abstract

The low mass of \(D^*_{s0}(2317)\) presents problems for the conventional quark model, leading to consideration of other options regarding a multi-quark system. Here, we investigate the scalar open-charm state \(D^*_{s0}(2317)\) and its bottom partner by the Thermal QCD Sum Rules (TQCDSR) method using the two-point correlation function with contributions of the nonperturbative condensates up to dimension six. Our calculations indicate that the variations in mass and decay constant values are stable through temperatures up to \(T\cong 100~\mathrm {MeV}\) and fall after this point. At the critical temperature, the values of mass and decay constant change up to \(94\%, 71\% \) of their values in vacuum in the molecular scenario, and \( 94\%, 75\% \) in the diquark–antidiquark scenario. Besides, we find more dramatic changes in mass and decay constant above \( T_\mathrm {c} \), and hence we interpret it as the hadrons starting to disappear. Also, the detailed search for hot medium effects on the hadronic parameters of open-charm meson \(D^*_{s0}(2317)\) and the bottom partner may have implications for the QCD phase diagram derived from heavy-ion collision experiments. Finally, these results may help distinguish conventional quark model mesons from exotic states.

abstract

The differential rate of the decay of the Higgs boson (\(h\)) to a pair of \(\tau \) leptons with their subsequent decay in the \(\tau ^-\to \pi ^- \nu _\tau \) and \(\tau ^+\to \pi ^+{\bar \nu }_\tau \) channels is studied. The Yukawa interaction between the Higgs boson and the \(\tau \) leptons is assumed to include scalar (S) and pseudoscalar (PS) couplings. Angular distributions of the pions in the \(h\to \tau ^- \tau ^+\to \pi ^-\nu _{\tau }\,\pi ^+{\bar \nu }_\tau \) decay are considered. For real values of the S and PS couplings, this decay is known to be a source of information on \(\mathcal {CP}\) violation in the \(h \tau \tau \) interaction. In the present paper, the main attention is paid to a possible non-Hermiticity of this interaction. Influence of non-Hermiticity on the distribution of the angle between planes of the \( \tau ^- \to \pi ^-\nu _{\tau }\) and \(\tau ^+ \to \pi ^+ {\bar \nu }_{\tau }\) decays, and distribution of the polar angle of one of the pions are analyzed. Asymmetries sensitive to parameters of \(\mathcal {CP}\) violation and non-Hermiticity of \(h \tau \tau \) interaction are proposed.

abstract

We report on the results of the computation of the order of \((k_{\mathrm {F}}a_0)^2\) correction, where \(k_{\mathrm {F}}=3\pi ^2\rho \) is the Fermi wave vector and \(a_0\) the \(s\)-wave scattering length of the repulsive interaction, to the ground-state energy of a mixture of oppositely polarized \(N_a\) spin-\(1/2\) fermions \(a\) of masses \(m_a\) and \(N_b\) spin-\(1/2\) fermions \(b\) of masses \(m_b\) (\(\rho =N/V\), \(N=N_a+N_b\)). It is shown that the results of the paper in which the same correction has been computed entirely numerically, using a more traditional approach, can be easily and semianalytically reproduced using the effective field theory technique.

abstract

In recent years, the artificial neural network (ANN) has been successfully applied in nuclear physics and some other areas of physics. This study begins with the calculations of \(\alpha \)-decay half-lives for some neutron-deficient nuclei using the Coulomb and proximity potential model (CPPM), temperature-dependent Coulomb and proximity potential model (CPPMT), Royer empirical formula, new Ren B (NRB) formula, and a trained artificial neural network model (\(T^{\mathrm {ANN}}\)). By comparison with experimental values, the ANN model is found to give very good descriptions of the half-lives of the neutron-deficient nuclei. Moreover, CPPMT is found to perform better than CPPM, indicating the importance of employing the temperature-dependent nuclear potential. Furthermore, to predict the \(\alpha \)-decay half-lives of unmeasured neutron-deficient nuclei, another ANN algorithm is trained to predict the \(Q_{\alpha }\) values. The results of the \(Q_{\alpha }\) predictions are compared with the Weizsäcker–Skyrme-4+RBF (WS4+RBF) formula. The half-lives of unmeasured neutron-deficient nuclei are then predicted using CPPM, CPPMT, Royer, NRB, and \(T^{\mathrm {ANN}}\), with \(Q_{\alpha }\) values predicted by ANN as inputs. This study concludes that half-lives of \(\alpha \)-decay from neutron-deficient nuclei can successfully be predicted using ANN, and this can contribute to the determination of nuclei at the driplines.

abstract

A direct algebraic solution has been obtained from the full bosonic master-field equation of the IIB matrix model for low dimensionality \(D=3\) and small matrix size \(N=3\). A different method is needed for larger values of \(D\) and \(N\). Here, we explore an indirect numerical approach and obtain an approximate numerical solution for the nontrivial case \((D,\,N)=(10,\,4)\) with a complex Pfaffian. We also present a suggestion for numerical calculations at larger values of \(N\).