Extended Nambu Jona-Lasinio Model Research Articles

Decays of radially excited vector mesons ρ′ and ω′ in the extended NJL model

The decay widths of [Formula: see text], [Formula: see text] and [Formula: see text] are recalculated within the extended Nambu–Jona-Lasinio (NJL) quark model. It is shown that the mass of [Formula: see text] meson derived in the NJL model agrees with the one given in Particle Data Group tables but significantly deviates from the recent result of CMD-3 collaboration. Comparisons with earlier theoretical results are presented.

Anisotropy of magnetized quark matter

Strong transient magnetic fields are generated in noncentral relativistic heavy-ion collisions. These fields induce anisotropy within the strongly interacting medium that, in principle, can affect the thermodynamic properties of the medium. We use the Polyakov loop extended Nambu Jona-Lasinio model to study the quark matter subjected to an external magnetic field at vanishing baryon chemical potential (μB). We have estimated the degree of anisotropy in the speed of sound and isothermal compressibility within the magnetized quark matter as a function of temperature (T) and magnetic field (). This study helps us to understand the extent of directionality generated in the initial stages of noncentral collisions while giving us useful information about the system. Published by the American Physical Society 2024

Neutral pseudoscalar and vector meson masses under strong magnetic fields in an extended NJL model: Mixing effects

Mixing effects on the mass spectrum of light neutral pseudoscalar and vector mesons in the presence of an external uniform magnetic field $\vec B$ are studied in the framework of a two-flavor NJL-like model. The model includes isoscalar and isovector couplings both in the scalar-pseudoscalar and vector sectors, and also incorporates flavor mixing through a 't Hooft-like term. Numerical results for the $B$ dependence of meson masses are compared with present lattice QCD results. In particular, it is shown that the mixing between pseudoscalar and vector meson states leads to a significant reduction of the mass of the lightest state. The role of chiral symmetry and the effect of the alignment of quark magnetic moments in the presence of the magnetic field are discussed.

Calculation of the Width of the τ → K–K 0 ντ Decay in the Extended Nambu–Jona-Lasinio Model with Estimation of the Contribution from the Final-State Interaction

The branching fraction of the decay $\tau \to K^{-} K^{0} \nu_{\tau}$ is calculated in the framework of the extended Nambu--Jona-Lasinio model. The contact and vector channels are considered. The contributions to this process of the $\rho$ meson in the ground and first radially excited states are taken into account in the vector channel. The obtained results are in satisfactory agreement with the experimental data. Taking into account the kaon interaction in the final state results in insignificant corrections, which are not beyond the scope of the model uncertainties.

τ → K–ηντ Decay in the Extended Nambu–Jona-Lasinio Model Including the Final-State Interaction

τ → K–ηντ Decay in the Extended Nambu–Jona-Lasinio Model Including the Final-State Interaction

Influences of magnetic field on the coexistence of diquark and chiral condensates in the Nambu–Jona–Lasinio model with axial anomaly

In this paper, we study the influences of magnetic fields on the coexistence of diquark and chiral condensates in an extended Nambu–Jona–Lasinio model with QCD axial anomaly, as it relates to color-flavor-locked quark matter. Due to the coupling of rotated-charged quarks to magnetic fields, diquark condensates become split, and the coexistence region is thus superseded in favor of a specific diquark Bose–Einstein condensation (BEC), denoted as the BECI phase. For strong magnetic fields, we find that the BECI transition is pushed to larger quark chemical potentials. The effect of magnetic catalysis tends to disrupt the BEC–BCS (Bardeen–Cooper–Schrieffer) crossover predicted in previous works. For intermediate fields, the effect of inverse magnetic catalysis is observed, and the axial-anomaly-induced phase structure is essentially unchanged.

The decay τ → K∗0(892)K−ντ in the extended NJL model

In the extended Nambu–Jona-Lasinio model, the branching fraction of [Formula: see text] is calculated. The contributions from the contact diagram and the diagrams with intermediate axial-vector, vector and pseudoscalar mesons in the ground and first radially excited states are taken into account. It is shown that an axial-vector and vector channel with a contact diagram give a dominant contribution to the branching fraction. The obtained results for the branching fraction [Formula: see text] are in satisfactory agreement with experimental data. A prediction for the differential distribution over the invariant mass of the meson pair [Formula: see text] is given.

The decays τ → (K,K(1460))ντ and the value of the weak decay constants FK and FK′ in the extended NJL model

In the extended Nambu–Jona-Lasinio (NJL) model, the decay widths of [Formula: see text], [Formula: see text] are calculated. The contributions from intermediate axial-vector mesons [Formula: see text], [Formula: see text] and the first radially excited state [Formula: see text] are taken into account. Estimates for the weak decay constants [Formula: see text] and [Formula: see text] are given. Predictions are made for the width of [Formula: see text] decay and [Formula: see text] constant.

On the Dependence of the Widths of the τ → [ρ0(770), ρ0(1450)] π−ντ Decays on the Parameters of the Intermediate a1 Meson

The widths of the τ → [ρ0(770), ρ0(1450)]π−ντ decays have been calculated within the extended Nambu—Jona-Lasinio model including both the ground and first radially excited intermediate meson states. The axial-vector channel with intermediate a1 mesons dominates. The values of the masses and total widths of the a1 meson recently obtained by the COMPASS and JPAC Collaborations have been taken into account.

Low-energy process e+e−→K+K− in the extended Nambu–Jona-Lasinio model

The process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$ is described in the framework of the Nambu--Jona-Lasinio model in the energy region 1--1.7 GeV. The contact terms with intermediate photon and terms with intermediate $\ensuremath{\rho},\phantom{\rule{0.16em}{0ex}}\ensuremath{\omega}$, and $\ensuremath{\phi}$ vector mesons in the ground and first radially excited states are taken into account. Our results are in satisfactory agreement with experimental data recently obtained at VEPP-2000 and SLAC.

Strangeness Fluctuation Using PNJL Model

The properties of net kaon fluctuations in nuclear matter has been studied within Polyakov loop extended Nambu–Jona-Lasinio model. The ratio of fourth order moment to second order moment (kurtosis) and the third order moment to the second order moment (skewness) of strangeness fluctuations have been calculated and compared with the recent experimental results.

Production ρ(770) of Meson Pairs in the Decays ρ(1450) → ρ(770)η and τ → ρ(770)ηντ and in the Process e+e– → ρ(770)η in the Extended Nambu–Jona-Lasinio Model

Production of $\rho(770)$, $\eta$ pairs at colliding of electron-positron beams and in the decays $\rho(1450)\rightarrow \rho(770)\eta$, $\tau\rightarrow \rho(770)\eta\nu_{\tau}$ is calculated in the framework of the Nambu - Jona-Lasinio model. In the process of electron-positron annihilation and the $\tau$ - lepton decay the contributions of the intermediate $\rho(770)$ vector meson in the ground and first radially excited state are taken into account. The theoretical prediction for the decay $\tau\rightarrow \rho(770)\eta\nu_{\tau}$ is given. The obtained results for other processes are in satisfactory agreement with the experimental data.

τ → (π0, η, η′, K0)K–ντ decays in the extended Nambu–Jona-Lasinio model

The results of earlier calculations of τ → (π0, η, η′, K0)K–ντ processes in the extended Nambu–Jona-Lasinio model are compared. The full widths of these processes are given. The contributions of intermediate vector and scalar mesons both in the ground state and in the first radially excited one (K*(892), K*(1410), K0*(800), K0*(1430), ρ(770), and ρ(1450)) are taken into account. The results are in reasonable agreement with the experimental data.

Meson production processes in electron–positron collisions and tau-lepton decays within the extended Nambu – Jona-Lasinio model

The extended Nambu–Jona-Lasinio model is briefly described and various ways to apply it are demonstrated. Theoretical approaches to the low-energy meson production processes in colliding electron–positron beams and tau-lepton decays are reviewed. The processes considered occur via intermediate scalar, vector, and axial-vector mesons in the ground state and in the first radially excited state. The model uses the concept of spontaneous chiral symmetry breaking to describe such states. Experimental and theoretical comparisons with other phenomenological strong interaction models are presented.

The production of the f1(1285)γ and a1(1260)γ in colliding e+e−-beams in threshold domain

The processes [Formula: see text] in the threshold domain are considered in the framework of the extended Nambu–Jona-Lasinio model. The channels with the ground [Formula: see text], [Formula: see text] and radially excited [Formula: see text], [Formula: see text] intermediate meson states are taken into account. It is shown that in the process [Formula: see text], the probability of the subprocesses with [Formula: see text]-mesons significantly exceeds the probability of the subprocesses with [Formula: see text]-mesons, whereas, in the process [Formula: see text], [Formula: see text]- and [Formula: see text]-channels give approximately equal contributions. The mechanism of this effect is discussed. The radiative decay widths of [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are calculated.

Finite-volume effects on phase transition in the Polyakov-loop extended Nambu–Jona-Lasinio model with a chiral chemical potential

To investigate the finite-volume effects on the chiral symmetry restoration and the deconfinement transition for a quantum chromodynamics (QCD) system with [Formula: see text] (two quark flavors), we apply the Polyakov-loop extended Nambu–Jona-Lasinio model by introducing a chiral chemical potential [Formula: see text] artificially. The final numerical results indicate that the introduced chiral chemical potential does not change the critical exponents, but shifts the location of critical end point (CEP) significantly; the ratios for the chiral chemical potentials and temperatures at CEP, [Formula: see text] and [Formula: see text], are significantly affected by the system size [Formula: see text]. The behavior is that [Formula: see text] increases slowly with [Formula: see text] when [Formula: see text] is “large” and [Formula: see text] decreases first and then increases with [Formula: see text] when [Formula: see text] is “small.” It is also found that for a fixed [Formula: see text], there is a [Formula: see text], where the critical end point vanishes and the whole phase diagram becomes a crossover when [Formula: see text]. Therefore, we suggest that for the heavy-ion collision experiments, which is to study the possible location of CEP, the finite-volume behavior should be taken into account.

Thermodynamic Hadron-Quark Phase Transition of Chiral Nuclear Matter to Quark-Gluon Plasma

After receiving very interesting results from investigations of chiral nuclear matter based on the extended Nambu-Jona--Lasinio model (ENJL) included the scalar-vector eight-point interaction, a fundamental question of nuclear physics is what happens to chiral nuclear matter as it is compressed or heated. At very high density and temperature, quarks and gluons come into play and a transition is expected to happen from a phase of nuclear matter consisting of confined hadrons and mesons to a state of `liberated' quarks and gluons. In this paper, we investigate the hadron-quark (HQ) phase transition occurs beyond the chiral phase transition in the nuclear matter. The results show that there exits a quarkyonic-like phase, appeared just before deconfinement, when the chiral symmetry is restored but the elementary excitation modes are still nucleonic.

Процессы рождения мезонов в электрон-позитронных столкновениях и распадах тау-лептонов в расширенной модели Намбу—Иона-Лазинио

Процессы рождения мезонов в электрон-позитронных столкновениях и распадах тау-лептонов в расширенной модели Намбу—Иона-Лазинио

The processes e+e−→ K±(K∗∓(892),K∗∓(1410)) and e+e−→ (η,η′(958))(ϕ(1020),ϕ(1680)) in the extended Nambu–Jona-Lasinio model

The processes [Formula: see text] and [Formula: see text] are calculated in the framework of the extended Nambu–Jona-Lasinio model. The intermediate vector mesons [Formula: see text], [Formula: see text], [Formula: see text] and their first radially excited states are taken into account. The obtained results are in satisfactory agreement with the experimental data. The predictions for the cross-sections of the reactions [Formula: see text], [Formula: see text] and [Formula: see text] were made.

The decay τ → K0K−ντ in the extended Nambu–Jona-Lasinio model

The full and differential widths of the decay [Formula: see text] are calculated in the framework of the extended Nambu–Jona-Lasinio model.The contributions of the subprocesses with the intermediate vector mesons [Formula: see text](770) and [Formula: see text](1450) are taken into account. The obtained results are in satisfactory agreement with the experimental data.