abstract

A phenomenological optical potential is used to study the elastic angular distributions for the \(^{19}\mathrm {F}+{^{208}}\)Pb system close to the Coulomb barrier. This potential is constructed by taking into account the flexible potential developed by Ginocchio. The fluctuations in the real and imaginary parts of the optical model potential follow the trends of the threshold anomaly. The set of optical potential parameters needed to analyze the fusion cross sections of the same system are obtained through analysis of the scattering cross sections. Theoretical fusion cross sections and results from four different experimental groups well agree for a range of energies. Several fluorine (F) isotopes are used as projectiles in this study of fusion cross sections by slightly altering the radial parameter. It was found that the fusion process occurs unfettered in the \(^{19}\mathrm {F} +{^{208}}\)Pb system below the Coulomb barrier but is seriously hindered in the case of its isotopic projectiles.

abstract

This study is an attempt to investigate the applicability of the non-extensive statistics involving the effects of magnetic fields on the thermodynamics of quantum chromodynamics (QCD). The non-extensive statistics are controlled by the entropic index, \(q \neq 1\). In the case of \(q = 1\), the Boltzmann–Gibbs statistics (extensive) are recovered. The thermodynamics such as pressure, entropy, and magnetization are determined for zero and non-zero magnetic fields. Therefore, the magnetic field is divided into strong, \(eB = 0.2\), 0.3 GeV\(^{2}\), and weak \(eB = 0.002\), 0.003, 0.005 GeV\(^{2}\) magnetic fields. The magnetic field effect is caused by adding a vacuum contribution to the free energy alongside the thermal contribution. The theoretical results are confronted with the lattice results which show overestimation especially at high temperatures and with higher entropic index \(q\). It is concluded that QCD matter is considered to be a para-magnetic matter. Nevertheless, the non-extensive statistics might not be a favorable tool for describing the strongly coupled media responses to the external magnetic fields.

abstract

A new picture of “one-resonance–one-symmetry” has been proposed recently to reveal nature of the reparametrization symmetry in neutrino oscillation in matter and where it resides: Symmetry of \(i \leftrightarrow j\) state-exchange-type exists at around a resonance, with \(i\) and \(j\) being the states which participate in the level crossing. Consistently, the 1–2 and 1–3 state-exchange symmetries are identified at around the solar and atmospheric resonances, respectively, in the locally-valid frameworks. On the other hand, the Denton et al. (DMP) perturbation theory, a globally-valid framework, has the 1–2 exchange symmetry which is akin to the one in the aforementioned solar-resonance perturbation (SRP) theory. In our picture, the symmetry must be associated with the resonance, not the framework, and if so, these two 1–2 symmetries must be identical to each other. We conduct a comparative study of the 1–2 symmetries possessed by SRP and DMP to confirm their identity. An almost identity is verified, but in a highly nontrivial way.

abstract

In this work, cross-section calculations of bound-free pair production (BFPP) are done for the mechanism in Pb–\(p\) collisions at the LHC. The BFPP cross section for the asymmetric collisions of Pb–\(p\) at the center-of-mass energies of \(\sqrt {s_{NN}}=5.02\) TeV and \(\sqrt {s_{NN}}=8.16\) TeV is computed. In order to reach the exact results, Monte Carlo integration techniques are utilized to calculate the lowest-order Feynman diagrams amplitudes via the lowest-order perturbation theory. Moreover, in this work, our cross-section results for the BFPP mechanism in Pb–\(p\) collisions at the LHC are compared with BFPP cross-section results obtained in the literature, which are reached for Pb–\(p\) collisions by using a simple scaling applied to scale the BFPP cross-section results in Pb–Pb collisions at the LHC.