ meson, we calculate the electromagnetic observables of this composite Nambu-Goldstone boson, including effects from ρ-meson dominance processes. Our calculation takes the composite structure of the mesons into account. The ρ-meson effects are found to be very small in the pion charge form factor, but substantial in the charge radius. Using the model, predictions are made for γ * π 0 →γ and ρπγ transition form factors

  4. A-dependence of inclusive πsup(+-) meson photoproduction

    International Nuclear Information System (INIS)

    Alanakyan, K.V.; Amaryan, M.D.; Demirchyan, R.A.; Egiyan, K.Sh.; Kocharova, Zh.L.; Ogandjanyan, M.S.; Sharabyan, Yu.G.; Stepanyan, S.G.

    1981-01-01

    The experimental data on A-dependence of photopions in wide energy and angular intervals of secondary PI +- -mesons are discussed. It is shown that if the invariant cross section of photopion production on 12 C, 27 Al, 63 Cu, 118 Sn and 208 Pb nuclei in the γ+A→PI +- +X reaction is represented in the form of f approximately equal to BAsup(n), then in the energy dependence of exponent n one can observe the same singularities as in the analogous hadron processes. The expansion of the angular interval up to 20-160 deg in the laboratory system made it possible to study in detail the nature of these singularities. The attempts are made to explain the observed singularities in the energy dependence n=n(TPI) by taking into account additional (to tne direct process of photoproduction on nuclear nucleons) sources of the inclusive PI-meson production [ru

  5. Theory of the low-energy pion-nucleon interaction

    International Nuclear Information System (INIS)

    Banerjee, M.K.; Cammarata, J.B.

    1978-01-01

    A once-subtracted form of the Low equation for the pion-nucleon scattering amplitude is derived, with partial conservation of axial-vector current used to define the amplitude when one pion is off the mass shell. The static approximation is not made and both the seagull terms and the antinucleon contribution (z graphs) are retained. The theory is applied to calculate the S-wave amplitudes in the elastic scattering region. Good agreement is found with the phase shift fits to the data when we use vertical-barg/sub π/(4M 2 ) vertical-bar = 11.69 and 25.5 MeV for the πN sigma commutator. The implications of this work for the analysis of low-energy elastic scattering of pions form nuclei are discussed. In particular, we point out how this work establishes the presence of a Laplacian term in the pion-nucleus optical potential with a magnitude that is fixed from the value of the sigma commutator

  6. Antibacterial activity of oxytetracycline photoproducts in marine aquaculture's water.

    Science.gov (United States)

    Leal, J F; Henriques, I S; Correia, A; Santos, E B H; Esteves, V I

    2017-01-01

    Oxytetracycline (OTC) is one of the most used antibiotics in aquaculture. The main concern related to its use is the bacterial resistance, when ineffective treatments are applied for its removal or inactivation. OTC photo-degradation has been suggested as an efficient complementary process to conventional methods used in intensive fish production (e.g.: ozonation). Despite this, and knowing that the complete mineralization of OTC is difficult, few studies have examined the antibacterial activity of OTC photoproducts. Thus, the main aim of this work is to assess whether the OTC photoproducts retain the antibacterial activity of its parent compound (OTC) after its irradiation, using simulated sunlight. For that, three Gram-negative bacteria (Escherichia coli, Vibrio sp. and Aeromonas sp.) and different synthetic and natural aqueous matrices (phosphate buffered solutions at different salinities, 0 and 21‰, and three different samples from marine aquaculture industries) were tested. The microbiological assays were made using the well-diffusion method before and after OTC has been exposed to sunlight. The results revealed a clear effect of simulated sunlight, resulting on the decrease or elimination of the antibacterial activity for all strains and in all aqueous matrices due to OTC photo-degradation. For E. coli, it was also observed that the antibacterial activity of OTC is lower in the presence of sea-salts, as demonstrated by comparison of halos in aqueous matrices containing or not sea-salts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. One spin pion asymmetry in d ↑ + A → π+- + X processes near θπ = 90 deg

    International Nuclear Information System (INIS)

    Averichev, G.S.; Agakishev, G.A.; Borzunov, Yu.T.

    1996-01-01

    The results of the measurements of the vector analyzing power of inclusive pions produced in the reactions of polarized deuterons with different (H and C) targets near 90 deg at incident beam momenta from 3 to 9 GeV/c are presented. The large values of the vector analyzing power and the different sings of the π + and π - asymmetries have been observed in the d ↑ + H → π +- +... reactions for a pion momentum in the range 300-350 MeV/c. The results of Monte Carlo simulations indicate the strong influence of the intermediate Δ-resonances on the value and the sing of the analyzing power [ru

  8. Dosimetry and radiobiology of negative pions and heavy ions

    International Nuclear Information System (INIS)

    Raju, M.R.

    1978-01-01

    The depth dose distribution of pion beams has not been found superior to protons. Pion radiation quality at the plateau region is comparable to conventional low-LET radiations, and radiobiology results also indicate RBE values close to unity. In the pion stopping region, the radiation quality increases considerably. Radiobiology data for negative pions at the Bragg peak position clearly indicate the increase in RBE and the reduction in OER. Even at the Bragg peak position, compared to fast neutrons, the average LET of negative pions is lower. Pion radiobiology data have indicated lower RBE values and higher OER values compared to fast neutrons. The radiation quality of fast neutrons is in between that of carbon and neon ions at the peak region and that of neon ions at the plateau is lower than for fast neutrons. The mean LET value for helium ions, even at the distal end of the peak, is lower than for fast neutrons. Dose localization of heavy ions has been found to decrease slowly with increasing charge of the heavy ion. The intercellular contact that protects cells after exposure to low-LET radiations is not detected after exposure to heavy ions. Single and fractionated doses of heavy ions produce dose-response curves for heavy ions having reduced shoulders but similar slopes when compared to gamma rays. Fractionated treatments of heavy ions produce an enhanced effect in the peak region compared to the plateau region and could lead to a substantial gain in therapeutic ratio. The OER for protons was similar to that for x rays. The OER values for negative pions, helium ions, and carbon ions were larger, for neon ions similar, and for argon ions smaller when compared to fast neutrons.Negative pions, helium ions, and carbon ions may be very effective clinically because the radiation quality of these beams is similar to that of the mixed scheme of neutrons and x rays

  9. Double charge exchange of pions on nuclei

    International Nuclear Information System (INIS)

    Dzhibuti, R.I.; Kezerashvili, R.Y.

    1985-01-01

    An analysis is made of the results of experimental and theoretical studies during the last ten years of a unique process: double charge exchange of pions on nuclei. On the one hand, the commissioning of meson factories and the use of new and more accurate experimental methods have led to the accumulation of rich and reliable material for not only light but also medium and heavy nuclei. On the other hand, the development and application of new microscopic theoretical approaches have led to a deepening of our ideas about the mechanism of these exotic reactions at low, intermediate, and high energies. The currently existing methods of theoretical investigation and all possible reaction mechanisms are considered. Particular attention is devoted to double charge exchange of pions on the lightest nuclei, for the theoretical description of which it is possible to use the well-developed methods for investigating few-particle systems. The experimental investigations of double-isobar analog and nonanalog transitions in the reaction of double charge exchange are systematized

  10. Elastic photoproduction of ρ0 mesons at HERA

    International Nuclear Information System (INIS)

    Aid, S.; Andreev, V.; Andrieu, B.

    1995-12-01

    The cross section for the elastic photoproduction of ρ 0 mesons (γp→ρ 0 p) has been measured with the H1 detector at HERA for two average photon-proton centre-of-mass energies of 55 and 187 GeV. The lower energy point was measured by observing directly the ρ 0 decay giving a cross section of 9.1±0.9 (stat.)±2.5 (syst.) μb. The logarithmic slope parameter of the differential cross section, dσ/dt, is found to be 10.9±2.4 (stat.)±1.1 (syst.) GeV -2 . The ρ 0 decay polar angular distribution is found to be consistent with s-channel helicity conservation. The higher energy cross section was determined from analysis of the lower part of the hadronic invariant mass spectrum of diffractive photoproduction and found to be 13.6±0.8 (stat.)±2.4 (syst.) μb. (orig.)

  11. Study of ultraviolet light-induced DNA damage and repair: the role of the (6-4) photoproduct

    International Nuclear Information System (INIS)

    Franklin, W.A.

    1985-01-01

    Ultraviolet light induces lethal, mutagenic, and carcinogenic effects to cells. These effects are a result of the induction of photoproducts in the cellular DNA. One class of photoproducts was found as alkaline labile lesions in DNA, and it was proposed that such lesions were precursor products to the 6,4'-[pyrimidin-2'-one]-pyrimidine class of photoproducts that have been previously shown to occur in UV light-irradiated DNA. Using a series of dinucleotide compounds, the precursor compounds were isolated, and were demonstrated to be alkaline labile. These products were named the UV light-induced pyrimidine-pyrimidone (6-4) photoproducts, and their chemistry of formation in dinucleotides and DNA was studied. The formation of these photoproducts under conditions of chemical photosensitization was also measured. The most abundant of the (6-4) photoproducts is the thymine-cytosine (6-4) product, and the molecular structure of this compounds was determined by the use of infrared spectroscopy, proton NMR, and mass spectroscopy. The (6-4) products have been recently shown to be the major UV light-induced premutagenic lesions in E. coli. In E. coli, the repair of the (6-4) products is under the control of the uvrABC excision pathway. The rate of removal of (6-4) products was measured in a series of human cells lines. The rate of removal of (6-4) products from the DNA of a xeroderma pigmentosum complementation group A cell line was nearly that of the normal cells, yet these cells are unable to excise cyclobutane pyrimidine dimers. These results suggest that the removal of cyclobutane pyrimidine dimers and (6-4) products may be controlled by separate enzymatic pathways

  12. Photoproduction of Mesons off Light Nuclei

    International Nuclear Information System (INIS)

    Keshelashvili, Irakli

    2011-01-01

    During the last few years, a series of experiments has been done at the ELSA accelerator in Bonn with the Crystal Barrel/TAPS setup and at the MAMI accelerator in Mainz with the Crystal Ball/TAPS setup. Photoproduction of light mesons off the deuteron and 3 He-nuclei has been studied in detail. We will report some of the most interesting results.A completely unexpected finding, is the pronounced structure in the excitation function of the γn → nη reaction around 1 GeV, which has no counterpart for the proton. Recent measurements at GRAAL, Sendai, ELSA [1] and MAMI estimate it's width below 50 MeV, which would be extremely narrow for a nucleon resonance at this excitation energy. In the experiment with the 3 He target, special attention was given to the threshold behavior of the γHe 3 reactions in view of possible indications for the formation of (quasi-)bound η-nucleus states, so-called η-mesic nuclei. A very strong threshold enhancement of coherent η-photoproduction off 3 He was found. In a new experiment, this reaction was measured with much better statistical accuracy compared to an earlier experiment at MAMI-B using the TAPS detector [2].

  13. Theoretical contributions to coherent pion production in subthreshold and relativistic heavy-ion collisions

    International Nuclear Information System (INIS)

    Deutchman, P.A.; Norbury, J.W.; Townsend, L.W.

    1986-01-01

    The analysis results from a microscopic calculation for pion production in heavy-ion collisions at intermediate to relativistic energies both above and below pion threshold are presented and the most important terms that contribute to the pion spectrum are determined. The energy dependence and the effects on the pion spectrum due to the various parameters in the theory are examined. The model is applied to coherent pion-production in 16 O + 12 C collisions. (orig.)

  14. Pion content of the nucleon in polarized semi-inclusive DIS

    Energy Technology Data Exchange (ETDEWEB)

    Melnitchouk, W. [Univ. of Regensburg (Germany); Thomas, A.W. [Univ. of Adelaide (Australia)

    1994-04-01

    An explicit pionic component of the nucleon may be identified by measuring polarized {Delta}{sup ++} fragments produced in deep-inelastic scattering (DIS) off polarized protons. The pion-exchange model predicts highly correlated polarizations of the {Delta}{sup ++} and target proton, in marked contrast with the competing diquark fragmentation process.

  15. Coupled channel theory of pion--deuteron reaction applied to threshold scattering

    International Nuclear Information System (INIS)

    Mizutani, T.; Koltun, D.S.

    1977-01-01

    Scattering and absorption of pions by a nuclear target are treated together in a coupled channel theory. The theory is developed explicitly for the problem of pion scattering and absorption by a deuteron. The equations are presented in terms of the integral equations of three-body scattering theory. The method is then applied in an approximate from to calculate the contribution of pion absorption to the scattering length for pion--deuteron scattering. The sensitivity of the calculated results to the model assumptions and approximations is investigated

  16. Neutral Pion Rejection at L2 using the CMS Endcap Preshower

    CERN Document Server

    Kyriakis, Aristotelis; Loukas, Demetrios; Mousa, Jehad; Seez, Christopher

    1999-01-01

    Applying a general Artificial Neural Network approach, we have examined the possibility of neutral pion rejection at the Level 2 Trigger stage ( L2) principally using information from the CMS Endcap Preshower. We have studied both pion/photon and pion/electron discrimination. For L2 the hope was to achieve some useful pion/electron discrimination for a high electron efficiency. For a single electron/photon efficiency of 95% the results show that no useful rejection of neutral pions against electrons/photons can be obtained using this algorithm alone, due to the presence of tracker material. If the efficiency is lowered or information from the tracker is available, the rejection can increase dramatically. This will be the case for off-line analyses.

  17. Measurement of Collins asymmetries in inclusive production of charged pion pairs in e(+)e(-) annihilation at BABAR

    NARCIS (Netherlands)

    Lees, J. P.; Poireau, V.; Tisserand, V.; Grauges, E.; Palano, A.; Eigen, G.; Stugu, B.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Schroeder, T.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; So, R. Y.; Khan, A.; Blinov, V. E.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Kravchenko, E. A.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Yushkov, A. N.; Kirkby, D.; Lankford, A. J.; Mandelkern, M.; Dey, B.; Gary, J. W.; Long, O.; Vitug, G. M.; Campagnari, C.; Sevilla, M. Franco; Hong, T. M.; Kovalskyi, D.; Richman, J. D.; West, C. A.; Eisner, A. M.; Lockman, W. S.; Schumm, B. A.; Seiden, A.; Chao, D. S.; Echenard, B.; Flood, K. T.; Hitlin, D. G.; Ongmongkolkul, P.; Andreassen, R.; Huard, Z.; Meadows, B. T.; Pushpawela, B. G.; Sokoloff, M. D.; Sun, L.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Nauenberg, U.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Spaan, B.; Schwierz, R.; Bernard, D.; Verderi, M.; Playfer, S.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cibinetto, G.; Fioravanti, E.; Garzia, I.; Luppi, E.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Martellotti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Bhuyan, B.; Prasad, V.; Morii, M.; Adametz, A.; Uwer, U.; Lacker, H. M.; Dauncey, P. D.; Mallik, U.; Cochran, J.; Meyer, W. T.; Prell, S.; Gritsan, A. V.; Arnaud, N.; Davier, M.; Derkach, D.; Grosdidier, G.; Le Diberder, F.; Lutz, A. M.; Malaescu, B.; Roudeau, P.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Coleman, J. P.; Fry, J. R.; Gabathuler, E.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Di Lodovico, F.; Sacco, R.; Cowan, G.; Bougher, J.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Griessinger, K.; Hafner, A.; Prencipe, E.; Schubert, K. R.; Barlow, R. J.; Lafferty, G. D.; Behn, E.; Cenci, R.; Hamilton, B.; Jawahery, A.; Roberts, D. A.; Cowan, R.; Dujmic, D.; Sciolla, G.; Cheaib, R.; Patel, P. M.; Robertson, S. H.; Biassoni, P.; Neri, N.; Palombo, F.; Cremaldi, L.; Godang, R.; Sonnek, P.; Summers, D. J.; Simard, M.; Taras, P.; De Nardo, G.; Monorchio, D.; Onorato, G.; Sciacca, C.; Martinelli, M.; Raven, G.; Jessop, C. P.; LoSecco, J. M.; Honscheid, K.; Kass, R.; Brau, J.; Frey, R.; Sinev, N. B.; Strom, D.; Torrence, E.; Feltresi, E.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simi, G.; Simonetto, F.; Stroili, R.; Akar, S.; Ben-Haim, E.; Bomben, M.; Bonneaud, G. R.; Briand, H.; Calderini, G.; Chauveau, J.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Sitt, S.; Biasini, M.; Manoni, E.; Pacetti, S.; Rossi, A.; Angelini, C.; Batignani, G.; Bettarini, S.; Carpinelli, M.; Casarosa, G.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Oberhof, B.; Paoloni, E.; Perez, A.; Rizzo, G.; Walsh, J. J.; Pegna, D. Lopes; Olsen, J.; Smith, A. J. S.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Gioi, L. Li; Piredda, G.; Buenger, C.; Grueberg, O.; Leddig, T.; Voss, C.; Waldi, R.; Adye, T.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; de Monchenault, G. Hamel; Vasseur, G.; Yeche, Ch.; Anulli, F.; Aston, D.; Bard, D. J.; Benitez, J. F.; Cartaro, C.; Convery, M. R.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Ebert, M.; Field, R. C.; Fulsom, B. G.; Gabareen, A. M.; Graham, M. T.; Hast, C.; Innes, W. R.; Kim, P.; Kocian, M. L.; Leith, D. W. G. S.; Lewis, P.; Lindemann, D.; Lindquist, B.; Luitz, S.; Luth, V.; Lynch, H. L.; MacFarlane, D. B.; Muller, D. R.; Neal, H.; Nelson, S.; Perl, M.; Pulliam, T.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Snyder, A.; Su, D.; Sullivan, M. K.; Va'vra, J.; Wisniewski, W. J.; Wittgen, M.; Wright, D. H.; Wulsin, H. W.; Ziegler, V.; Park, W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Randle-Conde, A.; Sekula, S. J.; Bellis, M.; Burchat, P. R.; Miyashita, T. S.; Puccio, E. M. T.; Alam, M. S.; Ernst, J. A.; Gorodeisky, R.; Guttman, N.; Peimer, D. R.; Soffer, A.; Spanier, S. M.; Ritchie, J. L.; Ruland, A. M.; Schwitters, R. F.; Wray, B. C.; Izen, J. M.; Lou, X. C.; Bianchi, F.; De Mori, F.; Filippi, A.; Gamba, D.; Zambito, S.; Lanceri, L.; Vitale, L.; Martinez-Vidal, F.; Oyanguren, A.; Villanueva-Perez, P.; Ahmed, H.; Albert, J.; Banerjee, Sw.; Bernlochner, F. U.; Choi, H. H. F.; Kowalewski, R.; Lewczuk, M. J.; Lueck, T.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Tasneem, N.; Gershon, T. J.; Harrison, P. F.; Latham, T. E.; Band, H. R.; Dasu, S.; Pan, Y.; Prepost, R.

    2014-01-01

    We present measurements of Collins asymmetries in the inclusive process e+e−→ππX, where π stands for charged pions, at a center-of-mass energy of 10.6 GeV. We use a data sample of 468  fb−1 collected by the BABAR experiment at the PEP-II B factory at SLAC, and consider pairs of charged pions

  18. Low-energy photo- and electroproduction for physical pions

    International Nuclear Information System (INIS)

    MacMullen, J.T.

    1979-02-01

    The background resonance Δ(1230), Nsup(*)(1520), Nsup(*)(1470) and Nsup(*)(1535)pion and axial-vector amplitudes are first calculated in the soft pion and on-shell configuration, respectively. Then a comparison is made with the usual soft pion theorems and on-shell low-energy expansions of current algebra as worked out in the previous paper. The agreement is good and we also deduce a nucleon dipole form factor axial-vector mass of msub(A)approximately equal to 1,23 GeV. Finally an approximate value for the non-strange current quark mass of m equal to 0,64 +- 1,11μ is extracted from the data

  19. Pion condensation in cold dense matter and neutron stars

    International Nuclear Information System (INIS)

    Haensel, P.; Proszynski, M.

    1982-01-01

    We study possible influence, on the neutron star structure, of a pion condensation occurring in cold dense matter. Several equations of state with pion-condensed phase are considered. The models of neutron stars are calculated and confronted with existing observational data on pulsars. Such a confrontation appears to rule out the models of dense matter with an abnormal self-bound state, and therefore it seems to exclude the possibility of the existence of abnormal superheavy neutron nuclei and abnormal neutron stars with a liquid pion-condensed surface

  20. Coherent pion production induced by protons and light ions

    International Nuclear Information System (INIS)

    Fernandez de Cordoba, P.; Oset, E.; Vicente-Vacas, M.J.

    1995-01-01

    We study coherent pion production by means of the (p,n) and (He,t) reactions on different nuclei and at different energies of the projectile. Energy and angular distributions are calculated. The angular distributions are rather narrow along the direction of the momentum transfer, particularly in heavy nuclei. The reaction is sensitive to the longitudinal part of the elementary NN→NΔ interaction. It also provides a new tool to obtain information on the pion-nuclear interaction, complementary to that offered by reactions with real pions. (orig.)

  1. Correlations of neutral pions in ultrarelativistic heavy ion collisions

    International Nuclear Information System (INIS)

    Peitzmann, T.; Beckmann, P.; Berger, F.; Glewing, G.; Dragon, L.; Glasow, R.; Kampert, K.H.; Loehner, H.; Purschke, M.; Santo, R.; Albrecht, R.; Bock, R.; Claesson, G.; Gutbrod, H.H.; Kolb, B.W.; Lund, I.; Schmidt, H.R.; Siemiarczuk, T.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Lee, I.Y.; Obenshain, F.E.; Plasil, F.; Soerensen, S.P.; Young, G.R.; Eklund, A.; Garpman, S.; Gustafsson, H.A.; Idh, J.; Kristiansson, P.; Oskarsson, A.; Otterlund, I.; Persson, S.; Stenlund, E.; Franz, A.; Poskanzer, A.M.; Ritter, H.G.

    1989-01-01

    Correlations of 4 photons representing neutral pions have been studied in ultrarelativistic heavy ion collisions. Data were taken in the WA80 experiment at the CERN-SPS with a 200 A GeV oxygen beam. The π 0 are detected via their decay photons with a high-granularity lead glass array. Special features of interferometry using neutral pions will be discussed. The extracted preliminary parameters for high p T pions emitted near midrapidity in O+Au collisions lead to rather small effective source sizes. (orig.)

  2. Pion-induced damage in silicon detectors

    CERN Document Server

    Bates, S; Glaser, M; Lemeilleur, F; León-Florián, E; Gössling, C; Kaiser, B; Rolf, A; Wunstorf, R; Feick, H; Fretwurst, E; Lindström, G; Moll, Michael; Taylor, G; Chilingarov, A G

    1995-01-01

    The damage induced by pions in silicon detectors is studied for positive and negative pions for fluence up to 10(14)cm-2 and 10(13) cm-2 respectively. Results on the energy dependence of the damage in the region of 65-330 MeV near to the  resonance are presented. The change in detector characteristics such as leakage current, charge collection efficiency and effective impurity concentration including long-term annealing effects have been studied. Comparisons to neutron and proton-induced damage are presented and discussed.

  3. Photon flux determination for a precision measurement of the neutral pion lifetime

    Energy Technology Data Exchange (ETDEWEB)

    Teymurazyan, Aram [Univ. of Kentucky, Lexington, KY (United States)

    2008-01-01

    The Jefferson Lab Hall B PrimEx Collaboration is using tagged photons to perform a 1.4% level measurement of the absolute cross section for the photo-production of neutral pions in the Coulomb field of a nucleus as a test of Chiral Perturbation Theory. Such a high precision pushes the limits of the photon tagging technique in regards to the determination of the absolute photon flux. A multifaceted approach to this problem has included measuring the absolute tagging ratios with a Total Absorption Counter (TAC) as well as relative tagging ratios with a Pair Spectrometer (PS), and determining the rate of the tagging counters using multi-hit TDC's and a clock trigger. This enables the determination of the absolute tagged photon flux for the PrimEx experiment with uncertainty of ~ 1.0%, which is unprecedented. In view of the stringent constraints on the required precision of the photon flux for this experiment, periodicmeasurements of the pair production cross section were performed throughout the run. In these measurements, both the photon energy and flux were determined by the Jefferson Lab Hall B tagger, and the electron-positron pairs were swept by a magnetic field and detected in the new 1728 channel hybrid calorimeter (HyCal). The pair production crosssection was extracted with an uncertainty of ~ 2%, producing an agreement with theoretical calculations at the level of ~ 2%. This measurement provided a unique opportunity to verify the photon flux determination procedure for the PrimEx experiment.

  4. Suppression factors in diffractive photoproduction of dijets

    International Nuclear Information System (INIS)

    Klasen, Michael; Kramer, Gustav

    2010-06-01

    After new publications of H1 data for the diffractive photoproduction of dijets, which overlap with the earlier published H1 data and the recently published data of the ZEUS collaboration, have appeared, we have recalculated the cross sections for this process in next-to-leading order (NLO) of perturbative QCD to see whether they can be interpreted consistently. The results of these calculations are compared to the data of both collaborations. We find that the NLO cross sections disagree with the data, showing that factorization breaking occurs at that order. If direct and resolved contributions are both suppressed by the same amount, the global suppression factor depends on the transverse-energy cut. However, by suppressing only the resolved contribution, also reasonably good agreement with all the data is found with a suppression factor independent of the transverse-energy cut. (orig.)

  5. The Λ(1520) photoproduction from proton

    International Nuclear Information System (INIS)

    He, Jun

    2014-01-01

    The Λ(1520) photoproduction from proton target is investigated within the effective Lagrangian method and well compared with the experimental data. The D 13 state N(2120) plays the most important role among the nucleon resonances. Besides N(2120), a nucleon resonance [5/2 - ] 2 (2080) predicted by the constituent quark model is found also important to reproduce the experimental data. Other nucleon resonances give negligible contributions in the channel considered in this work. (author)

  6. Evidence for pion absorption on four nucleons

    International Nuclear Information System (INIS)

    Rzehorz, B.; Backenstoss, G.; Dzemidzic, M.; Zagreb Univ.; Furic, M.; Zagreb Univ.; Hoffart, A.; Petkovic, T.; Zagreb Univ.; Ullrich, H.; Weyer, H.J.; Weiser, D.; Wildi, M.

    1996-01-01

    Experimental spectra from the coincident detection of three nucleons after the pion absorption in 4 He are displayed. The presence of a mechanism with four nucleons participating in the absorption process is made obvious. The total cross-sections for this absorption mode are: σ 4NA abs =(1.0±0.2)mb at T π =120 MeV and σ 4NA abs =(2.18± 0.65) mb at T π =210 MeV. (orig.)

  7. Aspects of the heavy-quark photoproduction in the semihard approach

    International Nuclear Information System (INIS)

    Mariotto, C. Brenner; Ducati, M.B. Gay; Machado, M.V.T.

    2002-01-01

    In this contribution we report on the calculations of heavy-quark photoproduction using the K p erpendicular to-factorization (semihard) approach, emphasizing the results obtained with the phenomenological saturation model. (author)

  8. Recent developments in the understanding of pion-nucleus scattering

    International Nuclear Information System (INIS)

    Johnson, M.B.

    1983-01-01

    A development of the theory of pion-nucleus scattering is given in a field theoretical framework. The theory is designed to describe pion elastic scattering and single- and double-charge exchange to isobaric analog states. An analysis of recent data at low and resonance energies is made. Strong modifications to the simple picture of the scattering as a succession of free pion-nucleon interactions are required in order to understand the data. The extent to which the experiment is understood in terms of microscopic theory is indicated. 71 references

  9. Two-arm semiconductor spectrometer for charged particles for the investigation of absorption by nuclei of stopped negative pions

    International Nuclear Information System (INIS)

    Gornov, M.G.; Gurov, Yu.B.; Lukin, A.S.; Morokhov, P.V.; Pechkurov, V.A.; Pichugin, A.P.; Saveliev, V.I.; Shafigullin, R.R.; Sergeev, F.M.; Khomutov, A.A.; Oganesian, K.O.; Osipenko, B.P.; Sandukovsky, V.G.

    1984-01-01

    A two-arm semiconductor spectrometer for the detection of secondary charged particles, such as p, d, t, 3 He, 4 He and of their correlations in the process of stopped pion absorption by nuclei is described. The spectrometer consists of two telescopes of Si-detectors with a sensitive surface of 800 mm 2 , two semiconductor detectors as monitors and the 'live' target, a silicon surface barrier detector. The number of semiconductor detectors is 19. A technique for pion stop selection in thin targets is described. The problem of particle identification and of measurements of their energy with the help of a multicrystal semiconductor telescope is discussed. The technique provides an absolute normalization of spectra. The 'alive' target helps to obtain more information on the process of pion absorption by Si-nuclei. (orig.)

  10. Exclusive channels in semi-inclusive production of pions and kaons

    International Nuclear Information System (INIS)

    Markus Diehl; Wolfgang Kugler; Andreas Schaefer; Christian Weiss

    2005-01-01

    We investigate the role of exclusive channels in semi-inclusive electroproduction of pions and kaons. Using the QCD factorization theorem for hard exclusive processes we evaluate the cross sections for exclusive pseudoscalar and vector meson production in terms of generalized parton distributions and meson distribution amplitudes. We investigate the uncertainties arising from the modeling of the nonperturbative input quantities. Combining these results with available experimental data, we compare the cross sections for exclusive channels to that obtained from quark fragmentation in semi-inclusive deep inelastic scattering. We find that rho0 production is the only exclusive channel with significant contributions to semi-inclusive pion production at large z and moderate Q2. The corresponding contribution to kaon production from the decay of exclusively produced phi and Kstar is rather small

  11. Exclusive channels in semi-inclusive production of pions and kaons

    Energy Technology Data Exchange (ETDEWEB)

    Markus Diehl; Wolfgang Kugler; Andreas Schaefer; Christian Weiss

    2005-06-01

    We investigate the role of exclusive channels in semi-inclusive electroproduction of pions and kaons. Using the QCD factorization theorem for hard exclusive processes we evaluate the cross sections for exclusive pseudoscalar and vector meson production in terms of generalized parton distributions and meson distribution amplitudes. We investigate the uncertainties arising from the modeling of the nonperturbative input quantities. Combining these results with available experimental data, we compare the cross sections for exclusive channels to that obtained from quark fragmentation in semi-inclusive deep inelastic scattering. We find that rho0 production is the only exclusive channel with significant contributions to semi-inclusive pion production at large z and moderate Q2. The corresponding contribution to kaon production from the decay of exclusively produced phi and Kstar is rather small.

  12. Negative pion capture in chemical compounds

    International Nuclear Information System (INIS)

    Butsev, V.S.; Chultem, D.; Gavrilov, Yu.K.; Ganzorig, Dz.; Norseev, Yu.V.; Presperin, V.

    1976-01-01

    The results are reported of an experiment of determination of the probability of capture of resting negative pions by iodine nuclei in alkali metal iodides (LiI, NaI, KI, RbI, CsI). The yield of an isomer sup(116m)(Sb/8 - ) with a high spin number, formed in the reaction 127 I(π - , lp 10n) allows to determine the relative probability of the nuclear capture of pions in the above compounds. The results obrained are compared with the predictions of the Fermi-Teller Z-law

  13. Calculation of the pion-nucleon double spectral functions and applications

    International Nuclear Information System (INIS)

    Grether, D.

    1986-01-01

    In the present thesis the latest results from pion-pion and pion-nucleon phase analyses are applied in order to calculate the pion-nucleon double spectral functions which belong to the elastic unitarity in the t-channel. The equivalence of the partial wave projection of these spectral functions in the s-channel with the elastic t-channel unitarity is extensively discussed. After we summarize the aspects of the pion-nucleon system seeming in this connection interesting we discuss the Mandelstam method for the calculation of the spectral functions by means of the elastic t-channel unitarity as well as the applied input and present the results. Thereafter we use these results in order to calculate by means of a fixed t-channel dispersion relation the real parts of the t-channel cuts. Partial wave projections into the t-channel are proved as equivalent to the elastic t-channel unitarity. We study the compatibility of the asymptotic behaviour of the spectral functions relative to the energy with current Regge pole models. Finally we use our results in order to calculate the pion-nucleon partial waves by means of their Froissart-Gribov representations which follow from their analyticity at fixed energy. (orig./HSI) [de

  14. Beam asymmetry Σ for π0 and η photoproduction on the proton at GlueX

    Science.gov (United States)

    Zhang, Zhenyu; GlueX Collaboration

    2016-09-01

    Measurements of meson photoproduction at high energies began almost 50 years ago with bubble chamber experiments at SLAC, DESY, and Cambridge. These data have been successfully described through Regge theory in terms of t-channel quasi-particle exchange. High statistics measurements of pseudoscalar meson photoproduction at GlueX, using the 9 GeV linearly-polarized, tagged photon beam in Jefferson Lab's Hall D, will provide important new constraints on these Regge models. These measurements will test our understanding of the photoproduction mechanism at high energy, which is a necessary first step toward the broader meson spectroscopy program at GlueX. Through finite energy sum rules, these measurements can also impose new constraints on the extraction of nucleon resonances from low energy photoproduction data. In this talk, preliminary results for the linearly polarized photon beam asymmetry Σ for the exclusive reactions γp -> pπ0 and γp -> pη will be presented. These are the first measurements of the η beam asymmetry at these energies. Supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and the China Scholarship Council No. 201506275156.

  15. Pion production in high energy heavy ion collisions

    International Nuclear Information System (INIS)

    Wolf, K.L.; Bock, R.; Brockmann, R.

    1984-01-01

    Experimental data for heavy ion pion production reactions are compared with the predictions of a number of versions of cascade models. Pion suppression effects observed in the experimental data are fit by introducing refinements into cascade theory. Impact parameter adjustment, off-shell effects on the potential and perturbations due to nuclear matter are considered

  16. Production of pions and anomalous projectile fragments in heavy ion collisions

    International Nuclear Information System (INIS)

    Noren, B.

    1988-05-01

    Results are presented from investigations of the mean free path (mfp) of multiply charged fragments, produced by 1.8 A GeV argon nuclei. The mfp's have been studied experimentally, and no dependence of the mfp on the distance from the preceeding collision is observed. In a Monte Carlo simulation, the mfp estimators are investigated for different statistics, with or without an enhanced reaction probability. Intermediate energy heavy ion collisions have been studied using the carbon beam produced at the CERN SC-accelerator. Cross-sections for pion + and pion - have been measured over a wide range of angles and targets. Also, coincidence measurements with projectile-like fragments have been performed. The pion - /pion + ratio has been studied for C+Li, C+C, C+Pb, C+ 116 Sn and C+ 124 Sn. Inconsistencies in the target mass dependence of the pion yield disappear if a correction for reabsorption in the target nucleus is included. The projectile breakup is significantly stronger for pion producing collisions than for the average collision, thus indicating a much stronger abundance of central collisions. (With 32 refs.) (author)

  17. UV-visible degradation of boscalid--structural characterization of photoproducts and potential toxicity using in silico tests.

    Science.gov (United States)

    Lassalle, Yannick; Kinani, Aziz; Rifai, Ahmad; Souissi, Yasmine; Clavaguera, Carine; Bourcier, Sophie; Jaber, Farouk; Bouchonnet, Stéphane

    2014-05-30

    Boscalid is a carboximide fungicide mainly used for vineyard protection as well as for tomato, apple, blueberry and various ornamental cultivations. The structural elucidation of by-products arising from the UV-visible photodegradation of boscalid has been investigated by gas chromatography/multi-stage mass spectrometry (GC/MS(n) ) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) couplings. The potential toxicities of transformation products were estimated by in silico calculations. Aqueous solutions of boscalid were irradiated up to 150 min in a self-made reactor equipped with a mercury lamp. Analyses were carried out using a gas chromatograph coupled with an ion trap mass spectrometer operated in both electron ionization (EI) and chemical ionization (CI) modes and a liquid chromatograph coupled with a quadrupole time-of-flight (Q-TOF) mass spectrometer operated in electrospray ionization (ESI) mode. Multiple-stage collision-induced dissociation (CID) experiments were performed to establish dissociation pathways of ions. The QSAR (Quantitative Structure-Activity Relationship) T.E.S.T. program allowed the estimation of the toxicities of the by-products. Eight photoproducts were investigated. Chemical structures were proposed not only on the interpretation of multi-stage CID experiments, but also on kinetics data. These structures led us to suggest photodegradation pathways. Three photoproducts were finally detected in Lebanon in a real sample of grape leaves for which routine analysis had led to the detection of boscalid at 4 mg kg(-1). With one exception, the structures proposed for the photoproducts on the basis of mass spectra interpretation have not been reported in previous studies. In silico toxicity predictions showed that two photoproducts are potentially more toxic than the parent compound considering oral rat LD50 while five photoproducts may induce mutagenic toxicity. With the exception of one compound, all photoproducts may

  18. UV-visible degradation of boscalid- structural characterization of photoproducts and potential toxicity using in silico tests

    International Nuclear Information System (INIS)

    Rifai, A.; Jaber, F.; Lassalle, Y.; Kinani, A.; Souissi, Y.; Clavaguera, C.; Bourcier, S.; Bouchonnet, St.

    2014-01-01

    RATIONALE: Boscalid is a carboximide fungicide mainly used for vineyard protection as well as for tomato, apple, blueberry and various ornamental cultivations. The structural elucidation of by-products arising from the UV-visible photodegradation of boscalid has been investigated by gas chromatography/multi-stage mass spectrometry (GC/MSn) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) couplings. The potential toxicities of transformation products were estimated by in silico calculations. METHODS: Aqueous solutions of boscalid were irradiated up to 150 min in a self-made reactor equipped with a mercury lamp. Analyses were carried out using a gas chromatograph coupled with an ion trap mass spectrometer operated in both electron ionization (EI) and chemical ionization (CI) modes and a liquid chromatograph coupled with a quadrupole time-of-flight (Q-TOF) mass spectrometer operated in electrospray ionization (ESI) mode. Multiple-stage collision-induced dissociation (CID) experiments were performed to establish dissociation pathways of ions. The QSAR (Quantitative Structure-Activity Relationship) T.E.S.T. program allowed the estimation of the toxicities of the by-products. RESULTS: Eight photoproducts were investigated. Chemical structures were proposed not only on the interpretation of multi-stage CID experiments, but also on kinetics data. These structures led us to suggest photodegradation pathways. Three photoproducts were finally detected in Lebanon in a real sample of grape leaves for which routine analysis had led to the detection of boscalid at 4 mg kg1. CONCLUSIONS: With one exception, the structures proposed for the photoproducts on the basis of mass spectra interpretation have not been reported in previous studies. In silico toxicity predictions showed that two photoproducts are potentially more toxic than the parent compound considering oral rat LD50 while five photoproducts may induce mutagenic toxicity. With the exception of one compound

  19. Photoproduction of events with rapidity gaps between jets with ZEUS at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, P.D.

    2006-11-15

    Cross sections for the photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 38.6 pb{sup -1}. Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E{sup CUT}{sub T}. The data show a clear excess above the predictions of standard photoproduction models. Models which include color-singlet exchange are able to describe the data. (orig.)

  20. Photoproduction of events with rapidity gaps between jets with ZEUS at HERA

    International Nuclear Information System (INIS)

    Ryan, P.D.

    2006-11-01

    Cross sections for the photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 38.6 pb -1 . Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value E CUT T . The data show a clear excess above the predictions of standard photoproduction models. Models which include color-singlet exchange are able to describe the data. (orig.)

  1. Dynamical chiral symmetry breaking and pion decay constant

    International Nuclear Information System (INIS)

    Gogohia, V.Sh.; Kluge, Gy.

    1991-08-01

    Flavour non-singlet, chiral axial-vector Ward-Takahashi identity is investigated in the framework of dynamical chiral symmetry breaking. The use of the condition of stationarity for the bound-state amplitude is proposed in order to fully determine this quantity and the regular piece of the corresponding axial vertex. This makes it possible to express the pion decay constant in terms of the quark propagator variables only. An exact expression was found for the pion decay constant in current algebra and in Jackiw-Johnson representation as well. We also find a new expression for the pion decay constant in the Pagels-Stokar-Cornwall variables within the framework of Jackiw-Johnson representation. (author) 22 refs.; 2 figs

  2. Pions to Quarks

    Science.gov (United States)

    Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian

    2009-01-01

    Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the

  3. Carbon monoxide apparent quantum yields and photoproduction in the Tyne estuary

    Directory of Open Access Journals (Sweden)

    A. Stubbins

    2011-03-01

    Full Text Available Carbon monoxide (CO apparent quantum yields (AQYs are reported for a suite of riverine, estuarine and sea water samples, spanning a range of coloured dissolved organic matter (CDOM sources, diagenetic histories, and concentrations (absorption coefficients. CO AQYs were highest for high CDOM riverine samples and almost an order of magnitude lower for low CDOM coastal seawater samples. CO AQYs were between 47 and 80% lower at the mouth of the estuary than at its head. Whereas, a conservative mixing model predicted only 8 to 14% decreases in CO AQYs between the head and mouth of the estuary, indicating that a highly photoreactive pool of terrestrial CDOM is lost during estuarine transit. The CDOM absorption coefficient (a at 412 nm was identified as a good proxy for CO AQYs (linear regression r2 > 0.8; n = 12 at all CO AQY wavelengths studied (285, 295, 305, 325, 345, 365, and 423 nm and across environments (high CDOM river, low CDOM river, estuary and coastal sea. These regressions are presented as empirical proxies suitable for the remote sensing of CO AQYs in natural waters, including open ocean water, and were used to estimate CO AQY spectra and CO photoproduction in the Tyne estuary based upon annually averaged estuarine CDOM absorption data. A minimum estimate of annual CO production was determined assuming that only light absorbed by CDOM leads to the formation of CO and a maximum limit was estimated assuming that all light entering the water column is absorbed by CO producing photoreactants (i.e. that particles are also photoreactive. In this way, annual CO photoproduction in the Tyne was estimated to be between 0.99 and 3.57 metric tons of carbon per year, or 0.004 to 0.014% of riverine dissolved organic carbon (DOC inputs to the estuary. Extrapolation of CO photoproduction rates to estimate total DOC photomineralisation indicate that less than 1% of DOC inputs are removed via photochemical processes during

  4. Pion in a box

    International Nuclear Information System (INIS)

    Bietenholz, W.; Rakow, P.E.L.; Schierholz, G.; Regensburg Univ.

    2010-02-01

    The residual mass of the pion in a finite spatial box at vanishing quark masses is computed with two flavors of dynamical clover fermions. The result is compared with predictions of chiral perturbation theory in the δ regime. (orig.)

  5. Pion double charge exchange

    International Nuclear Information System (INIS)

    Cooper, M.D.

    1978-01-01

    The pion double charge exchange data on the oxygen isotopes is reviewed and new data on 9 Be, 12 C, 24 Mg, and 28 Si are presented. Where theoretical calculations exist, they are compared to the data. 9 references

  6. Low-energy pion-nucleon scattering

    International Nuclear Information System (INIS)

    Gibbs, W.R.; Ai, L.; Kaufmann, W.B.

    1998-01-01

    An analysis of low-energy charged pion-nucleon data from recent π ± p experiments is presented. From the scattering lengths and the Goldberger-Miyazawa-Oehme (GMO) sum rule we find a value of the pion-nucleon coupling constant of f 2 =0.0756±0.0007. We also find, contrary to most previous analyses, that the scattering volumes for the P 31 and P 13 partial waves are equal, within errors, corresponding to a symmetry found in the Hamiltonian of many theories. For the potential models used, the amplitudes are extrapolated into the subthreshold region to estimate the value of the Σ term. Off-shell amplitudes are also provided. copyright 1998 The American Physical Society

  7. Time dependence of the masses of the pions

    Energy Technology Data Exchange (ETDEWEB)

    Boscoverde, Lello [IdFP, Garching (Germany)

    2013-07-01

    Recent work in Eddingtonian cosmology has demonstrated the relation of the visible mass of the universe to the spacial extent of the pions. Building on this finding, we conclude the masses of the pions themselves are dependent on the age of the universe. We present the previous work in this field as well as our new calculations.

  8. Quark Fragmentation to Pions in an Effective Chiral Theory

    Directory of Open Access Journals (Sweden)

    Yazaki K.

    2010-04-01

    Full Text Available A description of fragmentation functions which satisfy the momentum and isospin sum rules is presented in an effective chiral quark theory of QCD. We concentrate on the pion fragmentation function, taking into account cascade-like processes in a generalized jet-model approach. Numerical results obtained in this NJL-jet model are presented and compared to empirical parametrizations.

  9. Baryon magnetic moments in the quark model and pion cloud contributions

    International Nuclear Information System (INIS)

    Sato, Toshiro; Sawada, Shoji

    1981-01-01

    Baryon magnetic moment is studied paying attention to the effects of pion cloud which is surrounding the 'bare' baryon whose magnetic moment is given by the quark model with broken SU(6) symmetry. The precisely measured nucleon magnetic moments are reproduced by the pion cloud contributions from the distance larger than 1.4 fm. The effects of pion cloud on the hyperon magnetic moments are also discussed. It is shown that the pion cloud contributions largely reduce the discrepancies between the quark model predictions and the recent accurate experimental data on the hyperon magnetic moments. (author)

  10. Pion structure function from leading neutron electroproduction and SU(2) flavor asymmetry

    Energy Technology Data Exchange (ETDEWEB)

    McKenney, Joshua R. [North Carolina State Univ., Raleigh, NC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Univ. of North Carolina, Chapel Hill, NC (United States); Sato Gonzalez, Nobuo; Melnitchouk, Wally [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Ji, Chueng-Ryong [North Carolina State Univ., Raleigh, NC (United States)

    2016-03-01

    We examine the efficacy of pion exchange models to simultaneously describe leading neutron electroproduction at HERA and the $\\bar{d}-\\bar{u}$ flavor asymmetry in the proton. A detailed $\\chi^2$ analysis of the ZEUS and H1 cross sections, when combined with constraints on the pion flux from Drell-Yan data, allows regions of applicability of one-pion exchange to be delineated. The analysis disfavors several models of the pion flux used in the literature, and yields an improved extraction of the pion structure function and its uncertainties at parton momentum fractions in the pion of $4 \\times 10^{-4} \\lesssim x_\\pi \\lesssim 0.05$ at a scale of $Q^2$=10 GeV$^2$. Based on the fit results, we provide estimates for leading proton structure functions in upcoming tagged deep-inelastic scattering experiments at Jefferson Lab on the deuteron with forward protons.

  11. Biomedical applications of pion-producing accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Rosen, L [Los Alamos Scientific Lab., NM (USA)

    1980-01-01

    It was proved by the Los Alamos Scientific Laboratory of the U. S. that applications of pi-mesons in the treatment of cancer could eliminate the problem of dose localization attendant upon conventional radiation therapy. A negative pi-meson, once it is produced from energy, behaves quantum mechanically like an electron and executes orbits around a nucleus. Because its mass is 300 times that of an electron, the orbits are smaller in that ratio. Hence, on achieving the innermost orbit, the pi-meson is captured by the nucleus and causes it to explode. The resultant nuclear shrapnel travel very short distances, about 1 mm on the average, and are very effective in rendering afflicted cells non-productive without causing any damages to healthy cells in the vicinity of the tumor. Given pion therapy, over 100 patients showed encouraging results. The laboratory, sponsored by the National Cancer Institute, is now developing a small facility for pion therapy. Tests on the critical components of the pion generator are expected to be conducted within the next 12 - 16 months.

  12. The Nonlinear Effects of Pion-Quark Coupling in the Cloudy Bag Model

    OpenAIRE

    Yasuhiko, FUTAMI; Satoru, AKIYAMA; Department of Physics, Faculty of Science and Technology Science University of Tokyo; Department of Physics, Faculty of Science and Technology Science University of Tokyo

    1990-01-01

    The nonlinear pion-quark interaction in the Cloudy Bag Model is investigated. The Hamiltonian is normal-ordered. The vacuum expectation value of pion field squared is evaluated by introducting some cutoff momentum for the virtual pions.We then calculate g_A, including other corrections.

  13. The nonlinear effects of pion-quark coupling in the Cloudy Bag Model

    International Nuclear Information System (INIS)

    Futami, Yasuhiko; Akiyama, Satoru

    1990-01-01

    The nonlinear pion-quark interaction in the Cloudy Bag Model is investigated. The Hamiltonian is normal-ordered. The vacuum expectation value of pion field squared is evaluated by introducing some cutoff momentum for the virtual pions. We then calculate g A , including other corrections. (author)

  14. Charge exchange during pion-nucleon scattering at low energy: experiment and analysis

    International Nuclear Information System (INIS)

    Vernin, Pascal

    1972-01-01

    This research thesis lies within the frame of a more general study of pion-nucleon scattering according to the following processes: π + p → π + p; π - p → π - p; π - p → π 0 n. It more precisely addresses the last reaction, so-called charge exchange. Pion-nucleon interactions are described by phase shifts of scattering waves. But the measurement of one of these phase shifts (that of the S wave) requires very low energy pions, and could not have been performed until now with a good precision. In order to fill this gap, the author performed charge exchange experiments at 180 deg. and for energies of 22.6, 33.9 and 42.6 MeV. After a recall on involved theoretical data, the author describes the experimental setup, and reports the detailed study of problems raised by neutron detection. He shows that the analysis of experimental data allows (a 3 - a 1 ) to be obtained with a precision which, without being as high as desired, is nevertheless satisfying [fr

  15. Forward pion-nucleon charge exchange reaction and Regge constraints

    International Nuclear Information System (INIS)

    Huang Fei; Sibirtsev, A.; Krewald, S.; Hanhart, C.; Haidenbauer, J.; Meibner, U.-G.

    2009-01-01

    We present our recent study of pion-nucleon charge exchange amplitudes above 2 GeV. We analyze the forward pion-nucleon charge exchange reaction data in a Regge model and compare the resulting amplitudes with those from the Karlsruhe-Helsinki and George-Washington-University partial-wave analyses. We explore possible high-energy constraints for theoretical baryon resonance analyses in the energy region above 2 GeV. Our results show that for the pion-nucleon charge exchange reaction, the appropriate energy region for matching meson-nucleon dynamics to diffractive scattering should be around 3 GeV for the helicity flip amplitude. (authors)

  16. Hard exclusive pion electroproduction at backward angles with CLAS

    Science.gov (United States)

    Park, K.; Guidal, M.; Gothe, R. W.; Pire, B.; Semenov-Tian-Shansky, K.; Laget, J.-M.; Adhikari, K. P.; Adhikari, S.; Akbar, Z.; Avakian, H.; Ball, J.; Balossino, I.; Baltzell, N. A.; Barion, L.; Battaglieri, M.; Bedlinskiy, I.; Biselli, A. S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Cao, F. T.; Carman, D. S.; Celentano, A.; Charles, G.; Chetry, T.; Ciullo, G.; Clark, L.; Cole, P. L.; Contalbrigo, M.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Defurne, M.; Deur, A.; Djalali, C.; Dupre, R.; Egiyan, H.; El Alaoui, A.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fersch, R.; Filippi, A.; Garçon, M.; Ghandilyan, Y.; Gilfoyle, G. P.; Girod, F. X.; Golovatch, E.; Griffioen, K. A.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Heddle, D.; Hicks, K.; Holtrop, M.; Hyde, C. E.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jenkins, D.; Johnston, S.; Joo, K.; Kabir, M. L.; Keller, D.; Khachatryan, G.; Khachatryan, M.; Khandaker, M.; Kim, W.; Klein, F. J.; Kubarovsky, V.; Kuhn, S. E.; Lanza, L.; Livingston, K.; MacGregor, I. J. D.; Markov, N.; McKinnon, B.; Mirazita, M.; Mokeev, V.; Montgomery, R. A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Paolone, M.; Paremuzyan, R.; Pasyuk, E.; Phelps, W.; Pogorelko, O.; Poudel, J.; Price, J. W.; Prok, Y.; Protopopescu, D.; Ripani, M.; Rizzo, A.; Rossi, P.; Sabatié, F.; Salgado, C.; Schumacher, R. A.; Sharabian, Y.; Skorodumina, Iu.; Smith, G. D.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Tan, J. A.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Wei, X.; Zachariou, N.; Zhang, J.

    2018-05-01

    We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, ep →e‧ nπ+, above the resonance region at backward pion center-of-mass angles. The φπ* -dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs). These non-perturbative objects are defined as matrix elements of three-quark-light-cone-operators and characterize partonic correlations with a particular emphasis on baryon charge distribution inside a nucleon.

  17. Color-singlet and color-octet contributions to J/ψ photoproduction

    International Nuclear Information System (INIS)

    Kraemer, M.

    1996-09-01

    I discuss the impact of color-octet contributions and higher-order QCD corrections on the cross section for inelastic J/ψ photoproduction. The theoretical predictions are compared with recent experimental data obtained at HERA. (orig.)

  18. Jet photoproduction at HERA

    International Nuclear Information System (INIS)

    Frixione, S.

    1997-01-01

    We compute various kinematical distributions for one-jet and two-jet inclusive photoproduction at HERA. Our results are accurate to next-to-leading order in QCD. We use the subtraction method for the cancellation of infrared singularities. We perform a thorough study of the reliability of QCD predictions; in particular, we consider the scale dependence of our results and discuss the cases when the perturbative expansion might break down. We also deal with the problem of the experimental definition of the pointlike and hadronic components of the incident photon, and briefly discuss the sensitivity of QCD predictions upon the input parameters of the calculation, like α S and the parton densities. (orig.)

  19. Static model calculation of pion-nucleon scattering

    International Nuclear Information System (INIS)

    Itoh, Takashi

    1975-01-01

    The p-wave pion-nucleon scattering phase-shifts are computed by the Chew-Low static model for pion incident energy of 0-300 MeV. The square of the unrenormalized coupling constant is taken to be f 2 =0.2, and the cutoff is made at k sub(max)=6μ. The computed 3,3 phase-shift passes through 90 deg about at the right energy. The other phase-shifts computed are small in rough agreement with experiment. (auth.)

  20. The electric conductivity of a pion gas

    International Nuclear Information System (INIS)

    Atchison, J.; Rapp, R.

    2017-01-01

    The determination of transport coefficients plays a central role in characterizing hot and dense nuclear matter. In the present work we calculate the electric conductivity of hot hadronic matter by extracting it from the ρ meson spectral function, as its zero-energy limit at vanishing momentum. Using hadronic many-body theory, we calculate the ρ meson self-energy in a pion gas. This requires the dressing of the pion propagators in the ρ self-energy with π - ρ loops, and the inclusion of vertex corrections to maintain gauge invariance. The resulting spectral function is used to calculate the electric conductivity of hot hadronic matter. In particular, we analyze the transport peak of the spectral function and extract its behavior with temperature and coupling strength. Our results suggest that, while obeying lower bounds proposed by conformal field theories in the strong-coupling limit, hot pion matter is a strongly-coupled medium. (paper)

  1. Quantum mechanical signature in exclusive coherent pion production

    Science.gov (United States)

    Deutchman, P. A.; Buvel, R. L.; Maung, K. M.; Norbury, J. W.; Townsend, L. W.

    1986-01-01

    We calculate the coherent production of pions from subthreshold to relativistic energies in heavy-ion collisions using a quantum, microscopic, many-body model. For the first time, in this approach, we use harmonic oscillator wave functions to describe shell-model information. The theoretical quantum mechanical results obtained for the pion spectra represent an important improvement over our previous microscopic, many-body calculations.

  2. Neutrino emission in inhomogeneous pion condensed quark matter

    International Nuclear Information System (INIS)

    Huang, Xuguang; Wang, Qun; Zhuang, Pengfei

    2008-01-01

    It is believed that quark matter can exist in neutron star interior if the baryon density is high enough. When there is a large isospin density, quark matter could be in a pion condensed phase. We compute neutrino emission from direct Urca processes in such a phase, particularly in the inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states. The neutrino emissivity and specific heat are obtained, from which the cooling rate is estimated. (author)

  3. Experimental studies of pion-nucleus interactions at intermediate energies

    International Nuclear Information System (INIS)

    1992-01-01

    This report summarizes investigations of various pion-nucleus interactions and nucleon-nucleus charge-exchange reactions. The work was carried out with the LAMPF accelerator at the Los Alamos National Laboratory and the cyclotrons at the Paul Scherrer Institute (PSI) near Zurich, Switzerland, and at Indiana University (IUCF), as a collaborative effort among several laboratories and universities. The experimental activity at LAMPF involved measurements of new data on pion double-charge-exchange scattering, some initial work on a new Neutral Meson Spectrometer system, a search for deeply-bound pionic atoms, measurements of elastic scattering, and studies of the (n,p) reaction on various nuclei. At PSI measurements of pion quasielastic scattering were carried out, with detection of the recoil proton. Work on the analysis of data from a previous experiment at PSI on pion absorption in nuclei was continued. This experiment involved using a detector system that covered nearly the full solid angle

  4. Phototransformation of Amlodipine in Aqueous Solution: Toxicity of the Drug and Its Photoproduct on Aquatic Organisms

    Directory of Open Access Journals (Sweden)

    Marina DellaGreca

    2007-01-01

    Full Text Available The phototransformation of amlodipine in water was investigated under various conditions. A quantum yield ΦS2.2×10−4 and a half-life time t1/2 0.419 days were calculated when the drug in water (10−4 M was exposed to sunlight. The only photoproduct found was its pyridine derivative. Formation of this product was explained on the basis of a radical cation intermediate. The acute and chronic toxicity of the drug and its photoproduct were evaluated on different organisms of the freshwater chain (Brachionus calyciflorus, Thamnocephalus platyurus, Daphnia magna, Ceriodaphnia dubia. The photoproduct exhibited a stronger toxic potential than the parent drug on the long time for C. dubia.

  5. Pion-exchange contribution to the parity-violating asymmetry in pp scattering

    International Nuclear Information System (INIS)

    Silbar, R.R.; Kloet, W.M.; Kisslinger, L.S.; Dubach, J.

    1988-01-01

    Charged pion exchange, producing nΔ ++ intermediate states, contributes negatively to the weak scattering asymmetry in longitudinally-polarized pp scattering. Including this contribution moves the theoretical prediction away from the 800 MeV experimental datum. The pion-exchange contribution has both inelastic and elastic scattering components and is sizeable even below the pion production threshold. Strong distortions enhance the magnitude of the effect. 14 refs., 5 figs

  6. Partial-wave analyses of hadron scattering below 2 GeV

    International Nuclear Information System (INIS)

    Arndt, R.A.; Roper, L.D.

    1990-01-01

    The Center for Analysis of Particle Scattering (CAPS) in the Department of Physics at Virginia Polytechnic Institute and State University has analyzed basic two-body hadron reactions below 2 GeV for the last two decades. Reactions studied were nucleon-nucleon, pion-nucleon, K + -nucleon and pion photoproduction systems. In addition to analyses of these systems, a computer graphics system (SAID) has been developed and disseminated to over 200 research institutions using VAX computers. 8 refs

  7. Differential Cross-Sections for pi- p --> gamma n in the First Resonance Region

    CERN Document Server

    Guex-Le Lan, Huong; Hilscher, H; Joseph, C L; Schmitt, H; Tran, M T; Truöl, P; Vaucher, B; Winkelmann, E; Zupancic, Crtomir; Joseph, C L no 1; Tran, M T no 1; Vaucher, B no 1; Winkelmann, E no 1; Bayer, W no 2; Hilscher, H no 2; Schmitt, H no 2; Zupancic, C no 2; Truöl, P no 3; Guex, L H no 1

    1975-01-01

    Differential cross-sections for negative pion radiative capture on protons at c.m. angles of 60°, 90°, and 120° have been measured at nine incident laboratory energies between 110 and 270 MeV. Comparison with measured cross-sections for pion photoproduction and with conventional multipole analyses shows neither evidence for a violation of time reversal invariance nor for an isotensor component of the electromagnetic current of hardrons. Record added 1974-09-01, las

  8. Exclusive electroproduction of two pions at HERA

    Energy Technology Data Exchange (ETDEWEB)

    Abramowicz, H. [Tel Aviv Univ. (Israel). School of Physics; Max Planck Institute for Physics, Munich (Germany); Abt, I. [Max Planck Institute for Physics, Munich (Germany); Adamczyk, L. [AGH-Univ. of Science and Technology, Krakow (PL). Faculty of Physics and Applied Computer Science] (and others)

    2011-11-15

    The exclusive electroproduction of two pions in the mass range 0.4< M{sub {pi}}{sub {pi}} <2.5 GeV has been studied with the ZEUS detector at HERA using an integrated luminosity of 82 pb{sup -1}. The analysis was carried out in the kinematic range of 2< Q{sup 2}<80 GeV{sup 2}, 32pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, vertical stroke F(M{sub {pi}}{sub {pi}}) vertical stroke, assuming that the studied mass range includes the contributions of the {rho}, {rho}{sup '} and {rho}'' vector-meson states. The masses and widths of the resonances were obtained and the Q{sup 2} dependence of the cross-section ratios {sigma}({rho}{sup '} {yields} {pi}{pi})/{sigma}({rho}) and {sigma}({rho}'' {yields} {pi}{pi})/{sigma}({rho}) was extracted. The pion form factor obtained in the present analysis is compared to that obtained in e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -}. (orig.)

  9. Dispersion relation for hadronic light-by-light scattering: two-pion contributions

    Energy Technology Data Exchange (ETDEWEB)

    Colangelo, Gilberto [Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland); Hoferichter, Martin [Institute for Nuclear Theory, University of Washington, Seattle, WA 98195-1550 (United States); Kavli Institute for Theoretical Physics, University of California,Santa Barbara, CA 93106 (United States); Procura, Massimiliano [Theoretical Physics Department, CERN, Geneva (Switzerland); Stoffer, Peter [Helmholtz-Institut für Strahlen- und Kernphysik (Theory)and Bethe Center for Theoretical Physics, University of Bonn, 53115 Bonn (Germany); Department of Physics, University of California at San Diego, La Jolla, CA 92093 (United States)

    2017-04-27

    In this third paper of a series dedicated to a dispersive treatment of the hadronic light-by-light (HLbL) tensor, we derive a partial-wave formulation for two-pion intermediate states in the HLbL contribution to the anomalous magnetic moment of the muon (g−2){sub μ}, including a detailed discussion of the unitarity relation for arbitrary partial waves. We show that obtaining a final expression free from unphysical helicity partial waves is a subtle issue, which we thoroughly clarify. As a by-product, we obtain a set of sum rules that could be used to constrain future calculations of γ{sup ∗}γ{sup ∗}→ππ. We validate the formalism extensively using the pion-box contribution, defined by two-pion intermediate states with a pion-pole left-hand cut, and demonstrate how the full known result is reproduced when resumming the partial waves. Using dispersive fits to high-statistics data for the pion vector form factor, we provide an evaluation of the full pion box, a{sub μ}{sup π-box}=−15.9(2)×10{sup −11}. As an application of the partial-wave formalism, we present a first calculation of ππ-rescattering effects in HLbL scattering, with γ{sup ∗}γ{sup ∗}→ππ helicity partial waves constructed dispersively using ππ phase shifts derived from the inverse-amplitude method. In this way, the isospin-0 part of our calculation can be interpreted as the contribution of the f{sub 0}(500) to HLbL scattering in (g−2){sub μ}. We argue that the contribution due to charged-pion rescattering implements corrections related to the corresponding pion polarizability and show that these are moderate. Our final result for the sum of pion-box contribution and its S-wave rescattering corrections reads a{sub μ}{sup π-box}+a{sub μ,J=0}{sup ππ,π-pole} {sup LHC}=−24(1)×10{sup −11}.

  10. ABC's of pion charge exchange

    International Nuclear Information System (INIS)

    Gibbs, W.R.; Kaufmann, W.B.; Siegel, P.B.

    1985-01-01

    Calculations of pion single charge exchange using the PWIA and DWIA are presented. Emphasis is given to the effects of absorbtion and blocking. A microscopic calculation of the 0 0 excitation and low energy angular distribution is in excellent agreement with the data. A fixed nucleon multiple scattering calculation of the pion double charge exchange reaction is presented. Various valence neutron wave functions are used, and the contributions of different spatial orientations of the last two neutrons to the reaction are examined. The DCX cross section is found to be very sensitive to the inclusion of correlations in the two-neutron wave function. Satisfactory agreement with DCX data on 14 C can be obtained using a nucleonic picture of the nucleus

  11. Photoproduction of charged particle with high transverse momentum

    International Nuclear Information System (INIS)

    Campos Costa Ramos, S.E. de.

    1986-09-01

    Inclusive cross sections of high transverse moment charged pions induced by a high energy photon beam have been measured. These results do not account, neither in slope nor in normalisation, for the VDM component of the photon, evaluated with pion induced data taken in the same experimental conditions after VDM subtraction, excellent agreement is found with QCD calculations up to second order in α s , in an extended cinematic region, different choices of the gluon fragmentation function do not alter this conclusion. Our measures of the inclusive final state charge asymmetries also confirm QCD expectations. 42 refs [fr

  12. Isotopic spin effect in three-pion Bose-Einstein correlations

    International Nuclear Information System (INIS)

    Suzuki, N.

    1998-01-01

    Bose-Einstein (BE) correlations of identical particles in multiple production processes are extensively studied last years because they give an information on the space-time region of interaction. The basic effect is analogous to Hanbury-Brown - Twiss (HBT) interferometry in optics and suggests statistical production of the particles (mainly π mesons). The possible presence of coherent pionic component (for example, in the case of disoriented chiral condensate formation) modifies the HBT effect. On the other hand, the pions (contrary to photons) are subject to isotopic spin (and electric charge) conservation and so they can not be emitted independently. While the corresponding change of the statistical part is not essential for large multiplicities, the coherent part changes substantially when isotopic spin conservation is taken into account. BE correlations of the pions in the presence of both statistical and coherent components are reconsidered taking into account isotopic spin conservation in the coherent part. That will result in appearance of additional contribution to pionic correlation function. (author)

  13. Measurement of the Photoproduction of Vector and Scalar Bosons

    CERN Multimedia

    2002-01-01

    The original programme of the experiment consisted of a detailed study of projectile fragmentation on nucleons and nuclei with particular attention to diffractive excitation. This programme of research was then specified as the measurement of coherent photoproduction on nuclei up to $\\simeq$180 GeV with the following aims: \\item a) photoproduction of charmed particle pairs and measurement of charmed particle lifetimes by means of an active target; \\item b) study of the spectroscopy of the new massive particles with particular attention to the hadronic decay channels, containing charged particles and photons, and to radiative decays. \\end{enumerate}\\\\ \\\\ The apparatus consists of a forward spectrometer for charged particles and photons and of a large angle detector which provides the topology of individual events. The spectrometer subtends a solid angle of $\\simeq$ 40 msr and consists of four bending magnets interspaced by sets of drift chambers, counter hodoscopes and photon detectors. The momentum resolution...

  14. Pion interferometry of ultra-relativistic hadronic collisions

    International Nuclear Information System (INIS)

    Kolehmainen, K.

    1986-05-01

    Pion interferometry of ultra-relativistic hadronic collisions is described in the context of the inside-outside cascade model using a current ensemble method capable of describing an arbitrary distribution of pion sources with an arbitrary velocity distribution. The results are quite distinct from the usual Gaussian and Kopylov parameterizations. Extraction of the temperature parameter, effective source lifetime, and transverse size requires a full three-dimensional analysis of the correlation function in terms of the momentum difference. 7 refs., 4 figs

  15. NEUTRAL KAON PHOTOPRODUCTION AT LNS, TOHOKU UNIVERSITY

    Czech Academy of Sciences Publication Activity Database

    Kaneta, M.; Chiga, N.; Beckford, B.; Ejima, M.; Fujii, T.; Fujii, Y.; Fujibayashi, T.; Gogami, T.; Futatsukawa, K.; Hashimoto, O.; Hosomi, K.; Hirose, K.; Iguchi, A.; Kameoka, S.; Kanda, H.; Kato, H.; Kawama, D.; Kawasaki, T.; Kimura, C.; Kiyokawa, S.; Koike, T.; Kon, T.; Ma, Y.; Maeda, K.; Maruyama, N.; Matsumura, A.; Miyagi, Y.; Miura, Y.; Miwa, K.; Nakamura, S. N.; Nomura, H.; Okuyama, A.; Ohtani, A.; Otani, T.; Sato, M.; Shichijo, A.; Shirotori, K.; Takahashi, T.; Tamura, H.; Taniya, N.; Tsubota, H.; Tsukada, K.; Terada, N.; Ukai, M.; Uchida, D.; Watanabe, T.; Yamamoto, T.; Yamauchi, H.; Yokota, K.; Ishikawa, T.; Kinoshita, T.; Miyahara, H.; Nakabayashi, T.; Shimizu, H.; Suzuki, K.; Tamae, T.; Terasawa, T.; Yamazaki, H.; Han, Y. C.; Wang, T. S.; Sasaki, A.; Konno, O.; Bydžovský, Petr; Sotona, Miloslav

    2010-01-01

    Roč. 19, č. 12 (2010), s. 2355-2362 ISSN 0218-3013. [Sendai International Conference on Strangeness in Nuclear and Hadronic Systems. Sendai, 15.12.2008-18.12.2008] R&D Projects: GA ČR GA202/05/2142; GA ČR GA202/08/0984 Institutional research plan: CEZ:AV0Z10480505 Keywords : Strangeness * photoproduction Subject RIV: BE - Theoretical Physics Impact factor: 0.695, year: 2010

  16. The readout of the ZEUS forward detector and studies on the ρ' -resonance in the photoproduction of π+π-- pairs

    International Nuclear Information System (INIS)

    Stamm, J.

    1997-12-01

    Track finding and reconstruction of charged particles close to the beam-line with the ZEUS-detector at HERA uses three planar drift chambers in the forward (FTDs), and one in rear direction (RTD). In addition two pairs of transition radiation detectors (TRD) are located between the FTDs. In 1993-1995 the TRD and FRTD readout systems were included in the global ZEUS data acquisition. A detailed description of the systems is given. In particular the communication between single modules in the components system and the synchronisation with the global ZEUS trigger components are explained. The analysis of photoproduction events of the reaction ep → π + π - p in the region of M ππ > 1.1 GeV with special respect to the track reconstruction with RTD is described in a second part of this report. In this mass region the ρ'-resonance in the decay channel ρ'→ π + π - is studied. The mass peak at 1.6 GeV is best described with a parametrisation including two resonances. Results are also given on the vertical stroke t vertical stroke - and W-dependence of the cross section as well as the polar angular distribution of the decay pions. (orig.)

  17. A phenomenological determination of the pion-nucleon scattering lengths from pionic hydrogen

    CERN Document Server

    Ericson, Torleif Eric Oskar; Wycech, S

    2005-01-01

    A model independent expression for the electromagnetic corrections to a phenomenological hadronic pion-nucleon scattering length, extracted from pionic hydrogen, is obtained. In a non-relativistic approach and using an extended charge distribution, these corrections are derived up to terms of order (alpha)**2 log(alpha) in the limit of a short-range hadronic interaction. We infer a charged pion-proton scattering length of 0.0870(5) in units of inverse pion mass, which gives for the charged pion-proton-neutron coupling, through the GMO relation, a value of 14.04(17).

  18. Neutral pion production in heavy ion collisions at SIS-energies

    International Nuclear Information System (INIS)

    Sumbera, M.; Loehner, H.; Raschke, A.E.; Venema, L.B.; Wilschut, H.W.

    1993-01-01

    The production of π 0 mesons has been studied in the reactions 40 Ar+Ca and 197 Au+Au at 1.0 GeV/u. While the pion transverse momentum spectrum from the reaction Ar+Ca is consistent with a simple thermal exponential slope a second component is seen for the system Au+Au. Both neutral pions, neutrons and charged particles exhibit an anisotropy in the reaction plane azimuth. At midrapidity the emission of pions perpendicular to the reaction plane increases with their energy. (orig.)

  19. The TRIUMF low energy pion spectrometer and channel

    International Nuclear Information System (INIS)

    Sobie, R.J.; Drake, T.E.; Barnett, B.M.; Erdman, K.L.; Gyles, W.; Johnson, R.R.; Roser, H.W.; Tacik, R.; Blackmore, E.W.; Gill, D.R.

    1983-08-01

    A low energy pion spectrometer has been developed for use with the TRIUMF M13 pion channel. The combined channel and spectrometer resolution is presently 1.1 MeV at T = 50 MeV. This is limited by the amount of gas and detector material in the spectrometer in addition to the inherent resolution of the channel. Improvements to both the spectrometer and channel are discussed

  20. Zero-degree injection line for PILAC, the proposed Los Alamos Pion Linac

    International Nuclear Information System (INIS)

    Blind, B.

    1991-01-01

    In this paper, an optimized injection line for PILAC, the proposed Los Alamos Pion Linac, is presented. With the other optimized components (pion source, accelerator, and high-resolution beamline and spectrometer), the system is capable of delivering 10 9 920-MeV pions per second to the target. 3 refs., 2 figs