Deconfinement and chiral restoration in nonlocal SU(3) chiral quark models

We study the features of nonlocal SU(3) chiral quark models with wave function renormalization. Model parameters are determined from meson phenomenology, considering different nonlocal form factor shapes. In this context we analyze the characteristics of the deconfinement and chiral restoration transitions at finite temperature, introducing the couplings of fermions to the Polyakov loop. We analyze the results obtained for various thermodynamical quantities considering different Polyakov loop potentials and nonlocal form factors, in comparison with data obtained from lattice QCD calculations.Comment: 25 pages, 5 figures. Discussion of results enlarged, figures modified, references added. Version to appear in Physical Review

Generalized Ginzburg-Landau approach to inhomogeneous phases in nonlocal chiral quark models

We analyze the presence of inhomogeneous phases in the QCD phase diagram within the framework of nonlocal chiral quark models. We concentrate in particular in the positions of the tricritical (TCP) and Lifshitz (LP) points, which are studied in a general context using a generalized Ginzburg-Landau approach. We find that for all the phenomenologically acceptable model parametrizations considered the TCP is located at a higher temperature and a lower chemical potential in comparison with the LP. Consequently, these models seem to favor a scenario in which the onset of the first order transition between homogeneous phases is not covered by an inhomogeneous, energetically favored phase.Comment: 9 pages, 1 figure. V2: Two references added, figure modified, minor changes in the text introduced. Matches version to be published in Physics Letters

Inhomogeneous phases in nonlocal chiral quark models

The presence of inhomogeneous phases in the QCD phase diagram is analyzed within chiral quark models that include nonlocal interactions. We work at the mean field level, assuming that the spatial dependence of scalar and pseudo-scalar condensates is given by a dual chiral density wave. Phase diagrams for Gaussian nonlocal form factors are studied in detail and compared with those obtained within the Nambu-Jona-Lasinio model and quark-meson approaches.Comment: 14 pages, 3 figure

Effect of Inter-Site Repulsions on Magnetic Susceptibility of One-Dimensional Electron Systems at Quarter-Filling

The temperature dependence of the magnetic susceptibility, \chi (T), is investigated for one-dimensional interacting electron systems at quarter-filling within the Kadanoff-Wilson renormalization-group method. The forward scattering on the same branch (the g_4-process) is examined together with the backward (g_1) and forward (g_2) scattering amplitudes on opposite branches. In connection with lattice models, we show that \chi (T) is strongly enhanced by the nearest-neighbor interaction, an enhancement that surpasses one of the next-nearest-neighbor interaction. A connection between our predictions for \chi (T) and experimental results for \chi (T) in quasi-one-dimensional organic conductors is presented.Comment: 4 pages, 4 figures, to be published in Journal of the Physical Society of Japan, vol. 74, No. 1

tau -> pi pi pi nu_tau decays and the a_1(1260) off-shell width revisited

The tau -> pi pi pi nu_tau decay is driven by the hadronization of the axial-vector current. Within the resonance chiral theory, and considering the large-Nc expansion, this process has been studied in Ref.[1]. In the light of later developments we revise here this previous work by including a new off-shell width for the lightest a_1 resonance that provides a good description of the tau -> pi pi pi nu_tau spectrum and branching ratio. We also consider the role of the rho(1450) resonance in these observables. Thus we bring in an overall description of the tau -> pi pi pi nu_tau process in excellent agreement with our present experimental knowledge.Comment: 15 pages, 3 figure

Hadron structure in tau -> KKpi nu_tau decays

We analyse the hadronization structure of both vector and axial-vector currents leading to tau -> KKpi nu_tau decays. At leading order in the 1/Nc expansion, and considering only the contribution of the lightest resonances, we work out, within the framework of the resonance chiral Lagrangian, the structure of the local vertices involved in those processes. The couplings in the resonance theory are constrained by imposing the asymptotic behaviour of vector and axial-vector spectral functions ruled by QCD. In this way we predict the hadron spectra and conclude that, contrarily to previous assertions, the vector contribution dominates by far over the axial-vector one in all KKpi charge channels.Comment: 32 pages, 7 figure

T−μT {-} \mu quark matter phase transitions and critical end point in nonlocal PNJL models

We study the $T {-} {\mu}$ phase diagram of quark matter under the influence of a strong uniform magnetic field in the framework of a nonlocal extension of the Polyakov Nambu Jona Lasinio model (PNJL). The existence of a critical end point (CEP) is found for the whole considered range of the magnetic field (up to 1 $GeV^{2}$). We analyze the location of this CEP as a function of the external field and discuss the presence of inverse magnetic catalysis for nonzero chemical potentials. Our results show that the temperature of the CEP decreases with the magnetic field, in contrast to the behavior observed in local NJL/PNJL models

High field magnetic resonant properties of beta'-(ET)2SF5CF2SO3

A systematic electron spin resonance (ESR) investigation of the low temperature regime for the (ET)2SF5CF2SO3 system was performed in the frequency range of ~200-700 GHz, using backward wave oscillator sources, and at fields up to 25 T. Newly acquired access to the high frequency and fields shows experimental ESR results in agreement with the nuclear magnetic resonance (NMR) investigation, revealing evidence that the transition seen at 20 K is not of conventional spin-Peierls order. A significant change of the spin resonance spectrum in beta'-(ET)2SF5CF2SO3 at low temperatures, indicates a transition into a three-dimensional-antiferromagnetic (3D AFM) phase.Comment: 4 pages, 7 figures, minor grammatical change

Rare Kaon Decay K^+ --> \pi^+ \nu \bar{\nu} in SU(3)_C X SU(3)_L X U(1)_N Models

The rare kaon decay K^+ --> \pi^+ \nu \bar{\nu} is considered in the framework of the models based on the SU(3)_C X SU(3)_L X U(1)_N (3 - 3 - 1) gauge group. It is shown that a lower bound of the Z' mass in the 3 - 3 - 1 model with right-handed neutrinos at a value of 3 TeV is derived, while that in the minimal version -- 1.7 TeV.Comment: 7 pages, 1 figure, late

Charged pseudoscalar and vector meson masses under strong magnetic fields in an extended NJL model

The mass spectrum of $\pi^+$ and $\rho^+$ mesons in the presence of a static uniform magnetic field $\vec B$ is studied within a two-flavor NJL-like model. We improve previous calculations taking into account the effect of Schwinger phases carried by quark propagators, and using an expansion of meson fields in terms of the solutions of the corresponding equations of motion for nonzero $B$. It is shown that the meson polarization functions are diagonal in this basis. Our numerical results for the $\rho^+$ meson spectrum are found to disfavor the existence of a meson condensate induced by the magnetic field. In the case of the $\pi^+$ meson, $\pi$ - $\rho$ mixing effects are analyzed for the meson lowest energy state. The predictions of the model are compared with available lattice QCD results.Comment: 35 pages, 4 figures. arXiv admin note: text overlap with arXiv:2205.1592