International Journal of Modern Physics E

In this paper, we studied thermal evolution of isolated neutron stars (NSs) including the pion condensation core, with an emphasis on the stiffness of equation of state (EOS). Many temperature observations can be explained by the minimal cooling scenario which excludes the fast neutrino cooling process. However, several NSs are cold enough to require it. The most crucial problem for NS cooling theory is whether the nucleon direct Urca (DU) process is open. The DU process is forbidden if the nucleon symmetry energy is significantly low. Hence, another fast cooling process is required in such an EOS. As the candidate to solve this problem, we consider the pion condensation. We show that the low-symmetry energy model can account for most cooling observations including cold NSs, with strong neutron superfluidity. Simultaneously, it holds the $2M_{\odot }$ observations even if the pion condensation core exists. Thus, we propose the possibility of pion condensation, as an exotic state to solve the problem in low-symmetry energy EOSs. We examined the consistency of our EOSs with other various observations as well.

We study the production of heavy-flavor decay muons (HFM) in proton–proton ($p$–$p$) and heavy-ion ($A$–$A$) collisions using Angantyr model in PYTHIA8 at Large Hadron Collider (LHC) energies. These studies have been performed for three colliding systems: small ($p$–$p$), intermediate (Xe–Xe) and large (Pb–Pb). The works have been performed in $p$–$p$ (with $\sqrt{s}$ = 2.76, 5.02, 7.0 and 13TeV), Xe–Xe (with ${\sqrt{s}}_{\mathrm{\text{NN}}}$=5.44TeV) and Pb–Pb (with ${\sqrt{s}}_{NN}$=2.76 and 5.02TeV) collision systems. The production of heavy-flavor (charm and bottom quarks) decay muons in $p$–$p$ and $A$–$A$ collisions is measured in the forward rapidity $2.5<y<4$. The standard statistical uncertainty is computed for each case as ${\sqrt{N}}_{\mathrm{\text{yield}}}$. In the study of $p_T$-distribution of HFM at forward rapidity ($2.5<y<4$) using Angantyr model, we find that simulation results agree with ALICE data reasonably well for $p$–$p$ and $A$–$A$ collisions. The comparison of simulation results with ALICE data for $y$-distribution at $\sqrt{s}=5.02$ and 7.0TeV in $p$–$p$ collision has also been illustrated. In addition to the particle spectra, a more quantitative model-to-data comparison can be obtained through the observable $R_{AA}$. We, thus, calculate $R_{AA}$ of HFM in this work for ${\sqrt{s}}_{NN}=2.76$ and 5.02TeV. The simulated $R_{AA}$ results overestimate the ALICE data. $R_{AA}$ estimation as a function of $p_T$ shows almost constant values and close to unity at lower energy (${\sqrt{s}}_{NN}$=2.76TeV), but substantially lower than unity at comparatively higher energy (${\sqrt{s}}_{NN}$=5.02TeV). We also predict for the HFM $p_T$ spectrum and $y$-distribution in O–O collision at ${\sqrt{s}}_{NN}$=6.37TeV for 0–10$\%$ collision centrality. These simulated spectra are illustrated for ALICE Run3 experiment and they comply with other HFM ALICE measurements.

This paper reports on ⁴He elastic scattering by ${}^{6,7}$Li, ⁹Be and ${}^{11}$B angular distributions analyzed in the optical model (OM) context using Woods–Saxon (WS) potential form and double folding (DF) with distorted-wave Born approximation (DWBA), while applying the M3Y approach to the real part and a WS shape to describe the imaginary part of the optical model potential (OMP). Cluster folding (CF) with the DWBA model has also been explored for theoretical data analysis. The coupled reaction channels (CRC) method has been applied to all nuclear systems under consideration where both inelastic scattering and the transfer with elastic scattering have been involved in the analysis of experimental data. The study highlights the overall agreement between the data under the study and the concerned theoretical approaches.

In this paper, odd-mass isotopic chain of ${}^{123-129}$Sn has been studied within the framework of nucleon-pair shell model (NPSM) with the noncollective pair originating from the alignment of two neutrons in the $\nu$h11/2 orbit included. It was found that NPSM can reproduce the properties of the yrast bands satisfactorily, it is crucial to include the noncollective pair in the NPSM. The band structure can be explained as the backbending or the phase transition from vibrational limit to the rotational limit. The mechanism of the yrast band can be explained as band crossing between the ground state band and the S band constructed from the neutron alignment in the $\nu$h11/2 orbit. Our results also suggest that the mechanism of the band structure of those four Sn isotopes can also be interpreted as the competition and transition between collective and noncollective phase.

In this paper, we have studied all possible ${}^{48}\mathrm{\text{Ca}}$ and ${}^{58}\mathrm{\text{Fe}}$-induced fusion reactions for the synthesis of superheavy nuclei $104\le Z\le 125$. The semi-empirical formula for fusion barriers of ${}^{48}\mathrm{\text{Ca}}$ and ${}^{58}\mathrm{\text{Fe}}$ is constructed. Fusion and evaporation residue cross-sections are studied using advance statistical model (ASM). The fusion and evaporation residue cross-sections of this work are compared with that of experiments. We have also predicted suitable targets and production cross-sections for the synthesis of superheavy elements using the ${}^{48}\mathrm{\text{Ca}}$ and ${}^{58}\mathrm{\text{Fe}}$-induced fusion reactions. The ${}^{58}\mathrm{\text{Fe}}$-induced fusion reactions can be used to synthesize superheavy elements $Z=120,122$ and 124 using the targets ${}^{245}$Cm, ${}^{249}$Bk and ${}^{249}$Cf have half-lives greater than one year and produce the cross-sections in terms of pb.

The conventional quark mass is not continuous at thresholds. In this paper, we derive matching-invariant quark masses which are continuous everywhere. They are generally expanded as an obvious function of the logarithmic $\mathrm{\Lambda }$ scaled energy. The expansion coefficients are related to the gamma and beta functions, with concretization to four-loop level. Due to the maximal elimination of their direct dependence on the coupling with large uncertainties, the new expressions for quark masses converge much fast and accurate.

The developed fission systematics depicts the projectile energy and the target mass dependence of fission cross-sections of heavy nuclei. The developed model is fitted using experimental fission cross-section data of 500–1665 MeV negative pion induced fission in ${}^{119}$Sn, ${}^{197}$Au and ${}^{209}$Bi. The same systematics is further fitted using the cascade exciton model (CEM) calculations of the above-mentioned fission reactions. Parameterization of the model is performed by calculating its parameters and uncertainties in them. A comparison of the systematics predictions with experimental data and CEM calculations is made. Validation of the systematics using new target nuclei ${}^{152}$Eu, ${}^{181}$Ta, ${}^{198}$Hg and ${}^{210}$At (not included in the systematics development) over an extended range of pion energies, from 80 MeV to 2500 MeV, builds trust in it. The systematics is not valid for ${}^{232}$Th and ${}^{238}$U. The systematics is found to be valid for target nuclei from ${}^{119}$Sn to ${}^{210}$At and for incident negative pion energies from 80 MeV to 2500 MeV. Results are discussed in detail. Merits and demerits of the developed systematics have been concisely described. Valid conclusions and future perspectives are also given.

We study the change in internal rotational energy in the transformation of protons to neutrons in the $\beta$-decay reactions that take place in the collapse of the iron core of massive stars that precede Type II supernova explosions. We consider an ensemble of electrons, protons, neutrons and neutrinos undergoing $\beta$-decay reactions, treat the protons and neutrons as triatomic rotors, evaluate the equilibrium constant to obtain the change in rotational energy during the proton-to-neutron transformation. We estimate such change for a variety of conditions, and compare with the energy released in a supernova explosion.

The reduced electric quadrupole transition rates have been calculated for states of the negative parity band in the ${}^{99}$Pd nucleus using semiclassical particle-rotor model calculations. The calculated transition rates are found to decrease with increasing spin states. The dynamic moment of inertia ${\Im }^{(2)}$ of the states above I = $23/2\hslash$ are found to be large. The spin ($\hslash$) versus frequency ($\hslash \omega$) plot obtained from the semiclassical model for the configuration $\pi {(g_{9/2})}^{-4}$ ⊗$\nu [h_{11/2}{(g_{7/2})}^2]$ is found to agree with the experimental data, which suggests a possible anti magnetic rotational character in the negative parity band.