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Journal of Physics G: Nuclear and Particle Physics - latest papers
Latest articles for Journal of Physics G: Nuclear and Particle Physics
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Modified electron trajectory due to the axion dark matter background
It is well known that the coupling of an axion-like particle with a photon modifies the Maxwell equations. One of the main consequences of these modifications is the conversion of axions into photons. Little has been said about other possible effects. In this paper we show that the trajectory of an electron can be significantly altered because of the emergence of an electric field due to the dark matter background of the axion-like particles in this modified axion-electrodynamics. Different dark matter densities and magnetic field strengths are considered and it is shown that an axion-like particle with a mass ma ∼ 10−22 eV generates an electric field that can significantly change the trajectory of an electron in these scenarios.
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Response functions and giant monopole resonances for light to medium-mass nuclei from the ab initio symmetry-adapted no-core–shell model
Using the ab initio symmetry-adapted no-core–shell model, we compute sum rules and response functions for light to medium-mass nuclei, starting from interactions that are derived in the chiral effective field theory. Specifically, we investigate electromagnetic transitions of monopole, dipole and quadrupole nature for 4He, and explore dominant features of giant monopole resonances in symmetric nuclei such as the closed-shell 4He and 16O light nuclei, the intermediate-mass open-shell 20Ne and the medium-mass closed-shell 40Ca. Furthermore, for the NNLOopt chiral potential, we determine parameter-free monopole sum rules, which can provide information on the incompressibility of symmetric nuclear matter. We report 213(10) MeV as an estimate for the compression modulus for infinite nuclear matter, which overlaps with the lower range of values often used in current astrophysical applications.
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The QCD phase diagram and the baryon number fluctuations in NJL model with a temperature damping coupling strength
We investigate the chiral phase diagram in the NJL model with a modified coupling strength. Moreover, we delve deeply into the fluctuations of baryon numbers. A temperature damping factor for the coupling strength is introduced to mimic the temperature dependence of quantum chromodynamics (QCD) in the low and middle temperature ranges. This novel parameter is fitted by using the quark condensate from lattice QCD at finite temperature. Our approach provides a significant enhancement to the chiral phase diagram, accurately reproducing the pseudocritical temperature at μB = 0 and aligning the crossover boundary with lattice QCD results. The quark condensate is used to ascertain the location of the phase transition, and we find an area where both phases coexist. The chiral susceptibility is employed to identify the pseudo-critical line in the crossover region. The skewness ratios and the kurtosis ratios varying with T at several different μB are calculated meticulously, and the results demonstrate that they experience a significant change around the pseudo-critical line. Additionally, the skewness ratios and the kurtosis ratios along the pseudo-critical line (Tc(μB)) and the lines deviating from Tc(μB) are computed to gain a better understanding of the experimental results. This implies that the freeze-out line is relatively far from the critical end point.
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ρ-, π-meson form-factor in the point form of Poincaré-invariant quantum mechanics
Form-factor analysis of pseudoscalar and vector mesons with zero transmitted momentum has been carried out in the model based on the point form of Poincaré-invariant quantum mechanics. The original method of model parameters’ calculations from leptonic decays , using pseudoscalar density constant is proposed. The method is generalized in radiative decays and with the following anomalous magnetic moments calculation of constituent and quarks. It has been shown that the obtained parameters lead to the values of magnetic and quadrupole moment of meson which are comparable with other models as well as hadronic transition observables. A comparative analysis of the obtained values of and quark magnetic moments has been carried out. It has been found that the proposed model gives numerical evaluations which are comparable to other approaches and models.
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Hadron production in ultra-relativistic nuclear collisions and finite baryon-size effects
We investigate the relative yields of various like and unlike mass hadrons in ultra-relativistic heavy-ion collisions (URHIC). In the framework of thermal model, a strong evidence of strangeness imbalance is observed in the experiments at lower collision energies relative to non-strange particles, particularly pions. The study indicates that like mass particle ratios in the system at the chemical freeze-out in URHIC can be described effectively by considering baryons (antibaryons) as point like as well as finite size particles which imitates hard-core repulsive interactions leading to an excluded volume type effect. In this analysis, we employ the statistical hadron resonance gas model for both cases. A comparison between the two cases is provided. However, the importance of considering baryons (antibaryons) as finite size particles is revealed in the description of baryon to meson ratios. Best fits to particle ratios are obtained using χ2-minimization procedure. For the case of finite-size baryons (antibaryons), we find that considering their hard-core radii allows us to fit the available antibaryon-to-baryon and baryon (antibaryon)-to-pion ratio experimental data simultaneously quite well with the same model parameter values. Moreover, our results align well with the proton radius puzzle observed in the muonic hydrogen measurement data. Furthermore, the study reveals two distinct chemical freeze-out stages in both cases, where the earlier one corresponds to baryonic (hyperonic) and antibaryonic (antihyperonic) states and a later one to mesonic degrees of freedom. A comparison of freeze-out lines obtained from both the cases is made along with the results of some earlier studies.