Constituent quarks and charge particle production in heavy-ion collisions

International Nuclear Information System (INIS)

Mishra, Aditya Nath; Mazumder, Rakesh; Sahoo, Raghunath; Nandi, Basanta Kumar

2012-01-01

Relativistic heavy-ion collisions aims at producing a state of matter which is governed by partonic degree of freedom. The pseudorapidity density of particle multiplicity and transverse energy are the key observables which provide the properties of matter produced in heavy-ion collisions. Study of their dependence on centrality and collision energy is of paramount importance to understand the particle production mechanism. This may provide insight into the partonic phase that might be created in nuclear collisions. Here, in a constituent quarks framework, charged particle and transverse energy production in heavy-ion collisions are studied both as a function of centrality and collision energy, and hence the study gives a prediction for Pb + Pb collisions

Quark solitons as constituents of hadrons

International Nuclear Information System (INIS)

Ellis, J.; Frishman, Y.; Hanany, A.; Karlinev, M.

1992-01-01

We exhibit static solutions of multi-flavour QCD in two dimensions that have the quantum numbers of baryons and mesons, constructed out of quark and anti-quark solitons. In isolation the latter solitons have infinite energy, corresponding to the presence of a string carrying the non-singlet colour flux off to spatial infinity. When N c solitons of this type are combined, a static, finite-energy, colour singlet solution is formed, corresponding to a baryon. Similarly, static meson solutions are formed out of a soliton and an anti-soliton of different flavours. The stability of the mesons against annihilation is ensured by flavour conservation. The static solutions exist only when the fundamental fields of the bosonized lagrangian belong to U(N c xN f ) rather than to SU(N c )xU(N f ). Discussion of flavour-symmetry breaking requires a careful treatment of the normal-ordering ambiguity. Our results can be viewed as a derivation of the constituent quark model in QCD 2 , allowing a detailed study of constituent mass generation and of the heavy-quark symmetry. (orig.)

Hadron matrix elements of quark operators in the relativistic quark model, 2. Model calculation

Energy Technology Data Exchange (ETDEWEB)

Arisue, H; Bando, M; Toya, M [Kyoto Univ. (Japan). Dept. of Physics; Sugimoto, H

1979-11-01

Phenomenological studies of the matrix elements of two- and four-quark operators are made on the basis of relativistic independent quark model for typical three cases of the potentials: rigid wall, linearly rising and Coulomb-like potentials. The values of the matrix elements of two-quark operators are relatively well reproduced in each case, but those of four-quark operators prove to be too small in the independent particle treatment. It is suggested that the short-range two-quark correlations must be taken into account in order to improve the values of the matrix elements of the four-quark operators.

Double parton correlations in Light-Front constituent quark models

Directory of Open Access Journals (Sweden)

Rinaldi Matteo

2015-01-01

Full Text Available Double parton distribution functions (dPDF represent a tool to explore the 3D proton structure. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence quark region, by means of a constituent quark model, where two particle correlations are present without any additional prescription. This framework allows to understand the dynamical origin of the correlations and to clarify which, among the features of the results, are model independent. Use will be made of a relativistic light-front scheme, able to overcome some drawbacks of the previous calculation. Transverse momentum correlations, due to the exact treatment of the boosts, are predicted and analyzed. The role of spin correlations is also shown. Due to the covariance of the approach, some symmetries of the dPDFs are seen unambigously. For the valence sector, also the study of the QCD evolution of the model results, which can be performed safely thanks to the property of good support, has been also completed.

Radiative leptonic B{sub c} decay in the relativistic independent quark model

Energy Technology Data Exchange (ETDEWEB)

Barik, N [Department of Physics, Utkal University, Bhubaneswar-751004 (India); Naimuddin, Sk; Dash, P C [Department of Physics, Prananath Autonomous College, Khurda-752057 (India); Kar, Susmita [Department of Physics, North Orissa University, Baripada-757003 (India)

2008-12-01

The radiative leptonic decay B{sub c}{sup -}{yields}{mu}{sup -}{nu}{sub {mu}}{gamma} is analyzed in its leading order in a relativistic independent quark model based on a confining potential in an equally mixed scalar-vector harmonic form. The branching ratio for this decay in the vanishing lepton mass limit is obtained as Br(B{sub c}{yields}{mu}{nu}{sub {mu}}{gamma})=6.83x10{sup -5}, which includes the contributions of the internal bremsstrahlung and structure-dependent diagrams at the level of the quark constituents. The contributions of the bremsstrahlung and the structure-dependent diagrams, as well as their additive interference parts, are compared and found to be of the same order of magnitude. Finally, the predicted photon energy spectrum is observed here to be almost symmetrical about the peak value of the photon energy at E-tilde{sub {gamma}}{approx_equal}(M{sub B{sub c}}/4), which may be quite accessible experimentally at LHC in near future.

Successes and failures of the constituent quark model

International Nuclear Information System (INIS)

Lipkin, H.J.

1982-01-01

Our approach considers the model as a possible bridge between QCD and the experimental data and examines its predictions to see where these succeed and where they fail. We also attempt to improve the model by looking for additional simple assumptions which give better fits to the experimental data. But we avoid complicated models with too many ad hoc assumptions and too many free parameters; these can fit everything but teach us nothing. We define our constituent quark model by analogy with the constituent electron model of the atom and the constituent nucleon model of the nucleus. In the same way that an atom is assumed to consist only of constituent electrons and a central Coulomb field and a nucleus is assumed to consist only of constituent nucleons hadrons are assumed to consist only of their constituent valence quarks with no bag, no glue, no ocean, nor other constituents. Although these constituent models are oversimplified and neglect other constituents we push them as far as we can. Atomic physics has photons and vacuum polarization as well as constituent electrons, but the constituent model is adequate for calculating most features of the spectrum when finer details like the Lamb shift are neglected. 54 references

Constituent quark mass and nucleon properties in nuclei

International Nuclear Information System (INIS)

Beyer, M.; Singh, S.K.

1986-01-01

It is shown that the Nolen-Schiffer anomaly, the quenching of gsub(A) and the increase in some electromagnetic properties of nucleons in nuclei can all be explained qualitatively in a constituent quark model if the quark mass is assumed to depend on its confinement size. (author)

Do quarks play an explicit role as nuclear constituents ?

International Nuclear Information System (INIS)

Yamazaki, Toshimitsu.

1986-10-01

Experimental signatures for explicit roles of quarks as nuclear constituents are looked for. It is stressed that hyperons in nuclei may reveal unique information on nuclear interior and possible quark deconfinement. Future directions of hypernuclear spectroscopy are discussed. (author)

Constituent quarks and the gluonic contribution to the spin of the nucleon

International Nuclear Information System (INIS)

Eldahoumi, Gamal

2009-01-01

The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)

Constituent quarks and the gluonic contribution to the spin of the nucleon

Energy Technology Data Exchange (ETDEWEB)

Eldahoumi, Gamal

2009-01-15

The internal structure of the nucleon is more complicated than expected in a simple quark model. In particular, the portion of the nucleon spin carried by the spins of the quarks is not, as expected, of the order of one, but according to the experimental data much smaller. In this thesis we study the spin structure of the proton in quantum chromodynamics. The constituent quark model, based on SU(6), predicts that the spin of the proton should be carried by the quarks, in disagreement with the experiments. It appears strange, that the theoretical model works so well for the magnetic moments of the nucleons, but not for the spin, although the spin and the magnetic moments are closely related to each other. We shall resolve this problem by assuming that the constituent quarks have an internal structure on their own. Thus a constituent quark has a dynamical structure, and we can introduce notions like the quark or gluon distributions inside a constituent quark. In the light of new experimental data from HERMES, COMPASS, JLab, and RHIC-spin, the current status of our knowledge of the spin structure is discussed in the two theoretical frameworks: the naive parton model, and the QCD evolved parton model. QCD a is successful theory, both in perturbative and non-perturbative regions, but the spin of the nucleon still needs to be explained within QCD. (orig.)

Constituent quarks and multi-strange baryon production in heavy-ion collisions

International Nuclear Information System (INIS)

Sahoo, Raghunath; Behera, Nirbhay K.; Nandi, Basanta K.; Varma, Raghava

2009-01-01

Relativistic heavy-ion collisions aim at creating matter at extreme conditions of energy density and temperature which is governed by the partonic degrees of freedom called Quark-Gluon Plasma (QGP). In the early phase of ultra-relativistic heavy ion collisions, when a hot and dense region is formed in the core of the reaction zone, different quark flavors are produced copiously. The produced matter then undergoes transverse expansion and the produced particles suffer multiple scattering among themselves. The formation of the hadrons from the partonic phase is accomplished through further expansion and cooling of the system

Relativistic bound state wave functions

International Nuclear Information System (INIS)

Micu, L.

2005-01-01

A particular method of writing the bound state wave functions in relativistic form is applied to the solutions of the Dirac equation with confining potentials in order to obtain a relativistic description of a quark antiquark bound system representing a given meson. Concerning the role of the effective constituent in the present approach we first observe that without this additional constituent we couldn't expand the bound state wave function in terms of products of free states. Indeed, we notice that if the wave function depends on the relative coordinates only, all the expansion coefficients would be infinite. Secondly we remark that the effective constituent enabled us to give a Lorentz covariant meaning to the potential energy of the bound system which is now seen as the 4th component of a 4-momentum. On the other side, by relating the effective constituent to the quantum fluctuations of the background field which generate the binding, we provided a justification for the existence of some spatial degrees of freedom accompanying the interaction potential. These ones, which are quite unusual in quantum mechanics, in our model are the natural consequence of the the independence of the quarks and can be seen as the effect of the imperfect cancellation of the vector momenta during the quantum fluctuations. Related with all these we remark that the adequate representation for the relativistic description of a bound system is the momentum representation, because of the transparent and easy way of writing the conservation laws and the transformation properties of the wave functions. The only condition to be fulfilled is to find a suitable way to take into account the potential energy of the bound system. A particular feature of the present approach is that the confining forces are due to a kind of glue where both quarks are embedded. This recalls other bound state models where the wave function is factorized in terms of constituent wave functions and the confinement is

Constituent quarks in nuclear matter and the Nolen-Schiffer anomaly

International Nuclear Information System (INIS)

Lutz, M.; Lee, H.K.; Weise, W.

1991-01-01

We investigate the density dependence of the neutron-proton mass difference using the Nambu and Jona-Lasinio model in combination with the Isgur-Karl constituent quark model. The decrease of the constituent quark masses with increasing density reduces the n-p mass difference in the proper way to help resolving the Nolen-Schiffer anomaly. We point out however, that in the presence of vector interactions, this effect is less pronounced than previously suggested. (orig.)

Kaon quark distribution functions in the chiral constituent quark model

Science.gov (United States)

Watanabe, Akira; Sawada, Takahiro; Kao, Chung Wen

2018-04-01

We investigate the valence u and s ¯ quark distribution functions of the K+ meson, vK (u )(x ,Q2) and vK (s ¯)(x ,Q2), in the framework of the chiral constituent quark model. We judiciously choose the bare distributions at the initial scale to generate the dressed distributions at the higher scale, considering the meson cloud effects and the QCD evolution, which agree with the phenomenologically satisfactory valence quark distribution of the pion and the experimental data of the ratio vK (u )(x ,Q2)/vπ (u )(x ,Q2) . We show how the meson cloud effects affect the bare distribution functions in detail. We find that a smaller S U (3 ) flavor symmetry breaking effect is observed, compared with results of the preceding studies based on other approaches.

Relativistic few quark dynamics for hadrons

International Nuclear Information System (INIS)

Mitra, A.N.

1983-07-01

A microscopic confinement approach is presented to a few quarks systems through an effective (harmonic) kernel inserted at the level of q-q-bar and q-q pairs, using the vehicle of the Bethe-Salpeter equation for each such system. The formalism, which is realistic for light quark systems (which require an intrinsically relativistic treatment), has been developed in a simple enough form so as to be applicable in practice to a large class of phenomena amenable to experimental test. The comparison over a wide range of hadronic properties (from mass spectra to current matrix elements), all within a single integrated framework, would seem to strongly support the ansatz of universality of the reduced spring constant (ω-tilde) which plays a role analogous to the bag radius, but at a far more microscopic level

Quark-flavor mixing and the nucleon strangeness form factors

International Nuclear Information System (INIS)

Ito, H.

1995-01-01

We have calculated the strangeness form factors of the nucleon G E s (Q), G M s (Q) and G A s (Q) and the electromagnetic form factors G E N (Q) as well, by using a relativistic constituent quark model of the nucleon wave function on the light-cone. Octet of Goldstone bosons (π, K, η) are assumed to induce the SU flavor mixing among the light constituent quarks; d-→K+s →d for example, and this mechanism induces the strangeness content in the nucleon. To calculate the meson-loop corrections to the electroweak couplings of constituent quarks, we have employed two models of the quark-meson vertex; (1) composite model of the Goldstone bosons (2) and (3) chiral quark Lagrangian. The loop momenta are regulated in a gauge-invariant way for both models

A relativized quark model for radiative baryon transitions

International Nuclear Information System (INIS)

Warns, M.; Schroeder, H.; Pfeil, W.; Rollnik, H.

1989-03-01

In this paper we investigate the electromagnetic form factors of baryons and their resonances using the framework of a relativized constituent quark model. Beyond the usual single-quark transition ansatz, we incorporate relativistic corrections which are well-determined by the intrinsic strong interaction and confinement forces between the quarks. Furthermore we separate off for the compound three-quark system the relativistic center-of-mass motion by an approximately Lorentz-invariant approach. In this way for the first time recoil effects could be explicitly studied. Using the harmonic oscillator wavefunctions with the configuration mixing as derived in the Isgur-Karl model, after restoring gauge invariance our relativized interaction hamiltonian can be used to calculate the transversely and longitudinally polarized photon transition form factors of the baryons. (orig.)

Deformed baryons: constituent quark model vs. bag model

International Nuclear Information System (INIS)

Iwamura, Y.; Nogami, Y.

1985-01-01

Recently Bhaduri et al. developed a nonrelativistic constituent quark model for deformed baryons. In that model the quarks move in a deformable mean field, and the deformation parameters are determined by minimizing the quark energy subject to the constraint of volume conservation. This constraint is an ad hoc assumption. It is shown that, starting with a bag model, a model similar to that of Bhaduri et al. can be constructed. The deformation parameters are determined by the pressure balance on the bag surface. There is, however, a distinct difference between the two models with respect to the state dependence of the ''volume''. Implications of this difference are discussed

Elastic and radiative heavy quark interactions in ultra-relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Uphoff, Jan; Fochler, Oliver; Xu, Zhe; Greiner, Carsten

2015-01-01

Elastic and radiative heavy quark interactions with light partons are studied with the partonic transport model named the Boltzmann approach to multiparton scatterings (BAMPSs). After calculating the cross section of radiative processes for finite masses in the improved Gunion–Bertsch approximation and verifying this calculation by comparing to the exact result, we study elastic and radiative heavy quark energy loss in a static medium of quarks and gluons. Furthermore, the full 3 + 1D space–time evolution of gluons, light quarks, and heavy quarks in ultra-relativistic heavy-ion collisions at the BNL Relativistic Heavy-Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are calculated with BAMPS including elastic and radiative heavy flavor interactions. Treating light and heavy particles on the same footing in the same framework, we find that the experimentally measured nuclear modification factor of charged hadrons and D mesons at the LHC can be simultaneously described. In addition, we calculate the heavy flavor evolution with an improved screening procedure from hard-thermal-loop calculations and confront the results with experimental data of the nuclear modification factor and the elliptic flow of heavy flavor particles at the RHIC and the LHC. (paper)

Radiative transitions in mesons within a non relativistic quark model

International Nuclear Information System (INIS)

Bonnaz, R.; Silvestre-Brac, B.; Gignoux, C.

2002-01-01

An exhaustive study of radiative transitions in mesons is performed in a non relativistic quark model. Three different types of mesons wave functions are tested. The effect of some usual approximations is commented. Overall agreement with experimental data is obtained

Radiative transitions of B and Bs mesons in a non relativistic quark model with hulthen potential

International Nuclear Information System (INIS)

D'Souza, Praveen P.; Monteiro, A.P.; Vijaya Kumar, K.B.

2017-01-01

Heavy light mesons composed of one heavy quark and one light quark. They are the only mesons containing quarks of the third generation. Which has contributed enormously to our understanding of elementary particles and their interactions. In our calculation we get variational parameter for different heavy-light mesons. Having variational parameter eigen energy will be obtained. For meson system, the Hulthen term acts like a Coulombic term. The spin dependent potential from One Gluon Exchange Potential (OGEP) is introduced. The goal of the present work is to obtain the decay widths and understand the uncertainties in the calculation in the frame work of non-relativistic quark models. In the non-relativistic models this is satisfied for the c, b and t quarks

Ground-state triply and doubly heavy baryons in a relativistic three-quark model

International Nuclear Information System (INIS)

Martynenko, A.P.

2008-01-01

Mass spectra of the ground-state baryons consisting of three or two heavy (b or c) and one light (u,d,s) quarks are calculated in the framework of the relativistic quark model and the hyperspherical expansion. The predictions of masses of the triply and doubly heavy baryons are obtained by employing the perturbation theory for the spin-independent and spin-dependent parts of the three-quark Hamiltonian

Tensor Susceptibilities of the Vacuum from Constituent Quarks

International Nuclear Information System (INIS)

Broniowski, W.; Polyakov, M.; Goeke, K.; Hyun-Chul Kim

1998-01-01

We show that the constituent quark model leads to simple expression for the isoscalar and isovector tensor susceptibilities of the vacuum. The found values are negative and of magnitude compatible with QCD-sum-rule parametrizations of spectral densities in appropriate L=1-meson channels. (author)

Tensor Susceptibilities of the Vacuum from Constituent Quarks

Energy Technology Data Exchange (ETDEWEB)

Broniowski, W [The H. Niewodniczanski Institute of Nuclear Physics, Cracow (Poland); Polyakov, M; Goeke, K [Institute for Theoretical Physics II, Ruhr-Universitaet-Bochum, Bochum (Germany); Kim, Hyun-Chul [Pusan National University, Department of Physics, Pusan (Korea, Republic of)

1998-05-15

We show that the constituent quark model leads to simple expression for the isoscalar and isovector tensor susceptibilities of the vacuum. The found values are negative and of magnitude compatible with QCD-sum-rule parametrizations of spectral densities in appropriate L=1-meson channels. (author)

Color exotic constituent quarks and their possible manifestations in hadron spectroscopy

International Nuclear Information System (INIS)

Anisovich, V.V.

1985-01-01

Hypothetical colour-exotic constituent (or dressed) quarks are discussed. It is shown that the data on the excited baryons with Jsup(P)=1/2 + , 3/2 + and excited mesons with Jsup(P)=0 - , 1 - are in reasonable agreement with the hypothesis of the existence of colour-exotic quark in the colour state 6

Current quarks and constituent-classification quarks: some questions and ideas

International Nuclear Information System (INIS)

Close, F.E.

1977-01-01

A brief introduction is given to the spin dependence of inelastic photo and electroproduction. Parton model predictions of Kuti and Weisskopf are then criticized and a paradox noted in connection with a sum rule of Bjorken. The resolution of this paradox raises several questions concerning the constituent and current quark approaches to resonance excitation. Particular attention is given to current algebra constraints, angular momentum in the nucleon, the x → 1 behavior of inelastic electroproduction, psi production and radiative decays

B-meson decay constants from 2+1-flavor lattice QCD with domain-wall light quarks and relativistic heavy quarks

Energy Technology Data Exchange (ETDEWEB)

Christ, Norman H. [Columbia Univ., New York, NY (United States); Flynn, Jonathan M. [Univ. of Southampton, Southampton (United Kingdom); Izubuchi, Taku [Brookhaven National Lab. (BNL), Upton, NY (United States); Kawanai, Taichi [RIKEN, Wako (Japan); Brookhaven National Lab. (BNL), Upton, NY (United States); Lehner, Christoph [Brookhaven National Lab. (BNL), Upton, NY (United States); Soni, Amarjit [Brookhaven National Lab. (BNL), Upton, NY (United States); Van de Water, Ruth S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Witzel, Oliver [Boston Univ., Boston, MA (United States)

2015-03-10

We calculate the B-meson decay constants f_B, f_Bs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M_π ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(α_sa). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f_B⁰ = 196.2(15.7) MeV, f_B⁺ = 195.4(15.8) MeV, f_Bs = 235.4(12.2) MeV, f_Bs/f_B⁰ = 1.193(59), and f_Bs/f_B⁺ = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.

Particle production in high energy collisions and the non-relativistic quark model

International Nuclear Information System (INIS)

Anisovich, V.V.; Nyiri, J.

1981-07-01

The present review deals with multiparticle production processes at high energies using ideas which originate in the non-relativistic quark model. Consequences of the approach are considered and they are compared with experimental data. (author)

Ultra relativistic heavy ions collisions or the search for quark-gluon plasmas

International Nuclear Information System (INIS)

Blaizot, J.P.

1985-03-01

This paper reviews some aspects of the physics of ultra-relativistic heavy ion collisions. The qualitative changes expected in the properties of hadronic matter at high temperature and/or large baryon density are described in terms of simple models. We discuss a scenario giving the space-time evolution of a quark-gluon plasma. Finally we address the difficult question of the possible signatures of the formation of a quark-gluon plasma in heavy ion collisions

Definition of mass spectrum of mesons taking into account relativistic character of interactions

International Nuclear Information System (INIS)

Dinejkhan, M.; Zhaugasheva, S.A.; Karimzhan, K.

2009-01-01

Taking into account relativistic and nonlocal character of interactions, the mass spectrum of the mesons consisting of the light-light and light-heavy quarks with orbital and radial excitations, is determined. Our result show that good agreement with the experimental data for the slope and the intercept of the Regge trajectory can be obtained, only taking into account the nonperturbative and the nonlocal character of interactions. Dependence of constituent mass of constituent particles on mass of a free state is certain. When quarks are light the difference of current and valent masses of quarks is greater than valent masses of quarks, and when quarks are heavy the difference of these masses is insignificant. One of alternative variants of the account of nonlocality is suggested for the definition of properties of hadrons at large distances. Dependence of constituent mass on the radius of confinement is studied

Low energy constituent quark and pion effective couplings in a weak external magnetic field

Science.gov (United States)

Braghin, Fábio L.

2018-03-01

An effective model with pions and constituent quarks in the presence of a weak external background electromagnetic field is derived by starting from a dressed one gluon exchange quark-quark interaction. By applying the auxiliary field and background field methods, the structureless pion limit is considered to extract effective pion and constituent quark couplings in the presence of a weak magnetic field. The leading terms of a large quark and gluon masses expansion are obtained by resolving effective coupling constants which turn out to depend on a weak magnetic field. Two pion field definitions are considered for that. Several relations between the effective coupling constants and parameters can be derived exactly or in the limit of very large quark mass at zero and weak constant magnetic field. Among these ratios, the Gell-Mann-Oakes-Renner and the quark level Goldberger-Treiman relations are obtained. In addition to that, in the pion sector, the leading terms of Chiral Perturbation Theory coupled to the electromagnetic field are recovered. Some numerical estimates are provided for the effective coupling constants and parameters.

Sivers function in constituent quark models

CERN Document Server

Scopetta, S.; Fratini, F.; Vento, V.

2008-01-01

A formalism to evaluate the Sivers function, developed for calculations in constituent quark models, is applied to the Isgur-Karl model. A non-vanishing Sivers asymmetry, with opposite signs for the u and d flavor, is found; the Burkardt sum rule is fulfilled up to 2 %. Nuclear effects in the extraction of neutron single spin asymmetries in semi-inclusive deep inelastic scattering off 3He are also evaluated. In the kinematics of JLab, it is found that the nuclear effects described by an Impulse Approximation approach are under control.

Parton distributions and EMC ratios of the 6Li nucleus in the constituent quark exchange model

Science.gov (United States)

Modarres, M.; Hadian, A.

2017-10-01

While the constituent quark model (CQM), in which the quarks are assumed to be the complex objects, is used to calculate the parton distribution functions of the iso-scalar lithium-6 (6Li) nucleus, the u-d constituent quark distribution functions of the 6Li nucleus are evaluated from the valence quark exchange formalism (VQEF) for the A = 6 iso-scalar system. After computing the valence quark, sea quark, and gluon distribution functions in the constituent quark exchange model (CQEM, i.e., CQM +VQEF), the nucleus structure function is calculated for the 6Li nucleus at the leading order (LO) and the next-to-leading-order (NLO) levels to extract the European muon collaboration (EMC) ratio, at different hard scales, using the standard Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGALP) evolution equations. The outcomes are compared with those of our previous works and the available NMC experimental data, and various physical points are discussed. It is observed that the present EMC ratios are considerably improved compared with those of our previous works, in which only the valence quark distributions were considered to calculate the EMC ratio, and are closer to the NMC data. Finally, it is concluded that at a given appropriate hard scale, the LO approximation may be enough for calculating the nucleus EMC ratio.

KN phase shifts in a constituent quark model

International Nuclear Information System (INIS)

Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

2001-01-01

In a first step, the I=1 and I=0 kaon-nucleon s-wave phase shifts have been calculated in a quark potential model using the resonating group method (RGM) and a relativistic kinematics. The spinless Salpeter equation has been solved numerically using the Fourier grid hamiltonian method. The results have been compared to the nonrelativistic ones. For each isospin channel the phase shifts obtained are not so far from the nonrelativistic results. Then, K-nucleon p, d, f, g-waves phase shifts have been calculated using a nonrelativistic kinematics

Influence of a relativistic kinematics on s-wave KN phase shifts in a quark model

International Nuclear Information System (INIS)

Lemaire, S.; Labarsouque, J.; Silvestre-Brac, B.

2001-01-01

The I = 1 and I = 0 kaon-nucleon s-wave phase shifts have been calculated in a quark potential model using the resonating group method (RGM) and a relativistic kinematics. The spinless Salpeter equation has been solved numerically using the Fourier grid Hamiltonian method. The results have been compared to the non-relativistic ones. For each isospin channel the phase shifts obtained are not so far from the non-relativistic results. (author)

Determination of quark-antiquark potentials and meson spectra

International Nuclear Information System (INIS)

Semay, C.; Silvestre-Brac, B.

1999-01-01

We determine two different sets of quark-antiquark potential to be used in a Schroedinger or a Salpeter type of equation. The central part contains QCD inspired components: the Coulomb like interaction, the confinement potential and an instanton interaction. It is supplemented with phenomenological relativistic corrections. The constituent quarks are characterized by a colour charge density. The parameters are determined by a minimization procedure on representative samples of mesons and the full spectra are calculated. Refs. 6, tabs. 2 (author)

Electromagnetic splitting for mesons and baryons using dressed constituent quarks

International Nuclear Information System (INIS)

Silvestre-Brac, Bernard; Brau, Fabian; Semay, Claude

2003-01-01

Electromagnetic splittings for mesons and baryons are calculated in a formalism where the constituent quarks are considered as dressed quasiparticles. The electromagnetic interaction, which contains coulomb, contact and hyperfine terms, is folded with the quark electrical density. Two different types of strong potentials are considered. Numerical treatment is done very carefully and several approximations are discussed in detail. Our model contains only one free parameter and the agreement with experimental data is reasonable although it seems very difficult to obtain a perfect description in any case

Tetraquarks in a chiral constituent-quark model

International Nuclear Information System (INIS)

Vijande, J.; Fernandez, F.; Valcarce, A.; Silvestre-Brac, B.

2004-01-01

We analyze the possibility of heavy-light tetraquark bound states by means of a chiral constituent-quark model. The study is done in a variational approach. Special attention is paid to the contribution given by the different terms of the interacting potential and also to the role played by the different color channels. We find a stable state for both qq anti c anti c and qq anti b anti b configurations. Possible decay modes of these structures are analyzed. (orig.)

Tetraquarks in a chiral constituent-quark model

Energy Technology Data Exchange (ETDEWEB)

Vijande, J.; Fernandez, F.; Valcarce, A. [Grupo de Fisica Nuclear, Universidad de Salamanca, E-37008, Salamanca (Spain); Silvestre-Brac, B. [Institut des Sciences Nucleaires, 53 Avenue des Martyrs, F-38026, Grenoble Cedex (France)

2004-03-01

We analyze the possibility of heavy-light tetraquark bound states by means of a chiral constituent-quark model. The study is done in a variational approach. Special attention is paid to the contribution given by the different terms of the interacting potential and also to the role played by the different color channels. We find a stable state for both qq anti c anti c and qq anti b anti b configurations. Possible decay modes of these structures are analyzed. (orig.)

Spin content of constituent quarks and one-spin asymmetries in inclusive processes

International Nuclear Information System (INIS)

Troshin, S.M.; Tyurin, N.E.

1995-01-01

A mechanism for one-spin asymmetries observed in inclusive hadron production is considered. The main role belongs to the orbital angular momentum of the quark-antiquark cloud in the internal structure of constituent quarks. The origin of the asymmetries in pion production is a result of retaining this internal angular orbital momentum by the perturbative phase of QCD under transition from the non-perturbative phase is proved. The non-perturbative hadron structure is based on the results of chiral quark models. 33 refs.; 8 figs

Rare Λb→Λ l+l- and Λb→Λ γ decays in the relativistic quark model

Science.gov (United States)

Faustov, R. N.; Galkin, V. O.

2017-09-01

Rare Λb→Λ l+l- and Λb→Λ γ decays are investigated in the relativistic quark model based on the quark-diquark picture of baryons. The decay form factors are calculated accounting for all relativistic effects, including relativistic transformations of baryon wave functions from rest to a moving reference frame and the contribution of the intermediate negative-energy states. The momentum-transfer-squared dependence of the form factors is explicitly determined in the whole accessible kinematical range. The calculated decay branching fractions, various forward-backward asymmetries for the rare decay Λb→Λ μ+μ-, are found to be consistent with recent detailed measurements by the LHCb Collaboration. Predictions for the Λb→Λ τ+τ- decay observables are given.

Constituent quarks and enhancement of multi-strange baryons in heavy-ion collisions

International Nuclear Information System (INIS)

Behera, Nirbhay Kumar; Nandi, Basanta Kumar; Sahoo, Raghunath

2011-01-01

Heavy-ion collisions at relativistic energies aim to produce a state of matter which is governed by partonic degrees of freedom, known as Quark-Gluon Plasma (QGP). In the central rapidity region, strangeness enhancement has been proposed as a potential signature of QGP. It has been observed that a quark participant scaling of the multi-strange baryon production and also a strangeness scaling of the enhancement. This confirms that the partonic degrees of freedom is playing a major role in the particle production mechanism and may therefore significantly determine the formation of QGP in heavy ion collisions

Quark-quark interactions

International Nuclear Information System (INIS)

Jacob, M.

1982-01-01

This chapter discusses interactions only at the constituent level, as observed in hadron-hadron collisions. It defines quarks and gluons as constituents of the colliding hadrons, reviews some applications of perturbative OCD, discussing in turn lepton pair production, which in lowest order approximation corresponds to the Drell-Yan process. It investigates whether quark-quark interactions could not lead to some new color structure different from those prevalent for known baryons and mesons, which could be created in hadron interactions, and whether color objects (not specifically quarks or gluons) could not appear as free particles. Discussed is perturbative QCD in hadron collisions; the quark approach to soft processes; and new color structures. It points out that perturbative QCD has been at the origin of much progress in the understanding of hadron interactions at the constituent level

Experimental developments in relativistic heavy-ion collisions published between Quark Matter 2002 and the beginning of Quark Matter 2004

International Nuclear Information System (INIS)

Hemmick, Thomas K

2004-01-01

The Quark Matter conference is the 'meeting of record' for the field of relativistic heavy-ion physics. Each such conference is filled with exciting new data frequently presented to the world for the first time. However, the field also makes significant progress during the 18 months between Quark Matter conferences. Such progress is summarized in a single talk near the beginning of the conference and sets the stage for the newest data and discoveries. This paper is the experimental summary of selected results published in journals and presented at conferences between the end of QM2002 and the beginning of QM2004

Light-cone quark model with spin force for the nucleon and Δ(1232)

International Nuclear Information System (INIS)

Weber, H.J.

1992-01-01

Electromagnetic structure functions for the nucleon, static observables for the nucleon and N→D(1232) transition form factors are calculated in a relativistic constituent quark model on the light cone. The model simulates the main effect of the spin force between quarks in terms of smaller (and lighter) scalar ud diquarks in the nucleon. The polarized proton structure function is found to agree with the EMC data. (orig.)

Quark-diquark approximation of the three-quark structure of baryons in the quark confinement model

International Nuclear Information System (INIS)

Efimov, G.V.; Ivanov, M.A.; Lyubovitskij, V.E.

1990-01-01

Octet (1 + /2) and decuplet (3 + /2) of baryons as relativistic three-quark states are investigated in the quark confinement model (QCM), the relativistic quark model, based on some assumptions about hadronization and quark confinement. The quark-diquark approximation of the three-quark structure of baryons is proposed. In the framework of this approach the description of the main low-energy characteristics of baryons as magnetic moments, electromagnetic radii and form factors, ratio of axial and vector constants in semileptonic baryon octet decays, strong form factors and decay widths is given. The obtained results are in agreement with experimental data. 31 refs.; 4 figs.; 5 tabs

Studies on the quark confinement in a non-relativistic quark model

International Nuclear Information System (INIS)

Pfenninger, T.

1988-01-01

In the framework of the non-relativistic quark model we have studied several aspects of the description of the confinement by a confinement potential. A first consideration applied to the effects of the long-range color van-der-Waals forces on the nucleon-nucleon scattering. Regarding color dipole states as an additional closed channel in a dynamical and nonlocal resonating-group calculation we found a strong attraction. Additionally it was possible by means of the RGM kernels to derive an against earlier calculations improved color van-der-Waals potential in adiabatic approximation which regards correctly the internal kinetic and the confinement energy of the color octet states. This potential is not confined to large NN distances and shows asymptotically a 1/R 2 behaviour if it is based on a harmonic confinement. A further study applied to the question how far a possible vector character of the confinement, which is suggested by the elementary quark-gluon vertex, has effects on baryon properties and the NN interaction. Here it resulted that the vector confinement reacts in view of the model parameters very sensitively in the baryon properties whereas the scalar confinement did not show this dependence. In the NN scattering this vector confinement however plays a more secondary role. Because of the difficulties of the usual confinement potential with long-range color van-der-Waals forces we proposed in the last part a new potential and additional orthogonality relations for the quark wave functions in order to accomodate in the potential model to the string degrees of freedom. In scattering calculations we again studied the effects of the modification on the NN interaction. (orig./HSI) [de

Lowest-lying even-parity anti B{sub s} mesons: heavy-quark spin-flavor symmetry, chiral dynamics, and constituent quark-model bare masses

Energy Technology Data Exchange (ETDEWEB)

Albaladejo, M.; Fernandez-Soler, P.; Nieves, J.; Ortega, P.G. [Centro Mixto CSIC-Universidad de Valencia, Instituto de Fisica Corpuscular (IFIC), Institutos de Investigacion de Paterna, Aptd. 22085, Valencia (Spain)

2017-03-15

The discovery of the D{sup *}{sub s0}(2317) and D{sub s1}(2460) resonances in the charmed-strange meson spectra revealed that formerly successful constituent quark models lose predictability in the vicinity of two-meson thresholds. The emergence of non-negligible effects due to meson loops requires an explicit evaluation of the interplay between Q anti q and (Q anti q)(q anti q) Fock components. In contrast to the c anti s sector, there is no experimental evidence of J{sup P} = 0{sup +}, 1{sup +} bottom-strange states yet. Motivated by recent lattice studies, in this work the heavy-quark partners of the D{sub s0}{sup *}(2317) and D{sub s1}(2460) states are analyzed within a heavy meson chiral unitary scheme. As a novelty, the coupling between the constituent quark-model P-wave anti B{sub s} scalar and axial mesons and the anti B{sup (*)}K channels is incorporated employing an effective interaction, consistent with heavy-quark spin symmetry, constrained by the lattice energy levels. (orig.)

Search for free quarks produced in ultra-relativistic collisions at BNL [Brookhaven National Laboratory] and CERN [European Organization for Nuclear Research

International Nuclear Information System (INIS)

Matis, H.S.; Pugh, H.G.; Alba, G.P.; Bland, R.W.; Calloway, D.H.; Dickson, S.; Hodges, C.L.; Palmer, T.L.; Stricker, D.A.; Johnson, R.T.

1990-07-01

A high intensity experiment was performed to search for free quarks at BNL and CERN using ultra-relativistic beams. The experiment was designed to trap quarks in a Hg target or liquid Ar tank. No free quark candidate was found. Limits from 10 -7 to 10 -10 quarks per incident ion are reported. 7 refs., 2 figs., 2 tabs

Quark confinement in a constituent quark model

International Nuclear Information System (INIS)

Langfeld, K.; Rho, M.

1995-01-01

On the level of an effective quark theory, we define confinement by the absence of quark anti-quark thresholds in correlation function. We then propose a confining Nambu-Jona-Lasinio-type model. The confinement is implemented in analogy to Anderson localization in condensed matter systems. We study the model's phase structure as well as its behavior under extreme conditions, i.e. high temperature and/or high density

Bound nucleon structure function in the picture of relativistic constituent quarks

International Nuclear Information System (INIS)

Grigoryan, L.A.; Shakhbazyan, V.A.

1987-01-01

The structure function F 2N of nucleons in the deuterium, carbon and iron nuclei is calculated as a function of Q 2 in two approaches: taking into account the nucleon swelling in nuclei due to the partial deconfinement of quarks in nuclear medium; in the conventional approach of nuclear physics, taking into account the getting off the mass shell of the bound nucleon and Fermi motion in nucleons. It is shown that the conventional approach of nuclear physics does not explain the EMC effect in the region of small x

The baryonic spectrum in a constituent quark model including a three-body force

International Nuclear Information System (INIS)

Desplanques, B.; Gignoux, C.; Silvestre-Brac, B.; Gonzalez, P.; Navarro, J.; Noguera, S.

1992-01-01

We analyze, within a non-relativistic quark model, the low energy part of the baryonic spectrum in the octet and decuplet flavour representations. The relevance of a strong Coulomb potential is emphasized in order to explain its general features. The addition of a three-body force allows to solve the 'Roper puzzle', giving a consistent explanation to its relative position in the spectrum. (orig.)

Relativistic meson spectroscopy in momentum space

International Nuclear Information System (INIS)

Hersbach, H.

1994-01-01

In this paper a relativistic constituent-quark model based on the Ruijgrok--de Groot formalism is presented. The quark model is not defined in configuration space, but in momentum space. The complete meson spectrum, with the exception of the self-conjugate light unflavored mesons, is calculated. The potential used consists of a one-gluon exchange (OGE) part and a confining part. For the confining part a relativistic generalization of the linear plus constant potential was used, which is well defined in momentum space without introducing any singularities. For the OGE part several potentials were investigated. Retardations were included at all places. By the use of a fitting procedure involving 52 well-established mesons, but results were obtained for a potential consisting of a purely vector Richardson potential and a purely scalar confining potential. Reasonable results were also obtained for a modified Richardson potential. Most meson masses, with the exception of the π, the K, and the K 0 * , were found to be quite well described by the model

Ratios of Vector and Pseudoscalar B Meson Decay Constants in the Light-Cone Quark Model

Science.gov (United States)

Dhiman, Nisha; Dahiya, Harleen

2018-05-01

We study the decay constants of pseudoscalar and vector B meson in the framework of light-cone quark model. We apply the variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of β (scale parameter). Then with the help of known values of constituent quark masses, we obtain the numerical results for the decay constants f_P and f_V, respectively. We compare our numerical results with the existing experimental data.

Electromagnetic moments of hadrons and quarks in a hybrid model

International Nuclear Information System (INIS)

Gerasimov, S.B.

1989-01-01

Magnetic moments of baryons are analyzed on the basis of general sum rules following from the theory of broken symmetries and quark models including the relativistic effects and hadronic corrections due to the meson exchange currents. A new sum rule is proposed for the hyperon magnetic moments, which is in accord with the most precise new data and also with a theory of the electromagnetic ΛΣ 0 mixing. The numerical values of the quark electromagnetic moments are obtained within a hybrid model treating the pion cloud effects through the local coupling of the pion field with the constituent massive quarks. Possible sensitivity of the weak neutral current magnetic moments to violation of the Okubo-Zweig-Izuki rule is emphasized nand discussed. 39 refs.; 1 fig

Hadron form factors in the constituent quark model

International Nuclear Information System (INIS)

Cardarelli, F.; Salme', G.; Simula, S.; Pace, E.

1998-01-01

Hadron electromagnetic form factors are evaluated in a light-front constituent quark model based on the eigenfunctions of a mass operator, including in the q-q interaction a confining term and a one-gluon-exchange term (OGE). The spin-dependent part of the interaction plays an essential role for obtaining both a proper fit of the experimental nucleon electromagnetic form factors and the faster than dipole decrease of the magnetic N-P 33 (1232) transition form factor. The effects of the D wave, produced by the tensor part of the OGE interaction, on the quadrupole and Coulomb N-P 33 (1232) transition form factors have been found to be negligible. (author)

Various decays of some hadronic systems in constituent quark models

International Nuclear Information System (INIS)

Bonnaz, R.

2001-09-01

The topic of this study is the decay of mesons in constituent quark models. Those models as well as the various quark-antiquark interaction potentials are presented. Strong decay of a meson into two or three mesons is studied in the second part. The original 3 P o model is presented as well as the research of a vertex function γ(p) depending on the momentum for the created qq-bar pair. We show that a function γ(p) of constant+Gaussian type is superior than the constant usually used. The second part is dedicated to electromagnetic transitions studied through the emission of a real or a virtual photon. In the case of real photon emission, the different approximations found in the literature are reviewed and compared to the formalism going beyond the long wave length approximation. Mixing angles are tested for some mesons. In the case of virtual photon, the expression of decay width obtained by van Royen and Weisskopf is re-demonstrated and then improved by taking into account the quark momentum distribution inside the meson. An electromagnetic dressing of quarks is introduced that improves the results. All along this study, wave functions of various sophistication degrees are used. The results of decay widths are compared to a large bulk of experimental data. (author)

Strange mesonic transition form factor in the chiral constituent quark model

International Nuclear Information System (INIS)

Ito, H.; Ramsey-Musolf, M.J.

1998-01-01

The form factor g ρπ (S) (Q 2 ) of the strange vector current transition matrix element left-angle ρ|bar sγ μ s|π right-angle is calculated within the chiral quark model. A strange vector current of the constituent U and D quarks is induced by kaon radiative corrections and this mechanism yields the nonvanishing values of g ρπ (S) (0). The numerical result at the photon point is consistent with the one given by the φ-meson dominance model, but the falloff in the Q 2 dependence is faster than the monopole form factor. Mesonic radiative corrections are also examined for the electromagnetic ρ-to-π and K * -to-K transition amplitudes. copyright 1998 The American Physical Society

On the H particle stability in the non relativistic quark model

International Nuclear Information System (INIS)

Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.

1987-05-01

The H particle with quark content (uuddss) is presented as a good candidate to be stable with respect to strong interactions. In the framework of a non relativistic potential model, the binding energy is calculated by a full dynamical approach using a resonating group trial wave function. The center of mass motion and the Pauli principle are correctly treated. Sophisticated baryon wave functions are employed and the equation of motion is solved with six coupled channels including radial excited baryon states. The effect of breaking SU(3) flavour symmetry is discussed in detail

The influence of initial state fluctuations on heavy quark energy loss in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Cao, Shanshan; Bass, Steffen A; Huang, Yajing; Qin, Guang-You

2015-01-01

We study the effects of initial state fluctuations on the dynamical evolution of heavy quarks inside a quark–gluon plasma (QGP) created in relativistic heavy-ion collisions. The evolution of heavy quarks in QGP matter is described utilizing a modified Langevin equation that incorporates the contributions from both collisional and radiative energy loss. The spacetime evolution of the fireball medium is simulated with a (2 + 1)-dimensional viscous hydrodynamic model. We find that when the medium traversed by the heavy quark contains a fixed amount of energy, heavy quarks tend to lose more energy for greater fluctuations of the medium density. This may result in a larger suppression of heavy flavor observables in a fluctuating QGP matter than in a smooth one. The possibility of using hard probes to infer the information of initial states of heavy-ion collisions is discussed. (paper)

A constituent quark model with colour degrees of freedom confronts the data on hadron-nucleus interactions

International Nuclear Information System (INIS)

Rozanska, M.; Jezabek, M.

1991-04-01

Three version of a model with colour excitations of constituent quarks are examined using inclusive leading proton and antiproton spectra in nuclear interactions at high energies. The comparison with experimental data excludes the models in which fragmentation into leading final hadrons depends only on the colour charge of constituents in an intermediate system. (author)

Semileptonic decays of Λ{sub c} baryons in the relativistic quark model

Energy Technology Data Exchange (ETDEWEB)

Faustov, R.N.; Galkin, V.O. [Institute of Informatics in Education, FRC CSC RAS, Moscow (Russian Federation)

2016-11-15

Motivated by recent experimental progress in studying weak decays of the Λ{sub c} baryon we investigate its semileptonic decays in the framework of the relativistic quark model based on the quasipotential approach with the QCD-motivated potential. The form factors of the Λ{sub c} → Λlν{sub l} and Λ{sub c} → nlν{sub l} decays are calculated in the whole accessible kinematical region without extrapolations and additional model assumptions. Relativistic effects are systematically taken into account including transformations of baryon wave functions from the rest to moving reference frame and contributions of the intermediate negative-energy states. Baryon wave functions found in the previous mass spectrum calculations are used for the numerical evaluation. Comprehensive predictions for decay rates, asymmetries and polarization parameters are given. They agree well with available experimental data. (orig.)

Low-lying 1/2-hidden strange pentaquark states in the constituent quark model

Institute of Scientific and Technical Information of China (English)

Hui Li; Zong-Xiu Wu; Chun-Sheng An; Hong Chen

2017-01-01

We investigate the spectrum of the low-lying 1/2-hidden strange pentaquark states,employing the constituent quark model,and looking at two ways within that model of mediating the hyperfine interaction between quarks-Goldstone boson exchange and one gluon exchange.Numerical results show that the lowest 1/2-hidden strange pentaquark state in the Goldstone boson exchange model lies at ～ 1570 MeV,so this pentaquark configuration may form a notable component in S11(1535) if the Goldstone boson exchange model is applied.This is consistent with the prediction that S11 (1535) couples very strongly to strangeness channels.

Relativistic simulations of compact object mergers for nucleonic matter and strange quark matter

International Nuclear Information System (INIS)

Bauswein, Andreas Ottmar

2010-01-01

Under the assumption that the energy of the ground state of 3-flavor quark matter is lower than the one of nucleonic matter, the compact stellar remnants of supernova explosions are composed of this quark matter. Because of the appearance of strange quarks, such objects are called strange stars. Considering their observational features, strange stars are very similar to neutron stars made of nucleonic matter, and therefore observations cannot exclude the existence of strange stars. This thesis introduces a new method for simulating mergers of compact stars and black holes within a general relativistic framework. The main goal of the present work is the investigation of the question, whether the coalescence of two strange stars in a binary system yields observational signatures that allow one to distinguish them from colliding neutron stars. In this context the gravitational-wave signals are analyzed. It is found that in general the characteristic frequencies in the gravitational-wave spectra are higher for strange stars. Moreover, the amount of matter that becomes gravitationally unbound during the merging is determined. The detection of ejecta of strange star mergers as potential component of cosmic ray flux could serve as a proof of the existence of strange quark matter. (orig.)

Relativistic simulations of compact object mergers for nucleonic matter and strange quark matter

Energy Technology Data Exchange (ETDEWEB)

Bauswein, Andreas Ottmar

2010-01-29

Under the assumption that the energy of the ground state of 3-flavor quark matter is lower than the one of nucleonic matter, the compact stellar remnants of supernova explosions are composed of this quark matter. Because of the appearance of strange quarks, such objects are called strange stars. Considering their observational features, strange stars are very similar to neutron stars made of nucleonic matter, and therefore observations cannot exclude the existence of strange stars. This thesis introduces a new method for simulating mergers of compact stars and black holes within a general relativistic framework. The main goal of the present work is the investigation of the question, whether the coalescence of two strange stars in a binary system yields observational signatures that allow one to distinguish them from colliding neutron stars. In this context the gravitational-wave signals are analyzed. It is found that in general the characteristic frequencies in the gravitational-wave spectra are higher for strange stars. Moreover, the amount of matter that becomes gravitationally unbound during the merging is determined. The detection of ejecta of strange star mergers as potential component of cosmic ray flux could serve as a proof of the existence of strange quark matter. (orig.)

Relativistic quark model and behaviour of the meson electromagnetic form factors at small and intermediate momentum transfer Q2

International Nuclear Information System (INIS)

Bagdasaryan, A.S.; Esaybegyan, S.V.; Ter-Isaakyan, N.L.

1982-01-01

In a model of hadrons composed of relativistic quarks a description of meson static characteristics and pion electromagnetic form factor in the range of small and intermediate values of momentum transfer 0 2 2 have obtained. It is shown that in such a model the data available on the pion electromagnetic form factor may be described basing on a simplest quark without gluon exchange. The contribution of a one-gluon exchange diagram in such a model cannot exceed 30%

On equal constituent quark masses in different heavy quarkonia potential models

International Nuclear Information System (INIS)

Lewin, K.; Motz, G.

1989-01-01

In a representative number of more or less QCD-motivated QQ-bar potentials the simultaneous transformations of potentials V' j (r)=V i (r)-V i (r 0 ), m' Qi +1/2V j (r 0 ) (i -model index) introduce approximately equal constituent quark masses m' Qi ≅m Q (Q=b,c) for all considered models. The known model independence of m bi -m ci is explained and the influence of the transformation on data reproduction is studied. 16 refs.; 4 figs.; 1 tab

Constituent gluons and the static quark potential

Energy Technology Data Exchange (ETDEWEB)

Greensite, Jeff [San Francisco State Univ., CA (United States); Szczepaniak, Adam P. [Indiana Univ., Bloomington, IN (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-04-01

We suggest that Hamiltonian matrix elements between physical states in QCD might be approximated, in Coulomb gauge, by "lattice-improved" tree diagrams; i.e. tree diagram contributions with dressed ghost, transverse gluon, and Coulomb propagators obtained from lattice simulations. Such matrix elements can be applied to a variational treatment of hadronic states which include constituent gluons. As an illustration and first application of this hybrid approach, we derive a variational estimate of the heavy quark potential for distances up to 2.5 fm. The Coulomb string tension in SU(3) gauge theory is about a factor of four times greater than the asymptotic string tension. In our variational approach, using for simplicity a single variational parameter, we can reduce this overshoot by nearly the factor required. The building blocks of our approach are Coulomb gauge propagators, and in this connection we present new lattice results for the ghost and transverse gluon propagators in position space.

Constituent quarks and systematic errors in mid-rapidity charged multiplicity dNch/dη distributions

Science.gov (United States)

Tannenbaum, M. J.

2018-01-01

Centrality definition in A + A collisions at colliders such as RHIC and LHC suffers from a correlated systematic uncertainty caused by the efficiency of detecting a p + p collision (50 ± 5% for PHENIX at RHIC). In A + A collisions where centrality is measured by the number of nucleon collisions, Ncoll, or the number of nucleon participants, Npart, or the number of constituent quark participants, Nqp, the error in the efficiency of the primary interaction trigger (Beam-Beam Counters) for a p + p collision leads to a correlated systematic uncertainty in Npart, Ncoll or Nqp which reduces binomially as the A + A collisions become more central. If this is not correctly accounted for in projections of A + A to p + p collisions, then mistaken conclusions can result. A recent example is presented in whether the mid-rapidity charged multiplicity per constituent quark participant (dNch/dη)/Nqp in Au + Au at RHIC was the same as the value in p + p collisions.

Octet baryons in the independent-quark-model approach based on the Dirac equation with a power-law potential

Energy Technology Data Exchange (ETDEWEB)

Barik, N; Das, M [Utkal Univ., Bhubaneswar (India). Dept. of Physics

1983-01-13

Several properties of octet baryons such as (i) the magnetic moment, (ii) (Gsub(A)/Gsub(v))sub(n) for neutron ..beta..-decay and (iii) the charge radius of the proton have been calculated in a simple independent-quark model under the assumption that the individual constituent quarks are confined, in first approximation, by a relativistic power-law potential Vsub(q)(r)=(1+..beta..) (asup(..nu..+1)rsup(..nu..)+V/sub 0/) with a, ..nu..>0. In view of the simplicity of the model, the results obtained are quite encouraging.

Octet baryons in the independent-quark-model approach based on the Dirac equation with a power-law potential

International Nuclear Information System (INIS)

Barik, N.; Das, M.

1983-01-01

Several properties of octet baryons such as (i) the magnetic moment, (ii) (Gsub(A)/Gsub(v))sub(n) for neutron #betta#-decay and (iii) the charge radius of the proton have been calculated in a simple independent-quark model under the assumption that the individual constituent quarks are confined, in first approximation, by a relativistic power-law potential Vsub(q)(r)=(1+#betta#) (asup(#betta#+1)rsup(#betta#)+V 0 ) with a, #betta#>0. In view of the simplicity of the model, the results obtained are quite encouraging. (orig.)

Population of multi-quark states in exotic multiplets and thermalization in ultra-relativistic heavy ion collisions

International Nuclear Information System (INIS)

Scherer, S.; Bleicher, M.; Haussler, S.; Stoecker, H.

2008-01-01

The recent discussion about experimental evidence for pentaquark states has revitalized the interest in exotic hadrons. If such states really exist, it is natural to assume that they will be formed at the late hadronization stage of ultra-relativistic heavy ion collisions, given the success of quark recombination models in the description of hadronization. Here, we apply the qMD model to study the formation of color neutral exotic multi-quark clusters at hadronization. We search for color neutral clusters made up of up to six color charges, respectively. We thus obtain estimates for the numbers and phase space distributions of exotic hadronic states produced by clustering in heavy ion collisions, including the members of the pentaquark multiplets. We obtain particle abundances that are smaller than thermal model predictions. Moreover, the results obtained in recombination from ultra-relativistic heavy ion collisions can be compared to the estimates based on equal population of the corresponding multiplets, and to results from fully thermalized systems. We find that the distribution of exotic hadrons from recombination over large multiplets provides a sensitive signal for thermalization and decorrelation of the initial, non-equilibrium state of the collision. (author)

Models of quark bags and their consequences

International Nuclear Information System (INIS)

Bogolubov, P.N.

1977-01-01

The development of the first Dubna Quark Bag and the results obtained in this way are considered. The idea of the first Dubna Quark Bag is as follows: baryons are constructed of three quarks measons are constructed of two quarks, and each quark is interpreted as the Dirac particle which moves in a scalar square well. The so-called quasiindependent quark model is considered too. It is a simple quark model based on an analogy with the shell model for nuclei. The quarks are considered as moving in an arbitrary radially-symmetric field, and their one-particle wave function satisfies the usual Dirac equation. Such quark model can give at least the same results as the relativistic bag model. A possibility exists to improve the results of the relativistic quark model with the oscillator interaction between quarks. The results of the MIT-Bag model and the quasiindependent quark model coincide

Making quark matter at brook haven's new collider

International Nuclear Information System (INIS)

Jones, P.

2002-01-01

Quarks are believed to come in 6 flavours, only the lightest of which, the up and down quarks, are found in protons and neutrons. Isolated quarks have never been observed. As quarks are brought closer together, the force between them decreases dramatically, vanishing as the separation becomes very small. This suggests that quarks may become unbound if the density of quarks could be increased by squeezing a nucleus. The nucleus would have melted their constituent quarks, now free to roam the extended volume of the compressed nucleus. This situation would make a significant change in the structure of matter corresponding to a change of phase, rather like the transition from solid to liquid, but in this case from quark confined matter, to a quark gluon plasma (QGP). This new state of matter is thought to have been the natural phase of matter until 10 micro-seconds after the big-bang, and also to exist today in the core of neutron stars. Calculations show that the energy density needed to observe the phase transition is around 1 GeV/fm 3 , approximately 8 times that of normal nuclear matter. Attempts to recreate QGP have been underway at the relativistic heavy ion collider (RHIC) and at the CERN by colliding heavy-ion beams at the maximal energy possible. Between 4000 and 5000 charged particles are produced in the most violent events. The experimental challenge is to establish the existence of QGP from all this wealth of data. (A.C.)

CONFERENCE: Quark matter 88

International Nuclear Information System (INIS)

Jacob, Maurice

1988-01-01

The 'Quark Matter' Conference caters for physicists studying nuclear matter under extreme conditions. The hope is that relativistic (high energy) heavy ion collisions allow formation of the long-awaited quark-gluon plasma, where the inter-quark 'colour' force is no longer confined inside nucleon-like dimensions

Possible D(*) anti D(*) and B(*) anti B(*) molecular states in the extended constituent quark models

International Nuclear Information System (INIS)

Yang, You-Chang; Tan, Zhi-Yun; Ping, Jialun; Zong, Hong-Shi

2017-01-01

The possible neutral D (*) anti D (*) and B (*) anti B (*) molecular states are studied in the framework of the constituent quark models, which is extended by including the s-channel one-gluon exchange. Using different types of quark-quark potentials, we solve the four-body Schroedinger equation by means of the Gaussian expansion method. The bound states of D (*) anti D (*) with J PC = 1 ++ , 2 ++ and B (*) anti B (*) with J PC = 0 ++ , 1 +- , 1 ++ , 2 ++ are obtained. The molecular states D* anti D with J PC = 1 ++ and B* anti B with J PC = 1 +- are good candidates for X(3872) and Z 0 b (10610), respectively. The dependence of the results on the model parameters is also discussed. (orig.)

Low-lying 1/2- hidden strange pentaquark states in the constituent quark model

Science.gov (United States)

Li, Hui; Wu, Zong-Xiu; An, Chun-Sheng; Chen, Hong

2017-12-01

We investigate the spectrum of the low-lying 1/2- hidden strange pentaquark states, employing the constituent quark model, and looking at two ways within that model of mediating the hyperfine interaction between quarks - Goldstone boson exchange and one gluon exchange. Numerical results show that the lowest 1/2- hidden strange pentaquark state in the Goldstone boson exchange model lies at ˜1570 MeV, so this pentaquark configuration may form a notable component in S 11(1535) if the Goldstone boson exchange model is applied. This is consistent with the prediction that S 11(1535) couples very strongly to strangeness channels. Supported by National Natural Science Foundation of China (11675131, 11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

Relativistic heavy ion collisions

International Nuclear Information System (INIS)

Barz, H.W.; Kaempfer, B.; Schulz, H.

1984-12-01

An elementary introduction is given into the scenario of relativistic heavy ion collisions. It deals with relativistic kinematics and estimates of energy densities, extrapolations of the present knowledge of hadron-hadron and hadron-nuleus to nucleus-nucleus collisions, the properties of the quark-gluon plasma and the formation of the plasma and possible experimental signatures. Comments are made on a cosmic ray experiment which could be interpreted as a first indication of the quark-gluon phase of the matter. (author)

Constituent quark model for nuclear stopping in high energy nuclear collisions

International Nuclear Information System (INIS)

Choi, T.K.; Maruyama, M.; Takagi, F.

1997-01-01

We study nuclear stopping in high energy nuclear collisions using the constituent quark model. It is assumed that wounded nucleons with a different number of interacted quarks hadronize in different ways. The probabilities of having such wounded nucleons are evaluated for proton-proton, proton-nucleus, and nucleus-nucleus collisions. After examining our model in proton-proton and proton-nucleus collisions and fixing the hadronization functions, it is extended to nucleus-nucleus collisions. It is used to calculate the rapidity distribution and the rapidity shift of final-state protons in nucleus-nucleus collisions. The computed results are in good agreement with the experimental data on 32 S+ 32 S at E lab =200A GeV and 208 Pb+ 208 Pb at E lab =160A GeV. Theoretical predictions are also given for proton rapidity distribution in 197 Au+ 197 Au at √(s)=200A GeV (BNL-RHIC). We predict that the nearly baryon-free region will appear in the midrapidity region and the rapidity shift is left-angle Δy right-angle=2.24

Thermal recombination: Beyond the valence quark approximation

Energy Technology Data Exchange (ETDEWEB)

Mueller, B. [Department of Physics, Duke University, Durham, NC 27708 (United States); Fries, R.J. [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)]. E-mail: fries@physics.umn.edu; Bass, S.A. [Department of Physics, Duke University, Durham, NC 27708 (United States); RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States)

2005-07-07

Quark counting rules derived from recombination models agree well with data on hadron production at intermediate transverse momenta in relativistic heavy-ion collisions. They convey a simple picture of hadrons consisting only of valence quarks. We discuss the inclusion of higher Fock states that add sea quarks and gluons to the hadron structure. We show that, when recombination occurs from a thermal medium, hadron spectra remain unaffected by the inclusion of higher Fock states. However, the quark number scaling for elliptic flow is somewhat affected. We discuss the implications for our understanding of data from the Relativistic Heavy Ion Collider.

Relativistic wave functions of two spin 1/2 quarks in a model with QCD interaction

International Nuclear Information System (INIS)

Skachkov, N.B.; Solovtsov, I.L.

1981-01-01

Within the hamiltonian formulation of quantum field theory an equation is obtained for the vertex and wave functions of a composite system of two spin 1/2 quarks. Exact solutions are found for the relativistic potential having in the momentum representation the ''asymptotically-free'' behaviour at large values of momentum transfer Q 2 . It is shown that within the given model the π-meson wave function has zero at a finite distance corresponding to the point of discontinuity of the effective potential [ru

Transversity quark distributions in a covariant quark-diquark model

Energy Technology Data Exchange (ETDEWEB)

Cloet, I.C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439-4843 (United States)], E-mail: icloet@anl.gov; Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan)], E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, VA 23606 (United States); College of William and Mary, Williamsburg, VA 23187 (United States)], E-mail: awthomas@jlab.org

2008-01-17

Transversity quark light-cone momentum distributions are calculated for the nucleon. We utilize a modified Nambu-Jona-Lasinio model in which confinement is simulated by eliminating unphysical thresholds for nucleon decay into quarks. The nucleon bound state is obtained by solving the relativistic Faddeev equation in the quark-diquark approximation, where both scalar and axial-vector diquark channels are included. Particular attention is paid to comparing our results with the recent experimental extraction of the transversity distributions by Anselmino et al. We also compare our transversity results with earlier spin-independent and helicity quark distributions calculated in the same approach.

Relativistic BCS-BEC Crossover at Quark Level

Directory of Open Access Journals (Sweden)

Zhuang P.

2010-10-01

Full Text Available The non-relativistic G0G formalism of BCS-BEC crossover at finite temperature is extended to relativistic fermion systems. The theory recovers the BCS mean field approximation at zero temperature and the non-relativistic results in a proper limit. For massive fermions, when the coupling strength increases, there exist two crossovers from the weak coupling BCS superfluid to the non-relativistic BEC state and then to the relativistic BEC state. For color superconductivity at moderate baryon density, the matter is in the BCS-BEC crossover region, and the behavior of the pseudogap is quite similar to that found in high temperature superconductors.

Effective field theory and the quark model

International Nuclear Information System (INIS)

Durand, Loyal; Ha, Phuoc; Jaczko, Gregory

2001-01-01

We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the 'nonrelativistic' constituent QM for baryon masses and moments is completely equivalent through O(m s ) to a parametrization of the relativistic field theory in a general spin-flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections

Relativistic corrections to η{sub c}-pair production in high energy proton–proton collisions

Energy Technology Data Exchange (ETDEWEB)

Martynenko, A.P., E-mail: a.p.martynenko@samsu.ru [Samara State University, Pavlov Street 1, 443011, Samara (Russian Federation); Samara State Aerospace University named after S.P. Korolyov, Moskovskoye Shosse 34, 443086, Samara (Russian Federation); Trunin, A.M., E-mail: amtrnn@gmail.com [Samara State Aerospace University named after S.P. Korolyov, Moskovskoye Shosse 34, 443086, Samara (Russian Federation)

2013-06-10

On the basis of perturbative QCD and the relativistic quark model we calculate relativistic corrections to the double η{sub c} meson production in proton–proton interactions at LHC energies. Relativistic terms in the production amplitude connected with the relative motion of heavy quarks and the transformation law of the bound state wave functions to the reference frame of moving charmonia are taken into account. For the gluon and quark propagators entering the amplitude we use a truncated expansion in relative quark momenta up to the second order. Relativistic corrections to the quark bound state wave functions are considered by means of the Breit-like potential. It turns out that the examined effects decrease total non-relativistic cross section more than two times and on 20 percents in the rapidity region of LHCb detector.

Hadronization of the quark-gluon plasma

International Nuclear Information System (INIS)

Mueller, B.; Sano, M.; Sato, H.; Schaefer, A.

1986-11-01

We construct a model for hadronization of the quark-gluon plasma, based on the relativistic coalescence model. We relate the coalescence amplitude to the one-particle Wigner function for quarks in the plasma. The relation between the Wigner function and the nucleon structure function is pointed out. We derive explicit expressions for the production of mesons and baryons in the framework of the relativistic harmonic oscillator model of hadronic structure. (author)

Chiral bag model with constituent quarks: topological and nontopological decisions

International Nuclear Information System (INIS)

Malakhov, I.Yu.; Sveshnikov, K.A.; Fedorov, S.M.; Khalili, M.F.

2002-01-01

The three-phase modification of the hybrid chiral bag containing along with asymptotic freedom and hadronization phases and also intermediate phase of the constituent quarks is considered. The self-consistent solutions of the equations of the model in the (1 + 1)-dimensional case are determined with an account of the fermion vacuum polarization effects. The bag renormalized complete energy is studied as a function of the parameters characterizing the bag geometry and its topological (baryon) charge. It is shown that for nonzero topological charge there exists the whole series of configurations representing the local minima of the bag complete energy and containing all three phases, whereas the bag energy minimum in the nontopological case corresponds to zero dimensions of the area corresponding to asymptotic freedom phase [ru

On the mass spectra of the pseudoscalar mesons in the relativistic independent quark model

International Nuclear Information System (INIS)

Khrushchev, V.V.; Semenov, S.V.

2002-01-01

In the framework of the relativistic independent quark model with the QCD-motivated static potential, the masses of the ground states of pseudoscalar mesons and their radial excitations are calculated for both observed mesons and unobserved ones. The strength of the spin-spin interaction and the magnitude of the mean field contribution are estimated for both the light and heavy 0 -+ mesons. The calculated masses are in agreement with experimental values within an accuracy of 30 - 40 MeV, and the predictions are obtained for the mass values of a number of unobserved yet radial excitations of pseudoscalar mesons

Baryonic hybrids: Gluons as beads on strings between quarks

International Nuclear Information System (INIS)

Cornwall, John M.

2005-01-01

In this paper we analyze the ground state of the heavy-quark qqqG system using standard principles of quark confinement and massive constituent gluons as established in the center-vortex picture. The known string tension K F and approximately-known gluon mass M lead to a precise specification of the long-range nonrelativistic part of the potential binding the gluon to the quarks with no undetermined phenomenological parameters, in the limit of large interquark separation R. Our major tool (also used earlier by Simonov) is the use of proper-time methods to describe gluon propagation within the quark system, along with some elementary group theory describing the gluon Wilson-line as a composite of colocated q and q lines. We show that (aside from color-Coulomb and similar terms) the gluon potential energy in the presence of quarks is accurately described (for small gluon fluctuations) via attaching these three strings to the gluon, which in equilibrium sits at the Steiner point of the Y-shaped string network joining the three quarks. The gluon undergoes small harmonic fluctuations that slightly stretch these strings and quasiconfine the gluon to the neighborhood of the Steiner point. To describe nonrelativistic ground-state gluonic fluctuations at large R we use the Schroedinger equation, ignoring mixing with l=2 states. Available lattice data and real-world hybrids require consideration of R values small enough for significant relativistic corrections, which we apply using a variational principle for the relativistic harmonic-oscillator. We also consider the role of color-Coulomb contributions. In terms of interquark separations R, we find leading nonrelativistic large-R terms in the gluon excitation energy of the form ε(R)→M+ξ[K F /(MR)] 1/2 -ζα c /R where ξ,ζ are calculable numerical coefficients and α c ≅ 0.15 is the color-Coulomb qq coupling. When the gluon is relativistic, ε∼(K F /R) 1/3 . We get an acceptable fit to lattice data with M=500 Me

'Relativistic' quark model for mesons with flavour-independent potential

International Nuclear Information System (INIS)

Kroesen, G.

1987-01-01

On the base of the Bethe-Salpeter equation in instantaneous approximation a unified model for the mass spectrum of the mesons was designed. The 'relativistic' structure of the Bethe-Salpeter equation allows a natural inclusion of the spin dependences and an extension of the model to small quark masses. The model contains as essential property two potential contributions where one represents the one-gluon exchange while the other represents the confinement potential. The annihilation of qanti q into gluons was not regarded. The spectrum and the amplitudes of the Bethe-Salpeter equation were solved approximatively in numerical way for the lowest states. The free parameters of the model were determined by a fit of the spectrum to a wellknown part of the meson spectrum. The results yield even at small quark masses a quantitatively good picture for all meson families. The result shows that the spectra of the heavy and light mesons can be described by a flavor-independent potential which contains 5 free parameters. Both the internal spin dependent structure and the absolute position of the families can so correctly be described. Especially the position of the D, D s , and B states and the position of the uanti u, danti d states can be simultaneously described by a constant C in the long-range part of the potential. The constant C is thereby essentially determined by the splitting between the Υ family and the B family repectively Ψ and D family. The 3 S 1- 3 D 1 respectively the 3 P 2 - 3 F 2 configuration mixing was regarded. The results show that this mixing is negligibly small. (orig./HSI) [de

Probing the Quark Gluon Plasma with Heavy Flavours: recent results from ALICE

CERN Multimedia

CERN. Geneva

2017-01-01

The study of open heavy-flavour physics allows us to investigate the key properties of the Quark-Gluon Plasma (QGP) and the microscopic processes ongoing in the medium produced in heavy-ion collisions at relativistic energies. Heavy quarks are produced in the early stages of heavy-ion collisions and their further production and annihilation rates in the medium are expected to be very small throughout the evolution of the system. Therefore, they serve as penetrating probes that traverse the hot and dense medium, interact with the partonic constituents of the plasma and lose energy. Understanding the interactions of heavy quarks with the medium requires precise measurements over a wide momentum range in heavy-ion collisions, but also in smaller systems like pp collisions, which also test next-to-leading order perturbative QCD calculations, and proton-nucleus collisions, which are sensitive to Cold Nuclear Matter effects (CNM), such as the modification of the parton distribution functions of nuclei, and parton ...

Symmetries and aggregates of quarks as constituents of hadrons

International Nuclear Information System (INIS)

Kibler, M.

1982-07-01

The interest of the Lie algebra of the group SU(n) for the classification of hadrons and the description of some of their static properties is emphasized for n=3, 4, 6, 8. The cases n=3 and 4 allow to introduce the quark flavors (u,d,s,) and (u,d,c,s), respectively, and the consideration of the spin of hadrons leads to the chain SU(2m) contains SU(m) x SU(2). The hadrons are described as bound states or aggregates of quarks of type quark-quark-quark for baryons and quark-antiquark for mesons. The Pauli exclusion principle applied to the three-quark baryons requires the introduction of a new quantum number, the color: each flavor of quark then comes in three colors

The constituent quark model the spectrum of mesons

International Nuclear Information System (INIS)

Shojaei, M.R.; Rajabi, A.A.; Hasanabadi, H.

2007-01-01

Full text: We calculate exact solution of the Schroedinger equation analytically for a meson consisting of a quark and antiquark, considering the interaction potential between the particles as a combination of two potentials, a potential due to color charge and an oscillatory potential as confining potential. in this paper, first consider potential between quarks as a function of radios x, thus we assume this potential as a central potential. This potential is derived from that the central potential. This potential is derived from that the quark see itself under influence of another quark, in this case central potential is considered as: V(x)=ax 2 -c/x. Potential is obtained from interaction between a quark and an antiquary. The source of it is color charge and ax 2 potential plays confining potential. Because this potential shows oscillations of one quark to another quark in the distance x from it.. In addition to the above potentials we consider the spin-spin, spin - isospin and isospin - isospin interactions as perturbing potentials, and calculate the mass of the mesons for each potential separately finally using the equivalence of mass-energy we calculate the mass of the mesons

Heavy quark production form jet conversions in a quark-gluon plasma

Energy Technology Data Exchange (ETDEWEB)

Liu , W.; Fries, R.

2008-05-22

Recently, it has been demonstrated that the chemical composition of jets in heavy ion collisions is significantly altered compared to the jets in the vacuum. This signal can be used to probe the medium formed in nuclear collisions. In this study we investigate the possibility that fast light quarks and gluons can convert to heavy quarks when passing through a quark-gluon plasma. We study the rate of light to heavy jet conversions in a consistent Fokker-Planck framework and investigate their impact on the production of high-p{sub T} charm and bottom quarks at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

Quasinuclear colored quark model for hadrons

International Nuclear Information System (INIS)

Lipkin, H.J.

1978-09-01

Lectures are presented in which a quasinuclear constituent quark model in which constituent quarks are assumed to be made of constituent interacting with a two-body color-exchange logarithmic potential is considered. The color degree of freedom is discussed in detail. Some properties of the logarithmic potential and the definition of the quasinuclear model and its validity, and a comparison of some of its predictions with experiment are described. 31 references

Quark approach to Santilli's conjecture on hadronic structure - II

International Nuclear Information System (INIS)

Animalu, A.O.E.

1982-08-01

In this paper, we continue an earlier investigation of an exactly soluble relativistic Bohr-type model of the internal structure of the proton (three-quark baryon system) and the pion (quark-antiquark meson system), based on a realization of Santilli's conjecture that the hadronic constituents are extended (non-pointlike) objects. The model is abstracted from an expansion of a Yukawa-type potential between the valence quarks and a massive core, in which the meson or gluon exchange term has the effect of reducing the effective Bohr radius for binding to a value less than the radius of the strong charge sphere (or Compton wavelength) of each constituent, so that appreciable overlap of charge volumes occurs, to within a typical distance of order 0.25F or 1/(800 MeV) in qqq-system, and order 1/(1200 MeV) in qq-bar-system, which are comparable to gluon masses, msub(G) approx.= 800 to 1200 MeV, required by the lattice QCD and the MIT Bag Model. Based on the assumptions that the ground state of the proton has 1s 2 2s valence quark configuration, the non-strange quark mass is msub(p)/3, and the dimensionless strong coupling constant of the Yukawa-type potential is g 2 =1, the mass of the proton core is determined self-consistently to be 2470 MeV, exactly balancing the quark binding energy so that the valence quarks appear free. The model correctly predicts the masses of the well-known resonant states of the proton with Jsup(P)=1/2 + as excited states associated with the configuration 1s2s 2 and predicts an upper bound (spectroscopic limit) for the mass of the excited states of the proton in ns 2 ms configuration, as n→infinity and m→infinity, to be 3409 MeV. Based on a generalization of the model to qq-bar-systems, an upper bound (spectroscopic limit) for the mass of qq-bar in ns 2 configuration, as n→infinity, is found to be 3096 MeV, which is the mass of the J/psi-meson. The relation of the model to violation of time-reversal invariance (T-symmetry) by non

Heavy-to-light form factors for non-relativistic bound states

International Nuclear Information System (INIS)

Bell, G.; Feldmann, Th.

2007-01-01

We investigate transition form factors between non-relativistic QCD bound states at large recoil energy. Assuming the decaying quark to be much heavier than its decay product, the relativistic dynamics can be treated according to the factorization formula for heavy-to-light form factors obtained from the heavy-quark expansion in QCD. The non-relativistic expansion determines the bound-state wave functions to be Coulomb-like. As a consequence, one can explicitly calculate the so-called 'soft-overlap' contribution to the transition form factor

Compound quarks and gluons and parton confinement (proposal of a different approach)

International Nuclear Information System (INIS)

Krolikowski, W.

1978-01-01

The author develops further the compound model proposed in 1971, where coloured quarks are factorized into elementary constituents carrying separately the flavour and colour quantum numbers and obeying the 'compensating' wrong statistics. An 'effective quantum chromodynamics' is conjectured, where both coloured quarks and vector gluons (which obey good statistics) are factorized into elementary constituents obeying wrong statistics. Then the Pauli connection of spin and statistics confines these elementary constituents within bound states obeying good statistics. In the parton model approximation with these elementary constituents as partons it prevents also coloured quarks and vector gluons from appearing as free particles. The expected confinement violation for coloured quarks and vector gluons and the observed scaling violation have here a common origin, namely the clustering of elementary constituents inside hadrons. The basic difference between leptons and quarks is related in this model to wrong statistics of elementary constituents involved in the quark structure. (Auth.)

The quark revolution and the ZGS - new quarks physics since the ZGS

International Nuclear Information System (INIS)

Lipkin, H.J.

1994-01-01

Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966 but was dismissed as heresy. ZGS experiments played an important role in the quark revolution. This role is briefly reviewed and subsequent progress in quark physics is described

The quark bag model

International Nuclear Information System (INIS)

Hasenfratz, P.; Kuti, J.

1978-01-01

The quark bag model is reviewed here with particular emphasis on spectroscopic applications and the discussion of exotic objects as baryonium, gluonium, and the quark phase of matter. The physical vacuum is pictured in the model as a two-phase medium. In normal phase of the vacuum, outside hadrons, the propagation of quark and gluon fields is forbidden. When small bubbles in a second phase are created in the medium of the normal phase with a characteristic size of one fermi, the hadron constituent fields may propagate inside the bubbles in normal manner. The bubble (bag) is stabilized against the pressure of the confined hadron constituent fields by vacuum pressure and surface tension. Inside the bag the colored quarks and gluons are governed by the equations of quantum chromodynamics. (Auth.)

Four-quark bound states

International Nuclear Information System (INIS)

Zouzou, S.

1986-01-01

In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include the virtual meson-meson components of the wave function. With standard two-body potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic (anti Qanti Qqq) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q'qq) baryons. (orig.)

Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase distribution

International Nuclear Information System (INIS)

Gossiaux, Pol Bernard; Guiho, Vincent; Aichelin, Joerg

2005-01-01

We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of J/ψ production (integrated and differential) stemming from c-c-bar pairs that are initially uncorrelated

Quark-gluon plasma (Selected Topics)

International Nuclear Information System (INIS)

Zakharov, V. I.

2012-01-01

Introductory lectures to the theory of (strongly interacting) quark-gluon plasma given at the Winter School of Physics of ITEP (Moscow, February 2010). We emphasize theoretical issues highlighted by the discovery of the low viscosity of the plasma. The topics include relativistic hydrodynamics, manifestations of chiral anomaly in hydrodynamics, superfluidity, relativistic superfluid hydrodynamics, effective stringy scalars, holographic models of Yang-Mills theories.

Static quark-antiquark potential

International Nuclear Information System (INIS)

Deo, B.B.; Barik, B.K.

1983-01-01

A heavy-quark--antiquark potential is suggested which connects asymptotic freedom and quark confinement in a unified manner by formal methods of field theory using some plausible assumptions. The potential has only one additional adjustable parameter B which is proportional to (M/sub q//m/sub q/), where M/sub q/ and m/sub q/ are the constituent and current quark masses, respectively

Effective field theories of baryons and mesons, or, what do quarks do?

International Nuclear Information System (INIS)

Keaton, G.L.

1995-01-01

This thesis is an attempt to understand the properties of the protons, pions and other hadrons in terms of their fundamental building blocks. In the first chapter the author reviews several of the approaches that have already been developed. The Nambu-Jona-Lasinio model offers the classic example of a derivation of meson properties from a quark Lagrangian. The chiral quark model encodes much of the intuition acquired in recent decades. The author also discusses the non-linear sigma model, the Skyrme model, and the constituent quark model, which is one of the oldest and most successful models. In the constituent quark model, the constituent quark appears to be different from the current quark that appears in the fundamental QCD Lagrangian. Recently it was proposed that the constituent quark is a topological soliton. In chapter 2 the author investigates this soliton, calculating its mass, radius, magnetic moment, color magnetic moment, and spin structure function. Within the approximations used, the magnetic moments and spin structure function cannot simultaneously be made to agree with the constituent quark model. In chapter 3 the author uses a different plan of attack. Rather than trying to model the constituents of the baryon, he begins with an effective field theory of baryons and mesons, with couplings and masses that are simply determined phenomenologically. Meson loop corrections to baryon axial currents are then computed in the 1/N expansion. It is already known that the one-loop corrections are suppressed by a factor 1/N; here it is shown that the two-loop corrections are suppressed by 1/N 2 . To leading order, these corrections are exactly the same as would be calculated in the constituent quark model. This method therefore offers a different approach to the constituent quark

Topological and nontopological solutions for the chiral bag model with constituent quarks

International Nuclear Information System (INIS)

Sveshnikov, K.; Malakhov, I.; Khalili, M.; Fedorov, S.

2002-01-01

The three-phase version of the hybrid chiral bag model, containing the phase of asymptotic freedom, the hadronization phase as well as the intermediate phase of constituent quarks is proposed. For this model the self-consistent solutions of different topology are found in (1 + 1)D with due regard for fermion vacuum polarization effects. The renormalized total energy of the bag is studied as a function of its geometry and topological charge. It is shown that in the case of nonzero topological charge there exists a set of configurations being the local minima of the total energy of the bag and containing all the three phases, while in the nontopological case the minimum of the total energy of the bag corresponds to vanishing size of the phase of asymptotic freedom

Relativistic description of pair production of doubly heavy baryons in e+e− annihilation

International Nuclear Information System (INIS)

Martynenko, A. P.; Trunin, A. M.

2015-01-01

Relativistic corrections in the pair production of S-wave doubly heavy diquarks in electron-positron annihilation were calculated on the basis of perturbative QCD and the quark model. The relativistic corrections to the wave functions for quark bound states were taken into account with the aid of the Breit potential in QCD. Relativistic effects change substantially the nonrelativistic cross sections for pair diquark production. The yield of pairs of (ccq) doubly heavy baryons at B factories was estimated

Relativistic heavy ion reactions

Energy Technology Data Exchange (ETDEWEB)

Brink, D M

1989-08-01

The theory of quantum chromodynamics predicts that if nuclear matter is heated to a sufficiently high temperature then quarks might become deconfined and a quark-gluon plasma could be produced. One of the aims of relativistic heavy ion experiments is to search for this new state of matter. These lectures survey some of the new experimental results and give an introduction to the theories used to interpret them. 48 refs., 4 tabs., 11 figs.

Relativistic heavy ion reactions

International Nuclear Information System (INIS)

Brink, D.M.

1989-08-01

The theory of quantum chromodynamics predicts that if nuclear matter is heated to a sufficiently high temperature then quarks might become deconfined and a quark-gluon plasma could be produced. One of the aims of relativistic heavy ion experiments is to search for this new state of matter. These lectures survey some of the new experimental results and give an introduction to the theories used to interpret them. 48 refs., 4 tabs., 11 figs

Baryons in the unquenched quark model

Energy Technology Data Exchange (ETDEWEB)

Bijker, R.; Díaz-Gómez, S. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, AP 70-543, 04510 Mexico DF (Mexico); Lopez-Ruiz, M. A. [Physics Department and Center for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408 (United States); Santopinto, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Genova, via Dodecaneso 33, I-16146 Italy (Italy)

2016-07-07

In this contribution, we present the unquenched quark model as an extension of the constituent quark model that includes the effects of sea quarks via a {sup 3}P{sub 0} quark-antiquark pair-creation mechanism. Particular attention is paid to the spin and flavor content of the proton, magnetic moments and β decays of octet baryons.

Point form relativistic quantum mechanics and relativistic SU(6)

Science.gov (United States)

Klink, W. H.

1993-01-01

The point form is used as a framework for formulating a relativistic quantum mechanics, with the mass operator carrying the interactions of underlying constituents. A symplectic Lie algebra of mass operators is introduced from which a relativistic harmonic oscillator mass operator is formed. Mass splittings within the degenerate harmonic oscillator levels arise from relativistically invariant spin-spin, spin-orbit, and tensor mass operators. Internal flavor (and color) symmetries are introduced which make it possible to formulate a relativistic SU(6) model of baryons (and mesons). Careful attention is paid to the permutation symmetry properties of the hadronic wave functions, which are written as polynomials in Bargmann spaces.

Ultra-relativistic heavy-ion collisions - a hot cocktail of hydrodynamics, resonances and jets

Directory of Open Access Journals (Sweden)

Zabrodin E.

2015-01-01

Full Text Available Ultra-relativistic heavy-ion collisions at energies of RHIC and LHC are considered. For comparison with data the HYDJET++ model, which contains the treatment of both soft and hard processes, is employed. The study focuses mainly on the interplay of ideal hydrodynamics, final state interactions and jets, and its influence on the development of harmonics of the anisotropic flow. It is shown that jets are responsible for violation of the number-of-constituent-quark (NCQ scaling at LHC energies. The interplay between elliptic and triangular flows and their contribution to higher flow harmonics and dihadron angular correlations, including ridge, is also discussed.

Compositeness of quarks and leptons

International Nuclear Information System (INIS)

Peskin, M.E.

1981-01-01

I review along grand lines the theoretical ideas associated with the notion that quarks and leptons are composite. I first discuss various constituent pictures which have been proposed to account for the quantum numbers of the observed quarks and leptons, a study I call the Quantum Numerology. I then discuss some new theoretical developments of the past two years which bear on the subject of composite fermions and which make plausible (or rule out) some of the major dynamical assumptions of these constituent models. Finally, I discuss the consequences of the compositeness of quarks and leptons by setting up a series of scenarios for this compositeness and exploring, for each scenario, its experimental implications. (orig./HSI)

Possible D{sup (*)} anti D{sup (*)} and B{sup (*)} anti B{sup (*)} molecular states in the extended constituent quark models

Energy Technology Data Exchange (ETDEWEB)

Yang, You-Chang [Nanjing University, Department of Physics, Nanjing (China); Zunyi Normal University, School of Physics and Electronic Science, Zunyi (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China); Tan, Zhi-Yun [Zunyi Normal University, School of Physics and Electronic Science, Zunyi (China); Ping, Jialun [Nanjing Normal University, Department of Physics, Nanjing (China); Zong, Hong-Shi [Nanjing University, Department of Physics, Nanjing (China); Institute of Theoretical Physics, CAS, State Key Laboratory of Theoretical Physics, Beijing (China)

2017-09-15

The possible neutral D{sup (*)} anti D{sup (*)} and B{sup (*)} anti B{sup (*)} molecular states are studied in the framework of the constituent quark models, which is extended by including the s-channel one-gluon exchange. Using different types of quark-quark potentials, we solve the four-body Schroedinger equation by means of the Gaussian expansion method. The bound states of D{sup (*)} anti D{sup (*)} with J{sup PC} = 1{sup ++}, 2{sup ++} and B{sup (*)} anti B{sup (*)} with J{sup PC} = 0{sup ++}, 1{sup +-}, 1{sup ++}, 2{sup ++} are obtained. The molecular states D* anti D with J{sup PC} = 1{sup ++} and B* anti B with J{sup PC} = 1{sup +-} are good candidates for X(3872) and Z{sup 0}{sub b}(10610), respectively. The dependence of the results on the model parameters is also discussed. (orig.)

Electrical conductivity and shear viscosity of quark gluon plasma in a quasiparticle model

International Nuclear Information System (INIS)

Srivastava, P.K.; Mohanty, B.

2014-01-01

Relativistic heavy-ion collisions (HIC) have reported the formation of a strongly coupled quark gluon plasma (sQGP). To study the properties of this sQGP is the main focus nowadays. Among these the shear viscosity (η) and electrical conductivity (σ el ) could reflect the transport properties of the medium. By studying the shear viscosity or more specifically shear viscosity to entropy density ratio (η/s), one can understand the nature of interactions among the constituents of the produced medium, it gives a measure of the fluidity. Electrical conductivity represents the linear response of the system to an applied external electric field. The basic question one could ask is that whether the matter created at heavy ion collision experiment is an electrical conductor or an insulator. Recent lattice QCD as well as phenomenological studies have shown that these transport quantities show some kind of minimum in its variation with respect to temperature near the temperature corresponding to the transition from hadronic phase to quark-gluon phase

Meson spectra using relativistic quark models

International Nuclear Information System (INIS)

Eggers, M.C.

1985-01-01

The complexity of QCD has led to the use of simpler, phenomenological models for hadrons, notably potential models. A short overview of the origin, rationale, merits and demerits of such models is given. Nonrelativistic models and scaling laws are discussed using the WKB technique for illustrative purposes. The failure of nonrelativistic models to describe the lighter mesons motivates the introduction of relativistic equations. Relativistic kinematics are incorporated into a Schroedinger formalism using equations derived by A. Barut, while two-body kinematics are brought into a one-body form via a substitution related to the Todorov equation. The potential used involves a semi-analytic solution to a harmonic oscillator modified by a spin-spin interaction term. The results seem to indicate that such a harmonic oscillator is unsuitable to describe diquark systems adequately

Quark Matter 2017: Young Scientist Support

Energy Technology Data Exchange (ETDEWEB)

Evdokimov, Olga [University of Illinois at Chicago

2017-07-31

Quark Matter conference series are amongst the major scientific events for the Relativistic Heavy Ion community. With over 30 year long history, the meetings are held about every 1½ years to showcase the progress made in theoretical and experimental studies of nuclear matter under extreme conditions. The 26th International Conference on Ultra-relativistic Nucleus-Nucleus Collisions (Quark Matter 2017) was held at the Hyatt Regency Hotel in downtown Chicago from Sunday, February 5th through Saturday, February 11th, 2017. The conference featured about 180 plenary and parallel presentations of the most significant recent results in the field, a poster session for additional presentations, and an evening public lecture. Following the tradition of previous Quark Matter meetings, the first day of the conference was dedicated entirely to a special program for young scientists (graduate students and postdoctoral researchers). This grant will provided financial support for 235 young physicists facilitating their attendance of the conference.

Quark and pion effective couplings from polarization effects

Energy Technology Data Exchange (ETDEWEB)

Braghin, Fabio L. [Federal University of Goias, Instituto de Fisica, Goiania, GO (Brazil)

2016-05-15

A flavor SU(2) effective model for pions and quarks is derived by considering polarization effects departing from the usual quark-quark effective interaction induced by dressed gluon exchange, i.e. a global color model for QCD. For that, the quark field is decomposed into a component that yields light mesons and the quark-antiquark condensate, being integrated out by means of the auxiliary field method, and another component which yields constituent quarks, which is basically a background quark field. Within a long-wavelength and weak quark field expansion (or large quark effective mass expansion) of a quark determinant, the leading terms are found up to the second order in a zero-order derivative expansion, by neglecting vector mesons that are considerably heavier than the pion. Pions are considered in the structureless limit and, besides the chiral invariant terms that reproduce previously derived expressions, symmetry breaking terms are also presented. The leading chiral quark-quark effective couplings are also found corresponding to a NJL and a vector-NJL couplings. All the resulting effective coupling constants and parameters are expressed in terms of the current and constituent quark masses and of the coupling g. (orig.)

Lab cooks up quark soup

CERN Multimedia

Dumé, Belle

2003-01-01

"Physicists working at the Relativistic Heavy Ion Collider (RHIC) at the Brookhaven National Laboratory in the US say that they have come closer than ever before to creating a quark-gluon plasma" (0.5 page)

Towards the dynamical study of heavy-flavor quarks in the Quark-Gluon-Plasma

International Nuclear Information System (INIS)

Berrehrah, H; Bratkovskaya, E; Cassing, W; Gossiaux, P B; Aichelin, J

2014-01-01

Within the aim of a dynamical study of on- and off-shell heavy quarks Q in the quark gluon plasma (QGP) – as produced in relativistic nucleus-nucleus collisions – we study the heavy quark collisional scattering on partons of the QGP. The elastic cross sections σ q,g−Q are evaluated for perturbative partons (massless on-shell particles) and for dynamical quasi-particles (massive off-shell particles as described by the dynamical quasi-particles model D QPM ) using the leading order Born diagrams. We demonstrate that the finite width of the quasi-particles in the DQPM has little influence on the cross sections σ q,g−Q except close to thresholds. We, furthermore, calculate the heavy quark relaxation time as a function of temperature T within the different approaches using these cross sections

Modeling and Analysis of Ultra-Relativistic Heavy-Ion Collisions. Final Report

International Nuclear Information System (INIS)

Bass, Steffen A.

2008-01-01

Hadronic, i.e. strongly interacting, matter is described by the theory of quantum chromodynamics (QCD). The basic constituents of QCD, quarks and gluons, are normally confined to hadrons, but it is believed that under extreme conditions, such as shortly after the creation of the universe, quarks and gluons can exist as independent particles in a new state of matter, called a quark-gluon plasma (QGP). Due to the rapid expansion of the universe, this plasma went through a phase transition to form hadrons - most importantly nucleons - which constitute the building blocks of matter as we know it today. The investigation of the QGP under laboratory conditions will yield important novel insights into the development of the early universe and the behavior of matter under extreme conditions. This study is presently the subject of the physics program of the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. First data from the √s NN = 130 GeV and √s NN = 200 GeV Au+Au runs at RHIC have yielded many interesting and sometimes surprising results. While many theoretical predictions have been confirmed, some of the experimental results have brought surprises and indicate that RHIC is, indeed, probing a new physics regime of QCD matter.

The quark matter

International Nuclear Information System (INIS)

Rho, Mannque.

1980-04-01

The present status of our understanding of the physics of hadronic (nuclear or neutron) matter under extreme conditions, in particular at high densities is discussed. This is a problem which challenges three disciplines of physics: nuclear physics, astrophysics and particle physics. It is generally believed that we now have a correct and perhaps ultimate theory of the strong interactions, namely quantum chromodynamics (QCD). The constituents of this theory are quarks and gluons, so highly dense matters should be describable in terms of these constituents alone. This is a question that addresses directly to the phenomenon of quark confinement, one of the least understood aspects in particle physics. For nuclear physics, the possibility of a phase change between nuclear matter and quark matter introduces entirely new degrees of freedom in the description of nuclei and will bring perhaps a deeper understanding of nuclear dynamics. In astrophysics, the properties of neutron stars will be properly understood only when the equation of state of 'neutron' matter at densities exceeding that of nuclear matter can be realiably calculated. Most fascinating is the possibility of quark stars existing in nature, not entirely an absurd idea. Finally the quark matter - nuclear matter phase transition must have occured in the early stage of universe when matter expanded from high temperature and density; this could be an essential ingredient in the big-bang cosmology

Nuclear matter descriptions including quark structure of the hadrons

International Nuclear Information System (INIS)

Huguet, R.

2008-07-01

It is nowadays well established that nucleons are composite objects made of quarks and gluons, whose interactions are described by Quantum chromodynamics (QCD). However, because of the non-perturbative character of QCD at the energies of nuclear physics, a description of atomic nuclei starting from quarks and gluons is still not available. A possible alternative is to construct effective field theories based on hadronic degrees of freedom, in which the interaction is constrained by QCD. In this framework, we have constructed descriptions of infinite nuclear matter in relativistic mean field theories taking into account the quark structure of hadrons. In a first approach, the in medium modifications of mesons properties is dynamically obtained in a Nambu-Jona-Lasinio (NJL) quark model. This modification is taken into account in a relativistic mean field theory based on a meson exchange interaction between nucleons. The in-medium modification of mesons masses and the properties of infinite nuclear matter have been studied. In a second approach, the long and short range contributions to the in-medium modification of the nucleon are determined. The short range part is obtained in a NJL quark model of the nucleon. The long range part, related to pions exchanges between nucleons, has been determined in the framework of Chiral Perturbation theory. These modifications have been used to constrain the couplings of a point coupling relativistic mean field model. A realistic description of the saturation properties of nuclear matter is obtained. (author)

Summary of the Relativistic Heavy Ion Sessions

International Nuclear Information System (INIS)

Harris, J.W.

1988-07-01

This paper briefly discusses the topics covered in the relativistic heavy ion in sessions. The prime motivation for these investigations is the possibility of forming quark matter, therefore the formation of a quark-gluon plasma. Topics on suppression of J//psi/ production, th equation of state of nuclear matter, transverse energy distributions and two pion interferometry techniques are discussed. 38 refs

Perturbative determination of mass-dependent renormalization and improvement coefficients for the heavy-light vector and axial-vector currents with relativistic heavy and domain-wall light quarks

International Nuclear Information System (INIS)

Yamada, Norikazu; Aoki, Sinya; Kuramashi, Yoshinobu

2005-01-01

We determine the mass-dependent renormalization as well as improvement coefficients for the heavy-light vector and axial-vector currents consisting of the relativistic heavy and the domain-wall light quarks through the standard matching procedure. The calculation is carried out perturbatively at the one-loop level to remove the systematic error of O(α s (am Q ) n ap) as well as O(α s (am Q ) n ) (n>=0), where p is a typical momentum scale in the heavy-light system. We point out that renormalization and improvement coefficients of the heavy-light vector current agree with those of the axial-vector current, thanks to the exact chiral symmetry for the light quark. The results obtained with three different gauge actions, plaquette, Iwasaki and DBW2, are presented as a function of heavy quark mass and domain-wall height

Nuclear matter from effective quark-quark interaction.

Science.gov (United States)

Baldo, M; Fukukawa, K

2014-12-12

We study neutron matter and symmetric nuclear matter with the quark-meson model for the two-nucleon interaction. The Bethe-Bruckner-Goldstone many-body theory is used to describe the correlations up to the three hole-line approximation with no extra parameters. At variance with other nonrelativistic realistic interactions, the three hole-line contribution turns out to be non-negligible and to have a substantial saturation effect. The saturation point of nuclear matter, the compressibility, the symmetry energy, and its slope are within the phenomenological constraints. Since the interaction also reproduces fairly well the properties of the three-nucleon system, these results indicate that the explicit introduction of the quark degrees of freedom within the considered constituent quark model is expected to reduce the role of three-body forces.

A potential model for quark confinement

International Nuclear Information System (INIS)

Thaler, J.; Iqbal, M.J.

1985-02-01

A static quark potential model obtained from a relativistic wave-equation is considered. The long-part of the quadratic terms is suppressed by a glueball exchange mechanism and compatibility with the meson spectra is shown

Quark matter and quark stars at finite temperature in Nambu-Jona-Lasinio model

Energy Technology Data Exchange (ETDEWEB)

Chu, Peng-Cheng; Wang, Bin; Dong, Yu-Min; Jia, Yu-Yue; Wang, Shu-Mei; Ma, Hong-Yang [Qingdao Technological University, School of Science, Qingdao (China); Li, Xiao-Hua [University of South China, School of Nuclear Science and Technology, Hengyang (China); University of South China, Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment, Hengyang (China)

2017-08-15

We extend the SU(3) Nambu-Jona-Lasinio (NJL) model to include two types of vector interaction. Using these two types of vector interaction in NJL model, we study the quark symmetry free energy in asymmetric quark matter, the constituent quark mass, the quark fraction, the equation of state (EOS) for β-equilibrium quark matter, the maximum mass of QSs at finite temperature, the maximum mass of proto-quark stars (PQSs) along the star evolution, and the effects of the vector interaction on the QCD phase diagram. We find that comparing zero temperature case, the values of quark matter symmetry free energy get larger with temperature increasing, which will reduce the difference between the fraction of u, d and s quarks and stiffen the EoS for β-equilibrium quark matter. In particular, our results indicate that the maximum masses of the quark stars increase with temperature because of the effects of the quark matter symmetry free energy, and we find that the heating(cooling) process for PQSs will increase (decrease) the maximum mass within NJL model. (orig.)

ON-SHELL IMPROVEMENT OF THE MASSIVE WILSON QUARK ACTION.

Energy Technology Data Exchange (ETDEWEB)

AOKI, S.; KAYABA, Y.; KURAMASHI, Y.; YAMADA, N.

2005-04-01

We review a relativistic approach to the heavy quark physics in lattice QCD by applying a relativistic O(a) improvement to the massive Wilson quark action on the lattice. After explaining how power corrections of m{sub Q}a can be avoided and remaining uncertainties are reduced to be of order (a{Lambda}{sub QCD}){sup 2}, we demonstrate a determination of four improvement coefficients in the action up to one-loop level in a mass dependent way. We also show a perturbative determination of mass dependent renormalization factors and O(a) improvement coefficients for the vector and axial vector currents. Some preliminary results of numerical simulations are also presented.

Waves in magnetized quark matter

Science.gov (United States)

Fogaça, D. A.; Sanches, S. M.; Navarra, F. S.

2018-05-01

We study wave propagation in a non-relativistic cold quark-gluon plasma immersed in a constant magnetic field. Starting from the Euler equation we derive linear wave equations and investigate their stability and causality. We use a generic form for the equation of state, the EOS derived from the MIT bag model and also a variant of the this model which includes gluon degrees of freedom. The results of this analysis may be relevant for perturbations propagating through the quark matter phase in the core of compact stars and also for perturbations propagating in the low temperature quark-gluon plasma formed in low energy heavy ion collisions, to be carried out at FAIR and NICA.

Composite models of hadrons and relativistic bound states

International Nuclear Information System (INIS)

Filippov, A.T.

1977-01-01

The following problems are considered: what the constituents of the hadrons are; what their quantum numbers and their broken and unbroken symmetries are; what the dynamics of the constituents (equations, binding forces and the origin of symmetry violations) is. The most puzzling question is: why the constituents ''escape from freedom'' and are confined inside the hadrons; what experimentalists can report about the hadron constituents and their dynamics if not finding them. There are no final answers to all these questions. The achievements of quark model are described, some problems concerning the comparison of the quark model with experiment are considered. The attempt is also made to present alternative views on the same problems

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.)

Heavy baryon spectroscopy with relativistic kinematics

International Nuclear Information System (INIS)

Valcarce, A.; Garcilazo, H.; Vijande, J.

2014-01-01

We present a comparative Faddeev study of heavy baryon spectroscopy with nonrelativistic and relativistic kinematics. We show results for different standard hyperfine interactions with both kinematics in an attempt to learn about the light quark dynamics. We highlight the properties of particular states accessible in nowadays laboratories that would help in discriminating between different dynamical models. The advance in the knowledge of light quark dynamics is a key tool for the understanding of the existence of exotic hadrons.

Quark effects in nuclear physics

International Nuclear Information System (INIS)

Scholten, O.

1990-01-01

The magnitude of the quark effect for low-energy nuclear physics is investigated. Coulomb energy is studied in the A=3 system in order to determine the effect of the composite structure of the nucleon. In the actual calculations a non-relativistic quark-cluster model description has been used. A nucleon size b=0.617 fm, the width of the relative wave function Φ of the quarks in the nucleon, has been assumed. It is concluded that the contribution to Coulomb energies due to quark effects are significant compared to the observed Nolen-Schiffer anomaly. However these do not provide the long searched for 'smoking gun'. When the free parameters that appear in the calculation are adjusted to reproduce the same charge form factor, the calculated anomalies are not significantly different. 2 figs., 2 tabs., 8 refs.2

Proceedings of the Budapest workshop on relativistic heavy ion collisions

International Nuclear Information System (INIS)

Csoergoe, T.; Hegyi, S.; Levai, P.

1993-04-01

This volume is the Proceedings of the Budapest workshop on relativistic heavy ion collisions held in Budapest, 10-13 Aug, 1992. The topics include experimental heavy ion physics, Bose-Einstein correlations, intermittency, relativistic transport theory, Quark-Gluon Plasma rehadronization, astronuclear physics and cosmology. All contributions were indexed and abstracted. (author)

A scalar-vector model of quark-antiquark interaction under linear confinement

International Nuclear Information System (INIS)

Chakrabarty, S.

1992-08-01

Considering the idea that the constituent quark mass is the dressed sum of current quark mass and dynamical quark mass, and using the standard values of current quark masses we obtain approximate values of constituent quark masses, which are then used in our extensively studied Bethe-Salpeter-reduced potential model. We find that the mass formulas become much simpler for linear potential ar with zero anomalous magnetic moment (λ), the values of scalar-vector fraction (η) and 'a' in the linear potential being (1/4) and (1/5) respectively. Also, some of the quantities can be related to each other and the match with experimental data is good. (author). 18 refs, 3 tabs

Quark-Nova Explosion inside a Collapsar: Application to Gamma Ray Bursts

Directory of Open Access Journals (Sweden)

Rachid Ouyed

2009-01-01

Full Text Available If a quark-nova occurs inside a collapsar, the interaction between the quark-nova ejecta (relativistic iron-rich chunks and the collapsar envelope leads to features indicative of those observed in Gamma Ray Bursts. The quark-nova ejecta collides with the stellar envelope creating an outward moving cap (Γ∼ 1–10 above the polar funnel. Prompt gamma-ray burst emission from internal shocks in relativistic jets (following accretion onto the quark star becomes visible after the cap becomes optically thin. Model features include (i precursor activity (optical, X-ray, γ-ray, (ii prompt γ-ray emission, and (iii afterglow emission. We discuss SN-less long duration GRBs, short hard GRBs (including association and nonassociation with star forming regions, dark GRBs, the energetic X-ray flares detected in Swift GRBs, and the near-simultaneous optical and γ-ray prompt emission observed in GRBs in the context of our model.

Top-quark mass from the diphoton mass spectrum

Energy Technology Data Exchange (ETDEWEB)

Kawabata, Sayaka [Seoul National University of Science and Technology, Institute of Convergence Fundamental Studies, Seoul (Korea, Republic of); Yokoya, Hiroshi [Quantum Universe Center, KIAS, Seoul (Korea, Republic of)

2017-05-15

We calculate the gg → γγ amplitude by including the t anti t bound-state effects near their mass threshold. In terms of the non-relativistic expansion of the amplitude, the LO contribution is an energy-independent term in the one-loop amplitude. We include the NLO contribution described by the non-relativistic Green function and part of the NNLO contribution. Despite a missing NLO piece which can be accomplished with the two-loop-level amplitude via massive quarks, the shape of the diphoton mass spectrum is predicted with a good accuracy. Thanks to the simple and clean nature of the observable, its experimental measurement can be a direct method to determine the short-distance mass of the top quark at hadron colliders. (orig.)

A Tail of a Quark in N=4 SYM

OpenAIRE

Chernicoff, Mariano; Garcia, J. Antonio; Guijosa, Alberto

2009-01-01

We study the dynamics of a `composite' or `dressed' quark in strongly-coupled large-N_c N=4 super-Yang-Mills, making use of the AdS/CFT correspondence. We show that the standard string dynamics nicely captures the physics of the quark and its surrounding non-Abelian field configuration, making it possible to derive a relativistic equation of motion that incorporates the effects of radiation damping. From this equation one can deduce a non-standard dispersion relation for the composite quark, ...

The Tevalac: A national facility for relativistic heavy-ion research to 10 GeV per nucleon with uranium

International Nuclear Information System (INIS)

1982-12-01

This preliminary proposal addresses forefront physics research through the end of this century. It presents the implications of recent theoretical insights gained from relativistic heavy-ion studies that have led physicists to believe that the densities and temperatures needed to deconfine quarks from hadrons can be reached with only a ten-fold increase in beam energy beyond that available in today's highest-energy heavy-ion accelerators. In addition, the proposal describes a variety of other new and enhanced experimental opportunities that will be opened up by such an increase in projectile energy. Also presented are an accelerator concept, called the Tevalac, that provides the requisite 10-GeV/nucleon uranium beams and a program for research and development necessary to ensure that the facility to be proposed at a later date is ready for construction and will fit within the national program. Relativistic heavy-ion experiments using 1--2-GeV/nucleon beams have already demonstrated that high temperatures (of the order of 100 MeV) and high densities (up to four times normal nuclear density) are reached in head-on projectile-target collisions. Theoretical predictions now indicate a high probability that, when large amounts of nuclear matter are raised to the extreme temperatures and densities obtainable in head-on heavy-ion collisions at Tevalac beam energies, the quarks that constitute the individual nucleons will be deconfined: they will no longer be bound within individual nucleons, and a state of matter never before observed on earth--the quark-gluon plasma--will be created briefly. The investigation of the quark-gluon plasma will lead to unprecedented scientific opportunities and will serve as a bridge between conventional nuclear physics, which studies complex systems of particles, and high-energy physics, which studies the most fundamental constituents of matter

Quantum chromodynamics as effective theory of quarks and composite gluons

International Nuclear Information System (INIS)

Fuss, T.

2004-01-01

The dynamics of quarks is described by a nonperturbatively regularized NJL model which is canonically quantized and fulfil a probability interpretation. The quantum field theory of this model is formulated in a functional space. The wave functions of the quarks and gluons are calculated as eigenstates of Hard-Core equations and the gluons are considered as relativistic bound states of colored quark-antiquark pairs. The effective dynamics of the quarks and gluons is derived from weak mapping in functional space. This leads to the functional formulation of the phenomenological SU(3) local gauge invariant quark-gluon equations in temporal gauge. This means that the local gauge symmetry is a dynamical effect resulting from the quark model

Chemical Evolution of Strongly Interacting Quark-Gluon Plasma

International Nuclear Information System (INIS)

Pan, Ying-Hua; Zhang, Wei-Ning

2014-01-01

At very initial stage of relativistic heavy ion collisions a wave of quark-gluon matter is produced from the break-up of the strong color electric field and then thermalizes at a short time scale (~1 fm/c). However, the quark-gluon plasma (QGP) system is far out of chemical equilibrium, especially for the heavy quarks which are supposed to reach chemical equilibrium much late. In this paper a continuing quark production picture for strongly interacting QGP system is derived, using the quark number susceptibilities and the equation of state; both of them are from the results calculated by the Wuppertal-Budapest lattice QCD collaboration. We find that the densities of light quarks increase by 75% from the temperature T=400 MeV to T=150 MeV, while the density of strange quark annihilates by 18% in the temperature region. We also offer a discussion on how this late production of quarks affects the final charge-charge correlations

Effects of an electromagnetic quark form factor on meson properties

International Nuclear Information System (INIS)

Silvestre-Brac, B.

2002-01-01

A form factor is introduced in the quark electromagnetic current. Its effect is analyzed on charge mean square radii and form factors in the mesonic sector. The decay of a vector meson into lepton-antilepton pair is also affected. Two different expressions for the form factors, and two different types of quark potential are tested and some relativistic kinematical corrections are proposed. In any case the introduction of a quark form factor greatly improves the agreement with experimental data

Structure functions and pair correlations of the quark-gluon plasma

International Nuclear Information System (INIS)

Thoma, Markus H.

2005-01-01

Recent experiments at RHIC and theoretical considerations indicate that the quark-gluon plasma, present in the fireball of relativistic heavy-ion collisions, might be in a liquid phase. The liquid state can be identified by characteristic correlation and structure functions. Here definitions of the structure functions and pair correlations of the quark-gluon plasma are presented as well as perturbative results. These definitions might be useful for verifying the quark-gluon-plasma liquid in QCD lattice calculations

Future relativistic heavy ion experiments

International Nuclear Information System (INIS)

Pugh, H.G.

1980-12-01

Equations of state for nuclear matter and ongoing experimental studies are discussed. Relativistic heavy ion physics is the only opportunity to study in the laboratory the properties of extended multiquark systems under conditions such that quarks might run together into new arrangements previously unobserved. Several lines of further study are mentioned

Quark mass correction to the string potential

International Nuclear Information System (INIS)

Lambiase, G.; Nesterenko, V.V.

1995-01-01

A consistent method for calculating the interquark potential generated by the relativistic string with massive ends is proposed. In this approach the interquark potential in the model of the Nambu-Goto string with point-like masses at its ends is calculated. At first the calculation is done in the one-loop approximation and then the variational estimation is performed. The quark mass correction results in decreasing the critical distance (deconfinement radius). When quark mass decreases the critical distance also decreases. For obtaining a finite result under summation over eigenfrequencies of the Nambu-Goto string with massive ends a suitable mode-by-mode subtraction is proposed. This renormalization procedure proves to be completely unique. In the framework of the developed approach the one-loop interquark potential in the model of the relativistic string with rigidity is also calculated. 34 refs., 2 figs

Important configurations in six-quark N-N states. II. Current quark model

International Nuclear Information System (INIS)

Stancu, F.; Wilets, L.

1989-01-01

Quark basis states constructed from molecular-type orbitals were shown previously to be more convenient to use than cluster model states for N-N processes. The usual cluster model representation omits configurations which emerge naturally in a molecular basis which contains the same number of spatial functions. The importance of the omitted states was demonstrated for a constituent quark model. The present work extends the study to the prototypical current quark model, namely the MIT bag. In order to test the expansion for short-range N-N interactions, the eigenstates and eigenenergies of six quarks in a spherical bag, including one-gluon exchange, are calculated. The lowest eigenenergies are lowered significantly with respect to the usual cluster model. This reaffirms the importance of dynamics for obtaining the needed short-range repulsion

Quark gluon plasma

CERN Document Server

Nayak, Tapan; Sarkar, Sourav

2014-01-01

At extremely high temperatures and densities, protons and neutrons may dissolve into a "soup" of quarks and gluons, called the Quark-Gluon Plasma (QGP). For a few microseconds, shortly after the Big Bang, the Universe was filled with the QGP matter. The search and study of Quark-Gluon Plasma (QGP) is one of the most fundamental research topics of our times. The QGP matter has been probed by colliding heavy ions at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory, New York and the Large Hadron Collider at CERN, Geneva. By colliding heavy-ions at a speed close to that of light, scientists aim to obtain - albeit over a tiny volume of the size of a nucleus and for an infinitesimally short instant - a QGP state. This QGP state can be observed by dedicated experiments, as it reverts to hadronic matter through expansion and cooling. This volume presents some of the current theoretical and experimental understandings in the field of QGP.

Quark-nuclear hybrid star equation of state with excluded volume effects

Science.gov (United States)

Kaltenborn, Mark Alexander Randolph; Bastian, Niels-Uwe Friedrich; Blaschke, David Bernhard

2017-09-01

A two-phase description of the quark-nuclear matter hybrid equation of state that takes into account the effect of excluded volume in both the hadronic and the quark-matter phases is introduced. The nuclear phase manifests a reduction of the available volume as density increases, leading to a stiffening of the matter. The quark-matter phase displays a reduction of the effective string tension in the confining density functional from available volume contributions. The nuclear equation of state is based upon the relativistic density-functional model DD2 with excluded volume. The quark-matter equation of state is based upon a quasiparticle model derived from a relativistic density-functional approach and will be discussed in greater detail. The interactions are decomposed into mean scalar and vector components. The scalar interaction is motivated by a string potential between quarks, whereas the vector interaction potential is motivated by higher-order interactions of quarks leading to an increased stiffening at high densities. As an application, we consider matter under compact star constraints of electric neutrality and β equilibrium. We obtain mass-radius relations for hybrid stars that form a third family, disconnected from the purely hadronic star branch, and fulfill the 2 M⊙ constraint.

Composite hadrons and relativistic nuclei

International Nuclear Information System (INIS)

Blankenbecler, R.

1978-01-01

Lectures are presented describing a model of hadronic scattering at large momentum transfer, either transverse or longitudinal. This model emphasizes in this regime the importance of forces involving the interchange of constituents of the hadrons, hence its name, the constituent interchange model CIM. The CIM is a rearrangement of standard perturbation theory to take into account the fact that the binding force is very strong in color singlet states (singlet dominance). The hard scattering expansion, incoherence problems, nuclear wave functions and counting rules, interaction between nuclei, pion and proton yields and form factors, structure functions and nonscaling, massive lepton pairs, hadrons at large transverse momentum, and quark-quark scattering are treated. 49 references

Summary of the relativistic heavy ion sessions

International Nuclear Information System (INIS)

Harris, J.W.

1988-01-01

The topics covered in the Relativistic Heavy Ion Sessions span four orders of magnitude in energy in the laboratory and a few more in theory. In the two years since the last Intersections conference, experiments in the field of very high energy heavy ion research have begun at CERN and Brookhaven. The prime motivation for these experiments is the possibility of forming quark matter. This paper is a review of the topics covered in the Relativistic Heavy Ion Sessions

Several crucial problems in evaluating spectra of baryons with two heavy quarks

International Nuclear Information System (INIS)

Tong Shengping; Ding Yibing; Guo Xinheng; Shen Pengnian; Li Xueqian; Zhang Rui

2000-01-01

The spectra of baryons which include two heavy quarks and one light quark can be treated as a two-body system, where two heavy quarks constitute a bosonic diquark. The authors derive the effective potential between the light quark and the heavy diquark. In this work authors have discussed several serious problems: (1) the operator ordering, (2) the errors caused by the non-relativistic expansion, (3) spin-spin coupling and (4) the mixing between baryon states with scalar-diquark and vector-diquark

Faddeev approach in three-quark systems

International Nuclear Information System (INIS)

Kuperin, Yu.A.; Kvintsinskij, A.A.; Merkur'ev, S.P.; Novozhilov, V.Yu.

1985-01-01

Calculations of baryon static properties represent a noval field where the Faddeev differential equations are applied. The mass spectra and were functions of baryons from multiplets of spin-partity Jsup(P)=1/2 + , 3/2 + are investigated in non-relativistic quark model. The structure parameters characterizing the ''quality'' of the baryon wave functions, i.e. charge radii, electromagnetic form factors quark distribution functions, are calculated. It is shown that the majority of the popular qq-potentials do not give ''high quality'' wave functions in spite of the good fit for the hadron masses

Additivity of quark masses in gauge theories

International Nuclear Information System (INIS)

Scadron, M.D.

1987-01-01

It is shown that, in spite of the confinement of quarks in (color-singlet) hadrons, effective quark masses of all types (dynamically generated, constituent and current masses), naturally form hadron masses in an additivity fashion. For the purposes of brevity, the discussion is limited primarily to the nonstrange flavor sector

Studying extremely peripheral collisions of relativistic heavy ions

International Nuclear Information System (INIS)

Fatyga, M.

1990-01-01

Relativistic heavy ion facilities have been proposed (and in some cases constructed) with an intent to search for a new state of matter, a quark gluon plasma. As with all tools in the experimental physics, one should always search for ways in which relativistic heavy ions can be used to study physical phenomena beyond this original goal. New possibilities for a study of higher order photonuclear excitations in extremely peripheral collisions of relativistic heavy ions are discussed in this contribution. Data on the electromagnetic and nuclear fragmentation of a 14.6Gev/nucleon 28 Si projectile are presented

Meson-Meson molecules and compact four-quark states

International Nuclear Information System (INIS)

Vijande, J.; Valcarce, A.

2010-01-01

The physics of charm has become one of the best laboratories exposing the limitations of the naive constituent quark model and also giving hints into a more mature description of meson spectroscopy, beyond the simple quark-antiquark configurations. In this talk we review some recent studies of multiquark components in the charm sector and discuss in particular exotic and non-exotic four-quark systems.

Constituent rearrangement model and large transverse momentum reactions

International Nuclear Information System (INIS)

Igarashi, Yuji; Imachi, Masahiro; Matsuoka, Takeo; Otsuki, Shoichiro; Sawada, Shoji.

1978-01-01

In this chapter, two models based on the constituent rearrangement picture for large p sub( t) phenomena are summarized. One is the quark-junction model, and the other is the correlating quark rearrangement model. Counting rules of the models apply to both two-body reactions and hadron productions. (author)

Radiative leptonic decay: B{sup -}{yields}{mu}{sup -}{nu}{sub {mu}}{gamma} in a relativistic independent quark model

Energy Technology Data Exchange (ETDEWEB)

Barik, N [Department of Physics, Utkal University, Bhubaneswar-751004 (India); Naimuddin, Sk; Dash, P C [Department of Physics, Prananath Autonomous College, Khurda-752057 (India); Kar, Susmita [Department of Physics, North Orissa University, Baripada-757003 (India)

2008-01-01

We study the radiative leptonic decay, B{sup -}{yields}{mu}{sup -}{nu}{sub {mu}}{gamma}, in the framework of a relativistic independent quark model, based on the confining potential in the scalar-vector harmonic form. As expected, we find that the photon emission in this decay overcomes the so-called helicity suppression inevitable in the case of pure leptonic decay (B{sup -}{yields}{mu}{sup -}{nu}{sub {mu}}). Our result for the branching ratio is Br(B{sup -}{yields}{mu}{sup -}{nu}{sub {mu}}{gamma})=1.70x10{sup -6}, which is comparable with other model predictions within the current experimental upper limit. The photon energy spectrum predicted in the model is slightly asymmetric with the peak value around 1.45 GeV, which should render it quite accessible to experimental analysis.

Scaling of nuclear modification factors for hadrons and light nuclei

Energy Technology Data Exchange (ETDEWEB)

Zhou, C.S. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); University of Chinese Academy of Sciences, Beijing (China); Ma, Y.G. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China); ShanghaiTech University, Shanghai (China); Zhang, S. [Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai (China)

2016-12-15

The number of constituent quarks (NCQ) scaling for hadrons and the number of constituent nucleons (NCN) scaling for light nuclei are proposed for nuclear modification factors (R{sub cp}) of hadrons and light nuclei, respectively, according to the experimental investigations in relativistic heavy-ion collisions. Based on the coalescence mechanism the scalings are performed for pions and protons at the quark level, and for light nuclei d(anti d) and {sup 3}He at the nucleonic level, respectively, formed in Au+Au and Pb+Pb collisions, and a nice scaling behaviour emerges. The NCQ or NCN scaling law of R{sub cp} can be, respectively, taken as a probe for the quark or nucleon coalescence mechanism for the formation of hadron or light nuclei in relativistic heavy-ion collisions. (orig.)

Deeply virtual Compton scattering in a relativistic quark model

Energy Technology Data Exchange (ETDEWEB)

Spitzenberg, T.

2007-09-15

This thesis is mainly concerned with a model calculation for generalized parton distributions (GPDs). We calculate vectorial- and axial GPDs for the N{yields}N and N{yields}{delta} transition in the framework of a light front quark model. This requires the elaboration of a connection between transition amplitudes and GPDs. We provide the first quark model calculations for N{yields}{delta} GPDs. The examination of transition amplitudes leads to various model independent consistency relations. These relations are not exactly obeyed by our model calculation since the use of the impulse approximation in the light front quark model leads to a violation of Poincare covariance. We explore the impact of this covariance breaking on the GPDs and form factors which we determine in our model calculation and find large effects. The reference frame dependence of our results which originates from the breaking of Poincare covariance can be eliminated by introducing spurious covariants. We extend this formalism in order to obtain frame independent results from our transition amplitudes. (orig.)

Relativistic Faddeev description of baryons and nucleon structure function in the NJL model

Energy Technology Data Exchange (ETDEWEB)

Bentz, W.; Mineo, H.; Asami, H.; Yazaki, K

2000-05-08

In this work we use the Nambu-Jona-Lasinio (NJL) model as an effective quark theory based on QCD to describe the structure of baryons. Based on the solutions of the relativistic 3-quark Faddeev equation in the ladder approximation, we discuss the masses of the nucleon and the delta, the static properties of the nucleon, and the quark light cone momentum distributions in the nucleon.

B{sup ¯}{sub s}→K semileptonic decay from an Omnès improved constituent quark model

Energy Technology Data Exchange (ETDEWEB)

Albertus, C. [Departamento de Física Atómica, Nuclear y Molecular e Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Avenida de Fuentenueva s/n, E-18071 Granada (Spain); Hernández, E. [Departamento de Física Fundamental e IUFFyM, Universidad de Salamanca, Plaza de la Merced s/n, E-37008 Salamanca (Spain); Hidalgo-Duque, C.; Nieves, J. [Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Institutos de Investigación de Paterna, Apartado 22085, E-46071 Valencia (Spain)

2014-11-10

We study the f{sup +} form factor for the semileptonic B{sup ¯}{sub s}→K{sup +}ℓ{sup −}ν{sup ¯}{sub ℓ} decay in a constituent quark model. The valence quark estimate is supplemented with the contribution from the B{sup ¯⁎} pole that dominates the high q{sup 2} region. We use a multiply-subtracted Omnès dispersion relation to extend the quark model predictions from its region of applicability near q{sub max}{sup 2}=(M{sub B{sub s}}−M{sub K}){sup 2}∼23.75 GeV{sup 2} to all q{sup 2} values accessible in the physical decay. To better constrain the dependence of f{sup +} on q{sup 2}, we fit the subtraction constants to a combined input from previous light cone sum rule by Duplancic and Melic (2008) [11] and the present quark model results. From this analysis, we obtain Γ(B{sup ¯}{sub s}→K{sup +}ℓ{sup −}ν{sup ¯}{sub ℓ})=(5.47{sub −0.46}{sup +0.54})|V{sub ub}|{sup 2}×10{sup −9} MeV, which is about 10% and 20% higher than the predictions based on Lattice QCD and QCD light cone sum rules respectively. The former predictions, for both the form factor f{sup +}(q{sup 2}) and the differential decay width, lie within the 1σ band of our estimated uncertainties for all q{sup 2} values accessible in the physical decay, except for a quite small region very close to q{sub max}{sup 2}. Differences with the light cone sum results for the form factor f{sup +} are larger than 20% in the region above q{sup 2}=15 GeV{sup 2}.

Soap opera: the sad tale of the quark

International Nuclear Information System (INIS)

Lipkin, H.

1984-01-01

The history of quark physics is briefly reviewed, followed by an introduction to quantum chromodynamics, leading terms, and the OZI rule. The basic physics of hadron structure as revealed by experiment is then discussed, followed by the models used to treat it. The two complementary models are the quasinuclear colored quark model and the quark-parton model. Another model for orthogonal physical properties is the bag model. Several applications of the constituent quark model are considered, including hadron masses, spin physics, and multiquark physics. The theoretical basis and phenomenology of the OZI rule forbids processes described by disconnected quark line diagrams

Strangeness and the quark-gluon plasma: An experimenter's perspective

International Nuclear Information System (INIS)

Odyniec, G.

1994-02-01

Current status of experimental results on strange particle production in relativistic nucleus-nucleus collisions is reviewed. Emphasis is placed on the relevance to the hypothetical quark-gluon plasma formation and the origin of the Universe

Hadron production in relativistic heavy ion interactions and the search for the quark-gluon plasma

International Nuclear Information System (INIS)

Tannenbaum, M.J.

1989-12-01

The course starts with an introduction, from the experimentalist's point of view, of the challenge of measuring Relativistic Heavy Ion interactions. A review of some theoretical predictions for the expected signatures of the quark gluon plasma will be made, with a purpose to understand how they relate to quantities which may be experimentally measured. A short exposition of experimental techniques and details is given including charged particles in matter, momentum resolution, kinematics and Lorentz Transformations, calorimetry. Principles of particle identification including magnetic spectrometers, time of flight measurement. Illustrations using the E802 spectrometer and other measured results. Resolution smearing of spectra, and binning effects. Parent to daughter effects in decay, with π 0 → γ γ as an example. The experimental situation from the known data in p -- p collisions and proton-nucleus reactions is reviewed and used as a basis for further discussions. The ''Cronin Effect'' and the ''Seagull Effect'' being two arcana worth noting. Then, selected experiments from the BNL and CERN heavy ion programs are discussed in detail. 118 refs., 45 figs

Study of dibaryon states containing three different types of quarks

International Nuclear Information System (INIS)

Leandri, J.; Silvestre-Brac, B.

1997-01-01

Previously we have shown, in a simple chromomagnetic model, that including heavy quarks in the dibaryon sector can lead to favorable configurations for stability against decay into two baryons. In this study we investigate a reduced set of favorable candidates that have emerged from our previous works. We use a non-relativistic quark model with quarks interacting through a QCD-inspired potential, which has been tested previously in meson and baryon spectroscopy. A variational procedure is performed using a great number of Gaussian functions containing all the possibilities for colour, isospin, and spin components. (author)

Quarks in hadrons and nuclei and electromagnetic probes

International Nuclear Information System (INIS)

Faessler, Amand

1995-01-01

Deuteron properties and nuclear magnetic moments are studied in the non-relativistic quark cluster model. The quark cluster model is modified to include chiral symmetry. This reduces the number of parameters. The σ meson is exchanged between quarks and not as in earlier versions between nucleons. The charge monopole, quadrupole and magnetic-dipole form factors and the tensor polarization of the deuteron in this microscopic meson-quark cluster model are calculated. The deuteron wave function is derived from a microscopic 6-quark Hamiltonian which, in addition to a quadratic confinement potential, includes the one-pion and the one-gluon exchange potentials between quarks. The electromagnetic current operators are constructed on the quark level, i.e., the photon is coupled directly to the quarks. Aside from the one-body impulse current, pionic and gluonic exchange current corrections are included. Due to the Pauli principle on the quark level, new quark interchange terms arise in the one-body and two-body current matrix elements, that are not present on the nucleon level. While these additional quark exchange currents are small for low momentum transfers, we find that they appreciably influence the electromagnetic structure of the deuteron beyond a momentum transfer of q = 5fm -1 . (author)

Optimized non relativistic potential for quarkonium

International Nuclear Information System (INIS)

Rekab, S.; Zenine, N.

2006-01-01

For non relativistic quarkonia description, we consider a wide class of quark antiquark potentials in the form of power law. A systematic study is made by optimizing the potential parameters with a fit on quarkonia vector mesons that lie below the threshold for strong decays. Implications of the obtained results are discussed

Constraints on constituent quark masses from potential models

International Nuclear Information System (INIS)

Silvestre-Brac, B.

1998-01-01

Starting from reasonable hypotheses, the magnetic moments for the baryons are revisited dat the light of general space wave functions. They allow to put very severe bounds on the quark masses as derived from usual potential models. The experimental situation cannot be explained in the framework of such models. (author)

Constituent models and large transverse momentum reactions

International Nuclear Information System (INIS)

Brodsky, S.J.

1975-01-01

The discussion of constituent models and large transverse momentum reactions includes the structure of hard scattering models, dimensional counting rules for large transverse momentum reactions, dimensional counting and exclusive processes, the deuteron form factor, applications to inclusive reactions, predictions for meson and photon beams, the charge-cubed test for the e/sup +-/p → e/sup +-/γX asymmetry, the quasi-elastic peak in inclusive hadronic reactions, correlations, and the multiplicity bump at large transverse momentum. Also covered are the partition method for bound state calculations, proofs of dimensional counting, minimal neutralization and quark--quark scattering, the development of the constituent interchange model, and the A dependence of high transverse momentum reactions

Resource Letter Q-1: quarks

International Nuclear Information System (INIS)

Greenberg, O.W.

1982-01-01

Quarks as fundamental constituents of hadrons play a central role in elementary particle physics. We give an annotated bibliography of references to quarks and related topics in elementary particle physics, as well as to the role of quarks in areas outside elementary particle physics, such as nuclear physics, and astrophysics and cosmology. We label references E (elementary), I (intermediate), and A (advanced) to guide the reader. Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are indicated by an an asterisk. A short list of particularly helpful elementary and intermediate references is indicated by a star

Polarized constituent quarks in NLO approximation

International Nuclear Information System (INIS)

Khorramian, Ali N.; Tehrani, S. Atashbar; Mirjalili, A.

2006-01-01

The valon representation provides a basis between hadrons and quarks, in terms of which the bound-state and scattering properties of hadrons can be united and described. We studied polarized valon distributions which have an important role in describing the spin dependence of parton distribution in leading and next-to-leading order approximation. Convolution integral in frame work of valon model as a useful tool, was used in polarized case. To obtain polarized parton distributions in a proton we need to polarized valon distribution in a proton and polarized parton distributions inside the valon. We employed Bernstein polynomial averages to get unknown parameters of polarized valon distributions by fitting to available experimental data

Measuring the sea quark polarization

International Nuclear Information System (INIS)

Makdisi, Y.

1993-01-01

Spin is a fundamental degree of freedom and measuring the spin structure functions of the nucleon should be a basic endeavor for hadron physics. Polarization experiments have been the domain of fixed target experiments. Over the years large transverse asymmetries have been observed where the prevailing QCD theories predicted little or no asymmetries, and conversely the latest deep inelastic scattering experiments of polarized leptons from polarized targets point to the possibility that little of the nucleon spin is carried by the valence quarks. The possibility of colliding high luminosity polarized proton beams in the Brookhaven Relativistic Heavy Ion Collider (RHIC) provides a great opportunity to extend these studies and systematically probe the spin dependent parton distributions specially to those reactions that are inaccessible to current experiments. This presentation focuses on the measurement of sea quark and possibly the strange quark polarization utilizing the approved RHIC detectors

Theoretical perspective on RHIC [relativistic heavy ion collider] physics

International Nuclear Information System (INIS)

Dover, C.B.

1990-10-01

We discuss the status of the relativistic heavy ion collider (RHIC) project at Brookhaven, and assess some key experiments which propose to detect the signatures of a transient quark-gluon plasma (QGP) phase in such collisions. 24 refs

Heavy quark threshold dynamics in higher order

Energy Technology Data Exchange (ETDEWEB)

Piclum, J.H.

2007-05-15

In this work we discuss an important building block for the next-to-next-to-next-to leading order corrections to the pair production of top quarks at threshold. Specifically, we explain the calculation of the third order strong corrections to the matching coefficient of the vector current in non-relativistic Quantum Chromodynamics and provide the result for the fermionic part, containing at least one loop of massless quarks. As a byproduct, we obtain the matching coefficients of the axial-vector, pseudo-scalar and scalar current at the same order. Furthermore, we calculate the three-loop corrections to the quark renormalisation constants in the on-shell scheme in the framework of dimensional regularisation and dimensional reduction. Finally, we compute the third order strong corrections to the chromomagnetic interaction in Heavy Quark Effective Theory. The calculational methods are discussed in detail and results for the master integrals are given. (orig.)

Photons from the early stages of relativistic heavy-ion collisions

Science.gov (United States)

Oliva, L.; Ruggieri, M.; Plumari, S.; Scardina, F.; Peng, G. X.; Greco, V.

2017-07-01

We present results about photon-production in relativistic heavy-ion collisions. The main novelty of our study is the calculation of the contribution of the early-stage photons to the photon spectrum. The initial stage is modeled by an ensemble of classical gluon fields which decay to a quark-gluon plasma via the Schwinger mechanism, and the evolution of the system is studied by coupling classical field equations to relativistic kinetic theory; photon production is then computed by including the pertinent collision processes into the collision integral. We find that the contribution of the early-stage photons to the direct photon spectrum is substantial for pT≈2 GeV and higher, the exact value depending on the collision energy; therefore, we identify this part of the photon spectrum as the sign of the early stage. Moreover, the amount of photons produced during the early stage is not negligible with respect to those produced by a thermalized quark-gluon plasma: We support the idea that there is no dark age in relativistic heavy-ion collisions.

Entropy production in the relativistic heavy ion collisions

International Nuclear Information System (INIS)

Holme, A.K.; Csernai, L.P.; Levai, P.; Papp, G.

1989-09-01

A short overview is given on the most important possibilities of entropy production in the relativistic heavy ion collisions, which is connected to the shock phenomena. The E802 experiment is considered as an example, where one can determine the specific entropy content from measured strange particle ratios. The received large entropy value (S/N B ∼ 14) can be explained by assuming quark-gluon plasma formation. The possibility of overcooling of quark-gluon plasma and its deflagration are also investigated. (author) 22 refs.; 4 figs

Proton relativistic model

International Nuclear Information System (INIS)

Araujo, Wilson Roberto Barbosa de

1995-01-01

In this dissertation, we present a model for the nucleon, which is composed by three relativistic quarks interacting through a contract force. The nucleon wave-function was obtained from the Faddeev equation in the null-plane. The covariance of the model under kinematical null-plane boots is discussed. The electric proton form-factor, calculated from the Faddeev wave-function, was in agreement with the data for low-momentum transfers and described qualitatively the asymptotic region for momentum transfers around 2 GeV. (author)

Langevin dynamics of heavy flavors in relativistic heavy-ion collisions

CERN Document Server

Alberico, W M; De Pace, A; Molinari, A; Monteno, M; Nardi, M; Prino, F

2011-01-01

We study the stochastic dynamics of c and b quarks, produced in hard initial processes, in the hot medium created after the collision of two relativistic heavy ions. This is done through the numerical solution of the relativistic Langevin equation. The latter requires the knowledge of the friction and diffusion coefficients, whose microscopic evaluation is performed treating separately the contribution of soft and hard collisions. The evolution of the background medium is described by ideal/viscous hydrodynamics. Below the critical temperature the heavy quarks are converted into hadrons, whose semileptonic decays provide single-electron spectra to be compared with the current experimental data measured at RHIC. We focus on the nuclear modification factor R_AA and on the elliptic-flow coefficient v_2, getting, for sufficiently large p_T, a reasonable agreement.

Prospects of detecting baryon and quark superfluidity from cooling neutron stars

Science.gov (United States)

Page; Prakash; Lattimer; Steiner

2000-09-04

Baryon and quark superfluidity in the cooling of neutron stars are investigated. Future observations will allow us to constrain combinations of the neutron or Lambda-hyperon pairing gaps and the star's mass. However, in a hybrid star with a mixed phase of hadrons and quarks, quark gaps larger than a few tenths of an MeV render quark matter virtually invisible for cooling. If the quark gap is smaller, quark superfluidity could be important, but its effects will be nearly impossible to distinguish from those of other baryonic constituents.

A tail of a quark in N = 4 SYM

International Nuclear Information System (INIS)

Chernicoff, Mariano; Garcia, J. Antonio; Gueijosa, Alberto

2009-01-01

We study the dynamics of a 'composite' or 'dressed' quark in strongly-coupled large-N c N = 4 super-Yang-Mills, making use of the AdS/CFT correspondence. We show that the standard string dynamics nicely captures the physics of the quark and its surrounding non-Abelian field configuration, making it possible to derive a relativistic equation of motion that incorporates the effects of radiation damping. From this equation one can deduce a non-standard dispersion relation for the composite quark, as well as a Lorentz covariant formula for its rate of radiation. We explore the consequences of the equation in a few simple examples.

Decay constants in the heavy quark limit in models a la Bakamjian and Thomas

International Nuclear Information System (INIS)

Morenas, V.; Le Yaouanc, A.; Oliver, L.; Pene, O.; Raynal, J.C.

1997-07-01

In quark models a la Bakamjian and Thomas, that yield covariance and Isgur-Wise scaling of form factors in the heavy quark limit, the decay constants f (n) and f 1/2 (n) of S-wave and P-wave mesons composed of heavy and light quarks are computed. Different Ansaetze for the dynamics of the mass operator at rest are discussed. Using phenomenological models of the spectrum with relativistic kinetic energy and regularized short distance part the decay constants in the heavy quark limit are calculated. The convergence of the heavy quark limit sum rules is also studied. (author)

A relativistic quarkonium potential model

International Nuclear Information System (INIS)

Klima, B.; Maor, U.

1984-04-01

We review a recently developed relativistic quark-antiquark bound state equation using the expansion in intermediate states. Using a QCD motivated potential we succeeded very well to fit both the heavy systems (banti b, canti c) and the light systems (santi s, uanti u and danti d). Here we emphasize our results on heavy-light sustems and on the possible (tanti t) family. (orig.)

Relativistic bound states: a mass formula for vector mesons

International Nuclear Information System (INIS)

Richard, J.L.; Sorba, P.

1975-07-01

In the framework of a relativistic description of two particles bound states, a mass formula for vector mesons considered as quark-antiquark systems bound by harmonic oscillator like forces is proposed. Results in good agreement with experimental values are obtained [fr

Orbital angular momentum parton distributions in quark models

International Nuclear Information System (INIS)

Scopetta, S.; Vento, V.

2000-01-01

At the low energy, hadronic, scale we calculate Orbital Angular Momentum (OAM) twist-two parton distributions for the relativistic MIT bag model and for nonrelativistic quark models. We reach the scale of the data by leading order evolution in perturbative QCD. We confirm that the contribution of quarks and gluons OAM to the nucleon spin grows with Q 2 , and it can be relevant at the experimental scale, even if it is negligible at the hadronic scale, irrespective of the model used. The sign and shape of the quark OAM distribution at high Q 2 may depend strongly on the relative size of the OAM and spin distributions at the hadronic scale. Sizeable quark OAM distributions at the hadronic scale, as proposed by several authors, can produce the dominant contribution to the nucleon spin at high Q 2 . (author)

Quasirelativistic quark model in quasipotential approach

CERN Document Server

Matveev, V A; Savrin, V I; Sissakian, A N

2002-01-01

The relativistic particles interaction is described within the frames of quasipotential approach. The presentation is based on the so called covariant simultaneous formulation of the quantum field theory, where by the theory is considered on the spatial-like three-dimensional hypersurface in the Minkowski space. Special attention is paid to the methods of plotting various quasipotentials as well as to the applications of the quasipotential approach to describing the characteristics of the relativistic particles interaction in the quark models, namely: the hadrons elastic scattering amplitudes, the mass spectra and widths mesons decays, the cross sections of the deep inelastic leptons scattering on the hadrons

An introduction to quark-gluon plasma and high energy heavy ion collisions

International Nuclear Information System (INIS)

McLerran, L.

1987-01-01

The quark-gluon plasma, and how it might be produced in ultra-relativistic nuclear collisions is reviewed. I briefly introduce the quark-gluon plasma, and what we might learn from studying it. I then discuss what has been learned from the recent results from the CERN oxygen run. I then attempt to address the issue of whether A = 16 and E = 200 GeV are sufficient to make a quark-gluon plasma. I discuss strangeness and charm production as well as electromagnetic probes of the plasma

KN interaction in a constituent quark model

International Nuclear Information System (INIS)

Labarsouque, J.; Leandri, J.; Silvestre Brac, B.

1997-01-01

The kaon-nucleon s-wave phase shift have been calculated in a quark potential model using the resonating group method. The Hill-Wheeler equation has been solved numerically without any parametrization of the KN relative wave-function. The I = 0 phase shift has been found in agreement with the experimental data. In the I = 1 channel too much repulsion has been obtained., probably due to the lack of medium-range boson exchange type attraction. In a second step, pion and sigma-type exchange have been incorporated in the calculation

Limits and signatures of relativistic spaceflight

Science.gov (United States)

Yurtsever, Ulvi; Wilkinson, Steven

2018-01-01

While special relativity imposes an absolute speed limit at the speed of light, our Universe is not empty Minkowski spacetime. The constituents that fill the interstellar/intergalactic vacuum, including the cosmic microwave background photons, impose a lower speed limit on any object travelling at relativistic velocities. Scattering of cosmic microwave photons from an ultra-relativistic object may create radiation with a characteristic signature allowing the detection of such objects at large distances.

CONFERENCE: Quark Matter '95

International Nuclear Information System (INIS)

Anon.

1995-01-01

High energy heavy ion collisions have become one of the major growth areas of modern physics. Providing common ground between particle and nuclear physics, it has produced a wave of new interest and a series of major projects to provide beams of higher energies and increasing nuclear complexity. Reflecting this interest, and despite record rainstorms, over 450 enthusiastic high energy heavy ion followers met in Monterey, California, at the 11th International Conference on Ultra-relativistic Nucleus-Nucleus Collisions. Named Quark Matter '95, the meeting was characterized by its own flood of new results from experiments studying collisions of gold nuclei at the Brookhaven Alternating Gradient Synchrotron (AGS) and with silicon beams at the CERN SPS synchrotron, as well as preliminary results from the first run with lead beams at CERN late last year (December 1994, page 15). A striking aspect of the Conference was the growth in attendance and, in particular, the large number of young physicists who attended the meeting, underlining the vitality and appeal of this important field. The new preliminary data from CERN experiments NA44, NA49, NA52, WA97, and WA98, made available with remarkable speed following the initial lead beam run in November and December 1994, represent a significant step in the study of heavy ion collisions. Physicists have finally come close to conditions where it is possible to consider event-by-event analysis of these very complex final states. The importance of this emerging approach to relativistic heavy ion collisions was emphasized by Reinhard Stock (Frankfurt) and other speakers in a pre-conference workshop devoted to physics with the collider detectors at big new projects now in the pipeline - RHIC at Brookhaven and LHC at CERN. The study of collisions of heavy nuclei at relativistic energies is dominated by the search for the Quark-Gluon Plasma, the 'soup' of free quarks and gluons expected to have played an important role

Relativistic hydrodynamics, heavy ion reactions and antiproton annihilation

International Nuclear Information System (INIS)

Strottman, D.

1985-01-01

The application of relativistic hydrodynamics to relativistic heavy ions and antiproton annihilation is summarized. Conditions for validity of hydrodynamics are presented. Theoretical results for inclusive particle spectra, pion production and flow analysis are given for medium energy heavy ions. The two-fluid model is introduced and results presented for reactions from 800 MeV per nucleon to 15 GeV on 15 GeV per nucleon. Temperatures and densities attained in antiproton annihilation are given. Finally, signals which might indicate the presence of a quark-gluon plasma are briefly surveyed

A nucleon description based on confinement and a dynamic generation of the quark masses

International Nuclear Information System (INIS)

Caillon, J.C.

2010-01-01

We have considered the nucleon as an MIT bag, but instead of a perturbative vacuum, we use a QCD vacuum modified as compared to the outside space and hence a modified quark-condensate. Quarks acquire their constituent-masses through their interactions with this modified QCD vacuum in a framework of an NJL model. The value of the quark condensate modified in the nucleon is then determined self-consistently by the equilibrium condition for the bag: the outward pressure due to both the motion of three quarks and the modified vacuum in the nucleon must be counterbalanced by the inward pressure of the vacuum outside the bag. We are able to pass continuously from a nucleon description in a pure MIT bag model to a description using constituent quark masses determined in an NJL model.

Pion-cloud corrections to the relativistic S + V harmonic potential model

International Nuclear Information System (INIS)

Palladino, B.E.; Ferreira, P.L.

1988-01-01

Pionic corrections to the mass spectrum of low-lying s-wave baryons are incorporated in a relativistic independent quark model with equally mixed Lorentz scalar and vector harmonic potentials. (M.W.O.) [pt

Nonperturbative aspects of the quark-photon vertex

International Nuclear Information System (INIS)

Frank, M.R.

1994-01-01

The electromagnetic interaction with quarks is investigated through a relativistic, electromagnetic gauge-invariant treatment. Gluon dressing of the quark-photon vertex and the quark self-energy functions is described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger-Dyson equation in the rainbow approximation respectively. Results for the calculation of the quark-photon vertex are presented in both the time-like and space-like regions of photon momentum squared, however emphasis is placed on the space-like region relevant to electron scattering. The treatment presented here simultaneously addresses the role of dynamically generated q bar q vector bound states and the approach to asymptotic behavior. The resulting description is therefore applicable over the entire range of momentum transfers available in electron scattering experiments. Input parameters are limited to the model gluon two-point function which is chosen to reflect confinement and asymptotic freedom and are largely constrained by the obtained bound-state spectrum

A path integral for heavy-quarks in a hot plasma

CERN Document Server

Beraudo, A.; Faccioli, P.; Garberoglio, G.; 10.1016/j.nuclphysa.2010.06.007

2010-01-01

We propose a model for the propagation of a heavy-quark in a hot plasma, to be viewed as a first step towards a full description of the dynamics of heavy quark systems in a quark-gluon plasma, including bound state formation. The heavy quark is treated as a non relativistic particle interacting with a fluctuating field, whose correlator is determined by a hard thermal loop approximation. This approximation, which concerns only the medium in which the heavy quark propagates, is the only one that is made, and it can be improved. The dynamics of the heavy quark is given exactly by a quantum mechanical path integral that is calculated in this paper in the Euclidean space-time using numerical Monte Carlo techniques. The spectral function of the heavy quark in the medium is then reconstructed using a Maximum Entropy Method. The path integral is also evaluated exactly in the case where the mass of the heavy quark is infinite; one then recovers known results concerning the complex optical potential that controls the ...

Quark-lepton unification and proton decay

International Nuclear Information System (INIS)

Pati, J.C.; Salam, A.

1980-05-01

Complexions for proton decay arising within a maximal symmetry for quark-lepton unification, which leads to spontaneous rather than intrinsic violations of B, L and F are considered. Four major modes satisfying δB=-1 and δF=0, -2, -4 and -6 are noted. It is stressed that some of these modes can coexist in accord with allowed solutions for renormalization group equations for coupling constants for a class of unifying symmetries. None of these remarks is dependent on the nature of quark charges. It is noted that if quarks and leptons are made of constituent preons, the preon binding is likely to be magnetic. (author)

Workshop: Waiting for the top quark

International Nuclear Information System (INIS)

Anon.

1991-01-01

The world of elementary particle physics is eagerly waiting for the top quark, probably the final element of the 'periodic table' of elementary particle constituents. This table consists of two families of weakly interacting particles (leptons) - one series carrying electric charge; the other being electrically neutral - together with a family of quarks carrying electric charge 2/3 (up, charm, top) and a family of charge -1/3 quarks (down, strange, beauty). It was then not surprising that the 1990 Theory Workshop at the DESY Laboratory in Hamburg in October, devoted this time to 'top physics', attracted some 200 physicists, substantially more than previous workshops in the series

Negative parity non-strange baryons

International Nuclear Information System (INIS)

Stancu, F.; Stassart, P.

1991-01-01

Our previous study is extended to negative parity baryon resonances up to J=(9/2) - . The framework is a semi-relativistic constituent quark model. The quark-quark interaction contains a Coulomb plus linear confinement terms and a short distance spin-spin and tensor terms. It is emphasized that a linear confinement potential gives too large a mass to the D 35 (1930) resonance. (orig.)

The quark gluon plasma; Le plasma de quarks et de gluons

Energy Technology Data Exchange (ETDEWEB)

Granier de Cassagnac, R. [Ecole Polytechnique, Lab. Leprince-Ringuet, 91 - Palaiseau (France)

2010-05-15

The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)

Cooking Up Hot Quark Soup

Science.gov (United States)

Walsh, Karen McNulty

2011-03-28

Near-light-speed collisions of gold ions provide a recipe for in-depth explorations of matter and fundamental forces. The Relativistic Heavy Ion Collider (RHIC) has produced the most massive antimatter nucleus ever discovered?and the first containing an anti-strange quark. The presence of strange antimatter makes this antinucleus the first to be entered below the plane of the classic Periodic Table of Elements, marking a new frontier in physics.

Proceedings of the Workshop on relativistic heavy ion physics at present and future accelerators

International Nuclear Information System (INIS)

Csoergoe, T.; Hegyi, S.; Lukacs, B.; Zimanyi, J.

1991-09-01

This volume contains the Proceedings of the Budapest Workshop on relativistic heavy ion physics at present and future accelerators. The topics includes experimental heavy ion physics, particle phenomenology, Bose-Einstein correlations, relativistic transport theory, quark-gluon plasma rehadronization, astronuclear physics, leptonpair production and intermittency. All contributions were indexed separately for the INIS database. (G.P.)

Quark distributions in nuclear matter and the EMC effect

Energy Technology Data Exchange (ETDEWEB)

Mineo, H.; Bentz, W. E-mail: bentz@keyaki.cc.u-tokai.ac.jp; Ishii, N.; Thomas, A.W.; Yazaki, K

2004-05-03

Quark light cone momentum distributions in nuclear matter and the structure function of a bound nucleon are investigated in the framework of the Nambu-Jona-Lasinio model. This framework describes the nucleon as a relativistic quark-diquark state, and the nuclear matter equation of state by using the mean field approximation. The scalar and vector mean fields in the nuclear medium couple to the quarks in the nucleon and their effect on the spin independent nuclear structure function is investigated in detail. Special emphasis is placed on the important effect of the vector mean field and on a formulation which guarantees the validity of the number and momentum sum rules from the outset.

The Mesozoic Era of relativistic heavy ion physics and beyond

International Nuclear Information System (INIS)

Harris, J.W.

1994-03-01

In order to understand how matter 15 billion years ago in the form of quarks, gluons and leptons at a temperature of 2 x 10 12 degrees K evolved to become today's Universe, the goal of relativistic and ultra-relativistic heavy ion physics is to understand the equation of state of nuclear, hadronic and partonic matter. This quest is of cross-disciplinary interest. The phase transition from partonic matter to hadronic matter tens of micro-seconds after the beginning of the universe is of interest to cosmology. Fluctuations during this phase transition would influence nucleosynthesis and the understanding of baryonic inhomogeneities in the universe. The nuclear matter equation of state, which describes the incompressibility of nuclear matter, governs neutron star stability. It determines the possible existence of strange quark matter stars and the dynamics of supernova expansion in astrophysics. The existence of collective nuclear phenomena in nuclear physics is also determined by the nuclear equation of state. In relativistic heavy ion collisions collective nuclear flow has been observed and is being studied extensively to obtain a better understanding of the incompressibility of nuclear matter. In high energy nuclear and particle physics, production and excitations of hadronic final states have been studied in detail and are important to an overall understanding of the equation of state of nuclear matter at finite temperature. The possibility in ultra-relativistic heavy ion collisions to create and study highly excited hadronic and partonic degrees of freedom provides a unique opportunity for understanding the behavior of nuclear, hadronic and partonic matter. Study of the QCD vacuum, of particular interest in particle physics, would provide a better understanding of symmetry-breaking mechanisms and the origins of the masses of the various quarks and particles

QCD-based relativistic Hartree-Fock calculations for identical quarks

International Nuclear Information System (INIS)

Dey, J.; Dey, M.; Le Tourneux, J.

1985-12-01

As was first pointed out by Witten, large number of colours (Nsub(c)) leads to a simplification in the theory of baryon masses in that the quarks may be assumed to move in a mean field which can be found self-consistently. The interquark potential in such a description can be borrowed from the meson sector phenomenology in the absence of an accurate evaluation of it from large Nsub(c) quantum chromodynamics (QCD). We have carried out this program with such a potential due to Richardson, used often by workers in the meson sector. This potential has the advantage of incorporating the two main features of QCD, namely confinement and asymptotic freedom. In view of the small number of parameters involved, the results agree surprisingly well with experiment for the case of three identical quarks. (author)

A tail of a quark in Script N = 4 SYM

Science.gov (United States)

Chernicoff, Mariano; García, J. Antonio; Güijosa, Alberto

2009-09-01

We study the dynamics of a `composite' or `dressed' quark in strongly-coupled large-Nc Script N = 4 super-Yang-Mills, making use of the AdS/CFT correspondence. We show that the standard string dynamics nicely captures the physics of the quark and its surrounding non-Abelian field configuration, making it possible to derive a relativistic equation of motion that incorporates the effects of radiation damping. From this equation one can deduce a non-standard dispersion relation for the composite quark, as well as a Lorentz covariant formula for its rate of radiation. We explore the consequences of the equation in a few simple examples.

Dilepton as a signature for the baryon-rich quark-gluon matter

International Nuclear Information System (INIS)

Zejun He; Jiaju Zhang

1995-01-01

From the full stopping scenario, we study dilepton production in a baryon rich quark-gluon fireball on the basis of a relativistic hydrodynamic model, and find that with increasing initial baryon density a characteristic valley and a subsequent peak, which more uniquely signal the formation of the baryon-rich quark-gluon matter, appear in the total dilepton yield. Such characteristics can be tested in future experiments at CERN and Brookhaven. (author). Letter-to-the-editor

Accelerator-colliders for relativistic heavy ions or in search of luminosity

International Nuclear Information System (INIS)

Young, G.R.

1984-01-01

Some issues pertinent to the design of collider rings for relativistic heavy ions are presented. Experiments at such facilities are felt to offer the best chance for creating in the laboratory a new phase of subatomic matter, the quark-gluon plasma. It appears possible to design a machine with sufficient luminosity, even for the heaviest nuclei in nature, to allow a thorough exploration of the production conditions and decay characteristics of quark-gluon plasma

Relativistic description of quark-antiquark bound states. Spin-independent treatment

International Nuclear Information System (INIS)

Gara, A.; Durand, B.; Durand, L.; Nickisch, L.J.

1989-01-01

We present the results of a detailed study of light- and heavy-quark--antiquark bound states in the context of the reduced Bethe-Salpeter equation with static vector and scalar interactions. In the present paper, we consider the spin-averaged spectra. Spin effects are considered in a separate paper. We find that this approach, although apparently successful for the heavy-quark b bar b and c bar c states, fails for the s bar s, l bar l, and light-heavy states. The reasons for the failure are intrinsic to the method, as we discuss. Difficulties are already evident for the c bar c states

Identification of Hadronically Decaying W Bosons and Top Quarks using Multivariate Techniques at ATLAS

CERN Document Server

Nitta, Tatsumi; The ATLAS collaboration

2017-01-01

By colliding protons and examining the particle emitted from the collisions, the Large Hadron Collider aims to study the interactions of quarks and gluons at the highest energies accessible in a controlled experimental way. In such collisions, the types of interactions that occur may extend beyond those encompassed by the Standard Model of particle physics. Such interactions typically occur at energy scales much higher than the rest mass of the incoming or outgoing particles. Because of this, reconstructing highly relativistic particles emitted from these collisions is becoming increasingly important. In particular, the ability to identify the originating particle which decays hadronically using distinguishing features of the radiation pattern of the jet plays a central role in searches. This is typically done by the use of a single physically motivated observable constructed from the constituents of the jet. In this work, multiple complementary observables are combined using boosted decision trees and neural...

Relativistic generalisation of the Kroll-Watson formula

International Nuclear Information System (INIS)

Kaminski, J.Z.

1985-01-01

The relativistic analogue of the space-translation method is derived. Using this method the generalisation of the Kroll-Watson formula [1973, Phys. Rev. A. 8 804] is obtained for the scattering of an arbitrary charged particle (e.g. mesons, hyperons, quarks, etc). The separation of the background and resonant parts of the scattering amplitude is predicted. (author)

Partonic transverse momenta in non-relativistic hyper-central quark potential models

International Nuclear Information System (INIS)

Diakonos, F.K.; Kaplis, N.K.; Maintas, X.N.

2009-01-01

We investigate the impact of three-body forces on the transverse-momentum distribution of partons inside the proton. This is achieved by considering the three-body problem in a class of hyper-central quark potential models. Solving the corresponding Schroedinger equation, we determine the quark wave function in the proton and with appropriate transformations and projections we find the transverse-momentum distribution of a single quark. In each case the parameters of the quark potentials are adjusted in order to sufficiently describe observable properties of the proton. Using a factorization ansatz, we incorporate the obtained transverse-momentum distribution in a perturbative QCD scheme for the calculation of the cross-section for prompt photon production in pp collisions. A large set of experimental data is fitted using as a single free parameter the mean partonic transverse momentum. The dependence of left angle k T right angle on the collision characteristics (initial energy and transverse momentum of the final photon) is much smoother when compared with similar results found in the literature using a Gaussian distribution for the partonic transverse momenta. Within the considered class of hyper-central quark potentials the one with the weaker dependence on the hyper-radius is preferred for the description of the data since it leads to the smoothest mean partonic transverse-momentum profile. We have repeated all the calculations using a two-body potential of the same form as the optimal (within the considered class) hyper-central potential in order to check if the presence of three-body forces is supported by the experimental data. Our analysis indicates that three-body forces influence significantly the form of the parton transverse-momentum distribution and consequently lead to an improved description of the considered data. (orig.)

The spin predictions of the relativistic quark model for baryon decuplet production

CERN Document Server

Montvay, István

1973-01-01

Single-quark scattering contributions are considered in the case of ground-state decuplet baryon production. It is shown within the framework of an explicitly covariant approach that the spin consequences of the quark additivity assumption hold in the t-channel helicity frame independently of much of the details of the model. (12 refs).

FY07 LDRD Final Report Heavy Quark Jet Tomography

International Nuclear Information System (INIS)

Soltz, R.; Newby, J.; Glenn, A.; Klay, J.

2008-01-01

We propose and develop a new signature, the measurement of hadron-electron correlations to measure energy loss of heavy quarks in the quark-gluon plasma. This measurements will be used in future analyses to quantify the energy densities created in collisions of heavy ions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab and the Large Hadron Collider (LHC) at CERN. In addition we develop and implement a computing model that will leverage LLNL expertise in cost-effective high performance computing to perform data analyses and simulations for the ALICE experiment at CERN

From Lattice Boltzmann to hydrodynamics in dissipative relativistic fluids

Science.gov (United States)

Gabbana, Alessandro; Mendoza, Miller; Succi, Sauro; Tripiccione, Raffaele

2017-11-01

Relativistic fluid dynamics is currently applied to several fields of modern physics, covering many physical scales, from astrophysics, to atomic scales (e.g. in the study of effective 2D systems such as graphene) and further down to subnuclear scales (e.g. quark-gluon plasmas). This talk focuses on recent progress in the largely debated connection between kinetic transport coefficients and macroscopic hydrodynamic parameters in dissipative relativistic fluid dynamics. We use a new relativistic Lattice Boltzmann method (RLBM), able to handle from ultra-relativistic to almost non-relativistic flows, and obtain strong evidence that the Chapman-Enskog expansion provides the correct pathway from kinetic theory to hydrodynamics. This analysis confirms recently obtained theoretical results, which can be used to obtain accurate calibrations for RLBM methods applied to realistic physics systems in the relativistic regime. Using this calibration methodology, RLBM methods are able to deliver improved physical accuracy in the simulation of the physical systems described above. European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 642069.

Neutrino radiation-hydrodynamics. General relativistic versus multidimensional supernova simulations

International Nuclear Information System (INIS)

Liebendoerfer, Matthias; Fischer, Tobias; Hempel, Matthias

2010-01-01

Recently, simulations of the collapse of massive stars showed that selected models of the QCD phase transitions to deconfined quarks during the early postbounce phase can trigger the supernova explosion that has been searched for over many years in spherically symmetric supernova models. Using sophisticated general relativistic Boltzmann neutrino transport, it was found that a characteristic neutrino signature is emitted that permits to falsify or identify this scenario in the next Galactic supernova event. On the other hand, more refined observations of past supernovae and progressing theoretical research in different supernova groups demonstrated that the effects of multidimensional fluid instabilities cannot be neglected in global models of the explosions of massive stars. We point to different efforts where neutrino transport and general relativistic effects are combined with multidimensional fluid instabilities in supernovae. With those, it will be possible to explore the gravitational wave emission as a potential second characteristic observable of the presence of quark matter in new-born neutron stars. (author)

Matter Formed at the BNL Relativistic Heavy Ion Collider

International Nuclear Information System (INIS)

Brown, G.E.; Gelman, B.A.; Rho, Mannque

2006-01-01

We suggest that the 'new form of matter' found just above T c by the Relativistic Heavy Ion Collider is made up of tightly bound quark-antiquark pairs, essentially 32 chirally restored (more precisely, nearly massless) mesons of the quantum numbers of π, σ, ρ, and a 1 . Taking the results of lattice gauge simulations (LGS) for the color Coulomb potential from the work of the Bielefeld group and feeding this into a relativistic two-body code, after modifying the heavy-quark lattice results so as to include the velocity-velocity interaction, all ground-state eigenvalues of the 32 mesons go to zero at T c just as they do from below T c as predicted by the vector manifestation of hidden local symmetry. This could explain the rapid rise in entropy up to T c found in LGS calculations. We argue that how the dynamics work can be understood from the behavior of the hard and soft glue

Roles of quarks and gluons in the spin structure of nucleons

International Nuclear Information System (INIS)

Modarres, M.; Amir-Kabir Univ., Teheran; Ghafoori-Tabrizi, K.; Shahid-Beheshti Univ., Teheran

1992-01-01

The spin structure of protons will be discussed by using MIT-bag model and considering constituent quarks to be combined from current quarks and gluons. It will be shown that the gluonic degrees of freedom play an important role in prediction of the recent EMC results. (orig.)

A new formulation of the relativistic many-body theory of electric dipole moments of closed shell atoms

International Nuclear Information System (INIS)

Latha, K V P; Angom, Dilip; Chaudhuri, Rajat K; Das, B P; Mukherjee, Debashis

2007-01-01

The electric dipole moments of closed-shell atoms are sensitive to the parity and time-reversal violating phenomena in the nucleus. The nuclear Schiff moment is one such property, it arises from the parity and time reversal violating quark-quark interactions and the quark-chromo electric dipole moments. We calculate the electric dipole moment of atomic 199 Hg arising from the nuclear Schiff moment using the relativistic coupled-cluster theory. This is the most accurate calculation of the quantity to date. Our calculations in combination with the experiment data provide important insights to the P and T violating coupling constants at the elementary particle level. In addition, a new limit on the tensor-pseudo tensor induced atomic EDM, calculated using the relativistic coupled-cluster theory is also presented

Two views on the Bjorken scenario for ultra-relativistic heavy-ion collisions

CERN Multimedia

Maire, Antonin

2011-01-01

The sketch describes the Bjorken scenario foreseen for the collision of ultra-relativistic heavy-ions, leading to the creation of strongly-interacting hot and dense deconfined matter, the so-called Quark-Gluon Plasma (QGP).

Classical relativistic constituent particles and composite-particle scattering

International Nuclear Information System (INIS)

King, M.J.

1984-01-01

A nonlocal Lagrangian formalism is developed to describe a classical many-particle system. The nonstandard Lagrangian is a function of a single parameter s which is not, in general, associated with the physical clock. The particles are constrained to be constituents of composite systems, which in turn can decompose into asymptotic composite states representing free observable particles. To demonstrate this, explicit models of composite-composite particle scattering are constructed. Space-time conservation laws are not imposed separately on the system, but follow upon requiring the constituents to ''pair up'' into free composites at s = +infinity,-infinity. One model is characterized by the appearance of an ''external'' zero-mass composite particle which participates in the scattering process without affecting the space-time conservation laws of the two-composite system. Initial conditions on the two incoming composite particles and the zero-mass participant determine the scattering angle and the final states of the two outgoing composite particles. Although the formalism is classical, the model displays some features usually associated with quantum field theory, such as particle scattering by means of constituent exchange, creation and annihilation of particles, and restriction of values of angular momentum

Observational Constraints on Quark Matter in Neutron Stars

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

We study the observational constraints of mass and redshift on the properties of the equation of state (EOS) for quark matter in compact stars based on the quasi-particle description. We discuss two scenarios: strange stars and hybrid stars. We construct the equations of state utilizing an extended MIT bag model taking the medium effect into account for quark matter and the relativistic mean field theory for hadron matter. We show that quark matter may exist in strange stars and in the interior of neutron stars. The bag constant is a key parameter that affects strongly the mass of strange stars. The medium effect can lead to the stiffer hybrid-star EOS approaching the pure hadronic EOS, due to the reduction of quark matter, and hence the existence of heavy hybrid stars. We find that a middle range coupling constant may be the best choice for the hybrid stars being compatible with the observational constraints.

Energy dissipation and charged particle production in heavy ion collisions

International Nuclear Information System (INIS)

Mishra, Aditya Nath; Sahoo, Raghunath; Sarkisyan Edward, K.G.; )

2013-01-01

In this paper, we use a model combining the constituent quark picture with Landau relativistic hydrodynamics. Within this model, the secondary particle production in nucleus-nucleus or nucleon-nucleon (p-barp/pp) collisions is basically driven by the amount of the initial effective energy deposited by participants (quarks or nucleons) into the Lorentz contracted overlap region

Study of stellar objects with strange quark matter crust

International Nuclear Information System (INIS)

Hothi, N.; Bisht, S.

2012-01-01

The absolute stability of strange quark matter is a viable possibility and immensely effects physics at the astrophysical scale. Relativistic heavy-ion reactions offer a stage to produce this exotic state of matter and the enhanced production of strange particles during these reactions can be studied within the framework of quark-gluon plasma (QGP). We have tried to investigate the role of strangeness under the compact star phenomenology. Emphasis is laid upon the possibility of existence of a third family of strange quark stars and its study help in revealing a number of unexplored features of the cosmos. Bag model parameters have been used to determine some integral parameters for a sequence of strange stars with crust and strange dwarfs constructed out of strange quark matter crust. A comparative analysis is performed between the strange and neutron stars and the strange and white dwarfs based upon these intrinsic parameters and paramount differences are observed. The intimacy between astrophysics and strange quarks depends strongly upon the strange quark matter hypothesis. It states that for a collection of more than a few hundred u, d and s quarks, the energy per baryon E/A of strange quark matter (SQM) can be well below the energy per baryon of the most stable atomic nuclei

Eleven lectures on the physics of the quark-gluon plasma

International Nuclear Information System (INIS)

McLerran, L.

1984-10-01

These lectures are intended to be an introduction to the physics of the quark-gluon plasma, and were presented at a workshop on The Physics of the Quark-Gluon Plasma held at Hua-Zhong Normal University in Wuhan, People's Republic of China in September, 1983. The lectures cover perturbation theory of the plasma at high temperature as well as the non-perturbative methods and results of lattice gauge theory computations. Physical models of the confinement-deconfinement phase transition and the modes of chiral symmetry breaking are presented. The possibility that a quark-gluon plasma might be produced in ultra-relativistic nuclear collisions is analyzed. Separate entries were prepared for the data base for the eleven lectures

Relativistic effects in decay of S-wave quarkoniums

International Nuclear Information System (INIS)

Martynenko, A.P.; Saleev, V.A.

1995-01-01

The width of S-wave quarkonium decays η c ,η b → γγ and J/ψ, Y → e + e - are calculated using the quasipotential approach. The nontrivial dependence of decay amplitude on relative quark momentum is considered. It is shown that relativistic corrections reach values of 30-50% in the processes studied

RELATIVISTIC HEAVY ION PHYSICS: A THEORETICAL OVERVIEW.

Energy Technology Data Exchange (ETDEWEB)

KHARZEEV,D.

2004-03-28

This is a mini-review of recent theoretical work in the field of relativistic heavy ion physics. The following topics are discussed initial conditions and the Color Glass Condensate; approach to thermalization and the hydrodynamic evolution; hard probes and the properties of the Quark-Gluon Plasma. Some of the unsolved problems and potentially promising directions for future research are listed as well.

Effect of phase transition on QGP fluid in ultra-relativistic heavy ion collision

International Nuclear Information System (INIS)

Nonaka, Chiho; Miyamura, Osamu; Muroya, Shin

2001-01-01

A full (3+1)-dimensional calculation using the Lagrangian hydrodynamics is proposed for relativistic nuclear collisions. The calculation enables us to evaluate anisotropic flow of hot and dense matter which appears in non-central and/or asymmetrical relativistic nuclear collisions. The relativistic hydrodynamical model is related to the equation of the state and the useful for the verification of quark-gluon plasma state. By virtue of the Lagrangian hydrodynamics we can easily trace the trajectory which corresponds to the adiabatic paths in the T-μ plane. We evaluate the directly of the influence of the phase transition to physical phenomena in the ultra-relativistic nuclear collisions. Using our relativistic hydrodynamical model, we discuss the effect of the phase transition on the collective flow. (author)

Extended particle model with quark confinement and charmonium spectroscopy

International Nuclear Information System (INIS)

Hasenfratz, Peter; Kuti, Julius; Szalay, A.S.

Extended particle like vector gluon bubbles /bags/ are introduced which are stabilized against free expansion by a surface tension of volume tension. Since quraks are coupled to the gluon field, they are confined to the inside of the gluon bag without any further mechanism. Only color singlet gluon bags are allowed. Nonlinear boundary conditions are not imposed on the quark field in the model. A massless abelian gauge confined by a surface tension is first considered; in a four-dimensional relativistic picture the surface of the gauge field bubble appears as a tube with a three dimensional surface. As a first application, the model is used to study bound states of heavy charmed quarks (charmonium). Similar to the Born-Oppenheimer approximation in molecular physics, heavy charmed quarks are treated as nonrelativistic in their motion whereas the gluon bag and light quarks (u,d,s) are treated in an adiabatic approximation

The quark gluon plasma

International Nuclear Information System (INIS)

Granier de Cassagnac, R.

2010-01-01

The quark-gluon plasma (QGP) is a state of matter in which the universe was expected to be a few micro-seconds after the big-bang. Violent collisions of heavy ions are supposed to re-create this state in particle accelerators. Numerous signatures of this fugacious state have already been observed at the RHIC (relativistic heavy ion collider). The first evidence of the violence of collisions is the number of generated particles: about 6000 per collision, mostly hadrons. This figure seems high but in fact is less than theoretically expected and is the first sign of the formation of a QGP that saturates the density of gluons. Another sign, observed at the RHIC is the damping of the particle jets that are produced in the collision. This damping is consistent with the crossing of a medium whose density is so high that it can not be made of hadrons but of partons. In the RHIC experiments the collective behaviour of quarks and gluons shows that they are strongly interacting with one another. This fact supports the idea that the QGP is more a perfect liquid rather than an ideal gas in which quarks and gluons move freely. (A.C.)

Why heavy and light quarks radiate energy with similar rates

International Nuclear Information System (INIS)

Kopeliovich, B. Z.; Potashnikova, I. K.; Schmidt, Ivan

2010-01-01

The dead-cone effect has been predicted to reduce the magnitude of energy loss and jet quenching for heavy flavors produced with large p T in heavy-ion collisions. On the contrary, data from the Relativistic Heavy Ion Collider demonstrate a strong suppression of high-p T electrons from charm and bottom decays. We show that vacuum radiation of a highly virtual quark produced at high p T with a stripped-off color field develops a much wider dead cone, which screens the one related to the quark mass. Lacking the field, gluons cannot be radiated within this cone until the color field is regenerated and the quark virtuality cools down to the scale of the order of the quark mass. However, this takes longer than is essential for the observed jet quenching, leading to similar nuclear effects for the light and charm quark jets. Open beauty is expected to radiate much less within the p T range studied so far in heavy-ion collisions.

Relativistic few body calculations

International Nuclear Information System (INIS)

Gross, F.

1988-01-01

A modern treatment of the nuclear few-body problem must take into account both the quark structure of baryons and mesons, which should be important at short range, and the relativistic exchange of mesons, which describes the long range, peripheral interactions. A way to model both of these aspects is described. The long range, peripheral interactions are calculated using the spectator model, a general approach in which the spectators to nucleon interactions are put on their mass-shell. Recent numerical results for a relativistic OBE model of the NN interaction, obtained by solving a relativistic equation with one-particle on mass-shell, will be presented and discussed. Two meson exchange models, one with only four mesons (π,σ,/rho/,ω) but with a 25% admixture of γ 5 coupling for the pion, and a second with six mesons (π,σ,/rho/,ω,δ,/eta/) but pure γ 5 γ/sup μ/ pion coupling, are shown to give very good quantitative fits to the NN scattering phase shifts below 400 MeV, and also a good description of the /rvec p/ 40 Ca elastic scattering observables. Applications of this model to electromagnetic interactions of the two body system, with emphasis on the determination of relativistic current operators consistent with the dynamics and the exact treatment of current conservation in the presence of phenomenological form factors, will be described. 18 refs., 8 figs

Methods in relativistic nuclear physics

International Nuclear Information System (INIS)

Danos, M.; Gillet, V.; Cauvin, M.

1984-01-01

This book is intended to provide the methods and tools for performing actual calculations for finite many-body systems of bound relativistic constituent particles. The aim is to cover thoroughly the methodological aspects of the relativistic many-body problem for bound states while avoiding the presentation of specific models. The many examples contained in the later part of the work are meant to give concrete illustrations of how to actually apply the methods which are given in the first part. The basic framework of the approach is the lagrangian field theory solved in the time-independent Schroedinger picture. (Auth.)

Helicity and isospin asymmetries in the electroproduction of nucleon resonances

International Nuclear Information System (INIS)

Warns, M.; Pfeil, W.; Rollnik, H.

1989-10-01

We investigate the helicity asymmetries and isospin ratios of ratiative transition amplitudes for nucleon resonances electroproduced off proton and neutron targets at momentum transfers of Q 2 ≤3 GeV 2 . Calculations were done in the framework of a relativized constituent quark model which includes many-body effects due to the quark interaction potential and to a relativistic treatment of the center-of-mass motion of the three quark system. We find significant deviations from the predictions of the nonrelativistic quark models and the SU(6) W algebraic approach based on the single quark transition hypothesis. Our calculated relativistic corrections lead to an overall better agreement with the experimental data. The question if some of the low-lying P-wave baryons are of hermaphrodite nature is briefly discussed. Finally we analyse the electroexcitation of the missing [20,1 + ] P-wave resonances. (orig.)

Photon production in relativistic nuclear collisions at SPS and RHIC energies

CERN Document Server

Turbide, S; Rapp, R; 10.1142/S0217751X0402258X

2004-01-01

Chiral Lagrangians are used to compute the production rate of photons from the hadronic phase of relativistic nuclear collisions. Special attention is paid to the role of the a/sub 1/ pseudovector. Calculations that include strange meson reactions, form factors, the use of consistent vector spectral densities, the emission from a quark-gluon plasma, and primordial nucleon-nucleon collisions reproduce the photon spectra measured at the Super Proton Synchrotron (SPS). Some predictions for the Relativistic Heavy Ion Collider (RHIC) are made.

Electron-muon correlation as a new probe of strongly interacting quark-gluon plasma

International Nuclear Information System (INIS)

Akamatsu, Yukinao; Hatsuda, Tetsuo; Hirano, Tetsufumi

2009-01-01

As a new and clean probe to the strongly interacting quark-gluon plasma (sQGP), we propose an azimuthal correlation of an electron and a muon that originate from the semileptonic decay of charm and bottom quarks. By solving the Langevin equation for the heavy quarks under the hydrodynamic evolution of the hot plasma, we show that substantial quenching of the away-side peak in the electron-muon correlation can be seen if the sQGP drag force acting on heavy quarks is large enough as suggested from the gauge/gravity correspondence. The effect could be detected in high-energy heavy ion collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

Effects of delta degrees of freedom on quark condensate in hot and dense matter

International Nuclear Information System (INIS)

Li Lei; Ning Pingzhi

1996-01-01

The relativistic mean-field theory is applied to study the quark condensate systematically in nuclear matter at zero and finite temperature in terms of the relative importance of delta degrees of freedom. Calculations have included the high-order contributions to quark condensate in nuclear medium due to the baryon-baryon interactions. Numerical results are presented for the nuclear density up to five times larger than the normal density and temperature up to 120 MeV. It is found that the delta resonance in nuclear matter can cause substantial decreases to in-medium quark condensate

More sum rules for quark and lepton masses

International Nuclear Information System (INIS)

Terazawa, Hidezumi.

1990-04-01

Sum rules for quark and lepton masses are derived from the Ward identity of Chanowitz and Ellis for the vertex function of the trace of the energy-momentum tensor and the two axial-vector currents and the partially conserved axial-vector current hypothesis. They indicate, among other things, that the constituent quark masses of u and d and those of the techniquarks, if any, are about 300 MeV and 300 GeV, respectively. (author)

Relativistic quarkonium dynamics

International Nuclear Information System (INIS)

Sazdjian, H.

1985-06-01

We present, in the framework of relativistic quantum mechanics of two interacting particles, a general model for quarkonium systems satisfying the following four requirements: confinement, spontaneous breakdown of chiral symmetry, soft explicit chiral symmetry breaking, short distance interactions of the vector type. The model is characterized by two arbitrary scalar functions entering in the large and short distance interaction potentials, respectively. Using relationships with corresponding quantities of the Bethe-Salpeter equation, we also present the normalization condition of the wave functions, as well as the expressions of the meson decay coupling constants. The quark masses appear in this model as free parameters

Vector and Axial-Vector Correlators in AN Instanton-Like Quark Model

Science.gov (United States)

Dorokhov, Alexander E.

The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instanton-like quark-quark interaction. This function describes the transition between the high energy asymptotically free region of almost massless current quarks to the low energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic τ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, aμ hvp(1), is estimated.

Problems of describing the cumulative effect in relativistic nuclear physics

International Nuclear Information System (INIS)

Baldin, A.M.

1979-01-01

The problem of describing the cumulative effect i.e., the particle production on nuclei in the range kinematically forbidden for one-nucleon collisions, is studied. Discrimination of events containing cumulative particles fixes configurations in the wave function of a nucleus, when several nucleons are closely spaced and their quark-parton components are collectivized. For the cumulative processes under consideration large distances between quarks are very important. The fundamental facts and theoretical interpretation of the quantum field theory and of the condensed media theory in the relativistic nuclear physics are presented in brief. The collisions of the relativistic nuclei with low momentum transfers is considered in a fast moving coordinate system. The basic parameter determining this type of collisions is the energy of nucleon binding in nuclei. It has been shown that the short-range correlation model provides a good presentation of many characteristics of the multiple particle production and it may be regarded as an approximate universal property of hadron interactions

Interquark potential with finite quark mass from lattice QCD.

Science.gov (United States)

Kawanai, Taichi; Sasaki, Shoichi

2011-08-26

We present an investigation of the interquark potential determined from the q ̄q Bethe-Salpeter (BS) amplitude for heavy quarkonia in lattice QCD. The q ̄q potential at finite quark mass m(q) can be calculated from the equal-time and Coulomb gauge BS amplitude through the effective Schrödinger equation. The definition of the potential itself requires information about a kinetic mass of the quark. We then propose a self-consistent determination of the quark kinetic mass on the same footing. To verify the proposed method, we perform quenched lattice QCD simulations with a relativistic heavy-quark action at a lattice cutoff of 1/a≈2.1  GeV in a range 1.0≤m(q)≤3.6 GeV. Our numerical results show that the q ̄q potential in the m(q)→∞ limit is fairly consistent with the conventional one obtained from Wilson loops. The quark-mass dependence of the q ̄q potential and the spin-spin potential are also examined. © 2011 American Physical Society

Heavy quark photoproduction in ultraperipheral heavy ion collisions

International Nuclear Information System (INIS)

Klein, Spencer R.; Nystrand, Joakim; Vogt, Ramona

2002-01-01

Heavy quarks are copiously produced in ultraperipheral heavy ion collisions. In the strong electromagnetic fields, cc-bar and bb-bar are produced by photonuclear and two-photon interactions. Hadroproduction can also occur in grazing interactions. We calculate the total cross sections and the quark transverse momentum and rapidity distributions, as well as the QQ-bar invariant mass spectra from the three production channels. We consider AA and pA collisions at the Relativistic Heavy Ion Collider and the Large Hadron Collider. We discuss techniques for separating the three processes and describe how the AA to pA production ratios might be measured accurately enough to study nuclear shadowing

High energy cosmic ray signature of quark nuggets

Science.gov (United States)

Audouze, J.; Schaeffer, R.; Silk, J.

1985-01-01

It has been recently proposed that dark matter in the Universe might consist of nuggets of quarks which populate the nuclear desert between nucleons and neutron star matter. It is further suggested that the Centauro events which could be the signature of particles with atomic mass A approx. 100 and energy E approx. 10 to 15th power eV might also be related to debris produced in the encounter of two neutron stars. A further consequence of the former proposal is examined, and it is shown that the production of relativistic quark nuggets is accompanied by a substantial flux of potentially observable high energy neutrinos.

Relativistic mechanics of two interacting particles and bilocal theory

International Nuclear Information System (INIS)

Takabayasi, Takehiko

1975-01-01

New relativistic mechanics of two-particle system is set forth, where the two constituent particles are interacting by an arbitrary (central) action-at-a-distance. The fundamental equations are presented in a form covariant under general transformation of parameters parametrizing the world lines of constituent particles. The theory represents the proper relativistic generalization of the usual Newtonian mechanics in the sense that it tends in the non-relativistic (and weak interaction) limit to the usual mechanics of two particles moving under a corresponding non-relativistic potential. For the analysis of theory it is convenient to choose a certain particular gauge (i.e., parametrization) fixed by two gauge relations. This brings the theory to a canonical formalism accompanied by two weak equations, and in this gauge quantization can be performed. The result verifies that the relativistic quantum mechanics for two particles interacting by an action-at-a-distance is just represented by a bilocal wave equation and a subsidiary condition, with the clarification of its correspondence-theoretical foundation and internal dynamics. As an example the case of Hooke-type force is illustrated, where the internal motions are elliptic oscillations in the center-of-mass frame. Its quantum theory just reproduces the original form of bilocal theory giving bound states lying on a straightly rising trajectory and on its daughter trajectories. (auth.)

The penta-quark: a new kind of elementary particle?

International Nuclear Information System (INIS)

Goeke, K.; Praszatowicz, M.

2005-01-01

The discovery of the exotic Θ + with minimal quark structure uudds-bar may provide a sensation since, if confirmed, it is the first baryonic particle that cannot be composed of three quarks. The chiral quark soliton description of baryons has predicted the mass and an upper limit for the decay width of this particle prior to the experiments and in agreement with the present data. The model corresponds to a relativistic mean field description of the nucleon, where the quarks move in a self-consistent mean field of pionic and kaonic character. It uses an effective chiral Lagrangian based on spontaneously broken chiral symmetry of the QCD. In a natural way the chiral quark soliton model describes the well known lowest two multiplets (8, 1 + /2), (10, 3 + /2) and it predicts two more exotic particles being members of an anti-decuplet (10-bar, 1 + /2) consisting of penta-quarks. The very narrow width of the Θ + can be explained by the small overlap of the 5-quark light cone wave function of the Θ + with the small 5-quark light cone component of the wave function of the nucleon. If confirmed, Θ + will not only be a new kind of subatomic particle but will seriously influence our understanding of the structure of ordinary nucleons. (authors)

Quark self-energy beyond the mean field at finite temperature

International Nuclear Information System (INIS)

Zhuang, P.

1995-01-01

The Nambu--Jona-Lasinio model, an effective low-energy model of QCD, is extended to the next to the leading order in the 1/N c expansion at finite temperature and density. The contributions to the quark self-energy and the constituent quark mass from the meson dressing are considered in a perturbative approach about the mean field. In particular, the temperature dependence of the quark mass is shown numerically at zero chemical potential. The correction to the quark mass from the meson dressing amounts to 20% compared to the result of the leading order at low temperature, and rapidly approaches zero at high temperature

Quarks and gluons in nuclear and particle physics

International Nuclear Information System (INIS)

Van Hove, L.

1988-01-01

This paper provides a broad overview of strong interactions, or nuclear forces, as ones understanding has expanded over the past 25 years. The major particles and models are briefly touched upon. The author expands upon the field theories which have evolved to explain the experimental work, and the present model of quarks and gluons which form the components of hadrons. The standard model has been very successful in explaining much of the newly acquired experimental data. But the property of confinement, where the partons, (quarks and gluons), are not observed seperately has precluded observation of these particles. He touches on the manifestation of these particles in high energy physics, where they model the observed particles and resonances, and are responsible for the production of hadronic jets. However in nuclear physics, one does not need to postulate the existance of these particles to explain the properties of nuclei, until one deals with interaction energies in the range of GeV. The author then touches on the area of ultra-relativistic nuclear physics, where the partons must play a role in the effects which are observed. In particular he discusses deep inelastic lepton scattering on nuclei, the Drell-Yan process in nuclei, and ultra-relativistic nuclear collisions. Finally he gives a brief discussion of the quark-gluon plasma, which is postulated to form during very high energy collisions, manifesting itself as a brief deconfinement of the partons into an equilibrium plasma

Meson spectroscopy, quark mixing and quantum chromodynamics

International Nuclear Information System (INIS)

Filippov, A.T.

1979-01-01

A semiphenomenological theory of mass spectrum for mesons, consisting of a quark-antiquark pair, is presented. Relativistic kinematical effects of the quark mass differences, the SU(3)-symmetry breaking in slopes of the Regge trajectories and in radially excited states are taken into account. The OZI-rule breaking is taken into account by means of the mixing matrix for the quark wave functions, whose form is suggested by the quantum chromodynamics. A simple extrapolation of expression, given by the quantum chromodynamics from the ''asymptotic freedom'' region to the ''infrared slavery'' region is proposed to describe the dependence of the mixing parameters on the meson masses. To calculate masses and mixing angles for pseudoscalar mesons a condition is proposed that the pion mass is minimal. In this situation the eta-meson mass is near the maximal value. The predictions of the theory for masses and mixing angles of the mesons are in good agreement with the experiment

Shock wave produced by hadron-quark phase transition in neutron star

Energy Technology Data Exchange (ETDEWEB)

Gustavo de Almeida, Luis, E-mail: lgalmeida@cbpf.br [Universidade Federal do Acre – Campus Floresta, Estrada do Canela Fina, km 12, CEP 69980-000, Cruzeiro do Sul, AC (Brazil); Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, CEP 22290-180, Rio de Janeiro, RJ (Brazil); Duarte, Sérgio José Barbosa, E-mail: sbd@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, CEP 22290-180, Rio de Janeiro, RJ (Brazil); Rodrigues, Hilário, E-mail: harg.astrophys@gmail.com [Centro Federal de Educação Tecnológica Celso Suckow da Fonseca Av. Maracanã, 229, CEP 20271-110, Rio de Janeiro, RJ (Brazil)

2015-12-17

In this work we present a schematic description of the detonation wave in hadronic matter inside a neutron star core. We have used a simplified two shells model where the inner shell medium is initially composed of a small lump of strange quark matter surrounded by a large outer shell composed of hadronic matter. We have utilized an equation of state (EOS) based on Relativistic Mean Field Theory with the parameter set NL3 to describe the nuclear and subnuclear phases. We use the MIT bag model to describe the strange quark matter. The hadron-quark phase transition actually induces highly non equilibrium modes, which may become a detonation process (faster) or a burning process (slower). The main purpose of the work is to study the formation of a remnant quark star and the possibility of mass ejection caused by the hadron-quark phase transition. We have found that the total amount of ejected mass is dependant of the bag constant utilized in the strange matter description.

Messung der Produktion von aus leichten Quarks zusammengesetzten Hadronen und Anti-Kernen am Large Hadron Collider

CERN Document Server

Kalweit, Alexander; Wambach, Jochen

With the recording of the first collisions of the Large Hadron Collider (LHC) in November 2009, a new era in the domain of high energy and relativistic heavy-ion physics has started. As one of the early observables which can be addressed, the measurement of light quark flavor production is presented in this thesis. Hadrons that consist only of u, d, and s quarks constitute the majority of the produced particles in pp and Pb–Pb collisions. Their measurement forms the basis for a detailed understanding of the collision and for the answer of the question if hadronic matter undergoes a phase transition to the deconfined quark-gluon plasma at high temperatures. The basics of ultra-relativistic heavyion physics are briefly introduced in the first chapter followed by a short description of the ALICE experiment. A particular focus is put on the unique particle identification (PID) capabilities as they provide the basis of the measurements which are presented in the following chapters. The particle identification vi...

π-π scattering in a consistent relativistic quark model

International Nuclear Information System (INIS)

Micu, L.

1977-12-01

Introducing the expression of the interpolating field of a pion as a product of suitable modified free quark fields and of a scalar unquantified field into the LSZ formalism one deduces the vanishing of the exotic amplitudes and of the π-π scattering lengths. The asymptotic vanishing of the elastic π - π scattering amplitude may also be obtained under special requirements. (author)

Broken superfluid in dense quark matter

Energy Technology Data Exchange (ETDEWEB)

Parganlija, Denis; Schmitt, Andreas [Institut fuer Theoretische Physik, Technische Universitaet Wien, 1040 Vienna (Austria); Alford, Mark [Department of Physics, Washington University St Louis, MO, 63130 (United States)

2014-07-01

Quark matter at high densities is a superfluid. Properties of the superfluid become highly non-trivial if the effects of strange-quark mass and the weak interactions are considered. These properties are relevant for a microscopic description of compact stars. We discuss the effect of a (small) explicitly symmetry-breaking term on the properties of a zero-temperature superfluid in a relativistic φ{sup 4} theory. If the U(1) symmetry is exact, chemical potential and superflow can be equivalently introduced either via (1) a background gauge field or (2) a topologically nontrivial mode. However, in the case of the explicitly broken symmetry, we demonstrate that the scenarios (1) and (2) lead to quantitatively different results for the mass of the pseudo-Goldstone mode and the critical velocity for superfluidity.

Heavy Quark Dynamics toward thermalization: RAA, υ1, υ2, υ3

Directory of Open Access Journals (Sweden)

Plumari Salvatore

2018-01-01

Full Text Available We describe the propagation of Heavy quarks (HQs in the quark-gluon plasma (QGP within a relativistic Boltzmann transport (RBT approach. The interaction between heavy quarks and light quarks is described within quasi-particle approach which is able to catch the main features of non-perturbative interaction as the increasing of the interaction in the region of low temperature near TC. In our calculations the hadronization of charm quarks in D mesons is described by mean of an hybrid model of coalescence plus fragmentation. We show that the coalescence play a key role to get a good description of the experimental data for the nuclear suppression factor RAA and the elliptic flow υ2(pT at both RHIC and LHC energies. Moreover, we show some recent results on the direct flow υ1 and triangular flow υ3 of D meson.

''Follow that quark!'' (and other exclusive stories)

International Nuclear Information System (INIS)

Carroll, A.S.

1987-01-01

Quarks are considered to be the basic constituents of matter. In a series of recent experiments, Carroll studied exclusive reactions as a means of determining the interactions between quarks. Quantum Chromo-dynamics (QCD) is the modern theory of the interaction of quarks. This theory explains how quarks are held together via the strong interaction in particles known as hadrons. Hadrons consisting of three quarks are called baryons. Hadrons made up of a quark and an antiquark are called mesons. In his lecture, Carroll describes what happens when two hadrons collide and scatter to large angles. The violence of the collision causes the gluons that bind the quarks in a particular hadron to temporarily lose their grip on particular quarks. Quarks scramble toward renewed unity with other quarks, and they undergo rearrangement, which generally results in additional new particles. A two-body exclusive reaction has occurred when the same number of particles exist before and after the collisions. At large angles these exclusive reactions are very rare. The labels on the quarks known as flavor enable the experimenter to follow the history of individual quarks in detail during these exclusive reactions. Carroll describes the equipment used in the experiment to measure short distance, hard collisions at large angles. The collisions he discusses occur when a known beam of mesons or protons collide with a stationary proton target. Finally, Carroll summarizes what the experiments have shown from the study of exclusive reactions and what light some of their results shed on the theory of QCD

Simulations of non-relativistic quantum chromodynamics at strong and weak coupling

Science.gov (United States)

Shakespeare, Norman Harold

In this thesis heavy quarks are investigated using lattice nonrelativistic quantum chromodynamics (NRQCD). Two major research works are presented. In the first major work, simulations are done for the three quarkonium systems cc¯, bc¯, and bb¯. The hyperfine splittings are computed at both leading and next-to-leading order in the relativistic expansion, using a large number of lattice spacings. A detailed comparison between mean-link and average plaquette tadpole renormalization schemes is undertaken with a number of features favouring the use of mean-links. These include much better scaling behavior of the hyperfine splittings and smaller relativistic corrections to the spin splittings. Signs of a breakdown in the NRQCD expansion are seen when the bare quark mass, in lattice units, falls below about one. In the second work, coefficients for the perturbative expansion of the static quark self energy are extracted from Monte Carlo simulations in the perturbative region of lattice quantum chromodynamics (QCD). A very large systematic study resulted in a major extension of existing methods. Twisted boundary conditions are used to eliminate the effects of zero modes and to suppress tunneling between the degenerate Z3 vacua. The Monte Carlo results are in excellent agreement with analytic perturbation theory, which is known through second order. New results for the third order coefficient are reported. Preliminary work is reported on quark propagators which will be used to measure second order mass renormalizations for NRQCD fermions.

Relativistic actions for bound-states and applications in the meson spectroscopy

International Nuclear Information System (INIS)

Silva Carvalho, Hendly da.

1991-08-01

We study relativistic equations for bound states of two-body systems using Dirac's constraint formalism and supersymmetry. The two-body system can be of spinless particles, one of them spinning and the other one spinless, or both of them spinning. The interaction is described by scalar, timelike four-vector and spacelike four-vector potentials under Lorentz transformations. As an application we use the relativistic wave equation for two scalar particles and calculate the mass spectra of the mesons treating them as spinless quark-antiquark bound states. The interaction potential in this case is a convenient adaptation of the potential employed in non-relativistic calculations. Finally, we compare our results with more recent experimental data and with theoretical results obtained with the same potential used by us but with a non-relativistic wave equation. We also compare our results with results obtained with the relativistic wave equation but with a different interaction potential. (author). 38 refs, 9 figs, 8 tabs

Phase transition in dense nuclear matter with quark and gluon condensates

International Nuclear Information System (INIS)

Ellis, J.; Kapusta, J.I.; Olive, K.A.

1991-01-01

Nuclear matter is expected to modify the expectation values of the quark and gluon condensates. We utilize the chiral and scale symmetries of QCD to describe the interaction between these condensates and hadrons. We solve the resulting equations self-consistently in the relativistic mean field approximation. In order that these QCD condensates be driven towards zero at high density their coupling to sigma and vector mesons must be such that the masses of these mesons do not decrease with density. In this case a physically sensible phase transition to quark matter ensures. (orig.)

Quark-antiquark bound-state spectroscopy and QCD

International Nuclear Information System (INIS)

Bloom, E.D.

1982-11-01

The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n 3 S 1 states, the center of gravity of the masses of the n 3 P; states, n 3 P; fine structure and classification, branching ratios for upsilon' → tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top

Covariant introduction of quark spin into the dual resonance model

International Nuclear Information System (INIS)

Iroshnikov, G.S.

1979-01-01

A very simple method of insertion of a quark spin into the dual resonance model of hadron interaction is proposed. The method is suitable for amplitudes with an arbitrary number of particles. The amplitude of interaction of real particles is presented as a product of contribution of oscillatory excitations in the (q anti q) system and of a spin factor. The latter is equal to the trace of the product of the external particle wave functions constructed from structural quarks and satisfying the relativistic Bargman-Wigner equations. Two examples of calculating the meson interaction amplitudes are presented

Jets in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Wang, Xin-Nian; Gyulassy, M.

1990-09-01

Several aspects of hard and semihard QCD jets in relativistic heavy ion collisions are discussed, including multiproduction of minijets and the interaction of a jet with dense nuclear matter. The reduction of jet quenching effect in deconfined phase of nuclear matter is speculated to provide a signature of the formation of quark gluon plasma. HIJING Monte Carlo program which can simulate events of jets production and quenching in heavy ion collisions is briefly described. 35 refs., 13 figs

Relativistic continuum physics for the description of heavy ion collisions

International Nuclear Information System (INIS)

Lukacs, Bela

1986-01-01

The application of relativistic continuum physics to the description of the nuclear fireball evolution from the start of expansion to the breaking is discussed. The basic formalism and basic assumptions of relativistic hydrodynamics and thermodynamics are analyzed in detail. The four basic assumptions are not valid in the case of nuclear fireball produced in heavy ion collisions, but thermodynamics can be extended in different ways to incorporate anisotropy, fluctuations, gradients and the lack of the local equilibrium. The extended continuum formalism is applicable to the description of the nuclear fireball dynamics, including the nuclear - quark matter phase transition. (D.Gy.)

Meson Spectroscopy in the Light Quark Sector

Science.gov (United States)

De Vita, R.

2014-03-01

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 qbar q configuration as tetraquarks (qqoverline{qq}), hybrids (qbar qg) 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 qbar 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+e- annihilation, pbar p annihilation, pion scattering, proton-proton scattering and photo-production, to produce meson states. This intense effort is

Relativistic description of quark-antiquark bound states. II. Spin-dependent treatment

International Nuclear Information System (INIS)

Gara, A.; Durand, B.; Durand, L.

1990-01-01

We present the results of a study of light- and heavy-quark--antiquark bound states in the context of the reduced Bethe-Salpeter equation, including the full spin dependence. We obtain good fits to the observed spin splittings in the b bar b and c bar c systems using a short-distance single-gluon-exchange interaction, and a long-distance scalar confining interaction. However, we cannot obtain satisfactory fits to the centers of gravity of the b bar b and c bar c spin multiplets at the same time, and the splittings calculated for q bar Q mesons containing the lighter quarks are very poor. The difficulty appears to be intrinsic to the reduced Salpeter equation for reasons which we discuss

Heavy quark symmetry at large recoil: The case of baryons

International Nuclear Information System (INIS)

Koerner, J.G.; Kroll, P.

1992-02-01

We analyze the large recoil behaviour of heavy baryon transition form factors in semi-leptonic decays. We use a generalized Brodsky-Lepage hard scattering formalism where diquarks are considered as quasi-elementary constituents of baryons. In the limit of infinitely heavy quark masses the large recoil form factors exhibit a new model-independent heavy quark symmetry which is reminiscent but not identical to the Isgur-Wise symmetry at low recoil. (orig.)

Baryons and ladders

International Nuclear Information System (INIS)

Ball, R.D.

1990-01-01

By formal manipulation of the QCD functional integral we arrive at a relativistic low energy effective theory of non-local color singlet mesons and baryons, which at tree level sums up ladders of effective glue exchange between constituent quarks. (orig.)

On the axial charge gsub(A) and the quark confinement in nucleons

International Nuclear Information System (INIS)

Tegen, R.

1986-01-01

Calculations are presented of the axial charge gsub(A) in models where relativistic quarks are confined by arbitrary vector potentials, scalar potentials proportionalrsup(n) and scalar-vector potentials proportional1/2(1+γ 0 )rsup(n) for arbitrary n>=0. It is shown that gsub(A) vanishes for all vector potentials and is a monotonically decreasing function of the exponent n for scalar and scalar-vector potentials. The non-relativistic value 5/3 is reproduced (for n=0) as well as the MIT bag model value 1.09 (for n->infinite); they are upper and lower limits of gsub(A), respectively. This function gsub(A)(n) is shown not to depend on the quark confinement size (i.e. gsub(A) is scale invariant), but only depends on the type of confinement (scalar, vector). Acceptable values for gsub(A) are found with nsub(s) =2-3 (scalar) and nsub(s-v)=0.5-0.7 (scalar-vector). (orig.)

Quark-Meson-Coupling (QMC) model for finite nuclei, nuclear matter and beyond

Science.gov (United States)

Guichon, P. A. M.; Stone, J. R.; Thomas, A. W.

2018-05-01

The Quark-Meson-Coupling model, which self-consistently relates the dynamics of the internal quark structure of a hadron to the relativistic mean fields arising in nuclear matter, provides a natural explanation to many open questions in low energy nuclear physics, including the origin of many-body nuclear forces and their saturation, the spin-orbit interaction and properties of hadronic matter at a wide range of densities up to those occurring in the cores of neutron stars. Here we focus on four aspects of the model (i) a full comprehensive survey of the theory, including the latest developments, (ii) extensive application of the model to ground state properties of finite nuclei and hypernuclei, with a discussion of similarities and differences between the QMC and Skyrme energy density functionals, (iii) equilibrium conditions and composition of hadronic matter in cold and warm neutron stars and their comparison with the outcome of relativistic mean-field theories and, (iv) tests of the fundamental idea that hadron structure changes in-medium.

FONLL calculations for heavy quark production in nuclear collisions

CERN Document Server

Niel, Elisabeth Maria

2017-01-01

The ALICE detector at the LHC has been designed to study the collisions of heavy nuclei at energies much higher then the previous dedicated experiments at the Relativistic Heavy-Ion Collider (RHIC) of the Brookhaven National Laboratory. Colliding heavy nuclei allows to reproduce the hot and dense plasma of quarks and gluons (QGP) existing right after the Big Bang and hence study the very first instants of universe’s existence. In heavy ions collisions, heavy flavours, such as beauty and charm quark, are fundamental probes for the quark gluon plasma properties. That is because they experience the entire evolution of the system since they are produced at the very beginning. They are indeed a very powerful tool to test field theories such as Quantum Chromodynamics (QCD). Theoretical models predict that a fast parton(quark or gluon) looses energy while traversing a medium composed of colour charges. This phenomenon is called "jet quenching", it can be used to describe the QGP. It was first observed at RHIC by m...

Two photon correlation in anisotropic quark-gluon plasma (aQGP)

International Nuclear Information System (INIS)

Mohanty, Payal; Mandal, Mahatsab; Roy, Pradip K.

2013-01-01

The prime objective of heavy ion collision (HIC) at relativistic energy is to create and explore the properties of novel state of partonic matter, known as Quark Gluon Plasma (QGP). The only way to obtain the space-time structure of HIC is through the study of two-particle momentum correlations, commonly known as Hanbury-Brown-Twiss (HBT) interferometry

Magnetic moments of confined quarks and baryons in an independent-quark model based on Dirac equation with power-law potential

International Nuclear Information System (INIS)

Barik, N.; Das, M.

1983-01-01

The effect of confinement on the magnetic moment of a quark has been studied in a simple independent-quark model based on the Dirac equation with a power-law potential. The magnetic moments so obtained for the constituent quarks, which are found to be significantly different from their corresponding Dirac moments, are used in predicting the magnetic moments of baryons in the nucleon octet as well as those in the charmed and b-flavored sectors. We not only get an improved result for the proton magnetic moment, but the calculation for the rest of the nucleon octet also turns out to be in reasonable agreement with experiment. The overall predictions for the charmed and b-flavored baryons are also comparable with other model predictions

Quark-antiquark bound-state spectroscopy and QCD

Energy Technology Data Exchange (ETDEWEB)

Bloom, E.D.

1982-11-01

The discussion covers quarks as we know them, the classification of ordinary mesons in terms of constituent quarks, hidden charm states and charmed mesons, bottom quarks, positronium as a model for quarti q, quantum chromodynamics and its foundation in experiment, the charmonium model, the mass of states, fine structure and hyperfine structure, classification, widths of states, rate and multipolarity of gamma transitions, questions about bottom, leptonic widths and the determination of Q/sub b/, the mass splitting of the n/sup 3/S/sub 1/ states, the center of gravity of the masses of the n/sup 3/P; states, n/sup 3/ P; fine structure and classification, branching ratios for upsilon' ..-->.. tau chi/sub 6j/ and the tau cascade reactions, hyperfine splitting, and top. (GHT)

The strongly coupled quark-gluon plasma created at RHIC

International Nuclear Information System (INIS)

Heinz, Ulrich

2009-01-01

The relativistic heavy-ion collider (RHIC) was built to re-create and study in the laboratory the extremely hot and dense matter that filled our entire universe during its first few microseconds. Its operation since June 2000 has been extremely successful, and the four large RHIC experiments have produced an impressive body of data which indeed provide compelling evidence for the formation of thermally equilibrated matter at unprecedented temperatures and energy densities-a 'quark-gluon plasma (QGP)'. A surprise has been the discovery that this plasma behaves like an almost perfect fluid, with extremely low viscosity. Theorists had expected a weakly interacting gas of quarks and gluons, but instead we seem to have created a strongly coupled plasma liquid. The experimental evidence strongly relies on a feature called 'elliptic flow' in off-central collisions, with additional support from other observations. This paper explains how we probe the strongly coupled QGP, describes the ideas and measurements which led to the conclusion that the QGP is an almost perfect liquid, and shows how they tie relativistic heavy-ion physics into other burgeoning fields of modern physics, such as strongly coupled Coulomb plasmas, ultracold systems of trapped atoms and superstring theory

Another comment on 'relativistic description of quark-antiquark bound states'

International Nuclear Information System (INIS)

Lucha, W.; Rupprecht, H.; Schoeberl, F.F.

1991-04-01

We point out some ambiguities in the treatment of fermion-antifermion bound states by solving the reduced Salpeter equation in coordinate space. Our observations allow to cast some doubt on the validity of the conclusion of Gara et al. that moving from a nonrelativistic to a relativistic description makes things worse. (authors)

Riemann problems and their application to ultra-relativistic heavy ion collisions

International Nuclear Information System (INIS)

Plohr, B.J.; Sharp, D.H.

1986-07-01

Heavy ion collisions at sufficiently high energies to form quark-gluon plasma are considered. The phase transformation from a quark-gluon phase to hadrons as the nuclear matter cools is modeled as a hydrodynamical flow. Nonlinear waves are the predominant feature of this type of flow and the Riemann problem of a relativistic gas undergoing a phase transformation is explored as a method to numerically model this phase transition process in nuclear matter. The solution of the Riemann problem is outlined and results of preliminary numerical computations of the flow are presented. 10 refs., 2 figs

Measurement of the top-quark mass from the b jet energy spectrum

CERN Document Server

CMS Collaboration

2015-01-01

The top-quark mass is measured using the peak position of the energy distribution of b jets produced from top-quark decays. The analysis is based on a recent theoretical proposal. The measurement is carried out selecting $\\mathrm{t\\overline{t}}$ events with one electron and one muon in the final state in proton-proton collision data at $\\sqrt{s}=8~\\mathrm{TeV}$, corresponding to an integrated luminosity of 19.7$~\\mathrm{fb}^{-1}$. The fitted peak position of the observed energy distribution is calibrated using simulated events and translated to a top-quark mass measurement using relativistic kinematics, with the result $m_{\\mathrm{t}}=172.29\\pm1.17\\,(\\mathrm{stat.})\\pm2.66\\,(\\mathrm{syst.})~\\mathrm{GeV}$.

Searches for baryons with multiple heavy quarks at LHCb

CERN Multimedia

CERN. Geneva

2017-01-01

Hadrons are systems bound by the strong interaction, which is described at the fundamental level by quantum chromodynamics (QCD). While QCD is well understood at high energy in the perturbative regime, low-energy phenomena, such as the binding of quarks and gluons within hadrons, are more difficult to predict. High precision measurements are then of paramount importance to test the reliability of several models and computational techniques, such as constituent-quark models or lattice-QCD calculations, in predicting the mass spectrum and the properties of hadrons. Owing to its excellent capabilities with particle identification, tracking and vertex reconstruction, LHCb is in a unique position to make significant contributions to the sector of particle spectroscopy. For example, five narrow structures have been recently observed in the $\\Xi_c^+K^-$ mass spectrum, consistent with excited $\\Omega_c^{0}$ states, composed of a charm quark and two strange quarks. Despite the fact that the quark model predicts the ex...

Remarks on electromagnetic form factors of hadrons in the quark model

International Nuclear Information System (INIS)

Vainshtein, A.I.; Zakharov, V.I.

1977-01-01

Relations between the transversal and longitudinal parts of elastic and quasielastic form factors are studied within the quark model. It is shown that for an even number of the constituent quarks the longitudinal part dominates while for an odd number the transversal part is the largest one. Consequences form this result are considered for deuteron form factor and for matrix elements of the electromagnetic transitions between π, rho, A 1 mesons

Big Bang to Little Bang ---- Study of Quark-Gluon Plasma

Indian Academy of Sciences (India)

Tapan K. Nayak

2013-07-05

Jul 5, 2013 ... ... compressed into a space billions of times smaller than a proton. ... Quarks in neutron/proton. • Range 10. -13 cm ... Structure of an atom… …separate constituents nucleus electron .... HIGHEST MAN-MADE TEMPERATURE.

Calculating infrared contributions to vacuum expectation values of gluonic and quark fields

International Nuclear Information System (INIS)

Arbuzov, B.A.; Boos, E.E.; Turashvili, K.Sh.

1986-01-01

Based on the infrared asymptotics of the lower QCD Green's functions obtained before, we propose a definition and elaborate a technique for calculating non-perturbative vacuum expectations of gluon and quark fields. In our calculations, we use only the known QCD parameters: constituent quark masses, the confining potential slope and the QCD parameter Λ. The values obtained for the vacuum expectations agree well with experiment. (orig.)

Hydrodynamics of quark-gluon plasmas

International Nuclear Information System (INIS)

Blaizot, J.P.

1986-06-01

This paper reviews some aspects of the hydrodynamics of quark-gluon plasmas. Various stages of ultra-relativistic heavy ion collisions are described. Several estimates of the maximum energy density expected to be achieved in these collisions are compared. Discontinuities which may be induced in the hydrodynamic flow by a phase transition are described and a convenient numerical method designed to deal with such discontinuous flows is briefly presented. Finally, the correlations between particle transverse momenta and multiplicities are analyzed and one discusses to which extent these correlations could signal the occurrence of a phase transition in heavy ion collisions

Experimental status of the search for the quark-gluon plasma in ultra-relativistic heavy ion interactions

International Nuclear Information System (INIS)

Salmeron, R.A.

1992-01-01

The deconfinement of quarks, antiquarks and gluons, and the phase transition from a hadron phase to a quark-gluon plasma phase are presented after recalling some elementary notions about normal nuclear matter. Eight proposed signatures of the quark-gluon plasma are described and a summary is given of the experiments concerning three of them: Bose-Einstein interference, the suppression of the J/ψ production and strange particles production. (author)

Quark-gluon plasma in strong magnetic fields

Energy Technology Data Exchange (ETDEWEB)

Kalaydzhyan, Tigran

2013-04-15

One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

Quark-gluon plasma in strong magnetic fields

International Nuclear Information System (INIS)

Kalaydzhyan, Tigran

2013-04-01

One of the fundamental problems in subatomic physics is the determination of properties of matter at extreme temperatures, densities and electromagnetic fields. The modern ultrarelativistic heavy-ion experiments are able to study such states (the quark-gluon plasma) and indicate that the physics at extreme conditions differs drastically from what is known from the conventional observations. Also the theoretical methods developed mostly within the perturbative framework face various conceptual problems and need to be replaced by a nonperturbative approach. In this thesis we study the physics of the strongly-coupled quark-gluon plasma in external magnetic fields as well as general electromagnetic and topological properties of the QCD and QCD-like systems. We develop and apply various nonperturbative techniques, based on e.g. gauge-gravity correspondence, lattice QCD simulations, relativistic hydrodynamics and condensed-matter-inspired models.

Testing static quark-antiquark potentials with bottomonium

International Nuclear Information System (INIS)

Lichtenberg, D.B.; Predazzi, E.; Roncaglia, R.; Rosso, M.; Wills, J.G.

1989-01-01

We investigate the question of whether experimental data on the energy levels of bottomonium can discriminate between quark-antiquark potentials which are motivated by what we know about QCD and potentials which are purely phenomenological. We restrict ourselves to bottomonium because, of all the quarkonia observed thus far, bottomonium is the least relativistic and therefore the best testing ground for the static quarkonium potential. We consider two potentials whose functional form is motivated from perturbative QCD at short quark-antiquark separations and from nonperturbative lattice QCD at large separations. We also consider three strictly phenomenological potentials. We find that the best of the three phenomenological potentials, which has never been previously used, fits the spin-averaged data at least as well as the best of the QCD-motivated potentials. We propose further measurements on bottomium energy levels to provide additional tests. (orig.)

Hadron spectroscopy and form factors at quark level

International Nuclear Information System (INIS)

Chakrabarty, S.; Gupta, K.K.; Singh, N.N.; Mitra, A.N.

1988-01-01

The theoretical status of hadrons as quark composites is examined from the point of view of a simultaneous understanding of their on-shell (mass spectra) and off-shell (form factors, transition amplitudes) properties. Greater stress is laid on light quark systems which are more sensitive to the confinement regime, and more prone to relativistic effects than on heavy quarkonia (on which many reviews exist). Two broad theoretical approaches obeying Lorentz and gauge invariance are identified: (i) QCD sum rules as a means of extrapolation from high to low energies; and (ii) dynamical equations for providing a microcausal link in the opposite direction (from low to high energies). The latter represents the major focus of attention in this article, with the Bethe-Salpeter Equation (BSE) providing a formal plank for a comparative assessment of several models. The Null-plane ansatz which facilitates the reduction of the 4-D BSE to a covariant 3-D form also provides the language for its comparison with other covariant 3-D equations. In particular, attention is drawn to the interesting possibility of reconstructing the 4-D BS wave function from its 3-D form (in a two-tier fashion) as a practical tool for generating higher Fock-space components (qq effects) in the BS wave function, and (more interestingly) for a clean separation between soft and hard QCD effects. To illustrate one such practical tool for an integrated view of different hadronic sectors within a single framework, the results of a two-tier BS model are presented in respect of qq-bar, qqq, gg, ggg, gqq-bar states and compared with experiment as well as with the results of other contemporary models. The N.R Resonating Group Method, which becomes necessary for bigger (six-quark) systems is briefly discussed from the point of view of its compatibility with a relativistic form of quark dynamics motivated from the BSC. (Author)

Relativistic many-body bound systems. Monograph report

International Nuclear Information System (INIS)

Danos, M.; Gillet, V.

1975-04-01

The principles and the mathematical details of a fully relativistic nuclear theory are given. Since the concept of nuclear forces is a strictly non-relativistic construct, it must be abandoned, and the forces must be replaced explicitly by their physical origin, i.e., by the interaction between nucleons and mesons. Thus, in this monograph the description of a nucleus has been formulated as a problem of relativistic quantum field theory which is solved by nuclear physics methods; to wit: the physics is described by specifying a Lagrangian which is a functional of the constituent fields (= of the parton fields); the solutions for the physical systems then are obtained in a time-independent treatment as expansions in the parton fields: both particles and nuclei are composite systems, made up of parton configurations, which define a representation of the Hamiltonian (associated with the specified Lagrangian)

Tadpole renormalization and relativistic corrections in lattice NRQCD

Science.gov (United States)

Shakespeare, Norman H.; Trottier, Howard D.

1998-08-01

We make a detailed comparison of two tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. We renormalize improved gauge-field and NRQCD actions using the mean-link u0,L in the Landau gauge, and using the fourth root of the average plaquette u0,P. Simulations are done for the three quarkonium systems cc¯, bc¯, and bb¯. The hyperfine splittings are computed both at leading [O(MQv4)] and at next-to-leading [O(MQv6)] order in the relativistic expansion, where MQ is the renormalized quark mass, and v2 is the mean-squared velocity. Results are obtained at a large number of lattice spacings, in the range of about 0.14-0.38 fm. A number of features emerge, all of which favor tadpole renormalization using u0,L. This includes a much better scaling behavior of the hyperfine splittings in the three quarkonium systems when u0,L is used. We also find that relativistic corrections to the spin splittings are smaller when u0,L is used, particularly for the cc¯ and bc¯ systems. We also see signs of a breakdown in the NRQCD expansion when the bare quark mass falls below about 1 in lattice units. Simulations with u0,L also appear to be better behaved in this context: the bare quark masses turn out to be larger when u0,L is used, compared to when u0,P is used on lattices with comparable spacings. These results also demonstrate the need to go beyond tree-level tadpole improvement for precision simulations.

Heavy quark production processes in QCD

International Nuclear Information System (INIS)

Brodsky, S.J.; Gunion, J.F.

1984-12-01

We have identified two novel effects in QCD, each of which acts to enhance the production of heavy quark and supersymmetric particles beyond what is conventionally expected from gluon fusion. Both effects are present in QED, but are compounded in QCD because of the increased number of diagrams and the much larger coupling constant. The intrinsic charm quark distribution in the nucleon could account for the observed enhancements of the charm structure function at large x and features of the charm production data but this mechanism is relatively suppressed for heavier systems. Prebinding distortion of the fusion cross section is, however, likely to be significant for the production at low p/sub T/ of all particles containing heavy colored constituents. At this stage the QCD calculations are highly model dependent although they agree with the general properties which can be inferred from the operator product expansion in the heavy quark mass. Much more theoretical analysis of these effects is clearly needed. It is also clear that much more experimental work is necessary to extend and confirm the reported anomalous heavy quark signals. 22 references

Extreme states in nuclear matter

International Nuclear Information System (INIS)

Rafelski, J.; Frankfurt Univ.

1981-01-01

Theory of hot nuclear fireballs consisting of all possible finite size hadronic constituents in chemical and thermal equilibrium is presented. As a complement of this hadronic gas phase characterized by maximal temperature and energy density, the quark bag description of the hadronic fireball is considered. Preliminary calculations of temperatures and mean transverse momenta of particles emitted in high multiplicity relativistic nuclear collisions together with some considereations on the observability of quark matter are offered. (orig.)

Three particle Poincare states and SU(6) x SU(3) as a classification group for baryons

International Nuclear Information System (INIS)

Buccella, F.; Sciarrino, A.; Sorba, P.

1975-05-01

A complete set of democratic quantum numbers is introduced to classify the states of an irreducible unitary representation (IUR) of the Poincare group obtained from the decomposition of the direct products of three I.U.R. Such states are identified with the baryon states constituted of three free relativistic quarks. The transformation from current to constituent quarks is then easily reobtained. Moreover, the group SU(6) x SU(3) appears naturally as a collinear classification group for baryons. Results similar to those of the symmetric harmonic oscillator quark model are obtained [fr

Description of width and spectra of two relativistic fermions bound states

International Nuclear Information System (INIS)

Sidorov, A.V.; Skachkov, N.B.

1979-01-01

The formalism for relativistic description of two particles with spin 1/2 is constructed. Used is the two-particle three-dimensional equation, obtained by quasipotential approach. Quasipotential equation in the relativistic configurational space with OBEP potential is reduced to the system of partial equations which is the analog of nonrelativistic Hamada-Jonston system. WKB approach is used to calculate mass spectra and leptonic width of mesons in quark model. The results of the study can be applied to the calculation of mass spectra and widths of electromagnetic decays of systems of e + e - , μ + μ - , c anti c, b anti b, N anti N type

Relativistic shock waves and the excitation of plerions

Energy Technology Data Exchange (ETDEWEB)

Arons, J. (California Univ., Berkeley, CA (USA)); Gallant, Y.A. (California Univ., Berkeley, CA (USA). Dept. of Physics); Hoshino, Masahiro; Max, C.E. (California Univ., Livermore, CA (USA). Inst. of Geophysics and Planetary Physics); Langdon, A.B. (Lawrence Livermore National Lab., CA (USA))

1991-01-07

The shock termination of a relativistic magnetohydrodynamic wind from a pulsar is the most interesting and viable model for the excitation of the synchrotron sources observed in plerionic supernova remnants. We have studied the structure of relativistic magnetosonic shock waves in plasmas composed purely of electrons and positrons, as well as those whose composition includes heavy ions as a minority constituent by number. We find that relativistic shocks in symmetric pair plasmas create fully thermalized distributions of particles and fields downstream. Therefore, such shocks are not good candidates for the mechanism which converts rotational energy lost from a pulsar into the nonthermal synchrotron emission observed in plerions. However, when the upstream wind contains heavy ions which are minority constituent by number density, but carry the bulk of the energy density, much of the energy of the shock goes into a downstream, nonthermal power law distribution of positrons with energy distribution N(E)dE {proportional to}E{sup {minus}s}. In a specific model presented in some detail, s = 3. These characteristics are close to those assumed for the pairs in macroscopic MHD wind models of plerion excitation. The essential mechanism is collective synchrotron emission of left-handed extraordinary modes by the ions in the shock front at high harmonics of the ion cyclotron frequency, with the downstream positrons preferentially absorbing almost all of this radiation, mostly at their fundamental (relativistic) cyclotron frequencies. Possible applications to models of plerions and to constraints on theories of energy loss from pulsars are briefly outlines. 27 refs., 5 figs.

Final Report for Project ``Theory of ultra-relativistic heavy-ion collisions''

Energy Technology Data Exchange (ETDEWEB)

Ulrich W. Heinz

2012-11-09

In the course of this project the Ohio State University group led by the PI, Professor Ulrich Heinz, developed a comprehensive theoretical picture of the dynamical evolution of ultra-relativistic heavy-ion collisions and of the numerous experimental observables that can be used to diagnose the evolving and short-lived hot and dense fireball created in such collisions. Starting from a qualitative understanding of the main features based on earlier research during the last decade of the twentieth century on collisions at lower energies, the group exploited newly developed theoretical tools and the stream of new high-quality data from the Relativistic Heavy Ion Collider at Brookhaven National Laboratory (which started operations in the summer of the year 2000) to arrive at an increasingly quantitative description of the experimentally observed phenomena. Work done at Ohio State University (OSU) was instrumental in the discovery during the years 2001-2003 that quark-gluon plasma (QGP) created in nuclear collisions at RHIC behaves like an almost perfect liquid with minimal viscosity. The tool of relativistic fluid dynamics for viscous liquids developed at OSU in the years 2005-2007 opened the possibility to quantitatively determine the value of the QGP viscosity empirically from experimental measurements of the collective flow patterns established in the collisions. A first quantitative extraction of the QGP shear viscosity, with controlled theoretical uncertainty estimates, was achieved during the last year of this project in 2010. OSU has paved the way for a transition of the field of relativistic heavy-ion physics from a qualitative discovery stage to a new stage of quantitative precision in the description of quark-gluon plasma properties. To gain confidence in the precision of our theoretical understanding of quark-gluon plasma dynamics, one must test it on a large set of experimentally measured observables. This achievement report demonstrates that we have, at

Impact of early stage non-equilibrium dynamics on photon production in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Oliva, L; Plumari, S; Scardina, F; Greco, V; Ruggieri, M

2017-01-01

In this study we discuss our results on the spectrum of photons emitted from the quark-gluon plasma produced in heavy ion collisions at RHIC energies. Simulating the space-time evolution of the fireball by solving the relativistic Boltzmann transport equation and including two-particle scattering processes with photon emission allows us to make a first step in the description of thermal photons from the QGP as well as of those produced in the pre-equilibrium stage. Indeed, we consider not only a standard Glauber initial condition but also a model in which quarks and gluons are produced in the very early stage through the Schwinger mechanism by the decay of an initial color-electric field. In the latter approach relativistic kinetic equations are coupled in a self-consistent way to field equations. We aim at spotting the impact of early stage non-equilibrium dynamics on the photon production. (paper)

The A=3 Nolen-Schiffer anomaly and the up-down quark mass difference

International Nuclear Information System (INIS)

Encinosa, M.; Robson, D.

1990-01-01

A recently proposed nonrelativistic many-body quark model is used to generate class III nucleon-nucleon potentials in a Born-Oppenheimer approach. These potentials, when treated in first-order perturbation theory with a simple ansatz for the three-nucleon wave function, allow us to make an estimate of the 3 He- 3 H mass difference. For accepted values of the constituent up-down quark mass difference we find that approximately sixty percent of the A=3 Nolen-Schiffer anomaly can be accounted for solely from the up-down quark kinetic energy difference. (orig.)

Fourth workshop on experiments and detectors for a relativistic heavy ion collider

International Nuclear Information System (INIS)

Fatyga, M.; Moskowitz, B.

1990-01-01

This report contains papers on the following topics: physics at RHIC; flavor flow from quark-gluon plasma; space-time quark-gluon cascade; jets in relativistic heavy ion collisions; parton distributions in hard nuclear collisions; experimental working groups, two-arm electron/photon spectrometer collaboration; total and elastic pp cross sections; a 4π tracking TPC magnetic spectrometer; hadron spectroscopy; efficiency and background simulations for J/ψ detection in the RHIC dimuon experiment; the collision regions beam crossing geometries; Monte Carlo simulations of interactions and detectors; proton-nucleus interactions; the physics of strong electromagnetic fields in collisions of relativistic heavy ions; a real time expert system for experimental high energy/nuclear physics; the development of silicon multiplicity detectors; a pad readout detector for CRID/tracking; RHIC TPC R ampersand D progress and goals; development of analog memories for RHIC detector front-end electronic systems; calorimeter/absorber optimization for a RHIC dimuon experiment; construction of a highly segmented high resolution TOF system; progress report on a fast, particle-identifying trigger based on ring-imaging and highly integrated electronics for a TPC detector

Fourth workshop on experiments and detectors for a relativistic heavy ion collider

Energy Technology Data Exchange (ETDEWEB)

Fatyga, M.; Moskowitz, B. (eds.)

1990-01-01

This report contains papers on the following topics: physics at RHIC; flavor flow from quark-gluon plasma; space-time quark-gluon cascade; jets in relativistic heavy ion collisions; parton distributions in hard nuclear collisions; experimental working groups, two-arm electron/photon spectrometer collaboration; total and elastic pp cross sections; a 4{pi} tracking TPC magnetic spectrometer; hadron spectroscopy; efficiency and background simulations for J/{psi} detection in the RHIC dimuon experiment; the collision regions beam crossing geometries; Monte Carlo simulations of interactions and detectors; proton-nucleus interactions; the physics of strong electromagnetic fields in collisions of relativistic heavy ions; a real time expert system for experimental high energy/nuclear physics; the development of silicon multiplicity detectors; a pad readout detector for CRID/tracking; RHIC TPC R D progress and goals; development of analog memories for RHIC detector front-end electronic systems; calorimeter/absorber optimization for a RHIC dimuon experiment; construction of a highly segmented high resolution TOF system; progress report on a fast, particle-identifying trigger based on ring-imaging and highly integrated electronics for a TPC detector.

Mass spectrum of vector mesons in the relativistic model of quasi-independent quarks

International Nuclear Information System (INIS)

Savrin, V.I.; Khrushchev, V.V.; Semenov, S.V.

1988-01-01

Mass values of mesons with J PC =1 -- built of u-, d-, s-, c-, b-quarks in S-states have been found with the help of numerical solutions of Dirac equation. The potential entering the equation consists of the scalar linear potential and the Coulomb vector one. The main contribution into spectra dependence on the radial quantum number for light quarks is shown to give the cnfinement scalar flavour independent potential: V c (r)=κ 2 r, at parameter value κ∼ 0.42 GeV. The calculated mass values are in agreement with ∼ 5% accuracy with the data for well established mesons

Non-leptonic decays in an extended chiral quark model

Energy Technology Data Exchange (ETDEWEB)

Eeg, J. O. [Dept. of Physics, Univ. of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)

2012-10-23

We consider the color suppressed (nonfactorizable) amplitude for the decay mode B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}. We treat the b-quark in the heavy quark limit and the energetic light (u,d,s) quarks within a variant of Large Energy Effective Theory combined with an extension of chiral quark models. Our calculated amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} is suppressed by a factor of order {Lambda}{sub QCD}/m{sub b} with respect to the factorized amplitude, as it should according to QCD-factorization. Further, for reasonable values of the (model dependent) gluon condensate and the constituent quark mass, the calculated nonfactorizable amplitude for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0} can easily accomodate the experimental value. Unfortunately, the color suppressed amplitude is very sensitive to the values of these model dependent parameters. Therefore fine-tuning is necessary in order to obtain an amplitude compatible with the experimental result for B{sub d}{sup 0}{yields}{pi}{sup 0}{pi}{sup 0}.

Towards next-to-leading order corrections to the heavy quark potential in the effective string theory

Directory of Open Access Journals (Sweden)

Hwang Sungmin

2017-01-01

Full Text Available We present our calculation of the non-relativistic corrections to the heavy quark-antiquark potential up to leading and next-to-leading order (NLO via the effective string theory (EST. Full systematics of effective field theory (EFT are discussed in order for including the NLO contribution that arises in the EST. We also show how the number of dimensionful parameters arising from the EST are reduced by the constraints between the Wilson coeffcients from non-relativistic EFTs for QCD.

Relativistic quantum theory of composite systems

International Nuclear Information System (INIS)

Sogami, I.

1978-01-01

A relativistic quantum theory free from the difficulties of tachyons and ghosts is formulated to describe the scattering processes between composite systems of spinless quarks. To evade the complication brewed by introducing gluon fields or strings, valence quarks are effectively assumed to be in the relative motion of harmonic oscillation correlating with the motion of the composite system as a whole. A quark-antiquark system is represented by a bilocal field describing a sequence of mesons and every meson is identified with the composite system in a definite eigenstate of relative motion. The quantization is performed in the interaction picture, so that the microcausal condition is satisfied by local fields which result from the decomposition of bilocal fields. Imposing a weakened macrocausal condition on the whole motion of the extended system, a causal bilocal propagator is defined and a consistent time ordering among bilocal fields is defined. The invariant S-matrix is obtained and the graphical method for the calculation of its elements is developed in parallel with the conventional local field theory. For the (bilocal field) 3 interaction any malignant divergence does not appear excepting those in the renormalizable local field theory. The theory provides one promising and comprehensive phenomenology of hadrons which is suitable especially to describe the hard structure of hadrons. (author)

Adler function and hadronic contribution to the muon g-2 in a nonlocal chiral quark model

International Nuclear Information System (INIS)

Dorokhov, Alexander E.

2004-01-01

The behavior of the vector Adler function at spacelike momenta is studied in the framework of a covariant chiral quark model with instantonlike quark-quark interaction. This function describes the transition between the high-energy asymptotically free region of almost massless current quarks to the low-energy hadronized regime with massive constituent quarks. The model reproduces the Adler function and V-A correlator extracted from the ALEPH and OPAL data on hadronic τ lepton decays, transformed into the Euclidean domain via dispersion relations. The leading order contribution from the hadronic part of the photon vacuum polarization to the anomalous magnetic moment of the muon, a μ hvp(1) , is estimated

Physical Origin of Density Dependent Force of the Skyrme Type within the Quark Meson Coupling Model

International Nuclear Information System (INIS)

Pierre Guichon; Hrayr Matevosyan; N. Sandulescu; Anthony Thomas

2006-01-01

A density dependent, effective nucleon-nucleon force of the Skyrme type is derived from the quark-meson coupling model--a self-consistent, relativistic quark level description of nuclear matter. This new formulation requires no assumption that the mean scalar field is small and hence constitutes a significant advance over earlier work. The similarity of the effective interaction to the widely used SkM* force encourages us to apply it to a wide range of nuclear problems, beginning with the binding energies and charge distributions of doubly magic nuclei. Finding impressive results in this conventional arena, we apply the same effective interaction, within the Hartree-Fock-Bogoliubov approach, to the properties of nuclei far from stability. The resulting two neutron drip lines and shell quenching are quite satisfactory. Finally, we apply the relativistic formulation to the properties of dense nuclear matter in anticipation of future application to the properties of neutron stars

A T-matrix calculation for in-medium heavy-quark gluon scattering

International Nuclear Information System (INIS)

Huggins, K.; Rapp, R.

2012-01-01

The interactions of charm and bottom quarks in a quark-gluon plasma (QGP) are evaluated using a thermodynamic 2-body T-matrix. We specifically focus on heavy-quark (HQ) interactions with thermal gluons with an input potential motivated by lattice-QCD computations of the HQ free energy. The latter is implemented into a field-theoretic ansatz for color-Coulomb and (remnants of) confining interactions. This, in particular, enables to discuss corrections to the potential approach, specifically hard-thermal-loop corrections to the vertices, relativistic corrections deduced from pertinent Feynman diagrams, and a suitable projection on transverse thermal gluons. The resulting potentials are applied to compute scattering amplitudes in different color channels and utilized for a calculation of the corresponding HQ drag coefficient in the QGP. A factor of ∼2-3 enhancement over perturbative results is obtained, mainly driven by the resummation in the attractive color-channels.

Elliptic flow and energy loss of heavy quarks in ultrarelativistic heavy ion collisions

International Nuclear Information System (INIS)

Uphoff, Jan; Fochler, Oliver; Greiner, Carsten; Xu, Zhe

2011-01-01

The space-time propagation of heavy quarks in ultrarelativistic heavy ion collisions is studied within the partonic transport model Boltzmann approach of multiparton scatterings (BAMPS). In this model heavy quarks interact with the partonic medium via binary scatterings. The cross sections for these interactions are calculated with leading-order perturbative QCD, but feature a more precise Debye screening derived within the hard thermal loop approximation and obey the running of the coupling. Within this framework the elliptic flow and the nuclear modification factor of heavy quarks are computed for the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) energies and compared to available experimental data. It is found that binary scatterings alone cannot reproduce the data and therefore radiative corrections have to be taken into account.

Relativistic viscous hydrodynamics for heavy-ion collisions with ECHO-QGP

CERN Document Server

Del Zanna, L; Inghirami, G; Rolando, V; Beraudo, A; De Pace, A; Pagliara, G; Drago, A; Becattini, F

2013-01-01

We present ECHO-QGP, a numerical code for $(3+1)$-dimensional relativistic viscous hydrodynamics designed for the modeling of the space-time evolution of the matter created in high energy nuclear collisions. The code has been built on top of the \\emph{Eulerian Conservative High-Order} astrophysical code for general relativistic magneto-hydrodynamics [\\emph{Del Zanna et al., Astron. Astrophys. 473, 11, 2007}] and here it has been upgraded to handle the physics of the Quark-Gluon Plasma. ECHO-QGP features second-order treatment of causal relativistic viscosity effects in both Minkowskian or Bjorken coordinates; partial or complete chemical equilibrium of hadronic species before kinetic freeze-out; initial conditions based on the optical Glauber model, including a Monte-Carlo routine for event-by-event fluctuating initial conditions; a freeze-out procedure based on the Cooper-Frye prescription. The code is extensively validated against several test problems and results always appear accurate, as guaranteed by th...

Similarity flows in relativistic hydrodynamics

International Nuclear Information System (INIS)

Blaizot, J.P.; Ollitrault, J.Y.

1986-01-01

In ultra-relativistic heavy ion collisions, one expects in particular to observe a deconfinement transition leading to a formation of quark gluon plasma. In the framework of the hydrodynamic model, experimental signatures of such a plasma may be looked for as observable consequences of a first order transition on the evolution of the system. In most of the possible scenario, the phase transition is accompanied with discontinuities in the hydrodynamic flow, such as shock waves. The method presented in this paper has been developed to treat without too much numerical effort such discontinuous flow. It relies heavily on the use of similarity solutions of the hydrodynamic equations

QCD mixing effects in a gauge invariant quark model for photo- and electroproduction of baryon resonances

International Nuclear Information System (INIS)

Zhenping Li; Close, F.E.

1990-03-01

The photo and electroproduction of baryon resonances has been calculated using the Constituent Quark Model with chromodynamics consistent with O(υ 2 /c 2 ) for the quarks. We find that the successes of the nonrelativistic quark model are preserved, some problems are removed and that QCD mixing effects may become important with increasing q 2 in electroproduction. For the first time both spectroscopy and transitions receive a unified treatment with a single set of parameters. (author)

Quark-Gluon Soup -- The Perfectly Liquid Phase of QCD

Science.gov (United States)

Heinz, Ulrich

2015-03-01

At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.

Pseudoscaler meson masses in the quark model

International Nuclear Information System (INIS)

Karl, G.

1976-10-01

Pseudoscaler meson masses and sum rules are compared in two different limits of a quark model with 4 quarks. The conventional limit corresponds to a heavy c anti c state and generalizes ideal mixing in a nonet. The second limit corresponds to a missing SU 4 unitary singlet and appears more relevant to the masses of π, K, eta, eta'. If SU 3 is broken only by the mass difference between the strange and nonstrange quarks, the physical masses imply that the u anti u, d anti d and s anti s pairs account only for 33% of the composition of the eta'(960), while for the eta(548) this fraction is 86%. If some of the remaining matter is in the form of the constituents of J/psi, the relative proportion of the relative decays J/psi → eta γ vs J/psi → etaγ is accounted for in satisfactory agreement with experiment. (author)

Centrality dependence of identified particle elliptic flow in relativistic heavy ion collisions at √{sN N}=7.7 -62.4 GeV

Science.gov (United States)

Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Bai, X.; Bairathi, V.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Chisman, O.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, H. Z.; Huang, B.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, Y.; Li, W.; Li, C.; Li, X.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, Y. G.; Ma, G. L.; Ma, R.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X.; Sun, Z.; Sun, Y.; Sun, X. M.; Surrow, B.; Svirida, N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, Y.; Wang, G.; Wang, Y.; Wang, J. S.; Wang, H.; Webb, J. C.; Webb, G.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xin, K.; Xu, Z.; Xu, H.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, C.; Yang, S.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, Y.; Zhang, S.; Zhang, J.; Zhang, J.; Zhang, Z.; Zhang, X. P.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

2016-01-01

Elliptic flow (v2) values for identified particles at midrapidity in Au + Au collisions measured by the STAR experiment in the Beam Energy Scan at the Relativistic Heavy Ion Collider at √{sN N}= 7.7 -62.4 GeV are presented for three centrality classes. The centrality dependence and the data at √{sN N}= 14.5 GeV are new. Except at the lowest beam energies, we observe a similar relative v2 baryon-meson splitting for all centrality classes which is in agreement within 15% with the number-of-constituent quark scaling. The larger v2 for most particles relative to antiparticles, already observed for minimum bias collisions, shows a clear centrality dependence, with the largest difference for the most central collisions. Also, the results are compared with a multiphase transport (AMPT) model and fit with a blast wave model.

Mass spectra of four-quark states in the hidden charm sector

International Nuclear Information System (INIS)

Patel, Smruti; Shah, Manan; Vinodkumar, P.C.

2014-01-01

Masses of the low-lying four-quark states in the hidden charm sector (cq anti c anti q; q element of u,d) are calculated within the framework of a non-relativistic quark model. The four-body system is considered as two two-body systems such as diquark-antidiquark (Qq- anti Q anti q) and quark-antiquark-quark-antiquark (Q anti q- anti Qq) molecular-like four-quark states. Here, the Cornell-type potential has been used for describing the two-body interactions among Q-q, anti Q- anti q, Q- anti q, Qq- anti Q anti q and Q anti q- anti Qq, with appropriate string tensions. Our present analysis suggests the following exotic states: X(3823), Z c (3900), X(3915), Z c (4025), ψ (4040), Z 1 (4050) and X(4160) as Q anti q- anti Qq molecular-like four-quark states, while Z c (3885), X(3940) and Y(4140) as the diquark-antidiquark four-quark states. We have been able to assign the J PC values for many of the recently observed exotic states according to their structure. Apart from this, we have identified the charged state Z(4430) recently confirmed by LHCb as the first radial excitation of Zc(3885) with G = + 1 and Y(4360) state as the first radial excitation of Y(4008) with G = - 1 and the state ψ(4415) as the first radial excitation of the ψ(4040) state. (orig.)

Nucleon electromagnetic form factors in a relativistic quark model with chiral symmetry

Energy Technology Data Exchange (ETDEWEB)

Barik, N; Das, M

1987-05-01

The nucleon electromagnetic form factors are computed in an independent quark model based on the Dirac equation. Corrections for centre-of-mass motion and pion-cloud effects are incorporated. Results for static quantities are in reasonable agreement with the experimental data.

Relativistic rapprochement of weak and strong interactions

International Nuclear Information System (INIS)

Strel'tsov, V.N.

1995-01-01

On the basis of the relativistic Yukawa potentials for the nuclear (quark) field and the field of intermediate vector W-, Z-bosons, it is shown that the interactions described by them increase differently with growing velocity (the weak one increases more rapidly). According to the estimates, they are compared (at distances of the 'action radius' of nuclear forces) at an energy of about 10 12 GeV (10 6 GeV for the pion field) what is smaller than the corresponding value in the model of 'grand unification'. 3 refs., 2 tabs

Proton relativistic model; Modelo relativistico do proton

Energy Technology Data Exchange (ETDEWEB)

Araujo, Wilson Roberto Barbosa de

1996-12-31

In this dissertation, we present a model for the nucleon, which is composed by three relativistic quarks interacting through a contract force. The nucleon wave-function was obtained from the Faddeev equation in the null-plane. The covariance of the model under kinematical null-plane boots is discussed. The electric proton form-factor, calculated from the Faddeev wave-function, was in agreement with the data for low-momentum transfers and described qualitatively the asymptotic region for momentum transfers around 2 GeV. (author) 42 refs., 22 figs., 1 tab.

Toward the Limits of Matter: Ultra-relativistic nuclear collisions at CERN

CERN Document Server

Schukraft, Jurgen

2015-01-01

Strongly interacting matter as described by the thermodynamics of QCD undergoes a phase transition, from a low temperature hadronic medium to a high temperature quark-gluon plasma state. In the early universe this transition occurred during the early microsecond era. It can be investigated in the laboratory, in collisions of nuclei at relativistic energy, which create "fireballs" of sufficient energy density to cross the QCD Phase boundary. We describe 3 decades of work at CERN, devoted to the study of the QCD plasma and the phase transition. From modest beginnings at the SPS, ultra-relativistic heavy ion physics has evolved today into a central pillar of contemporary nuclear physics and forms a significant part of the LHC program.

Quarks: Two's company, three a crowd?

International Nuclear Information System (INIS)

Anon.

1990-01-01

Last year, careful measurements by the experiments studying electron positron annihilation in CERN's new LEP ring and at Stanford's SLC linear collider showed that the conventional list of the basic constituents of matter is complete. Three types of particles (electron, muon and tau) interacting under the weak nuclear force are linked to six quarks - the constituents of nuclear matter - grouped pairwise into three distinct families ('up' and 'down', 'strange' and 'charm', 'beauty' and 'top'). The question now is to understand why this sixquark model works

Threshold pion photoproduction in A light-cone quark model

International Nuclear Information System (INIS)

Konen, W.; Drechsel, D.

1991-01-01

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

Nucleon electromagnetic form factors in a relativistic quark model with chiral symmetry

International Nuclear Information System (INIS)

Barik, N.

1987-01-01

The nucleon electromagnetic form factors are computed in an independent quark model based on the Dirac equation. Corrections for centre-of-mass motion and pion-cloud effects are incorporated. Results for static quantities are in reasonable agreement with the experimental data. (author)

Quark condensation, induced symmetry breaking and color superconductivity at high density

International Nuclear Information System (INIS)

Langfeld, Kurt; Rho, Mannque

1999-01-01

The phase structure of hadronic matter at high density relevant to the physics of compact stars and relativistic heavy-ion collisions is studied in a low-energy effective quark theory. The relevant phases that figure are (1) chiral condensation, (2) diquark color condensation (color superconductivity) and (3) induced Lorentz-symmetry breaking (''ISB''). For a reasonable strength for the effective four-Fermi current-current interaction implied by the low-energy effective quark theory for systems with a Fermi surface we find that the ''ISB'' phase sets in together with chiral symmetry restoration (with the vanishing quark condensate) at a moderate density while color superconductivity associated with scalar diquark condensation is pushed up to an asymptotic density. Consequently, color superconductivity seems rather unlikely in heavy-ion collisions although it may play a role in compact stars. Lack of confinement in the model makes the result of this analysis only qualitative but the hierarchy of the transitions we find seems to be quite robust

Dilepton production from the quark-gluon plasma using (3 +1 )-dimensional anisotropic dissipative hydrodynamics

Science.gov (United States)

Ryblewski, Radoslaw; Strickland, Michael

2015-07-01

We compute dilepton production from the deconfined phase of the quark-gluon plasma using leading-order (3 +1 )-dimensional anisotropic hydrodynamics. The anisotropic hydrodynamics equations employed describe the full spatiotemporal evolution of the transverse temperature, spheroidal momentum-space anisotropy parameter, and the associated three-dimensional collective flow of the matter. The momentum-space anisotropy is also taken into account in the computation of the dilepton production rate, allowing for a self-consistent description of dilepton production from the quark-gluon plasma. For our final results, we present predictions for high-energy dilepton yields as a function of invariant mass, transverse momentum, and pair rapidity. We demonstrate that high-energy dilepton production is extremely sensitive to the assumed level of initial momentum-space anisotropy of the quark-gluon plasma. As a result, it may be possible to experimentally constrain the early-time momentum-space anisotropy of the quark-gluon plasma generated in relativistic heavy-ion collisions using high-energy dilepton yields.

Ultra-relativistic heavy ions and the CBA

International Nuclear Information System (INIS)

McLerran, L.D.

1982-01-01

The study of ultra-relativistic heavy ions at an accelerator such as the CBA provides a unique glimpse of matter as it may have appeared in the early universe. This hot dense matter very probably appears as a quark-gluon plasma which expands and cools into hadronic matter. The CBA would provide data at the very highest energies, and produce matter at the highest energy densities. The possibility of using a cyclotron to inject very heavy ions into the AGS and then into the CBA would also allow the production of quark-gluon matter at higher energy densities than would light ions, and would make the matter in a larger volume where surface effects are minimized. At the highest energies with very heavy ions, there is great flexibility in the experimental signals which might be studied, as well as the nature of the matter which is produced. Some of the possibilities are discussed

Photons from Ultra-Relativistic Heavy Ion Collisions

CERN Document Server

Sarkar, S

2000-01-01

It is believed that a novel state of matter - Quark Gluon Plasma (QGP) will be transiently produced if normal hadronic matter is subjected to sufficiently high temperature and/or density. We have investigated the possibility of QGP formation in the ultra-relativistic collisions of heavy ions through the electromagnetic probes - photons and dileptons. The formulation of the real and virtual photon production rate from strongly interacting matter is studied in the framework of Thermal Field Theory. Since signals from the QGP will pick up large backgrounds from hadronic matter we have performed a detailed study of the changes in the hadronic properties induced by temperature within the ambit of the Quantum Hadrodynamic model, gauged linear and non-linear sigma models, hidden local symmetry approach and QCD sum rule approach. The possibility of observing the direct thermal photons and lepton pairs from quark gluon plasma has been contrasted with that from hot hadronic matter with and without medium effects for va...

Hard probes (and soft ones) to test the quark-gluon soup

CERN Multimedia

Preuss, Paul

2006-01-01

"We need the hardest probes of all to study the hot, dense state of matter that exists when two heavy nuclei like gold collide with enough energy to temporarily free the quarks and gluons in their constituent protons and neutrons." (3 pages)

Ultra-relativistic heavy ion collisions in a multi-string model

International Nuclear Information System (INIS)

Werner, K.

1987-01-01

We present a model for ultra-relativistic heavy ion collisions based on color string formation and subsequent independent string fragmentation. Strings are formed due to color exchange between quarks at each individual nucleon nucleon collision. The fragmentation is treated as in e + e - or lepton nucleon scattering. Calculation for pp, pA, and AA were carried out using the Monte Carlo code VENUS for Very Energetic Nuclear Scattering (version 1.0). 20 refs., 6 figs

Asymptotics of pion electromagnetics form factor in scale invariant quark model

International Nuclear Information System (INIS)

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

1976-01-01

A consistent relativistic approach is proposed to the investigation of asymptotic behaviour of form factor of a system, composed of two spinor particles, interacting with the vector of (pseudo) scalar neutral field. It is shown that the assumption of finite and small asymptotical value of quark-gluon interaction invariant charge at small distances (g 9 2 9 2 ln(-Q 2 ) 2 values (Q 2 is squared momentum)

How to deal with relativistic heavy ion collisions

International Nuclear Information System (INIS)

Hagedorn, R.

1981-01-01

A qualitative review is given of the theoretical problems and possibilities arising when one tries to understand what happens in relativistic heavy ion collisions. The striking similarity between these and pp collisions suggests the use of techniques similar to those used five to twelve years ago in pp collisions to disentangle collective motions from thermodynamics. A very heuristic and qualitative sketch of statistical bootstrap thermodynamics concludes an idealized picture in which a relativistic heavy ion collision appears as a superposition of moving 'fireballs' with equilibrium thermodynamics in the rest frames of these fireballs. The interesting problems arise where this theoretician's picture deviates from reality: non-equilibrium, more complicated motion (shock waves, turbulence, spin) and the collision history. Only if these problems have been solved or shown to be irrelevant can we safely identify signatures of unusual states of hadronic matter as, for example, a quark-gluon plasma or density isomers. (orig.)

The quark propagator in a covariant gauge

International Nuclear Information System (INIS)

Bonnet, F.D.R.; Leinweber, D.B.; Williams, A.G.; Zanotti, J.M.

2000-01-01

Full text: The quark propagator is one of the fundamental building blocks of QCD. Results strongly depend on the ansatz for the propagator. Direct simulations of QCD on a space time lattice can provide guidance and constraints on the analytic structure of the quark propagator. On the lattice the infrared and asymptotic behaviour of the quark propagator is of particular interest since it is a reflection of the accuracy of the discretised quark action. In the deep infrared region, artefacts associated with the finite size of the lattice spacing become small. This is the most interesting region as nonperturbative physics lies here. However, the ultraviolet behaviour at large momentum of the propagator will in general strongly deviate from the correct continuum behaviour. This behaviour will be action dependent. Some interesting progress has been made in improving the ultraviolet behaviour of the propagator. A method, recently developed and referred to as tree-level correction, consists of using the knowledge of the tree-level behaviour to eliminate the obvious lattice artefacts. Tree-level correction represents a crucial step in extracting meaningful results for the mass function and the renormalisation function outside of the deep infrared region. The mass function is particularly interesting as it provides insights into the constituent quark mass as a measure of the nonperturbative physics. In this poster I will present results from the analytic structure of the propagator in recent lattice studies for a variety of fermion actions in lattice QCD. I will also present the new ratio method used to tree-level correct these quark propagators

Charge radii of octet and decuplet baryons in chiral constituent ...

Indian Academy of Sciences (India)

in electron–baryon scattering experiments [4,5] giving rp = 0.877 ± 0.007 fm ... breaking of the SU(3) symmetry and a non-vanishing neutron charge mean square radius ... QCD Lagrangian is not invariant under the chiral transformation. ... of a constituent quark GBs [34–37], successfully explains the 'proton spin problem'.

Quark-gluon soup — The perfectly liquid phase of QCD

Science.gov (United States)

Heinz, Ulrich

2015-01-01

At temperatures above about 150 MeV and energy densities exceeding 500 MeV/fm3, quarks and gluons exist in the form of a plasma of free color charges that is about 1000 times hotter and a billion times denser than any other plasma ever created in the laboratory. This quark-gluon plasma (QGP) turns out to be strongly coupled, flowing like a liquid. About 35 years ago, the nuclear physics community started a program of relativistic heavy-ion collisions with the goal of producing and studying QGP under controlled laboratory conditions. This article recounts the story of its successful creation in collider experiments at Brookhaven National Laboratory and CERN and the subsequent discovery of its almost perfectly liquid nature, and reports on the recent quantitatively precise determination of its thermodynamic and transport properties.

Bound-state quark and gluon contributions to structure functions in QCD

International Nuclear Information System (INIS)

Brodsky, S.J.

1991-01-01

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: 'intrinsic' contributions, which are due to the direct scattering on the bound-state constituents, and 'extrinsic' contributions, which are derived from particles created in the collision. In this talk, I discuss several aspects of deep inealstic structure functions in which the bound-state structure of the proton plays a crucial role: (1) the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; (2) the separation of the quark structure function of the proton into intrinsic 'bound-valence' and extrinsic 'non-valence' components which takes into account the Pauli principle; (3) the properties and identification of intrinsic heavy quark structure functions; and (4) a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. (orig.)

Bound-state quark and gluon contributions to structure functions in QCD

International Nuclear Information System (INIS)

Brodsky, S.J.

1990-08-01

One can distinguish two types of contributions to the quark and gluon structure functions of hadrons in quantum chromodynamics: ''intrinsic'' contributions, which are due to the direct scattering on the bound-state constituents, and ''extrinsic'' contributions, which are derived from particles created in the collision. In this talk, I discussed several aspects of deep inelastic structure functions in which the bound-state structure of the proton plays a crucial role: the properties of the intrinsic gluon distribution associated with the proton bound-state wavefunction; the separation of the quark structure function of the proton onto intrinsic ''bound-valence'' and extrinsic ''non-valence'' components which takes into account the Pauli principle; the properties and identification of intrinsic heavy quark structure functions; and a theory of shadowing and anti-shadowing of nuclear structure functions, directly related to quark-nucleon interactions and the gluon saturation phenomenon. 49 refs., 5 figs

Challenges to quantum chromodynamics: Anomalous spin, heavy quark, and nuclear phenomena

International Nuclear Information System (INIS)

Brodsky, S.J.

1989-11-01

The general structure of QCD meshes remarkably well with the facts of the hadronic world, especially quark-based spectroscopy, current algebra, the approximate point-like structure of large momentum transfer inclusive reactions, and the logarithmic violation of scale invariance in deep inelastic lepton-hadron reactions. QCD has been successful in predicting the features of electron-positron and photon-photon annihilation into hadrons, including the magnitude and scaling of the cross sections, the shape of the photon structure function, the production of hadronic jets with patterns conforming to elementary quark and gluon subprocesses. The experimental measurements appear to be consistent with basic postulates of QCD, that the charge and weak currents within hadrons are carried by fractionally-charged quarks, and that the strength of the interactions between the quarks, and gluons becomes weak at short distances, consistent with asymptotic freedom. Nevertheless in some cases, the predictions of QCD appear to be in dramatic conflict with experiment. The anomalies suggest that the proton itself as a much more complex object than suggested by simple non-relativistic quark models. Recent analyses of the proton distribution amplitude using QCD sum rules points to highly-nontrival proton structure. Solutions to QCD in one-space and one-time dimension suggest that the momentum distributions of non-valence quarks in the hadrons have a non-trival oscillatory structure. The data seems also to be suggesting that the ''intrinsic'' bound state structure of the proton has a non- negligible strange and charm quark content, in addition to the ''extrinsic'' sources of heavy quarks created in the collision itself. 144 refs., 46 figs., 2 tabs

Neutrino emissivity in the quark-hadron mixed phase of neutron stars

Energy Technology Data Exchange (ETDEWEB)

Spinella, William M. [Computational Science Research Center San Diego State University, San Diego, CA (United States); San Diego State University, Department of Physics, San Diego, CA (United States); Weber, Fridolin [San Diego State University, Department of Physics, San Diego, CA (United States); University of California San Diego, Center for Astrophysics and Space Sciences, La Jolla, CA (United States); Contrera, Gustavo A. [CONICET, Buenos Aires (Argentina); CONICET - Dept. de Fisica, UNLP, IFLP, La Plata (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina); Orsaria, Milva G. [CONICET, Buenos Aires (Argentina); Universidad Nacional de La Plata, Grupo de Gravitacion, Astrofisica y Cosmologia, Facultad de Ciencias Astronomicas y Geofisicas, La Plata (Argentina)

2016-03-15

Numerous theoretical studies using various equation of state models have shown that quark matter may exist at the extreme densities in the cores of high-mass neutron stars. It has also been shown that a phase transition from hadronic matter to quark matter would result in an extended mixed phase region that would segregate phases by net charge to minimize the total energy of the phase, leading to the formation of a crystalline lattice. The existence of quark matter in the core of a neutron star may have significant consequences for its thermal evolution, which for thousands of years is facilitated primarily by neutrino emission. In this work we investigate the effect a crystalline quark-hadron mixed phase can have on the neutrino emissivity from the core. To this end we calculate the equation of state using the relativistic mean-field approximation to model hadronic matter and a nonlocal extension of the three-flavor Nambu-Jona-Lasinio model for quark matter. Next we determine the extent of the quark-hadron mixed phase and its crystalline structure using the Glendenning construction, allowing for the formation of spherical blob, rod, and slab rare phase geometries. Finally we calculate the neutrino emissivity due to electron-lattice interactions utilizing the formalism developed for the analogous process in neutron star crusts. We find that the contribution to the neutrino emissivity due to the presence of a crystalline quark-hadron mixed phase is substantial compared to other mechanisms at fairly low temperatures (quark fractions (

Identification of hadronically decaying W bosons and top quarks using multivariate techniques at ATLAS

CERN Document Server

Nitta, Tatsumi; The ATLAS collaboration

2017-01-01

By colliding protons and examining particles emitted from the collisions, the Large Hadron Collider aims to study the interactions of quarks and gluons at the highest energies accessible in a controlled experimental way. In such collisions, W bosons or top quarks which have TeV scale momentum can be accessible. Reconstructing such boosted jets are becoming important. In particular, the ability to identify original particle that decays to quarks against normal QCD jets plays a central role in various searches at high energy scale. This is typically done by the use of a single physically motivated observable constructed from the constituents of the jet. In this work, multiple complementary observables are combined using boosted decision trees and neural networks to increase the ability to distinguish W bosons and top quarks from light quark jets in the ATLAS experiment.

The universality of the confining potential and the running of the quasi-Coulombic potential constant in the independent-quark model

International Nuclear Information System (INIS)

Khruschev, V.V.; Savrin, V.I.; Semenov, S.V.

1999-01-01

Parameters of the QCD-motivated static potential and the quark masses are calculated on the basis of the 1 -- meson mass spectra in the framework of the relativistic independent-quark model based on the Dirac equation. The value of the confining potential parameter is found to be (0.20 ± 0.01) GeV 2 for interactions between quarks and antiquarks independently on their flavors. The flavor independence of the confining potential is justified on the 5 x 10 -2 accuracy level both for the heavy quarks and for the light ones. The values of parameter α s , which is a strength of the quasi-Coulombic potential are consistent with the QCD-motivated decrease of α s at small interaction range [ru

Single photons, dileptons and hadrons from relativistic heavy ion collisions and quark-hadron phase transition

CERN Document Server

Srivastava, D K

2001-01-01

The production of single photons in Pb+Pb collisions at the CERN SPS as measured by the WA98 experiment is analysed. A quark gluon plasma is assumed to be formed initially, which expands, cools, hadronizes, and undergoes freeze-out. A rich hadronic equation of state is used and the transverse expansion of the interacting system is taken into account. The recent estimates of photon production in quark-matter (at two loop level) along with the dominant reactions in the hadronic matter leading to photons are used. About half of the radiated photons are seen to have a thermal origin. The same treatment and the initial conditions provide a very good description to hadronic spectra measured by several groups and the intermediate mass dileptons measured by the NA50 experiment, lending a strong support to the conclusion that quark gluon plasma has been formed in these collisions. Predictions for RHIC and LHC energies are also given. (37 refs).

Heavy flavours in ultra-relativistic heavy ions collisions; Les saveurs lourdes dans les collisions d'ions lourds ultra-relativistes

Energy Technology Data Exchange (ETDEWEB)

Rosnet, Ph

2008-01-15

The ultra-relativistic collisions of heavy ions are the today's only means to tackle in laboratory conditions the phase diagram in quantum chromodynamics and the strong interaction. The most recent theoretical studies predict a phase transition between the cold nuclear matter (a hadronic gas) and a plasma of quarks and gluons. Heavy flavour can characterize the nuclear matter produced in a heavy ion collision as well as its spatial-temporal evolution. Their study can be made through their decay into muons. The first part of this work presents the issue of ultra-relativistic heavy ion collisions and the role of heavy flavours. In the second part the author reviews the results of experiments performed at RHIC and particularly presents the analysis of the mass spectrum of dimuons in the Phenix experiment. The third part describes the muon trigger system of the Alice experiment at CERN and the expected performances for the study of di-muons.

Hot QCD equations of state and relativistic heavy ion collisions

Science.gov (United States)

Chandra, Vinod; Kumar, Ravindra; Ravishankar, V.

2007-11-01

We study two recently proposed equations of state obtained from high-temperature QCD and show how they can be adapted to use them for making predictions for relativistic heavy ion collisions. The method involves extracting equilibrium distribution functions for quarks and gluons from the equation of state (EOS), which in turn will allow a determination of the transport and other bulk properties of the quark gluon-plasma. Simultaneously, the method also yields a quasiparticle description of interacting quarks and gluons. The first EOS is perturbative in the QCD coupling constant and has contributions of O(g5). The second EOS is an improvement over the first, with contributions up to O[g6ln(1/g)]; it incorporates the nonperturbative hard thermal contributions. The interaction effects are shown to be captured entirely by the effective chemical potentials for the gluons and the quarks, in both cases. The chemical potential is seen to be highly sensitive to the EOS. As an application, we determine the screening lengths, which are, indeed, the most important diagnostics for QGP. The screening lengths are seen to behave drastically differently depending on the EOS considered and therefore yield a way to distinguish the two equations of state in heavy ion collisions.

Stress tensor of a quark moving through N=4 thermal plasma

International Nuclear Information System (INIS)

Friess, Joshua J.; Gubser, Steven S.; Michalogiorgakis, Georgios; Pufu, Silviu S.

2007-01-01

We develop the linear equations that describe graviton perturbations of AdS 5 -Schwarzschild generated by a string trailing behind an external quark moving with constant velocity. Solving these equations allows us to evaluate the stress tensor in the boundary gauge theory. Components of the stress tensor exhibit directional structures in Fourier space at both large and small momenta. We comment on the possible relevance of our results to relativistic heavy-ion collisions

Strangeness chemical equilibration in a quark-gluon plasma

International Nuclear Information System (INIS)

Letessier, Jean; Rafelski, Johann

2007-01-01

We study, in the dynamically evolving quark-gluon plasma (QGP) fireball formed in relativistic heavy ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC), the growth of strangeness yield toward and beyond the chemical equilibrium. We account for the contribution of the direct strangeness production and evaluate the thermal-QCD strangeness production mechanisms. The specific yield of strangeness per entropy, s/S, is the primary target variable. We explore the effect of collision impact parameter, i.e., fireball size, on kinetic strangeness chemical equilibration in QGP. Insights gained in studying the RHIC data with regard to the dynamics of the fireball are applied to the study of strangeness production at the LHC. We use these results and consider the strange hadron relative particle yields at RHIC and LHC in a systematic fashion. We consider both the dependence on s/S and the direct dependence on the participant number

Hadronic interactions from effective chiral Lagrangians of quarks and gluons

International Nuclear Information System (INIS)

Krein, G.

1996-06-01

We discuss the combined used of the techniques of effective chiral field theory and the field theoretic method known as Fock-Tani representation to derive effective hadron interactions. The Fock-Tani method is based on a change of representation by means of a unitary transformation such that the composite hadrons are redescribed by elementary-particle field operators. Application of the unitary transformation on the microscopic quark-quark interaction derived from a chiral effective Lagrangian leads to chiral effective interactions describing all possible processes involving hadrons and their constituents. The formalism is illustrated by deriving the one-pion-exchange potential between the nucleons using the quark-gluon effective chiral Lagrangian of Manohar and Georgi. We also present the results of a study of the saturation properties of the nuclear matter using this formalism. (author). 9 refs., 2 figs

Heavy flavours in ultra-relativistic heavy ions collisions

International Nuclear Information System (INIS)

Rosnet, Ph.

2008-01-01

The ultra-relativistic collisions of heavy ions are the today's only means to tackle in laboratory conditions the phase diagram in quantum chromodynamics and the strong interaction. The most recent theoretical studies predict a phase transition between the cold nuclear matter (a hadronic gas) and a plasma of quarks and gluons. Heavy flavour can characterize the nuclear matter produced in a heavy ion collision as well as its spatial-temporal evolution. Their study can be made through their decay into muons. The first part of this work presents the issue of ultra-relativistic heavy ion collisions and the role of heavy flavours. In the second part the author reviews the results of experiments performed at RHIC and particularly presents the analysis of the mass spectrum of dimuons in the Phenix experiment. The third part describes the muon trigger system of the Alice experiment at CERN and the expected performances for the study of di-muons

Transport quasiparticles and transverse interactions in quark-gluon plasmas

International Nuclear Information System (INIS)

Baym, Gordon

1996-01-01

Calculations of the properties of interacting quark-gluon plasmas are beset by infrared divergences associated with the fact that magnetic interactions, i.e., those occurring through exchange of transverse gluons, are, in the absence of a 'magnetic mass''in QCD, not screened. In this lecture we discuss the effects of magnetic interactions on the transport coefficients and the quasiparticle structure of quark-gluon plasmas. We describe how inclusion of dynamical screening effects - corresponding to Landau damping of the virtual quanta exchanged - leads to finite transport scattering rates. In the weak coupling limit, dynamical screening effects dominate over a magnetic mass. We illustrate the breakdown of the quasi particle structure of degenerate plasmas caused by long-ranged magnetic interactions, describe the structure of fermion quasiparticles in hot relativistic plasmas, and touch briefly on the problem of the lifetime of quasiparticle in the presence of long-ranged magnetic interactions. (author)

Quark matter 93

Energy Technology Data Exchange (ETDEWEB)

Otterlund, Ingvar; Ruuskanen, Vesa

1993-12-15

In his welcome address to the 10th International Conference on Ultra- Relativistic Nucleus-Nucleus Collisions (Quark Matter '93), held in Borlange, Sweden, from 20-24 June, Hans-Ake Gustafsson was puzzled why this year's conference was billed as the tenth in the series. He had tried to count but could only find eight forerunners - Bielefeld (1982), Brookhaven (1983), Helsinki (1984), Asilomar (1986), Nordkirchen (1987), Lenox (1988), Menton (1990), Gatlinburg (1991), making this year's meeting at Borlange the ninth. The answer was given by Helmut Satz in his introductory talk, pointing out that at the time of the Bielefeld meeting, a few conferences dealing with similar topics had already been held. The Bielefeld organizers thus did not consider their conference the first. Whatever its pedigree, the Borlange meeting covered particle production in highly excited and compressed nuclear matter, fluctuations and correlations, quark phenomena (quantum chromodynamics - QCD) in nuclear collisions, probes and signatures of Quark-Gluon Plasma (QGP), future collider experiments and instrumentation. The theoretical talks were split between the fundamental properties of the hot and dense matter at or near equilibrium, and the interface between theory and experiment. The phenomenological modelling of heavy ion collisions seems to reproduce at least all the main features of the data with hadrons, resonances and strings as the degrees of freedom. However secondary interactions among the produced hadrons or strings need to be added. Hydrodynamic calculations lead to results which reproduce the main features of the collisions. With increasing collision energy, the parton degrees of freedom become more important. Klaus Geiger described an ambitious scheme treating the whole nucleus-nucleus collision in terms of a kinetic parton (quark/gluon) cascade. The initial parton distribution at the beginning of the collision is determined from the quark-gluon nuclear structure and the

Quark matter 93

International Nuclear Information System (INIS)

Otterlund, Ingvar; Ruuskanen, Vesa

1993-01-01

In his welcome address to the 10th International Conference on Ultra- Relativistic Nucleus-Nucleus Collisions (Quark Matter '93), held in Borlange, Sweden, from 20-24 June, Hans-Ake Gustafsson was puzzled why this year's conference was billed as the tenth in the series. He had tried to count but could only find eight forerunners - Bielefeld (1982), Brookhaven (1983), Helsinki (1984), Asilomar (1986), Nordkirchen (1987), Lenox (1988), Menton (1990), Gatlinburg (1991), making this year's meeting at Borlange the ninth. The answer was given by Helmut Satz in his introductory talk, pointing out that at the time of the Bielefeld meeting, a few conferences dealing with similar topics had already been held. The Bielefeld organizers thus did not consider their conference the first. Whatever its pedigree, the Borlange meeting covered particle production in highly excited and compressed nuclear matter, fluctuations and correlations, quark phenomena (quantum chromodynamics - QCD) in nuclear collisions, probes and signatures of Quark-Gluon Plasma (QGP), future collider experiments and instrumentation. The theoretical talks were split between the fundamental properties of the hot and dense matter at or near equilibrium, and the interface between theory and experiment. The phenomenological modelling of heavy ion collisions seems to reproduce at least all the main features of the data with hadrons, resonances and strings as the degrees of freedom. However secondary interactions among the produced hadrons or strings need to be added. Hydrodynamic calculations lead to results which reproduce the main features of the collisions. With increasing collision energy, the parton degrees of freedom become more important. Klaus Geiger described an ambitious scheme treating the whole nucleus-nucleus collision in terms of a kinetic parton (quark/gluon) cascade. The initial parton distribution at the beginning of the collision is determined from the quark-gluon nuclear structure

Highlights from the Quark Matter 2012 conference: a theorist's perspective

CERN Multimedia

CERN. Geneva

2012-01-01

The series of Quark Matter conferences is traditionally the most important venue for showing new results in the field of ultra-relativistic nucleus-nucleus collisions. This year's edition was held in August in Washington DC and it attracted almost 700 participants. It featured the newest results from experiments at the LHC and at RHIC, as well as a broad range of new theoretical developments. This talk will provide - from a theorist's perspective - a selective review of results presented at this conference.

Experimental status of the AGS Relativistic Heavy Ion Program

International Nuclear Information System (INIS)

Sangster, T.C.

1994-10-01

The universal motivation for colliding large nuclei at relativistic energies is the expectation that a small volume of the primordial quark soup, generally referred to as the Quark-Gluon Plasma (QGP), can be created and studied. The QGP is formed via a phase transition caused by either the extreme baryon densities and/or the extreme temperatures achieved in the overlap zone of the two colliding nuclei. Experiments at the Brookhaven National Laboratory Alternating Gradient Synchrotron (AGS) using a beam of Si nuclei at 14.6 GeV per nucleon on various nuclear targets have been completed. These same experiments are now actively searching for signatures of QGP formation using a beam of Au nuclei at 11.7 GeV per nucleon. This paper briefly summarizes some of the key results from the Si beam program and the current status of the experimental Au beam program at the AGS

Relativistic impulse approximation and deuteron spin structure

International Nuclear Information System (INIS)

Tokarev, M.V.

1992-01-01

The fragmentation processes were considered of tensor- and vector-polarized deuterons to protons in the framework of the covariant approach in the light cone variables on the basis of the relativistic deuteron wave function with one nucleon on-mass shell. The experimental verification of predicted dependences of T 20 and K is of interest for the research of the momentum and spin distributions of high momentum deuteron constituents. 21 refs.; 6 figs

Electric polarizability of pions in the semirelativistic quark model; Ehlektricheskaya polyarizuemost' pionov v polurelyativistskoj kvarkovoj modeli

Energy Technology Data Exchange (ETDEWEB)

Maksimenko, N V [Gomel& #x27; skij Gosudarstvennyj Univ. im. F.Skoriny, Gomel (Belarus); Kuchin, S M [Filial Bryanskogo Gosudarstvennogo Univ. im. akademika I.G.Petrovskogo, Novozybkov (Russian Federation)

2012-07-01

In the paper the calculation is performed of the generalized and static polarizability of charged pions, which are considered as a relativistic system of two point spinor quarks with the linear interaction potential. The question of the relationship between static electricity and generalized polarizabilities of pions in the framework of this approach is studied.

Configuration space Faddeev calculations

International Nuclear Information System (INIS)

Payne, G.L.; Klink, W.H.; Polyzou, W.N.

1992-12-01

The detailed study of few-body systems provides one of the most precise tools for studying the dynamics of nuclei and nucleons. This research program consists of a careful theoretical study of few-body systems and methods for modeling these systems. During the past year several aspects of this program were completed. Brief summaries are given of work on the following topics: The relativistic three quark problem; the relativistic Balian-Brezin method; spin in light front quantum mechanical models; proton-deutron scattering and reactions; point form relativistic quantum mechanics of constituents; solutions of quantum mechanical anharmonic oscillators; shift operators and the U(N) multiplicity problem

PSR1987A: the case for strange-quark stars

International Nuclear Information System (INIS)

Glendenning, N.K.

1989-01-01

The new fast pulsar observed in the remnant of SN1987A, together with other considerations, provide evidence that there are two types of collapsed stars: neutron stars, having moderate central densities and subject to the usual mass constraint, and strange-quark-matter stars. We show that (i) all known pulsar masses and frequencies, with the exception of the new one, can be accounted for by plausible neutron star models; (ii) no known neutron star model can withstand the fast rotation of the new pulsar unless the central energy density is ∼ 15 that of normal nuclei, at which densities hadrons cannot plausibly exist as constituents; and (iii) if strange-quark matter is the true ground state of the strong interactions, strange-quark stars can sustain the high rotation imputed to the new pulsar. In the absence of another plausible structure that can withstand the fast rotation, we provisionally infer that the new pulsar is such a star. (author)

Dynamics of hadronization in ultra-relativistic nucleus-nucleus collisions

International Nuclear Information System (INIS)

Friman, B.L.

1986-01-01

One of the main problems in the search for quark-gluon plasma in ultra-relativistic nucleus-nucleus collisions is finding a reliable signature for deconfinement. Several signatures have been suggested, e.g., dileptons with a spectrum characteristic of the plasma, an increase in the number of strange particles and effects due to the hadronization of the plasma. In this talk I will describe some recent work on the effects of the hadronization transition in the central rapidity region within the hydrodynamic model of Bjorken, Kajantie and McLerran. (orig.)

Phase transition dynamics in ultra-relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Csernai, L.P.; Kapusta, J.I.; Kluge, G.Y.; Zabrodin, E.E.

1992-11-01

The authors investigate various problems related to the dynamics of a first-order phase transition from quark-gluon plasma to hadronic matter in ultra-relativistic heavy ion collisions. These include nucleation, growth and fusion of hadronic bubbles in either the Bjorken longitudinal hydrodynamic expansion model or the Cooper-Frye-Schonberg spherical hydrodynamic expansion model. With reasonable input parameters the conversion of one phase into the other is relatively close to the idealized adiabatic Maxwell construction, although one can choose parameters such that the conversion is strongly out of equilibrium. 10 refs., 7 figs

From the top-quark to the Higgs-Boson: the search for the heaviest particles of nature

International Nuclear Information System (INIS)

Mueller, T.

2001-01-01

According to our present knowledge the fundamental constituents of matter are quarks and leptons ordered by their mass into three particle families. With the discovery of the top quark about six years age our periodic table of elementary particles has been completed but the origin of its unusually high mass and, more general, of the mass of all particles, still needs to be established. The Institut fuer Experimentelle Kernphysik in Karlsruhe, who researches on the top quark and its properties, also takes part in the world-wide race for the discovery of the widely believed mediator of mass, the Higgs boson. (orig.)

Quark-gluon plasmas and collective features of nucleus-nucleus collisions at high energy

International Nuclear Information System (INIS)

Blaizot, J.P.

1987-05-01

This paper reviews some aspects of the dynamics of the quark-gluon plasmas which may be produced in ultra-relativistic heavy ion collisions. A space-time description of the central rapidity region is presented. It is shown that the hydrodynamical flow induces correlations between particle transverse momenta and multiplicities. One discusses to which extent these correlations could signal the occurrence of a phase transition in heavy ion collisions

Differential elliptic flow of identified hadrons and constituent quark number scaling at the GSI Facility for Antiproton and Ion Research (FAIR)

International Nuclear Information System (INIS)

Bhaduri, Partha Pratim; Chattopadhyay, Subhasis

2010-01-01

Differential elliptic flow v 2 (p T ) for identified hadrons is investigated in the FAIR energy regime, employing a hadronic-string transport model (UrQMD) as well as a partonic transport model (AMPT). It is observed that both models show a mass ordering of v 2 at low p T and a switch-over resulting in a baryon-meson crossing at intermediate p T . AMPT generates higher v 2 values compared to UrQMD. In addition, constituent quark number scaling behavior of elliptic flow is addressed. Scaling behavior in terms of the transverse momentum p T is found to be absent for both the partonic and the hadronic model. However, UrQMD and AMPT with a string melting scenario do exhibit an NCQ scaling of v 2 to varying degrees, with respect to the transverse kinetic energy KE T . But the default AMPT, where partonic scatterings are not included, does not show any considerable scaling behavior. A variable α is defined to quantify the degree of KE T scaling. We found that UrQMD gives better scaling than AMPT at FAIR.

Hadronic energy spectra from nuclear collisions: Effects from collective transverse flow and the phase transition to quark matter

International Nuclear Information System (INIS)

Heinz, U.

1988-11-01

I give an overview of the processes determining the shape of energy spectra of hadrons emitted in relativistic nuclear collisions, and discuss how one can extract from them information on the presence of collective transverse flow and on the transition to quark-gluon matter in such collisions. 6 refs., 3 figs

Two-Quark Condensate Changes with Quark Current Mass

International Nuclear Information System (INIS)

Lu Changfang; Lue Xiaofu; Wu Xiaohua; Zhan Yongxin

2009-01-01

Using the Schwinger-Dyson equation and perturbation theory, we calculate the two-quark condensates for the light quarks u, d, strange quark s and a heavy quark c with their current masses respectively. The results show that the two-quark condensate will decrease when the quark mass increases, which hints the chiral symmetry may be restored for the heavy quarks.

Proceedings of the Helmholtz international school physics of heavy quarks and hadrons (HQ2013)

International Nuclear Information System (INIS)

Ali, Ahmed; Bystritskiy, Yury; Ivanov, Mikhail

2014-07-01

The following topics were dealt with: Higgs boson production and couplings with the ATLAS detector, recent CMS results on heavy quarks and hadrons, mesons with open charm and beauty, new-physics searches in B→D (*) τν τ , spectroscopy and Regge trajectories of heavy quarkonia, weak decays of B s mesons, the possible role of scalar glueball-quarkonia mixing in the f 0 (1370,1500,17100) resonances produced in charmonia decays, effective weak Lagrangians in the Standard Model and B decays, heavy-quark physics in the covariant quark model, application of QCD sum rules to heavy-quark physics, top-quark production, helicity amplitudes and angular decay distributions, small-x behavior of deep-inelastic structure functions F 2 and F 2 cc , XYZ stated, recent Belle results, light and heavy hadrons in AdS/QCD, renorm dynamics, valence quarks and multiparticle production, prompt photons and associated b,c-tagged jet production within the k T factorization approach, heavy quarkonium production at the LHC in the framework of NRQCD and parton Reggeization approach, light-cone distribution amplitudes of bottom baryons, rare semileptonic B + → π + l + l - decay, bimodality phenomenon in finite and infinite systems within an exactly solvable statistical model, CP violation in D meson decays, the scalar mesons in multichannel ππ scattering and decays of the ψ and Υ families, the latest results of the ATLAS experiment on heavy-quark physics, relativistic corrections to pair charmonium production at the LHC, the rise and fall of the fourth quark-lepton generation. (HSI)

The strongly coupled quark-gluon plasma created at RHIC

CERN Document Server

Heinz, Ulrich W

2009-01-01

The Relativistic Heavy Ion Collider (RHIC) was built to re-create and study in the laboratory the extremely hot and dense matter that filled our entire universe during its first few microseconds. Its operation since June 2000 has been extremely successful, and the four large RHIC experiments have produced an impressive body of data which indeed provide compelling evidence for the formation of thermally equilibrated matter at unprecedented temperatures and energy densities -- a "quark-gluon plasma (QGP)". A surprise has been the discovery that this plasma behaves like an almost perfect fluid, with extremely low viscosity. Theorists had expected a weakly interacting gas of quarks and gluons, but instead we seem to have created a strongly coupled plasma liquid. The experimental evidence strongly relies on a feature called "elliptic flow" in off-central collisions, with additional support from other observations. This article explains how we probe the strongly coupled QGP, describes the ideas and measurements whi...

Jetted GRBs, afterglows and SGRs from quark stars birth

CERN Document Server

Dar, Arnon

1999-01-01

Recent studies suggest that when cold nuclear matter is compressed to high nuclear densities, diquarks with spin zero and antisymmetric color wave function Bose condensate into a superfluid/superconducting state that is several times as dense. Various astrophysical phenomena may be explained by gravitational collapse of neutron stars (NSs) to (di)quark stars (QSs) as a result of a first order phase transition in NSs within $\\sim 10^{4}$ years after their birth in supernova explosions, when they cooled and spun down sufficiently (by magnetic braking ?). The gravitational energy release drives an explosion which may eject both highly relativistic narrowly collimated jets and a mildly relativistic ``spherical'' shell. The slow contraction/cooling of the remnant QSs can power soft gamma ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs), without invoking a huge magnetic energy storage. The jets can produce the observed gamma ray bursts (GRBs) in distant galaxies when they happen to point in our direction and...

A quark structure of hadrons and nuclei

International Nuclear Information System (INIS)

Chakrabarty, S.; Deoghuria, S.

1992-08-01

In this review we look into the recent understanding of mesons, baryons and nuclei as few quark bound states within the framework of quantum chromodynamics (QCD). In particular, we have reviewed our understanding of the nature of confining interaction, the spin - dependence of colour forces and the role of non-perturbative effects in the study of quark forces in the potential model approach. We also give a comparative study of results obtained by several potential models with reference to the experimental data. We find that although the Lorentz nature of confinement and the nature of spin-dependent colour forces have been better understood now, only a partial understanding of these problems are obtained so far. Our study reveals that properties of baryons could be explained by the same potential model which successfully describe the mesons. However, the nuclei require chiral symmetry and non-perturbative methods for their description. We also discuss the relation between constituent, current and dynamical quark masses. We conclude that QCD motivated approaches have shown much success in explaining many results on hadronic and nuclear data. (author). 212 refs, 14 tabs

Heavy hadron spectroscopy: A quark model perspective

International Nuclear Information System (INIS)

Vijande, J.; Valcarce, A.; Caramés, T.F.; Garcilazo, H.

2013-01-01

We present recent results of hadron spectroscopy and hadron–hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher order Fock space components in the hadron spectra and the connection of this extension with the hadron–hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory

PREFACE: Quark Matter 2006 Conference

Science.gov (United States)

Ma, Yu-Gang; Wang, En-Ke; Cai, Xu; Huang, Huan-Zhong; Wang, Xin-Nian; Zhu, Zhi-Yuan

2007-07-01

The Quark Matter 2006 conference was held on 14 20 November 2006 at the Shanghai Science Hall of the Shanghai Association of Sciences and Technology in Shanghai, China. It was the 19th International Conference on Ultra-Relativistic Nucleus Nucleus Collisions. The conference was organized jointly by SINAP (Shanghai Institute of Applied Physics, Chinese Academy of Sciences (CAS)) and CCNU (Central China Normal University, Wuhan). Over 600 scientists from 32 countries in five continents attended the conference. This is the first time that China has hosted such a premier conference in the field of relativistic heavy-ion collisions, an important event for the Chinese high energy nuclear physics community. About one half of the conference participants are junior scientists—a clear indication of the vigor and momentum for this field, in search of the fundamental nature of the nuclear matter at extreme conditions. Professor T D Lee, honorary chair of the conference and one of the founders of the quark matter research, delivered an opening address with his profound and philosophical remarks on the recent discovery of the nature of strongly-interacting quark-gluon-plasma (sQGP). Professor Hongjie Xu, director of SINAP, gave a welcome address to all participants on behalf of the two hosting institutions. Dr Peiwen Ji, deputy director of the Mathematics and Physics Division of the Natural Science Foundation of China (NSFC), also addressed the conference participants and congratulated them on the opening of the conference. Professor Mianheng Jiang, vice president of the Chinese Academy of Sciences (CAS), gave a concise introduction about the CAS as the premier research institution in China. He highlighted continued efforts at CAS to foster international collaborations between China and other nations. The Quark Matter 2006 conference is an example of such a successful collaboration between high energy nuclear physicists in China and other nations all over the world. The

Quarks

Energy Technology Data Exchange (ETDEWEB)

Shekhter, V [AN SSSR, Leningrad. Inst. Yadernoj Fiziki

1981-04-01

The history is described of the concept of quarks, ie., hypothetical particles of which,hadrons (strongly interacting particles) are believed to consist. The quark properties differ from those of known elementary particles. The electric charge of quarks is 1/3 and 2/3 of the electron charge and they obviously only exist inside hadrons. Quark existence is generally recognized because it has been confirmed by experimental verification of predictions made using a quark model.

Relativistic Few-Body Hadronic Physics Calculations

Energy Technology Data Exchange (ETDEWEB)

Polyzou, Wayne [Univ. of Iowa, Iowa City, IA (United States)

2016-06-20

The goal of this research proposal was to use ``few-body'' methods to understand the structure and reactions of systems of interacting hadrons (neutrons, protons, mesons, quarks) over a broad range of energy scales. Realistic mathematical models of few-hadron systems have the advantage that they are sufficiently simple that they can be solved with mathematically controlled errors. These systems are also simple enough that it is possible to perform complete accurate experimental measurements on these systems. Comparison between theory and experiment puts strong constraints on the structure of the models. Even though these systems are ``simple'', both the experiments and computations push the limits of technology. The important property of ``few-body'' systems is that the ``cluster property'' implies that the interactions that appear in few-body systems are identical to the interactions that appear in complicated many-body systems. Of particular interest are models that correctly describe physics at distance scales that are sensitive to the internal structure of the individual nucleons. The Heisenberg uncertainty principle implies that in order to be sensitive to physics on distance scales that are a fraction of the proton or neutron radius, a relativistic treatment of quantum mechanics is necessary. The research supported by this grant involved 30 years of effort devoted to studying all aspects of interacting two and three-body systems. Realistic interactions were used to compute bound states of two- and three-nucleon, and two- and three-quark systems. Scattering observables for these systems were computed for a broad range of energies - from zero energy scattering to few GeV scattering, where experimental evidence of sub-nucleon degrees of freedom is beginning to appear. Benchmark calculations were produced, which when compared with calculations of other groups provided an essential check on these complicated calculations. In

Adler function for light quarks in analytic perturbation theory

International Nuclear Information System (INIS)

Milton, K. A.; Solovtsov, I. L.; Solovtsova, O. P.

2001-01-01

The method of analytic perturbation theory, which avoids the problem of ghost-pole-type singularities and gives a self-consistent description of both spacelike and timelike regions, is applied to describe the 'light' Adler function corresponding to the nonstrange vector channel of the inclusive decay of the τ lepton. The role of threshold effects is investigated. The behavior of the quark-antiquark system near threshold is described by using a new relativistic resummation factor. It is shown that the method proposed leads to good agreement with the 'experimental' Adler function down to the lowest energy scale

Hot and dense matter in compact stars - from nuclei to quarks

International Nuclear Information System (INIS)

Hempel, Matthias

2010-01-01

This dissertation deals with the equation of state of hot and dense matter in compact stars, with special focus on first order phase transitions. A general classification of first order phase transitions is given and the properties of mixed phases are discussed. Aspects of nucleation and the role of local constraints are investigated. The derived theoretical concepts are applied to matter in neutron stars and supernovae, in the hadron-quark and the liquid-gas phase transition. For the detailed description of the liquid-gas phase transition a new nuclear statistical equilibrium model is developed. It is based on a thermodynamic consistent implementation of relativistic mean-field interactions and excluded volume effects. With this model different equation of state tables are calculated and the composition and thermodynamic properties of supernova matter are analyzed. As a first application numerical simulations of core-collapse supernovae are presented. For the hadron-quark phase transition two possible scenarios are studied in more detail. First the appearance of a new mixed phase in a proto neutron star and the implications on its evolution. In the second scenario the consequences of the hadron-quark transition in corecollapse supernovae are investigated. Simulations show that the appearance of quark matter has clear observable signatures and can even lead to the generation of an explosion. (orig.)

Hot and dense matter in compact stars - from nuclei to quarks

Energy Technology Data Exchange (ETDEWEB)

Hempel, Matthias

2010-10-19

This dissertation deals with the equation of state of hot and dense matter in compact stars, with special focus on first order phase transitions. A general classification of first order phase transitions is given and the properties of mixed phases are discussed. Aspects of nucleation and the role of local constraints are investigated. The derived theoretical concepts are applied to matter in neutron stars and supernovae, in the hadron-quark and the liquid-gas phase transition. For the detailed description of the liquid-gas phase transition a new nuclear statistical equilibrium model is developed. It is based on a thermodynamic consistent implementation of relativistic mean-field interactions and excluded volume effects. With this model different equation of state tables are calculated and the composition and thermodynamic properties of supernova matter are analyzed. As a first application numerical simulations of core-collapse supernovae are presented. For the hadron-quark phase transition two possible scenarios are studied in more detail. First the appearance of a new mixed phase in a proto neutron star and the implications on its evolution. In the second scenario the consequences of the hadron-quark transition in corecollapse supernovae are investigated. Simulations show that the appearance of quark matter has clear observable signatures and can even lead to the generation of an explosion. (orig.)

Search for vector-like T' quarks using tools for the analysis of jet substructure with the CMS experiment

CERN Document Server

Höing, Rebekka Sophie; Haller, Johannes

2015-01-01

A search for pairs of vector-like T' quark produced in proton-proton collisions recorded with the CMS experiment at p s = 8 TeV is presented. The search is optimized for decays of T' quarks to top quarks and Higgs bosons, where the top quarks and Higgs bosons decay hadronically. The T'-quark mass range between 500 and 1000 GeV is investigated. The top quarks and Higgs bosons produced in decays of the heavy T' quarks acquire large Lorentz boosts. The signatures of these particles in the detector can overlap and are therefore dicult to resolve using classical jet reconstruction methods. Large-radius jets are reconstructed and subjets formed from their constituents. The decay products of particles with large Lorentz boosts are highly collimated and can all be found within a single one of these large-radius jets. Top jets containing hadronic top-quark decays are identied with a top-tagging algorithm that analyzes the jet substructure. A b-tagging algorithm is applied to the reconstructed subjets in order to nd bo...

Oxygen induced reactions at 200 and 60 GeV/nucleon

International Nuclear Information System (INIS)

Gutbrod, H.H.; Albrecht, R.; Claesson, G.; Bock, R.; Kolb, B.W.; Lund, I.; Schmidt, H.R.; Siemiarczuk, T.; Awes, T.C.; Baktash, C.; Ferguson, R.L.; Johnson, J.W.; Lee, I.Y.; Obenshain, F.E.; Plasil, F.; Sorensen, S.P.; Young, G.R.

1988-01-01

The ultimate goal of ultra-relativistic heavy ion physics is the creation and detection of a new form of matter, the so-called Quark-Gluon Plasma (QGP). The QGP is a state of matter in which normal nuclear matter has been compressed to such an extent that the color force field between the constituents of the nucleon is sufficiently screened that a deconfinement phase transition takes place [Sa86]. It is widely believed that the early universe, some 10 -6 seconds after its creation, consisted of this form of primordial matter. This paper shows the space-time evolution of quark matter, created in the laboratory by means of the ultra-relativistic collision of two heavy nuclei. If two nuclei of high energy collide, they will create a zone of hot and dense matter, eventually having an energy density high enough to melt the individual nucleons into a soup of freely moving quarks and gluons, the above described QGP. The QGP will rapidly expand, and quarks will hadronize, mainly into charged and neutral mesons. The (very difficult) experimental task is to search amongst and amidst the abundantly created mesons for signatures of the early QGP phase

Space-Time Geometry of Quark and Strange Quark Matter

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

We study quark and strange quark matter in the context of general relativity. For this purpose, we solve Einstein's field equations for quark and strange quark matter in spherical symmetric space-times. We analyze strange quark matter for the different equations of state (EOS) in the spherical symmetric space-times, thus we are able to obtain the space-time geometries of quark and strange quark matter. Also, we discuss die features of the obtained solutions. The obtained solutions are consistent with the results of Brookhaven Laboratory, i.e. the quark-gluon plasma has a vanishing shear (i.e. quark-gluon plasma is perfect).

Prediction of new Quarks, Generations and Quark Masses

Science.gov (United States)

Lach, Thedore

2002-04-01

The Standard model currently suggests no relationship between the quark and lepton masses. The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an up quark mass of 237.31 MeV/c2 and a dn quark mass of 42.392 MeV/c2. These two new quarks help explain the numerical relationship between all the quark and lepton masses in a single function. The mass of each SNU-P (quark or lepton) is just the geometric mean of two related SNU-Ps, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.743828 (predicted), 117.3520, 1778.38, 26950.08 MeV. The resulting slope of these masses when plotted on semi log paper is "e" to 5 significant figures using the currently accepted mass for Tau. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these quarks, and lepton.

Construction of six-quark states from parity eigenfunctions for n-n processes

International Nuclear Information System (INIS)

Stancu, F.; Wilets, L.

1987-01-01

The work presented is to classify and construct six-quark states as totally antisymmetric states of six fermions, each described by orbital, spin, isospin, and color degrees of freedom. A classification scheme is proposed based on parity eigenfunctions. The single-particle hamiltonian is assumed to be reflectionally and axially symmetric and can be obtained, for example, from constrained Hartree-Fock or solition mean field theories. The ultimate aim is to study N-N processes in the context of the (relativistic) soliton bag model

The calculation of multiquark hadrons by the quark model baryon, meson and multiquark states

International Nuclear Information System (INIS)

Takeuchi, Sachiko; Takizawa, Makoto; Yasui, Shigehiro

2011-01-01

The 1st new hadron summer school related with the new science field, 'the comprehensive research of new hadron states searched by variable flavor number scheme', was held on August 18-20, 2010. This report is one of the 'quark model' lectures. The chapter 1 describes following problems: 1. The background and the significance as a phenomenological theory of the constituent quark model. 2. The introduction of the quark model. 3. The summary of the properties of hadrons in which the quark model can apply to three quarks (qqq) and, one quark and antiquark (q - q) configurations, but is difficult to apply to some configurations. 4. A brief summary of exotic hadrons and recent problems. In chapter 2, the introduction and some exercises of the stochastic variational method are reported as a technique of solving spatial part of multiquark states. In the chapter 3, spins and color parts in multiquark states are calculated. The group theory is applied to calculate the eigenvalues of the Casimir operators of SU(2), SU(3) and SU(6). In the problems of being unable to apply Casimir operators, the direct matrix diagonalization method, m-scheme, is employed for interacting quarks and for the interaction involving quark mass. To find the attractive interaction in tetraquark (QQqq-bar) state is given as an exercise problem. (Y. Kazumata)

Towards a non-perturbative matching of HQET and QCD with dynamical light quarks

International Nuclear Information System (INIS)

Della Morte, M.; Simma, H.; Sommer, R.

2007-10-01

We explain how the strategy of solving renormalization problems in HQET non-perturbatively by a matching to QCD in finite volume can be implemented to include dynamical fermions. As a primary application, some elements of an HQET computation of the mass of the b-quark beyond the leading order with N f =2 are outlined. In particular, the matching of HQET and QCD requires relativistic QCD simulations in a volume with L∼0.5 fm, which will serve to quantitatively determine the heavy quark mass dependence of heavy-light meson observables in the continuum limit of finite-volume two-flavour lattice QCD. As a preparation for the latter, we report on our determination of the renormalization constants and improvement coefficients relating the renormalized current and subtracted bare quark mass in the relevant weak coupling region. The calculation of these coefficients employs a constant physics condition in the Schrodinger functional scheme, where the box size L is fixed by working at a prescribed value of the renormalized coupling. (orig.)

Towards a non-perturbative matching of HQET and QCD with dynamical light quarks

Energy Technology Data Exchange (ETDEWEB)

Della Morte, M. [CERN, Geneva (Switzerland). Physics Dept.; Fritzsch, P.; Heitger, J. [Muenster Univ. (Germany). Inst. fuer Theoretische Physik 1; Meyer, H.B. [Massachusets Institute of Technology, Center for Theoretical Physics, Cambridge, MA (United States); Simma, H.; Sommer, R. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2007-10-15

We explain how the strategy of solving renormalization problems in HQET non-perturbatively by a matching to QCD in finite volume can be implemented to include dynamical fermions. As a primary application, some elements of an HQET computation of the mass of the b-quark beyond the leading order with N{sub f} =2 are outlined. In particular, the matching of HQET and QCD requires relativistic QCD simulations in a volume with L{approx}0.5 fm, which will serve to quantitatively determine the heavy quark mass dependence of heavy-light meson observables in the continuum limit of finite-volume two-flavour lattice QCD. As a preparation for the latter, we report on our determination of the renormalization constants and improvement coefficients relating the renormalized current and subtracted bare quark mass in the relevant weak coupling region. The calculation of these coefficients employs a constant physics condition in the Schrodinger functional scheme, where the box size L is fixed by working at a prescribed value of the renormalized coupling. (orig.)

Susceptibilities of conserved quantities in relativistic heavy-ion collisions at RHIC

International Nuclear Information System (INIS)

Chatterjee, A.; Nayak, T.K.; Chatterjee, S.; Sahoo, N.R.

2016-01-01

The major motivations of heavy-ion collisions at ultra-relativistic energies is to study the formation of new form of matter, called quark-gluon plasma (QGP) and study its basic properties. Susceptibilities of conserved quantities, such as electric charge, baryon number and strangeness are sensitive to the onset of quantum chromodynamics (QCD) phase transition, and provide information on the mater produce in heavy ion collisions. In this work, we have used the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) and the hadron resonance gas (HRG) models to analyzes the 2"n"d order susceptibilities of conserved charges. In experiments, one needs to understand and correct for detector acceptance, efficiency and limited particle identification in order to interpret the results and compare with theoretical calculations. The transverse momentum cutoff dependence of suitably normalized susceptibilities are proposed as useful observables to probe the properties of the medium at freezout

KN s-wave phase shifts in the non-relativistic quark model

International Nuclear Information System (INIS)

Silvestre-Brac, B.; Labarsouque, J.

1995-01-01

The I=1 and 0 kaon-nucleon s-wave phase shifts have been calculated in a quark potential model using the resonating group method (RGM). The Hill-Wheeler equation has been solved numerically without any parametrization of the KN relative wave-function. The kaon and the nucleon wave-functions have been expanded as sums of several well-chosen gaussian functions, and the sensitivity of the results to the number of terms was analyzed carefully. The I=0 phase shifts are in agreement with the experimental data. In the I=1 channel too much repulsion is obtained, probably due to the lack of medium-range boson exchange type attraction. ((orig.))

Open heavy flavor and other hard probes in ultra-relativistic heavy-ion collisions

OpenAIRE

Uphoff, Jan

2014-01-01

In this thesis hard probes are studied in the partonic transport model BAMPS (Boltzmann Approach to MultiParton Scatterings). Employing Monte Carlo techniques, this model describes the 3+1 dimensional evolution of the quark gluon plasma phase in ultra-relativistic heavy-ion collisions by propagating all particles in space and time and carrying out their collisions according to the Boltzmann equation. Since hard probes are produced in hard processes with a large momentum transfer, the value of...

Relativistic actions for bound-states and applications in the meson spectroscopy; Acoes relativisticas para estados ligados e aplicacoes na espectroscopia de mesons

Energy Technology Data Exchange (ETDEWEB)

Silva Carvalho, Hendly da

1991-08-01

We study relativistic equations for bound states of two-body systems using Dirac`s constraint formalism and supersymmetry. The two-body system can be of spinless particles, one of them spinning and the other one spinless, or both of them spinning. The interaction is described by scalar, timelike four-vector and spacelike four-vector potentials under Lorentz transformations. As an application we use the relativistic wave equation for two scalar particles and calculate the mass spectra of the mesons treating them as spinless quark-antiquark bound states. The interaction potential in this case is a convenient adaptation of the potential employed in non-relativistic calculations. Finally, we compare our results with more recent experimental data and with theoretical results obtained with the same potential used by us but with a non-relativistic wave equation. We also compare our results with results obtained with the relativistic wave equation but with a different interaction potential. (author). 38 refs, 9 figs, 8 tabs.

Singular charge density at the center of the pion?

International Nuclear Information System (INIS)

Miller, Gerald A.

2009-01-01

We relate the three-dimensional infinite momentum frame spatial charge density of the pion to its electromagnetic form factor F π (Q 2 ). Diverse treatments of the measured form factor data including phenomenological fits, nonrelativistic quark models, the application of perturbative quantum chromodynamics (QCD), QCD sum rules, holographic QCD, and the Nambu-Jona-Lasinio (NJL) model all lead to the result that the charge density at the center of the pion has a logarithmic divergence. Relativistic constituent quark models do not display this singularity. Future measurements planned for larger values of Q 2 may determine whether or not a singularity actually occurs.

Di-Jet Conical Correlations Associated with Heavy Quark Jets in anti-de Sitter Space/Conformal Field Theory Correspondence

International Nuclear Information System (INIS)

Noronha, Jorge; Gyulassy, Miklos; Torrieri, Giorgio

2009-01-01

We show that far zone Mach and diffusion wake 'holograms' produced by supersonic strings in anti-de Sitter space/conformal field theory (AdS/CFT) correspondence do not lead to observable conical angular correlations in the strict N c →∞ supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium 'neck' zone near the jet is shown to produce an apparent sonic boom azimuthal angle distribution that is roughly independent of the heavy quark's velocity. Our results indicate that a measurement of the dependence of the away-side correlations on the velocity of associated identified heavy quark jets at the BNL Relativistic Heavy Ion Collider and CERN LHC will provide a direct test of the nonperturbative dynamics involved in the coupling between jets and the strongly coupled quark-gluon plasma implied by AdS/CFT correspondence

Di-jet conical correlations associated with heavy quark jets in anti-de sitter space/conformal field theory correspondence.

Science.gov (United States)

Noronha, Jorge; Gyulassy, Miklos; Torrieri, Giorgio

2009-03-13

We show that far zone Mach and diffusion wake "holograms" produced by supersonic strings in anti-de Sitter space/conformal field theory (AdS/CFT) correspondence do not lead to observable conical angular correlations in the strict N_{c}-->infinity supergravity limit if Cooper-Frye hadronization is assumed. However, a special nonequilibrium "neck" zone near the jet is shown to produce an apparent sonic boom azimuthal angle distribution that is roughly independent of the heavy quark's velocity. Our results indicate that a measurement of the dependence of the away-side correlations on the velocity of associated identified heavy quark jets at the BNL Relativistic Heavy Ion Collider and CERN LHC will provide a direct test of the nonperturbative dynamics involved in the coupling between jets and the strongly coupled quark-gluon plasma implied by AdS/CFT correspondence.

Quark Condensate in the Strange Matter

Institute of Scientific and Technical Information of China (English)

LU Chang-Fang; LU" Xiao-Fu

2003-01-01

In a nonlinear chiral SU(3) framework, we investigate the quark condensate in the strange matter including N, Σ, Ξ, and Λ, making use of chiral symmetry spontaneous breaking Lagrangian and mean-field approximation. The results show that the chiral symmetry is restored partially when the strange matter density increases and that 〈π→2〉 plays a very important role in the strange matter which may approach the constituents of the neutron stars. In addition, we can find that the strange matter density where the π-condensate emerges leads to the ratio of the nucleon number to baryon number.

Probing the specific entropy produced in ultra-relativistic heavy-ion collisions with a silicon pixel multiplicity detector: a simulation study

Czech Academy of Sciences Publication Activity Database

Antinori, F.; Balada, A.; Barbera, R.; Staroba, Pavel; Závada, Petr

2000-01-01

Roč. 452, - (2000), s. 323-337 ISSN 0168-9002 Institutional research plan: CEZ:AV0Z1010920 Keywords : ultra-relativistic * heavy-ion collisions * nuclear matter * phase diagram * hadron gas * Quark Gluon Plasma * particle multiplicity * transverse momentum spectra Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 0.964, year: 2000

First observation of ΛO, bar ΛO, ΚsO production in relativistic heavy ion collisions at the AGS

International Nuclear Information System (INIS)

Hallman, T.; Madansky, L.; Welsh, R.; Bonner, B.E.; Krishna, N.; Kruk, J.; Mutchler, G.S.; Nessi, M.; Nessi-Tedaldi, F.; Tonse, S.; Eiseman, S.E.; Etkin, A.; Foley, K.J.; Hackenburg, R.W.; Longacre, R.S.; Love, W.A.; Morris, T.W.; Saulys, A.C.; Lindenbaum, S.J.; Kramer, M.A.; Chan, C.S.

1990-01-01

A topic presently of considerable discussion is the character and evolution of the hot, dense matter thought to be formed when relativistic nuclei undergo catastrophic central collisions. The concentration of strange matter in such reactions is of some interest in this regard. Were a plasma of quarks and gluons formed, one might expect to observe a substantial increase in the concentration of strange matter, as a consequence of Pauli-blocking of u, d, quark production. The authors report here the first observation of inclusive Λ O , bar Λ O , Κ s O production in nucleus-nucleus collisions at 14.5 GeV/n

Prediction of new Quarks, Generations & low Mass Quarks

Science.gov (United States)

Lach, Theodore

2003-04-01

The CBM (model) of the nucleus has resulted in the prediction of two new quarks, an "up" quark of mass 237.31 MeV/c2 and a "dn" quark of mass 42.392 MeV/c2. These two new predicted quarks helped to determine that the masses of the quarks and leptons are all related by a geometric progression relationship. The mass of each quark or lepton is just the "geometric mean" of two related elementary particles, either in the same generation or in the same family. This numerology predicts the following masses for the electron family: 0.511000 (electron), 7.74 (predicted), 117.3, 1778.4 (tau), 26950.1 MeV. The geometric ratio of this progression is 15.154 (e to the power e). The mass of the tau in this theory agrees very well with accepted values. This theory suggests that all the "dn like" quarks have a mass of just 10X multiples of 4.24 MeV (the mass of the "d" quark). The first 3 "up like" quark masses are 38, 237.31 and 1500 MeV. This theory also predicts a new heavy generation with a lepton mass of 27 GeV, a "dn like" quark of 42.4 GeV, and an "up like" quark of 65 GeV. Significant evidence already exists for the existence of these new quarks, and lepton. Ref. Masses of the Sub-Nuclear Particles, nucl-th/ 0008026, @ http://xxx.lanl.gov. Infinite Energy, Vol 5, issue 30.

Thermal evolution of massive strange compact objects in a SU(3) chiral Quark Meson model

Energy Technology Data Exchange (ETDEWEB)

Zacchi, Andreas

2017-07-04

In this work, thermodynamical properties of strongly interacting matter within a chiral SU(2)- and SU(3) chiral Quark Meson model have been analysed. Both effective models describe the development of the quark masses in media via the corresponding fields through chiral symmetry, which is expected to be restored at high temperatures and/or high densities, and spontaneously broken at low temperatures and/or densities. Spontaneous and explicit chiral symmetry breaking patterns give rise to massive Goldstone bosons, which are associated with the pions. Their chiral partners, the sigma mesons, are expected to be degenerate in mass, which was what we studied and observed at large temperatures/densities. The derivation and computation of thermodynamical quantities and properties in both cases can for instance be used to study relativistic and hydrodynamic Heavy Ion Collisions and the early universe for vanishing baryon number (SU(2)-case). They are also interesting for extreme astrophysical scenarios, such as Supernova explosions and the thermal evolution of their remnants, which has been among the topics of this thesis (SU(3)-case). Inclusion of the zero point energy in the SU(2) model has been carried out separately for the meson sector and for the quark sector as well as in a combined approach, where we learned, that the quark sector is quite dominant and that the vacuum fluctuations of the meson fields have little influence on the order parameter, but affect the relativistic degrees of freedom. In the SU(3) case, the inclusion of the zero point energy in the quark sector is much more computationally complex, but, as in the SU(2) case, is also not negliable, as its influence also changes the thermodynamical quantities at finite temperatures in a nontrivial manner. Here some features of the Supernova equation of state have been studied, which look promising for further investigations for Supernovae (proto neutron stars) and also for compact star mergers. The final

Interplay Between Quark-Antiquark and Diquark Condensates in Vacuum in a Two-Flavor Nambu-Jona-Lasinio Model

Institute of Scientific and Technical Information of China (English)

ZHOU Bang-Rong

2007-01-01

By means of a relativistic effective potential, we analytically research competition between the quarkLasinio (NJL) model and obtain the Gs-Hs phase diagram, where Gs and Hs are the respective four-fermion coupling constants in scalar quark-antiquark channel and scalar color anti-triplet diquark channel. The results show that, in the that there is no diquark condensates in the vacuum of QCD, will also impose a real restriction to any given two-flavor NJL model which is intended to simulate QCD, i.e. in such model the resulting snallest ratio Gs/Hs after the Fierz transformations in the Hartree approximation must be larger than 2/3. A few phenomenological QCD-like NJL models are checked and analyzed.

Temperature anomalies of shock and isentropic waves of quark-hadron phase transition

Science.gov (United States)

Konyukhov, A. V.; Iosilevskiy, I. L.; Levashov, P. R.; Likhachev, A. P.

2018-01-01

In this work, we consider a phenomenological equation of state, which combinesstatistical description for hadron gas and a bag-model-based approach for the quark-gluon plasma. The equation of state is based on the excluded volume method in its thermodynamically consistent variant from Satarov et al [2009 Phys. At. Nucl. 72 1390]. The characteristic shape of the Taub adiabats and isentropes in the phase diagram is affected by the anomalous pressure-temperature dependence along the curve of phase equilibrium. The adiabats have kink points at the boundary of the two-phase region, inside which the temperature decreases with compression. Thermodynamic properties of matter observed in the quark-hadron phase transition region lead to hydrodynamic anomalies (in particular, to the appearance of composite compression and rarefaction waves). On the basis of relativistic hydrodynamics equations we investigate and discuss the structure and anomalous temperature behavior in these waves.

Chemical Potential Dependence of the Dressed-Quark Propagator from an Effective Quark-Quark Interaction

Institute of Scientific and Technical Information of China (English)

ZONG Hong-Shi; PING Jia-Lun; SUN Wei-Min; CHANG Chao-Hsi; WANG Fan

2002-01-01

We exhibit a method for obtaining the low chemical potential dependence of the dressed quark propagatorfrom an effective quark-quark interaction model. Within this approach we explore the chemical potential dependenceof the dressed-quark propagator, which provides a means of determining the behavior of the chiral and deconfinementorder parameters. A comparison with the results of previous researches is given.

The ρ - ω mass difference in a relativistic potential model with pion corrections

International Nuclear Information System (INIS)

Palladino, B.E.; Ferreira, P.L.

1988-01-01

The problem of the ρ - ω mass difference is studied in the framework of the relativistic, harmonic, S+V independent quark model implemented by center-of-mass, one-gluon exchange and plon-cloud corrections stemming from the requirement of chiral symmetry in the (u,d) SU(2) flavour sector of the model. The plonic self-energy corrections with different intermediate energy states are instrumental of the analysis of the problem, which requires and appropriate parametrization of the mesonic sector different from that previously used to calculate the mass spectrum of the S-wave baryons. The right ρ - ω mass splitting is found, together with a satisfactory value for the mass of the pion, calculated as a bound-state of a quark-antiquark pair. An analogous discussion based on the cloudy-bag model is also presented. (author) [pt

Quarks and partons

International Nuclear Information System (INIS)

Close, F.E.

1976-01-01

The studies of inelastic electron scattering at SLAC and of neutrino scattering at CERN have been widely interpreted as giving support to the idea that the nucleon is built from elementary constituents, called partons, and that these partons have the same quantum numbers as the quarks that are familiar in spectroscopy. In particular, a very simple regularity in the data, known as scale invariance or just 'scaling' was seen at least at moderate energies (2 2 > approximately 1 GeV) which is natural in the parton model. The data on e + e - annihilation also appear to be consistent with scaling when Esub(cm) approximately 5 GeV. These lectures are concerned with the scaling phenomena. One may expect the new hadronic degree of freedom to generate scaling violations in inelastic electron and neutrino scattering. These are mentioned briefly in these lectures. (Auth.)

Exactly solvable model of phase transition between hadron and quark-gluon-matter

International Nuclear Information System (INIS)

Gorenstein, M.I.; Petrov, V.K.; Shelest, V.P.; Zinovjev, G.M.

1982-01-01

An exactly solvable model of phase transition between hadron and quark-gluon matter is proposed. The hadron phase of this model is considered as a gas of bags filled by point massless constituents. The mass and volume spectrum of the bag is found. The thermodynamical characteristics of a bag gas in the neighbourhood of a phase transition point are ascertained in analytical form

Axial-vector gluons and the fine structure of heavy quark--antiquark systems

International Nuclear Information System (INIS)

Feinberg, G.; Lynn, B.; Sucher, J.

1979-01-01

We point out that two models of the origin of spin-dependent forces in heavy quark systems make very different predictions about the relative size of these forces in c-barc and b-barb. The model in which these forces are relativistic corrections to vector or scalar gluon exchange predicts smaller spin-dependent effects in b-barb than in c-barc while a model in which these forces are due to exchange of axial-vector gluons predicts a similar size for spin-dependent splittings in the two systems

Radiative decays of single heavy flavour baryons

International Nuclear Information System (INIS)

Majethiya, Ajay; Patel, Bhavin; Vinodkumar, P.C.

2009-01-01

The electromagnetic transitions between (J P =(3)/(2) + ) and (J P =(1)/(2) + ) baryons are important decay modes to observe new hadronic states experimentally. For the estimation of these transitions widths, we employ a non-relativistic quark potential model description with color Coulomb plus linear confinement potential. Such a description has been employed to compute the ground-state masses and magnetic moments of the single heavy flavor baryons. The magnetic moments of the baryons are obtained using the spin-flavor structure of the constituting quark composition of the baryon. Here, we also define an effective constituent mass of the quarks (ecqm) by taking into account the binding effects of the quarks within the baryon. The radiative transition widths are computed in terms of the magnetic moments of the baryon and the photon energy. Our results are compared with other theoretical models. (orig.)

Radial excitations in nucleon-nucleon scattering

International Nuclear Information System (INIS)

Silvestre-Brac, B.; Carbonell, J.; Gignoux, C.

1986-01-01

In the non-relativistic constituent quark model, the role of the radial excitations of the nucleon is studied within a resonating group approach of the nucleon-nucleon scattering. It is shown that, rather than the inclusion of new channels, it is important to include mixed-symmetry spin-isospin components in the nucleon wave function. It is also found that during the collision there is no significant deformation of the nucleon. (orig.)

Re-hardening of hadron transverse mass spectra in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Ohnishi, A.; Otuka, N.; Sahu, P.K.; Isse, M.; Nara, Y.

2001-01-01

We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65 + 65 A GeV by using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma formation. (author)

Hot nuclear matter in the modified quark-meson coupling model with quark-quark correlations

International Nuclear Information System (INIS)

Zakout, I.; Jaqaman, H.R.

2000-01-01

Short-range quark-quark correlations in hot nuclear matter are examined within the modified quark-meson coupling (MQMC) model by adding repulsive scalar and vector quark-quark interactions. Without these correlations, the bag radius increases with the baryon density. However, when the correlations are introduced the bag size shrinks as the bags overlap. Also as the strength of the scalar quark-quark correlation is increased, the decrease of the effective nucleon mass M* N with the baryonic density is slowed down and tends to saturate at high densities. Within this model we study the phase transition from the baryon-meson phase to the quark-gluon plasma (QGP) phase with the latter modelled as an ideal gas of quarks and gluons inside a bag. Two models for the QGP bag parameter are considered. In one case, the bag is taken to be medium-independent and the phase transition from the hadron phase to QGP is found to occur at five to eight times ordinary nuclear matter density for temperatures less than 60 MeV. For lower densities, the transition takes place at a higher temperature, reaching up to 130 MeV at zero density. In the second case, the QGP bag parameter is considered to be medium-dependent as in the MQMC model for the hadronic phase. In this case, it is found that the phase transition occurs at much lower densities. (author)

Strange quark matter in the Universe and accelerator nuclear beams

International Nuclear Information System (INIS)

Okonov, Eh.

1995-01-01

An almost symmetric mixture of u, d and s-quarks - Strange Quark Matter (SQM) is strongly argued to be the ground and absolutely stable of the matter. Astrophysical objects, supposed to be the SQM states, could be formed as the result of the Big Bang (in the early Universe) and the conversion of neutron stars into strange ones. Such objects are considered to be favourable candidates as black holes. The unique possibility to produce the SQM under terrestrial conditions (at accelerator laboratories) are violent relativistic nucleus-nucleus collisions so called 'little big bang'. The expected singulares of SQM are reviewed which could be revealed from astrophysical observations of peculiarities of large SQM objects as well as from accelerator experiments with searching smaller SQM states including the simplest one - metastable six-quark H dihyperon. The first results of the Dubna search experiments, with considerable heating of matter and formation a dense strangeness abundant fireball (mixed phase?) in central nuclear collisions, is presented. Under these favourable conditions a candidate for H dihyperon is observed and an upper limit of production cross sections of this SQM state is estimated. Some prospects and advantages of further searches for light SQM states, using the JINR new superconducting accelerator - Nuclotron with energy 5-6 GeV per nucleon, are briefly outlined. 19 refs., 7 figs

PREFACE: Quark Matter 2008

Science.gov (United States)

Jan-e~Alam; Subhasis~Chattopadhyay; Tapan~Nayak

2008-10-01

Quark Matter 2008—the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions was held in Jaipur, the Pink City of India, from 4-10 February, 2008. Organizing Quark Matter 2008 in India itself indicates the international recognition of the Indian contribution to the field of heavy-ion physics, which was initiated and nurtured by Bikash Sinha, Chair of the conference. The conference was inaugurated by the Honourable Chief Minister of Rajasthan, Smt. Vasundhara Raje followed by the key note address by Professor Carlo Rubbia. The scientific programme started with the theoretical overview, `SPS to RHIC and onwards to LHC' by Larry McLerran followed by several theoretical and experimental overview talks on the ongoing experiments at SPS and RHIC. The future experiments at the LHC, FAIR and J-PARC, along with the theoretical predictions, were discussed in great depth. Lattice QCD predictions on the nature of the phase transition and critical point were vigorously debated during several plenary and parallel session presentations. The conference was enriched by the presence of an unprecedented number of participants; about 600 participants representing 31 countries across the globe. This issue contains papers based on plenary talks and oral presentations presented at the conference. Besides invited and contributed talks, there were also a large number of poster presentations. Members of the International Advisory Committee played a pivotal role in the selection of speakers, both for plenary and parallel session talks. The contributions of the Organizing Committee in all aspects, from helping to prepare the academic programme down to arranging local hospitality, were much appreciated. We thank the members of both the committees for making Quark Matter 2008 a very effective and interesting platform for scientific deliberations. Quark Matter 2008 was financially supported by: Air Liquide (New Delhi) Board of Research Nuclear Sciences (Mumbai) Bose

Numerical magneto-hydrodynamics for relativistic nuclear collisions

Energy Technology Data Exchange (ETDEWEB)

Inghirami, Gabriele [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Goethe-Universitaet, Institute for Theoretical Physics, Frankfurt am Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Forschungszentrum Juelich, John von Neumann Institute for Computing, Juelich (Germany); Del Zanna, Luca [Universita di Firenze, Dipartimento di Fisica e Astronomia, Firenze (Italy); INAF - Osservatorio Astrofisico di Arcetri, Firenze (Italy); INFN - Sezione di Firenze, Firenze (Italy); Beraudo, Andrea [INFN - Sezione di Torino, Torino (Italy); Moghaddam, Mohsen Haddadi [INFN - Sezione di Torino, Torino (Italy); Hakim Sabzevari University, Department of Physics, P. O. Box 397, Sabzevar (Iran, Islamic Republic of); Becattini, Francesco [Universita di Firenze, Dipartimento di Fisica e Astronomia, Firenze (Italy); INFN - Sezione di Firenze, Firenze (Italy); Bleicher, Marcus [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Goethe-Universitaet, Institute for Theoretical Physics, Frankfurt am Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Forschungszentrum Juelich, John von Neumann Institute for Computing, Juelich (Germany)

2016-12-15

We present an improved version of the ECHO-QGP numerical code, which self-consistently includes for the first time the effects of electromagnetic fields within the framework of relativistic magneto-hydrodynamics (RMHD). We discuss results of its application in relativistic heavy-ion collisions in the limit of infinite electrical conductivity of the plasma. After reviewing the relevant covariant 3 + 1 formalisms, we illustrate the implementation of the evolution equations in the code and show the results of several tests aimed at assessing the accuracy and robustness of the implementation. After providing some estimates of the magnetic fields arising in non-central high-energy nuclear collisions, we perform full RMHD simulations of the evolution of the quark-gluon plasma in the presence of electromagnetic fields and discuss the results. In our ideal RMHD setup we find that the magnetic field developing in non-central collisions does not significantly modify the elliptic flow of the final hadrons. However, since there are uncertainties in the description of the pre-equilibrium phase and also in the properties of the medium, a more extensive survey of the possible initial conditions as well as the inclusion of dissipative effects are indeed necessary to validate this preliminary result. (orig.)

Regularities in hadron systematics, Regge trajectories and a string quark model

International Nuclear Information System (INIS)

Chekanov, S.V.; Levchenko, B.B.

2006-08-01

An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have non-linear behaviour. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semi-classical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses. (orig.)

A Model-Independent Discussion of Quark Number Density and Quark Condensate at Zero Temperature and Finite Quark Chemical Potential

International Nuclear Information System (INIS)

Xu Shu-Sheng; Shi Chao; Cui Zhu-Fang; Zong Hong-Shi; Jiang Yu

2015-01-01

Generally speaking, the quark propagator is dependent on the quark chemical potential in the dense quantum chromodynamics (QCD). By means of the generating functional method, we prove that the quark propagator actually depends on p_4 + iμ from the first principle of QCD. The relation between quark number density and quark condensate is discussed by analyzing their singularities. It is concluded that the quark number density has some singularities at certain μ when T = 0, and the variations of the quark number density as well as the quark condensate are located at the same point. In other words, at a certain μ the quark number density turns to nonzero, while the quark condensate begins to decrease from its vacuum value. (paper)

Quark phases in neutron stars and a third family of compact stars as signature for phase transitions

International Nuclear Information System (INIS)

Schertler, K.; Greiner, C.; Schaffner-Bielich, J.; Thoma, M.H.

2000-01-01

The appearance of quark phases in the dense interior of neutron stars provides one possibility to soften the equation of state (EOS) of neutron star matter at high densities. This softening leads to more compact equilibrium configurations of neutron stars compared to pure hadronic stars of the same mass. We investigate the question to which amount the compactness of a neutron star can be attributed to the presence of a quark phase. For this purpose we employ several hadronic EOS in the framework of the relativistic mean-field (RMF) model and an extended MIT bag model to describe the quark phase. We find that -- almost independent of the model parameters -- the radius of a pure hadronic neutron star gets typically reduced by 20-30% if a pure quark phase in the center of the star does exist. For some EOS we furthermore find the possibility of a third family of compact stars which may exist besides the two known families of white dwarfs and neutron stars. We show how an experimental proof of the existence of a third family by mass and radius measurements may provide a unique signature for a phase transition inside neutron stars

Measuring Shear Viscosity Using Transverse Momentum Correlations in Relativistic Nuclear Collisions

International Nuclear Information System (INIS)

Gavin, Sean; Abdel-Aziz, Mohamed

2006-01-01

Elliptic flow measurements at the Brookhaven National Laboratory Relativistic Heavy Ion Collider suggest that quark-gluon fluid flows with very little viscosity compared to weak-coupling expectations, challenging theorists to explain why this fluid is so nearly ''perfect.'' It is therefore vital to find quantitative experimental information on the viscosity of the fluid. We propose that measurements of transverse momentum fluctuations can be used to determine the shear viscosity. We use current data to estimate the viscosity-to-entropy ratio in the range from 0.08 to 0.3 and discuss how future measurements can reduce this uncertainty

Relativistic corrections to the form factors of Bc into P-wave orbitally excited charmonium

Science.gov (United States)

Zhu, Ruilin

2018-06-01

We investigated the form factors of the Bc meson into P-wave orbitally excited charmonium using the nonrelativistic QCD effective theory. Through the analytic computation, the next-to-leading order relativistic corrections to the form factors were obtained, and the asymptotic expressions were studied in the infinite bottom quark mass limit. Employing the general form factors, we discussed the exclusive decays of the Bc meson into P-wave orbitally excited charmonium and a light meson. We found that the relativistic corrections lead to a large correction for the form factors, which makes the branching ratios of the decay channels B (Bc ± →χcJ (hc) +π± (K±)) larger. These results are useful for the phenomenological analysis of the Bc meson decays into P-wave charmonium, which shall be tested in the LHCb experiments.

Effects of causality on the fluidity and viscous horizon of quark-gluon plasma

Science.gov (United States)

Rahaman, Mahfuzur; Alam, Jan-e.

2018-05-01

The second-order Israel-Stewart-M u ̈ller relativistic hydrodynamics was applied to study the effects of causality on the acoustic oscillation in relativistic fluid. Causal dispersion relations have been derived with nonvanishing shear viscosity, bulk viscosity, and thermal conductivity at nonzero temperature and baryonic chemical potential. These relations have been used to investigate the fluidity of quark-gluon plasma (QGP) at finite temperature (T ). Results of the first-order dissipative hydrodynamics have been obtained as a limiting case of the second-order theory. The effects of the causality on the fluidity near the transition point and on the viscous horizon are found to be significant. We observe that the inclusion of causality increases the value of fluidity measure of QGP near Tc and hence makes the flow strenuous. It was also shown that the inclusion of the large magnetic field in the causal hydrodynamics alters the fluidity of QGP.

Confinement of quarks

International Nuclear Information System (INIS)

Nambu, J.

1978-01-01

Three quark models of hadron structure, which suggest an explanation of quarks confinement mechanism in hadrons are considered. Quark classifications, quark flawors and colours, symmetry model of hadron structure based on the colour theory of strong interaction are discussed. Diagrams of colour combinations of quarks and antiquarks, exchange of gluons, binding quarks in hadron. Quark confinement models based on the field theory, string model rotating and bag model are discussed. Diagrams of the colour charge distribution explaining the phenomena of infrared ''slavery'' and ultraviolet ''freedom'' are given. The models considered explain but some quark properties, creating prerequisites for the development of the consequent theory of hadron structure

Phenomenological aspects of nonrelativistic potential models

International Nuclear Information System (INIS)

Lucha, W.; Schoeberl, F.F.

1989-01-01

This review reports on the description of hardrons as bound states of quarks by nonrelativistic potential models. It contains a brief sketch of the way in which information on the form of the inter-quark potential may be gained from quantum chromodynamics, proofs of some general theorems related to the potential-model approach, a discussion of the significance of the treatment of bound states consisting of relativistically-moving constituents by the nonrelativistic Schroedinger formalism, as well as a brief survey of the motivations for the various proposed potential models. Finally, it illustrates the application of the developed theoretical framework at a few selected examples. 60 refs., 8 figs., 17 tabs. (Authors)

Charge parity exotic mesons

International Nuclear Information System (INIS)

Burden, C.J.

1998-01-01

Full text: Evidence for a meson with exotic quantum numbers J PC 1 -+ , the ρ(1405), has been observed at the AGS at Brookhaven and Crystal Barrel at CERN. This meson is exotic to the extent that its quantum numbers are not consistent with the generalised Pauli exclusion principle applied to the naive constituent quark model. In a fully relativistic field theoretic treatment, however, there is nothing in principle to preclude the existence of charge parity exotics. Using our earlier covariant Bethe-Salpeter model of light-quark mesons with no new parameter fitting we demonstrate the existence of a q - q-bar bound state with the quantum numbers of the ρ

Third-order QCD corrections to heavy quark pair production near threshold

Energy Technology Data Exchange (ETDEWEB)

Schuller, Kurt

2008-11-07

The measurement of the top quark mass is an important task at the future International Linear Collider. The most promising process is the top quark pair production in the threshold region. In this region the top quarks behave non-relativistically and a perturbative treatment using effective field theories is possible. Current second order theoretical predictions in a fixed order approach show an uncertainty which is bigger than the expected experimental errors. Therefore, an improvement of the cross section calculation is desirable. There are two ways to incorporate higher order effects, one is to calculate the full next order in the fixed order approach, another possibility is to resum large logarithms. In this work, the fixed order calculation has been extended to the third order in perturbation theory for the QCD corrections. The result is a strongly improved scale behavior and a better understanding of heavy quarkonium systems. The Green function result is given in a semi-analytic form. The energy levels and wave functions for heavy quarkonium states have been calculated from the poles of the Green function and are presented for arbitrary quantum number n. The results have been implemented in a Mathematica program which makes the data easily accessible. Once some missing matching coefficients are calculated, and a complete electroweak calculation is available, the results of this work can be used to improve the precision of the top quark mass measurement to an uncertainty of less than 50 MeV. An inclusion of initial state radiation and beam effects are essential for a realistic observable. In the future, the results obtained could be used for a third order resummation of large logarithms. Further applications are also the extraction of the bottom quark mass with sum rules. (orig.)

Perturbative study in quantum field theory at finite temperature, application to lepton pair production from a quark-gluon plasma

International Nuclear Information System (INIS)

Altherr, T.

1989-12-01

The main topic of this thesis is a perturbative study of Quantum Field Theory at Finite Temperature. The real-time formalism is used throughout this work. We show the cancellation of infrared and mass singularities in the case of the first order QCD corrections to lepton pair production from a quark-gluon plasma. Two methods of calculation are presented and give the same finite result in the limit of vanishing quark mass. These finite terms are analysed and give small corrections in the region of interest for ultra-relativistic heavy ions collisions, except for a threshold factor. Specific techniques for finite temperature calculations are explicited in the case of the fermionic self-energy in QED [fr

The charge form factor of pseudoscalar mesons in a relativistic constituent quark model

Energy Technology Data Exchange (ETDEWEB)

Cardarelli, F.; Pace, E. [Univ. of Rome, Roma (Italy); Grach, I.L. [Inst. of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others

1994-04-01

The charge form factor of pseudoscalar mesons has been investigated in the light-cone formalism, up to Q{sup 2} relevant to CEBAF energies. The consequences of adopting the meson wave functions generated through the Godfrey-Isgur q{bar q} potential, which reproduces the mass spectra, are discussed.

Physics with relativistic heavy ions: QGP and other delicacies

International Nuclear Information System (INIS)

Young, G.R.

1995-01-01

Conditions favorable to formation and observation of a deconfined state of quarks and gluons (often called the quark-gluon plasma) are thought to exist following the collision of very heavy nuclei at center-of-mass energies exceeding several tens of GeV/nucleon. The Relativistic Heavy Ion Collider under construction at BNL since 1991 is designed to provide such collisions at energies up to √s/A = 200 GeV. Two large dedicated experiments are being built to operate there; these two experiments take rather different approaches to the problem of classifying such collisions and probing for signals of QGP formation. Two smaller experiments are proposed to focus on specific aspects of these collisions. Recent developments in the understanding of the initial state formed in such collisions include, particularly, the possible rapid equilibration of the gluon density, leading in an equilibrium picture to such high temperatures that sizable thermal excitation of charm becomes probable. Recent theoretical conjectures have focussed on the possible formation of a disordered chiral condensate following chiral symmetry restoration in heavy-nucleus collisions, which might be a consequence of nonequilibrium deexcitation of a dense partonic state

Method of taking into account meson and quark-gluon degrees of freedom in hadron-hadron interactions at low and intermediate energies. Application to NN scattering

International Nuclear Information System (INIS)

Safronov, A.N.

1983-01-01

A system of nonsingular integral equations is formulated for the calculation of hadron-hadron partial amplitudes in the low-and intermediate-energy range taking into account meson and quark-gluon degrees of freedom. The quark-gluon degrees of freedom are included in the framework of the composite-quark-bag model, and the meson degrees of freedom are treated by the methods of the relativistic quantum field theory. It is shown that including the quark-gluon degrees of freedom leads to suppression of meson exchange effects, mostly of heavy meson (rho, ω) exchanges. The method has been applied to the calculation of the 3 S 1 , 1 S 0 , 3 P 0 , 3 P 1 , and 1 P 1 phase shifts for the nucleon-nucleon scattering at the incident nucleon energies T=0-1050 MeV, as well as to the S-wave scattering lengths and effective radii

LATTICE SIMULATIONS OF THE THERMODYNAMICS OF STRONGLY INTERACTING ELEMENTARY PARTICLES AND THE EXPLORATION OF NEW PHASES OF MATTER IN RELATIVISTIC HEAVY ION COLLISIONS

International Nuclear Information System (INIS)

KARSCH, F.

2006-01-01

At high temperatures or densities matter formed by strongly interacting elementary particles (hadronic matter) is expected to undergo a transition to a new form of matter--the quark gluon plasma--in which elementary particles (quarks and gluons) are no longer confined inside hadrons but are free to propagate in a thermal medium much larger in extent than the typical size of a hadron. The transition to this new form of matter as well as properties of the plasma phase are studied in large scale numerical calculations based on the theory of strong interactions--Quantum Chromo Dynamics (QCD). Experimentally properties of hot and dense elementary particle matter are studied in relativistic heavy ion collisions such as those currently performed at the relativistic heavy ion collider (RHIC) at BNL. We review here recent results from studies of thermodynamic properties of strongly interacting elementary particle matter performed on Teraflops-Computer. We present results on the QCD equation of state and discuss the status of studies of the phase diagram at non-vanishing baryon number density

Pions, delta's and quarks in nuclei

International Nuclear Information System (INIS)

Laget, J.M.

1983-10-01

Nuclear Physics has now evolved from the study of the many nucleon problem, to the study of the interplay of the degrees of freedom of such a complex system and the internal degrees of freedom of each of its hadronic constituents. Extensive studies of electronuclear reactions have all allowed us to disentangle the basic mechanisms of the interaction between two baryons in a nucleus. The pion exchange mechanisms, which dominates at large distance has been singled out. The NΔ interaction, which enter the description of the intermediate range part, has been studied. Evidences for effects due to the quark structure of the nucleon have been found. But more systematic studies are needed to study them in detail

From nucleons to quarks in nuclei

International Nuclear Information System (INIS)

Laget, J.M.

1984-07-01

Nuclear Physics has now evolved from the study of the many nucleon problem, to the study of the interplay of the degrees of freedom of such a complex system and the internal degrees of freedom of each of its hadronic constituents. Extensive studies of electronuclear reactions have allowed us to disentangle the basic mechanisms of the interaction between two baryons in a nucleus. The pion exchange mechanism, which dominates at large distance has been singled out. The NΔ interaction, which enter the description of the intermediate range part, has been studied. Evidences for effects due to the quark structure of the nucleon have been found. They involve the short distance structure of the nucleus

Relativistic and non-relativistic studies of nuclear matter

NARCIS (Netherlands)

Banerjee, MK; Tjon, JA

2002-01-01

We point out that the differences between the results of the non-relativistic lowest order Brueckner theory (LOBT) and the relativistic Dirac-Brueckner analysis predominantly arise from two sources. Besides effects from a nucleon mass modification M* in nuclear medium we have in a relativistic

Quark core stars, quark stars and strange stars

International Nuclear Information System (INIS)

Grassi, F.

1988-01-01

A recent one flavor quark matter equation of state is generalized to several flavors. It is shown that quarks undergo a first order phase transition. In addition, this equation of state depends on just one parameter in the two flavor case, two parameters in the three flavor case, and these parameters are constrained by phenomenology. This equation of state is then applied to the hadron-quark transition in neutron stars and the determination of quark star stability, the investigation of strange matter stability and possible strange star existence. 43 refs., 6 figs

Top quark pair production and top quark properties at CDF

Energy Technology Data Exchange (ETDEWEB)

Moon, Chang-Seong [INFN, Pisa

2016-06-02

We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix element $|V_{tb}|$ from the ratio $R$ is discussed. We also present the latest measurements on the forward-backward asymmetry ($A_{FB}$) in top anti-top quark production. With the full CDF Run II data set, the measurements are performed in top anti-top decaying to final states that contain one or two charged leptons (electrons or muons). In addition, we combine the results of the leptonic forward-backward asymmetry in $t\\bar t$ system between the two final states. All the results show deviations from the next-to-leading order (NLO) standard model (SM) calculation.

Thermodynamics and relativistic kinetic theory for q-generalized Bose-Einstein and Fermi-Dirac systems

Science.gov (United States)

Mitra, Sukanya

2018-01-01

The thermodynamics and covariant kinetic theory are elaborately investigated in a non-extensive environment considering the non-extensive generalization of Bose-Einstein (BE) and Fermi-Dirac (FD) statistics. Starting with Tsallis' entropy formula, the fundamental principles of thermostatistics are established for a grand canonical system having q-generalized BE/FD degrees of freedom. Many particle kinetic theory is set up in terms of the relativistic transport equation with q-generalized Uehling-Uhlenbeck collision term. The conservation laws are realized in terms of appropriate moments of the transport equation. The thermodynamic quantities are obtained in a weak non-extensive environment for a massive pion-nucleon and a massless quark-gluon system with non-zero baryon chemical potential. In order to get an estimate of the impact of non-extensivity on the system dynamics, the q-modified Debye mass and hence the q-modified effective coupling are estimated for a quark-gluon system.

Duality of two-point functions for confined non-relativistic quark-antiquark systems

International Nuclear Information System (INIS)

Fishbane, P.M.; Gasiorowicz, S.G.; Kaus, P.

1985-01-01

An analog to the scattering matrix describes the spectrum and high-energy behavior of confined systems. We show that for non-relativistic systems this S-matrix is identical to a two-point function which transparently describes the bound states for all angular momenta. Confined systems can thus be described in a dual fashion. This result makes it possible to study the modification of linear trajectories (originating in a long-range confining potential) due to short range forces which are unknown except for the way in which they modify the asymptotic behavior of the two point function. A type of effective range expansion is one way to calculate the energy shifts. 9 refs

Chemical Potentials of Quarks Extracted from Particle Transverse Momentum Distributions in Heavy Ion Collisions at RHIC Energies

International Nuclear Information System (INIS)

Zhao, Hong; Liu, Fu-Hu

2014-01-01

In the framework of a multisource thermal model, the transverse momentum distributions of charged particles produced in nucleus-nucleus (A-A) and deuteron-nucleus (d-A) collisions at relativistic heavy ion collider (RHIC) energies are investigated by a two-component revised Boltzmann distribution. The calculated results are in agreement with the PHENIX experimental data. It is found that the source temperature increases obviously with increase of the particle mass and incident energy, but it does not show an obvious change with the collision centrality. Then, the values of chemical potentials for up, down, and strange quarks can be obtained from the antiparticle to particle yield ratios in a wide transverse momentum range. The relationship between the chemical potentials of quarks and the transverse momentum with different centralities is investigated, too

Semileptonic Decays of Heavy Lambda Baryons in a Quark Model

Energy Technology Data Exchange (ETDEWEB)

Winston Roberts; Muslema Pervin; Simon Capstick

2005-03-01

The semileptonic decays of {Lambda}{sub c} and {Lambda}{sub b} are treated in the framework of a constituent quark model. Both nonrelativistic and semirelativistic Hamiltonians are used to obtain the baryon wave functions from a fit to the spectra, and the wave functions are expanded in both the harmonic oscillator and Sturmian bases. The latter basis leads to form factors in which the kinematic dependence on q{sup 2} is in the form of multipoles, and the resulting form factors fall faster as a function of q{sup 2} in the available kinematic ranges. As a result, decay rates obtained in the two models using the Sturmian basis are significantly smaller than those obtained using the harmonic oscillator basis. In the case of the {Lambda}{sub c}, decay rates calculated using the Sturmian basis are closer to the experimentally reported rates. However, we find a semileptonic branching fraction for the {Lambda}{sub c} to decay to excited {Lambda}* states of 11% to 19%, in contradiction with what is assumed in available experimental analyses. Our prediction for the {Lambda}{sub b} semileptonic decays is that decays to the ground state {Lambda}{sub c} provide a little less than 70% of the total semileptonic decay rate. For the decays {Lambda}{sub b} {yields} {Lambda}{sub c}, the analytic form factors we obtain satisfy the relations expected from heavy-quark effective theory at the non-recoil point, at leading and next-to-leading orders in the heavy-quark expansion. In addition, some features of the heavy-quark limit are shown to naturally persist as the mass of the heavy quark in the daughter baryon is decreased.

Semileptonic Decays of Heavy Omega Baryons in a Quark Model

International Nuclear Information System (INIS)

Muslema Pervin; Winston Roberts; Simon Capstick

2006-01-01

The semileptonic decays of (Omega) c and (Omega) b are treated in the framework of a constituent quark model developed in a previous paper on the semileptonic decays of heavy Λ baryons. Analytic results for the form factors for the decays to ground states and a number of excited states are evaluated. For (Omega) b to (Omega) c the form factors obtained are shown to satisfy the relations predicted at leading order in the heavy-quark effective theory at the non-recoil point. A modified fit of nonrelativistic and semirelativistic Hamiltonians generates configuration-mixed baryon wave functions from the known masses and the measured Λ c + → Λe + ν rate, with wave functions expanded in both harmonic oscillator and Sturmian bases. Decay rates of (Omega) b to pairs of ground and excited (Omega) c states related by heavy-quark symmetry calculated using these configuration-mixed wave functions are in the ratios expected from heavy-quark effective theory, to a good approximation. Our predictions for the semileptonic elastic branching fraction of (Omega) Q vary minimally within the models we use. We obtain an average value of (84 ± 2%) for the fraction of (Omega) c → Ξ (*) decays to ground states, and 91% for the fraction of (Omega) c → (Omega) (*) decays to the ground state (Omega). The elastic fraction of (Omega) b → (Omega) c ranges from about 50% calculated with the two harmonic-oscillator models, to about 67% calculated with the two Sturmian models

On the gluonic correction to lepton-pair decays in a relativistic quarkonium model

International Nuclear Information System (INIS)

Ito, Hitoshi

1987-01-01

The gluonic correction to the leptonic decay of the heavy vector meson is investigated by using the perturbation theory to the order α s . The on-mass-shell approximation is assumed for the constituent quarks so that we assure the gauge independence of the correction. The decay rates in the model based on the Bethe-Salpeter equation are also shown, in which the gluonic correction with a high-momentum cutoff is calculated for the off-shell quarks. It is shown that the static approximation to the correction factor (1 - 16α s /3π) is not adequate and the gluonic correction does not suppress but enhance the decay rates of the ground states for the c anti c and b anti b systems. (author)

Short range part of the NN interaction: Equivalent local potentials from quark exchange kernels

International Nuclear Information System (INIS)

Suzuk, Y.; Hecht, K.T.

1983-01-01

To focus on the nature of the short range part of the NN interaction, the intrinsically nonlocal interaction among the quark constituents of colorless nucleons is converted to an equivalent local potential using resonating group kernels which can be evaluated in analytic form. The WKB approximation based on the Wigner transform of the nonlocal kernels has been used to construct the equivalent potentials without recourse to the long range part of the NN interaction. The relative importance of the various components of the exchange kernels can be examined: The results indicate the importance of the color magnetic part of the exchange kernel for the repulsive part in the (ST) = (10), (01) channels, in particular since the energy dependence of the effective local potentials seems to be set by this term. Large cancellations of color Coulombic and quark confining contributions, together with the kinetic energy and norm exchange terms, indicate that the exact nature of the equivalent local potential may be sensitive to the details of the parametrization of the underlying quark-quark interaction. The equivalent local potentials show some of the characteristics of the phenomenological short range terms of the Paris potential

Inclusive production of large-p/sub T/ protons and quark-quark elastic scattering

International Nuclear Information System (INIS)

Chen, C.K.

1978-01-01

A proton-formation process in combination with hard quark-quark scattering is capable of explaining the observed large-p/sub T/ single-proton inclusive production data. This model implies that the inclusive production of two large-p/sub T/ protons at opposite directions is dominated by large-angle elastic scattering of two up quarks, and becomes an ideal place to study elastic quark-quark scattering. This two-proton inclusive production process is also ideal for the study of the spin structure of quark-quark elastic scattering, so the assumptions of pure vector-type quark-quark interaction and of colored quarks can be checked empirically. The consistency of applying the quark-elastic-scattering idea to large-angle elastic proton-proton scattering and to the inclusive production of large-p/sub T/ protons is also demonstrated

Exclusive description of multiple production on nuclei in the additive quark model. Multiplicity distributions in interactions with heavy nuclei

International Nuclear Information System (INIS)

Levchenko, B.B.; Nikolaev, N.N.

1985-01-01

In the framework of the additive quark model of multiple production on nuclei we calculate the multiplicity distributions of secondary particles and the correlations between secondary particles in πA and pA interactions with heavy nuclei. We show that intranuclear cascades are responsible for up to 50% of the nuclear increase of the multiplicity of fast particles. We analyze the sensitivity of the multiplicities and their correlations to the choice of the quark-hadronization function. We show that with good accuracy the yield of relativistic secondary particles from heavy and intermediate nuclei depends only on the number N/sub p/ of protons knocked out of the nucleus, and not on the mass number of the nucleus (N/sub p/ scaling)

Thermal radiation from an evolving viscous quark gluon plasma

International Nuclear Information System (INIS)

Mitra, Sukanya; Mohanty, Payal; Sarkar, Sourav; Alam, Jan-E

2013-01-01

The effects of viscosity on the space-time evolution of quark gluon plasma produced in nuclear collisions at relativistic heavy ion collider energies have been studied. The entropy generated due to the viscous motion of the fluid has been taken into account in constraining the initial temperature by the final multiplicity (measured at the freeze-out point). The viscous effects on the photon spectra has been introduced consistently through the evolution dynamics and phase space factors of all the participating partons/hadrons in the production process. In contrast to some of the recent calculations the present work includes the contribution from the hadronic phase. A small change in the transverse momentum (p T ) distribution of photons is observed due to viscous effects. (author)

Valence QCD: Connecting QCD to the quark model

International Nuclear Information System (INIS)

Liu, K.F.; Dong, S.J.; Draper, T.; Sloan, J.; Leinweber, D.; Woloshyn, R.M.

1999-01-01

A valence QCD theory is developed to study the valence quark properties of hadrons. To keep only the valence degrees of freedom, the pair creation through the Z graphs is deleted in the connected insertions, whereas the sea quarks are eliminated in the disconnected insertions. This is achieved with a new 'valence QCD' Lagrangian where the action in the time direction is modified so that the particle and antiparticle decouple. It is shown in this valence version of QCD that the ratios of isovector to isoscalar matrix elements (e.g., F A /D A and F S /D S ratios) in the nucleon reproduce the SU(6) quark model predictions in a lattice QCD calculation. We also consider how the hadron masses are affected on the lattice and discover new insights into the origin of dynamical mass generation. It is found that, within statistical errors, the nucleon and the Δ become degenerate for the quark masses we have studied (ranging from 1 to 4 times the strange mass). The π and ρ become nearly degenerate in this range. It is shown that valence QCD has the C, P, T symmetries. The lattice version is reflection positive. It also has the vector and axial symmetries. The latter leads to a modified partially conserved axial Ward identity. As a result, the theory has a U(2N F ) symmetry in the particle-antiparticle space. Through lattice simulation, it appears that this is dynamically broken down to U q (N F )xU bar q (N F ). Furthermore, the lattice simulation reveals spin degeneracy in the hadron masses and various matrix elements. This leads to an approximate U q (2N F )xU bar q (2N F ) symmetry which is the basis for the valence quark model. In addition, we find that the masses of N, Δ,ρ,π,a 1 , and a 0 all drop precipitously compared to their counterparts in the quenched QCD calculation. This is interpreted as due to the disappearance of the 'constituent' quark mass which is dynamically generated through tadpole diagrams. The origin of the hyperfine splitting in the baryon is

Electromagnetic processes in relativistic heavy ion collisions

International Nuclear Information System (INIS)

Bertulani, C.A.; Universidade Federal do Rio de Janeiro; Baur, G.

1987-10-01

A study of the processes generated by the electromagnetic interaction in relativistic nuclear, and atomic collisions is presented. There is nowadays a vivid interest in this field due to the construction of relativistic heavy ion accelerators. Certainly, the most important purpose of these relativistic heavy ion machines is the study of nuclear matter under extreme conditions. In central nucleus-nucleus collisions one hopes to observe new forms of nuclear matter, like the quark-gluon plasma. On the other hand, very strong electromagnetic fields for a very short time are present in distant collisions with no nuclear contact. Such fields can also lead to interesting effects, which are discussed here. There has been many interesting theoretical and experimental developments on this subject, and new areas of research were opened. Of special interest is, e.g., the case of nuclear fragmentation. This is accomplished through the excitation of giant resonances or by direct breakt-up of the nuclei by means of their electromagnetic interaction. It is shown that this process can be used to study nuclear structure properties which are not accessible by means of the traditional electromagnetic excitation at nonrelativistic energies. The creation of particles is also of interest due the large cross sections, specially in the case of electron-positron pair creation. Although to explain the many processes originated in this way one can develop very elaborate and complicated calculations, the results can be understood in very simple terms because of our almost complete comprehension of the electromagntic interaction. For those processes where the electromagntic interaction plays the dominant role this is clearly a very useful tool for the investigation of the structures created by the strong interaction in the nuclei or hadrons. (orig.)

Quark chiral condensate from the overlap quark propagator

Science.gov (United States)

Wang, Chao; Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Zhaofeng

2017-05-01

From the overlap lattice quark propagator calculated in the Landau gauge, we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data. The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N f = 2+1 flavors. Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) GeV. We obtain in the SU(2) chiral limit. Supported by National Natural Science Foundation of China (11575197, 11575196, 11335001, 11405178), joint funds of NSFC (U1632104, U1232109), YC and ZL acknowledge the support of NSFC and DFG (CRC110)

Quark-gluon plasma at finite baryons density and in limit of large Nc

International Nuclear Information System (INIS)

Azakov, S.I.

1987-01-01

Study of thermodynamics of ideal colourless quark-gluon (QG) gas in limit of large N C is carried out. Consideration of this limit much simplifies the problem on calculation of such system statsum. Unlike the papers where the properties of ideal colourless QG-gas were defined in approximation valid at large V volumes, in the given calculations the volume may be arbitrary. The ideal QG gas is considered in a final volume. Phase transition is shown to be absent in the problem more relativistic from the physical view point, when conservation of the baryon charge is taken into account

Scaling properties of hyperon production in Au+Au collisions at square root [sNN]=200 GeV.

Science.gov (United States)

Adams, J; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Bezverkhny, B I; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, C O; Blyth, S-L; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Castillo, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, Y; Cheng, J; Cherney, M; Chikanian, A; Choi, H A; Christie, W; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Daugherity, M; de Moura, M M; Dedovich, T G; DePhillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Filimonov, K; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Gans, J; Ganti, M S; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Guertin, S M; Guimaraes, K S F F; Guo, Y; Gupta, N; Gutierrez, T D; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horner, M J; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lapointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; Levine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Netrakanti, P K; Nikitin, V A; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Poljak, N; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Razin, S V; Reinnarth, J; Relyea, D; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Schweda, K; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sugarbaker, E; Sumbera, M; Sun, Z; Surrow, B; Swanger, M; Symons, T J M; Szanto de Toledo, A; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

2007-02-09

We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2constituent quark degrees of freedom.

Semileptonic decays of B and D mesons in the light-front formalism

International Nuclear Information System (INIS)

Jaus, W.

1990-01-01

The light-front formalism is used to present a relativistic calculation of form factors for semileptonic D and B decays in the constituent quark model. The quark-antiquark wave functions of the mesons can be obtained, in principle, from an analysis of the meson spectrum, but are approximated in this work by harmonic-oscillator wave functions. The predictions of the model are consistent with the experimental data for B decays. The Kobayashi-Maskawa (KM) matrix element |V cs | is determined by a comparison of the experimental and theoretical rates for D 0 →K - e + ν, and is consistent with a unitary KM matrix for three families. The predictions for D→K * transitions are in conflict with the data

Heavy quark fragmentation functions in the heavy quark effective theory

International Nuclear Information System (INIS)

Martynenko, A.P.; Saleev, V.A.

1996-01-01

The fragmentation of b-bar-antiquark into polarized B c * -mesons and b-quark into P-wave (c-bar b) states in the Heavy Quark Effective Theory. The heavy quark fragmentation functions in longitudinally and transversely polarized S-wave b-bar c-states and P-wave mesons containing b-, c-quarks also, with the exact account of corrections of first order in 1/m b . 20 refs., 2 figs

Test of quark fragmentation in the quark-parton model framework

International Nuclear Information System (INIS)

Derrick, M.; Barish, S.J.; Barnes, V.E.

1979-08-01

The hadronic system produced in charged-current antineutrino interactions is used to study fragmentation of the d-quark. Some problems encountered in separating the current quark-fragments are discussed. The fragmentation function for the current quark is in good agreement with the expectations of the naive quark-parton model and, in particular, there is no evidence of either a Q 2 - or x/sub BJ/-dependence. 10 references

Shear viscosity of the quark-gluon plasma in a kinetic theory approach

International Nuclear Information System (INIS)

Puglisi, A.; Plumari, S.; Scardina, F.; Greco, V.

2014-01-01

One of the main results of heavy ions collision (HIC) at relativistic energy experiments is the very small shear viscosity to entropy density ratio of the Quark-Gluon Plasma, close to the conjectured lower bound η/s=1/4π for systems in the infinite coupling limit. Transport coefficients like shear viscosity are responsible of non-equilibrium properties of a system: Green-Kubo relations give us an exact expression to compute these coefficients. We compute shear viscosity numerically using Green-Kubo relation in the framework of Kinetic Theory solving the relativistic transport Boltzmann equation in a finite box with periodic boundary conditions. We investigate a system of particles interacting via anisotropic and energy dependent cross-section in the range of temperature of interest for HIC. Green-Kubo results are in agreement with Chapman-Enskog approximation while Relaxation Time approximation can underestimates the viscosity of a factor 2. The correct analytic formula for shear viscosity can be used to develop a transport theory with a fixed η/s and have a comparison with physical observables like elliptic flow

Relativistic shocks in the systems containing domains with anomalous equation of state and quark baryonic matter hadronization

International Nuclear Information System (INIS)

Bugaev, K.A.; Gorenshtejn, M.I.; Zhdanov, V.I.

1987-01-01

Theoretical basis for general stability criterion of relativistic shocks in baryonic matter is proposed. Different formulations of shock mechanical stability are considered and applied to the analysis of rarefaction shock hadronization transition. 13 refs.; 2 figs

Quark mass effects in quark number susceptibilities

International Nuclear Information System (INIS)

Graf, Thorben; Petreczky, Peter

2017-01-01

The quark degrees of freedom of the QGP with special focus on mass effects are investigated. A next-to-leading-order perturbation theory approach with quark mass dependence is applied and compared to lattice QCD results. (paper)

Strong and electromagnetic interactions in hadron systems

International Nuclear Information System (INIS)

Aissat, N.; Amghar, A.; Cano, F.; Gonzalez, F.; Noguera, S.; Carbonell, J.; Desplanques, B.; Silvestre-Brac, B.; Karmanov, V.; Mathiot, J.F.

1997-01-01

The pionic strong decay amplitudes of baryon resonances are studied in a constituent quark model. Particular attention is given to the operator describing the transition. The nucleon form factors are calculated in a non-relativistic approach, with emphasis on the highest momentum transfers. The aim is to determine the ingredients that are essential in getting correct results and are likely to be required for a more realistic estimate in a fully relativistic approach. The deuteron form factors have been calculated in the light-front approach using wave functions determined in a perturbative way. The derivation of the neutron charge form factor from the deuteron structure function, A(q 2 ), is reanalyzed including further mesonic exchange contributions. (authors)

Thermodynamics and relativistic kinetic theory for q-generalized Bose-Einstein and Fermi-Dirac systems

Energy Technology Data Exchange (ETDEWEB)

Mitra, Sukanya [Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat (India)

2018-01-15

The thermodynamics and covariant kinetic theory are elaborately investigated in a non-extensive environment considering the non-extensive generalization of Bose-Einstein (BE) and Fermi-Dirac (FD) statistics. Starting with Tsallis' entropy formula, the fundamental principles of thermostatistics are established for a grand canonical system having q-generalized BE/FD degrees of freedom. Many particle kinetic theory is set up in terms of the relativistic transport equation with q-generalized Uehling-Uhlenbeck collision term. The conservation laws are realized in terms of appropriate moments of the transport equation. The thermodynamic quantities are obtained in a weak non-extensive environment for a massive pion-nucleon and a massless quark-gluon system with non-zero baryon chemical potential. In order to get an estimate of the impact of non-extensivity on the system dynamics, the q-modified Debye mass and hence the q-modified effective coupling are estimated for a quark-gluon system. (orig.)

[Pion interferometry search for a phase change in hadronic matter in relativistic heavy ion collisions and its application to RHIC: Progress report

Energy Technology Data Exchange (ETDEWEB)

Cherney, M.

1992-05-01

The purpose of this research is to assist in the investigation of the behavior of hadronic matter under extreme conditions. Specifically, this project intends to actively involve Creighton students and faculty in the search for indications of a phase transition from hadronic to quark matter. It is believed that the conditions necessary for the formation of this quark-gluon plasma include large energy densities over extended volumes. The technique of boson interferometry may prove to be the effective tool in verifying the existence of a quark-gluon plasma. This project continues active collaboration with Department of Energy research centers working on the NA36, NA44, and STAR experiments. It involves the effective development of the hardware, software and analytical skills required for a large relativistic heavy ion facility at Brookhaven National Laboratory (RHIC). Integral to this endeavor are educational opportunities for students at Creighton University.

(Pion interferometry search for a phase change in hadronic matter in relativistic heavy ion collisions and its application to RHIC: Progress report)

Energy Technology Data Exchange (ETDEWEB)

Cherney, M.

1992-01-01

The purpose of this research is to assist in the investigation of the behavior of hadronic matter under extreme conditions. Specifically, this project intends to actively involve Creighton students and faculty in the search for indications of a phase transition from hadronic to quark matter. It is believed that the conditions necessary for the formation of this quark-gluon plasma include large energy densities over extended volumes. The technique of boson interferometry may prove to be the effective tool in verifying the existence of a quark-gluon plasma. This project continues active collaboration with Department of Energy research centers working on the NA36, NA44, and STAR experiments. It involves the effective development of the hardware, software and analytical skills required for a large relativistic heavy ion facility at Brookhaven National Laboratory (RHIC). Integral to this endeavor are educational opportunities for students at Creighton University.

[Pion interferometry search for a phase change in hadronic matter in relativistic heavy ion collisions and its application to RHIC: Progress report

International Nuclear Information System (INIS)

Cherney, M.

1992-01-01

The purpose of this research is to assist in the investigation of the behavior of hadronic matter under extreme conditions. Specifically, this project intends to actively involve Creighton students and faculty in the search for indications of a phase transition from hadronic to quark matter. It is believed that the conditions necessary for the formation of this quark-gluon plasma include large energy densities over extended volumes. The technique of boson interferometry may prove to be the effective tool in verifying the existence of a quark-gluon plasma. This project continues active collaboration with Department of Energy research centers working on the NA36, NA44, and STAR experiments. It involves the effective development of the hardware, software and analytical skills required for a large relativistic heavy ion facility at Brookhaven National Laboratory (RHIC). Integral to this endeavor are educational opportunities for students at Creighton University

Charm quark mass with calibrated uncertainty

Energy Technology Data Exchange (ETDEWEB)

Erler, Jens [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico, DF (Mexico); Masjuan, Pere [Universitat Autonoma de Barcelona, Grup de Fisica Teorica, Departament de Fisica, Barcelona (Spain); Institut de Fisica d' Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST), Barcelona (Spain); Spiesberger, Hubert [Johannes Gutenberg-Universitaet, PRISMA Cluster of Excellence, Institut fuer Physik, Mainz (Germany); University of Cape Town, Centre for Theoretical and Mathematical Physics and Department of Physics, Rondebosch (South Africa)

2017-02-15

We determine the charm quark mass m{sub c} from QCD sum rules of the moments of the vector current correlator calculated in perturbative QCD at O(α{sub s}{sup 3}). Only experimental data for the charm resonances below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the zeroth moment. Existing data from the continuum region can then be used to bound the theoretic uncertainty. Our result is m{sub c}(m{sub c}) = 1272 ± 8 MeV for α{sub s}(M{sub Z}) = 0.1182, where the central value is in very good agreement with other recent determinations based on the relativistic sum rule approach. On the other hand, there is considerably less agreement regarding the theory dominated uncertainty and we pay special attention to the question how to quantify and justify it. (orig.)

Femtoscopic analysis of baryon correlations in ultra-relativistic heavy-ion collisions registered by ALICE

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00361630

Heavy-ion collisions at ultra-relativistic energies give a unique possibility to create and to analyse the Quark-Gluon Plasma predicted by the theory of Quantum Chromodynamics. The research on the properties of such state of matter is crucial for understanding the features of the strongly interacting system. Experimental results reveal the collective behaviour of matter created in the heavy-ion collisions at ultra-relativistic energies. The existence of this effect can be verified by the measurement of the transverse mass dependence of the source size extracted using different particle species. Such characteristics can be determined using the analysis technique called femtoscopy. This method is based on the correlations of particles with small relative momenta which originate from the effects of Quantum Statistics as well as the strong and Coulomb Final State Interactions. A recent analysis of the particle production at the highest available collision energies of heavy-ion collisions reveals the puzzling res...

The Quark-Gluon Plasma Collective Dynamics and Hard Thermal Loops

CERN Document Server

Blaizot, J P; Blaizot, Jean-Paul; Iancu, Edmond

2002-01-01

We present a unified description of the high temperature phase of QCD, the so-called quark-gluon plasma, in a regime where the effective gauge coupling $g$ is sufficiently small to allow for weak coupling calculations. The main focuss is the construction of the effective theory for the collective excitations which develop at a typical scale $gT$, which is well separated from the typical energy of single particle excitations which is the temperature $T$. We show that the plasma particles provide a source for long wavelength oscillations of average fields which carry the quantum numbers of the plasma constituents, the quarks and the gluons. To leading order in $g$, the plasma particles obey simple gauge-covariant kinetic equations, whose derivation from the general Dyson-Schwinger equations is outlined. As a by-product, the ``hard thermal loops'' emerge naturally in a physically transparent framework. We show that the collective excitations can be described in terms of classical fields, and develop for these a ...

Method of taking into account the meson and quark-gluon degrees of freedom in hadron-hadron interactions at low and intermediate energies. Application to NN scattering

International Nuclear Information System (INIS)

Safronov, A.N.

1983-01-01

A system of nonsingular integral equations is formulated for calculation of the partial-wave amplitudes of hadron-hadron scattering in the region of low and intermediate energies with allowance for the meson and quark-gluon degrees of freedom. The quark-gluon degrees of freedom are taken into account in the framework of the model of composite quark bags, and the meson degrees of freedom by the methods of relativistic quantum field theory. It is shown that inclusion of the quark-gluon degrees of freedom leads to suppression of meson exchange effects, for the most part exchanges of heavy mesons (rho,ω). The method is applied to the calculation of the 3 S 1 , 1 S 0 , 3 P 0 , 3 P 1 , and 1 P 1 phase shifts of nucleon-nucleon scattering in the range of incident-nucleon energies T = 0--1050 MeV, as well as the S-wave scattering lengths and effective ranges

1/mQ corrections to form factors and extraction of |Vcb|

International Nuclear Information System (INIS)

Liu, J.; Chao, K.

1997-01-01

Form factors for 0 - →0 - and 0 - →1 - mesonic transitions in the heavy quark limit and the 1/m Q corrections are analyzed model independently within the Bethe-Salpeter (BS) formalism. The analysis shows that the BS formalism has spin-flavor symmetry in the heavy quark limit and respects Luke's theorem when the 1/m Q corrections are taken into account. All form factors for B→D (*) transitions beyond the zero recoil point are estimated in a relativistic constituent quark model based on the BS formalism. Using these form factors we calculate the branching ratios for the semileptonic decays B→D (*) l + ν l and extract the Cabibbo-Kobayashi-Maskawa matrix element |V cb |. We get |V cb |=0.042±0.003 which is consistent with the current world average. copyright 1997 The American Physical Society

PADÉ APPROXIMANTS FOR THE EQUATION OF STATE FOR RELATIVISTIC HYDRODYNAMICS BY KINETIC THEORY

Energy Technology Data Exchange (ETDEWEB)

Tsai, Shang-Hsi; Yang, Jaw-Yen, E-mail: shanghsi@gmail.com [Institute of Applied Mechanics, National Taiwan University, Taipei 10764, Taiwan (China)

2015-07-20

A two-point Padé approximant (TPPA) algorithm is developed for the equation of state (EOS) for relativistic hydrodynamic systems, which are described by the classical Maxwell–Boltzmann statistics and the semiclassical Fermi–Dirac statistics with complete degeneracy. The underlying rational function is determined by the ratios of the macroscopic state variables with various orders of accuracy taken at the extreme relativistic limits. The nonunique TPPAs are validated by Taub's inequality for the consistency of the kinetic theory and the special theory of relativity. The proposed TPPA is utilized in deriving the EOS of the dilute gas and in calculating the specific heat capacity, the adiabatic index function, and the isentropic sound speed of the ideal gas. Some general guidelines are provided for the application of an arbitrary accuracy requirement. The superiority of the proposed TPPA is manifested in manipulating the constituent polynomials of the approximants, which avoids the arithmetic complexity of struggling with the modified Bessel functions and the hyperbolic trigonometric functions arising from the relativistic kinetic theory.

Relativistic equations

International Nuclear Information System (INIS)

Gross, F.

1986-01-01

Relativistic equations for two and three body scattering are discussed. Particular attention is paid to relativistic three body kinetics because of recent form factor measurements of the Helium 3 - Hydrogen 3 system recently completed at Saclay and Bates and the accompanying speculation that relativistic effects are important for understanding the three nucleon system. 16 refs., 4 figs

Diquark condensation and the quark-quark interaction

International Nuclear Information System (INIS)

Bloch, J. C. R.; Roberts, C. D.; Schmidt, S. M.

1999-01-01

We employ a bispinor gap equation to study superfluidity at nonzero chemical potential, μ≠0, in two- and three-color QCD, exploring the gap's sensitivity to the nature of the quark-quark interaction. The two-color theory, QC 2 D, is an excellent exemplar; the order of truncation of the quark-quark scattering kernel K has no qualitative impact, which allows a straightforward elucidation of the effects of μ when the coupling is strong. In the three-color theory the rainbow-ladder truncation admits diquark bound states, a defect that is eliminated by an improvement of K. The corrected gap equation describes a superfluid phase that is semiquantitatively similar to that obtained using the rainbow truncation. A model study suggests that the width of the superfluid gap and the transition point in QC 2 D provide reliable quantitative estimates of those quantities in QCD. (c) 1999 The American Physical Society

Duality and quarks

International Nuclear Information System (INIS)

Volkov, D.V.; Zheltukhin, A.A.; Pashnev, A.I.

1975-01-01

As it has shown, the study of vacuum transitions in dual models makes it possible to establish certain relations between duality, on the one hand, and the quark structure of resonances and the internal symmetries, on the other. In the case of Veneziano model the corresponding quark structure of resonances is determined by the infinity number of quarks of increasing mass. The intercents of the main trajectory and all adopted trajectories are additive with respect to squares of mass-forming quarks. The latter circumstance results in a number of important consequences: the presence of quadratic mass formulas for resonance states; the exact SU(infinity)-symmetry for the three-resonance coupling constants; the validity of Adler's self-consistency principle for external particles composed of different quarks and anti-quarks, etc

Ultra-relativistic heavy ions and cosmic rays

International Nuclear Information System (INIS)

McLerran, L.

1983-05-01

The collisions of ultra-relativistic heavy ions, E/sub /N/ greater than or equal to 1 TeV/nucleon are most interesting, since, at these energies, matter is produced at sufficiently high energy density that a quark-gluon plasma has a good chance to form. Very heavy ions are also most interesting since the matter forms in a larger volume than for light ions, and the matter is at a somewhat higher energy density. At very high energies with very heavy ions there is great flexibility in the experimental signals which might be studied, as well as the nature of the matter which is produced. The fragmentation region and central region provide different environments where a plasma might form. The former is baryon rich while the central region is high temperature with low baryon number density and is not accessible except at very high energies