Semileptonic decays of Λc+ in dynamical approaches

Nucleon and pion electromagnetic form factors in a light-front constituent quark model

Radiative πϱ and πω transition form factors in a light-front constituent quark model

Properties of \r{ho}-meson in symmetric nuclear matter are investigated within a light-front constituent quark model (LFCQM), using the in-medium input calculated by the quark-meson coupling (QMC) model. The LFCQM used here was previously applied in vacuum to calculate the \r{ho}-meson electromagnetic properties, namely, charge G 0 , magnetic G 1 , and quadrupole G 2 form factors, as well as the electromagnetic radius and decay constant. We predict the in-medium modifications of the \r{ho}-meson electromagnetic form factors in symmetric nuclear matter.

The pion electromagnetic form factor is calculated with a light-front quark model. The "plus" and "minus" component of the electromagnetic current are used to calculate the electromagnetic form factor in the Breit frame with two models for the q\bar{q} vertex. The light front constituent quark models describes very well hadronic wave function for pseudo-scalar and vector particles. Symmetry problems arinsing in the light-front approach are solved by the pole dislocation method. The results are compared with new experimental data and with other quark models.

Weak decay form factors of heavy pseudoscalar mesons within a light-front constituent quark model

In this study, the T-even sub-leading twist transverse momentum dependent distributions (TMDs) of proton in the light-front quark-diquark model (LFQDM) have been investigated. We have derived the overlap form of the light-front wave functions (LFWFs) for the sub-leading twist proton TMDs by detangling the un-integrated quark-quark correlator for the semi-inclusive deep inelastic scattering (SIDIS). We have obtained the explicit expressions of TMDs for both the cases of the diquark being a scalar or a vector and analyzed their relationships with leading twist TMDs within the same model. Average transverse momenta and average square transverse momenta for the TMDs have been tabulated and compared with the results from the light-front bag model and the light-front constituent quark model (LFCQM). In addition to this, we have also compared our results for the PDF e(x) with the recent CLAS collaboration results.Transverse momentum dependent parton distributions of proton; T-even sub-leading twist TMDs; light-front quark-diquark model.

The $\rho$ meson gravitational form factors are studied based on a light-front constituent quark model which has been successfully employed to calculate its generalized parton distributions and some low-energy observables. The distributions of energy, spin, pressures, and shear forces inside the $\rho$ meson are explicitly given.

We use ideal fluid energy conditions to constrain the free parameter of the degree of nonconservation $\ensuremath{\zeta}$ of the energy-momentum tensor in Rastall gravity theory. We study the mass-radius relation of strange stars and the corresponding stability using the obtained range of $\ensuremath{\zeta}$ constrained by energy conditions. In our calculations, we use the MIT bag model with a color-flavor-locked state to describe strange quark matter. We obtain a finite, narrow range of $0\ensuremath{\le}\ensuremath{\zeta}\ensuremath{\le}0.5$. In addition to $\ensuremath{\zeta}$, the corresponding nonconservation of the energy-momentum tensor depends on the gradient of the energy-momentum scalar. The behavior of matter in the MIT bag model is one example in which the energy-momentum tensor is conserved through the zero value on the gradient of the energy-momentum scalar. We also find that the corresponding mass-radius relation of strange stars depends on the interplay of matter parameters, such as ${m}_{s}$, $B$, $\mathrm{\ensuremath{\Delta}}$, and the Rastall parameter $\ensuremath{\zeta}$. In addition, we find that as $\ensuremath{\zeta}$ increases, the maximum strange star mass decreases. Furthermore, the stability of strange stars with regard to radial oscillations in Rastall gravity theory is rather different from that in general relativity because of the impact of the nonconservation of the energy-momentum tensor. The stability boundary mass and radius determined from the zero modes of radial perturbation oscillations are not the same as the maximum mass and corresponding radius. This is because the Rastall nonconservation term increases the matter pressure to support the strange star against collapse, especially when ${v}_{s}^{2}>1/3$. The reverse applies when ${v}_{s}^{2}<1/3$.

The possibility of compact stars as hideouts for color-spin-locked (CSL) quark matter (QM) is investigated in both the MIT bag model and the Nambu-Jona-Lasinio (NJL) model. Within the framework of the NJL model, the idea of absolutely stable quark matter and the existence of the conventional pure quark star (QS) are not supported; in addition, there appears to be no stable hybrid configuration above 2M⊙ as the hideout for CSL QM. The stable configurations of massive strange quark stars could be reproduced in the MIT bag model with QCD corrections being taken into account; moreover, they could act as the hiding place for the CSL QM. An interesting scenario is proposed that the phase transition to the CSL phase could occur in the cooling process. The CSL quark matter is an electromagnetic (EM) superconductor of type I, and a complete Meissner effect is expected. However, the analysis for this sizable superconductor indicates that most of the magnetic field is frozen inside the quark core with a critical strength, while in some special cases a small fraction could be expelled from a thin layer near the surface in a short time. The analysis on energetics and timescale suggests that this process could act as an inducement mechanism to power typical fast radio bursts, but as a single source of energy, it is unlikely to generate other EM emissions such as gamma-ray bursts and giant flares. Published by the American Physical Society 2025

Neutron star due to their high interior matter density are expected to be composed of a quark core, a mixed quark-hadron matter, and a layer of hadronic matter. Thus, in this paper, we compute the equation of state of these parts of neutron star to evaluate its structure properties. We use two models for describing EOS of quark matter, NJL and MIT bag models, and employ three approaches in this work. A density dependent bag constant satisfy the quark confinement in the simple MIT bag model. We also study the interaction behavior of quarks, firstly one gluon exchange within MIT bag model and the secondly dynamical mass will be held as effective interaction that roles between particles. Density dependence of quark mass is obtained from NJL self consistent model. NJL model is a effective manner for justify the chiral symmetry. Applying the Gibbs conditions the equation of state of the quarks and hadrons mixed phase is obtained. Since the hadronic matter is under the influence of strong force of nucleons, we calculate the equation of state of this phase using a powerful variational many-body technique. Finally, we calculate the mass and radius of a cold neutron star with a quark core by numerically solving the TOV equation. To check our used EOS, we compare our results with the recent observational data. Our results are in a good agreement with some observed compact objects such as $SAXJ1748.9-2021$, $4U1608-52$ and $Vela X-1$.

Spin-dependent structure functions ${g}_{1}^{p}(x)$ and ${g}_{2}^{p}(x)$ of the proton are calculated in the MIT bag model and in the color-dielectric model using the method of Signal and co-workers. Decomposition of ${g}_{2}$ into the twist-two and -three parts, according to Jaffe, has also been done. While characteristics of the quark wave functions in these models are clearly seen in the $x$ dependence of ${g}_{1}^{p}(x)$, the transverse part ${g}_{2}^{p}(x)$ is rather insensitive to the models. By selecting out the twist-three part of ${g}_{2}^{p}(x)$, however, the model dependence becomes evident. The color-dielectric model predicts quark distributions which are closer to the nonrelativistic quark model when compared with the MIT bag model.

We study the hadron-quark phase transition in the interior of neutron stars (NS). For the hadronic sector, we use a microscopic equation of state (EOS) involving nucleons and hyperons derived within the Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and three-body forces. For the description of quark matter, we employ both the MIT bag model with a density dependent bag constant, and the color dielectric model. We calculate the structure of NS interiors with the EOS comprising both phases, and we find that the NS maximum masses are never larger than 1.7 solar masses, no matter the model chosen for describing the pure quark phase.

The purpose of this paper is to introduce and study Poincaré-Steklov (PS) operators associated to the Dirac operator D m with the so-called MIT bag boundary condition. In a domain ⊂ ‫ޒ‬ 3 , for a complex number z and for U z a solution of (D m − z)U z = 0, the associated PS operator maps the value of − U zthe MIT bag boundary value of U z -to + U z , where ± are projections along the boundary ∂ and In the first part of this paper, we show that the PS operator is a zeroth-order pseudodifferential operator and give its principal symbol. In the second part, we study the PS operator when the mass m is large, we prove that it fits into the framework of 1/m-pseudodifferential operators, and we derive some important properties, especially its semiclassical principal symbol. Subsequently, we apply these results to establish a Krein-type resolvent formula for the Dirac operator H M = D m + Mβ1 ‫ޒ‬ 3 \ for large masses M > 0 in terms of the resolvent of the MIT bag operator on . With its help, the large coupling convergence with a convergence rate of O(M −1 ) is shown. 1. Introduction 2923 2. Preliminaries 2927 3. Basic properties of the MIT bag model 2933 4. Poincaré-Steklov operators as pseudodifferential operators 2939 5. Approximation of the Poincaré-Steklov operators for large masses 2945 6. Resolvent convergence to the MIT bag model 2955 Appendix: Dirac algebra and applications 2966 Acknowledgements 2968 References 2968

The belief t ha t quarks are confined has been theoret ical ly exploi ted in a number of different ways. The basic support for the assumption rests on the expectat ion tha t some day i t might be confirmed as a basic result of quantum chromodynamics. By taking confinement for granted, however, various confining models have been util ized to explore possible consequences on the propert ies of hadrons and to deduce the salient features of the model which the rigorous theory of confinement should retain. Among these a t t empts some developed thei r approach via suitable enrichment of the nonrelat ivist ic quark model by means of the int roduct ion of quark-confining potent ia ls , such tha t the appropr ia te hadronic propert ies may be checked in the l ight of the assumed confinement (1,2). Other t rea tments are based on the relat ivis t ic equations for the quark fields with, ei ther the imposi t ion of such boundary conditions which provide confinement (e.g. MIT bag model (3)), or an insert ion in the Dirac equation of appropr ia te potent ials (Coulomb, l inearor harmonic-osci l lator potent ia l (4-s)). I t is worth noting here tha t , while the bag model requires a different bag radius for each hadron under consideration, the relat ivis t ic quark-confining models operate with only a few parameters characterizing the potent ia l which acts on all quark fiavours indiscriminately. In this way the confining potent ia l models are more economic but, on the other hand, may present too r igid l imitat ions. The bag model and the confining potent ia l models, however, share a common feature of admit t ing explici t determinat ion of the quark wave functions which, in turn, permits

We investigate the procedure which one uses to calculate the nucleon form factors, for both the electromagnetic and axial-vector currents, from bag models. We first point out that these form factors, as functions of ${q}^{2}$ alone, can in general be expressed in terms of several matrix elements, all of which are defined in the Breit frame. We then evaluate these Breit-frame matrix elements by assuming both (1) that the current operators can be approximated by the one-body quark contribution, and (2) that the nucleon wave functions at rest can be approximated by those given in the MIT bag model. Typical numerical results, as augmented by pionic corrections, provide a reasonable description of the experimental data.