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.     

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.     

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 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.     

Model independent bounds on the modulus of the pion form factor on the unitarity cut below the ωπ threshold

We study the structure of local baryon fields using the method of QCD sum rule. We only consider the single baryon fields and calculate their operator product expansions. We find that the octet baryon fields belonging to the chiral representations $[(\mathbf{3},\bar{\mathbf{3}}) \oplus(\bar{\mathbf{3}}, \mathbf{3})]$ and [(8,1)??(1,8)] and the decuplet baryon fields belonging to the chiral representations [(3,6)??(6,3)] lead to the baryon masses which are consistent with the experimental data of ground baryon masses. We also calculate their decay constants, check our normalizations for baryon fields in Chen et?al. (Phys. Rev.?D 81:054002, 2009) and find that they are well-defined.     

Baryon number generation from cosmic string loops

Baryon number generation due to the decay of particle-antiparticle pairs created from cosmic string loops is studied. In the situation when cusp evaporation occurs a significant baryon asymmetry (baryon/entropy ∼ 10⁻⁴ ϵ: ϵ is a net baryon asymmetry generated from one pair of particle-antiparticle) can be generated.     

Baryon asymmetry, inflation and squeezed states

We use the general formalism of squeezed rotated states to calculate baryon asymmetry in the wake of inflation through parametric amplification. We base our analysis on a B and CP violating Lagrangian in an isotropically expanding universe. The B and CP violating terms originate from the coupling of complex fields with non-zero baryon number to a complex background inflaton field. We show that a differential amplification of particle and antiparticle modes gives rise to baryon asymmetry.     

Thermodynamic generation of the baryon asymmetry

A new technique for generating the baryon asymmetry of the universe is discussed. By using the natural CPT non-invariance of the universe during its early history, we discuss how a baryon asymmetry can develop while baryon violating interactions are still in thermal equilibrium with respect to an effective hamiltonian. Furthermore, both the ground state and fundamental interactions in these theories can be CP conserving.     

Baryon production in lepton-nucleon scattering and diquark fragmentation

We study baryon production in deep inelastic scattering using an extended version of the Lund jet model. There are two contributing sources. The first is baryon production in the target fragmentation. In a scheme related to our earlier work on lowp _hu baryon fragmentation we present some details of the fragmentation of a diquark into baryons and mesons. A non-negligible baryon-antibaryon production is observed ine ⁺ e ^? annihilation. In a previous paper we developed a model for this production, and the same mechanism should also give fast baryons in leptoproduction. In this paper we discuss those features of baryon production which can be more easily studied in a leptoproduction experiment.     

Baryon resonances and their properties from the CLAS data

The study of the baryon spectrum is a fundamental part of the scientific program in Hall B at Jefferson Lab. By using the CLAS detector, reactions involving electromagnetic production of exclusive hadronic final states in the kinematic region of baryon resonances have been extensively measured, with the purpose of extracting information on non-strange baryon excited states. Some selected topics in the N ^* CLAS experimental program are outlined and corresponding new experimental results are reported and briefly discussed.     

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.     

Baryon exchange processes

The theory and phenomenology of baryon exchange processes are critically reviewed. As regards theory the main topics are the parity doublet problem and the patterns of exchange degenerate baryon trajectories implied by duality. In the phenomenological part, all baryon exchange reactions are considered, with the emphasis being on seeing how far simple ideas of pole exchange with the constraints implied by duality and broken SU(3) can be taken in forming an understanding of the data.     

Baryons in dual unitarization and dynamical thresholds

Baryon exchange and baryon resonance production is introduced in the dual unitarisation scheme. The dynamical threshold for the production of meson and baryon resonances is incorporated. It is shown that the intercepts of the ω and the f, which are generated by baryons, are suppressed by the above dynamical threshold effects to $\text{α}{}_{\mathrm{\omega }}\text{(0) ? 0}$ and α_f(0) < 0. The pomeron is shifted slightly upwards by baryon production. An upper limit is determined for the ratio of the crossed and uncrossed produced baryon lines. The breaking of the Freund-Rosner-Walz rule is discussed.     

Dark matter and the baryon asymmetry of the universe

We present a mechanism to generate the baryon asymmetry of the Universe which preserves the net baryon number created in the big bang. If dark matter particles carry baryon number Bx, and sigmaxannih相似文献   

Electroweak sphalerons with spin and charge

We show that, at finite weak mixing angle the sphaleron solution of Weinberg–Salam theory can be endowed with angular momentum proportional to the electric charge. Carrying baryon number 1/2 these sphalerons with spin and charge may contribute to baryon number violating processes.     

Elementary examples of baryon number generation

Elementary examples are provided of reaction rate matrices satisfying the constraints of unitarity and CPT invariance, which can lead a system with baryon number initially zero to evolve toward non-zero baryon number. The importance of the unitarity constraint is emphasized.