A Chiral Quark Soliton Model for the Baryon Embedded in Nuclear Medium

A chiral quark soliton model for the baryon embedded in nuclear medium is proposed. The effective vacuum expectation value of the scalar field felt up by a quark of the baryon in nuclear medium is estimated. The model is solved for the hedgehog baryon state in the semiclassical approximation and self-conskitent approach. Some static properties of the baryon embedded in nuclear medium are calculated. An increment in ra&ns af the baryon is obtained. The numerical results can be used to explain the A-dependence of EMC effect and vacqum pressure constants in nuclear medium.     

Baryon recoil and the fragmentation regions in ultra-relativistic nuclear collisions

The maximum baryon and energy densities reached in the fragmentation regions of nuclear collisions are estimated with a new hydrodynamical model. Unlike previous models where recoil is included as a source term for the baryon current, in our model the baryon current is strictly conserved. The parameters of the model are furthermore adjusted to take into account the large baryon rapidity shifts observed recently in p + A → p + X. The implications for the production of high baryon density quark-gluon plasmas are discussed.     

大N_c集体激发理论下的重子共振态

最近Diakonov考虑了大Nc平均场近似下重子共振态谱的海夸克效应并提出重子共振态谱的集体激发理论,该理论恰好是SU(6)夸克模型的一种推广。检查了Diakonov重子谱理论中介子张量势的物理含义并给出重子共振态谱公式参数的数值优化。发现,重子共振态谱公式能够与2 Ge V以下重子谱良好吻合。     

A Monte Carlo model to produce baryons ine + e − annihilation

A simple model is described extending the Field-Feynman model to baryon production in quark fragmentation. The model predicts baryon baryon correlations within jets and in opposite jets produced in electron-positron annihilation. Existing data is well described by the model.     

Baryon–Baryon and Meson–Baryon Potentials with QCD-Based Short-Range Cores

A unified potential model of baryon–baryon and meson–baryon interactions at low energies is proposed. In this model, the short-range cores which simulate recent lattice QCD calculations are introduced. In baryon–baryon sector, our potentials give a very good agreement with NN and YN scattering data and have very similar behavior to those from the lattice QCD calculations. The π N and KN interactions are also well described in our model.     

Spontaneous baryogenesis

The recently discovered mechanism of “spontaneous baryogenesis” for generating the baryon asymmetry is implemented in several particle physics models. In these scenarios, baryon number is an approximate symmetry spontaneously broken at a scale |;. The baryon asymmetry is generated without CP violation. Furthermore, this can come about during an epoch when baryon violation is in thermal equilibrium. We consider how various observational constraints affect the realization of this mechanism in acceptable models of particle interactions, and find that the observed baryon asymmetry can be produced for |;≳ 3 × 10¹³ GeV.     

Prediction,supported by data,of a qualitative breaking of SU3 for baryon resonance decay rates

In the light of recently reported difficulties met by SU3 in comparing with experimental decay rates of baryon resonances, we present an alternative scheme which provides a simple understanding of yet unexplained features of baryon resonance data, and which implies a qualitative breaking of SU3 for baryon resonance decay rates.     

Heavy flavor baryon spectra via QCD sum rules

In this talk, we give a short review of our recent works on studying the singly heavy baryon, doubly heavy baryon, and triply heavy baryon spectra from QCD sum rules.     

Wave function renormalization in heavy baryon chiral perturbation theory

We establish exact relations between relativistic form factors and amplitudes for single-baryon processes and the corresponding quantities calculated in the framework of heavy baryon chiral perturbation theory. A crucial ingredient for the proper matching is the first complete treatment of baryon wave function renormalization in heavy baryon chiral perturbation theory.     

Molecular dynamics simulation for the baryon-quark phase transition at finite baryon density

We study the baryon-quark phase transition in the molecular dynamics (MD) of the quark degrees of freedom at finite baryon density. The baryon state at low baryon density, and the deconfined quark state at high baryon density are reproduced. We investigate the equations of state of matters with different u-d-s compositions. It is found that the baryon-quark transition is sensitive to the quark width.     

Influence of Entropy on Composition and Structure of Massive Protoneutron Stars

Adjusting the suitable coupling constants in relativistic mean field (RMF) theory and focusing on thermal effect of an entropy per baryon (S) from 0 to 3, we investigate the composition and structure of massive protoneutron stars corresponding PSR J1614-2230 and PSR J0348+0432. It is found that massive protoneutron stars (PNSs) have more hyperons than cold neutron stars. The entropy per baryon will stiffen the equation of state, and the influence on the pressure is more obvious at low density than high density, while the influence on the energy density is more obvious at high density than low density. It is found that higher entropy will give higher maximum mass, higher central temperature and lower central density. The entropy per baryon changes from 0 to 3, the radius of a PNS corresponding PSR J0348+0432 will increase from 12.86 km to 19.31 km and PSR J1612-2230 will increase from 13.03 km to 19.93 km. The entropy per baryon will raise the central temperature of massive PNSs in higher entropy per baryon, but the central temperature of massive PNSs maybe keep unchanged in lower entropy per baryon. The entropy per baryon will increase the moment of inertia of a massive protoneutron star, while decrease gravitational redshift of a massive neutron star.     

Decuplet contribution to the meson–baryon scattering lengths

We calculate decuplet contributions to the s-wave pseudoscalar meson octet–baryon scattering lengths to the third order in heavy baryon chiral perturbation theory (HBχPT). Using experimental pion–nucleon and kaon–nucleon scattering lengths as inputs, we determine low-energy constants and predict other meson–baryon scattering lengths. Numerically we consider three cases: (1) the case with only baryon octet contributions; (2) with decuplet contributions and (3) in the large N_c limit. Hopefully, the analytical expressions and the predictions are helpful to future investigations of the meson–baryon scattering lengths. PACS 13.75.Gx; 13.75.Jz     

Baryon production in the string fragmentation picture

An improved version of the “pop-corn” model for baryon production in quark and gluon jets is presented. With a reduced number of parameters the model reproduces well both production rates for different baryon species and baryon momentum distributions. Predictions are presented for a set of baryon-antibaryon correlations.     

Heavy flavor baryon spectra via QCD sum rules

In this talk, we give a short review of our recent works on studying the singly heavy baryon, doubly heavy baryon, and triply heavy baryon Spectra from QCD sum rules.     

Confining Potential Mode in Baryons Spectrum

Based on the flux tube model, the effects of the confining potentials of different configurations, namely the △-type and the Y-type, on the spectra of baryons are studied on SUSF（6） basis. The baryon spectra are obtained in a unified manner. Our result shows that by employing either the △-mode or the Y-mode confining potential, one can achieve reasonable baryon spectra. The △-mode may be mostly effective for the short- and medium-distances, while the Y-mode may offer more contributions to the spectra for long-distances. Although the binding energies in baryon spectra may deviate by a few to several tens MeV for different modes, it is hard to determine either one to be dominant by simply evaluating the baryon spectra. One may need to invoke the baryon decay process to make further judgement.     

Proton fluctuations

We survey the utility of net baryon number fluctuations in a rapidity interval as a probe of baryon production in nuclear collisions.     

Fluctuations as probe of the QCD phase transition and freeze-out in heavy ion collisions at LHC and RHIC

We discuss the relevance of higher order cumulants of net baryon number fluctuations for the analysis of freeze-out and critical conditions in heavy ion collisions at LHC and RHIC. Using properties of O(4) scaling functions, we discuss the generic structure of these higher cumulants at vanishing baryon chemical potential and apply chiral model calculations to explore their properties at non-zero baryon chemical potential. We show that the ratios of the sixth to second and eighth to second order cumulants of the net baryon number fluctuations change rapidly in the transition region of the QCD phase diagram. Already at vanishing baryon chemical potential they deviate considerably from the predictions of the hadron resonance gas model which reproduce the second and fourth order cumulants of the net proton number fluctuations at RHIC. We point out that the sixth order cumulants of baryon number and electric charge fluctuations remain negative at the chiral transition temperature. Thus, they offer the possibility to probe the proximity of the chemical freeze-out to the crossover line.     

暗能量和重子数等曲率扰动

文章对作为暗能量候选者之一的Quintessence场与物质的相互作用及其在宇宙学中的应用进行了研究,通过引入Quintessence与重子流的耦合合理地解释了重子与反重子的不对称性.另外还详细地计算了重子数等曲率扰动.     

Intriguing aspects in baryon production at relativistic heavy-ion collider

We review experimental results on baryon production at mid-rapidity in nucleus-nucleus collisions at RHIC. Outstanding physics issues include the mechanism for baryon-anti-baryon production from thermally equilibrated partons, the dynamics of baryon number transport and the evolution dynamics of baryons during hadronic expansion before the final freeze-out. We highlight recent measurements on the production of protons, lambdas and their anti-particles in terms of these physics issues. We propose a physical mechanism of topological baryon formation through gluon junction hadronization and future measurements, which can test this hypothesis experimentally.