Fluctuations of the order parameter chiral transition in a hot and dense quark gas are examined random-phase approximation with use QCD-motivated effective Lagrangian. We show that there arise soft modes having large strength narrow width above critical temperature, which analogous to fluctuations superconductor point. It is argued contribute cooling quark-gluon plasma.

Recent lattice-gauge-theory simulations at finite temperatures have suggested that chiral-symmetry restoration entails parity doubling of the baryon spectrum. We show a natural extension Gell-Mann--L\'evy model incorporates this effect. Predictions candidate effective for hadronic component high-density and high-temperature nuclear matter are discussed. The suggests parametrization dependence baryon-doublet masses on quark mass. This is compared with recent lattice results.

Spectral enhancement near the ${2m}_{\ensuremath{\pi}}$ threshold in $I\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}J\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ channel nuclei is shown to be a distinct signal of partial restoration chiral symmetry. The relevance this phenomenon with possible detection $2{\ensuremath{\pi}}^{0}$ and $2\ensuremath{\gamma}$ hadron-nucleus photon-nucleus reactions discussed.

On the basis of classical theory envelopes, we formulate renormalization group (RG) method for global analysis, recently proposed by Goldenfeld et al. It is clarified why RG equation improves things.

We report a project to study scalar particles by lattice QCD simulations. After brief introduction of the current situation sigma meson, we describe our numerical simulations mesons, $\sigma$ and $\kappa$. observe low mass, $m_\pi<m_\sigma\le m_\rho$, for which disconnected diagram plays an important role. For kappa obtain higher mass than experimental value, i.e., $m_\kappa\sim 2m_{K^*}$.

Baryon resonances with even and odd parity are collectively investigated from the viewpoint of chiral symmetry (ChS). We propose a quartet scheme where Delta's N(*)'s form multiplet. This gives parameter-free constraints on baryon masses in quartet, which consistent observed spin 1 / 2,3 2,5 2. The also selection rules one-pion decay: absence nonchanging decay N(1720)-->piDelta(1232) is typical example should be confirmed experimentally to unravel role ChS resonances.

We derive generic relativistic hydrodynamical equations with dissipative effects from the underlying Boltzmann equation in a mechanical and systematic way on basis of so-called renormalization-group method. A macroscopic frame vector is introduced to specify which dynamics described. Our method so only few ansatz that our gives microscopic foundation available equations, also can be applied make reduction kinetic other than simple equation.

Understanding the underlying mechanisms causing rapid thermalization deduced for high-energy heavy ion collisions is still a challenge. To estimate time, entropy growth classical Yang-Mills theories studied, based on determination of Lyapunov exponents. Distinct regimes short, medium and long sampling times are characterized by different properties their spectrum Clarifying existence these implications gauge-field dynamics one results this article. As phenomenological application we conclude...

The renormalization group method of Goldenfeld, Oono and their collaborators is applied to asymptotic analysis vector fields. formulated on the basis theory envelopes, as was done for scalar This formulation actually completes discussion previous work equations. It shown in a generic way that equations with bifurcation leads Landau-Stuart (time-dependent) Ginzburg-Landau confirmed this powerful reduction dynamics reductive perturbation is. Some examples ordinary diferential equations, such...

We investigate the possible precursory phenomena of color superconductivity in quark matter at finite temperature T with use a low-energy effective theory QCD. It is found that fluctuating pair field exists prominent strength even well above critical ${T}_{c}.$ show collective has complex energy located second Riemann sheet, which approaches origin as lowered to discuss relevance precursor observables be detected heavy ion collisions.

We make an intensive investigation of the soft mode at quantum chromodynamics (QCD) criticalpoint on basis functional renormalization group (FRG)method in local potential approximation. calculate spectral functions|$\rho_{\sigma, \pi}(\omega,\, p)$| scalar (⁠|$\sigma$|⁠) andpseudoscalar (⁠|$\pi$|⁠) channels beyond random phase approximation inthe quark–meson model. At finite baryon chemical |$\mu$| with afinite quark mass, baryon-number fluctuation is coupled to thescalar channel and...

The dynamical symmetry breaking phenomena in the Nambu and Jona-Lasinio model are reexamined framework of a self-consistent mean-field (SCMF) theory. First, we formulate SCMF theory lucid manner based on successful decomposition Lagrangian into semiclassical residual interaction parts by imposing condition that "the dangerous term" Bogoliubov's sense should vanish. Then, show difference energy density between super normal phases, correct expression which original authors failed to give, can...

We study the possible significance of four-quark states in isosinglet scalar mesons (${J}^{PC}={0}^{++}$, $I=0$) by performing two-flavor full lattice QCD simulations on an ${8}^{3}\ifmmode\times\else\texttimes\fi{}16$ using improved gauge action and clover-improved Wilson quark action. In particular, we evaluate propagators molecular tetraquark operators together with singly disconnected diagrams. computation diagrams employ ${Z}_{2}$-noise method truncated eigenmode approach. show that...