Narrow Results

In this paper, we examine the radially excited states of B-mesons: $B^{\pm },B^{\pm \ast },B_s^{0\ast },B_s^0,B_c^{\pm \ast }$ and $B_c^{\pm }$-mesons. Our investigation uses the relativistic independent quark model, which relies on a flavor-independent average potential expressed in the scalar and vector square root form. We make phenomenological fit the potential model parameters, $a=0.885$ GeV, $U_0=-1.070$ GeV for calculation of 1S state of B-mesons: $B^{\pm }(5.272\mathrm{\text{GeV}}),B^{\pm \ast }$ (5.329GeV), $B_s^0(5.360\mathrm{\text{GeV}}),B_s^{0\ast }(5.429\mathrm{\text{GeV}}),B_C^{\pm }(6.0593\mathrm{\text{GeV}}),$ $B_C^{\pm \ast }(6.2604\mathrm{\text{GeV}})$, which aligns well with theoretical and experimental data. For higher radially excited states (2S, 3S, 4S, 5S), we adjust $U_0=-1.344$ GeV while keeping “a” fixed, yielding results consistent with other theoretical models. With these parameters, we compute the pseudoscalar and vector meson decay constants, magnetic transition rates, non-leptonic decay widths, branching fractions, rare decay widths, and semileptonic decay widths and branching fractions of the B-mesons. Our findings show reasonable agreement with lattice QCD calculations, experimental results and other theoretical predictions. For instance, our predicted radiative decay width for $B_c^{\ast }$ (1S) $\to$ $B_c$(1S)$\gamma$, sensitive to the $B_c^{\ast }$ and $B_c$, mass difference, can aid in experimentally determining the $B_c^{\ast }$, mass. Predicted non-leptonic branching fractions, such as $B^0\to D^{-}{\rho }^{+}(6.393\times {10}^{-3}),$ $B^0\to D^{-}{k}^{+}(2.148\times {10}^{-4})$ and $B_S^0\to D_S^{-}{k}^{+}(2.188\times {10}^{-4})$, align with PDG values of $(7.6\pm 1.2)\times {10}^{-3},(2.05\pm 0.08)\times {10}^{-4}$ and $(2.25\pm 0.12)\times {10}^{-4}$. Additionally, we calculate the dileptonic decays of $B^0\to {\mu }^{+}{\mu }^{-}(2.245\times {10}^{-10})$ and $B_S^0\to {\mu }^{+}{\mu }^{-}(3.506\times {10}^{-9})$, which agrees with CMS, LHCb and PDG results. Our semileptonic decays of $B^0$ and $B_S^0$ mesons are computed and compared with PDG results. Furthermore, the results obtained for mass difference, $\mathrm{\Delta }M(0.509{\mathrm{\text{ps}}}^{-1}$ and $17.699{\mathrm{\text{ps}}}^{-1})$, mixing parameters, $x_q(0.771$ and $26.82)$, ${\chi }_q$ (0.1866 and 0.4993) of $B^0-{\bar{B}}^0$ and $B_S^0-{\bar{B}}_S^0$ oscillations, shows good agreement with PDG data, validating our model.

To date, superconductivity in fullerides has been almost exclusively tuned by (chemical or physical) pressure control of the conduction bandwidth, W at half filling. This contrasts sharply with the extensive control of the superconducting transition temperature, $T_c$ in atom-based superconductors such as the cuprates and iron pnictides and chalcogenides via changes in valence (bandfilling). Here, we investigate the effect of doping away from the exactly half-filled ${\text{C}}_{60}^{3-}$ level in quaternary face-centered-cubic (fcc) — structured fulleride solids with nominal composition (${\text{Rb}}_{2.5-x}$Cs_x)${\text{Ba}}_{0.5}$${\text{C}}_{60}$ ($0\le x\le 2.5$), in which divalent ${\text{Ba}}^{2+}$ ions partially replace monovalent alkali ${\text{Rb}}^{+}$/${\text{Cs}}^{+}$ ions. The resulting charged-modified fullerides in which the $t_{1u}$ bandwidth is also varied with changing x show a dome-shaped dependence of $T_c$ on interfullerene separation in analogy with their half-filled antecedents. However, following electron injection beyond half-filling, the superconductivity dome is found to shift towards shorter interfullerene separations, i.e. towards increased conduction bandwidths.

${\text{Ni}}_{1-x}$Ti_xMnSb polycrystalline alloys in the range $0\le x\le 0.20$ were synthesized employing the standard solid-phase synthesis method. The crystal, magnetic, as well as electrical properties of the alloys were investigated using neutron powder diffraction and magneto-resistance measurements. The results reveal that the substitution of Ti for Ni within the temperature range of 2.5–300 K does not induce alterations in the crystal and magnetic structures of NiMnSb. The ordered Ni magnetic moment approaches zero. The study of the electrical transport properties of the ${\text{Ni}}_{1-x}$Ti_xMnSb alloys, where $0\le x\le 0.20$, has demonstrated a half-metallic state at low temperatures and metallic conductivity for temperatures exceeding 160 K. A semiconductor state manifests at titanium concentrations of x = 0.2 and was observed at temperatures below 21 K. The obtained experimental results are elucidated through first-principles theoretical calculations.