Accessing the distribution of linearly polarized gluons in unpolarized hadrons
Boer, Daniël; Brodsky, Stanley J.; Mulders, Piet J.; Pisano, Cristian
2011-01-01
Gluons inside unpolarized hadrons can be linearly polarized provided they have a nonzero transverse momentum. The simplest and theoretically safest way to probe this distribution of linearly polarized gluons is through cos(2 phi) asymmetries in heavy quark pair or dijet production in electron-hadron
Linearly Polarized Gluons and the Higgs Transverse Momentum Distribution
Boer, Daniel; den Dunnen, Wilco J.; Pisano, Cristian; Schlegel, Marc; Vogelsang, Werner
2012-01-01
We study how gluons carrying linear polarization inside an unpolarized hadron contribute to the transverse momentum distribution of Higgs bosons produced in hadronic collisions. They modify the distribution produced by unpolarized gluons in a characteristic way that could be used to determine
QCD evolution of (un)polarized gluon TMDPDFs and the Higgs q(T)-distribution
Garcia, M.; Kasemets, T.; Mulders, P.J.G.; Pisano, C.
2015-01-01
Abstract: We provide the proper definition of all the leading-twist (un)polarized gluon transverse momentum dependent parton distribution functions (TMDPDFs), by considering the Higgs boson transverse momentum distribution in hadron-hadron collisions and deriving the factorization theorem in terms
QCD evolution of (un)polarized gluon TMDPDFs and the Higgs q T -distribution
Echevarria, Miguel G.; Kasemets, Tomas; Mulders, Piet J.; Pisano, Cristian
2015-07-01
We provide the proper definition of all the leading-twist (un)polarized gluon transverse momentum dependent parton distribution functions (TMDPDFs), by considering the Higgs boson transverse momentum distribution in hadron-hadron collisions and deriving the factorization theorem in terms of them. We show that the evolution of all the (un)polarized gluon TMDPDFs is driven by a universal evolution kernel, which can be resummed up to next-to-next-to-leading-logarithmic accuracy. Considering the proper definition of gluon TMDPDFs, we perform an explicit next-to-leading-order calculation of the unpolarized ( f {1/ g }), linearly polarized ( h {1/⊥ g }) and helicity ( g {1/L g }) gluon TMDPDFs, and show that, as expected, they are free from rapidity divergences. As a byproduct, we obtain the Wilson coefficients of the refactorization of these TMDPDFs at large transverse momentum. In particular, the coefficient of g {1/L g }, which has never been calculated before, constitutes a new and necessary ingredient for a reliable phenomenological extraction of this quantity, for instance at RHIC or the future AFTER@LHC or Electron-Ion Collider. The coefficients of f {1/ g } and h {1/⊥ g } have never been calculated in the present formalism, although they could be obtained by carefully collecting and recasting previous results in the new TMD formalism. We apply these results to analyze the contribution of linearly polarized gluons at different scales, relevant, for instance, for the inclusive production of the Higgs boson and the C-even pseudoscalar bottomonium state η b . Applying our resummation scheme we finally provide predictions for the Higgs boson q T -distribution at the LHC.
The Weizsäcker-Williams distribution of linearly polarized gluons (and its fluctuations) at small x
Energy Technology Data Exchange (ETDEWEB)
Dumitru, Adrian; Skokov, Vladimir
2017-09-11
The conventional and linearly polarized Weizsäcker-Williams gluon distributions at small x are defined from the two-point function of the gluon field in light-cone gauge. They appear in the cross section for dijet production in deep inelastic scattering at high energy. We determine these functions in the small-x limit from solutions of the JIMWLK evolution equations and show that they exhibit approximate geometric scaling. Also, we discuss the functional distributions of these WW gluon distributions over the JIMWLK ensemble at rapidity Y ~ 1/αs. These are determined by a 2d Liouville action for the logarithm of the covariant gauge function g2tr A+(q)A+(-q). For transverse momenta on the order of the saturation scale we observe large variations across configurations (evolution trajectories) of the linearly polarized distribution up to several times its average, and even to negative values.
Gluons and the Quark Sea at High Energies: Distributions, Polarization, Tomography
Energy Technology Data Exchange (ETDEWEB)
Boer, Daniel; /Groningen U.; Diehl, Markus; /DESY; Milner, Richard; /MIT; Venugopalan, Raju; /Brookhaven; Vogelsang, Werner; /Tubingen U.; Kaplan, David; /Washington U., Seattle; Montgomery, Hugh; /Jefferson Lab; Vigdor, Steven; /Brookhaven; Accardi, A.; /Jefferson Lab; Aschenauer, E.C.; /Brookhaven; Burkardt, M.; /New Mexico State U.; Ent, R.; /Jefferson Lab; Guzey, V.; /Jefferson Lab; Hasch, D.; /Frascati; Kumar, K.; /Massachusetts U., Amherst; Lamont, M.A.C.; /Brookhaven; Li, Ying-chuan; /Brookhaven; Marciano, W.; /Brookhaven; Marquet, C.; /CERN; Sabatie, F.; /IRFU, SPhN, Saclay; Stratmann, M.; /Brookhaven /LBL, Berkeley /Buenos Aires U. /Antwerp U. /Pelotas U. /Moncton U. /Santa Maria U., Valparaiso /CCTVal, Valparaiso /Hefei, CUST /Shandong U., Weihai /Boskovic Inst., Zagreb /Zagreb U., Phys. Dept. /Jyvaskyla U. /Orsay, LPT /Paris U., VI-VII /Ecole Polytechnique, CPHT /IRFU, SPhN, Saclay /Saclay, SPhT /Ruhr U., Bochum /Giessen U. /DESY /Hamburg U., Inst. Theor. Phys. II /Heidelberg U. /Mainz U., Inst. Kernphys. /Mainz U., Inst. Phys. /Regensburg U. /Tubingen U. /Wuppertal U. /DESY /Cagliari U. /INFN, Cagliari /Frascati /Milan U. /INFN, Milan /INFN, Pavia /Pavia U. /INFN, Perugia /Perugia U.; /more authors..
2012-06-07
This report on the science case for an Electron-Ion Collider (EIC) is the result of a ten-week program at the Institute for Nuclear Theory (INT) in Seattle (from September 13-November 19, 2010), motivated by the need to develop a strong case for the continued study of the QCD description of hadron structure in the coming decades. Hadron structure in the valence quark region will be studied extensively with the Jefferson Lab 12 GeV science program, the subject of an INT program the previous year. The focus of the INT program was on understanding the role of gluons and sea quarks, the important dynamical degrees of freedom describing hadron structure at high energies. Experimentally, the most direct and precise way to access the dynamical structure of hadrons and nuclei at high energies is with a high luminosity lepton probe in collider mode. An EIC with optimized detectors offers enormous potential as the next generation accelerator to address many of the most important, open questions about the fundamental structure of matter. The goal of the INT program, as captured in the writeups in this report, was to articulate these questions and to identify golden experiments that have the greatest potential to provide definitive answers to these questions. At resolution scales where quarks and gluons become manifest as degrees of freedom, the structure of the nucleon and of nuclei is intimately connected with unique features of QCD dynamics, such as confinement and the self-coupling of gluons. Information on hadron sub-structure in DIS is obtained in the form of 'snapshots' by the 'lepton microscope' of the dynamical many-body hadron system, over different momentum resolutions and energy scales. These femtoscopic snapshots, at the simplest level, provide distribution functions which are extracted over the largest accessible kinematic range to assemble fundamental dynamical insight into hadron and nuclear sub-structure. For the proton, the EIC would be
χc charmonium - a tool to investigate gluon polarization
International Nuclear Information System (INIS)
Batunin, A.V.; Slabospitskij, S.R.
1986-01-01
Production of particles with a hidden charm Χ C in polarized parton beams (quarks or gluons) is studied. Parton polarization is shown to cause the changes of angular distributions of Χ C meson decay products, which allows one to investigate possible gluon polarization in hadrons
EXPLORING THE POLARIZATION OF GLUONS IN THE NUCLEON.
Energy Technology Data Exchange (ETDEWEB)
STRATMANN,M.; VOGELSANG,W.
2007-10-22
We give an overview of the current status of investigations of the polarization of gluons in the nucleon. We describe some of the physics of the spin-dependent gluon parton distribution and its phenomenology in high-energy polarized hadronic scattering. We also review the recent experimental results.
Gluons and the quark sea at high energies: distributions, polarization, tomography
Energy Technology Data Exchange (ETDEWEB)
Boer, D.; Venugopalan, R.; Diehl, M.; Milner, R.; Vogelsang, W.; et al.
2011-09-30
This report is based on a ten-week program on Gluons and the quark sea at high-energies, which took place at the Institute for Nuclear Theory (INT) in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics (QCD). This report is organized around the following four major themes: (i) the spin and flavor structure of the proton, (ii) three dimensional structure of nucleons and nuclei in momentum and configuration space, (iii) QCD matter in nuclei, and (iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific opportunities presented by an EIC.
Gluons and the quark sea at high energies: distributions, polarization, tomography
Boer, D; Milner, Richard; Venugopalan, Raju; Vogelsang, Werner; Kaplan, David; Montgomery, Hugh; Vigdor, Steven; Accardi, A.; Aschenauer, E.C.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M.A.C.; Li, Ying-chuan; Marciano, W.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Sassot, R.; Zurita, P.; Cherednikov, I.O.; Goncalves, V.P.; Sandapen, R.; Kopeliovich, B.Z.; Gao, J.-H.; Liang, Z.-T.; Passek-Kumericki, K.; Kumericki, K.; Lappi, T.; Wallon, S.; Pire, B.; Geraud, R.; Moutarde, H.; Gelis, F.; Soyez, G.; Meskauskas, M.; Mueller, Dieter; Stefanis, N.G.; Gallmeister, K.; Mosel, U.; Diehl, M.; Bartels, J.; Pirner, H.J.; Hagler, P.; Jager, B.; Spiesberger, H.; Lautenschlager, T.; Schafer, A.; Ringer, F.; Vogelsang, W.; Kroll, P.; Alekhin, S.; Blumlein, J; Moch, S.-O.; Pisano, C.; Rojo, J.; Bacchetta, A.; Pasquini, B.; Radici, M.; Ciofi degli Atti, C.; Mezzetti, C.B.; Kaptari, L.P.; Anselmino, M.; Tanaka, K.; Koike, Y.; Kumano, S.; Motyka, L.; Golec-Biernat, K.; Stasto, A.M.; Golec-Biernat, K.; Szymanowski, L.; Cherednikov, I.O.; Kaptari, L.P.; Radyushkin, A.; Alekhin, S.; Kondratenko, A.; Horowitz, W.A.; Schnell, G.; Chevtsov, P.; Mulders, P.J.; Rogers, T.C.; Boer, D.; Forshaw, J.R.; Cooper-Sarkar, A.; Chirilli, G.A.; Muller, D.; Wang, X.-N.; Yuan, F.; Qian, X.; Brodsky, S.J.; Schweitzer, P.; Horn, T.; Tuchin, K.; Dupre, R.; Erdelyi, B.; Manikonda, S.; Ostrumov, P.N.; Abeyratne, S.; Erdelyi, B.; Vossen, A.; Riordan, S.; Tsentalovich, E.; Goldstein, G.R.; Pozdeyev, E.; Huang, M.; Aidala, C.; Dumitru, A.; Dominguez, F.; Ben-Zvi, I.; Deshpande, A.; Faroughy, C.; Hammons, L.; Hao, Y.; Johnson, E.C.; Litvinenko, V.N.; Taneja, S.; Tsoupas, N.; Webb, S.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M.M.; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Ptitsyn, V.; Rao, T.; Roser, T.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Zelenski, A.; Beuf, G.; Burton, T.; Debbe, R.; Fazio, S.; Marciano, W.J.; Qiu, J.-W.; Toll, T.; Ullrich, T.; Deshpande, A.; Dumitru, A.; Kang, Z.-B.; Stasto, A.M.; Yuan, F.; Kovchegov, Y.V.; Majumder, A; Metz, A.; Zhou, J.; Gamberg, L.; Stasto, A.M.; Strikman, M.; Xiao, B.-W.; Guzzi, M.; Nadolsky, P.; Olness, F.; BC, H.; Liuti, S.; Ahmed, S.; Bogacz, A.; Derbenev, Ya.; Hutton, A.; Krafft, G.; Li, R.; Marhauser, F.; Morozov, V.; Pilat, F.; Rimmer, R.; Satogata, T.; Sullivan, M.; Spata, M.; Terzic, B.; Wang, H.; Yunn, B.; Zhang, Y.; Avakian, H.; Musch, B.; Nadel-Turonski, P.; Prokudin, A.; Radyushkin, A.; Weiss, C.; Krafft, G.; Radyushkin, A.; Sayed, H.; Gilfoyle, G.P.; Cloet, I.C.; Miller, G.; Gonderinger, M.
2011-01-01
This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that will be able to collide electrons and positrons with polarized protons and with light to heavy nuclei at high energies, offering unprecedented possibilities for in-depth studies of quantum chromodynamics. This report is organized around four major themes: i) the spin and flavor structure of the proton, ii) three-dimensional structure of nucleons and nuclei in momentum and configuration space, iii) QCD matter in nuclei, and iv) Electroweak physics and the search for physics beyond the Standard Model. Beginning with an executive summary, the report contains tables of key measurements, chapter overviews for each of the major scientific themes, and detailed individual contributions on various aspects of the scientific op...
Gluons and the quark sea at high energies : distributions, polarization, tomography
Boer, D.; Diehl, M.; Milner, R.; Venugopalan, R.; Vogelsang, W.; Accardi, A.; Aschenauer, E.; Burkardt, M.; Ent, R.; Guzey, V.; Hasch, D.; Kumar, K.; Lamont, M. A. C.; Li, Y.; Marciano, W. J.; Marquet, C.; Sabatie, F.; Stratmann, M.; Yuan, F.; Abeyratne, S.; Ahmed, S.; Aidala, C.; Alekhin, S.; Anselmino, M.; Avakian, H.; Bacchetta, A.; Bartels, J.; H., BC; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Beuf, G.; Blumlein, J.; Blaskiewicz, M .; Bogacz, A.; Brodsky, S. J.; Burton, T.; Calaga, R.; Chang, X.; Cherednikov, I. O.; Chevtsov, P.; Chirilli, G. A.; Atti, C. Ciofi degli; Cloet, I. C.; Cooper-Sarkar, A.; Debbe, R.; Derbenev, Ya; Deshpande, A.; Dominguez, F.; Dumitru, A.; Dupre, R.; Erdelyi, B.; Faroughy, C.; Fazio, S.; Fedotov, A.; Forshaw, J. R.; Geraud, R.; Gallmeister, K.; Gamberg, L.; Gao, J. -H.; Gassner, D.; Gelis, F.; Gilfoyle, G. P.; Goldstein, G.; Golec-Biernat, K.; Goncalves, V. P.; Gonderinger, M.; Guzzi, M.; Hagler, P.; Hahn, H.; Hammons, L.; Hao, Y.; He, P.; Horn, T.; Horowitz, W. A.; Huang, M.; Hutton, A.; Jager, B.; Jackson, W.; Jain, A.; Johnson, E. C.; Kang, Z. -B.; Kaptari, L. P.; Kayran, D.; Kewisch, J.; Koike, Y.; Kondratenko, A.; Kopeliovich, B. Z.; Kovchegov, Y. V.; Krafft, G.; Kroll, P.; Kumano, S.; Kumericki, K.; Lappi, T.; Lautenschlager, T.; Li, R.; Liang, Z. -T.; Litvinenko, V. N.; Liuti, S.; Luo, Y.; Muller, D.; Mahler, G.; Majumder, A.; Manikonda, S.; Marhauser, F.; McIntyre, G.; Meskauskas, M.; Meng, W.; Metz, A.; Mezzetti, C. B.; Miller, G. A.; Minty, M.; Moch, S. -O.; Morozov, V.; Mosel, U.; Motyka, L.; Moutarde, H.; Mulders, P. J.; Musch, B.; Nadel-Turonski, P.; Nadolsky, P.; Olness, F.; Ostrumov, P. N.; Parker, B.; Pasquini, B.; Passek-Kumericki, K.; Pikin, A.; Pilat, F.; Pire, B.; Pirner, H.; Pisano, C.; Pozdeyev, E.; Prokudin, A.; Ptitsyn, V.; Qian, X.; Qiu, J. -W.; Radici, M.; Radyushkin, A.; Rao, T.; Rimmer, R.; Ringer, F.; Riordan, S.; Rogers, T.; Rojo, J.; Roser, T.; Sandapen, R.; Sassot, R.; Satogata, T.; Sayed, H.; Schafer, A.; Schnell, G.; Schweitzer, P.; Sheehy, B.; Skaritka, J.; Soyez, G.; Spata, M.; Spiesberger, H.; Stasto, A. M.; Stefanis, N. G.; Strikman, M.; Sullivan, M.; Szymanowski, L.; Tanaka, K.; Taneja, S.; Tepikian, S.; Terzic, B.; Than, Y.; Toll, T.; Trbojevic, D.; Tsentalovich, E.; Tsoupas, N.; Tuchin, K.; Tuozzolo, J.; Ullrich, T.; Vossen, A.; Wallon, S.; Wang, G.; Wang, H.; Wang, X. -N.; Webb, S.; Weiss, C.; Wu, Q.; Xiao, B. -W.; Xu, W.; Yunn, B.; Zelenski, A.; Zhang, Y.; Zhou, J.; Zurita, P.
2011-01-01
This report is based on a ten-week program on "Gluons and the quark sea at high-energies", which took place at the Institute for Nuclear Theory in Seattle in Fall 2010. The principal aim of the program was to develop and sharpen the science case for an Electron-Ion Collider (EIC), a facility that
Gluon field distribution in baryons
International Nuclear Information System (INIS)
Bissey, F.; Cao, F-G.; Kitson, A.; Lasscock, B.G.; Leinweber, D.B.; Signal, A.I.; Williams, A.G.; Zanotti, J.M.
2005-01-01
Methods for revealing the distribution of gluon fields within the three-quark static-baryon potential are presented. In particular, we outline methods for studying the sensitivity of the source on the emerging vacuum response for the three-quark system. At the same time, we explore the possibility of revealing gluon-field distributions in three-quark systems in QCD without the use of gauge-dependent smoothing techniques. Renderings of flux tubes from a preliminary high-statistics study on a 12 3 x 24 lattice are presented
Possibility of determining gluon polarization via polarized top pairs in gamma-proton scattering
International Nuclear Information System (INIS)
Atag, S.; Billur, A.A.
2009-01-01
We study the possibility for directly measuring the polarized gluon distribution in the process γp→t-bar t. It is shown that polarization asymmetry of the final top quarks is proportional to the gluon polarization. With available energy and luminosity, the collision of a polarized proton beam and a Compton backscattered photon beam can create polarized top quarks which carry the spin information of the process. Energy dependence and angular distributions of the polarization asymmetry of the top pairs has been discussed including statistical uncertainty.
International Nuclear Information System (INIS)
Rindani, S.D.
2002-01-01
QCD corrections to order α s in the soft-gluon approximation to angular distributions of decay charged leptons in the process e + e - → t t-bar, followed by semileptonic decay of t or t-bar, are obtained in the e + e - centre-of-mass frame. As compared to distributions in the top rest frame, these have the advantage that they would allow direct comparison with experiment without the need to reconstruct the top rest frame. The results also do not depend on the choice of a spin quantization axis for t or t-bar. Analytic expression for the triple distribution in the polar angle of t and polar and azimuthal angles of the lepton is obtained. Analytic expression is also derived for the distribution in the charged-lepton polar angle. Numerical values are discussed for √s = 400, 800 and 1500 GeV. (author)
Polarized photons from quark-gluon plasma
International Nuclear Information System (INIS)
Goloviznin, V.V.; Snigirev, A.M.; Zinov'ev, G.M.
1988-01-01
The degree of polarization of magnetic bremsstrahlung radiation resulting from the interaction of escaping quarks with a collective confining color field is calculated. For a wide rapidity interval the angle at which the photon is registered and constitutes about 25%. This could signal about quark-gluon plasma formation
The Gluon Sivers Distribution: Status and Future Prospects
International Nuclear Information System (INIS)
Zhou, Jian; Boer, Daniël; Pisano, Cristian; Lorcé, Cédric
2015-01-01
We review what is currently known about the gluon Sivers distribution and what are the opportunities to learn more about it. Because single transverse spin asymmetries in p"↑p→πX provide only indirect information about the gluon Sivers function through the relation with the quark-gluon and tri-gluon Qiu-Sterman functions, current data from hadronic collisions at RHIC have not yet been translated into a solid constraint on the gluon Sivers function. SIDIS data, including the COMPASS deuteron data, allow for a gluon Sivers contribution of natural size expected from large N_c arguments, which is O(1/N_c) times the nonsinglet quark Sivers contribution. Several very promising processes to measure the gluon Sivers effect directly have been suggested, which besides RHIC investigations, would strongly favor experiments at AFTER@LHC and a possible future Electron-Ion Collider. Due to the inherent process dependence of TMDs, the gluon Sivers TMD probed in the various processes are different linear combinations of two universal gluon Sivers functions that have different behavior under charge conjugation and that therefore satisfy different theoretical constraints. For this reason both hadronic and DIS type of collisions are essential in the study of the role of gluons in transversely polarized protons.
Experiments to measure the gluon helicity distribution in protons
International Nuclear Information System (INIS)
Spinka, H.; Beddo, M.E.; Underwood, D.G.
1993-01-01
Several experiments are described that could obtain information about the gluon helicity distribution in protons. These experiments include inclusive direct-γ, direct-γ + jet, jet, and jet + jet production with colliding beams of longitudinally-polarized protons. Some rates and kinematics are also discussed
Direct Probes of Linearly Polarized Gluons inside Unpolarized Hadrons
Boer, D.; Brodsky, S. J.; Mulders, P.J.G.; Pisano, C.
2011-01-01
We show that linearly polarized gluons inside unpolarized hadrons can be directly probed in jet or heavy quark pair production in electron-hadron collisions. We discuss the simplest cos2 asymmetries and estimate their maximal value, concluding that measurements of the unknown linearly polarized
Non-perturbative inputs for gluon distributions in the hadrons
Energy Technology Data Exchange (ETDEWEB)
Ermolaev, B.I. [Ioffe Physico-Technical Institute, Saint Petersburg (Russian Federation); Troyan, S.I. [St. Petersburg Institute of Nuclear Physics, Gatchina (Russian Federation)
2017-03-15
Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K{sub T}-and collinear factorizations. (orig.)
Non-perturbative inputs for gluon distributions in the hadrons
International Nuclear Information System (INIS)
Ermolaev, B.I.; Troyan, S.I.
2017-01-01
Description of hadronic reactions at high energies is conventionally done in the framework of QCD factorization. All factorization convolutions comprise non-perturbative inputs mimicking non-perturbative contributions and perturbative evolution of those inputs. We construct inputs for the gluon-hadron scattering amplitudes in the forward kinematics and, using the optical theorem, convert them into inputs for gluon distributions in the hadrons, embracing the cases of polarized and unpolarized hadrons. In the first place, we formulate mathematical criteria which any model for the inputs should obey and then suggest a model satisfying those criteria. This model is based on a simple reasoning: after emitting an active parton off the hadron, the remaining set of spectators becomes unstable and therefore it can be described through factors of the resonance type, so we call it the resonance model. We use it to obtain non-perturbative inputs for gluon distributions in unpolarized and polarized hadrons for all available types of QCD factorization: basic, K_T-and collinear factorizations. (orig.)
Impact of gluon polarization on Higgs boson plus jet production at the LHC
Boer, Daniel; Pisano, Cristian
2015-01-01
In this paper we consider Higgs boson plus jet production as a process that is sensitive to the linear polarization of gluons inside the unpolarized protons of the LHC. The leading order expressions for the transverse momentum distribution of the Higgs boson plus jet pair are provided in terms of
Probing Quark-Gluon Interactions with Transverse Polarized Scattering
International Nuclear Information System (INIS)
Rondon, Oscar A.
2011-01-01
Transverse polarized inelastic scattering extends the power of the electromagnetic interaction as a probe of nucleon dynamics beyond the leading order regime explored with longitudinally polarized DIS. In transverse polarized scattering, the twist-3 g 2 spin structure function contributes at the same order as the longitudinal, twist-2, g 1 , so interactions between quarks and gluons can be studied, opening a window on the mechanisms of confinement. This talk reports the results of Jefferson Lab's Resonances Spin Structure experiment measurement of g 2 and the d 2 twist-3 quark matrix element at a four-momentum transfer of 1.3 GeV 2 .
Ball, R D; Ridolfi, G
1996-01-01
We perform a full next-to-leading analysis of the the available experimental data on the polarized structure function g_1 of the nucleon, and give a precise determination of its singlet axial charge together with a thorough assessment of the theoretical uncertainties. We find that the data are now sufficient to separately determine first moments of the polarized quark and gluon distributions and show in particular that the gluon contribution is large and positive.
Regge behaviour of distribution functions and evolution of gluon ...
Indian Academy of Sciences (India)
work we solved DGLAP evolution equation for gluon distribution function at low-x in next-to-leading order (NLO) and the t and x-evolutions of gluon distribution function thus obtained have been compared with global MRST2004 and GRV98 parametrizations. In PQCD, since the higher-order terms in the leading logarithmic.
The gluon distribution at small x - a phenomenological analysis
International Nuclear Information System (INIS)
Harriman, P.N.; Martin, A.D.; Stirling, W.J.; Roberts, R.G.
1990-03-01
The size of the gluon distribution at small χ has important implications for phenomenology at future high energy hadron-hadron and lepton-hadron colliders. We extend a recent global parton distribution fit to investigate the constraints on the gluon from deep inelastic and prompt photon data. In particular, we estimate a band of allowed gluon distributions with qualitatively small-χ behaviour and study the implications of these on a variety of cross sections at high energy pp and ep colliders. (author)
Mechanism of J/PSI production: determining gluon distributions
International Nuclear Information System (INIS)
Nandi, S.; Schneider, H.R.
1978-01-01
Assuming a generalised Drell-Yan type mechanism for hadronic PSI-production, the relative importance of the different possible contributions is estimated from the data. We find that about 80% of the pp → PSI X cross-section is due to gluons. Therefore, these data give some information on the gluon distribution G(x) in the proton. Assuming xG(x) approximately (1-x)sup(n), data restrict n to 4... 6, in agreement with dimensional counting rules. The energy dependence of sigma(anti p p → PSI X)/sigma(pp → PSIX) is predicted. (orig.) [de
Q2 evolution of a soft gluon distribution function
International Nuclear Information System (INIS)
Enkovskij, L.L.; Kotikov, A.V.; Pakkanoni, F.
1992-01-01
Model parameter dependence refferring to the function of gluon distribution linked with the exchange of a dipole pomeron from Q 2 is calculated within the framework of the Gribov-Lipatov-Altarelli-Parisi evolution equation (GLAP) both in the leading logarithm approximation and in the double logarithmic approximation. The behaviour of logarithmic parametrization ∼ (ln(1/x)) b appears to be unstable in relation to perturbative calculations
The three loop two-mass contribution to the gluon vacuum polarization
Energy Technology Data Exchange (ETDEWEB)
Bluemlein, J.; Freitas, A. de; Schoenwald, K. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Schneider, C. [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation (RISC)
2017-10-15
We calculate the two-mass contribution to the 3-loop vacuum polarization of the gluon in Quantum Chromodynamics at virtuality p{sup 2}=0 for general masses and also present the analogous result for the photon in Quantum Electrodynamics.
Scale dependence and small x behaviour of polarized parton distributions
Ball, R D; Ridolfi, G; Forte, S; Ridolfi, G
1995-01-01
We discuss perturbative evolution of the polarized structure function g_1 in the (x,Q^2) plane, with special regard to the small-x region. We determine g_1 in terms of polarized quark and gluon distributions using coefficient functions to order alpha_s. At small x g_1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution.
Regge behaviour of structure function and gluon distribution at low-x in leading order
International Nuclear Information System (INIS)
Sarma, J.K.
2000-01-01
We present a method to find the gluon distribution from the F 2 proton structure function data at low-x assuming the Regge behaviour of the gluon distribution function at this limit. We use the leading order (LO) Altarelli-Parisi (AP) evolution equation in our analysis and compare our result with those of other authors. We also discuss the limitations of the Taylor expansion method in extracting the gluon distribution from the F 2 structure function used by those authors. (orig.)
NLO QCD result for the gluon polarization from open charm $D^{0}$ meson production at COMPASS
Kurek, Krzysztof
2011-01-01
One of the main goals of the COMPASS experiment is the measurement of the gluon contribution to the nucleon spin. Among the processes studied by COMPASS, open- charm $D^{0}$ meson production seems to be the cleanest channel for probing gluons in the energy range covered by the experiment. The gluon polarisation is related to the measured asymmetry for charmed mesons production via the analyzing power (asymmetry at the partonic level) calculated in the perturbative QCD frame. The analyzing power for the "photon-gluon fusion" process corresponds to a LO QCD approximation. The signicant improvement of the statistical precision and the new, nal LO result are presented . The NLO QCD corrections to the partonic cross sections (unpolarised and polarized ones) are now also included into the analysis scheme since these higher order contributions are not negligible. The preliminary NLO QCD result on the gluon polarisation based on a set of measured $D^{0}$ meson asymmetries in kinematical bins of the $D^{0}$ energy amd...
Measurement of gluon polarization through spin asymmetry in the production of charmed mesons
International Nuclear Information System (INIS)
Panebianco, St.
2005-09-01
The main aim of the COMPASS experiment is the measurement of the gluon polarization in the nucleon, which can be accessed by the spin asymmetry in the scattering of a polarized muon beam on a polarized nucleon target. The process sensitive to the gluon polarization is the photon-gluon fusion, which can be tagged in the cleanest way by looking at the production of D 0 mesons. At COMPASS, D 0 mesons are reconstructed from the invariant mass of their decay products. However, it is a rare process, dominated by a large combinatorial background. This thesis presents some studies devoted to the improvement of the charmed mesons reconstruction. The measurement of the efficiency and the space resolution of the 3 drift chamber stations of the COMPASS spectrometer is a necessary step in understanding the performances of the reconstruction of particle trajectories. The hadron identification, which is fundamental in the reconstruction of charmed meson decay, is performed by a RICH detector. A statistical treatment of signal and background, together with an upgrade project to replace the present front-end electronics, have been developed in order to improve the particle identification performances. The second part of this work concerns the spin asymmetry measurement, which requires the application of event selection criteria in order to minimize the noise over signal ratio in the D 0 invariant mass, and the development of event-weighting methods to reduce the statistical error. This work presents a preliminary result, based on 2002-2004 statistics, which is the ΔG/G measurement from open charm production. Although the error bars are large, the measured gluon polarization is compatible with zero. Given the present accuracy, this result is compatible with the existing direct measurements from other channels. However, it does not allow to distinguish between different theoretical models. (author)
International Nuclear Information System (INIS)
Lam, C.S.; Li, B.A.
1980-05-01
A way to detect experimentally the existence of triple gluon coupling and the Adler-Bell-Jackiw anomaly is to measure the Q 2 -dependence of polarized deep inelastic scattering. These effects lead to a ln ln Q 2 term which we calculate by introducing a new gluon operator in the Wilson expansion
Analysis of the proton longitudinal structure function from the gluon distribution function
International Nuclear Information System (INIS)
Boroun, G.R.; Rezaei, B.
2012-01-01
We make a critical, next-to-leading order, study of the relationship between the longitudinal structure function F L and the gluon distribution proposed in Cooper-Sarkar et al. (Z. Phys. C 39:281, 1988; Acta Phys. Pol. B 34:2911 2003), which is frequently used to extract the gluon distribution from the proton longitudinal structure function at small x. The gluon density is obtained by expanding at particular choices of the point of expansion and compared with the hard Pomeron behavior for the gluon density. Comparisons with H1 data are made and predictions for the proposed best approach are also provided. (orig.)
McKinney, Cameron Palmer
In the 1980s, polarized deep inelastic lepton-nucleon scattering experiments revealed that only about a third of the proton's spin of ½ h is carried by the quarks and antiquarks, leaving physicists with the puzzle of how to account for the remaining spin. As gluons carry roughly 50% of the proton's momentum, it seemed most logical to look to the gluon spin as another significant contributor. However, lepton-nucleon scattering experiments only access the gluon helicity distribution, Delta g, through effects on the quark distributions via scaling violations. Constraining Deltag through scaling violations requires experiments that together cover a large range of Q 2. Such experiments had been carried out with unpolarized beams, leaving g(x) (the unpolarized gluon distribution) relatively well-known, but the polarized experiments have only thus far provided weak constraints on Deltag in a limited momentum fraction range. With the commissioning in 2000 of the Relativistic Heavy Ion Collider, the first polarized proton-proton (pp) collider, and the first polarized pp running in 2002, the gluon distributions could be accessed directly by studying quark-gluon and gluon-gluon interactions. In 2009, data from measurements of double longitudinal spin asymmetries, ALL, at the STAR and PHENIX experiments through 2006 were included in a QCD global analysis performed by Daniel de Florian, Rodolfo Sassot, Marco Stratmann, and Werner Vogelsang (DSSV), yielding the first direct constraints on the gluon helicity. The DSSV group found that the contribution of the gluon spin to the proton spin was consistent with zero, but the data provided by PHENIX and STAR was all at mid-rapidity, meaning Delta g was constrained by data only a range in x from 0.05 to 0.2, leaving out helicity contributions from the huge number of low- x gluons. A more recent analysis by DSSV from 2014 including RHIC data through 2009 for the first time points to significant gluon polarization at intermediate
Muoproduction of J/ψ and the gluon distribution of the nucleon
International Nuclear Information System (INIS)
Ashman, J.; Combley, F.; Salmon, D.; Wheeler, S.; Bee, C.P.; Brown, S.C.; Court, G.; Francis, D.; Gabathuler, E.; Gamet, R.; Hayman, P.; Holt, J.R.; Jones, T.; Matthews, M.; Wimpenny, S.J.; Coignet, G.; Toth, J.; Urban, L.; Drees, J.; Edwards, A.W.; Hamacher, K.; Korzen, B.; Kruener, U.; Moenig, K.; Pavel, N.; Peschel, H.; Nassalski, J.; Sandacz, A.; Windmolders, R.; Ernst, T.; Landgraf, U.; Schroeder, T.; Stier, H.E.; Stock, J.; Wallucks, W.
1992-01-01
Measurements are presented of the inclusive distributions of the J/ψ meson produced by muons of energy 200 GeV from an ammonia target. The gluon distribution of the nucleon has been derived from the data in the range 0.04< x<0.36 using a technique based on the colour singlet model. An arbitrary normalisation factor is required to obtain a reasonable integral of the gluon distribution. Some comments are made on the use of J/ψ production by virtual photons to extract the gluon distribution at HERA. (orig.)
Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations
International Nuclear Information System (INIS)
Gary, J. William
1999-01-01
Gluon jets are identified in e + e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP
Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations
Energy Technology Data Exchange (ETDEWEB)
Gary, J. William
1999-03-01
Gluon jets are identified in e{sup +}e{sup -} hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP.
Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations
Energy Technology Data Exchange (ETDEWEB)
Gary, J.W. [California Univ., Riverside, CA (United States). Dept. of Physics
1999-03-01
Gluon jets are identified in e{sup +}e{sup -} hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP. (orig.) 6 refs.
Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations
International Nuclear Information System (INIS)
Gary, J.W.
1999-01-01
Gluon jets are identified in e + e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP. (orig.)
Multiplicity distributions of gluon and quark jets and a test of QCD analytic calculations
Gary, J. William
1999-03-01
Gluon jets are identified in e +e - hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon hets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The mean and first few higher moments of the gluon jet charged particle multiplicity distribution are compared to the analogous results found for light quark (uds) jets, also defined inclusively. Large differences are observed between the mean, skew and curtosis values of the gluon and quark jets, but not between their dispersions. The cumulant factorial moments of the distributions are also measured, and are used to test the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the separated gluon and quark jet cumulant moments compared to a next-to-leading order calculation without energy conservation. There is good quantitative agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets. The data sample used is the LEP-1 sample of the OPAL experiment at LEP.
Spin asymmetry in proton-proton collisions as a probe of sea and gluon polarization in a proton
International Nuclear Information System (INIS)
Cheng, H.; Lai, S.
1990-01-01
Quark and gluon spin densities in a proton are phenomenologically parametrized based on the European Muon Collaboration (EMC) data and on some plausible theoretical arguments. Four different characteristic values of gluon and sea polarizations suggested by various theoretical conjectures are considered. The sea polarization in a proton is probed by measuring the spin-spin asymmetry A LL DY in the Drell-Yan process, while the helicity asymmetry A LL γ in direct photon production at high p T is employed to test the gluon spin content. Helicity asymmetries in both processes are quite sizable. A LL DY is positive and of order 10 -1 if the sea is polarized opposite to the proton spin, as suggested by the EMC data. However, even in the absence of the sea polarization at the EMC energies, we find A LL DY to be large and negative. Experimental measurements of A LL DY and A LL γ together will not only provide a clean probe of sea and gluon polarizations, but also test whether the combination Δs-(α s /4π)ΔG inferred from the EMC data is valid, i.e., whether gluons contribute to the spin-dependent structure function g 1 p (x,Q 2 ) via the triangular anomaly
Wolin, Scott Justin
The PHENIX experiment is one of two detectors located at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, NY. Understanding the spin structure of the proton is a central goal at RHIC, the only polarized proton-on-proton collider in existence. The PHENIX spin program has two primary objectives. The first is to improve the constraints on the polarized parton distributions of the anti-u and anti-d quarks within the proton. The second objective is to improve the constraint on the gluon spin contribution to the proton spin, DeltaG. The focus of this thesis is the second objective. PHENIX experiment has been successful at providing the first meaningful constraints on DeltaG, along with STAR, the other detector located at RHIC. These constraints have, in fact, eliminated the extreme scenarios for gluon polarization through measurements of the double spin asymmetry, ALL, between the cross section of like and unlike sign helicity pp interactions. ALL measurements can be performed with a variety of final states at PHENIX. Until 2009, these final states were only measured for pseudo-rapidities of |eta| Piston Calorimeter (MPC) was installed in 2006 and 2007 at forward rapidity, 3.1 < |eta| < 3.9, with the intention of giving PHENIX the ability to constrain Delta g(x) for x < 0.05. Following this, an electronics upgrade to the MPC will be described which enables the selection of events with two hadrons detected in the MPC. This requirement favors gluons at even lower x than the single hadron event selection. The di-hadron measurement that this upgrade makes possible will allow PHENIX to produce an ALL measurement that constrains Deltag(x) in the range of 5 x 10-4 < x < 0.01. Finally, we discuss the most important systematic uncertainty common to all ALL measurements which arises from the determination of the relative luminosity. A precision ALLL measurement requires measuring the final state yield from the portions of the proton beams that
International Nuclear Information System (INIS)
Greiner, M.; Hofmann, C.; Schaefer, A.; Soff, G.
1994-08-01
The photon-gluon fusion process into a pair of heavy quarks is studied for peripheral Pb+Pb collisions at LHC energies. The double differential cross section with respect to the invariant mass and the rapidity of the produced quark pair at zero rapidity is directly proportional to the gluon distribution in the nuclear medium. Differential cross sections for the b-quark production lie well in the μbarn/GeV regime which will allow the deduction of the gluon distribution at low x. Rapidity cuts for the actual detectors are also considered. (orig.)
Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions
OPAL Collaboration; Ackerstaff, K.; et al.
Gluon jets are identified in e+e^- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observed to provide a much improved description of the data compared to a next-to-leading order calculation without energy conservation. There is agreement between the data and calculations for the ratios of the cumulant moments between gluon and quark jets.
Polarized Parton Distributions at an Electron-Ion Collider
Ball, Richard D.; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2014-01-01
We study the potential impact of inclusive deep-inelastic scattering data from a future electron-ion collider (EIC) on longitudinally polarized parton distribution (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin.
Polarized parton distributions at an electron–ion collider
Energy Technology Data Exchange (ETDEWEB)
Ball, Richard D. [Tait Institute, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh EH9 3JZ, Scotland (United Kingdom); Forte, Stefano [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Guffanti, Alberto [The Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Nocera, Emanuele R. [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Genova (Italy); Rojo, Juan [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland)
2014-01-20
We study the potential impact of inclusive deep-inelastic scattering data from a future electron–ion collider (EIC) on longitudinally polarized parton distributions (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin.
Polarized parton distributions at an electron–ion collider
International Nuclear Information System (INIS)
Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2014-01-01
We study the potential impact of inclusive deep-inelastic scattering data from a future electron–ion collider (EIC) on longitudinally polarized parton distributions (PDFs). We perform a PDF determination using the NNPDF methodology, based on sets of deep-inelastic EIC pseudodata, for different realistic choices of the electron and proton beam energies. We compare the results to our current polarized PDF set, NNPDFpol1.0, based on a fit to fixed-target inclusive DIS data. We show that the uncertainties on the first moments of the polarized quark singlet and gluon distributions are substantially reduced in comparison to NNPDFpol1.0, but also that more measurements may be needed to ultimately pin down the size of the gluon contribution to the nucleon spin
International Nuclear Information System (INIS)
Akimenko, S.A.
1992-01-01
The experiments with various polarized beams and targets for searching spin effects in such processes as χ-, direct photon- and massive lepton-pairs productions are proposed. The goal is to clear up a wide range of problems on the spin-dependent quark and gluon structure functions. 35 refs.; 18 figs.; 5 tabs
Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs
Czech Academy of Sciences Publication Activity Database
Ageev, E.; Alexakhin, V.; Alexandrov, Y.; Alexeev, G.; Amoroso, A.; Badelek, B.; Balestra, F.; Ball, J.; Baum, G.; Bedfer, Y.; Berglund, P.; Bernet, C.; Bertini, R.; Birsa, R.; Bisplinghoff, J.; Bordalo, P.; Bradamante, F.; Bravar, A.; Bressan, A.; Burtin, E.; Bussa, M.; Bytchkov, V.; Cerini, L.; Chapiro, A.; Cicuttin, A.; Colantoni, M.; Colavita, A.; Costa, S.; Crespo, M.; d'Hose, N.; Dalla Torre, S.; Dasgupta, S. S.; De Masi, R.; Dedek, N.; Denisov, O.; Dhara, L.; Diaz Kavka, V.; Dinkelbach, A.; Dolgopolov, A.; Donskov, S.; Dorofeev, V.; Doshita, N.; Duic, V.; Dünnweber, W.; Ehlers, J.; Eversheim, P.; Eyrich, W.; Fabro, M.; Faessler, M.; Falaleev, V.; Fauland, P.; Ferrero, A.; Ferrero, L.; Finger, M.; Finger jr., M.; Fischer, H.; Franz, J.; Friedrich, J.; Frolov, V.; Fuchs, U.; Garfagnini, R.; Gautheron, F.; Gavrichtchouk, O.; Gerassimov, S.; Geyer, R.; Giorgi, M.; Gobbo, B.; Goertz, S.; Gorin, A.; Grajek, O.; Grasso, A.; Grube, B.; Grünemaier, A.; Hannappel, J.; von Harrach, D.; Hasegawa, T.; Hedicke, S.; Heinsius, F.; Hermann, R.; Hess, C.; Hinterberger, F.; von Hodenberg, M.; Horikawa, N.; Horikawa, S.; Ijaduola, R.; Ilgner, C.; Ioukaev, A.; Ishimoto, S.; Ivanov, O.; Iwata, T.; Jahn, R.; Janata, A.; Joosten, R.; Jouravlev, N. I.; Kabuss, E.; Kalinnikov, V.; Kang, D.; Karstens, F.; Kastaun, W.; Ketzer, B.; Khaustov, G.; Khokhlov, Y.; Khomutov, N.; Kisselev, Y.; Klein, F.; Koblitz, S.; Koivuniemi, J.; Kolosov, V.; Komissarov, E.; Kondo, K.; Königsmann, K.; Konoplyannikov, A.; Konorov, I.; Konstantinov, V.; Korentchenko, A.; Korzenev, A.; Kotzinian, A.; Koutchinski, N.; Kowalik, K.; Kravchuk, N.; Krivokhizhin, G.; Kroumchtein, Z.; Kuhn, R.; Kunne, F.; Kurek, K.; Ladygin, M.; Lamanna, M.; Le Goff, J.; Leberig, M.; Lichtenstadt, J.; Liska, T.; Ludwig, I.; Maggiora, A.; Maggiora, M.; Magnon, A.; Mallot, G.; Manuilov, I.; Marchand, C.; Marroncle, J.; Martin, A.; Marzec, J.; Matsuda, T.; Maximov, A.; Medved, K.; Meyer, W.; Mielech, A.; Mikhailov, Y.; Moinester, M.; Nähle, O.; Nassalski, J.; Neliba, S.; Neyret, D.; Nikolaenko, V.; Nozdrin, A.; Obraztsov, V.; Olshevsky, A.; Ostrick, M.; Padee, A.; Pagano, P.; Panebianco, S.; Panzieri, D.; Paul, S.; Pereira, H.; Peshekhonov, D.; Peshekhonov, V.; Piragino, G.; Platchkov, S.; Platzer, K.; Pochodzalla, J.; Polyakov, V.; Popov, A.; Pretz, J.; Quintans, C.; Ramos, S.; Rebourgeard, P.; Reicherz, G.; Reymann, J.; Rith, K.; Rozhdestvensky, A.; Rondio, E.; Sadovski, A.; Saller, E.; Samoylenko, V.; Sandacz, A.; Sans, M.; Sapozhnikov, M.; Savin, I.; Schiavon, P.; Schill, C.; Schmidt, T.; Schmitt, H.; Schmitt, L.; Shevchenko, O.; Shishkin, A.; Siebert, H.; Sinha, L.; Sissakian, A.; Skachkova, A.; Slunecka, M.; Smirnov, G.; Sozzi, F.; Sugonyaev, V.; Srnka, Aleš; Stinzing, F.; Stolarski, M.; Sulc, M.; Sulej, R.; Takabayashi, N.; Tchalishev, V.; Tassarotto, F.; Teufel, A.; Thers, D.; Tkatchev, L.; Toeda, T.; Tretyak, V.; Trousov, S.; Varanda, M.; Virius, M.; Vlassov, N.; Wagner, M.; Webb, R.; Weise, E.; Weitzel, Q.; Wiedner, U.; Wiesmann, M.; Windmolders, R.; Wirth, S.; Wislicki, W.; Zanetti, A.; Zaremba, K.; Zhao, J.; Ziegler, R.; Zvyagin, A.
2006-01-01
Roč. 633, č. 1 (2006), s. 25-32 ISSN 0370-2693 R&D Projects: GA MŠk(CZ) ME 492 Institutional research plan: CEZ:AV0Z20650511 Keywords : nucleon * spin * gluon * polarization * asymmetry * deep inelastic scattering Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 5.043, year: 2006
Multiplicity distributions of gluon and quark jets and tests of QCD analytic predictions
Ackerstaff, K; Allison, J; Altekamp, N; Anderson, K J; Anderson, S; Arcelli, S; Asai, S; Axen, D A; Azuelos, Georges; Ball, A H; Barberio, E; Barlow, R J; Bartoldus, R; Batley, J Richard; Baumann, S; Bechtluft, J; Beeston, C; Behnke, T; Bell, A N; Bell, K W; Bella, G; Bentvelsen, Stanislaus Cornelius Maria; Bethke, Siegfried; Biebel, O; Biguzzi, A; Bird, S D; Blobel, Volker; Bloodworth, Ian J; Bloomer, J E; Bobinski, M; Bock, P; Bonacorsi, D; Boutemeur, M; Bouwens, B T; Braibant, S; Brigliadori, L; 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; Clarke, P E L; Cohen, I; Conboy, J E; Cooke, O C; Cuffiani, M; Dado, S; Dallapiccola, C; Dallavalle, G M; Davis, R; De Jong, S; del Pozo, L A; Desch, Klaus; Dienes, B; Dixit, M S; do Couto e Silva, E; Doucet, M; Duchovni, E; Duckeck, G; Duerdoth, I P; Eatough, D; Edwards, J E G; Estabrooks, P G; Evans, H G; Evans, M; Fabbri, Franco Luigi; Fanti, M; Faust, A A; Fiedler, F; Fierro, M; Fischer, H M; Fleck, I; Folman, R; Fong, D G; Foucher, M; Fürtjes, A; Futyan, D I; Gagnon, P; Gary, J W; Gascon, J; Gascon-Shotkin, S M; Geddes, N I; Geich-Gimbel, C; Geralis, T; Giacomelli, G; Giacomelli, P; Giacomelli, R; Gibson, V; Gibson, W R; Gingrich, D M; Glenzinski, D A; Goldberg, J; Goodrick, M J; Gorn, W; Grandi, C; Gross, E; Grunhaus, Jacob; Gruwé, M; Hajdu, C; Hanson, G G; Hansroul, M; Hapke, M; Hargrove, C K; Hart, P A; 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; Homer, R James; Honma, A K; Horváth, D; Hossain, K R; Howard, R; Hüntemeyer, P; Hutchcroft, D E; Igo-Kemenes, P; Imrie, D C; Ingram, M R; Ishii, K; Jawahery, A; Jeffreys, P W; Jeremie, H; Jimack, Martin Paul; Joly, A; Jones, C R; Jones, G; Jones, M; Jost, U; 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; Kirk, J; Klier, A; Kluth, S; Kobayashi, T; Kobel, M; Koetke, D S; Kokott, T P; Kolrep, M; Komamiya, S; Kress, T; Krieger, P; Von Krogh, J; Kyberd, P; Lafferty, G D; Lahmann, R; Lai, W P; Lanske, D; Lauber, J; Lautenschlager, S R; Layter, J G; Lazic, D; Lee, A M; Lefebvre, E; Lellouch, Daniel; Letts, J; Levinson, L; Lloyd, S L; Loebinger, F K; Long, G D; Losty, Michael J; Ludwig, J; Macchiolo, A; MacPherson, A L; Mannelli, M; Marcellini, S; Markus, 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; Mikenberg, G; Miller, D J; Mincer, A; Mir, R; Mohr, W; Montanari, A; Mori, T; Morii, M; Müller, U; Mihara, S; Nagai, K; Nakamura, I; Neal, H A; Nellen, B; Nisius, R; O'Neale, S W; Oakham, F G; Odorici, F; Ögren, H O; Oh, A; Oldershaw, N J; Oreglia, M J; Orito, S; Pálinkás, J; Pásztor, G; Pater, J R; Patrick, G N; Patt, J; Pearce, M J; Pérez-Ochoa, R; Petzold, S; Pfeifenschneider, P; Pilcher, J E; Pinfold, J L; Plane, D E; Poffenberger, P R; Poli, B; Posthaus, A; Rees, D L; Rigby, D; Robertson, S; Robins, S A; Rodning, N L; Roney, J M; Rooke, A M; Ros, E; Rossi, A M; Routenburg, P; Rozen, Y; Runge, K; Runólfsson, O; Ruppel, U; Rust, D R; Rylko, R; Sachs, K; Saeki, T; Sarkisyan-Grinbaum, E; Sbarra, C; Schaile, A D; Schaile, O; Scharf, F; Scharff-Hansen, P; Schenk, P; Schieck, J; Schleper, P; Schmitt, B; Schmitt, S; Schöning, A; Schröder, M; Schultz-Coulon, H C; Schumacher, M; Schwick, C; Scott, W G; Shears, T G; Shen, B C; Shepherd-Themistocleous, C H; Sherwood, P; Siroli, G P; Sittler, A; Skillman, A; Skuja, A; Smith, A M; Snow, G A; Sobie, Randall J; Söldner-Rembold, S; Springer, R W; Sproston, M; Stephens, K; Steuerer, J; Stockhausen, B; Stoll, K; Strom, D; Szymanski, P; Tafirout, R; Talbot, S D; Tanaka, S; Taras, P; Tarem, S; Teuscher, R; Thiergen, M; Thomson, M A; Von Törne, E; Towers, S; Trigger, I; Trócsányi, Z L; Tsur, E; Turcot, A S; Turner-Watson, M F; Utzat, P; Van Kooten, R; Verzocchi, M; Vikas, P; Vokurka, E H; 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; Wilkens, B; Wilson, G W; Wilson, J A; Wolf, G; Wyatt, T R; Yamashita, S; Yekutieli, G; Zacek, V; Zer-Zion, D
1999-01-01
Gluon jets are identified in e+e- hadronic annihilation events by tagging two quark jets in the same hemisphere of an event. The gluon jet is defined inclusively as all the particles in the opposite hemisphere. Gluon jets defined in this manner have a close correspondence to gluon jets as they are defined for analytic calculations, and are almost independent of a jet finding algorithm. The charged particle multiplicity distribution of the gluon jets is presented, and is analyzed for its mean, dispersion, skew, and curtosis values, and for its factorial and cumulant moments. The results are compared to the analogous results found for a sample of light quark (uds) jets, also defined inclusively. We observe differences between the mean, skew and curtosis values of gluon and quark jets, but not between their dispersions. The cumulant moment results are compared to the predictions of QCD analytic calculations. A calculation which includes next-to-next-to-leading order corrections and energy conservation is observe...
Dynamical behavior connection of the gluon distribution and the proton structure function at small x
International Nuclear Information System (INIS)
Boroun, G.R.
2014-01-01
We make a critical study of the relationship between the singlet structure function F 2 S and the gluon distribution G(x,Q 2 ) proposed in the past two decades, which is frequently used to extract the gluon distribution from the proton structure function. We show that a simple relation is not generally valid in the simplest state. We complete this relation by using a Laplace transform method and hard-pomeron behavior at LO and NLO at small x. Our study shows that this relation is dependent on the splitting functions and initial conditions at Q 2 =Q 2 0 and running coupling constant at NLO. The resulting analytic expression allows us to predict the proton structure function with respect to the gluon distributions and to compare the results with H1 data and a QCD analysis fit. Comparisons with other results are made and predictions for the proposed best approach are also provided. (orig.)
Scale dependence and small-x behaviour of polarized parton distributions
International Nuclear Information System (INIS)
Ball, R.D.; Forte, S.; Ridolfi, G.
1995-01-01
We discuss perturbative evolution of the polarized structure function g 1 in the (x, Q 2 ) plane, with special regard to the small-x region. We determine g 1 in terms of polarized quark and gluon distributions using coefficient functions to order α s . At small x g 1 then displays substantial scale dependence, which necessarily implies a corresponding scale dependence in the large-x region. This scale dependence has significant consequences for the extraction of the first moment from the experimental data, reducing its value while increasing the error. Conversely, the scale dependence may be used to constrain the size of the polarized gluon distribution. ((orig.))
Spin asymmetries for events with high pT hadrons in DIS and an evaluation of the gluon polarization
International Nuclear Information System (INIS)
Adeva, B.; Gallas, A.; Gracia, G.; Plo, M.; Saborido, J.; Arik, E.; Ozben, C.; Unel, G.; Arvidson, A.; Rodriguez, M.; Badelek, B.; Baum, G.; Bueltmann, S.; Tripet, A.; Berglund, P.; Betev, L.; Haft, K.; Staude, A.; Vogt, J.; Birsa, R.
2004-01-01
We present a measurement of the longitudinal spin cross section asymmetry for deep-inelastic muon-nucleon interactions with two high transverse momentum hadrons in the final state. Two methods of event classification are used to increase the contribution of the photon-gluon fusion process to above 30%. The most effective one, based on a neural network approach, provides the asymmetries A p = 0.030±0.057(stat)±0.010(syst) and A d =0.070±0.076(stat)±0.010(syst). From these values we derive an averaged gluon polarization ΔG/G=-0.20±0.28(stat)±0.10(syst) at an average fraction of nucleon momentum carried by gluons =0.07
Directory of Open Access Journals (Sweden)
Nakagawa Itaru
2017-01-01
Full Text Available Two selected topics from the latest RHIC spin results are discussed here. For the transversely polarized spin program, an unexpectedly large single spin asymmetry in the very forward neutron production observed in polarized proton + nucleus collisions at √s = 200 GeV is discussed in this document. For the longitudinal program, the latest highlights from the measurements on the gluon spin components of the proton spin is discussed. After a decade of continuous efforts to hunt for the gluon polarization, the RHIC collaboration is about to catch the tail of the experimental evidence that gluon carries substantially large portion of the proton spin.
Cross-channel analysis of quark and gluon generalized parton distributions with helicity flip
International Nuclear Information System (INIS)
Pire, B.; Semenov-Tian-Shansky, K.; Szymanowski, L.; Wallon, S.
2014-01-01
Quark and gluon helicity flip generalized parton distributions (GPDs) address the transversity quark and gluon structure of the nucleon. In order to construct a theoretically consistent parametrization of these hadronic matrix elements, we work out the set of combinations of those GPDs suitable for the SO(3) partial wave (PW) expansion in the cross-channel. This universal result will help to build up a flexible parametrization of these important hadronic non-perturbative quantities, using, for instance, the approaches based on the conformal PW expansion of GPDs such as the Mellin-Barnes integral or the dual parametrization techniques. (orig.)
Cross-channel analysis of quark and gluon generalized parton distributions with helicity flip
Energy Technology Data Exchange (ETDEWEB)
Pire, B. [CNRS, CPhT, Ecole Polytechnique, Palaiseau (France); Semenov-Tian-Shansky, K. [Universite de Liege, IFPA, Departement AGO, Liege (Belgium); Szymanowski, L. [National Centre for Nuclear Research (NCBJ), Warsaw (Poland); Wallon, S. [Universite de Paris-Sud, CNRS, LPT, Orsay (France); Universite Paris 06, Faculte de Physique, UPMC, Paris (France)
2014-05-15
Quark and gluon helicity flip generalized parton distributions (GPDs) address the transversity quark and gluon structure of the nucleon. In order to construct a theoretically consistent parametrization of these hadronic matrix elements, we work out the set of combinations of those GPDs suitable for the SO(3) partial wave (PW) expansion in the cross-channel. This universal result will help to build up a flexible parametrization of these important hadronic non-perturbative quantities, using, for instance, the approaches based on the conformal PW expansion of GPDs such as the Mellin-Barnes integral or the dual parametrization techniques. (orig.)
Pinning down the large-x gluon with NNLO top-quark pair differential distributions
Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan
2016-01-01
Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work
Muoproduction of J/ψ-mesons and the gluon distribution in nucleons
International Nuclear Information System (INIS)
Jong, Maarten de.
1991-01-01
The cross sections for production of J/ψ-mesons in muon-scattering at hydrogen and deuterium have been measured at a muon-energy of 280 GeV in order to extract from these the momentum distribution of gluons in the nucleon. These cross sections turned out to be equal for protons and neutrons within the experimental error. In the framework of the colour singlet model the gluon distribution has been determined from the cross section for the inelastic production of J/ψ mesons. At small gluon impulses the distribution obtained resembles a brems-strahlung spectrum. This distribution decreases, according to a simple description (counting rules) at larger impulses. The same model however underestimates the cross section for elastic production of J/ψ-mesons seriously. It is found that in inelastic production of J/ψ-mesons both helicities of the meson occur equally. Also a correlation has been observed between the scattering plane and the plane in which the J/ψ meson decays. The production of J/ψ-mesons and ψ'-mesons has been investigated in muon scattering at concrete at the same incoming energy. The measured ratio of their cross sections agrees with the colour singlet model but disagrees with the simplified description which characterizes the 'photon-gluon fusion model'. The possible nuclear-mass dependence of the cross section for J/ψ-meson production has been investigated in interactions of muons with tin and carbon at an energy of 280 GeV. This possible dependence turns out to be absent which means that on the basis of the colour singlet model the distributions of the gluons in the nucleon are equal in tin and carbon. (author). 103 refs.; 60 figs.; 19 tabs
Pinning down the large-x gluon with NNLO top-quark pair differential distributions
International Nuclear Information System (INIS)
Czakon, Michał; Hartland, Nathan P.; Mitov, Alexander; Nocera, Emanuele R.; Rojo, Juan
2017-01-01
Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.
Pinning down the large-x gluon with NNLO top-quark pair differential distributions
Energy Technology Data Exchange (ETDEWEB)
Czakon, Michał [Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen University,D-52056 Aachen (Germany); Hartland, Nathan P. [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands); Mitov, Alexander [Cavendish Laboratory, University of Cambridge,Cambridge CB3 0HE (United Kingdom); Nocera, Emanuele R. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, OX1 3NP, Oxford (United Kingdom); Rojo, Juan [Department of Physics and Astronomy, VU University Amsterdam,De Boelelaan 1081, NL-1081, HV Amsterdam (Netherlands); Nikhef,Science Park 105, NL-1098 XG Amsterdam (Netherlands)
2017-04-10
Top-quark pair production at the LHC is directly sensitive to the gluon PDF at large x. While total cross-section data is already included in several PDF determinations, differential distributions are not, because the corresponding NNLO calculations have become available only recently. In this work we study the impact on the large-x gluon of top-quark pair differential distributions measured by ATLAS and CMS at √s=8 TeV. Our analysis, performed in the NNPDF3.0 framework at NNLO accuracy, allows us to identify the optimal combination of LHC top-quark pair measurements that maximize the constraints on the gluon, as well as to assess the compatibility between ATLAS and CMS data. We find that differential distributions from top-quark pair production provide significant constraints on the large-x gluon, comparable to those obtained from inclusive jet production data, and thus should become an important ingredient for the next generation of global PDF fits.
Efremov, A. V.; Ivanov, N. Ya.; Teryaev, O. V.
2018-05-01
We study the Callan-Gross ratio R = dσL / dσT in heavy-quark pair leptoproduction, lN →l‧ Q Q bar X, as a probe of linearly polarized gluons inside unpolarized proton, where dσT (dσL) is the differential cross section of the γ* N → Q Q bar X process initiated by a transverse (longitudinal) virtual photon. Note first that the maximal value for the quantity R allowed by the photon-gluon fusion with unpolarized gluons is large, about 2. We calculate the contribution of the transverse-momentum dependent gluonic counterpart of the Boer-Mulders function, h1 ⊥g , describing the linear polarization of gluons inside unpolarized proton. Our analysis shows that the maximum value of the ratio R depends strongly on the gluon polarization; it varies from 0 to Q2/4m2 depending on h1⊥g . We conclude that the Callan-Gross ratio in heavy-quark pair leptoproduction is predicted to be large and very sensitive to the contribution of linearly polarized gluons. For this reason, future measurements of the longitudinal and transverse components of the charm and bottom production cross sections at the proposed EIC and LHeC colliders seem to be very promising for determination of the linear polarization of gluons inside unpolarized proton.
Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs
Ageev, E S; Alexandrov, Yu A; Alexeev, G D; Amoroso, A; Badelek, B; Balestra, F; Ball, J; Baum, G; Bedfer, Y; Berglund, P; Bernet, C; Bertini, R; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, Franco; Bravar, A; Bressan, A; Brona, G; Burtin, E; Bussa, M P; Bychkov, V N; Cerini, L; Chapiro, A; Cicuttin, A; Colantoni, M L; Colavita, A A; Costa, S; Crespo, M L; Dalla Torre, S; Das-Gupta, S S; Dedek, N; De Masi, R; Denisov, O Yu; Dhara, L; Díaz, V; Dinkelbach, A M; Dolgopolov, A V; Donskov, S V; Dorofeev, V A; Doshita, N; Duic, V; Dünnweber, W; Ehlers, J; Eversheim, P D; Eyrich, W; Fabro, M; Faessler, Martin A; Falaleev, V; Fauland, P; Ferrero, A; Ferrero, L; Finger, Miroslav H; Finger, M Jr; Fischer, H; Franz, J; Friedrich, J M; Frolov, V; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S G; Geyer, R; Giorgi, M; Gobbo, B; Görtz, S; Gorin, A M; Grajek, O A; Grasso, A; Grube, B; Grünemaier, A; Hannappel, J; Von Harrach, D; Hasegawa, T; Hedicke, S; Heinsius, F H; Hermann, R; Hess, C; Hinterberger, F; Von Hodenberg, M; Horikawa, N; Horikawa, S; D'Hose, N; Ijaduola, R B; Ilgner, C; Ioukaev, A I; Ishimoto, S; Ivanov, O; Iwata, T; Jahn, R; Janata, A; Joosten, R; Jouravlev, N I; Kabuss, E M; Kalinnikov, V; Kang, D; Karstens, F; Kastaun, W; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Khomutov, N V; Kisselev, Yu V; Klein, F; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Komissarov, E V; Kondo, K; Königsmann, K C; Konoplyannikov, A K; Konorov, I; Konstantinov, V F; Korentchenko, A S; Korzenev, A; Kotzinian, A M; Koutchinski, N A; Kowalik, K L; Kravchuk, N P; Krivokhizhin, V G; Krumshtein, Z; Kühn, R; Kunne, Fabienne; Kurek, K; Ladygin, M E; Lamanna, M; Leberig, M; Le Goff, J M; Lichtenstadt, J; Liska, T; Ludwig, I; Maggiora, A; Maggiora, M; Magnon, A; Mallot, G K; Manuilov, I V; Marchand, C; Marroncle, J; Martin, A; Marzec, J; Matsuda, T; Maksimov, A N; Medved, K S; Meyer, W; Mielech, A; Mikhailov, Yu V; Moinester, M A; Nahle, O; Nassalski, J P; Neliba, S; Neyret, D P; Nikolaenko, V I; Nozdrin, A A; Obraztsov, V F; Olshevskii, A G; Ostrick, M; Padee, A; Pagano, P; Panebianco, S; Panzieri, D; Paul, S; Pereira, H D; Peshekhonov, V D; Piragino, G; Platchkov, S; Platzer, K; Pochodzalla, J; Polyakov, V A; Popov, A A; Pretz, J; Procureur, S; Quintans, C; Ramos, S; Rebourgeard, P C; Reicherz, G; Reymann, J; Rith, K; Rondio, Ewa; Rozhdestvensky, A M; Sadovski, A B; Saller, E; Samoylenko, V D; Sandacz, A; Sans, M; Sapozhnikov, M G; Savin, I A; Schiavon, Paolo; Schill, C; Schmidt, T; Schmitt, H; Schmitt, L; Shevchenko, O Yu; Shishkin, A A; Siebert, H W; Sinha, L; Sissakian, A N; Skachkova, A N; Slunecka, M; Smirnov, G I; Sozzi, F; Srnka, A; Stinzing, F; Stolarski, M; Sugonyaev, V P; Sulc, M; Sulej, R; Takabayashi, N; Tchalishev, V V; Tessarotto, F; Teufel, A; Thers, D; Tkatchev, L G; Toeda, T; Tretyak, V I; Trousov, S; Varanda, M; Virius, M; Vlassov, N V; Wagner, M; Webb, R; Weise, E; Weitzel, Q; Wiedner, U; Wiesmann, M; Windmolders, R; Wirth, S; Wislicki, W; Zanetti, A M; Zaremba, K; Zhao, J; Ziegler, R; Zvyagin, A
2006-01-01
We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2 = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.
Energy Technology Data Exchange (ETDEWEB)
D' Enterria, David, E-mail: dde@cern.ch [CERN, PH Department, CH-1211 Geneva 23 (Switzerland); ICREA and ICC-UB, Universitat de Barcelona, 08028 Barcelona, Catalonia (Spain); Rojo, Juan [CERN, PH Department, TH Unit, CH-1211 Geneva 23 (Switzerland)
2012-07-21
The impact of isolated-photon data from proton-(anti)proton collisions at RHIC, Spp{sup Macron }S, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-{gamma} measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20%) of its uncertainties around fractional momenta x Almost-Equal-To 0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20% at the LHC. We conclude that present and future isolated-photon measurements constitute an interesting addition to coming global PDF analyses.
d'Enterria, David
2012-01-01
The impact of isolated-photon data from proton-(anti)proton collisions at RHIC, SppbarS, Tevatron and LHC energies, on the parton distribution functions of the proton is studied using a recently developed Bayesian reweighting method. The impact on the gluon density of the 35 existing isolated-gamma measurements is quantified using next-to-leading order (NLO) perturbative QCD calculations complemented with the NNPDF2.1 parton densities. The NLO predictions are found to describe well most of the datasets from 200 GeV up to 7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at the LHC are precise enough to constrain the gluon distribution and lead to a moderate reduction (up to 20%) of its uncertainties around fractional momenta x~0.02. As a particular case, we show that the improved gluon density reduces the PDF uncertainty for the Higgs boson production cross section in the gluon-fusion channel by more than 20% at the LHC. We conclude that present and future isolated-photon measuremen...
Heavy-quark hadroproduction in kT-factorization approach with unintegrated gluon distributions
International Nuclear Information System (INIS)
Shabelski, Yu.M.; Shuvaev, A.G.
2006-01-01
The processes of heavy-quark production using the unintegrated gluon distributions are considered. The numerical predictions for high-energy nucleon-nucleon and photon-nucleon collisions of the k T -factorization approach (semihard theory) are compared with the experimental data from Tevatron collider and HERA. The total production cross sections and p T distributions are considered and they are in reasonable agreement with the data for reasonable values of QCD scale [ru
Gluon distributions in nucleons and pions at a low resolution scale
International Nuclear Information System (INIS)
Christiansen, H.R.
2000-10-01
In this paper we study the gluon distribution functions in nucleons and pions at a low resolution Q 2 scale. This is an important issue since parton densities at low Q 2 have always been taken as an external input which is adjusted through DGLAP evolution to fit the experimental data at higher scales. Here, in the framework of a model recently developed, it is shown that the hypothetical cloud of neutral pions surrounding nucleons and pions appears to be responsible for the characteristic valence-like gluon distributions needed at the initial low scale. As an additional result, we get the remarkable prediction that neutral and charged ions have different intrinsic sea flavor contents. (author)
International Nuclear Information System (INIS)
Koller, K.; Krasemann, H.
1979-08-01
We investigate the Dalitz plot population and thrust angular distribution for the Orthoquarkonium decay Q anti Q → 3 scalar gluons. The Dalitz plot for scalar gluons is populated in corners where events are 2 jet like and this disagrees with existing Upsilon data. The scalar gluon thrust angular distribution is also in striking disagreement with the UPSILON data and so scalar gluons are completely ruled out. (orig.)
Pire, B.; Szymanowski, L.
2017-12-01
We calculate at the leading order in αs the QCD amplitude for exclusive neutrino production of a D* or Ds* charmed vector meson on a nucleon. We work in the framework of the collinear QCD approach where generalized parton distributions (GPDs) factorize from perturbatively calculable coefficient functions. We include O (mc) terms in the coefficient functions and the O (mD) term in the definition of heavy meson distribution amplitudes. The show that the analysis of the angular distribution of the decay D(s) *→D(s )π allows us to access the transversity gluon GPDs.
Unbiased determination of polarized parton distributions and their uncertainties
Energy Technology Data Exchange (ETDEWEB)
Ball, Richard D. [Tait Institute, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh EH9 3JZ, Scotland (United Kingdom); Forte, Stefano, E-mail: forte@mi.infn.it [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Guffanti, Alberto [The Niels Bohr International Academy and Discovery Center, The Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Nocera, Emanuele R. [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Genova (Italy); Rojo, Juan [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland)
2013-09-01
We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations.
Unbiased determination of polarized parton distributions and their uncertainties
International Nuclear Information System (INIS)
Ball, Richard D.; Forte, Stefano; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2013-01-01
We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, test for its stability upon various modifications of the fitting procedure, and compare it to other recent polarized parton sets, and in particular obtain predictions for polarized first moments of PDFs based on it. We find that the uncertainties on the gluon, and to a lesser extent the strange PDF, were substantially underestimated in previous determinations
Soft gluon resummation of Drell-Yan rapidity distributions: Theory and phenomenology
International Nuclear Information System (INIS)
Bonvini, Marco; Forte, Stefano; Ridolfi, Giovanni
2011-01-01
We examine critically the theoretical underpinnings and phenomenological implications of soft gluon (threshold) resummation of rapidity distributions at a hadron collider, taking Drell-Yan production at the Tevatron and the LHC as a reference test case. First, we show that in perturbative QCD soft gluon resummation is necessary whenever the partonic (rather the hadronic) center-of-mass energy is close enough to threshold, and we provide tools to assess when resummation is relevant for a given process. Then, we compare different prescriptions for handling the divergent nature of the series of resummed perturbative corrections, specifically the minimal and Borel prescriptions. We assess the intrinsic ambiguities of resummed results, both due to the asymptotic nature of their perturbative expansion, and to the treatment of subleading terms. Turning to phenomenology, we introduce a fast and accurate method for the implementation of resummation with the minimal and Borel prescriptions using an expansion on a basis of Chebyshev polynomials. We then present results for W and Z production as well as both high- and low-mass dilepton pairs at the LHC, and show that soft gluon resummation effects are generally comparable in size to NNLO corrections, but sometimes affected by substantial ambiguities.
Three gluon jets as a test of QCD
International Nuclear Information System (INIS)
Koller, K.; Walsh, T.F.
1977-10-01
As a test of quantum chromodynamics (QCD), we suggest looking for gluon jets in the decay of a heavy quark-antiquark bound state produced in e + e - -annihilation, Q anti Q → 3 gluons → 3 gluon jets. In particular, we point out that these events form a jet Dalitz plot, and we calculate the gluon or jet distributions (including the effect of polarized e + e - -beams). This process affords a test of the gluon spin. It is the analogue of two-jet angular distributions in e + e - %→ q anti q → 2 quark jets. We also estimate multiplicities and momentum distributions of hadrons in Q anti Q → 3 gluons → hadrons, using the recently discovered UPSILON (9.4) as an example. (orig.) [de
Asymmetry distributions and mass effects in dijet-events at a polarized HERA
Maul, M; Mirkes, E; Rädel, G
1998-01-01
The asymmetry distributions for several kinematic variables are considered for finding a systematic way to maximize the signal for the extraction of the polarized gluon density. The relevance of mass effects for the corresponding dijet cross section is discussed and the different approximations for including mass effects are compared. We also compare via the programs PEPSI and MEPJET two different Monte Carlo (MC) approaches for simulating the expected signal in the dijet asymmetry at a polarized HERA.
Energy Technology Data Exchange (ETDEWEB)
Kanki, T [Osaka Univ., Toyonaka (Japan). Coll. of General Education
1976-12-01
We present a quark-gluon-parton model in which quark-partons and gluons make clusters corresponding to two or three constituent quarks (or anti-quarks) in the meson or in the baryon, respectively. We explicitly construct the constituent quark state (cluster), by employing the Kuti-Weisskopf theory and by requiring the scaling. The quark additivity of the hadronic total cross sections and the quark counting rules on the threshold powers of various distributions are satisfied. For small x (Feynman fraction), it is shown that the constituent quarks and quark-partons have quite different probability distributions. We apply our model to hadron-hadron inclusive reactions, and clarify that the fragmentation and the diffractive processes relate to the constituent quark distributions, while the processes in or near the central region are controlled by the quark-partons. Our model gives the reasonable interpretation for the experimental data and much improves the usual ''constituent interchange model'' result near and in the central region (x asymptotically equals x sub(T) asymptotically equals 0).
Energy Technology Data Exchange (ETDEWEB)
Panebianco, St
2005-09-15
The main aim of the COMPASS experiment is the measurement of the gluon polarization in the nucleon, which can be accessed by the spin asymmetry in the scattering of a polarized muon beam on a polarized nucleon target. The process sensitive to the gluon polarization is the photon-gluon fusion, which can be tagged in the cleanest way by looking at the production of D{sup 0} mesons. At COMPASS, D{sup 0} mesons are reconstructed from the invariant mass of their decay products. However, it is a rare process, dominated by a large combinatorial background. This thesis presents some studies devoted to the improvement of the charmed mesons reconstruction. The measurement of the efficiency and the space resolution of the 3 drift chamber stations of the COMPASS spectrometer is a necessary step in understanding the performances of the reconstruction of particle trajectories. The hadron identification, which is fundamental in the reconstruction of charmed meson decay, is performed by a RICH detector. A statistical treatment of signal and background, together with an upgrade project to replace the present front-end electronics, have been developed in order to improve the particle identification performances. The second part of this work concerns the spin asymmetry measurement, which requires the application of event selection criteria in order to minimize the noise over signal ratio in the D{sup 0} invariant mass, and the development of event-weighting methods to reduce the statistical error. This work presents a preliminary result, based on 2002-2004 statistics, which is the {delta}G/G measurement from open charm production. Although the error bars are large, the measured gluon polarization is compatible with zero. Given the present accuracy, this result is compatible with the existing direct measurements from other channels. However, it does not allow to distinguish between different theoretical models. (author)
International Nuclear Information System (INIS)
Schmieden, Kristof
2013-04-01
The measurement of the effective weak mixing angle with the ATLAS experiment at the LHC is presented. It is extracted from the forward-backward asymmetry in the polar angle distribution of the muons originating from Z boson decays in the reaction pp→Z/γ * +X→ μ + μ - +X. In total 4.7 fb -1 of proton-proton collisions at √(s)=7 TeV are analysed. In addition, the full polar and azimuthal angular distributions are measured as a function of the transverse momentum of the Z/γ * system and are compared to several simulations as well as recent results obtained in p anti p collisions. Finally, the angular distributions are used to confirm the spin of the gluon using the Lam-Tung relation.
Rapidity distribution of photons from an anisotropic quark-gluon plasma
International Nuclear Information System (INIS)
Bhattacharya, Lusaka; Roy, Pradip
2010-01-01
We calculate rapidity distribution of photons due to Compton and annihilation processes from quark gluon plasma with pre-equilibrium momentum-space anisotropy. We also include contributions from hadronic matter with late-stage transverse expansion. A phenomenological model has been used for the time evolution of hard momentum scale, p hard (τ), and anisotropy parameter, ξ(τ). As a result of pre-equilibrium momentum-space anisotropy, we find significant modification of photons rapidity distribution. For example, with the fixed initial condition (FIC) free-streaming (δ=2) interpolating model we observe significant enhancement of photon rapidity distribution at fixed p T , where as for FIC collisionally broadened (δ=2/3) interpolating model the yield increases till y∼1. Beyond that suppression is observed. With fixed final multiplicity (FFM) free-streaming interpolating model we predict enhancement of photon yield which is less than the case of FIC. Suppression is always observed for FFM collisionally broadened interpolating model.
Globally Polarized Quark-gluon Plasma in Non-central A+ACollisions
Energy Technology Data Exchange (ETDEWEB)
Liang, Zuo-tang; Wang, Xin-Nian
2004-10-01
Produced partons have large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of non-central heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling.Such global quark polarization will lead to many observable consequences,such as left-right asymmetry of hadron spectra, global transverse polarization of thermal photons, dileptons and hadrons. Hadrons from the decay of polarized resonances will have azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is predicted with indifferent hadronization scenarios and can be easily tested.
The Higgs transverse momentum distribution in gluon fusion as multiscale problem
International Nuclear Information System (INIS)
Bagnaschi, E.; Vicini, A.
2015-05-01
We consider Higgs production in gluon fusion and in particular the prediction of the Higgs transverse momentum distribution. We discuss the ambiguities affecting the matching procedure between fixed order matrix elements and the resummation to all orders of the terms enhanced by log(p H T /m H ) factors. Following a recent proposal (Grazzini et al., hep-ph/1306.4581), we argue that the gluon fusion process, computed considering two active quark flavors, is a multiscale problem from the point of view of the resummation of the collinear singular terms. We perform an analysis at parton level of the collinear behavior of the real emission amplitudes and we derive an upper limit to the range of transverse momenta where the collinear approximation is valid. This scale is then used as the value of the resummation scale in the analytic resummation framework or as the value of the h parameter in the POWHEG-BOX code. Finally, we provide a phenomenological analysis in the Standard Model, in the Two Higgs Doublet Model and in the Minimal Supersymmetric Standard Model. In the two latter cases, we provide an ansatz for the central value of the matching parameters not only for a Standard Model-like Higgs boson, but also for heavy scalars and in scenarios where the bottom quark may play the dominant role.
Transverse momentum dependent quark distributions and polarized Drell-Yan processes
Zhou, Jian; Yuan, Feng; Liang, Zuo-Tang
2009-01-01
We study the spin-dependent quark distributions at large transverse momentum. We derive their transverse momentum behaviors in the collinear factorization approach in this region. We further calculate the angular distribution of the Drell-Yan lepton pair production with polarized beams and present the results in terms of the collinear twist-three quark-gluon correlation functions. In the intermediate transverse momentum region, we find that the two pproaches: the collinear factorization and t...
Phenomenology of gluon TMDs at NNLL
Garcia, M.
2015-01-01
All the leading-Twist (un)polarized gluon transverse momentum dependent parton distribution functions have the same evolution, once they are properly defined in order to cancel spurious rapidity divergences. Currently known perturbative ingredients can be used to resum large logarithms up to
Unintegrated gluon distributions in D*± and dijet associated photoproduction at HERA
International Nuclear Information System (INIS)
Lipatov, A.V.; Zotov, N.P.
2006-01-01
We consider the photoproduction of D *± mesons associated with two hadron jets at HERA collider in the framework of the k T -factorization approach. The unintegrated gluon densities in a proton are obtained from the full CCFM, from unified BFKL-DGLAP evolution equations as well as from the Kimber-Martin-Ryskin prescription. Resolved photon contributions are reproduced by the initial-state gluon radiation. We investigate different production rates and make a comparison with the recent experimental data taken by the ZEUS collaboration. Special attention is given to the specific dijet correlations which can provide unique information about non-collinear gluon evolution dynamics. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Sichtermann, Ernst
2016-12-15
The fundamental structure of nucleons and nuclear matter is described by the properties and dynamics of quarks and gluons in quantum chromodynamics. Electron-nucleon collisions are a powerful method to study this structure. As one increases the energy of the collisions, the interaction process probes regions of progressively higher gluon density. This density must eventually saturate. An high-energy polarized Electron-Ion Collider (EIC) has been proposed to observe and study the saturated gluon density regime. Selected measurements will be discussed, following a brief introduction.
International Nuclear Information System (INIS)
Weiler, T.
1981-01-01
An overview is presented of the attributes of gluons, deducible from experimental data. Particular attention is given to the photon-gluon fusion model of charm leptoproduction. The agreement with QCD and theoretical prejudice is qualitatively good
Heavy Flavour Production as Probe of Gluon Sivers Function
International Nuclear Information System (INIS)
Godbole, Rohini M.; Kaushik, Abhiram; Misra, Anuradha; Rawoot, Vaibhav; Sonawane, Bipin
2017-01-01
Heavy flavour production like J/ψ and D-meson production in scattering of electrons/unpolarized protons off polarized proton target offer promising probes to investigate gluon Sivers function. In this talk, I will summarize our recent work on transverse single spin asymmetry in J/ψ-production and D-meson production in pp↑ scattering using a generalized parton model approach. We compare predictions obtained using different models of gluon Sivers function within this approach and then, taking into account the transverse momentum dependent evolution of the unpolarized parton distribution functions and gluon Sivers function, we study the effect of evolution on asymmetry. (author)
On positivity of parton distributions
International Nuclear Information System (INIS)
Altarelli, G.; Forte, S.; Ridolfi, G.
1998-01-01
We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at leading order when all quark and gluon distributions are defined in terms of suitable physical processes. We specify a convenient physical definition for the polarized and unpolarized gluon distributions in terms of Higgs production from gluon fusion. We show that these bounds are modified by subleading corrections, and we determine them up to NLO. We examine the ensuing phenomenological implications, in particular in view of the determination of the polarized gluon distribution. (orig.)
On positivity of parton distributions
Altarelli, Guido; Ridolfi, G; Altarelli, Guido; Forte, Stefano; Ridolfi, Giovanni
1998-01-01
We discuss the bounds on polarized parton distributions which follow from their definition in terms of cross section asymmetries. We spell out how the bounds obtained in the naive parton model can be derived within perturbative QCD at leading order when all quark and gluon distributions are defined in terms of suitable physical processes. We specify a convenient physical definition for the polarized and unpolarized gluon distributions in terms of Higgs production from gluon fusion. We show that these bounds are modified by subleading corrections, and we determine them up to NLO. We examine the ensuing phenomenological implications, in particular in view of the determination of the polarized gluon distribution.
Are the gluon distributions different in π- and K-mesons?
International Nuclear Information System (INIS)
Batunin, A.V.; Likhoded, A.K.; Kiselev, V.V.
1988-01-01
The experimental data an excess of D-meson production in K - -beam as compared with π - one (NA32 collaboration) is discussed. Such a situation is shown to be possible at larger total number of gluons in K-meson only. However, this is in a disagreemtn with other charm production experiments
Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase distribution
International Nuclear Information System (INIS)
Gossiaux, Pol Bernard; Guiho, Vincent; Aichelin, Joerg
2005-01-01
We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of J/ψ production (integrated and differential) stemming from c-c-bar pairs that are initially uncorrelated
International Nuclear Information System (INIS)
Block, Martin M.; Durand, Loyal
2011-01-01
We recently derived a very accurate and fast new algorithm for numerically inverting the Laplace transforms needed to obtain gluon distributions from the proton structure function F 2 γp (x,Q 2 ). We numerically inverted the function g(s), s being the variable in Laplace space, to G(v), where v is the variable in ordinary space. We have since discovered that the algorithm does not work if g(s)→0 less rapidly than 1/s as s→∞, e.g., as 1/s β for 0 β-1 and a polynomial in v. We test the algorithm numerically for very small positive β, β=10 -6 obtaining numerical results that imitate the Dirac delta function δ(v). We also devolve the published MSTW2008LO gluon distribution at virtuality Q 2 =5 GeV 2 down to the lower virtuality Q 2 =1.69 GeV 2 . For devolution, β is negative, giving rise to inverse Laplace transforms that are distributions and not proper functions. This requires us to introduce the concept of Hadamard Finite Part integrals, which we discuss in detail. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Schmieden, Kristof
2013-04-15
The measurement of the effective weak mixing angle with the ATLAS experiment at the LHC is presented. It is extracted from the forward-backward asymmetry in the polar angle distribution of the muons originating from Z boson decays in the reaction pp{yields}Z/{gamma}{sup *}+X{yields} {mu}{sup +}{mu}{sup -}+X. In total 4.7 fb{sup -1} of proton-proton collisions at {radical}(s)=7 TeV are analysed. In addition, the full polar and azimuthal angular distributions are measured as a function of the transverse momentum of the Z/{gamma}{sup *} system and are compared to several simulations as well as recent results obtained in p anti p collisions. Finally, the angular distributions are used to confirm the spin of the gluon using the Lam-Tung relation.
Quarks and gluons in hadrons and nuclei
International Nuclear Information System (INIS)
Close, F.E.
1989-12-01
These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. This lecture discusses the distribution functions of quarks and gluons in nucleons and nuclei, and how knowledge of these is necessary before some quark-gluon plasma searches can be analyzed. 56 refs., 2 figs
International Nuclear Information System (INIS)
Boroun, G.R.
2005-01-01
An approximation method based on Regge behavior is presented. This new method relates the reduced cross section derivative and the structure function Regge behavior at low x. With the use of this approximation method, the C and λ parameters are calculated from the HERA reduced cross section data taken at low-x. Also, we calculate the structure functions F 2 (x,Q 2 ) even for low-x values, which have not been investigated. To test the validity of calculated structure functions, we find the gluon distribution function in the Leading order approximation based on Regge behaviour of structure function and compare to the NLO QCD fit to H1 data and NLO parton distribution function.
ATLAS, Collaboration
2013-01-01
Expected distributions of the test statistics q=log(L(0^+)/L(2^+)) for the spin-0 and spin-2 (produced by gluon fusion) hypotheses. The observed value is indicated by a vertical line. The coloured areas correspond to the integrals of the expected distributions used to compute the p-values for the rejection of each hypothesis.
QCD Analysis of Polarized Scattering Data and New Polarized Parton Distributions
International Nuclear Information System (INIS)
Bluemlein, J.; Boettcher, H.
2002-01-01
In this talk results from a new QCD analysis in Leading (LO) and Next-to-Leading (NLO) Order are presented. New parametrizations of the polarized quark and gluon densities are derived together with parametrizations of their fully correlated 1σ error bands. Furthermore the value of α s (M 2 Z ) is determined. Finally a number of low moments of the polarized parton densities are compared with results from lattice simulations. All details of the analysis are given in J. Bluemlein, H. Boettcher, Nucl. Phys. B636, 225 (2002). (author)
Directory of Open Access Journals (Sweden)
V.P. Gonçalves
2017-05-01
Full Text Available The exclusive vector meson production cross section is one of the most promising observables to probe the high energy regime of the QCD dynamics. In particular, the squared momentum transfer (t distributions are an important source of information about the spatial distribution of the gluons in the hadron and about fluctuations of the color fields. In this paper we complement previous studies on exclusive vector meson photoproduction in hadronic collisions presenting a comprehensive analysis of the t-spectrum measured in exclusive ρ, ϕ and J/Ψ photoproduction in pp and PbPb collisions at the LHC. We compute the differential cross sections taking into account gluon saturation effects and compare the predictions with those obtained in the linear regime of the QCD dynamics. Our results show that gluon saturation suppresses the magnitude of the cross sections and shifts the position of the dips towards smaller values of t.
Energy Technology Data Exchange (ETDEWEB)
Block, Martin M. [Northwestern University, Department of Physics and Astronomy, Evanston, IL (United States); Durand, Loyal [University of Wisconsin, Department of Physics, Madison, WI (United States)
2011-11-15
We recently derived a very accurate and fast new algorithm for numerically inverting the Laplace transforms needed to obtain gluon distributions from the proton structure function F{sub 2}{sup {gamma}}{sup p}(x,Q{sup 2}). We numerically inverted the function g(s), s being the variable in Laplace space, to G(v), where v is the variable in ordinary space. We have since discovered that the algorithm does not work if g(s){yields}0 less rapidly than 1/s as s{yields}{infinity}, e.g., as 1/s{sup {beta}} for 0 <{beta}<1. In this note, we derive a new numerical algorithm for such cases, which holds for all positive and non-integer negative values of {beta}. The new algorithm is exact if the original function G(v) is given by the product of a power v{sup {beta}}{sup -1} and a polynomial in v. We test the algorithm numerically for very small positive {beta}, {beta}=10{sup -6} obtaining numerical results that imitate the Dirac delta function {delta}(v). We also devolve the published MSTW2008LO gluon distribution at virtuality Q{sup 2}=5 GeV{sup 2} down to the lower virtuality Q{sup 2}=1.69 GeV{sup 2}. For devolution, {beta} is negative, giving rise to inverse Laplace transforms that are distributions and not proper functions. This requires us to introduce the concept of Hadamard Finite Part integrals, which we discuss in detail. (orig.)
International Nuclear Information System (INIS)
Schiller, D.H.; Koerner, J.G.
1981-07-01
We develop the helicity description for the processes e + e - → qanti qg and e + e - → Qanti Q(1 -- ) → ggg(γgg) in the purely electromagnetic case, in the γ-Z 0 interference region and on the Z 0 -pole. We present complete differential cross section formulas including beam, quark and gluon polarization effects. We also treat the corresponding processes e + e - → qanti qS and e + e - → Qanti Q(1 -- ) → SSS(γSS) involving scalar gluons. (orig.)
Are Parton Distributions Positive?
Forte, Stefano; Ridolfi, Giovanni; Altarelli, Guido; Forte, Stefano; Ridolfi, Giovanni
1999-01-01
We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the leading log level if the quark and gluon distribution are defined in terms of physical processes. We show how these conditions are modified at the next-to-leading level, and discuss their phenomenological implications, in particular in view of the determination of the polarized gluon distribution
Are parton distributions positive?
International Nuclear Information System (INIS)
Forte, Stefano; Altarelli, Guido; Ridolfi, Giovanni
1999-01-01
We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the leading log level if the quark and gluon distribution are defined in terms of physical processes. We show how these conditions are modified at the next-to-leading level, and discuss their phenomenological implications, in particular in view of the determination of the polarized gluon distribution
International Nuclear Information System (INIS)
Wang Fan; Sun Weimin; Chen Xiangsong; Lu Xiaofu; Goldman, T.
2009-01-01
It is unavoidable to deal with the quark and gluon momentum and angular momentum contributions to the nucleon momentum and spin in the study of nucleon internal structure. However we never have the quark and gluon momentum, orbital angular momentum and gluon spin operators which satisfy both the gauge invariance and the canonical momentum and angular momentum commutation relation. The conflicts between the gauge invariance and canonical quantization requirement of these operators are discussed. A new set of quark and gluon momentum, orbital angular momentum and spin operators, which satisfy both the gauge invariance and canonical momentum and angular momentum commutation relation, are proposed. The key point to achieve such a proper decomposition is to separate the gauge field into the pure gauge and the gauge covariant parts. The same conflicts also exist in QED and quantum mechanics and have been solved in the same manner. The impacts of this new decomposition to the nucleon internal structure are discussed. (authors)
The gluon structure of hadrons and nuclei from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Shanahan, Phiala A. [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
2018-04-01
I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.
The gluon structure of hadrons and nuclei from lattice QCD
Shanahan, Phiala
2018-03-01
I discuss recent lattice QCD studies of the gluon structure of hadrons and light nuclei. After very briefly highlighting new determinations of the gluon contributions to the nucleon's momentum and spin, presented by several collaborations over the last year, I describe first calculations of gluon generalised form factors. The generalised transversity gluon distributions are of particular interest since they are purely gluonic; they do not mix with quark distributions at leading twist. In light nuclei they moreover provide a clean signature of non-nucleonic gluon degrees of freedom, and I present the first evidence for such effects, based on lattice QCD calculations. The planned Electron-Ion Collider, designed to access gluon structure quantities, will have the capability to test this prediction, and measure a range of gluon observables including generalised gluon distributions and transverse momentum dependent gluon distributions, within the next decade.
Photon beam polarization and non-dipolar angular distributions
International Nuclear Information System (INIS)
Peshkin, M.
1996-01-01
Angular distributions of ejecta from unoriented atoms and molecules depend upon the polarization state of the incident x-rays as well as upon the dynamics of the physical systems being studied. I recommend a simple geometrical way of looking at the polarization and its effects upon angular distributions. The polarization is represented as a vector in a parameter space that faithfully represents the polarization of the beam. The simple dependence of the angular dependence of the angular distributions on the polarization vector enables easy extraction of the dynamical information contained in those angular distributions. No new physical results emerge from this geometrical approach, but known consequences of the symmetries appear in an easily visualized form that I find pleasing and that has proved to be useful for planning experiments and for analyzing data
Unbiased determination of polarized parton distributions and their uncertainties
Ball, Richard D.; Guffanti, Alberto; Nocera, Emanuele R.; Ridolfi, Giovanni; Rojo, Juan
2013-01-01
We present a determination of a set of polarized parton distributions (PDFs) of the nucleon, at next-to-leading order, from a global set of longitudinally polarized deep-inelastic scattering data: NNPDFpol1.0. The determination is based on the NNPDF methodology: a Monte Carlo approach, with neural networks used as unbiased interpolants, previously applied to the determination of unpolarized parton distributions, and designed to provide a faithful and statistically sound representation of PDF uncertainties. We present our dataset, its statistical features, and its Monte Carlo representation. We summarize the technique used to solve the polarized evolution equations and its benchmarking, and the method used to compute physical observables. We review the NNPDF methodology for parametrization and fitting of neural networks, the algorithm used to determine the optimal fit, and its adaptation to the polarized case. We finally present our set of polarized parton distributions. We discuss its statistical properties, ...
Hydrogen Distribution in the Lunar Polar Regions
Sanin, A. B.; Mitrofanov, I. G.; Litvak, M. L.; Bakhtin, B. N.; Bodnarik, J. G.; Boynton, W. V.; Chin, G.; Evans, L. G.; Harshmann, K.; Fedosov, F.;
2016-01-01
We present a method of conversion of the lunar neutron counting rate measured by the Lunar Reconnaissance Orbiter (LRO) Lunar Exploration Neutron Detector (LEND) instrument collimated neutron detectors, to water equivalent hydrogen (WEH) in the top approximately 1 m layer of lunar regolith. Polar maps of the Moon’s inferred hydrogen abundance are presented and discussed.
Massively Parallel Polar Decomposition on Distributed-Memory Systems
Ltaief, Hatem; Sukkari, Dalal E.; Esposito, Aniello; Nakatsukasa, Yuji; Keyes, David E.
2018-01-01
We present a high-performance implementation of the Polar Decomposition (PD) on distributed-memory systems. Building upon on the QR-based Dynamically Weighted Halley (QDWH) algorithm, the key idea lies in finding the best rational approximation
Polarized quark distributions in bound nucleon and polarized EMC effect in Thermodynamical Bag Model
Energy Technology Data Exchange (ETDEWEB)
Ganesamurthy, Kuppusamy, E-mail: udckgm@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India); Sambasivam, Raghavan, E-mail: udcsam@sify.co [Research Department of Physics, Urumu Dhanalakshmi College, Trichy 620019 (India)
2011-04-15
The polarized parton distribution functions (PDFs) and nuclear structure functions are evaluated by the phenomenological Thermodynamical Bag Model for nuclear media {sup 7}Li and {sup 27}Al. The Fermi statistical distribution function which includes the spin degree of freedom is used in this statistical model. We predict a sizeable polarized EMC effect. The results of quark spin sum and axial coupling constant of bound nucleons are compared with theoretical predictions of modified Nambu-Jona-Lasinio (NJL) model by Bentz et al.
International Nuclear Information System (INIS)
Koller, K.; Walsh, T.
1978-03-01
We discuss what can be learned of the 3 S 1 quarkonium decay QantiQ → 3 gluoans QantiQ → γ + 2 gluons. The former is a way to find gluon jets and test QCD. The latter also allows us to measure gluoan + gluon → hadrons and look for pure gluonic resonances (glueballs). (orig.) [de
Adolph, C; Alexakhin, V Yu; Alexandrov, Yu; Alexeev, G D; Amoroso, A; Antonov, A A; Austregesilo, A; Badelek, B; Balestra, F; Barth, J; Baum, G; Bedfer, Y; Berlin, A; Bernhard, J; Bertini, R; Bettinelli, M; Bicker, K; Bieling, J; Birsa, R; Bisplinghoff, J; Bordalo, P; Bradamante, F; Braun, C; Bravar, A; Bressan, A; Buchele, M; Burtin, E; Capozza, L; Chiosso, M; Chung, S U; Cicuttin, A; Crespo, M L; Dalla Torre, S; Das, S; Dasgupta, S S; Dasgupta, S; Denisov, O Yu; Dhara, L; 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; du Fresne von Hohenesche, N; Friedrich, J M; Frolov, V; Garfagnini, R; Gautheron, F; Gavrichtchouk, O P; Gerassimov, S; Geyer, R; Giorgi, M; Gnesi, I; Gobbo, B; Goertz, S; Grabmuller, S; Grasso, A; Grube, B; Gushterski, R; Guskov, A; Guthorl, T; Haas, F; von Harrach, D; Heinsius, F H; Herrmann, F; Hess, C; Hinterberger, F; Horikawa, N; Hoppner, Ch; d'Hose, N; Huber, S; Ishimoto, S; Ivanov, O; Ivanshin, Yu; Iwata, T; Jahn, R; Jary, V; Jasinski, P; Joosten, R; Kabuss, E; Kang, D; Ketzer, B; Khaustov, G V; Khokhlov, Yu A; Kisselev, Yu; Klein, F; Klimaszewski, K; Koblitz, S; Koivuniemi, J H; Kolosov, V N; Kondo, K; Konigsmann, K; Konorov, I; Konstantinov, V F; Korzenev, A; Kotzinian, A M; Kouznetsov, O; Kramer, M; Kroumchtein, Z V; Kunne, F; Kurek, K; Lauser, L; Lednev, A A; Lehmann, A; Levorato, S; Lichtenstadt, J; Liska, T; Maggiora, A; Magnon, A; Makke, N; Mallot, G K; Mann, A; Marchand, C; Martin, A; Marzec, J; Matsuda, T; Meshcheryakov, G; Meyer, W; Michigami, T; Mikhailov, Yu V; Morreale, A; Mutter, A; Nagaytsev, A; Nagel, T; Nerling, F; Neubert, S; Neyret, D; Nikolaenko, V I; Nowak, W D; Nunes, A S; Olshevsky, A G; Ostrick, M; Padee, A; Panknin, R; Panzieri, D; Parsamyan, B; Paul, S; Perevalova, E; Pesaro, G; Peshekhonov, D V; Piragino, G; Platchkov, S; Pochodzalla, J; Polak, J; Polyakov, V A; Pretz, J; Quaresma, M; Quintans, C; Rajotte, J F; Ramos, S; Rapatsky, V; Reicherz, G; Rocco, E; Rondio, E; Rossiyskaya, N S; Ryabchikov, D I; Samoylenko, V D; Sandacz, A; Sapozhnikov, M G; Sarkar, S; Savin, I A; Sbrizzai, G; Schiavon, P; Schill, C; Schluter, T; Schmidt, A; Schmidt, K; Schmitt, L; Schmiden, H; Schonning, K; Schopferer, S; Schott, M; Shevchenko, O Yu; Silva, L; Sinha, L; Sissakian, A N; Slunecka, M; Smirnov, G I; Sosio, S; Sozzi, F; Srnka, A; Steiger, L; Stolarski, M; Sulc, M; Sulej, R; Suzuki, H; Sznajder, P; Takekawa, S; Ter Wolbeek, J; Tessaro, S; Tessarotto, F; Tkatchev, L G; Uhl, S; Uman, I; Vandenbroucke, M; Virius, M; Vlassov, N V; Wang, L; Weisrock, T; Wilfert, M; Windmolders, R; Wislicki, W; Wollny, H; Zaremba, K; Zavertyaev, M; Zemlyanichkina, E; Ziembicki, M; Zhuravlev, N; Zvyagin, A
2013-01-01
The gluon polarisation in the nucleon was measured using open charm production by scattering 160 GeV/c polarised muons off longitudinally polarised protons or deuterons. The data were taken by the COMPASS collaboration between 2002 and 2007. A detailed account is given of the analysis method that includes the application of neural networks. Several decay channels of $D^0$ mesons are investigated. Longitudinal spin asymmetries of the D meson production cross-sections are extracted in bins of $D^0$ transverse momentum and energy. At leading order QCD accuracy the average gluon polarisation is determined as $(\\Delta g/g)^{LO}=-0.06 \\pm 0.21 (stat.) \\pm 0.08 (syst.)$ at the scale $ \\approx 13$ (GeV/c)$^2$ and an average gluon momentum fraction $\\approx$ 0.11. The average gluon polarisation is also obtained at next-to-leading order QCD accuracy as $(\\Delta g/g) NLO = -0.13 \\pm 0.15 (stat.) \\pm 0.15 (syst.)$ at the scale $ \\approx $ 13 (GeV/c)$^2$ and $ \\approx $ 0.20.
Energy Technology Data Exchange (ETDEWEB)
Hermann, Roman
2009-09-05
The spin structure of the nucleon is investigated at the COMPASS experiment at the CERN SPS using polarized muons scattering off polarized nucleons. The contribution of the quarks to nucleon spin, as measured in the inclusive deep-inelastic scattering, is not sufficient to explain the spin of the nucleon. Thus it has to be clarified how the gluon polarization and the angular momenta of quarks and gluons contribute to the spin of the nucleon. Since the gluon polarization can only be estimated from the Q{sup 2}-dependence of inclusive deep inelastic asymmetries, a direct measurement of the gluon polarization is mandatory. The COMPASS collaboration determines the gluon polarization from cross section asymmetries in photon-gluon fusion processes using open charm production or the production of hadron pairs with large transverse momenta. This thesis presents a measurement of the gluon polarization using the COMPASS data of the years 2003 and 2004. The events with large virtuality, Q{sup 2}>1 GeV{sup 2}/c{sup 2}, and hadron pairs with large transverse momenta, p perpendicular to > 0.7 GeV/c have been used in the analysis. The photon-nucleon asymmetry was determined by using a weighted double ratio method of the selected events. The cut on p perpendicular to > 0.7 GeV/c suppresses leading order processes, so that the obtained asymmetry can be directly linked to the gluon polarization, if the analyzing power and the photon-gluon fusion fraction is known. The measured value is very small and compatible with a vanishing gluon polarization. To avoid false asymmetries, which could be caused by a change of the detector acceptances double ratios were analyzed, where the cross section cancels, and only detector asymmetries remain. It is shown that the COMPASS spectrometer was stable during the time of data taking. For the computation of the analyzing power Monte Carlo events were generated using the LEPTO and the COMGeant software packages. In this context a good MC description
Electron distribution in polar heterojunctions within a realistic model
Energy Technology Data Exchange (ETDEWEB)
Tien, Nguyen Thanh, E-mail: thanhtienctu@gmail.com [College of Natural Science, Can Tho University, 3-2 Road, Can Tho City (Viet Nam); Thao, Dinh Nhu [Center for Theoretical and Computational Physics, College of Education, Hue University, 34 Le Loi Street, Hue City (Viet Nam); Thao, Pham Thi Bich [College of Natural Science, Can Tho University, 3-2 Road, Can Tho City (Viet Nam); Quang, Doan Nhat [Institute of Physics, Vietnamese Academy of Science and Technology, 10 Dao Tan Street, Hanoi (Viet Nam)
2015-12-15
We present a theoretical study of the electron distribution, i.e., two-dimensional electron gas (2DEG) in polar heterojunctions (HJs) within a realistic model. The 2DEG is confined along the growth direction by a triangular quantum well with a finite potential barrier and a bent band figured by all confinement sources. Therein, interface polarization charges take a double role: they induce a confining potential and, furthermore, they can make some change in other confinements, e.g., in the Hartree potential from ionized impurities and 2DEG. Confinement by positive interface polarization charges is necessary for the ground state of 2DEG existing at a high sheet density. The 2DEG bulk density is found to be increased in the barrier, so that the scattering occurring in this layer (from interface polarization charges and alloy disorder) becomes paramount in a polar modulation-doped HJ.
Self-adaptive demodulation for polarization extinction ratio in distributed polarization coupling.
Zhang, Hongxia; Ren, Yaguang; Liu, Tiegen; Jia, Dagong; Zhang, Yimo
2013-06-20
A self-adaptive method for distributed polarization extinction ratio (PER) demodulation is demonstrated. It is characterized by dynamic PER threshold coupling intensity (TCI) and nonuniform PER iteration step length (ISL). Based on the preset PER calculation accuracy and original distribution coupling intensity, TCI and ISL can be made self-adaptive to determine contributing coupling points inside the polarizing devices. Distributed PER is calculated by accumulating those coupling points automatically and selectively. Two different kinds of polarization-maintaining fibers are tested, and PERs are obtained after merely 3-5 iterations using the proposed method. Comparison experiments with Thorlabs commercial instrument are also conducted, and results show high consistency. In addition, the optimum preset PER calculation accuracy of 0.05 dB is obtained through many repeated experiments.
Charmed quark production as a gluon probe
International Nuclear Information System (INIS)
Phillips, R.J.N.
1980-09-01
The lowest-order QCD mechanisms for producing cc or other heavy quarks depend on the gluon distributions in hadrons; hence the latter can be extracted directly from experiment. Recent results are described. (author)
DEFF Research Database (Denmark)
Shvetsov-Shilovskiy, Nikolay; Dimitrovski, Darko; Madsen, Lars Bojer
2012-01-01
In the tunneling regime we present a semiclassical model of above-threshold ionization with inclusion of the Stark shift of the initial state, the Coulomb potential, and a polarization induced dipole potential. The model is used for the investigation of the photoelectron momentum distributions...... in close to circularly polarized light, and it is validated by comparison with ab initio results and experiments. The momentum distributions are shown to be highly sensitive to the tunneling exit point, the Coulomb force, and the dipole potential from the induced dipole in the atomic core...
Selection of Photon Gluon Fusion Events in DIS
International Nuclear Information System (INIS)
Kowalik, K.; Rondio, E.; Sulej, R.; Zaremba, K.
2001-01-01
A selection of the Photon Gluon Fusion (PGF) process with light quarks for deep inelastic scattering events is presented. This process is directly sensitive to gluon polarization and our goal is to find out the most effective selection on a sample of events simulated for the SMC experiment. We compare two general multi-class classification methods - Bayes method and neural network with a conventional selection procedure. The neural network algorithm presented here is a modification of method belonging to the family of directional minimization algorithms. This method is convenient and effective for photon gluon fusion selection and determination of gluon polarization. Finally we present the estimation for precision of gluon polarization for neural network method. (author)
Frixione, Stefano; Ridolfi, G
1999-01-01
We consider the resummation of soft-gluon emission in the transverse-momentum distribution of vector mesons in hadronic collisions. We find that the resummed expression in the impact-parameter formulation has an expansion in $\\as$ with factorially growing terms with oscillating signs. These diverging terms arise from the small impact-parameter region of integration, and are of a subleading nature. We also obtain a closed expression for the next-to-leading logarithm resummation in $\\qt$-space, and we study its analytic structure. We find in this case that, although no factorially growing terms are present, there are geometrical singularities that severely restrict the range of applicability of the resummation formula.
International Nuclear Information System (INIS)
Sugano, K.
1987-01-01
The properties of gluon jets are reviewed, and the measured characteristics are compared to the theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, in general the agreement between experiment and theory is remarkable. There are some intriguing differences. Since the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on our understanding of QCD. Finally, the future prospects are discussed
International Nuclear Information System (INIS)
Sugano, K.
1988-01-01
The properties of gluon jets are reviewed from an experimental point of view. The measured characteristics are compared to theoretical expectations. Although neither data nor models for the gluon jets are in the mature stage, there are remarkable agreements and also intriguing disagreements between experiment and theory. Since much interesting data have begun to emerge from various experiments and the properties of gluon jets are deeply rooted in the basic structure of non-Abelian gauge theory, the study of gluon jets casts further light on understanding of QCD. The future prospects are discussed
Testing proton spin models with polarized beams
International Nuclear Information System (INIS)
Ramsey, G.P.
1991-01-01
We review models for spin-weighted parton distributions in a proton. Sum rules involving the nonsinglet components of the structure function xg 1 p help narrow the range of parameters in these models. The contribution of the γ 5 anomaly term depends on the size of the integrated polarized gluon distribution and experimental predictions depend on its size. We have proposed three models for the polarized gluon distributions, whose range is considerable. These model distributions give an overall range is considerable. These model distributions give an overall range of parameters that can be tested with polarized beam experiments. These are discussed with regard to specific predictions for polarized beam experiments at energies typical of UNK
Modelling the gluon propagator
Energy Technology Data Exchange (ETDEWEB)
Leinweber, D.B.; Parrinello, C.; Skullerud, J.I.; Williams, A.G
1999-03-01
Scaling of the Landau gauge gluon propagator calculated at {beta} = 6.0 and at {beta} = 6.2 is demonstrated. A variety of functional forms for the gluon propagator calculated on a large (32{sup 3} x 64) lattice at {beta} = 6.0 are investigated.
Superthermal electron distribution measurements from polarized electron cyclotron emission
International Nuclear Information System (INIS)
Luce, T.C.; Efthimion, P.C.; Fisch, N.J.
1988-06-01
Measurements of the superthermal electron distribution can be made by observing the polarized electron cyclotron emission. The emission is viewed along a constant magnetic field surface. This simplifies the resonance condition and gives a direct correlation between emission frequency and kinetic energy of the emitting electron. A transformation technique is formulated which determines the anisotropy of the distribution and number density of superthermals at each energy measured. The steady-state distribution during lower hybrid current drive and examples of the superthermal dynamics as the runaway conditions is varied are presented for discharges in the PLT tokamak. 15 refs., 8 figs
Gluon saturation in a saturated environment
International Nuclear Information System (INIS)
Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan
2011-01-01
A bootstrap equation for self-quenched gluon shadowing leads to a reduced magnitude of broadening for partons propagating through a nucleus. Saturation of small-x gluons in a nucleus, which has the form of transverse momentum broadening of projectile gluons in pA collisions in the nuclear rest frame, leads to a modification of the parton distribution functions in the beam compared with pp collisions. In nucleus-nucleus collisions all participating nucleons acquire enhanced gluon density at small x, which boosts further the saturation scale. Solution of the reciprocity equations for central collisions of two heavy nuclei demonstrate a significant, up to several times, enhancement of Q sA 2 , in AA compared with pA collisions.
Multi-user distribution of polarization entangled photon pairs
Energy Technology Data Exchange (ETDEWEB)
Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I., E-mail: isabelle.zaquine@telecom-paristech.fr [LTCI, CNRS, Télécom ParisTech, Université Paris-Saclay, 75013 Paris (France); Ghalbouni, J. [Applied Physics Laboratory, Faculty of Sciences 2, Lebanese University, Campus Fanar, BP 90656 Jdeidet (Lebanon)
2015-10-14
We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.
International Nuclear Information System (INIS)
Block, Martin M.; Durand, Loyal; McKay, Douglas W.
2008-01-01
We derive a second-order linear differential equation for the leading-order gluon distribution function G(x,Q 2 )=xg(x,Q 2 ) which determines G(x,Q 2 ) directly from the proton structure function F 2 p (x,Q 2 ). This equation is derived from the leading-order evolution equation for F 2 p (x,Q 2 ), and does not require knowledge of either the individual quark distributions or the gluon evolution equation. Given an analytic expression that successfully reproduces the known experimental data for F 2 p (x,Q 2 ) in a domain x min (Q 2 )≤x≤x max (Q 2 ), Q min 2 ≤Q 2 ≤Q max 2 of the Bjorken variable x and the virtuality Q 2 in deep inelastic scattering, G(x,Q 2 ) is uniquely determined in the same domain. We give the general solution and illustrate the method using the recently proposed Froissart-bound-type parametrization of F 2 p (x,Q 2 ) of E. L. Berger, M. M. Block and C.-I. Tan [Phys. Rev. Lett. 98, 242001 (2007)]. Existing leading-order gluon distributions based on power-law descriptions of individual parton distributions agree roughly with the new distributions for x > or approx. 10 -3 as they should, but are much larger for x -3 .
Gluon quasidistribution function at one loop
Energy Technology Data Exchange (ETDEWEB)
Wang, Wei; Zhao, Shuai [Shanghai Jiao Tong University, INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, School of Physics and Astronomy, Shanghai (China); Zhu, Ruilin [Shanghai Jiao Tong University, INPAC, Shanghai Key Laboratory for Particle Physics and Cosmology, School of Physics and Astronomy, Shanghai (China); Nanjing Normal University, Department of Physics and Institute of Theoretical Physics, Nanjing, Jiangsu (China)
2018-02-15
We study the unpolarized gluon quasidistribution function in the nucleon at one loop level in the large momentum effective theory. For the quark quasidistribution, power law ultraviolet divergences arise in the cut-off scheme and an important observation is that they all are subjected to Wilson lines. However for the gluon quasidistribution function, we first point out that the linear ultraviolet divergences also exist in the real diagram which is not connected to any Wilson line. We then study the one loop corrections to parton distribution functions in both cut-off scheme and dimensional regularization to deal with the ultraviolet divergences. In addition to the ordinary quark and gluon distributions, we also include the quark to gluon and gluon to quark splitting diagrams. The complete one-loop matching factors between the quasi and light cone parton distribution functions are presented in the cut-off scheme. We derive the P{sup z} evolution equation for quasi parton distribution functions, and find that the P{sup z} evolution kernels are identical to the DGLAP evolution kernels. (orig.)
High Performance Polar Decomposition on Distributed Memory Systems
Sukkari, Dalal E.
2016-08-08
The polar decomposition of a dense matrix is an important operation in linear algebra. It can be directly calculated through the singular value decomposition (SVD) or iteratively using the QR dynamically-weighted Halley algorithm (QDWH). The former is difficult to parallelize due to the preponderant number of memory-bound operations during the bidiagonal reduction. We investigate the latter scenario, which performs more floating-point operations but exposes at the same time more parallelism, and therefore, runs closer to the theoretical peak performance of the system, thanks to more compute-bound matrix operations. Profiling results show the performance scalability of QDWH for calculating the polar decomposition using around 9200 MPI processes on well and ill-conditioned matrices of 100K×100K problem size. We study then the performance impact of the QDWH-based polar decomposition as a pre-processing step toward calculating the SVD itself. The new distributed-memory implementation of the QDWH-SVD solver achieves up to five-fold speedup against current state-of-the-art vendor SVD implementations. © Springer International Publishing Switzerland 2016.
Soft Gluon Radiation off Heavy Quarks beyond Eikonal Approximation
International Nuclear Information System (INIS)
Mazumder, Surasree; Bhattacharyya, Trambak; Abir, Raktim
2016-01-01
We calculate the soft gluon radiation spectrum off heavy quarks (HQs) interacting with light quarks (LQs) beyond small angle scattering (eikonality) approximation and thus generalize the dead-cone formula of heavy quarks extensively used in the literatures of Quark-Gluon Plasma (QGP) phenomenology to the large scattering angle regime which may be important in the energy loss of energetic heavy quarks in the deconfined Quark-Gluon Plasma medium. In the proper limits, we reproduce all the relevant existing formulae for the gluon radiation distribution off energetic quarks, heavy or light, used in the QGP phenomenology.
Chala, Mikael; Perez, Gilad; Santiago, Jose
2015-01-01
We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bou...
International Nuclear Information System (INIS)
Khadkikar, S.B.; Vinodkumar, P.C.
1987-04-01
Confinement model for gluons using a 'colour super current' is formulated. An attempt has been made to derive a suitable dielectric function corresponding to the current confinement model. A simple inhomogeneous dielectric confinement model for gluons is studied for comparison. The model Hamiltonians are second quantized and the glueball states are constructed. The spurious motion of the centre of confinement is accounted for. The results of the current confinement scheme are found to be in good agreement with the experimental candidates for glueballs. (author). 16 refs, 3 tabs
Gluon and quark jets in a recursive model motivated by quantum chromodynamics
International Nuclear Information System (INIS)
Sukhatme, U.P.
1979-01-01
We compute observable quantities like the multiplicity and momentum distributions of hadrons in gluon and quark jets in the framework of a recursive cascade model, which is strongly motivated by the fundamental interactions of QCD. Fragmentation occurs via 3 types of breakups: quark → meson + quark, gluon → meson + gluon, gluon → quark + antiquark. In our model gluon jets are softer than quark jets. The ratio of gluon jet to quark jet multiplicity is found to be 2 asymptotically, but much less at lower energies. Some phenomenological consequences for γ decay are discussed. (orig.)
Measurement of the Polarized Structure Function $g_1^p$ at HERA
Ball, R.D.; Forte, S.; Hughes, V.W.; Lichtenstadt, J.; Ridolfi, G.; Ball, Richard D.; Deshpande, Abhay; Forte, Stefano; Hughes, Vernon W.; Lichtenstadt, Jechiel; Ridolfi, Giovanni
1996-01-01
We present estimates of possible data on spin-dependent asymmetries in inclusive scattering of high energy polarized electrons by high energy polarized protons at HERA, including statistical errors, and discuss systematic uncertainties. We show that these data would shed light on the small x behaviour of the polarized structure function g_1, and would reduce substantially the uncertainty on the determination of the polarized gluon distribution.
Massively Parallel Polar Decomposition on Distributed-Memory Systems
Ltaief, Hatem
2018-01-01
We present a high-performance implementation of the Polar Decomposition (PD) on distributed-memory systems. Building upon on the QR-based Dynamically Weighted Halley (QDWH) algorithm, the key idea lies in finding the best rational approximation for the scalar sign function, which also corresponds to the polar factor for symmetric matrices, to further accelerate the QDWH convergence. Based on the Zolotarev rational functions—introduced by Zolotarev (ZOLO) in 1877— this new PD algorithm ZOLO-PD converges within two iterations even for ill-conditioned matrices, instead of the original six iterations needed for QDWH. ZOLO-PD uses the property of Zolotarev functions that optimality is maintained when two functions are composed in an appropriate manner. The resulting ZOLO-PD has a convergence rate up to seventeen, in contrast to the cubic convergence rate for QDWH. This comes at the price of higher arithmetic costs and memory footprint. These extra floating-point operations can, however, be processed in an embarrassingly parallel fashion. We demonstrate performance using up to 102, 400 cores on two supercomputers. We demonstrate that, in the presence of a large number of processing units, ZOLO-PD is able to outperform QDWH by up to 2.3X speedup, especially in situations where QDWH runs out of work, for instance, in the strong scaling mode of operation.
International Nuclear Information System (INIS)
Granier de Cassagnac, R.
2010-01-01
The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)
Practical quantum key distribution with polarization-entangled photons
International Nuclear Information System (INIS)
Poppe, A.; Fedrizzi, A.; Boehm, H.; Ursin, R.; Loruenser, T.; Peev, M.; Maurhardt, O.; Suda, M.; Kurtsiefer, C.; Weinfurter, H.; Jennewein, T.; Zeilinger, A.
2005-01-01
Full text: We present an entangled-state quantum cryptography system that operated for the first time in a real-world application scenario. The full key generation protocol was performed in real-time between two distributed embedded hardware devices, which were connected by 1.45 km of optical fiber, installed for this experiment in the Vienna sewage system. A source for polarization-entangled photons delivered about 8200 entangled photon pairs per second. After transmission to the distant receivers, a mean value of 468 pairs per second remained for the generation of a raw key, which showed an average qubit error rate of 6.4 %. The raw key was sifted and subsequently processed by a classical protocol which included error correction and privacy amplification. The final secure key bit rate was about 76 bits per second. The generated quantum key was then handed over and used by a secure communication application. (author)
Exciton distribution function and secondary radiation in polar semiconductors
International Nuclear Information System (INIS)
Trallero Giner, C.; Sotolongo Costa, O.
1985-07-01
An explicit non-equilibrium distribution function for excitons in the ground state n=1 in the case when the fundamental interaction is with acoustical phonons is calculated for polar semiconductors. Using it, a general expression for the secondary radiation cross-section (valid for Raman, hot and thermalized luminescence processes), is obtained. The results are applied to explain the temperature dependence of the 1LO and 2LO luminescence lines half-width in CdS single crystals. The relative contributions of 3LO Raman and luminescence intensities and the variation of the secondary emission spectrum as function of exciton life-time are studied. Comparison with experimental results yields quantitative agreement. (author)
Continuous Variable Quantum Key Distribution Using Polarized Coherent States
Vidiella-Barranco, A.; Borelli, L. F. M.
We discuss a continuous variables method of quantum key distribution employing strongly polarized coherent states of light. The key encoding is performed using the variables known as Stokes parameters, rather than the field quadratures. Their quantum counterpart, the Stokes operators Ŝi (i=1,2,3), constitute a set of non-commuting operators, being the precision of simultaneous measurements of a pair of them limited by an uncertainty-like relation. Alice transmits a conveniently modulated two-mode coherent state, and Bob randomly measures one of the Stokes parameters of the incoming beam. After performing reconciliation and privacy amplification procedures, it is possible to distill a secret common key. We also consider a non-ideal situation, in which coherent states with thermal noise, instead of pure coherent states, are used for encoding.
Quark self-energy in an ellipsoidally anisotropic quark-gluon plasma
Kasmaei, Babak S.; Nopoush, Mohammad; Strickland, Michael
2016-12-01
We calculate the quark self-energy in a quark-gluon plasma that possesses an ellipsoidal momentum-space anisotropy in the local rest frame. By introducing additional transverse-momentum anisotropy parameters into the parton distribution functions, we generalize previous results which were obtained for the case of a spheroidal anisotropy. Our results demonstrate that the presence of anisotropies in the transverse directions affects the real and imaginary parts of quark self-energy and, consequently, the self-energy depends on both the polar and azimuthal angles in the local rest frame of the matter. Our results for the quark self-energy set the stage for the calculation of the effects of ellipsoidal momentum-space anisotropy on quark-gluon plasma photon spectra and collective flow.
Angular distribution of large qsub(T) muon pairs in different reference frames
International Nuclear Information System (INIS)
Lindfors, J.
1979-01-01
The angular distribution of large transverse momentum muon pairs produced in hadron-hadron collisions is calculated in lowest order of perturbative QCD. It is shown that for the process quark-antiquark → gluon + μ + μ - the polar and azimuthal angle distributions can be made independent of the parton distributions by choosing a special reference frame, the Collins-Soper frame, but for the process quark + gluon → quark + μ + μ - this is not possible. (author)
Probing Transverse Momentum Dependent Parton Distributions in Charmonium and Bottomonium Production
Mukherjee, Asmita; Rajesh, Sangem
2015-01-01
We propose the study of unpolarized transverse momentum dependent gluon parton distributions as well as the effect of linearly polarized gluons on transverse momentum and rapidity distributions of $J/\\psi$ and $\\Upsilon$ production within the framework of transverse momentum dependent factorization employing color evaporation model (CEM) in unpolarized proton-proton collision. We estimate the transverse momentum and rapidity distributions of $J/\\psi$ and $\\Upsilon$ at LHCb, RHIC and AFTER ene...
Angular distribution coefficients for γ-ray polarization produced in polarized capture reactions
International Nuclear Information System (INIS)
Wulf, E.A.; Guillemette, J.; Weller, H.R.; Seyler, R.G.
1999-01-01
The previous publications have dealt with the angular momentum formalism of both linear and circularly polarized photons in (γ, x) reactions on both polarized and unpolarized targets, and the inverse (capture) reactions initiated by polarized beams. In the present work, utilizing the general formalism of Welton, the authors deal with the linear polarization of the γ-rays which are produced in capture reactions on unpolarized targets, including the possibility of having incident polarized spin 1/2 projectiles. These capture reactions are denoted by a(rvec x, rvec L)c, where rvec x is the incident polarized spin 1/2 projectile and rvec L represents the outgoing polarized γ-ray. They present here the formalism in a convenient form, display a sample table of coefficients, and illustrate its use by means of several examples. A FORTRAN code will be made available for generating similar coefficients for other reactions
1990-01-01
This volume contains 14 review articles on the theory and phenomenology of the creation and diagnosis of quark-gluon plasma. They are written by active investigators of in the various research topics, which range from the QCD foundation through transport theory and thermalization models to the examination of possible signatures. The monograph should be useful not only to the experienced researchers in the subject but also to newcomers.
International Nuclear Information System (INIS)
Ayala, A.L.
1996-01-01
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab
Energy Technology Data Exchange (ETDEWEB)
Chala, Mikael [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Juknevich, Jose [International School for Advanced Studies, Trieste (Italy); Istituto Nazionale di Fisica Nucleare, Trieste (Italy); Perez, Gilad [Weizmann Institute of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics; Santiago, Jose [Granada Univ. (Spain). CAFPE; Granada Univ. (Spain). Dept. de Fisica Teorica y del Cosmos; European Organization for Nuclear Research (CERN), Geneva (Switzerland)
2014-11-15
We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bounds on its mass can be up to 2 TeV milder than in the simpler models considered so far for the LHC14. We discuss the origin of this difference and prospects for dedicated searches.
Nayak, Tapan; Sarkar, Sourav
2014-01-01
At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.
International Nuclear Information System (INIS)
Chala, Mikael; Juknevich, Jose; Perez, Gilad
2014-11-01
We study the phenomenology of vector resonances in the context of natural composite Higgs models. A mild hierarchy between the fermionic partners and the vector resonances can be expected in these models based on the following arguments. Both direct and indirect (electroweak and flavor precision) constraints on fermionic partners are milder than the ones on spin one resonances. Also the naturalness pressure coming from the top partners is stronger than that induced by the gauge partners. This observation implies that the search strategy for vector resonances at the LHC needs to be modified. In particular, we point out the importance of heavy gluon decays (or other vector resonances) to top partner pairs that were overlooked in previous experimental searches at the LHC. These searches focused on simplified benchmark models in which the only new particle beyond the Standard Model was the heavy gluon. It turns out that, when kinematically allowed, such heavy-heavy decays make the heavy gluon elusive, and the bounds on its mass can be up to 2 TeV milder than in the simpler models considered so far for the LHC14. We discuss the origin of this difference and prospects for dedicated searches.
Gluon saturation and baryon stopping in the SPS, RHIC, and LHC energy regions
International Nuclear Information System (INIS)
Li Shuang; Feng Shengqin
2012-01-01
A new geometrical scaling method with a gluon saturation rapidity limit is proposed to study the gluon saturation feature of the central rapidity region of relativistic nuclear collisions. The net-baryon number is essentially transported by valence quarks that probe the saturation regime in the target by multiple scattering. We take advantage of the gluon saturation model with geometric scaling of the rapidity limit to investigate net baryon distributions, nuclear stopping power and gluon saturation features in the SPS and RHIC energy regions. Predictions for net baryon rapidity distributions, mean rapidity loss and gluon saturation feature in central Pb + Pb collisions at the LHC are made in this paper. (authors)
A gluon cluster solution of effective Yang-Mills theory
Pavlovsky, O V
2001-01-01
A classical solution of the effective Yang-Mills (YM) theory with a finite energy and nonstandard Lagrangian was obtained. Influence of vacuum polarization on gluon cluster formation was discussed. Appearance of cluster solutions in the theory of non-Abelian fields can take place only if the result goes beyond the framework of pure YM theory. It is shown that account of quantum effects of polarized vacuum in the presence of a classical gluon field can also result in formation of the solutions. Solutions with the finite intrinsic energy are provided. Besides, fields of colour groups SU(2) were studied
Gluon asymmetries in the leptoproduction of J/Ψ
International Nuclear Information System (INIS)
Godbole, R.M.; Gupta, S.; Sridhar, K.
1990-07-01
We study J/Ψ production, in deep inelastic scattering experiments with polarised beams and polarised targets. The spin asymmetries are seen to depend strongly on the particular form of the spin dependent gluon distributions used. Therefore, it should be possible in these experiments, to discriminate between different parametrizations of polarised gluon distributions, and hence between the distinctly different physical pictures of the proton spin underlying these parametrizations. (author). 18 refs, 4 figs, 1 tab
The gluon condensation at high energy hadron collisions
Energy Technology Data Exchange (ETDEWEB)
Zhu, Wei, E-mail: weizhu@mail.ecnu.edu.cn [Department of Physics, East China Normal University, Shanghai 200241 (China); Lan, Jiangshan [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)
2017-03-15
We report that the saturation/CGC model of gluon distribution is unstable under action of the chaotic solution in a nonlinear QCD evolution equation, and it evolves to the distribution with a sharp peak at the critical momentum. We find that this gluon condensation is caused by a new kind of shadowing–antishadowing effects, and it leads to a series of unexpected effects in high energy hadron collisions including astrophysical events. For example, the extremely intense fluctuations in the transverse-momentum and rapidity distributions of the gluon jets present the gluon-jet bursts; a sudden increase of the proton–proton cross sections may fill the GZK suppression; the blocking QCD evolution will restrict the maximum available energy of the hadron–hadron colliders.
Energy Technology Data Exchange (ETDEWEB)
Weinzierl, Stefan, E-mail: weinzierl@uni-mainz.de
2017-03-13
This report is centred around tree-level scattering amplitudes in pure Yang–Mills theories, the most prominent example is given by the tree-level gluon amplitudes of QCD. I will discuss several ways of computing these amplitudes, illustrating in this way recent developments in perturbative quantum field theory. Topics covered in this review include colour decomposition, spinor and twistor methods, off- and on-shell recursion, MHV amplitudes and MHV expansion, the Grassmannian and the amplituhedron, the scattering equations and the CHY representation. At the end of this report there will be an outlook on the relation between pure Yang–Mills amplitudes and scattering amplitudes in perturbative quantum gravity.
Quark and Gluon Relaxation in Quark-Gluon Plasmas
Heiselberg, H.; Pethick, C. J.
1993-01-01
The quasiparticle decay rates for quarks and gluons in quark-gluon plasmas are calculated by solving the kinetic equation. Introducing an infrared cutoff to allow for nonperturbative effects, we evaluate the quasiparticle lifetime at momenta greater than the inverse Debye screening length to leading order in the coupling constant.
High Performance Polar Decomposition on Distributed Memory Systems
Sukkari, Dalal E.; Ltaief, Hatem; Keyes, David E.
2016-01-01
The polar decomposition of a dense matrix is an important operation in linear algebra. It can be directly calculated through the singular value decomposition (SVD) or iteratively using the QR dynamically-weighted Halley algorithm (QDWH). The former
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Mesic, Benjamin; Starodumov, Andrei; Susa, Tatjana; Ather, Mohsan Waseem; Attikis, Alexandros; Kolosova, Marina; Mavromanolakis, Georgios; Mousa, Jehad; Nicolaou, Charalambos; Ptochos, Fotios; Razis, Panos A; Rykaczewski, Hans; Finger, Miroslav; Finger Jr, Michael; Ayala, Edy; Carrera Jarrin, Edgar; Abdalla, Hassan; Abdelalim, Ahmed Ali; Mahmoud, Mohammed; Bhowmik, Sandeep; Carvalho Antunes De Oliveira, Alexandra; Dewanjee, Ram Krishna; Ehataht, Karl; Kadastik, Mario; Raidal, Martti; Veelken, Christian; Eerola, Paula; Kirschenmann, Henning; Pekkanen, Juska; Voutilainen, Mikko; Havukainen, Joona; Heikkilä, Jaana Kristiina; Jarvinen, Terhi; Karimäki, Veikko; Kinnunen, Ritva; Lampén, Tapio; Lassila-Perini, Kati; Laurila, Santeri; Lehti, Sami; Lindén, Tomas; Luukka, Panja-Riina; Mäenpää, Teppo; Siikonen, Hannu; Tuominen, Eija; Tuominiemi, Jorma; Tuuva, Tuure; Besancon, Marc; Couderc, Fabrice; Dejardin, Marc; Denegri, Daniel; Faure, Jean-Louis; Ferri, Federico; Ganjour, Serguei; Givernaud, Alain; Gras, Philippe; Hamel de Monchenault, Gautier; Jarry, Patrick; Leloup, Clément; Locci, Elizabeth; Malcles, Julie; Negro, Giulia; Rander, John; Rosowsky, André; Sahin, Mehmet Özgür; Titov, Maksym; Abdulsalam, Abdulla; Amendola, Chiara; Antropov, Iurii; Beaudette, Florian; Busson, Philippe; Charlot, Claude; Granier de Cassagnac, Raphael; Kucher, Inna; Lobanov, Artur; Martin Blanco, Javier; Nguyen, Matthew; Ochando, Christophe; Ortona, Giacomo; Pigard, Philipp; Salerno, Roberto; Sauvan, Jean-Baptiste; Sirois, Yves; Stahl Leiton, Andre Govinda; Zabi, Alexandre; Zghiche, Amina; Agram, Jean-Laurent; Andrea, Jeremy; Bloch, Daniel; Brom, Jean-Marie; Chabert, Eric Christian; Cherepanov, Vladimir; Collard, Caroline; Conte, Eric; Fontaine, Jean-Charles; Gelé, Denis; Goerlach, Ulrich; Jansová, Markéta; Le Bihan, Anne-Catherine; Tonon, Nicolas; Van Hove, Pierre; Gadrat, Sébastien; Beauceron, Stephanie; Bernet, Colin; Boudoul, Gaelle; Chanon, Nicolas; Chierici, Roberto; Contardo, Didier; Depasse, Pierre; 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Tiwari, Praveen Chandra; Bahinipati, Seema; Kar, Chandiprasad; Mal, Prolay; Mandal, Koushik; Nayak, Aruna; Sahoo, Deepak Kumar; Swain, Sanjay Kumar; Bansal, Sunil; Beri, Suman Bala; Bhatnagar, Vipin; Chauhan, Sushil; Chawla, Ridhi; Dhingra, Nitish; Gupta, Rajat; Kaur, Anterpreet; Kaur, Amandeep; Kaur, Manjit; Kaur, Sandeep; Kumar, Ramandeep; Kumari, Priyanka; Lohan, Manisha; Mehta, Ankita; Sandeep, Kaur; Sharma, Sandeep; Singh, Jasbir; Walia, Genius; Bhardwaj, Ashutosh; Choudhary, Brajesh C; Garg, Rocky Bala; Gola, Mohit; Keshri, Sumit; Kumar, Ashok; Malhotra, Shivali; Naimuddin, Md; Priyanka, Priyanka; Ranjan, Kirti; Shah, Aashaq; Sharma, Ramkrishna; Bhardwaj, Rishika; Bharti, Monika; Bhattacharya, Rajarshi; Bhattacharya, Satyaki; Bhawandeep, Bhawandeep; Bhowmik, Debabrata; Dey, Sourav; Dutt, Suneel; Dutta, Suchandra; Ghosh, Shamik; Mondal, Kuntal; Nandan, Saswati; Purohit, Arnab; Rout, Prasant Kumar; Roy, Ashim; Roy Chowdhury, Suvankar; Saha, Gourab; Sarkar, Subir; Sharan, Manoj; Singh, Bipen; Thakur, Shalini; Behera, Prafulla Kumar; Chudasama, Ruchi; Dutta, Dipanwita; Jha, Vishwajeet; Kumar, Vineet; Netrakanti, Pawan Kumar; Pant, Lalit Mohan; Shukla, Prashant; Aziz, Tariq; Bhat, Muzamil Ahmad; Dugad, Shashikant; Mohanty, Gagan Bihari; Sur, Nairit; Sutar, Bajrang; Ravindra Kumar Verma, Ravindra; Banerjee, Sudeshna; Bhattacharya, Soham; Chatterjee, Suman; Das, Pallabi; Guchait, Monoranjan; Jain, Sandhya; Karmakar, Saikat; Kumar, Sanjeev; Maity, Manas; Majumder, Gobinda; Mazumdar, Kajari; Sahoo, Niladribihari; Sarkar, Tanmay; Chauhan, Shubhanshu; Dube, Sourabh; Hegde, Vinay; Kapoor, Anshul; Kothekar, Kunal; Pandey, Shubham; Rane, Aditee; Sharma, Seema; Chenarani, Shirin; Eskandari Tadavani, Esmaeel; Etesami, Seyed Mohsen; Khakzad, Mohsen; Mohammadi Najafabadi, Mojtaba; Naseri, Mohsen; Rezaei Hosseinabadi, Ferdos; Safarzadeh, Batool; Zeinali, Maryam; Felcini, Marta; Grunewald, Martin; Abbrescia, Marcello; Calabria, Cesare; Colaleo, Anna; Creanza, Donato; Cristella, Leonardo; De Filippis, Nicola; De Palma, Mauro; Di Florio, Adriano; Errico, Filippo; Fiore, Luigi; Gelmi, Andrea; Iaselli, Giuseppe; Ince, Merve; Lezki, Samet; Maggi, Giorgio; Maggi, Marcello; Miniello, Giorgia; My, Salvatore; Nuzzo, Salvatore; Pompili, Alexis; Pugliese, Gabriella; Radogna, Raffaella; Ranieri, Antonio; Selvaggi, Giovanna; Sharma, Archana; Silvestris, Lucia; Venditti, Rosamaria; Verwilligen, Piet; Zito, Giuseppe; Abbiendi, Giovanni; Battilana, Carlo; Bonacorsi, Daniele; Borgonovi, Lisa; Braibant-Giacomelli, Sylvie; Campanini, Renato; Capiluppi, Paolo; Castro, Andrea; Cavallo, Francesca Romana; Chhibra, Simranjit Singh; Ciocca, Claudia; Codispoti, Giuseppe; Cuffiani, Marco; Dallavalle, Gaetano-Marco; Fabbri, Fabrizio; Fanfani, Alessandra; Giacomelli, Paolo; Grandi, Claudio; Guiducci, Luigi; Iemmi, Fabio; Marcellini, Stefano; Masetti, Gianni; Montanari, Alessandro; Navarria, Francesco; Perrotta, Andrea; Primavera, Federica; Rossi, Antonio; Rovelli, Tiziano; Siroli, Gian Piero; Tosi, Nicolò; Albergo, Sebastiano; Di Mattia, Alessandro; Potenza, Renato; Tricomi, Alessia; Tuve, Cristina; Barbagli, Giuseppe; Chatterjee, Kalyanmoy; Ciulli, Vitaliano; Civinini, Carlo; D'Alessandro, Raffaello; Focardi, Ettore; Latino, Giuseppe; Lenzi, Piergiulio; Meschini, Marco; Paoletti, Simone; Russo, Lorenzo; Sguazzoni, Giacomo; Strom, Derek; Viliani, Lorenzo; Benussi, Luigi; Bianco, Stefano; Fabbri, Franco; Piccolo, Davide; Ferro, Fabrizio; Ravera, Fabio; Robutti, Enrico; Tosi, Silvano; Benaglia, Andrea; Beschi, Andrea; Brianza, Luca; Brivio, Francesco; Ciriolo, Vincenzo; Di Guida, Salvatore; Dinardo, Mauro Emanuele; Fiorendi, Sara; Gennai, Simone; Ghezzi, Alessio; Govoni, Pietro; Malberti, Martina; Malvezzi, Sandra; Massironi, Andrea; Menasce, Dario; Moroni, Luigi; Paganoni, Marco; Pedrini, Daniele; Ragazzi, Stefano; Tabarelli de Fatis, Tommaso; Zuolo, Davide; Buontempo, Salvatore; Cavallo, Nicola; Di Crescenzo, Antonia; Fabozzi, Francesco; Fienga, Francesco; Galati, Giuliana; Iorio, Alberto Orso Maria; Khan, Wajid Ali; Lista, Luca; Meola, Sabino; Paolucci, Pierluigi; Sciacca, Crisostomo; Voevodina, Elena; Azzi, Patrizia; Bacchetta, Nicola; Bisello, Dario; Boletti, Alessio; Bragagnolo, Alberto; Carlin, Roberto; Checchia, Paolo; Dall'Osso, Martino; De Castro Manzano, Pablo; Dorigo, Tommaso; Dosselli, Umberto; Gasparini, Fabrizio; Gasparini, Ugo; Gozzelino, Andrea; Hoh, Siew Yan; Lacaprara, Stefano; Lujan, Paul; Margoni, Martino; Meneguzzo, Anna Teresa; Pazzini, Jacopo; Ronchese, Paolo; Rossin, Roberto; Simonetto, Franco; Tiko, Andres; Torassa, Ezio; Zanetti, Marco; Zotto, Pierluigi; Zumerle, Gianni; Braghieri, Alessandro; Magnani, Alice; Montagna, Paolo; Ratti, Sergio P; Re, Valerio; Ressegotti, Martina; Riccardi, Cristina; Salvini, Paola; Vai, Ilaria; Vitulo, Paolo; Alunni Solestizi, Luisa; Biasini, Maurizio; Bilei, Gian Mario; Cecchi, Claudia; Ciangottini, Diego; Fanò, Livio; Lariccia, Paolo; Leonardi, Roberto; Manoni, Elisa; Mantovani, Giancarlo; Mariani, Valentina; Menichelli, Mauro; Rossi, Alessandro; Santocchia, Attilio; Spiga, Daniele; Androsov, Konstantin; Azzurri, Paolo; Bagliesi, Giuseppe; Bianchini, Lorenzo; Boccali, Tommaso; Borrello, Laura; Castaldi, Rino; Ciocci, Maria Agnese; Dell'Orso, Roberto; Fedi, Giacomo; Fiori, Francesco; Giannini, Leonardo; Giassi, Alessandro; Grippo, Maria Teresa; Ligabue, Franco; Manca, Elisabetta; Mandorli, Giulio; Messineo, Alberto; Palla, Fabrizio; Rizzi, Andrea; Spagnolo, Paolo; Tenchini, Roberto; Tonelli, Guido; Venturi, Andrea; Verdini, Piero Giorgio; Barone, Luciano; Cavallari, Francesca; Cipriani, Marco; Daci, Nadir; Del Re, Daniele; Di Marco, Emanuele; Diemoz, Marcella; Gelli, Simone; Longo, Egidio; Marzocchi, Badder; Meridiani, Paolo; Organtini, Giovanni; Pandolfi, Francesco; Paramatti, Riccardo; Preiato, Federico; Rahatlou, Shahram; Rovelli, Chiara; Santanastasio, Francesco; Amapane, Nicola; Arcidiacono, Roberta; Argiro, Stefano; Arneodo, Michele; Bartosik, Nazar; Bellan, Riccardo; Biino, Cristina; Cartiglia, Nicolo; Cenna, Francesca; Cometti, Simona; Costa, Marco; Covarelli, Roberto; Demaria, Natale; Kiani, Bilal; Mariotti, Chiara; Maselli, Silvia; Migliore, Ernesto; Monaco, Vincenzo; Monteil, Ennio; Monteno, Marco; Obertino, Maria Margherita; Pacher, Luca; Pastrone, Nadia; Pelliccioni, Mario; Pinna Angioni, Gian Luca; Romero, Alessandra; Ruspa, Marta; Sacchi, Roberto; Shchelina, Ksenia; Sola, Valentina; Solano, Ada; Soldi, Dario; Staiano, Amedeo; Belforte, Stefano; Candelise, Vieri; Casarsa, Massimo; Cossutti, Fabio; Della Ricca, Giuseppe; Vazzoler, Federico; Zanetti, Anna; Kim, Dong Hee; Kim, Gui Nyun; Kim, Min Suk; Lee, Jeongeun; Lee, Sangeun; Lee, Seh Wook; Moon, Chang-Seong; Oh, Young Do; Sekmen, Sezen; Son, Dong-Chul; Yang, Yu Chul; Kim, Hyunchul; Moon, Dong Ho; Oh, Geonhee; Goh, Junghwan; Kim, Tae Jeong; Cho, Sungwoong; Choi, Suyong; Go, Yeonju; Gyun, Dooyeon; Ha, Seungkyu; Hong, Byung-Sik; Jo, Youngkwon; Lee, Kisoo; Lee, Kyong Sei; Lee, Songkyo; Lim, Jaehoon; Park, Sung Keun; Roh, Youn; Kim, Hyunsoo; Almond, John; Kim, Junho; Kim, Jae Sung; Lee, Haneol; Lee, Kyeongpil; Nam, Kyungwook; Oh, Sung Bin; Radburn-Smith, Benjamin Charles; Seo, Seon-hee; Yang, Unki; Yoo, Hwi Dong; Yu, Geum Bong; Jeon, Dajeong; Kim, Hyunyong; Kim, Ji Hyun; Lee, Jason Sang Hun; Park, Inkyu; Choi, Young-Il; Hwang, Chanwook; Lee, Jongseok; Yu, Intae; Dudenas, Vytautas; Juodagalvis, Andrius; Vaitkus, Juozas; Ahmed, Ijaz; Ibrahim, Zainol Abidin; Md Ali, Mohd Adli Bin; Mohamad Idris, Faridah; Wan Abdullah, Wan Ahmad Tajuddin; Yusli, Mohd Nizam; Zolkapli, Zukhaimira; Castaneda Hernandez, Alfredo; Murillo Quijada, Javier Alberto; Duran-Osuna, Cecilia; Castilla-Valdez, Heriberto; De La Cruz-Burelo, Eduard; Ramirez-Sanchez, Gabriel; Heredia-De La Cruz, Ivan; Rabadán-Trejo, Raúl Iraq; Lopez-Fernandez, Ricardo; Mejia Guisao, Jhovanny; Reyes-Almanza, Rogelio; Ramírez García, Mateo; Sánchez Hernández, Alberto; Carrillo Moreno, Salvador; Oropeza Barrera, Cristina; Vazquez Valencia, Fabiola; Eysermans, Jan; Pedraza, Isabel; Salazar Ibarguen, Humberto Antonio; Uribe Estrada, Cecilia; Morelos Pineda, Antonio; Krofcheck, David; Bheesette, Srinidhi; Butler, Philip H; Ahmad, Ashfaq; Ahmad, Muhammad; Asghar, Muhammad Irfan; Hassan, Qamar; Hoorani, Hafeez R; Saddique, Asif; Shah, Mehar Ali; Shoaib, Muhammad; Waqas, Muhammad; Bialkowska, Helena; Bluj, Michal; Boimska, Bozena; Frueboes, Tomasz; Górski, Maciej; Kazana, Malgorzata; Nawrocki, Krzysztof; Szleper, Michal; Traczyk, Piotr; Zalewski, Piotr; Bunkowski, Karol; Byszuk, Adrian; Doroba, Krzysztof; Kalinowski, Artur; Konecki, Marcin; Krolikowski, Jan; Misiura, Maciej; Olszewski, Michal; Pyskir, Andrzej; Walczak, Marek; Araujo, Mariana; Bargassa, Pedrame; Beirão Da Cruz E Silva, Cristóvão; Di Francesco, Agostino; Faccioli, Pietro; Galinhas, Bruno; Gallinaro, Michele; Hollar, Jonathan; Leonardo, Nuno; Nemallapudi, Mythra Varun; Seixas, Joao; Strong, Giles; Toldaiev, Oleksii; Vadruccio, Daniele; Varela, Joao; Golunov, Alexey; Golutvin, Igor; Karjavine, Vladimir; Korenkov, Vladimir; Kozlov, Guennady; Lanev, Alexander; Malakhov, Alexander; Matveev, Viktor; Mitsyn, Valeri Valentinovitch; Moisenz, Petr; Palichik, Vladimir; Perelygin, Victor; Shmatov, Sergey; Shulha, Siarhei; Smirnov, Vitaly; Trofimov, Vladimir; Yuldashev, Bekhzod S; Zarubin, Anatoli; Zhiltsov, Victor; Golovtsov, Victor; Ivanov, Yury; Kim, Victor; Kuznetsova, Ekaterina; Levchenko, Petr; Murzin, Victor; Oreshkin, Vadim; Smirnov, Igor; Sosnov, Dmitry; Sulimov, Valentin; Uvarov, Lev; Vavilov, Sergey; Vorobyev, Alexey; Andreev, Yuri; Dermenev, Alexander; Gninenko, Sergei; Golubev, Nikolai; Karneyeu, Anton; Kirsanov, Mikhail; Krasnikov, Nikolai; Pashenkov, Anatoli; Tlisov, Danila; Toropin, Alexander; Epshteyn, Vladimir; Gavrilov, Vladimir; Lychkovskaya, Natalia; Popov, Vladimir; Pozdnyakov, Ivan; Safronov, Grigory; Spiridonov, Alexander; Stepennov, Anton; Stolin, Viatcheslav; Toms, Maria; Vlasov, Evgueni; Zhokin, Alexander; Aushev, Tagir; Chadeeva, Marina; Parygin, Pavel; Philippov, Dmitry; Polikarpov, Sergey; Popova, Elena; Rusinov, Vladimir; Andreev, Vladimir; Azarkin, Maksim; Dremin, Igor; Kirakosyan, Martin; Rusakov, Sergey V; Terkulov, Adel; Baskakov, Alexey; Belyaev, Andrey; Boos, Edouard; Ershov, Alexander; Gribushin, Andrey; Kaminskiy, Alexandre; Kodolova, Olga; Korotkikh, Vladimir; Lokhtin, Igor; Miagkov, Igor; Obraztsov, Stepan; Petrushanko, Sergey; Savrin, Viktor; Snigirev, Alexander; Vardanyan, Irina; Barnyakov, Alexander; Blinov, Vladimir; Dimova, Tatyana; Kardapoltsev, Leonid; Skovpen, Yuri; Azhgirey, Igor; Bayshev, Igor; Bitioukov, Sergei; Elumakhov, Dmitry; Godizov, Anton; Kachanov, Vassili; Kalinin, Alexey; Konstantinov, Dmitri; Mandrik, Petr; Petrov, Vladimir; Ryutin, Roman; Slabospitskii, Sergei; Sobol, Andrei; Troshin, Sergey; Tyurin, Nikolay; Uzunian, Andrey; Volkov, Alexey; Babaev, Anton; Baidali, Sergei; Okhotnikov, Vitalii; Adzic, Petar; Cirkovic, Predrag; Devetak, Damir; Dordevic, Milos; Milosevic, Jovan; Alcaraz Maestre, Juan; Álvarez Fernández, Adrian; Bachiller, Irene; Barrio Luna, Mar; Brochero Cifuentes, Javier Andres; Cerrada, Marcos; Colino, Nicanor; De La Cruz, Begona; Delgado Peris, Antonio; Fernandez Bedoya, Cristina; Fernández Ramos, Juan Pablo; Flix, Jose; Fouz, Maria Cruz; Gonzalez Lopez, Oscar; Goy Lopez, Silvia; Hernandez, Jose M; Josa, Maria Isabel; Moran, Dermot; Pérez-Calero Yzquierdo, Antonio María; Puerta Pelayo, Jesus; Redondo, Ignacio; Romero, Luciano; Senghi Soares, Mara; Triossi, Andrea; Albajar, Carmen; de Trocóniz, Jorge F; Cuevas, Javier; Erice, Carlos; Fernandez Menendez, Javier; Folgueras, Santiago; Gonzalez Caballero, Isidro; González Fernández, Juan Rodrigo; Palencia Cortezon, Enrique; Rodríguez Bouza, Víctor; Sanchez Cruz, Sergio; Vischia, Pietro; Vizan Garcia, Jesus Manuel; Cabrillo, Iban Jose; Calderon, Alicia; Chazin Quero, Barbara; Duarte Campderros, Jordi; Fernandez, Marcos; Fernández Manteca, Pedro José; García Alonso, Andrea; Garcia-Ferrero, Juan; Gomez, Gervasio; Lopez Virto, Amparo; Marco, Jesus; Martinez Rivero, Celso; Martinez Ruiz del Arbol, Pablo; Matorras, Francisco; Piedra Gomez, Jonatan; Prieels, Cédric; Rodrigo, Teresa; Ruiz-Jimeno, Alberto; Scodellaro, Luca; Trevisani, Nicolò; Vila, Ivan; Vilar Cortabitarte, Rocio; Abbaneo, Duccio; Akgun, Bora; Auffray, Etiennette; Baillon, Paul; Ball, Austin; Barney, David; Bendavid, Joshua; Bianco, Michele; Bocci, Andrea; Botta, Cristina; Brondolin, Erica; Camporesi, Tiziano; Cepeda, Maria; Cerminara, Gianluca; Chapon, Emilien; Chen, Yi; Cucciati, Giacomo; D'Enterria, David; Dabrowski, Anne; Daponte, Vincenzo; David Tinoco Mendes, Andre; De Roeck, Albert; Deelen, Nikkie; Dobson, Marc; Dünser, Marc; Dupont, Niels; Elliott-Peisert, Anna; Everaerts, Pieter; Fallavollita, Francesco; Fasanella, Daniele; Franzoni, Giovanni; Fulcher, Jonathan; Funk, Wolfgang; Gigi, Dominique; Gilbert, Andrew; Gill, Karl; Glege, Frank; Guilbaud, Maxime; Gulhan, Doga; Hegeman, Jeroen; Innocente, Vincenzo; Jafari, Abideh; Janot, Patrick; Karacheban, Olena; Kieseler, Jan; Kornmayer, Andreas; Krammer, Manfred; Lange, Clemens; Lecoq, Paul; Lourenco, Carlos; Malgeri, Luca; Mannelli, Marcello; Meijers, Frans; Merlin, Jeremie Alexandre; Mersi, Stefano; Meschi, Emilio; Milenovic, Predrag; Moortgat, Filip; Mulders, Martijn; Ngadiuba, Jennifer; Nourbakhsh, Shervin; Orfanelli, Styliani; Orsini, Luciano; Pantaleo, Felice; Pape, Luc; Perez, Emmanuel; Peruzzi, Marco; Petrilli, Achille; Petrucciani, Giovanni; Pfeiffer, Andreas; Pierini, Maurizio; Pitters, Florian Michael; Rabady, Dinyar; Racz, Attila; Reis, Thomas; Rolandi, Gigi; Rovere, Marco; Sakulin, Hannes; Schäfer, Christoph; Schwick, Christoph; Seidel, Markus; Selvaggi, Michele; Sharma, Archana; Silva, Pedro; Sphicas, Paraskevas; Stakia, Anna; Steggemann, Jan; Tosi, Mia; Treille, Daniel; Tsirou, Andromachi; Veckalns, Viesturs; Zeuner, Wolfram Dietrich; Caminada, Lea; Deiters, Konrad; Erdmann, Wolfram; Horisberger, Roland; Ingram, Quentin; Kaestli, Hans-Christian; Kotlinski, Danek; Langenegger, Urs; Rohe, Tilman; Wiederkehr, Stephan Albert; Backhaus, Malte; Bäni, Lukas; Berger, Pirmin; Chernyavskaya, Nadezda; Dissertori, Günther; Dittmar, Michael; Donegà, Mauro; Dorfer, Christian; Grab, Christoph; Heidegger, Constantin; Hits, Dmitry; Hoss, Jan; Klijnsma, Thomas; Lustermann, Werner; Manzoni, Riccardo Andrea; Marionneau, Matthieu; Meinhard, Maren Tabea; Micheli, Francesco; Musella, Pasquale; Nessi-Tedaldi, Francesca; Pata, Joosep; Pauss, Felicitas; Perrin, Gaël; Perrozzi, Luca; Pigazzini, Simone; Quittnat, Milena; Ruini, Daniele; Sanz Becerra, Diego Alejandro; Schönenberger, Myriam; Shchutska, Lesya; Tavolaro, Vittorio Raoul; Theofilatos, Konstantinos; Vesterbacka Olsson, Minna Leonora; Wallny, Rainer; Zhu, De Hua; Aarrestad, Thea Klaeboe; Amsler, Claude; Brzhechko, Danyyl; Canelli, Maria Florencia; De Cosa, Annapaola; Del Burgo, Riccardo; Donato, Silvio; Galloni, Camilla; Hreus, Tomas; Kilminster, Benjamin; Leontsinis, Stefanos; Neutelings, Izaak; Pinna, Deborah; Rauco, Giorgia; Robmann, Peter; Salerno, Daniel; Schweiger, Korbinian; Seitz, Claudia; Takahashi, Yuta; Zucchetta, Alberto; Chang, Yu-Hsiang; Cheng, Kai-yu; Doan, Thi Hien; Jain, Shilpi; Khurana, Raman; Kuo, Chia-Ming; Lin, Willis; Pozdnyakov, Andrey; Yu, Shin-Shan; Chang, Paoti; Chao, Yuan; Chen, Kai-Feng; Chen, Po-Hsun; Hou, George Wei-Shu; Kumar, Arun; Li, You-ying; Liu, Yueh-Feng; Lu, Rong-Shyang; Paganis, Efstathios; Psallidas, Andreas; Steen, Arnaud; Asavapibhop, Burin; Srimanobhas, Norraphat; Suwonjandee, Narumon; Bat, Ayse; Boran, Fatma; Cerci, Salim; Damarseckin, Serdal; Demiroglu, Zuhal Seyma; Dolek, Furkan; Dozen, Candan; Dumanoglu, Isa; Girgis, Semiray; Gokbulut, Gul; Guler, Yalcin; Gurpinar, Emine; Hos, Ilknur; Isik, Candan; Kangal, Evrim Ersin; Kara, Ozgun; Kayis Topaksu, Aysel; Kiminsu, Ugur; Oglakci, Mehmet; Onengut, Gulsen; Ozdemir, Kadri; Ozturk, Sertac; Sunar Cerci, Deniz; Tali, Bayram; Tok, Ufuk Guney; Turkcapar, Semra; Zorbakir, Ibrahim Soner; Zorbilmez, Caglar; Isildak, Bora; Karapinar, Guler; Yalvac, Metin; Zeyrek, Mehmet; Atakisi, Ismail Okan; Gülmez, Erhan; Kaya, Mithat; Kaya, Ozlem; Tekten, Sevgi; Yetkin, Elif Asli; Agaras, Merve Nazlim; Atay, Serhat; Cakir, Altan; Cankocak, Kerem; Komurcu, Yildiray; Sen, Sercan; Grynyov, Boris; Levchuk, Leonid; Ball, Fionn; Beck, Lana; Brooke, James John; Burns, Douglas; Clement, Emyr; Cussans, David; Davignon, Olivier; Flacher, Henning; Goldstein, Joel; Heath, Greg P; Heath, Helen F; Kreczko, Lukasz; Newbold, Dave M; Paramesvaran, Sudarshan; Penning, Bjoern; Sakuma, Tai; Smith, Dominic; Smith, Vincent J; Taylor, Joseph; Titterton, Alexander; Belyaev, Alexander; Brew, Christopher; Brown, Robert M; Cieri, Davide; Cockerill, David JA; Coughlan, John A; Harder, Kristian; Harper, Sam; Linacre, Jacob; Olaiya, Emmanuel; Petyt, David; Shepherd-Themistocleous, Claire; Thea, Alessandro; Tomalin, Ian R; Williams, Thomas; Womersley, William John; Auzinger, Georg; Bainbridge, Robert; Bloch, Philippe; Borg, Johan; Breeze, Shane; Buchmuller, Oliver; Bundock, Aaron; Casasso, Stefano; Colling, David; Corpe, Louie; Dauncey, Paul; Davies, Gavin; Della Negra, Michel; Di Maria, Riccardo; Haddad, Yacine; Hall, Geoffrey; Iles, Gregory; James, Thomas; Komm, Matthias; Laner, Christian; Lyons, Louis; Magnan, Anne-Marie; Malik, Sarah; Martelli, Arabella; Nash, Jordan; Nikitenko, Alexander; Palladino, Vito; Pesaresi, Mark; Richards, Alexander; Rose, Andrew; Scott, Edward; Seez, Christopher; Shtipliyski, Antoni; Singh, Gurpreet; Stoye, Markus; Strebler, Thomas; Summers, Sioni; Tapper, Alexander; Uchida, Kirika; Virdee, Tejinder; Wardle, Nicholas; Winterbottom, Daniel; Wright, Jack; Zenz, Seth Conrad; Cole, Joanne; Hobson, Peter R; Khan, Akram; Kyberd, Paul; Mackay, Catherine Kirsty; Morton, Alexander; Reid, Ivan; Teodorescu, Liliana; Zahid, Sema; Call, Kenneth; Dittmann, Jay; Hatakeyama, Kenichi; Liu, Hongxuan; Madrid, Christopher; Mcmaster, Brooks; Pastika, Nathaniel; Smith, Caleb; Bartek, Rachel; Dominguez, Aaron; Buccilli, Andrew; Cooper, Seth; Henderson, Conor; Rumerio, Paolo; West, Christopher; Arcaro, Daniel; Bose, Tulika; Gastler, Daniel; Rankin, Dylan; Richardson, Clint; Rohlf, James; Sulak, Lawrence; Zou, David; Benelli, Gabriele; Coubez, Xavier; Cutts, David; Hadley, Mary; Hakala, John; Heintz, Ulrich; Hogan, Julie Managan; Kwok, Ka Hei Martin; Laird, Edward; Landsberg, Greg; Lee, Jangbae; Mao, Zaixing; Narain, Meenakshi; Piperov, Stefan; Sagir, Sinan; Syarif, Rizki; Usai, Emanuele; Yu, David; Band, Reyer; Brainerd, Christopher; Breedon, Richard; Burns, Dustin; Calderon De La Barca Sanchez, Manuel; Chertok, Maxwell; Conway, John; Conway, Rylan; Cox, Peter Timothy; Erbacher, Robin; Flores, Chad; Funk, Garrett; Ko, Winston; Kukral, Ota; Lander, Richard; Mulhearn, Michael; Pellett, Dave; Pilot, Justin; Shalhout, Shalhout; Shi, Mengyao; Stolp, Dustin; Taylor, Devin; Tos, Kyle; Tripathi, Mani; Wang, Zhangqier; Zhang, Fengwangdong; Bachtis, Michail; Bravo, Cameron; Cousins, Robert; Dasgupta, Abhigyan; Florent, Alice; Hauser, Jay; Ignatenko, Mikhail; Mccoll, Nickolas; Regnard, Simon; Saltzberg, David; Schnaible, Christian; Valuev, Vyacheslav; Bouvier, Elvire; Burt, Kira; Clare, Robert; Gary, J William; Ghiasi Shirazi, Seyyed Mohammad Amin; Hanson, Gail; Karapostoli, Georgia; Kennedy, Elizabeth; Lacroix, Florent; Long, Owen Rosser; Olmedo Negrete, Manuel; Paneva, Mirena Ivova; Si, Weinan; Wang, Long; Wei, Hua; Wimpenny, Stephen; Yates, Brent; Branson, James G; Cittolin, Sergio; Derdzinski, Mark; Gerosa, Raffaele; Gilbert, Dylan; Hashemi, Bobak; Holzner, André; Klein, Daniel; Kole, Gouranga; Krutelyov, Vyacheslav; Letts, James; Masciovecchio, Mario; Olivito, Dominick; Padhi, Sanjay; Pieri, Marco; Sani, Matteo; Sharma, Vivek; Simon, Sean; Tadel, Matevz; Vartak, Adish; Wasserbaech, Steven; Wood, John; Würthwein, Frank; Yagil, Avraham; Zevi Della Porta, Giovanni; Amin, Nick; Bhandari, Rohan; Bradmiller-Feld, John; Campagnari, Claudio; Citron, Matthew; Dishaw, Adam; Dutta, Valentina; Franco Sevilla, Manuel; Gouskos, Loukas; Heller, Ryan; Incandela, Joe; Ovcharova, Ana; Qu, Huilin; Richman, Jeffrey; Stuart, David; Suarez, Indara; Wang, Sicheng; Yoo, Jaehyeok; Anderson, Dustin; Bornheim, Adolf; Lawhorn, Jay Mathew; Newman, Harvey B; Nguyen, Thong; Spiropulu, Maria; Vlimant, Jean-Roch; Wilkinson, Richard; Xie, Si; Zhang, Zhicai; Zhu, Ren-Yuan; Andrews, Michael Benjamin; Ferguson, Thomas; Mudholkar, Tanmay; Paulini, Manfred; Sun, Menglei; Vorobiev, Igor; Weinberg, Marc; Cumalat, John Perry; Ford, William T; Jensen, Frank; Johnson, Andrew; Krohn, Michael; MacDonald, Emily; Mulholland, Troy; Stenson, Kevin; Ulmer, Keith; Wagner, Stephen Robert; Alexander, James; Chaves, Jorge; Cheng, Yangyang; Chu, Jennifer; Datta, Abhisek; Mcdermott, Kevin; Mirman, Nathan; Patterson, Juliet Ritchie; Quach, Dan; Rinkevicius, Aurelijus; Ryd, Anders; Skinnari, Louise; Soffi, Livia; Tan, Shao Min; Tao, Zhengcheng; Thom, Julia; Tucker, Jordan; Wittich, Peter; Zientek, Margaret; Abdullin, Salavat; Albrow, Michael; Alyari, Maral; Apollinari, Giorgio; Apresyan, Artur; Apyan, Aram; Banerjee, Sunanda; Bauerdick, Lothar AT; Beretvas, Andrew; Berryhill, Jeffrey; Bhat, Pushpalatha C; Bolla, Gino; Burkett, Kevin; Butler, Joel Nathan; Canepa, Anadi; Cerati, Giuseppe Benedetto; Cheung, Harry; Chlebana, Frank; Cremonesi, Matteo; Duarte, Javier; Elvira, Victor Daniel; Freeman, Jim; Gecse, Zoltan; Gottschalk, Erik; Gray, Lindsey; Green, Dan; Grünendahl, Stefan; Gutsche, Oliver; Hanlon, Jim; Harris, Robert M; Hasegawa, Satoshi; Hirschauer, James; Hu, Zhen; Jayatilaka, Bodhitha; Jindariani, Sergo; Johnson, Marvin; Joshi, Umesh; Klima, Boaz; Kortelainen, Matti J; Kreis, Benjamin; Lammel, Stephan; Lincoln, Don; Lipton, Ron; Liu, Miaoyuan; Liu, Tiehui; Lykken, Joseph; Maeshima, Kaori; Marraffino, John Michael; Mason, David; McBride, Patricia; Merkel, Petra; Mrenna, Stephen; Nahn, Steve; O'Dell, Vivian; Pedro, Kevin; Pena, Cristian; Prokofyev, Oleg; Rakness, Gregory; Ristori, Luciano; Savoy-Navarro, Aurore; Schneider, Basil; Sexton-Kennedy, Elizabeth; Soha, Aron; Spalding, William J; Spiegel, Leonard; Stoynev, Stoyan; Strait, James; Strobbe, Nadja; Taylor, Lucas; Tkaczyk, Slawek; Tran, Nhan Viet; Uplegger, Lorenzo; Vaandering, Eric Wayne; Vernieri, Caterina; Verzocchi, Marco; Vidal, Richard; Wang, Michael; Weber, Hannsjoerg Artur; Whitbeck, Andrew; Acosta, Darin; Avery, Paul; Bortignon, Pierluigi; Bourilkov, Dimitri; Brinkerhoff, Andrew; Cadamuro, Luca; Carnes, Andrew; Carver, Matthew; Curry, David; Field, Richard D; Gleyzer, Sergei V; Joshi, Bhargav Madhusudan; Konigsberg, Jacobo; Korytov, Andrey; Ma, Peisen; Matchev, Konstantin; Mei, Hualin; Mitselmakher, Guenakh; Shi, Kun; Sperka, David; Wang, Jian; Wang, Sean-Jiun; Joshi, Yagya Raj; Linn, Stephan; Ackert, Andrew; Adams, Todd; Askew, Andrew; Hagopian, Sharon; Hagopian, Vasken; Johnson, Kurtis F; Kolberg, Ted; Martinez, German; Perry, Thomas; Prosper, Harrison; Saha, Anirban; Schiber, Catherine; Sharma, Varun; Yohay, Rachel; Baarmand, Marc M; Bhopatkar, Vallary; Colafranceschi, Stefano; Hohlmann, Marcus; Noonan, Daniel; Rahmani, Mehdi; Roy, Titas; Yumiceva, Francisco; Adams, Mark Raymond; Apanasevich, Leonard; Berry, Douglas; Betts, Russell Richard; Cavanaugh, Richard; Chen, Xuan; Dittmer, Susan; Evdokimov, Olga; Gerber, Cecilia Elena; Hangal, Dhanush Anil; Hofman, David Jonathan; Jung, Kurt; Kamin, Jason; Mills, Corrinne; Sandoval Gonzalez, Irving Daniel; Tonjes, Marguerite; Varelas, Nikos; Wang, Hui; Wang, Xiao; Wu, Zhenbin; Zhang, Jingyu; Alhusseini, Mohammad; Bilki, Burak; Clarida, Warren; Dilsiz, Kamuran; Durgut, Süleyman; Gandrajula, Reddy Pratap; Haytmyradov, Maksat; Khristenko, Viktor; Merlo, Jean-Pierre; Mestvirishvili, Alexi; Moeller, Anthony; Nachtman, Jane; Ogul, Hasan; Onel, Yasar; Ozok, Ferhat; Penzo, Aldo; Snyder, Christina; Tiras, Emrah; Wetzel, James; Blumenfeld, Barry; Cocoros, Alice; Eminizer, Nicholas; Fehling, David; Feng, Lei; Gritsan, Andrei; Hung, Wai Ting; Maksimovic, Petar; Roskes, Jeffrey; Sarica, Ulascan; Swartz, Morris; Xiao, Meng; You, Can; Al-bataineh, Ayman; Baringer, Philip; Bean, Alice; Boren, Samuel; Bowen, James; Bylinkin, Alexander; Castle, James; Khalil, Sadia; Kropivnitskaya, Anna; Majumder, Devdatta; Mcbrayer, William; Murray, Michael; Rogan, Christopher; Sanders, Stephen; Schmitz, Erich; Tapia Takaki, Daniel; Wang, Quan; Duric, Senka; Ivanov, Andrew; Kaadze, Ketino; Kim, Doyeong; Maravin, Yurii; Mendis, Dalath Rachitha; Mitchell, Tyler; Modak, Atanu; Mohammadi, Abdollah; Saini, Lovedeep Kaur; Skhirtladze, Nikoloz; Rebassoo, Finn; Wright, Douglas; Baden, Drew; Baron, Owen; Belloni, Alberto; Eno, Sarah Catherine; Feng, Yongbin; Ferraioli, Charles; Hadley, Nicholas John; Jabeen, Shabnam; Jeng, Geng-Yuan; Kellogg, Richard G; Kunkle, Joshua; Mignerey, Alice; Ricci-Tam, Francesca; Shin, Young Ho; Skuja, Andris; Tonwar, Suresh C; Wong, Kak; Abercrombie, Daniel; Allen, Brandon; Azzolini, Virginia; Baty, Austin; Bauer, Gerry; Bi, Ran; Brandt, Stephanie; Busza, Wit; Cali, Ivan Amos; D'Alfonso, Mariarosaria; Demiragli, Zeynep; Gomez Ceballos, Guillelmo; Goncharov, Maxim; Harris, Philip; Hsu, Dylan; Hu, Miao; Iiyama, Yutaro; Innocenti, Gian Michele; Klute, Markus; Kovalskyi, Dmytro; Lee, Yen-Jie; Luckey, Paul David; Maier, Benedikt; Marini, Andrea Carlo; Mcginn, Christopher; Mironov, Camelia; Narayanan, Siddharth; Niu, Xinmei; Paus, Christoph; Roland, Christof; Roland, Gunther; Stephans, George; Sumorok, Konstanty; Tatar, Kaya; Velicanu, Dragos; Wang, Jing; Wang, Ta-Wei; Wyslouch, Bolek; Zhaozhong, Shi; Benvenuti, Alberto; Chatterjee, Rajdeep Mohan; Evans, Andrew; Hansen, Peter; Kalafut, Sean; Kubota, Yuichi; Lesko, Zachary; Mans, Jeremy; Ruckstuhl, Nicole; Rusack, Roger; Turkewitz, Jared; Wadud, Mohammad Abrar; Acosta, John Gabriel; Oliveros, Sandra; Avdeeva, Ekaterina; Bloom, Kenneth; Claes, Daniel R; Fangmeier, Caleb; Golf, Frank; Gonzalez Suarez, Rebeca; Kamalieddin, Rami; Kravchenko, Ilya; Monroy, Jose; Siado, Joaquin Emilo; Snow, Gregory R; Stieger, Benjamin; Godshalk, Andrew; Harrington, Charles; Iashvili, Ia; Kharchilava, Avto; Mclean, Christine; Nguyen, Duong; Parker, Ashley; Rappoccio, Salvatore; Roozbahani, Bahareh; Barberis, Emanuela; Freer, Chad; Hortiangtham, Apichart; Morse, David Michael; Orimoto, Toyoko; Teixeira De Lima, Rafael; Wamorkar, Tanvi; Wang, Bingran; Wisecarver, Andrew; Wood, Darien; Bhattacharya, Saptaparna; Charaf, Otman; Hahn, Kristan Allan; Mucia, Nicholas; Odell, Nathaniel; Schmitt, Michael Henry; Sung, Kevin; Trovato, Marco; Velasco, Mayda; Bucci, Rachael; Dev, Nabarun; Hildreth, Michael; Hurtado Anampa, Kenyi; Jessop, Colin; Karmgard, Daniel John; Kellams, Nathan; Lannon, Kevin; Li, Wenzhao; Loukas, Nikitas; Marinelli, Nancy; Meng, Fanbo; Mueller, Charles; Musienko, Yuri; Planer, Michael; Reinsvold, Allison; Ruchti, Randy; Siddireddy, Prasanna; Smith, Geoffrey; Taroni, Silvia; Wayne, Mitchell; Wightman, Andrew; Wolf, Matthias; Woodard, Anna; Alimena, Juliette; Antonelli, Louis; Bylsma, Ben; Durkin, Lloyd Stanley; Flowers, Sean; Francis, Brian; Hart, Andrew; Hill, Christopher; Ji, Weifeng; Ling, Ta-Yung; Luo, Wuming; Winer, Brian L; Wulsin, Howard Wells; Cooperstein, Stephane; Elmer, Peter; Hardenbrook, Joshua; Higginbotham, Samuel; Kalogeropoulos, Alexis; Lange, David; Lucchini, Marco Toliman; Luo, Jingyu; Marlow, Daniel; Mei, Kelvin; Ojalvo, Isabel; Olsen, James; Palmer, Christopher; Piroué, Pierre; Salfeld-Nebgen, Jakob; Stickland, David; Tully, Christopher; Malik, Sudhir; Norberg, Scarlet; Barker, Anthony; Barnes, Virgil E; Das, Souvik; Gutay, Laszlo; Jones, Matthew; Jung, Andreas Werner; Khatiwada, Ajeeta; Mahakud, Bibhuprasad; Miller, David Harry; Neumeister, Norbert; Peng, Cheng-Chieh; Qiu, Hao; Schulte, Jan-Frederik; Sun, Jian; Wang, Fuqiang; Xiao, Rui; Xie, Wei; Cheng, Tongguang; Dolen, James; Parashar, Neeti; Chen, Zhenyu; Ecklund, Karl Matthew; Freed, Sarah; Geurts, Frank JM; Kilpatrick, Matthew; Li, Wei; Michlin, Benjamin; Padley, Brian Paul; Roberts, Jay; Rorie, Jamal; Shi, Wei; Tu, Zhoudunming; Zabel, James; Zhang, Aobo; Bodek, Arie; de Barbaro, Pawel; Demina, Regina; Duh, Yi-ting; Dulemba, Joseph Lynn; Fallon, Colin; Ferbel, Thomas; Galanti, Mario; Garcia-Bellido, Aran; Han, Jiyeon; Hindrichs, Otto; Khukhunaishvili, Aleko; Lo, Kin Ho; Tan, Ping; Taus, Rhys; Verzetti, Mauro; Agapitos, Antonis; Chou, John Paul; Gershtein, Yuri; Gómez Espinosa, Tirso Alejandro; Halkiadakis, Eva; Heindl, Maximilian; Hughes, Elliot; Kaplan, Steven; Kunnawalkam Elayavalli, Raghav; Kyriacou, Savvas; Lath, Amitabh; Montalvo, Roy; Nash, Kevin; Osherson, Marc; Saka, Halil; Salur, Sevil; Schnetzer, Steve; Sheffield, David; Somalwar, Sunil; Stone, Robert; Thomas, Scott; Thomassen, Peter; Walker, Matthew; Delannoy, Andrés G; Heideman, Joseph; Riley, Grant; Spanier, Stefan; Thapa, Krishna; Bouhali, Othmane; Celik, Ali; Dalchenko, Mykhailo; De Mattia, Marco; Delgado, Andrea; Dildick, Sven; Eusebi, Ricardo; Gilmore, Jason; Huang, Tao; Kamon, Teruki; Luo, Sifu; Mueller, Ryan; Patel, Rishi; Perloff, Alexx; Perniè, Luca; Rathjens, Denis; Safonov, Alexei; Akchurin, Nural; Damgov, Jordan; De Guio, Federico; Dudero, Phillip Russell; Kunori, Shuichi; Lamichhane, Kamal; Lee, Sung Won; Mengke, Tielige; Muthumuni, Samila; Peltola, Timo; Undleeb, Sonaina; Volobouev, Igor; Wang, Zhixing; Greene, Senta; Gurrola, Alfredo; Janjam, Ravi; Johns, Willard; Maguire, Charles; Melo, Andrew; Ni, Hong; Padeken, Klaas; Ruiz Alvarez, José David; Sheldon, Paul; Tuo, Shengquan; Velkovska, Julia; Verweij, Marta; Xu, Qiao; Arenton, Michael Wayne; Barria, Patrizia; Cox, Bradley; Hirosky, Robert; Joyce, Matthew; Ledovskoy, Alexander; Li, Hengne; Neu, Christopher; Sinthuprasith, Tutanon; Wang, Yanchu; Wolfe, Evan; Xia, Fan; Harr, Robert; Karchin, Paul Edmund; Poudyal, Nabin; Sturdy, Jared; Thapa, Prakash; Zaleski, Shawn; Brodski, Michael; Buchanan, James; Caillol, Cécile; Carlsmith, Duncan; Dasu, Sridhara; Dodd, Laura; Gomber, Bhawna; Grothe, Monika; Herndon, Matthew; Hervé, Alain; Hussain, Usama; Klabbers, Pamela; Lanaro, Armando; Long, Kenneth; Loveless, Richard; Ruggles, Tyler; Savin, Alexander; Smith, Nicholas; Smith, Wesley H; Woods, Nathaniel
2018-01-01
The pseudorapidity distributions of dijets as a function of their average transverse momentum ($ p_{\\mathrm{T}}^{text{ave}} $) are measured in proton-lead (pPb) and proton-proton (pp) collisions. The data samples were collected by the CMS experiment at the CERN LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. A significant modification of the pPb spectra with respect to the pp spectra is observed in all $p_{\\mathrm{T}}^{text{ave}}$ intervals investigated. The ratios of the pPb and pp distributions are compared to next-to-leading order perturbative quantum chromodynamics calculations with unbound nucleon and nuclear parton distribution functions (PDFs). These results give the first evidence that the gluon PDF at large Bjorken $x$ in lead ions is strongly suppressed with respect to the PDF in unbound nucleons.
Forte, Stefano; Ridolfi, G; Forte, Stefano; Mangano, Michelangelo L.; Ridolfi, Giovanni
2001-01-01
We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Delta q-Delta qbar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure.
International Nuclear Information System (INIS)
Forte, Stefano; Mangano, Michelangelo L.; Ridolfi, Giovanni
2001-01-01
We discuss the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments. We summarize the next-to-leading-order treatment of charged-current polarized structure functions, their relation to polarized parton distributions and scale dependence, and discuss their description by means of a next-to-leading-order evolution code. We discuss current theoretical expectations and positivity constraints on the unmeasured C-odd combinations Δq-Δq-bar of polarized quark distributions, and their determination in charged-current deep-inelastic scattering experiments. We give estimates of the expected errors on charged-current structure functions at a future neutrino factory, and perform a study of the accuracy in the determination of polarized parton distributions that would be possible at such a facility. We show that these measurements have the potential to distinguish between different theoretical scenarios for the proton spin structure
Rapidity evolution of gluon TMD from low to moderate x
International Nuclear Information System (INIS)
Balitsky, I.
2016-01-01
I discuss how the rapidity evolution of gluon transverse momentum dependent distribution (TMD) changes from nonlinear evolution at small x << 1 to linear evolution at moderate x ∼ 1. I have described the rapidity evolution of gluon TMD in the whole range of Bjorken x B and the whole range of transverse momentum. It should be emphasized that with our definition of rapidity cutoff the leading-order matrix elements of TMD operators are UV-finite so the rapidity evolution is the only evolution and it describes all the dynamics of gluon TMDs in the leading-log approximation
Production and recombination of gluons
International Nuclear Information System (INIS)
Temiraliev, A.T.
2006-01-01
Full text: Nonlinear Markov process of parton production has been considered. The Kolmogorov equation is applied for the evolution equation based on the approximation of independent gluons production in every decay act. We introduced a 'crossing' parameter and used the combination relations to obtain nonlinear recombination equation for the evolution of gluon structure function. (author)
Liu, Hong; Zhu, Jingping; Wang, Kai
2015-08-24
The geometrical attenuation model given by Blinn was widely used in the geometrical optics bidirectional reflectance distribution function (BRDF) models. Blinn's geometrical attenuation model based on symmetrical V-groove assumption and ray scalar theory causes obvious inaccuracies in BRDF curves and negatives the effects of polarization. Aiming at these questions, a modified polarized geometrical attenuation model based on random surface microfacet theory is presented by combining of masking and shadowing effects and polarized effect. The p-polarized, s-polarized and unpolarized geometrical attenuation functions are given in their separate expressions and are validated with experimental data of two samples. It shows that the modified polarized geometrical attenuation function reaches better physical rationality, improves the precision of BRDF model, and widens the applications for different polarization.
From Color Fields to Quark Gluon Plasma
Energy Technology Data Exchange (ETDEWEB)
Fries, Rainer J. [School of Physics and Astronomy, University of Minnesota, Minneapolis MN 55455 (United States); Kapusta, Joseph I. [School of Physics and Astronomy, University of Minnesota, Minneapolis MN 55455 (United States); Li, Yang [School of Physics and Astronomy, University of Minnesota, Minneapolis MN 55455 (United States)
2006-08-07
We discuss a model for the energy distribution and the early space-time evolution of a heavy ion collision. We estimate the gluon field generated in the wake of hard processes and through primordial fluctuations of the color charges in the nuclei. Without specifying the dynamical mechanism of thermalization we calculate the energy momentum tensor of the following plasma phase. The results of this model can be used as initial conditions for a further hydrodynamic evolution.
Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Alfred, M.; Apadula, N.; Aramaki, Y.; Asano, H.; Atomssa, E. T.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Bandara, N. S.; Bannier, B.; Barish, K. N.; Bathe, S.; Bazilevsky, A.; Beaumier, M.; Beckman, S.; Belmont, R.; Berdnikov, A.; Berdnikov, Y.; Black, D.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Bryslawskyj, J.; Buesching, H.; Bumazhnov, V.; Campbell, S.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Chujo, T.; Citron, Z.; Csanád, M.; Csörgő, T.; Danley, T. W.; Datta, A.; Daugherity, M. S.; David, G.; Deblasio, K.; Dehmelt, K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Ding, L.; Dion, A.; Diss, P. B.; Do, J. H.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Feege, N.; Fields, D. E.; Finger, M.; Finger, M.; Fokin, S. L.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Gal, C.; Gallus, P.; Garg, P.; Ge, H.; Giordano, F.; Glenn, A.; Goto, Y.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gu, Y.; Gunji, T.; Guragain, H.; Hachiya, T.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamilton, H. F.; Han, S. Y.; Hanks, J.; Hasegawa, S.; Haseler, T. O. S.; Hashimoto, K.; He, X.; Hemmick, T. K.; Hill, J. C.; Hollis, R. S.; Homma, K.; Hong, B.; Hoshino, T.; Hotvedt, N.; Huang, J.; Huang, S.; Ikeda, Y.; Imai, K.; Imazu, Y.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ivanishchev, D.; Jacak, B. V.; Jeon, S. J.; Jezghani, M.; Jia, J.; Jiang, X.; Johnson, B. M.; Joo, E.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kanda, S.; Kang, J. H.; Kang, J. S.; Kawall, D.; Kazantsev, A. V.; Key, J. A.; Khachatryan, V.; Khanzadeev, A.; Kihara, K.; Kim, C.; Kim, D. H.; Kim, D. J.; Kim, E.-J.; Kim, G. W.; Kim, H.-J.; Kim, M.; Kim, Y. K.; Kimelman, B.; Kistenev, E.; Kitamura, R.; Klatsky, J.; Kleinjan, D.; Kline, P.; Koblesky, T.; Kofarago, M.; Komkov, B.; Koster, J.; Kotov, D.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Lacey, R.; Lajoie, J. G.; Lebedev, A.; Lee, K. B.; Lee, S.; Lee, S. H.; Leitch, M. J.; Leitgab, M.; Li, X.; Lim, S. H.; Liu, M. X.; Lynch, D.; Makdisi, Y. I.; Makek, M.; Manion, A.; Manko, V. I.; Mannel, E.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Meles, A.; Mendoza, M.; Meredith, B.; Miake, Y.; Mignerey, A. C.; Miller, A. J.; Milov, A.; Mishra, D. K.; Mitchell, J. T.; Miyasaka, S.; Mizuno, S.; Mohanty, A. K.; Montuenga, P.; Moon, T.; Morrison, D. P.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Mwai, A.; Nagamiya, S.; Nagashima, K.; Nagle, J. L.; Nagy, M. I.; Nakagawa, I.; Nakagomi, H.; Nakano, K.; Nattrass, C.; Netrakanti, P. K.; Nihashi, M.; Niida, T.; Nishimura, S.; Nouicer, R.; Novák, T.; Novitzky, N.; Nyanin, A. S.; O'Brien, E.; Ogilvie, C. A.; Orjuela Koop, J. D.; Osborn, J. D.; Oskarsson, A.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, J. S.; Park, S.; Pate, S. F.; Patel, L.; Patel, M.; Peng, J.-C.; Perepelitsa, D. V.; Perera, G. D. N.; Peressounko, D. Yu.; Perry, J.; Petti, R.; Pinkenburg, C.; Pinson, R.; Pisani, R. P.; Purschke, M. L.; Rak, J.; Ramson, B. J.; Ravinovich, I.; Read, K. F.; Reynolds, D.; Riabov, V.; Riabov, Y.; Rinn, T.; Riveli, N.; Roach, D.; Rolnick, S. D.; Rosati, M.; Rowan, Z.; Rubin, J. G.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sako, H.; Samsonov, V.; Sarsour, M.; Sato, S.; Sawada, S.; Schaefer, B.; Schmoll, B. K.; Sedgwick, K.; Seele, J.; Seidl, R.; Sen, A.; Seto, R.; Sett, P.; Sexton, A.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Snowball, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stepanov, M.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sumita, T.; Sun, J.; Sziklai, J.; Takahara, A.; Taketani, A.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tieulent, R.; Timilsina, A.; Todoroki, T.; Tomášek, M.; Torii, H.; Towell, C. L.; Towell, M.; Towell, R.; Towell, R. S.; Tserruya, I.; van Hecke, H. W.; Vargyas, M.; Velkovska, J.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, Y.; Watanabe, Y. S.; Wei, F.; Whitaker, S.; White, A. S.; Wolin, S.; Woody, C. L.; Wysocki, M.; Xia, B.; Xue, L.; Yalcin, S.; Yamaguchi, Y. L.; Yanovich, A.; Yoo, J. H.; Yoon, I.; Younus, I.; Yu, H.; Yushmanov, I. E.; Zajc, W. A.; Zelenski, A.; Zhou, S.; Zou, L.; Phenix Collaboration
2016-12-01
We report the double-helicity asymmetry, ALL J /ψ, in inclusive J /ψ production at forward rapidity as a function of transverse momentum pT and rapidity |y |. The data analyzed were taken during √{s }=510 GeV longitudinally polarized p +p collisions at the Relativistic Heavy Ion Collider in the 2013 run using the PHENIX detector. At this collision energy, J /ψ particles are predominantly produced through gluon-gluon scatterings, thus ALL J /ψ is sensitive to the gluon polarization inside the proton. We measured ALL J /ψ by detecting the decay daughter muon pairs μ+μ- within the PHENIX muon spectrometers in the rapidity range 1.2 <|y |<2.2 . In this kinematic range, we measured the ALL J /ψ to be 0.012 ±0.010 (stat) ±0.003 (syst). The ALL J /ψ can be expressed to be proportional to the product of the gluon polarization distributions at two distinct ranges of Bjorken x : one at moderate range x ≈5 ×10-2 where recent data of jet and π0 double helicity spin asymmetries have shown evidence for significant gluon polarization, and the other one covering the poorly known small-x region x ≈2 ×10-3. Thus our new results could be used to further constrain the gluon polarization for x <5 ×10-2.
Calculation of parton fragmentation functions from jet calculus: gluon applications
International Nuclear Information System (INIS)
Lassila, K.E.; Ng, A.
1985-01-01
A method is presented for calculation of general parton fragmentation functions based on jet calculus plus meson and baryon wave functions. Results for gluon fragmentation into mesons and baryons are discussed and related to recent information on upsilon decay into gluons. The expressions derived can be used directly in e + e - cross section predictions and will need to be folded in with baryon parton distribution functions when used in p-barp collisions. (author)
Phenomenological Evidence for Gluon Depletion in pA Collisions
Hwa, R. C.; Pisut, J.; Pisutova, N.
2000-01-01
The data of J/psi suppression at large x_F in pA collisions are used to infer the existence of gluon depletion as the projectile proton traverses the nucleus. The modification of the gluon distribution is studied by use of a convolution equation whose non-perturbative splitting function is determined phenomenologically. The depletion factor at x_1=0.8 is found to be about 25% at A=100.
International Nuclear Information System (INIS)
Fredriksson, S.
1984-01-01
The Stockholm diquark is a very small (0.1-0.2 fm), bound pair of two unequal quarks in spin 0 and colour 3*. If it exists, it is expected to simulate many of the trends presently attributed to perturbative gluon processes. The Stockholm group (S. Ekelin, M. Jaendel, T.I. Larson and myself) is therefore looking for reactions where the non-perturbative QCD phenomenon of diquark formation would give signatures completely different from those of perturbative gluonic contributions. I report here on some new suggestions for diquark effects in deep inelastic scattering, with emphasis on neutron-proton differences, proton production in the current fragmentation region and nuclear target (''EMC'') effects
Intrinsically stable phase-modulated polarization encoding system for quantum key distribution
Energy Technology Data Exchange (ETDEWEB)
Liu Xiaobao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China); Liao Changjun [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)], E-mail: chliao@scnu.edu.cn; Mi Jinglong; Wang Jindong; Liu Songhao [Laboratory of Photonic Information Technology, School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510006 (China)
2008-12-22
We demonstrate experimentally an intrinsically stable polarization coding and decoding system composed of optical-fiber Sagnac interferometers with integrated phase modulators for quantum key distribution. An interference visibility of 98.35% can be kept longtime during the experiment without any efforts of active compensation for coding all four desired polarization states.
Czech Academy of Sciences Publication Activity Database
Adare, A.; Afanasiev, S.; Aidala, C.; Růžička, Pavel; Tomášek, Lukáš; Vrba, Václav
2009-01-01
Roč. 103, č. 1 (2009), 012003/1-012003/4 ISSN 0031-9007 R&D Projects: GA MŠk LA08015 Institutional research plan: CEZ:AV0Z10100502 Keywords : PHENIX * gluon * proton spin Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 7.328, year: 2009 http://arxiv.org/pdf/0810.0694
Prospects for Measuring $\\Delta$G from Jets at HERA with Polarized Protons and Electrons
De Roeck, A.; Kunne, F.; Maul, M.; Schafer, A.; Wu, C.Y.; Mirkes, E.; Radel, G.
1996-01-01
The measurement of the polarized gluon distribution function Delta G(x) from photon-gluon fusion processes in electron-proton deep inelastic scattering producing two jets has been investigated. The study is based on the MEPJET and PEPSI simulation programs. The size of the expected spin asymmetry and corresponding statistical uncertainties for a possible measurement with polarized beams of electrons and protons at HERA have been estimated. The results show that the asymmetry can reach a few percent, and is not washed out by hadronization and higher order processes.
Prospects for measuring ΔG from jets at HERA with polarized protons and electrons
International Nuclear Information System (INIS)
Roeck, A. de; Feltesse, J.; Kunne, F.; Maul, M.; Schaefer, A.; Wu, C.Y.; Mirkes, E.; Raedel, G.
1996-09-01
The measurement of the polarized gluon distribution function ΔG(x) from photon-gluon fusion processes in electron-proton deep inelastic scattering producing two jets has been investigated. The study is based on the MEPJET and PEPSI simulation programs. The size of the expected spin asymmetry and corresponding statistical uncertainties for a possible measurement with polarized beams of electrons and protons at HERA have been estimated. The results show that the asymmetry can reach a few percent, and is not washed out by hadronization and higher order processes. (orig.)
International Nuclear Information System (INIS)
Duro, Juan Antonio; Padilla, Emilio
2008-01-01
The concept of polarization is linked to the extent that a given distribution leads to the formation of homogeneous groups with opposing interests. This concept, which is basically different from the traditional one of inequality, is related to the level of inherent potential conflict in a distribution. The polarization approach has been widely applied in the analysis of income distribution. The extension of this approach to the analysis of international distribution of CO 2 emissions is quite useful as it gives a potent informative instrument for characterizing the state and evolution of the international distribution of emissions and its possible political consequences in terms of tensions and the probability of achieving agreements. In this paper we analyze the international distribution of per capita CO 2 emissions between 1971 and 2001 through the adaptation of the polarization concept and measures. We find that the most interesting grouped description deriving from the analysis is a two groups' one, which broadly coincide with Annex B and non-Annex B countries of the Kyoto Protocol, which shows the power of polarization analysis for explaining the generation of groups in the real world. The analysis also shows a significant reduction in international polarization in per capita CO 2 emissions between 1971 and 1995, but not much change since 1995, which might indicate that polarized distribution of emission is still one of the important factors leading to difficulties in achieving agreements for reducing global emissions. (author)
Cai, Hong; Long, Christopher M; DeRose, Christopher T; Boynton, Nicholas; Urayama, Junji; Camacho, Ryan; Pomerene, Andrew; Starbuck, Andrew L; Trotter, Douglas C; Davids, Paul S; Lentine, Anthony L
2017-05-29
We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.
Vector optical fields with polarization distributions similar to electric and magnetic field lines.
Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian
2013-07-01
We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.
International Nuclear Information System (INIS)
Uvarov, V.M.; Barashkov, P.D.
1985-01-01
The problem on the effect of the interplanetary magnetic field (IMF) on the distribution of electric fields in polar ionosphere is discussed. The problem on excitation of electric fields is reduced to the solution of the system of continuity equations for the current in three regions-northern polar cap, southern cap and the region outside the caps. It is shown that one succeeds in reproducing the observed types of distributions of electric fields
Probing sea quarks and gluons: the electron-ion collider project
International Nuclear Information System (INIS)
Horn, T.
2014-01-01
A future Electron-Ion Collider (EIC) would be the world's first polarized electron-proton collider, and the world's first e-A collider, and would seek the QCD foundation of nucleons and nuclei in terms of the sea quarks and gluons, matching to these valence quark studies. The EIC will provide a versatile range of kinematics and beam polarization, as well as beam species, to allow for mapping the spin and spatial structure of the quark sea and gluons, to discover the collective effects of gluons in atomic nuclei, and to understand the emergence of hadronic matter from color charge. (authors)
Lunar Polar Cold Traps: Spatial Distribution and Temperatures
Paige, David A.; Siegler, M.; Lawrence, D. J.
2006-09-01
We have developed a ray-tracing and radiosity model that can accurately calculate lunar surface and subsurface temperatures for arbitrary topography. Using available digital elevation models for the lunar north and south polar regions derived from Clementine laser altimeter and image data, as well as ground-based radar data, we have calculated lunar surface and subsurface temperatures at 2 km resolution that include full effects of indirect solar and infrared radiation due to topography. We compare our thermal model results with maps of epithermal neutron flux measured by Lunar Prospector. When we use the ray tracing and thermal model to account for the effects of temperature and topography on the neutron measurements, our results show that the majority of the moon's polar cold traps are not filled with water ice.
Quark jets, gluon jets and the three-gluon vertex
International Nuclear Information System (INIS)
Fodor, Z.
1989-11-01
Using hadronic jets in electron-positron annihilation, we suggest a simple and model-independent method to see the differences between quark and gluon jets. We define and analyse special energy dependent moments of jets and choose those which are the most characteristic to the jet type. The method handles the energy of a jet in an adequate way. We discuss new methods using jet flavor tagging, ordinary flavor tagging of a definite quark jet or discrimination between quark and gluon jets, to test the triple-gluon vertex in electron-positron annihilation. An enriched sample of gluon jets, jets with the smallest energy in four-jet events, as well as a continuous tagging variable are also studied. 21 refs., 6 figs. (Author)
Inclusive gluon production in deep inelastic scattering at high parton density
International Nuclear Information System (INIS)
Kovchegov, Yuri V.; Tuchin, Kirill
2002-01-01
We calculate the cross section of single inclusive gluon production in deep inelastic scattering at very high energies in the saturation regime, where the parton densities inside hadrons and nuclei are large and the evolution of structure functions with energy is nonlinear. The expression we obtain for the inclusive gluon production cross section is generated by this nonlinear evolution. We analyze the rapidity distribution of the produced gluons as well as their transverse momentum spectrum given by the derived expression for the inclusive cross section. We propose an ansatz for the multiplicity distribution of gluons produced in nuclear collisions which includes the effects of nonlinear evolution in both colliding nuclei
Bootstrapping quarks and gluons
Energy Technology Data Exchange (ETDEWEB)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces.
Bootstrapping quarks and gluons
International Nuclear Information System (INIS)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces
Numerical estimates of the evolution of quark and gluon populations inside QCD jets
International Nuclear Information System (INIS)
Garetto, M.
1980-01-01
The system of first order differential equations for the probabilities of producing nsub(g) gluons and nsub(q) quarks in a single gluon or quark jet are solved numerically for a convenient choice of the parameters A, A-tilde, B. Relevant branching ratios as the evolution parameter Y increases are shown. The different behaviour of the distributions in the quark- and in the gluon-jet is discussed. (author)
New shapes of light-cone distributions of the transversely polarized ρ-mesons
International Nuclear Information System (INIS)
Bakulev, A.P.; Mikhajlov, S.V.
2000-01-01
The leading twist light-cone distributions for transversely polarized ρ-, ρ ' - and b 1 mesons are reanalyzed in the framework of QCD sum rules with nonlocal condensates. Using different kinds of sum rules to obtain reliable predictions, we estimate the 2-, 4-, 6- and 8-th moments for transversely polarized ρ- and ρ ' -meson distributions and reestimate tensor couplings f ρ,ρ ' ,b 1 T . It is stressed that the results of standard sum rules also support our estimation of the second moment of the transversely polarized ρ-meson distribution. New models for light-cone distributions are briefly discussed. Our results are compared with those found by Ball and Braun (1996), and the latter is shown to be incomplete
One gluon, two gluon: multigluon production via high energy evolution
International Nuclear Information System (INIS)
Kovner, Alex; Lublinsky, Michael
2006-01-01
We develop an approach for calculating the inclusive multigluon production within the JIMWLK high energy evolution. We give a formal expression of multigluon cross section in terms of a generating functional for arbitrary number of gluons n. In the dipole limit the expression simplifies dramatically. We recover the previously known results for single and double gluon inclusive cross section and generalize those for arbitrary multigluon amplitude in terms of Feynman diagramms of Pomeron - like objects coupled to external rapidity dependent field s(η). We confirm the conclusion that the AGK cutting rules in general are violated in multigluon production. However we present an argument to the effect that for doubly inclusive cross section the AGK diagramms give the leading contribution at high energy, while genuine violation only occurs for triple and higher inclusive gluon production. We discuss some general properties of our expressions and suggest a line of argument to simplify the approach further
Gluon Polarisation Measurements at COMPASS
Silva, Luís
2012-01-01
One of the missing keys in the present understanding of the spin structure of the nucleon is the contribution from the gluons: the so-called gluon polarisation. This quantity can be determined in DIS through the photon-gluon fusion process, in which two analysis methods may be used: (i) identifying open charm events or (ii) selecting events with high $p_{T}$ hadrons. The data used in the present work were collected in the COMPASS experiment, where a 160 GeV/c naturally polarised muon beam, impinging on a polarised nucleon fixed target is used. Preliminary results for the gluon polarisation from high $p_{T}$ and open charm analyses are presented. The gluon polarisation result for high $p_{T}$ hadrons is divided, for the first time, into three statistically independent measurements at LO. The result from open charm analysis is obtained at LO and NLO. In both analyses a new weighted method based on a neural network approach is used.
Relative influences of climate change and human activity on the onshore distribution of polar bears
Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Atwood, Todd C.; Peacock, Elizabeth; Miller, Susanne; Divoky, George J.
2017-01-01
Climate change is altering habitat for many species, leading to shifts in distributions that can increase levels of human-wildlife conflict. To develop effective strategies for minimizing human-wildlife conflict, we must understand the relative influences that climate change and other factors have on wildlife distributions. Polar bears (Ursus maritimus) are increasingly using land during summer and autumn due to sea ice loss, leading to higher incidents of conflict and concerns for human safety. We sought to understand the relative influence of sea ice conditions, onshore habitat characteristics, and human-provisioned food attractants on the distribution and abundance of polar bears while on shore. We also wanted to determine how mitigation measures might reduce human-polar bear conflict associated with an anthropogenic food source. We built a Bayesian hierarchical model based on 14 years of aerial survey data to estimate the weekly number and distribution of polar bears on the coast of northern Alaska in autumn. We then used the model to predict how effective two management options for handling subsistence-harvested whale remains in the community of Kaktovik, Alaska might be. The distribution of bears on shore was most strongly influenced by the presence of whale carcasses and to a lesser extent sea ice and onshore habitat conditions. The numbers of bears on shore were related to sea ice conditions. The two management strategies for handling the whale carcasses reduced the estimated number of bears near Kaktovik by > 75%. By considering multiple factors associated with the onshore distribution and abundance of polar bears we discerned what role human activities played in where bears occur and how successful efforts to manage the whale carcasses might be for reducing human-polar bear conflict.
The PLUTO experiment at DORIS (DESY) and the discovery of the gluon (A recollection)
Energy Technology Data Exchange (ETDEWEB)
Stella, Bruno R. [Rome-3 Univ. (Italy). Dipt. di Fisica; Istituto Nazionale di Fisica Nucleare, Rome (Italy); Meyer, Hans-Juergen
2010-08-15
With the aim of determining the contribution of the PLUTO experiment at the DORIS e{sup +}e{sup -} storage ring to the discovery of the gluon, as members of this former collaboration we have reconsidered all the scientific material produced by PLUTO in 1978 and the first half of 1979. It is clear that the experiment demonstrated the main decay of the Y(9.46 GeV) resonance to be mediated by 3 gluons, by providing evidence for the agreement of this hypothesis with average values and differential distributions of all possible experimental variables and by excluding all other possible alternative models. Moreover PLUTO measured in June 1979 the matrix element of the 3-gluon decay to be quantitatively as expected by QCD (even after hadronization) and, having checked the possibility to correctly trace the gluons' directions, demonstrated the spin 1 nature of the gluon by excluding spin 0 and spin 1/2. The hadronization of the gluon like a quark jet, hypothesized in the 3-gluon jet Monte Carlo simulation, was compatible with the topological data at this energy and was shown to be an approximation at 10% level for the multiplicity ({approx} < p {sub vertical} {sub stroke} {sub vertical} {sub stroke} {sub >}{sup -1}); the right expected gluon fragmentation was needed for the inclusive distributions; this was the first experimental study of (identified) gluon jets. In the following measurements at the PETRA storage ring, these results were confirmed by PLUTO and by three contemporaneous experiments by evidencing at higher energies the gluon radiation (''bremsstrahlung''), the softer one, by jet broadening, and the hard one, by the emission of (now clearly visible) gluon jets by quarks. The gluon's spin 1 particle nature was also confirmed. The PLUTO results on Y decays had been confirmed both by contemporaneous experiments at DORIS (partially) and later (also partially) were confirmed by more sophisticated detectors. (orig.)
The PLUTO experiment at DORIS (DESY) and the discovery of the gluon (A recollection)
International Nuclear Information System (INIS)
Stella, Bruno R.; Meyer, Hans-Juergen
2010-08-01
With the aim of determining the contribution of the PLUTO experiment at the DORIS e + e - storage ring to the discovery of the gluon, as members of this former collaboration we have reconsidered all the scientific material produced by PLUTO in 1978 and the first half of 1979. It is clear that the experiment demonstrated the main decay of the Y(9.46 GeV) resonance to be mediated by 3 gluons, by providing evidence for the agreement of this hypothesis with average values and differential distributions of all possible experimental variables and by excluding all other possible alternative models. Moreover PLUTO measured in June 1979 the matrix element of the 3-gluon decay to be quantitatively as expected by QCD (even after hadronization) and, having checked the possibility to correctly trace the gluons' directions, demonstrated the spin 1 nature of the gluon by excluding spin 0 and spin 1/2. The hadronization of the gluon like a quark jet, hypothesized in the 3-gluon jet Monte Carlo simulation, was compatible with the topological data at this energy and was shown to be an approximation at 10% level for the multiplicity (∼ vertical stroke vertical stroke > -1 ); the right expected gluon fragmentation was needed for the inclusive distributions; this was the first experimental study of (identified) gluon jets. In the following measurements at the PETRA storage ring, these results were confirmed by PLUTO and by three contemporaneous experiments by evidencing at higher energies the gluon radiation (''bremsstrahlung''), the softer one, by jet broadening, and the hard one, by the emission of (now clearly visible) gluon jets by quarks. The gluon's spin 1 particle nature was also confirmed. The PLUTO results on Y decays had been confirmed both by contemporaneous experiments at DORIS (partially) and later (also partially) were confirmed by more sophisticated detectors. (orig.)
A new prescription for soft gluon resummation
International Nuclear Information System (INIS)
Abbate, Riccardo; Forte, Stefano; Ridolfi, Giovanni
2007-01-01
We present a new prescription for the resummation of the divergent series of perturbative corrections, due to soft gluon emission, to hard processes near threshold in perturbative QCD (threshold resummation). This prescription is based on Borel resummation, and contrary to the commonly used minimal prescription, it does not introduce a dependence of resummed physical observables on the kinematically unaccessible x→0 region of parton distributions. We compare results for resummed deep-inelastic scattering obtained using the Borel prescription and the minimal prescription and exploit the comparison to discuss the ambiguities related to the resummation procedure
Uvarov, V. M.; Barashkov, P. D.
1985-08-01
Heppner (1972), in an analysis of satellite data, observed 12 types of electric-field distributions in the polar ionosphere along the morning-evening meridian. In the present paper it is shown that these distribution types can be described by the analytical model of Uvarov and Barashkov (1984). In this model the excitation of the electric fields is investigated by solving the set of continuity equations for current in three regions (the north and south polar caps and a region outside the caps) with allowance for the magnetic conjugacy of the ionosphere in the two hemispheres.
The gluon contribution to polarised nucleon structure functions
International Nuclear Information System (INIS)
Ross, G.G.; Roberts, R.G.
1990-08-01
As with all parton distributions in quantum chromodynamics (QCD) the separation of polarised nucleon structure functions into gluon and quark contributions must be specified. We consider a definition of the gluon contribution to polarised nucleon structure functions based on exclusive processes which is explicitly gauge invariant, has no regularisation ambiguities, is insensitive to infrared singularities and can be related to other polarised scattering processes. We discuss the relationship of this gluon definition to others that have recently been used and to the estimates that have been made of the gluon contribution using current algebra and other methods. A quantitative analysis of the structure function g 1 (x,Q 2 ) for polarised deep inelastic scattering is carried out, with the aim of examining the importance of the gluon contribution. Using the positivity of parton distributions the magnitude of Δg(x,Q 2 ) is constrained by a realistic estimate of the unpolarised glue. With the appropriate choice of the hard scattering cross-section, Δσ γg , we find that even with a maximally polarised glue (for x > 0.1), some polarised strange quark contribution is still needed by the data of the EMC. (author)
Double-spin asymmetry of J/ψ production in polarized pp-collisions at HERA-N-vector polarized
International Nuclear Information System (INIS)
Teryaev, O.; Tkabladze, A.
1996-01-01
We calculated the color-octet contribution to the double spin asymmetry of J/ψ hadroproduction with nonzero transverse momenta at fixed target energies √ s ≅ 40 GeV. It is shown that color-octet contribution is dominant in the asymmetries. The expected asymmetries and statistical errors in a future option of HERA with longitudinally polarized protons at √ s = 39 GeV (HERA-N polarized) should allow one to distinguish between different parametrizations for polarized gluon distribution in proton
CERN. Geneva
2017-01-01
Emissions of soft gluons from energetic particles play an important role in collider processes. While the basic physics of soft emissions is simple, it gives rise to a variety of interesting and intricate phenomena (non-global logs, Glauber phases, super-leading logs, factorization breaking). After an introduction, I will review progress in resummation methods such as Soft-Collinear Effective Theory driven by a better understanding of soft emissions. I will also show some new results for computations of soft-gluon effects in gap-between-jets and isolation-cone cross sections.
The unconfined quarks and gluons
International Nuclear Information System (INIS)
Abdus Salam
1977-01-01
The consequences of the lepton-hadron gauge unification hypothesis with unconfined quarks and gluons being the hall-mark are discussed. Quark and gluon decays into leptons are shown to provide a new source of multileptonic production in NN, νN and μN collisions. A theorem is stated and proved which highlights the differences between the dynamics of gauge versus non-gauge 1 - particles. Empirical manifestations of gauge coloured mesons are discussed. The question of exact confinement or not is concluded to be in the end an empirical one and must be settled in the laboratory
LaRue, Michelle A.; Stapleton, Seth P.; Porter, Claire; Atkinson, Stephen N.; Atwood, Todd C.; Dyck, Markus; Lecomte, Nicolas
2015-01-01
High-resolution satellite imagery is a promising tool for providing coarse information about polar species abundance and distribution, but current applications are limited. With polar bears (Ursus maritimus), the technique has only proven effective on landscapes with little topographic relief that are devoid of snow and ice, and time-consuming manual review of imagery is required to identify bears. Here, we evaluated mechanisms to further develop methods for satellite imagery by examining data from Rowley Island, Canada. We attempted to automate and expedite detection via a supervised spectral classification and image differencing to expedite image review. We also assessed what proportion of a region should be sampled to obtain reliable estimates of density and abundance. Although the spectral signature of polar bears differed from nontarget objects, these differences were insufficient to yield useful results via a supervised classification process. Conversely, automated image differencing—or subtracting one image from another—correctly identified nearly 90% of polar bear locations. This technique, however, also yielded false positives, suggesting that manual review will still be required to confirm polar bear locations. On Rowley Island, bear distribution approximated a Poisson distribution across a range of plot sizes, and resampling suggests that sampling >50% of the site facilitates reliable estimation of density (CV in certain areas, but large-scale applications remain limited because of the challenges in automation and the limited environments in which the method can be effectively applied. Improvements in resolution may expand opportunities for its future uses.
LaRue, Michelle A.; Stapleton, Seth P.; Porter, Claire; Atkinson, Stephen N.; Atwood, Todd C.; Dyck, Markus; Lecomte, Nicolas
2015-01-01
High-resolution satellite imagery is a promising tool for providing coarse information about polar species abundance and distribution, but current applications are limited. With polar bears (Ursus maritimus), the technique has only proven effective on landscapes with little topographic relief that are devoid of snow and ice, and time-consuming manual review of imagery is required to identify bears. Here, we evaluated mechanisms to further develop methods for satellite imagery by examining data from Rowley Island, Canada. We attempted to automate and expedite detection via a supervised spectral classification and image differencing to expedite image review. We also assessed what proportion of a region should be sampled to obtain reliable estimates of density and abundance. Although the spectral signature of polar bears differed from nontarget objects, these differences were insufficient to yield useful results via a supervised classification process. Conversely, automated image differencing—or subtracting one image from another—correctly identified nearly 90% of polar bear locations. This technique, however, also yielded false positives, suggesting that manual review will still be required to confirm polar bear locations. On Rowley Island, bear distribution approximated a Poisson distribution across a range of plot sizes, and resampling suggests that sampling >50% of the site facilitates reliable estimation of density (CV large-scale applications remain limited because of the challenges in automation and the limited environments in which the method can be effectively applied. Improvements in resolution may expand opportunities for its future uses.
A solution of the DGLAP equation for gluon at low x
Indian Academy of Sciences (India)
Using (43) we will estimate the logarithmic slope of the structure function from the proposed gluon distribution at several points of expansion and compare with data [19] at. Q2 =20 GeV2 where the data on the slope are available. 3. Results and discussion. In the present paper, we have obtained a new description of gluon ...
Quark and gluon fragmentation in high energy e+e- annihilation
International Nuclear Information System (INIS)
Saxon, D.H.
1986-07-01
The paper on quark and gluon fragmentation in high energy e + e - annihilation is based on lectures given at the International School of High Energy Physics, Yugoslavia, 1986. Fragmentation Models, charged particle multiplicity, Bose-Einstein correlations, single particle inclusive distributions, hadrons in jets, leading particle effects, baryon production, comparison of quark and gluon jets, and the string effect, are all discussed. (UK)
Development of a distributed polarization-OTDR to measure two vibrations with the same frequency
Pan, Yun; Wang, Feng; Wang, Xiangchuan; Zhang, Mingjiang; Zhou, Ling; Sun, Zhenqing; Zhang, Xuping
2015-08-01
A polarization optical time-domain reflectometer (POTDR) can distributedly measure the vibration of fiber by detecting the vibration induced polarization variation only with a polarization analyzer. It has great potential in the monitoring of the border intrusion, structural healthy, anti-stealing of pipeline and so on, because of its simple configuration, fast response speed and distributed measuring ability. However, it is difficult to distinguish two vibrations with the same frequency for POTDR because the signal induced by the first vibration would bury the other vibration induced signal. This paper proposes a simple method to resolve this problem in POTDR by analyzing the phase of the vibration induced signal. The effectiveness of this method in distinguishing two vibrations with the same frequency for POTDR is proved by simulation.
Polarized parton distributions from charged-current deep-inelastic scattering
International Nuclear Information System (INIS)
Ridolfi, G
2003-01-01
We investigate the capabilities of a neutrino factory in the determination of polarized parton distributions from charged-current deep-inelastic scattering experiments, with special attention to the accuracy of this kind of measurements. We show that a neutrino factory would allow to distinguish between different theoretical scenarios for the proton spin structure
Fragmentation of quarks and gluons
International Nuclear Information System (INIS)
Soeding, P.
1983-10-01
The author presents a review about quark and gluon jets. He describes the particle contents of the different types of jets. Finally he considers the hadronization mechanism with special regards to three-jet events in e + e - annihilation and hadronization in nuclear matter. (HSI)
1995-01-01
This is a sequel to the review volume Quark-Gluon Plasma. There are 13 articles contributed by leading investigators in the field, covering a wide range of topics about the theoretical approach to the subject. These contributions are timely reviews of nearly all the actively pursued problems, written in a pedagogical style suitable for beginners as well as experienced researchers.
Vogt, Ramona
1998-01-01
Aspects of quark-gluon plasma signatures that can be measured by CMS are discussed. First the initial conditions of the system from minijet production are introduced, including shadowing effects. Color screening of the Upsilon family is then presented, followed by energy loss effects on charm and bottom hadrons, high Pt jets and global observables.
International Nuclear Information System (INIS)
Uvarov, V.M.; Barashkov, P.D.
1989-01-01
All types of distributions, known due to the experiment, for Ee-m electric field evening-morning component along morning-evening meridian are reproduced and corresponding types of convection in polar ionosphere are calculated on the basis of model of continuous distribution of E large-scale electric fields. Two-, three- and four-whirl types of convection are realized depending on conditions in interplanetary medium
Predicting 21st-century polar bear habitat distribution from global climate models
Durner, George M.; Douglas, David C.; Nielson, R.M.; Amstrup, Steven C.; McDonald, T.L.; Stirling, I.; Mauritzen, Mette; Born, E.W.; Wiig, O.; Deweaver, E.; Serreze, Mark C.; Belikov, Stanislav; Holland, M.M.; Maslanik, J.; Aars, Jon; Bailey, D.A.; Derocher, A.E.
2009-01-01
Projections of polar bear (Ursus maritimus) sea ice habitat distribution in the polar basin during the 21st century were developed to understand the consequences of anticipated sea ice reductions on polar bear populations. We used location data from satellitecollared polar bears and environmental data (e.g., bathymetry, distance to coastlines, and sea ice) collected from 1985 to 1995 to build resource selection functions (RSFs). RSFs described habitats that polar bears preferred in summer, autumn, winter, and spring. When applied to independent data from 1996 to 2006, the RSFs consistently identified habitats most frequently used by polar bears. We applied the RSFs to monthly maps of 21st-century sea ice concentration projected by 10 general circulation models (GCMs) used in the Intergovernmental Panel of Climate Change Fourth Assessment Report, under the A1B greenhouse gas forcing scenario. Despite variation in their projections, all GCMs indicated habitat losses in the polar basin during the 21st century. Losses in the highest-valued RSF habitat (optimal habitat) were greatest in the southern seas of the polar basin, especially the Chukchi and Barents seas, and least along the Arctic Ocean shores of Banks Island to northern Greenland. Mean loss of optimal polar bear habitat was greatest during summer; from an observed 1.0 million km2 in 1985-1995 (baseline) to a projected multi-model mean of 0.32 million km2 in 2090-2099 (-68% change). Projected winter losses of polar bear habitat were less: from 1.7 million km2 in 1985-1995 to 1.4 million km2 in 2090-2099 (-17% change). Habitat losses based on GCM multi-model means may be conservative; simulated rates of habitat loss during 1985-2006 from many GCMs were less than the actual observed rates of loss. Although a reduction in the total amount of optimal habitat will likely reduce polar bear populations, exact relationships between habitat losses and population demographics remain unknown. Density and energetic
Soft Probes of the Quark-Gluon Plasma in ATLAS
Wozniak, K W; The ATLAS collaboration
2014-01-01
Measurements of low-$p_{_{\\rm T}}$ ($<$ 5 GeV) particles in Pb+Pb collisions at the LHC provide valuable insight in the production and evolution of the quark-gluon plasma. In particular, measurements of the elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS makes it possible to measure flow event-by-event and to determine the correlations between different event planes and different flow harmonics.
The distribution of polarized radio sources >15 μJy IN GOODS-N
International Nuclear Information System (INIS)
Rudnick, L.; Owen, F. N.
2014-01-01
We present deep Very Large Array observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.''6 and 10''. At 1.''6, we find that the peak flux cumulative number count distribution is N(> p) ∼ 45*(p/30 μJy) –0.6 per square degree above a detection threshold of 14.5 μJy. This represents a break from the steeper slopes at higher flux densities, resulting in fewer sources predicted for future surveys with the Square Kilometer Array and its precursors. It provides a significant challenge for using background rotation measures (RMs) to study clusters of galaxies or individual galaxies. Most of the polarized sources are well above our detection limit, and they are also radio galaxies that are well-resolved even at 10'', with redshifts from ∼0.2-1.9. We determined a total polarized flux for each source by integrating the 10'' polarized intensity maps, as will be done by upcoming surveys such as POSSUM. These total polarized fluxes are a factor of two higher, on average, than the peak polarized flux at 1.''6; this would increase the number counts by ∼50% at a fixed flux level. The detected sources have RMs with a characteristic rms scatter of ∼11 rad m –2 around the local Galactic value, after eliminating likely outliers. The median fractional polarization from all total intensity sources does not continue the trend of increasing at lower flux densities, as seen for stronger sources. The changes in the polarization characteristics seen at these low fluxes likely represent the increasing dominance of star-forming galaxies.
Quark and gluon tagging in dijet mass resonance search
Kellermann, Edgar
2013-01-01
Several models beyond the Standard Model predict new phenomena in particle physics, which would appear as resonant signals in dijet mass distributions. An example for such a resonance is the excited quark q, which is a consequence of Compositeness Models postulating that quarks and leptons are build by more fundamental particles. The main signature of an excited quark would be a dijet event, originated from the radiation of a gluon from the original excited quark when going back to its non-excited state, leading to a quark and a gluon in the final state (with a branching ratio of 83%) . Other examples are the heavy vector bosonsW0 decaying to two quarks and colour octet scalar S8 decaying to two gluons.
Study of gluon condensates using the Bogolyubov transformation
International Nuclear Information System (INIS)
Iracane, Daniel
1985-01-01
We describe the ground state of non-perturbative QCD as a gluon condensate. In the framework of the Coulomb gauge Hamiltonian, we introduce an effective interaction between infrared gluons by removing high-momentum gluons. The Bogoliubov transformation provides us with our variational space. The minimisation over this Fock subspace leads to a non-perturbative vacuum and its excitations. The minimum functional space for a boson dynamic is a distribution set. We find two kinds of condensation. The first one occurs only for zero-momentum states and looks like the Bose Condensation. In the second one, the quasiparticle spectrum shows a finite gap and the vacuum is a superconducting state. We give constraints on the interaction so that the superconducting phase is more bounded than the Bose one. (author) [fr
The quark-gluon model for particle production processes
International Nuclear Information System (INIS)
Volkovitskij, P.E.
1983-01-01
The quark-gluon model for hadronization of strings produced in soft and hard processes is suggested. The model is based on the distribution functions of valence quarks in hadrons which have correct Regge behaviour. The simplest case is discussed in which only the longitudinal degrees of freedom are taken into account
Li, Xiaobo; Hu, Haofeng; Liu, Tiegen; Huang, Bingjing; Song, Zhanjie
2016-04-04
We consider the degree of linear polarization (DOLP) polarimetry system, which performs two intensity measurements at orthogonal polarization states to estimate DOLP. We show that if the total integration time of intensity measurements is fixed, the variance of the DOLP estimator depends on the distribution of integration time for two intensity measurements. Therefore, by optimizing the distribution of integration time, the variance of the DOLP estimator can be decreased. In this paper, we obtain the closed-form solution of the optimal distribution of integration time in an approximate way by employing Delta method and Lagrange multiplier method. According to the theoretical analyses and real-world experiments, it is shown that the variance of the DOLP estimator can be decreased for any value of DOLP. The method proposed in this paper can effectively decrease the measurement variance and thus statistically improve the measurement accuracy of the polarimetry system.
Gluon mass generation without seagull divergences
International Nuclear Information System (INIS)
Aguilar, Arlene C.; Papavassiliou, Joannis
2010-01-01
Dynamical gluon mass generation has been traditionally plagued with seagull divergences, and all regularization procedures proposed over the years yield finite but scheme-dependent gluon masses. In this work we show how such divergences can be eliminated completely by virtue of a characteristic identity, valid in dimensional regularization. The ability to trigger the aforementioned identity hinges crucially on the particular Ansatz employed for the three-gluon vertex entering into the Schwinger-Dyson equation governing the gluon propagator. The use of the appropriate three-gluon vertex brings about an additional advantage: one obtains two separate (but coupled) integral equations, one for the effective charge and one for the gluon mass. This system of integral equations has a unique solution, which unambiguously determines these two quantities. Most notably, the effective charge freezes in the infrared, and the gluon mass displays power-law running in the ultraviolet, in agreement with earlier considerations.
NUCLEON POLARIZATION IN 3-BODY MODELS OF POLARIZED LI-6
SCHELLINGERHOUT, NW; KOK, LP; COON, SA; ADAM, RM
1993-01-01
Just as He-3 --> can be approximately characterized as a polarized neutron target, polarized Li-6D has been advocated as a good isoscalar nuclear target for the extraction of the polarized gluon content of the nucleon. The original argument rests upon a presumed ''alpha + deuteron'' picture of Li-6,
International Nuclear Information System (INIS)
Iwamae, A; Sato, T; Horimoto, Y; Inoue, K; Fujimoto, T; Uchida, M; Maekawa, T
2005-01-01
A helium plasma is produced by electron-cyclotron resonance heating in a cusp-configuration magnetic field. Several neutral helium lines are found polarized in the direction perpendicular to the magnetic field; the maximum polarization degree exceeds 10%. The polarization degree and intensity of the emission lines yield, respectively, the alignment and population of the upper levels. The population-alignment collisional-radiative model is developed, and the experimental result is interpreted in terms of an anisotropic electron velocity distribution; it is of a Saturn-type with the central thermal component of 14 eV and the 'ring' component displaced by 9.2 eV from the central component. The relative number of 'ring' electrons is 40%. (letter to the editor)
Tortosa, Elena; Hoogenraad, Casper C
2018-02-01
In neurons, polarized cargo distribution occurs mainly between the soma and axonal and dendritic compartments, and requires coordinated regulation of cytoskeletal remodeling and membrane trafficking. The Golgi complex plays a critical role during neuronal polarization and secretory trafficking has been shown to differentially transport proteins to both axons and dendrites. Besides the Golgi protein sorting, recent data revealed that palmitoylation cycles are an efficient mechanism to localize cytoplasmic, non-transmembrane proteins to particular neuronal compartments, such as the newly formed axon. Palmitoylation allows substrate proteins to bind to and ride with Golgi-derived secretory vesicles to all neuronal compartments. By allowing cytoplasmic proteins to 'hitchhike' on transport carriers in a non-polarized fashion, compartmentalized depalmitoylation may act as a selective retention mechanism. Copyright © 2018 Elsevier Ltd. All rights reserved.
Chimera distribution amplitudes for the pion and the longitudinally polarized ρ-meson
Energy Technology Data Exchange (ETDEWEB)
Stefanis, N.G., E-mail: stefanis@tp2.ruhr-uni-bochum.de [Institut für Theoretische Physik II, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Pimikov, A.V., E-mail: pimikov@theor.jinr.ru [Bogoliubov Laboratory of Theoretical Physics, JINR, 141980 Dubna (Russian Federation); Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China)
2016-01-15
Using QCD sum rules with nonlocal condensates, we show that the distribution amplitude of the longitudinally polarized ρ-meson may have a shorttailed platykurtic profile in close analogy to our recently proposed platykurtic distribution amplitude for the pion. Such a chimera distribution de facto amalgamates the broad unimodal profile of the distribution amplitude, obtained with a Dyson–Schwinger equations-based computational scheme, with the suppressed tails characterizing the bimodal distribution amplitudes derived from QCD sum rules with nonlocal condensates. We argue that pattern formation, emerging from the collective synchronization of coupled oscillators, can provide a single theoretical scaffolding to study unimodal and bimodal distribution amplitudes of light mesons without recourse to particular computational schemes and the reasons for them.
Zhang, Yu; Li, Fei; Zhang, Shengkai; Zhu, Tingting
2017-04-01
Synthetic Aperture Radar (SAR) is significantly important for polar remote sensing since it can provide continuous observations in all days and all weather. SAR can be used for extracting the surface roughness information characterized by the variance of dielectric properties and different polarization channels, which make it possible to observe different ice types and surface structure for deformation analysis. In November, 2016, Chinese National Antarctic Research Expedition (CHINARE) 33rd cruise has set sails in sea ice zone in Antarctic. Accurate leads spatial distribution in sea ice zone for routine planning of ship navigation is essential. In this study, the semantic relationship between leads and sea ice categories has been described by the Conditional Random Fields (CRF) model, and leads characteristics have been modeled by statistical distributions in SAR imagery. In the proposed algorithm, a mixture statistical distribution based CRF is developed by considering the contexture information and the statistical characteristics of sea ice for improving leads detection in Sentinel-1A dual polarization SAR imagery. The unary potential and pairwise potential in CRF model is constructed by integrating the posteriori probability estimated from statistical distributions. For mixture statistical distribution parameter estimation, Method of Logarithmic Cumulants (MoLC) is exploited for single statistical distribution parameters estimation. The iteration based Expectation Maximal (EM) algorithm is investigated to calculate the parameters in mixture statistical distribution based CRF model. In the posteriori probability inference, graph-cut energy minimization method is adopted in the initial leads detection. The post-processing procedures including aspect ratio constrain and spatial smoothing approaches are utilized to improve the visual result. The proposed method is validated on Sentinel-1A SAR C-band Extra Wide Swath (EW) Ground Range Detected (GRD) imagery with a
International Nuclear Information System (INIS)
Usubov, Z.U.
1996-01-01
The paper considers a possibility to investigate the associated production of J/ψ+γ with high transverse momentum in polarized pp-interactions at Relativistic Heavy Ion Collider energies. The differential cross sections and their asymmetries are evaluated. The accuracy which can be achieved in the gluon distribution function measurement is discussed. 16 refs., 4 figs., 1 tab
Shadowing of gluons in perturbative QCD: A comparison of different models
International Nuclear Information System (INIS)
Jalilian-Marian, Jamal; Wang, Xin-Nian
2001-01-01
We investigate the different perturbative QCD-based models for nuclear shadowing of gluons. We show that, in the kinematic region appropriate to the BNL relativistic heavy ion collider experiment, all models give similar estimates for the magnitude of gluon shadowing. At scales relevant to CERN large hadron collider (LHC), there is a sizable difference between the predictions of the different models. However, the uncertainties in gluon shadowing coming from a different parametrization of the gluon distribution in nucleons, are larger than those due to different perturbative QCD models of gluon shadowing. We also investigate the effect of initial nonperturbative shadowing on the magnitude of perturbative shadowing and show that the magnitudes of perturbative and nonperturbative shadowing are comparable at RHIC but perturbative shadowing dominates over nonperturbative shadowing at smaller values of x reached at LHC
Forward gluon production in hadron-hadron scattering with Pomeron loops
International Nuclear Information System (INIS)
Iancu, E.
2006-01-01
We discuss new physical phenomena expected in particle production in hadron-hadron collisions at high energy, as a consequence of Pomerons loop effects in the evolution equations for the Color Glass Condensate. We focus on gluon production in asymmetric, 'dilute-dense', collisions: a dilute projectile scatters off a dense hadronic target, whose gluon distribution is highly evolved. This situation is representative for particle production in proton-proton collisions at forward rapidities (say, at LHC) and admits a dipole factorization similar to that of deep inelastic scattering (DIS). We show that at sufficiently large forward rapidities, where the Pomerons loop effects become important in the evolution of the target wavefunction, gluon production is dominated by 'black spots' (saturated gluon configurations) up to very large values of the transverse momentum, well above the average saturation momentum in the target. In this regime, the produced gluon spectrum exhibits diffusive scaling, so like DIS at sufficiently high energy. (authors)
A New Approach for High Pressure Pixel Polar Distribution on Off-line Signature Verification
Directory of Open Access Journals (Sweden)
Jesús F. Vargas
2010-06-01
Full Text Available Features representing information of High Pressure Points froma static image of a handwritten signature are analyzed for an offline verification system. From grayscale images, a new approach for High Pressure threshold estimation is proposed. Two images, one containingthe High Pressure Points extracted and other with a binary version ofthe original signature, are transformed to polar coordinates where a pixel density ratio between them is calculated. Polar space had been divided into angular and radial segments, which permit a local analysis of the high pressure distribution. Finally two vectors containing the density distribution ratio are calculated for nearest and farthest points from geometric center of the original signature image. Experiments were carried out using a database containing signature from 160 individual. The robustness of the analyzed system for simple forgeries is tested out with Support Vector Machines models. For the sake of completeness, a comparison of the results obtained by the proposed approach with similar works published is presented.
International Nuclear Information System (INIS)
Suniaev, R.A.; Titarchuk, L.G.
1984-01-01
Analytical consideration is given to the comptonization of photons and its effects on the radiation emitted from accretion disks of compact X-ray sources, such as black holes and neutron stars. Attention is given to the photon distribution during escape from the disk, the angular distribution of hard radiation from the disk, the polarization of hard radiation and the electron temperature distribution over the optical depth. It is shown that the hard radiation spectrum is independent of the low-frequency photon source distribution. The angular distribution and polarization of the outgoing X-rays are a function of the optical depth. A Thomson approximation is used to estimate the angular distribution of the hard radiation and the polarization over the disk. The polarization results are compared with OSO-8 satellite data for Cyg X-1 and show good agreement at several energy levels. 17 references
Two theoretical treatments of the quark-gluon plasma
International Nuclear Information System (INIS)
Carrington, M.E.
1989-01-01
The study of the quark-gluon plasma is of direct relevance to questions about the confinement properties of QCD and the validity of the standard theory of QCD in a different physical regime. Part 1 of this work contains a brief discussion of the theoretical and numerical evidence for the existence of the quark-gluon plasma. In the next two sections, two different approaches are discussed. In Part 2, the problem is presented in the general framework of kinetic theory. A definition of the Wigner distribution operator is introduced for quarks and a set of kinetic equations are derived for the momentum moments of this operator. A Wigner distribution operator is defined for gluons and the momentum of this operator are calculated and related to physical quantities. In Part 3, a calculation of linear response functions in a hot gluon plasma is presented. Problems related to gauge invariance and to the definition of a thermal ensemble in the presence of unphysical degrees of freedom are discussed. Results in different gauges and with different ensembles are compared, and the implications of the results for plasma oscillations are discussed
International Nuclear Information System (INIS)
Matsuoka, Daisuke; Nakasako, Masayoshi
2013-01-01
Highlights: ► Empirical distribution functions of water molecules in protein hydration are made. ► The functions measure how hydrogen-bond geometry in hydration deviate from ideal. ► The functions assess experimentally identified hydration structures of protein. - Abstract: To quantitatively characterize hydrogen-bond geometry in local hydration structures of proteins, we constructed a set of empirical hydration distribution functions (EHDFs) around polar protein atoms in the main and side chains of 11 types of hydrophilic amino acids (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 113 (2009) 11274). The functions are the ensemble average of possible hydration patterns around the polar atoms, and describe the anisotropic deviations from ideal hydrogen bond geometry. In addition, we defined probability distribution function of hydration water molecules (PDFH) over the hydrophilic surface of a protein as the sum of EHDFs of solvent accessible polar protein atoms. The functions envelop most of hydration sites identified in crystal structures of proteins (D. Matsuoka, M. Nakasako, Journal of Physical Chemistry B 114 (2010) 4652). Here we propose the application of EHDFs and PDFHs for assessing crystallographically identified hydration structures of proteins. First, hydration water molecules are classified with respect to the geometry in hydrogen bonds in referring EHDFs. Difference Fourier electron density map weighted by PDFH of protein is proposed to identify easily density peaks as candidates of hydration water molecules. A computer program implementing those ideas was developed and used for assessing hydration structures of proteins
Symmetry breaking effect on determination of polarized and unpolarized parton distributions
International Nuclear Information System (INIS)
Arbabifar, F.; Khorramian, Ali N.; Khanpour, H.; Atashbar Tehrani, S.
2013-01-01
We perform a new extraction for unpolarized and polarized parton distribution functions considering a flavor decompositions for sea quarks and applying very recent deep inelastic scattering (DIS) and semi inclusive deep inelastic scattering (SIDIS) data in the fixed flavor number scheme (FFNS) framework. In the new symmetry breaking scenario the light quark and antiquark densities are extracted separately and new parametrization forms are determined for them. The heavy flavors contribution, including charm and bottom quarks, are also taken to be account for unpolarized distributions
Gluon exchange in elastic hadron scattering
International Nuclear Information System (INIS)
Jenkovszky, L.L.; Paccanoni, F.; Chikovani, Z.E.
1991-01-01
It is generally accepted that the Pomeron, which determines the long-range component of the strong interaction, corresponds to exchange of gluons with the corresponding quantum numbers (the minimum number of such gluons is two). The C-odd partner of the Pomeron, the odderon, corresponds to exchange of an odd number of gluons (three or more). By means of a model of the nonperturbative gluon propagator, restrictions are obtained on the parameters of two-gluon (Pomeron) and three-gluon (odderon) exchange in hadron scattering. In the framework of this model an interpretation is proposed for the various asymptotic regimes in the behavior of the total cross section and of the differential cross section of elastic scattering at high energies
Energy Technology Data Exchange (ETDEWEB)
Zhang, Shukui [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Poelker, Matthew [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Stutzman, Marcy L. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Chen, Yiqiao [SVT Associates, Inc., Eden Prairie, MN (United States); Moy, Aaron [SVT Associates, Inc., Eden Prairie, MN (United States)
2015-09-01
Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.
Garcia, Rolando R.; Boville, Byron A.
1994-01-01
According to the 'downward control' principle, the extratropical mean vertical velocity on a given pressure level is approximately proportional to the meridional gradient of the vertically integrated zonal force per unit mass exerted by waves above that level. In this paper, a simple numerical model that includes parameterizations of both planetary and gravity wave breaking is used to explore the influence of gravity wave breaking in the mesosphere on the mean meridional circulation and temperature distribution at lower levels in the polar winter stratosphere. The results of these calculations suggest that gravity wave drag in the mesosphere can affect the state of the polar winter stratosphere down to altitudes below 30 km. The effect is most important when planetary wave driving is relatively weak: that is, during southern winter and in early northern winter. In southern winter, downwelling weakens by a factor of 2 near the stratospause and by 20% at 30 km when gravity wave drag is not included in the calculations. As a consequence, temperatures decrease considerably throughout the polar winter stratosphere (over 20 K above 40 km and as much as 8 K at 30 km, where the effect is enhanced by the long radiative relaxation timescale). The polar winter states obtained when gravity wave drag is omitted in this simple model resemble the results of simulations with some general circulation models and suggest that some of the shortcomings of the latter may be due to a deficit in mesospheric momentum deposition by small-scale gravity waves.
Directory of Open Access Journals (Sweden)
H. Laakso
2002-11-01
Full Text Available Using spacecraft potential measurements of the Polar electric field experiment, we investigate electron density variations of key plasma regions within the magnetosphere, including the polar cap, cusp, trough, plasmapause, and auroral zone. The statistical results were presented in the first part of this study, and the present paper reports detailed structures revealed by individual satellite passes. The high-altitude (> 3 RE polar cap is generally one of the most tenuous regions in the magnetosphere, but surprisingly, the polar cap boundary does not appear as a steep density decline. At low altitudes (1 RE in summer, the polar densities are very high, several 100 cm-3 , and interestingly, the density peaks at the central polar cap. On the noonside of the polar cap, the cusp appears as a dense, 1–3° wide region. A typical cusp density above 4 RE distance is between several 10 cm-3 and a few 100 cm-3 . On some occasions the cusp is crossed multiple times in a single pass, simultaneously with the occurrence of IMF excursions, as the cusp can instantly shift its position under varying solar wind conditions, similar to the magnetopause. On the nightside, the auroral zone is not always detected as a simple density cavity. Cavities are observed but their locations, strengths, and sizes vary. Also, the electric field perturbations do not necessarily overlap with the cavities: there are cavities with no field disturbances, as well as electric field disturbances observed with no clear cavitation. In the inner magnetosphere, the density distributions clearly show that the plasmapause and trough densities are well correlated with geomagnetic activity. Data from individual orbits near noon and midnight demonstrate that at the beginning of geomagnetic disturbances, the retreat speed of the plasmapause can be one L-shell per hour, while during quiet intervals the plasmapause can expand anti-earthward at the same speed. For the trough region, it is found
2016-06-02
Retrieval of droplet-size density distribution from multiple-field-of-view cross-polarized lidar signals: theory and experimental validation...Gilles Roy, Luc Bissonnette, Christian Bastille, and Gilles Vallee Multiple-field-of-view (MFOV) secondary-polarization lidar signals are used to...use secondary polarization. A mathematical relation among the PSD, the lidar fields of view, the scattering angles, and the angular depolarization
High energy evolution of soft gluon cascades
International Nuclear Information System (INIS)
Shuvaev, A.; Wallon, S.
2006-01-01
In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)
High energy evolution of soft gluon cascades
Energy Technology Data Exchange (ETDEWEB)
Shuvaev, A. [St. Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg district (Russian Federation); Wallon, S. [Universite Paris XI, Laboratoire de Physique Theorique, Orsay Cedex (France)
2006-04-15
In this paper we derive an evolution equation for the gluon density in soft gluon cascades emitted from any colored source, in the leading logarithmic approximation of perturbative QCD. We show that this equation has the same form as the BFKL equation in the forward case. An explicit expression for the total cascade wavefunction involving an arbitrary number of soft gluons is obtained. Renormalization of the colored source wavefunction turns out to be responsible for the reggeization of the source. (orig.)
Quark ACM with topologically generated gluon mass
Choudhury, Ishita Dutta; Lahiri, Amitabha
2016-03-01
We investigate the effect of a small, gauge-invariant mass of the gluon on the anomalous chromomagnetic moment (ACM) of quarks by perturbative calculations at one-loop level. The mass of the gluon is taken to have been generated via a topological mass generation mechanism, in which the gluon acquires a mass through its interaction with an antisymmetric tensor field Bμν. For a small gluon mass ( ACM at momentum transfer q2 = -M Z2. We compare those with the ACM calculated for the gluon mass arising from a Proca mass term. We find that the ACM of up, down, strange and charm quarks vary significantly with the gluon mass, while the ACM of top and bottom quarks show negligible gluon mass dependence. The mechanism of gluon mass generation is most important for the strange quarks ACM, but not so much for the other quarks. We also show the results at q2 = -m t2. We find that the dependence on gluon mass at q2 = -m t2 is much less than at q2 = -M Z2 for all quarks.
Tejos, R.; Sauer, M.; Vanneste, S.; Palacios-Gomez, M.; Li, H.; Heilmann, M.; van Wijk, R.; Vermeer, J.E.M.; Heilmann, I.; Munnik, T.; Friml, J.
2014-01-01
Cell polarity manifested by asymmetric distribution of cargoes, such as receptors and transporters, within the plasma membrane (PM) is crucial for essential functions in multicellular organisms. In plants, cell polarity (re)establishment is intimately linked to patterning processes. Despite the
Gluon radiation in diffractive electroproduction
International Nuclear Information System (INIS)
Buchmueller, W.; McDermott, M.F.; Hebecker, A.
1996-07-01
Order α s -correlations to the diffractive structure functions F L D and F 2 D at large Q 2 and small x are evaluated in the semiclassical approach, where the initial proton is treated as a classical colour field. The diffractive final state contains a fast gluon in addition to a quark-antiquark pair. Two of these partons may have large transverse momentum. Our calculations lead to an intuitive picture of deep-inelastic diffractive processes which is very similar to Bjorken's aligned-jet model. Both diffractive structure functions contain leading twist contributions from high-p perpendicular to jets. (orig.)
Distribution of irregularities in the northern polar region determined from Hilat observations
International Nuclear Information System (INIS)
Macdougall, J.W.
1990-01-01
Three years' observations of the Hilat satellite from stations Sondre, Churchill, and Tromso have been used to study the distributions of scintillations over the northern polar region. Two regions showed enhancement. Region (1) was an enhancement of phase scintillations when the line of sight to the satellite lay along an L shell and the observing station was under the auroral oval. Region (2) is revealed most clearly by amplitude scintillations and maximizes in an annular region several degrees poleward of the auroral oval. Region (1) is most likely associated with large-scale 'blobs' of ionization in the auroral zone; region (2) appears to be due to km-scale irregularities generated in the polar cap. 17 refs
Retrieval of cloud droplet size distribution parameters from polarized reflectance measurements
Directory of Open Access Journals (Sweden)
M. Alexandrov
2011-09-01
Full Text Available We present an algorithm for retrieval of cloud droplet size distribution parameters (effective radius and variance from the Research Scanning Polarimeter (RSP measurements. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS, which is due to be launched as part of the NASA Glory Project. This instrument measures both polarized and total reflectances in 9 spectral channels with center wavelengths ranging from 410 to 2250 nm. For cloud droplet size retrievals we utilize the polarized reflectances in the scattering angle range between 140 and 170 degrees where they exhibit rainbow. The shape of the rainbow is determined mainly by single-scattering properties of the cloud particles, that simplifies the inversions and reduces retrieval uncertainties. The retrieval algorithm was tested using realistically simulated cloud radiation fields. Our retrievals of cloud droplet sizes from actual RSP measurements made during two recent field campaigns were compared with the correlative in situ observations.
Peng, Feng; Li, Chuang; Yang, Jun; Hou, Chengcheng; Zhang, Haoliang; Yu, Zhangjun; Yuan, Yonggui; Li, Hanyang; Yuan, Libo
2017-07-10
We propose a dual-channel measurement system for evaluating the optical path symmetry of an interferometric fiber optic gyro (IFOG) coil. Utilizing a bidirectional distributed polarization measurement system, the forward and backward transmission performances of an IFOG coil are characterized simultaneously by just a one-time measurement. The simple but practical configuration is composed of a bidirectional Mach-Zehnder interferometer and multichannel transmission devices connected to the IFOG coil under test. The static and dynamic temperature results of the IFOG coil reveal that its polarization-related symmetric properties can be effectively obtained with high accuracy. The optical path symmetry investigation is highly beneficial in monitoring and improving the winding technology of an IFOG coil and reducing the nonreciprocal effect of an IFOG.
Gluon chains and multiquark hadrons
International Nuclear Information System (INIS)
Jadach, S.; Jezabek, M.
1979-01-01
A monopole approximation to the confining potential is proposed. In this approximation spatially separated groups of quarks carry a definite total colour charge. The potentials which lead to the formation of gluon chains are discussed. The generalization of a (3,3bar) chain notion, studied by Tiktopoulos, to the case of arbitrary colour charges is given. It is argued that these generalized chains may be unstable with respect to splitting into a system of weakly interacting chains of the (3,3bar) type. A unified picture of the high energy hadronic collisions, based on the gluon chain notion and the monopole approximation is proposed. In the meson-meson sector this picture is equivalent to the topological approach. For the other processes it is similar to the approach of Rossi and Veneziano. However, it is argued that the introduction of the junction line into the quark frame is superfluous. The results are expressed in the language of the coloured dual diagrams which provide a generalization of those of Harari and Rosner. (author)
Single decay-lepton angular distributions in polarized e+e- t¯t and ...
Indian Academy of Sciences (India)
may be obtained on the real and imaginary parts of the electric and weak dipole ... An e·e linear collider operating at centre-of-mass (cm) energy of 500 GeV or higher ... systems to be unobservably small, in some extensions of SM, CP violation might be con- .... soft-gluon approximation are presented here for the first time.
Ward identities for amplitudes with reggeized gluons
International Nuclear Information System (INIS)
Bartles, J.; Vacca, G.P.
2012-05-01
Starting from the effective action of high energy QCD we derive Ward identities for Green's functions of reggeized gluons. They follow from the gauge invariance of the effective action, and allow to derive new representations of amplitudes containing physical particles as well as reggeized gluons. We explicitly demonstrate their validity for the BFKL kernel, and we present a new derivation of the kernel.
Soft gluon resummation for gluon-induced Higgs Strahlung
Energy Technology Data Exchange (ETDEWEB)
Harlander, Robert; Zirke, Tom [Fachbereich C, Bergische Universitaet Wuppertal (Germany); Kulesza, Anna; Theeuwes, Vincent [Institute for Theoretical Physics, WWU Muenster (Germany)
2015-07-01
We study the effect of soft gluon emission on the total cross section predictions for the gg → HZ associated Higgs production process at the LHC. To this end, we perform resummation of threshold corrections at the NLL accuracy in the absolute threshold production limit and in the threshold limit for production of a ZH system with a given invariant mass. Analytical results and numerical predictions for various possible LHC collision energies are presented. The perturbative stability of the results is verified by including universal NNLL effects. We find that resummation significantly reduces the scale uncertainty of the gg → HZ contribution, which is the dominant source of perturbative uncertainty to ZH production. We use our results to evaluate updated numbers for the total inclusive cross section of associated pp → ZH production at the LHC. The reduced scale uncertainty of the gg → HZ component translates into a decrease of the overall scale error by about a factor of two.
Polarization states encoded by phase modulation for high bit rate quantum key distribution
International Nuclear Information System (INIS)
Liu Xiaobao; Tang Zhilie; Liao Changjun; Lu Yiqun; Zhao Feng; Liu Songhao
2006-01-01
We present implementation of quantum cryptography with polarization code by wave-guide type phase modulator. At four different low input voltages of the phase modulator, coder encodes pulses into four different polarization states, 45 o , 135 o linearly polarized or right, left circle polarized, while the decoder serves as the complementary polarizers
Baryonic decay of the J/psi and gluon spin
International Nuclear Information System (INIS)
Pallin, D.
1985-04-01
A study of the J/psi state of the charmomium (c antic state) was performed at the D.C.I. collider in Orsay with the DM2 detector. 9 millions of J/psi have been produced, corresponding to more than one half of the actual world statistics. The very simple mecanism of the e +- annihilation into baryon-antibaryon via the J/psi state, allows measurements of the gluon spin through the emitted baryon angular distribution. The analyse of the channels J/psi → p antip and Λ antiΛ, permits to obtain parameters for the angular distributions. These experimental values favour very clearly a vectorial gluon hypothesis, as postulated by the quantum Chromodynamics [fr
Parton distributions from SMC and SLAC data
International Nuclear Information System (INIS)
Ramsey, G.P.
1996-01-01
We have extracted spin-weighted parton distributions in a proton from recent data at CERN and SLAC. The valence, sea quark and Antiquark spin-weighted distributions are determined separately. The data are all consistent with a small to moderate polarized gluon distribution, so that the anomaly term is not significant in the determination of the constituent contributions to the spin of the proton. We have analyzed the consistency of the results obtained from various sets of data and the Biorken sum rule. Although all data are consistent with the sum rule, the polarized distributions from different experiments vary, even with higher order QCD corrections taken into account. Results split into two models, one set implying a large polarized strange sea which violates the positivity bound, and the other set yielding a smaller polarized strange sea. Only further experiments which extract information about the polarized sea will reconcile these differences. We suggest specific experiments which can be performed to determine the size of the polarized sea and gluons
Duality and multi-gluon scattering
International Nuclear Information System (INIS)
Mangano, M.; Parke, S.; Xu Zhan
1988-01-01
For the six-gluon scattering process we give explicit and simple expressions for the amplitude and its square. To achieve this we use an analogy with string theories to identify a unique procedure for writing the multi-gluon scattering amplitudes in terms of a sum of gauge invariant dual sub-amplitudes multiplied by an appropriate color (Chan-Paton) factor. The sub-amplitudes defined in this way are invariant under cyclic permutations, satisfy powerful identities which relate different non-cyclic permutations and factorize in the soft gluon limit, the two-gluon collinear limit and on multi-gluon poles. Also, to leading order in the number of colors these sub-amplitudes sum incoherently in the square of the full matrix element. The results contained here are important for Monte Carlo studies of multi-jet processes at hadron colliders as well as for understanding the general structure of QCD. (orig.)
Comiso, Joey C.
1995-01-01
Surface temperature is one of the key variables associated with weather and climate. Accurate measurements of surface air temperatures are routinely made in meteorological stations around the world. Also, satellite data have been used to produce synoptic global temperature distributions. However, not much attention has been paid on temperature distributions in the polar regions. In the polar regions, the number of stations is very sparse. Because of adverse weather conditions and general inaccessibility, surface field measurements are also limited. Furthermore, accurate retrievals from satellite data in the region have been difficult to make because of persistent cloudiness and ambiguities in the discrimination of clouds from snow or ice. Surface temperature observations are required in the polar regions for air-sea-ice interaction studies, especially in the calculation of heat, salinity, and humidity fluxes. They are also useful in identifying areas of melt or meltponding within the sea ice pack and the ice sheets and in the calculation of emissivities of these surfaces. Moreover, the polar regions are unique in that they are the sites of temperature extremes, the location of which is difficult to identify without a global monitoring system. Furthermore, the regions may provide an early signal to a potential climate change because such signal is expected to be amplified in the region due to feedback effects. In cloud free areas, the thermal channels from infrared systems provide surface temperatures at relatively good accuracies. Previous capabilities include the use of the Temperature Humidity Infrared Radiometer (THIR) onboard the Nimbus-7 satellite which was launched in 1978. Current capabilities include the use of the Advance Very High Resolution Radiometer (AVHRR) aboard NOAA satellites. Together, these two systems cover a span of 16 years of thermal infrared data. Techniques for retrieving surface temperatures with these sensors in the polar regions have
HUNTING THE QUARK GLUON PLASMA.
Energy Technology Data Exchange (ETDEWEB)
LUDLAM, T.; ARONSON, S.
2005-04-11
The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear
HUNTING THE QUARK GLUON PLASMA
International Nuclear Information System (INIS)
LUDLAM, T.; ARONSON, S.
2005-01-01
The U.S. Department of Energy's Relativistic Heavy Ion Collider (RHIC) construction project was completed at BNL in 1999, with the first data-taking runs in the summer of 2000. Since then the early measurements at RHIC have yielded a wealth of data, from four independent detectors, each with its international collaboration of scientists: BRAHMS, PHENIX, PHOBOS, and STAR [1]. For the first time, collisions of heavy nuclei have been carried out at colliding-beam energies that have previously been accessible only for high-energy physics experiments with collisions of ''elementary'' particles such as protons and electrons. It is at these high energies that the predictions of quantum chromodynamics (QCD), the fundamental theory that describes the role of quarks and gluons in nuclear matter, come into play, and new phenomena are sought that may illuminate our view of the basic structure of matter on the sub-atomic scale, with important implications for the origins of matter on the cosmic scale. The RHIC experiments have recorded data from collisions of gold nuclei at the highest energies ever achieved in man-made particle accelerators. These collisions, of which hundreds of millions have now been examined, result in final states of unprecedented complexity, with thousands of produced particles radiating from the nuclear collision. All four of the RHIC experiments have moved quickly to analyze these data, and have begun to understand the phenomena that unfold from the moment of collision as these particles are produced. In order to provide benchmarks of simpler interactions against which to compare the gold-gold collisions, the experiments have gathered comparable samples of data from collisions of a very light nucleus (deuterium) with gold nuclei, as well as proton-proton collisions, all with identical beam energies and experimental apparatus. The early measurements have revealed compelling evidence for the existence of a new form of nuclear matter at extremely high
Gluons from logarithmic slopes of F2 in the NLL approximation
International Nuclear Information System (INIS)
Golec-Biernat, K.
1994-02-01
We make a critical, next-to-leading order, study of the accuracy of the ''Prytz'' relation, which is frequently used to extract the gluon distribution at small x from the logarithmic slopes of the structure function F 2 . We find that the simple relation is not generally valid in the HERA regime, but show that it is a reasonable approximation for gluons which are sufficiency singular at small x. (author). 9 refs, 3 figs
Dilepton spectrum from quark-gluon plasma in second Born approximation
International Nuclear Information System (INIS)
Makhlin, A.N.
1989-01-01
The real time temperature Keldysh technique has been used to calculate the rate of dilepton emission from quark-gluon plasma in the first order with respect to strong coupling constant. This approximation us shown to be inconsistent. The radiative corrections turned to be of the same order as the contribution of real processes with gluons. Nevertheless the general properties inherent in dilepton emission from continuous media can be verified by measuring the lepton distribution inside the dilepton. 11 refs.; 2 figs
Hadronic total cross-sections through soft gluon summation in impact parameter space
International Nuclear Information System (INIS)
Grau, A.
1999-01-01
IThe Bloch-Nordsieck model for the parton distribution of hadrons in impact parameter space, constructed using soft gluon summation, is investigated in detail. Its dependence upon the infrared structure of the strong coupling constant α s is discussed, both for finite as well as singular, but integrable, α s . The formalism is applied to the prediction of total proton-proton and proton-antiproton cross-sections, where screening, due to soft gluon emission from the initial valence quarks, becomes evident
Unpolarized and polarized parton densities in term of Fermi-Dirac distributions
International Nuclear Information System (INIS)
Bourrely, C.
1996-01-01
A description of quark parton densities of the proton in terms of Fermi-Dirac distributions parametrized with very few parameters is given. It allows a fair description of the NMC, BCDMS, SLAC and HERA data on F 2 p (x,Q 2 ) in a broad range of x and Q 2 . With some simple assumptions unpolarized and polarized quark parton distributions are related which lead to a fair description of the spin-dependent structure functions xg 1 p (x,Q 2 ) and xg 1 n (x,Q 2 ). Finally, several predictions are presented for lepton pair and gauge boson production in pp collisions at energies accessible in the future at RHIC. (author)
International Nuclear Information System (INIS)
Cipriano, P.; Dooling, S.; Grebenyuk, A.; Gunnellini, P.; Katsas, P.; Hautmann, F.; Oxford Univ.; Jung, H.; Antwerpen Univ.
2013-08-01
In the forthcoming high-luminosity phase at the LHC many of the most interesting QCD measurements so far become prohibitively difficult due to the high pile-up. We suggest a program of QCD measurements based on the observed Higgs boson which can be started now and can be carried through also in the large pile-up environment at high luminosity. It focuses on gluonic processes at high mass scales, and their distinctive QCD features compared to classic probes such as Drell-Yan. It explores the strong-interaction sector of the Standard Model both at high transverse momenta and at low transverse momenta, by investigating issues on gluon fusion processes which have never been addressed experimentally before. We discuss a few specific examples and present results of Monte Carlo simulations.
Energy Technology Data Exchange (ETDEWEB)
Cipriano, P.; Dooling, S.; Grebenyuk, A.; Gunnellini, P.; Katsas, P. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hautmann, F. [Sussex Univ., Brighton (United Kingdom). Dept. of Physics and Astronomy; Oxford Univ. (United Kingdom). Dept. of Physics; Jung, H. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Antwerpen Univ. (Belgium). Elementaire Deeltjes Fysica
2013-08-15
In the forthcoming high-luminosity phase at the LHC many of the most interesting QCD measurements so far become prohibitively difficult due to the high pile-up. We suggest a program of QCD measurements based on the observed Higgs boson which can be started now and can be carried through also in the large pile-up environment at high luminosity. It focuses on gluonic processes at high mass scales, and their distinctive QCD features compared to classic probes such as Drell-Yan. It explores the strong-interaction sector of the Standard Model both at high transverse momenta and at low transverse momenta, by investigating issues on gluon fusion processes which have never been addressed experimentally before. We discuss a few specific examples and present results of Monte Carlo simulations.
International Nuclear Information System (INIS)
Manoshin, S; Rubtsov, A; Bodnarchuk, V; Mattauch, S; Ioffe, A
2014-01-01
Latest developments of the polarized neutron suite in the VITESS simulation package allowed for simulations of time-dependent spin handling devices (e.g. radio-frequency (RF) flippers, adiabatic gradient RF-flippers) and the instrumentation built upon them (NRSE, SESANS, MIEZE, etc.). However, till now the magnetic field distribution in such devices have been considered as 'ideal' (sinusoidal, triangular or rectangular), when the main practical interest is in the use of arbitrary magnetic field distributions (either obtained by the field mapping or by FEM calculations) that may significantly influence the performance of real polarized neutron instruments and is the key issue in the practical use of the simulation packages. Here we describe modified VITESS modules opening the possibility to load the magnetic field 3-dimensional space map from an external source (file). Such a map can be either obtained by direct measurements or calculated by dedicated FEM programs (such as ANSYS, MagNet, Maxwell or similar). The successful use of these new modules is demonstrated by a very good agreement of neutron polarimetric experiments with performance of the spin turner with rotating magnetic field and an adiabatic gradient RF-flipper simulated by VITESS using calculated 3-dimensional field maps (using MagNet) and magnetic field mapping, respectively.
Constituent gluon interpretation of glueballs and gluelumps
International Nuclear Information System (INIS)
Boulanger, N.; Buisseret, F.; Mathieu, V.; Semay, C.
2008-01-01
Arguments are given that support the interpretation of the lattice QCD glueball and gluelump spectra in terms of bound states of massless constituent gluons with helicity 1. In this scheme, we show that the mass hierarchy of the currently known gluelumps and glueballs is mainly due to the number of constituent gluons and can be understood within a simple flux tube model. It is also argued that the lattice QCD 0 +- glueball should be seen as a four-gluon bound state. We finally predict the mass of the 0 - state, not yet computed in lattice QCD. (orig.)
The gluon Sivers asymmetry measurements at COMPASS
Szabelski, Adam
2018-01-01
The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. As such, a nonzero Sivers effect for gluons could be a signature of their nonzero orbital angular momentum inside the nucleon. COMPASS has collected data of semi-inclusive deep inelastic scattering by impinging 160 GeV/$c$ muons on transversely polarised proton and deuteron targets. The gluon Sivers asymmetry is extracted from a high-$p_T$ hadron pair sample with the use of monte carlo simulations and the a neural network approach. The results of a similar analysis for a Collins-like asymmetry for gluons will also be given.
The gluon Sivers asymmetry measurements at COMPASS
Szabelski, Adam
2017-01-01
The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. As such, a nonzero Sivers effect for gluons could be a signature of their nonzero orbital angular momentum inside the nucleon. COMPASS has collected data of semi-inclusive deep inelastic scattering by impinging 160 GeV/$c$ muons on transversely polarised proton and deuteron targets. The gluon Sivers asymmetry is extracted from a high-$p_T$ hadron pair sample with the use of monte carlo simulations and the a neural network approach. The results of a similar analysis for a Collins-like asymmetry for gluons will also be given.
DEFF Research Database (Denmark)
Bechshøft, T.Ø.; Jakobsen, Jette; Sonne, C.
2011-01-01
of the organ to sample in order to get a representative value for this important biomarker. The aim here was to assess the distribution of vitamins A (retinol) and E (α-tocopherol) within the polar bear multireniculate kidney (i.e. polar vs. medial position) and also within the cortex vs. medulla of each...... separate renculi. The results showed no significant difference between the medial and polar renculi with regards to either retinol (p=0.44) or α-tocopherol (p=0.75). There were, however, significant differences between cortex and medulla for both vitamins (retinol, p=0.0003; α-tocopherol, p...
Soft gluon resummation in the infrared region and the Froissart bound
Pancheri, Giulia; Godbole, Rohini M; Srivastava, Yogendra N
2010-01-01
We describe the taming effect induced by soft gluon $k_t$-resummation on the rapid rise of QCD mini-jet contributions to the total cross-sections.This results from an eikonal model in which the rise of the total cross-section is due to mini-jet contribution. We perform the calculation with current Parton Density Functions (PDFs). The impact parameter distribution we use is obtained as the Fourier transform of the resummed $k_t$-distribution of soft gluons emitted from the initial state during the collision.The emission, which is energy dependent, destroys the initial collinearity of partons.In this model, the strong power-like rise due to the increasing number of low-x gluon collisions is tamed by the acollinearity induced by soft gluon kt-resummation down to zero gluon momenta. It explicitly links a singular soft gluon coupling in the infrared region to the behaviour dictated by the Froissart bound for the total cross-section. The model describes well both proton and photon processes at present accelerator e...
Spatial distribution of spin polarization in a channel on the surface of a topological insulator
International Nuclear Information System (INIS)
Zhou Xiaoying; Shao Huaihua; Liu Yiman; Tang Dongsheng; Zhou Guanghui
2012-01-01
We study the spatial distribution of electron spin polarization for a gate-controlled T-shaped channel on the surface of a three-dimensional topological insulator (3D TI). We demonstrate that an energy gap depending on channel geometry parameters is definitely opened due to the spatial confinement. Spin surface locking in momentum space for a uniform wide channel with Hamiltonian linearity in the wavevector is still kept, but it is broken with Hamiltonian nonlinearity in the wavevector, like that for two-dimensional surface states widely studied in the literature. However, the spin surface locking for a T-shaped channel is broken even with Hamiltonian linearity in the wavevector. Interestingly, the magnitude and direction of the in-plane spin polarization are spatially dependent in all regions due to the breaking of translational symmetry of the T-shaped channel system. These interesting findings for an electrically controlled nanostructure based on the 3D TI surface may be testable with the present experimental technique, and may provide further understanding the nature of 3D TI surface states. (paper)
On the distribution of energy versus Alfvénic correlation for polar wind fluctuations
Directory of Open Access Journals (Sweden)
B. Bavassano
2006-11-01
Full Text Available Previous analyses have shown that polar wind fluctuations at MHD scales appear as a mixture of Alfvénic fluctuations and variations with an energy imbalance in favour of the magnetic term. In the present study, by separately examining the behaviour of kinetic and magnetic energies versus the Alfvénic correlation level, we unambiguously confirm that the second population is essentially related to a large increase of the magnetic energy with respect to that of the Alfvénic population. The relevant new result is that this magnetic population, though of secondary importance in terms of occurrence frequency, corresponds to a primary peak in the distribution of total energy. The fact that this holds in the case of polar wind, which is the least structured type of interplanetary plasma flow and with the slowest evolving Alfvénic turbulence, strongly suggests the general conclusion that magnetic structures cannot be neglected when modeling fluctuations for all kinds of wind regime.
International Nuclear Information System (INIS)
Koller, K.; Zerwas, P.M.; Walsh, T.F.
1978-12-01
We show how the Q 2 evolution of gluon jets can be used to provide indirect but strong evidence for the 3 gluon vertex of QCD. We propose looking for this evolution in the QantiQ → 3G → hadrons decay of successive 1 3 S 1 quarkonium states. The results apply to other processes if G jets can be isolated. (orig.) [de
The structure of the gluon propagator
Energy Technology Data Exchange (ETDEWEB)
Leinweber, D.B.; Parrinello, C.; Skullerud, J.I.; Williams, A.G
1999-03-01
The gluon propagator has been calculated for quenched QCD in the Landau gauge at {beta} = 6.0 for volumes 16{sup 3} x 48 and 32{sup 3} x 64, and at {beta} 6.2 for volume 24{sup 3} x 48. The large volume and different lattice spacings allow us to identify and minimise finite volume and finite lattice spacing artefacts. We also study the tensor structure of the gluon propagator, confirming that it obeys the lattice Landau gauge condition.
Describing gluons at zero and finite temperature
International Nuclear Information System (INIS)
Maas, A.
2010-01-01
Any description of gluons requires a well-defined gauge. This is complicated non-perturbatively by Gribov copies. A possible method-independent gauge definition to resolve this problem is presented and afterwards used to study the properties of gluons at any temperature. It is found that only chromo-electric properties reflect the phase transition. From these the gauge-invariant phase transition temperature is determined for SU(2) and SU(3) Yang-Mills theory independently. (author)
Identified particles in quark and gluon jets
Abreu, P; Adye, T; Ajinenko, I; Alekseev, G D; Alemany, R; Allport, P P; Almehed, S; Amaldi, Ugo; Amato, S; Andreazza, A; Andrieux, M L; Antilogus, P; Apel, W D; Åsman, B; Augustin, J E; Augustinus, A; Baillon, Paul; Bambade, P; Barão, F; Barbi, M S; Barbiellini, Guido; Bardin, Dimitri Yuri; Barker, G; Baroncelli, A; Bärring, O; Barrio, J A; Bartl, Walter; Bates, M J; Battaglia, Marco; Baubillier, M; Baudot, J; Becks, K H; Begalli, M; Beillière, P; Belokopytov, Yu A; Benvenuti, Alberto C; Berggren, M; Bertini, D; Bertrand, D; Besançon, M; Bianchi, F; Bigi, M; Bilenky, S M; Billoir, P; Bizouard, M A; Bloch, D; Blume, M; Bolognese, T; Bonesini, M; Bonivento, W; Booth, P S L; Bosio, C; Botner, O; Boudinov, E; Bouquet, B; Bourdarios, C; Bowcock, T J V; Bozzo, M; Branchini, P; Brand, K D; Brenke, T; Brenner, R A; Bricman, C; Brown, R C A; Brückman, P; Brunet, J M; Bugge, L; Buran, T; Burgsmüller, T; Buschmann, P; Cabrera, S; Caccia, M; Calvi, M; Camacho-Rozas, A J; Camporesi, T; Canale, V; Canepa, M; Cankocak, K; Cao, F; Carena, F; Carroll, L; Caso, Carlo; Castillo-Gimenez, M V; Cattai, A; Cavallo, F R; Chabaud, V; Charpentier, P; Chaussard, L; Checchia, P; Chelkov, G A; Chen, M; Chierici, R; Chliapnikov, P V; Chochula, P; Chorowicz, V; Chudoba, J; Cindro, V; Collins, P; Contri, R; Cortina, E; Cosme, G; Cossutti, F; Cowell, J H; Crawley, H B; Crennell, D J; Crosetti, G; Cuevas-Maestro, J; Czellar, S; Dahl-Jensen, Erik; Dahm, J; D'Almagne, B; Dam, M; Damgaard, G; Dauncey, P D; Davenport, Martyn; Da Silva, W; Defoix, C; Deghorain, A; Della Ricca, G; Delpierre, P A; Demaria, N; De Angelis, A; de Boer, Wim; De Brabandere, S; De Clercq, C; La Vaissière, C de; De Lotto, B; De Min, A; De Paula, L S; De Saint-Jean, C; Dijkstra, H; Di Ciaccio, Lucia; Di Diodato, A; Djama, F; Djannati, A; Dolbeau, J; Doroba, K; Dracos, M; Drees, J; Drees, K A; Dris, M; Durand, J D; Edsall, D M; Ehret, R; Eigen, G; Ekelöf, T J C; Ekspong, Gösta; Elsing, M; Engel, J P; Erzen, B; Espirito-Santo, M C; Falk, E; Fassouliotis, D; Feindt, Michael; Ferrer, A; Fichet, S; Filippas-Tassos, A; Firestone, A; Fischer, P A; Föth, H; Fokitis, E; Fontanelli, F; Formenti, F; Franek, B J; Frenkiel, P; Fries, D E C; Frodesen, A G; Frühwirth, R; Fulda-Quenzer, F; Fuster, J A; Galloni, A; Gamba, D; Gandelman, M; García, C; García, J; Gaspar, C; Gasparini, U; Gavillet, P; Gazis, E N; Gelé, D; Gerber, J P; Gerdyukov, L N; Gokieli, R; Golob, B; Gopal, Gian P; Gorn, L; Górski, M; Guz, Yu; Gracco, Valerio; Graziani, E; Green, C; Grefrath, A; Gris, P; Grosdidier, G; Grzelak, K; Gumenyuk, S A; Gunnarsson, P; Günther, M; Guy, J; Hahn, F; Hahn, S; Hajduk, Z; Hallgren, A; Hamacher, K; Harris, F J; Hedberg, V; Henriques, R P; Hernández, J J; Herquet, P; Herr, H; Hessing, T L; Heuser, J M; Higón, E; Hilke, Hans Jürgen; Hill, T S; Holmgren, S O; Holt, P J; Holthuizen, D J; Hoorelbeke, S; Houlden, M A; Hrubec, Josef; Huet, K; Hultqvist, K; Jackson, J N; Jacobsson, R; Jalocha, P; Janik, R; Jarlskog, C; Jarlskog, G; Jarry, P; Jean-Marie, B; Johansson, E K; Jönsson, L B; Jönsson, P E; Joram, Christian; Juillot, P; Kaiser, M; Kapusta, F; Karafasoulis, K; Karlsson, M; Karvelas, E; Katargin, A; Katsanevas, S; Katsoufis, E C; Keränen, R; Khokhlov, Yu A; Khomenko, B A; Khovanskii, N N; King, B J; Kjaer, N J; Klapp, O; Klein, H; Klovning, A; Kluit, P M; Köne, B; Kokkinias, P; Koratzinos, M; Korcyl, K; Kostyukhin, V; Kourkoumelis, C; Kuznetsov, O; Krammer, Manfred; Kreuter, C; Kronkvist, I J; Krumshtein, Z; Krupinski, W; Kubinec, P; Kucewicz, W; Kurvinen, K L; Lacasta, C; Laktineh, I; Lamsa, J; Lanceri, L; Lane, D W; Langefeld, P; Lapin, V; Laugier, J P; Lauhakangas, R; Leder, Gerhard; Ledroit, F; Lefébure, V; Legan, C K; Leitner, R; Lemonne, J; Lenzen, Georg; Lepeltier, V; Lesiak, T; Libby, J; Liko, D; Lindner, R; Lipniacka, A; Lippi, I; Lörstad, B; Loken, J G; López, J M; Loukas, D; Lutz, P; Lyons, L; MacNaughton, J N; Maehlum, G; Mahon, J R; Malmgren, T G M; Malychev, V; Mandl, F; Marco, J; Marco, R P; Maréchal, B; Margoni, M; Marin, J C; Mariotti, C; Markou, A; Martínez-Rivero, C; Martínez-Vidal, F; Martí i García, S; Masik, J; Matorras, F; Matteuzzi, C; Matthiae, Giorgio; Mazzucato, M; McCubbin, M L; McKay, R; McNulty, R; Medbo, J; Merk, M; Meroni, C; Meyer, S; Meyer, W T; Michelotto, M; Migliore, E; Mirabito, L; Mitaroff, Winfried A; Mjörnmark, U; Moa, T; Møller, R; Mönig, K; Monge, M R; Morettini, P; Müller, H; Münich, K; Mulders, M; Mundim, L M; Murray, W J; Muryn, B; Myatt, Gerald; Naraghi, F; Navarria, Francesco Luigi; Navas, S; Nawrocki, K; Negri, P; Neumann, W; Neumeister, N; Nicolaidou, R; Nielsen, B S; Nieuwenhuizen, M; Nikolaenko, V; Niss, P; Nomerotski, A; Normand, Ainsley; Novák, M; Oberschulte-Beckmann, W; Obraztsov, V F; Olshevskii, A G; Onofre, A; Orava, Risto; Österberg, K; Ouraou, A; Paganini, P; Paganoni, M; Pagès, P; Pain, R; Palka, H; Papadopoulou, T D; Papageorgiou, K; Pape, L; Parkes, C; Parodi, F; Passeri, A; Pegoraro, M; Peralta, L; Pernicka, Manfred; Perrotta, A; Petridou, C; Petrolini, A; Petrovykh, M; Phillips, H T; Piana, G; Pierre, F; Pimenta, M; Podobnik, T; Podobrin, O; Pol, M E; Polok, G; Poropat, P; Pozdnyakov, V; Privitera, P; Pukhaeva, N; Pullia, Antonio; Radojicic, D; Ragazzi, S; Rahmani, H; Rames, J; Ratoff, P N; Read, A L; Reale, M; Rebecchi, P; Redaelli, N G; Regler, Meinhard; Reid, D; Reinhardt, R; Renton, P B; Resvanis, L K; Richard, F; Richardson, J; Rídky, J; Rinaudo, G; Ripp, I; Romero, A; Roncagliolo, I; Ronchese, P; Roos, L; Rosenberg, E I; Roudeau, Patrick; Rovelli, T; Rückstuhl, W; Ruhlmann-Kleider, V; Ruiz, A; Rybicki, K; Rybin, A; Saarikko, H; Sacquin, Yu; Sadovskii, A; Sahr, O; Sajot, G; Salt, J; Sánchez, J; Sannino, M; Schimmelpfennig, M; Schneider, H; Schwickerath, U; Schyns, M A E; Sciolla, G; Scuri, F; Seager, P; Sedykh, Yu; Segar, A M; Seitz, A; Sekulin, R L; Serbelloni, L; Shellard, R C; Siegrist, P; Silvestre, R; Simonetti, S; Simonetto, F; Sissakian, A N; Sitár, B; Skaali, T B; Smadja, G; Smirnov, N; Smirnova, O G; Smith, G R; Sosnowski, R; Souza-Santos, D; Spassoff, Tz; Spiriti, E; Sponholz, P; Squarcia, S; Stampfer, D; Stanescu, C; Stanic, S; Stapnes, Steinar; Stavitski, I; Stevenson, K; Stocchi, A; Strauss, J; Strub, R; Stugu, B; Szczekowski, M; Szeptycka, M; Tabarelli de Fatis, T; Tavernet, J P; Chikilev, O G; Thomas, J; Tilquin, A; Timmermans, J; Tkatchev, L G; Todorov, T; Todorova, S; Toet, D Z; Tomaradze, A G; Tomé, B; Tonazzo, A; Tortora, L; Tranströmer, G; Treille, D; Tristram, G; Trombini, A; Troncon, C; Tsirou, A L; Turluer, M L; Tyapkin, I A; Tyndel, M; Tzamarias, S; Überschär, B; Ullaland, O; Uvarov, V; Valenti, G; Vallazza, E; Van der Velde, C; van Apeldoorn, G W; van Dam, P; Van Doninck, W K; Van Eldik, J; Van Lysebetten, A; Vassilopoulos, N; Vegni, G; Ventura, L; Venus, W A; Verbeure, F; Verlato, M; Vertogradov, L S; Vilanova, D; Vincent, P; Vitale, L; Vlasov, E; Vodopyanov, A S; Vrba, V; Wahlen, H; Walck, C; Weierstall, M; Weilhammer, Peter; Weiser, C; Wetherell, Alan M; Wicke, D; Wickens, J H; Wielers, M; Wilkinson, G R; Williams, W S C; Winter, M; Witek, M; Wlodek, T; Woschnagg, K; Yip, K; Yushchenko, O P; Zach, F; Zaitsev, A; Zalewska-Bak, A; Zalewski, Piotr; Zavrtanik, D; Zevgolatakos, E; Zimin, N I; Zito, M; Zontar, D; Zucchelli, G C; Zumerle, G
1997-01-01
A sample of about 1.4 million hadronic \\z decays, selected among the data recorded by the DELPHI detector at LEP during 1994, was used to measure for the first time the momentum spectra of \\kp, \\ko, \\p, \\l and their antiparticles in gluon and quark jets. As observed for inclusive charged particles, the production spectra of identified particles were found to be softer in gluon jets than in quark jets, with a higher total multiplicity.
A new hypothesis on the nature of quark and gluon confinement
International Nuclear Information System (INIS)
Gribov, V.N.
1986-06-01
A new hypothesis of quark confinement is proposed: formation of superbound states in light quark vacuum analogical to the electron states in the field of nuclei about Z 180. The vacuum polarization effect of a heavy antiquark produces a light quark-antiquark pair. If the effective charge of the central particle is greater than a critical value, the new antiquark goes to the infinity and the bounded quark screenes the color field of the central charge. Thus, the colored states are unstable and vacuum polarization produces colorless bound states. A similar effect of gluon instability can explain the structure of mesons with light quarks and antiquarks: the central self-bounded unstable gluon state polarizes and binds a light quark-antiquark pair. Consequences of the new hypothesis on the measurability of color charge, on the structure of baryons and on the possible experimental verification of the existence of the proposed structures are discussed. (D.Gy.)
J/ψ production in polarized and unpolarized ep collision and Sivers and cos 2φ asymmetries
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, Asmita; Rajesh, Sangem [Indian Institute of Technology Bombay, Department of Physics, Mumbai (India)
2017-12-15
We calculate the Sivers and cos 2φ azimuthal asymmetries in J/ψ production in the polarized and unpolarized semi-inclusive ep collision, respectively, using the formalism based on the transverse momentum-dependent parton distributions (TMDs). The non-relativistic QCD-based color octet model is employed in calculating the J/ψ production rate. The Sivers asymmetry in this process directly probes the gluon Sivers function. The estimated Sivers asymmetry at z = 1 is negative, which is in good agreement with the COMPASS data. The effect of TMD evolution on the Sivers asymmetry is also investigated. The cos 2φ asymmetry is sizable and probes the linearly polarized gluon distribution in an unpolarized proton. (orig.)
Directory of Open Access Journals (Sweden)
Gunnar Treff
2017-08-01
Full Text Available Polarized (POL training intensity distribution (TID emphasizes high-volume low-intensity exercise in zone (Z1 (< first lactate threshold with a greater proportion of high-intensity Z3 (>second lactate threshold compared to Z2 (between first and second lactate threshold. In highly trained rowers there is a lack of prospective controlled evidence whether POL is superior to pyramidal (PYR; i.e., greater volume in Z1 vs. Z2 vs. Z3 TID. The aim of the study was to compare the effect of POL vs. PYR TID in rowers during an 11-wk preparation period. Fourteen national elite male rowers participated (age: 20 ± 2 years, maximal oxygen uptake (V˙O2max: 66 ± 5 mL/min/kg. The sample was split into PYR and POL by varying the percentage spent in Z2 and Z3 while Z1 was clamped to ~93% and matched for total and rowing volume. Actual TIDs were based on time within heart rate zones (Z1 and Z2 and duration of Z3-intervals. The main outcome variables were average power in 2,000 m ergometer-test (P2,000 m, power associated with 4 mmol/L [blood lactate] (P4[BLa], and V˙O2max. To quantify the level of polarization, we calculated a Polarization-Index as log (%Z1 × %Z3 / %Z2. PYR and POL did not significantly differ regarding rowing or total volume, but POL had a higher percentage of Z3 intensities (6 ± 3 vs. 2 ± 1%; p < 0.005 while Z2 was lower (1 ± 1 vs. 3 ± 2%; p < 0.05 and Z1 was similar (94 ± 3 vs. 93 ± 2%, p = 0.37. Consequently, Polarization-Index was significantly higher in POL (3.0 ± 0.7 vs. 1.9 ± 0.4 a.u.; p < 0.01. P2,000 m did not significantly change with PYR (1.5 ± 1.7%, p = 0.06 nor POL (1.5 ± 2.6%, p = 0.26. V˙O2max did not change (1.7 ± 5.6%, p = 0.52 or 0.6 ± 2.6, p = 0.67 and a small increase in P4[BLa] was observed in PYR only (1.9 ± 4.8%, p = 0.37 or −0.5 ± 4.1%, p = 0.77. Changes from pre to post were not significantly different between groups in any performance measure. POL did not prove to be superior to PYR, possibly due to
Soft probes of the quark gluon plasma in ATLAS
Wozniak, K W; The ATLAS collaboration
2014-01-01
Measurements of low-$p_{T}$ (< 5 GeV) particle production have provided valuable insight on the production and evolution of the quark-gluon plasma in Pb+Pb collisions at the LHC. In particular, measurements of elliptic and higher order collective flow imprinted on the azimuthal angle distributions of low-$p_{T}$ particles directly probe the strongly-coupled dynamics of the quark gluon plasma and test hydrodynamic model descriptions of its evolution. The large acceptance of detectors like ATLAS have made it possible to measure flow event-by-event and to determine the correlations between different harmonics. Recent measurements of low-$p_{T}$ particle production and multi-particle correlations in proton-lead collisions have shown features similar to the collective flow observed in Pb+Pb collisions. Results will be presented from a variety of single and multi-particle measurements in Pb+Pb and proton-Pb collisions that probe the collective dynamics of the quark gluon plasma and possibly provide evidence for ...
Gluon density determination from open charm events at HERA
International Nuclear Information System (INIS)
Woudenberg, R. van; Ould-Saada, F.; Eisenberg, Y.; Glasman, C.; Karshon, U.; Montag, A.; Egli, S.
1992-01-01
We study some prospects of measuring the gluon density in the proton using charm events at HERA for the ep center of mass energy √s = 314 GeV. We invoke the QCD-improved boson-gluon fusion model and find the following cross-section: σ(ep → ecanti cX) ≅ O(0.6 μb). This cross-section would provide O(10 8 ) events/year, for an integrated luminosity of 100 pb -1 . We have investigated two traditional methods for tagging of charm, namely, D *± reconstruction using the process D *± → D 0 π ± → (K -+ π ± )π ± , and dileptonic decays of charmed hadrons (canti c → l + l - X). The inclusive cross-sections after full detector simulation are 10 3 pb and 10 2 pb, respectively. In both cases the background was strongly reduced. By using these events, the gluon distribution in the proton can be measured in the range 10 -3 ≤ x g ≤ 10 -1 . We conclude that an adequate discrimination among the present theoretical parametrizations can be achieved at HERA. (orig.)
Experimental study of rapidity gaps in gluon jets
Gary, J W
2003-01-01
Gluon jets are selected from hadronic Z/sup 0/ decay events produced in e/sup +/e/sup -/ annihilations, collected with the OPAL detector at LEP. A subsample of these jets is identified which exhibit a large gap in the rapidity distribution of particles within the jet. These jets are observed to demonstrate a high degree of sensitivity to the presence of color reconnection, i.e. higher order QCD processes affecting the underlying color structure. We test two QCD Monte Carlo programs which implement color reconnection: one in the Ariadne Monte Carlo and the other by Rathsman in the Pythia Monte Carlo. We find these models can describe our gluon jet measurements only if very large values are used for the cutoff parameters which serve to terminate the parton showers, and conclude that color reconnection as implemented in these models is disfavored. Further, we use our data on gluon jets with a rapidity gap to search for glueball-like objects in the leading part of those jets. We do not find any clear evidence for...
Smetacek, Victor; Klaas, Christine; Menden-Deuer, Susanne; Rynearson, Tatiana A.
The quantitative distribution of dominant phytoplankton species was mapped at high spatial resolution (15 km spacing) during a quasi-synoptic, mesoscale survey of hydrographical, chemical, pigment, and zooplankton fields carried out along the Antarctic Polar Front within a grid 140×130 km 2 during austral summer. A rapid assessment method for quantifying phytoplankton species by microscopy in concentrated samples on board enabled estimation of total biomass and that of dominant species at hourly sampling intervals. The biomass distribution pattern derived from this method was remarkably coherent and correlated very well with chlorophyll concentrations and the location of different water masses covered by the grid. A "background" chlorophyll concentration of 0.5 mg m -3 in the grid could be assigned to the uniformly distributed pico- and nanophytoplankton; all higher values (up to 2.0 mg m -3) were contributed by large diatoms. Three species complexes ( Chaetoceros atlanticus/dichaeta, Pseudo-nitzschia cf. Lineola, and Thalassiothrix antarctica) contributed about one-third each to the biomass. Although all species were found throughout the study area, distinct patterns in abundance emerged: The Thalassiothrix maximum was located north of the frontal jet, Chaetoceros biomass was highest along the jet, and Pseudo-nitzschia was the most uniformly distributed of the three taxa. Since the meridional pattern of biomass and species composition persisted for about 5 weeks, despite heavy grazing pressure of small copepods, we hypothesize that the dominant species reflect the highest degree of grazer protection in the assemblage. This is accomplished by large size, needle-shaped cells, and long spines armed with barbs. We suggest that these persistent species sequester the limiting nutrient—iron—from the assemblage of smaller, less-defended species that must hence have higher turn-over rates.
Multiplicities of $\\pi^{0}$, $\\eta$, $K^{0}$ and of charged particles in quark and gluon jets
Abbiendi, G.; Ainsley, C.; Akesson, P.F.; Alexander, G.; Allison, John; Anderson, K.J.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Bailey, I.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Biebel, O.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Boeriu, O.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Cammin, J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanti, M.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Glenzinski, D.; Goldberg, J.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hauke, A.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lawson, I.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; Lillich, J.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rembser, C.; Rick, H.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sarkisyan, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schmitt, S.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Tarem, S.; Taylor, R.J.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trefzger, T.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Vannerem, P.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.
2000-01-01
We compared the multiplicities of pizero, eta, Kzero and of charged particles in quark and gluon jets in 3-jet events, as measured by the OPAL experiment at LEP. The comparisons were performed for distributions unfolded to 100% pure quark and gluon jets, at an effective scale Qjet which took into account topological dependences of the 3-jet environment. The ratio of particle multiplicity in gluon jets to that in quark jets as a function of Qjet for pizero, eta and Kzero was found to be independent of the particle species. This is consistent with the QCD prediction that the observed enhancement in the mean particle rate in gluon jets with respect to quark jets should be independent of particle species. In contrast to some theoretical predictions and previous observations, we observed no evidence for an enhancement of eta meson production in gluon jets with respect to quark jets, beyond that observed for charged particles. We measured the ratio of the slope of the average charged particle multiplicity in gluon ...
Two-Loop Gluon to Gluon-Gluon Splitting Amplitudes in QCD
International Nuclear Information System (INIS)
Bern, Z.
2004-01-01
Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g → gg splitting amplitudes in QCD, N = 1, and N = 4 super-Yang-Mills theories, which describe the limits of two-loop n-point amplitudes where two gluon momenta become parallel. They also represent an ingredient in a direct x-space computation of DGLAP evolution kernels at next-to-next-to-leading order. To obtain the splitting amplitudes, we use the unitarity sewing method. In contrast to the usual light-cone gauge treatment, our calculation does not rely on the principal-value or Mandelstam-Leibbrandt prescriptions, even though the loop integrals contain some of the denominators typically encountered in light-cone gauge. We reduce the integrals to a set of 13 master integrals using integration-by-parts and Lorentz invariance identities. The master integrals are computed with the aid of differential equations in the splitting momentum fraction z. The ε-poles of the splitting amplitudes are consistent with a formula due to Catani for the infrared singularities of two-loop scattering amplitudes. This consistency essentially provides an inductive proof of Catani's formula, as well as an ansatz for previously-unknown 1/ε pole terms having non-trivial color structure. Finite terms in the splitting amplitudes determine the collinear behavior of finite remainders in this formula
Quarkonium states in an anisotropic quark-gluon plasma
Energy Technology Data Exchange (ETDEWEB)
Guo Yun
2009-09-10
In this work we study the properties of quarkonium states in a quark-gluon plasma which, due to expansion and non-zero viscosity, exhibits a local anisotropy in momentum space. We determine the hard-loop resummed gluon propagator in an anisotropic QCD plasma in general linear gauges and define a potential between heavy quarks from the Fourier transform of its static limit. This potential which arises due to one-gluon exchange describes the force between a quark and anti-quark at short distances. It is closer to the vacuum potential as compared to the isotropic Debye screened potential which indicates the reduced screening in an anisotropic QCD plasma. In addition, angular dependence appears in the potential; we find that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment. The potential at long distances, however, is non-perturbative and modeled as a QCD string which is screened at the same scale as the Coulomb field. At asymptotic separation the potential energy is non-zero and inversely proportional to the temperature. With a phenomenological potential model which incorporates the different behaviors at short and long distances, we solve the three-dimensional Schroedinger equation. Our numerical results show that quarkonium binding is stronger at non-vanishing viscosity and expansion rate, and that the anisotropy leads to polarization of the P-wave states. Furthermore, we determine viscosity corrections to the imaginary part of the heavy-quark potential in the weak-coupling hard-loop approximation. The imaginary part is found to be smaller (in magnitude) than at vanishing viscosity. This implies a smaller decay width of quarkonium bound states in an anisotropic plasma. (orig.)
Quarkonium states in an anisotropic quark-gluon plasma
International Nuclear Information System (INIS)
Guo Yun
2009-01-01
In this work we study the properties of quarkonium states in a quark-gluon plasma which, due to expansion and non-zero viscosity, exhibits a local anisotropy in momentum space. We determine the hard-loop resummed gluon propagator in an anisotropic QCD plasma in general linear gauges and define a potential between heavy quarks from the Fourier transform of its static limit. This potential which arises due to one-gluon exchange describes the force between a quark and anti-quark at short distances. It is closer to the vacuum potential as compared to the isotropic Debye screened potential which indicates the reduced screening in an anisotropic QCD plasma. In addition, angular dependence appears in the potential; we find that there is stronger attraction on distance scales on the order of the inverse Debye mass for quark pairs aligned along the direction of anisotropy than for transverse alignment. The potential at long distances, however, is non-perturbative and modeled as a QCD string which is screened at the same scale as the Coulomb field. At asymptotic separation the potential energy is non-zero and inversely proportional to the temperature. With a phenomenological potential model which incorporates the different behaviors at short and long distances, we solve the three-dimensional Schroedinger equation. Our numerical results show that quarkonium binding is stronger at non-vanishing viscosity and expansion rate, and that the anisotropy leads to polarization of the P-wave states. Furthermore, we determine viscosity corrections to the imaginary part of the heavy-quark potential in the weak-coupling hard-loop approximation. The imaginary part is found to be smaller (in magnitude) than at vanishing viscosity. This implies a smaller decay width of quarkonium bound states in an anisotropic plasma. (orig.)
Directory of Open Access Journals (Sweden)
K. Horikawa
2014-10-01
Full Text Available In 1957, Agodi predicted that the neutron angular distribution in (γ, n reactions with a 100% linearly polarized γ-ray beam for dipole excitation should be anisotropic and universally described by the simple function of a+b⋅cos(2ϕ at the polar angle θ=90°, where ϕ is the azimuthal angle. However, this prediction has not been experimentally confirmed in over half a century. We have verified experimentally this angular distribution in the (γ, n reaction for 197Au, 127I, and natural Cu targets using linearly polarized laser Compton scattering γ-rays. The result suggests that the (γ→, n reaction is a novel tool to study nuclear physics in the giant dipole resonance region.
International Nuclear Information System (INIS)
Robinet, F.
2008-09-01
The 1/2 spin of the nucleon decomposes into 3 contributions: the quark and the gluon spin and their angular momenta. It is known that the fraction of the nucleon spin carried by the quark is small. Nowadays, a series of measurements aims to determine the contribution of the gluon spin in order, perhaps, to recover the totality of the nucleon spin. This is one of the main goals of the COMPASS experiment at CERN where spin asymmetries are measured using a polarized muon beam on a polarized nucleon target. The photon-gluon fusion processes, sensitive to the gluon polarization, are selected by detecting D 0 in the final state. This method offers a very clean selection of the desired signal but is statistically limited. The work presented in this thesis is primarily focused on the development of an analysis method maximizing the statistics. In particular, the D 0 mesons reconstruction is submitted to a high combinatorial background. Parameterizing the probability for an event to signal the statistical error is significantly reduced. The momentum resolution, associated with the particle detection, is an important factor allowing to minimize the combinatorial background. This thesis presents the characteristics of drift chamber-type detectors contributing to the performances of the COMPASS spectrometer. Finally, the results joined by the systematic errors study, are presented along with their implications on the contribution of the gluon spin to the nucleon spin. (author)
Asymmetry of prompt photon production in polarized pp collisions at RHIC
Energy Technology Data Exchange (ETDEWEB)
Skoro, G.P.; Zupan, M. [Institute of Nuclear Science ' Vinca' , Faculty of Physics University of Belgrade, (Yugoslavia); Tokarev, M.V. [Laboratory of High Energies, Joint Institute of Nuclear Research Dubna, Moscow Region (Russian Federation)
1999-08-01
The prompt photon production in polarized pp collision at high energies is studied. The double-spin asymmetry A{sub LL} of the process of calculated by using the Monte Carlo code Sphinx. A possibility to discriminate the spin-dependent gluon distributions and to determine the sign of {delta}G is discussed. A detailed study of the expected background, such as {pi}{sup 0} production and decay, is given. Predictions for the longitudinal asymmetry A{sub LL} of the prompt photons and {pi}{sup 0}-meson production in the polarized pp collisions at RHIC energies have been made.
Asymmetry of prompt photon production in polarized pp collisions at RHIC
International Nuclear Information System (INIS)
Skoro, G.P.; Zupan, M.; Tokarev, M.V.
1999-01-01
The prompt photon production in polarized pp collision at high energies is studied. The double-spin asymmetry A LL of the process of calculated by using the Monte Carlo code SPHINX. A possibility to discriminate the spin-dependent gluon distributions and to determine the sign of ΔG id discussed. A detailed study of the expected background, such as π 0 production and decay, is given. Predictions for the longitudinal asymmetry A LL of the prompt photons and π 0 -meson production in the polarized pp collisions at RHIC energies have been made
DEFF Research Database (Denmark)
Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer
2009-01-01
We solve the three-dimensional time-dependent Schrödinger equation for a three-cycle circularly polarized laser pulse interacting with an atom. The photoelectron momentum distributions show counterintuitive shifts, similar to those observed in a recent experiment (Eckle et al 2008 Science 322 1525...
QCD analysis of polarized deep inelastic scattering data
International Nuclear Information System (INIS)
Bluemlein, Johannes; Boettcher, Helmut
2010-05-01
A QCD analysis of the world data on polarized deep inelastic scattering is presented in next-to-leading order, including the heavy flavor Wilson coefficient in leading order in the fixed flavor number scheme. New parameterizations are derived for the quark and gluon distributions and the value of α s (M z 2 ) is determined. The impact of the variation of both the renormalization and factorization scales on the distributions and the value of α s is studied. We obtain α s NLO (M Z 2 )=0.1132 -0.0095 +0.0056 . The first moments of the polarized twist-2 parton distribution functions are calculated with correlated errors to allow for comparisons with results from lattice QCD simulations. Potential higher twist contributions to the structure function g 1 (x,Q 2 ) are determined and found to be compatible with zero both for proton and deuteron targets. (orig.)
Quantum Simulations of Strongly Coupled Quark-Gluon Plasma
International Nuclear Information System (INIS)
Filinov, V.S.; Bonitz, M.; Ivanov, Yu.B.
2013-01-01
particles. This method has been successfully applied to strongly coupled electrodynamic plasmas (EMP). A strongly correlated behavior of the QGP is expected to show up in long-ranged spatial correlations of quarks and gluons which, in fact, may give rise to liquid-like and, possibly, solid-like structures. This expectation is based on a very similar behavior observed in electrodynamic plasmas. We have done already the first calculation of the QGP equation of state, spatial and color pair distribution functions, diffusion coefficients and shear viscosity. The preliminary results has already been reported and discussed at the international conferences and meetings and are accepted for publications. (author)
A polarized neutron study of the magnetization distribution in Co2FeSi
International Nuclear Information System (INIS)
Brown, P J; Kainuma, R; Kanomata, T; Okubo, A; Neumann, K-U; Umetsu, R Y; Ziebeck, K R A
2013-01-01
The magnetization distribution in Co 2 FeSi which has the largest moment per formula unit ∼6 μ B of all Heusler alloys, has been determined using polarized neutron diffraction. The experimentally determined magnetization has been integrated over spheres centred on the three sites of the L1 2 structure giving μ Fe = 3.10(3) μ B and μ Co = 1.43(2) μ B , results which are slightly lower than the moments in atomic spheres of similar radii obtained in recent LDA + U band structure calculations (Li et al 2010 Chin. Phys. B 19 097102). Approximately 50% of the magnetic carriers at the Fe sites were found to be in orbitals with e g symmetry. This was higher, ≃65%, at the Co sites. Both Fe and Co were found to have orbital moments that are larger than those predicted. Comparison with similar results obtained for related alloys suggests that there must be a finite density of states in both spin bands at the Fermi energy indicating that Co 2 FeSi is not a perfect half-metallic ferromagnet. (paper)
A polarized neutron study of the magnetization distribution in Co₂FeSi.
Brown, P J; Kainuma, R; Kanomata, T; Neumann, K-U; Okubo, A; Umetsu, R Y; Ziebeck, K R A
2013-05-22
The magnetization distribution in Co2FeSi which has the largest moment per formula unit ∼6 μB of all Heusler alloys, has been determined using polarized neutron diffraction. The experimentally determined magnetization has been integrated over spheres centred on the three sites of the L12 structure giving μ Fe = 3.10(3) μB and μ Co = 1.43(2) μB, results which are slightly lower than the moments in atomic spheres of similar radii obtained in recent LDA + U band structure calculations (Li et al 2010 Chin. Phys. B 19 097102). Approximately 50% of the magnetic carriers at the Fe sites were found to be in orbitals with eg symmetry. This was higher, ≃65%, at the Co sites. Both Fe and Co were found to have orbital moments that are larger than those predicted. Comparison with similar results obtained for related alloys suggests that there must be a finite density of states in both spin bands at the Fermi energy indicating that Co2FeSi is not a perfect half-metallic ferromagnet.
Adamczyk, L; Adkins, J K; Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alekseev, I; Alford, J; Anson, C D; Aparin, A; Arkhipkin, D; Aschenauer, E C; Averichev, G S; Banerjee, A; Beavis, D R; Bellwied, R; Bhasin, A; Bhati, A K; Bhattarai, P; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Brandin, A V; Brovko, S G; Bültmann, S; Bunzarov, I; Burton, T P; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, J M; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Chwastowski, J; Codrington, M J M; Contin, G; Cramer, J G; Crawford, H J; Cudd, A B; Cui, X; Das, S; Davila Leyva, A; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; Derradi de Souza, R; Dhamija, S; di Ruzza, B; Didenko, L; Dilks, C; Ding, F; Djawotho, P; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunkelberger, L E; Dunlop, J C; Efimov, L G; Engelage, J; Engle, K S; Eppley, G; Eun, L; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Fedorisin, J; Filip, P; Finch, E; Fisyak, Y; Flores, C E; Gagliardi, C A; Gangadharan, D R; Garand, D; Geurts, F; Gibson, A; Girard, M; Gliske, S; Greiner, L; Grosnick, D; Gunarathne, D S; Guo, Y; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hamed, A; Han, L-X; Haque, R; Harris, J W; Heppelmann, S; Hirsch, A; Hoffmann, G W; Hofman, D J; Horvat, S; Huang, B; Huang, H Z; Huang, X; Huck, P; Humanic, T J; Igo, G; Jacobs, W W; Jang, H; Judd, E G; Kabana, S; Kalinkin, D; Kang, K; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kesich, A; Khan, Z H; Kikola, D P; Kisel, I; Kisiel, A; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Kosarzewski, L K; Kotchenda, L; Kraishan, A F; Kravtsov, P; Krueger, K; Kulakov, I; Kumar, L; Kycia, R A; Lamont, M A C; Landgraf, J M; Landry, K D; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; LeVine, M J; Li, C; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lisa, M A; Liu, F; Ljubicic, T; Llope, W J; Lomnitz, M; Longacre, R S; Luo, X; Ma, G L; Ma, Y G; Madagodagettige Don, D M M D; Mahapatra, D P; Majka, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Minaev, N G; Mioduszewski, S; Mohanty, B; Mondal, M M; Morozov, D A; Mustafa, M K; Nandi, B K; Nasim, Md; Nayak, T K; Nelson, J M; Nigmatkulov, G; Nogach, L V; Noh, S Y; Novak, J; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Olvitt, D L; Pachr, M; Page, B S; Pal, S K; Pan, Y X; Pandit, Y; Panebratsev, Y; Pawlak, T; Pawlik, B; Pei, H; Perkins, C; Peryt, W; Pile, P; Planinic, M; Pluta, J; Poljak, N; Poniatowska, K; Porter, J; Poskanzer, A M; Pruthi, N K; Przybycien, M; Pujahari, P R; Putschke, J; Qiu, H; Quintero, A; Ramachandran, S; Raniwala, R; Raniwala, S; Ray, R L; Riley, C K; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ross, J F; Roy, A; Ruan, L; Rusnak, J; Rusnakova, O; Sahoo, N R; Sahu, P K; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schmah, A M; Schmidke, W B; Schmitz, N; Seger, J; Seyboth, P; Shah, N; Shahaliev, E; Shanmuganathan, P V; Shao, M; Sharma, B; Shen, W Q; Shi, S S; Shou, Q Y; Sichtermann, E P; Singaraju, R N; Skoby, M J; Smirnov, D; Smirnov, N; Solanki, D; Sorensen, P; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Sumbera, M; Sun, X; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; Szelezniak, M A; Takahashi, J; Tang, A H; Tang, Z; Tarnowsky, T; Thomas, J H; Timmins, A R; Tlusty, D; Tokarev, M; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Turnau, J; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vandenbroucke, M; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Vertesi, R; Videbæk, F; Viyogi, Y P; Vokal, S; Vossen, A; Wada, M; Wang, F; Wang, G; Wang, H; Wang, J S; Wang, X L; Wang, Y; Wang, Y; Webb, G; Webb, J C; Westfall, G D; Wieman, H; Wissink, S W; Witt, R; Wu, Y F; Xiao, Z; Xie, W; Xin, K; Xu, H; Xu, J; Xu, N; Xu, Q H; Xu, Y; Xu, Z; Yan, W; Yang, C; Yang, Y; Yang, Y; Ye, Z; Yepes, P; Yi, L; Yip, K; Yoo, I-K; Yu, N; Zawisza, Y; Zbroszczyk, H; Zha, W; Zhang, J B; Zhang, J L; Zhang, S; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y; Zyzak, M
2015-08-28
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, A_{LL}, in polarized pp collisions at center-of-mass energy sqrt[s]=200 GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. The measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x>0.05.
Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cudd, A. B.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kosarzewski, L. K.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration
2015-08-01
We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, AL L, in polarized p p collisions at center-of-mass energy √{s }=200 GeV . The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC p p data. The measured asymmetries provide evidence at the 3 σ level for positive gluon polarization in the Bjorken-x region x >0.05 .
Gluon Bremsstrahlung in Weakly-Coupled Plasmas
International Nuclear Information System (INIS)
Arnold, Peter
2009-01-01
I report on some theoretical progress concerning the calculation of gluon bremsstrahlung for very high energy particles crossing a weakly-coupled quark-gluon plasma. (i) I advertise that two of the several formalisms used to study this problem, the BDMPS-Zakharov formalism and the AMY formalism (the latter used only for infinite, uniform media), can be made equivalent when appropriately formulated. (ii) A standard technique to simplify calculations is to expand in inverse powers of logarithms ln(E/T). I give an example where such expansions are found to work well for ω/T≥10 where ω is the bremsstrahlung gluon energy. (iii) Finally, I report on perturbative calculations of q.
Gluon bremsstrahlung and elastic scattering of hadrons
International Nuclear Information System (INIS)
Povh, B.
2001-01-01
The differential and the total cross sections in high energy hadron-proton interactions give a beautiful insight in the low Q 2 structure of the nucleon. The cross section is composed of two parts: a large energy independent part corresponding to the interaction of the valence quark with the target without gluon radiation and an energy dependent part caused by gluon bremsstrahlung. The gluons are located at small transverse distances of about 0.3 fm from the valence quarks. The model with two scales, the size of the hadron (R 2 ∼ 1 fm 2 ) and the size of the gluonic cloud (r 0 2 ∼ 0.1 fm 2 ), correctly predicts the total and the differential cross sections and the behaviour of diffractive dissociation in hadronic and deep inelastic events. (orig.)
Constituent gluons and the static quark potential
Energy Technology Data Exchange (ETDEWEB)
Greensite, Jeff [San Francisco State Univ., CA (United States); Szczepaniak, Adam P. [Indiana Univ., Bloomington, IN (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-04-01
We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.
Quark vs Gluon Jet Tagging at ATLAS
Rubbo, Francesco; The ATLAS collaboration
2017-01-01
Distinguishing quark-initiated from gluon-initiated jets is useful for many measurements and searches at the LHC. We present a quark-initiated versus gluon-initiated jet tagger from the ATLAS experiment using the number of reconstructed charged particles inside the jet. The measurement of the charged-particle multiplicity inside jets from Run 1 is used to derive uncertainties on the tagger performance for Run 2. With an efficiency of 60% to select quark-initiated jets, the efficiency to select gluon-initiated jets is between 10 and 20% across a wide range in jet pT up to 1.5 TeV with about an absolute 5% systematic uncertainty on the efficiencies. In addition, we also present preliminary studies on a tagger for the ATLAS experiment using the full radiation pattern inside a jet processed as images in deep neural network classifiers.
Experimental properties of gluon and quark jets from a point source
Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Blobel, V.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David 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.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hoch, M.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; 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, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, 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.
1999-01-01
Gluon jets are identified in hadronic Z0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large transverse momentum, we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29 +- 0.09 +- 0.15 in agreement with the prediction that this ratio should ap...
Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Boeriu, O.; Bock, P.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Buesser, K.; Burckhart, H.J.; Campana, S.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Csilling, A.; Cuffiani, M.; Dado, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Gagnon, P.; Gary, John William; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Horvath, D.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, Laura L.; Kramer, T.; Krieger, P.; von Krogh, J.; Kruger, K.; Kuhl, T.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, J.; Macpherson, A.; Mader, W.; Marcellini, S.; Martin, A.J.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.J.; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Nanjo, H.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Rick, H.; Roney, J.M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schoerner-Sadenius, Thomas; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Sherwood, P.; Siroli, G.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vollmer, C.F.; Vannerem, P.; Vertesi, R.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Warsinsky, M.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija
2004-01-01
We present the first experimental results based on the jet boost algorithm, a technique to select unbiased samples of gluon jets in e+e- annihilations, i.e. gluon jets free of biases introduced by event selection or jet finding criteria. Our results are derived from hadronic Z0 decays observed with the OPAL detector at the LEP e+e- collider at CERN. First, we test the boost algorithm through studies with Herwig Monte Carlo events and find that it provides accurate measurements of the charged particle multiplicity distributions of unbiased gluon jets for jet energies larger than about 5 GeV, and of the jet particle energy spectra (fragmentation functions) for jet energies larger than about 14 GeV. Second, we apply the boost algorithm to our data to derive unbiased measurements of the gluon jet multiplicity distribution for energies between about 5 and 18 GeV, and of the gluon jet fragmentation function at 14 and 18 GeV. In conjunction with our earlier results at 40 GeV, we then test QCD calculations for the en...
Monte Carlo study on the properties of gluon and quark jets
Kun Shi Zhang; Mei Ling Yu; Lian Shou Liu
2002-01-01
The 3-jet events produced in e/sup +/e/sup -/ collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, /sub gluon///sub quark/, has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH, and DELPHI Collaborations, indicating that the method proposed to select gluon and quark jets from ...
Gluon fragmentation in T(1S) decays
International Nuclear Information System (INIS)
Bienlein, J.K.
1983-05-01
In T(1S) decays most observables (sphericity, charged multiplicity, photonic energy fraction, inclusive spectra) can be understood assuming that gluons fragment like quarks. New results from LENA use the (axis-independent) Fox-Wolfram moments for the photonic energy deposition. Continuum reactions show 'standard' Field-Feynman fragmentation. T(1S) decays show a significant difference in the photonic energy topology. It is more isotropic than with the Field-Feynman fragmentation scheme. Gluon fragmentation into isoscalar mesons (a la Peterson and Walsh) is excluded. But if one forces the leading particle to be isoscalar, one gets good agreement with the data. (orig.)
Effects of gluon radiation in hadronic collisions
International Nuclear Information System (INIS)
Gustafson, Goesta.
1989-10-01
In this talk I discuss effects of gluon emission in soft collisions, the so-called 'soft radiation' in the Fritjof model. It is seen e.g. that the pT in the fragmentation regions, the seagull effect, increases with energy in fair agreement with experiments. I also discuss the content of strange and heavier quarks in high-pT gluon jets. Within the dipole scheme for QCD cascades on finds a larger production of heavier quarks than in previous approaches. Qualitative agreement with data is obtained for the K/π ratio and D meson production
Quark-gluon plasma, and strangeness
International Nuclear Information System (INIS)
Rafelski, Johann; Letessier, Jean
2002-01-01
In order to recognize the new form of matter created at RHIC and SPS as the deconfined quark-gluon plasma state (QGP), we need to understand the expected properties of this phase near to the conditions of its formation and disintegration. Thus, we first develop a model of QGP considering the constrains arising from QCD properties and lattice results, and explore its properties. In the second part, we describe the kinetic theory of strangeness production in the QGP phase. We show that gluon fusion dominate and evaluate the degree of equilibration expected at RHIC
Gluon amplitudes as 2 d conformal correlators
Pasterski, Sabrina; Shao, Shu-Heng; Strominger, Andrew
2017-10-01
Recently, spin-one wave functions in four dimensions that are conformal primaries of the Lorentz group S L (2 ,C ) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wave functions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2 d CFT. The Britto-Cachazo-Feng-Witten (BCFW) recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis.
High energy multi-gluon exchange amplitudes
International Nuclear Information System (INIS)
Jaroszewicz, T.
1980-11-01
We examine perturbative high energy n-gluon exchange amplitudes calculated in the Coulomb gauge. If n exceeds the minimum required by the t-channel quantum numbers, such amplitudes are non-leading in lns. We derive a closed system of coupled integral equations for the corresponding two-particle n-gluon vertices, obtained by summing the leading powers of ln(N μ psup(μ)), where psup(μ) is the incident momentum and Nsup(μ) the gauge-defining vector. Our equations are infra-red finite, provided the external particles are colour singlets. (author)
Energy change of a heavy quark in a viscous quark–gluon plasma with fluctuations
International Nuclear Information System (INIS)
Jiang, Bing-feng; Hou, De-fu; Li, Jia-rong
2016-01-01
When a heavy quark travels through the quark–gluon plasma, the polarization and fluctuating chromoelectric fields will be produced simultaneously in the plasma. The drag force due to those fields exerting in return on the moving heavy quark will cause energy change to it. Based on the dielectric functions derived from the viscous chromohydrodynamics, we have studied the collisional energy change of a heavy quark traversing the viscous quark–gluon plasma including fluctuations of chromoelectric field. Numerical results indicate that the chromoelectric field fluctuations lead to an energy gain of the moving heavy quark. Shear viscosity suppresses the fluctuation-induced energy gain and the viscous suppression effect for the charm quark is much more remarkable than that for the bottom quark. While, the fluctuation energy gain is much smaller than the polarization energy loss in magnitude and the net energy change for the heavy quark is at loss.
Analysis of the logarithmic slope of F2 from the Regge gluon density behavior at small x
International Nuclear Information System (INIS)
Boroun, G. R.
2010-01-01
We study the accuracy of the Regge behavior of the gluon distribution function for an approximate relation that is frequently used to extract the logarithmic slopes of the structure function from the gluon distribution at small x. We show that the Regge behavior analysis results are comparable with HERA data and are also better than other methods that expand the gluon density at distinct points of expansion. We also show that for Q 2 = 22.4 GeV 2 , the x dependence of the data is well described by gluon shadowing corrections to the GLR-MQ equation. The resulting analytic expression allows us to predict the logarithmic derivative ∂F 2 (x, Q 2 )/∂lnQ 2 and to compare the results with the H1 data and a QCD analysis fit with the MRST parameterization input.
Squeezed colour states in gluon jet
Kilin, S. YA.; Kuvshinov, V. I.; Firago, S. A.
1993-01-01
The possibility of the formation of squeezed states of gluon fields in quantum chromodynamics due to nonlinear nonperturbative self interaction during jet evolution in the process of e(+)e(-) annihilation into hadrons, which are analogous to the quantum photon squeezed states in quantum electrodynamics, is demonstrated. Additionally, the squeezing parameters are calculated.
Gluon gas viscosity in nonperturbative region
International Nuclear Information System (INIS)
Il'in, S.V.; Mogilevskij, O.A.; Smolyanskij, S.A.; Zinov'ev, G.M.
1992-01-01
Using the Green-Kubo-type formulae and the cutoff model motivated by Monte Carlo lattice gluodynamics simulations we find the temperature behaviour of shear viscosity of gluon gas in the region of deconfinement phase transition. 22 refs.; 1 fig. (author)
Electromagnetic signals of quark gluon plasma
Indian Academy of Sciences (India)
Successive equilibration of quark degrees of freedom and its effects on electromagnetic signals of quark gluon plasma are discussed. The effects of the variation of vector meson masses and decay widths on photon production from hot strongly interacting matter formed after Pb + Pb and S + Au collisions at CERN SPS ...
Inflating metastable quark-gluon plasma universe
International Nuclear Information System (INIS)
Jenkovszky, L.L.; Kaempfer, B.; Sysoev, V.M.
1990-01-01
We show within the Friedmann model with the equation of state p(T)=aT 4 -AT that our universe has expanded exponentially when it was in a metastable quark-gluon plasma state. The scale factor during that epoch increased by many orders of magnitude. 13 refs.; 5 figs
Bosonization with inclusion of the gluon condensate
International Nuclear Information System (INIS)
Ebert, D.; Volkov, M.K.
1994-01-01
The effects of the gluon condensate on the quark condensate and on masses and coupling constants of composite mesons are discussed within a QCD-motivated Nambu-Jona-Lasinio model for zero temperature as well as for the case of finite temperature and baryon number density. (orig.)
Quark-gluon plasma (Selected Topics)
International Nuclear Information System (INIS)
Zakharov, V. I.
2012-01-01
Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.
Exploring Quarks, Gluons and the Higgs Boson
Johansson, K. Erik
2013-01-01
With real particle collision data available on the web, the amazing dynamics of the fundamental particles of the standard model can be explored in classrooms. Complementing the events from the ATLAS experiment with animations of the fundamental processes on the quark and gluon level makes it possible to better understand the invisible world of…
Soft gluon contributions to hard processes
International Nuclear Information System (INIS)
Ciafaloni, M.
1981-10-01
The main concern of this paper is in trying to elucidate the origin of large QCD perturbative corrections and explain how to deal with them to all orders. They come essentially from the phase space regions close to the kinematical boundary of a hard process, in which one or many gluons become soft
Searching for the quarks and gluons plasma
International Nuclear Information System (INIS)
Gerschel, C.; Kluberg, L.
1989-01-01
Some investigations involving quark matter, at CERN, are discussed. The CERN available oxygen and sulfur beams, with energy about 200 GeV/nuclei, allow the obtention of high energy densities, never reached before. The possibilities of investigating (at CERN) the quarks and gluons plasma are considered. The first and unexpected results obtained from the NA38 experiment are overviewed [fr
Gluon 2- and 3-Point Correlation Functions on the Lattice
Parrinello, Claudio
1993-01-01
I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex.
2- and 3-point gluon correlation functions on the lattice
Energy Technology Data Exchange (ETDEWEB)
Parrinello, C. (Dept. of Physics, Univ. of Edinburgh (United Kingdom))
1994-04-01
I present some preliminary results, obtained in collaboration with C. Bernard and A. Soni, for the lattice evaluation of 2- and 3-point gluon correlation functions in momentum space, with emphasis on the amputated 3-gluon vertex function. The final goal of this approach is the study of the running QCD coupling constant as defined from the amputated 3-gluon vertex. (orig.)
Advantages of polarization experiments at RHIC
International Nuclear Information System (INIS)
Underwood, D.G.
1991-01-01
We point out various spin experiments that could be done if the polarized beam option is pursued at RHIC. The advantages of RHIC for investigating several current and future physics problems are discussed. In particular, the gluon spin dependent structure function of the nucleon could be measured cleanly and systematically. Relevant experience developed in conjunction with the Fermilab Polarized Beam program is also presented
The anomalous contribution to polarized leptoproduction
International Nuclear Information System (INIS)
Altarelli, G.; Ross, G.
1988-01-01
We show that, due to the anomaly, the gluon contribution to the first moment of the polarized proton structure function, as measured in deep inelastic scattering, is not suppressed by a power of the strong coupling evaluated at a large scale. As a result, the EMC result for the first moment of polarized proton electroproduction is consistent with a large quark spin component. (orig.)
Forward gluon production in hadron-hadron scattering with Pomeron loops
Energy Technology Data Exchange (ETDEWEB)
Iancu, E. [CEA Saclay, Service de Physique Th orique (DSM/SPhT), Unite de recherche associ e au CNRS (URA D2306), 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Marquet, C.; Soyez, G. [CEA Saclay, Service de Physique Th orique (DSM/SPhT), Unite de recherche associ e au CNRS (URA D2306), 91 - Gif-sur-Yvette (France). Direction des Sciences de la Matiere; Liege Univ., Fundamental Theoretical Physics Group (Belgium)
2006-07-01
We discuss new physical phenomena expected in particle production in hadron-hadron collisions at high energy, as a consequence of Pomerons loop effects in the evolution equations for the Color Glass Condensate. We focus on gluon production in asymmetric, 'dilute-dense', collisions: a dilute projectile scatters off a dense hadronic target, whose gluon distribution is highly evolved. This situation is representative for particle production in proton-proton collisions at forward rapidities (say, at LHC) and admits a dipole factorization similar to that of deep inelastic scattering (DIS). We show that at sufficiently large forward rapidities, where the Pomerons loop effects become important in the evolution of the target wavefunction, gluon production is dominated by 'black spots' (saturated gluon configurations) up to very large values of the transverse momentum, well above the average saturation momentum in the target. In this regime, the produced gluon spectrum exhibits diffusive scaling, so like DIS at sufficiently high energy. (authors)
Deciphering the quark-gluon structure of the photon in electronγ collisions
International Nuclear Information System (INIS)
Eboli, O.J.P.; Gonzalez-Garcia, M.C.; Halzen, F.; Novaes, S.F.
1992-11-01
The capability of an electron γ collider to unravel the hadronic content of the photon is investigated. The experimental problem for probing the gluonic structure of the photon is that small-x triggers overwhelmingly select soft photons rather than soft gluons in hard photons. It is showed that the problem can be finessed in experiments where laser back-scattering is used to prepare a source of very hard photons. It is illustrated their power for studying the parton distribution of the photon and, specifically, for separating the quark and gluon components in events where dijets, jet-γ pairs, and heavy quark pairs are produced. (author)
Diffractive J/ψ photoproduction as a probe of the gluon density
International Nuclear Information System (INIS)
Ryskin, M.G.; Roberts, R.G.; Martin, A.D.; Levin, E.M.
1995-11-01
We use perturbative QCD beyond the leading Ln Q 2 approximation, to show how measurements of diffractive J/ψ production at HERA can provide a sensitive probe of the gluon density of the proton at small values of Bjorken x. We estimate both the effect of the relativistic motion of the c and c within the J/ψ and of the rescattering of the cc quark pair on the proton. We find that the available data for diffractive J/ψ photoproduction can discriminate between the gluon distributions of the most recent sets of partons. (author). 18 refs., 9 figs., 1 tab
The Mellin transform technique for the extraction of the gluon density
International Nuclear Information System (INIS)
Graudenz, D.
1995-06-01
A new method is presented to determine the gluon density in the proton from jet production in deeply inelastic scattering. By using the technique of Mellin transforms not only for the solution of the scale evolution equation of the parton densities but also for the evaluation of scattering cross sections, the gluon density can be extracted in next-to-leading order QCD. The method described in this paper is, however, more general, and can be used in situations where a repeated fast numerical evaluation of scattering cross sections for varying parton distribution functions is required. (orig.)
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
Brodsky, S.J.
1990-08-01
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs
Bound-state quark and gluon contributions to structure functions in QCD
International Nuclear Information System (INIS)
Brodsky, S.J.
1991-01-01
One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: 'intrinsic' contributions, which are due to the direct scattering on the bound-state constituents, and 'extrinsic' contributions, which are derived from particles created in the collision. In this talk, I discuss several aspects of deep inealstic structure functions in which the bound-state structure of the proton plays a crucial role: (1) the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; (2) the separation of the quark structure function of the proton into intrinsic 'bound-valence' and extrinsic 'non-valence' components which takes into account the Pauli principle; (3) the properties and identification of intrinsic heavy quark structure functions; and (4) a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. (orig.)
Directory of Open Access Journals (Sweden)
S.M. Moosavi Nejad
2016-04-01
Full Text Available Basically, the energy distribution of bottom-flavored hadrons produced through polarized top quark decays t(↑→W++b(→Xb, is governed by the unpolarized rate and the polar and the azimuthal correlation functions which are related to the density matrix elements of the decay t(↑→bW+. Here we present, for the first time, the analytical expressions for the O(αs radiative corrections to the differential azimuthal decay rates of the partonic process t(↑→b+W+ in two helicity systems, which are needed to study the azimuthal distribution of the energy spectrum of the hadrons produced in polarized top decays. These spin-momentum correlations between the top quark spin and its decay product momenta will allow the detailed studies of the top decay mechanism. Our predictions of the hadron energy distributions also enable us to deepen our knowledge of the hadronization process and to test the universality and scaling violations of the bottom-flavored meson fragmentation functions.
The impact of PDF and alphas uncertainties on Higgs Production in gluon fusion at hadron colliders
Demartin, Federico; Forte, Stefano; Mariani, Elisa; Rojo, Juan; Vicini, Alessandro
2010-01-01
We present a systematic study of uncertainties due to parton distributions and the strong coupling on the gluon-fusion production cross section of the Standard Model Higgs at the Tevatron and LHC colliders. We compare procedures and results when three recent sets of PDFs are used, CTEQ6.6, MSTW08
A first unbiased global determination of polarized PDFs and their uncertainties
International Nuclear Information System (INIS)
Nocera, Emanuele R.; Ball, Richard D.; Forte, Stefano; Ridolfi, Giovanni; Rojo, Juan
2014-01-01
We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the previous NNPDFpol1.0 PDF set, are supplemented with the most recent polarized hadron collider data for inclusive jet and W boson production from the STAR and PHENIX experiments at RHIC, and with open-charm production data from the COMPASS experiment, thereby allowing for a separate determination of the polarized quark and antiquark PDFs, and an improved determination of the medium- and large-x polarized gluon PDF. We study the phenomenological implications of the NNPDFpol1.1 set, and we provide predictions for the longitudinal double-spin asymmetry for semi-inclusive pion production at RHIC
A first unbiased global determination of polarized PDFs and their uncertainties
Directory of Open Access Journals (Sweden)
Emanuele R. Nocera
2014-10-01
Full Text Available We present a first global determination of spin-dependent parton distribution functions (PDFs and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the previous NNPDFpol1.0 PDF set, are supplemented with the most recent polarized hadron collider data for inclusive jet and W boson production from the STAR and PHENIX experiments at RHIC, and with open-charm production data from the COMPASS experiment, thereby allowing for a separate determination of the polarized quark and antiquark PDFs, and an improved determination of the medium- and large-x polarized gluon PDF. We study the phenomenological implications of the NNPDFpol1.1 set, and we provide predictions for the longitudinal double-spin asymmetry for semi-inclusive pion production at RHIC.
A first unbiased global determination of polarized PDFs and their uncertainties
Energy Technology Data Exchange (ETDEWEB)
Nocera, Emanuele R. [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ball, Richard D. [Higgs Centre, University of Edinburgh, JCMB, KB, Mayfield Rd, Edinburgh EH9 3JZ, Scotland (United Kingdom); Forte, Stefano [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Genova (Italy); Rojo, Juan [PH Department, TH Unit, CERN, CH-1211 Geneva 23 (Switzerland); Rudolf Peierls Centre for Theoretical Physics, 1 Keble Road, University of Oxford, OX1 3NP Oxford (United Kingdom)
2014-10-15
We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the previous NNPDFpol1.0 PDF set, are supplemented with the most recent polarized hadron collider data for inclusive jet and W boson production from the STAR and PHENIX experiments at RHIC, and with open-charm production data from the COMPASS experiment, thereby allowing for a separate determination of the polarized quark and antiquark PDFs, and an improved determination of the medium- and large-x polarized gluon PDF. We study the phenomenological implications of the NNPDFpol1.1 set, and we provide predictions for the longitudinal double-spin asymmetry for semi-inclusive pion production at RHIC.
A first unbiased global determination of polarized PDFs and their uncertainties
Nocera, Emanuele R.; Forte, Stefano; Ridolfi, Giovanni; Rojo, Juan
2014-01-01
We present a first global determination of spin-dependent parton distribution functions (PDFs) and their uncertainties using the NNPDF methodology: NNPDFpol1.1. Longitudinally polarized deep-inelastic scattering data, already used for the previous NNPDFpol1.0 PDF set, are supplemented with the most recent polarized hadron collider data for inclusive jet and $W$ boson production from the STAR and PHENIX experiments at RHIC, and with open-charm production data from the COMPASS experiment, thereby allowing for a separate determination of the polarized quark and anti-quark PDFs, and an improved determination of the medium- and large-$x$ polarized gluon PDF. We study the phenomenological implications of the NNPDFpol1.1 set, and we provide predictions for the longitudinal double-spin asymmetry for semi-inclusive pion production at RHIC.
Experimental properties of gluon and quark jets from a point source
International Nuclear Information System (INIS)
Abbiendi, G.; Ackerstaff, K.; Alexander, G.
1999-01-01
Gluon jets are identified in hadronic Z 0 decays as all the particles in a hemisphere opposite to a hemisphere containing two tagged quark jets. Gluon jets defined in this manner are equivalent to gluon jets produced from a color singlet point source and thus correspond to the definition employed for most theoretical calculations. In a separate stage of the analysis, we select quark jets in a manner to correspond to calculations, as the particles in hemispheres of flavor tagged light quark (uds) events. We present the distributions of rapidity, scaled energy, the logarithm of the momentum, and transverse momentum with respect to the jet axes, for charged particles in these gluon and quark jets. We also examine the charged particle multiplicity distributions of the jets in restricted intervals of rapidity. For soft particles at large p T , we observe the charged particle multiplicity ratio of gluon to quark jets to be 2.29±0.09(stat.)±0.15(syst.), in agreement with the prediction that this ratio should approximately equal the ratio of QCD color factors, C A /C F =2.25. The intervals used to define soft particles and large p T for this result, p T < 3.0 GeV/c, are motivated by the predictions of the Herwig Monte Carlo multihadronic event generator. Additionally, our gluon jet data allow a sensitive test of the phenomenon of non-leading QCD terms known as color reconnection. We test the model of color reconnection implemented in the Ariadne Monte Carlo multihadronic event generator and find it to be disfavored by our data. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Chandra, Vinod [Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat (India); Sreekanth, V. [Indian Institute of Science, Centre for High Energy Physics, Bangalore (India)
2017-06-15
Momentum anisotropy present during the hydrodynamic evolution of the Quark-Gluon Plasma (QGP) in RHIC may lead to the chromo-Weibel instability and turbulent chromo-fields.The dynamics of the quark and gluon momentum distributions in this case is governed by an effective diffusive Vlasov equation (linearized). The solution of this linearized transport equation for the modified momentum distribution functions lead to the mathematical form of non-equilibrium momentum distribution functions of quarks/antiquarks and gluons. The modifications to these distributions encode the physics of turbulent color fields and momentum anisotropy. In the present manuscript, we employ these distribution functions to estimate the thermal dilepton production rate in the QGP medium. The production rate is seen to have appreciable sensitivity to the strength of the anisotropy. (orig.)
International Nuclear Information System (INIS)
Gonzalo, A B; Rosa, M I de la; Perez, C; Mar, S; Gruetzmacher, K
2004-01-01
We report on quantitative measurements of ground-state atomic hydrogen densities in a stationary plasma far off thermodynamic equilibrium, generated in a hollow cathode discharge, by two-photon polarization spectroscopy via the 1S-2S transition. Absolute densities are obtained using a well established calibration method based on the non-resonant two-photon polarization signal of xenon gas at room temperature, which serves as the reference at the wavelength of the hydrogen transition. This study is dedicated to demonstrating the capability of two-photon polarization spectroscopy close to the detection limit. Therefore, it requires single-longitudinal mode UV-laser radiation provided by an advanced UV-laser spectrometer
Soft gluon approach for diffractive photoproduction of J/ψ
International Nuclear Information System (INIS)
Ma, J.P.; Xu Jiasheng
2002-01-01
We study diffractive photoproduction of J/ψ by taking the charm quark as a heavy quark. A description of nonperturbative effect related to J/ψ can be made by using NRQCD. In the forward region of the kinematics, the interaction between the cc-bar-pair and the initial hadron is due to exchange of soft gluons. The effect of the exchange can be studied by using the expansion in the inverse of the quark mass m c . At the leading order we find that the nonperturbative effect related to the initial hadron is represented by a matrix element of field strength operators, which are separated in the moving direction of J/ψ in the spacetime. The S-matrix element is then obtained without using perturbative QCD and the results are not based on any model. Corrections to the results can be systematically added. Keeping the dominant contribution of the S-matrix element in the large energy limit we find that the imaginary part of the S-matrix element is related to the gluon distribution for x→0 with a reasonable assumption, the real part can be obtained with another approximation or with dispersion relation. Our approach is different than previous approaches and also our results are different than those in these approaches. The differences are discussed in detail. A comparison with experiment is also made and a qualitative agreement is found. (author)
Soft gluon resummation formulae for hard proton processes in QCD
International Nuclear Information System (INIS)
Craigie, N.S.; Jones, H.F.
1980-01-01
We briefly review the treatment of leading logarithmic behaviour of the parton distributions in QCD within the Bethe-Salpeter framework by analysing directly parton hadron Green functions in the limit of parton four-momentum k 2 → - infinitely in a special light-like gauge involving a spectator vector. This technique allows us to derive the factorization of parton probabilities in leading logarithmic order in QCD in the various inclusive processes involving a single short-distance scale. The proof requires us to show that the use of planar gauges eta = psub(A) + psub(B) + ..., where psub(A), psub(B)... are the observed hadron momenta, reduces to choosing the appropriate light-like gauge for each hadron-parton BS channel, after demonstrating a Bloch-Nordsieck cancellation of the real and virtual soft left-over gluons. In the case where two large momentum scales appear, by restricting the transverse phase space into which the gluons are radiated, we derive the double logarithmic eikonal renormalization of the hard scattering formula of the type proposed recently by Parisi and Petronzio. (orig.)
Higgs production in gluon fusion beyond NNLO
Energy Technology Data Exchange (ETDEWEB)
Ball, Richard D. [Edinburgh Univ. (United Kingdom). Tait Inst.; Bonvini, Marco [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Forte, Stefano [Milano Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Milano (Italy); Marzani, Simone [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Ridolfi, Giovanni [Genova Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Genova (Italy)
2013-03-15
We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N{sup 3}LO) in {alpha}{sub s} with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N{sup 3}LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.
Higgs production in gluon fusion beyond NNLO
International Nuclear Information System (INIS)
Ball, Richard D.; Bonvini, Marco; Forte, Stefano; Marzani, Simone; Ridolfi, Giovanni
2013-01-01
We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N 3 LO) in α s with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N 3 LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result
Higgs production in gluon fusion beyond NNLO
Energy Technology Data Exchange (ETDEWEB)
Ball, Richard D. [Tait Institute, University of Edinburgh, Edinburgh EH9 3JZ, Scotland (United Kingdom); Bonvini, Marco [Deutsches Elektronen-Synchroton, DESY, Notkestraße 85, D-22603 Hamburg (Germany); Forte, Stefano, E-mail: forte@mi.infn.it [Dipartimento di Fisica, Università di Milano and INFN, Sezione di Milano, Via Celoria 16, I-20133 Milano (Italy); Marzani, Simone [Institute for Particle Physics Phenomenology, Durham University, Durham DH1 3LE, England (United Kingdom); Ridolfi, Giovanni [Dipartimento di Fisica, Università di Genova and INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy)
2013-09-21
We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N{sup 3}LO) in α{sub s} with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analyticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N{sup 3}LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.
Higgs production in gluon fusion beyond NNLO
International Nuclear Information System (INIS)
Ball, Richard D.; Forte, Stefano; Marzani, Simone
2013-03-01
We construct an approximate expression for the cross section for Higgs production in gluon fusion at next-to-next-to-next-to-leading order (N 3 LO) in α s with finite top mass. We argue that an accurate approximation can be constructed by exploiting the analiticity of the Mellin space cross section, and the information on its singularity structure coming from large N (soft gluon, Sudakov) and small N (high energy, BFKL) all order resummation. We support our argument with an explicit comparison of the approximate and the exact expressions up to the highest (NNLO) order at which the latter are available. We find that the approximate N 3 LO result amounts to a correction of 17% to the NNLO QCD cross section for production of a 125 GeV Higgs at the LHC (8 TeV), larger than previously estimated, and it significantly reduces the scale dependence of the NNLO result.
The actin cytoskeleton may control the polar distribution of an auxin transport protein
Muday, G. K.; Hu, S.; Brady, S. R.; Davies, E. (Principal Investigator)
2000-01-01
The gravitropic bending of plants has long been linked to the changes in the transport of the plant hormone auxin. To understand the mechanism by which gravity alters auxin movement, it is critical to know how polar auxin transport is initially established. In shoots, polar auxin transport is basipetal (i.e., from the shoot apex toward the base). It is driven by the basal localization of the auxin efflux carrier complex. One mechanism for localizing this efflux carrier complex to the basal membrane may be through attachment to the actin cytoskeleton. The efflux carrier protein complex is believed to consist of several polypeptides, including a regulatory subunit that binds auxin transport inhibitors, such as naphthylphthalamic acid (NPA). Several lines of experimentation have been used to determine if the NPA binding protein interacts with actin filaments. The NPA binding protein has been shown to partition with the actin cytoskeleton during detergent extraction. Agents that specifically alter the polymerization state of the actin cytoskeleton change the amount of NPA binding protein and actin recovered in these cytoskeletal pellets. Actin-affinity columns were prepared with polymers of actin purified from zucchini hypocotyl tissue. NPA binding activity was eluted in a single peak from the actin filament column. Cytochalasin D, which fragments the actin cytoskeleton, was shown to reduce polar auxin transport in zucchini hypocotyls. The interaction of the NPA binding protein with the actin cytoskeleton may localize it in one plane of the plasma membrane, and thereby control the polarity of auxin transport.
Prokeš, K.; de Visser, A.; Huang, Y.K.; Fåk, B.; Ressouche, E.
2010-01-01
We report a polarized neutron-diffraction study conducted to reveal the nature of the weak ferromagnetic moment in the superconducting ferromagnet UCoGe. We find that the ordered moment in the normal phase in low magnetic fields (B∥c) is predominantly located at the U atom and has a magnitude of
The structure of gluon radiation in QCD
International Nuclear Information System (INIS)
Parke, S.; Mangano, M.
1989-08-01
For massless QCD the hard scattering amplitudes are naturally written in terms of the dual color expansion. here I present this expansion for purely gluonic processes and processes involving quark-antiquark pairs and gluons. The properties of the sub-amplitudes as well as explicit algebraic expressions are given for a number of these processes. Also, I demonstrate how to recover massless QED amplitudes from the dual expansion of massless QCD. 16 refs., 3 figs., 1 tab
Effective gluon interactions from superstring disk amplitudes
Energy Technology Data Exchange (ETDEWEB)
Oprisa, D.
2006-05-15
In this thesis an efficient method for the calculation of the N-point tree-level string amplitudes is presented. Furthermore it is shown that the six-gluon open-superstring disk amplitude can be expressed by a basis of six triple hypergeometric functions, which encode the full {alpha}' dependence. In this connection material for obtaining the {alpha}' expansion of these functions is derived. Hereby many Euler-Zagier sums are calculated including multiple harmonic series. (HSI)
Gluon saturation beyond (naive) leading logs
Energy Technology Data Exchange (ETDEWEB)
Beuf, Guillaume
2014-12-15
An improved version of the Balitsky–Kovchegov equation is presented, with a consistent treatment of kinematics. That improvement allows to resum the most severe of the large higher order corrections which plague the conventional versions of high-energy evolution equations, with approximate kinematics. This result represents a further step towards having high-energy QCD scattering processes under control beyond strict Leading Logarithmic accuracy and with gluon saturation effects.
The gluon propagator in momentum space
Energy Technology Data Exchange (ETDEWEB)
Bernard, C. [Washington Univ., St. Louis, MO (United States). Dept. of Physics; Parrinello, C. [New York Univ., NY (United States). Dept. of Physics]|[Brookhaven National Lab., Upton, NY (United States); Soni, A. [Brookhaven National Lab., Upton, NY (United States)
1992-12-31
We consider quenched QCD on a 16{sup 3}{times}40 lattice at {beta}=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others.
The gluon propagator in momentum space
Energy Technology Data Exchange (ETDEWEB)
Bernard, C. (Washington Univ., St. Louis, MO (United States). Dept. of Physics); Parrinello, C. (New York Univ., NY (United States). Dept. of Physics Brookhaven National Lab., Upton, NY (United States)); Soni, A. (Brookhaven National Lab., Upton, NY (United States))
1992-01-01
We consider quenched QCD on a 16[sup 3][times]40 lattice at [beta]=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others.
The gluon propagator in momentum space
Energy Technology Data Exchange (ETDEWEB)
Bernard, C. (Dept. of Physics, Washington Univ., St. Louis, MO (United States)); Parrinello, C. (Physics Dept., New York Univ., NY (United States) Physics Dept., Brookhaven National Lab., Upton, NY (United States)); Soni, A. (Physics Dept., Brookhaven National Lab., Upton, NY (United States))
1993-03-01
We consider quenched QCD on a 16[sup 3] x 40 lattice at [beta] = 6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others. (orig.)
Physics of the quark-gluon plasma
International Nuclear Information System (INIS)
Polonyi, J.; Institut National de Physique Nucleaire et de Physique des Particules; Lorand Eoetvoes Univ., Budapest
1995-01-01
Some features of the high temperature gluonic matter, such as the breakdown of the fundamental group symmetry by the kinetic energy, the screening of test quarks by some unusual gluon states and the explanation of the absence of isolated quarks in the vacuum without the help of infinities are presented in this talk. Special attention is paid to separate the dynamical input inferred from the numerical results of lattice gauge theory from the kinematics. (author)
The structure of gluon radiation in QCD
International Nuclear Information System (INIS)
Parke, S.; Mangano, M.
1990-01-01
For massless QCD the hard scattering amplitudes are naturally written in terms of the dual color expansion. Here I present this expansion for purely gluonic processes and processes involving quark-antiquark pairs and gluons. The properties of the sub-amplitudes as well as explicit algebraic expressions are given for a number of these processess. Finally, I demonstrate how to recover massless QED amplitudes from the dual expansion of massless QCD
Soft gluon emission in coloured quark scattering
International Nuclear Information System (INIS)
Frenkel, J.; Meuldemans, R.; Mohammad, I.; Taylor, J.C.
1977-01-01
In order to investigate the infrared behaviour of non-Abelian gauge theories the leading logarithms in the bremsstrahlung of two soft gluons by a coloured quark scattered in an external colourless potential have been calculated. In the calculations only diagrams containing exactly one Yang-Mills vertex have been used alongside with the dimensional infrared regularization. An expression is obtained exhibiting a crucial difference between QCD and QED
Effective gluon interactions from superstring disk amplitudes
International Nuclear Information System (INIS)
Oprisa, D.
2006-05-01
In this thesis an efficient method for the calculation of the N-point tree-level string amplitudes is presented. Furthermore it is shown that the six-gluon open-superstring disk amplitude can be expressed by a basis of six triple hypergeometric functions, which encode the full α' dependence. In this connection material for obtaining the α' expansion of these functions is derived. Hereby many Euler-Zagier sums are calculated including multiple harmonic series. (HSI)
Hadronization of the quark-gluon plasma
International Nuclear Information System (INIS)
Mueller, B.; Sano, M.; Sato, H.; Schaefer, A.
1986-11-01
We construct a model for hadronization of the quark-gluon plasma, based on the relativistic coalescence model. We relate the coalescence amplitude to the one-particle Wigner function for quarks in the plasma. The relation between the Wigner function and the nucleon structure function is pointed out. We derive explicit expressions for the production of mesons and baryons in the framework of the relativistic harmonic oscillator model of hadronic structure. (author)
Signatures of quark-gluon plasma production
International Nuclear Information System (INIS)
Gyulassy, M.
1985-01-01
A critical analysis of a variety of proposed signatures for quark-gluon formation in ultrarelativistic nuclear collisions is given. The authors emphasize that longitudinal growth rather than the nuclear radius controls the time scales for expansion. The author pointed out the qualitative difference of the evolution of the plasma produced in the stopping regime E approx. 10 GeV/nucleon and the scaling regime E > 1 TeV/nucleon. This difference reflects itself in the the rmal profile function
The gluon propagator in momentum space
International Nuclear Information System (INIS)
Bernard, C.; Soni, A.
1992-01-01
We consider quenched QCD on a 16 3 x40 lattice at β=6.0. We give preliminary numerical results for the lattice gluon propagator evaluated both in coordinate and momentum space. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others
Quark-gluon mixing in scalar mesons
International Nuclear Information System (INIS)
Eremyan, Sh.S.; Nazaryan, A.E.
1986-01-01
Scalar mesons are considered within the quark-gluon mixing model. It is shown that there exists decouplet of scalar particles consisting of S* (975), ε (1400), S*' (1700), δ (980) and κ (1350) resonances. It has turned out that the long ago known S* (975)-resonance is a nearly pure glouball. A good description of all available experimental data on scalar meson decays is obtained
Zhu, P. Y.
1991-01-01
The effective-medium approximation is applied to investigate scattering from a half-space of randomly and densely distributed discrete scatterers. Starting from vector wave equations, an approximation, called effective-medium Born approximation, a particular way, treating Green's functions, and special coordinates, of which the origin is set at the field point, are used to calculate the bistatic- and back-scatterings. An analytic solution of backscattering with closed form is obtained and it shows a depolarization effect. The theoretical results are in good agreement with the experimental measurements in the cases of snow, multi- and first-year sea-ice. The root product ratio of polarization to depolarization in backscattering is equal to 8; this result constitutes a law about polarized scattering phenomena in the nature.
Bhandari, Anak; Hamre, Børge; Frette, Øvynd; Zhao, Lu; Stamnes, Jakob J; Kildemo, Morten
2011-06-01
A Lambert surface would appear equally bright from all observation directions regardless of the illumination direction. However, the reflection from a randomly scattering object generally has directional variation, which can be described in terms of the bidirectional reflectance distribution function (BRDF). We measured the BRDF of a Spectralon white reflectance standard for incoherent illumination at 405 and 680 nm with unpolarized and plane-polarized light from different directions of incidence. Our measurements show deviations of the BRDF for the Spectralon white reflectance standard from that of a Lambertian reflector that depend both on the angle of incidence and the polarization states of the incident light and detected light. The non-Lambertian reflection characteristics were found to increase more toward the direction of specular reflection as the angle of incidence gets larger.
The hadron to quark/gluon transition
International Nuclear Information System (INIS)
Brown, G.E.; Bethe, H.A.; Pizzochero, P.M.
1991-01-01
In this paper we are concerned with the hadron to quark/gluon transition. We describe the equilibrium states of hadronic matter by a Hagedorn spectrum; introducing scaling masses, as dictated by the restoration of chiral invariance with increasing temperature, we show that in the chiral SU(2) f limit there is a maximum hadron temperature (T H ) max ≅ 128 MeV. Since the quark/gluon perturbative phase involves restoration of conformal invariance, we take the bag constant to be the conformal anomaly, i.e. the gluon condensate. The stability condition P QG > 0 for the pressure requires that there is a minimum temperature; we find (T QG ) min ≅ 172 MeV for SU(2) f . According to the simple Hagedorn model, there appears to be a region of temperature between (T H ) max and (T QG ) min in which no admissible equilibrium states exist. Since the two phases cannot exist at a common temperature, in this model there is no QCD phase transition. (orig.)
Quark and gluon condensate in vacuum
International Nuclear Information System (INIS)
Vajnshtejn, A.I.; Zakharov, V.I.; Shifman, M.A.
1979-01-01
The mechanism of quark confinement has been reviewed. The fact that coloured particles in a free state cannot be observed is connected with specific properties of vacuum in quantum chromodynamics. The basic hypothesis consists in the existence of vacuum fields, quark and gluon condensates, which affect the coloured objects. The vacuum transparent relative to noncharged ''white'' states serves as a source of the force acting upon the coloured particles. It has been a sucess to examine strictly the action of the vacuum fields on quarks when the distance between them is relatively small and the force of the vacuum fields on quarks is relatively small too. It is shown that the interaction with the vacuum fields manifests itself earlier than the forces connected with the gluon exchange do. It is assumed that the vacuum condensate of quarks and gluons and its relation to properties of resonances and to the bag model exist in reality. The dispersion sum rules are used for calculating masses and lepton widths of resonances
Polarization phenomena in quantum chromodynamics
International Nuclear Information System (INIS)
Brodsky, S.J.
1994-03-01
The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and non-perturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g A on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x bj ; (b) consequences of the principle of hadron helicity retention in high x F inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. He also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A NN observed in large angle proton-proton scattering, the anomalously large ρπ branching ratio of the J/ψ, and the rapidly changing polarization dependence of both J/ψ and continuum lepton pair hadroproduction observed at large x F . The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron
Polarization phenomena in quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Brodsky, S.J. [Stanford Univ., CA (United States)
1994-12-01
The author discusses a number of interrelated hadronic spin effects which test fundamental features of perturbative and nonperturbative QCD. For example, the anomalous magnetic moment of the proton and the axial coupling g{sub A} on the nucleon are shown to be related to each other for fixed proton radius, independent of the form of the underlying three-quark relativistic quark wavefunction. The renormalization scale and scheme ambiguities for the radiative corrections to the Bjorken sum rule for the polarized structure functions can be eliminated by using commensurate scale relations with other observables. Other examples include (a) new constraints on the shape and normalization of the polarized quark and gluon structure functions of the proton at large and small x{sub bj}; (b) consequences of the principle of hadron retention in high x{sub F} inclusive reactions; (c) applications of hadron helicity conservation to high momentum transfer exclusive reactions; and (d) the dependence of nuclear structure functions and shadowing on virtual photon polarization. The author also discusses the implications of a number of measurements which are in striking conflict with leading-twist perturbative QCD predictions, such as the extraordinarily large spin correlation A{sub NN} observed in large angle proton-proton scattering, the anomalously large {rho}{pi} branching ratio of the J/{psi}, and the rapidly changing polarization dependence of both J/{psi} and continuum lepton pair hadroproduction observed at large x{sub F}. The azimuthal angular dependence of the Drell-Yan process is shown to be highly sensitive to the projectile distribution amplitude, the fundamental valence light-cone wavefunction of the hadron.
Water on Mars: Inventory, distribution, and possible sources of polar ice
Clifford, S. M.
1992-01-01
Theoretical considerations and various lines of morphologic evidence suggest that, in addition to the normal seasonal and climatic exchange of H2O that occurs between the Martian polar caps, atmosphere, and mid to high latitude regolith, large volumes of water have been introduced into the planet's long term hydrologic cycle by the sublimation of equatorial ground ice, impacts, catastrophic flooding, and volcanism. Under the climatic conditions that are thought to have prevailed on Mars throughout the past 3 to 4 b.y., much of this water is expected to have been cold trapped at the poles. The amount of polar ice contributed by each of the planet's potential crustal sources is discussed and estimated. The final analysis suggests that only 5 to 15 pct. of this potential inventory is now in residence at the poles.
Uchiyama, Kazuharu; Nishikawa, Naoki; Nakagomi, Ryo; Kobayashi, Kiyoshi; Hori, Hirokazu
2018-02-01
To design optoelectronic functionalities in nanometer scale based on interactions of electronic system with optical near-fields, it is essential to evaluate the relationship between optical near-fields and their sources. Several theoretical studies have been performed, so far, to analyze such complex relationship to design the interaction fields of several specific scales. In this study, we have performed detailed and high-precision measurements of optical near-field structures woven by a large number of independent polarizations generated in the gold nanorods array under laser light irradiation at the resonant frequency. We have accumulated the multi-layered data of optical near-field imaging at different heights above the planar surface with the resolution of several nm by a STM-assisted scanning near-field optical microscope. Based on these data, we have performed an inverse calculation to estimate the position, direction, and strength of the local polarization buried under the flat surface of the sample. As a result of the inverse operation, we have confirmed that the complexities in the nanometer scale optical near-fields could be reconstructed by combinations of induced polarization in each gold nanorod. We have demonstrated the hierarchical properties of optical near-fields based on spatial frequency expansion and superposition of dipole fields to provide insightful information for applications such for secure multi-layered information storage.
Bechshøft, T Ø; Jakobsen, J; Sonne, C; Dietz, R
2011-08-15
Vitamins A and E content of inner organs, among these the kidneys, are increasingly being used as an indicator of adverse effects caused to the organism by e.g. environmental contaminants. In general, only a renal sub sample is used for analyses, and it is thus essential to know which part of the organ to sample in order to get a representative value for this important biomarker. The aim here was to assess the distribution of vitamins A (retinol) and E (α-tocopherol) within the polar bear multireniculate kidney (i.e. polar vs. medial position) and also within the cortex vs. medulla of each separate renculi. The results showed no significant difference between the medial and polar renculi with regards to either retinol (p=0.44) or α-tocopherol (p=0.75). There were, however, significant differences between cortex and medulla for both vitamins (retinol, p=0.0003; α-tocopherol, ppolar bear kidneys. Prior to analysis, the renculi should be separated into medulla and cortex. The results indicated no significant differences between renculi from different parts of the kidney. Copyright © 2011 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Rush, Scott A.; Borga, Katrine; Dietz, Rune; Born, Erik W.; Sonne, Christian; Evans, Thomas; Muir, Derek C.G.; Letcher, Robert J.; Norstrom, Ross J.; Fisk, Aaron T.
2008-01-01
To assess geographic distributions of elements in the Arctic we compared essential and non-essential elements in the livers of polar bears (Ursus maritimus) collected from five regions within Canada in 2002, in Alaska between 1994 and 1999 and from the northwest and east coasts of Greenland between 1988 and 2000. As, Hg, Pb and Se varied with age, and Co and Zn with gender, which limited spatial comparisons across all populations to Cd, which was highest in Greenland bears. Collectively, geographic relationships appeared similar to past studies with little change in concentration over time in Canada and Greenland for most elements; Hg and Se were higher in some Canadian populations in 2002 as compared to 1982 and 1984. Concentrations of most elements in the polar bears did not exceed toxicity thresholds, although Cd and Hg exceeded levels correlated with the formation of hepatic lesions in laboratory animals. - Geographical trends were observed for a number of elements in livers, including mercury, of polar bears collected across Alaska, Canada and Greenland and were similar to those observed in the early 1980s
Dynamical gluon mass in the instanton vacuum model
Musakhanov, M.; Egamberdiev, O.
2018-04-01
We consider the modifications of gluon properties in the instanton liquid model (ILM) for the QCD vacuum. Rescattering of gluons on instantons generates the dynamical momentum-dependent gluon mass Mg (q). First, we consider the case of a scalar gluon, no zero-mode problem occurs and its dynamical mass Ms (q) can be found. Using the typical phenomenological values of the average instanton size ρ = 1 / 3 fm and average inter-instanton distance R = 1 fm we get Ms (0) = 256 MeV. We then extend this approach to the real vector gluon with zero-modes carefully considered. We obtain the following expression Mg2 (q) = 2 Ms2 (q). This modification of the gluon in the instanton media will shed light on nonperturbative aspect on heavy quarkonium physics.
Thermal radiation from an evolving viscous quark gluon plasma
International Nuclear Information System (INIS)
Mitra, Sukanya; Mohanty, Payal; Sarkar, Sourav; Alam, Jan-E
2013-01-01
The effects of viscosity on the space-time evolution of quark gluon plasma produced in nuclear collisions at relativistic heavy ion collider energies have been studied. The entropy generated due to the viscous motion of the fluid has been taken into account in constraining the initial temperature by the final multiplicity (measured at the freeze-out point). The viscous effects on the photon spectra has been introduced consistently through the evolution dynamics and phase space factors of all the participating partons/hadrons in the production process. In contrast to some of the recent calculations the present work includes the contribution from the hadronic phase. A small change in the transverse momentum (p T ) distribution of photons is observed due to viscous effects. (author)
Semirelativistic potential model for three-gluon glueballs
International Nuclear Information System (INIS)
Mathieu, Vincent; Semay, Claude; Silvestre-Brac, Bernard
2008-01-01
The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Our results are in good agreement with other approaches and lattice calculation for the odderon trajectory but differ strongly from lattice in the J +- sector. We propose a possible explanation for this problem.
International Nuclear Information System (INIS)
Fowler, G.N.; Navarra, F.S.; Plumer, M.; Lawrence Berkeley Laboratory, Nuclear Science Division, Berkeley, California 94720); Vourdas, A.; Weiner, R.M.
1989-01-01
The interacting gluon model developed to describe the inelasticity distribution in hadron-nucleon collisions has been generalized and applied to hadron-nucleus and nucleus-nucleus interactions. Leading particle spectra and energy distributions in hadron-nucleus and nucleus-nucleus collisions are calculated
International Nuclear Information System (INIS)
Von Neumann-Cosel, Peter
2012-01-01
Small-angle polarized proton scattering including 0° at incident energies of a few 100 MeV/nucleon is established as a new spectrospcopic tool for the study of E1 and M1 strength distributions. Experiments of this type have been realized recently at RCNP, Osaka, Japan with high energy resolution of the order 25 - 30 keV (FWHM). Using 208 Pb as an example, the physics potential of such data is discussed. It includes information on the properties of the Pygmy Dipole Resonance but also on complete E1 and M1 strength distributions and thus the gamma strength function. The E1 polarizability can be extracted with a precision of about 4% providing important experimental constraints on the neutron skin thickness in 208 Pb.
Li, W.
2017-12-01
Data is the crux of science. The widespread availability of big data today is of particular importance for fostering new forms of geospatial innovation. This paper reports a state-of-the-art solution that addresses a key cyberinfrastructure research problem—providing ready access to big, distributed geospatial data resources on the Web. We first formulate this data-access problem and introduce its indispensable elements, including identifying the cyber-location, space and time coverage, theme, and quality of the dataset. We then propose strategies to tackle each data-access issue and make the data more discoverable and usable for geospatial data users and decision makers. Among these strategies is large-scale web crawling as a key technique to support automatic collection of online geospatial data that are highly distributed, intrinsically heterogeneous, and known to be dynamic. To better understand the content and scientific meanings of the data, methods including space-time filtering, ontology-based thematic classification, and service quality evaluation are incorporated. To serve a broad scientific user community, these techniques are integrated into an operational data crawling system, PolarHub, which is also an important cyberinfrastructure building block to support effective data discovery. A series of experiments were conducted to demonstrate the outstanding performance of the PolarHub system. We expect this work to contribute significantly in building the theoretical and methodological foundation for data-driven geography and the emerging spatial data science.
The Theory of Quark and Gluon Interactions
Ynduráin, Francisco J
2006-01-01
F. J. Ynduráin's book on Quantum Chromodynamics has become a classic among advanced textbooks. First published in 1983, and translated into Russian in 1986, it now sees its fourth edition. It addresses readers with basic knowledge of field theory and particle phenomenology. The author presents the basic facts of quark and gluon physics in pedagogical form. Theory is always confronted with experimental findings. The reader will learn enough to be able to follow modern research articles. This fourth edition presents a new section on heavy quark effective theories, more material on lattice QCD and on chiral perturbation theory.
Gluon fragmentation into 3 PJ quarkonium
International Nuclear Information System (INIS)
Ma, J.P.
1995-01-01
The functions of the gluon fragmentation into 3 P j quarkonium are calculated to order α 2 s . With the recent progress in analysing quarkonium systems in QCD it is possible show how the so called divergence in the limit of the zero-binding energy, which is related to P-wave quarkonia, is treated correctly in the case of fragmentation functions. The obtained fragmentation functions satisfy explicitly at the order of α 2 s the Altarelli-Parisi equation and when z → 0 they behave as z -1 as expected. 19 refs., 7 figs
Quarks, gluons, colour: facts or fiction?
International Nuclear Information System (INIS)
Buchholz, D.
1996-01-01
A general method is presented that allows one to determine from the local gauge invariant observables of a quantum field theory the underlying particle and symmetry structures appearing at the lower (ultraviolet) end of the spatio-temporal scale. Particles that are confined to small scales, i.e. do not appear in the physical spectrum, can be uncovered in this way without taking recourse to gauge fields or indefinite metric spaces. In this way notions such as quark, gluon, colour symmetry and confinement acquire a new and intrinsic meaning which is stable under gauge or duality transformations. The method is illustrated by the example of the Schwinger model. (orig.)
Hydrodynamics of quark-gluon plasmas
International Nuclear Information System (INIS)
Blaizot, J.P.
1986-06-01
This paper reviews some aspects of the hydrodynamics of quark-gluon plasmas. Various stages of ultra-relativistic heavy ion collisions are described. Several estimates of the maximum energy density expected to be achieved in these collisions are compared. Discontinuities which may be induced in the hydrodynamic flow by a phase transition are described and a convenient numerical method designed to deal with such discontinuous flows is briefly presented. Finally, the correlations between particle transverse momenta and multiplicities are analyzed and one discusses to which extent these correlations could signal the occurrence of a phase transition in heavy ion collisions
Effective gluon operators and neutron dipole moment
International Nuclear Information System (INIS)
Bigi, I.; Ural'tsev, N.G.
1991-01-01
The role of the purely gluon CP odd six-dimension effective arising in various CP-breaking models is discussed. This operators of most interest in the nonminimal Higgs sector models, the right W models and supersymmetric theories, where it may induce the neutron dipole moment at the level of the experimental restriction. The method for evaluating the magnitude d n is proposed and the reasons are given in favor that the original Weiberg's estimate based on the naive Dimensional Analysis is overdone significantly. The Peccei -Quinn mechanism, impact on the magnitude of d n , which generally may be very essential, is discussed
Electric and magnetic properties of hot gluons
International Nuclear Information System (INIS)
Hansson, T.H.; Zahed, I.
1987-01-01
The dielectric constant ε and magnetic permeability μ for gluon plasma are calculated from the one-loop gauge-invariant effective action. The real parts are gauge-fixing independent and agree with earlier work. The imaginary part of μ/sup -1/ is zero in any covariant background-field gauge, while the imaginary part of ε is gauge-fixing dependent and negative definite. This result indicates that there is no consistent perturbative description of gluonic plasmons on scale ≥(g 2 T)/sup -1/
The quark gluon plasma; Le plasma de quarks et de gluons
Energy Technology Data Exchange (ETDEWEB)
Granier de Cassagnac, R. [Ecole Polytechnique, Lab. Leprince-Ringuet, 91 - Palaiseau (France)
2010-05-15
The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)
Generalized parton distribution for non zero skewness
International Nuclear Information System (INIS)
Kumar, Narinder; Dahiya, Harleen; Teryaev, Oleg
2012-01-01
In the theory of strong interactions the main open question is how the nucleon and other hadrons are built from quarks and gluons, the fundamental degrees of freedom in QCD. An essential tool to investigate hadron structure is the study of deep inelastic scattering processes, where individual quarks and gluons can be resolved. The parton densities extracted from such processes encode the distribution of longitudinal momentum and polarization carried by quarks, antiquarks and gluons within a fast moving hadron. They have provided much to shape the physical picture of hadron structure. In the recent years, it has become clear that appropriate exclusive scattering processes may provide such information encoded in the general parton distributions (GPDs). Here, we investigate the GPD for deep virtual compton scattering (DVCS) for the non zero skewness. The study has investigated the GPDs by expressing them in terms of overlaps of light front wave functions (LFWFs). The work represented a spin 1/2 system as a composite of spin 1/2 fermion and spin 1 boson with arbitrary masses
International Nuclear Information System (INIS)
Capri, M.A.L.; Lemes, V.E.R.; Sobreiro, R.F.; Sorella, S.P.; Dudal, D.; Verschelde, H.; Gracey, J.A.
2006-01-01
The ghost condensate abc c b c c > is considered together with the gluon condensate μ 2 > in SU(2) Euclidean Yang-Mills theories quantized in the Landau gauge. The vacuum polarization ceases to be transverse due to the nonvanishing condensate abc c b c c >. The gluon propagator itself remains transverse. By polarization effects, this ghost condensate induces then a splitting in the gluon mass parameter, which is dynamically generated through μ 2 >. The obtained effective masses are real when μ 2 > is included in the analysis. In the absence of μ 2 >, the already known result that the ghost condensate induces effective tachyonic masses is recovered. At the one-loop level, we find that the effective diagonal mass becomes smaller than the off-diagonal one. This might serve as an indication for some kind of Abelian dominance in the Landau gauge, similar to what happens in the maximal Abelian gauge
Directory of Open Access Journals (Sweden)
Yuji Koike
2016-08-01
Full Text Available We compute the contribution from the longitudinally polarized proton to the twist-3 double-spin asymmetry ALT in inclusive (light hadron production from proton–proton collisions, i.e., p↑p→→hX. We show that using the relevant QCD equation-of-motion relation and Lorentz invariance relation allows one to eliminate the twist-3 quark-gluon correlator (associated with the longitudinally polarized proton in favor of one-variable twist-3 quark distributions and the (twist-2 transversity parton density. Including this result with the twist-3 pieces associated with the transversely polarized proton and unpolarized final-state hadron (which have already been calculated in the literature, we now have the complete leading-order cross section for this process.
Polarized proton collider at RHIC
International Nuclear Information System (INIS)
Alekseev, I.; Allgower, C.; Bai, M.; Batygin, Y.; Bozano, L.; Brown, K.; Bunce, G.; Cameron, P.; Courant, E.; Erin, S.; Escallier, J.; Fischer, W.; Gupta, R.; Hatanaka, K.; Huang, H.; Imai, K.; Ishihara, M.; Jain, A.; Lehrach, A.; Kanavets, V.; Katayama, T.; Kawaguchi, T.; Kelly, E.; Kurita, K.; Lee, S.Y.; Luccio, A.; MacKay, W.W.; Mahler, G.; Makdisi, Y.; Mariam, F.; McGahern, W.; Morgan, G.; Muratore, J.; Okamura, M.; Peggs, S.; Pilat, F.; Ptitsin, V.; Ratner, L.; Roser, T.; Saito, N.; Satoh, H.; Shatunov, Y.; Spinka, H.; Syphers, M.; Tepikian, S.; Tominaka, T.; Tsoupas, N.; Underwood, D.; Vasiliev, A.; Wanderer, P.; Willen, E.; Wu, H.; Yokosawa, A.; Zelenski, A.N.
2003-01-01
In addition to heavy ion collisions (RHIC Design Manual, Brookhaven National Laboratory), RHIC will also collide intense beams of polarized protons (I. Alekseev, et al., Design Manual Polarized Proton Collider at RHIC, Brookhaven National Laboratory, 1998, reaching transverse energies where the protons scatter as beams of polarized quarks and gluons. The study of high energy polarized protons beams has been a long term part of the program at BNL with the development of polarized beams in the Booster and AGS rings for fixed target experiments. We have extended this capability to the RHIC machine. In this paper we describe the design and methods for achieving collisions of both longitudinal and transverse polarized protons in RHIC at energies up to √s=500 GeV
International Nuclear Information System (INIS)
Mischler, J.; Banouni, M.; Banazeth, C.; Negre, M.; Benazeth, N.
1986-01-01
The influence of the surface topography on the polar angular distributions of secondary electrons emitted in Ar + (and Xe - )-Al collisions was studied. After each set of experiments, the surface target was viewed by scanning electron microscope. Under normal incidence, continuum background and Al L 23 VV Auger electron polar angular distributions were not modified by the topography and closely followed a cosine law. For Al L 23 MM Auger electrons, experimental angular distributions as a function of the emission polar angle theta, either were near a constant law or followed a decreasing law depending on the irradiation conditions. The N(theta) curves calculated from the models showed that the isotropic angular distributions obtained for electrons generated outside the crystal from a flat surface could be strongly modified by the surface topography. (author)
Energy Technology Data Exchange (ETDEWEB)
Goncalves, V.P. [Lund University, Department of Astronomy and Theoretical Physics, Lund (Sweden); Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Pelotas, RS (Brazil); Martins, L.A.S.; Sauter, W.K. [Universidade Federal de Pelotas, Instituto de Fisica e Matematica, Pelotas, RS (Brazil)
2016-02-15
The current uncertainty on the gluon density extracted from the global parton analysis is large in the kinematical range of small values of the Bjorken-x variable and low values of the hard scale Q{sup 2}. An alternative to reduces this uncertainty is the analysis of the exclusive vector meson photoproduction in photon-hadron and hadron-hadron collisions. This process offers a unique opportunity to constrain the gluon density of the proton, since its cross section is proportional to the gluon density squared. In this paper we consider current parametrisations for the gluon distribution and estimate the exclusive vector meson photoproduction cross section at HERA and LHC using the leading logarithmic formalism. We perform a fit of the normalisation of the γh cross section and the value of the hard scale for the process and demonstrate that the current LHCb experimental data are better described by models that assume a slow increasing of the gluon distribution at small x and low Q{sup 2}. (orig.)
International Nuclear Information System (INIS)
Lu, G.; Reiff, P.H.; Karty, J.L.; Hairston, M.R.; Heelis, R.A.
1989-01-01
Plasma flow data from the AE-C, AE-D and DE 2 satellites have been used to systematically study the distribution of the convection potential around the polar cap boundary under a variety of different interplanetary magnetic field (IMF) conditions. For either a garden hose (B x B y x B y >0) orientation of the IMF, the potential distribution is mainly affected by the sign of B y . In the northern hemisphere, the zero potential line (which separates the dusk convection cell from the dawn cell) on the dayside shifts duskward as B y changes from positive to negative. But in the southern hemisphere, a dawnward shift has been found, although the uncertainties are large. The typical range of displacement is about ±1.5 hours MLT. Note that this shift is in the opposite direction from most simple schematic models of ionospheric flow; this reflects the fact that the polar cap boundary is typically more poleward than the flow reversal associated with the region 1 current system, which shifts in the opposite direction. Thus the enhanced flow region typically crosses noon. In most cases a sine wave is an adequate representation of the distribution of potential around the boundary. However, in a few cases the data favors (at the 80% confidence level) a steeper gradient near noon, more indicative of a throat. The potential drop at the duskside boundary is almost greater than at the dawnside boundary. A slight duskward shift of the patterns observed as the IMF changes from garden hose to ortho-garden hose conditions. Analytic equipotential contours, given the potential function as a boundary condition, are constructed for several IMF conditions
Cornwall, C.; Titus, T.N.
2009-01-01
In the 1970s, Mariner and Viking observed features in the Mars northern polar region that were a few hundred kilometers in diameter with 20 fj,m brightness temperatures as low as 130 K (considerably below C02 ice sublimation temperatures). Over the past decade, studies have shown that these areas (commonly called "cold spots") are usually due to emissivity effects of frost deposits and occasionally to active C02 snowstorms. Three Mars years of Mars Global Surveyor Thermal Emission Spectrometer data were used to observe autumn and wintertime cold spot activity within the polar regions. Many cold spots formed on or near scarps of the perennial cap, probably induced by adiabatic cooling due to orographic lifting. These topographically associated cold spots were often smaller than those that were not associated with topography. We determined that initial grain sizes within the cold spots were on the order of a few millimeters, assuming the snow was uncontaminated by dust or water ice. On average, the half-life of the cold spots was 5 Julian days. The Mars global dust storm in 2001 significantly affected cold spot activity in the north polar region. Though overall perennial cap cold spot activity seemed unaffected, the distribution of cold spots did change by a decrease in the number of topographically associated cold spots and an increase in those not associated with topography. We propose that the global dust storm affected the processes that form cold spots and discuss how the global dust storm may have affected these processes. ?? 2009 by the American Geophysical Union.
Proton-proton elastic scattering with massive gluons
International Nuclear Information System (INIS)
Sauter, Werner K.; Ducati, M.B. Gay
2001-01-01
In this contribution different approaches to generate a gluon mass are discussed. More specially a recent result for the gluon propagator with a dynamical mass, proposal by Gorbar and Natale, is used in connection with the Landshoff-Nachtmann model for the Pomeron to describe the elastic differential cross section for pp scattering, with good agreement. (author)
Differences between quark and gluon jets as seen at LEP
International Nuclear Information System (INIS)
Tasevsky, M.
2001-01-01
The differences between quark and gluon jets are studied using LEP results on jet widths, scale dependent multiplicities, ratios of multiplicities, slopes and curvatures and fragmentation functions. It is emphasized that the observed differences stem primarily from the different quark and gluon colour factors
Differences between Quark and Gluon jets as seen at LEP
Tasevsky, Marek
2001-01-01
The differences between quark and gluon jets are studied using LEP results on jet widths, scale dependent multiplicities, ratios of multiplicities, slopes and curvatures and fragmentation functions. It is emphasized that the observed differences stem primarily from the different quark and gluon colour factors.
Dynamical instabilities in quark-gluon plasma with hard jet
International Nuclear Information System (INIS)
Pavlenko, O.P.
1990-01-01
The dynamical instabilities, whose development can be expected under the hard jet propagating through the quark-gluon plasma, are analyzed. The possible signals of the quark-gluon plasma formation in ultrarelativistic nuclear collisions connected with the development of the plasma-jet instabilities are discussed. 10 refs
Gluon condensate from lattice caculations: SU(3) pure gauge theory
International Nuclear Information System (INIS)
Kripfganz, J.
1981-01-01
A short distance expansion of Wilson loops is used to define and isolate vacuum expectation values of composite gluon operators. It is applied to available lattice Monte Carlo data for SU(3) pure gauge theory. The value obtained for the gluon condensate is consistent with the ITEP estimate. (author)
Soft gluon resummation for the single-spin production of W±-bosons
International Nuclear Information System (INIS)
Weber, A.
1993-01-01
We carefully study the production of W ± -bosons in singly-polarized hadron-hadron collisions. In the region of small transverse momenta of the produced W ± we perform the soft gluon resummation to double logarithmic accuracy. Special emphasis is laid on matching the resummed expression to the O(α s ) perturbative result valid at large transverse momenta. We investigate the phenomenological relevance of our results for pp-collisions at RHIC and show that in the future single-spin W ± -production may help to shed more light on the surprising EMC-result. (orig.)
Zhang, Y.; Li, F.; Zhang, S.; Hao, W.; Zhu, T.; Yuan, L.; Xiao, F.
2017-09-01
In this paper, Statistical Distribution based Conditional Random Fields (STA-CRF) algorithm is exploited for improving marginal ice-water classification. Pixel level ice concentration is presented as the comparison of methods based on CRF. Furthermore, in order to explore the effective statistical distribution model to be integrated into STA-CRF, five statistical distribution models are investigated. The STA-CRF methods are tested on 2 scenes around Prydz Bay and Adélie Depression, where contain a variety of ice types during melt season. Experimental results indicate that the proposed method can resolve sea ice edge well in Marginal Ice Zone (MIZ) and show a robust distinction of ice and water.
The Mixed Quark-Gluon Condensate from the Global Color Symmetry Model
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; PING Jia-Lun; LU Xiao-Fu; WANG Fan; ZHAO En-Guang
2002-01-01
The mixed quark-gluon condensate from the global color symmetry model is derived. It is shown that themixed quark-gluon condensate depends explicitly on the gluon propagator. This interesting feature may be regarded asan additional constraint on the model of gluon propagator. The values of the mixed quark-gluon condensate from someansatz for the gluon propagator are compared with those determined from QCD sum rules.
International Nuclear Information System (INIS)
Degtyarenko, P.V.; Efremenko, Yu.V.; Fedorov, V.B.
1991-01-01
Energy and A-dependencies of cumulative Λ 0 particle spectra for the particles emitted at angle 90 deg have been studied by means of electronic method; its polarization has been determined. Obtained data are analyzed both in terms of nuclear scaling phenomena and of possible existence of baryonrich quark-gluon plasma and are compared with other known data on cumulative particle formation. 31 refs.; 8 figs
Energy Technology Data Exchange (ETDEWEB)
Wunderlich, Y.; Afzal, F.; Thiel, A.; Beck, R. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany)
2017-05-15
This work presents a simple method to determine the significant partial wave contributions to experimentally determined observables in pseudoscalar meson photoproduction. First, fits to angular distributions are presented and the maximum orbital angular momentum L{sub max} needed to achieve a good fit is determined. Then, recent polarization measurements for γp → π{sup 0}p from ELSA, GRAAL, JLab and MAMI are investigated according to the proposed method. This method allows us to project high-spin partial wave contributions to any observable as long as the measurement has the necessary statistical accuracy. We show, that high precision and large angular coverage in the polarization data are needed in order to be sensitive to high-spin resonance states and thereby also for the finding of small resonance contributions. This task can be achieved via interference of these resonances with the well-known states. For the channel γp → π{sup 0}p, those are the N(1680)(5)/(2){sup +} and Δ(1950)(7)/(2){sup +}, contributing to the F-waves. (orig.)
Dietzel, Erik; Anderson, Danielle E; Castan, Alexandre; von Messling, Veronika; Maisner, Andrea
2011-07-01
In paramyxoviruses, the matrix (M) protein mediates the interaction between the envelope and internal proteins during particle assembly and egress. In measles virus (MeV), M mutations, such as those found in subacute sclerosing panencephalitis (SSPE) strains, and differences in vaccine and wild-type M proteins can affect the strength of interaction with the envelope glycoproteins, assembly efficiency, and spread. However, the contribution of the M protein to the replication and pathogenesis of the closely related canine distemper virus (CDV) has not been characterized. To this end this, we generated a recombinant wild-type CDV carrying a vaccine strain M protein. The recombinant virus retained the parental growth phenotype in VerodogSLAMtag cells, but displayed an increased particle-to-infectivity ratio very similar to that of the vaccine strain, likely due to inefficient H protein incorporation. Even though infectious virus was released only from the apical surface, consistent with the release polarity of the wild-type CDV strain, envelope protein distribution in polarized epithelial cells reproduced the bipolar pattern seen in vaccine strain-infected cells. Most notably, the chimeric virus was completely attenuated in ferrets and caused only a mild and transient leukopenia, indicating that the differences in particle infectivity and envelope protein sorting mediated by the vaccine M protein contribute importantly to vaccine strain attenuation.
Equation of state of quasi-free gluon gas
International Nuclear Information System (INIS)
Chakrabarty, Somenath; Syam, Debapriyo
1993-01-01
The object of this work is to derive an equation of state for a system of gluons beyond the deconfining temperature (∼200 MeV) with phenomenological applications in mind. Our starting point is the relativistic virial theorem. We assume that the non-Abelian nature of QCD (especially the confirming gluon-gluon interaction), as far as the gluon gas is concerned, can be accounted for by postulating a bag pressure (B), while the residual interaction among the gluons can be treated as if the problem is Abelian. Near the 'critical' temperature the residual interactions are seen to play an important role. Also the Stefan-Boltzmann constant is required to be replaced by an effective constant having a somewhat smaller value. (Author)
Bound states of quarks and gluons and hadronic transitions
International Nuclear Information System (INIS)
Castro, Antonio Soares de.
1990-05-01
A potential which incorporates the concepts of confinement and asymptotic freedom, previously utilized in the description of the spectroscopy of mesons and baryons, is extended to the gluon sector. The mass spectroscopy of glueballs and hybrids is analyzed considering only pairwise potentials and massive constituent gluons. The mass spectrum of the color octet two-gluon system is adopted as a suitable description of the intermediate states of hadronic transitions, within the framework of the multipole expansion for quantum chromodynamics. The spin-dependent effects in the gluonium spectrum, associated with the Coulombian potential, are calculated through the inverted first Born approximation for the gluon-gluon scattering. (author). 102 refs, 1 fig, 13 tabs
Fractal based observables to probe jet substructure of quarks and gluons
Davighi, Joe; Harris, Philip
2018-04-01
New jet observables are defined which characterize both fractal and scale-dependent contributions to the distribution of hadrons in a jet. These infrared safe observables, named Extended Fractal Observables (EFOs), have been applied to quark-gluon discrimination to demonstrate their potential utility. The EFOs are found to be individually discriminating and only weakly correlated to variables used in existing discriminators. Consequently, their inclusion improves discriminator performance, as here demonstrated with particle level simulation from the parton shower.
Rafiee Fanood, Mohammad M; Ganjitabar, Hassan; Garcia, Gustavo A; Nahon, Laurent; Turchini, Stefano; Powis, Ivan
2018-04-17
Photoionization of the chiral monoterpene limonene has been investigated using polarized synchrotron radiation between the adiabatic ionization threshold, 8.505 and 23.5 eV. A rich vibrational structure is seen in the threshold photoelectron spectrum and is interpreted using a variety of computational methods. The corresponding photoelectron circular dichroism-measured in the photoelectron angular distribution as a forward-backward asymmetry with respect to the photon direction-was found to be strongly dependent on the vibronic structure appearing in the photoelectron spectra, with the observed asymmetry even switching direction in between the major vibrational peaks. This effect can be ultimately attributed to the sensitivity of this dichroism to small phase shifts between adjacent partial waves of the outgoing photoelectron. These observations have implications for potential applications of this chiroptical technique, where the enantioselective analysis of monoterpene components is of particular interest. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
International Nuclear Information System (INIS)
Nurdin, M.; Nikijuluw, N.; Subardjo; Sudarto, S.
2000-01-01
Based on previous investigation results, a favourable zone of 20-80 meters in wide, 80-240 meters in length and in the direction of East-West to Northwest-Southeast was found. The favourable zone is conductor, associated with sulfide. Induced polarization method has been applied to find vertical and horizontal sulfide distribution. The measurement was conducted in perpendicular to lateral direction of the conductive zone in an interval of 20 meters. Properties measured are apparent resistivity and charge ability. Measurement results indicated the presence of sulfide zone with the position and dip are sub-vertical. Sulfide zones were found on the fault cross-point with the directions being East-West to East South East-West North West by fault is North-South. This anomalies were then represented in 3 (three) dimension tomographic model. (author)
International Nuclear Information System (INIS)
Genin, F.Y.; Stolz, C.J.; Reitter, T.; Kozlowski, M.R.; Bevis, R.P.; vonGunten, M.K.
1997-01-01
Hafnia-silica multilayer polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The polarizers were designed to operate at 1064 nm at Brewster's angle (56 degree). They were tested with a 3-ns laser pulse at 45, 56, and 65 degree incidence angle in order to vary the electric field distribution in the multilayer, study their effects on damage morphology, and investigate possible advantages of off-use angle laser conditioning. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies (pit, flat bottom pit, scald, outer layer delamination) were observed; they depend strongly on incident angle of the laser beam. Massive delamination observed at 45 and 56 degree incidence, did not occur at 65 degree; instead, large and deep pits were found at 65 degree. Electric field distribution, temperature rise, and change in stress in the multilayer were calculated to attempt to better understand the relation between damage morphology, electric field peak locations, and maximum thermal stress gradients. The calculations showed a twofold increase in stress change in the hafnia top layers depending on incident angle. Stress gradient in the first hafnia-silica interface was found to be highest for 45, 56, and 65 degree, respectively. Finally, the maximum stress was deeper in the multilayer at 65 degree. Although the limitations of such simple thermal mechanical model are obvious, the results can explain that outer layer delamination is more likely at 45 and 56 degree than 65 degree and that damage sites are expected to be deeper at 65 degree
Change detection in full and dual polarization sar data and the complex wishart distribution
DEFF Research Database (Denmark)
Nielsen, Allan Aasbjerg; Conradsen, Knut; Skriver, Henning
A test statistic for equality of two complex variance-covariance matrices following the complex Wishart distribution with an associated probability of observing a smaller value of the test statistic is sketched. We demonstrate the use of the test statistic and the associated probability measure f...... for change detection in both full and dual polarimetry synthetic aperture radar (SAR) data collected by the Danish EMISAR system....
Bringi, V. N.; Chandrasekar, V.; Hubbert, J.; Gorgucci, E.; Randeu, W. L.; Schoenhuber, M.
2003-01-01
The application of polarimetric radar data to the retrieval of raindrop size distribution parameters and rain rate in samples of convective and stratiform rain types is presented. Data from the Colorado State University (CSU), CHILL, NCAR S-band polarimetric (S-Pol), and NASA Kwajalein radars are analyzed for the statistics and functional relation of these parameters with rain rate. Surface drop size distribution measurements using two different disdrometers (2D video and RD-69) from a number of climatic regimes are analyzed and compared with the radar retrievals in a statistical and functional approach. The composite statistics based on disdrometer and radar retrievals suggest that, on average, the two parameters (generalized intercept and median volume diameter) for stratiform rain distributions lie on a straight line with negative slope, which appears to be consistent with variations in the microphysics of stratiform precipitation (melting of larger, dry snow particles versus smaller, rimed ice particles). In convective rain, `maritime-like' and `continental-like' clusters could be identified in the same two-parameter space that are consistent with the different multiplicative coefficients in the Z = aR1.5 relations quoted in the literature for maritime and continental regimes.
Casimir meets Poisson: improved quark/gluon discrimination with counting observables
Frye, Christopher; Larkoski, Andrew J.; Thaler, Jesse; Zhou, Kevin
2017-09-01
Charged track multiplicity is among the most powerful observables for discriminating quark- from gluon-initiated jets. Despite its utility, it is not infrared and collinear (IRC) safe, so perturbative calculations are limited to studying the energy evolution of multiplicity moments. While IRC-safe observables, like jet mass, are perturbatively calculable, their distributions often exhibit Casimir scaling, such that their quark/gluon discrimination power is limited by the ratio of quark to gluon color factors. In this paper, we introduce new IRC-safe counting observables whose discrimination performance exceeds that of jet mass and approaches that of track multiplicity. The key observation is that track multiplicity is approximately Poisson distributed, with more suppressed tails than the Sudakov peak structure from jet mass. By using an iterated version of the soft drop jet grooming algorithm, we can define a "soft drop multiplicity" which is Poisson distributed at leading-logarithmic accuracy. In addition, we calculate the next-to-leading-logarithmic corrections to this Poisson structure. If we allow the soft drop groomer to proceed to the end of the jet branching history, we can define a collinear-unsafe (but still infrared-safe) counting observable. Exploiting the universality of the collinear limit, we define generalized fragmentation functions to study the perturbative energy evolution of collinear-unsafe multiplicity.
Quarkonium decays: Testing the 3-gluon vertex
International Nuclear Information System (INIS)
Koller, K.; Walsh, T.F.; Zerwas, P.M.; Technische Hochschule Aachen
1980-12-01
We study the 3-jet decays of S and P-wave quarkonia with C = +. If observed, some of these will offer a way of seeing the 3G vertex of QCD via 1 Ssub(o), 3 Psub(o), 3 P 2 (Qanti Q) → GGG + Gqanti q → 3 jets. (As is well-known, cancellations reduce 3 P 1 (anti Q) → GGG.) We elaborate in detail the S-wave decay as it is expected to show all the characteristic features of orthoquarkonium decays into 4 jets, 3 S 1 (Qanti Q) → GGGG + GGqanti q → 4 jets which we will comment upon. These quarkonium decays offer a very clear signal for QCD as a non-abelian local gauge field theory with color-charged gluons. (orig.)
Very boosted Higgs in gluon fusion
Grojean, Christophe; Schlaffer, Matthias; Weiler, Andreas
2014-01-01
The Higgs production and decay rates offer a new way to probe new physics beyond the Standard Model. While dynamics aiming at alleviating the hierarchy problem generically predict deviations in the Higgs rates, the current experimental analyses cannot resolve the long- and short-distance contributions to the gluon fusion process and thus cannot access directly the coupling between the Higgs and the top quark. We investigate the production of a boosted Higgs in association with a high-transverse momentum jet as an alternative to the $t\\bar{t}h$ channel to pin down this crucial coupling. Presented first in the context of an effective field theory, our analysis is then applied to models of partial compositeness at the TeV scale and of natural supersymmetry.
Quark-gluon plasma: experimental signatures
International Nuclear Information System (INIS)
Drapier, O.
1995-01-01
The existence of a deconfining phase transition of nuclear matter is a clear prediction of lattice quantum chromodynamics calculations. The signatures of this quark-gluon plasma (QGP) have been searched for, since the first high energy ion beams became available at BNL and CERN in 1986, and gold and lead beams are now accelerated at 11 and 160 GeV per nucleon by the AGS and SPS. An overview of the main signatures expected in case of QGP formation is presented here. Although some recent results have been found in agreement with the predictions of the QGP scenario, no clear evidence for its formation has been observed at present. Nevertheless, new high statistics results are expected from CERN lead beams. In addition, future experiments are being prepared at RHIC and LHCC, providing an increase by two orders of magnitude of the c.m.s. energy within a few years. (author). 66 refs., 28 figs
Soft gluons and superleading logarithms in QCD
Forshaw, J R
2009-01-01
After a brief introduction to the physics of soft gluons in QCD we present a surprising prediction. Dijet production in hadron-hadron collisions provides the paradigm, i.e. h_1 +h_2 \\to jj+X. In particular, we look at the case where there is a restriction placed on the emission of any further jets in the region in between the primary (highest p_T) dijets. Logarithms in the ratio of the jet scale to the veto scale can be summed to all orders in the strong coupling. Surprisingly, factorization of collinear emissions fails at scales above the veto scale and triggers the appearance of double logarithms in the hard sub-process. The effect appears first at fourth order relative to the leading order prediction and is subleading in the number of colours.
Very boosted Higgs in gluon fusion
Energy Technology Data Exchange (ETDEWEB)
Grojean, C. [Univ. Autonoma de Barcelona, Bellaterra (Spain). ICREA at IFAE; Salvioni, E. [California Univ., Davis, CA (United States). Dept. of Physics; European Organization for Nuclear Research (CERN), Geneva (Switzerland); Padova Univ. (Italy). Dipt. di Fisica e Astronomica; INFN, Sezione di Padova (Italy); Schlaffer, M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Weiler, A. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
2013-12-15
The Higgs production and decay rates offer a new way to probe new physics beyond the Standard Model. While dynamics aiming at alleviating the hierarchy problem generically predict deviations in the Higgs rates, the current experimental analyses cannot resolve the long- and short-distance contributions to the gluon fusion process and thus cannot access directly the coupling between the Higgs and the top quark. We investigate the production of a boosted Higgs in association with a high-transverse momentum jet as an alternative to the t anti th channel to pin down this crucial coupling. Presented rst in the context of an effective field theory, our analysis is then applied to models of partial compositeness at the TeV scale and of natural supersymmetry.
Gluon Green functions free of quantum fluctuations
Directory of Open Access Journals (Sweden)
A. Athenodorou
2016-09-01
Full Text Available This letter reports on how the Wilson flow technique can efficaciously kill the short-distance quantum fluctuations of 2- and 3-gluon Green functions, remove the ΛQCD scale and destroy the transition from the confining non-perturbative to the asymptotically-free perturbative sector. After the Wilson flow, the behavior of the Green functions with momenta can be described in terms of the quasi-classical instanton background. The same behavior also occurs, before the Wilson flow, at low-momenta. This last result permits applications as, for instance, the detection of instanton phenomenological properties or a determination of the lattice spacing only from the gauge sector of the theory.
Energy Technology Data Exchange (ETDEWEB)
Castro, Antonio Soares de
1990-05-01
A potential which incorporates the concepts of confinement and asymptotic freedom, previously utilized in the description of the spectroscopy of mesons and baryons, is extended to the gluon sector. The mass spectroscopy of glueballs and hybrids is analyzed considering only pairwise potentials and massive constituent gluons. The mass spectrum of the color octet two-gluon system is adopted as a suitable description of the intermediate states of hadronic transitions, within the framework of the multipole expansion for quantum chromodynamics. The spin-dependent effects in the gluonium spectrum, associated with the Coulombian potential, are calculated through the inverted first Born approximation for the gluon-gluon scattering. (author). 102 refs, 1 fig, 13 tabs.
Physics of the quark - gluon plasma
International Nuclear Information System (INIS)
2001-09-01
This document gathers 31 contributions to the workshop on the physics of quark-gluon plasma that took place in Palaiseau in september 2001: 1) gamma production in heavy collisions, 2) BRAHMS, 3) experimental conference summary, 4) modelling relativistic nuclear collisions, 5) microscopic reaction dynamics at SPS and RHIC, 6) direct gamma and hard scattering at SPS, 7) soft physics at RHIC, 8) results from the STAR experiment, 9) quarkonia: experimental possibilities, 10) elliptic flow measurements with PHENIX, 11) charmonium production in p-A collisions, 12) anisotropic flow at the SPS and RHIC, 13) deciphering the space-time evolution of heavy ion collisions with correlation measurements, 14) 2-particle correlation at RHIC, 15) particle spectra at AGS, SPS and RHIC, 16) strangeness production in STAR, 17) strangeness production in Pb-Pb collisions at SPS, 18) heavy ion physics at CERN after 2000 and before LHC, 19) NEXUS guideline and theoretical consistency, 20) introduction to high p T physics at RHIC, 21) a novel quasiparticle description of the quark-gluon plasma, 22) dissociation of excited quarkonia states, 23) high-mass dimuon and B → J/Ψ production in ultrarelativistic heavy ion collisions, 24) strange hyperon production in p + p and p + Pb interactions from NA49, 25) heavy quarkonium hadron cross-section, 26) a new method of flow analysis, 27) low mass dilepton production and chiral symmetry restoration, 28) classical initial conditions for nucleus-nucleus collisions, 29) numerical calculation of quenching weights, 30) strangeness enhancement energy dependence, and 31) heavy quarkonium dissociation
Physics of the quark - gluon plasma
Energy Technology Data Exchange (ETDEWEB)
NONE
2001-09-01
This document gathers 31 contributions to the workshop on the physics of quark-gluon plasma that took place in Palaiseau in september 2001: 1) gamma production in heavy collisions, 2) BRAHMS, 3) experimental conference summary, 4) modelling relativistic nuclear collisions, 5) microscopic reaction dynamics at SPS and RHIC, 6) direct gamma and hard scattering at SPS, 7) soft physics at RHIC, 8) results from the STAR experiment, 9) quarkonia: experimental possibilities, 10) elliptic flow measurements with PHENIX, 11) charmonium production in p-A collisions, 12) anisotropic flow at the SPS and RHIC, 13) deciphering the space-time evolution of heavy ion collisions with correlation measurements, 14) 2-particle correlation at RHIC, 15) particle spectra at AGS, SPS and RHIC, 16) strangeness production in STAR, 17) strangeness production in Pb-Pb collisions at SPS, 18) heavy ion physics at CERN after 2000 and before LHC, 19) NEXUS guideline and theoretical consistency, 20) introduction to high p{sub T} physics at RHIC, 21) a novel quasiparticle description of the quark-gluon plasma, 22) dissociation of excited quarkonia states, 23) high-mass dimuon and B {yields} J/{psi} production in ultrarelativistic heavy ion collisions, 24) strange hyperon production in p + p and p + Pb interactions from NA49, 25) heavy quarkonium hadron cross-section, 26) a new method of flow analysis, 27) low mass dilepton production and chiral symmetry restoration, 28) classical initial conditions for nucleus-nucleus collisions, 29) numerical calculation of quenching weights, 30) strangeness enhancement energy dependence, and 31) heavy quarkonium dissociation.
Baryonic hybrids: Gluons as beads on strings between quarks
International Nuclear Information System (INIS)
Cornwall, John M.
2005-01-01
In this paper we analyze the ground state of the heavy-quark qqqG system using standard principles of quark confinement and massive constituent gluons as established in the center-vortex picture. The known string tension K F and approximately-known gluon mass M lead to a precise specification of the long-range nonrelativistic part of the potential binding the gluon to the quarks with no undetermined phenomenological parameters, in the limit of large interquark separation R. Our major tool (also used earlier by Simonov) is the use of proper-time methods to describe gluon propagation within the quark system, along with some elementary group theory describing the gluon Wilson-line as a composite of colocated q and q lines. We show that (aside from color-Coulomb and similar terms) the gluon potential energy in the presence of quarks is accurately described (for small gluon fluctuations) via attaching these three strings to the gluon, which in equilibrium sits at the Steiner point of the Y-shaped string network joining the three quarks. The gluon undergoes small harmonic fluctuations that slightly stretch these strings and quasiconfine the gluon to the neighborhood of the Steiner point. To describe nonrelativistic ground-state gluonic fluctuations at large R we use the Schroedinger equation, ignoring mixing with l=2 states. Available lattice data and real-world hybrids require consideration of R values small enough for significant relativistic corrections, which we apply using a variational principle for the relativistic harmonic-oscillator. We also consider the role of color-Coulomb contributions. In terms of interquark separations R, we find leading nonrelativistic large-R terms in the gluon excitation energy of the form ε(R)→M+ξ[K F /(MR)] 1/2 -ζα c /R where ξ,ζ are calculable numerical coefficients and α c ≅ 0.15 is the color-Coulomb qq coupling. When the gluon is relativistic, ε∼(K F /R) 1/3 . We get an acceptable fit to lattice data with M=500 Me
The Large Scale Distribution of Water Ice in the Polar Regions of the Moon
Jordan, A.; Wilson, J. K.; Schwadron, N.; Spence, H. E.
2017-12-01
For in situ resource utilization, one must know where water ice is on the Moon. Many datasets have revealed both surface deposits of water ice and subsurface deposits of hydrogen near the lunar poles, but it has proved difficult to resolve the differences among the locations of these deposits. Despite these datasets disagreeing on how deposits are distributed on small scales, we show that most of these datasets do agree on the large scale distribution of water ice. We present data from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter (LRO), LRO's Lunar Exploration Neutron Detector (LEND), the Neutron Spectrometer on Lunar Prospector (LPNS), LRO's Lyman Alpha Mapping Project (LAMP), LRO's Lunar Orbiter Laser Altimeter (LOLA), and Chandrayaan-1's Moon Mineralogy Mapper (M3). All, including those that show clear evidence for water ice, reveal surprisingly similar trends with latitude, suggesting that both surface and subsurface datasets are measuring ice. All show that water ice increases towards the poles, and most demonstrate that its signature appears at about ±70° latitude and increases poleward. This is consistent with simulations of how surface and subsurface cold traps are distributed with latitude. This large scale agreement constrains the origin of the ice, suggesting that an ancient cometary impact (or impacts) created a large scale deposit that has been rendered locally heterogeneous by subsequent impacts. Furthermore, it also shows that water ice may be available down to ±70°—latitudes that are more accessible than the poles for landing.
Shear and bulk viscosity of high-temperature gluon plasma
Zhang, Le; Hou, De-Fu
2018-05-01
We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)
Advantages of polarization experiments at RHIC
International Nuclear Information System (INIS)
Underwood, D.G.
1990-01-01
We point out various spin experiments that could be done if the polarized beam option is pursued at RHIC. The advantages of RHIC for investigating several current and future physics problems are discussed. In particular, the gluon spin dependent structure function of the nucleon could be measured cleanly and systematically. Relevant experience developed in conjunction with the Fermilab Polarized Beam program is also presented. 8 refs., 2 tabs
Pommereau, J. P.; Piquard, J.
1994-01-01
A light, relatively cheap and easy to operate balloonborne UV-visible spectrometer was designed for investigating ozone photochemistry in the Arctic winter. The instrument was flown 11 times during the European Arctic Stratospheric Ozone Experiment (EASOE) in winter 1991-92 in Northern Scandinavia. The first simultaneous measurements of vertical distributions of aerosols, PSC's, O3, NO2 and OClO inside the vortex during flight no. 6 on 16 January, in cold conditions are reported, which show that nitrogen oxides were almost absent (lower than 100 ppt) in the stratosphere below 22 km, while a layer of relatively large OClO concentration (15 ppt) was present at the altitude of the minimum temperature.
Directory of Open Access Journals (Sweden)
Maxime Deutsch
2014-05-01
Full Text Available Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.
Deutsch, Maxime; Gillon, Béatrice; Claiser, Nicolas; Gillet, Jean-Michel; Lecomte, Claude; Souhassou, Mohamed
2014-05-01
Since the 1980s it has been possible to probe crystallized matter, thanks to X-ray or neutron scattering techniques, to obtain an accurate charge density or spin distribution at the atomic scale. Despite the description of the same physical quantity (electron density) and tremendous development of sources, detectors, data treatment software etc., these different techniques evolved separately with one model per experiment. However, a breakthrough was recently made by the development of a common model in order to combine information coming from all these different experiments. Here we report the first experimental determination of spin-resolved electron density obtained by a combined treatment of X-ray, neutron and polarized neutron diffraction data. These experimental spin up and spin down densities compare very well with density functional theory (DFT) calculations and also confirm a theoretical prediction made in 1985 which claims that majority spin electrons should have a more contracted distribution around the nucleus than minority spin electrons. Topological analysis of the resulting experimental spin-resolved electron density is also briefly discussed.
The SU(3) running coupling from lattice gluons
Energy Technology Data Exchange (ETDEWEB)
Parrinello, C. [Edinburgh Univ. (United Kingdom). Dept. of Phys. and Astron.; UKQCD Collaboration
1995-04-01
We provide numerical results for the running coupling in SU(3) Yang-Mills theory as determined from an analysis of lattice two and three-point gluon correlation functions. The coupling is evaluated directly, from first principles, by defining suitable renormalisation constants from the lattice triple gluon vertex and gluon propagator. For momenta larger than 2GeV, the coupling is found to run according to the 2-loop asymptotic formula. The influence of lattice artifacts on the results appears negligible within the precision of our measurements, although further work on this point is in progress. ((orig.)).
Infra-red ghost contribution to the gluon Green's functions
International Nuclear Information System (INIS)
Paccanoni, F.
1985-01-01
The Schwinger-Dyson equations for the ghost propagator and the ghost-ghost-gluon vertex function are studied in the Landau gauge. A confining infra-red singularity is assumed for the gluon propagator and a suitable approximation is devised for the solution of the integral equations. It is found that the bare values of the ghost propagator and coupling cannot be a consistent solution of either equation. It is determined a possible behaviour of the correction factor for the ghost propagator in the small-momentum limit and discussed the consistency of the approximation schemes for the gluon propagator that neglet Faddeev-Popov ghost
Quark and gluon propagators in the spherical bag model
Energy Technology Data Exchange (ETDEWEB)
Kulish, Yu V [AN Ukrainskoj SSR, Fiziko-Tekhnicheskij Inst., Kharkov
1983-12-01
The quark and gluon propagators in a spherical cavity have been obtained by summation of the quark field modes (J-1/2, J is the total moment) and gluon field modes (J=1). The requirements for the spatial components of the gluon propagator Gsub(ik)(x, x') and the quark propagator S(x, x') to be Green functions of the wave equations result in the coincidence of directions for anti x and anti x' vectors. Relations have been derived which allow verification of the self-consistency of approximations used to calculate dynamic values.
Quark and gluon propagators in the spherical bag model
International Nuclear Information System (INIS)
Kulish, Yu.V.
1983-01-01
The quark and gluon propagators in a spherical cavity have been obtained by summation of the quark field modes (J-1/2, J is the total moment) and gluon field modes (J=1). The requirements for the spatial components of the gluon propagator Gsub(ik)(x, x') and the quark propagator S(x, x') to be Green functions of the wave equations result in the coincidence of directions for anti x and anti x' vectors. Relations have been derived which allow verification of the self-consistency of approximations used to calculate dynamic values
Quark-gluon mixing in pseudoscalar and tensor mesons
International Nuclear Information System (INIS)
Eremyan, Sh.S.; Nazaryan, A.E.
1986-01-01
A mixing model of quark-antiquark ang gluonium states in η, η', i(1440) pseudoscalar and f, f', Θ(1690) tensor mesons is considered. Description of and predictions for 68 two-particle decays with these particles taking part in them are obtained. It is shown that i(1440) by 85% consists of gluonium and Θ(1690) is a pure gluonic state. The quark-gluon and gluon-gluon couplings in the pseudoscalar sector are obtained to be stronger as compared to the corresponding ones in the tensor case
Quasi-particle model for lattice QCD: quark-gluon plasma in heavy ion collisions
International Nuclear Information System (INIS)
Chandra, Vinod; Ravishankar, V.
2009-01-01
We propose a quasi-particle model to describe the lattice QCD equation of state for pure SU(3) gauge theory in its deconfined state, for T≥1.5T c . The method involves mapping the interaction part of the equation of state to an effective fugacity of otherwise non-interacting quasi-gluons. We find that this mapping is exact. Using the quasi-gluon distribution function, we determine the energy density and the modified dispersion relation for the single particle energy, in which the trace anomaly is manifest. As an application, we first determine the Debye mass, and then the important transport parameters, viz., the shear viscosity, η, and the shear viscosity to entropy density ratio, η/S. We find that both η and η/S are sensitive to the interactions, and that the interactions significantly lower both η and η/S. (orig.)
Quark charges and colour gluon mass from deep-inelastic bremsstrahlung
International Nuclear Information System (INIS)
Pandita, P.N.
1978-01-01
Sum rules are derived for the structure function V(x) for the 'three-photon' process e +- + p →e +- + γ +X which can distinguish between various colour models below colour threshold, independently of the quark and gluon distributions. A careful study of the sum rule for V(x) in the broken colour gauge theory model can in principle be used to determine the colour gluon mass. Invoking the specific assumptions of the dominance of p-type quarks and neglecting the sea of quark-antiquark pairs, bounds for V(x) are obtained in terms of νW 2 (x) which can distinguish between various colour models below colour threshold. (author)
Monte Carlo study on the properties of gluon and quark jets
Zhang Kun Shi; Yu Mei Ling; LianShouLiu
2002-01-01
The 3-jet events produced in e sup + e sup - collisions at 91.2 GeV have been studied using Monte Carlo method. After applying two angular cuts the three angles between the jets are used to identify the individual jet in 3-jet events. The energy distributions of the three jets, the mean particle multiplicities, mean transverse momenta of the three jets in equal energy bins and their distributions have been analyzed. Comparing with the corresponding results from the quark jets in 2-jet events, a simple method to select gluon and quark jets from 3-jet events is obtained. The properties of the gluon and quark jets being selected using the introduced method are in qualitative agreement with the expectations of perturbative QCD. The ratio of the mean multiplicity between quark and gluon jets, sub g sub l sub u sub o sub n / sub q sub u sub q sub r sub k , has been calculated. The results, again, agree with the experimental results from SLD, OPAL, ALEPH and DELPHI Collaborations, indicating that the method propose...
Study on the coherent emission of gluons in QCD jets from electron-positron annihilation
International Nuclear Information System (INIS)
Kreutzmann, H.
1990-11-01
The inclusive momentum distribution of charged particles is studied with the OPAL detector at LEP in multihadronic events produced in e + e - -annihilations at E cm ≅ M(Z 0 ). Agreement is found with analytical formulae for gluon production that include the phenomena of soft gluon interference. Using data from c.m. energies between 14 GeV and 91 GeV, the dependence of the inclusive momentum distribution on the centre of momentum energy E cm is investigated. The analytic predictions derived from perturbative energy E cm ≅ M(Z 0 ) and its change with E cm are also described by QCD shower Monte Carlo programs which include either coherent gluon branchings or string fragmentation. Simple incoherent models with independent fragmentation fail to reproduce the energy dependence and the momentum spectra. A detailed simulation of the OPAL Jet Chamber and a reconstruction program for jet chamber tracks were developed and applied in this analysis. The essential features of both programs are presented. (orig.) [de
The very hot soup of quarks and gluons; La tres chaude soupe de quarks et de gluons
Energy Technology Data Exchange (ETDEWEB)
Ter Minassian, V.
2010-05-15
The Phenix collaboration at the RHIC collider (Usa) has measured directly, for the first time, the temperature just after 2 gold nuclei have collided. All the experimental conditions were taken to assure that the temperature measured was that of the quark-gluon plasma. The value of this temperature is 4000*10{sup 9} K, which is 1.20 as high as the theoretical temperature threshold for the existence of the quark-gluon plasma. It is a proof that the quark-gluon plasma can be created within the operating conditions of the RHIC. (A.C.)
Role of the QCD induced gluon-gluon coupling to gauge boson pairs in the multitev region
International Nuclear Information System (INIS)
Ametller, L.; Gava, E.; Paver, N.; Treleani, D.
1985-02-01
We discuss the production of γγ and Zsup(O)γ pairs induced by the gluon-gluon fusion mechanism at typical supercollider energies. Due to the large flux of gluons with small fractional momenta, it is found that in certain kinematical configurations that subprocess, although of order (αsub(S)/π) 2 with respect to the leading quark annihilation, can give an appreciable contribution to the cross-section for Zsup(O)γ and even a larger one for the γγ production. (author)
DEFF Research Database (Denmark)
Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer
2010-01-01
We solve the three-dimensional time-dependent Schrödinger equation for a few-cycle circularly polarized femtosecond laser pulse that interacts with an oriented target exemplified by an argon atom, initially in a 3px or 3py state. The photoelectron momentum distributions show distinct signatures o...
Transverse momentum distributions inside the nucleon from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Musch, Bernhard Ulrich
2009-05-29
Nucleons, i.e., protons and neutrons, are composed of quarks and gluons, whose interactions are described by the theory of quantum chromodynamics (QCD), part of the standard model of particle physics. This work applies lattice QCD to compute quark momentum distributions in the nucleon. The calculations make use of lattice data generated on supercomputers that has already been successfully employed in lattice studies of spatial quark distributions (''nucleon tomography''). In order to be able to analyze transverse momentum dependent parton distribution functions, this thesis explores a novel approach based on non-local operators. One interesting observation is that the transverse momentum dependent density of polarized quarks in a polarized nucleon is visibly deformed. A more elaborate operator geometry is required to enable a quantitative comparison to high energy scattering experiments. First steps in this direction are encouraging. (orig.)
Strangeness and the quark-gluon plasma: An experimenter's perspective
International Nuclear Information System (INIS)
Odyniec, G.
1994-02-01
Current status of experimental results on strange particle production in relativistic nucleus-nucleus collisions is reviewed. Emphasis is placed on the relevance to the hypothetical quark-gluon plasma formation and the origin of the Universe
The LPM effect in sequential bremsstrahlung: 4-gluon vertices
Energy Technology Data Exchange (ETDEWEB)
Arnold, Peter; Chang, Han-Chih [Department of Physics, University of Virginia,382 McCormick Road, Charlottesville, Virginia 22904-4714 (United States); Iqbal, Shahin [National Centre for Physics, Quaid-i-Azam University Campus, Islamabad, 45320 (Pakistan)
2016-10-24
The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue study of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper completes the calculation of the rate for real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; q̂ approximation; and large N{sub c}) by now including processes involving 4-gluon vertices.
Resummation and the gluon damping rate in hot QCD
International Nuclear Information System (INIS)
Pisarski, R.D.
1990-08-01
At high temperature a consistent perturbative expansion requires the resummation of an infinite subset of loop corrections into an effective expansion. This effective exansion is used to compute the gluon damping rate at leading order. 25 refs
Differences between quark and gluon jets at LEP1
Boutemeur, Madjid
1997-01-01
A report is ven here on the differences between quark and gluon initiated jets as measured in LEPl. Various measurements, agree qualitatively on the differences between quark and gluon jets. However a direct quantitative comparison among the measurements as well as comparisons between the measurements and analytical calculations are difficult. This is due to the dependence of the results on the selected event topologies and used jet finding algorithms. Topology dependence of the charged particle multiplicity in quark and gluon jets is studied by ALEPH and transverse momentum-like scales are proposed to account for it. OPAL produced the first quantitative test of QCD analytic prediction for the ratio of the mean particle multiplicity between gluon and quark jets valid, at least, for 39 GeV jets.
A new method for computing the quark-gluon vertex
International Nuclear Information System (INIS)
Aguilar, A C
2015-01-01
In this talk we present a new method for determining the nonperturbative quark-gluon vertex, which constitutes a crucial ingredient for a variety of theoretical and phenomenological studies. This new method relies heavily on the exact all-order relation connecting the conventional quark-gluon vertex with the corresponding vertex of the background field method, which is Abelian-like. The longitudinal part of this latter quantity is fixed using the standard gauge technique, whereas the transverse is estimated with the help of the so-called transverse Ward identities. This method allows the approximate determination of the nonperturbative behavior of all twelve form factors comprising the quark-gluon vertex, for arbitrary values of the momenta. Numerical results are presented for the form factors in three special kinematical configurations (soft gluon and quark symmetric limit, zero quark momentum), and compared with the corresponding lattice data. (paper)
Quantum chromodynamics as effective theory of quarks and composite gluons
International Nuclear Information System (INIS)
Fuss, T.
2004-01-01
The dynamics of quarks is described by a nonperturbatively regularized NJL model which is canonically quantized and fulfil a probability interpretation. The quantum field theory of this model is formulated in a functional space. The wave functions of the quarks and gluons are calculated as eigenstates of Hard-Core equations and the gluons are considered as relativistic bound states of colored quark-antiquark pairs. The effective dynamics of the quarks and gluons is derived from weak mapping in functional space. This leads to the functional formulation of the phenomenological SU(3) local gauge invariant quark-gluon equations in temporal gauge. This means that the local gauge symmetry is a dynamical effect resulting from the quark model
Time evolution of the quark-gluon plasma
International Nuclear Information System (INIS)
Cooper, F.; New Hampshire Univ., Durham, NH
1993-01-01
We review progress in our understanding the production and time evolution of the quark gluon plasma starting with boost invariant initial conditions in a filed theory model based on the Schwinger mechanism of particle production via tunneling
On the application of gluon to heavy quarkonium fragmentation function
International Nuclear Information System (INIS)
Qi Wei; Wang Jianxiong
2007-01-01
We analyze the uncertainties induced by different definitions of the momentum fraction z in the application of gluon to heavy quarkonium fragmentation function. We numerically calculate the initial g→J/ψ fragmentation functions by using the non-covariant definitions of z with finite gluon momentum and find that these fragmentation functions have strong dependence on the gluon momentum k. As |k|→∞, these fragmentation functions approach to the fragmentation function in the light-cone definition. We find that when |k| is small (for instance in the typical energy scale (about 4-20GeV) of the gluon production at the hadron colliders, such as Tevatron and LHC), large uncertainty remains while the in-covariant definitions of z are employed in the application of the fragmentation functions. (authors)
Strangeness Production in a Chemically Equilibrating Quark-Gluon Plasma
Institute of Scientific and Technical Information of China (English)
HE Ze-Jun; LONG Jia-Li; MA Yu-Gang; MA Guo-Liang
2004-01-01
@@ We study the strangeness of a chemically equilibrating quark-gluon plasma at finite baryon density based on the and will accelerate with the change of the initial system from a chemically non-equilibrated to an equilibrated system. We also find that the calculated strangeness is very different from the one in the thermodynamic equilibrium system. This study may be helpful to understand the formation of quark-gluon plasma via a chemically non-equilibrated evolution framework.
The five-gluon amplitude and one-loop integrals
International Nuclear Information System (INIS)
Bern, Z.; Dixon, L.; Kosower, D.A.
1992-12-01
We review the conventional field theory description of the string motivated technique. This technique is applied to the one-loop five-gluon amplitude. To evaluate the amplitude a general method for computing dimensionally regulated one-loop integrals is outlined including results for one-loop integrals required for the pentagon diagram and beyond. Finally, two five-gluon helicity amplitudes are given
On γ5 in higher-order QCD calculations and the NNLO evolution of the polarized valence distribution
International Nuclear Information System (INIS)
Moch, S.; Vogt, A.
2015-06-01
We discuss the prescription for the Dirac matrix γ 5 in dimensional regularization used in most second- and third-order QCD calculations of collider cross sections. We provide an alternative implementation of this approach that avoids the use of an explicit form of γ 5 and of its (anti-) commutation relations in the most important case of no more than one γ 5 in each fermion trace. This treatment is checked by computing the third-order corrections to the structure functions F 2 and g 1 in charged-current deep-inelastic scattering with axial-vector couplings to the W-bosons. We derive the so far unknown third-order helicity-difference splitting function ΔP ns (2)s that contributes to the next-to-next-to-leading order (NNLO) evolution of the polarized valence quark distribution of the nucleon. This function is negligible at momentum fractions x>or similar 0.3 but relevant at x<<1.
McGawley, Kerry; Juudas, Elisabeth; Kazior, Zuzanna; Ström, Kristoffer; Blomstrand, Eva; Hansson, Ola; Holmberg, Hans-Christer
2017-01-01
Introduction: The current study aimed to investigate the responses to block- versus evenly-distributed high-intensity interval training (HIT) within a polarized microcycle. Methods: Twenty well-trained junior cross-country skiers (10 males, age 17.6 ± 1.5 and 10 females, age 17.3 ± 1.5) completed two, 3-week periods of training (EVEN and BLOCK) in a randomized, crossover-design study. In EVEN, 3 HIT sessions (5 × 4-min of diagonal-stride roller-skiing) were completed at a maximal sustainable intensity each week while low-intensity training (LIT) was distributed evenly around the HIT. In BLOCK, the same 9 HIT sessions were completed in the second week while only LIT was completed in the first and third weeks. Heart rate (HR), session ratings of perceived exertion (sRPE), and perceived recovery (pREC) were recorded for all HIT and LIT sessions, while distance covered was recorded for each HIT interval. The recovery-stress questionnaire for athletes (RESTQ-Sport) was completed weekly. Before and after EVEN and BLOCK, resting saliva and muscle samples were collected and an incremental test and 600-m time-trial (TT) were completed. Results: Pre- to post-testing revealed no significant differences between EVEN and BLOCK for changes in resting salivary cortisol, testosterone, or IgA, or for changes in muscle capillary density, fiber area, fiber composition, enzyme activity (CS, HAD, and PFK) or the protein content of VEGF or PGC-1α. Neither were any differences observed in the changes in skiing economy, [Formula: see text] or 600-m time-trial performance between interventions. These findings were coupled with no significant differences between EVEN and BLOCK for distance covered during HIT, summated HR zone scores, total sRPE training load, overall pREC or overall recovery-stress state. However, 600-m TT performance improved from pre- to post-training, irrespective of intervention ( P = 0.003), and a number of hormonal and muscle biopsy markers were also significantly
International Nuclear Information System (INIS)
Kaempfer, B.; Technische Univ. Dresden; Pavlenko, O.P.; AN Ukrainskoj SSR, Kiev; Gorenstein, M.I.; Peshier, A.; Soff, G.
1994-07-01
The influence of a non-vanishing baryon charge on the rapidity distribution of dileptons produced in ultrarelativistic heavy-ion collisions is studied. We employ a frozen motion model with scaling invariant expansion of the hadronizing quark-gluon plasma as well as a realistic rapidity distribution of secondary particles (i.e., pions and baryons) expected for RHIC energies. We find a considerable suppression of the dilepton production yield at large rapidities due to the finite baryon density. To discriminate the thermal dileptons from Drell-Yan background we propose to utilize the dilepton yield scaled suitably by the pion multiplicity as function of rapidity. (orig.)
Quarks and gluons in hadrons and nuclei
International Nuclear Information System (INIS)
Close, F.E.
1989-01-01
These lectures discuss the particle-nuclear interface -- a general introduction to the ideas and application of colored quarks in nuclear physics, color, the Pauli principle, and spin flavor correlations -- this lecture shows how the magnetic moments of hadrons relate to the underlying color degree of freedom, and the proton's spin -- a quark model perspective. This lecture reviews recent excitement which has led some to claim that in deep inelastic polarized lepton scattering very little of the spin of a polarized proton is due to its quarks. 38 refs
TMD splitting functions in kT factorization. The real contribution to the gluon-to-gluon splitting
International Nuclear Information System (INIS)
Hentschinski, M.; Kusina, A.; Kutak, K.; Serino, M.
2018-01-01
We calculate the transverse momentum dependent gluon-to-gluon splitting function within k T -factorization, generalizing the framework employed in the calculation of the quark splitting functions in Hautmann et al. (Nucl Phys B 865:54-66, arXiv:1205.1759, 2012), Gituliar et al. (JHEP 01:181, arXiv:1511.08439, 2016), Hentschinski et al. (Phys Rev D 94(11):114013, arXiv:1607.01507, 2016) and demonstrate at the same time the consistency of the extended formalism with previous results. While existing versions of k T factorized evolution equations contain already a gluon-to-gluon splitting function i.e. the leading order Balitsky-Fadin-Kuraev-Lipatov (BFKL) kernel or the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) kernel, the obtained splitting function has the important property that it reduces both to the leading order BFKL kernel in the high energy limit, to the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) gluon-to-gluon splitting function in the collinear limit as well as to the CCFM kernel in the soft limit. At the same time we demonstrate that this splitting kernel can be obtained from a direct calculation of the QCD Feynman diagrams, based on a combined implementation of the Curci-Furmanski-Petronzio formalism for the calculation of the collinear splitting functions and the framework of high energy factorization. (orig.)
Co-distribution of seabirds and their polar cod prey near the ice edge in southern Baffin Bay
DEFF Research Database (Denmark)
LeBlanc, Mathieu; Gauthier, S; Mosbech, Anders
species, and age-1 polar cod found in bird stomachs were likely individuals associated to ice. At a large scale of hundreds of kilometers, seabirds and age-0 polar cod were more abundant in ice-covered habitats (30 to 100% ice concentration). At medium and small scale of 12.5 and 1 km respectively...
Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju
2012-09-01
The event-by-event multiplicity distribution, the energy densities and energy density weighted eccentricity moments ɛn (up to n=6) at early times in heavy-ion collisions at both the BNL Relativistic Heavy Ion Collider (RHIC) (s=200GeV) and the CERN Large Hardron Collider (LHC) (s=2.76TeV) are computed in the IP-Glasma model. This framework combines the impact parameter dependent saturation model (IP-Sat) for nucleon parton distributions (constrained by HERA deeply inelastic scattering data) with an event-by-event classical Yang-Mills description of early-time gluon fields in heavy-ion collisions. The model produces multiplicity distributions that are convolutions of negative binomial distributions without further assumptions or parameters. In the limit of large dense systems, the n-particle gluon distribution predicted by the Glasma-flux tube model is demonstrated to be nonperturbatively robust. In the general case, the effect of additional geometrical fluctuations is quantified. The eccentricity moments are compared to the MC-KLN model; a noteworthy feature is that fluctuation dominated odd moments are consistently larger than in the MC-KLN model.
Letter of Intent for a Drell-Yan Experiment with a Polarized Proton Target
International Nuclear Information System (INIS)
Geesaman, D.; Reimer, P.; Brown, C.; Christian, D.; Diefenthaler, M.; Peng, J.C.; Chang, W.C.; Chen, Y.C.; Sawada, S.; Chang, T.H.; Huang, J.; Jiang, X.; Leitch, M.; Klein, A.; Liu, K.; Liu, M.; McGaughey, P.; Beise, E.; Nakahara, K.; Aidala, C.; Lorenzon, W.; Raymond, R.; Badman, T.; Long, E.; Slifer, K.; Zielinski, R.; Guo, R.S.; Goto, Y.; El Fassi, L.; Myers, K.; Ransome, R.; Tadepalli, A.; Tice, B.; Chen, J.P.; Nakano, K.; Shibata, T.A.; Crabb, D.; Day, D.; Keller, D.; Rondon, O.
2014-01-01
It is well known that the proton is a spin-1/2 particle, but how the constituents (quarks and gluons) assemble to this quantized spin is still a mystery. There is a worldwide effort to map out the individual contributions to the proton spin. It is established that the quark spins contribute around 30%, while the gluon intrinsic angular momentum is still under active investigation at the Relativistic Heavy Ion Collider. Fully resolving the proton spin puzzle requires information on the orbital angular momentum (OAM) of both quarks and gluons. Recent studies have shown that the so-called transverse momentum-dependent parton distribution functions (TMDs) can inform us about the OAM of the partons. One of the most important TMDs, and the main focus of this LOI, is the so-called Sivers function. To summarize, we propose to make the first measurement of the Sivers function of sea quarks, which is expected to be non-zero if the sea quarks contribute orbital angular momentum to the proton spin, as expected from the pion cloud model, which also partially explains the E866 results. Thus, we will be able to deduce whether or not sea quark orbital motion contributes significantly to the proton spin. Specifically, we will determine the contribution from the anti-up quarks, with Bjorken-x in the range of ~ 0.1 to 0.5. Drell-Yan production off a polarized proton target has never been measured, and is complementary to the recently approved (stage-1) experiment E1027 at Fermilab, which will measure the Sivers function of the valence quarks using a polarized proton beam on an unpolarized proton target. If the measured sea quark Sivers function is non-zero, we will also determine its sign.
Ilyushin, Yaroslaw; Kutuza, Boris
Observations and mapping of the upwelling thermal radiation of the Earth is the very promising remote sensing technique for the global monitoring of the weather and precipitations. For reliable interpretation of the observation data, numerical model of the microwave radiative transfer in the precipitating atmosphere is necessary. In the present work, numerical simulations of thermal microwave radiation in the rain have been performed at three wavelengths (3, 8 and 22 mm). Radiative properties of the rain have been simulated using public accessible T-matrix codes (Mishchenko, Moroz) for non-spherical particles of fixed orientation and realistic raindrop size distributions (Marshall-Palmer) within the range of rain intensity 1-100 mm/h. Thermal radiation of infinite flat slab medium and isolated rain cell of kilometer size has been simulated with finite difference scheme for the vectorial radiative transfer equation (VRTE) in dichroic scattering medium. Principal role of cell structure of the rain field in the formation of angular and spatial distribution of the intensity and polarization of the upwelling thermal radiation has been established. Possible approaches to interpretation of satellite data are also discussed. It is necessary that spatial resolution of microwave radiometers be less than rain cell size. At the present time the resolution is approximately 15 km. It can be considerably improved, for example by two-dimensional synthetic aperture millimeter-wave radiometric interferometer for measuring full-component Stokes vector of emission from hydrometeors. The estimates show that in millimeter band it is possible to develop such equipment with spatial resolution of the order of 1-2 km, which is significantly less than the size of rain cell, with sensitivity 0.3-0.5 K. Under this condition the second Stokes parameter may by successfully measured and may be used for investigation of precipitation regions. Y-shaped phased array antenna is the most promising to
Evidence of ghost suppression in gluon mass scale dynamics
Aguilar, A. C.; Binosi, D.; Figueiredo, C. T.; Papavassiliou, J.
2018-03-01
In this work we study the impact that the ghost sector of pure Yang-Mills theories may have on the generation of a dynamical gauge boson mass scale, which hinges on the appearance of massless poles in the fundamental vertices of the theory, and the subsequent realization of the well-known Schwinger mechanism. The process responsible for the formation of such structures is itself dynamical in nature, and is governed by a set of Bethe-Salpeter type of integral equations. While in previous studies the presence of massless poles was assumed to be exclusively associated with the background-gauge three-gluon vertex, in the present analysis we allow them to appear also in the corresponding ghost-gluon vertex. The full analysis of the resulting Bethe-Salpeter system reveals that the contribution of the poles associated with the ghost-gluon vertex are particularly suppressed, their sole discernible effect being a slight modification in the running of the gluon mass scale, for momenta larger than a few GeV. In addition, we examine the behavior of the (background-gauge) ghost-gluon vertex in the limit of vanishing ghost momentum, and derive the corresponding version of Taylor's theorem. These considerations, together with a suitable Ansatz, permit us the full reconstruction of the pole sector of the two vertices involved.
Lie, E.; Bernhoft, A.; Riget, F.; Belikov, Stanislav; Boltunov, Andrei N.; Derocher, A.E.; Garner, G.W.; Wiig, O.; Skaare, J.U.
2003-01-01
Geographical variation of organochlorine pesticides (OCPs) was studied in blood samples from 90 adult female polar bear (Ursus maritimus) from Svalbard, Franz Josef Land, Kara Sea, East-Siberian Sea and Chukchi Sea. In all regions, oxychlordane was the dominant OCP. Regional differences in mean levels of HCB, oxychlordane, trans-nonachlor, ??-HCH, ??-HCH and p,p???-DDE were found. The highest levels of oxychlordane, trans-nonachlor and DDE were found in polar bears from Franz Josef Land and Kara Sea. HCB level was lowest in polar bears from Svalbard. Polar bears from Chukchi Sea had the highest level of ??- and ??-HCH. The lowest ??-HCH concentration was found in bears from Kara Sea. In all the bears, ???HCHs was dominated by ??-HCH. The geographical variation in OCP levels and pattern may suggest regional differences in pollution sources and different feeding habits in the different regions. Polar bears from the Western Russian Arctic were exposed to higher levels of chlordanes and p,p???-DDE than polar bears from locations westwards and eastwards from this region. This may imply the presence of a significant pollution source in the Russian Arctic area. The study suggests that the western Russian Arctic is the most contaminated region of the Arctic and warrants further research. ?? 2002 Elsevier Science B.V. All rights reserved.
International Nuclear Information System (INIS)
Rindani, Saurabh D.; Sharma, Pankaj
2009-01-01
We examine the contribution of general Z*ZH and γ*ZH three-point interactions arising from new physics to the Higgs production process e + e - →HZ. From Lorentz covariance, each of these vertices may be written in terms of three (complex) form factors, whose real and imaginary parts together make six independent couplings. We take into account possible longitudinal or transverse beam polarization likely to be available at a linear collider. We show how partial cross sections and angular asymmetries in suitable combinations with appropriate beam polarizations can be used to disentangle various couplings from one another. A striking result is that using transverse polarization, one of the γZH couplings, not otherwise accessible, can be determined independently of all other couplings. Transverse polarization also helps in the independent determination of a combination of two other couplings, in contrast to a combination of four accessible with unpolarized or longitudinally polarized beams. We also obtain the sensitivity of the various observables in constraining the new-physics interactions at a linear collider operating at a center-of-mass energy of 500 GeV with longitudinal or transverse polarization.
Measurements of gluon spin-sensitive quantities at the Z0 resonance
International Nuclear Information System (INIS)
Fan, C.G.
1993-10-01
Measurements have been made of the scaled jet energies (x 1 , x 2 , x 3 ) and the Ellis-Karliner angle (cosθ EK ), which are sensitive to the spill of the gluon, in the 3-jet hadronic events from the e + e - annihilation at the Z 0 resonance. The experiment is performed with the SLD detector at the Stanford Linear Accelerator Center (SLAC). The data used in this analysis was collected during the 1992 physics run, which includes 10,252 hadronic Z 0 events that have CDC information written out. Only charged tracks measured in the central drift chamber are used for the measurements of the above variables. The raw data are found to be in good agreement with the Monte Carlo simulations passing the same set of track and event selection cuts. A bin-to-bin correction is done for the distributions of x 1 , x 2 , x 3 , and cosθ EK to account for the effects of hadronization, detector acceptance and resolution. The corrected data is compared to the parton level distributions of x 1 , x 2 , x 3 , and cosθ EK simulated from the vector QCD model and the scalar gluon model respectively. The systematic errors, calculated for all the bins in these distributions, are obtained by comparing the results from different sets of track and event selection cuts, from different hadronization models and from different Monte Carlo programs. Good agreement is found between data and the vector QCD model. The scalar gluon model strongly disagrees with the data
Measurements of gluon spin-sensitive quantities at the Z^{0} resonance
Energy Technology Data Exchange (ETDEWEB)
Fan, Cheng -Gang [Stanford Univ., CA (United States)
1993-10-01
Measurements have been made of the scaled jet energies (x_{1}, x_{2}, x_{3}) and the Ellis-Karliner angle (cosθ_{EK}), which are sensitive to the spill of the gluon, in the 3-jet hadronic events from the e^{+}e^{-} annihilation at the Z^{0} resonance. The experiment is performed with the SLD detector at the Stanford Linear Accelerator Center (SLAC). The data used in this analysis was collected during the 1992 physics run, which includes 10,252 hadronic Z^{0} events that have CDC information written out. Only charged tracks measured in the central drift chamber are used for the measurements of the above variables. The raw data are found to be in good agreement with the Monte Carlo simulations passing the same set of track and event selection cuts. A bin-to-bin correction is done for the distributions of x_{1}, x_{2}, x_{3}, and cosθ_{EK} to account for the effects of hadronization, detector acceptance and resolution. The corrected data is compared to the parton level distributions of x_{1}, x_{2}, x_{3}, and cosθ_{EK} simulated from the vector QCD model and the scalar gluon model respectively. The systematic errors, calculated for all the bins in these distributions, are obtained by comparing the results from different sets of track and event selection cuts, from different hadronization models and from different Monte Carlo programs. Good agreement is found between data and the vector QCD model. The scalar gluon model strongly disagrees with the data.
Infrared Behavior of Gluon and Ghost Propagators in Landau Gauge QCD
International Nuclear Information System (INIS)
von Smekal, L.; Hauck, A.; Alkofer, R.
1997-01-01
A truncation scheme for the Dyson-Schwinger equations of Euclidean QCD in Landau gauge is presented. It implements the Slavnov-Taylor identities for the three-gluon and ghost-gluon vertices, whereas irreducible four-gluon couplings as well as the gluon-ghost and ghost-ghost scattering kernels are neglected. The infrared behavior of gluon and ghost propagators is obtained analytically: The gluon propagator vanishes for small momenta, whereas the ghost propagator diverges strongly. The numerical solutions are compared with recent lattice results. The running coupling approaches a fixed point, α c ≅9.5 , in the infrared. copyright 1997 The American Physical Society
NLO QCD corrections to Higgs boson production plus three jets in gluon fusion
Energy Technology Data Exchange (ETDEWEB)
Cullen, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Deurzen, H. van; Greiner, N.; Luisoni, G.; Mirabella, E.; Peraro, T. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Mastrolia, P. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Padova Univ. (Italy). Dipt. di Fisica e Astronomia; INFN, Sezione di Padova (Italy); Ossola, G. [New York Univ., NY (United States). New York City College of Technology; New York Univ., NY (United States). The Graduate School and University Center; Tramontano, F. [Napoli Univ. (Italy). Dipt. di Fisica; INFN, Sezione di Napoli (Italy)
2013-07-15
We report on the calculation of the cross section for Higgs boson production in association with three jets via gluon fusion, at next-to-leading-order (NLO) accuracy in QCD, in the infinite top-mass approximation. After including the complete NLO QCD corrections, we observe a strong reduction in the scale dependence of the result, and an increased steepness in the transverse momentum distributions of both the Higgs and the leading jets. The results are obtained with the combined use of GoSam, Sherpa, and the MadDipole/MadEvent framework.
Virtual photoproduction of hadrons at large p/sub T/ as a probe for gluon bremsstrahlung
Floratos, Emmanuel G
1978-01-01
In a SU/sub 3, colour/ x SU/sub 3, flavour/ invariant interaction of quarks and gluons, where the colour degree of freedom is locally gauged, first-order corrections of the naive parton model are calculated for the one-hadron inclusive virtual photoproduction. The high p/sub T/ distribution of hadrons is studied and the kinetical region in which the prediction of the model dominates over the fall- off approximately exp(-bp/sub T//sup 2/) which seems to be supported by the low-p/sub T/ available experimental data is determined. (29 refs).
Transport quasiparticles and transverse interactions in quark-gluon plasmas
International Nuclear Information System (INIS)
Baym, Gordon
1996-01-01
Calculations of the properties of interacting quark-gluon plasmas are beset by infrared divergences associated with the fact that magnetic interactions, i.e., those occurring through exchange of transverse gluons, are, in the absence of a 'magnetic mass''in QCD, not screened. In this lecture we discuss the effects of magnetic interactions on the transport coefficients and the quasiparticle structure of quark-gluon plasmas. We describe how inclusion of dynamical screening effects - corresponding to Landau damping of the virtual quanta exchanged - leads to finite transport scattering rates. In the weak coupling limit, dynamical screening effects dominate over a magnetic mass. We illustrate the breakdown of the quasi particle structure of degenerate plasmas caused by long-ranged magnetic interactions, describe the structure of fermion quasiparticles in hot relativistic plasmas, and touch briefly on the problem of the lifetime of quasiparticle in the presence of long-ranged magnetic interactions. (author)
Worldline calculation of the three-gluon vertex
International Nuclear Information System (INIS)
Ahmadiniaz, N.; Schubert, C.
2012-01-01
The three-gluon vertex is a basic object of interest in nonabelian gauge theory. At the one-loop level, it has been calculated and analyzed by a number of authors. Here we use the worldline formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in terms of field strength tensors. We verify its equivalence with previously obtained representations, and explain the relation of its structure to the low-energy effective action. The sum rule found by Binger and Brodsky for the scalar, spinor and gluon loop contributions in the present approach relates to worldline supersymmetry.
Neural network classification of quark and gluon jets
International Nuclear Information System (INIS)
Graham, M.A.; Jones, L.M.; Herbin, S.
1995-01-01
We demonstrate that there are characteristics common to quark jets and to gluon jets regardless of the interaction that produced them. The classification technique we use depends on the mass of the jet as well as the center-of-mass energy of the hard subprocess that produces the jet. In addition, we present the quark-gluon separability results of an artificial neural network trained on three-jet e + e - events at the Z 0 mass, using a back-propagation algorithm. The inputs to the network are the longitudinal momenta of the leading hadrons in the jet. We tested the network with quark and gluon jets from both e + e - →3 jets and bar pp→2 jets. Finally, we compare the performance of the artificial neural network with the results of making well chosen physical cuts
The gluon Reggeization in perturbative QCD at NLO
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Fadin, V.S. [Novosibirsk State Univ., Institute for Nuclear Physics (Russian Federation)
2005-07-01
The gluon Reggeization is one of the outstanding properties of QCD. It is extremely important for description of high energy processes. In particular, it appears as the basis of the BFKL approach to summation of the terms strengthened by powers of log(1/x). The hypothesis is extremely powerful, since all scattering amplitudes are expressed in terms of the gluon trajectory and several Reggeon vertices. Now the hypothesis is proved in NLA (next-to leading approximation). The proof is based on bootstrap relations. It is shown that an infinite number of these relations is reduced to several bootstrap conditions on the gluon trajectory and the Reggeon vertices. It is shown that fulfillment of these conditions means a proof of the Reggeization hypothesis. All bootstraps conditions are formulated explicitly and are proved to be fulfilled.
Non-perturbative power corrections to ghost and gluon propagators
International Nuclear Information System (INIS)
Boucaud, Philippe; Leroy, Jean-Pierre; Yaouanc, Alain Le; Lokhov, Alexey; Micheli, Jacques; Pene, Olivier; RodrIguez-Quintero, Jose; Roiesnel, Claude
2006-01-01
We study the dominant non-perturbative power corrections to the ghost and gluon propagators in Landau gauge pure Yang-Mills theory using OPE and lattice simulations. The leading order Wilson coefficients are proven to be the same for both propagators. The ratio of the ghost and gluon propagators is thus free from this dominant power correction. Indeed, a purely perturbative fit of this ratio gives smaller value ( ≅ 270MeV) of Λ M-barS-bar than the one obtained from the propagators separately( ≅ 320MeV). This argues in favour of significant non-perturbative ∼ 1/q 2 power corrections in the ghost and gluon propagators. We check the self-consistency of the method
Low-momentum ghost dressing function and the gluon mass
International Nuclear Information System (INIS)
Boucaud, Ph.; Leroy, J. P.; Le Yaouanc, A.; Micheli, J.; Pene, O.; Gomez, M. E.; Rodriguez-Quintero, J.
2010-01-01
We study the low-momentum ghost propagator Dyson-Schwinger equation in the Landau gauge, assuming for the truncation a constant ghost-gluon vertex, as it is extensively done, and a simple model for a massive gluon propagator. Then, regular Dyson-Schwinger equation solutions (the zero-momentum ghost dressing function not diverging) appear to emerge, and we show the ghost propagator to be described by an asymptotic expression reliable up to the order O(q 2 ). That expression, depending on the gluon mass and the zero-momentum Taylor-scheme effective charge, is proven to fit pretty well some low-momentum ghost propagator data [I. L. Bogolubsky, E. M. Ilgenfritz, M. Muller-Preussker, and A. Sternbeck, Phys. Lett. B 676, 69 (2009); Proc. Sci., LAT2007 (2007) 290] from big-volume lattice simulations where the so-called ''simulated annealing algorithm'' is applied to fix the Landau gauge.
Transverse momentum of gluons in ep-scattering at HERA
International Nuclear Information System (INIS)
Cholewa, A.
2005-11-01
A Monte Carlo analysis of the phase space of hard interacting gluons in ep-scattering is presented. The event generator CASCADE is used in combination with the program HZTOOL to identify the accessible regions of phase space of present HERA measurements. A map of the k t -x g -plane is presented to show that in the region -3≤log g ≤-1 transverse gluon momenta of up to k t >or sim 20 GeV are accessible to HERA measurements. Furthermore the observables x γ and the transverse jet energy E T are found to be highly sensitive to the transverse momentum and the longitudinal momentum fraction of gluons. (orig.) (orig.)
In search of the quark-gluon plasma
International Nuclear Information System (INIS)
Schutz, Y.; Delagrange, H.
2002-01-01
This article describes in a very pedagogical manner the ultimate state of matter when quarks are no longer confined in hadrons. This state is called quark and gluon plasma, its existence is suspected through 4 facts: 1) a quark and gluon plasma that has just been created from a high energy ion-collision is mainly made up of light quarks (up and down), then this plasma should evolve towards other quarks (particularly strange quarks) because of the Pauli exclusion principle. This fact has been experimentally confirmed: at the CERN accelerator physicists have detected a higher production of strange hadrons when the energy of the collision increases; 2) some particles like ρ 0 mesons, that are made up of 2 quarks, are massively produced in ion collisions, their mass has been measured at the moment of the collision and later in the quark and gluon plasma, 2 different values have been found so it confirms the theory that predicts that free quarks have a mass that decreases as energy increases; 3) J/Ψ mesons are made up of a charmed quark combined with its anti-quark, physicists have noticed that less J/Ψ mesons are detected when the energy of the collision rises, this result agrees with the fact that in quark gluon plasma where quarks are free and of different colours and flavors, it is highly unlikely that a charmed quark combines with its anti-quark to form a J/Ψ meson; and 4) the theory of the formation of quark gluon plasma predicts that its electromagnetic radiation has a thermal radiation specificity, physicists have studied the radiation spectra emitted in the core of a ion collision, they have shown that it is a thermal radiation and that the temperature of the emitter corresponds to the temperature of a quark gluon plasma. (A.C.)
D'Eramo, Francesco; Liu, Hong; Rajagopal, Krishna
2013-01-01
We calculate P(k_\\perp), the probability distribution for an energetic parton that propagates for a distance L through a medium without radiating to pick up transverse momentum k_\\perp, for a medium consisting of weakly coupled quark-gluon plasma. We use full or HTL self-energies in appropriate regimes, resumming each in order to find the leading large-L behavior. The jet quenching parameter \\hat q is the second moment of P(k_\\perp), and we compare our results to other determinations of this quantity in the literature, although we emphasize the importance of looking at P(k_\\perp) in its entirety. We compare our results for P(k_\\perp) in weakly coupled quark-gluon plasma to expectations from holographic calculations that assume a plasma that is strongly coupled at all length scales. We find that the shape of P(k_\\perp) at modest k_\\perp may not be very different in weakly coupled and strongly coupled plasmas, but we find that P(k_\\perp) must be parametrically larger in a weakly coupled plasma than in a strongl...
Internal Spin Structure of the Nucleon in Polarized Deep Inelastic Muon-Nucleon Scattering
International Nuclear Information System (INIS)
Wislicki, W.
1998-01-01
We present the study of the internal spin structure of the nucleon in spin-dependent deep inelastic scattering of muons on nucleons. The data were taken by the NA47 experiment of the Spin Muon Collaboration (SMC) on the high energy muon beam at CERN. The experiment used the polarized proton and deuteron targets. The structure function g 1 p (x) and g 1 d (x) were determined from the asymmetries of the spin-dependent event rates in the range of 0.003 2 >=10 GeV 2 . Using the first moments of these structure functions an agreement with the Bjorken sum rule prediction was found within one standard deviation. The first moments of g 1 (x), for both proton and deuteron, are smaller than the Ellis-Jaffe sum rule prediction. This disagreement can be interpreted in terms of negative polarization of the strange sea in the nucleon. The singlet part of the axial current matrix element can be interpreted as an overall spin carried by quarks in the nucleon. Its value is significantly smaller than nucleon spin. Semi-inclusive asymmetries of yields of positive and negative hadrons produced on both targets were also measured and analysed in term of quark-parton model, together with inclusive asymmetries. From this analysis the quark spin distributions were determined, separately for valence u and d quarks and for non-strange sea quarks. Valence u quarks are positively polarized and their polarization increases with x. Valence d quarks are negatively polarized and their polarization does not exhibit any x-dependence. The non-strange sea is unpolarized in the whole measured range of x. The first moments of the valance quark spin distributions were found consistent with the values obtained from weak decay constants F and D and their second moments are consistent with lattice QCD calculations. In the QCD analysis of the world data the first moment of the gluon spin distribution was found with a large error. Also, a search for a non-perturbative anomaly at high x was done on the world
A gauge quantum field theory of confined quarks and gluons
International Nuclear Information System (INIS)
Voelkel, A.H.
1983-01-01
A SU(3)-gauge quantum field theory with a quark triplet, an antiquark triplet and a self-conjugate gluon octet as basic fields is investigated. In virtue of a non trivial coupling between the representation of the translation group and the SU(3)-colour charge of the basic fields it is proved: (i) The basic quark, antiquark and gluon fields are confined. (ii) Every statevector of the physical Hilbert space is a SU(3)-colour singlet state. (iii) Poincare invariance holds in the physical Hilbert space. (orig.)
Evidence for a spin 1 gluon in three jet events
International Nuclear Information System (INIS)
Brandelik, R.; Braunschweig, W.; Gather, K.; Kadansky, V.; Kirschfink, F.J.; Luebelsmeyer, K.; Martyn, H.U.; Peise, G.; Rimkus, J.; Sander, H.G.
1980-08-01
High energy e + e - annihilation events obtained in the TASSO detector at PETRA have been used to determine the spin of the gluon in the reaction e + e - → q anti qg. We analyzed angular correlations between the 3 jet axes. While vector gluons are consistent with the data (55% confidence limit), scalar fluons are disfavored by 3.8 standard deviations, corresponding to a confidence level of about 10 -4 . Our conclusion is free of possible biases due to uncertainties in the fragmentation process or in determining the q anti qg kinematic from the observed hadrons. (orig.)
The hard gluon component of the QCD Pomeron
International Nuclear Information System (INIS)
White, A.R.
1996-01-01
The authors argue that deep-inelastic diffractive scaling provides fundamental insight into the QCD Pomeron. The logarithmic scaling violations seen experimentally are in conflict with the scale-invariance of the BFKL Pomeron and with phenomenological two-gluon models. Instead the Pomeron appears as a single gluon at short-distances, indicating the appearance of a Super-Critical phase of Reggeon Field Theory. That the color compensation takes place at a longer distance is consistent with the Pomeron carrying odd color charge parity
Check of the bootstrap conditions for the gluon Reggeization
International Nuclear Information System (INIS)
Papa, A.
2000-01-01
The property of gluon Reggeization plays an essential role in the derivation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at high energy √s in perturbative QCD. This property has been proved to all orders of perturbation theory in the leading logarithmic approximation and it is assumed to be valid also in the next-to-leading logarithmic approximation, where it has been checked only to the first three orders of perturbation theory. From s-channel unitarity, however, very stringent 'bootstrap' conditions can be derived which, if fulfilled, leave no doubts that gluon Reggeization holds
'' Ideal Gas '' gluon plasma with medium dependent dispersion relation
International Nuclear Information System (INIS)
Gorenstein, M.I.
1995-01-01
An '' ideal gas '' model with temperature dependent particle mass is constructed for the gluon plasma equation of state. This simple model gives us an example of a system with temperature dependent effective Hamiltonian. To satisfy thermodynamical relations in these systems, standard statistical mechanics formulas have to be supplemented by special requirements which are considered in details. A self-consistent '' ideal gas '' formulation is used to describe Monte Carlo lattice data for the thermodynamical functions of SU(2) and SU(3) gluon plasma. 14 refs., 8 figs
Plaquette expectation value and gluon condensate in three dimensions
International Nuclear Information System (INIS)
Hietanen, Ari; Kajantie, Keijo; Schroeder, York; Laine, Mikko; Rummukainen, Kari
2005-01-01
In three dimensions, the gluon condensate of pure SU(3) gauge theory has ultraviolet divergences up to 4-loop level only. By subtracting the corresponding terms from lattice measurements of the plaquette expectation value and extrapolating to the continuum limit, we extract the finite part of the gluon condensate in lattice regularization. Through a change of regularization scheme to MS-bar and (inverse) dimensional reduction, this result would determine the first non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure. (author)
Nielsen's identity and gluon condensation at finite temperature
International Nuclear Information System (INIS)
Skalozub, V.V.
1992-11-01
The gauge dependence problem of the gluon field zero component condensate, A 0 =const, is investigated in finite temperature SU(3) gluodynamics. The two-loop effective action W(A 0 ,ξ) is recalculated in the background R ξ gauge. The obtained result somewhat differs from that of other authors. By straightforward calculation it is shown that W(A 0 ,ξ) satisfies the Nielsen (the Ward type) identity. Thus, the gauge invariance of the gluon condensation phenomenon is proved. (author). 14 refs
Plaquette expectation value and gluon condensate in three dimensions
Hietanen, A; Laine, Mikko; Rummukainen, K; Schröder, Y
2005-01-01
In three dimensions, the gluon condensate of pure SU(3) gauge theory has ultraviolet divergences up to 4-loop level only. By subtracting the corresponding terms from lattice measurements of the plaquette expectation value and extrapolating to the continuum limit, we extract the finite part of the gluon condensate in lattice regularization. Through a change of regularization scheme to MSbar and (inverse) dimensional reduction, this result would determine the first non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure.
Energy Technology Data Exchange (ETDEWEB)
Kang, Hyejoo
2002-01-30
We present production measurements of the charged hadrons {pi}{sup {+-}}, K{sup {+-}} and p/{bar p} in e{sup +}e{sup -} interactions at the Z{sup 0} pole. The excellent particle identification capability of the SLC Large Detector (SLD) at the Stanford Linear Collider (SLC) are used. In addition to studies over a wide momentum range in hadronic Z{sup 0} events of all five flavors, we have made the most precise measurements in light (uds), c and b flavor events separately. Unambiguous flavor dependencies have been observed, and the results have been compared with the predictions of several QCD fragmentation models. We have also exploited the unique feature of electron beam polarization in our experiment to compare hadron production separately in quark and antiquark jets. Direct evidence that higher momentum hadrons are more likely to contain the primary quark and antiquark is seen, with precision sufficient to provide new model tests. Finally, we have studied hard gluon jets in detail. We have confirmed that gluon jets have a higher multiplicity of softer particles than light quark jets, and found this enhancement to be the same for {pi}{sup {+-}}, K{sup {+-}} and p/{bar p} at the few percent level at all momenta. Any overall difference in the hadron fractions is limited to 0.018 at the 95% confidence level, indicating that there are no differences at the hadronization stage in jet formation between gluons and quarks.
Yoon, Soo Jeong; Yoon, Dae Young; Lee, Hyung Jin; Baek, Sora; Lim, Kyoung Ja; Seo, Young Lan; Yun, Eun Joo
2017-08-01
The objective of this study was to assess the distribution of citations received by scientific papers published in the imaging literature between 2001 and 2010. We extracted the number of citations of all articles and reviews for 5 years after publication using the Scopus (Elsevier) citation database of imaging journals between 2001 and 2010. We quantitatively analyzed article and review citations from each journal and each year, including the number, proportion, and annual number of citations of the most- (≥ 20 citations) and least-cited (three or fewer citations) papers; ratio of most-cited to least-cited papers; 75/25 percentile citation ratio; 90/10 percentile citation ratio; Gini coefficient; and Kolkata index. Our analysis of 124,331 articles and 13,575 reviews from 121 journals showed that the proportion of most-cited articles (from 19.6% to 27.1%) and reviews (from 19.1% to 37.2%) increased from 2001 to 2010, whereas the proportion of least-cited articles (from 32.3% to 23.0%) and reviews (from 31.9% to 15.8%) declined over the same period. The annual numbers of citations of most-cited articles and reviews both reached a peak in the fourth year after publication, whereas those of least-cited articles and reviews reached a peak in the second and fist years, respectively, after publication and thereafter decreased. The 75/25 percentile ratio for articles declined from 41.1 to 27.5 between 2001 and 2010. Over the same time, the 75/25 percentile ratio for reviews declined from 47.4 to 22.9. The 90/10 percentile ratio for articles declined from 1730.8 to 188.7; for reviews, the 90/10 percentile ratio declined from 5788.0 to 100.7. The Gini coefficient of articles and reviews also declined from 0.6116 to 0.5721 for articles and from 0.6507 to 0.5649 for reviews; the k index, from 0.7260 to 0.7088 for articles from 0.7409 to 0.7072 for reviews. Inequality and polarization of citations consistently decreased in the imaging literature from 2001 to 2010.
Energy Technology Data Exchange (ETDEWEB)
Fernandez, Jorge; MartIn, Fernando [Departamento de Quimica C-9, Universidad Autonoma de Madrid, 28049 Madrid (Spain)], E-mail: fernando.martin@uam.es
2009-04-15
We have evaluated fully differential electron angular distributions in H{sub 2} and D{sub 2} dissociative photoionization by using linearly polarized light of 20, 27 and 33 eV. At 20 eV, the distributions exhibit simple p-wave patterns, which is the signature of direct ionization through the X{sup 2}{sigma}{sub g}{sup +}(1s{sigma}{sub g}) channel. At 27 eV, where the Q{sub 1} autoionizing states are populated, we observe a similar pattern, except when the molecule is oriented perpendicularly to the polarization direction and the energy of the ejected electron is small. In contrast, at 33 eV, autoionization from the Q{sub 1} and Q{sub 2} states leads to interferences between the X{sup 2}{sigma}{sub g}{sup +}(1s{sigma}{sub g}) and {sup 2}{sigma}{sub u}{sup +}(2p{sigma}{sub u}) ionization channels that result in a strong asymmetry of the electron angular distributions along the molecular axis. This asymmetry changes rapidly with the energy of the ejected electron. Electron angular distributions integrated over all possible molecular orientations or ion angular distributions integrated over electron emission angle show no reminiscence of the above phenomena, but the corresponding asymmetry parameters dramatically change with electron and ion energies in the region of autoionizing states.
Kovchegov, Yuri V.; Skokov, Vladimir V.
2018-05-01
We show that, in the saturation/color glass condensate framework, odd azimuthal harmonics of the two-gluon correlation function with a long-range separation in rapidity are generated by the higher-order saturation corrections in the interactions with the projectile and the target. At the very least, the odd harmonics require three scatterings in the projectile and three scatterings in the target. We derive the leading-order expression for the two-gluon production cross section which generates odd harmonics: the expression includes all-order interactions with the target and three interactions with the projectile. We evaluate the obtained expression both analytically and numerically, confirming that the odd-harmonics contribution to the two-gluon production in the saturation framework is nonzero.
Singh, Dharmendra Kumar; Kawamura, Kimitaka; Yanase, Ayako; Barrie, Leonard A
2017-08-15
The distributions, correlations, and source apportionment of aromatic acids, aromatic ketones, polycyclic aromatic hydrocarbons (PAHs), and trace metals were studied in Canadian high Arctic aerosols. Nineteen PAHs including minor sulfur-containing heterocyclic PAH (dibenzothiophene) and major 6 carcinogenic PAHs were detected with a high proportion of fluoranthene followed by benzo[k]fluoranthene, pyrene, and chrysene. However, in the sunlit period of spring, their concentrations significantly declined likely due to photochemical decomposition. During the polar sunrise from mid-March to mid-April, benzo[a]pyrene to benzo[e]pyrene ratios significantly dropped, and the ratios diminished further from late April to May onward. These results suggest that PAHs transported over the Arctic are subjected to strong photochemical degradation at polar sunrise. Although aromatic ketones decreased in spring, concentrations of some aromatic acids such as benzoic and phthalic acids increased during the course of polar sunrise, suggesting that aromatic hydrocarbons are oxidized to result in aromatic acids. However, PAHs do not act as the major source for low molecular weight (LMW) diacids such as oxalic acid that are largely formed at polar sunrise in the arctic atmosphere because PAHs are 1 to 2 orders of magnitude less abundant than LMW diacids. Correlations of trace metals with organics, their sources, and the possible role of trace transition metals are explained.
Park, S H; Tornow, W; Montgomery, C
2001-01-01
Beams of nearly monochromatic gamma-rays are produced via intracavity Compton backscattering in the OK-4/Duke storage ring FEL, the high-intensity gamma-ray source (HI gamma S). Presently, HI gamma S generates gamma-ray beams with an energy tunable from 2 to 58 MeV and a maximum flux of 5x10 sup 7 gamma-rays per second. The gamma-rays are linearly polarized with a degree of polarization close to 100% (V.N. Litvinenko, et al., Predictions and expected performance for the VUV OK-5/Duke Storage Ring FEL with variable polarization, Nucl. Instr. and Meth. A, to be published in this proceeding) and they are collimated to pencil-like semi-monoenergetic beams with RMS energy spreads as low as 0.2%. The detailed theoretical and experimental studies of the gamma-ray beam quality were conducted during the last two years (S.H. Park, Thesis, Duke University, Durham, NC, USA, 2000). In this paper, we present the theoretical analysis and the experimental results on the spatial distribution and polarization of gamma-rays fro...
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Park, S.H. E-mail: shpark@nanum.kaeri.re.kr; Litvinenko, V.N.; Tornow, W.; Montgomery, C
2001-12-21
Beams of nearly monochromatic {gamma}-rays are produced via intracavity Compton backscattering in the OK-4/Duke storage ring FEL, the high-intensity {gamma}-ray source (HI{gamma}S). Presently, HI{gamma}S generates {gamma}-ray beams with an energy tunable from 2 to 58 MeV and a maximum flux of 5x10{sup 7} {gamma}-rays per second. The {gamma}-rays are linearly polarized with a degree of polarization close to 100% (V.N. Litvinenko, et al., Predictions and expected performance for the VUV OK-5/Duke Storage Ring FEL with variable polarization, Nucl. Instr. and Meth. A, to be published in this proceeding) and they are collimated to pencil-like semi-monoenergetic beams with RMS energy spreads as low as 0.2%. The detailed theoretical and experimental studies of the {gamma}-ray beam quality were conducted during the last two years (S.H. Park, Thesis, Duke University, Durham, NC, USA, 2000). In this paper, we present the theoretical analysis and the experimental results on the spatial distribution and polarization of {gamma}-rays from the HI{gamma}S facility.
International Nuclear Information System (INIS)
Park, S.H.; Litvinenko, V.N.; Tornow, W.; Montgomery, C.
2001-01-01
Beams of nearly monochromatic γ-rays are produced via intracavity Compton backscattering in the OK-4/Duke storage ring FEL, the high-intensity γ-ray source (HIγS). Presently, HIγS generates γ-ray beams with an energy tunable from 2 to 58 MeV and a maximum flux of 5x10 7 γ-rays per second. The γ-rays are linearly polarized with a degree of polarization close to 100% (V.N. Litvinenko, et al., Predictions and expected performance for the VUV OK-5/Duke Storage Ring FEL with variable polarization, Nucl. Instr. and Meth. A, to be published in this proceeding) and they are collimated to pencil-like semi-monoenergetic beams with RMS energy spreads as low as 0.2%. The detailed theoretical and experimental studies of the γ-ray beam quality were conducted during the last two years (S.H. Park, Thesis, Duke University, Durham, NC, USA, 2000). In this paper, we present the theoretical analysis and the experimental results on the spatial distribution and polarization of γ-rays from the HIγS facility
Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François
2015-04-20
During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs. Copyright © 2015 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Procureur, S.
2006-07-01
The main goal of the COMPASS experiment at CERN is the determination of the gluon polarisation in the nucleon, V. For this, the helicity asymmetry of the photon gluon fusion process is measured, in the scattering of polarized muons on a polarised deuteron target. This process can be tagged by the production of hadrons with high transverse momentum (pT), that allows to get a large statistics. On the other hand, a physical background remains and complicates the extraction of V. This PhD thesis presents different studies performed to optimize the determination of c in this channel. In particular, a study of the alignment of the 200 detection planes is presented, leading to an improvement of the spectrometer resolution. Performances of the 12 Micromegas detectors have also been determined during 2004 run. Then, the asymmetries obtained in the analysis of 2002 to 2004 data are calculated, for various high PT selections: production of 1 or 2 hadrons, at low or high Q2. An optimization of the selection, based on a neural network, has also been developed, and a detailed study of the experimental false asymmetry has been performed. V extraction is then described, based on Monte Carlo simulations (using PYTHIA or LEPTO). For the first time, the asymmetry of the so-called resolved photon processes is estimated. An improvement on the reconstruction of nucleon momentum fraction carried by the gluon is also proposed, by reconstructing pseudo-jets. Finally, small values obtained for GG are discussed, in terms of constraints on the gluon contribution to the nucleon spin. (author)
Directory of Open Access Journals (Sweden)
Yingxia Yu
2013-09-01
Full Text Available Using the Quasi-Two-Dimensional (quasi-2D model, the current-voltage (I-V characteristics of AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs with different gate length were simulated based on the measured capacitance-voltage (C-V characteristics and I-V characteristics. By analyzing the simulation results, we found that the different polarization charge distribution generated by the different channel electric field distribution can result in different polarization Coulomb field scattering, and the difference of the electron mobility mostly caused by the polarization Coulomb field scattering can reach up to 1829.9 cm2/V·s for the prepared AlGaN/AlN/GaN HFET. In addition, it was also found that when the two-dimension electron gas (2DEG sheet density is modulated by the drain-source bias, the electron mobility appears peak with the variation of the 2DEG sheet density, and the ratio of gate length to drain-source distance is smaller, the 2DEG sheet density corresponding to the peak point is higher.
International Nuclear Information System (INIS)
Williams, W.G.
1988-01-01
The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)
Infrared behaviour of three and four gluon vertices in Yang-Mills theory
International Nuclear Information System (INIS)
Brandt, F.T.; Frenkel, J.
1985-01-01
The structure of the 3-point function with one and two external gluons on-shell is studied in a general covariant gauge. The contributions which result in one loop approximation are expressed in terms of simple functions containing collinear and soft singularities. Furthermore, the contributions associated with the 4-point vertex when all external gluons are on-shell are analysed. As an application of these results, the infrared structure of gluon-gluon scattering amplitude is studied. (Author) [pt
Quark-gluon plasma and the little bang
International Nuclear Information System (INIS)
McLerran, L.
1981-06-01
A space-time picture of the fragmentation and central regions is presented for extremely high energy head-on heavy nucleus collisions. The energy densities of the matter produced in such collisions are estimated. Speculations concerning the possible formation of a quark-gluon plasma are discussed, as are possible experimental signals for analyzing such a plasma
Bounds on the gluon mass from nucleon decay
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Avila, M.A. [Universidad Autonoma del Estado de Morelos, Morelos (Mexico)
2001-04-01
Permanent confinement of quarks is assumed to hold in QCD. However, if the gluon has a small mass it is possible to produce-quarks in hadron decays, high-energy reactions or in the early-universe. This situation is modelled by a quark-diquark potential composed of a linear (or harmonic) plus a Yukawa term. We compare our prediction for the proton decay with the experimental lower bound on its life-time, and obtain an upper bound on the gluon mass. [Spanish] Se supone se cumple el confinamiento permanente de quarks en cromodinamica cuantica. Si el gluon tiene masa pequena es posible producir quarks libres en decaimiento hadronicos, reacciones de altas energias o en el universo temprano. Esta situacion es modelada por un potencial quark-diquark, compuesto de un termino lineal (o armonico) mas un termino Yukawa. Comparamos nuestra prediccion para el decaimiento del proton con la cota inferior experimental de su vida media y obtenemos una cota superior sobre la masa del gluon.
Universal Regge slope α' from QCD gluon propagator
International Nuclear Information System (INIS)
Nielsen, H.B.; Ninomiya, M.
1980-02-01
An effective gluon propagator is estimated in the presence of a fluctuating color magnetic field in vacuum. Using the dual honeycomb diagram tlhe universal slope is estimated to yield Λsub(p) = 0.34 GeV when corrected by instanton, for α' = 0.88 GeV -2 . (Auth.)
Screening in an expanding quark-gluon plasma
International Nuclear Information System (INIS)
Broniowski, W.
1988-12-01
Effects of expansion on the Debye length in quark-gluon plasma are calculated in an abelian, boost invariant model. It is found that for early times the screening is significantly more efficient than what follows from naive static considerations. 11 refs., 1 fig., 1 tab. (author)
The quark gluon plasma: Lattice computations put to experimental test
Indian Academy of Sciences (India)
I describe how lattice computations are being used to extract experimentally relevant features of the quark gluon plasma. I deal speciﬁcally with relaxation times, photon emissivity, strangeness yields, event-by-event ﬂuctuations of conserved quantities and hydrodynamic ﬂow. Finally I give evidence that the plasma is rather ...
The angular ordering in soft-gluon emission
International Nuclear Information System (INIS)
Tesima, K.
1987-01-01
The way to evaluate multi-parton cross-sections systematically is discussed. In the leading-double-log approximation in QCD, the successive emission of soft gluons is at successively smaller angles. The angular ordering, however, is violated in the next-to-leading order
How Resummation Depresses the Gluon at Small x
Forte, Stefano; Ball, Richard D.; Forte, Stefano; Altarelli, Guido; Ball, Richard D.
2006-01-01
We summarize recent progress in the resummation of perturbative evolution at small x. We show that the problem of incorporating BFKL small x logs in GLAP evolution is now completely solved, and that the main effect of small x resummation is to reduce the growth of the gluon at small x in the HERA and LHC regions.
Nonperturbative quark-gluon thermodynamics at finite density
Andreichikov, M. A.; Lukashov, M. S.; Simonov, Yu. A.
2018-03-01
Thermodynamics of the quark-gluon plasma at finite density is studied in the framework of the Field Correlator Method, where thermodynamical effects of Polyakov loops and color magnetic confinement are taken into account. Having found good agreement with numerical lattice data for zero density, we calculate pressure P(T,μ), for 0 confinement.
Strangeness and quark gluon plasma: Aspects of theory and experiment
International Nuclear Information System (INIS)
Eggers, H.C.; Rafelski, J.
1990-07-01
A survey of our current understanding of the strange particle signature of quark gluon plasma is presented. Emphasis is placed on the theory of strangeness production in the plasma and recent pertinent experimental results. Useful results on spectra of thermal particles are given. (orig.)
Quark-gluon plasma: Status of heavy ion physics
Indian Academy of Sciences (India)
Lattice quantum chromodynamics (QCD), deﬁned on a discrete space–time lattice, leads to a spectacular non-perturbative prediction of a new state of matter, called quark-gluon plasma (QGP), at sufﬁciently high temperatures or equivalently large energy densities. The experimental programs of CERN, Geneva and BNL, ...
Gluon condensation and modelling of quark confinement in QCD-motivated Nambu-Jona-Lasinio model
International Nuclear Information System (INIS)
Bel'kov, A.A.; Ebert, D.; Emel'yanenko, A.V.
1992-01-01
The possibility of modelling of a quark propagator without poles realizing quark confinement is considered on the basis of a nonperturbative gluon propagator including gluon condensation and a dynamical gluon mass. The property of spontaneous chiral symmetry breaking is retained providing us with a reasonable pattern of low-lying meson properties. 2 figs.; 1 tab