International Journal of Modern Physics E

In the nearly 20 years that have elapsed since its discovery, the gauge-gravity correspondence has become established as an efficient tool to explore the physics of a large class of strongly-coupled field theories. A brief overview is given here of its formulation and a few of its applications, emphasizing attempts to emulate aspects of the strong-coupling regime of quantum chromodynamics (QCD). To the extent possible, the presentation is self-contained, and does not presuppose knowledge of string theory.

Beyond the shape phase transition from the spherical vibrator to the deformed rotor regime at $N=90$, the interplay of $\beta$- and $\gamma$-degrees of freedom becomes important, which affects the relative positions of the $K^{\pi }=0^{+}\beta$- and $K^{\pi }=2^{+}\gamma$-bands. In the microscopic approach of the dynamic pairing plus quadrupole model, a correlation of the strength of the quadrupole force and the formation of the $\beta$- and $\gamma$-bands in ${}^{158}$Dy is described. The role of the potential energy surface is illustrated. The $E2$ transition rates in the lower three $K$-bands and the multi-phonon bands with $K^{\pi }=0^{+},2^{+}$ and $4^{+}$ are well reproduced. The absolute $B(E2,2_{\mathrm{\text{i}}}^{+}=0_2^{+})$ $(i=2,3)$ serves as a good measure of the quadrupole strength. The role of the single particle Nilsson orbits is also described.

The nuclear suppression factor $R_{AA}$ and elliptic flow ${\nu }_2$ are calculated by considering the effects of shear viscosity to the entropy density ratio $\eta /s$, using the viscose hydrodynamics at the first- and second-orders of approximation and considering temperature dependent coupling ${\alpha }_s(T)$. It is shown that the second-order viscose hydrodynamics (varying shear viscosity to entropy ratio) with averaged value of $4\pi \eta /s=1.5\pm 0.1$ gives the best results of $R_{AA}$ and ${\nu }_2$ in comparison to the experimental data.

We have measured the differential cross-sections for the elastic and inelastic scattering of $\alpha$-particles on ${}^{13}$C target at the isochronous cyclotron U-150 M INP Republic of Kazakhstan. The beam energies of $\alpha$-particles were 29MeV and 50MeV. As a result of research we obtained new experimental data for the $\alpha$ + ${}^{13}$C elastic scattering and inelastic one leading to the 3.68 ($3/2^{-}$), 6.86 ($5/2^{+}$) and 7.5 ($5/2^{-}$)MeV excited states of ${}^{13}$C nucleus. The experimental results on elastic scattering were analyzed within the framework of the optical model using Woods–Saxon potential and the double folding one. The theoretical calculations for the concerned excited states were performed using the coupled channel (CC) method. The optimal deformation parameters for the excited states of ${}^{13}$C nucleus were extracted.

A systematic study on the alpha decay half-lives of various isotopes of superheavy element (SHE) $Z=121$ within the range $290\le A\le 339$ is presented for the first time using Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated $\alpha$ decay half-lives of the isotopes within our formalism match well with the values computed using Viola–Seaborg systematic, Universal curve of Poenaru et al., and the analytical formula of Royer. In our study by comparing the $\alpha$ decay half-lives with the spontaneous fission half-lives, we have predicted $2\alpha$ chain from ${}^{309,311,312}$121, $3\alpha$ chain from ${}^{310}$121 and $1\alpha$ chain from ${}^{313,314}$121. Clearly our study shows that the isotopes of SHE $Z=121$ within the mass range $309\le A\le 314$ will survive fission and can be synthesized and detected in the laboratory via alpha decay. We hope that our predictions will provide a new guide to future experiments.

The modified BCS (MBCS) and modified Lipkin–Nogami (MLN) models were used to calculate the thermodynamic properties of ${}^{183,184,185}$W nuclei. We also compared the results with the results of BCS model. In the case of heat capacity, modified methods give results which are qualitatively closer to the experimental data compared to the predictions of BCS model.

From the recently established lower-limits on the nonobservability of the neutrinoless double-beta decay of ${}^{76}$Ge (GERDA collaboration) and ${}^{136}$Xe (EXO-200 and KamLAND-Zen collaborations), combined with the ATLAS and CMS data, we extract limits for the left–right (LR) mixing angle, $\zeta$, of the $\mathrm{\text{SU}}{(2)}_L\times \mathrm{\text{SU}}{(2)}_R$ electroweak Hamiltonian. For the theoretical analysis, which is a model dependent, we have adopted a minimal extension of the Standard Model (SM) of Electroweak Interactions belonging to the $\mathrm{\text{SU}}{(2)}_L\times \mathrm{\text{SU}}{(2)}_R$ representation. The nuclear-structure input of the analysis consists of a set of matrix elements and phase-space factors, and the experimental lower-limits for the half-lives. The other input are the ATLAS and CMS cross-section measurements of the $pp$-collisions into two-jets and two-leptons, performed at the large hadron collider (LHC). Our analysis yields the limit $\zeta <10^{-3}$ for $M_R>3\mathrm{\text{TeV}}$, by combining the model-dependent limits extracted from the double-beta-decay measurements and those extracted from the results of the CMS and ATLAS measurements.

The Coulomb barrier heights are calculated by using the proximity potential with a new universal function in comparison with the results of proximity potentials Prox77, AW95, Bass73, BW91, CW76, DP and Ng80. It is found that the new results of Coulomb barrier heights are better than those of most proximity potentials. Then this proximity potential with the new universal function was used to calculate the Coulomb barrier positions and heights from light fusion systems to heavy fusion systems. The parametrized formulas are obtained for Coulomb barrier height and position, and can reproduce most of calculated barrier heights and positions within the accuracy of $\pm 1\%$.

Several typical triaxial models have been parallel addressed and applied to describe the energy values and $B(E2)$ transitional rates in the ground band and the $\gamma$ band for ${}^{192}$Os. It is shown that the different triaxial model presents different triaxial dynamics but each of them can only succeed to explain part of the spectral properties of this nucleus, which indicates that the triaxial shape of ${}^{192}$Os may be more complicated than that reflected by an ideal triaxial model. In addition, the staggering signature in experiments hints that $\gamma$-rigid triaxiality should be more or less involved in ${}^{192}$Os.

The total elastic nucleon–nucleus cross-section is calculated at energies up to 600 MeV for the elements ${}^{12}$C, ${}^{208}$Pb, ${}^{16}$O, ⁹Be, ⁴He, ²H, ${}^{238}$U and ${}^{27}$Al using a finite electromagnetic potential, which is obtained considering a Randall–Sundrum II scenario modified by the inclusion of $p$ compact extra dimensions. The length scale bound is set in the potential to compare with known experimental data.

Kaons and pions are observed by their characteristic decay times of 12, 52 and 26 ns after impact of relatively weak ns-long laser pulses on ultra-dense hydrogen H(0), as reported previously. The signal using an ultra-dense protium p(0) generator with natural hydrogen is now studied. Deflection in a weak magnetic field or penetration through metal foils cannot distinguish between the types of decaying mesons. The signals observed are thus not caused by the decaying mesons themselves, but by the fast particles often at $>50$MeV u${}^{-1}$ formed in their decay. The fast particles are concluded to be mainly muons from their relatively small magnetic deflection and strong penetration. This is further supported by published studies on the direct observation of the beta decay of muons in scintillators and solid converters using the same type of p(0) generator.

In this paper, we have studied the energy spectra and $B(E2)$ values of ${}^{124—130}$Ba isotopes in the shape phase transition region between the spherical and gamma unstable deformed shapes. We have used a transitional interacting Boson model (IBM), Hamiltonian which is based on affine SU(1,1) Lie algebra in the both IBM-1 and 2 versions and also the Catastrophe theory in combination with a coherent state formalism to generate energy surfaces and determine the exact values of control parameters. Our results for control parameters suggest a combination of $U$(5) and SO(6) dynamical symmetries in this isotopic chain. Also, the theoretical predictions can be rather well reproduce the experimental counterparts, when the control parameter is approached to the SO(6) limit.

We determine the energy spectrum and wave function for the Bohr–Mottelson Hamiltonian on $\gamma$-rigid regime separately with the harmonic and Coulomb energy-dependent potentials. We study the effect of potential parameters on the energy levels and probability density distribution. The transition rates are determined in each case.