Nicotri, Stefano
2009-01-01
A holographic description of scalar mesons is presented, in which two- and three-point functions are holographically reconstructed. Mass spectrum, decay constants, eigenfunctions and the coupling of the scalar states with two pseu- doscalars are found. A comparison of the results with current phenomenology is discussed.
The Search and Study of Low-mass Scalar Mesons in the Reaction np -> npPi+Pi- AT Pn=3.83 Gev/c
Troyan, Yu A; Troyan, A Yu; Plekhanov, E B; Jerusalimov, A P; Arakelian, S G
2010-01-01
This work is devoted to search and study scalar sigma0 0+[0++] - mesons in the system of Pi+Pi- from the reaction np -> npPi+Pi- at the impulse of the quasimonochromatic neutrons c from the data obtained in an exposure of the 1m H2 bubble chamber of LHE (JINR)The resonance with and has been found out in effective mass distribution. Value of a statistical deviation of this peculiarity from a background is more than four. Spin of the resonance has been estimated, which, with high probability, is equal 0. The other quantum numbers of the resonance have been estimated.
Troyan, Yu. A.; Beljaev, A. V.; Troyan, A. Yu.; Plekhanov, E. B.; Jerusalimov, A. P.; Arakelian, S. G.
2010-01-01
This work is devoted to search and study scalar $\\sigma_0 0^+[0^++]$ - mesons in the system of $\\pi^+\\pi^-$ from the reaction $np -> np\\pi^+\\pi^-$ at the impulse of the quasimonochromatic neutrons c from the data obtained in an exposure of the 1m H2 bubble chamber of LHE (JINR)The resonance with and has been found out in effective mass distribution. Value of a statistical deviation of this peculiarity from a background is more than four. Spin of the resonance has been estimated, which, with h...
Energy Technology Data Exchange (ETDEWEB)
Hooft, G. t' [Institute for Theoretical Physics, Utrecht University, and Spinoza Institute, Postbus 8000, 3508 TA Utrecht (Netherlands); Isidori, G. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); INFN, Laboratori Nazionali di Frascati, Via E.Fermi 40, 00044 Frascati (Italy); Maiani, L. [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , P.le A. Moro 2, 00185 Roma (Italy); INFN, Sezione di Roma ' La Sapienza' , P.le A. Moro 2, 00185 Roma (Italy); Polosa, A.D. [INFN, Sezione di Roma ' La Sapienza' , P.le A. Moro 2, 00185 Roma (Italy)], E-mail: antonio.polosa@cern.ch; Riquer, V. [INFN, Sezione di Roma ' La Sapienza' , P.le A. Moro 2, 00185 Roma (Italy)
2008-05-08
We discuss the effect of the instanton induced, six-fermion effective Lagrangian on the decays of the lightest scalar mesons in the diquark-antidiquark picture. This addition allows for a remarkably good description of light scalar meson decays. The same effective Lagrangian produces a mixing of the lightest scalars with the positive parity qq-bar states. Comparing with previous work where the qq-bar mesons are identified with the nonet at 1200-1700 MeV, we find that the mixing required to fit the mass spectrum is in good agreement with the instanton coupling obtained from light scalar decays. A coherent picture of scalar mesons as a mixture of tetraquark states (dominating in the lightest mesons) and heavy qq-bar states (dominating in the heavier mesons) emerges.
The light scalar mesons as tetraquarks
Directory of Open Access Journals (Sweden)
Gernot Eichmann
2016-02-01
Full Text Available We present a numerical solution of the four-quark Bethe–Salpeter equation for ground-state scalar tetraquarks with JPC=0++. We find that the four-body equation dynamically generates pseudoscalar-meson poles in the Bethe–Salpeter amplitude. The resulting tetraquarks are genuine four-quark states that are dominated by pseudoscalar meson–meson correlations. Diquark–antidiquark contributions are subleading because of their larger mass scale. In the light quark sector, the sensitivity of the tetraquark wave function to the pion poles leads to an isoscalar tetraquark mass Mσ∼350 MeV which is comparable to that of the σ/f0(500. The masses of its multiplet partners κ and a0/f0 follow a similar pattern. This provides support for a tetraquark interpretation of the light scalar meson nonet in terms of ‘meson molecules’.
Electromagnetic Form Factor of Charged Scalar Meson
Institute of Scientific and Technical Information of China (English)
LI Heng-Mei; CHEN Ning; WANG Zhi-Gang; WAN Shao-Long
2007-01-01
Wavefunctions and the electromagnetic form factor of charged scalar mesons are studied with the vector-vectortype flat-bottom potential model under the framework of the spinor spinor Bethe Salpeter equation. The obtained results are in agreement with other theories.
On the spectral functions of scalar mesons
Giacosa, Francesco
2007-01-01
In this work we study the spectral functions of scalar mesons in one- and two-channel cases. When the propagators satisfy the K\\"allen-Lehman representation a normalized spectral function is obtained, allowing to take into account finite-width effects in the evaluation of decay rates. In the one-channel case, suitable to the light sigma and k mesons, the spectral function can deviate consistently from a Breit-Wigner shape. In the two-channel case with one subthreshold channel the evaluated spectral function is well approximated by a Flatte' distribution; when applying the study to the $a_0(980)$ and $f_0(980)$ mesons the three-level forbidden KK decay is analysed.
Scalar meson mass from renormalized One Boson Exchange Potential
Cordon, A Calle
2008-01-01
We determine the mass and strength of the scalar meson from NN scattering data by renormalizing the One Boson Exchange Potential. This procedure provides a great insensitivity to the unknown short distance interaction making the vector mesons marginally important and allowing for SU(3) couplings in the 1S0 channel. The scalar meson parameters are tightly constrained by low energy np. We discuss whether this scalar should be compared to the recent findings based on the Roy equations analysis of pipi scattering.
Troyan, Yu A; Troyan, A Yu; Plekhanov, E B; Jerusalimov, A P; Arakelian, S G
2008-01-01
Using irradiation of 1-m. HBC LHE JINR by qvasimonochromatic neutron beam with impulse Pn=(5.20 +/- 0.12)GeV/c which was produced after acceleration deuterons in the sinchrophasotron LHE JINR where selected 2560 events of reaction np --> npPi+Pi-. After supplementary sorting out events in which a secondary proton flies forward in general c.m.s. of reaction in the effective mass spectrum of Pi+Pi- - combinations there were found out nine peculiarities at masses 350, 408, 489, 579, 676, 762, 878, 1036, 1170 MeV/c^2 and with experimental widths not more than several tens MeV/c^2. The resosnsce effects are too increased after use additional criterion - balance of tne sum of the longitidual impulse of Pi+ and Pi- mesons in the general c.m.s. of the reaction. By these conditions the values of standart derivation from the background are (5 - 7.5). The direct measurement of the spin of resonances was carried out. Also other quantum numbers where obtained. All of these peculiarities have similar set of quantum numbers...
Scalar mesons and tetraquarks from twisted mass lattice QCD
Wagner, Marc; Daldrop, Jan Oliver; Brida, Mattia Dalla; Gravina, Mario; Scorzato, Luigi; Urbach, Carsten; Wiese, Christian
2013-01-01
We study light scalar mesons with particular focus on the a_0(980) using lattice QCD with 2+1+1 dynamical quark flavors. To investigate the structure of these scalar mesons and to identify, whether a sizeable tetraquark component is present, we use a large set of operators, including diquark-antidiquark, mesonic molecule and two-meson operators. We find that the low-lying states overlap essentially exclusively with two-meson states. This indicates that in the channels investigated no tightly bound four-quark states of either molecular or diquark-antidiquark type exist.
Scalar mesons and tetraquarks by means of lattice QCD
Wagner, Marc; Daldrop, Jan Oliver; Brida, Mattia Dalla; Gravina, Mario; Scorzato, Luigi; Urbach, Carsten; Wiese, Christian
2012-01-01
We study the light scalar mesons a_0(980) and kappa using N_f = 2+1+1 flavor lattice QCD. In order to probe the internal structure of these scalar mesons, and in particular to identify, whether a sizeable tetraquark component is present, we use a large set of operators, including diquark-antidiquark, mesonic molecule and two-meson operators. The inclusion of disconnected diagrams, which are technically rather challenging, but which would allow us to extend our work to e.g. the f_0(980) meson, is introduced and discussed.
Scalar mesons in a linear sigma model with (axial-)vector mesons
Parganlija, D; Wolf, Gy; Giacosa, F; Rischke, D H
2012-01-01
The structure of the scalar mesons has been a subject of debate for many decades. In this work we look for $\\bar{q}q$ states among the physical resonances using an extended Linear Sigma Model that contains scalar, pseudoscalar, vector, and axial-vector mesons both in the non-strange and strange sectors. We perform global fits of meson masses, decay widths and amplitudes in order to ascertain whether the scalar $\\bar{q}q$ states are below or above 1 GeV. We find the scalar states above 1 GeV to be preferred as $\\bar{q}q$ states.
The effect of isospin violation on scalar meson production
Hanhart, C; Peláez, J R
2007-01-01
We investigate the isospin-violating mixing of the light scalar mesons a0(980) and f0(980) within the unitarized chiral approach. Isospin-violating effects are considered to leading order in the quark mass difference and electromagnetism. In this approach both resonances are generated through meson-meson dynamics. Our results provide a description of the mixing phenomenon within a framework consistent with chiral symmetry and unitarity, where these resonances are not predominantly quark-antiquark states. We discuss in detail the reactions J/Psi to phi S, where S denotes a suitable pair of pseudo--scalar mesons in the scalar channel, namely pi0 eta, K+K-, and K0 \\bar K^0. In this work predictions for the cross section in the kaon channels are given for the first time with isospin violating effects included.
Chiral symmetry and scalar meson in hadron and nuclear physics
Kunihiro, T
1995-01-01
After giving a short introduction to the Nambu-Jona-Lasinio model with an anomaly term, we show the importance of the scalar-scalar correlation in the low-energy hadron dynamics, which correlation may be summarized by a scalar-isoscalar meson, the sigma meson. The discussion is based on the chiral quark model with the sigma-meson degrees of freedom. Possible experiments are proposed to produce the elusive meson in a nucleus and detect it. In relation to a precursory soft mode for the chiral transition, the reason is clarified why the dynamic properties of the superconductor may be described by the diffusive time-dependent Ginzburg-Landau (TDGL) equation. We indicate the chiral symmetry plays a significant role also in nuclei; one may say that the stability of nuclei is due to the chiral symmetry of QCD.
Analysis of the scalar nonet mesons with QCD sum rules
Energy Technology Data Exchange (ETDEWEB)
Wang, Zhi-Gang [North China Electric Power University, Department of Physics, Baoding (China)
2016-08-15
In this article, we assume that the nonet scalar mesons below 1 GeV are the two-quark-tetraquark mixed states and study their masses and pole residues using the QCD sum rules. In the calculation, we take into account the vacuum condensates up to dimension 10 and the O(α{sub s}) corrections to the perturbative terms in the operator product expansion. We determine the mixing angles, which indicate the two-quark components are much larger than 50 %, then we obtain the masses and pole residues of the nonet scalar mesons. (orig.)
Leading-twist distribution amplitudes of scalar and vector mesons
Li, B.-L.; Chang, L.; Ding, M.; Roberts, C. D.; Zong, H.-S.
2016-11-01
A symmetry-preserving truncation of the two-body light-quark bound-state problem in relativistic quantum field theory is used to calculate the leading-twist parton distribution amplitudes (PDAs) of scalar systems, both ground-state and radial excitations, and the radial excitations of vector mesons. Owing to the fact that the scale-independent leptonic decay constant of a scalar meson constituted from equal-mass valence constituents vanishes, it is found that the PDA of a given scalar system possesses one more zero than that of an analogous vector meson. Consequently, whereas the mean light-front relative momentum of the valence constituents within a vector meson is zero, that within a scalar meson is large, an outcome which hints at a greater role for light-front angular momentum in systems classified as P -wave in quantum mechanical models. Values for the scale-dependent decay constants of ground-state scalar and vector systems are a by-product of this analysis, and they turn out to be roughly equal, viz. ≃0.2 GeV at an hadronic scale. In addition, it is confirmed that the dilation characterizing ground-state PDAs is manifest in the PDAs of radial excitations too. The impact of S U (3 )-flavor symmetry breaking is also considered. When compared with pseudoscalar states, it is a little stronger in scalar systems, but the size is nevertheless determined by the flavor dependence of dynamical chiral symmetry breaking and the PDAs are still skewed toward the heavier valence quark in asymmetric systems.
How we discovered the nonet of light scalar mesons
van Beveren, Eef
2007-01-01
As has been confirmed meanwhile by lattice-QCD calculations (see e.g. hep-lat/0702023), the confinement spectrum of non-exotic quark-antiquark systems has its ground state for scalar mesons well above 1 GeV in the Resonance Spectrum Expansion (RSE). For instance, in the S-wave Kaon-pion RSE amplitude, a broad resonance was predicted slightly above 1.4 GeV [hep-ex/0106077], which is confirmed by experiment as the K*0(1430). However, a complete nonet of light scalar mesons was predicted (Zeit.Phys.C30,615 [http://www-spires.slac.stanford.edu/spires/find/hep?key=1573454]) as well, when a model strongly related to the RSE and initially developed to describe the heavy quarkonia resonance spectra (Phys.Rev.D21,772 [http://www-spires.slac.stanford.edu/spires/find/hep?key=363162]) was applied in the light-quark sector. Thus, it was found that the light scalar-meson nonet constitutes part of the ordinary meson spectrum, albeit represented by "extraordinary" [hep-ph/0701038] poles [hep-ex/0106077]. Similar resonances a...
Scalar mesons and the search for the 0{sup ++} glueball
Energy Technology Data Exchange (ETDEWEB)
Thoma, U. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2003-11-01
The possibility that gluonic excitations of hadronic matter or of the QCD vacuum may exist is perhaps one of the most fascinating topics in hadron spectroscopy. Glueballs are predicted by many models; in particular, present-day lattice gauge calculations require their existence. All these models agree that the lightest glueball should have scalar quantum numbers and a mass around 1.6GeV, which corresponds to the mass region where the scalar q anti q-mesons are expected. Therefore, mixing effects can complicate the search for the glueball. Experiments indeed show an overpopulation of states, for which many different interpretations exist. This reflects the complexity of the situation. New data from various experiments on scalar states give hints toward an interpretation of the scalar states. But still many questions remain. (orig.)
Scalar mesons and the search for the 0{sup ++} Glueball
Energy Technology Data Exchange (ETDEWEB)
Ulrike Thoma
2002-10-01
The possibility that gluonic excitations of hadronic matter or of the QCD vacuum may exist is perhaps one of the most fascinating topics in hadron spectroscopy. Glueballs are predicted by many models; in particular present-day lattice gauge calculations require their existence. All these models agree that the lightest glueball should have scalar quantum numbers and a mass around 1.6 GeV, which corresponds to the mass region where the scalar qq[bar]-mesons are expected. Therefore mixing effects can complicate the search for the glueball. Experiments indeed show an overpopulation of states, for which many different interpretations exist. This reflects the complexity of the situation. New data from various experiments on scalar states give hints toward an interpretation of the scalar states. But, still many questions remain.
Charmless nonleptonic decays into scalar and pseudoscalar mesons
Indian Academy of Sciences (India)
B Mawlong
2007-10-01
The charmless nonleptonic decay modes → 0 () involving a scalar and a pseudoscalar meson in the ﬁnal state are studied. The scalar meson 0 is considered as a $q\\bar{q}$ state, as favored by some recent studies. Using the generalized factorization approach, the branching ratios and CP violation parameters are computed for these modes. The form factors are calculated using the results from relativistic light front quark model and the ISGW2 model. It is found that the direct CP violation parameters in these modes are small. However, the obtained branching ratios are not in agreement with the experimental data. Therefore, these modes may be considered as possible probes for new physics.
Photoproduction of scalar mesons at CLAS
Chandavar, Shloka; Hicks, Kenneth; Weygand, Dennis; CLAS Collaboration
2013-10-01
A single gluon, which carries color charge, cannot exist independently outside a hadron. Lattice QCD calculations in pure SU(3), however, predict the existence of glueballs which are bound states of two or more gluons. In the real world, the challenge to identify glueballs experimentally is the fact they mix with meson states. The f0 (1500) is one of several candidates for the lightest glueball, with JPC =0++ . We investigate the presence of this particle in photoproduction by analyzing the reaction γp -->fJ p -->KS0KS0 p --> 2 (π+π-) p . This reaction was studied using data from the g12 experiment performed using the CLAS detector at Jefferson Lab. A preliminary partial wave analysis, performed on the KS0KS0 invariant mass spectrum, will be presented. These results update those presented for this reaction channel at previous conferences. This work is supported by grant from NSF.
Scalar {sigma} meson effects in {rho} and {omega} decays
Energy Technology Data Exchange (ETDEWEB)
Bramon, A. [Universitat Autonoma de Barcelona, Dept. de Fisica, Bellaterra, Barcelona (Spain); Escribano, R. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Rome (Italy); Lucio, J.L.M.; Napsuciale, M. [Universidad de Guanajuato, Instituto de Fisica, Leon (Mexico)
2001-05-01
The complementarity between Chiral Perturbation Theory and the Linear Sigma Model in the scalar channel is exploited to study {pi}{sup 0} {pi}{sup 0} production in {rho} and {omega} radiative decays, where the effects of a low mass scalar resonance {sigma} (500) should manifest. The recently reported data on {rho} {yields} {pi}{sup 0} {pi}{sup 0} y seem to require the contribution of a low mass and moderately narrow {sigma} (500). The properties of this controversial state could be fixed by improving the accuracy of these measurements. Data on {omega} {yields} {pi}{sup 0} {pi}{sup 0} y can also be accommodated in the framework, but are much less sensitive to the {sigma} (500) properties.
Light Scalar Mesons in Central Production at COMPASS
Austregesilo, A
2016-01-01
COMPASS is a fixed-target experiment at the CERN SPS that studies the spectrum of light-quark hadrons. In 2009, it collected a large dataset using a $190\\,$GeV$/c$ positive hadron beam impinging on a liquid-hydrogen target in order to measure the central exclusive production of light scalar mesons. One of the goals is the search for so-called glueballs, which are hypothetical meson-like objects without valence-quark content. We study the decay of neutral resonances by selecting centrally produced pion pairs from the COMPASS dataset. The angular distributions of the two pseudoscalar mesons are decomposed in terms of partial waves, where particular attention is paid to the inherent mathematical ambiguities. The large dataset allows us to perform a detailed analysis in bins of the two squared four-momentum transfers carried by the exchange particles in the reaction. Possible parameterisations of the mass dependence of the partial-wave amplitudes in terms of resonances are also discussed.
Unifying Scalars and Light Mesons by Holographic QCD
de Paula, W
2009-01-01
We show that the universality of the infrared dynamics of string modes dual to $q\\bar q$ states within a Dynamical AdS/QCD model of coupled dilaton-gravity background implies in the Regge-like spectrum of $f_0$'s scalars and higher spin mesons consistent with experimental data. The pion mass and its trajectory were also described with a scale deformation of the metric and a rescaled string mass. The available experimental decay widths of the $S\\to PP$ decays provided a complementary check of the proposed classification scheme for $f_0(980)$, $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ as radial excitations of $f_0(600)$. For $f_0(980)$ we estimated a mixing angle of $\\pm 20^o$ with other structures.
Scalar meson f{sub 0}(980) in heavy-meson decays.
Energy Technology Data Exchange (ETDEWEB)
El-Bennich, B.; Leitner, O.; Dedonder, J.-P.; Loiseau, B.; Physics; Lab. de Physique Nucleaire et de Hautes Energies; Lab. Nazionali di Frascati
2009-04-01
A phenomenological analysis of the scalar meson f{sub 0}(980) is performed that relies on the quasi-two-body decays D and D{sub s} {yields} f{sub 0}(980)P, with P = {pi}, K. The two-body branching ratios are deduced from experimental data on D or D{sub s} {yields} {pi}{pi}{pi}, K{sup -} K{pi} and from the f{sub 0}(980) {yields} {pi}{sup +}{pi}{sup -} and f{sub 0}(980) {yields} K{sup +}K{sup -} branching fractions. Within a covariant quark model, the scalar form factors for the transitions D and D{sub s} {yields} f{sub 0}(980) are computed. The weak D decay amplitudes, in which these form factors enter, are obtained in the naive factorization approach assuming a q{bar q} state for the scalar and pseudoscalar mesons. They allow to extract information on the f{sub 0}(980) wave function in terms of u{bar u}, d{bar d}, and s{bar s} pairs as well as on the mixing angle between the strange and nonstrange components. The weak transition form factors are modeled by the one-loop triangular diagram using two different relativistic approaches: covariant light-front dynamics and dispersion relations. We use the information found on the f{sub 0}(980) structure to evaluate the scalar and vector form factors in the transitions D and D{sub s} {yields} f{sub 0}(980), as well as to make predictions for B and B{sub s} {yields} f{sub 0}(980), for the entire kinematically allowed momentum range of q{sup 2}.
Exclusive central diffractive production of scalar, pseudoscalar and vector mesons
Directory of Open Access Journals (Sweden)
Lebiedowicz P.
2014-01-01
Full Text Available We discuss exclusive central diffractive production of scalar (ƒ0(980, ƒ0(1370, ƒ0(1500, pseudoscalar (η, η′(958, and vector (ρ0 mesons in proton-proton collisions. The amplitudes are formulated in terms of effective vertices required to respect standard rules of Quantum Field Theory and propagators for the exchanged pomeron and reggeons. Different pomeron-pomeron-meson tensorial (vectorial coupling structures are possible in general. In most cases two lowest orbital angular momentum - spin couplings are necessary to describe experimental differential distributions. For the ƒ0(980 and η production the reggeon-pomeron, pomeron-reggeon, and reggeon-reggeon exchanges are included in addition, which seems to be necessary at relatively low energies. The theoretical results are compared with the WA102 experimental data, in order to determine the model parameters. For the ρ0 production the photon-pomeron and pomeron-photon exchanges are considered. The coupling parameters of tensor pomeron and/or reggeon are fixed from the H1 and ZEUS experimental data of the γp → ρ0 p reaction. We present first predictions of this mechanism for pp → ppπ+π− reaction being studied at COMPASS, RHIC, Tevatron, and LHC. Correlation in azimuthal angle between outgoing protons and distribution in pion rapidities at √s = 7 TeV are presented. We show that high-energy central production of mesons could provide crucial information on the spin structure of the soft pomeron.
Leading-twist distribution amplitudes of scalar- and vector-mesons
Li, Bo-Lin; Ding, Minghui; Roberts, Craig D; Zong, Hong-Shi
2016-01-01
A symmetry-preserving truncation of the two-body light-quark bound-state problem in relativistic quantum field theory is used to calculate the leading-twist parton distribution amplitudes (PDAs) of scalar systems, both ground-state and radial excitations, and the radial excitations of vector mesons. Owing to the fact that the scale-independent leptonic decay constant of a scalar meson constituted from equal-mass valence-constituents vanishes, it is found that the PDA of a given scalar system possesses one more zero than that of an analogous vector meson. Consequently, whereas the mean light-front relative momentum of the valence-constituents within a vector meson is zero, that within a scalar meson is large, an outcome which hints at a greater role for light-front angular momentum in systems classified as $P$-wave in quantum mechanical models. Values for the scale-dependent decay constants of ground-state scalar and vector systems are a by-product of this analysis, and they turn out to be roughly equal, viz. ...
New insights into the Ds0 *(2317 ) and other charm scalar mesons
Guo, Zhi-Hui; Meißner, Ulf-G.; Yao, De-Liang
2015-11-01
Through the scattering of light-pseudoscalar mesons (π ,K ,η ,η' ) off charmed mesons (D ,Ds) , we study the Ds0 *(2317 ) state and other relevant charm scalar mesons in a unitarized chiral effective field theory approach. We investigate the charm scalar meson poles with different strangeness (S ) and isospin (I ) quantum numbers as well as their corresponding residues, which provide the coupling strengths of the charm scalar mesons. Both the light-quark mass and NC dependences of the pole positions of the Ds0 *(2317 ) and the poles with (S ,I )=(0 ,1 /2 ) are analyzed in detail in this work. Interestingly we observe quite similar pion mass trajectories for the resonance pole at around 2.1 GeV with (S ,I )=(0 ,1 /2 ) to those of the f0(500 ) given in the literature. When increasing the values of NC we find that a bound state and a virtual state in the (S ,I )=(1 ,0 ) channel asymmetrically approach the D K threshold for NC6 , the bound and virtual states move into the complex plane on the second Riemann sheet and become a symmetric pair of resonance poles. For large enough values of NC, neither the Ds0 *(2317 ) pole nor the poles with (S ,I )=(0 ,1 /2 ) tend to fall down to the real axis, indicating that they do not behave like a standard quark-antiquark meson at large NC.
Three-body force and the tetraquark interpretation of light scalar mesons
Institute of Scientific and Technical Information of China (English)
ZOU Fan-Yong; CHEN Xiao-Lin; DENG Wei-Zhen
2008-01-01
We study the possible tetraquark interpretation of light scalar meson states a0(980), f0(980), κ,σ within the framework of the non-relativistic potential model. The wave functions of tetraquark states are obtained in a space spanned by multiple Gaussian functions. We find that the mass spectra of the light scalar mesons can be well accommodated in the tetraquark picture if we introduce a three-body quark interaction in the quark model. Using the obtained multiple Gaussian wave functions, the decay constants of tetraquarks are also calculated within the "fall apart" mechanism.
Effects of isovector scalar $\\delta$-meson on hypernuclei
Ikram, M; Biswal, S K; Patra, S K
2014-01-01
We analyze the effects of $\\delta-$ meson on hypernuclei within the frame-work of relativistic mean field theory. The $\\delta-$ meson is included into the Lagrangian for hypernuclei. The extra nucleon-meson coupling ($g_\\delta$) affects the every piece of physical observables, like binding energy, radii and single particle energy of hypernuclei. The lambda mean field potential is investigated which is consistent with other predictions. Flipping of single particle energy levels are observed with the strength of $g_\\delta$ in the considered hypernuclei as well as normal nuclei. The spin-orbit potentials are observed for considered hypernuclei and the effect of $g_\\delta$ on spin-orbit potentials is also analyzed. The calculated single-$\\Lambda$ binding energies ($B_\\Lambda$) are quite agreeable with the experimental data.
New insights into the $D^{*}_{s0}(2317)$ and other charm scalar mesons
Guo, Zhi-Hui; Yao, De-Liang
2015-01-01
Through the scattering of light-pseudoscalar mesons ($\\pi,K,\\eta,\\eta'$) off charmed mesons ($D, D_s$), we study the $D^{*}_{s0}(2317)$ state and other relevant charm scalar mesons in a unitarized chiral effective field theory approach. We investigate the charm scalar meson poles with different strangeness ($S$) and isospin ($I$) quantum numbers as well as their corresponding residues, which provide the coupling strengths of the charm scalar mesons. Both the light-quark mass and $N_C$ dependences of the pole positions of the $D^{*}_{s0}(2317)$ and the poles with $(S,I)=(0,1/2)$ are analyzed in detail in this work. Interestingly we observe quite similar pion mass trajectories for the resonance pole at around 2.1 GeV with $(S,I)=(0,1/2)$ to those of the $f_0(500)$ given in the literature. When increasing the values of $N_C$ we find that a bound state and a virtual state in the $(S,I)=(1,0)$ channel asymmetrically approach the $D K$ threshold for $N_C6$, the bound and virtual states move into the complex plane o...
Classification of the scalar mesons: a strange pole expedition into charm and beauty territory
Van Beveren, E; Beveren, Eef van; Rupp, George
2004-01-01
The classification of scalar and vector mesons is reviewed within the framework of the Resonance-Spectrum Expansion (RSE). This method allows a simple and straightforward description of non-exotic meson-meson scattering, incorporating the effects of quark confinement and OZI-allowed decay in a fully nonperturbative way. Results for resonances and bound states are compared to experiment, on the basis of computed pole positions and cross sections. New predictions for open-charm and -bottom scalar mesons are presented. Concretely, observed vector states for u-ubar/d-dbar, s-sbar, c-cbar, and b-bbar are reproduced, and others are predicted. In the light scalar sector, the now established two nonets, one below 1 GeV and one in the region 1.3 - 1.5 GeV, are easily described, through the appearance of extra poles in the scattering matrix. The recently found Ds0*(2317) meson is accurately reproduced by the same mechanism, as a quasi-bound state in the coupled c-sbar/DK system. In S-wave D-pion and B-pion scattering, ...
Renormalizable Electrodynamics of Scalar and Vector Mesons. Part II
Salam, Abdus; Delbourgo, Robert
1964-01-01
The "gauge" technique" for solving theories introduced in an earlier paper is applied to scalar and vector electrodynamics. It is shown that for scalar electrodynamics, there is no {lambda}φ*2φ2 infinity in the theory, while with conventional subtractions vector electrodynamics is completely finite. The essential ideas of the gauge technique are explained in section 3, and a preliminary set of rules for finite computation in vector electrodynamics is set out in Eqs. (7.28) - (7.34).
Excited Scalar Mesons and the Search for Glueballs
Parganlija, Denis
2016-01-01
We discuss the importance of mixing between glueballs -- bound states of gluons -- and excited $\\bar{q}q$ states for the glueball search. A preliminary study of the excited states in the Extended Linear Sigma Model (eLSM) suggests their masses in the scalar channel to be in the vicinity of the scalar-glueball mass found in Lattice QCD. This could have implications for future glueball searches.
Neutron Stars in Relativistic Mean Field Theory with Isovector Scalar Meson
Kubis, S; Stachniewicz, S
1998-01-01
We study the equation of state of beta-stable dense matter and models of neutron stars in the relativistic mean field theory with the isovector scalar mean field corresponding to the delta-meson [a_0(980)]. A range of values of the delta-meson coupling compatible with the Bonn potentials is explored. Parameters of the model in the isovector sector are constrained to fit the nuclear symmetry energy, E_s=30 MeV. We find that the quantity most sensitive to the delta-meson coupling is the proton fraction of neutron star matter. It increases significantly in the presence of the delta-field. The energy per baryon also increases but the effect is smaller. The equation of state becomes slightly stiffer and the maximum neutron star mass increases for stronger delta-meson coupling.
Finite nuclei in relativistic models with a light chiral scalar meson
Furnstahl, R. J.; Serot, Brian D.
1993-05-01
Relativistic chiral models with a light scalar meson appear to provide an economical marriage of successful relativistic mean-field theories and chiral symmetry. The scalar meson serves as both the chiral partner of the pion and the mediator of the intermediate-range nucleon-nucleon (NN) attraction. However, while some of these models can reproduce the empirical nuclear matter saturation point, they fail to reproduce observed properties of finite nuclei, such as spin-orbit splittings, shell structure, charge densities, and surface energetics. These deficiencies imply that this realization of chiral symmetry is incorrect. An alternative scenario, which features a heavy chiral scalar and dynamical generation of the NN attraction, is discussed.
Scalar Mesons as qbar^2 q^2? Insight from the Lattice
Alford, M
2003-01-01
I describe some insight obtained from a lattice calculation on the possibility that the light scalar mesons are qbar^2 q^2 states rather than qbar q. First I review some general features of qbar^2 q^2 states in QCD inspired quark models. Then I describe a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, which finds indications that for sufficiently heavy quarks there is a stable four-quark bound state with JPC=0{++} and non-exotic flavor quantum numbers.
Photoproduction of scalar mesons using CLAS at JLab
Chandavar, Shloka; Hicks, Kenneth; Weygand, Dennis; CLAS Collaboration
2014-09-01
The search for glueballs has been ongoing for decades. The lightest glueball has been predicted by quenched lattice QCD to have a mass in the range of 1.0-1.7 GeV and JPC =0++ . The mixing of glueball states with neighbouring meson states complicates their identification. The f0 (1500) is one of several candidates for the lightest glueball, whose presence in the Ks0 Ks0 channel is investigated in photoproduction using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. This is done by studying the reaction, γp -->fJ p -->Ks0> Ks0p --> 2 (π+π-) p using data from the g12 experiment. A brief description of this analysis, along with a preliminary partial wave analysis results will be presented. The search for glueballs has been ongoing for decades. The lightest glueball has been predicted by quenched lattice QCD to have a mass in the range of 1.0-1.7 GeV and JPC =0++ . The mixing of glueball states with neighbouring meson states complicates their identification. The f0 (1500) is one of several candidates for the lightest glueball, whose presence in the Ks0Ks0 channel is investigated in photoproduction using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. This is done by studying the reaction, γp -->fJ p -->Ks0 Ks0p --> 2 (π+π-) p using data from the g12 experiment. A brief description of this analysis, along with a preliminary partial wave analysis results will be presented. NSF.
Nuclear Matter in Relativistic Mean Field Theory with Isovector Scalar Meson
Kubis, S
1997-01-01
Relativistic mean field (RMF) theory of nuclear matter with the isovector scalar mean field corresponding to the delta-meson [a_0(980)] is studied. While the delta-meson mean field vanishes in symmetric nuclear matter, it can influence properties of asymmetric nuclear matter in neutron stars. The RMF contribution due to delta-field to the nuclear symmetry energy is negative. To fit the empirical value, E_s=30 MeV, a stronger rho-meson coupling is required than in the absence of the delta-field. The energy per particle of neutron matter is then larger at high densities than the one with no delta-field included. Also, the proton fraction of beta-stable matter increases. Splitting of proton and neutron effective masses due to the delta-field can affect transport properties of neutron star matter.
Two-body charmed B(Bs) decays involving a light scalar meson
Zou, Zhi-Tian; liu, Xin
2016-01-01
Based on the assumption of two-quark structure for the light scalar mesons, within the framework of perturbative QCD approach, we investigate the $B_{q}\\to D_{(s)}^{(*)} S(q=u,d,s)$ decays induced by $b\\to u $ transition, where $S$ denotes a light scalar meson. Under two different scenarios, we calculate the branching ratios of 96 decay modes totally, which are in the range of $10^{-5}$ to $10^{-8}$. The comparison between our predictions and the experimental data will allow us to probe the inner structure of the scalar mesons. In the standard model, since all decays can only occur through tree operators, there are no $CP$ asymmetries. From our calculations, it has been shown that the annihilation type diagrams, especially the nonfactorizable annihilation diagrams, play important roles in the decay amplitudes, especially for these color-suppressed and pure annihilation type decay modes. We also find that the branching ratios of color-allowed type decays are sensitive to the different scenarios, so the measure...
A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS
Bicudo, P J A
1998-01-01
We introduce coupled channels of Bethe-Salpeter mesons both in the mass gap equation for chiral symmetry breaking and in the boundstate equation for mesons. Consistency is insured by the Ward Identities for axial currents, which preserve the Goldstone boson nature of the pion. We find that the coupling of channels yields the widths of resonances and contributes to mass splittings, but it does not shift globally the hadron spectrum. We find that coupled channels reduce the breaking of chiral symmetry. This reduction is constrained by the coupling of a scalar meson to a pair of pseudoscalar mesons. The light and wide $\\sigma-f_0(600)$, the narrow $f_0(980)$ and the relatively heavy $f_0(1370)$ are studied in order to comply with the spontaneous breaking of chiral symmetry. Exact calculations are performed in a particular model. In this model we find that the $f_0(980)$ is the best candidate for the groundstate quark antiquark meson . In particular its width is naturally small. In this case the coupled channels ...
Gaussian Sum-Rule Analysis of Scalar Gluonium and Quark Mesons
Steele, T G; Orlandini, G
2003-01-01
Gaussian sum-rules, which are related to a two-parameter Gaussian-weighted integral of a hadronic spectral function, are able to examine the possibility that more than one resonance makes a significant contribution to the spectral function. The Gaussian sum-rules, including instanton effects, for scalar gluonic and non-strange scalar quark currents clearly indicate a distribution of the resonance strength in their respective spectral functions. Furthermore, analysis of a two narrow resonance model leads to excellent agreement between theory and phenomenology in both channels. The scalar quark and gluonic sum-rules are remarkably consistent in their prediction of masses of approximately 1.0 GeV and 1.4 GeV within this model. Such a similarity would be expected from hadronic states which are mixtures of gluonium and quark mesons.
Low-mass vector-meson production at forward rapidity in $p$$+$$p$ collisions at $\\sqrt{s}=200$ GeV
Adare, A; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Ta'ani, H; Alexander, J; Alfred, M; Andrews, K R; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Asano, H; Aschenauer, E C; Atomssa, E T; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Bandara, N S; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Beaumier, M; Beckman, S; Belmont, R; Ben-Benjamin, J; Bennett, R; Berdnikov, A; Berdnikov, Y; Black, D; Blau, D S; Bok, J; Bok, J S; Boyle, K; Brooks, M L; Broxmeyer, D; Bryslawskyj, J; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Castera, P; Chen, C -H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; del Valle, Z Conesa; Connors, M; Csanád, M; Csörgő, T; Dairaku, S; Datta, A; Daugherity, M S; David, G; Dayananda, M K; DeBlasio, K; Dehmelt, K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Ding, L; Dion, A; Do, J H; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; D'Orazio, L; Efremenko, Y V; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Feege, N; Fields, D E; Finger, M; Jr., \\,; Fleuret, F; Fokin, S L; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fusayasu, T; Gal, C; Gallus, P; Garg, P; Garishvili, I; Ge, H; Giordano, F; Glenn, A; Gong, X; Gonin, M; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Gu, Y; Gunji, T; Guo, L; Guragain, H; Gustafsson, H -Å; Hachiya, T; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Han, S Y; Hanks, J; Harper, C; Hasegawa, S; Hashimoto, K; Haslum, E; Hayano, R; He, X; Hemmick, T K; Hester, T; Hill, J C; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Hoshino, T; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Imazu, Y; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Ivanishchev, D; Iwanaga, Y; Jacak, B V; Jeon, S J; Jezghani, M; Jia, J; Jiang, X; John, D; Johnson, B M; Jones, T; Joo, E; Joo, K S; Jouan, D; Jumper, D S; Kamin, J; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kazantsev, A V; Kempel, T; Key, J A; Khachatryan, V; Khanzadeev, A; Kihara, K; Kijima, K M; Kim, B I; Kim, C; Kim, D H; Kim, D J; Kim, E -J; Kim, H -J; Kim, M; Kim, Y -J; Kim, Y K; Kinney, E; Kiss, Á; Kistenev, E; Klatsky, J; Kleinjan, D; Kline, P; Koblesky, T; Kochenda, L; Kofarago, M; Komkov, B; Konno, M; Koster, J; Kotov, D; Král, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Leitgab, M; Li, X; Lim, S H; Levy, L A Linden; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Makek, M; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Meles, A; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Miller, A J; Milov, A; Mishra, D K; Mitchell, J T; Miyachi, Y; Miyasaka, S; Mizuno, S; Mohanty, A K; Montuenga, P; Moon, H J; Moon, T; Morino, Y; Morreale, A; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Mwai, A; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakagomi, H; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nattrass, C; Netrakanti, P K; Newby, J; Nguyen, M; Nihashi, M; Niida, T; Nouicer, R; Novitzky, N; Nyanin, A S; Oakley, C; O'Brien, E; Ogilvie, C A; Oka, M; Okada, K; Koop, J D Orjuela; Oskarsson, A; Ouchida, M; Ozaki, H; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, S; Park, S K; Pate, S F; Patel, L; Patel, M; Pei, H; Peng, J -C; Pereira, H; Perepelitsa, D V; Perera, G D N; Peressounko, D Yu; Perry, J; Petti, R; Pinkenburg, C; Pinson, R; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reygers, K; Reynolds, D; Riabov, V; Riabov, Y; Richardson, E; Riveli, N; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosendahl, S S E; Rowan, Z; Rubin, J G; Sahlmueller, B; Saito, N; Sakaguchi, T; Sako, H; Samsonov, V; Sano, S; Sarsour, M; Sato, S; Sato, T; Savastio, M; 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; Shim, H H; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Sodre, T; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stepanov, M; Stoll, S P; Sugitate, T; Sukhanov, A; Sumita, T; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Thomas, D
2014-01-01
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low mass vector meson, $\\omega$, $\\rho$, and $\\phi$, production through the dimuon decay channel at forward rapidity ($1.2<|y|<2.2$) in $p$$+$$p$ collisions at $\\sqrt{s}=200$ GeV. The differential cross sections for these mesons are measured as a function of both $p_T$ and rapidity. We also report the integrated differential cross sections over $1
Institute of Scientific and Technical Information of China (English)
郭华; 胡翔
2001-01-01
The ω-and p-meson tensor couplings to nucleons in a derivative scalar coupling model for finite nuclei are investigated. The influences of the tensor couplings on the binding energies per nucleon, the root-mean-square charge radii, spin-orbit splittings and single particle energies are discussed. The obtained results show that the spin-orbit splittings for finite nuclei are more sensitive to the ω-meson tensor coupling.
On nature of scalar and tensor mesons from the analysis of processes pi-pi-> pi-pi, K-Kbar, eta-eta
Surovtsev, Y S; Krupa, D; Nagy, M; Surovtsev, Yu. S.
2006-01-01
Analysis of the isoscalar S- and D-waves of processes pi-pi-> pi-pi, K-Kbar, eta-eta is carried out aimed at studying the status and QCD nature of scalar and tensor mesons below 2 GeV and 2.3 GeV, respectively. Assignment of these mesons to lower scalar and tensor nonets is proposed.
Das, Swapan
2015-01-01
The coherent $\\eta$ meson energy $E_\\eta$ distribution spectra in the proton nucleus reaction have been calculated to investigate the $\\pi^0 - \\eta$ mesons' interference, in addition to the study of resonance $N^*$ dynamics in the nucleus. The elementary reaction occurring in the nucleus is assumed to proceed as $ pN \\to pN^* $; $ N^* \\to N\\eta $. Born terms in the intermediate state is also considered. In a scalar-isovector nucleus, this reaction occurs because of $\\pi^0$ and $\\eta$ meson exchange interactions for the forward going proton and $\\eta$ meson; other meson exchange potentials do not contribute in this process. The sensitivity of the cross section to the hadron nucleus interactions, and the beam energy dependence of the cross section are studied for this reaction.
Institute of Scientific and Technical Information of China (English)
XIE Chuan-Mei; LI Heng-Mei; WAN Shao-Long
2009-01-01
The wave functions and electromagnetic form factor of charged scalar mesons are studied with a modified vector-vector flat-bottom potential model under the framework of the Schwinger-Dyeon and Bethe-Salpeter equations.The obtained results agree well with other theories.
Pallante, E.
2015-01-01
We discuss properties of non-Abelian gauge theories that change significantly across the lower edge of the conformal window. Their probes are the topological observables, the meson spectrum and the scalar glueball operator. The way these quantities change tells about the way conformal symmetry is
Pseudo-scalar meson form factors with maximally twisted Wilson fermions at Nf = 2
Simula, S
2007-01-01
We present preliminary results for various electroweak form factors of pseudo-scalar mesons using the tree-level improved Symanzik gauge action and the maximally twisted mass fermionic action with Nf = 2 dynamical flavors. Our results, obtained for both light and heavy quark masses at a single lattice spacing (a ~ 0.09 fm) and at a single lattice volume (V * T = 24**3 * 48), exhibit a quite remarkable statistical precision thanks to the use of all-to-all quark propagators computed with a stochastic method. Moreover very low values of the four-momentum transfer are achieved by making use of twisted boundary conditions on the valence quark fields. The mass dependence of the pion charge radius is analyzed using Chiral Perturbation Theory, obtaining clear evidence of relevant two-loop contributions. The universal Isgur-Wise function is computed from heavy-to-heavy electromagnetic transitions and its slope in the case of $u(d)$ spectator quarks is found to be rho(IW)**2 = 0.77 +/- 0.28, where the error is statisti...
Dey, Biplab; Ireland, David G; Meyer, Curtis A
2010-01-01
The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins for all particles quantized along a single direction, the longitudinal beam direction, is used for consistency and clarity in interpretation. A single spin-quantization axis for all particles enables the amplitudes to be written in a manifestly covariant fashion with simple relations to those of the well-known CGLN formalism. Possible sign discrepancies between theoretical amplitude-level expressions and experimentally measurable intensity profiles are dealt with carefully. Our motivation is to provide a coherent framework for coupled-channel partial-wave analysis of several meson photoproduction reactions, incorporating recently published and forthcoming polarization data from Jefferson Lab.
Lattice investigation of the scalar mesons a_0(980) and \\kappa\\ using four-quark operators
Alexandrou, Constantia; Brida, Mattia Dalla; Gravina, Mario; Scorzato, Luigi; Urbach, Carsten; Wagner, Marc
2012-01-01
We carry out an exploratory study of the isospin one a0(980) and the isospin one-half kappa scalar mesons using Nf=2+1+1 Wilson twisted mass fermions at one lattice spacing. The valence strange quark is included as an Osterwalder-Seiler fermion with mass tuned so that the kaon mass matches the corresponding mass in the unitary Nf=2+1+1 theory. We investigate the internal structure of these mesons by using a basis of four-quark interpolating fields. We construct diquark-diquark and molecular-typecinterpolating fields and analyse the resulting correlation matrices keeping only connected contributions. For both channels, the low-lying spectrum is found to be consistent with two-particle scattering states. Therefore, our analysis shows no evidence for an additional state that can be interpreted as either a tetraquark or a tightly-bound molecular state.
Deep inelastic scattering off scalar mesons in the 1/N expansion from the D3D7-brane system
Kovensky, Nicolas; Schvellinger, Martin
2016-01-01
Deep inelastic scattering (DIS) of charged leptons off scalar mesons in the $1/N$ expansion is studied by using the gauge/gravity duality. We focus on the D3D7-brane system and investigate the corresponding structure functions by considering both the high energy limit and the $1/N$ expansion. These limits do not commute. From the D7-brane DBI action we derive a Lagrangian at sub-leading order in the D7-brane fluctuations and obtain a number of interactions some of which become relevant for two-hadron final-state DIS. By considering first the high energy limit followed by the large $N$ one, our results fit lattice QCD data within $1.27\\%$ for the first three moments of $F_2$ for the lightest pseudoscalar meson.
Deep inelastic scattering off scalar mesons in the 1/N expansion from the D3D7-brane system
Energy Technology Data Exchange (ETDEWEB)
Jorrin, David; Kovensky, Nicolas; Schvellinger, Martin [Instituto de Física La Plata-UNLP-CONICET and,Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata,Calle 49 y 115, C.C. 67 (1900) La Plata, Buenos Aires (Argentina)
2016-12-01
Deep inelastic scattering (DIS) of charged leptons off scalar mesons in the 1/N expansion is studied by using the gauge/gravity duality. We focus on the D3D7-brane system and investigate the corresponding structure functions by considering both the high energy limit and the 1/N expansion. These limits do not commute. From the D7-brane DBI action we derive a Lagrangian at sub-leading order in the D7-brane fluctuations and obtain a number of interactions some of which become relevant for two-hadron final-state DIS. By considering first the high energy limit followed by the large N one, our results fit lattice QCD data within 1.27% for the first three moments of F{sub 2} for the lightest pseudoscalar meson.
Energy Technology Data Exchange (ETDEWEB)
Biplab Dey, Michael E. McCracken, David G. Ireland, Curtis A. Meyer
2011-05-01
The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins for all particles quantized along a single direction, the longitudinal beam direction, is used for consistency and clarity in interpretation. A single spin-quantization axis for all particles enables the amplitudes to be written in a manifestly covariant fashion with simple relations to those of the well-known CGLN formalism. Possible sign discrepancies between theoretical amplitude-level expressions and experimentally measurable intensity profiles are dealt with carefully. Our motivation is to provide a coherent framework for coupled-channel partial-wave analysis of several meson photoproduction reactions, incorporating recently published and forthcoming polarization data from Jefferson Lab.
Photoproduction of the scalar mesons $f_0(500)$ and $f_0(980)$ off the nucleon
Lee, Je-Hee; Ryu, Hui-Young; Yu, Byung-Geel
2016-01-01
We investigate photoproduction of the scalar mesona off the nucleon, using the effective Lagrangians and the Regge approach. We first study $f_0(980)$ photoproduction, replacing the Feynman propagator with the Regge ones for the $\\rho$-meson exchange in the $t$-channel. The model parameters are fixed by reproducing the experimental data on the differential cross section. We then apply the same method to $f_0(500)$ or $\\sigma$ photoproduction with the same parameters for the Regge propagator. Since the threshold energy of the $f_0(500)$ production is rather low, $N^*$ resonances, which can decay into the nucleon and two pions in the isoscalar and scalar state, can come into play in the $s$-channel. To examine the effects of the $N^*$ resonances, we set up two models to look into the respective contribution of the $N^*$ resonances. We find that in particular $N^*(1440)$ and $N^*(1680)$ play important roles in $f_0(500)$ photoproduction. We discuss the physical implications of the present results.
The scalar mesons in decays of the ψ and ϒ families
Energy Technology Data Exchange (ETDEWEB)
Surovtsev, Yu.S. [Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141 980 (Russian Federation); Bydžovský, P. [Nuclear Physics Institute, Czech Academy of Sciences, 25068 Řež (Czech Republic); Gutsche, T. [Institut für Theoretische Physik, Universität Tübingen, Kepler Center for Astro and Particle Physics, Auf der Morgenstelle 14, D–72076 Tübingen (Germany); Kamiński, R. [Institute of Nuclear Physics, Polish Academy of Sciences, Cracow 31342 (Poland); Lyubovitskij, V.E. [Institut für Theoretische Physik, Universität Tübingen, Kepler Center for Astro and Particle Physics, Auf der Morgenstelle 14, D–72076 Tübingen (Germany); Nagy, M. [Institute of Physics, Slovak Academy of Sciences, Bratislava 84511 (Slovakia)
2013-12-15
The f{sub 0} mesons are studied in a combined analysis of data on isoscalar S-wave processes ππ→ππ,KK{sup ¯},ηη and on decays J/ψ→ϕ(ππ,KK{sup ¯}),ψ(2S)→J/ψ(ππ) and ϒ(2S)→ϒ(1S)ππ from the Argus, Crystal Ball, CLEO, CUSB, DM2, Mark II, Mark III, and BES III Collaborations. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. Some spectroscopic implications from results of the analysis are discussed.
The scalar mesons in decays of the ψ and ϒ families
Surovtsev, Yu. S.; Bydžovský, P.; Gutsche, T.; Kamiński, R.; Lyubovitskij, V. E.; Nagy, M.
2013-12-01
The f0 mesons are studied in a combined analysis of data on isoscalar S-wave processes ππ→ππ,KK¯,ηη and on decays J/ψ→ϕ(ππ,KK¯),ψ(2S)→J/ψ(ππ) and ϒ(2S)→ϒ(1S)ππ from the Argus, Crystal Ball, CLEO, CUSB, DM2, Mark II, Mark III, and BES III Collaborations. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. Some spectroscopic implications from results of the analysis are discussed.
Discretization effects and the scalar meson correlator in mixed-action lattice simulations
Aubin, C; Van de Water, Ruth S
2008-01-01
We study discretization effects in a mixed-action lattice theory with domain-wall valence quarks and Asqtad-improved staggered sea quarks. At the level of the chiral effective Lagrangian, discretization effects in the mixed-action theory give rise to two new parameters as compared to the lowest order Lagrangian for staggered fermions -- the residual quark mass, m_res, and the mixed valence-sea meson mass-splitting, Delta_mix. We find that the size of m_res is approximately four times smaller than our lightest valence quark mass on our coarser lattice spacing, and comparable to that of simulations by RBC and UKQCD. We also find that the size of Delta_mix is comparable to the smallest of the staggered meson taste-splittings measured by MILC. Because lattice artifacts are different in the valence and sea sectors of the mixed-action theory, they give rise to unitarity-violating effects that disappear in the continuum limit. Such effects are expected to be mild for many quantities of interest, but are significant ...
Isentropic thermodynamics and scalar-mesons properties near the QCD critical end point
Energy Technology Data Exchange (ETDEWEB)
Costa, Pedro [University of Coimbra, CFisUC, Department of Physics, Coimbra (Portugal)
2016-08-15
We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov-Nambu-Jona-Lasinio model with entanglement interaction giving special attention to the π and σ -mesons properties, namely the decay widths σ→ππ, for several conditions around the CEP: we focus on the possible σ→ππ decay along the isentropic trajectories close to the CEP since the hydrodynamical expansion of a heavy-ion collision fireball nearly follows trajectories of constant entropy. It is expected that the type of transition the dense medium goes through as it expands after the thermalization determines the behavior of this decay. It is shown that no pions are produced from the sigma decay in the chirally symmetric phase if the isentropic lines approach the first-order line from chemical potentials above it. Near the CEP or above the σ→ππ decay is possible with a high decay width. (orig.)
Isentropic thermodynamics and scalar-mesons properties near the QCD critical end point
Costa, Pedro
2016-01-01
We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov$-$Nambu$-$Jona-Lasinio model with entanglement interaction giving special attention to the $\\pi$ and $\\sigma$-mesons properties, namely the decay widths $\\sigma\\rightarrow\\pi\\pi$, for several conditions around the CEP: we focus on the possible $\\sigma\\rightarrow\\pi\\pi$ decay along the isentropic trajectories close to the CEP since the hydrodynamical expansion of a heavy-ion collision fireball nearly follows trajectories of constant entropy. It is expected that the type of transition the dense medium goes through as it expands after the thermalization determines the behavior of this decay. It is shown that no pions are produced from the sigma decay in the chirally symmetric phase if the isentropic lines approach the first order line from chemical potentials above it. Near the CEP or above the $\\sigma\\rightarrow\\pi\\pi$ decay is possible with a high decay width.
The Scalar $q \\overline{q}$ nonet and Confirmation of the broad sigma meson
Törnqvist, N A
1996-01-01
The available data on the a0(980), f0(980), f0(1300) and K*0(1430) meso= ns are fitted as a distorted 0++ nonet using only 6 parameters and a very genera= l model. This includes all light two-pseudoscalar thresholds, constraints f= rom Adler zeroes, flavour symmetric couplings, unitarity and physically accep= table analyticity. One finds that with the large overall coupling there can app= ear two physical resonance poles from only one q bar q state. Thus the f0(980= ) and f0(1300) resonance poles are two manifestations of the same s bar s state= . On the other hand, the u bar u state, when unitarized and strongly distorted= by hadronic mass shifts, becomes an extremely broad Breit-Wigner-like backgr= ound, with its pole at s =3D(0.158-i0.235) GeV^2. This is the sigma meson requi= red by models for spontaneous breaking of chiral symmetry.
Photoproduction of Scalar Mesons Using the CEBAF Large Acceptance Spectrometer (CLAS)
Chandavar, Shloka K.
The search for glueballs has been ongoing for several decades. The lightest glueball has been predicted by quenched lattice QCD to have mass in the range of 1.0--1.7 GeV and JPC = 0++ . The mixing of glueball states with neighbouring meson states complicates their identification and hence several experiments have been carried out over the years to study the glueball candidates. By analyzing the decay channels and production mechanisms of these candidates, their glueball content can theoretically be determined. In reality, a lot of confusion still exists about the status of these glueball candidates. The f0(1500) is one of several contenders for the lightest glueball, which has been extensively studied in several different kinds of experiments. However, there exists no photoproduction data on this particle. In the analysis presented in this dissertation, the presence of the f0(1500) in the KS 0KS0 channel is investigated in photoproduction using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility, also called Jefferson Lab (JLab). This is done by studying the reaction, gammap → fJp → KS0 KS0p → 2(pi +pi-)p using data from the g12 experiment. A clear peak is seen at 1500 MeV in the background subtracted data. This is enhanced if the momentum transfer is restricted to be less than 1 GeV2. Comparing with simulations, it is seen that this peak is associated with t channel production mechanism. The f 2'(1525) has a mass of 1525 MeV and a width of 73 MeV, and hence there is a possibility of it contributing to the peak observed in our data. A moments analysis seems to suggest some presence of a D wave, however, the low acceptance at forward and backward angles prohibits a definitive conclusion.
Aitala, E M; Amato, S; Anjos, J C; Appel, J A; Ashery, D; Banerjee, S; Bediaga, I; Blaylock, G; Bracker, S B; Burchat, P R; Burnstein, R A; Carter, T; Carvalho, H S; Copty, N K; Cremaldi, L M; Darling, C; Denisenko, K; Devmal, S; Fernandez, A; Fox, G F; Gagnon, P; Göbel, C; Gounder, K; Halling, A M; Herrera, G; Hurvits, G; James, C; Kasper, P A; Kwan, S; Langs, D C; Leslie, J; Lundberg, B; Magnin, J; Massafferri, A; MayTal-Beck, S; Meadows, B; de Mello Neto, J R T; Mihalcea, D; Milburn, R H; de Miranda, J M; Napier, A; Nguyen, A; d'Oliveira, A B; O'Shaughnessy, K; Peng, K C; Perera, L P; Purohit, M V; Quinn, B; Radeztsky, S; Rafatian, A; Reay, N W; Reidy, J J; dos Reis, A C; Rubin, H A; Sanders, D A; Santha, A K S; Santoro, A F S; Schwartz, A J; Sheaff, M; Sidwell, R A; Slaughter, A J; Sokoloff, M D; Solano Salinas, C J; Stanton, N R; Stefanski, R J; Stenson, K; Summers, D J; Takach, S; Thorne, K; Tripathi, A K; Watanabe, S; Weiss-Babai, R; Wiener, J; Witchey, N; Wolin, E; Yang, S M; Yi, D; Yoshida, S; Zaliznyak, R; Zhang, C
2002-09-16
We study the Dalitz plot of the decay D(+)-->K(-)pi(+)pi(+) with a sample of 15090 events from Fermilab experiment E791. Modeling the decay amplitude as the coherent sum of known Kpi resonances and a uniform nonresonant term, we do not obtain an acceptable fit. If we allow the mass and width of the K(*)(0)(1430) to float, we obtain values consistent with those from PDG but the chi(2) per degree of freedom of the fit is still unsatisfactory. A good fit is found when we allow for the presence of an additional scalar resonance, with mass 797+/-19+/-43 MeV/c(2) and width 410+/-43+/-87 MeV/c(2). The mass and width of the K(*)(0)(1430) become 1459+/-7+/-5 MeV/c(2) and 175+/-12+/-12 MeV/c(2), respectively. Our results provide new information on the scalar sector in hadron spectroscopy.
The Search and Study of Low-Mass Scalar Mesons in the Reaction np --> np Pi+Pi- at Pn = 5.20 Gev/c^2
Troyan, Yu. A.; Beljaev, A. V.; Troyan, A. Yu.; Plekhanov, E. B.; Jerusalimov, A. P.; Arakelian, S. G.
2008-01-01
Using irradiation of a 1-meter Hydrogen Bubble Chamber (LHE JINR) by a quasimonochromatic neutron beam with impulse Pn=(5.20 +/- 0.12)GeV/c produced after acceleration of deuterons in the synchrophasotron (LHE JINR) 2560 events of reaction np-->npPi+Pi- were selected. After supplementary sorting out the events where a secondary proton flies forward in the general c.m.s. of reaction in the effective mass spectrum of Pi+Pi- - combinations, there were nine peculiarities found out at masses 350, ...
The nature of the lightest scalar meson, its N_c behaviour and semi-local duality
Energy Technology Data Exchange (ETDEWEB)
JR Pelaez, MR Pennington, J Ruiz de Elvira, DJ Wilson
2011-12-01
One-loop unitarized Chiral Perturbation Theory (UChPT) calculations, suggest a different N{sub c} behaviour for the {sigma} or f{sub 0}(600) and {rho}(770) mesons: while the {rho} meson becomes narrower with N{sub c}, as expected for a {bar q}q meson, the f{sub 0}(600) contribution to the total cross section below 1 GeV becomes less and less important. Here we review our recent work where we have shown, by means of finite energy sum rules, that a different N{sub c} behavior for these resonances may lead to a conflict with semi-local duality for large N{sub c}, since local duality requires a cancellation between the f{sub 0}(600) and {rho}(770) amplitudes. However, UChPT calculations also suggest a subdominant {bar q}q component for the f{sub 0}(600) with a mass above 1 GeV and this can restore semi-local duality, as we show.
Surovtsev, Yurii S; Gutsche, Thomas; Kaminski, Robert; Lyubovitskij, Valery E; Nagy, Miroslav
2013-01-01
The $f_0$ mesons are studied in a combined analysis of data on the isoscalar S-wave processes $\\pi\\pi\\to\\pi\\pi,K\\overline{K},\\eta\\eta$ and on decays $J/\\psi\\to\\phi(\\pi\\pi, K\\overline{K})$, $\\psi(2S)\\to J/\\psi(\\pi\\pi)$, and $\\Upsilon(2S)\\to\\Upsilon(1S)\\pi\\pi$ from the Argus, Crystal Ball, CLEO, CUSB, DM2, Mark II, Mark III, and BESIII collaborations. The method of analysis, based on analyticity and unitarity and using an uniformization procedure, is set forth with some details. Some spectroscopic implications from results of the analysis are discussed.
Directory of Open Access Journals (Sweden)
Gorazd Cvetič
2015-05-01
Full Text Available Some of the outstanding questions of particle physics today concern the neutrino sector, in particular whether there are more neutrinos than those already known and whether they are Dirac or Majorana particles. There are different ways to explore these issues. In this article we describe neutrino-mediated decays of charged pseudoscalar mesons such as π±,K± and B±, in scenarios where extra neutrinos are heavy and can be on their mass shell. We discuss semileptonic and leptonic decays of such kinds. We investigate possible ways of using these decays in order to distinguish between the Dirac and Majorana character of neutrinos. Further, we argue that there are significant possibilities of detecting CP violation in such decays when there are at least two almost degenerate Majorana neutrinos involved. This latter type of scenario fits well into the known neutrino minimal standard model (MSM which could simultaneously explain the Dark Matter and Baryon Asymmetry of the Universe.
Energy Technology Data Exchange (ETDEWEB)
Pelaez, J. R. [Univ. Complutense Madrid (Spain); Pennington, Michael R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); de Elvira, J. Ruiz [Univ. Complutense Madrid (Spain); Wilson, D. J. [Argonne National Lab. (ANL), Argonne, IL (United States)
2011-11-01
The leading 1/N{sub c} behavior of Unitarized Chiral Perturbation Theory distinguishes the nature of the {rho} and the {sigma}. At one loop order the {rho} is a {bar q}q meson, while the {sigma} is not. However, semi-local duality between resonances and Regge behaviour cannot be satisfied for larger N{sub c}, if such a distinction holds. While the {sigma} at N{sub c}= 3 is inevitably dominated by its di-pion component, Unitarised Chiral Perturbation Theory beyond one loop order reveals that as N{sub c} increases above 6-8, the {sigma} has a sub-dominant {bar q}q fraction up at 1.2 GeV. Remarkably this ensures semi-local duality is fulfilled for the range of N{sub c} {approx}< 15-30, where the unitarization procedure adopted applies.
Energy Technology Data Exchange (ETDEWEB)
Phillips, D.R.; Afnan, I.R. [Department of Physics, The Flinders University of South Australia, GPO Box 2100, Adelaide 5001 (Australia)
1996-10-01
The four-dimensional {ital NN}-{pi}{ital NN} equations are adapted to the case of scalar particles with a {phi}{sup 2}{sigma} interaction Lagrangian and solved for energies below the {sigma}-production threshold. This is achieved in the approximation where {phi}{sigma} scattering is dominated by the {ital s}-channel {phi}-pole term. The importance of the removal of double counting is investigated and a detailed comparison of the results of a covariant coupled-channel formulation and the Bethe-Salpeter equation in the ladder and ladder plus crossed-box approximations is presented. A brief discussion of the extension of the method to energies above the {sigma}-production threshold is given. {copyright} {ital 1996 The American Physical Society.}
Solving the four-dimensional NN-πNN equations for scalars below the meson-production threshold
Phillips, D. R.; Afnan, I. R.
1996-10-01
The four-dimensional NN-πNN equations are adapted to the case of scalar particles with a φ2σ interaction Lagrangian and solved for energies below the σ-production threshold. This is achieved in the approximation where φσ scattering is dominated by the s-channel φ-pole term. The importance of the removal of double counting is investigated and a detailed comparison of the results of a covariant coupled-channel formulation and the Bethe-Salpeter equation in the ladder and ladder plus crossed-box approximations is presented. A brief discussion of the extension of the method to energies above the σ-production threshold is given.
Achasov, N N
2006-01-01
The high-statistical KLOE data on the $\\phi\\to\\pi^0\\pi^0\\gamma$ decay are described simultaneously with the data on $\\pi\\pi$ scattering and the $\\pi\\pi\\to K\\bar K$ reaction. The description is carried out taking into account the chiral shielding of the putative $\\sigma (600)$ meson and it's mixing with the well-established $f_0(980)$ meson. It is shown that the data don't contradict the existence of the $\\sigma (600)$ meson and yield evidence in favor of the four-quark nature of the $\\sigma (600)$ and $f_0(980)$ mesons.
Troyan, Yu A; Troyan, A Y; Plekhanov, E B; Jerusalimov, A P; Arakelian, S G; Troyan, Yu. A.
2006-01-01
The production and properties of the resonances in the system of Pi+Pi- were studied in the reaction np --> npPi+Pi- at the momentum of incident neutrons Pn=(5.20 +/- 0.12)GeV/c. In this work in comparison with previous ones we made more hard selection of events taking into account track measurement precise. In the distribution of the Pi+Pi- combinations effective masses we have found 8 peculiarities. All the observable peculiarities have spins equal to zero. There were no corresponding picks in the Pi-PI- and Pi-Pi0 - systems in the reactions np --> npPi+Pi- Pi- and np --> npPi-Pi0. So, we have observed a row of resonances with a set of quantum numbers 0+(0++) -- SIGMA0 - mesons decaying on the channel SIGMA0 --> Pi+Pi-. The obtained in other experiments masses coincide with the sequence of masses observed in our experiment. Especially good coincidence can be obtained in the K-matrix approach (see RPP).
Mapelli, Alessandro
2014-01-01
Low mass on - detec tor cooling systems are being developed and stud ied by the Detector Technology group (PH - DT) in the CERN Physics Department in close collaboration with LHC and non - LHC experiments . Two approaches are currently being investigated. The first approach, for barrel configurations, consists in integrating the cooli ng apparatus in light mechanical structures support ing the detectors. In this case , the thermal management can be achieved either with light cooling pipes and thin plates or with a network of microchannels embedded in thin strips of silicon or polyimide . Both configuratio ns are being investigated in the context of the 2018 upgrade program of the ALICE Inner Tracking System (ITS). Moreover, it is also possible to use a s ilicon microchannel cooling device itself as structural support for the detectors and electronics. Such a configur ation has been adopted by the NA62 collaboration for the ir GigaTracKer (GTK) as well as by the LHCb collaboration for the 2018 major upgrade of...
Two Higgs doublet model and leptoquarks constraints from D meson decays
Barranco, J; Macias, V Gonzalez; Lopez-Lozano, L
2014-01-01
We use a combined analysis of the semileptonic and leptonic branching ratios of the D mesons to constrain scalar leptoquark interactions and charged higgs-like interactions. For the THDM type II, we found that a low mass 6.3GeV < m_{H^+} < 63.1GeV for the charged Higgs is favored at 90% C.L. although at 95% there is still agreement with other constraints. We find for the leptoquark states a more restrictive bound than previous analysis.
Energy Technology Data Exchange (ETDEWEB)
Girard, P
2000-04-19
The subject of this thesis is an experimental study of the pseudo-scalar mesons photoproduction on the proton in an energy range from {radical}S=1450 MeV to 2100 MeV. It has been realized with the 4{pi} CLAS detector of Th. Jefferson Laboratory. A software has been developed in order to perform the time calibration of the tagging system, and allowed us to measure a time resolution of 150 ps (FWHM). Gla Data have been analyzed. We determine CLAS energy resolution and show that these values are compatible with those given in the detector conceptual design report. Information from the analysis of the neutral mesons photoproduction channels and from the study of the p({gamma}, p{pi}{sup +}{pi}{sup -}) reaction has been used to develop correction methods, applied to raw data, in order to extract the differential cross-sections for the reactions p({gamma}, p){pi}{sup 0}. New data points are shown and compared to the VPI multipole analysis. A preliminary study of the p({gamma}, p){eta} is stated in order to establish the method limits. An anomaly has been found in the data at a total center of mass energy of {radical}s = 1790 MeV and is discussed. (author)
Patkós, András; Szépfalusy, P; Szep, Zs.
2002-01-01
The relationship between the scalar-isoscalar spectral function and the second Riemann sheet pole in the same channel is analyzed in an effective linear $\\sigma$-model with help of an expansion in the number of the Goldstone-bosons. A generic scenario is suggested for the temperature/density driven evolution of the pole location. An extended temperature range, correlated with characteristic pole locations, is found where the phenomenon of threshold enhancement takes place in the spectral function.
Axially Symmetric Cosmological Mesonic Stiff Fluid Models in Lyra's Geometry
Gad, Ragab M
2009-01-01
In this paper, we obtained a new class of axially symmetric cosmological mesonic stiff fluid models in the context of Lyra's geometry. Expressions for the energy, pressure and the massless scalar field are derived by considering the time dependent displacement field. We found that the mesonic scalar field depends on only $t$ coordinate. Some physical properties of the obtained models are discussed.
Dynamically Generated Open and Hidden Charm Meson Systems
Gamermann, D; Strottman, D D; Vacas, M J V
2006-01-01
The lowest order chiral Lagrangian successfully applied to study the interaction of the SU(3) octet of pseudo-scalar mesons is generalized to include all mesons from the SU(4) 15-plet of pseudo-scalar mesons. Exchanges of heavy vector mesons, which are indirectly taken into account via this approach, are suppressed. Unitarization in coupled channels leads to dynamical generation of resonances in the open and hidden charm sectors. In particular, for reasonable values of the input, a new narrow scalar resonance in the hidden charm sector appears with a mass of 3.7 GeV.
Scalar f sub 0 (980) and sigma(500) meson exchange in phi decays into pi sup 0 pi sup 0 gamma
Bramon, A; Lucio, M J L; Napsuciale, M; Pancheri, G
2002-01-01
The complementarity between chiral perturbation theory and the linear sigma model is exploited to study pi sup 0 pi sup 0 production in phi radiative decays, where the effects of the f sub 0 (980) scalar resonance, and those of its more controversial sigma(500) partner, should become manifest via the phi->K sup + K sup - (gamma)-> pi sup 0 pi sup 0 gamma decay chain. The recently reported data on phi-> pi sup 0 pi sup 0 gamma coming from the VEPP-2M e sup + e sup - collider in Novosibirsk and the DA PHI NE phi-factory in Frascati can be reasonably described in our approach, which we propose as a promising first step towards more detailed analyses. The f sub 0 (980) contribution, which appears as a moderately narrow peak at the high part of the dipion mass spectrum, can be interpreted as the isoscalar member of the scalar nonet with a large f sub 0 K anti K coupling and an f sub 0 pi pi coupling suppressed by almost ideal sigma-f sub 0 mixing. Indeed, the mixing angle in the flavor basis is found to be phi sub...
Low mass dimuon production with the ALICE muon spectrometer
Casula, Ester Anna Rita
Low mass vector meson ($\\rho$, $\\omega$, $\\phi$) production provides key information on the hot and dense state of strongly interacting matter produced in high-energy heavy ion collisions (called Quark Gluon Plasma). Strangeness enhancement is one of the possible signatures of the Quark Gluon Plasma formation and can be accessed through the measurement of $\\phi$ meson production with respect to $\\rho$ and $\\omega$ mesons, while the measurement of the $\\phi$ nuclear modification factor provides a powerful tool to probe the production dynamics and hadronization process in relativistic heavy ion collisions. Vector mesons can be detected through their decays into muon pairs with the ALICE muon spectrometer. This thesis presents the results on the measurement of the $\\phi$ differential cross section, as a function of the transverse momentum, in pp collisions at $\\sqrt{s}$ = 2.76 TeV; the measurement of the $\\phi$ yield and of the nuclear modification factor $R_{pA}$ at forward and backward rapidity, as a function...
Chiral Restoration and the Scalar and Vector Correlations in Hot and Dense Matter
Kunihiro, T
2003-01-01
First, it is pointed out that hadron/nuclear physics based on QCD should be regarded as ``condensed matter physics'' of the QCD vacuum. We indicate that phase shift analyses which respect chiral symmetry (ChS), analyticity and crossing symmetry of the scattering amplitude show the $sigma$ meson pole in the s-channel in the low mass region as well as the $rho$ meson pole in the $t$-channel in the pipi scattering in the scalar channel. We review recent developments in exploring possible precursory phenomena of partial restoration of chis in nuclear medium by examining the spectral function in the scalar and the vector channels. We emphasize that the wave function renormalization of the pion in the medium plays an essential role to induce the decrease of the pion decay constant as the order parameter of chiral transition. An emphasis is also put on the importance to examine the scalar and vector channels simultaneously for exploring the possible restoration of chiral symmetry.
Branching fractions and direct CP violation in charmless three-body decays of B mesons
Cheng, Hai-Yang; Chua, Chun-Khiang
2013-12-01
Charmless three-body decays of B mesons are studied using a simple model based on the framework of the factorization approach. Hadronic three-body decays receive both resonant and nonresonant contributions. Dominant nonresonant contributions to tree-dominated three-body decays arise from the b→u tree transition which can be evaluated using heavy-meson chiral perturbation theory valid in the soft-meson limit. For penguin-dominated decays, nonresonant signals come mainly from the penguin amplitude governed by the matrix elements of scalar densities ⟨M1M2|q¯1q2|0⟩. We use the measurements of B¯0→KSKSKS to constrain the nonresonant component of ⟨KK¯|s¯s|0⟩. The intermediate vector-meson contributions to three-body decays are identified through the vector current, while the scalar-meson resonances are mainly associated with the scalar density. While the calculated direct CP violation in B-→K+K-K- and B-→π+π-π- decays agrees well with experiment in both magnitude and sign, the predicted CP asymmetries in B-→π-K+K- and B-→K-π+π- have incorrect signs when confronted with experiment. It has been conjectured recently that a possible resolution to this CP puzzle may rely on final-state rescattering of π+π- and K+K-. Assuming a large strong phase associated with the matrix element ⟨Kπ|s¯q|0⟩ arising from some sort of power corrections, we fit it to the data of K-π+π- and find a correct sign for π-K+K-. We predict some testable CP violation in B¯0→K+K-π0 and K+K-KS. In the low-mass regions of the Dalitz plot, we find that the regional CP violation is indeed largely enhanced with respect to the inclusive one, though it is still significantly below the data. In this work, strong phases arise from effective Wilson coefficients, propagators of resonances, and the matrix element of the scalar density ⟨M1M2|q¯1q2|0⟩.
Bubble contributions to scalar correlators with mixed actions
Fu, Ziwen
2013-01-01
WWithin mixed-action chiral perturbation theory (MA$\\chi$PT), Sasa's derivation of the bubble contribution to scalar $a_0$ meson is extended to those of scalar $\\kappa$ and $\\sigma$ mesons. We revealed that $\\kappa$ bubble has two double poles and $\\sigma$ bubble contains a quadratic-in-$t^2$ growth factor stemming from the multiplication of two double poles for a general mass tuning of valence quarks and sea quarks. The corresponding preliminary analytical expressions in MA$\\chi$PT with 2+1 chiral valence quarks and 2+1 staggered sea quarks will be helpful for lattice studies of scalar mesons.
Low mass enhanced probability of pion in hadronic matter due to its Landau cut contributions
Ghosh, Sabyasachi
2015-01-01
In the real-time thermal field theory, the pion self-energy at finite temperature and density is evaluated where the different mesonic and baryonic loops are considered. The interactions of pion with the other mesons and baryons in the medium are governed by the effective hadronic Lagrangian densities whose effective strength of coupling constants have been determined from the experimental decay widths of the mesons and baryons. The detail branch cut structures of these different mesonic and baryonic loops are analyzed. The Landau cut contributions of different baryon and meson loops become only relevant around the pion pole and it is completely appeared in presence of medium. The in-medium spectral function of pion has been plotted for different values of temperature, baryon chemical potential as well as three momentum of the pion. A noticeable low mass probability in pion spectral function promise to contribute in the low mass dilepton enhancement via indirect modification of $\\rho$ self-energy for $\\pi\\pi$...
Neutral mesons and disconnected diagrams in Twisted Mass QCD
Michael, C
2007-01-01
We evaluate properties of neutral mesons in Nf=2 dynamical simulations of TMQCD at maximal twist. The pion is explored - establishing the size of the isospin splitting (an order a^2 effect). We investigate the eta' (the Nf=2 flavour singlet pseudoscalar meson) and neutral rho and scalar mesons. We show that disconnected diagrams can be evaluated very efficiently in TMQCD using variance reduction methods.
The Effects of δ Meson on the Neutron Star Cooling
Institute of Scientific and Technical Information of China (English)
许妍; 刘广洲; 吴姚睿; 朱明枫; 喻孜; 王红岩; 赵恩广
2012-01-01
In the framework of the relativistic mean field theory, the isovector scalar interaction is considered by exchanging δ meson to study the influence of δ meson on the cooling properties of neutron star matter. The calculation results show that with the inclusion of δ meson, the neutrino emissivity of the direct Urca processes increases, and thus enhances the cooling of neutron star matter. When strong proton superfluidity is considered, the theoretical cooling curves agree with the observed thermal radiation for isolated neutron stars.
Decay constants of p and d wave heavy light mesons
Energy Technology Data Exchange (ETDEWEB)
Veseli, Sinisa; Dunietz, Isard
1996-07-01
We investigate decay constants of P- and D-wave heavy-light mesons within the mock-meson approach. Numerical estimates are obtained using the relativistic quark model. We also comment on recent calculations of heavy-light pseudo-scalar and vector decay constants.
Mesons at finite baryon density in (2+1)d
Strouthos, C G
2003-01-01
We discuss the critical properies of the three-dimensional Gross-Neveu model at nonzero temperature and nonzero chemical potential. We also present numerical and analytical results for the in-medium interaction due to scalar meson exchange. Further, we discuss in-medium modifications of mesonic dispersion relations and wavefunctions.
DEFF Research Database (Denmark)
Sannino, Francesco
2016-01-01
We construct effective Lagrangians, and corresponding counting schemes, valid to describe the dynamics of the lowest lying large N stable massive composite state emerging in strongly coupled theories. The large N counting rules can now be employed when computing quantum corrections via an effective...... at the electroweak scale. To illustrate the formalism we consider the possibility that the Higgs emerges as: the lightest glueball of a new composite theory; the large N scalar meson in models of dynamical electroweak symmetry breaking; the large N pseudodilaton useful also for models of near-conformal dynamics....... For each of these realisations we determine the leading N corrections to the electroweak precision parameters. The results nicely elucidate the underlying large N dynamics and can be used to confront first principle lattice results featuring composite scalars with a systematic effective approach....
DEFF Research Database (Denmark)
Sannino, Francesco
2016-01-01
We construct effective Lagrangians, and corresponding counting schemes, valid to describe the dynamics of the lowest lying large N stable massive composite state emerging in strongly coupled theories. The large N counting rules can now be employed when computing quantum corrections via an effective...... at the electroweak scale. To illustrate the formalism we consider the possibility that the Higgs emerges as: the lightest glueball of a new composite theory; the large N scalar meson in models of dynamical electroweak symmetry breaking; the large N pseudodilaton useful also for models of near-conformal dynamics....... For each of these realisations we determine the leading N corrections to the electroweak precision parameters. The results nicely elucidate the underlying large N dynamics and can be used to confront first principle lattice results featuring composite scalars with a systematic effective approach....
Scalar and Pseudoscalar Glueballs
Cheng, Hai-Yang
2009-01-01
We employ two simple and robust results to constrain the mixing matrix of the isosinglet scalar mesons $f_0(1710)$, $f_0(1500)$, $f_0(1370)$: one is the approximate SU(3) symmetry empirically observed in the scalar sector above 1 GeV and confirmed by lattice QCD, and the other is the scalar glueball mass at 1710 MeV in the quenched approximation. In the SU(3) symmetry limit, $f_0(1500)$ becomes a pure SU(3) octet and is degenerate with $a_0(1450)$, while $f_0(1370)$ is mainly an SU(3) singlet with a slight mixing with the scalar glueball which is the primary component of $f_0(1710)$. These features remain essentially unchanged even when SU(3) breaking is taken into account. The observed enhancement of $\\omega f_0(1710)$ production over $\\phi f_0(1710)$ in hadronic $J/\\psi$ decays and the copious $f_0(1710)$ production in radiative $J/\\psi$ decays lend further support to the prominent glueball nature of $f_0(1710)$. We deduce the mass of the pseudoscalar glueball $G$ from an $\\eta$-$\\eta'$-$G$ mixing formalism...
Scalar strong interaction hadron theory
Hoh, Fang Chao
2015-01-01
The scalar strong interaction hadron theory, SSI, is a first principles' and nonlocal theory at quantum mechanical level that provides an alternative to low energy QCD and Higgs related part of the standard model. The quark-quark interaction is scalar rather than color-vectorial. A set of equations of motion for mesons and another set for baryons have been constructed. This book provides an account of the present state of a theory supposedly still at its early stage of development. This work will facilitate researchers interested in entering into this field and serve as a basis for possible future development of this theory.
Scalar Glueball Mixing and Decay
Burakovsky, L; Burakovsky, Leonid; Page, Philip R.
1999-01-01
We provide the first explanation of the counter-intuitive scalar glueball couplings to pseudoscalar mesons found in lattice QCD and predict hitherto uncalculated decay modes. Significant a_1 pi and (pi pi)_S (pi pi)_S couplings are found. We demonstrate the equivalence of linear and quadratic mass matrices for glueball-quarkonium mixing. The equivalence of formalisms which deal with a glueball-quarkonium basis and only a quarkonium basis is demonstrated. We show that the f_0(1500) is not the heaviest state arising from glueball-quarkonium mixing for a glueball mass consistent with lattice QCD. The masses and couplings of scalar mesons, as well as their valence content, are calculated.
Screening masses of mesons in 2+1 flavour QCD
Mukherjee, S
2007-01-01
We present results for screening masses of light and strange mesons in 2+1 flavour QCD using improved (p4fat3) staggered fermions on 6x24^3 lattices. We have studied the screening masses of scalar, pseudo-scalar, vector and axial-vector mesons along the line of constant physics, determined by a pion mass ~220 MeV and a kaon mass ~500 MeV. In order to investigate the cut-off and volume dependencies we have also performed studies of the meson screening correlators in the non-interacting theory using the p4 and the standard staggered discretizations.
Low-Mass Diffraction at the LHC
Jenkovszky, Laszlo; Lämsä, Jerry; Orava, Risto
2011-01-01
The expected resonance structure for the low-mass single diffractive states from a Regge-dual model elaborated paper by the present authors in a previous is predicted. Estimates for the observable low-mass single diffraction dissociation (SDD) cross sections and efficiencies for single diffractive events simulated by PYTHIA 6.2 as a function of the diffractive mass are given.
Meson Screening Masses in Thermal QCD
Directory of Open Access Journals (Sweden)
Czerski Piotr
2012-12-01
Full Text Available The quark-gluon plasma (QGP excitations, corresponding to the scalar and pseudoscalar meson quantum numbers, for different temperatures are calculated. Analysis is performed in the Hard Thermal Loop (HTL Approximation and leads to a better understanding of the excitations of QGP in the deconfined phase and is also of relevance for lattice studies.
Photoproduction of vector mesons off nucleons near threshold
Energy Technology Data Exchange (ETDEWEB)
Friman, B. [Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik; Soyeur, M. [Laboratoire National Saturne, Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)
1995-12-31
A simple meson-exchange model is proposed for the photoproduction of {rho}- and {omega}-mesons off protons near threshold. This model provides a good description of the available data and implies a large {rho}-nucleon interaction in the scalar channel ({sigma}-exchange). This phenomenological interaction is applied to estimate the leading contribution to the self-energy of {rho}-mesons in matter. The implications of our calculation for experimental studies of the {rho}-meson mass in nuclei are discussed. (author). 28 refs.
National Aeronautics and Space Administration — A cylindrical, low-mass, high-efficiency, leak-proof cryogenic valve will be designed using composites and exotic metals. Based upon cryogenically-proven Venturi...
National Aeronautics and Space Administration — Two low-mass, linear throttling, high-efficiency, leak-proof cryogenic valves of diameters 1/2" and 4" will be built and tested. Based upon cryogenically-proven...
Energy Technology Data Exchange (ETDEWEB)
Fabiano, N. [Perugia, Univ. (Italy)]|[INFN, Frascati (Italy). Laboratori Nazionali di Frascati
1997-03-01
The possibility of formation for a bound state of a t quark and a lighter one is investigated using potential model predictions and heavy quark effective theory approach. Resulting estimates for the 1S-2S splitting of the energy levels are compared to the total top decay width {Gamma}{sub t}. As for the case of toponium, their conclusions show that the probability of formation for T-mesons is negligibly small due to the high top mass value.
Energy Technology Data Exchange (ETDEWEB)
Steffen Strauch
2009-10-01
This is a brief and selective discussion of meson photoproduction measurements with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Meson photo- production is being used as a tool for various investigations, including the spectroscopy of baryons and mesons and the search for vector-meson medium modifications.
Energy Technology Data Exchange (ETDEWEB)
Steffen Strauch
2009-10-01
This is a brief and selective discussion of meson photoproduction measurements with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Meson photo- production is being used as a tool for various investigations, including the spectroscopy of baryons and mesons and the search for vector-meson medium modifications.
The scalar kappa from D+ -> K- pi+ pi+: Further Studies
Göbel, C
2003-01-01
We briefly review the recent results obtained by Fermilab experiment E791 on the Dalitz plot analysis of the decay D+ -> K- pi+ pi+, where indication for a light Kpi scalar resonance, the kappa, was found. We also present preliminary studies providing further information on the phase behavior of the scalar components at low mass, supporting the previous indication for the kappa.
Eta Meson Production in Proton-Proton and Nuclear Collisions
Norbury, John W.; Dick, Frank
2008-01-01
Total cross sections for eta meson production in proton - proton collisions are calculated. The eta meson is mainly produced via decay of the excited nucleon resonance at 1535 MeV. A scalar quantum field theory is used to calculate cross sections, which also include resonance decay. Comparison between theory and experiment is problematic near threshold when resonance decay is not included. When the decay is included, the comparison between theory and experiment is much better.
Spin O decay angular distribution for interfering mesons in electroproduction
Energy Technology Data Exchange (ETDEWEB)
Funsten, H.; Gilfoyle, G.
1994-04-01
Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W({theta},{psi}). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W({theta},{psi}) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter`s relative orbital angular momentum m-projection; none is {open_quotes}absorbed{close_quotes} into daughter helicities. The decaying meson`s helicity maximally appears in W({theta},{psi}). W({theta},{psi}) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W({theta},{psi}) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W ({theta},{psi}), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters.
Bianchi Type-I cosmological mesonic stiff fluid models in Lyra's geometry
Indian Academy of Sciences (India)
S D Katore; S V Thakare; K S Adhao
2008-07-01
Bianchi Type-I cosmological models in Lyra's geometry are obtained when the source of gravitational field is a perfect fluid coupled with massless mesonic scalar field. Some physical and kinematical properties of the models are also discussed.
Calorimetry of low mass Pu239 items
Energy Technology Data Exchange (ETDEWEB)
Cremers, Teresa L [Los Alamos National Laboratory; Sampson, Thomas E [Los Alamos National Laboratory
2010-01-01
Calorimetric assay has the reputation of providing the highest precision and accuracy of all nondestructive assay measurements. Unfortunately, non-destructive assay practitioners and measurement consumers often extend, inappropriately, the high precision and accuracy of calorimetric assay to very low mass items. One purpose of this document is to present more realistic expectations for the random uncertainties associated with calorimetric assay for weapons grade plutonium items with masses of 200 grams or less.
Charbonnel, Corinne
2008-01-01
Low-mass stars exhibit, at all stages of their evolution, the signatures of complex physical processes that require challenging modeling beyond standard stellar theory. In this review, we recall the most striking observational evidences that probe the interaction and interdependence of various transport processes of chemicals and angular momentum in these objects. We then focus on the impact of atomic diffusion, large scale mixing due to rotation, and internal gravity waves on stellar properties on the main sequence and slightly beyond.
Charbonnel, Corinne; Talon, Suzanne
2008-10-01
Low-mass stars exhibit, at all stages of their evolution, the signatures of complex physical processes that require challenging modeling beyond standard stellar theory. In this review, we recall the most striking observational evidences that probe the interaction and interdependence of various transport processes of chemicals and angular momentum in these objects. We then focus on the impact of atomic diffusion, large scale mixing due to rotation, and internal gravity waves on stellar properties on the main sequence and slightly beyond.
30 Doradus: The Low-Mass Stars
Zinnecker, H.; Brandl, B.; Brandner, W.; Moneti, A.; Hunter, D.
We have obtained HST/NICMOS H-band images of the central 1'x1' field around the R136 starburst cluster in the 30 Doradus HII region, in an attempt to reveal the presence (or absence) of a low-mass stellar population (M VIH 3-colour image of the central 30" x 30" area. The result clearly shows unexpected patches of extinction, with one patch only about 5" from the cluster core.
Semileptonic decays of the Bc meson
Barik, N.; Naimuddin, Sk.; Dash, P. C.; Kar, Susmita
2009-10-01
We study the semileptonic transitions Bc→ηc,J/Ψ,D,D*,B,B*,Bs,Bs* in the leading order in the framework of a relativistic independent quark model based on a confining potential in the equally mixed scalar-vector harmonic form. We compute relevant weak form factors as overlap integrals of the meson-wave functions obtained in the relativistic independent quark model in the whole accessible kinematical range. We predict that the semileptonic transitions of the Bc meson are mostly dominated by two Cabibbo-Kobayashi-Maskawa (CKM)-favored modes, Bc→Bs(Bs⋆)eν, contributing about 77% of the total decay width, and its decays to vector meson final states take place in the predominantly transverse mode. Our predicted values for the total decay rates, branching ratios, polarization ratios, the forward-backward asymmetry factor, etc., are broadly in agreement with other model predictions.
Stabilization of the linear SU(2) Nambu-Jona-Lasinio soliton via vector mesons
Energy Technology Data Exchange (ETDEWEB)
Arriola, E.R. (Bochum Univ. (Germany). Inst. fuer Theoretische Physik 2 Granada Univ. (Spain). Dept. de Fisica Moderna); Doering, F.; Schueren, C.; Goeke, K. (Bochum Univ. (Germany). Inst. fuer Theoretische Physik 2)
1994-03-01
The solitonic sector of the SU(2) NJL model with [sigma], [pi] [rho] A[sub 1] and [omega] mesons is investigated. the scalar and pseudo-scalar meson fields are not constrained to the chiral circle condition, i.e. [sigma][sup 2](r) + ''pi''[sup 2](r) ''no='' f[sub [pi
Decay constants of P and D-wave heavy-light mesons
Veseli, S
1996-01-01
We investigate decay constants of P and D-wave heavy-light mesons within the mock-meson approach. Numerical estimates are obtained using the relativistic quark model. We also comment on recent calculations of heavy-light pseudo-scalar and vector decay constants.
Quark Model Estimates of the Structure of the Meson-N-N*(1535,1/2-) Transition Vertices
Dillig, M; Marranghello, G F; Luetz, E F; Vasconcellos, C A Z
2006-01-01
We address an actual problem of baryon-resonance dominated meson-exchange processes in the low GeV regime, i.e. the phase and the structure of meson-NN* transition vertices. Our starting point is a quark-diquark model for the baryons (obeying approximate covariance; the mesons are kept as elementary objects), together with the relative phases for the NN vertices, as determined from low energy NN scattering. From the explicit representation of the N and N* baryons, we exemplify the derivation of the coupling constants and form factors of the NN*(1535,1/2-)transition vertices for pseudo-scalar, scalar and vector mesons.
Scalar-Pseudoscalar scattering and pseudoscalar resonances
Albaladejo, M
2010-01-01
The interactions between the f_0(980) and a_0(980) scalar resonances and the lightest pseudoscalar mesons are studied. We first obtain the interacting kernels, without including any ad hoc free parameter, because the lightest scalar resonances are dynamically generated. These kernels are unitarized, giving the final amplitudes, which generate pseudoscalar resonances, associated with the K(1460), \\pi(1300), \\pi(1800), \\eta(1475) and X(1835). We also consider the exotic channels with I=3/2 and I^G=1^+ quantum numbers. The former could be also resonant in agreement with a previous prediction.
Energy Technology Data Exchange (ETDEWEB)
Assiro, R. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Cappelli, L. [Università di Cassino e del Lazio Meridionale (Italy); Cascella, M. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento Matematica e Fisica, Università del Salento (Italy); De Lorenzis, L. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Grancagnolo, F. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Ignatov, F. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); L' Erario, A.; Maffezzoli, A. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Miccoli, A. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Onorato, G. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Università G. Marconi, Roma (Italy); Perillo, M. [EnginSoft S.p.a., Trento (Italy); Piacentino, G. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Fermilab, Batavia, IL (United States); Università G. Marconi, Roma (Italy); Rella, S. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Dipartimento di Ingegneria dell' Innovazione, Università del Salento (Italy); Rossetti, F. [EnginSoft S.p.a., Trento (Italy); Spedicato, M. [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Tassielli, G., E-mail: giovanni.tassielli@le.infn.it [Istituto Nazionale di Fisica Nucleare, Lecce (Italy); Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Università G. Marconi, Roma (Italy); and others
2013-08-01
We present a novel low mass drift chamber concept, developed in order to fulfill the stringent requirements imposed by the experiments for extremely rare processes, which require high resolutions (order of 100–200 keV/c) for particle momenta in a range (50–100 MeV/c) totally dominated by the multiple scattering contribution. We describe a geometry optimization procedure and a new wiring strategy with a feed-through-less wire anchoring system developed and tested on a drift chamber prototype under completion at INFN-Lecce.
The Frequency of Low-mass Exoplanets
O'Toole, S J; Tinney, C G; Butler, R P; Marcy, G W; Carter, B; Bailey, J; Wittenmyer, R A
2009-01-01
We report first results from the Anglo-Australian Telescope Rocky Planet Search - an intensive, high-precision Doppler planet search targeting low-mass exoplanets in contiguous 48 night observing blocks. On this run we targeted 24 bright, nearby and intrinsically stable Sun-like stars selected from the Anglo-Australian Planet Search's main sample. These observations have already detected one low-mass planet reported elsewhere (HD16417b), and here we reconfirm the detection of HD4308b. Further, we have Monte-Carlo simulated the data from this run on a star-by-star basis to produce robust detection constraints. These simulations demonstrate clear differences in the exoplanet detectability functions from star to star due to differences in sampling, data quality and intrinsic stellar stability. They reinforce the importance of star-by-star simulation when interpreting the data from Doppler planet searches. The simulations indicate that for some of our target stars we are sensitive to close-orbiting planets as sma...
Methanol emission from low mass protostars
Maret, S; Tielens, A G G M; Caux, E; Le Floc'h, B; Faure, A; Castets, A; Flower, D R
2005-01-01
We present observations of methanol lines in a sample of Class 0 low mass protostars. Using a 1-D radiative transfer model, we derive the abundances in the envelopes. In two sources of the sample, the observations can only be reproduced by the model if the methanol abundance is enhanced by about two order of magnitude in the inner hot region of the envelope. Two other sources show similar jumps, although at a lower confidence level. The observations for the other three sources are well reproduced with a constant abundance, but the presence of a jump cannot be ruled out. The observed methanol abundances in the warm gas around low mass protostars are orders of magnitude higher than gas phase chemistry models predict. Hence, in agreement with other evidences, this suggest that the high methanol abundance reflects recent evaporation of ices due to the heating by the newly formed star. The observed abundance ratios of CH3 OH, H2 CO, and CO are in good agreement with grain surface chemistry models. However, the abs...
Asymmetric vector mesons produced in nuclear collisions
Energy Technology Data Exchange (ETDEWEB)
Dremin, I.M.; Nechitailo, V.A. [Lebedev Physical Institute, Moscow (Russian Federation); National Research Nuclear University ' ' MEPhI' ' , Moscow (Russian Federation)
2016-09-15
It is argued that the experimentally observed phenomenon of asymmetric shapes of vector mesons produced in nuclear media during high-energy nucleus-nucleus collisions can be explained as Fano-Feshbach resonances. It has been observed that the mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape with some excess in the low-mass wing of the resonance. It is clear that the whole phenomenon is related to some interaction with the nuclear medium. Moreover, it can be further described in quantum mechanics as the interference of direct and continuum states in the Fano-Feshbach effect. To reveal the nature of the interaction it is proposed to use a phenomenological model of the additional contribution due to Cherenkov gluons. They can be created because of the excess of the refractivity index over 1 just in the low-mass wing as required by the classical Cherenkov treatment. In quantum mechanics, this requirement is related to the positive real part of the interaction amplitude in this wing. The corresponding parameters are found from the comparison with ρ-meson data and admit reasonable explanation. (orig.)
Asymmetric vector mesons produced in nuclear collisions
Dremin, I. M.; Nechitailo, V. A.
2016-09-01
It is argued that the experimentally observed phenomenon of asymmetric shapes of vector mesons produced in nuclear media during high-energy nucleus-nucleus collisions can be explained as Fano-Feshbach resonances. It has been observed that the mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape with some excess in the low-mass wing of the resonance. It is clear that the whole phenomenon is related to some interaction with the nuclear medium. Moreover, it can be further described in quantum mechanics as the interference of direct and continuum states in the Fano-Feshbach effect. To reveal the nature of the interaction it is proposed to use a phenomenological model of the additional contribution due to Cherenkov gluons. They can be created because of the excess of the refractivity index over 1 just in the low-mass wing as required by the classical Cherenkov treatment. In quantum mechanics, this requirement is related to the positive real part of the interaction amplitude in this wing. The corresponding parameters are found from the comparison with ρ-meson data and admit reasonable explanation.
Boosting low-mass hadronic resonances
Shimmin, Chase; Whiteson, Daniel
2016-09-01
Searches for new hadronic resonances typically focus on high-mass spectra due to overwhelming QCD backgrounds and detector trigger rates. We present a study of searches for relatively low-mass hadronic resonances at the LHC in the case that the resonance is boosted by recoiling against a well-measured high-pT probe such as a muon, photon or jet. The hadronic decay of the resonance is then reconstructed either as a single large-radius jet or as a resolved pair of standard narrow-radius jets, balanced in transverse momentum to the probe. We show that the existing 2015 LHC data set of p p collisions with ∫L d t =4 fb-1 should already have powerful sensitivity to a generic Z' model which couples only to quarks, for Z' masses ranging from 20 - 500 GeV /c2 .
Magnetometer Searches for Ultra Low Mass Fields
Romalis, Michael
2017-01-01
New spin interactions arise in a variety of extensions to the Standard Model. Well-known spin-dependent effects, such as permanent electric dipole moments and violations of Lorentz and CPT symmetries, have been searched for in many experiments. The existence of low-mass axion-like particles would also generate spin-dependent effects that can be searched for in similar experiments, but often with unique signatures. Since particles with spin also have a magnetic moment, such experiments are automatically sensitive to ordinary magnetic fields and one of the challenges is to eliminate such effects, using for example, two different spin species in a co-magnetometer arrangement. I will describe several past and on-going experiments using co-magnetometers based on nuclear spin-polarized noble gases. These experiments are used to search for both axion-like dark matter and for axion-mediated forces that are independent of dark matter.
Olivier Chesneau's work on low mass stars
Eric, Lagadec
2015-01-01
During his too short career, Olivier Chesneau pioneered the study of the circumstellar environments of low mass evolved stars using very high angular resolution techniques. He applied state of the art high angular resolution techniques, such as optical interferometry and adaptive optics imaging, to the the study of a variety of objects, from AGB stars to Planetary Nebulae, via e.g. Born Again stars, RCB stars and Novae. I present here an overview of this work and most important results by focusing on the paths he followed and key encounters he made to reach these results. Olivier liked to work in teams and was very strong at linking people with complementary expertises to whom he would communicate his enthusiasm and sharp ideas. His legacy will live on through the many people he inspired.
Mass Function of Low Mass Dark Halos
Yahagi, H; Yoshii, Y; Yahagi, Hideki; Nagashima, Masahiro; Yoshii, Yuzuru
2004-01-01
The mass function of dark halos in a Lambda-dominated cold dark matter (LambdaCDM) universe is investigated. 529 output files from five runs of N-body simulations are analyzed using the friends-of-friends cluster finding algorithm. All the runs use 512^3 particles in the box size of 35 h^{-1}Mpc to 140 h^{-1}Mpc. Mass of particles for 35 h^{-1} Mpc runs is 2.67 times 10^7 h^{-1} M_{solar}. Because of the high mass resolution of our simulations, the multiplicity function in the low-mass range, where the mass is well below the characteristic mass and $\
CFFF low mass flow DCW generator operation
Lineberry, J. T.; Galanga, F. L.; Frazier, J. W.
1986-01-01
A summary of testing of the low mass flow diagonal conducting sidewall MHD generator in the CFFF is given. These summaries include details of the powered generator tests conducted during the 1985 LMF4 test series. A presentation of experimental generator electrical data collected during these tests is included. The quality of these data is discussed and a review of representative data presentations is made as a means of identifying phenomena associated with coal-fired MHD generators. Unique characteristics of coal slag effects upon electrical performance are seen in the voltage profiles and power characteristics for the generator. Fundamental theoretical analyses of the generator are used to qualify the levels of generator performance that were demonstrated during testing. These analyses are directed at isolating possible sources that have caused performance deficiencies and anomalies seen in the test data.
Boosting low-mass hadronic resonances
Shimmin, Chase
2016-01-01
Searches for new hadronic resonances typically focus on high-mass spectra, due to overwhelming QCD backgrounds and detector trigger rates. We present a study of searches for relatively low-mass hadronic resonances at the LHC in the case that the resonance is boosted by recoiling against a well-measured high-$p_{\\textrm{T}}$ probe such as a muon, photon or jet. The hadronic decay of the resonance is then reconstructed either as a single large-radius jet or as a resolved pair of standard narrow-radius jets, balanced in transverse momentum to the probe. We show that the existing 2015 LHC dataset of $pp$ collisions with $\\int\\mathcal{L}dt = 4\\ \\mathrm{fb}^{-1}$ should already have powerful sensitivity to a generic $Z'$ model which couples only to quarks, for $Z'$ masses ranging from 20-500 GeV/c$^2$.
Fundamental properties of low-mass stars
Ribas, I; Jordi, C; Baraffe, I; Chabrier, G; Gallardo, J
2007-01-01
Numerous investigations on the fundamental properties of low-mass stars using eclipsing binaries indicate a strong discrepancy between theory and observations that is still awaiting explanation. Current models seem to predict radii for stars less massive than the Sun that are some 10% smaller than observed, while their effective temperatures are some 5% larger. Here we discuss recent new observational data that are relevant to this issue and review the progress made in understanding the origin of the important differences with theoretical calculations. Notably, we provide evidence that stellar activity may be responsible for the mismatch between observations and theory through two different channels: inhibition of convection or effects of a significant starspot coverage. The activity hypothesis is put to a test with observational diagnostics and some of the consequences of the large starspot coverage are evaluated. We conclude that stellar activity likely plays a key role in defining the properties of active ...
Nonchiral enhancement of scalar glueball decay in the Witten-Sakai-Sugimoto model
Brünner, Frederic
2015-01-01
We estimate the consequences of finite masses of pseudoscalar mesons on the decay rates of scalar glueballs in the Witten-Sakai-Sugimoto model, a top-down holographic model of low-energy QCD, by extrapolating from the calculable vertex of glueball fields and the eta' meson which follows from the Witten-Veneziano mechanism for giving mass to the latter. Evaluating the effect on the recently calculated decay rates of glueballs in the Witten-Sakai-Sugimoto model, we find a strong enhancement of the decay of scalar glueballs into kaons and eta mesons, in fairly close agreement with experimental data on the glueball candidate f0(1710).
Single meson contributions to the muon's anomalous magnetic moment
Energy Technology Data Exchange (ETDEWEB)
Pauk, Vladyslav [Johannes Gutenberg-Universitaet, Institut fuer Kernphysik, Mainz (Germany); Johannes Gutenberg-Universitaet, PRISMA Cluster of Excellence, Mainz (Germany); Taras Shevchenko National University of Kyiv, Department of Physics, Kyiv (Ukraine); Vanderhaeghen, Marc [Johannes Gutenberg-Universitaet, Institut fuer Kernphysik, Mainz (Germany); Johannes Gutenberg-Universitaet, PRISMA Cluster of Excellence, Mainz (Germany)
2014-08-15
We develop the formalism to provide an improved estimate for the hadronic light-by-light correction to the muon's anomalous magnetic moment a{sub μ}, by considering single meson contributions beyond the leading pseudoscalar mesons. We incorporate available experimental input as well as constraints from light-by-light scattering sum rules to estimate the effects of axial-vector, scalar, and tensor mesons. We give numerical evaluations for the hadronic light-by-light contribution of these states to a{sub μ}. The presented formalism allows one to further improve on these estimates, once new data for such meson states will become available. (orig.)
A Light-Cone QCD Inspired Meson Model with a Relativistic Confining Potential in Momentum Space
Institute of Scientific and Technical Information of China (English)
LI Lei; WANG Shun-Jin; ZHOU Shan-Gui; ZHANG Guang-Biao
2007-01-01
For describing the radial excited states a relativistic confining potential in momentum space is included in the meson effective light-cone Hamiltonian. The meson eigen equations are transformed from the front form to the instant form and formulated in total angular representation. Details about numerically solving these equations are discussed, mainly focusing on treating singularities arising from one-gluon exchange interactions and confinement. The results of pseudo-scalar mesons indicate that the improved meson effective light-cone Hamiltonian can describe the ground states and radial excited states well. Some radial excited states are also predicted and waiting for experimental test.
Effect of the extra dimensions on the meson spectra in the perturbed background
Naji, J.; Heshmatian, S.
2017-05-01
A class of the d-dimensional black holes space-time with the perturbed geometric function and dilaton field is considered to study meson spectroscopy. Holographic description of the black holes are used to investigate the meson spectra and the effective potential of mesons which described by a massless scalar field in the d-dimensional black holes with a dilaton background. The effects of perturbations and extra dimensions on the meson spectra and effective potential are investigated by using some experimental data and simulation of spectra ratios.
Central production of two-pseudoscalar meson systems at the COMPASS experiment at CERN
Energy Technology Data Exchange (ETDEWEB)
Austregesilo, Alexander
2014-10-20
COMPASS is a fixed-target experiment at the CERN SPS which recorded a data set with an incident proton beam impinging on a liquid hydrogen target in order to study the central production of light scalar mesons. We select events with two protons and two pseudo-scalar mesons in the final state and decompose their angular distribution in terms of partial-wave amplitudes. Fits to the mass-dependence of these amplitudes are used to determine the Breit-Wigner parameters of scalar resonances.
Nuclear Matter with Quark-Meson Coupling; 1, Comparison of Nontopological Soliton Models
Barnea, N; Barnea, Nir; Walhout, Timothy S.
1999-01-01
A system of nontopological solitons interacting through scalar and vector meson exchange is used to model nuclear matter. The models studied are of the Friedberg-Lee type, which exhibit dynamical bag formation due to the coupling of quarks to a scalar composite gluon field. It is shown that the chiral chromodielectric model gives the best fit to the empirical data. The presence of the scalar meson guarantees saturation and an increase of the proton charge radius with nuclear density consistent with the EMC effect.
Decay constants and spectroscopy of mesons in lattice QCD using domain-wall fermions
Fahy, B; Hashimoto, S; Kaneko, T; Noaki, J; Tomii, M
2015-01-01
We report results of masses and decay constants of light and charmed pseudo-scalar mesons using lattice QCD with M\\"obius domain-wall fermions. Using this formulation we are able to compute pseudo-scalar decay constants through the pseudo-scalar density operator as well as with the axial-vector current. Results are shown from several lattice spacings and pion masses between 230 MeV and 500 MeV. We present an analysis of these results at different quark masses to show the chiral properties of the light mesons masses and decay constants.
Low Mass Dimuon Production in p-A Collisions at 400 GeV/c with the NA60 Detector
Uras, Antonio; De Falco, Alessandro
2011-01-01
The NA60 experiment has studied low-mass muon pair production in proton-nucleus collisions with a system of Be, Cu, In, W, Pb and U targets using a 400 GeV/c proton beam at the CERN SPS. The mass spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons eta, rho, omega, eta' and phi. A new measurement of the electromagnetic transition form factors of the eta and omega was performed. The values found agree with the previous available measurements, improving their uncertainty thanks to the higher statistics, and confirm the discrepancy with the prediction of the Vector Meson Dominance (VMD) model in the case of the electromagnetic form factor of the omega meson; for this latter, the comparison of the data to an improved calculation including also a direct point-like term is discussed. The pT spectra for the omega and phi mesons are studied in the full pT range accessible, up to pT = 2 GeV/c. The pT spectrum of the eta meson is also considered, starting from pT...
The Effect of Vector Meson Decays on Dihadron Fragmentation Functions
Matevosyan, Hrayr H; Bentz, Wolfgang
2014-01-01
Dihadron Fragmentation Functions (DFF) provide a vast amount of information on the intricate details of the parton hadronization process. Moreover, they provide a unique access to the "clean" extraction of nucleon transversity parton distribution functions in semi inclusive deep inelastic two hadron production process with a transversely polarised target. On the example of the u \\to \\pi^+ \\pi^-, we analyse the properties of unpolarised DFFs using their probabilistic interpretation. We use both the NJL-jet hadronization model and PYTHIA 8.1 event generator to explore the effect of the strong decays of the vector mesons produced in the quark hadronization process on the pseudoscalar DFFs. Our study shows that, even though it is less probable to produce vector mesons in the hadronization process than pseudo scalar mesons of the same charge, the products of their strong decays drastically affect the DFFs for pions because of the large combinatorial factors. Thus, an accurate description of both vector meson produ...
Accretion Disks around Young Low Mass Stars
Directory of Open Access Journals (Sweden)
Paola D´Alessio
2001-01-01
Full Text Available In the past decade, it has become clear that almost half of the low mass pre-main sequence stars are surrounded by disks, which are responsible for the observed infrared and optical-UV excess emission. The characterization of the structure of circumstellar disks is a crucial step towards understanding the early stellar evolution and planet formation. The thesis summarized here presents physical models of the detailed structure of accretion disks surrounding T Tauri stars. The disks are assumed to be in steady state, in vertical hydrostatic equilibrium, and with a turbulent viscosity described by the alpha-prescription. We consider different heating mechanisms: viscous dissipation, heating by cosmic rays and radioactive decay, irradiation by the central star or irradiation by an infalling envelope. The energy is transported in the vertical direction by radiation, convection and the turbulent flux. Give n the disk structure, we calculate its emission by integrating the radiative transfer equation for an arbitrary orientation of the disk relative to the line of sight. Spectral energy distributions (SEDs and images are compared with observations, and disk properties can be inferred or constrained.
Similarity flow of a neutral scalar coupled to a fixed source
Jones, Billy D
2013-01-01
A neutral scalar meson interacting with a fixed isoscalar nucleon is evolved according to the similarity renormalization group. The fixed source ends up being too singular and an appropriately dressed static source arises from the similarity flow. The fixed source is dressed by a virtual cloud of mesons extending out past the inverse meson mass according to the Yukawa potential. For low energies the source produces a Yukawa mean field which decouples from the remaining meson field fluctuations. The renormalization group procedure for effective particles is also illustrated for this fixed-source model.
Chen, Kan; Liu, Xiang; Matsuki, Takayuki
2015-01-01
Inspired by the abundant experimental observation of axial vector states, we study whether the observed axial vector states can be categorized into the conventional axial vector meson family. In this paper we carry out analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial vector mesons, which are valuable to further experimental exploration of the observed and predicted axial vector mesons.
QCD monopole and sigma meson coupling
Iwazaki, Aiichi
2016-01-01
Under the assumption of the Abelian dominance in QCD, we show that chiral condensate is locally present around a QCD monopole. The appearance of the chiral condensate around a GUT monopole was shown in the previous analysis of the Rubakov effect. We apply a similar analysis to the QCD monopole. It follows that the condensation of the monopole carrying the chiral condensate leads to the chiral symmetry breaking as well as quark confinement. To realize the result explicitly, we present a phenomenological linear sigma model coupled with the monopoles, in which the monopole condensation causes the chiral symmetry breaking as well as confinement. The monopoles are assumed to be described by a model of dual superconductor. We identify the monopoles with scalar isoscalar $f_0$ mesons with masses $1400\\sim 1700$ MeV as well as dual gauge fields with $h_1$ vector mesons with masses $\\sim 1500$MeV.
In-medium kaon and antikaon properties in the quark-meson coupling model
Tsushima, K; Thomas, A W; Wright, S V
1998-01-01
The properties of the kaon, $K$, and antikaon, $\\kbar$, in nuclear medium are studied in the quark-meson coupling (QMC) model. Employing a constituent quark-antiquark (MIT bag model) picture, their excitation energies in a nuclear medium at zero momentum are calculated within mean field approximation. The scalar, and the vector mesons are assumed to couple directly to the nonstrange quarks and antiquarks in the $K$ and $\\kbar$ mesons. It is demonstrated that the $\\rho$ meson induces different mean field potentials for each member of the isodoublets, $K$ and $\\kbar$, when they are embedded in asymmetric nuclear matter. Furthermore, it is also shown that this $\\rho$ meson potential is repulsive for the $K^-$ meson in matter with a neutron excess, and renders $K^-$ condensation less likely to occur.
Energy Technology Data Exchange (ETDEWEB)
Hilger, Thomas Uwe
2012-04-11
The interplay of hadron properties and their modification in an ambient nuclear medium on the one hand and spontaneous chiral symmetry breaking and its restoration on the other hand is investigated. QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D- anti D and B- anti B mesons as a function of the nuclear matter density and investigate the impact of various condensates in linear density approximation. The analysis also includes D{sub s} and D{sup *}{sub 0} mesons. QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector D mesons and derive the corresponding Weinberg type sum rules. Based on QCD sum rules we explore the consequences of a scenario for the ρ meson, where the chiral symmetry breaking condensates are set to zero whereas the chirally symmetric condensates remain at their vacuum values. The complementarity of mass shift and broadening is discussed. An alternative approach which utilizes coupled Dyson-Schwinger and Bethe-Salpeter equations for quark-antiquark bound states is investigated. For this purpose we analyze the analytic structure of the quark propagators in the complex plane numerically and test the possibility to widen the applicability of the method to the sector of heavy-light mesons in the scalar and pseudo-scalar channels, such as the D mesons, by varying the momentum partitioning parameter. The solutions of the Dyson-Schwinger equation in the Wigner-Weyl phase of chiral symmetry at nonzero bare quark masses are used to investigate a scenario with explicit but without dynamical chiral symmetry breaking.
Chiral Loops and Ghost States in the Quenched Scalar Propagator
Energy Technology Data Exchange (ETDEWEB)
W. Bardeen; A. Duncan; E. Eichten; N. Isgur; H. Thacker
2001-06-01
The scalar, isovector meson propagator is analyzed in quenched QCD, using the MQA pole-shifting ansatz to study the chiral limit. In addition to the expected short-range exponential falloff characteristic of a heavy scalar meson, the propagator also exhibits a longer-range, negative metric contribution which becomes pronounced for smaller quark masses. We show that this is a quenched chiral loop effect associated with the anomalous structure of the eta' propagator in quenched QCD. Both the time dependence and the quark mass dependence of this effect are well-described by a chiral loop diagram corresponding to an eta'-pi intermediate state, which is light and effectively of negative norm in the quenched approximation. The relevant parameters of the effective Lagrangian describing the scalar sector of the quenched theory are determined.
Lasukov, V. V.
2012-06-01
It is shown that negative Scalars can claim to be the object referred to as black holes, therefore observation of black holes means observation of Scalars. In contrast to blackholes, negative Scalars contain no singularity inside. Negative Scalars can be observed from the effect of generation of ordinary matter by the Lemaître primordial atom.
Ishii, Masahiro; Yahiro, Masanobu
2016-01-01
We propose a practical effective model by introducing temperature ($T$) dependence to the coupling strengths of four-quark and six-quark Kobayashi-Maskawa-'t Hooft interactions in the 2+1 flavor Polyakov-loop extended Nambu-Jona-Lasinio model. The $T$ dependence is determined from LQCD data on the renormalized chiral condensate around the pseudocritical temperature $T_c^{\\chi}$ of chiral crossover and the screening-mass difference between $\\pi$ and $a_0$ mesons in $T > 1.1T_c^\\chi$ where only the $U(1)_{\\rm A}$-symmetry breaking survives. The model well reproduces LQCD data on screening masses $M_{\\xi}^{\\rm scr}(T)$ for both scalar and pseudoscalar mesons, particularly in $T \\ge T_c^{\\chi}$. Using this effective model, we predict meson pole masses $M_{\\xi}^{\\rm pole}(T)$ for scalar and pseudoscalar mesons. For $\\eta'$ meson, the prediction is consistent with the experimental value at finite $T$ measured in heavy-ion collisions. We point out that the relation $M_{\\xi}^{\\rm scr}(T)-M_{\\xi}^{\\rm pole}(T) \\approx...
Heavy-light mesons in a relativistic model
Liu, Jing-Bin; Yang, Mao-Zhi
2016-07-01
We study the heavy-light mesons in a relativistic model, which is derived from the Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation to the heavy quark. The kernel we choose is based on scalar confinement and vector Coulomb potentials. The transverse interaction of the gluon exchange is also taken into account in this model. The spectra and wave functions of D, Ds, B, Bs meson states are obtained. The spectra are calculated up to the order of 1/m Q, and wave functions are treated to leading order. Supported by National Natural Science Foundation of China (11375088, 10975077, 10735080, 11125525)
Asymmetric vector mesons produced in nuclear collisions
Dremin, I M
2016-01-01
It is argued that the experimentally observed phenomenon of asymmetric shapes of vector mesons produced in nuclear media during high energy nucleus-nucleus collisions can be explained as Fano-Feshbach resonances. It has been observed that the mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape with some excess in the low-mass wing of the resonance. It is clear that the whole phenomenon is related to some interaction with the nuclear medium. Moreover, it can be further detalized in quantum mechanics as the interference of direct and continuum states in Fano-Feshbach effect. To reveal the nature of the interaction it is proposed to use a phenomenological model of the additional contribution due to Cherenkov gluons. They can be created because of the excess of the refractivity index over 1 just in the low-mass wing as required by the classical Cherenkov treatment. In quantum mechanics, this requirement is related to the positive real part of the interaction ...
Charm meson scattering cross sections by pion and rho meson
Lin Zi Wei; Ko, C M
2001-01-01
Using the local flavor SU(4) gauge invariance in the limit of vanishing vector-meson masses, we extend our previous study of charm-meson scattering cross sections by pion and rho meson, which is based only on the pseudoscalar-pseudoscalar-vector meson couplings, to include also contributions from the couplings among three vector mesons and among four particles. We find that diagrams with light-meson exchanges usually dominate the cross sections. For the processes considered previously, the additional interactions lead only to diagrams involving charm-meson exchanges and contact interactions, and the cross sections for these processes are thus not much affected. Nevertheless, these additional interactions introduce new processes with light-meson exchanges and increase significantly the total scattering cross sections of charm mesons by pion and rho meson.
Astrophysical Constraints on Singlet Scalars at LHC
Hertzberg, Mark P
2016-01-01
We consider the viability of new heavy gauge singlet scalar particles at the LHC. Our motivation for this study comes from the possibility of a new particle with mass ~ 750 GeV decaying significantly into two photons at LHC, but our analysis applies more broadly. We show that there are significant constraints from astrophysics and cosmology on the simplest UV complete models that incorporate such a particle and its associated collider signal. The simplest and most obvious UV complete model that incorporates the signal is that it arises from a new singlet scalar (or pseudo-scalar) coupled to a new electrically charged and colored heavy fermion. Here we show that these new fermions (and anti-fermions) would be produced in the early universe, then form new color singlet heavy mesons with light quarks, obtain a non-negligible freeze-out abundance, and remain in kinetic equilibrium until decoupling. These heavy mesons possess interesting phenomenology, dependent on their charge, including forming new bound states ...
Vector-meson dominance revisited
Directory of Open Access Journals (Sweden)
Terschlüsen Carla
2012-12-01
Full Text Available The interaction of mesons with electromagnetism is often well described by the concept of vector-meson dominance (VMD. However, there are also examples where VMD fails. A simple chiral Lagrangian for pions, rho and omega mesons is presented which can account for the respective agreement and disagreement between VMD and phenomenology in the sector of light mesons.
Cherenkov and Fano effects at the origin of asymmetric vector mesons in nuclear media
Dremin, I M
2015-01-01
It is argued that the experimentally observed phenomenon of asymmetric vector mesons produced in nuclear media during high energy nucleus-nucleus collisions can be explained as Cherenkov and Fano effects. The mass distributions of lepton pairs created at meson decays decline from the traditional Breit-Wigner shape in the low-mass wing of the resonance. That is explained by the positive real part of the amplitude in this wing for classic Cherenkov treatment and further detalized in quantum mechanics as the interference of direct and continuum states in Fano effect. The corresponding parameters are found from the comparison with rho-meson data and admit reasonable explanation.
Strong Two--Body Decays of Light Mesons
Ricken, R; Merten, D; Metsch, B C; Ricken, Ralf; Koll, Matthias; Merten, Dirk; Metsch, Bernard C.
2003-01-01
In this paper, we present results on strong two-body decay widths of light $q\\bar q$ mesons calculated in a covariant quark model. The model is based on the Bethe-Salpeter equation in its instantaneous approximation and has already been used for computing the complete meson mass spectrum and many electroweak decay observables. Our approach relies on the use of a phenomenological confinement potential with an appropriate spinorial Dirac structure and 't Hooft's instanton--induced interaction as a residual force for pseudoscalar and scalar mesons. The transition matrix element for the decay of one initial meson into two final mesons is evaluated in lowest order by considering conventional decays via quark loops as well as Zweig rule violating instanton--induced decays generated by the six--quark vertex of 't Hooft's interaction; the latter mechanism only contributes if all mesons in the decay have zero total angular momentum. We show that the interference of both decay mechanisms plays an important role in the ...
Existence of the critical endpoint in the vector meson extended linear sigma model
Kovács, Peter; Wolf, György
2016-01-01
The chiral phase transition of the strongly interacting matter is investigated at nonzero temperature and baryon chemical potential mu_B within an extended (2+1) flavor Polyakov constituent quark-meson model which incorporates the effect of the vector and axial vector mesons. The effect of the fermionic vacuum and thermal fluctuations computed from the grand potential of the model is taken into account in the curvature masses of the scalar and pseudoscalar mesons. The parameters of the model are determined by comparing masses and tree-level decay widths with experimental values in a chi^2-minimization procedure which selects between various possible assignments of scalar nonet states to physical particles. We examine the restoration of the chiral symmetry by monitoring the temperature evolution of condensates and the chiral partners' masses and of the mixing angles for the pseudoscalar eta-eta' and the corresponding scalar complex. We calculate the pressure and various thermodynamical observables derived from...
Transversity and Meson Photoproduction
Goldstein, G R; Goldstein, Gary R.; Gamberg, Leonard
2002-01-01
Both meson photoproduction and semi-inclusive deep inelastic scattering can potentially probe transversity in the nucleon. We explore how that potential can be realized dynamically. The role of rescattering in both exclusive and inclusive meson production as a source for transverse polarization asymmetry is examined. We use a dynamical model to calculate the asymmetry and relate that to the transversity distribution of the nucleon.
Indian Academy of Sciences (India)
Ajay Kumar Rai; P C Vinodkumar
2006-05-01
The mass spectrum of $c\\bar{b}$ meson is investigated with an effective quark-antiquark potential of the form $\\dfrac{-_{c}}{r} + Ar^{}$ with varying from 0.5 to 2.0. The and -wave masses, pseudoscalar decay constant, weak decay partial widths in spectator model and the lifetime of c meson are computed. The properties calculated here are found to be in good agreement with other theoretical and experimental values at potential index, = 1.
Exclusive semileptonic decays of charmed and b-flavored mesons
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Tripathy, S.K. [Physics Department, Utkal University, Bhubaneswar-751004 (India); Kar, S.; Dash, P.C. [Physics Department, Prananath College, Khurda-752057 (India)
1997-10-01
We investigate the exclusive semileptonic decays of (B,B{sub s};D,D{sub s}) mesons into less heavy as well as light mesons in a field-theoretic framework based on the independent quark model with a confining potential in scalar-vector-harmonic form. With the recoil effect properly taken into account, the present model describes consistently the semileptonic decays of charmed and b-flavored mesons, agreeing well with the experimental data. The transition form factors in the heavy to heavy decays, in particular, comply with the heavy quark symmetry relations expected from HQET. The CKM parameters extracted in this formalism are close to the existing data. The model prediction also satisfies the Isgur-Wise relation connecting the form factors of the semileptonic (B{r_arrow}{rho}e{nu}) and that of rare radiative decay (B{r_arrow}{rho}{gamma}). {copyright} {ital 1997} {ital The American Physical Society}
Scalar Field (Wave) Dark Matter
Matos, T
2016-01-01
Recent high-quality observations of dwarf and low surface brightness (LSB) galaxies have shown that their dark matter (DM) halos prefer flat central density profiles. On the other hand the standard cold dark matter model simulations predict a more cuspy behavior. Feedback from star formation has been widely used to reconcile simulations with observations, this might be successful in field dwarf galaxies but its success in low mass galaxies remains uncertain. One model that have received much attention is the scalar field dark matter model. Here the dark matter is a self-interacting ultra light scalar field that forms a cosmological Bose-Einstein condensate, a mass of $10^{-22}$eV/c$^2$ is consistent with flat density profiles in the centers of dwarf spheroidal galaxies, reduces the abundance of small halos, might account for the rotation curves even to large radii in spiral galaxies and has an early galaxy formation. The next generation of telescopes will provide better constraints to the model that will help...
Quenched Charmed Meson Spectra Using Tadpole Improved Quark Action on Anisotropic Lattices
Institute of Scientific and Technical Information of China (English)
LIU Liu-Ming; SU Shi-Quan; LI Xin; LIU Chuan
2005-01-01
@@ Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for four lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with three different values of gauge coupling β and four different values of bare speed of light v. With the bare speed of light parameter v tuned in a mass-dependent way, we study the mass spectra of D, Ds, ηc, D*, Ds* and J/ψ mesons. The results extrapolated to the continuum limit are compared with the experiment, and a qualitative agreement is found.
Generalized SU(3) Nambu-Jona-Lasinio model. Pt. 1; Mesonic modes
Energy Technology Data Exchange (ETDEWEB)
Klimt, S.; Lutz, M.; Vogl, U.; Weise, W. (Regensburg Univ. (Germany, F.R.). Inst. fuer Physik 1 - Theoretische Physik)
1990-10-08
We present calculations of mesonic (quark-antiquark) modes in a generalized Nambu-Jona-Lasinio model with three quark flavours. The effective interaction between quarks is symmetric under chiral SU(3){sub L}xSU(3){sub R} and incorporates a U(1){sub A}-breaking six-point interaction as suggested by 't Hooft. We coencentrate on the evaluation of masses and decay constants of pseudoscalar mesons, with special emphasis on the underlying symmetry breaking patterns. Scalar, vector and axial vector mesonic modes are also discussed. (orig.).
Meson correlators in QCD vacuum is saturation the right approach?
Sheel, V; Parikh, J C; Sheel, Varun; Mishra, Hiranmaya; Parikh, Jitendra C
1994-01-01
Equal time, point to point correlation functions for spatially separated meson currents are calculated with respect to a variational construct for the ground state of QCD. With exact calculations, vector, axial vector and scalar channels show qualitative agreement with the phenomenological predictions, where as pseudoscalar channel does not. However, the pseudoscalar correlator, when approximated by saturating with intermediate one pion states agrees with results obtained from spectral density functions parametrised by pion decay constant and value obtained from chiral perturbation theory.
Strong couplings and form factors of charmed mesons in holographic QCD
Ballon-Bayona, Alfonso; Krein, Gastão; Miller, Carlisson
2017-07-01
We extend the two-flavor hard-wall holographic model of Erlich, Katz, Son, and Stephanov [Phys. Rev. Lett. 95, 261602 (2005), 10.1103/PhysRevLett.95.261602] to four flavors to incorporate strange and charm quarks. The model incorporates chiral and flavor symmetry breaking and provides a reasonable description of masses and weak decay constants of a variety of scalar, pseudoscalar, vector, and axial-vector strange and charmed mesons. In particular, we examine flavor symmetry breaking in the strong couplings of the ρ meson to the charmed D and D* mesons. We also compute electromagnetic form factors of the π , ρ , K , K*, D and D* mesons. We compare our results for the D and D* mesons with lattice QCD data and other nonperturbative approaches.
Astrophysical constraints on singlet scalars at LHC
Hertzberg, Mark P.; Masoumi, Ali
2017-04-01
We consider the viability of new heavy gauge singlet scalar particles at colliders such as the LHC . Our original motivation for this study came from the possibility of a new heavy particle of mass ~ TeV decaying significantly into two photons at colliders, such as LHC, but our analysis applies more broadly. We show that there are significant constraints from astrophysics and cosmology on the simplest UV complete models that incorporate such new particles and its associated collider signal. The simplest and most obvious UV complete model that incorporates such signals is that it arises from a new singlet scalar (or pseudo-scalar) coupled to a new electrically charged and colored heavy fermion. Here we show that these new fermions (and anti-fermions) would be produced in the early universe, then form new color singlet heavy mesons with light quarks, obtain a non-negligible freeze-out abundance, and remain in kinetic equilibrium until decoupling. These heavy mesons possess interesting phenomenology, dependent on their charge, including forming new bound states with electrons and protons. We show that a significant number of these heavy states would survive for the age of the universe and an appreciable number would eventually be contained within the earth and solar system. We show that this leads to detectable consequences, including the production of highly energetic events from annihilations on earth, new spectral lines, and, spectacularly, the destabilization of stars. The lack of detection of these consequences rules out such simple UV completions, putting pressure on the viability of such new particles at LHC . To incorporate such a scalar would require either much more complicated UV completions or even further new physics that provides a decay channel for the associated fermion.
Photoproduction of the Scalar Meson $f_0(500)$
Lee, Je-Hee; Yu, Byung-Geel; Kim, Hyun-Chul
2015-01-01
In the present talk, we report a recent investigation on photoproduction of the $\\gamma N \\to f_0(500)N$ within a framework of the effective Lagrangian. We include the nucleon resonances with pin $1/2$ in the $s$ channel. The coupling constants have been etermined by assuming that the decay process $N^* \\to (\\pi\\pi)_{I=0,J=0}N$ can be regarded as $N^* \\to f_0(500) N$. We discuss the numerical results for the total cross sections and possible extension of the present work.
The formation of low-mass stars and brown dwarfs
Stamatellos, Dimitris
2013-01-01
It is estimated that ~60% of all stars (including brown dwarfs) have masses below 0.2Msun. Currently, there is no consensus on how these objects form. I will briefly review the four main theories for the formation of low-mass objects: turbulent fragmentation, ejection of protostellar embryos, disc fragmentation, and photo-erosion of prestellar cores. I will focus on the disc fragmentation theory and discuss how it addresses critical observational constraints, i.e. the low-mass initial mass function, the brown dwarf desert, and the binary statistics of low-mass stars and brown dwarfs. I will examine whether observations may be used to distinguish between different formation mechanisms, and give a few examples of systems that strongly favour a specific formation scenario. Finally, I will argue that it is likely that all mechanisms may play a role in low-mass star and brown dwarf formation.
Low-Mass Planar Photonic Imaging Sensor Project
National Aeronautics and Space Administration — We propose a revolutionary electro-optical (EO) imaging sensor concept that provides a low-mass, low-volume alternative to the traditional bulky optical telescope...
Kleihaus, Burkhard; Yazadjiev, Stoytcho
2015-01-01
In the presence of a complex scalar field scalar-tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and ordinary hairy black holes. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
Star Formation Modes in Low-Mass Disk Galaxies
Gallagher, J S
2001-01-01
Low-mass disk galaxies with well-organized structures are relatively common in low density regions of the nearby Universe. They display a wide range in levels of star formation activity, extending from sluggishly evolving `superthin' disk systems to nearby starbursts. Investigations of this class of galaxy therefore provides opportunities to test and define models of galactic star formation processes. In this paper we briefly explore characteristics of examples of quiescent and starbursting low-mass disk galaxies.
Tolos, Laura; Gamermann, Daniel; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; LlanesEstrada, FJ; Pelaez,
2011-01-01
Charmed mesons in dense matter are studied within a unitary coupled-channel approach which takes into account Pauli-blocking effects and meson self-energies in a self-consistent manner. We obtain the open-charm meson spectral functions in this dense medium, and discuss their implications on hidden c
Effects of staggered fermions and mixed actions on the scalar correlator
Prelovsek, S
2006-01-01
We provide the analytic predictions for the flavor non-singlet scalar correlator, which will enable determination of the scalar meson mass from the lattice scalar correlator. We consider simulations with 2+1 staggered sea quarks and staggered or chiral valence quarks. At small u/d masses the correlator is dominated by the bubble contribution, which is the intermediate state with two pseudoscalar mesons. We determine the bubble contribution within Staggered and Mixed Chiral Perturbation Theory. Its effective mass is smaller than the mass M_pi+M_eta, which is the lightest intermediate state in proper 2+1 QCD. The unphysical effective mass is a consequence of the taste breaking that makes possible the intermediate state with mass 2*M_pi. We find that the scalar correlator can be negative in the simulations with mixed quark actions if the sea and valence quark masses are tuned by matching the pion masses M_{val,val}=M_{pi_5}.
Low Mass Dimuon Production in p-A Collisions at $\\sqrt{s} = 27.5$ GeV with NA60
Uras, Antonio; Oppedisano, C; Scomparin, E; Banicz, K; Damjanovic, S; David, A; Forster, A; Guettet, N; Keil, M; Lourenco, C; Martins, P; Radermacher, E; Ramalhete, P; Rosinsky, P; Shahoyan, R; Specht, H J; Castor, J; Devaux, A; Fargeix, J; Seixas, J; Sonderegger, P; Gulkanian, H; Poghosyan, T; Heuser, J M; Guichard, A; Floris, M; Li, Z; Force, P; Ferretti, A; En'yo, H; Ducroux, L; de Falco, A; Colla, A; Cortese, P; Cicalo, C; Pillot, P; Chaurand, B; Ohnishi, H; Parracho, P; Puddu, G; Veenhof, R; Serci, S; Lozano, J; Usai, G; Wohri, H K; Tieulent, R; Masoni, A; Neves, A; Manso, F
2011-01-01
The NA60 experiment has studied low-mass muon pair production in proton-nucleus collisions with a system of Be, Cu, In, W, Pb and U targets using a 400 GeV/$c$ proton beam at the CERN SPS. The mass spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons $\\eta$, $\\rho$, $\\omega$, $\\eta'$ and $\\phi$. A new high-precision measurement of the electromagnetic transition form factors of the $\\eta$ and $\\omega$ mesons is presented, complemented with a measurement of the temperature parameter of the $\\rho$ meson in cold nuclear matter. The $\\pt$ spectra for the $\\omega$ and $\\phi$ mesons are extracted in the full $\\pt$ range accessible, up to $\\pt = 2$ GeV/$c$. The nuclear dependence of the production cross sections for the $\\eta$, $\\omega$ and $\\phi$ mesons has been investigated in terms of the power law $\\sigma_\\mathrm{pA} \\propto \\mathrm{A}^\\alpha$, and the $\\alpha$ parameter was studied as a function of $\\pt$.
The Low-mass Populations in OB Associations
Briceño, C; Sherry, W; Mamajek, E; Mathieu, R; Walter, F; Zinnecker, H; Briceno, Cesar; Preibisch, Thomas; Sherry, William; Mamajek, Eric; Mathieu, Robert; Walter, Frederick; Zinnecker, Hans
2006-01-01
Low-mass stars 0.1 ~< M ~< 1 Msun) in OB associations are key to addressing some of the most fundamental problems in star formation. The low-mass stellar populations of OB associations provide a snapshot of the fossil star-formation record of giant molecular cloud complexes. Large scale surveys have identified hundreds of members of nearby OB associations, and revealed that low-mass stars exist wherever high-mass stars have recently formed. The spatial distribution of low-mass members of OB associations demonstrate the existence of significant substructure ("subgroups"). This "discretized" sequence of stellar groups is consistent with an origin in short-lived parent molecular clouds within a Giant Molecular Cloud Complex. The low-mass population in each subgroup within an OB association exhibits little evidence for significant age spreads on time scales of ~10 Myr or greater, in agreement with a scenario of rapid star formation and cloud dissipation. The Initial Mass Function (IMF) of the stellar popula...
Matos, T; Urena-Lopez, L A; Núñez, D
2001-01-01
This work is a review of the last results of research on the Scalar Field Dark Matter model of the Universe at cosmological and at galactic level. We present the complete solution to the scalar field cosmological scenario in which the dark matter is modeled by a scalar field $\\Phi$ with the scalar potential $V(\\Phi)=V_{0}(cosh {(\\lambda \\sqrt{\\kappa_{0}}\\Phi)}-1)$ and the dark energy is modeled by a scalar field $\\Psi$, endowed with the scalar potential $\\tilde{V}(\\Psi)= \\tilde{V_{0}}(\\sinh{(\\alpha \\sqrt{\\kappa_{0}}\\Psi)})^{\\beta}$, which together compose the 95% of the total matter energy in the Universe. The model presents successfully deals with the up to date cosmological observations, and is a good candidate to treat the dark matter problem at the galactic level.
Baryogenesis with Scalar Bilinears
Ma, E; Sarkar, U; Ma, Ernest; Raidal, Martti; Sarkar, Utpal
1999-01-01
We show that if a baryon asymmetry of the universe is generated through the out-of-equilibrium decays of heavy scalar bilinears coupling to two fermions of the minimal standard model, it is necessarily an asymmetry conserving $(B-L)$ which cannot survive past the electroweak phase transition because of sphalerons. We then show that a surviving $(B-L)$ asymmetry may be generated if the heavy scalars decay into two fermions, \\underline {and into two light scalars} (which may be detectable at hadron colliders). We list all possible such trilinear scalar interactions, and discuss how our new baryogenesis scenario may occur naturally in supersymmetric grand unified theories.
Energy Technology Data Exchange (ETDEWEB)
Kleihaus, Burkhard, E-mail: b.kleihaus@uni-oldenburg.de [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Kunz, Jutta [Institut für Physik, Universität Oldenburg, Postfach 2503, D-26111 Oldenburg (Germany); Yazadjiev, Stoytcho [Department of Theoretical Physics, Faculty of Physics, Sofia University, Sofia 1164 (Bulgaria)
2015-05-11
In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
Directory of Open Access Journals (Sweden)
Burkhard Kleihaus
2015-05-01
Full Text Available In the presence of a complex scalar field scalar–tensor theory allows for scalarized rotating hairy black holes. We exhibit the domain of existence for these scalarized black holes, which is bounded by scalarized rotating boson stars and hairy black holes of General Relativity. We discuss the global properties of these solutions. Like their counterparts in general relativity, their angular momentum may exceed the Kerr bound, and their ergosurfaces may consist of a sphere and a ring, i.e., form an ergo-Saturn.
The Thermal Pulses of Very-Low-Mass Stars
Gautschy, Alfred
2013-01-01
Very-low-mass stars can develop secularly unstable hydrogen-burning shells late in their life. Since the thermal pulses that go along are driven at the bottoms of very shallow envelopes, the stars' luminosities and effective temperatures react strongly during a pulse cycle. Towards the end of the Galaxy's stelliferous era, the hydrogen-shell flashing very-low-mass single stars should inflict an intricate light-show performed by the large population of previously inconspicuous dim stars. Unfortunately, this natural spectacle will discharge too late for mankind to indulge in. Not all is hopeless, though: In the case of close binary-star evolution, hydrogen-shell flashes of mass-stripped, very-low mass binary components can develop in a fraction of a Hubble time. Therefore, the Galaxy should be able put forth a few candidates that are going to evolve through a H-shell flash in a humanity-compatible time frame.
Diffractive production of mesons
Schicker, R
2014-01-01
The interest in the study of diffractive meson production is discussed. The description of diffraction within Regge phenomenology is presented, and the QCD-based understanding of diffractive processes is given. Central production is reviewed, and the corresponding main results from the COMPASS experiment and from the experiments at the ISR, RHIC, TEVATRON and LHC collider are summarised.
Energy Technology Data Exchange (ETDEWEB)
Frederic D. R. Bonnet; Robert G. Edwards; George T. Fleming; Randal Lewis; David Richards
2003-07-22
We have started a program to compute the electromagnetic form factors of mesons. We discuss the techniques used to compute the pion form factor and present preliminary results computed with domain wall valence fermions on MILC asqtad lattices, as well as Wilson fermions on quenched lattices. These methods can easily be extended to rho-to-gamma-pi transition form factors.
Diffractive production of mesons
Directory of Open Access Journals (Sweden)
Schicker Rainer
2014-01-01
Full Text Available The interest in the study of diffractive meson production is discussed. The description of diffraction within Regge phenomenology is presented, and the QCD-based understanding of diffractive processes is given. Central production is reviewed, and the corresponding main results from the COMPASS experiment and from the experiments at the ISR, RHIC, TEVATRON and LHC collider are summarised.
Page, Philip R.
1998-01-01
We report on some interesting recent theoretical and experimental advances on J^PC exotics and hybrid mesons. These are the decay selection rules governing J^PC exotic decay, the experimental evidence for a J^PC = 1^-+ exotic in eta pi and rho pi, and the production of charmonium hybrids at forthcoming B-factories.
Direct search for low mass dark matter particles with CCDs
Energy Technology Data Exchange (ETDEWEB)
Barreto, J. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro (Brazil); Cease, H.; Diehl, H.T. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Estrada, J., E-mail: estrada@fnal.gov [Fermi National Accelerator Laboratory, Batavia, IL (United States); Flaugher, B.; Harrison, N.; Jones, J.; Kilminster, B. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Molina, J. [Facultad de Ingenieria, Universidad Nacional de Asuncion (FIUNA), Asuncion (Paraguay); Smith, J. [Fermi National Accelerator Laboratory, Batavia, IL (United States); Schwarz, T. [University of California at Davis, CA (United States); Sonnenschein, A. [Fermi National Accelerator Laboratory, Batavia, IL (United States)
2012-05-15
A direct dark matter search is performed using fully-depleted high-resistivity CCD detectors. Due to their low electronic readout noise (R.M.S. {approx}7 eV) these devices operate with a very low detection threshold of 40 eV, making the search for dark matter particles with low masses ({approx}5 GeV) possible. The results of an engineering run performed in a shallow underground site are presented, demonstrating the potential of this technology in the low mass region.
Benchmark low-mass objects in Moving Groups
Directory of Open Access Journals (Sweden)
Burningham B.
2013-04-01
Full Text Available In order to compile a sample of ultracool dwarfs that will serve as benchmarks for testing theoretical formation and evolutionary models, we selected low-mass cool (>M7 objects that are potentially members of five known young Moving Groups in the solar neighbourhood. We have studied the kinematics of the sample, finding that 49 targets belong to the young disk area, from which 36 are kinematic member of one of the five moving groups under study. Some of the identified low-mass members have been spectroscopically characterised (Teff, log g and confirmed as young members through a detailed study of age indicators.
Salgado, M; Nucamendi, U; Salgado, Marcelo; Sudarsky, Daniel; Nucamendi, Ulises
1998-01-01
We study in the physical frame the phenomenon of spontaneous scalarization that occurs in scalar-tensor theories of gravity for compact objects. We discuss the fact that the phenomenon occurs exactly in the regime where the Newtonian analysis indicates it should not. Finally we discuss the way the phenomenon depends on the equation of state used to describe the nuclear matter.
Origin of the hot gas in low-mass protostars
DEFF Research Database (Denmark)
Van Kempen, T. A.; Kristensen, L. E.; Herczeg, G. J.
2010-01-01
Aims. "Water In Star-forming regions with Herschel" (WISH) is a Herschel key programme aimed at understanding the physical and chemical structure of young stellar objects (YSOs) with a focus on water and related species. Methods. The low-mass protostar HH 46 was observed with the Photodetector Ar...
Low-Mass, Low-Power Hall Thruster System
Pote, Bruce
2015-01-01
NASA is developing an electric propulsion system capable of producing 20 mN thrust with input power up to 1,000 W and specific impulse ranging from 1,600 to 3,500 seconds. The key technical challenge is the target mass of 1 kg for the thruster and 2 kg for the power processing unit (PPU). In Phase I, Busek Company, Inc., developed an overall subsystem design for the thruster/cathode, PPU, and xenon feed system. This project demonstrated the feasibility of a low-mass power processing architecture that replaces four of the DC-DC converters of a typical PPU with a single multifunctional converter and a low-mass Hall thruster design employing permanent magnets. In Phase II, the team developed an engineering prototype model of its low-mass BHT-600 Hall thruster system, with the primary focus on the low-mass PPU and thruster. The goal was to develop an electric propulsion thruster with the appropriate specific impulse and propellant throughput to enable radioisotope electric propulsion (REP). This is important because REP offers the benefits of nuclear electric propulsion without the need for an excessively large spacecraft and power system.
On the development of low mass shaking force balanced manipulators
van der Wijk, V.; Herder, Justus Laurens; Lenarcic, Jadran; Stanisic, Michael M.
2010-01-01
Whenever mechanisms have to run at high speeds, dynamic balancing (shaking force and shaking moment balancing) becomes an important issue to reduce machine vibrations. This article considers Fischer’s method of principal vectors for shaking force balancing with low mass addition. A method based on l
Luminosity functions for very low mass stars and brown dwarfs
Laughlin, Gregory; Bodenheimer, Peter
1993-01-01
A theoretical investigation of the luminosity function for low-mass objects to constrain the stellar initial mass function at the low-mass end is reported. The ways in which luminosity functions for low-mass stars are affected by star formation histories, brown dwarf and premain-sequence cooling rates and main-sequence mass luminosity relations, and the IMF are examined. Cooling rates and the mass-luminosity relation are determined through a new series of evolutionary calculations for very low mass stars and brown dwarfs in the range 0.05-0.50 solar mass. Model luminosity functions are constructed for specific comparison with the results of four recent observational surveys. The likelihood that the stellar mass function in the solar neighborhood is increasing at masses near the bottom of the main sequence and perhaps at lower masses is confirmed. In the most optimistic case, brown dwarfs contribute half of the local missing disk mass. The actual contribution is likely to be considerably less.
Origin of the hot gas in low-mass protostars
DEFF Research Database (Denmark)
Van Kempen, T. A.; Kristensen, L. E.; Herczeg, G. J.
2010-01-01
Aims. "Water In Star-forming regions with Herschel" (WISH) is a Herschel key programme aimed at understanding the physical and chemical structure of young stellar objects (YSOs) with a focus on water and related species. Methods. The low-mass protostar HH 46 was observed with the Photodetector...
Polarizability of. pi. mesons in the confined quark model
Energy Technology Data Exchange (ETDEWEB)
Avakyan, E.Z.; Avakyan, S.L.; Efimov, G.V.; Ivanov, M.A. (Joint Institute for Nuclear Research, Dubna (USSR))
1989-05-01
The electric polarizabilities {alpha}{sub {pi}} and magnetic {beta}{sub {pi}} polarizabilities of {pi}{sup +} and {pi}{sup 0} mesons are calculated using the confined quark model. Diagrams with intermediate vector ({rho},{omega}), axial-vector ({ital a}{sub 1}, {ital f}{sub 1}), and scalar ({Epsilon}, {ital f}{sub 0}) states are included. It turns out that the intermediate mesons contribute significantly to the pion electric and magnetic polarizabilities. The following values (in units of 10{sup {minus}43} cm{sup 3}) are obtained: {alpha}{sub {pi}{sup +}}=5.8, {beta}{sub {pi}{sup +}}={minus}5.6, {alpha}{sub {pi}{sup 0}}={minus}1.1, and {beta}{sub {pi}{sup 0}}=2.8. The widths of two-particle strong and radiative decays of scalar mesons are calculated. The results are compared with the available experimental data and the results of other approaches.
Lower and upper bounds on the mass of light quark-antiquark scalar resonance in the SVZ sum rules
Afonin, S S
2016-01-01
The calculation of the mass of light scalar isosinglet meson within the Shifman--Vainshtein--Zakharov (SVZ) sum rules is revisited. We develop simple analytical methods for estimation of hadron masses in the SVZ approach and try to reveal the origin of their numerical values. The calculations of hadron parameters in the SVZ sum rules are known to be heavily based on a choice of the perturbative threshold. This choice requires some important ad hoc information. We show analytically that the scalar mass under consideration has a lower and upper bound which are independent of this choice. The lower limit lies around the $\\omega$-meson mass and the upper one does near the $f_1$-meson mass. Our analysis seems to finally exclude the interpretation of the $f_0(500)$ (called also $\\sigma$) meson as a quark-antiquark state in the SVZ sum rules.
A covariant model of the electromagnetic current for the study of two-body scalar systems
Acero, M A; Sandoval, C E; Sanctis, Maurizio De; Sandoval, Carlos E.
2005-01-01
We present a procedure to derive a covariant electromagnetic current operator for a system made up by two scalars constituents. Using different wave functions we fitted their parameters to the experimental data of the pion form factor, obtainig great discrepancy at low momentum transfer. Introducing the Vector Meson Dominance corrective factor, we obtained a better fit to the data.
To Learn Production of Scalars VS. Tensors in e+e- Collisions
Achasov, N. N.; Goncharenko, A. I.; Kiselev, A. V.; Rogozina, E. V.
2014-12-01
The intensity of scalar a0(980), f0(980) and tensor a2(1320), f2(1270) mesons production at VEPP-2000 (BINP, Novosibirsk) and the upgraded DAΦNE (Frascati, Italy) in the processes e+e- → a0(f0, a2, f2)γ is calculated.
Decays of open charmed mesons in the extended Linear Sigma Model
Directory of Open Access Journals (Sweden)
Eshraim Walaa I.
2014-01-01
Full Text Available We enlarge the so-called extended linear Sigma model (eLSM by including the charm quark according to the global U(4r × U(4l chiral symmetry. In the eLSM, besides scalar and pseudoscalar mesons, also vector and axial-vector mesons are present. Almost all the parameters of the model were fixed in a previous study of mesons below 2 GeV. In the extension to the four-flavor case, only three additional parameters (all of them related to the bare mass of the charm quark appear.We compute the (OZI dominant strong decays of open charmed mesons. The results are compatible with the experimental data, although the theoretical uncertainties are still large.
Meson screening masses at finite temperature with Highly Improved Staggered Quarks
Maezawa, Y; Karsch, F; Petreczky, P; Mukherjee, S
2013-01-01
We report on the first study of the screening properties of the mesonic excitations with strange ($s$) and charm ($c$) quarks, specifically the ground states of the pseudo-scalar and vector meson excitations for the $\\bar{s}s$, $\\bar{s}c$ and $\\bar{c}c$ flavor combinations, using the Highly Improved Staggered Quark action with dynamical physical strange quark and nearly-physical up and down quarks. By comparing with their respective vacuum meson masses and by investigating the influence of the changing temporal boundary conditions of the valence quarks we study the thermal modifications of these mesonic excitations. While the $\\bar{s}s$ states show significant modifications even below the chiral crossover temperature $T_c$, the modifications of the open-charm and charmonium like states become visible only for temperatures $T\\gtrsim T_c$ and $T\\gtrsim1.2T_c$, respectively.
Screening of the meson fields in the Nambu - Jona-Lasinio model
Energy Technology Data Exchange (ETDEWEB)
Florkowski, W. [Institute of Nuclear Physics, Cracow (Poland)]|[Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Friman, B.L. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)]|[Technische Hochschule Darmstadt (Germany). Inst. fuer Kernphysik
1993-03-01
The spatial dependence of the finite-temperature meson correlation function in the (pseudo)scalar channel is studied in the Nambu-Jona-Lasinio model. The screening masses, obtained from the asymptotic behaviour of the static correlation function, are found to differ substantially from the dynamic masses, defined by a pole of the meson propagator. In particular, at high temperatures, the meson screening masses are large, although there are no well defined meson modes. In the high-temperature limit, the screening masses approach 2{pi}T, which corresponds to a gas of non-interacting, massless quarks. However interaction effects remain well beyond the chiral transition temperatures. The overall temperature dependence of the screening masses is in agreement with lattice results. (author). 26 refs, 5 figs.
Warm stellar matter within the quark-meson-coupling model
Panda, P. K.; Providência, C.; Menezes, D. P.
2010-10-01
In the present article, we investigate stellar matter obtained within the quark-meson-coupling (QMC) model for fixed temperature and with the entropy of the order of 1 or 2 Boltzmann units per baryon for neutrino-free matter and matter with trapped neutrinos. A new prescription for the calculation of the baryon effective masses in terms of the free energy is used. Comparing the results of the present work with those obtained from the nonlinear Walecka model, smaller strangeness and neutrino fractions are predicted within QMC. As a consequence, QMC has a smaller window of metastability for conversion into a low-mass blackhole during cooling.
Importance of the meson cloud to hadron structure
Pearce, B. C.; Speth, J.; Szczurek, A.
1994-07-01
We present a review of our recent results on the role of the mesonic cloud in the structure of hadrons in both soft and hard kinematical regimes. We compute the pion and nucleon form factors of the scalar operator overlineuu + overlinedd within a meson exchange model. Our results agree with recent dispersion relation analyses near the Cheng-Dashen point but show some deviation at higher energies. In particular, we confirm the observation that the strong ππ interaction gives rise to a scalar square radius of the nucleon of 1.5 fm 2 and a 15 MeV contribution to the pion nucleon sigma term. Some aspects of the meson cloud around the nucleon for deep-inelastic lepton scattering are studied in the framework of the Sullivan formalism. We present a simple two-phase model of the nucleon. Renormalization of the valence quark distribution due to the mesonic cloud is taken into account explicitly. We study the dependence of different quantities on the cut-off parameter of the form factor, the role of different mesons in deep-inelastic scattering, and SU(2) F symmetry breaking in the nucleon sea in connection to the Gottfried Sum Rule. It is possible to obtain agreement with the CCFR data using relatively hard meson-N-N form factors. The E615 data on ( overlineu + overlined)/2 - overlines restrict the cut-off parameter in the dipole form factor to about 1.2 GeV. For this value the cut-off parameter we get the largest violation of the Gottfried Sum Rule, about half of that observed by NMC. Mesonic models predict violation of the SU (2) symmetry in the nucleon sea which seems to be necessary to explain the violation of the Gottfried Sum Rule. Since up to now there is no consensus concerning the explanation of the NMC effect, one has to study the role the overlined/ overlineu asymmetry may play in other processes. Here we study the effect of the asymmetry for the Drell-Yan processes. We find that careful analysis of the dilepton production in the p-p and p-n collisions should
Light Meson Distribution Amplitudes
Arthur, R.; Brommel, D.; Donnellan, M.A.; Flynn, J.M.; Juttner, A.; de Lima, H.Pedroso; Rae, T.D.; Sachrajda, C.T.; Samways, B.
2010-01-01
We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.
Photoproduction of Pseudoscalar Mesons
Arndt, R A; O'Rielly, G V; Strakovsky, I I; Workman, R L
2003-01-01
Experiments that study the photoproduction of pseudoscalar mesons; pions, etas and kaons, have the potential to increase our knowledge of baryon and hyperon resonance properties. Recent experiments at JLab, Mainz, GRAAL, and Bonn are beginning to produce results in the form of polarization and asymmetry measurements and determinations of the differential and integrated cross sections. These new data are essential to the performance of Partial-Wave Analyses that are less model dependent and coupled-channels calculations that incorporate unitarity dynamically,combining hadronic reaction channels together with electromagnetic processes. This approach is necessary to extract resonance properties and may lead to the identification of missing, but predicted, resonances. Some recent experimental and phenomenological results for single and double pseudoscalar meson photoproduction are discussed.
Dillig, M
2002-01-01
We investigate the exclusive production of the pseudoscalar mesons $\\pi ^{0}, \\eta, \\eta^{\\prime}, K^{+}$ and of the vector mesons $\\omega, \\phi$ in a microscopic gluon-exchange or instanton model. We describe the baryons as covariant quark - scalar diquark systems with harmonic confinement, thus taking into account center-of-mass corrections and Lorentz contraction in different frames. The excitation of intermediate baryon resonances is accounted by colorless 2-gluon (soft Pomeron) exchange. We find that our model accounts for the systematics of the high precision data on exclusive meson production from various modern proton factories.
Terasaki, Kunihiko
2008-01-01
It is pointed out that assigning D_{s0}^+(2317) to an iso-triplet tetra-quark meson is favored by experiments. It also is discussed why its neutral and doubly charged partners have never been observed in inclusive e^+e^- annihilation. To search for them, hadronic weak decays of B mesons would be better, and their production rates, Br(B_u^+ -> D^-D_{s0}^{++}(2317)) and Br(B_d^0 ->antiD^0D_{s0}^{0}(2317)), would be around 10^{-3}.
Page, P R
1996-01-01
New experimental information on the non--exotic J^{PC} = 0^{-+} isovector seen at 1.8 GeV by VES yields convincing evidence of its excited gluonic (hybrid) nature when a critical study of alternative quarkonium assignments is made in the context of ^3 P_0 decay by flux--tube breaking. Production of this gluonic excitation via meson exchange is promising, although its two photon production vanishes.
Albrecht, H.; Binder, U.; Böckmann, P.; Gläser, R.; Harder, G.; Lembke-Koppitz, I.; Schmidt-Parzefall, W.; Schröder, H.; Schulz, H. D.; Wurth, R.; Yagil, A.; Donker, J. P.; Drescher, A.; Kamp, D.; Matthiesen, U.; Scheck, H.; Spaan, B.; Spengler, J.; Wegener, D.; Gabriel, J. C.; Schubert, K. R.; Stiewe, J.; Strahl, K.; Waldi, R.; Weseler, S.; Edwards, K. W.; Frisken, W. R.; Gilkinson, D. J.; Gingrich, D. M.; Kapitza, H.; Kim, P. C. H.; Kutschke, R.; Macfarlane, D. B.; McKenna, J. A.; McLean, K. W.; Nilsson, A. W.; Orr, R. S.; Padley, P.; Parsons, J. A.; Patel, P. M.; Prentice, J. D.; Seywerd, H. C. J.; Swain, J. D.; Tsipolitis, G.; Yoon, T.-S.; Yun, J. C.; Ammar, R.; Coppage, D.; Davis, R.; Kanekal, S.; Kwak, N.; Boštjančič, B.; Kernel, G.; Pleško, M.; Jönsson, L.; Babaev, A.; Danilov, M.; Golutvin, A.; Gorelov, I.; Lubimov, V.; Matveev, V.; Nagovitsin, V.; Ryltsov, V.; Semenov, A.; Shevchenko, V.; Soloshenko, V.; Tchistilin, V.; Tichomirov, I.; Zaitzev, Yu.; Childers, R.; Darden, C. W.; Oku, Y.; Gennow, H.; Argus Collaboration
1987-02-01
B mesons have been reconstructed in five decay channels of the type B→D ∗±nπ(n=1,2,3) using data accumulated by the ARGUS experiment at the e +e - storage ring DORIS II at DESY. In total, we find 40 neutral B mesons above a background of 15±6 events with a mass of (5278.2±1.0±3.0) MeV/ c2 and 32 charged B mesons above a background of 17±6 events with a mass of (5275.8±1.3±3.0) MeV/ c2. The decays overlineB0D∗+π -π 0, overlineB0D∗+π -π -π +, and B-→ D∗+π -π -π 0 have been observed for the first time. We find substantially smaller branching ratios for the decay modes overlineB0→ D∗+π - and B-→ D∗+π -π - than previously published by the CLEO collaboration.
The Effect of Vector Meson Decays on Dihadron Fragmentation Functions
Directory of Open Access Journals (Sweden)
Matevosyan Hrayr H.
2014-03-01
Full Text Available Dihadron Fragmentation Functions (DFF provide a vast amount of information on the intricate details of the parton hadronization process. Moreover, they provide a unique access to the “clean” extraction of nucleon transversity parton distribution functions in semi inclusive deep inelastic two hadron production process with a transversely polarised target. On the example of the u → π+π−, we analyse the properties of unpolarised DFFs using their probabilistic interpretation. We use both the NJL-jet hadronization model and PYTHIA 8.1 event generator to explore the effect of the strong decays of the vector mesons produced in the quark hadronization process on the pseudoscalar DFFs. Our study shows that, even though it is less probable to produce vector mesons in the hadronization process than pseudo scalar mesons of the same charge, the products of their strong decays drastically affect the DFFs for pions because of the large combinatorial factors. Thus, an accurate description of both vector meson production and decays are crucial for theoretical understanding of DFFs.
D¯ D meson pair production in antiproton-nucleus collisions
Shyam, R.; Tsushima, K.
2016-10-01
We study the D ¯D (D¯0D0 and D-D+) charm meson pair production in antiproton (p ¯) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the t -channel exchanges of Λc+, Σc+, and Σc++ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approximated by using an eikonal approximation-based procedure. Detailed numerical results are presented for total and double differential cross sections for the D¯0D0 and D-D+ production reactions on 16O and 90Zr targets. It is noted that at p ¯ beam momenta of interest to the P ¯ ANDA experiment, medium effects lead to noticeable enhancements in the charm meson production cross sections.
Vargyas, Marton
2013-01-01
In case of an UA(1) symmetry restoration in a hot and dense hadronic matter, the mass of the produced hadrons and mesons can significantly change, and their production cross-section can also be modified. In this M.Sc. Thesis I search for the signature of an eta' enhancement in the PHENIX dilepton spectrum in 200 GeV Au+Au collisions, which has a significant enhancement in the low-mass region, e.g. in the (0.1-1.0) GeV invariant electron-positron mass range. This is also the region of the eta' meson's Dalitz-decay (eta'->ee gamma), so the eta' enhancement might be responsible for at least a part of the excess. Other mesons' (other) properties can also be changed in the hot, dense medium, but in this thesis I focus on the mass modification of the eta' meson. To explore the role of eta', I used EXODUS simulations to generate different dilepton spectra, corresponding to different eta' properties. The conclusion here was that the excess can not be described with just the eta' mass modification, but the agreement w...
Dynamical corotation torques on low-mass planets
Paardekooper, Sijme-Jan
2014-01-01
We study torques on migrating low-mass planets in locally isothermal discs. Previous work on low-mass planets generally kept the planet on a fixed orbit, after which the torque on the planet was measured. In addition to these static torques, when the planet is allowed to migrate it experiences dynamical torques, which are proportional to the migration rate and whose sign depends on the background vortensity gradient. We show that in discs a few times more massive than the Minimum Mass Solar Nebula, these dynamical torques can have a profound impact on planet migration. Inward migration can be slowed down significantly, and if static torques lead to outward migration, dynamical torques can take over, taking the planet beyond zero-torque lines set by saturation of the corotation torque in a runaway fashion. This means the region in non-isothermal discs where outward migration is possible can be larger than what would be concluded from static torques alone.
Accurate Low-Mass Stellar Models of KOI-126
Feiden, Gregory A; Dotter, Aaron
2011-01-01
The recent discovery of an eclipsing hierarchical triple system with two low-mass stars in a close orbit (KOI-126) by Carter et al. (2011) appeared to reinforce the evidence that theoretical stellar evolution models are not able to reproduce the observational mass-radius relation for low-mass stars. We present a set of stellar models for the three stars in the KOI-126 system that show excellent agreement with the observed radii. This agreement appears to be due to the equation of state implemented by our code. A significant dispersion in the observed mass-radius relation for fully convective stars is demonstrated; indicative of the influence of physics currently not incorporated in standard stellar evolution models. We also predict apsidal motion constants for the two M-dwarf companions. These values should be observationally determined to within 1% by the end of the Kepler mission.
Old star clusters: Bench tests of low mass stellar models
Directory of Open Access Journals (Sweden)
Salaris M.
2013-03-01
Full Text Available Old star clusters in the Milky Way and external galaxies have been (and still are traditionally used to constrain the age of the universe and the timescales of galaxy formation. A parallel avenue of old star cluster research considers these objects as bench tests of low-mass stellar models. This short review will highlight some recent tests of stellar evolution models that make use of photometric and spectroscopic observations of resolved old star clusters. In some cases these tests have pointed to additional physical processes efficient in low-mass stars, that are not routinely included in model computations. Moreover, recent results from the Kepler mission about the old open cluster NGC6791 are adding new tight constraints to the models.
The different baryonic Tully-Fisher relations at low masses
Brook, Chris B.; Santos-Santos, Isabel; Stinson, Greg
2016-06-01
We compare the Baryonic Tully-Fisher relation (BTFR) of simulations and observations of galaxies ranging from dwarfs to spirals, using various measures of rotational velocity Vrot. We explore the BTFR when measuring Vrot at the flat part of the rotation curve, Vflat, at the extent of H I gas, Vlast, and using 20 per cent (W20) and 50 per cent (W50) of the width of H I line profiles. We also compare with the maximum circular velocity of the parent halo, V_max^DM, within dark matter only simulations. The different BTFRs increasingly diverge as galaxy mass decreases. Using Vlast one obtains a power law over four orders of magnitude in baryonic mass, with slope similar to the observed BTFR. Measuring Vflat gives similar results as Vlast when galaxies with rising rotation curves are excluded. However, higher rotation velocities would be found for low-mass galaxies if the cold gas extended far enough for Vrot to reach a maximum. W20 gives a similar slope as Vlast but with slightly lower values of Vrot for low-mass galaxies, although this may depend on the extent of the gas in your galaxy sample. W50 bends away from these other relations towards low velocities at low masses. By contrast, V_max^DM bends towards high velocities for low-mass galaxies, as cold gas does not extend out to the radius at which haloes reach V_max^DM. Our study highlights the need for careful comparisons between observations and models: one needs to be consistent about the particular method of measuring Vrot, and precise about the radius at which velocities are measured.
Nuclear symmetry energy in a modified quark meson coupling model
Mishra, R N; Panda, P K; Barik, N; Frederico, T
2015-01-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to $\\sigma$, $\\omega$, and $\\rho$ mesons through mean-field approximations. We find an analytic expression for the symmetry energy ${\\cal E}_{sym}$ as a function of its slope $L$. Our result establishes a linear correlation between $L$ and ${\\cal E}_{sym}$. We also analyze the constraint on neutron star radii in $(pn)$ matter with $\\beta$ equilibrium.
Studies of phi meson radiative decays with KLOE
Energy Technology Data Exchange (ETDEWEB)
Aloisio, A.; Ambrosino, F.; Antonelli, A.; Antonelli, M.; Bacci, C.; Bencivenni, G.; Bertolucci, S.; Bini, C.; Bloise, C.; Bocci, V.; Bossi, F.; Branchini, P.; Bulychjov, S.A.; Caloi, R.; Campana, P.; Capon, G.; Carboni, G.; Casarsa, M.; Casavola, V.; Cataldi, G.; Ceradini, F.; Cervelli, F.; Cevenini, F.; Chiefari, G.; Ciambrone, P.; Conetti, S.; De Lucia, E.; De Robertis, G.; De Simone, P.; De Zorzi, G.; Dell' Agnello, S.; Denig, A.; Di Domenico, A.; Di Donato, C.; Di Falco, S.; Doria, A.; Dreucci, M.; Erriquez, O.; Farilla, A.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Finocchiaro, G.; Forti, C.; Franceschi, A.; Franzini, P.; Gatt, C.; Gauzzi, P.; Giovannella, S.; Gorini, E.; Grancagnolo, F.; Graziani, E.; Han, S.W.; Incagli, M.; Ingrosso, L.; Kluge, W.; Kuo, C.; Kulikov, V.; Lacava, F.; Lanfranchi, G.; Lee-Franzini, J.; Leone, D.; Lu, F.; Martemianov, M.; Matsyuk, M.; Mei, W.; Merola, L.; Messi, R.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Napolitano, M.; Nedosekin, A.; Nguyen, F.; Palutan, M.; Pasqualucci, E.; Passalacqua, L.; Passeri, A.; Patera, V.; Petrolo, E.; Pontecorvo, L.; Primavera, M.; Ruggieri, F.; Santangelo, P.; Santovetti, E.; Saracino, G.; Schamberger, R.D.; Sciascia, B.; Sciubba, A.; Scuri, F.; Sfiligoi, I.; Spadaro, T.; Spiriti, E.; Tong, G.L.; Tortora, L.; Valente, E.; Valente, P.; Valeriani, B.; Vernanzoni, G.; Veneziano, S.; Ventura, A.; Xu, G.; Yu, G.W
2003-04-01
A sample of 5.3 x 10{sup 7}phi mesons, produced at the Frascati phi-factory DAPHINE, has been used by the KLOE Collaboration to study the phi radiative decays. The decays phi {yields} {eta}{pi}{sup 0}{gamma} and phi {yields} {pi}{sup o}{pi}{sup o}{gamma} have been exploited to study the scalar mesons a{sub o}(980) and f{sub o}(980). Furthermore a new determination of the {eta} - {eta}' mixing angle has been obtained from the measurement of the ratio of the decay rates of phi {yields} {eta}'{gamma} to phi {yields} {eta}{gamma} to phi {yields} {eta}{gamma}.
Effective field theory for pions and a dilatonic meson
Golterman, Maarten
2016-01-01
Numerical simulations of QCD-like theories which are chirally broken but exhibit a very small beta function reveal a flavor-singlet scalar, or "dilatonic meson," which is much lighter than any other states except pions. We develop a systematic low-energy expansion for the pions and the dilatonic meson, in which the presence of the latter is attributed to an approximate scale symmetry. In order to justify the power counting we invoke the Veneziano limit, in which the number of flavors $N_f$ in the fundamental representation grows in proportion with the number of colors $N_c$, while the ratio $N_f/N_c$ is kept close to, but below, the critical value where the conformal window is entered.
Formation and composition of planets around very low mass stars
Alibert, Yann
2016-01-01
The recent detection of planets around very low mass stars raises the question of the formation, composition and potential habitability of these objects. We use planetary system formation models to infer the properties, in particular their radius distribution and water content, of planets that may form around stars ten times less massive than the Sun. Our planetary system formation and composition models take into account the structure and evolution of the protoplanetary disk, the planetary mass growth by accretion of solids and gas, as well as planet-planet, planet-star and planet-disk interactions. We show that planets can form at small orbital period in orbit about low mass stars. We show that the radius of the planets is peaked at about 1 rearth and that they are, in general, volatile rich especially if proto-planetary discs orbiting this type of stars are long-lived. Close-in planets orbiting low-mass stars similar in terms of mass and radius to the ones recently detected can be formed within the framewo...
Rare B Meson Decays With Omega Mesons
Energy Technology Data Exchange (ETDEWEB)
Zhang, Lei; /Colorado U.
2006-04-24
Rare charmless hadronic B decays are particularly interesting because of their importance in understanding the CP violation, which is essential to explain the matter-antimatter asymmetry in our universe, and of their roles in testing the ''effective'' theory of B physics. The study has been done with the BABAR experiment, which is mainly designed for the study of CP violation in the decays of neutral B mesons, and secondarily for rare processes that become accessible with the high luminosity of the PEP-II B Factory. In a sample of 89 million produced B{bar B} pairs on the BABAR experiment, we observed the decays B{sup 0} {yields} {omega}K{sup 0} and B{sup +} {yields} {omega}{rho}{sup +} for the first time, made more precise measurements for B{sup +} {yields} {omega}h{sup +} and reported tighter upper limits for B {yields} {omega}K* and B{sup 0} {yields} {omega}{rho}{sup 0}.
MesonNet Workshop on Meson Transition Form Factors
Eidelman, S; Hanhart, C; Kubis, B; Kupsc, A; Leupold, S; Moskal, P; Schadmand, S
2012-01-01
The mini-proceedings of the Workshop on Meson Transition Form Factors held in Cracow from May 29th to 30th, 2012 introduce the meson transition form factor project with special emphasis on the interrelations between the various form factors (on-shell, single off-shell, double off-shell). Short summaries of the talks presented at the workshop follow.
Meson-Meson Scattering in Relativistic Constraint Dynamics
Crater, H W; Crater, Horace W.
2004-01-01
Dirac's relativistic constraint dynamics have been successfully applied to obtain a covariant nonperturbative description of QED and QCD bound states. We use this formalism to describe a microscopic theory of meson-meson scattering as a relativistic generalization of the nonrelativistic quark-interchange model developed by Barnes and Swanson.
The Magsat scalar magnetometer
Farthing, W. H.
1980-01-01
The Magsat scalar magnetometer is derived from optical pumping magnetometers flown on the orbiting geophysical observatories. The basic sensor, a cross-coupled arrangement of absorption cells, photodiodes, and amplifiers, oscillates at the Larmor frequency of atomic moments precessing about the ambient field direction. The Larmor frequency output is accumulated digitally and stored for transfer to the spacecraft telemetry stream. In orbit the instrument has met its principal objective of calibrating the vector magnetometer and providing scalar field data.
Search for Invisible Decays of Dark Photons and Low Mass Higgs Bosons at BaBar
Giuffrida, Alexander; BaBar Collaboration
2017-01-01
The BaBar detector at the PEP-II asymmetric B-Factory collected a large dataset of e+e-collisions at the center-of-mass energies near Upsilon mesons. We use the BaBar dataset recorded in 2007-2008 to search for events that produce a high energy photon and no other visible decay products. Such invisible decays may occur through the process ϒ -> γ A, where Ais a light CP-odd Higgs scalar, or e+e- -> γ A', where A' is a Dark Photon vector particle. This search takes advantage ofa high energy single photon trigger, so that such events would be recorded despite the lack of visible charged tracks. We have tuned our selection on 10% of the data collected with the single photon triggers. Our analysis uses machine learning techniques to enhance the selection efficiencies and suppress the backgrounds. For the final results, we apply our selection to the full data set of approximately 60 fb-1. We observed no significant signal, and set the upper limits on the branching ratio of ϒ -> γ A and cross section of e+e- -> γ A'. For the A' mode, our upper limits on the mixing strength parameter rule out the Dark Photon as an explanation for the aμ anomaly. Rose Hills Foundation.
Spacetime compactification induced by scalars
Energy Technology Data Exchange (ETDEWEB)
Gell-Mann, M.; Zwiebach, B.
1984-07-05
It is shown that scalars of a nonlinear sigma model coupled to gravity can trigger spontaneous compactification of spacetime if the scalar manifold has an Einstein metric and the scalar self-coupling constant takes a specific value. The compactified space becomes isomorphic to the scalar manifold and the four-dimensional space has no cosmological term at the classical level.
Heavy meson fragmentation at LHC
Directory of Open Access Journals (Sweden)
M. A. Gomshi Nobary
2003-06-01
Full Text Available Large Hadron Collider (LHC at CERN will provide excellent opportunity to study the production and decay of heavy mesons and baryons with high statistics. We aim at the heavy mesons in this work and calculate their fragmentation functions consistent with this machine and present their total fragmentation probabilities and average fragmentation parameters.
Decay Constants of Vector Mesons
Institute of Scientific and Technical Information of China (English)
LI Heng-Mei; WAN Shao-Long
2008-01-01
@@ The light vector mesons are studied within the framework of the Bethe-Salpeter equation with the vector-vectortype flat-bottom potential The Bethe-Salpeter wavefunctions and the decay constants of the vector mesons are obtained. All the obtained results, fρ, fφ, and fΚ* , are in agreement with the experimental values, respectively.
Exotic meson spectroscopy with CLAS
Energy Technology Data Exchange (ETDEWEB)
Adams, G.; Napolitano, J. [Rensselaer Polytechnic Inst., Troy, NY (United States)
1994-04-01
The identification and study of mesons with explicit gluonic degrees of freedom will provide major constraints on nonperturbative QCD and models thereof. CLAS will provide a unique opportunity for studying these resonances by measuring photoproduction of multi-meson final states.
The light meson spectroscopy program
Directory of Open Access Journals (Sweden)
Smith Elton S.
2014-06-01
Full Text Available Recent discoveries of a number of unexpected new charmomium-like meson states at the BaBar and Belle B-factories have demonstrated how little is still known about meson spectroscopy. In this talk we will review recent highlights of the light quark spectroscopy from collider and fixed target experiments.
The light meson spectroscopy program
Energy Technology Data Exchange (ETDEWEB)
Smith, Elton S. [JLAB
2014-06-01
Recent discoveries of a number of unexpected new charmomium-like meson states at the BaBar and Belle B-factories have demonstrated how little is still known about meson spectroscopy. In this talk we will review recent highlights of the light quark spectroscopy from collider and fixed target experiments.
Meson Resonances from Lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Edwards, Robert G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-06-01
There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the method in meson systems.
Meson resonances on the lattice
Energy Technology Data Exchange (ETDEWEB)
Edwards, Robert G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2016-06-01
There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the method in meson systems
DN interaction from meson exchange
Haidenbauer, J.; Krein, G.; Meiner, U. -G.; Tolos, L.
A model of the DN interaction is presented which is developed in close analogy to the meson-exchange (K) over barN potential of the Julich group utilizing SU(4) symmetry constraints. The main ingredients of the interaction are provided by vector meson (rho, omega) exchange and higher-order box
The Present Status on sigma and kappa Meson Properties
Ishida, M
2003-01-01
The recent experimental data of both pipi / Kpi scattering and production processes, suggesting the existence of scalar sigma and kappa mesons, are reviewed. In many pipi /Kpi production processes the direct effects of their productions are observed, while they are, because of chiral symmetry, hidden in scattering processes, and now sigma(500--600) and kappa(800--900) are considered to be confirmed experimentally. The recent criticism on our method of analyses, which is based on the long believed prejudice of universal pipi / Kpi phase through scattering and production amplitudes, is explained not to be valid.
Light Meson Physics from Maximally Twisted Mass Lattice QCD
Baron, R; Dimopoulos, P; Farchioni, F; Frezzotti, R; Gimenez, V; Herdoiza, G; Jansen, K; Lubicz, V; Michael, C; Muenster, G; Palao, D; Rossi, G C; Scorzato, L; Shindler, A; Simula, S; Sudmann, T; Urbach, C; Wenger, U
2009-01-01
We present a comprehensive investigation of light meson physics using maximally twisted mass fermions for two mass-degenerate quark flavours. By employing four values of the lattice spacing, spatial lattice extents ranging from 2.0 fm to 2.5 fm and pseudo scalar masses in the range 280 MeV to 650 MeV we control the major systematic effects of our calculation. This enables us to confront our data with chiral perturbation theory and extract low energy constants of the effective chiral Lagrangian and derived quantities, such as the light quark mass, with high precision.
Palazzi, Paolo
2007-01-01
The neglected 35 MeV/c2 particle mass quantization hypothesis has recently been reassessed for all known meson states. The rule is found to be statistically relevant, once the states are grouped by quark composition and JPC, with slightly different mass units for each group. In certain groups the mass unit is spin-dependent. Also the mass units are linearly quantized, with highly structured correlation patterns. The baryon masses are organized along similar lines. These results support an indication that hadrons might be shell-structured.
Physics opportunities with meson beams
Energy Technology Data Exchange (ETDEWEB)
Briscoe, William J.; Doering, Michael; Haberzettl, Helmut; Strakovsky, Igor I. [The George Washington University, Washington, DC (United States); Manley, D.M. [Kent State University, Kent, OH (United States); Naruki, Megumi [Kyoto University, Kyoto (Japan); Swanson, Eric S. [University of Pittsburgh, Pittsburgh, PA (United States)
2015-10-15
Over the past two decades, meson photo- and electroproduction data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even non-existent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state-of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility. (orig.)
Physics Opportunities with Meson Beams
Briscoe, William J; Haberzettl, Helmut; Manley, D Mark; Naruki, Megumi; Strakovsky, Igor I; Swanson, Eric S
2015-01-01
Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.
Wang, X J; Wang, Xiao-Jun; Yan, Mu-Lin
1999-01-01
We study SU(3)$_L\\timesSU(3)_R$ chiral quark model of mesons up to next leading order of $1/N_c$ expansion. Composite vector and axial-vector mesons resonances are introduced via non-linear realization of chiral SU(3) and vector meson dominant. Effects of one-loop graphs of pseudoscalar, vector and axial-vector mesons is calculated systematically and the significant results are obtained. Correction of effective gluon interaction is studied too. The light quark masses are introduced via new mechanism which agree with phenomenology and the requirement of chiral symmetry. Up to powers four of derivatives, chiral effective lagrangian of mesons is derived and evaluated to next leading order of $1/N_c$. Low energy limit of the model is examined. Ten low energy coupling constants $L_i(i=1,2,...,10)$ in ChPT are obtained and agree with ChPT well.
Low mass vector-meson production in p-W and S-U high energy collisions
Energy Technology Data Exchange (ETDEWEB)
Abreu, N.C. [LIP, Av. Elias Garcia 14, P-1000 Lisbon (Portugal)]|[FCUL, Universidade de Lisboa, Lisbon (Portugal); Baglin, C.; Baldit, A.; Barriere, C.; Bedjidian, M.; Borhani, A.; Contardo, D.; Descroix, E.; Devaux, A.; Drapier, O.; Espagnon, B.; Fargeix, J.; Ferreira, R.; Force, P.; Gago, J.; Gerschel, C.; Gorodetzky, P.; Grossiord, J.Y.; Guichard, A.; Guillaud, J.P.; Guimaraes, J.; Haroutunian, R.; Jouan, D.; Jouan, D.; Kluberg, L.; Kossakowski, R.; Landaud, G.; Lourenco, C.; Luquin, L.; Malek, F.; Mandry, L.; Mazini, R.; Pizzi, J.R.; Racca, C.; Ramos, S.; Romana, A.; Ronceux, B.; Silva, S.; Sonderegger, P.; Rarrago, X.; Varela, J.; NA38 Collaboration
1995-07-20
NA 38 results on {rho}+{omega} and {phi} production in p-W and S-U interactions at 200 GeV/nucleon are presented. Transverse mass distributions and slopes are measured. The value of the ratio {ital B}{sub {phi}}{sigma}{sub {phi}}/{ital B}{sub {rho}}{sigma}{sub {rho}}+{ital B}{sub {omega}}{sigma}{sub {omega}} is given for different {ital P}{sub {ital T}} and that it increases with {epsilon} when going from p-W to S-U collisions. Assuming the A dependence {sigma}{sub {ital SU}} ={sigma}{sub 0} ({ital A}{sub {ital beam}} {center_dot} {ital A}{sub {ital target}}){sup {alpha}}, we obtain {alpha}{sub {phi}} values significantly bigger than one and greater than the {alpha}{sub {rho}+{omega}} values in different {ital P}{sub {ital T}} regions. All these results clearly show a {phi} enhancement going from {ital p}{minus}{ital W} to {ital S}{minus}{ital U} interactions independent of {ital P}{sub {ital T}}. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.
Weak leptonic decay of light and heavy pseudoscalar mesons in an independent quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Dash, P.C. (Department of Physics, Utkal University, Bhubaneswar-751004 (India))
1993-04-01
Weak leptonic decays of light and heavy pseudoscalar mesons are studied in a field-theoretic framework based on the independent quark model with a scalar-vector harmonic potential. Defining the quark-antiquark momentum distribution amplitude obtainable from the bound quark eigenmodes of the model with the assumption of a strong correlation between quark-antiquark momenta inside the decaying meson in its rest frame, we derive the partial decay width with correct kinematical factors from which we extract an expression for the pseudoscalar decay constants [ital f][sub [ital M
Self-consistent description of $\\Lambda$ hypernuclei in the quark-meson coupling model
Tsushima, K; Thomas, A W
1997-01-01
The quark-meson coupling model, which has been successfully used to describe the properties of both finite nuclei and infinite nuclear matter, is applied to a study of $\\Lambda$ hypernuclei. With the assumption that the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, a very weak spin-orbit force in the $\\Lambda$-nucleus interaction is achieved automatically. This can be interpreted as a direct consequence of the quark structure of the $\\Lambda$ hyperon. Possible implications and extensions of the present investigation are also discussed.
Where are the Low-mass Population III Stars?
Ishiyama, Tomoaki; Sudo, Kae; Yokoi, Shingo; Hasegawa, Kenji; Tominaga, Nozomu; Susa, Hajime
2016-07-01
We study the number and the distribution of low-mass Population III (Pop III) stars in the Milky Way. In our numerical model, hierarchical formation of dark matter minihalos and Milky-Way-sized halos are followed by a high-resolution cosmological simulation. We model the Pop III formation in H2 cooling minihalos without metal under UV radiation of the Lyman-Werner bands. Assuming a Kroupa initial mass function (IMF) from 0.15 to 1.0 M ⊙ for low-mass Pop III stars, as a working hypothesis, we try to constrain the theoretical models in reverse by current and future observations. We find that the survivors tend to concentrate on the center of halo and subhalos. We also evaluate the observability of Pop III survivors in the Milky Way and dwarf galaxies, and constraints on the number of Pop III survivors per minihalo. The higher latitude fields require lower sample sizes because of the high number density of stars in the galactic disk, the required sample sizes are comparable in the high- and middle-latitude fields by photometrically selecting low-metallicity stars with optimized narrow-band filters, and the required number of dwarf galaxies to find one Pop III survivor is less than 10 at <100 kpc for the tip of red giant stars. Provided that available observations have not detected any survivors, the formation models of low-mass Pop III stars with more than 10 stars per minihalo are already excluded. Furthermore, we discuss the way to constrain the IMF of Pop III stars at a high mass range of ≳10 M ⊙.
Light vector meson production in pp collisions at sqrt(s) = 7 TeV
DEFF Research Database (Denmark)
Collaboration, ALICE; Abelev, B.; Abrahantes Quintana, A.
2012-01-01
The ALICE experiment has measured low-mass dimuon production in pp collisions at \\sqrt{s} = 7 TeV in the dimuon rapidity region 2.5y\\eta^{}, \\phi) into muons and semi-leptonic decays of charmed mesons. The measured production cross sections for \\omega and \\phi are \\sigma_\\omega (1p_t5 GeV/c,2.5y4...
Optimisation of low-mass drift chambers for HADES
Energy Technology Data Exchange (ETDEWEB)
Garabatos, C.; Karig, W.; Muentz, C.; Steigerwald, A.; Stroth, J.; Wuestenfeld, J.; Zentek, A.; Bethge, K. [Frankfurt Univ. (Germany); Chernenko, S.; Fateev, O.; Glonti, L.; Smykov, L.; Zanewsky, Yu. [Joint Institute of Nuclear Research (JINR), 141980 Dubna (Russian Federation); Bokemeyer, H.; Koenig, W.; Stelzer, H.; Zumbruch, P. [Gesellschaft fuer Schwerionenforschung (GSI), 64291 Darmstadt (Germany)
1998-07-21
A set of low-mass drift chambers designed for the tracking of di-electrons in the HADES spectrometer is presented. Short radiation length is ensured by using a Helium-based gas mixture and aluminium cathode wires, whereas the acceptance is maximised by limiting the width of the side frames of the detectors. The measured performance of these devices, which improves with increasing concentration of quencher gas, is shown and discussed. Position resolutions down to 70 {mu}m have been obtained under stable operation. Long-term gain stability is also reported. (orig.)
Optimisation of low-mass drift chambers for HADES
Garabatos, C.; Karig, W.; Müntz, C.; Steigerwald, A.; Stroth, J.; Wüstenfeld, J.; Zentek, A.; Bethge, K.; Chernenko, S.; Fateev, O.; Glonti, L.; Smykov, L.; Zanewsky, Yu; Bokemeyer, H.; Koenig, W.; Stelzer, H.; Zumbruch, P.
A set of low-mass drift chambers designed for the tracking of di-electrons in the HADES spectrometer is presented. Short radiation length is ensured by using a Helium-based gas mixture and aluminium cathode wires, whereas the acceptance is maximised by limiting the width of the side frames of the detectors. The measured performance of these devices, which improves with increasing concentration of quencher gas, is shown and discussed. Position resolutions down to 70 μm have been obtained under stable operation. Long-term gain stability is also reported.
Compact Stars in low-mass X-ray binaries
Hossein, Sk. Monowar; Molla, Sajahan; Jafry, Md. Abdul Kayum; Kalam, Mehedi
2014-01-01
We propose a model for compact stars in low-mass X-ray binaries(LMXBs) namely KS 1731-260, EXO 1745-248 and 4U 1608-52. Here we investigate the physical phenomena of a compact star in the LMXBs. Using our model, we have calculated central density, surface density, mass(M) and red-shift for the above mentioned compact stars, which is very much consistent with the reported data. We also obtain the possible equation of state(EOS) of the stars which is physically acceptable.
A low mass pixel detector upgrade for CMS
Kaestli, Hans-Christian
2010-01-01
and commissioning of the present pixel detector, we intend to upgrade the whole pixel detector in 2015. The main focus is on lowering the material budget and adding more tracking points. We will present the design of a new low mass pixel system consisting of 4 barrel layers and 3 end cap disks on each side. The design comprises of thin detector modules and a lightweight mechanical support structure using CO2 cooling. In addition, large efforts have been made to move material from the services out of the tracking regi...
High and low mass Axion Haloscopes at UWA
McAllister, Ben T; Ivanov, Eugene N; Tobar, Michael E
2016-01-01
We consider the design of a haloscope experiment (ORGAN) to probe for axions at 26.6 GHz. The motivation for this search is to perform the first direct test of a result which claims a possible axion signal at this frequency. There are many technical issues and optimisations that must be considered in the design of a high mass axion haloscope. We discuss the current status of the ORGAN experiment, as well as its future. We also discuss low mass axion haloscopes employing lumped 3D LC resonators.
Formation of low-mass stars and brown dwarfs
Hennebelle, Patrick
2012-01-01
These lectures attempt to expose the most important ideas, which have been proposed to explain the formation of stars with particular emphasis on the formation of brown dwarfs and low-mass stars. We first describe the important physical processes which trigger the collapse of a self-gravitating piece of fluid and regulate the star formation rate in molecular clouds. Then we review the various theories which have been proposed along the years to explain the origin of the stellar initial mass f...
Young stars of low mass in the Gum nebula
Graham, J. A.; Heyer, Mark H.
1989-01-01
Observations are presented for four recently formed stars in the vicinity of the Gum nebula which are heavily obscured by surrounding dust and are associated with small reflection nebulae. HH46 is the only currently active star of the sample, and it is found to have a spectral type in the range of late G-early K, with superimposed emission lines of H-alpha, Ca II, Fe I, Fe II, and weak He I at near zero velocities. It is suggested that the observed scenario of low-mass stars in an older massive star environment may be analogous to the circumstances surrounding the birth of the sun.
Grube, Boris
2015-01-01
The COmmon Muon and Proton Apparatus for Structure and Spectroscopy (COMPASS) is a multi-purpose fixed-target experiment at the CERN Super Proton Synchrotron (SPS) aimed at studying the structure and spectrum of hadrons. The two-stage spectrometer has a good acceptance for charged as well as neutral particles over a wide kinematic range and thus allows to access a wide range of reactions. Light mesons are studied with negative (mostly $\\pi^-$) and positive ($p$, $\\pi^+$) hadron beams with a momentum of 190 GeV/$c$. The spectrum of light mesons is investigated in various final states produced in diffractive dissociation reactions at squared four-momentum transfers to the target between 0.1 and 1.0 $(\\text{GeV}/c)^2$. The flagship channel is the $\\pi^-\\pi^+\\pi^-$ final state, for which COMPASS has recorded the currently largest data sample. These data not only allow to measure the properties of known resonances with high precision, but also to search for new states. Among these is a new resonance-like signal, t...
Energy Technology Data Exchange (ETDEWEB)
Crowe, K.M.
1992-01-01
The activities of this group are primarily concerned with experiments using the Crystal Barrel Detector. This detector is installed and operating at the Low Energy Antiproton Ring (LEAR) at CERN. QCD, the modem theory of the strong interaction, is reasonably well understood at high energies, but unfortunately, low-energy QCD is still not well understood, and is far from being adequately tested. The Crystal Barrel experiments are designed to provide some of the tests. The basic line of research involves meson spectroscopy, analyses bearing on the quark and/or gluon content of nuclear states, and the exploration of mechanisms and rules which govern p[bar p] annihilation dynamics. The Crystal Barrel Detector detects and identifies charged and neutral particles with a geometric acceptance close to 100%. The principal component of the detector is an array of 1,380 CsI(TI) crystals. These crystals surround a Jet Drift Chamber (JDC), located in a 1.5 Tesla magnetic field, which measures the momentum and dE/dx of charged particles. One of the very interesting physics goals of the detector is a search for exotic mesonic states -- glueballs and hybrids. Annihilation at rest will be studied with both liquid and gaseous hydrogen targets. The gaseous target offers the possibility of triggering on atomic L-shell X rays so that specific initial angular momentum states can be studied.These topics as well as other related topics are discussed in this report.
Energy Technology Data Exchange (ETDEWEB)
Crowe, K.M.
1992-12-01
The activities of this group are primarily concerned with experiments using the Crystal Barrel Detector. This detector is installed and operating at the Low Energy Antiproton Ring (LEAR) at CERN. QCD, the modem theory of the strong interaction, is reasonably well understood at high energies, but unfortunately, low-energy QCD is still not well understood, and is far from being adequately tested. The Crystal Barrel experiments are designed to provide some of the tests. The basic line of research involves meson spectroscopy, analyses bearing on the quark and/or gluon content of nuclear states, and the exploration of mechanisms and rules which govern p{bar p} annihilation dynamics. The Crystal Barrel Detector detects and identifies charged and neutral particles with a geometric acceptance close to 100%. The principal component of the detector is an array of 1,380 CsI(TI) crystals. These crystals surround a Jet Drift Chamber (JDC), located in a 1.5 Tesla magnetic field, which measures the momentum and dE/dx of charged particles. One of the very interesting physics goals of the detector is a search for exotic mesonic states -- glueballs and hybrids. Annihilation at rest will be studied with both liquid and gaseous hydrogen targets. The gaseous target offers the possibility of triggering on atomic L-shell X rays so that specific initial angular momentum states can be studied.These topics as well as other related topics are discussed in this report.
Directory of Open Access Journals (Sweden)
Grube Boris
2016-01-01
Full Text Available The goal of the COMPASS experiment at CERN is to study the structure and dynamics of hadrons. The two-stage spectrometer used by the experiment has large acceptance and covers a wide kinematic range for charged as well as neutral particles and can therefore measure a wide range of reactions. The spectroscopy of light mesons is performed with negative (mostly π− and positive (p, π+ hadron beams with a momentum of 190 GeV/c. The light-meson spectrum is measured in different final states produced in diffractive dissociation reactions with squared four-momentum transfer t to the target between 0.1 and 1.0 (GeV=c2. The flagship channel is the π−π−π+ final state, for which COMPASS has recorded the currently world’s largest data sample. These data not only allow to measure the properties of known resonances with high precision, but also to observe new states. Among these is a new axial-vector signal, the a1(1420, with unusual properties. Novel analysis techniques have been developed to extract also the amplitude of the π−π+ subsystem as a function of 3π mass from the data. The findings are confirmed by the analysis of the π−π0π0 final state.
Grube, Boris
2016-11-29
The goal of the COMPASS experiment at CERN is to study the structure and dynamics of hadrons. The two-stage spectrometer used by the experiment has large acceptance and covers a wide kinematic range for charged as well as neutral particles and can therefore measure a wide range of reactions. The spectroscopy of light mesons is performed with negative (mostly $\\pi^-$) and positive ($p$, $\\pi^+$) hadron beams with a momentum of 190 GeV/$c$. The light-meson spectrum is measured in different final states produced in diffractive dissociation reactions with squared four-momentum transfer $t$ to the target between 0.1 and 1.0 $(\\text{GeV}/c)^2$. The flagship channel is the $\\pi^-\\pi^-\\pi^+$ final state, for which COMPASS has recorded the currently world's largest data sample. These data not only allow to measure the properties of known resonances with high precision, but also to observe new states. Among these is a new axial-vector signal, the $a_1(1420)$, with unusual properties. Novel analysis techniques have been...
Grube, Boris
2016-11-01
The goal of the COMPASS experiment at CERN is to study the structure and dynamics of hadrons. The two-stage spectrometer used by the experiment has large acceptance and covers a wide kinematic range for charged as well as neutral particles and can therefore measure a wide range of reactions. The spectroscopy of light mesons is performed with negative (mostly π-) and positive (p, π+) hadron beams with a momentum of 190 GeV/c. The light-meson spectrum is measured in different final states produced in diffractive dissociation reactions with squared four-momentum transfer t to the target between 0.1 and 1.0 (GeV=c)2. The flagship channel is the π-π-π+ final state, for which COMPASS has recorded the currently world's largest data sample. These data not only allow to measure the properties of known resonances with high precision, but also to observe new states. Among these is a new axial-vector signal, the a1(1420), with unusual properties. Novel analysis techniques have been developed to extract also the amplitude of the π-π+ subsystem as a function of 3π mass from the data. The findings are confirmed by the analysis of the π-π0π0 final state.
Haas, Florian
2009-01-01
QCD predicts four quark states or gluonic excitations like hybrids or glueballs to contribute to the meson spectrum in addition to $q\\overline{q}$ pair configurations. The most promising way to identify such states is the search for $J^{PC}$ quantum number combinations which are forbidden in the constituent quark model. The fixed target COMPASS experiment at CERN offers the opportunity to search for such states in the light quark sector with an unprecedented statistics. Diffractive reactions of 190 GeV/c pions on a lead target were studied by COMPASS during a pilot run in 2004. A Partial Wave Analysis (PWA) of the $\\pi^{−}\\pi^{−}\\pi^{+}$ final state with 42 waves including acceptance corrections through a phase-space Monte Carlo simulation of the spectrometer was performed. The exotic $\\pi_{1}$(1600) meson with quantum numbers $J^{PC}= 1^{−+}$ has been clearly established in the rho-pi decay channel with a mass of 1660 $\\pm$ 10(stat) MeV/c$^{2}$ and a width of 269 $\\pm$ 21(stat) MeV/c$^{2}$. The final s...
INFLUENCE OF THE DELTA-DELTA-MESON COUPLING ON NUCLEON AND DELTA PROPERTIES IN NUCLEAR-MATTER
DEJONG, F; MALFLIET, R
1994-01-01
We introduce a scalar and a vector DELTADELTA-meson vertex in the relativistic Dirac-Brueckner model for nuclear matter and investigate the consequences. We find small effects on the effective nucleon properties. The effects in the DELTA sector are more profound, although the DELTA is still effectiv
Egorov, A I; Sushkov, Sergey V
2016-01-01
In 1921 Bach and Weyl derived the method of superposition to construct new axially symmetric vacuum solutions of General Relativity. In this paper we extend the Bach-Weyl approach to non-vacuum configurations with massless scalar fields. Considering a phantom scalar field with the negative kinetic energy, we construct a multi-wormhole solution describing an axially symmetric superposition of $N$ wormholes. The solution found is static, everywhere regular and has no event horizons. These features drastically tell the multi-wormhole configuration from other axially symmetric vacuum solutions which inevitably contain gravitationally inert singular structures, such as `struts' and `membranes', that keep the two bodies apart making a stable configuration. However, the multi-wormholes are static without any singular struts. Instead, the stationarity of the multi-wormhole configuration is provided by the phantom scalar field with the negative kinetic energy. Anther unusual property is that the multi-wormhole spaceti...
Bent by baryons: the low mass galaxy-halo relation
Sawala, Till; Fattahi, Azadeh; Navarro, Julio F; Bower, Richard G; Crain, Robert A; Vecchia, Claudio Dalla; Furlong, Michelle; Jenkins, Adrian; McCarthy, Ian G; Qu, Yan; Schaller, Matthieu; Schaye, Joop; Theuns, Tom
2014-01-01
The relation between galaxies and dark matter halos is of vital importance for evaluating theoretical predictions of structure formation and galaxy formation physics. We show that the widely used method of abundance matching based on dark matter only simulations fails at the low mass end because two of its underlying assumptions are broken: only a small fraction of low mass (below 10^9.5 solar masses) halos host a visible galaxy, and halos grow at a lower rate due to the effect of baryons. In this regime, reliance on dark matter only simulations for abundance matching is neither accurate nor self-consistent. We find that the reported discrepancy between observational estimates of the halo masses of dwarf galaxies and the values predicted by abundance matching does not point to a failure of LCDM, but simply to a failure to account for baryonic effects. Our results also imply that the Local Group contains only a few hundred observable galaxies in contrast with the thousands of faint dwarfs that abundance matchi...
SETI Observations of Low Mass Stars at the SETI Institute
Harp, Gerald R.
2017-05-01
Are planets orbiting low-mass stars suitable for the development of life? Observations in the near future, including radio, will help to assess whether atmospheres do persist over long timescales for planets orbiting nearby M dwarfs, and clarify the nature of the radiation that penetrates to the surface of these planets. These are important ingredients for assessing planetary habitability, yet the question of habitability can be answered only with the positive measurement of an unambiguous biosignature. Radio and optical SETI observations capable of detecting technological activities of intelligent inhabitants could provide the most compelling evidence for the habitability of exoplanets orbiting M dwarfs. In this presentation we shall consider what information can be gleaned from our observations so far. The SETI Institute is currently undertaking a large survey of 20,000 low mass stars that is now about 30% complete. The frequency coverage on each star is about 450 MHz bandwidth (per star) over a range of selected frequencies from 1-10 GHz. From these observations we derive quantitative results relating to the probability that M dwarfs are actually inhabited.
Low-mass stars: Open problems all along their evolution
Directory of Open Access Journals (Sweden)
Heners N.
2013-03-01
Full Text Available Although low-mass stars have a comparatively simple structure, current stellar models are far from reproducing them accurately. In light of the observational progress, in particular of asteroseismology, the deficits of the theory of stellar structure and evolution become increasingly evident, and can no longer be hidden under the carpet of observational errors. In my brief review I will discuss a number of obvious problems of the models, which are mainly – and not surprisingly so – connected with convective and other mixing processes. They begin already on the pre-main sequence and continue throughout the complete evolution. In addition to the deficits in the treatment of physical processes I will also address our difficulties in obtaining completely satisfying agreement between different numerical codes. It will be shown that this concerns already the main sequence evolution of low-mass stars without a convective core. Keeping this in mind, it is no surprise that models for stars on the Asymptotic Giant Branch differ widely.
Deep, Low Mass Ratio Overcontact Binaries. II. IK Persei
Zhu, L.-Y.; Qian, S.-B.; Soonthornthum, B.; Yang, Y.-G.
2005-06-01
BV photometric light curves of the eclipsing binary IK Per were obtained during three nights in 2002 December. The photometric elements were computed using the Wilson-Devinney code. The results reveal that IK Per is an A-type overcontact binary system with a low mass ratio of q=0.17 and a large degree of overcontact of 60%. The asymmetry of the light curves (i.e., the O'Connell effect) is explained by spot models. The observed long-term orbital period decrease [dP/dt=-(2.5+/-0.09)×10-7 days yr-1] is probably influenced by the presence of a third body in the system. The low mass ratio, high degree of overcontact, and secular orbital decrease all indicate that the situation of IK Per resembles those of FG Hya, GR Vir, and AW UMa. Because of the decrease of their orbital periods, the shrinking of the inner and outer critical Roche lobes will lead the common envelopes to overlap more, and finally the systems will evolve into single rapid-rotation stars.
Where are the low mass Pop III stars ?
Ishiyama, Tomoaki; Yokoi, Shingo; Hasegawa, Kenji; Tominaga, Nozomu; Susa, Hajime
2016-01-01
We study the number and the distribution of low mass Pop III stars in the Milky Way. In our numerical model, hierarchical formation of dark matter minihalos and Milky Way sized halos are followed by a high resolution cosmological simulation, which can predict the spatial distribution of Pop III survivors in the Milky Way. We model the Pop III formation in H$_2$ cooling minihalos without metal under UV radiation of the Lyman-Werner bands. Assuming a Kroupa IMF from 0.15 to 1.0 Msun for low mass Pop III stars, as a working hypothesis, we try to constrain the theoretical models in reverse by current and future observations. We find that the number of survivors is proportional to the halo mass and the number of Pop III per minihalo. Thus, the distribution of survivors reflects that of dark matter and the survivors tend to concentrate on the center of halo and subhalos. We also evaluate the observability of Pop III survivors in the Milky Way and dwarf galaxies, and constraints on the number of Pop III survivors pe...
Fast migration of low-mass planets in radiative discs
Pierens, Arnaud
2015-01-01
Low-mass planets are known to undergo Type I migration and this process must have played a key role during the evolution of planetary systems. Analytical formulae for the disc torque have been derived assuming that the planet evolves on a fixed circular orbit. However, recent work has shown that in isothermal discs, a migrating protoplanet may also experience dynamical corotation torques that scale with the planet drift rate. The aim of this study is to examine whether dynamical corotation torques can also affect the migration of low-mass planets in non-isothermal discs. We performed 2D radiative hydrodynamical simulations to examine the orbital evolution outcome of migrating protoplanets as a function of disc mass. We find that a protoplanet can enter a fast migration regime when it migrates in the direction set by the entropy-related horseshoe drag and when the Toomre stability parameter is less than a threshold value below which the horseshoe region contracts into a tadpole-like region. In that case, an un...
Powerful Winds from Low-Mass Stars: V374 Peg
Vidotto, A A; Opher, M; Donati, J -F; Gombosi, T I
2010-01-01
The rapid rotation (P=0.44 d) of the M dwarf V374Peg (M4) along with its intense magnetic field point toward magneto-centrifugal acceleration of a coronal wind. In this work, we investigate the structure of the wind of V374Peg by means of 3D magnetohydrodynamical (MHD) numerical simulations. For the first time, an observationally derived surface magnetic field map is implemented in MHD models of stellar winds for a low mass star. We show that the wind of V374Peg deviates greatly from a low-velocity, low-mass-loss rate solar-type wind. We find general scaling relations for the terminal velocities, mass-loss rates, and spin-down times of highly magnetized M dwarfs. In particular, for V374Peg, our models show that terminal velocities across a range of stellar latitudes reach ~(1500-2300) n_{12}^{-1/2} km/s, where n_{12} is the coronal wind base density in units of 10^{12} cm^{-3}, while the mass-loss rates are about 4 x 10^{-10} n_{12}^{1/2} Msun/yr. We also evaluate the angular-momentum loss of V374Peg, which p...
Modeling water emission from low-mass protostellar envelopes
van Kempen, T A; Van Dishoeck, E F; Hogerheijde, M R; Jørgensen, J K
2008-01-01
Within low-mass star formation, water vapor plays a key role in the chemistry and energy balance of the circumstellar material. The Herschel Space Observatory will open up the possibility to observe water lines originating from a wide range of excitation energies.Our aim is to simulate the emission of rotational water lines from envelopes characteristic of embedded low-mass protostars. A large number of parameters that influence the water line emission are explored: luminosity, density,density slope and water abundances.Both dust and water emission are modelled using full radiative transfer in spherical symmetry. The temperature profile is calculated for a given density profile. The H2O level populations and emission profiles are in turn computed with a non-LTE line code. The results are analyzed to determine the diagnostic value of different lines, and are compared with existing observations. Lines can be categorized in: (i) optically thick lines, including ground-state lines, mostly sensitive to the cold ou...
A spectral differential characterization of low-mass companions
Directory of Open Access Journals (Sweden)
Lyubchik Y.
2013-04-01
Full Text Available We present a new approach with which the dynamical mass of low-mass companions around cool stars can be found. In order to discover companions to late-type stars the stellar spectrum is removed. For this we substract two spectra obtained at different orbital phases from each other in order to discover the companion spectrum in the difference spectrum in which the companion lines appear twice (positive and negative signal. The resulting radial velocity difference of these two signals provides the true mass of the companion. For our test case GJ1046, an M2V dwarf with a low-mass companion that most likely is a brown dwarf we select the CO line region in the K-band. We show that the dynamical mass of a faint companion to an M dwarf can be determined using our spectral differential technique. Only if the companion rotates rapidly and has a small radial velocity amplitude due to a high mass, does blending occur for all lines so that our approach fails. In addition to determining the companion mass, we restore the single companion spectrum from the difference spectrum using singular value decomposition.
Formation of low-mass stars and brown dwarfs
Hennebelle, Patrick
2012-01-01
These lectures attempt to expose the most important ideas, which have been proposed to explain the formation of stars with particular emphasis on the formation of brown dwarfs and low-mass stars. We first describe the important physical processes which trigger the collapse of a self-gravitating piece of fluid and regulate the star formation rate in molecular clouds. Then we review the various theories which have been proposed along the years to explain the origin of the stellar initial mass function paying particular attention to four models, namely the competitive accretion and the theories based respectively on stopped accretion, MHD shocks and turbulent dispersion. As it is yet unsettled whether the brown dwarfs form as low-mass stars, we present the theory of brown dwarfs based on disk fragmentation stressing all the uncertainties due to the radiative feedback and magnetic field. Finally, we describe the results of large scale simulations performed to explain the collapse and fragmentation of molecular cl...
Formation of Low-Mass Stars and Brown Dwarfs
Hennebelle, P.
2012-11-01
These lectures attempt to expose the most important ideas, which have been proposed to explain the formation of stars with particular emphasis on the formation of brown dwarfs and low-mass stars. We first describe the important physical processes which trigger the collapse of a self-gravitating piece of fluid and regulate the star formation rate in molecular clouds. Then we review the various theories which have been proposed along the years to explain the origin of the stellar initial mass function paying particular attention to four models, namely the competitive accretion and the theories based respectively on stopped accretion, MHD shocks and turbulent dispersion. As it is yet unsettled whether the brown dwarfs form as low-mass stars, we present the theory of brown dwarfs based on disk fragmentation stressing all the uncertainties due to the radiative feedback and magnetic field. Finally, we describe the results of large scale simulations performed to explain the collapse and fragmentation of molecular clouds.
Rejon-Barrera, Fernando
2015-01-01
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
Energy Technology Data Exchange (ETDEWEB)
Rejon-Barrera, Fernando [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands); Robbins, Daniel [Department of Physics, Texas A& M University,TAMU 4242, College Station, TX 77843 (United States)
2016-01-22
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
Pseudovector mesons, hybrids and glueballs
Burakovsky, L; Burakovsky, Leonid; Page, Philip R.
2000-01-01
We consider glueball- (hybrid) meson mixing for the low-lying four pseudovector states. The h_1'(1380) decays dominantly to K*K with some presence in rho pi and omega eta. The newly observed h_1(1600) has a D- to S-wave width ratio to omega eta which does not enable differentiation between a conventional and hybrid meson interpretation. We predict the decay pattern of the isopartner conventional or hybrid meson b_1(1650). A notably narrow s sbar partner h_1'(1810) is predicted.
Meson Production Experiments at CLAS
Energy Technology Data Exchange (ETDEWEB)
S. Strauch
2006-11-01
Electromagnetic meson production is an important tool in the investigation of the structure of the nucleon. Consequently, a series of meson photo- and electroproduction experiments have been performed with the CLAS detector at Jefferson Lab. In this overview I will report on measurements of cross sections, as well as recent and upcoming measurements of single- and double-polarization observables in meson photoproduction. The data will greatly constrain partial-wave analyses and reduce model-dependent uncertainties in the extraction of nucleon resonance properties.
Ground State Mass Spectrum for Scalar Diquarks with Bethe-Salpeter Equation
Institute of Scientific and Technical Information of China (English)
WANG Zhi-Gang; WAN Shao-Long; YANG Wei-Min
2007-01-01
In this article,we study the structures of the pseudoscalar mesons π,K and the scalar diquarks Ua,Da,Sa in the framework of the coupled rainbow Schwinger-Dyson equation and ladder Bethe-Salpeter equation with the confining effective potential.The u,d,s quarks have small current masses,and the renormalization is very large,the mass poles in the timelike region are absent which implements confinement naturally.The Bethe-Salpeter wavefunctions of the pseudoscalar mesons π,K,and the scalar diquarks Ua,Da,Sa have the same type (Gaussian type) momentum dependence,center around zero momentum and extend to the energy scale about q2 = 1 GeV2,which happens to be the energy scale for the chiral symmetry breaking,the strong interactions in the infrared region result in bound (or quasi-bound) states.The numerical results for the masses and decay constants of the π and K mesons can reproduce the experimental values,and the ground state masses of the scalar diquarks Ua,Da,Sa are consistent with the existing theoretical calculations.We suggest a new Lagrangian which may explain the uncertainty of the masses of the scalar diquarks.
Indian Academy of Sciences (India)
Gy Wolf
2006-04-01
One consequence of the chiral restoration is the mixing of parity partners. We look for a possible signature of the mixing of vector and axial vector mesons in heavy-ion collisions. We suggest an experimental method for its observation. The dynamical evolution of the heavy-ion collision is described by a transport equation of QMD-type evolving nucleons, * and resonances, ’s and $\\sum$ baryons, and furthermore, ’s, ’s ’s ’s ’s and kaons with their isospin degrees of freedom. The input cross-sections and resonance parameters of the model are fitted to the available nucleon–nucleon and pion–nucleon cross-sections.
Production of Pseudoscalar Mesons
Briscoe, W J; Strakovsky, I I; Workman, R L
2003-01-01
Experiments that study the hadronic and electromagnetic production of the pseudoscalar mesons -- pions, etas and kaons, contribute to our knowledge of the properties of baryon and hyperon resonances. Fixed-target programs at hadronic facilities such as BNL-AGS have been phased out. However, the availability of modern experimental facilities with pseudo-monochromatic or tagged medium-energy photon beams at GRAAL, SPring-8, Bonn, Mainz, and Jefferson Lab, together with LEGS, Max-Lab, and HIGS at lower energies, are beginning to produce high-quality results. These new data have smaller statistical uncertainties and better understood systematic uncertainties, than those obtained at the older bremsstrahlung facilities, for measurements of differential and integrated cross sections, as well as polarization and asymmetry. Experimental results are compared with the predictions of QCD-based approaches, such as the lattice-gauge calculations of baryon properties, and Chiral Perturbation Theory applied to threshold phot...
Photoproduction of Hybrid Mesons
Barnes, T
1998-01-01
In this contribution I discuss prospects for photoproducing hybrid mesons at CEBAF, based on recent model results and experimental indications of possible hybrids. One excellent opportunity appears to be a search for the I=1, JPC=2+-, neutral "(b2)o" hybrid in (a2 pi)o through diffractive photoproduction. Other notable possibilities accessible through pi+ or pio exchange photoproduction are I=1, JPC=1-+, charged "pi1+" in f1 pi+, (b1 pi)+ and (rho pi)+; piJ(1770)+ in f2 pi+ and (b1 pi)+; pi(1800)+ in f0 pi+, f2 pi+, omega rho+ and (rho pi)+; a1 in f1 pi+ and f2 pi+; and omega in (rho pi)o, omega eta and (K1 K)o.
The sigma meson from QCD sum rules for large-$N_c$ Regge spectra
Afonin, S S
2016-01-01
The QCD sum rules in the large-$N_c$ limit for the light non-strange vector, axial-vector and scalar mesons are considered assuming a string-like linear spectrum for the radially excited states. We propose a improved method for a combined analysis of these channels that gives a reasonable description of the observed spectrum. Fixing the universal slope of radial trajectories and the quark condensate from the vector channels, we argue that, in contrast to a common belief, the prediction of a light quark-antiquark scalar state compatible with $f_0(500)$ can be quite natural within the planar QCD sum rules.
Skyrmions with vector mesons revisited
Oh, Yongseok
2014-01-01
In order to develop a model that can describe both a single baryon and multi-baryon systems on the same footing, we re-investigate the Skyrme model in a chiral Lagrangian derived from the hidden local symmetry (HLS) up to $O(p^4)$ including the homogeneous Wess-Zumino terms. We use the master formulas that connect the parameters of the HLS Lagrangian and a class of holographic QCD models, which provides a controllable way to determine the low-energy constants of the Lagrangian once the pion decay constant and the vector meson mass are given. Therefore, this model allows us to study the role of vector mesons in the skyrmion structure. We find that the $\\rho$ and $\\omega$ vector mesons have different roles in the skyrmion structure and that the $\\omega$ meson has an important role in the properties of the nucleon.
Exploring Low-Mass Dark Matter with CRESST
Strauss, R.; Angloher, G.; Bento, A.; Bucci, C.; Canonica, L.; Defay, X.; Erb, A.; Feilitzsch, F. v.; Ferreiro Iachellini, N.; Gorla, P.; Gütlein, A.; Hauff, D.; Jochum, J.; Kiefer, M.; Kluck, H.; Kraus, H.; Lanfranchi, J. C.; Loebell, J.; Münster, A.; Pagliarone, C.; Petricca, F.; Potzel, W.; Pröbst, F.; Reindl, F.; Schäffner, K.; Schieck, J.; Schönert, S.; Seidel, W.; Stodolsky, L.; Strandhagen, C.; Tanzke, A.; Trinh Thi, H. H.; Türkoglu, C.; Uffinger, M.; Ulrich, A.; Usherov, I.; Wawoczny, S.; Willers, M.; Wüstrich, M.; Zöller, A.
2016-08-01
The CRESST-II (Cryogenic Rare Event Search with Superconducting Thermometers) experiment, whose second phase has been successfully finished in summer 2015, aims at the direct detection of dark matter particles. The intrinsic radiopurity of CaWO_4 crystals, the capability to reject recoil events from alpha-surface contamination, and the energy threshold were significantly improved compared to previous runs of the experiment. A moderate exposure of 29 kg-days acquired by one ˜ 250 g CaWO_4 detector provides competitive limits on the spin-independent dark matter particle-nucleon cross section and probes a new region of parameter space for dark matter particle masses below 3 GeV/c^2. The potential for low-mass dark matter particle search can be further exploited by a new detector design planned for CRESST-III. We describe the experimental strategy for the near future and give projections for the sensitivity.
Feedback in low-mass galaxies in the early Universe.
Erb, Dawn K
2015-07-09
The formation, evolution and death of massive stars release large quantities of energy and momentum into the gas surrounding the sites of star formation. This process, generically termed 'feedback', inhibits further star formation either by removing gas from the galaxy, or by heating it to temperatures that are too high to form new stars. Observations reveal feedback in the form of galactic-scale outflows of gas in galaxies with high rates of star formation, especially in the early Universe. Feedback in faint, low-mass galaxies probably facilitated the escape of ionizing radiation from galaxies when the Universe was about 500 million years old, so that the hydrogen between galaxies changed from neutral to ionized-the last major phase transition in the Universe.
Star Formation Triggered by Low-Mass Clump Collisions
Kitsionas, Spyridon; Whitworth, Anthony P.
We investigate by means of high-resolution numerical simulations the phenomenology of star formation triggered by low-velocity collisions between low-mass molecular clumps. The simulations are performed using an SPH code which satisfies the Jeans condition by invoking On-the-Fly Particle Splitting (Kitsionas & Whitworth 2002). The efficiency of star formation appears to increase with increasing clump mass and/or decreasing impact parameter b and/or increasing clump velocity. For bcompressed layers which fragment into filaments that break up into cores. Protostellar objects then condense out of the cores and accrete from them. The resulting accretion rates are comparable to those of Class 0 objects. The densities in the filaments are sufficient that they could be mapped in ammonia or CS line radiation in nearby star formation regions. The phenomenology of star formation observed in our simulations compares rather well with the observed filamentary distribution of young stars in Taurus (Hartmann 2002).
Optimizing Cryogenic Detectors for Low-Mass WIMP Searches
Arnaud, Q.; Billard, J.; Juillard, A.
2016-07-01
This paper describes the methodology and results from a study dedicated to the optimization of cryogenic detectors for low-mass WIMP searches. Considering a data-driven background model from the EDELWEISS-III experiment, and two analysis methods, namely profile likelihood and boosted decision tree, we indentify the main experimental constraints and performances that have to be improved. We found that there is a clear difference in how to optimize the detector setup whether focusing on WIMPs with masses below 5 GeV or above. Finally, in the case of a hundred-kg scale experiment, we discuss the requirements to probe most of the parameter space region delimited by the ultimate neutrino bound below 6 GeV.
Low Mass Printable Devices for Energy Capture, Storage, and Use
Frazier, Donald O.; Singer, Christopher E.; Rogers, Jan R.; Schramm, Harry F.; Fabisinski, Leo L.; Lowenthal, Mark; Ray, William J.; Fuller, Kirk A.
2010-01-01
The energy-efficient, environmentally friendly technology that will be presented is the result of a Space Act Agreement between NthDegree Technologies Worldwide, Inc., and the National Aeronautics and Space Administration's (NASA's) Marshall Space Flight Center (MSFC). The work combines semiconductor and printing technologies to advance lightweight electronic and photonic devices having excellent potential for commercial and exploration applications. Device development involves three projects that relate to energy generation and consumption: (1) a low-mass efficient (low power, low heat emission) micro light-emitting diode (LED) area lighting device; (2) a low-mass omni-directional efficient photovoltaic (PV) device with significantly improved energy capture; and (3) a new approach to building super-capacitors. These three technologies, energy capture, storage, and usage (e.g., lighting), represent a systematic approach for building efficient local micro-grids that are commercially feasible; furthermore, these same technologies, appropriately replacing lighting with lightweight power generation, will be useful for enabling inner planetary missions using smaller launch vehicles and to facilitate surface operations during lunar and planetary surface missions. The PV device model is a two sphere, light trapped sheet approximately 2-mm thick. The model suggests a significant improvement over current thin film systems. For lighting applications, all three technology components are printable in-line by printing sequential layers on a standard screen or flexographic direct impact press using the three-dimensional printing technique (3DFM) patented by NthDegree. One primary contribution to this work in the near term by the MSFC is to test the robustness of prototype devices in the harsh environments that prevail in space and on the lunar surface. It is anticipated that this composite device, of which the lighting component has passed off-gassing testing, will function
Fast migration of low-mass planets in radiative discs
Pierens, A.
2015-12-01
Low-mass planets are known to undergo Type I migration and this process must have played a key role during the evolution of planetary systems. Analytical formulae for the disc torque have been derived assuming that the planet evolves on a fixed circular orbit. However, recent work has shown that in isothermal discs, a migrating protoplanet may also experience dynamical corotation torques that scale with the planet drift rate. The aim of this study is to examine whether dynamical corotation torques can also affect the migration of low-mass planets in non-isothermal discs. We performed 2D radiative hydrodynamical simulations to examine the orbital evolution outcome of migrating protoplanets as a function of disc mass. We find that a protoplanet can enter a fast migration regime when it migrates in the direction set by the entropy-related horseshoe drag and when the Toomre stability parameter is less than a threshold value below which the horseshoe region contracts into a tadpole-like region. In that case, an underdense trapped region appears near the planet, with an entropy excess compared to the ambient disc. If the viscosity and thermal diffusivity are small enough so that the entropy excess is conserved during migration, the planet then experiences strong corotation torques arising from the material flowing across the planet orbit. During fast migration, we observe that a protoplanet can pass through the zero-torque line predicted by static torques. We also find that fast migration may help in disrupting the mean-motion resonances that are formed by convergent migration of embryos.
Leading logarithms in N-flavour mesonic Chiral Perturbation Theory
Energy Technology Data Exchange (ETDEWEB)
Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, S 223 62 Lund (Sweden); Kampf, Karol, E-mail: karol.kampf@mff.cuni.cz [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, CZ-18000 Prague (Czech Republic); Lanz, Stefan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, S 223 62 Lund (Sweden); Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern (Switzerland)
2013-08-01
We extend earlier work on leading logarithms in the massive nonlinear O(n) sigma model to the case of SU(N)×SU(N)/SU(N) which coincides with mesonic Chiral Perturbation Theory for N flavours of light quarks. We discuss the leading logarithms for the mass and decay constant to six loops and for the vacuum expectation value 〈q{sup ¯}q〉 to seven loops. For dynamical quantities the expressions grow extremely large much faster such that we only quote the leading logarithms to five loops for the vector and scalar form factor and for meson–meson scattering. The last quantity we consider is the vector–vector to meson–meson amplitude where we quote results up to four loops for a subset of quantities, in particular for the pion polarizabilities. As a side result we provide an elementary proof that the factors of N appearing at each loop order are odd or even depending on the order and the remaining traces over external flavours.
Heavy vector and axial-vector mesons in hot and dense asymmetric strange hadronic matter
Kumar, Arvind; Chhabra, Rahul
2015-09-01
We calculate the effects of finite density and temperature of isospin asymmetric strange hadronic matter, for different strangeness fractions, on the in-medium properties of vector (D*,Ds*,B*,Bs*) and axial-vector (D1,D1 s,B1,B1 s) mesons, using the chiral hadronic SU(3) model and QCD sum rules. We focus on the evaluation of in-medium mass-shift and shift in decay constant of above vector and axial-vector mesons. In the quantum chromodynamics sum rule approach, the properties, e.g., the masses and decay constants of vector and axial-vector mesons are written in terms of quark and gluon condensates. These quark and gluon condensates are evaluated in the present work within the chiral SU(3) model, through the medium modification of scalar-isoscalar fields σ and ζ , the scalar-isovector field δ , and the scalar dilaton field χ , in the strange hadronic medium which includes both nucleons as well as hyperons. As we shall see in detail, the masses and decay constants of heavy vector and axial-vector mesons are affected significantly from isospin asymmetry and the strangeness fraction of the medium, and these modifications may influence the experimental observables produced in heavy-ion collision experiments. The results of present investigations of in-medium properties of vector and axial-vector mesons at finite density and temperature of strange hadronic medium may be helpful for understanding the experimental data from heavy-ion collision experiments in particular for the compressed baryonic matter (CBM) experiment of the FAIR facility at GSI, Germany.
Leptonic decay of light vector mesons in an independent quark model
Energy Technology Data Exchange (ETDEWEB)
Barik, N. (Department of Physics, Utkal University, Bhubaneswar-751004 (India)); Dash, P.C. (Department of Physics, P. N. College, Khurda, Orissa (India)); Panda, A.R. (Department of Physics, Kendrapara College, Kendrapara, Orissa (India))
1993-02-01
Leptonic decay widths of light vector mesons are calculated in a framework based on the independent quark model with a scalar-vector harmonic potential. Assuming a strong correlation to exist between the quark-antiquark momenta inside the meson, so as to make their total momentum identically zero in the center-of-mass frame of the meson, we extract the quark and antiquark momentum distribution amplitudes from the bound quark eigenmode. Using the model parameters determined from earlier studies, we arrive at the leptonic decay widths of ([rho],[omega],[phi]) as (6.26 keV, 0.67 keV, 1.58 keV) which are in very good agreement with the respective experimental data (6.77[plus minus]0.32 keV, 0.6[plus minus]0.02 keV, 1.37[plus minus]0.05 keV).
Chiral symmetry restoration in σ-meson production in hadronic processes
Directory of Open Access Journals (Sweden)
Kukulin V.I.
2014-06-01
Full Text Available Some puzzles about the nature and properties of the lightest scalar meson, σ or f0(500, are analyzed in the paper. We studied the σ-meson production both in N + N, N + d, etc., collisions and also in J/ψ, ψ(2S, ψ(3S, Υ(2S, etc., two-pion decays. The fundamental distinctions between the basic σ-meson parameters found in various hadronic processes can be explained most naturally by the chiral symmetry restoration in intermediate excited hadronic resonances. In the present paper we discuss some important aspects of chiral symmetry restoration in hadronic processes with interrelation to the basic features of QCD.
Relativistic nuclear theory—nucleons and mesons: origin, current status, and trends
Savushkin, L. N.
2015-11-01
The nuclear shell model (NSM) is a fundamental model of nuclear theory. At the initial stage, the NSM was developed on the basis of the Schrödinger equation, in particular because it was not clear which Dirac matrices should be associated with various components of the (relativistic) shell model potential. In the early 1970s, the relativistic version of the NSM with meson fields as its main components was developed on the basis of the Dirac equation. The relativistic nuclear shell model (RNSM) includes meson fields with different space-time transformation properties (scalar, four-vector, etc.) that determine the behavior of the (corresponding) meson fields under Lorentz transformations. This fact directly indicates that nuclear theory should be relativistic and based on the Dirac equation.
Scattering vector mesons in D4-D8 holographic QCD
Energy Technology Data Exchange (ETDEWEB)
Boschi-Filho, Henrique; Braga, Nelson; Ballon Bayona, C.A.; Torres, Marcus A.C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)
2009-07-01
Full text. Sakai and Sugimoto authored one of the most successful string top-down models in describing real QCD, the D4-D8 brane model of holographic QCD. This model succeeds in exhibiting chiral symmetry breaking and confinement.A drawback of this model is that all massive hadrons have their masses set by the Kaluza-Klein compactification scale and we would have to work at energy scales below 1 GeV in order to describe a four dimensional physics. Still, they were able to find pion form factors and pion in agreement with experiment at scale of 1 GeV and above. They also calculate pion quadratic square radius in check with experiment, from a formula that depends on the entire Kaluza-Klein tower of excited pion states. Their model also realizes vector meson dominance (VMD) in electromagnetic interaction as proposed by Sakurai in the sixties. 5D gauge fields from flavor symmetry provides a zoo of mesons (scalar, pseudo-scalar, vector and pseudo-vector) and instanton configurations of such fields are interpreted as baryon fields. Inspired by the results of pion form factors and pion quadratic radius predicted in close agreement with experiment, we further calculate vector and axial vector mesons {psi}(z) wave functions, form factors, we discuss about its Q{sup -2} power behavior at large virtuosity (Q{sup 2}), and we check necessary relations between coupling constants and masses (superconvergence) that grants such power behavior of form factors. We compare our results with what is found in bottom-up hard wall and soft wall models and discuss the problems of the D4-D8 model. (author)
B Meson Decays to mega K*, omega rho, omega omega, omega phi, and omega f0
Energy Technology Data Exchange (ETDEWEB)
Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Tisserand, V.; Zghiche, A.; /Annecy, LAPP; Grauges, E.; /Barcelona; Palano, A.; /Bari U. /INFN, Bari; Chen, J.C.; Qi, N.D.; Rong, G.; Wang, P.; Zhu, Y.S.; /Beijing, Inst. High Energy Phys.; Eigen, G.; Ofte, I.; Stugu, B.; /Bergen U.; Abrams,; /LBL, Berkeley /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /Bristol U. /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UCLA /UC, Riverside /UC, San Diego
2006-07-28
The authors describe searches for B meson decays to the charmless vector-vector final states {omega}K*, {omega}p, {omega}{omega}, and {omega}{phi} with 233 x 10{sup 6} B{bar B} pairs produced in e{sup +}e{sup -} annihilation at {radical}s = 10.58 GeV. They also search for the vector-scalar B decay to {omega}f{sub 0}.
Polyakov SU(3) extended linear $\\sigma$-model: Sixteen mesonic states in chiral phase-structure
Tawfik, Abdel Nasser
2014-01-01
The derivative of the grand potential in mean field approximation, non-strange and strange condensates and deconfinement phase-transition in thermal and dense hadronic medium are verified in extended SU(3) linear sigma-model (eLSM). In determining the chiral phase-transition, the chiral condensates sigma_x and sigma_y are analysed. The chiral mesonic phase-structures in temperature- and density-dependence are taken as free parameters to be fitted. These parameters are classified corresponding to scalar meson nonets; (pseudo)-scalar and (axial)-vector. For deconfinement phase-transition, effective Polyakov loop-potentials phi and phi^* are utilized. We investigated the in-medium effects on the masses of sixteen mesonic states states. The results are presented for two different forms for the effective Polyakov loop-potential and compared with other models with and without anomalous terms. The Polyakov loop potential in LSM has considerable effects on the chiral phase-transition in meson masses so that the resto...
SCALAR WAVES AND WIRELESS POWER
Directory of Open Access Journals (Sweden)
Trunev A. P.
2013-11-01
Full Text Available It is established that in the classical electrodynamics with Lorenz gauge there are solutions in the form of waves of scalar and vector potential at zero magnetic and electric field. It is shown that wave scalar and vector potential can interact with the substance, causing ionization of the atoms and molecules. The analogue of scalar waves in electrodynamics and sound waves in gas dynamics is discussed. Proposed technical application of the waves of scalar and vector potential similar to acoustic waves. Discusses Tesla invented electrical device capable of generating and receiving scalar waves
Directory of Open Access Journals (Sweden)
B.Karuna kumar
2009-09-01
Full Text Available Fingerprints are today the most widely used biometric features for personal identification. With the increasing usage of biometric systems the question arises naturally how to store and handle the acquired sensor data. Our algorithm for the digitized images is based on adaptive uniform scalar quantization of discrete wavelet transform sub band decomposition. This technique referred to as the wavelet scalar quantization method. The algorithm produces archival quality images at compression ratios of around 15 to 1 and will allow the current database of paper finger print cards to be replaced by digital imagery. A compliance testing program is also being implemented to ensure high standards of image quality and interchangeability of data between different implementations.
LEO P: AN UNQUENCHED VERY LOW-MASS GALAXY
Energy Technology Data Exchange (ETDEWEB)
McQuinn, Kristen B. W.; Skillman, Evan D.; Berg, Danielle [Minnesota Institute for Astrophysics, School of Physics and Astronomy, 116 Church Street, S.E., University of Minnesota, Minneapolis, MN 55455 (United States); Dolphin, Andrew [Raytheon Company, 1151 E. Hermans Road, Tucson, AZ 85756 (United States); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Salzer, John J.; Rhode, Katherine L. [Department of Astronomy, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Adams, Elizabeth A. K. [ASTRON, the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); Giovanelli, Riccardo; Haynes, Martha P. [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Girardi, Léo, E-mail: kmcquinn@astro.umn.edu [Osservatorio Astronomico di Padova, INAF, Vicolo dell’Osservatorio 5, I-35122 Padova (Italy)
2015-10-20
Leo P is a low-luminosity dwarf galaxy discovered through the blind H i Arecibo Legacy Fast ALFA survey. The H i and follow-up optical observations have shown that Leo P is a gas-rich dwarf galaxy with active star formation, an underlying older population, and an extremely low oxygen abundance. We have obtained optical imaging with the Hubble Space Telescope to two magnitudes below the red clump in order to study the evolution of Leo P. We refine the distance measurement to Leo P to be 1.62 ± 0.15 Mpc, based on the luminosity of the horizontal branch stars and 10 newly identified RR Lyrae candidates. This places the galaxy at the edge of the Local Group, ∼0.4 Mpc from Sextans B, the nearest galaxy in the NGC 3109 association of dwarf galaxies of which Leo P is clearly a member. The star responsible for ionizing the H ii region is most likely an O7V or O8V spectral type, with a stellar mass ≳25 M{sub ⊙}. The presence of this star provides observational evidence that massive stars at the upper end of the initial mass function are capable of being formed at star formation rates as low as ∼10{sup −5} M{sub ⊙} yr{sup −1}. The best-fitting star formation history (SFH) derived from the resolved stellar populations of Leo P using the latest PARSEC models shows a relatively constant star formation rate over the lifetime of the galaxy. The modeled luminosity characteristics of Leo P at early times are consistent with low-luminosity dSph Milky Way satellites, suggesting that Leo P is what a low-mass dSph would look like if it evolved in isolation and retained its gas. Despite the very low mass of Leo P, the imprint of reionization on its SFH is subtle at best, and consistent with being totally negligible. The isolation of Leo P, and the total quenching of star formation of Milky Way satellites of similar mass, implies that the local environment dominates the quenching of the Milky Way satellites.
Egorov, A. I.; Kashargin, P. E.; Sushkov, Sergey V.
2016-09-01
In 1921 Bach and Weyl derived the method of superposition to construct new axially symmetric vacuum solutions of general relativity. In this paper we extend the Bach-Weyl approach to non-vacuum configurations with massless scalar fields. Considering a phantom scalar field with the negative kinetic energy, we construct a multi-wormhole solution describing an axially symmetric superposition of N wormholes. The solution found is static, everywhere regular and has no event horizons. These features drastically tell the multi-wormhole configuration from other axially symmetric vacuum solutions which inevitably contain gravitationally inert singular structures, such as ‘struts’ and ‘membranes’, that keep the two bodies apart making a stable configuration. However, the multi-wormholes are static without any singular struts. Instead, the stationarity of the multi-wormhole configuration is provided by the phantom scalar field with the negative kinetic energy. Anther unusual property is that the multi-wormhole spacetime has a complicated topological structure. Namely, in the spacetime there exist 2 N asymptotically flat regions connected by throats.
A covariant nonlocal Lagrangian for the description of the scalar kaonic sector
Soltysiak, Milena
2016-01-01
Mesons are extended objects, hence their interaction can be described by utilizing form factors. At the Lagrangian level, one can use nonlocal interaction terms. Here we describe two possible nonlocal Lagrangians leading to a 3D form factor: the first one is simple but does not fulfill covariance (if one insists on a 3D cutoff), the second extension is more involved but guarantees covariance. Such form factors are useful when calculating mesonic loops. As an important example, we discuss the scalar kaonic sector, $I(J^{P})=\\frac{1}{2}(0^{+})$. The Lagrangian contains a single scalar kaon (the well-establish state $K_{0}^{\\ast}(1430)$), but through loops $K_{0}^{\\ast}(800)$ emerges as a dynamically generated companion pole (which disappears in the large-$N_{c}$ limit).
Construction of the pion scalar form factor from few poles and zero
Directory of Open Access Journals (Sweden)
Kamiński Robert
2016-01-01
Full Text Available Construction and analysis of the pion scalar-isoscalar form factor in the elastic region is presented. Precise S-wave ππ scattering phase shifts generated by dispersive analysis of experimental data with imposed crossing symmetry condition are used. Final result for values of the f0(500 meson mass and width, mσ = (487 ± 31 MeV; Γσ = (542 ± 60 MeV is compatible with the results from dispersive analyses of the Bern and Madrid-Kraków groups to be considered now as the most reliable values of the f0(500 scalar meson parameters. Parameters of the f0(980, although lying almost on the KK̄ threshold also agree with values predicted by these two groups.
Chemical tracers of episodic accretion in low-mass protostars
Visser, Ruud; Jorgensen, Jes K
2015-01-01
Aims: Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This paper aims to study such chemical effects and discusses the feasibility of using molecular spectroscopy as a tracer of episodic accretion rates and timescales. Methods: We simulate a strong accretion burst in a diverse sample of 25 spherical envelope models by increasing the luminosity to 100 times the observed value. Using a comprehensive gas-grain network, we follow the chemical evolution during the burst and for up to 10^5 yr after the system returns to quiescence. The resulting abundance profiles are fed into a line radiative transfer code to simulate rotational spectra of C18O, HCO+, H13CO+, and N2H+ at a series of time steps. We compare these spectra to observations taken from the literature and to previously unpublished data of HCO+ and N2H+ 6-5 from th...
Searches for Low Mass Higgs Boson at the Tevatron
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Sforza Federico
2012-07-01
Full Text Available We present the result of the searches for a low mass Standard Model Higgs boson performed at the Tevatron pp¯ $par p$ collider (√s = 1.96 TeV by the CDF and D0 experiments with an integrated luminosity of up to 8.5 fb-1. Individual searches are discussed and classified according to their sensitivity. Primary channels rely on the associate production with a vector boson (WH or ZH and the H → bb¯ $H o bar b$ decay channel (favored for MH ≲ 135 GeV/c2. Event selection is based on the leptonic decay of the vector boson and the identification of b–hadron enriched jets. Each individual channel is sensitive, for MH = 115 GeV/c2, to less than 5 times the SM expected cross section and the most sensitive channels can exclude a production cross section of 2.3×σHSM Secondary channels rely on a variety of final states. Although they are from 2 to 5 times less sensitive than any primary channel, they contribute to the Tevatron combination and, in some cases, they pose strong constrains on exotic Higgs boson models.
Model Atmospheres From Very Low Mass Stars to Brown Dwarfs
Allard, F; Freytag, B
2010-01-01
Since the discovery of brown dwarfs in 1994, and the discovery of dust cloud formation in the latest Very Low Mass Stars (VLMs) and Brown Dwarfs (BDs) in 1996, the most important challenge in modeling their atmospheres as become the understanding of cloud formation and advective mixing. For this purpose, we have developed radiation hydrodynamic 2D model atmosphere simulations to study the formation of forsterite dust in presence of advection, condensation, and sedimentation across the M-L-T VLMs to BDs sequence (Teff = 2800 K to 900 K, Freytag et al. 2010). We discovered the formation of gravity waves as a driving mechanism for the formation of clouds in these atmospheres, and derived a rule for the velocity field versus atmospheric depth and Teff , which is relatively insensitive to gravity. This rule has been used in the construction of the new model atmosphere grid, BT-Settl, to determine the microturbulence velocity, the diffusion coefficient, and the advective mixing of molecules as a function of depth. ...
Structure and evolution of low-mass stars
Chabrier, G; Chabrier, Gilles; Baraffe, Isabelle
1997-01-01
We present extensive calculations of the structure and the evolution of low-massstars in the range 0.07-0.8 $\\msol$, for metallicities $-2.0\\le \\mh \\le 0.0$. These calculations are based on the most recent description of the microphysics characteristic of these dense and cool objects and on the lattest generation of grainless non-grey atmosphere models. We examine the evolution of the different mechanical and thermal properties of these objects as a function of mass and metallicity. We also demonstrate the inaccuracy of grey models and $T(\\tau)$ relationships under these conditions. We provide detailed tables of the mass-radius-luminosity-effective temperature relations for various ages and metallicities, aimed at calibrating existing or future observations of low-mass stars and massive brown dwarfs. We derive new hydrogen-burning minimum masses, within the afore-mentioned metallicity range. These minimum masses are found to be smaller than previous estimates, a direct consequence of non-grey effects. At last...
Low-mass visual companions to nearby G-dwarfs
Tokovinin, Andrei
2010-01-01
Complete census of wide visual companions to nearby G-dwarf stars can be achieved by selecting candidates from the 2MASS Point-Source Catalog and checking their status by second-epoch imaging. Such data are obtained for 124 candidates with separations up to 20", 47 of which are shown to be new physical low-mass stellar companions. A list of visual binaries with G-dwarf primaries is produced by combining newly found companions with historical data. Maximum likelihood analysis leads to the companion frequency of 0.13+-0.015 per decade of separation. The mass ratio is distributed almost uniformly, with a power-law index between -0.4 and 0. The remaining uncertainty in the index is related to modeling of the companion detection threshold in 2MASS. These findings are confirmed by alternative analysis of wider companions in 2MASS, removing the contamination by background stars statistically. Extension of this work will lead to a complete detection of visual companions - a necessary step towards reaching unbiased mu...
A low mass pixel detector upgrade for CMS
Kästli, H C
2010-01-01
The CMS pixel detector has been designed for a peak luminosity of 10^34cm-2s-1 and a total dose corresponding to 2 years of LHC operation at a radius of 4 cm from the interaction region. Parts of the pixel detector will have to be replaced until 2015. The detector performance will be degraded for two reasons: radiation damage of the innermost layers and the planned increase of the LHC peak luminosity by a factor of 2-3. Based on the experience in planning, constructing and commissioning of the present pixel detector, we intend to upgrade the whole pixel detector in 2015. The main focus is on lowering the material budget and adding more tracking points. We will present the design of a new low mass pixel system consisting of 4 barrel layers and 3 end cap disks on each side. The design comprises of thin detector modules and a lightweight mechanical support structure using CO2 cooling. In addition, large efforts have been made to move material from the services out of the tracking region.
Flare activity on low-mass eclipsing binary GJ 3236*
Šmelcer, L.; Wolf, M.; Kučáková, H.; Bílek, F.; Dubovský, P.; Hoňková, K.; Vraštil, J.
2017-04-01
We report the discovery of optical flares on the very low-mass red-dwarf eclipsing binary GJ 3236 and the results of our 2014-2016 photometric campaign. In total, this binary was monitored photometrically in all filters for about 900 h, which has revealed a flare rate of about 0.06 flares per hour. The amplitude of its flares is the largest among those detected in the V band (∼1.3 mag), R band (∼0.8 mag), I band (∼0.2 mag) and clear band (∼0.5 mag). The light curves of GJ 3236 were analysed and the statistics of detected flare events are presented. The energy released during individual flares was calculated as up to 2.4 × 1027 J and compared with other known active stars. The cumulative distribution of flare energies appears to follow a broken power law. The flare activity of this binary also plays an important role in the precise determination of its physical parameters and evolutionary status.
Rotational Velocities of Individual Components in Very Low Mass Binaries
Konopacky, Q M; Fabrycky, D C; Macintosh, B A; White, R J; Barman, T S; Rice, E L; Hallinan, G; Duchene, G
2012-01-01
We present rotational velocities for individual components of eleven very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics (LGS AO) system. We find that the observed sources tend to be rapid rotators (vsini > 10 km/s), consistent with previous seeing-limited measurements of VLM objects. The two sources with the largest vsini, LP 349-25B and HD 130948C, are rotating at ~30% of their break up speed, and are among the most rapidly rotating VLM objects known. Furthermore, five binary systems, all with orbital semi-major axes <3.5 AU, have component vsini values that differ by greater than 3sigma. To bring the binary components with discrepant rotational velocities into agreement would require the rotational axes to be inclined with respect to each other, and that at least one component is inclined with respect to the orbital plane. Alternatively, each comp...
SHIELD: Comparing Gas and Star Formation in Low Mass Galaxies
Teich, Yaron G; Nims, Elise; Cannon, John M; Adams, Elizabeth A K; Bernstein-Cooper, Elijah Z; Giovanelli, Riccardo; Haynes, Martha P; Józsa, Gyula I G; McQuinn, Kristen B W; Salzer, John J; Skillman, Evan D; Warren, Steven R; Dolphin, Andrew; Elson, E C; Haurberg, Nathalie; Ott, Jürgen; Saintonge, Amelie; Cave, Ian; Hagen, Cedric; Huang, Shan; Janowiecki, Steven; Marshall, Melissa V; Thomann, Clara M; Van Sistine, Angela
2016-01-01
We analyze the relationships between atomic, neutral hydrogen (HI) and star formation (SF) in the 12 low-mass SHIELD galaxies. We compare high spectral (~0.82 km/s/channel) and spatial resolution (physical resolutions of 170 pc - 700 pc) HI imaging from the VLA with H\\alpha and far-ultraviolet imaging. We quantify the degree of co-spatiality between star forming regions and regions of high HI column densities. We calculate the global star formation efficiencies (SFE, $\\Sigma_{\\rm SFR}$ / $\\Sigma_{\\rm HI}$), and examine the relationships among the SFE and HI mass, HI column density, and star formation rate (SFR). The systems are consuming their cold neutral gas on timescales of order a few Gyr. While we derive an index for the Kennicutt-Schmidt relation of N ~ 0.68 $\\pm$ 0.04 for the SHIELD sample as a whole, the values of N vary considerably from system to system. By supplementing SHIELD results with those from other surveys, we find that HI mass and UV-based SFR are strongly correlated over five orders of ma...
The low mass ratio contact binary system V728 Herculis
Erkan, Naci
2015-01-01
We present the orbital period study and the photometric analys of the contact binary system V728 Her. Our orbital period analysis shows that the period of the system increases (dP/dt=1.92x10^-7dyr^-1) and the mass transfer rate from the less massive component to more massive one is 2.51x10^-8M_suny^-1. In addition, an advanced sinusoidal variation in period can be attributed to the light-time effect by a tertiary component or the Applegate mechanism triggered by the secondary component. The simultaneous multicolor BVR light and radial velocity curves solution indicates that the physical parameters of the system are M1=1.8M_sun, M2=0.28M_sun, R1=1.87R_sun, R2=0.82R_sun, L1=5.9L_sun, and L2=1.2L_sun. We discuss the evolutionary status and conclude that V728 Her is a deep (f=81%), low mass ratio (q=0.16) contact binary system.
Tracing Cold HI Gas in Nearby, Low-Mass Galaxies
Warren, Steven R; Stilp, Adrienne M; Dalcanton, Julianne J; Ott, Juergen; Walter, Fabian; Petersen, Eric A; Koribalski, Baerbel; West, Andrew A
2012-01-01
We analyze line-of-sight atomic hydrogen (HI) line profiles of 31 nearby, low-mass galaxies selected from the Very Large Array - ACS Nearby Galaxy Survey Treasury (VLA-ANGST) and The HI Nearby Galaxy Survey (THINGS) to trace regions containing cold (T $\\lesssim$ 1400 K) HI from observations with a uniform linear scale of 200 pc/beam. Our galaxy sample spans four orders of magnitude in total HI mass and nine magnitudes in M_B. We fit single and multiple component functions to each spectrum to isolate the cold, neutral medium given by a low dispersion (<6 km/s) component of the spectrum. Most HI spectra are adequately fit by a single Gaussian with a dispersion of 8-12 km/s. Cold HI is found in 23 of 27 (~85%) galaxies after a reduction of the sample size due to quality control cuts. The cold HI contributes ~20% of the total line-of-sight flux when found with warm HI. Spectra best fit by a single Gaussian, but dominated by cold HI emission (i.e., have velocity dispersions <6 km/s) are found primarily beyon...
Structure and evolution of low-mass Population II stars
Montalbán, J.; D'Antona, F.; Mazzitelli, I.
2000-08-01
The focus of the present paper is on the detailed description of the internal structures of low mass, population II stars, to clarify some issues about these stellar models and, mainly, their present reliability for observational comparisons. We then explore 1) the role of the local convective model; 2) the differences between "grey" and "non grey" models, and between models in which the photospheric boundary conditions are set at different optical depths (τph = 3 or 100); 3) the role of the equation of state (EoS), both in the atmospheric models and in the interior. One of the major conclusions of the paper is a cautionary note about the usage of the additive volume law in EoS calculations. The dependence of the HR diagram locations and mass luminosity relations on metal and helium content are also discussed. A few comparisons with globular cluster stars show that: 1) general consistency of distance scales and morphologies in the HR diagram is found, when comparing ground based measurements in the Johnson B and V bands and observations in the HST bands; 2) a discrepancy between models and observations may exist for more metal rich clusters; 3) the plausible hypothesis that the mass function in the globular cluster NGC 6397 behaves smoothly until the lower limit of the main sequence poses constraints on the mass-luminosity relation at the lowest end of the main sequence. The evolutionary tracks are available at the WEB location http://www.mporzio.astro.it.
Most Double Degenerate Low Mass White Dwarf Binaries Merge
Brown, Warren R; Kenyon, Scott J; Gianninas, A
2016-01-01
We estimate the merger rate of double degenerate binaries containing extremely low mass (ELM) <0.3 Msun white dwarfs in the Galaxy. Such white dwarfs are detectable for timescales of 0.1 Gyr -- 1 Gyr in the ELM Survey; the binaries they reside in have gravitational wave merger times of 0.001 Gyr -- 100 Gyr. To explain the observed distribution requires that most ELM white dwarf binary progenitors detach from the common envelope phase with <1 hr orbital periods. We calculate the local space density of ELM white dwarf binaries and estimate a merger rate of 3e-3/yr over the entire disk of the Milky Way; the merger rate in the halo is 10 times smaller. The ELM white dwarf binary merger rate exceeds by a factor of 40 the formation rate of stable mass transfer AM CVn binaries, marginally exceeds the rate of underluminous supernovae, and is identical to the formation rate of R CrB stars. On this basis, we conclude that ELM white dwarf binaries can be the progenitors of all observed AM CVn and possibly underlum...
Improving PARSEC models for very low mass stars
Chen, Yang; Bressan, Alessandro; Marigo, Paola; Barbieri, Mauro; Kong, Xu
2014-01-01
Many stellar models present difficulties in reproducing basic observational relations of very low mass stars (VLMS), including the mass--radius relation and the optical colour--magnitudes of cool dwarfs. Here, we improve PARSEC models on these points. We implement the T--tau relations from PHOENIX BT-Settl model atmospheres as the outer boundary conditions in the PARSEC code, finding that this change alone reduces the discrepancy in the mass--radius relation from 8 to 5 per cent. We compare the models with multi--band photometry of clusters Praesepe and M67, showing that the use of T--tau relations clearly improves the description of the optical colours and magnitudes. But anyway, using both Kurucz and PHOENIX model spectra, model colours are still systematically fainter and bluer than the observations. We then apply a shift to the above T--tau relations, increasing from 0 at T_eff = 4730 K to ~14% at T_eff = 3160 K, to reproduce the observed mass--radius radius relation of dwarf stars. Taking this experiment...
Evolution of Low-Mass Population III Stars
Suda, T; Itoh, N; Suda, Takuma; Fujimoto, Masayuki Y.
2005-01-01
The evolution of low-mass Pop.III of mass 0.8-1.1 Msun is followed from the main sequence to the onset of H mixing into a convective zone driven by the He core flash. We examine the dependence of stellar structure on the adopted input physics and find that consideration of the non-resonant term in the 3-alpha reaction rate is crucial, since the CN cycle is activated when the abundance by number of 12C produced by this reaction is no larger than 10^-11-10^-9. This explains why recent computations of Pop.III do not find a He flash occurring at the bottom of the H-burning shell at the beginning of the H shell burning phase, as first found by Fujimoto et al.(1990) who did not include the non-resonant term in their calculations. We confirm that, if the non-resonant term of the 3-alpha reaction rate is not included in the input physics, the He-H flash in the shell occurs for M >= 1.0 Msun. We also find that the treatment of the EOS for the Coulomb liquid region, where electron conduction and radiation compete, is i...
On the low-mass diskless population of Corona Australis
Martí, Belén López; Merín, Bruno; Morales-Calderón, María; Bouy, Hervé; Barrado, David; Eislöffel, Jochen
2010-01-01
We combine published optical and near-infrared photometry to identify new low-mass candidate members in an area of about 0.64 deg^2 in Corona Australis, using the S-parameter method developed by Comer\\'on et al. (2009). Five new candidate members of the region are selected, with estimated ages between 3 and 15 Myr, and masses between 0.05 and 0.15 M_Sun. Using Spitzer photometry, we confirm that these objects are not surrounded by optically thick disks. However, one of them is found to display excess at 24 micron, thus suggesting it harbours a disk with an inner hole. With an estimated mass of 0.07 M_Sun according to the SED fitting, this is one of the lowest-mass objects reported to possess a transitional disk. Including these new members, the fraction of disks is about 50% among the total Corona Australis population selected by the same criteria, lower than the 70% fraction reported by Sicilia-Aguilar et al. (2008) for this region. Even so, we find a ratio of transitional to primordial disks (45%) very simi...
Variational Worldline Approximation for the Relativistic Two-Body Bound State in a Scalar Model
Barro-Bergfl"odt, K; Stingl, M
2006-01-01
We use the worldline representation of field theory together with a variational approximation to determine the lowest bound state in the scalar Wick-Cutkosky model where two equal-mass constituents interact via the exchange of mesons. Self-energy and vertex corrections are included approximately in a consistent way as well as crossed diagrams. Only vacuum-polarization effects of the heavy particles are neglected. In a path integral description of an appropriate current-current correlator an effective, retarded action is obtained by integrating out the meson field. As in the polaron problem we employ a quadratic trial action with variational functions to describe retardation and binding effects through multiple meson exchange.The variational equations for these functions are derived, discussed qualitatively and solved numerically. We compare our results with the ones from traditional approaches based on the Bethe-Salpeter equation and find an enhanced binding. For weak coupling this is worked out analytically ...
Search for rare B meson decays into D {/s +} mesons
Albrecht, H.; Ehrlichmann, H.; Hamacher, T.; Hofmann, R. P.; Kirchhoff, T.; Nau, A.; Nowak, S.; Schröder, H.; Schulz, H. D.; Walter, M.; Wurth, R.; Appuhn, R. D.; Hast, C.; Kolanoski, H.; Lange, A.; Lindner, A.; Mankel, R.; Schieber, M.; Siegmund, T.; Spaan, B.; Thurn, H.; Töpfer, D.; Walther, A.; Wegener, D.; Bittner, M.; Eckstein, P.; Paulini, M. G.; Reim, K.; Wegener, H.; Mundt, R.; Oest, T.; Reiner, R.; Schmidt-Parzefall, W.; Funk, W.; Stiewe, J.; Werner, S.; Ehret, K.; Hofmann, W.; Hüpper, A.; Khan, S.; Knöpfle, K. T.; Spengler, J.; Britton, D. I.; Charlesworth, C. E. K.; Edwards, K. W.; Hyatt, E. R. F.; Kapitza, H.; Krieger, P.; Macfarlane, D. B.; Patel, P. M.; Prentice, J. D.; Saull, P. R. B.; Tzamariudaki, K.; van de Water, R. G.; Yoon, T.-S.; Reßing, D.; Schmidtler, M.; Schneider, M.; Schubert, K. R.; Strahl, K.; Waldi, R.; Weseler, S.; Kernel, G.; Križan, P.; Križnič, E.; Podobnik, T.; Živko, T.; Balagura, V.; Belyaev, I.; Chechelnitsky, S.; Danilov, M.; Droutskoy, A.; Gershtein, Yu.; Golutvin, A.; Gorelov, I.; Kostina, G.; Lubimov, V.; Pakhlov, P.; Ratnikov, F.; Semenov, S.; Shibaev, V.; Soloshenko, V.; Tichomirov, I.; Zaitsev, Yu.
1993-03-01
A search has been performed for rare B meson decays into D {/s -} mesons arising from b→ u transitions, W exchange modes, B + annihilation processes, and decays where the D {/s +} is not produced via a W→ c bar s quark pair coupling, using the ARGUS detector operating on the Ψ(4 S) resonance at the e + e - storage ring DORIS II. Upper limits for individual decay modes are obtained. In addition, from a study of D {/s +}ℓ- correlations an upper limit of BR ( B→ D {/s +}ℓ- X) (90% CL) is determined.
Hard Exclusive Production of Tensor Mesons
Braun, V M
2001-01-01
We point out that hard exclusive production of tensor mesons $f_2(1270)$ with helicity $\\lambda=\\pm 2$ is dominated by the gluon component in the meson wave function and can be used to determine gluon admixture in tensor mesons in a theoretically clean manner. We present a detailed analysis of the tensor meson distribution amplitudes and calculate the transition form factor $\\gamma+\\gamma^*\\to f_2(1270)$ for one real and one virtual photon.
Heavy meson production in hot dense matter
Tolos, Laura; Gamermann, Daniel; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Nieves, JM; Oset, E; Vacas, MJV
2010-01-01
The properties of charmed mesons in dense matter are studied using a unitary coupled-channel approach in the nuclear medium which takes into account Pauli-blocking effects and meson self-energies in a self-consistent manner. We obtain the open-charm meson spectral functions in this dense nuclear env
Rotational Velocities of Individual Components in Very Low Mass Binaries
Konopacky, Q. M.; Ghez, A. M.; Fabrycky, D. C.; Macintosh, B. A.; White, R. J.; Barman, T. S.; Rice, E. L.; Hallinan, G.; Duchêne, G.
2012-05-01
We present rotational velocities for individual components of 11 very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics system. We find that the observed sources tend to be rapid rotators (v sin i > 10 km s-1), consistent with previous seeing-limited measurements of VLM objects. The two sources with the largest v sin i, LP 349-25B and HD 130948C, are rotating at ~30% of their break-up speed, and are among the most rapidly rotating VLM objects known. Furthermore, five binary systems, all with orbital semimajor axes lsim3.5 AU, have component v sin i values that differ by greater than 3σ. To bring the binary components with discrepant rotational velocities into agreement would require the rotational axes to be inclined with respect to each other, and that at least one component is inclined with respect to the orbital plane. Alternatively, each component could be rotating at a different rate, even though they have similar spectral types. Both differing rotational velocities and inclinations have implications for binary star formation and evolution. We also investigate possible dynamical evolution in the triple system HD 130948A-BC. The close binary brown dwarfs B and C have significantly different v sin i values. We demonstrate that components B and C could have been torqued into misalignment by the primary star, A, via orbital precession. Such a scenario can also be applied to another triple system in our sample, GJ 569A-Bab. Interactions such as these may play an important role in the dynamical evolution of VLM binaries. Finally, we note that two of the binaries with large differences in component v sin i, LP 349-25AB and 2MASS 0746+20AB, are also known radio sources.
ROTATIONAL VELOCITIES OF INDIVIDUAL COMPONENTS IN VERY LOW MASS BINARIES
Energy Technology Data Exchange (ETDEWEB)
Konopacky, Q. M.; Macintosh, B. A. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Ghez, A. M. [UCLA Division of Astronomy and Astrophysics, Los Angeles, CA 90095-1562 (United States); Fabrycky, D. C. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); White, R. J. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Barman, T. S. [Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ 86001 (United States); Rice, E. L. [American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192 (United States); Hallinan, G. [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Duchene, G., E-mail: macintosh1@llnl.gov, E-mail: konopacky@di.utoronto.ca, E-mail: ghez@astro.ucla.edu, E-mail: fabrycky@ucolick.org, E-mail: white@chara.gsu.edu, E-mail: barman@lowell.edu, E-mail: erice@amnh.org, E-mail: gh@astro.caltech.edu, E-mail: gduchene@berkeley.edu [Astronomy Department, University of California, Berkeley, Hearst Field Annex B-20, CA 94720-3411 (United States)
2012-05-01
We present rotational velocities for individual components of 11 very low mass (VLM) binaries with spectral types between M7 and L7.5. These results are based on observations taken with the near-infrared spectrograph, NIRSPEC, and the Keck II laser guide star adaptive optics system. We find that the observed sources tend to be rapid rotators (v sin i > 10 km s{sup -1}), consistent with previous seeing-limited measurements of VLM objects. The two sources with the largest v sin i, LP 349-25B and HD 130948C, are rotating at {approx}30% of their break-up speed, and are among the most rapidly rotating VLM objects known. Furthermore, five binary systems, all with orbital semimajor axes {approx}<3.5 AU, have component v sin i values that differ by greater than 3{sigma}. To bring the binary components with discrepant rotational velocities into agreement would require the rotational axes to be inclined with respect to each other, and that at least one component is inclined with respect to the orbital plane. Alternatively, each component could be rotating at a different rate, even though they have similar spectral types. Both differing rotational velocities and inclinations have implications for binary star formation and evolution. We also investigate possible dynamical evolution in the triple system HD 130948A-BC. The close binary brown dwarfs B and C have significantly different v sin i values. We demonstrate that components B and C could have been torqued into misalignment by the primary star, A, via orbital precession. Such a scenario can also be applied to another triple system in our sample, GJ 569A-Bab. Interactions such as these may play an important role in the dynamical evolution of VLM binaries. Finally, we note that two of the binaries with large differences in component v sin i, LP 349-25AB and 2MASS 0746+20AB, are also known radio sources.
Medium Modification of Vector Mesons
Energy Technology Data Exchange (ETDEWEB)
Chaden Djalali, Michael Paolone, Dennis Weygand, Michael H. Wood, Rakhsha Nasseripour
2011-03-01
The theory of the strong interaction, Quantum Chromodynamics (QCD), has been remarkably successful in describing high-energy and short-distance-scale experiments involving quarks and gluons. However, applying QCD to low energy and large-distance scale experiments has been a major challenge. Various QCD-inspired models predict a partial restoration of chiral symmetry in nuclear matter with modifications of the properties of hadrons from their free-space values. Measurable changes such as a shift in mass and/or a change of width are predicted at normal nuclear density. Photoproduction of vector mesons off nuclei have been performed at different laboratories. The properties of the ρ, ω and φ mesons are investigated either directly by measuring their mass spectra or indirectly through transparency ratios. The latest results regarding medium modifications of the vector mesons in the nuclear medium will be discussed.
Neutral B meson flavor tagging
Wilson, Robert J.
2001-07-01
We present an investigation of the use of net charge and kaon identification to tag the flavor of neutral B mesons. The net charge of the neutral B meson decay products is zero if all charged particles are used and slightly non-zero if only undiscriminated hadronic final states are used. The net charge of the kaons alone correctly tags the identity of the neutral meson in at least a third of all decays. We have parametrized the particle identification capability of several techniques, such as dE/dx in time projection chambers, LEP/SLC ring-imaging chambers and an enhanced BaBar DIRC. Using these parametrisations we compare the relative tagging power of each technique to that of an ideal detector.
Neutral B meson flavor tagging
Wilson, R J
2001-01-01
We present an investigation of the use of net charge and kaon identification to tag the flavor of neutral B mesons. The net charge of the neutral B meson decay products is zero if all charged particles are used and slightly non-zero if only undiscriminated hadronic final states are used. The net charge of the kaons alone correctly tags the identity of the neutral meson in at least a third of all decays. We have parametrized the particle identification capability of several techniques, such as dE/dx in time projection chambers, LEP/SLC ring-imaging chambers and an enhanced BaBar DIRC. Using these parametrisations we compare the relative tagging power of each technique to that of an ideal detector. (8 refs).
Photoproduction of mesons off nuclei
Krusche, B
2011-01-01
Recent results for the photoproduction of mesons off nuclei are reviewed. These experiments have been performed for two major lines of research related to the properties of the strong interaction. The investigation of nucleon resonances requires light nuclei as targets for the extraction of the isospin composition of the electromagnetic excitations. This is done with quasi-free meson photoproduction off the bound neutron and supplemented with the measurement of coherent photoproduction reactions, serving as spin and/or isospin filters. Furthermore, photoproduction from light and heavy nuclei is a very efficient tool for the study of the interactions of mesons with nuclear matter and the in-medium properties of hadrons. Experiments are currently rapidly developing due to the combination of high quality tagged (and polarized) photon beams with state-of-the-art 4pi detectors and polarized targets.
Geometric scalar theory of gravity
Energy Technology Data Exchange (ETDEWEB)
Novello, M.; Bittencourt, E.; Goulart, E.; Salim, J.M.; Toniato, J.D. [Instituto de Cosmologia Relatividade Astrofisica ICRA - CBPF Rua Dr. Xavier Sigaud 150 - 22290-180 Rio de Janeiro - Brazil (Brazil); Moschella, U., E-mail: novello@cbpf.br, E-mail: eduhsb@cbpf.br, E-mail: Ugo.Moschella@uninsubria.it, E-mail: egoulart@cbpf.br, E-mail: jsalim@cbpf.br, E-mail: toniato@cbpf.br [Università degli Studi dell' Insubria - Dipartamento di Fisica e Matematica Via Valleggio 11 - 22100 Como - Italy (Italy)
2013-06-01
We present a geometric scalar theory of gravity. Our proposal will be described using the ''background field method'' introduced by Gupta, Feynman, Deser and others as a field theory formulation of general relativity. We analyze previous criticisms against scalar gravity and show how the present proposal avoids these difficulties. This concerns not only the theoretical complaints but also those related to observations. In particular, we show that the widespread belief of the conjecture that the source of scalar gravity must be the trace of the energy-momentum tensor — which is one of the main difficulties to couple gravity with electromagnetic phenomenon in previous models — does not apply to our geometric scalar theory. From the very beginning this is not a special relativistic scalar gravity. The adjective ''geometric'' pinpoints its similarity with general relativity: this is a metric theory of gravity. Some consequences of this new scalar theory are explored.
Albrecht, H.; Hamacher, T.; Hofmann, R. P.; Kirchhoff, T.; Mankel, R.; Nau, A.; Nowak, S.; Schröder, H.; Schulz, H. D.; Walter, M.; Wurth, R.; Hast, C.; Kapitza, H.; Kolanoski, H.; Kosche, A.; Lange, A.; Lindner, A.; Schieber, M.; Siegmund, T.; Spaan, B.; Thurn, H.; Töpfer, D.; Wegener, D.; Eckstein, P.; Schubert, K. R.; Schwierz, R.; Waldi, R.; Reim, K.; Wegener, H.; Eckmann, R.; Kuipers, H.; Mai, O.; Mundt, R.; Oest, T.; Reiner, R.; Schmidt-Parzefall, W.; Stiewe, J.; Werner, S.; Ehret, K.; Hofmann, W.; Hüpper, A.; Knöpfle, K. T.; Spengler, J.; Krieger, P.; Macfarlane, D. B.; Saull, P. R. B.; Tzamariudaki, K.; van de Water, R. G.; Yoon, T.-S.; Frankl, C.; Reßing, D.; Schmidtler, M.; Schneider, M.; Weseler, S.; Kernel, G.; Križan, P.; Križnič, E.; Podobnik, T.; Živko, T.; Balagura, V.; Belyaev, I.; Schechelnitsky, S.; Danilov, M.; Doutskoy, A.; Gershtein, Yu.; Golutvin, A.; Korolko, I.; Kostina, G.; Litvintsev, D.; Lubimov, V.; Pakhlov, P.; Semenov, S.; Snizhko, A.; Tichomirov, I.; Zaitsev, Yu.
1995-06-01
Using the ARGUS detector at the storage ring DORIS II we have measured τ decays into three charged mesons containing K * mesons. Exploiting the good particle identification capabilities of the detector we have determined the following branching ratios:Brleft( {tau ^ - to overline {K^{*0} } π ^ - v_tau } right) = left( {0.25 ± 0.10 ± 0.05} right)% , B r (τ-→ K *0 K - v τ)= (0.20±0.05±0.04)%, and B r (τ-→ K *- X 0 v τ) =(1.15±0.15-0.18 +0.13)%.
Exlusive charmed meson pair production
Berezhnoy, A V
2004-01-01
The experimental data of BELLE Collaboration on the exclusive charmed meson pair production in the process of monophotonic $e^+e^-$-annihilation ($e^+e^-\\to \\gamma^* \\to D\\bar D$) has been studied. It has been shown that these data is described satisfactorily in the frame work of constituent quark model. Our studies have demonstrated that the central production process $e^+e^-\\to e^+e^-\\gamma\\gamma \\to e^+e^-D\\bar D +X$ and the process of monophotonic $e^+e^-$-annihilation yield comparable numbers of the charmed meson pairs.
Buchheim, Thomas; Kampfer, Burkhard
2014-01-01
Wilson coefficients of light four-quark condensates in QCD sum rules are evaluated for pseudo-scalar $D$ mesons, thus, pushing the sum rules toward mass dimension six. Contrary to the situation for $\\bar{q}q$ mesons the impact of the four-quark condensates for vacuum as well as in-medium situations is found to be rather small within the Borel window used in previous analyses. The complete four-quark condensate contributions enable to identify candidates for an order parameter of spontaneous chiral symmetry breaking/restoration as well as to evaluate stability criteria of operator product expansions.
Vector mesons in meson-baryon scattering and large-N{sub c} quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Fuhrmann, Hans-Friedrich
2016-02-11
We examined strong interactions in the low-energy regime in terms of two complementary non-perturbative approaches: the interplay of large-N{sub c} QCD and chiral perturbation theory was studied. While the expansion in the parameter 1/N{sub c} is based on quark and gluon degrees of freedom, chiral perturbation theory uses hadrons as effective degrees of freedom. The focus of our work was the investigation of mesons and baryons composed from up-, down- and strange quarks. We used the chiral SU(3) Lagrangian with (J{sup P}=(1)/(2){sup +})- and (J{sup P}=(3)/(2){sup +})-baryon ground states as building blocks. In the SU(3)-flavour limit the latter form an octet and a decuplet, respectively. Studies in chiral perturbation theory hold a challenge: the chiral Lagrangian consists of an infinite number of terms. The treatment of low-energy QCD physics via a perturbation theory requires the ordering of these terms according to their relevance. We used the interplay between large-N{sub c} QCD and chiral perturbation theory to shed light on the structure of the chiral Lagrangian. In the limit of large-N{sub c} the low-energy parameters of the chiral Lagrangian are correlated. For instance the masses of the two baryon multiplets turn degenerate in the SU(3)-flavour limit. This serves as the starting point of our investigations. In this work we analysed the time-ordered product of two scalar and two vector currents in the baryon ground state. The examination of these matrix elements at large-N{sub c} was compared to corresponding results derived in chiral perturbation theory. From this we obtained sum rules for some low-energy parameters of the chiral Lagrangian. The results for the vector correlation function were used to constrain a phenomenological interaction of light vector mesons with the baryon ground states. In the second part of this thesis we addressed a formal problem which arises in a partial wave decomposition of reaction amplitudes for particles with non
Frigerio, Michele; Riva, Francesco; Urbano, Alfredo
2012-01-01
We show that the dark matter (DM) could be a light composite scalar $\\eta$, emerging from a TeV-scale strongly-coupled sector as a pseudo Nambu-Goldstone boson (pNGB). Such state arises naturally in scenarios where the Higgs is also a composite pNGB, as in $O(6)/O(5)$ models, which are particularly predictive, since the low-energy interactions of $\\eta$ are determined by symmetry considerations. We identify the region of parameters where $\\eta$ has the required DM relic density, satisfying at the same time the constraints from Higgs searches at the LHC, as well as DM direct searches. Compositeness, in addition to justify the lightness of the scalars, can enhance the DM scattering rates and lead to an excellent discovery prospect for the near future. For a Higgs mass $m_h\\simeq 125$ GeV and a pNGB characteristic scale $f \\lesssim 1$ TeV, we find that the DM mass is either $m_\\eta \\simeq 50-70$ GeV, with DM annihilations driven by the Higgs resonance, or in the range 100-500 GeV, where the DM derivative interac...
A Complex Organic Slushy Bathing Low-Mass Protostars
Drozdovskaya, Maria; Walsh, Catherine; Visser, Ruud; Harsono, Daniel; van Dishoeck, Ewine
2015-08-01
Complex organic molecules are ubiquitous companions of young forming stars. They were first observed in hot cores surrounding high-mass protostars [e.g., 1], but have since also been detected in the environs of several low-mass counterparts [e.g., 2]. Recent studies have shown that colder envelopes and positions with impinging outflows may also glow with emission from complex organic species [e.g., 3, 4]. For this meeting, I would like to present physicochemical modeling results on the synthesis of complex organics in an envelope-cavity system that is subject to non-thermal processing. This includes wavelength-dependent radiative transfer calculations with RADMC [5] and a comprehensive gas-grain chemical network [6]. The results show that the morphology of such a system delineates three distinct regions: the cavity wall layer with time-dependent and species-variant enhancements; a torus rich in complex organic ices, but not reflected in gas-phase abundances; and the remaining outer envelope abundant in simpler solid and gaseous molecules. Within the adopted paradigm, complex organic molecules are demonstrated to have unique lifetimes and be grouped into early and late species [7]. Key chemical processes for forming and destroying complex organic molecules will be discussed. In addition, the results of adding newly experimentally verified routes [8] into the existing chemical networks will be shown.[1] Blake G. A., Sutton E. C., Masson C. R., Phillips T. G., 1987, ApJ, 315, 621[2] Jørgensen J. K., Favre C., Bisschop S. E., Bourke T. L., van Dishoeck E. F., Schmalzl M., 2012, ApJ, 757, L4[3] Arce H. G., Santiago-García J., Jørgensen J. K., Tafalla M., Bachiller R., 2008, ApJ, 681, L21[4] Öberg K. I., Bottinelli S., Jørgensen J. K., van Dishoeck E. F., 2010, ApJ, 716, 825[5] Dullemond C. P., Dominik C., 2004, A&A, 417, 159[6] Walsh C., Millar T. J., Nomura H., Herbst E., Widicus Weaver S., Aikawa Y., Laas J. C., Vasyunin A. I., 2014, A&A, 563, A33[7] Drozdovskaya
Terrestrial planets and water delivery around low-mass stars
Dugaro, A.; de Elía, G. C.; Brunini, A.; Guilera, O. M.
2016-11-01
Context. Theoretical and observational studies suggest that protoplanetary disks with a wide range of masses could be found around low-mass stars. Aims: We analyze planetary formation processes in systems without gas giants around M3- and M0-type stars of 0.29 M⊙ and 0.5 M⊙, respectively. In particular, we assume disks with masses of 5% and 10% of the mass of the star. Our study focuses on the formation of terrestrial-like planets and water delivery in the habitable zone (HZ). Methods: First, we use a semi-analytical model to describe the evolution of embryos and planetesimals during the gaseous phase. Then, a N-body code is used to analyze the last giant impact phase after the gas dissipation. Results: For M3-type stars, five planets with different properties are formed in the HZ. These planets have masses of 0.072 M⊕, 0.13 M⊕ (two of them), and 1.03 M⊕, and have water contents of 5.9%, 16.7%, 28.6%, and 60.6% by mass, respectively. Then, the fifth planet formed in the HZ is a dry world with 0.138 M⊕. For M0-type stars, four planets are produced in the HZ with masses of 0.28 M⊕, 0.51 M⊕, 0.72 M⊕, and 1.42 M⊕, and they have water contents of 26.7%, 45.8%, 68%, and 50.5% by mass, respectively. Conclusions: M3- and M0-type stars represent targets of interest for the search of exoplanets in the HZ. In fact, the Mars-mass planets formed around M3-type stars could maintain habitable conditions in their early histories. Thus, the search for candidates around young M3-type stars could lead to the detection of planets analogous to early Mars. Moreover, Earth-mass planets should also be discovered around M3-type stars and, sub- and super-Earths should be detected around M0-type stars. Such planets are very interesting since they could maintain habitable conditions for very long.
Miniature Low-Mass Drill Actuated by Flextensional Piezo Stack
Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph
2010-01-01
characteristics of low mass, small size, low power, and low axial loads for sampling.
Pseudoscalar meson form factors and decays
Dorokhov, A E
2011-01-01
In this communication we discuss few topics related with modern experimental data on the physics of light pseudoscalar mesons. It includes the contribution of the pseudoscalar mesons to the muon anomalous magnetic moment (AMM), $g-2$, the rare decays of light pseudoscalar mesons to lepton pair, the transition form factors of pseudoscalar mesons at large momentum transfer, the pion transversity form factor. Measuring the muon anomalous magnetic moment $g-2$ and the rare decays of light pseudoscalar mesons into lepton pair $P\\rightarrow l^{+}l^{-} $ serve as important test of the standard model. To reduce the theoretical uncertainty in the standard model predictions the data on the transition form factors of light pseudoscalar mesons play significant role. Recently new data on behavior of these form factors at large momentum transfer was supplied by the BABAR collaboration. Within the nonlocal chiral quark model it shown how to describe these data and how the meson distribution amplitude evolves as a function o...
Holographic mesons in various dimensions
Myers, R C; Myers, Robert C.; Thomson, Rowan M.
2006-01-01
We calculate the spectrum of fluctuations of a probe Dk-brane in the background of N Dp-branes, for k=p,p+2,p+4 and p< 5. The result corresponds to the mesonic spectrum of a (p+1)-dimensional super-Yang-Mills (SYM) theory coupled to `dynamical quarks', i.e., fields in the fundamental representation -- the latter are confined to a defect for k=p and p+2. We find a universal behaviour where the spectrum is discrete and the mesons are deeply bound. The mass gap and spectrum are set by the scale M ~ m_q/g_{eff}(m_q), where m_q is the mass of the fundamental fields and g_{eff}(m_q) is the effective coupling evaluated at the quark mass, i.e. g_{eff}^2(m_q)=\\gym^2N m_q^{p-3}. We consider the evolution of the meson spectra into the far infrared of three-dimensional SYM, where the gravity dual lifts to M-theory. We also argue that the mass scale appearing in the meson spectra is dictated by holography.
Exclusive meson production at NLO
Energy Technology Data Exchange (ETDEWEB)
Diehl, M.; Kugler, W.
2007-06-15
We report on numerical studies of the NLO corrections to exclusive meson electroproduction, both in collider and fixed-target kinematics. Corrections are found to be huge at small x{sub B} and moderate at intermediate or large x{sub B}. (orig.)
Theoretical overview: The New mesons
Energy Technology Data Exchange (ETDEWEB)
Quigg, Chris; /Fermilab
2004-11-01
After commenting on the state of contemporary hadronic physics and spectroscopy, I highlight four areas where the action is: searching for the relevant degrees of freedom, mesons with beauty and charm, chiral symmetry and the D{sub sJ} levels, and X(3872) and the lost tribes of charmonium.
Exclusive meson production at COMPASS
Pochodzalla, J; Moinester, M A; Piller, G; Sandacz, A; Vanderhaeghen, M; Pochodzalla, Josef; Mankiewicz, Lech; Moinester, Murray; Piller, Gunther; Sandacz, Andrzej; Vanderhaeghen, Marc
1999-01-01
We explore the feasibility to study exclusive meson production (EMP) in hard muon-proton scattering at the COMPASS experiment. These measurements constrain the off-forward parton distributions (OFPD's) of the proton, which are related to the quark orbital contribution to the proton spin.
Vector meson electroproduction in QCD
Institute of Scientific and Technical Information of China (English)
LU Juan; CAI Xian-Hao; ZHOU Li-Juan
2012-01-01
Based on the generalized QCD vector meson dominance model,we study the electroproduction of a vector meson off a proton in the QCD inspired eikonalized model.Numerical calculations for the total cross section σtot and differential cross section dσ/dt are performed for p,ω and φ meson electroproduction in this paper.Since gluons interact among themselves (self-interaction),two gluons can form a glueball with quantum numbers IG,JPC =0+,2++,decay width Γt ≈ 100 MeV,and mass of mG=2.23 GeV.The three gluons can form a three-gluon colorless bound state with charge conjugation quantum number C =-1,called the Odderon.The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the virtual photon) and the proton target (a three-quark system) are the tensor glueball and the Odderon.Our calculated results in the tensor glueball and Odderon exchange model fit to the existing data successfully,which evidently shows that our present QCD mechanism is a good description of meson electroproduction off a proton.It should be emphasized that our mechanism is different from the theoretical framework of Block et al.We also believe that the present study and its success are important for the investigation of other vector meson electro- and photoproduction at high energies,as well as for searching for new particles such as tensor glueballs and Odderons,which have been predicted by QCD and the color glass condensate model (CGC).Therefore,in return,it can test the validity of QCD and the CGC model.
Vector meson electroproduction in QCD
Lu, Juan; Cai, Xian-Hao; Zhou, Li-Juan
2012-08-01
Based on the generalized QCD vector meson dominance model, we study the electroproduction of a vector meson off a proton in the QCD inspired eikonalized model. Numerical calculations for the total cross section σtot and differential cross section dσ/dt are performed for ρ, ω and varphi meson electroproduction in this paper. Since gluons interact among themselves (self-interaction), two gluons can form a glueball with quantum numbers IG, JPC = 0+,2++, decay width Γt ≈ 100 MeV, and mass of mG = 2.23 GeV. The three gluons can form a three-gluon colorless bound state with charge conjugation quantum number C = -1, called the Odderon. The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the virtual photon) and the proton target (a three-quark system) are the tensor glueball and the Odderon. Our calculated results in the tensor glueball and Odderon exchange model fit to the existing data successfully, which evidently shows that our present QCD mechanism is a good description of meson electroproduction off a proton. It should be emphasized that our mechanism is different from the theoretical framework of Block et al. We also believe that the present study and its success are important for the investigation of other vector meson electro- and photoproduction at high energies, as well as for searching for new particles such as tensor glueballs and Odderons, which have been predicted by QCD and the color glass condensate model (CGC). Therefore, in return, it can test the validity of QCD and the CGC model.
Electroweak Baryogenesis and Colored Scalars
Energy Technology Data Exchange (ETDEWEB)
Cohen, Timothy; /SLAC /Michigan U., MCTP; Pierce, Aaron; /Michigan U., MCTP
2012-02-15
We consider the 2-loop finite temperature effective potential for a Standard Model-like Higgs boson, allowing Higgs boson couplings to additional scalars. If the scalars transform under color, they contribute 2-loop diagrams to the effective potential that include gluons. These 2-loop effects are perhaps stronger than previously appreciated. For a Higgs boson mass of 115 GeV, they can increase the strength of the phase transition by as much as a factor of 3.5. It is this effect that is responsible for the survival of the tenuous electroweak baryogenesis window of the Minimal Supersymmetric Standard Model. We further illuminate the importance of these 2-loop diagrams by contrasting models with colored scalars to models with singlet scalars. We conclude that baryogenesis favors models with light colored scalars. This motivates searches for pair-produced di-jet resonances or jet(s) + = E{sub T}.
Nonleptonic two-body Bc-meson decays
Naimuddin, Sk.; Kar, Susmita; Priyadarsini, M.; Barik, N.; Dash, P. C.
2012-11-01
We study the exclusive nonleptonic two-body Bc decays within factorization approximation, in the framework of the relativistic independent quark model based on a confining potential in the scalar-vector harmonic form. The relevant weak form factors and branching ratios for different decay modes (Bc→PP,PV,VP) are predicted in reasonable agreement with other quark model predictions. We find that the dominant contribution to the Bc-meson lifetime comes from the Cabibbo-Kobayashi-Masakawa favored c¯→s¯, d¯ decay modes, and the most promising modes are found to be Bc-→B¯s0π-, Bc-→B¯s0ρ- and Bc-→B¯s⋆0π- with predicted branching ratios of 12.01, 9.96, and 8.61%, respectively, which might be easily detected at the hadron collider in the near future.
Electromagnetic form factors of heavy flavored vector mesons
Priyadarsini, M.; Dash, P. C.; Kar, Susmita; Patra, Sweta P.; Barik, N.
2016-12-01
We study the electromagnetic form factors of heavy flavored vector mesons such as (D*,Ds*,J /Ψ ) , (B*,Bs*,ϒ ) via one photon radiative decays (V →P γ ) in the relativistic independent quark (RIQ) model based on a flavor independent average interaction potential in the scalar vector harmonic form. The momentum dependent spacelike (q2<0 ) form factors calculated in this model are analytically continued to the physical timelike region 0 ≤q2≤(MV-MP)2 . The predicted coupling constant gV P γ=FV P(q2=0 ) for real photon case in the limit q2→0 and decay widths Γ (V →P γ ) are found in reasonable agreement with experimental data and other model predictions.
Quark Propagator and Meson Correlators in the QCD Vacuum
Sheel, V; Parikh, J C; Sheel, Varun; Mishra, Hiranmaya; Parikh, Jitendra C.
1997-01-01
Equal time, point to point correlation functions for spatially separated meson currents are calculated with respect to a variational construct for the ground state of QCD. Given such an ansatz we make no further approximations in the evaluation of the correlators. Our calculations for the vector, axial vector and scalar channels show qualitative agreement with the phenomenological predictions, whereas the pseudoscalar channel does not. However, the pseudoscalar correlator, when approximated by saturating with intermediate one pion states agrees with results obtained from spectral density functions parameterised by pion decay constant and $$ value obtained from chiral perturbation theory. We discuss this departure in the pseudoscalar channel, in context of the quark propagation in the vacuum.
Relativistic Many-Body Hamiltonian Approach to Mesons
Llanes-Estrada, F J; Llanes-Estrada, Felipe J.; Cotanch, Stephen R.
2002-01-01
We represent QCD at the hadronic scale by means of an effective Hamiltonian, $H$, formulated in the Coulomb gauge. As in the Nambu-Jona-Lasinio model, chiral symmetry is explicity broken, however our approach is renormalizable and also includes confinement through a linear potential with slope specified by lattice gauge theory. This interaction generates an infrared integrable singularity and we detail the computationally intensive procedure necessary for numerical solution. We focus upon applications for the $u, d, s$ and $c$ quark flavors and compute the mass spectrum for the pseudoscalar, scalar and vector mesons. We also perform a comparative study of alternative many-body techniques for approximately diagonalizing $H$: BCS for the vacuum ground state; TDA and RPA for the excited hadron states. The Dirac structure of the field theoretical Hamiltonian naturally generates spin-dependent interactions, including tensor, spin-orbit and hyperfine, and we clarify the degree of level splitting due to both spin an...
Finite Hypernuclei in the Latest Quark-Meson Coupling Model
Energy Technology Data Exchange (ETDEWEB)
Pierre A. M. Guichon; Anthony W. Thomas; Kazuo Tsushima
2007-12-12
The most recent development of the quark-meson coupling (QMC) model, in which the effect of the mean scalar field in-medium on the hyperfine interaction is also included self-consistently, is used to compute the properties of finite hypernuclei. The calculations for $\\Lambda$ and $\\Xi$ hypernuclei are of comparable quality to earlier QMC results without the additional parameter needed there. Even more significantly, the additional repulsion associated with the increased hyperfine interaction in-medium completely changes the predictions for $\\Sigma$ hypernuclei. Whereas in the earlier work they were bound by an amount similar to $\\Lambda$ hypernuclei, here they are unbound, in qualitative agreement with the experimental absence of such states. The equivalent non-relativistic potential felt by the $\\Sigma$ is repulsive inside the nuclear interior and weakly attractive in the nuclear surface, as suggested by the analysis of $\\Sigma$-atoms.
Low Scale Inflation at High Energy Colliders and Meson Factories
Bramante, Joseph; Delgado, Antonio; Martin, Adam
2016-01-01
Inflation occurring at energy densities less than (10$^{14}$ GeV)$^4$ produces tensor perturbations too small to be measured by cosmological surveys. However, we show that it is possible to probe low scale inflation by measuring the mass of the inflaton at low energy experiments. Detection prospects and cosmological constraints are determined for low scale quartic hilltop models of inflation paired with a curvaton field, which imprints the spectrum of scalar perturbations observed in large scale structure and on the cosmic microwave background. With cosmological constraints applied, low scale quartic inflation at energies GeV--PeV, can be mapped to an MeV--TeV mass inflaton resonance, discoverable through a Higgs portal coupling at upcoming collider and meson decay experiments. It is demonstrated that low scale inflatons can have detectably large couplings to Standard Model particles through a Higgs portal, permitting prompt reheating after inflation, without spoiling, through radiative corrections to the inf...
Scalar and Asymptotic Scalar Derivatives Theory and Applications
Isac, George
2008-01-01
This book is devoted to the study of scalar and asymptotic scalar derivatives and their applications to some problems in nonlinear analysis, Riemannian geometry and applied mathematics. The theoretical results are developed in particular with respect to the study of complementarity problems, monotonicity of nonlinear mappings and the non-gradient type monotonicity on Riemannian manifolds. Scalar and Asymptotic Derivatives: Theory and Applications also presents the material in relation to Euclidean spaces, Hilbert spaces, Banach spaces, Riemannian manifolds, and Hadamard manifolds. This book is
Direct CP Violation in Charmless Three-body Decays of $B$ Mesons
Cheng, Hai-Yang; Zhang, Zhi-Qing
2016-01-01
Direct CP violation in charmless three-body hadronic decays of $B$ mesons is studied within the framework of a simple model based on the factorization approach. Three-body decays of heavy mesons receive both resonant and nonresonant contributions. Dominant nonresonant contributions to tree-dominated and penguin-dominated three-body decays arise from the $b\\to u$ tree transition and $b\\to s$ penguin transition, respectively. The former can be evaluated in the framework of heavy meson chiral perturbation theory with some modification, while the latter is governed by the matrix element of the scalar density $\\langle M_1M_2|\\bar q_1 q_2|0\\rangle$. Strong phases in this work reside in effective Wilson coefficients, propagators of resonances and the matrix element of scalar density. In order to accommodate the branching fraction and CP asymmetries observed in $B^-\\to K^-\\pi^+\\pi^-$, the matrix element $\\langle K\\pi|\\bar sq|0\\rangle$ should have an additional strong phase, which might arise from some sort of power c...
Dynamics of strong and radiative decays of Ds-mesons in the hadrogenesis conjecture
Soyeur, Madeleine
2009-01-01
The positive parity scalar D$_{s0}^*$(2317) and axial-vector D$_{s1}^*$(2460) charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D(D$_s$)-meson ground states. The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian. Chiral corrections to order Q$_\\chi^2$ are calculated and found to be small. The D$_{s0}^*$(2317) and D$_{s1}^*$(2460) mesons decay either strongly into the isospin-violating $\\pi^0$D$_s$ and $\\pi^0$D$_s^*$ channels or electromagnetically. We show that the $\\pi^0$-$\\eta$ and (K$^0$D$^+$-K$^+$D$^0$) mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the $KD$ component of the states. The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral...
Hyperon stars in a modified quark meson coupling model
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2016-09-01
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a modified quark meson coupling model where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. The effect of a nonlinear ω -ρ term on the EOS is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of 2 M⊙ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear ω -ρ term in the context of obtaining the star mass constraint in the present set of parametrizations.
Spectra of heavy-light mesons in a relativistic model
Liu, Jing-Bin
2016-01-01
The spectra and wave functions of heavy-light mesons are calculated within a relativistic quark model, which is derived from the instantaneous Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation on the heavy quark. The kernel we choose is based on scalar confining and vector Coulomb potentials. The Hamiltonian for heavy-light quark-antiquark system is calculated up to order $1/m_Q^2$. The results are in good agreement with available experimental data except for the masses of the anomalous $D_{s0}^*(2317)$ and $D_{s1}(2460)$ states. The newly observed charmed meson states can be accommodated successfully in the relativistic model and their assignments are presented, the $D_{sJ}^*(2860)$ can be interpreted as the $|1^{3/2}D_1\\rangle$ and $|1^{5/2}D_3\\rangle$ states being the $J^P=1^-$ and $3^-$ members of the 1D family in our model.
Hyperon star in a modified quark meson coupling model
Mishra, R N; Panda, P K; Barik, N; Frederico, T
2016-01-01
We determine the equation of state (EOS) of nuclear matter with the inclusion of hyperons in a self-consistent manner by using a Modified Quark Meson Coupling Model (MQMC) where the confining interaction for quarks inside a baryon is represented by a phenomenological average potential in an equally mixed scalar-vector harmonic form. The hadron-hadron interaction in nuclear matter is then realized by introducing additional quark couplings to $\\sigma$, $\\omega$, and $\\rho$ mesons through mean-field approximations. The effect of a nonlinear $\\omega$-$\\rho$ term on the equation of state is studied. The hyperon couplings are fixed from the optical potential values and the mass-radius curve is determined satisfying the maximum mass constraint of $2$~M$_{\\odot}$ for neutron stars, as determined in recent measurements of the pulsar PSR J0348+0432. We also observe that there is no significant advantage of introducing the nonlinear $\\omega$-$\\rho$ term in the context of obtaining the star mass constraint in the present...
Strong and Electromagnetic Transitions in Heavy Flavor Mesons
Lähde, T A
2003-01-01
The electromagnetic and pionic transitions in mesons with heavy flavor quarks are calculated within the framework of the covariant Blankenbecler-Sugar equation. The M1 transitions in the charmonium system are shown to be sensitive to the relativistic aspect of the spin-flip magnetic moment operator, and the Lorentz structure of the Q\\bar Q interaction. The observed rate for the M1 transition J/psi -> eta_c gamma is shown to provide strong evidence for a scalar confining interaction. The single pion and dipion widths are calculated for the heavy-light D mesons, by employment of the pseudovector pion-quark coupling suggested by chiral perturbation theory. The pionic transitions D* -> D pi are shown to provide constraining information on the pion-quark axial coupling g_A^q. It is also shown that axial exchange charge contributions associated with the Q\\bar q interaction suppress the axial charge amplitude for pion emission by an order of magnitude. The models for pi and M1 transitions also make it possible to es...
Spectra of heavy-light mesons in a relativistic model
Energy Technology Data Exchange (ETDEWEB)
Liu, Jing-Bin; Lue, Cai-Dian [Institute of High Energy Physics, Beijing (China)
2017-05-15
The spectra and wave functions of heavy-light mesons are calculated within a relativistic quark model which is based on a heavy-quark expansion of the instantaneous Bethe-Salpeter equation by applying the Foldy-Wouthuysen transformation. The kernel we choose is the standard combination of linear scalar and Coulombic vector. The effective Hamiltonian for heavy-light quark-antiquark system is calculated up to order 1/m{sub Q}{sup 2}. Our results are in good agreement with available experimental data except for the anomalous D{sub s0}{sup *}(2317) and D{sub s1}(2460) states. The newly observed heavy-light meson states can be accommodated successfully in the relativistic quark model with their assignments presented. The D{sub sJ}{sup *}(2860) can be interpreted as the vertical stroke 1{sup 3/2}D{sub 1} right angle and vertical stroke 1{sup 5/2}D{sub 3} right angle states being members of the 1D family with J{sup P} = 1{sup -} and 3{sup -}. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Mendoza S, J.A.; Ramirez, C.A. [Depto. de Fisica-Geologia, Universidad de Pamplona, Pamplona, Norte de Santander, Colombia, Escuela de Fisica, Universidad Industrial de Santander, A.A. 678, Bucaramanga (Colombia)]. e-mail: jairoam@unipamplona.edu.co
2007-07-01
We calculate the branching ratios for the decays B {yields} K{sub 0}{sup *}{pi} and B {yields} F{sub 0}k, in the 'Naive Factorization (NFA)' approximation, The dipole penguin operator O{sub 11} contributions are included and the scalar mesons are considered as qq{sup -} bounded states. We compare, favorably our results with the experimental available data. (Author)
Leitão, Sofia; Stadler, Alfred; Peña, M. T.; Biernat, Elmar P.
2017-01-01
The Covariant Spectator Theory (CST) is used to calculate the mass spectrum and vertex functions of heavy-light and heavy mesons in Minkowski space. The covariant kernel contains Lorentz scalar, pseudoscalar, and vector contributions. The numerical calculations are performed in momentum space, where special care is taken to treat the strong singularities present in the confining kernel. The observed meson spectrum is very well reproduced after fitting a small number of model parameters. Remarkably, a fit to a few pseudoscalar meson states only, which are insensitive to spin-orbit and tensor forces and do not allow to separate the spin-spin from the central interaction, leads to essentially the same model parameters as a more general fit. This demonstrates that the covariance of the chosen interaction kernel is responsible for the very accurate prediction of the spin-dependent quark-antiquark interactions.
Leitão, Sofia; Peña, M T; Biernat, Elmar P
2016-01-01
The Covariant Spectator Theory (CST) is used to calculate the mass spectrum and vertex functions of heavy-light and heavy mesons in Minkowski space. The covariant kernel contains Lorentz scalar, pseudoscalar, and vector contributions. The numerical calculations are performed in momentum space, where special care is taken to treat the strong singularities present in the confining kernel. The observed meson spectrum is very well reproduced after fitting a small number of model parameters. Remarkably, a fit to a few pseudoscalar meson states only, which are insensitive to spin-orbit and tensor forces and do not allow to separate the spin-spin from the central interaction, leads to essentially the same model parameters as a more general fit. This demonstrates that the covariance of the chosen interaction kernel is responsible for the very accurate prediction of the spin-dependent quark-antiquark interactions.
Spherically symmetric scalar field collapse
Indian Academy of Sciences (India)
Koyel Ganguly; Narayan Banerjee
2013-03-01
It is shown that a scalar field, minimally coupled to gravity, may have collapsing modes even when the energy condition is violated, that is, for ( + 3) < 0. This result may be useful in the investigation of the possible clustering of dark energy. All the examples dealt with have apparent horizons formed before the formation of singularity. The singularities formed are shell focussing in nature. The density of the scalar field distribution is seen to diverge at singularity. The Ricci scalar also diverges at the singularity. The interior spherically symmetric metric is matched with exterior Vaidya metric at the hypersurface and the appropriate junction conditions are obtained.
Exclusive meson production at COMPASS
Sznajder, Paweł
2014-01-01
In this paper we summarize recent measurements of exclusive meson production performed by the COMPASS Collaboration. In particular, recent results on the transverse target spin asymmetries for exclusive r 0 production are presented. Some of these asymmetries are sensitive to the GPDs E , which are related to the orbital angular momentum of quarks. Other asymmetries are sensitive to the chiral-odd, transverse GPDs H T . Measurements of exclusive processes, which are a part of the COMPASS-II proposal, are also discussed
Durgut, Suleyman; CMS Collaboration
2017-01-01
Exotic meson spectroscopy searches at the LHC yielded interesting results. Using an integrated luminosity of 25 . 6fb-1 recorded in proton-proton collisions at √{ 7} TeV and √{ 8} TeV, CMS searched for enhancements in multi-lepton final states in the mass range below the ϒ(1 S) ϒ(1 S) mass. Results will be presented and discussed.
Matching the Heavy Vector Meson Theory
Bijnens, J; Talavera, P
1998-01-01
We show how to obtain a ``heavy'' meson effective lagrangian for the case where the number of heavy particles is not conserved. We apply the method in a simple example at tree level and perform then the reduction for the case of vector mesons in Chiral Perturbation Theory in a manifestly chiral invariant fashion. Some examples showing that ``heavy'' meson effective theory also works at the one-loop level are included.
In-medium properties of mesons
Metag, Volker; Nanova, Mariana; Brinkmann, Kai-Thomas
2017-01-01
In the project B.4, the modification of meson properties (mass, width) in a nuclear medium has been studied in photoproduction of mesons off nuclear targets. This work has been motivated by theoretical expectations of in-medium modifications of hadrons based on the conjecture of a partial restoration of chiral symmetry in a strongly interacting medium. It has been shown that these in-medium changes can be discussed in a compact form in terms of an optical potential describing the meson-nucleus interaction. Experimental approaches to determine the real and imaginary part of the meson-nucleus potential have been developed. The experiments have been performed with the Crystal Barrel/TAPS detector at the electron accelerator ELSA (Bonn) and the Crystal Ball/TAPS detector at MAMI (Mainz). Measuring the excitation function and momentum distribution for photo production of ω and η' mesons, the real parts of the ω and η'-nucleus potential, given by the in-medium mass shift, have been determined. For the η' meson a lowering of the mass at normal nuclear matter density by -(39±7(stat)±15(syst)) MeV is observed, while for the ω meson a slightly smaller mass shift is found, however, with much larger uncertainties, not excluding a zero mass shift. The imaginary part of the potentials has been extracted from the measurement of the transparency ratio which compares the meson production cross section per nucleon within a nucleus to the production cross section off the free proton. For the η' meson the imaginary part of the potential is found to be smaller than the real part. In case of the ω meson the opposite is observed. This makes the η' meson a good candidate for the search for meson-nucleus bound states while no resolved ω mesic states can be expected. The results are compared with theoretical predictions. An outlook on future experiments is given.
Diffractive Leptoproduction of Vector Mesons in QCD
Brodsky, Stanley J.; Frankfurt, L.; Gunion, J. F.; Mueller, A.H.; Strikman, M.
1994-01-01
We demonstrate that the distinctive features of the forward differential cross section of diffractive leptoproduction of a vector meson can be legitimately calculated in perturbative QCD in terms of the light-cone $q \\bar q$ wave function of the vector meson and the gluon distribution of the target. In particular, we calculate the $Q^2$ and nuclear dependence of the diffractive leptoproduction of vector mesons and estimate the cross section. The production of longitudinally polarized vector m...
Exclusive meson production at HERMES
Manaenkov, Sergey
2016-01-01
The data were accumulated with the HERMES forward spectrometer using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. Exclusive electroproduction of $\\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of $Q^2>1.0$ GeV$^2$, 3.0 GeV $< W <$ 6.3 GeV, and $-t'< 0.2 $ GeV$^{2}$, while for $\\rho^0$-meson production on a transversely polarized hydrogen target $-t'< 0.4$ GeV$^{2}$ is used. Spin-density matrix elements for $\\omega$ production are presented in projections of $Q^2$ or $-t'$, while the ratios of the helicity amplitudes for the reaction $\\gamma^*+p \\to \\rho^0+p$ are obtained in the entire kinematic region. The usage of the transversely polarized target allows for the first time the extraction of the ratios of certain nucleon-helicity-flip amplitudes to the natural-parity exchange amplitude $T_{0\\frac{1}{2}0\\frac{1}{2}}$ without the nucleon-helicity flip describing the longitudinal $\\rho^0$-meson production by the longitudinal...
Heavy and light meson wavefunctions
Wu, Xing-Gang
2013-01-01
We present a short review on the properties of heavy and light mesons' light-cone wavefunctions (LCWFs), and their distribution amplitudes (DAs). The B meson LCWFs can be treated by taking the heavy quark limit ($m_b\\to\\infty$) and by using the heavy quark effective theory (HQET). Using the relations between 2- and 3- particle WFs derived from the QCD equations of motion and constraints from the heavy quark symmetry, one can obtain their transverse momentum dependence up to next-to-leading order in Fock state expansion. Furthermore, we propose a simple model for B meson WFs with 3-particle Fock states' contributions, whose behaviors are controlled by two parameters $\\bar\\Lambda$ and $\\delta$. Using such model, the form factors $F^{B\\to\\pi}_{+,0,T}$ and $F^{B\\to K}_{+,0,T}$ in large recoil region are studied up to ${\\cal O}(1/m_b^2)$ within the $k_T$ factorization approach. When $\\bar\\Lambda\\in [0.50,0.55]$ and $\\delta\\in[0.25,0.30]$, the results of $F^{B\\to\\pi}_{+,0,T}(Q^2)$ and $F^{B\\to K}_{+,0,T}(Q^2)$ are ...
Allen, Mark T.
In the Standard Model (SM) of particle physics, the charged-current couplings of the quark sector are described by the Cabibho-Kobayashi-Maskawa (CKM) matrix elements Vqq' . The consistency of multiple measurements of the sides and angles of the CKM Unitarity Triangle provides a stringent test of the SM, and also provides constraints on non-SM physics. The CKM angle alpha can be measured from the interference between B0 → pi + pi- decays with and without B 0 ↔ B¯0 mixing, in combination with the isospin related decays B+ → pi + pi- and B0 → pi 0 pi0. The B → Kpi system also exhibits interesting CP-violating features, including direct CP violation in B0 → K+pi- decays. Sum rules derived from U-spin symmetry and parameters from the B → pipi system relate the branching fraction and charge asymmetry of B +/- → K+/-pi 0 decays to other decays in the Kpi system. Based on a sample of 383 x 106 U (4S) → BB¯ decays, we report updated measurements of the branching fraction for B 0 → pi0pi0 and the time-integrated CP asymmetry, Cp0p0 . We also measure the branching fractions for B +/- → h+/-pi 0 (h+/- = pi+/- , K+/-) and the corresponding charge asymmetries Ah+/-p 0 . We find the branching ratios and asymmetries: B (B0 → pi0pi 0) = (1.47 +/- 0.25 +/- 0.12) x 10-6, B (B+/- → pi+/- pi0 = (5.02 +/- 0.46 +/- 0.29) x 10 -6, B (B+/- K +/-pi0) = (13.56 +/- 0.56 +/- 0.68) x 10-6, Cp0p0 = -0.49 +/- 0.35 +/- 0.04, Ap+/-p 0 = 0.03 +/- 0.08 +/- 0.01, and AK+/-p 0 = 0.030 +/- 0.039 +/- 0.010. Finally, we present bounds on the CKM angle alpha using isospin relations.
Effective non-Coulombic power-law potential for the study of light and heavy mesons
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1982-08-01
From purely phenomenological considerations we have shown that it is possible to describe successfully the heavy meson spectra of cc-bar and bb-bar systems in the framework of an effective non-Coulombic power-law potential in the form V(r) = V/sub 0/+ar/sup ..nu../ (with a,..nu..>0). The nonsingular short-distance behavior of this potential, which is in apparent contradiction with the predictions of quantum- chromodynamics, does not pose any problem in explaining the fine-hyperfine splitting, if we prescribe the spin dependence to be generated through this static confining potential in the form of an approximately equal admixture of scalar and vector parts with no contributions from the anomalous quark magnetic moments. This nonrelativistic formalsm, when extended to a unified study of the entire meson spectra including the ordinary light and the heavy mesons, gives a very good account of the meson masses, fine-hyperfine splittings, electromagnetic transition rates, and leptonic decay widths without reflecting any inadequacy in the short- and long-range behavior of this simple effective power-law potential.
Non-self-conjugate mesons in a potential model with vacuum-polarization corrections
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1980-10-01
We present a unified approach to the study of non-self-conjugate mesons including both light and heavy mesons in the framework of the vacuum-polarization-corrected flavor-independent potential. We have found that the quark-confining potential in the form of an almost equal admixture of vector and scalar parts successfully explains the S-wave hyperfine levels of the observed light and heavy mesons. Finally we calculate the electromagnetic mass differences of the heavy-quark mesons and obtain (K-bar*/sup 0/-K*/sup -/)=3.79 MeV, (K-bar/sup 0/-K/sup -/)=6 MeV, (D*/sup +//sub c/-D*/sup 0//sub c/)=2.4 MeV, (D/sup +//sub c/-D/sup 0//sub c/)=5.8 MeV, (D*/sup 0//sub b/-D*/sup -//sub b/)=3.547 MeV, and (D/sup 0//sub b/-D/sup -//sub b/)=3.558 MeV.
Central Production of Two-Pseudoscalar Meson Systems at the COMPASS Experiment at CERN
Austregesilo, Alexander; Mallot, Gerhard
The question of the existence of glueballs is one of the unsolved problems in modern particle physics and can be regarded as a stringent test for quantum chromodynamics. Especially the supernumerous states in the light scalar meson spectrum are candidates for the observation of mixing effects between $q\\bar q$ mesons and pure gluonic bound states. On the other hand, the existence and the properties of many resonances in this sector are disputed. The COMPASS experiment was proposed to make significant contributions to this field. COMPASS is a fixed-target experiment at the CERN SPS which focused on light-quark hadron spectroscopy during the data taking periods in 2008 and 2009. A world-leading data set was collected with a $190\\,\\mathrm{GeV}/c$ hadron beam impinging on a liquid hydrogen target in order to study, inter alia, the central production of glueball candidates in the light meson sector. Especially the double-Pomeron exchange mechanism is well suited for the production of mesons without valenc...
Meson effective mass in the isospin medium in hard-wall AdS/QCD model
Energy Technology Data Exchange (ETDEWEB)
Mamedov, Shahin [Gazi University, Department of Physics, Ankara (Turkey); Baku State University, Institute for Physical Problems, Baku (Azerbaijan); Azerbaijan National Academy of Sciences, Institute of Physics, Baku (Azerbaijan)
2016-02-15
We study a mass splitting of the light vector, axial-vector, and pseudoscalar mesons in the isospin medium in the framework of the hard-wall model. We write an effective mass definition for the interacting gauge fields and scalar field introduced in gauge field theory in the bulk of AdS space-time. Relying on holographic duality we obtain a formula for the effective mass of a boundary meson in terms of derivative operator over the extra bulk coordinate. The effective mass found in this way coincides with the one obtained from finding of poles of the two-point correlation function. In order to avoid introducing distinguished infrared boundaries in the quantization formula for the different mesons from the same isotriplet we introduce extra action terms at this boundary, which reduces distinguished values of this boundary to the same value. Profile function solutions and effective mass expressions were found for the in-medium ρ, a{sub 1}, an π mesons. (orig.)
Supernova Equation of State with an extended SU(3) Quark-Meson Model
Beisitzer, Thomas; Schaffner-Bielich, Juergen
2014-01-01
The quark-meson model is investigated for the two- and three-flavor case extended by contributions of vector mesons under conditions encountered in core-collapse supernova matter. Typical temperature ranges, densities and electron fractions, as found in core-collapse supernova simulations, are studied by implementing charge neutrality and local beta-equilibrium with respect to weak interactions. Within this framework, we analyze the resulting phase diagram and equation of state (EoS) and investigate the impact of undetermined parameters of the model. The EoS turns out to be relatively independent on the entropy per baryon but there are significant changes when going from the two-flavor to the three-flavor case due to the nontrivial contribution from the strange quarks which stay massive even at high densities. While an increasing vector meson coupling constant leads to a substantial stiffening of the EoS, we find that the impact of changing the scalar meson mass is equally strong and results in a softening of...
Gubler, Philipp; Lee, Su Houng; Oka, Makoto; Ozaki, Sho; Suzuki, Kei
2015-01-01
We investigate the mass spectra of open heavy flavor mesons in an external constant magnetic field within QCD sum rules. Spectral ans\\"atze on the phenomenological side are proposed in order to properly take into account mixing effects between the pseudoscalar and vector channels, and the Landau levels of charged mesons. The operator product expansion is implemented up to dimension--5 operators. As a result, we find for neutral D mesons a significant positive mass shift that goes beyond simple mixing effects. In contrast, charged D mesons are further subject to Landau level effects, which together with the mixing effects almost completely saturate the mass shifts obtained in our sum rule analysis.
Meson's Correlation Functions in a Nuclear Medium
Park, Chanyong
2016-01-01
We investigate meson's spectrum, decay constant and form factor in a nuclear medium through holographic two- and three-point correlation functions. To describe a nuclear medium composed of protons and neutrons, we consider a hard wall model on the thermal charged AdS geometry and show that due to the isospin interaction with a nuclear medium, there exist splittings of the meson's spectrum, decay constant and form factor relying on the isospin charge. In addition, we show that the rho-meson's form factor describing an interaction with pseudoscalar fluctuation decreases when the nuclear density increases, while the interaction with a longitudinal part of an axial vector meson increases.
Meson's correlation functions in a nuclear medium
Park, Chanyong
2016-09-01
We investigate meson's spectrum, decay constant and form factor in a nuclear medium through holographic two- and three-point correlation functions. To describe a nuclear medium composed of protons and neutrons, we consider a hard wall model on the thermal charged AdS geometry and show that due to the isospin interaction with a nuclear medium, there exist splittings of the meson's spectrum, decay constant and form factor relying on the isospin charge. In addition, we show that the ρ-meson's form factor describing an interaction with pseudoscalar fluctuation decreases when the nuclear density increases, while the interaction with a longitudinal part of an axial vector meson increases.
Unraveling the pattern of the XYZ mesons
Directory of Open Access Journals (Sweden)
J. Vijande
2014-09-01
Full Text Available We present a plausible mechanism for the origin of the XYZ mesons in the heavy meson spectra within a standard quark-model picture. We discuss the conditions required for the existence of four-quark bound states or resonances contributing to the heavy meson spectra, being either compact or molecular. We concentrate on charmonium and bottomonium spectra, where several new states, difficult to understand as simple quark–antiquark pairs, have been reported by different experimental collaborations. The pivotal role played by entangled meson–meson thresholds is emphasized.
Single spin asymmetry for charm mesons
Energy Technology Data Exchange (ETDEWEB)
Dominguez Zacarias, G. [PIMAyC, Eje Central Lazaro Cardenas No. 152, Apdo. Postal 14-805, D.F. (Mexico); Herrera, G.; Mercado, J. [Centro de Investigacion y de Estudios Avanzados, Apdo. Postal 14-740, D.F. (Mexico)
2007-08-15
We study single spin asymmetries of D{sup 0} and D{sup -} mesons in polarized proton-proton collisions. A two component model is used to describe charm meson production. The production of D mesons occurs by recombination of the constituents present in the initial state as well as by fragmentation of quarks in the final state. This model has proved to describe the production of charm. The recombination component involves a mechanism of spin alignment that ends up in a single spin asymmetry. Experimental measurements of single spin asymmetry for pions at RHIC are compared with the model. Predictions for the asymmetry in D mesons are presented. (orig.)
Spin-1 diquark contributing to the formation of tetraquarks in light mesons
Kim, Hungchong; Kim, K S
2016-01-01
We apply a mixing framework to light meson systems and examine the tetraquark possibility in the scalar channel ($J=0$). In the diquark-antidiquark model, a scalar diquark is a compact object when its color and flavor structures are in ($\\bar{\\bm{3}}_c$, $\\bar{\\bm{3}}_f$). Assuming that all the quarks are in an $S$-wave, the spin-0 tetraquark formed out of this scalar diquark has only one spin configuration, $|J,J_{12},J_{34}\\rangle=|000\\rangle$, where $J$ is the spin of the tetraquark, $J_{12}$ the diquark spin, $J_{34}$ the antidiquark spin. In the construction of the scalar tetraquark, we notice that another compact diquark with spin-1 in ($\\bm{6}_c$, $\\bar{\\bm{3}}_f$) can be used although it is less compact than the scalar diquark. The spin-0 tetraquark formed with this vector diquark leads to the spin configuration $|J,J_{12},J_{34}\\rangle=|011\\rangle$. The two configurations, $|000\\rangle$ and $|011\\rangle$, are found to mix strongly through the color-spin interaction. The physical states can be identif...
Large N Scalars: From Glueballs to Dynamical Higgs Models
Sannino, Francesco
2015-01-01
We construct effective Lagrangians, and corresponding counting schemes, valid to describe the dynamics of the lowest lying large N stable massive composite state emerging in strongly coupled theories. The large N counting rules can now be employed when computing quantum corrections via an effective Lagrangian description. The framework allows for systematic investigations of composite dynamics of non-Goldstone nature. Relevant examples are the lightest glueball states emerging in any Yang-Mills theory. We further apply the effective approach and associated counting scheme to composite models at the electroweak scale. To illustrate the formalism we consider the possibility that the Higgs emerges as: the lightest glueball of a new composite theory; the large N scalar meson in models of dynamical electroweak symmetry breaking; the large N pseudodilaton useful also for models of near-conformal dynamics. For each of these realisations we determine the leading N corrections to the electroweak precision parameters. ...
Inflation and the Higgs Scalar
Energy Technology Data Exchange (ETDEWEB)
Green, Dan [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
2014-12-05
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A simple scalar model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
Inflation and the Higgs Scalar
Green, Dan
2014-01-01
This note makes a self-contained exposition of the basic facts of big bang cosmology as they relate to inflation. The fundamental problems with that model are then explored. A quartic scalar potential model of inflation is evaluated which provides the solution of those problems and makes predictions which will soon be definitively tested. The possibility that the recently discovered fundamental Higgs scalar field drives inflation is explored.
Nuclear symmetry energy in a modified quark-meson coupling model
Mishra, R. N.; Sahoo, H. S.; Panda, P. K.; Barik, N.; Frederico, T.
2015-10-01
We study nuclear symmetry energy and the thermodynamic instabilities of asymmetric nuclear matter in a self-consistent manner by using a modified quark-meson coupling model where the confining interaction for quarks inside a nucleon is represented by a phenomenologically averaged potential in an equally mixed scalar-vector harmonic form. The nucleon-nucleon interaction in nuclear matter is then realized by introducing additional quark couplings to σ ,ω , and ρ mesons through mean-field approximations. We find an analytic expression for the symmetry energy Esym as a function of its slope L . Our result establishes a linear correlation between L and Esym. We also analyze the constraint on neutron star radii in (p n ) matter with β equilibrium.
Up sector of minimal flavor violation: top quark properties and direct D meson CP violation
Energy Technology Data Exchange (ETDEWEB)
Bai, Yang; Berger, Joshua; Hewett, JoAnne L.; Li, Ye
2013-07-01
Minimal Flavor Violation in the up-type quark sector leads to particularly interesting phenomenology due to the interplay of flavor physics in the charm sector and collider physics from flavor changing processes in the top sector. We study the most general operators that can affect top quark properties and D meson decays in this scenario, concentrating on two CP violating operators for detailed studies. The consequences of these effective operators on charm and top flavor changing processes are generically small, but can be enhanced if there exists a light flavor mediator that is a Standard Model gauge singlet scalar and transforms under the flavor symmetry group. This flavor mediator can satisfy the current experimental bounds with a mass as low as tens of GeV and explain observed D-meson direct CP violation. Additionally, the model predicts a non-trivial branching fraction for a top quark decay that would mimic a dijet resonance.
Continuum extrapolation of finite temperature meson correlation functions in quenched lattice QCD
Francis, Anthony
2010-01-01
We explore the continuum limit $a\\rightarrow 0$ of meson correlation functions at finite temperature. In detail we analyze finite volume and lattice cut-off effects in view of possible consequences for continuum physics. We perform calculations on quenched gauge configurations using the clover improved Wilson fermion action. We present and discuss simulations on isotropic $N_\\sigma^3\\times 16$ lattices with $N_\\sigma=32,48,64,128$ and $128^3 \\times N_\\tau$ lattices with $N_\\tau=16,24,32,48$ corresponding to lattice spacings in the range of $0.01 fm \\lsim a \\lsim\\ 0.031 fm$ at $T\\simeq1.45T_c$. Continuum limit extrapolations of vector meson and pseudo scalar correlators are performed and their large distance expansion in terms of thermal moments is introduced. We discuss consequences of this analysis for the calculation of the electrical conductivity of the QGP at this temperature.
The quark-meson coupling model for $\\Lambda$, $\\Sigma$ and $\\Xi$ hypernuclei
Tsushima, K; Haidenbauer, J; Thomas, A W
1998-01-01
The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both infinite nuclear matter and finite nuclei, is applied to a systematic study of $\\Lambda, \\Sigma$ and $\\Xi$ hypernuclei. Assumptions made in the present study are, (i) the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, and (ii) an SU(6) valence quark model for the bound nucleons and hyperon. The model automatically leads to a very weak spin-orbit interaction for the $\\Lambda$ in a hypernucleus. Effects of the Pauli blocking at the quark level, and the $\\Sigma N - \\Lambda N$ channel coupling (strong conversion), are also taken into account in a phenomenological way.
Quarkonia and heavy-light mesons in a covariant quark model
Directory of Open Access Journals (Sweden)
Leitão Sofia
2016-01-01
Full Text Available Preliminary calculations using the Covariant Spectator Theory (CST employed a scalar linear confining interaction and an additional constant vector potential to compute the mesonic mass spectra. In this work we generalize the confining interaction to include more general structures, in particular a vector and also a pseudoscalar part, as suggested by a recent study [1]. A one-gluon-exchange kernel is also implemented to describe the short-range part of the interaction. We solve the simplest CST approximation to the complete Bethe-Salpeter equation, the one-channel spectator equation, using a numerical technique that eliminates all singularities from the kernel. The parameters of the model are determined through a fit to the experimental pseudoscalar meson spectra, with a good agreement for both quarkonia and heavy-light states.
A decreased probability of habitable planet formation around low-mass stars
Raymond, Sean N; Meadows, Victoria
2007-01-01
Smaller terrestrial planets ( 0.3 Earth mass habitable planets decreases for low-mass stars for every realistic combination of parameters. This "habitable fraction" is small for stellar masses below a mass in the interval 0.5 to 0.8 Solar masses, depending on disk parameters, an interval that excludes most M stars. Radial mixing and therefore water delivery are inefficient in lower-mass disks commonly found around low-mass stars, such that terrestrial planets in the habitable zones of most low-mass stars are likely to be small and dry.
Open charm-bottom scalar tetraquarks and their strong decays
Agaev, S S; Sundu, H
2016-01-01
The mass and meson-current coupling of the diquark-antidiquark states with the quantum numbers $J^{P}=0^{+}$ and quark contents $Z_{q}=[cq][\\bar {b} \\bar q ]$ and $Z_{s}=[cs][\\bar {b} \\bar s]$ are calculated using two-point QCD sum rule approach. In calculations the quark, gluon and mixing condensates up to eight dimensions are taken into account. The parameters of the scalar tetraquarks extracted from this analysis are employed to explore the strong vertices $Z_q B_c \\pi $, $Z_q B_c \\eta $ and $Z_s B_c \\eta $ and compute the couplings $g_{Z_qB_c \\pi }$, $g_{Z_qB_c \\eta }$ and $g_{Z_sB_c \\eta }$. The strong couplings are obtained within the soft-meson approximation of QCD light-cone sum rule method: they form, alongside with other parameters, the basis for evaluating the widths of $Z_q \\to B_c \\pi$, $% Z_q \\to B_c \\eta$ and $Z_s \\to B_c \\eta$ decays. Obtained in this work results for the mass of the tetraquarks $Z_{q}$ and $Z_{s}$ are compared with available predictions presented in the literature.
Search for a Scalar Bottom Quark with Mass 3.5-4.5 GeV/$c^{2}$
Savinov, V; Fadeev, V; Gao, Y S; Maravin, Y; Narsky, I; Stroynowski, R; Ye, J; Wlodek, T; Artuso, M; Ayad, R; Boulahouache, C; Bukin, K; Dambasuren, E; Karamov, S; Majumder, G; Moneti, G C; Mountain, R; Schuh, S; Skwarnicki, T; Stone, S; Wang, J C; Wolf, A; Wu, J; Kopp, S E; Kostin, M A; Mahmood, A H; Csorna, S E; Danko, I; McLean, K W; Xu, Z; Godang, R; Bonvicini, G; Cinabro, D; Dubrovin, M; McGee, S; Zhou, G J; Lipeles, E; Pappas, S P; Schmidtler, M; Shapiro, A; Sun, W M; Weinstein, A J; Würthwein, F; Jaffe, D E; Masek, G E; Paar, H P; Potter, E M; Prell, S; Asner, D M; Eppich, A; Hill, T S; Morrison, R J; Briere, R A; Chen, G P; Gritsan, A; Alexander, J P; Baker, R; Bebek, C; Berger, B E; Berkelman, K; Blanc, F; Boisvert, V; Cassel, David G; Drell, P S; Duboscq, J E; Ecklund, K M; Ehrlich, R; Foland, A D; Gaidarev, P B; Galik, R S; Gibbons, L K; Gittelman, B; Gray, S W; Hartill, D L; Heltsley, B K; Hopman, P I; Hsu, L; Jones, C D; Kandaswamy, J; Kreinick, D L; Lohner, M; Magerkurth, A; Meyer, T O; Mistry, N B; Nordberg, E; Palmer, M; Patterson, J R; Peterson, D; Riley, D; Romano, A; Thayer, J G; Urner, D; Valant-Spaight, B L; Viehhauser, G; Warburton, A; Avery, P; Prescott, C; Rubiera, A I; Stöck, H; Yelton, J; Brandenburg, G; Ershov, A; Kim, D Y J; Wilson, R; Bergfeld, T; Eisenstein, B I; Ernst, J; Gladding, G E; Gollin, G D; Hans, R M; Johnson, E; Karliner, I; Marsh, M A; Plager, C; Sedlack, C; Selen, M; Thaler, J J; Williams, J; Edwards, K W; Janicek, R; Patel, P M; Sadoff, A J; Ammar, R; Bean, A; Besson, D; Zhao, X; Anderson, S; Frolov, V V; Kubota, Y; Lee, S J; Mahapatra, R; O'Neill, J J; Poling, R A; Riehle, T; Smith, A; Stepaniak, C J; Urheim, J; Ahmed, S; Alam, M S; Athar, S B; Jian, L; Ling, L; Saleem, M; Timm, S; Wappler, F; Anastassov, A; Eckhart, E; Gan, K K; Gwon, C; Hart, T; Honscheid, K; Hufnagel, D; Kass, R; Pedlar, T K; Schwarthoff, H; Thayer, J B; Von Törne, E; Zoeller, M M; Richichi, S J; Severini, H; Skubic, P L; Undrus, A; Chen, S; Fast, J; Hinson, J W; Lee, J; Miller, D H; Shibata, E I; Shipsey, I P J; Pavlunin, V; Cronin-Hennessy, D; Lyon, A L; Thorndike, E H
2001-01-01
We report on a search for a supersymmetric $\\tilde{B}$ meson with mass between 3.5 and 4.5 GeV/$c^2$ using 4.52 ${\\rm fb}^{-1}$ of integrated luminosity produced at $\\sqrt{s}=10.52$ GeV, just below the $e^+e^-\\to B\\bar{B}$ threshold, and collected with the CLEO detector. We find no evidence for a light scalar bottom quark.
Cannon, John M.; McNichols, Andrew; Teich, Yaron; Adams, Elizabeth A.; Giovanelli, Riccardo; Haynes, Martha P.; McQuinn, Kristen B.; Salzer, John Joseph; Skillman, Evan D.; Dolphin, Andrew E.; Elson, Edward C.; Haurberg, Nathalie C.; Huang, Shan; Janowiecki, Steven; Jozsa, Gyula; Leisman, Luke; Ott, Juergen; Papastergis, Emmanouil; Rhode, Katherine L.; Saintonge, Amelie; Van Sistine, Angela; Warren, Steven R.
2017-01-01
The “Survey of HI in Extremely Low-mass Dwarfs” (SHIELD) is a multiwavelength study of local volume low-mass galaxies drawn from the Arecibo Legacy Fast ALFA (ALFALFA) catalog. HST/Spitzer joint program GO-12658 revealed the stellar populations of the first 12 SHIELD galaxies (Cannon et al. 2011), allowing accurate distance measurements (McQuinn et al. 2014) and detailed studies of the patterns of recent star formation in each galaxy (McQuinn et al. 2015). These HST and Spitzer images are a critical interpretive benchmark for ground-based optical imaging and spectroscopy (Haurberg et al. 2015), as well as for sensitive VLA HI spectral line imaging of the SHIELD galaxies (McNichols et al. 2016; Teich et al. 2016). These results have furthered our understanding of the evolution of galaxies in a mass regime that was previously only sparsely populated. With the low-redshift ALFALFA catalog now complete, the scope of the SHIELD program has been expanded to include all 82 galaxies that meet distance, line width, and HI flux criteria for being gas-rich, low-mass galaxies. In HST program 13750, images of 18 more SHIELD galaxies have again set the physical scales for supporting HI spectral line imaging with both the VLA and the WSRT (Gordon et al. 2016). Taken as a whole, the ongoing SHIELD program is one of the most comprehensive multiwavelength studies of the physical properties of low-mass galaxies outside of the Local Group.
Isospin violating decays of positive parity B{sub s} mesons in HMχPT
Energy Technology Data Exchange (ETDEWEB)
Fajfer, Svjetlana [University of Ljubljana, Department of Physics, Ljubljana (Slovenia); J. Stefan Institute, Jamova 39, P. O. Box 3000, Ljubljana (Slovenia); Prapotnik Brdnik, Anita [J. Stefan Institute, Jamova 39, P. O. Box 3000, Ljubljana (Slovenia); University of Maribor, Faculty of Civil Engineering, Transportation Engineering and Architecture, Maribor (Slovenia)
2016-10-15
Recent lattice QCD results suggest that the masses of the first two positive parity B{sub s} mesons lie below the BK threshold, similar to the case of D{sup *}{sub s0}(2317){sup +} and D{sub s1}(2460){sup +} mesons. The mass spectrum of B{sub s} mesons seems to follow the pattern of a D{sub s} mass spectrum. As in the case of charmed mesons, the structure of positive parity B{sub s} mesons is very intriguing. To shed more light on this issue, we investigate the strong isospin violating decays B{sub s0}{sup *0} → B{sub s}{sup 0}π{sup 0}, B{sub s1}{sup 0} → B{sub s}{sup *0}π{sup 0}, and B{sub s1}{sup 0} → B{sub s}{sup 0}ππ within heavy meson chiral perturbation theory. The two-body decay amplitude arises at tree level and we show that the loop corrections give significant contributions. On the other hand, in the case of three-body decay B{sub s1}{sup 0} → B{sub s}{sup 0}ππ the amplitude occurs only at loop level. We find that the decay widths for these decays are Γ(B{sub s1}{sup 0} → B{sub s}{sup 0}ππ) ∝ 10{sup -3} keV, and Γ(B{sub s0}{sup *0} → B{sub s}{sup 0}π{sup 0}) ≤ 55 keV, Γ(B{sub s1}{sup 0} → B{sub s}{sup *0}π{sup 0}) ≤ 50 keV. More precise knowledge of the coupling constant describing the interaction of positive and negative parity heavy mesons with light pseudo-scalar mesons would help to increase the accuracy of our calculation. (orig.)
Chiral Corrections to Vector Meson Decay Constants
Bijnens, J; Talavera, P; Bijnens, Johan; Gosdzinsky, Peter; Talavera, Pere
1998-01-01
We calculate the leading quark mass corrections of order $m_q\\log(m_q)$, $m_q$ and $m_q^{3/2}$ to the vector meson decay constants within Heavy Vector Meson Chiral Perturbation Theory. We discuss the issue of electromagnetic gauge invariance and the heavy mass expansion. Reasonably good fits to the observed decay constants are obtained.
Dynamically generated open and hidden charm mesons
Gamermann, D; Strottman, D; Vacas, M J Vicente
2007-01-01
In this presentation I explain our framework for dynamically generating resonances from the meson meson interaction. Our model generates many poles in the T-matrix which are associated with known states, while at the same time new states are predicted.
Experimental evidence for hadroproduction of exotic mesons
Energy Technology Data Exchange (ETDEWEB)
G. S. Adams; T. Adams; Z. Bar-Yam; J. M. Bishop; V. A. Bodyagin; B. B. Brabson; D. S. Brown; N. M. Cason; S. U. Chung; R. R. Crittenden; J. P. Cummings; K. Danyo; S. Denisov; V. Dorofeev; J. P. Dowd; A. R. Dzierba; P. Eugenio; J. Gunter; R. W. Hackenburg; M. Hayek; E. I. Ivanov; I. Kachaev; W. Kern; E. King; O. L. Kodolova; V. L. Korotkikh; M. A. Kostin; J. Kuhn; R. Lindenbusch; V. Lipaev; J. M. LoSecco; J. J. Manak; J. Napolitano; M. Nozar; C. Olchanski; A. I. Ostrovidov; T. K. Pedlar; A. Popov; D. R. Rust; D. Ryabchikov; A. H. Sanjari; L. I. Sarycheva; E. Scott; K. K. Seth; N. Shenhav; W. D. Shephard; N. B. Sinev; J. A. Smith; P. T. Smith; D. L. Stienike; T. Sulanke; S. A. Taegar; S. Teige; D. R. Thompson; I. N. Vardanyan; D. P. Weygand; D. White; H. J. Willutzki; J. Wise; M. Witkowski; A. A. Yershov; D. Zhao
2001-01-01
New measurements of peripheral meson production are presented. The data confirm the existence of exotic mesons at 1.4 and 1.6 GeV/c2. The latter state dominates the eta'pi- decay spectrum. The data on eta pi+pi-pi- decay show large strength in several exotic (Jpc = 1- +) waves as well.
Heavy Mesons in Nuclear Matter and Nuclei
Tolos, Laura; Garcia-Recio, Carmen; Molina, Raquel; Nieves, Juan; Oset, Eulogio; Ramos, Angels; Romanets, Olena; Salcedo, Lorenzo Luis; Torres-Rincon, Juan M
2014-01-01
Heavy mesons in nuclear matter and nuclei are analyzed within different frameworks, paying a special attention to unitarized coupled-channel approaches. Possible experimental signatures of the properties of these mesons in matter are addressed, in particular in connection with the future FAIR facility at GSI.
National Aeronautics and Space Administration — NASA needs sensor systems to inspect space structures with minimum human interaction. These systems must be highly integrated and self-sufficient, low mass, simple...
Low-mass dark matter search results from full exposure of PandaX-I experiment
Xiao, Xiang; Tan, Andy; Chen, Yunhua; Cui, Xiangyi; Fang, Deqing; Fu, Changbo; Giboni, Karl L; Gong, Haowei; Guo, Guodong; He, Ming; Ji, Xiangdong; Ju, Yonglin; Lei, Siao; Li, Shaoli; Lin, Qing; Liu, Huaxuan; Liu, Jianglai; Liu, Xiang; Lorenzon, Wolfgang; Ma, Yugang; Mao, Yajun; Ni, Kaixuan; Pushkin, Kirill; Ren, Xiangxiang; Schubnell, Michael; Shen, Manbing; Shi, Yuji; Stephenson, Scott; Wang, Hongwei; Wang, Jiming; Wang, Meng; Wang, Siguang; Wang, Xuming; Wang, Zhou; Wu, Shiyong; Xiao, Mengjiao; Xie, Pengwei; Yan, Binbin; You, Yinghui; Zeng, Xionghui; Zhang, Tao; Zhao, Li; Zhou, Xiaopeng; Zhu, Zhonghua
2015-01-01
We report the results of a weakly-interacting massive particle (WIMP) dark matter search using the full 80.1\\;live-day exposure of the first stage of the PandaX experiment (PandaX-I) located in the China Jin-Ping Underground Laboratory. The PandaX-I detector has been optimized for detecting low-mass WIMPs, achieving a photon detection efficiency of 9.6\\%. With a fiducial liquid xenon target mass of 54.0\\,kg, no significant excess event were found above the expected background. A profile likelihood analysis confirms our earlier finding that the PandaX-I data disfavor all positive low-mass WIMP signals reported in the literature under standard assumptions. A stringent bound on the low mass WIMP is set at WIMP mass below 10\\,GeV/c$^2$, demonstrating that liquid xenon detectors can be competitive for low-mass WIMP searches.
Recent advances in the theoretical modeling of pulsating low-mass He-core white dwarfs
Córsico, A H; Calcaferro, L M; Serenelli, A M; Kepler, S O; Jeffery, C S
2016-01-01
Many extremely low-mass (ELM) white-dwarf (WD) stars are currently being found in the field of the Milky Way. Some of these stars exhibit long-period nonradial $g$-mode pulsations, and constitute the class of ELMV pulsating WDs. In addition, several low-mass pre-WDs, which could be precursors of ELM WDs, have been observed to show short-period photometric variations likely due to nonradial $p$ modes and radial modes. They could constitute a new class of pulsating low-mass pre-WD stars, the pre-ELMV stars. Here, we present the recent results of a thorough theoretical study of the nonadiabatic pulsation properties of low-mass He-core WDs and pre-WDs on the basis of fully evolutionary models representative of these stars.
1988 CELLO, JADE, and PLUTO contributions to ''exotic'' meson spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Feindt, M.
1989-04-25
This article reviews selected recent results on resonance formation in ..gamma gamma.. reactions obtained with the CELLO, JADE, and PLUTO spectrometers at the /ital e//sup +//ital e/minus// storage ring PETRA. New stringent limits on the ..gamma gamma.. coupling of glueball candidates as well as new results on tensor and scalar mesons are presented. The recent observation of ..pi../sub 2/(1680) formation is confirmed by the CELLO group. Finally the two spin 1 states observed in ..gamma gamma../sup */ interactions, in particular the parity of the /ital X//sub 1/(1420) and the model dependence of present analyses are discussed.
Studies of Excited $D$ mesons in $B$ meson decays
AUTHOR|(CDS)2082679
This thesis documents the studies of several three-body B + meson decays, each with a charged charmed meson in the final state. All analyses presented use a data sample recorded by the LHCb detector in 2011 and 2012, corresponding to an integrated luminosity of 3.0 $fb^{-1}$ of $pp$ collision data. The $B^{+} \\to D^{-}K^{+}\\pi^{+}$ and $B^{+} \\to D^{+}K^{+}\\pi^{-}$ decay modes are observed for the first time. The branching fraction of the favoured $B^{+} \\to D^{-}K^{+}\\pi^{+}$ decay mode is measured relative to the topologically similar $B^{+} \\to D^{-}\\pi^{+}\\pi^{+}$ decay and the $B^{+} \\to D^{-}K^{+}\\pi^{+}$ final state is used as a normalisation channel for the suppressed $B^{+} \\to D^{+}K^{+}\\pi^{-}$ decay branching fraction measurement. Searches are performed for the quasi-two-body decays $B^{+} \\to D^{+}K^{*}(892)^{0}$ and $B^{+} \\to D_{2}^{*}(2460)^{0}K^{+}$, using the sample of $B^{+} \\to D^{+}K^{+}\\pi^{-}$ candidate decays. No significant signals are observed for either decay mode and upper limits a...
Status of chiral meson physics
Energy Technology Data Exchange (ETDEWEB)
Bijnens, Johan [Department of Astronomy and Theoretical Physics, Lund University, Sölvegatan 14A, SE 22362 Lund (Sweden)
2016-01-22
This talk includes a short introduction to Chiral Perturbation Theory in the meson sector concentrating on a number of recent developments. I discuss the latest fit of the low-energy constants. Finite volume corrections are discussed for the case with twisted boundary conditions for form-factors and first results at two-loops for three flavours for masses. The last part discusses the extension to other symmetry breaking patterns relevant for technicolour and related theories as well as the calculation of leading logarithms to high loop orders.
Vector meson condensation in a pion superfluid
Brauner, Tomáš; Huang, Xu-Guang
2016-11-01
We revisit the suggestion that charged ρ -mesons undergo Bose-Einstein condensation in isospin-rich nuclear matter. Using a simple version of the Nambu-Jona-Lasinio (NJL) model, we conclude that ρ -meson condensation is either avoided or postponed to isospin chemical potentials much higher than the ρ -meson mass as a consequence of the repulsive interaction with the preformed pion condensate. In order to support our numerical results, we work out a linear sigma model for pions and ρ -mesons, showing that the two models lead to similar patterns of medium dependence of meson masses. As a byproduct, we analyze in detail the mapping between the NJL model and the linear sigma model, focusing on conditions that must be satisfied for a quantitative agreement between the models.
Vector meson condensation in a pion superfluid
Brauner, Tomas
2016-01-01
We revisit the suggestion that charged rho-mesons undergo Bose-Einstein condensation in isospin-rich nuclear matter. Using a simple version of the Nambu-Jona-Lasinio (NJL) model, we conclude that rho-meson condensation is either avoided or postponed to isospin chemical potentials much higher than the rho-meson mass as a consequence of the repulsive interaction with the preformed pion condensate. In order to support our numerical results, we work out a linear sigma model for pions and rho-mesons, showing that the two models lead to similar patterns of medium dependence of meson masses. As a byproduct, we analyze in detail the mapping between the NJL model and the linear sigma model, focusing on conditions that must be satisfied for a quantitative agreement between the models.
Meson spectroscopy, quark mixing and quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Filippov, A.T.
1979-04-01
A semiphenomenological theory of the quark-antiquark meson mass spectrum is presented. Relativistic kinematic effects due to unequal quark masses and SU (3) -breaking effects in the slopes of Regge trajectories and in radially excited states are taken into account. Violation of the OZI rule is accounted for by means of a mixing matrix for the quark wave functions, which is given by QCD. To describe the dependence of the mixing parameters on the meson masses, a simple extrapolation of the QCD expressions is proposed from the ''asymptotic-freedom'' region to the ''infrared-slavery'' region. To calculate the masses and mixing angles of the pseudoscalar mesons, the condition for a minimal pion mass is proposed. The eta-meson mass is then shown to be close to its maximum. The predictions of the theory for meson masses and mixing angles are in good agreement with experiment.
Light Vector Mesons in the Nuclear Medium
Energy Technology Data Exchange (ETDEWEB)
Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis; Djalali, Chaden; Tur, Clarisse; Mosel, Ulrich; Muehlich, Pascal; Adams, Gary; Amaryan, Moscov; Amaryan, Moskov; Ambrozewicz, Pawel; Anghinolfi, Marco; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, James; Baltzell, Nathan; Barrow, Steve; Battaglieri, Marco; Bedlinskiy, Ivan; Bektasoglu, Mehmet; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Biselli, Angela; Blaszczyk, Lukasz; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Carnahan, Bryan; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crannell, Hall; Crede, Volker; Cummings, John; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Denizli, Haluk; Dennis, Lawrence; Deur, Alexandre; Dharmawardane, Kahanawita; Dickson, Richard; Dodge, Gail; Doughty, David; Dugger, Michael; Dytman, Steven; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feldman, Gerald; Feuerbach, Robert; Fradi, Ahmed; Funsten, Herbert; Garcon, Michel; Gavalian, Gagik; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gordon, Christopher; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hadjidakis, Cynthia; Hafidi, Kawtar; Hakobyan, Hayk; Hakobyan, Rafael; Hanretty, Charles; Hardie, John; Hassall, Neil; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Klimenko, Alexei; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Li, Ji; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; McAleer, Simeon; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mehrabyan, Surik; Melone, Joseph; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Minehart, Ralph; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Mueller, James; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Preedom, Barry; Price, John; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Riccardi, Gregory; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Ronchetti, Federico; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Stepan; Stepanyan, Samuel; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Todor, Luminita; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Watts, Daniel; Weinstein, Lawrence; Williams, Michael; Wolin, Elliott; Yegneswaran, Amrit; Zana, Lorenzo; Zhang, Bin; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen
2008-07-01
The light vector mesons ($\\rho$, $\\omega$, and $\\phi$) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the $\\rho$ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The $\\rho$ meson mass spectrum was extracted after the $\\omega$ and $\\phi$ signals were removed in a nearly model-independent way. Comparisons were made between the $\\rho$ mass spectra from the heavy targets ($A > 2$) with the mass spectrum extracted from the deuterium target. With respect to the $\\rho$-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body eff
Low mass dielectrons radiated off cold nuclear matter measured with HADES
Lorenz, M.; Agakishiev, G.; Behnke, C.; Belver, D.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Blume, C.; Böhmer, M.; Cabanelas, P.; Chernenko, S.; Dritsa, C.; Dybczak, A.; Epple, E.; Fabbietti, L.; Fateev, O.; Fonte, P.; Friese, J.; Fröhlich, I.; Galatyuk, T.; Garzón, J. A.; Gill, K.; Golubeva, M.; González-Díaz, D.; Guber, F.; Gumberidze, M.; Harabasz, S.; Hennino, T.; Höhne, C.; Holzmann, R.; Huck, P.; Ierusalimov, A.; Ivashkin, A.; Jurkovic, M.; Kämpfer, B.; Karavicheva, T.; Koenig, I.; Koenig, W.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kotte, R.; Krása, A.; Krebs, E.; Krizek, F.; Kuc, H.; Kugler, A.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lang, S.; Lapidus, K.; Lebedev, A.; Lopes, L.; Maier, L.; Mangiarotti, A.; Markert, J.; Metag, V.; Michel, J.; Müntz, C.; Münzer, R.; Naumann, L.; Palka, M.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Pietraszko, J.; Przygoda, W.; Ramstein, B.; Rehnisch, L.; Reshetin, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Siebenson, J.; Sobolev, Yu. G.; Spataro, S.; Ströbele, H.; Stroth, J.; Strzempek, P.; Sturm, C.; Svoboda, O.; Tarantola, A.; Teilab, K.; Tlusty, P.; Traxler, M.; Tsertos, H.; Vasiliev, T.; Wagner, V.; Weber, M.; Wendisch, C.; Wüstenfeld, J.; Yurevich, S.; Zanevsky, Y.
2014-03-01
The High Acceptance DiElectron Spectrometer HADES [1] is installed at the Helmholtzzentrum für Schwerionenforschung (GSI) accelerator facility in Darmstadt. It investigates dielectron emission and strangeness production in the 1-3 AGeV regime. A recent experiment series focusses on medium-modifications of light vector mesons in cold nuclear matter. In two runs, p+p and p+Nb reactions were investigated at 3.5 GeV beam energy; about 9·109 events have been registered. In contrast to other experiments the high acceptance of the HADES allows for a detailed analysis of electron pairs with low momenta relative to nuclear matter, where modifications of the spectral functions of vector mesons are predicted to be most prominent. Comparing these low momentum electron pairs to the reference measurement in the elementary p+p reaction, we find in fact a strong modification of the spectral distribution in the whole vector meson region.
Measurement of Charm Meson Lifetimes
Energy Technology Data Exchange (ETDEWEB)
Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L.P.; Zhou, G.J. [Wayne State University, Detroit, Michigan 48202 (United States); Chan, S.; Eigen, G.; Lipeles, E.; Schmidtler, M.; Shapiro, A.; Sun, W.M.; Urheim, J.; Weinstein, A.J.; Wuerthwein, F. [California Institute of Technology, Pasadena, California 91125 (United States); Jaffe, D.E.; Masek, G.; Paar, H.P.; Potter, E.M.; Prell, S.; Sharma, V. [University of California, San Diego, La Jolla, California 92093 (United States); Asner, D.M.; Eppich, A.; Gronberg, J.; Hill, T.S.; Korte, C.M.; Lange, D.J.; Morrison, R.J.; Nelson, H.N.; Nelson, T.K.; Roberts, D.; Tajima, H. [University of California, Santa Barbara, California 93106 (United States); Behrens, B.H.; Ford, W.T.; Gritsan, A.; Krieg, H.; Roy, J.; Smith, J.G. [University of Colorado, Boulder, Colorado 80309-0390 (United States); Alexander, J.P.; Baker, R.; Bebek, C.; Berger, B.E.; Berkelman, K.; Boisvert, V.; Cassel, D.G.; Crowcroft, D.S.; Dickson, M.; von Dombrowski, S.; Drell, P.S.; Dumas, D.J.; Ecklund, K.M.; Ehrlich, R.; Foland, A.D.; Gaidarev, P.; Gibbons, L.; Gittelman, B.; Gray, S.W.; Hartill, D.L.; Heltsley, B.K.; Henderson, S.; Hopman, P.I.; Katayama, N.; Kreinick, D.L.; Lee, T.; Liu, Y.; Meyer, T.O.; Mistry, N.B.; Ng, C.R.; Nordberg, E.; Ogg, M.; Patterson, J.R.; Peterson, D.; Riley, D.; Soffer, A.; Thayer, J.G.; Thies, P.G.; Valant-Spaight, B.; Warburton, A.; Ward, C. [Cornell University, Ithaca, New York 14853 (United States); Athanas, M.; Avery, P.; Jones, C.D.; Lohner, M.; Prescott, C.; Rubiera, A.I.; Yelton, J.; Zheng, J. [University of Florida, Gainesville, Florida 32611 (United States); Brandenburg, G.; Briere, R.A.; Ershov, A.; Gao, Y.S.; Kim, D.Y.; Wilson, R. [Harvard University, Cambridge, Massachusetts 02138 (United States); Browder, T.E.; Li, Y.; Rodriguez, J.L.; Yamamoto, H. [University of Hawaii at Manoa, Honolulu, Hawaii 96822 (United States); Bergfeld, T.; Eisenstein, B.I.; Ernst, J.; Gladding, G.E.; Gollin, G.D; and others
1999-06-01
We report measurements of the D{sup 0} , D{sup +} , and D{sup +}{sub s} meson lifetimes using 3.7 fb{sup {minus}1} of e{sup +}e{sup {minus}} annihilation data collected near the {Upsilon}(4S) resonance with the CLEO detector. The measured lifetimes of the D{sup 0} , D{sup +} , and D{sup +}{sub s} mesons are 408.5{plus_minus}4.1{sup +3.5}{sub {minus}3.4} fs , 1033.6{plus_minus}22.1{sup +9.9}{sub {minus}12.7} fs , and 486.3{plus_minus}15.0{sup +4.9}{sub {minus}5.1} fs . The precisions of these lifetimes are comparable to those of the best previous measurements, and the systematic errors are very different. In a single experiment we find that the ratio of the D{sup +}{sub s} and D{sup 0} lifetimes is 1.19{plus_minus}0.04 . {copyright} {ital 1999} {ital The American Physical Society}
Strong Couplings of Three Mesons with Charm(ing) Involvement
Lucha, Wolfgang; Sazdjian, Hagop; Simula, Silvano
2016-01-01
We determine the strong couplings of three mesons that involve, at least, one $\\eta_c$ or $J/\\psi$ meson, within the framework of a constituent-quark model by means of relativistic dispersion formulations. For strong couplings of $J/\\psi$ mesons to two charmed mesons, our approach leads to predictions roughly twice as large as those arising from QCD sum rules.
Scalar transport by planktonic swarms
Martinez-Ortiz, Monica; Dabiri, John O.
2012-11-01
Nutrient and energy transport in the ocean is primarily governed by the action of physical phenomena. In previous studies it has been suggested that aquatic fauna may significantly contribute to this process through the action of the induced drift mechanism. In this investigation, the role of planktonic swarms as ecosystem engineers is assessed through the analysis of scalar transport within a stratified water column. The vertical migration of Artemia salina is controlled via luminescent signals on the top and bottom of the column. The scalar transport of fluorescent dye is visualized and quantified through planar laser induced fluorescence (PLIF). Preliminary results show that the vertical movement of these organisms enhances scalar transport relative to control cases in which only buoyancy forces and diffusion are present. Funded by the BSF program (2011553).
Scalar spin of elementary fermions
Energy Technology Data Exchange (ETDEWEB)
Jourjine, A., E-mail: jourjine@pks.mpg.de
2014-01-20
We show that, using the experimentally observed values of CKM and PMNS mixing matrices, all known elementary fermions can be assigned a new quantum number, the scalar spin, in a unique way. This is achieved without introduction of new degrees of freedom. The assignment implies that tau-neutrino should be an anti-Dirac spinor, while mu–tau leptons and charm–top, strange–bottom quarks form Dirac–anti-Dirac scalar spin doublets. The electron and its neutrino remain as originally described by Dirac.
Buttazzo, Dario
2014-01-01
In the motivated hypothesis that the scalar bosons of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) be the lightest new particles around, a possible strategy to search for signs of the extra CP-even states is outlined. It is shown how the measurements of the couplings of the 126 GeV Higgs boson constrain the region of the physical parameters in a generic NMSSM which minimises the fine-tuning of the electroweak scale. We also determine the cross section for the production of a heavier CP-even scalar, together with its most relevant branching ratios.
Perfect Actions for Scalar Theories
Bietenholz, W
1998-01-01
We construct an optimally local perfect lattice action for free scalars of arbitrary mass, and truncate its couplings to a unit hypercube. Spectral and thermodynamic properties of this ``hypercube scalar'' are drastically improved compared to the standard action. We also discuss new variants of perfect actions, using anisotropic of triangular lattices, or applying new types of RGTs. Finally we add a $\\lambda \\phi^{4}$ term and address perfect lattice perturbation theory. We report on a lattice action for the anharmonic oscillator, which is perfect to $O(\\lambda)$.
Scalar mixing in isotropic turbulence
Kosály, George
1989-04-01
Eswaran and Pope [Phys. Fluids 31, 506 (1988)] performed direct numerical simulations to study the influence of the initial scalar integral length scale on mixing in stationary, isotropic turbulence. Their data demonstrate that both the decay rate and the shape of the rms versus time curve depend on the initial value of the scalar-to-velocity integral length-scale ratio. The present paper discusses modifications of the high Reynolds number theory of Corrsin [AIChE J. 10, 870 (1964)]. The predictions mirror the behavior found in the moderate Reynolds number simulations.
Exclusive φ meson production in HERMES
Energy Technology Data Exchange (ETDEWEB)
Golembiovskaya, Mayya
2014-03-15
In the present work exclusive φ meson leptoproduction at HERMES experiment in DESY was studied using the data collected at HERA accelerator in the period from 1998 till 2000 and from 2006 till 2007 years. In the analysis unpolarized and longitudinally polarized hydrogen and deuteron targets were used, the beam consisted of longitudinally polarized leptons. Via measurement of the angular and momentum distribution of the φ meson decay products 23 spin density matrix elements (SDMEs) for the φ meson were obtained. The number of SDMEs was defined by the experiment conditions, e.g. by the beam and target polarization directions. For the mentioned time period φ meson SDMEs were defined at HERMES for the first time. The quantities U{sub 1}, U{sub 2} and U{sub 3} which can be used to check presence of unnatural parity exchange (UPE) mechanism in phi meson production were calculated from SDMEs. All the results were obtained in 3 kinematic bins of Q{sup 2}, 4 kinematic bins of t' and for the integrated kinematics. No statistically significant difference between the results for hydrogen and deuteron targets was observed. The UPE quantities were found to be zero within 2 σ for the integrated kinematics, indicating negligible contribution of UPE for the φ meson production which is in agreement with theory predictions. The test of s-channel helicity conservation hypothesis via comparison of corresponding SDME values showed helicity conservation for the φ meson production.
GlueX: Meson Spectroscopy in Photoproduction
Energy Technology Data Exchange (ETDEWEB)
Salgado, Carlos [Norfolk State University, JLAB; Smith, Elton S. [JLAB
2014-03-01
The goal of the GlueX experiment \\cite{gluex} is to provide crucial data to help understand the soft gluonic fields responsible for binding quarks in hadrons. Hybrid mesons, and in particular exotic hybrid mesons, provide the ideal laboratory for testing QCD in the confinement regime since these mesons explicitly manifest the gluonic degrees of freedom. Photoproduction is expected to be effective in producing exotic hybrids but there is little data on the photoproduction of light mesons. GlueX will use the new 12-GeV electron beam at Jefferson Lab to produce a 9-GeV beam of linearly polarized photons using the technique of coherent bremsstrahlung. A solenoid-based hermetic detector is under construction, which will be used to collect data on meson production and decays. These data will also be used to study the spectrum of conventional mesons, including the poorly understood excited vector mesons. This talk will give an update on the experiment as well as describe theoretical developments \\cite{Dudek:2011bn} to help understand how these data can provide insights into the fundamental theory of strong interactions.
Meson Form Factors and Deep Exclusive Meson Production Experiments
Energy Technology Data Exchange (ETDEWEB)
Horn, Tanja [The Catholic Univ. of America, Washington, DC (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
2017-05-01
Pion and kaon electroproduction data play a unique role in Nature and our understanding of them is essential for explaining hadron structure. Precision longitudinaltransverse separated pion and kaon cross sections are of particular interest. They allow for the extraction of meson form factors and validation of understanding of hard exclusive and semi-inclusive reactions (π+, K+, π0, γ) towards 3D hadron imaging and potential future flavor decomposition. We review recent data and present prospects for deep exclusive pion and kaon electroproduction at the 12 GeV Jefferson Lab including the prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavor of GPDs, including the helicity-flip GPDs.
Meson screening masses from lattice QCD with two light and the strange quark
Cheng, M; Francis, A; van der Heide, J; Jung, C; Kaczmarek, O; Karsch, F; Laermann, E; Mawhinney, R D; Miao, C; Mukherjee, S; Petreczky, P; Rantaharju, J; Schmidt, C; Soeldner, W
2010-01-01
We present results for screening masses of mesons built from light and strange quarks in the temperature range of approximately between 140 MeV to 800 MeV. The lattice computations were performed with 2+1 dynamical light and strange flavors of improved (p4) staggered fermions along a line of constant physics defined by a pion mass of about 220 MeV and a kaon mass of 500 MeV. The lattices had temporal extents Nt = 4, 6 and 8 and aspect ratios of Ns / Nt \\geq 4. At least up to a temperature of 140 MeV the pseudo-scalar screening mass remains almost equal to the corresponding zero temperature pseudo-scalar (pole) mass. At temperatures around 3Tc (Tc being the transition temperature) the continuum extrapolated pseudo-scalar screening mass approaches very close to the free continuum result of 2 \\pi T from below. On the other hand, at high temperatures the vector screening mass turns out to be larger than the free continuum value of 2 \\pi T. The pseudo-scalar and the vector screening masses do not become degenerate...
Radiative decay of light and heavy mesons
Energy Technology Data Exchange (ETDEWEB)
Barik, N. (Department of Physics, Utkal University, Bhubaneswar-751004 (India)); Dash, P.C. (Department of Physics, P. N. College, Khurda, Orissa (India))
1994-01-01
The [ital M]1 transition among the vector ([ital V]) and pseudoscalar ([ital P]) mesons in the light and heavy flavor sectors has been investigated in a potential model of independent quarks. Going beyond the static approximation, to add some momentum dependence due to the recoil effect in a more realistic calculation, we find an improvement in the results for the radiative decay of light flavored mesons. However, our prediction on the decay rates for the mesons ([ital D][sup *] and [ital B][sup *]) in the heavy flavor sector remains unaffected and compares well with those of other model calculations.
In-medium properties of mesons
Directory of Open Access Journals (Sweden)
Metag Volker
2017-01-01
Full Text Available In the project B.4, the modification of meson properties (mass, width in a nuclear medium has been studied in photoproduction of mesons off nuclear targets. This work has been motivated by theoretical expectations of in-medium modifications of hadrons based on the conjecture of a partial restoration of chiral symmetry in a strongly interacting medium. It has been shown that these in-medium changes can be discussed in a compact form in terms of an optical potential describing the meson-nucleus interaction. Experimental approaches to determine the real and imaginary part of the meson-nucleus potential have been developed. The experiments have been performed with the Crystal Barrel/TAPS detector at the electron accelerator ELSA (Bonn and the Crystal Ball/TAPS detector at MAMI (Mainz. Measuring the excitation function and momentum distribution for photo production of ω and η′ mesons, the real parts of the ω and η′-nucleus potential, given by the in-medium mass shift, have been determined. For the η′ meson a lowering of the mass at normal nuclear matter density by -(39±7(stat±15(syst MeV is observed, while for the ω meson a slightly smaller mass shift is found, however, with much larger uncertainties, not excluding a zero mass shift. The imaginary part of the potentials has been extracted from the measurement of the transparency ratio which compares the meson production cross section per nucleon within a nucleus to the production cross section off the free proton. For the η′ meson the imaginary part of the potential is found to be smaller than the real part. In case of the ω meson the opposite is observed. This makes the η′ meson a good candidate for the search for meson-nucleus bound states while no resolved ω mesic states can be expected. The results are compared with theoretical predictions. An outlook on future experiments is given.
The eta' meson from lattice QCD
Jansen, K; Dollan, Ralph
2008-01-01
We study the flavour singlet pseudoscalar mesons from first principles using lattice QCD. With N_f=2 flavours of light quark, this is the so-called eta_2 meson and we discuss the phenomenological status of this. Using maximally twisted-mass lattice QCD, we extract the mass of the eta_2 meson at two values of the lattice spacing for lighter quarks than previously discussed in the literature. We are able to estimate the mass value in the limit of light quarks with their physical masses.
Vector-pseudoscalar two-meson distribution amplitudes in three-body $B$ meson decays
Chen Chuan Hung; Chen, Chuan-Hung; Li, Hsiang-nan
2004-01-01
We study three-body nonleptonic decays $B\\to VVP$ by introducing two-meson distribution amplitudes for the vector-pseudoscalar pair, such that the analysis is simplified into the one for two-body decays. The twist-2 and twist-3 $\\phi K$ two-meson distribution amplitudes, associated with longitudinally and transversally polarized $\\phi$ mesons, are constrained by the experimental data of the $\\tau\\to\\phi K\
Spin-1 diquark contributing to the formation of tetraquarks in light mesons
Energy Technology Data Exchange (ETDEWEB)
Kim, Hungchong [Korea Aerospace University, Research Institute of Basic Science, Goyang (Korea, Republic of); Cheoun, Myung-Ki [Soongsil University, Department of Physics, Seoul (Korea, Republic of); Kim, K.S. [Korea Aerospace University, School of Liberal Arts and Science, Goyang (Korea, Republic of)
2017-03-15
We apply a mixing framework to the light-meson systems and examine tetraquark possibility in the scalar channel. In the diquark-antidiquark model, a scalar diquark is a compact object when its color and flavor structures are in (anti 3{sub c}, anti 3{sub f}). Assuming that all the quarks are in an S-wave, the spin-0 tetraquark formed out of this scalar diquark has only one spin configuration, vertical stroke J,J{sub 12},J{sub 34} right angle = vertical stroke 000 right angle, where J is the spin of the tetraquark, J{sub 12} the diquark spin, J{sub 34} the antidiquark spin. In this construction of the scalar tetraquark, we notice that another compact diquark with spin-1 in (6{sub c}, anti 3{sub f}) can be used although it is less compact than the scalar diquark. The spin-0 tetraquark constructed from this vector diquark leads to the spin configuration vertical stroke J,J{sub 12},J{sub 34} right angle = vertical stroke 011 right angle. The two configurations, vertical stroke 000 right angle and vertical stroke 011 right angle, are found to mix strongly through the color-spin interaction. The physical states can be identified with certain mixtures of the two configurations which diagonalize the hyperfine masses of the color-spin interaction. Matching these states to two scalar resonances a{sub 0}(980), a{sub 0}(1450) or to K{sup *}{sub 0}(800), K{sup *}{sub 0}(1430) depending on the isospin channel, we find that their mass splittings are qualitatively consistent with the hyperfine mass splittings, which can support their tetraquark structure. To test our mixing scheme further, we also construct the tetraquarks for J = 1, J = 2 with the spin configurations vertical stroke 111 right angle and vertical stroke 2011 right angle, and we discuss possible candidates in the physical spectrum. (orig.)
Alonso, Rodrigo; Manohar, Aneesh V
2016-01-01
The $S$-matrix of a quantum field theory is unchanged by field redefinitions, and so only depends on geometric quantities such as the curvature of field space. Whether the Higgs multiplet transforms linearly or non-linearly under electroweak symmetry is a subtle question since one can make a coordinate change to convert a field that transforms linearly into one that transforms non-linearly. Renormalizability of the Standard Model (SM) does not depend on the choice of scalar fields or whether the scalar fields transform linearly or non-linearly under the gauge group, but only on the geometric requirement that the scalar field manifold ${\\mathcal M}$ is flat. We explicitly compute the one-loop correction to scalar scattering in the SM written in non-linear Callan-Coleman-Wess-Zumino (CCWZ) form, where it has an infinite series of higher dimensional operators, and show that the $S$-matrix is finite. Standard Model Effective Field Theory (SMEFT) and Higgs Effective Field Theory (HEFT) have curved ${\\mathcal M}$, ...
SCALAR AND VECTOR IN COMPULATION
Directory of Open Access Journals (Sweden)
Valery F. Ochkov
2013-01-01
Full Text Available The article deals with two fundamental data types – scalar and vector (array, without the ability of working with them one cannot solve using computer school or university tasks in mathematics, physics, chemistry and other technical training courses. Some fundamentals of teaching computer science at school and university are covered as well.
Scalar Calibration of Vector Magnetometers
DEFF Research Database (Denmark)
Merayo, José M.G.; Brauer, Peter; Primdahl, Fritz;
2000-01-01
The calibration parameters of a vector magnetometer are estimated only by the use of a scalar reference magnetometer. The method presented in this paper differs from those previously reported in its linearized parametrization. This allows the determination of three offsets or signals in the absence...
Alonso, Rodrigo; Manohar, Aneesh V.
2016-01-01
The $S$-matrix of a quantum field theory is unchanged by field redefinitions, and so only depends on geometric quantities such as the curvature of field space. Whether the Higgs multiplet transforms linearly or non-linearly under electroweak symmetry is a subtle question since one can make a coordinate change to convert a field that transforms linearly into one that transforms non-linearly. Renormalizability of the Standard Model (SM) does not depend on the choice of scalar fields or whether the scalar fields transform linearly or non-linearly under the gauge group, but only on the geometric requirement that the scalar field manifold ${\\mathcal M}$ is flat. We explicitly compute the one-loop correction to scalar scattering in the SM written in non-linear Callan-Coleman-Wess-Zumino (CCWZ) form, where it has an infinite series of higher dimensional operators, and show that the $S$-matrix is finite. Standard Model Effective Field Theory (SMEFT) and Higgs Effective Field Theory (HEFT) have curved ${\\mathcal M}$, ...
Quark diagram analysis of B-meson emitting vector ( V) and vector ( V) mesons
Kaur, Maninder
2017-07-01
This paper presents the two body weak nonleptonic decays of B-mesons emitting vector ( V) and vector ( V) mesons within the framework of the diagrammatic approaches at flavor SU(3) symmetry. We have investigated exclusive two body decays of B-meson using model independent quark diagram scheme. We have shown that the recent measurement of the two body exclusive decays of B-mesons can allow us to determine the magnitude and even sign of the QD amplitude for B → VV decays. Therefore, we become able to make few predictions for their branching fractions.
Tetraquarks in the 1/N expansion and meson-meson resonances
Maiani, L
2016-01-01
Diquarks are found to have the right degrees of freedom to describe the tetraquark poles in hidden-charm to open-charm meson-meson amplitudes. Compact tetraquarks result as intermediate states in non-planar diagrams of the 1/N expansion and the corresponding resonances are narrower than what estimated before. The proximity of tetraquarks to meson-thresholds has an apparent role in this analysis and, in the language of meson molecules, an halving rule in the counting of states is obtained.
Indirect Constraints on the Scalar Di-Photon Resonance at the LHC
Goertz, Florian; Katz, Andrey; Nardecchia, Marco
2016-01-01
Motivated by the tantalizing excesses recently reported in the di-photon invariant mass spectrum at the LHC, we scrutinize some implications of scalar di-photon resonances in high energy proton-proton collisions. In particular, indications of a large width impose several challenges for model building. We show how calculability and unitarity considerations severely limit possible perturbative realizations of such a signal and propose a simple criterion that can be adapted to any renormalizable model. Furthermore, we discuss correlations between a di-photon excess and precision observables, including the anomalous magnetic and electric dipole moments of quarks and leptons, neutral meson oscillations and radiative flavor changing neutral current mediated decays of heavy leptons and hadrons. We find that existing searches and measurements significantly constrain the possibilities for a scalar resonance decaying into final states involving Standard Model fermions. We propose future search strategies which could el...
Hybrid Exotic Meson Decay Width
Cook, M S
2005-01-01
We present results of a decay width calculation for a hybrid exotic meson(h, JPC=1-+) in the decay channel h to pi+a1. This calculation uses quenched lattice QCD and Luescher's finite box method. Operators for the h and pi+a1 states are used in a correlation matrix which was expanded by varying the smearing and fuzzing levels at source and sink points. Scattering phase shifts for a discrete set of relative pi+a1 momenta are determined using eigenvalues of the correlation matrix and formulae derived by Luescher. The phase shift data is very sparse, but fits to a Breit-Wigner model are made, resulting in a decay width of about 80 MeV.
Evolutionary implications of the new triple-alpha nuclear reaction rate for low mass stars
Dotter, Aaron
2009-01-01
Context: Ogata et al. (2009; hereafter OKK) presented a theoretical determination of the triple-alpha nuclear reaction rate. Their rate differs from the NACRE rate by many orders of magnitude at temperatures relevant for low mass stars. Aims: We explore the evolutionary implications of adopting the OKK triple-alpha reaction rate in low mass stars and compare the results with those obtained using the NACRE rate. Methods: The triple-alpha reaction rates are compared by following the evolution of stellar models at 1 and 1.5 Msol with Z=0.0002 and Z=0.02. Results: Results show that the OKK rate has severe consequences for the late stages of stellar evolution in low mass stars. Most notable is the shortening--or disappearance--of the red giant phase. Conclusions: The OKK triple-alpha reaction rate is incompatible with observations of extended red giant branches and He burning stars in old stellar systems.
New Light on Dark Stars Red Dwarfs, Low-Mass Stars, Brown Dwarfs
Reid, I. Neill
2005-01-01
There has been very considerable progress in research into low-mass stars, brown dwarfs and extrasolar planets during the past few years, particularly since the fist edtion of this book was published in 2000. In this new edtion the authors present a comprehensive review of both the astrophysical nature of individual red dwarf and brown dwarf stars and their collective statistical properties as an important Galactic stellar population. Chapters dealing with the observational properies of low-mass dwarfs, the stellar mass function and extrasolar planets have been completely revised. Other chapters have been significantly revised and updated as appropriate, including important new material on observational techniques, stellar acivity, the Galactic halo and field star surveys. The authors detail the many discoveries of new brown dwarfs and extrasolar planets made since publication of the first edition of the book and provide a state-of-the-art review of our current knowledge of very low-mass stars, brown dwarfs a...
Visual orbit for the low-mass binary Gliese 22 AC from speckle interferometry
Woitas, J; Docobo, J A; Leinert, C; Leinert, Ch.
2003-01-01
Based on 14 data points obtained with near-infrared speckle interferometry and covering an almost entire revolution, we present a first visual orbit for the low-mass binary system Gliese 22 AC. The quality of the orbit is largely improved with respect to previous astrometric solutions. The dynamical system mass is 0.592 +- 0.065 solar masses, where the largest part of the error is due to the Hipparcos parallax. A comparison of this dynamical mass with mass-luminosity relations on the lower main sequence and theoretical evolutionary models for low-mass objects shows that both probably underestimate the masses of M dwarfs. A mass estimate for the companion Gliese 22 C indicates that this object is a very low-mass star with a mass close to the hydrogen burning mass limit.
Measuring the Initial Mass Function of Low Mass Stars and Brown Dwarfs
Jeffries, R D
2012-01-01
I review efforts to determine the form and any lower limit to the initial mass function in the Galactic disk, using observations of low-mass stars and brown dwarfs in the field, young clusters and star forming regions. I focus on the methodologies that have been used and the uncertainties that exist due to observational limitations and to systematic uncertainties in calibrations and theoretical models. I conclude that whilst it is possible that the low-mass IMFs deduced from the field and most young clusters are similar, there are too many problems to be sure; there are examples of low-mass cluster IMFs that appear to be very discrepant and the IMFs for brown dwarfs in the field and young clusters have yet to be reconciled convincingly.
Scalar Field Dark Matter in Clusters of Galaxies
Bernal, Tula; Matos, Tonatiuh
2016-01-01
One alternative to the CDM paradigm is the Scalar Field Dark Matter (SFDM) model, which assumes dark matter is a spin-0 ultra-light scalar field with a typical mass $m\\sim10^{-22}\\mathrm{eV}/c^2$ and positive self-interactions. Due to the ultra-light boson mass, the SFDM could form Bose-Einstein condensates in the very early universe, which are interpreted as the dark matter haloes. Although cosmologically the model behaves as CDM, they differ at small scales: SFDM naturally predicts fewer satellite haloes, cores in dwarf galaxies and the formation of massive galaxies at high redshifts. The ground state (or BEC) solution at zero temperature suffices to describe low-mass galaxies but fails for larger systems. A possible solution is adding finite-temperature corrections to the SF potential which allows combinations of excited states. In this work we test the finite-temperature multistate SFDM solution at galaxy cluster scales and compare our results with the NFW and BEC profiles. We achieve this by fitting the ...
(→ + - 0) meson photoproduction on proton
Indian Academy of Sciences (India)
Swapan Das
2010-10-01
The cross-section for the + - 0 invariant mass distribution in the $ p$ reaction in the GeV region is calculated. This reaction is assumed to proceed through the formation of the -meson in the intermediate state, because the production cross-section for this meson in the reaction in the GeV region is significant and it has a large branching ratio (88.8%) in the + − 0 channel. The cross-sections for this reaction are calculated using the energy-dependent reaction amplitude, → (0), extracted from the latest -meson photoproduction data. We use established procedure to calculate other factors, like width and propagator of the -meson, so that our calculation can provide reliable cross-section. The calculated results reproduce the measured + - 0 invariant mass distribution spectra in the reaction.
Meson's correlation functions in a nuclear medium
Directory of Open Access Journals (Sweden)
Chanyong Park
2016-09-01
Full Text Available We investigate meson's spectrum, decay constant and form factor in a nuclear medium through holographic two- and three-point correlation functions. To describe a nuclear medium composed of protons and neutrons, we consider a hard wall model on the thermal charged AdS geometry and show that due to the isospin interaction with a nuclear medium, there exist splittings of the meson's spectrum, decay constant and form factor relying on the isospin charge. In addition, we show that the ρ-meson's form factor describing an interaction with pseudoscalar fluctuation decreases when the nuclear density increases, while the interaction with a longitudinal part of an axial vector meson increases.
Two Photon Couplings of Hybrid Mesons
Page, P R
1996-01-01
A new formalism is developed for the two photon production of hybrid mesons via intermediate hadronic decays. In an adiabatic and non--relativistic context with spin 1 pair creation we obtain the first absolute estimates of unmixed hybrid production strengths to be small (0.03 - 3 eV) in relation to experimental meson widths (0.1 - 5 keV). Within this context, two photon collisions therefore strongly discriminate between hybrid and conventional meson wave function components at BaBar, Cleo II, LEP2 and LHC, filtering out non--gluonic components. Decay widths of unmixed hybrids are tiny. The formalism also induces conventional meson two photon widths roughly in agreement with experiment.
Exclusive hadronic decays of B mesons
Hölscher, Andreas
1991-06-01
The recent experimental results on exclusive hadronic decays of B mesons obtained by the ARGUS collaboration are presented in the talk. The results include exclusive hadronic decays involving a b → c transition, namely B decays with a D, D ∗ plus several pions and B decays to J/ψ or ψ' mesons plus Kaons have been studied. The measurements of branching ratios for two-body B decays involving a J/ψ or ψ' meson are of wide interest in the light of proposals for the study of CP violation in future experiments. The branching ratios are compared with the predictions of the model of Bauer, Stech and Wirbel and with a model of A.V. Dobrovolskaya. Using the cleanest decay channels, the masses and mass difference of the charged and neutral B meson are obtained. This mass difference is then compared with the mass splitting in other isospinmultipletts and with theoretical models.
Meson masses in large Nf QCD from Bethe-Salpeter equation
Harada, M; Yamawaki, K; Harada, Masayasu; Kurachi, Masafumi; Yamawaki, Koichi
2003-01-01
We solve the homogeneous Bethe-Salpeter (HBS) equation for the scalar, pseudoscalar, vector and axial-vector bound states of quark and anti-quark in large Nf QCD with the improved ladder approximation in the Landau gauge. Quark mass function in the HBS equation is obtained from the Schwinger-Dyson (SD) equation in the same approximation for the consistency with the chiral symmetry. Amazingly, due to the fact that the two-loop running coupling of large Nf QCD is explicitly written in terms of an analytic function, large Nf QCD turns out to be the first example in which the SD equation can be solved in the complex plane and hence the HBS equation directly in the time-like region. We find that approaching the chiral phase transition point from the broken phase, the scalar, vector and axial-vector meson masses vanish to zero with the same scaling behavior, all degenerate with the massless pseudoscalar meson. This may suggest a new type of manifestation of the chiral symmetry restoration in large Nf QCD.
Scalar potentials out of canonical quantum cosmology
Guzman, W; Socorro, J; Urena-Lopez, L A
2005-01-01
Using canonical quantization of a flat FRW cosmological model containing a real scalar field $\\phi$ endowed with a scalar potential $V(\\phi)$, we are able to obtain exact and semiclassical solutions of the so called Wheeler-DeWitt equation for a particular family of scalar potentials. Some features of the solutions and their classical limit are discussed.
Galactic Collapse of Scalar Field Dark Matter
Alcubierre, M; Matos, T; Núñez, D; Urena-Lopez, L A; Wiederhold, P; Alcubierre, Miguel; Matos, Tonatiuh; Nunez, Dario; Wiederhold, Petra
2002-01-01
We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations and phenomenological studies in galaxies.
Galactic Collapse of Scalar Field Dark Matter
2001-01-01
We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations and phenomenological studies in galaxies.
Scalar-Scalar, Scalar-Tensor, and Tensor-Tensor Correlators from Anisotropic Inflation
Gumrukcuoglu, A E; Peloso, Marco
2010-01-01
We compute the phenomenological signatures of a model (Watanabe et al' 09) of anisotropic inflation driven by a scalar and a vector field. The action for the vector is U(1) invariant, and the model is free of ghost instabilities. A suitable coupling of the scalar to the kinetic term of the vector allows for a slow roll evolution of the vector vev, and hence for a prolonged anisotropic expansion; this provides a counter example to the cosmic no hair conjecture. We compute the nonvanishing two point correlation functions between physical modes of the system, and express them in terms of power spectra with angular dependence. The anisotropy parameter g_* for the scalar-scalar spectrum (defined as in the Ackerman et al '07 parametrization) turns out to be negative in the simplest realization of the model, which, therefore, cannot account for the angular dependence emerged in some analyses of the WMAP data. A g_* of order -0.1 is achieved when the energy of the vector is about 6-7 orders of magnitude smaller than ...
The Diversity of Low-mass Exoplanets Characterized via Transit Timing
Jontof-Hutter, Daniel; Ford, Eric B.; Rowe, Jason F.; Lissauer, Jack. J.; Fabrycky, Daniel C.
2016-10-01
Transit timing variations (TTV) in multi-transiting systems enables precise characterizations of low-mass planets and their orbits. The range of orbital periods and incident fluxes with detailed TTV constraints complements the radial velocity sample for low-mass planets, pushing exoplanet characterization to the regime sub-Earth size planets and out to Mercury-like distances. This has revealed an astonishing diversity in the density of super-Earth mass planets. We summarize these and other contributions to exoplanet science from TTVs.
First detection of a low-mass stellar halo around the young open cluster Eta Chamaeleontis
Murphy, Simon J; Bessell, Michael S
2010-01-01
We have identified several lithium-rich low-mass (0.08
Bs mesons: semileptonic and nonleptonic decays
Directory of Open Access Journals (Sweden)
Albertus C.
2014-01-01
Full Text Available In this contribution we compute some nonleptonic and semileptonic decay widths of Bs mesons, working in the context of constituent quark models [1, 2]. For the case of semileptonic decays we consider reactions leading to kaons or different Jπ Ds mesons. The study of nonleptonic decays has been done in the factorisation approximation and includes the final states enclosed in Table 2.
Single Meson Photoproduction at JLab Energies
Mathieu, Vincent; Joint Physics Analysis Center Team
2016-09-01
In this talk, I present the results from the Joint Physics Analysis Center about the photoproduction of a single meson (pseudoscalar or vector meson). We have developed the theoretical formalism to analysis forthcoming data at the, recently upgraded, JLab facility. We also present prediction for observables in the energy range of Eg = 5-11 GeV. Material (codes, notes, sim- ulations, etc) can be found online at the JPAC interactive website: http://www.indiana.edu/ jpac/index.html
Pseudoscalar D and B mesons in the hot dense and nonstrange symmetric medium
Chhabra, Rahul; Kumar, Arvind
2017-01-01
We investigate the effect of temperature and density on the shift in the masses and decay constants of the pseudoscalar D and B mesons in the nonstrange symmetric medium. We use chiral SU(3) model to calculate the medium modified scalar and isoscalar fields σ, ζ, δ and χ. We use these modified fields to calculate the in-medium quark and gluon condensates by solving the coupled equations of motions in the chiral SU(3) model. We obtain the medium modified mass and decay constant through these medium modified condensates using the QCD sum rules. Further we use the 3P0 model by taking the internal structure of the mesons to calculate the in-medium decay width of the higher charmonium states χ(3556) , ψ(3686) and ψ(3770) to the D D pairs, through the in-medium mass of D meson and neglecting the mass modification of higher charmonium states. We also compare the present data with the previous results. These results of present investigation may be important to explain the possible outcomes of the experiments like CBM, Panda at GSI. I am not getting any financial support from my institute to attend this meeting. Please provide me financial support so that I may not deprive to attend the meeting.
In-medium pseudoscalar $D/B$ mesons and charmonium decay width
Chhabra, Rahul
2016-01-01
Using QCD sum rules and chiral SU(3) model, we investigate the effect of temperature, density, strangeness fraction and isospin asymmetric parameter on the shift in masses and decay constants of the pseudoscalar $D$ and $B$ meson in hadronic medium, which consist of nucleons and hyperons. The in-medium properties of $D$ and $B$ mesons within QCD sum rule approach depend upon the quark and gluon condensates. In chiral SU(3) model, quark and gluon condensates are introduced through the explicit symmetry breaking term and the trace anomaly property of the QCD, respectively and are written in terms of scalar fields $\\sigma$, $\\zeta$, $\\delta$ and $\\chi$. Hence, through medium modification of $\\sigma$, $\\zeta$, $\\delta$ and $\\chi$ fields, we obtain the medium modified masses and decay constants of $D$ and $B$ mesons. As an application, using $^3 P_0$ model, we calculate the in-medium decay width of the higher charmonium states $ \\psi(3686)$, $\\psi(3770)$ and $\\chi(3556)$ to the $D \\bar{D}$ pairs, considering the i...
${\\bar D}D$ meson pair production in antiproton-nucleus collisions
Shyam, R
2016-01-01
We study the $\\bar D D$ (${\\bar D}^0 D^0$ and $D^-D^+$) charm meson pair production in antiproton (${\\bar p}$) induced reactions on nuclei at beam energies ranging from threshold to several GeV. Our model is based on an effective Lagrangian approach that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction proceeds via the $t$-channel exchanges of $\\Lambda_c^+$, $\\Sigma_c^+$, and $\\Sigma_c^{++}$ baryons in the initial collision of the antiproton with one of the protons of the target nucleus. The medium effects on the exchanged baryons are included by incorporating in the corresponding propagators, the effective charm baryon masses calculated within a quark-meson coupling (QMC) model. The wave functions of the bound proton have been determined within the QMC model as well as in a phenomenological model where they are obtained by solving the Dirac equation with appropriate scalar and vector potentials. The initial- and final-state distortion effects have been approx...
Search for Scalar Leptons and Scalar Quarks at LEP
Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, M; Doria, A; Dova, M T; Duchesneau, D; Duda, M; Echenard, B; Eline, A; El-Hage, A; El-Mamouni, H; Engler, A; Eppling, F J; Extermann, P; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, M; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, F; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Nisati, A; Novák, T; Nowak, H; Ofierzynski, R A; Organtini, G; Pal, I; Palomares, C; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Rubio, J A; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Schäfer, C; Shchegelskii, V; Schopper, Herwig Franz; Schotanus, D J; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wang, Q; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M
2004-01-01
Scalar partners of quarks and leptons, predicted in supersymmetric models, are searched for in e^+e^- collisions at centre-of-mass energies between 192GeV and 209GeV at LEP. No evidence for any such particle is found in a data sample of 450 pb^-1. Upper limits on their production cross sections are set and lower limits on their masses are derived in the framework of the Minimal Supersymmetric Standard Model.
Observation of B meson decays to ωK* and improved measurements for ωρ and ωf0
Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Lopez, L.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Osipenkov, I. L.; Tackmann, K.; Tanabe, T.; Hawkes, C. M.; Soni, N.; Watson, A. T.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Fulsom, B. G.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; Barrett, M.; Khan, A.; Randle-Conde, A.; Blinov, V. E.; Bukin, A. D.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Bondioli, M.; Curry, S.; Eschrich, I.; Kirkby, D.; Lankford, A. J.; Lund, P.; Mandelkern, M.; Martin, E. C.; Stoker, D. P.; Abachi, S.; Buchanan, C.; Atmacan, H.; Gary, J. W.; Liu, F.; Long, O.; Vitug, G. M.; Yasin, Z.; Zhang, L.; Sharma, V.; Campagnari, C.; Hong, T. M.; Kovalskyi, D.; Mazur, M. A.; Richman, J. D.; Beck, T. W.; Eisner, A. M.; Heusch, C. A.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Schalk, T.; Schumm, B. A.; Seiden, A.; Winstrom, L. O.; Cheng, C. H.; Doll, D. A.; Echenard, B.; Fang, F.; Hitlin, D. G.; Narsky, I.; Piatenko, T.; Porter, F. C.; Andreassen, R.; Mancinelli, G.; Meadows, B. T.; Mishra, K.; Sokoloff, M. D.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Gilman, J. D.; Hirschauer, J. F.; Nagel, M.; Nauenberg, U.; Smith, J. G.; Rodriguez, D. M.; Thomas, E. W.; Tomassini, E. W.; Wagner, S. R.; Ayad, R.; Soffer, A.; Toki, W. H.; Wilson, R. J.; Feltresi, E.; Hauke, A.; Jasper, H.; Karbach, M.; Merkel, J.; Petzold, A.; Spaan, B.; Wacker, K.; Kobel, M. J.; Nogowski, R.; Schubert, K. R.; Schwierz, R.; Volk, A.; Bernard, D.; Bonneaud, G. R.; Latour, E.; Verderi, M.; Clark, P. J.; Playfer, S.; Watson, J. E.; Andreotti, M.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cecchi, A.; Cibinetto, G.; Franchini, P.; Luppi, E.; Negrini, M.; Petrella, A.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Pacetti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Tosi, S.; Chaisanguanthum, K. S.; Morii, M.; Adametz, A.; Marks, J.; Schenk, S.; Uwer, U.; Bernlochner, F. U.; Klose, V.; Lacker, H. M.; Bard, D. J.; Dauncey, P. D.; Tibbetts, M.; Behera, P. K.; Chai, X.; Charles, M. J.; Mallik, U.; Cochran, J.; Crawley, H. B.; Dong, L.; Meyer, W. T.; Prell, S.; Rosenberg, E. I.; Rubin, A. E.; Gao, Y. Y.; Gritsan, A. V.; Guo, Z. J.; Arnaud, N.; Béquilleux, J.; D'Orazio, A.; Davier, M.; Firmino da Costa, J.; Grosdidier, G.; Le Diberder, F.; Lepeltier, V.; Lutz, A. M.; Pruvot, S.; Roudeau, P.; Schune, M. H.; Serrano, J.; Sordini, V.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Bingham, I.; Burke, J. P.; Chavez, C. A.; Fry, J. R.; Gabathuler, E.; Gamet, R.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Clarke, C. K.; di Lodovico, F.; Sacco, R.; Sigamani, M.; Cowan, G.; Paramesvaran, S.; Wren, A. C.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Hafner, A.; Alwyn, K. E.; Bailey, D.; Barlow, R. J.; Jackson, G.; Lafferty, G. D.; West, T. J.; Yi, J. I.; Anderson, J.; Chen, C.; Jawahery, A.; Roberts, D. A.; Simi, G.; Tuggle, J. M.; Dallapiccola, C.; Salvati, E.; Saremi, S.; Cowan, R.; Dujmic, D.; Fisher, P. H.; Henderson, S. W.; Sciolla, G.; Spitznagel, M.; Yamamoto, R. K.; Zhao, M.; Patel, P. M.; Robertson, S. H.; Schram, M.; Lazzaro, A.; Lombardo, V.; Palombo, F.; Stracka, S.; Bauer, J. M.; Cremaldi, L.; Godang, R.; Kroeger, R.; Summers, D. J.; Zhao, H. W.; Simard, M.; Taras, P.; Nicholson, H.; de Nardo, G.; Lista, L.; Monorchio, D.; Onorato, G.; Sciacca, C.; Raven, G.; Snoek, H. L.; Jessop, C. P.; Knoepfel, K. J.; Losecco, J. M.; Wang, W. F.; Corwin, L. A.; Honscheid, K.; Kagan, H.; Kass, R.; Morris, J. P.; Rahimi, A. M.; Regensburger, J. J.; Sekula, S. J.; Wong, Q. K.; Blount, N. L.; Brau, J.; Frey, R.; Igonkina, O.; Kolb, J. A.; Lu, M.; Rahmat, R.; Sinev, N. B.; Strom, D.; Strube, J.; Torrence, E.; Castelli, G.; Gagliardi, N.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simonetto, F.; Stroili, R.; Voci, C.; Del Amo Sanchez, P.; Ben-Haim, E.; Briand, H.; Chauveau, J.; Hamon, O.; Leruste, Ph.; Ocariz, J.; Perez, A.; Prendki, J.; Sitt, S.; Gladney, L.; Biasini, M.; Manoni, E.; Angelini, C.; Batignani, G.; Bettarini, S.; Calderini, G.; Carpinelli, M.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Marchiori, G.; Morganti, M.; Neri, N.; Paoloni, E.; Rizzo, G.; Walsh, J. J.; Lopes Pegna, D.; Lu, C.; Olsen, J.; Smith, A. J. S.; Telnov, A. V.; Anulli, F.; Baracchini, E.; Cavoto, G.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.
2009-03-01
We present measurements of B meson decays to the final states ωK*, ωρ, and ωf0, where K* indicates a spin 0, 1, or 2 strange meson. The data sample corresponds to 465×106 B Bmacr pairs collected with the BABAR detector at the PEP-II e+e- collider at SLAC. B meson decays involving vector-scalar, vector-vector, and vector-tensor final states are analyzed; the latter two shed new light on the polarization of these final states. We measure the branching fractions for nine of these decays; five are observed for the first time. For most decays we also measure the charge asymmetry and, where relevant, the longitudinal polarization fL.
Decay of charmonium states into a scalar and a pseudoscalar glueball
Directory of Open Access Journals (Sweden)
Eshraim Walaa I.
2016-01-01
Full Text Available In the framework of a chiral symmetric model, we expand a U(4R × U(4L symmetric linear sigma model with (axial-vector mesons by including a dilaton field, a scalar glueball, and the pseudoscalar glueball. We compute the decay width of the scalar charmonium state χC0(IP into a predominantly scalar glueball f0(1710. We calculate the decay width of the pseudoscalar charmonium states ηC(IS into a predominantly scalar glueball f0(1710 as well as into a pseudoscalar glueball with a mass of 2.6 GeV (as predicted by Lattice-QCD simulations and with a mass of 2.37 GeV (corresponding to the mass of the resonance X(2370. This study is interesting for the upcoming PANDA experiment at the FAIR facility and BESIII experiment. Moreover, we obtain the mixing angle between a pseudoscalar glueball, with a mass of 2.6 GeV, and the charmonium state ηC.
Decay of charmonium states into a scalar and a pseudoscalar glueball
Eshraim, Walaa I.
2016-11-01
In the framework of a chiral symmetric model, we expand a U(4)R × U(4)L symmetric linear sigma model with (axial-)vector mesons by including a dilaton field, a scalar glueball, and the pseudoscalar glueball. We compute the decay width of the scalar charmonium state χC0(IP) into a predominantly scalar glueball f0(1710). We calculate the decay width of the pseudoscalar charmonium states ηC(IS) into a predominantly scalar glueball f0(1710) as well as into a pseudoscalar glueball with a mass of 2.6 GeV (as predicted by Lattice-QCD simulations) and with a mass of 2.37 GeV (corresponding to the mass of the resonance X(2370)). This study is interesting for the upcoming PANDA experiment at the FAIR facility and BESIII experiment. Moreover, we obtain the mixing angle between a pseudoscalar glueball, with a mass of 2.6 GeV, and the charmonium state ηC.
Constrained inflaton due to a complex scalar
Energy Technology Data Exchange (ETDEWEB)
Budhi, Romy H. S. [Physics Department, Gadjah Mada University,Yogyakarta 55281 (Indonesia); Institute for Theoretical Physics, Kanazawa University,Kanazawa 920-1192 (Japan); Kashiwase, Shoichi; Suematsu, Daijiro [Institute for Theoretical Physics, Kanazawa University,Kanazawa 920-1192 (Japan)
2015-09-14
We reexamine inflation due to a constrained inflaton in the model of a complex scalar. Inflaton evolves along a spiral-like valley of special scalar potential in the scalar field space just like single field inflation. Sub-Planckian inflaton can induce sufficient e-foldings because of a long slow-roll path. In a special limit, the scalar spectral index and the tensor-to-scalar ratio has equivalent expressions to the inflation with monomial potential φ{sup n}. The favorable values for them could be obtained by varying parameters in the potential. This model could be embedded in a certain radiative neutrino mass model.
Spectroscopy of mesonic molecules with heavy-light flavour mesons
Rathaud, D P
2016-01-01
In this work, we have calculated the mass spectra and decay properties of dimesonic (meson-antimeson) bound state in the variational scheme. The intermesonic interaction considered as the Hellmann potential and One Pion Exchange potential. The mass spectra of the $D\\bar{D^{*}}$, $D\\bar{D_{s}^{*}}$, $D_{s}\\bar{D^{*}}$, $D_{s}\\bar{D_{s}^{*}}$, $D^{*}\\bar{D^{*}}$, $D_{s}^{*}\\bar{D_{s}^{*}}$, $D\\bar{B^{*}}$, $D\\bar{B_{s}^{*}}$, $D_{s}\\bar{B^{*}}$, $D_{s}\\bar{B_{s}^{*}}$, $B^{*}\\bar{D}$,$B^{*}\\bar{D_{s}}$, $B\\bar{B^{*}}$, $B_{s}\\bar{B^{*}}$, $B_{c}\\bar{B^{*}}$, $B^{*}\\bar{B^{*}}$, $B^{*}\\bar{B_{s}^{*}}$, $B_{s}^{*}\\bar{B_{s}^{*}}$ etc.. are calculated. The states X(3872), $X_{2c}(4013)$ ,$Z_{b}(10610)/X_{b}$ and $Z_{b}(10650)/X_{b2}$ are compared with $D\\bar{D^{*}}$, $D^{*}\\bar{D^{*}}$, $B\\bar{B^{*}}$ and $B^{*}\\bar{B^{*}}$ dimesonic bound states. To probe the molecular structure of the compared states, we have calculated the decay properties sensitive to their long and short distance structure of hadorinc molecul...
CP violating scalar Dark Matter
Cordero-Cid, A; Keus, V; King, S F; Moretti, S; Rojas, D; Sokołowska, D
2016-01-01
We study an extension of the Standard Model (SM) in which two copies of the SM scalar $SU(2)$ doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are \\textit{inert}, are added to the scalar sector. We allow for CP-violation in the \\textit{inert} sector, where the lightest \\textit{inert} state is protected from decaying to SM particles through the conservation of a $Z_2$ symmetry. The lightest neutral particle from the \\textit{inert} sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.
Scalar-tensor linear inflation
Artymowski, Michal
2016-01-01
We investigate two approaches to non minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for any form of the non-minimal coupling to gravity of the form of $f(\\varphi)R/2$; b) the particle physics approach, where we motivate the form of the Jordan frame potential by the loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced inflation, but instead of the Starobinsky attractor they lead to the linear inflation in the strong coupling limit.
Scalar-tensor linear inflation
Artymowski, Michał; Racioppi, Antonio
2017-04-01
We investigate two approaches to non-minimally coupled gravity theories which present linear inflation as attractor solution: a) the scalar-tensor theory approach, where we look for a scalar-tensor theory that would restore results of linear inflation in the strong coupling limit for a non-minimal coupling to gravity of the form of f(varphi)R/2; b) the particle physics approach, where we motivate the form of the Jordan frame potential by loop corrections to the inflaton field. In both cases the Jordan frame potentials are modifications of the induced gravity inflationary scenario, but instead of the Starobinsky attractor they lead to linear inflation in the strong coupling limit.
Scalar Fields in Particle Physics
Pedro, Leonardo
2016-01-01
Extending the scalar sector helps in studying the Higgs mechanism and some Standard Model problems. We implement the correspondence between the gauge-dependent elementary states and the non-perturbative non-abelian gauge-invariant asymptotic states, necessary to study the non-perturbative phenomenology of two-Higgs-doublet models. The Flavour and CP violation in experimental data follows a hierarchical pattern, accounted by the Standard Model. We define the Minimal Flavour Violation condition with six spurions in effective field theories, implying Flavour and CP violation entirely dependent on the fermion mixing matrices but independent of the fermion masses hierarchy; it is renormalization-group invariant. We study the phenomenology of renormalizable two-Higgs-doublet models which verify the defined condition as consequence of a symmetry; new light physical scalars, mediating Flavour Changing Neutral Currents, are allowed by flavour data without flavour coefficients beyond the Standard Model; we tested the m...
CP violating scalar Dark Matter
Energy Technology Data Exchange (ETDEWEB)
Cordero-Cid, A.; Hernández-Sánchez, J. [Instituto de Física and Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 542, C.P. 72570 Puebla (Mexico); Keus, V. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Gustaf Hallstromin katu 2, Helsinki, FIN-00014 (Finland); School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); King, S.F. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Moretti, S. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Particle Physics Department, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom); Rojas, D. [Instituto de Física and Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Apdo. Postal 542, C.P. 72570 Puebla (Mexico); Sokołowska, D. [Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw (Poland)
2016-12-05
We study an extension of the Standard Model (SM) in which two copies of the SM scalar SU(2) doublet which do not acquire a Vacuum Expectation Value (VEV), and hence are inert, are added to the scalar sector. We allow for CP-violation in the inert sector, where the lightest inert state is protected from decaying to SM particles through the conservation of a Z{sub 2} symmetry. The lightest neutral particle from the inert sector, which has a mixed CP-charge due to CP-violation, is hence a Dark Matter (DM) candidate. We discuss the new regions of DM relic density opened up by CP-violation, and compare our results to the CP-conserving limit and the Inert Doublet Model (IDM). We constrain the parameter space of the CP-violating model using recent results from the Large Hadron Collider (LHC) and DM direct and indirect detection experiments.
Scalar Trapping and Saxion Cosmology
Moroi, Takeo; Nakayama, Kazunori; Takimoto, Masahiro
2013-01-01
We study in detail the dynamics of a scalar field in thermal bath with symmetry breaking potential. In particular, we focus on the process of trapping of a scalar field at an enhanced symmetry point through the thermal/non-thermal particle production, taking into account the interactions of produced particles with the standard model particles. As an explicit example, we revisit the saxion dynamics with an initial amplitude much larger than the Peccei-Quinn scale and show that the saxion trapping phenomenon happens for the most cases and it often leads to thermal inflation. We also study the saxion dynamics after thermal inflation, and it is shown that thermal dissipation effect on the saxion can relax the axion overproduction problem from the saxion decay.
Variations on Slavnov's scalar product
Foda, O
2012-01-01
We consider the rational six-vertex model on an L-by-L lattice with domain wall boundary conditions and restrict N parallel-line rapidities, N < L/2, to satisfy length-L XXX spin-1/2 chain Bethe equations. We show that the partition function is an (L-2N)-parameter extension of Slavnov's scalar product of a Bethe eigenstate and a generic state, with N magnons each, on a length-L XXX spin-1/2 chain. Decoupling the extra parameters, we obtain a third determinant expression for the scalar product, where the first is due to Slavnov [1], and the second is due to Kostov and Matsuo [2]. We show that the new determinant is a discrete KP tau-function in the inhomogeneities, and consequently that tree-level N = 4 SYM structure constants that are known to be determinants, remain determinants at 1-loop level.
Scalar top study: Detector optimization
Indian Academy of Sciences (India)
C Milsténe; A Sopczak
2007-11-01
A vertex detector concept of the linear collider flavour identification (LCFI) collaboration, which studies pixel detectors for heavy quark flavour identification, has been implemented in simulations for -quark tagging in scalar top studies. The production and decay of scalar top quarks (stops) is particularly interesting for the development of the vertex detector as only two -quarks and missing energy (from undetected neutralinos) are produced for light stops. Previous studies investigated the vertex detector design in scenarios with large mass differences between stop and neutralino, corresponding to large visible energy in the detector. In this study we investigate the tagging performance dependence on the vertex detector design in a scenario with small visible energy for the international linear collider (ILC).
Photoproduction and Decay of Light Mesons in CLAS
Energy Technology Data Exchange (ETDEWEB)
Amaryan, Moskov Jamalovich [Old Dominion University
2013-08-01
We present preliminary experimental results on photoproduction and decay of light mesons measured with CLAS setup at JLAB . This include Dalitz decay of pseudoscalar and vector mesons, radiative decay of pseudoscalar mesons as well hadronic decays of pseudoscalar and vector mesons. The collected high statistics in some of decay channels exceeds the world data by an order of magnitude and some other decay modes are observed for the first time. It is shown how the CLAS data will improve the world data on transition form factors of light mesons, Dalitz plot analyses, branching ratios of rare decay modes and other fundamental properties potentially accessible through the light meson decays.
Tawfik, Abdel Nasser; Magdy, Niseem
2015-01-01
Effects of an external magnetic field on various properties of quantum chromodynamics (QCD) matter under extreme conditions of temperature and density (chemical potential) have been analyzed. To this end, we use SU(3) Polyakov linear-σ model and assume that the external magnetic field (e B ) adds some restrictions to the quarks' energy due to the existence of free charges in the plasma phase. In doing this, we apply the Landau theory of quantization, which assumes that the cyclotron orbits of charged particles in a magnetic field should be quantized. This requires an additional temperature to drive the system through the chiral phase transition. Accordingly, the dependence of the critical temperature of chiral and confinement phase transitions on the magnetic field is characterized. Based on this, we have studied the thermal evolution of thermodynamic quantities (energy density and trace anomaly) and the first four higher-order moment of particle multiplicity. Having all these calculations, we have studied the effects of the magnetic field on the chiral phase transition. We found that both critical temperature Tc and critical chemical potential increase with increasing magnetic field, e B . Last but not least, the magnetic effects of the thermal evolution of four scalar and four pseudoscalar meson states are studied. We concluded that the meson masses decrease as the temperature increases up to Tc. Then, the vacuum effect becomes dominant and rapidly increases with the temperature T . At low T , the scalar meson masses normalized to the lowest Matsubara frequency rapidly decrease as T increases. Then, starting from Tc, we find that the thermal dependence almost vanishes. Furthermore, the meson masses increase with increasing magnetic field. This gives a characteristic phase diagram of T vs external magnetic field e B . At high T , we find that the masses of almost all meson states become temperature independent. It is worthwhile to highlight that the various meson
Abedi, Habib
2016-01-01
Multiple field models of inflation exhibit new features than single field models. In this work, we study the hierarchy of parameters based on Hubble expansion rate in curved field space and derive the system of flow equations that describe their evolution. Then we focus on obtaining derivatives of number of $e$-folds with respect to scalar fields during inflation and at hypersurface of the end of inflation.
Random scalar fields and hyperuniformity
Ma, Zheng; Torquato, Salvatore
2017-06-01
Disordered many-particle hyperuniform systems are exotic amorphous states of matter that lie between crystals and liquids. Hyperuniform systems have attracted recent attention because they are endowed with novel transport and optical properties. Recently, the hyperuniformity concept has been generalized to characterize two-phase media, scalar fields, and random vector fields. In this paper, we devise methods to explicitly construct hyperuniform scalar fields. Specifically, we analyze spatial patterns generated from Gaussian random fields, which have been used to model the microwave background radiation and heterogeneous materials, the Cahn-Hilliard equation for spinodal decomposition, and Swift-Hohenberg equations that have been used to model emergent pattern formation, including Rayleigh-Bénard convection. We show that the Gaussian random scalar fields can be constructed to be hyperuniform. We also numerically study the time evolution of spinodal decomposition patterns and demonstrate that they are hyperuniform in the scaling regime. Moreover, we find that labyrinth-like patterns generated by the Swift-Hohenberg equation are effectively hyperuniform. We show that thresholding (level-cutting) a hyperuniform Gaussian random field to produce a two-phase random medium tends to destroy the hyperuniformity of the progenitor scalar field. We then propose guidelines to achieve effectively hyperuniform two-phase media derived from thresholded non-Gaussian fields. Our investigation paves the way for new research directions to characterize the large-structure spatial patterns that arise in physics, chemistry, biology, and ecology. Moreover, our theoretical results are expected to guide experimentalists to synthesize new classes of hyperuniform materials with novel physical properties via coarsening processes and using state-of-the-art techniques, such as stereolithography and 3D printing.
Quantum gravity and scalar fields
Energy Technology Data Exchange (ETDEWEB)
Mackay, Paul T. [School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom); Toms, David J., E-mail: d.j.toms@newcastle.ac.u [School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU (United Kingdom)
2010-02-15
In this Letter we consider the quantization of a scalar field coupled to gravity at one loop order. We investigate the divergences appearing in the mass (i.e. phi{sup 2}) term in the effective action. We use the Vilkovisky-DeWitt effective action technique which guarantees that the result is gauge invariant as well as gauge condition independent in contrast to traditional calculations. Our final result is to identify the complete pole part of the effective action.
Foda, O; Zuparic, M
2009-01-01
Using a Jacobi-Trudi-type identity, we show that the scalar product of a general state and a Bethe eigenstate in a finite-length XXZ spin-1/2 chain is (a restriction of) a KP tau function. This leads to a correspondence between the eigenstates and points on Sato's Grassmannian. Each of these points is a function of the rapidities of the corresponding eigenstate, the inhomogeneity variables of the spin chain and the crossing parameter.
Energy Technology Data Exchange (ETDEWEB)
Foda, O. [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)], E-mail: foda@ms.unimelb.edu.au; Wheeler, M. [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)], E-mail: mwheeler@ms.unimelb.edu.au; Zuparic, M. [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3010 (Australia)], E-mail: mzup@ms.unimelb.edu.au
2009-10-21
Using a Jacobi-Trudi-type identity, we show that the scalar product of a general state and a Bethe eigenstate in a finite-length XXZ spin-1/2 chain is (a restriction of) a KP {tau} function. This leads to a correspondence between the eigenstates and points on Sato's Grassmannian. Each of these points is a function of the rapidities of the corresponding eigenstate, the inhomogeneity variables of the spin chain and the crossing parameter.
Energy Technology Data Exchange (ETDEWEB)
Alonso, Rodrigo [Department of Physics, University of California at San Diego,La Jolla, CA 92093 (United States); Jenkins, Elizabeth E.; Manohar, Aneesh V. [Department of Physics, University of California at San Diego,La Jolla, CA 92093 (United States); CERN TH Division,CH-1211 Geneva 23 (Switzerland)
2016-08-17
The S-matrix of a quantum field theory is unchanged by field redefinitions, and so it only depends on geometric quantities such as the curvature of field space. Whether the Higgs multiplet transforms linearly or non-linearly under electroweak symmetry is a subtle question since one can make a coordinate change to convert a field that transforms linearly into one that transforms non-linearly. Renormalizability of the Standard Model (SM) does not depend on the choice of scalar fields or whether the scalar fields transform linearly or non-linearly under the gauge group, but only on the geometric requirement that the scalar field manifold M is flat. Standard Model Effective Field Theory (SMEFT) and Higgs Effective Field Theory (HEFT) have curved M, since they parametrize deviations from the flat SM case. We show that the HEFT Lagrangian can be written in SMEFT form if and only if M has a SU(2){sub L}×U(1){sub Y} invariant fixed point. Experimental observables in HEFT depend on local geometric invariants of M such as sectional curvatures, which are of order 1/Λ{sup 2}, where Λ is the EFT scale. We give explicit expressions for these quantities in terms of the structure constants for a general G→H symmetry breaking pattern. The one-loop radiative correction in HEFT is determined using a covariant expansion which preserves manifest invariance of M under coordinate redefinitions. The formula for the radiative correction is simple when written in terms of the curvature of M and the gauge curvature field strengths. We also extend the CCWZ formalism to non-compact groups, and generalize the HEFT curvature computation to the case of multiple singlet scalar fields.
On the mass assembly of low-mass galaxies in hydrodynamical simulations of structure formation
De Rossi, Maria E; Tissera, Patricia B; Gonzalez-Samaniego, Alejandro; Pedrosa, Susana
2013-01-01
Cosmological hydrodynamical simulations are studied in order to analyse generic trends for the stellar, baryonic and halo mass assembly of low-mass galaxies (M_* 2, the overall properties of simulated galaxies are not in large disagreement with those derived from observations.
Revealing the physics of r modes in low-mass X-ray binaries
Ho, W.C.G.; Andersson, N.; Haskell, B.
2011-01-01
We consider the astrophysical constraints on the gravitational-wave-driven r-mode instability in accreting neutron stars in low-mass x-ray binaries. We use recent results on superfluid and superconducting properties to infer the core temperature in these neutron stars and show the diversity of the o
Spitzer Space Telescope spectroscopy of ices toward low-mass embedded protostars
Boogert, ACA; Pontoppidan, KM; Lahuis, F; Jorgensen, JK; Augereau, JC; Blake, GA; Brooke, TY; Dullemond, CP; Evans, NJ; Geers, [No Value; Hogerheijde, MR; Kessler-Silacci, J; Knez, C; Morris, P; Noriega-Crespo, A; Schoier, FL; van Dishoeck, EF; Allen, LE; Harvey, PM; Koerner, DW; Mundy, LG; Myers, PC; Padgett, DL; Sargent, AI; Stapelfeldt, KR
2004-01-01
Sensitive 5-38 mum Spitzer Space Telescope and ground-based 3-5 mum spectra of the embedded low-mass protostars B5 IRS1 and HH 46 IRS show deep ice absorption bands superposed on steeply rising mid-infrared continua. The ices likely originate in the circumstellar envelopes. The CO2 bending mode at 1
The Influence of Environment on the Chemical Evolution in Low-mass Galaxies
Liu, Yiqing; Peng, Eric
2016-01-01
The mean alpha-to-iron abundance ratio ([$\\alpha$/Fe]) of galaxies is sensitive to the chemical evolution processes at early time, and it is an indicator of star formation timescale ($\\tau_{{\\rm SF}}$). Although the physical reason remains ambiguous, there is a tight relation between [$\\alpha$/Fe] and stellar velocity dispersion ($\\sigma$) among massive early-type galaxies (ETGs). However, no work has shown convincing results as to how this relation behaves at low masses. We assemble 15 data sets from the literature and build a large sample that includes 192 nearby low-mass ($18<\\sigma<80$~\\kms) ETGs. We find that the [$\\alpha$/Fe]-$\\sigma$ relation generally holds for low-mass ETGs, except in extreme environments. Specifically, in normal galaxy cluster environments, the [$\\alpha$/Fe]-$\\sigma$ relation and its intrinsic scatter are, within uncertainties, similar for low-mass and high-mass ETGs. However, in the most massive relaxed galaxy cluster in our sample, the zero point of the relation is higher an...
Microlensing discovery of a population of very tight, very low mass binary brown dwarfs
DEFF Research Database (Denmark)
Choi, J.-Y.; Han, C.; Udalski, A.
2013-01-01
the discovery via gravitational microlensing of two very low mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 M ☉ and 0.034 M ☉, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field BD binaries known...
Low-mass black holes as the remnants of primordial black hole formation
Greene, Jenny E
2012-01-01
This article documents our ongoing search for the elusive "intermediate-mass" black holes. These would bridge the gap between the approximately ten solar mass "stellar-mass" black holes that are the end-product of the life of a massive star, and the "supermassive" black holes with masses of millions to billions of solar masses found at the centers of massive galaxies. The discovery of black holes with intermediate mass is the key to understanding whether supermassive black holes can grow from stellar-mass black holes, or whether a more exotic process accelerated their growth only hundreds of millions of years after the Big Bang. Here we focus on searches for black holes with masses of 10^4-10^6 solar masses that are found at galaxy centers. We will refer to black holes in this mass range as "low-mass" black holes, since they are at the low-mass end of supermassive black holes. We review the searches for low-mass black holes to date and show tentative evidence, from the number of low-mass black holes that are ...
The role of low-mass star clusters in massive star formation. The Orion Case
Rivilla, V M; Jimenez-Serra, I; Rodriguez-Franco, A
2013-01-01
To distinguish between the different theories proposed to explain massive star formation, it is crucial to establish the distribution, the extinction, and the density of low-mass stars in massive star-forming regions. We analyze deep X-ray observations of the Orion massive star-forming region using the Chandra Orion Ultradeep Project (COUP) catalog. We studied the stellar distribution as a function of extinction, with cells of 0.03 pc x 0.03 pc, the typical size of protostellar cores. We derived stellar density maps and calculated cluster stellar densities. We found that low-mass stars cluster toward the three massive star-forming regions: the Trapezium Cluster (TC), the Orion Hot Core (OHC), and OMC1-S. We derived low-mass stellar densities of 10^{5} stars pc^{-3} in the TC and OMC1-S, and of 10^{6} stars pc^{-3} in the OHC. The close association between the low-mass star clusters with massive star cradles supports the role of these clusters in the formation of massive stars. The X-ray observations show for ...
The hot core around the low-mass protostar IRAS 16293-2422 : Scoundrels rule!
Cazaux, S; Tielens, AGGM; Ceccarelli, C; Castets, A; Wakelam, [No Value; Caux, E; Parise, B; Teyssier, D
2003-01-01
While warm dense gas is prevalent around low-mass protostars, the presence of complex saturated molecules-the chemical inventory characteristic of hot cores-has remained elusive in such environments. Here we report the results of an IRAM 30 m study of the molecular composition associated with the lo
Catalogue of Galactic low-mass X-ray binaries (Liu+, 2007)
Liu, Q.Z.; van Paradijs, J.A.; van den Heuvel, E.P.J.
2007-01-01
We present a new edition of the catalogue of the low-mass X-ray binaries in the Galaxy and the Magellanic Clouds. The catalogue contains source name(s), coordinates, finding chart, X-ray luminosity, system parameters, and stellar parameters of the components and other characteristic properties of 18
Low-Mass Active Galactic Nuclei with Rapid X-Ray Variability
Ho, Luis
2016-01-01
We present a detailed study of the optical spectroscopic properties of 12 active galactic nuclei (AGNs) with candidate low-mass black holes (BHs) selected by Kamizasa et al. through rapid X-ray variability. The high-quality, echellette Magellan spectra reveal broad H$\\alpha$ emission in all the sources, allowing us to estimate robust viral BH masses and Eddington ratios for this unique sample. We confirm that the sample contains low-mass BHs accreting at high rates: the median $M_{\\rm BH} = 1.2\\times 10^6M_\\odot$ and median $L_{\\rm bol}/L_{\\rm Edd}=0.44$. The sample follows the $M_{\\rm BH}-\\sigma_*$ relation, within the considerable scatter typical of pseudobulges, the probable hosts of these low-mass AGNs. Various lines of evidence suggest that ongoing star formation is prevalent in these systems. We propose a new strategy to estimate star formation rates in AGNs hosted by low-mass, low-metallicity galaxies, based on modification of an existing method using the strength of [O II] $\\lambda 3727$, [O III] $\\la...
A Study in Blue: The Baryon Content of Isolated Low Mass Galaxies
Bradford, Jeremy D; Blanton, Michael R
2015-01-01
We study the baryon content of low mass galaxies selected from the Sloan Digital Sky Survey (SDSS DR8), focusing on galaxies in isolated environments where the complicating physics of galaxy-galaxy interactions are minimized. We measure neutral hydrogen (HI) gas masses and line-widths for 148 isolated galaxies with stellar mass between $10^7$ and $10^{9.5} M_{\\odot}$. We compare isolated low mass galaxies to more massive galaxies and galaxies in denser environments by remeasuring HI emission lines from the Arecibo Legacy Fast ALFA (ALFALFA) survey 40% data release. All isolated low mass galaxies either have large atomic gas fractions or large atomic gas fractions cannot be ruled out via their upper limits. We measure a median atomic gas fraction of $f_{\\rm gas} = 0.82 \\pm 0.13$ for our isolated low mass sample with no systems below 0.30. At all stellar masses, the correlations between galaxy radius, baryonic mass and velocity width are not significantly affected by environment. Finally, we estimate a median b...
Discovery of an outflow of the very low-mass star ISO 143
Joergens, V; Pohl, A
2012-01-01
We discover that the very young very low-mass star ISO143 (M5) is driving an outflow based on spectro-astrometry of forbidden [SII] emission lines at 6716A and 6731A observed in UVES/VLT spectra. ISO143 is only one of a handful of brown dwarfs and very low-mass stars (M5-M8) for which an outflow has been detected and that show that the T Tauri phase continues at very low masses. We have found the outflow of ISO143 to be intrinsically asymmetric and the accretion disk to not obscure the outflow, as solely the red outflow component is visible in the [SII] lines. ISO143 is only the third T Tauri object showing a stronger red outflow component in spectro-astrometry, after RW Aur (G5) and ISO217 (M6.25). We show here that including ISO143 two out of seven outflows confirmed in the very low-mass regime (M5-M8) are intrinsically asymmetric. We measure a spatial extension of the outflow in [SII] of up to 200-300 mas (about 30-50 AU) and velocities of up to 50-70 km/s. We detect furthermore line emission of ISO143 in ...
LOW-MASS ACTIVE GALACTIC NUCLEI WITH RAPID X-RAY VARIABILITY
Energy Technology Data Exchange (ETDEWEB)
Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Kim, Minjin [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)
2016-04-10
We present a detailed study of the optical spectroscopic properties of 12 active galactic nuclei (AGNs) with candidate low-mass black holes (BHs) selected by Kamizasa et al. through rapid X-ray variability. The high-quality, echellette Magellan spectra reveal broad Hα emission in all the sources, allowing us to estimate robust virial BH masses and Eddington ratios for this unique sample. We confirm that the sample contains low-mass BHs accreting at high rates: the median M{sub BH} = 1.2 × 10{sup 6} M{sub ⊙} and median L{sub bol}/L{sub Edd} = 0.44. The sample follows the M{sub BH}–σ{sub *} relation, within the considerable scatter typical of pseudobulges, the probable hosts of these low-mass AGNs. Various lines of evidence suggest that ongoing star formation is prevalent in these systems. We propose a new strategy to estimate star formation rates in AGNs hosted by low-mass, low-metallicity galaxies, based on modification of an existing method using the strength of [O ii] λ3727, [O iii] λ5007, and X-rays.
VizieR Online Data Catalog: Very low mass objects in ONC (Rodriguez-Ledesma+, 2010)
Rodriguez-Ledesma, M. V.; Mundt, R.; Eisloeffel, J.
2010-01-01
Table 1 lists the 638 very low mass objects in the Orion Nebula Cluster with magnitudes between 14-21mag in I band for which NIR (JHK) photometry is available. The I band data is from Rodriguez-Ledesma et al. (2009, Cat. ) and JHK data from 2MASS, UKIDSS, and VLT. (1 data file).
Istrate, Alina; Langer, Norbert
2014-01-01
Millisecond pulsars (MSPs) are generally believed to be old neutron stars (NSs) which have been spun up to high rotation rates via accretion of matter from a companion star in a low-mass X-ray binary (LMXB). However, many details of this recycling scenario remain to be understood. Here we investigate binary evolution in close LMXBs to study the formation of radio MSPs with low-mass helium white dwarf companions (He WDs) in tight binaries with orbital periods P_orb = 2-9 hr. In particular, we examine: i) if such observed systems can be reproduced from theoretical modelling using standard prescriptions of orbital angular momentum losses (i.e. with respect to the nature and the strength of magnetic braking), ii) if our computations of the Roche-lobe detachments can match the observed orbital periods, and iii) if the correlation between WD mass and orbital period (M_WD, P_orb) is valid for systems with P_orb < 2 days. Numerical calculations with a detailed stellar evolution code were used to trace the mass-tra...
Using K2 to Investigate Planetary Systems Orbiting Low-Mass Stars
Dressing, Courtney D.; Newton, Elisabeth R.; Charbonneau, David; Schlieder, Joshua E.; K2 CHAI Consortium
2016-10-01
The NASA K2 mission is using the repurposed Kepler spacecraft to search for transiting planets in multiple fields along the ecliptic plane. Unlike the original Kepler mission, which stared at a single region of the sky for four years, K2 observes each field for a much shorter timespan of roughly 80 days. While planets in the habitable zones of Sun-like stars would be unlikely to transit even once during an 80-day interval, planets in the habitable zones of faint low-mass stars have much shorter orbital periods and may even transit multiple times during a single K2 campaign. Accordingly, M and K dwarfs are frequently nominated as K2 Guest Observer targets and K2 has already observed significantly more low-mass stars than the original Kepler mission. While the K2 data are therefore an enticing resource for studying the properties and frequency of planetary systems orbiting low-mass stars, many K2 target stars are not well-characterized and some candidate low-mass stars are actually giants or reddened Sun-like stars. We are improving the characterization of K2 planetary systems orbiting low-mass stars by using SpeX on the NASA Infrared Telescope Facility and TripleSpec on the 200-inch Hale Telescope at Palomar Observatory to acquire near-infrared spectra of K2 target stars. We then employ empirically-based relations to determine the temperatures, radii, luminosities, and metallicities of K2 planet candidate host stars. Refining the stellar parameters allows us to identify astrophysical false positives and better constrain the radii and insolation flux environments of bona fide transiting planets. I will present our resulting catalog of stellar properties and discuss the prospects for using K2 data to investigate whether planet occurrence rates for mid-M dwarfs are similar to those for early-M and late-K dwarfs.
Investigating the Properties of Low-Mass Stars Using Spectra of Wide Binaries
Schluns, Kyle; West, A. A.; Dhital, S.; Massey, A. P.
2013-01-01
We present results from a study designed to characterize wide, low-mass (Sun) binaries identified in the Sloan Digital Sky Survey (SDSS). We examine the SDSS database level completeness (for identifying visual binaries) and analyze the pairs that both have individual SDSS spectra. A comprehensive by-eye examination reveals that a significant fraction of the sources within 1" of the primary stellar source are misclassified as duplicate detections and, hence, are omitted from the photometric primary catalog in the SDSS database. This discrepancy has a noticeable effect on estimates of the binary fraction, mass function, luminosity function, and other studies that rely on large, photometric samples of low-mass stars. Due to their coeval nature, binaries with at least one low-mass component are important for calibrating the age-activity relation and the relative metallicity scales. Better defined stellar ages and metallicities allow for a proper analysis of stellar and Galactic evolution using ubiquitous low-mass stars. We constructed a spectroscopic sample of wide binaries, for which there is at least one low-mass component and an individual spectrum for each star. Each binary was verified using measurements of their common proper motions and a chance alignment probability calculated from a six-dimensional model of the Milky Way. The orbital separation of the binary components provides an extra age constraint due to mechanisms that destroy wide binaries during thin-disk dynamical heating. We evaluate the behavior of the magnetic activity in coeval systems, with a specific focus on the dependence of activity on orbital separation and location in the Galactic disk. The preliminary results of our analysis will help calibrate the age-activity relation in M dwarfs. In addition, we calibrate the relative metallicity scale for metal poor K and M dwarfs using a modified index based on TiO and CaH molecular band features.
Low mass dielectrons radiated off cold nuclear matter measured with HADES
Directory of Open Access Journals (Sweden)
Lorenz M.
2014-03-01
Full Text Available The High Acceptance DiElectron Spectrometer HADES [1] is installed at the Helmholtzzentrum für Schwerionenforschung (GSI accelerator facility in Darmstadt. It investigates dielectron emission and strangeness production in the 1-3 AGeV regime. A recent experiment series focusses on medium-modifications of light vector mesons in cold nuclear matter. In two runs, p+p and p+Nb reactions were investigated at 3.5 GeV beam energy; about 9·109 events have been registered. In contrast to other experiments the high acceptance of the HADES allows for a detailed analysis of electron pairs with low momenta relative to nuclear matter, where modifications of the spectral functions of vector mesons are predicted to be most prominent. Comparing these low momentum electron pairs to the reference measurement in the elementary p+p reaction, we find in fact a strong modification of the spectral distribution in the whole vector meson region.
Low scale inflation at high energy colliders and meson factories
Bramante, Joseph; Cook, Jessica; Delgado, Antonio; Martin, Adam
2016-12-01
Inflation occurring at energy densities less than (1014 GeV )4 produces tensor perturbations too small to be measured by cosmological surveys. However, we show that it is possible to probe low scale inflation by measuring the mass of the inflaton in low energy experiments. Detection prospects and cosmological constraints are determined for low scale quartic hilltop models of inflation paired with a curvaton field, which imprints the spectrum of scalar perturbations observed in large scale structure and on the cosmic microwave background. With cosmological constraints applied, low scale quartic inflation at energies GeV-PeV can be mapped to a MeV-TeV mass inflaton resonance, discoverable through a Higgs portal coupling at upcoming collider and meson decay experiments. It is demonstrated that low scale inflatons can have detectably large couplings to Standard Model particles through a Higgs portal, permitting prompt reheating after inflation, without spoiling, through radiative corrections to the inflaton's self-coupling, the necessary flatness of a low scale inflationary potential. A characteristic particle spectrum for a quartic inflaton-curvaton pair is identified: to within an order of magnitude, the mass of the curvaton can be predicted from the mass of the inflaton, and vice versa. Low scale inflation Higgs portal sensitivity targets are found for experiments like the LHC, SHiP, BEPC, and KEKB.
Electroproduction of pseudoscalar mesons above the resonance region
Energy Technology Data Exchange (ETDEWEB)
Niczyporuk, B.B. [Continuous Electron beam Accelerator Facility, Newport News, VA (United States)
1994-04-01
In this paper, the author has revisited twenty year old data considering the progress achieved in related fields. To make further progress in our understanding of strong interactions, one needs much better quality of exclusive electroproduction data. A measurement of the differential cross section {sigma}(t, W, Q{sup 2}) for the reactions e{sup {minus}} + p {r_arrow} e{sup {minus}} + {pi}{sup +}(K{sup +}) + n({Lambda}{degrees}) at a beam energy of {ge} 4 GeV is proposed. Data will be collected simultaneously for both reactions using the CLAS detector at CEBAF in the following kinematical region: Q{sup 2} > 1 GeV{sup 2} and W > 2 GeV. One of the most interesting aspects of electroproduction is that it can be used to measure photoproduction amplitudes as functions of the photon mass squared Q{sup 2} and momentum transfer t. Emphasis is given to measuring the differential cross sections for t {approximately} m{sup 2}{sub {pi},{kappa}}. Above the resonance region (W > 2 GeV), the cross section is dominated by the amplitudes for scalar photons. Measured angular distributions of produced mesons will be used to estimate the contribution of various amplitudes to the cross sections. High statistics and good quality data collected simultaneously using a large acceptance detector will improve our understanding of nucleon structure as well as the hadronic properties of the photon.
Schiraldi, Vito; Morello, Michael Joseph
In fisica delle particelle, con il termine di "oscillazione" si indica la trasformazione di una particella neutra nella sua antiparticella e viceversa, fenomeno dovuto al fatto che gli autostati di flavor non sono autostati della matrice di massa. Il Modello Standard delle interazioni fondamentali predice che l'oscillazione del mesone D^0 avvenga su tempi molto maggiori di una vita media, e appaia perciò come un effetto piccolo, inferiore al percento, in contrasto con il caso dei mesoni B^0 e B^0_s che oscillano con molta maggiore rapidità. Sperimentalmente, l'oscillazione dei mesoni D^0 è rimasta inosservata fino a tempi recenti: la prima evidenza sperimentale dell'esistenza di un effetto di oscillazione è stata ottenuta soltanto nella primavera del 2007 dagli esperimenti BaBar (SLAC, USA) e Belle (KEKB, Japan). Nell'agosto 2007 anche l’esperimento CDF (Fermilab, USA) ha presentato una evidenza simile, basata sull'analisi di una parte del campione di dati disponibile. La tesi descrive gli aspetti speri...
Quarkonium Contribution to Meson Molecules
Cincioglu, E; Ozpineci, A; Yilmazer, A U
2016-01-01
Starting from a molecular picture for the X(3872) resonance, this state and its J^{PC}=2++ HQSS partner [X2(4012)] are analyzed within a model which incorporates possible mixings with 2P charmonium states. Since it is reasonable to expect the bare chi_{c1}(2P) to be located above the D\\bar D* threshold, but relatively close to it, the presence of the charmonium state provides an effective attraction that will contribute to bind the X(3872), but it will not appear in the 2++ sector. Indeed in this latter sector, the chi_{c2}(2P) should provide an effective small repulsion, because it is placed well below the D*\\bar D* threshold. We show how the 1++ and 2++ bare charmonium poles are modified due to the D(*)\\bar D(*) loop effects, and the first one is moved to the complex plane. The meson loops produce, besides some shifts in the masses of the charmonia, a finite width for the 1++ dressed charmonium state. On the other hand, the X(3872) and X2(4012) start developing some charmonium content, which is estimated by...
Energy Technology Data Exchange (ETDEWEB)
Barik, N.; Jena, S.N.
1981-08-01
Phenomenological evidence from meson spectroscopy is presented to support the view that a unified description of bound light- and heavy-quark systems is possible within the scope of a nonrelativistic-potential-model approach. The vacuum-polarization-corrected potential with its confinement part in the form of an approximately equal admixture of vector and scalar components is found to be a suitable one for the purpose. The overall systematics of the predictions based on this potential model for the meson masses, fine-hyperfine splittings, leptonic decay widths, and the Regge slopes are observed to be consistent with the premise that the forces between quarks and antiquarks are independent of the quark flavors.
B-meson decays to eta' rho, eta' f0, and eta' K*
Energy Technology Data Exchange (ETDEWEB)
del Amo Sanchez, P.; Lees, J.P.; Poireau, V.; Prencipe, E.; Tisserand, V.; /Annecy, LAPP; Garra Tico, J.; Grauges, E.; /Barcelona U., ECM; Martinelli, M.; Palano, A.; Pappagallo, M.; /INFN, Bari /Bari U.; Eigen, G.; Stugu, B.; Sun, L.; /Bergen U.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G.; Osipenkov, I.L.; Tanabe, T.; /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Indian Inst. Tech., Guwahati /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Orsay, LAL /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /INFN, Milan /Mississippi U. /Montreal U. /INFN, Naples /Naples U. /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Southern Methodist U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas U. /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison
2010-08-25
We present measurements of B-meson decays to the final states {eta}{prime} {rho}, {eta}{prime} f{sub 0}, and {eta}{prime} K*, where K* stands for a vector, scalar, or tensor strange meson. We observe a significant signal or evidence for {eta}{prime} {rho}{sup +} and all the {eta}{prime}K* channels. We also measure, where applicable, the charge asymmetries, finding results consistent with no direct CP violation in all cases. The measurements are performed on a data sample consisting of 467 x 10{sup 6} B{bar B} pairs, collected with the BABAR detector at the PEP-II e{sup +}e{sup -} collider at the SLAC National Accelerator Laboratory. Our results favor the theoretical predictions from perturbative QCD and QCD Factorization and we observe an enhancement of the tensor K*{sub 2} (1430) with respect to the vector K*(892) component.
Searches for low-mass neutral Higgs bosons using the CMS detector
Carrillo Montoya, Camilo Andres
2016-01-01
Searches for additional scalars and pseudoscalar with masses below the newly discovered higgs boson h(125). These searches are motivated within several BSM theories, most significantly extensions of the non mininal extensions of the MSSM like the NMSSM, where additional scalar and pseudoscalar states are expected. The mass range from 350 MeV to 110 GeV is explored with different final states. The current status of these searches will be reviewed and prospects will be given to extend these searches in the Run2 of the LHC
Constraints on the $\\eta \\eta'$ decay rate of a scalar glueball from gauge/gravity duality
Brünner, Frederic
2015-01-01
Predictions of glueball decay rates in the holographic Witten-Sakai-Sugimoto model for low-energy QCD can be uniquely extended to include finite quark masses up to an as yet undetermined parameter in the coupling of glueballs to the nonanomalous part of the pseudoscalar mass terms. The assumption of a universal coupling of glueballs to mass terms of the full nonet of pseudoscalar mesons leads to flavor asymmetries in the decay rates of scalar glueballs that agree well with experimental data for the glueball candidate $f_0(1710)$ and implies a vanishing decay rate into $\\eta\\eta'$ pairs, for which only upper bounds for the $f_0(1710)$ meson are known at present from experiment. Relaxing this assumption, the holographic model gives a tight correlation between the decay rates into pairs of pseudo-Goldstone bosons of same type and $\\eta\\eta'$ pairs. If $\\Gamma(G\\to KK)/\\Gamma(G\\to\\pi\\pi)$ is kept within the range reported currently by the Particle Data Group for the $f_0(1710)$ meson, the rate $\\Gamma(G\\to\\eta\\et...
Meson Spectroscopy in the Light Quark Sector
Energy Technology Data Exchange (ETDEWEB)
De Vita, R.; Lunardi, S.; Bizzeti, P. G.; Bucci, C.; Chiari, M.; Dainese, A.; Di Nezza, P.; Menegazzo, R.; Nannini, A.; Signorini, C.; Valiente-Dobon, J. J.
2014-01-01
Understanding the hadron spectrum is one of the fundamental issues in modern particle physics. We know that existing hadron configurations include baryons, made of three quarks, and mesons, made of quark-antiquark pairs. However most of the mass of the hadrons is not due to the mass of these elementary constituents but to their binding force. Studying the hadron spectrum is therefore a tool to understand one of the fundamental forces in nature, the strong force, and Quantum Chromo Dynamics (QCD), the theory that describes it. This investigation can provide an answer to fundamental questions as what is the origin of the mass of hadrons, what is the origin of quark confinement, what are the relevant degrees of freedom to describe these complex systems and how the transition between the elementary constituents, quarks and gluons, and baryons and mesons occurs. In this field a key tool is given by meson spectroscopy. Mesons, being made by a quark and an anti-quark, are the simplest quark bound system and therefore the ideal benchmark to study the interaction between quarks and understand what the role of gluons is. In this investigation, it is fundamental to precisely determine the spectrum and properties of mesons but also to search for possible unconventional states beyond the configuration q{anti q} as tetraquarks (qq{anti qq}), hybrids (q{anti q}g) and glueballs. These states can be distinguished unambiguously from regular mesons when they have exotic quantum numbers, i.e. combinations of total angular momentum, spin and parity that are not allowed for q{anti q} states. These are called exotic quantum numbers and the corresponding states are referred to as exotics. The study of the meson spectrum and the search for exotics is among the goals of several experiments in the world that exploit different reaction processes, as e{sup +}e{sup -} annihilation, p{anti p} annihilation, pion scattering, proton-proton scattering and photo-production, to produce meson states
Review of meson spectroscopy: quark states and glueballs
Energy Technology Data Exchange (ETDEWEB)
Chanowitz, M.S.
1981-11-01
A group of three lectures on hadron spectroscopy are presented. Topics covered include: light L = 0 mesons, light L = 1 mesons, antiquark antiquark quark quark exotics, a catalogue of higher quark antiquark excitations, heavy quarkonium, and glueballs. (GHT)
Light Vector Mesons in the Nuclear Medium
Wood, M H; Weygand, D P; Djalali, C; Tur, C; Mosel, U; Mühlich, P; Adams, G; Amaryan, M J; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Battaglieri, M; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Casey, L; Chen, S; Cheng, L; Cole, P L; Collins, P; Coltharp, P; Crabb, D; Crannell, H; Credé, V; Cummings, J P; Dashyan, N; De Vita, R; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Dharmawardane, K V; Dickson, R; Dodge, G E; Doughty, D; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Feldman, G; Feuerbach, R J; Fradi, A; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gordon, C I O; Gothe, R W; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hafidi, K; Hakobyan, H; Hakobyan, R S; Hanretty, C; Hardie, J; Hassall, N; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Johnstone, J R; Joo, K; Jüngst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Khetarpal, P; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Kossov, M; Krahn, Z; Kramer, L H; Kubarovski, V; Kühn, J; Kuhn, S E; Kuleshov, S V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Ji, Li; Livingston, K; Lu, H Y; MacCormick, M; Markov, N; Mattione, P; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mehrabyan, S; Melone, J J; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Moriya, K; Morrow, S A; Moteabbed, M; Müller, J; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Sabati, F; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabyan, Yu G; Sharov, D; Shvedunov, N V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S; Stepanyan, S S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Tedeschi, D J; Tkabladze, A; Tkachenko, S; Todor, L; Ungaro, M; Vineyard, M F; Vlassov, A V; Watts, D P; Weinstein, L B; Williams, M; Wolin, E; Yegneswaran, A; Zana, L; Zhang, B; Zhang, J; Zhao, B; Zhao, Z W
2008-01-01
The light vector mesons ($\\rho$, $\\omega$, and $\\phi$) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the $\\rho$ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The $\\rho$ meson mass spectrum was extracted after the $\\omega$ and $\\phi$ signals were removed in a nearly model-independent way. Comparisons were made between the $\\rho$ mass spectra from the heavy targets ($A > 2$) with the mass spectrum extracted from the deuterium target. With respect to the $\\rho$-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body effects such as collisional...