Modern Physics Letters A

A few years ago the use of standard functional manipulations was demonstrated to imply an unexpected property satisfied by the fermionic Green’s functions of QCD: effective locality. This feature of QCD is non-perturbative as it results from a full integration of the gluonic degrees of freedom. In this paper, previous derivations of effective locality are reviewed, corrected, and enhanced. Focusing on the way non-Abelian gauge-invariance is realized in the non-perturbative regime of QCD, the deeper meaning of effective locality is discussed.

In this work, we address the reheating issue in the context of F(R) gravity, for theories that the inflationary era does not obey the slow-roll condition but the constant-roll condition is assumed. As it is known, the reheating era takes place after the end of the inflationary era, so we investigate the implications of a constant-roll inflation era on the reheating era. We quantify our considerations by calculating the reheating temperature for the constant-roll R² model and we compare to the standard reheating temperature in the context of F(R) gravity. As we demonstrate, the new reheating temperature may differ from the standard one, and in addition, we show how the reheating era may restrict the constant-roll era by constraining the constant-roll parameter. However, due to the observational constraints on the constant-roll parameter, no large deviations from the slow-roll picture occur.

We consider a model of dark quantum electrodynamics (QEDs) which is coupled to a visible photon through a kinetic mixing term. We compute the $g_{\chi }-2$ for the dark fermion, where $g_{\chi }$ is its gyromagnetic factor. We show that the $g_{\chi }-2$ of the dark fermion is related to the $g_{\chi }^{\prime }-2$ of (visible) QEDs through a constant which depends on the kinetic mixing factor. We determine $g_{\chi }-2$ as a function of the mass ratio $\kappa =m_B/m_{\chi }$, where $m_B$ and $m_{\chi }$ denote the masses of the dark photon and the dark fermion, respectively, and we show how $g_{\chi }-2$ becomes very different for light and heavy fermions around $m_B\le 10^{-4}$ eV.

In this paper, we have investigated the Thomas–Fermi model for the electron gas in Rindler space. We have observed that if the uniform acceleration is along $+x$-direction, then there is $y-z$-symmetry in space. For the sake of mathematical simplicity, we have therefore assumed a two-dimensional spatial structure $(x-y)$ in Rindler space. It has been shown that in two-dimensional spatial coordinates, the electrons are distributed discontinuously but in a periodic manner in a number of rectangular strip-like domains along $\pm y$-direction. Some of them are having void structure, with no electrons inside such rectangular strips, while some are filled up with electrons. We call the latter type domain as the normal zone. We have also given physical interpretation for such exotic type electron distribution in Rindler space.

In this study, the validity of the generalized second law of thermodynamics (GSLT) has been investigated in F(R, G) gravity. We consider that the boundary of the universe is surrounded by an apparent horizon in the spatially flat Friedmann–Robertson–Walker (FRW) universe, and we take into account the Hawking temperature on the horizons. The unified solutions of the field equations corresponding to gravity theory have been applied to the validity of the GSLT frame, and in this way, both the solutions have been verified and all the expansion history of the universe has been shown in a unified picture.

The cross-sections of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{h}_c$ and $e^{+}{e}^{-}\to {\pi }^{+}{D}^0{D}^{\ast -}+\mathrm{\text{c.c.}}$ have been measured by BESIII experiment. A new resonance $Y(4390)$ is observed in the two decay modes. A combined fit is performed to the two cross-sections. $Y(4390)$’s parameters are determined to be $M_{Y(4390)}=(4392.6\pm 4.2\pm 1.0)\mathrm{\text{MeV}}/c^2$, ${\mathrm{\Gamma }}_{Y(4390)}=(154.2\pm 9.3\pm 2.4)\mathrm{\text{MeV}}$, where the first uncertainties are statistical and the second systematic. The ratio $\frac{{ℬ}(Y(4390)\to {\pi }^{+}{D}^0{D}^{\ast -}+\mathrm{\text{c.c.}})}{{ℬ}(Y(4390)\to {\pi }^{+}{\pi }^{-}{h}_c)}$ is also obtained and it indicates that $Y(4390)$’s main decay modes maybe $\pi D{D}^{\ast }$. We determine the lower limit of its leptonic decay width of around 150 eV, which can be compared with the theoretical expectations of different models. These information may help in understanding the nature of this state.

Recent LHCb measurements of the $J/\psi$ meson production in jets are analyzed using fragmentation jet function formalism. It is shown that disagreement with theoretical predictions for distribution over the fraction of $J/\psi$ transverse momentum $z(J/\psi )$ in the cases of prompt production can be explained if one takes into account evolution of the fragmentation function and contributions from double parton scattering (DPS) mechanism or gluon fragmentation.