Modern Physics Letters A

In this paper, we perform a comparative analysis between the future proposed long-baseline experiments ESSnuSB and T2HK in measuring the leptonic CP phase ${\delta }_{\mathrm{\text{CP}}}$. In particular, we study the effect of the neutrino mass ordering degeneracy and the leptonic mixing angle ${𝜃}_{23}$ octant degeneracy in the measurement of leptonic CP violation and precision for both experiments. Since the ESSnuSB (T2HK) experiment probes the second (first) oscillation maximum to study neutrino oscillations, the effect of these degeneracies are significantly different in both experiments. Our main conclusion is that for the ESSnuSB experiment, the information on the neutrino mass ordering does not play a major role in the determination of ${\delta }_{\mathrm{\text{CP}}}$, which is not the case for the T2HK experiment. However, the information on the true octant compromises the CP sensitivity of the ESSnuSB experiment as compared to T2HK if ${𝜃}_{23}$ lies in the lower octant. These conclusions are true for both the 540 km and 360 km baseline options for the ESSnuSB experiment. In addition, we investigate the effect of different running times in neutrino and antineutrino modes and the effect of ${𝜃}_{23}$ precision in measuring ${\delta }_{\mathrm{\text{CP}}}$.

In this paper, we have studied the spectra of strange particles in pp collision at $\sqrt{s}$ = 0.9 TeV by using different simulation models, EPOS-1.99, SIBYLL-2.3c, QGSJETII-04 and EPOS-LHC. The transverse momentum and rapidity distribution in the $p_T$ range of $0<p_T<10$ GeV/c and $0<p_T<2$ GeV/c, respectively, are investigated for the strange particles, $K_s^o$, $\mathrm{\Lambda }$, ${\mathrm{\Xi }}^{-}$. Similarly, a comparative study is done for the ratio of $\mathrm{\Lambda }/K_s^o$ and ${\mathrm{\Xi }}^{-}/\mathrm{\Lambda }$ as a function of transverse momentum and rapidity. The validity of simulation models is tested by comparing simulation results to the CMS experimental data at $\sqrt{s}$ = 0.9 TeV. For $p_T$ distributions, the EPOS-LHC model in the $p_T$ range $p_T<0.3$ GeV/c, $p_T>8$ GeV/c and in $3.6<p_T<3.8$ GeV/c while EPOS-1.99 model in the $p_T$ range $2.5<p_T<2.8$ GeV/c and QGSJETII-04 model in the $p_T$ range $2.5<p_T<2.8$ GeV/c as well as, $3.6<p_T<3.8$ GeV/c explain the experimental data well. For the, $\mathrm{\Lambda }/K_s^o$ and ${\mathrm{\Xi }}^{-}/\mathrm{\Lambda }$ versus transverse momentum distributions, EPOS-LHC model in the $p_T$ range of, $2.4<p_T<2.6$ GeV/c and $1.6<p_T<1.8$ GeV/c, EPOS-1.99 model in the $p_T$ range, $1.7<p_T<2.2$ GeV/c, SIBYLL-2.3c model in the $p_T$ range, $1.4<p_T<1.6$ GeV/c and QGSJETII-04 model in the $p_T$ range $0.4<p_T<0.6$ GeV/c explain the experimental data very well. Similarly, for $\mathrm{\Lambda }/K_s^o$ and ${\mathrm{\Xi }}^{-}/\mathrm{\Lambda }$ versus rapidity distribution QGSJETII-04 predictions in the rapidity region, $0.4<\left|y\right|<0.6$, $1.4<\left|y\right|<1.6$, and $\left|y\right|>1.8$, while EPOS-LHC model in the region, $\left|y\right|>1.8$, very well explained the experimental data. Although good comparison of the models predictions with the experimental data is observed, none of them completely describe the experimental data the spectra of strange particles over the entire $p_T$ and $y$ range.

We discuss the recently suggested Ricci–Gauss–Bonnet holographic dark energy in Chern–Simons modified gravity. We have tested some general forms of the scale factor $a(t)$, and used two physically reasonable forms which have been proved to be consistent with observations. Both solutions predict a sign flipping in the evolution of cosmic pressure which is positive during the early-time deceleration and negative during the late-time acceleration. This sign flipping in the evolution of cosmic pressure helps in explaining the cosmic deceleration–acceleration transition, and it has appeared in other cosmological models in different contexts. However, this work shows a pressure singularity which needs to be explained. The evolution of the equation of state parameter $\omega (t)$ shows the same asymptotic behavior for both solutions indicating a quintessence-dominated universe in the far future. We also note that $\omega (t)$ goes to negative values (leaving the decelerating dust-dominated era at $\omega =0$) at exactly the same time the pressure becomes negative. Again, there is another singularity in the behavior of $\omega (t)$ which happens at the same cosmic time of the pressure singularity.

In this paper, we explore the effect of gravity on the flow of proper time near static spherically symmetric black hole possessing an electric charge. We use the Reissner–Nordström metric. In the first case, the traveling twin travels away from the black hole and in the second it travels toward it. We then compare it with the case of relativistic kinematics where the static twin ages faster than the traveling twin.

In this paper, we consider a non-static cylindrically symmetric self-gravitating system with anisotropic matter configuration and investigate its stability regions by using a homogenous model. We establish perturbed form of dynamical equations by using Eulerian and Lagrangian approaches. The conservation of baryon number is applied to obtain adiabatic index as well as perturbed pressure. A variational principle is used to find characteristic frequency which helps to compute the instability criteria. It is found that dynamical instability can be prevented till the radius of a cylinder exceeds the limit R$>$18. We conclude that the system becomes unstable against radial oscillations as the radial pressure increases relative to tangential pressure.

In this work, we construct a new kind of rainbow functions, which has generalized uncertainty principle parameter. Then, we investigate modified thermodynamic quantities and phase transition of rainbow Schwarzschild black hole by employing this new kind of rainbow functions. Our results demonstrate that the rainbow gravity and generalized uncertainty principle have a great effect on the picture of Hawking radiation. They prevent black holes from total evaporation and cause a remnant. In addition, after analyzing the modified local thermodynamic quantities, we find that the effect of rainbow gravity and the generalized uncertainty principle lead to one first-order phase transition, two second-order phase transitions and two Hawking–Page-type phase transitions in the thermodynamic system of rainbow Schwarzschild black hole.

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein’s cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a homogeneous isotropic background in classical general relativity. The solution procedure is adopted in a model-independent way (or the cosmological parametrization). A simple parametrization of the Hubble parameter (H) as a function of cosmic time t is considered which yields an exponential type of evolution of the scale factor (a) and also shows a negative value of deceleration parameter at the present time with a signature flip from early deceleration to late acceleration. Cosmological dynamics of the model obtained have been discussed illustratively for different phases of the evolution of the universe. The evolution of different cosmological parameters is shown graphically for flat and closed cases of Friedmann–Lemaitre–Robertson–Walker (FLRW) spacetime for the presented model (open case is incompatible to the present scenario). We have also constrained our model parameters with the updated (36 points) observational Hubble dataset.

We consider the ${𝒫}{𝒯}$-symmetric quantum field theory on the noncommutative spacetime with angular twist and construct its pseudo-Hermitian interpretation. We explore the differences between internal and spatial parities in the context of the angular twist and for the latter we find new ${𝒫}{𝒯}$-symmetric interactions that are nontrivial only for the noncommutative spacetime. We reproduce the same formula for the leading order T-matrix of the equivalent Hermitian model as the one obtained earlier for the quantum field theory on the commutative spacetime. This formula implies that the leading order scattering amplitude preserves the symmetries of the noncommutative geometry if they are not broken in the non-Hermitian formulation.

It is known that static and spherically symmetric black hole solutions of general relativity in different spacetimes can be embedded into higher-dimensional flat spacetime. Given this result, we have explored the thermodynamic nature of black holes á la its embedding into flat spacetime. In particular, we have explicitly demonstrated that black hole temperature can indeed be determined starting from the embedding and hence mapping of the static observers in black hole spacetime to Rindler observers in flat spacetime. Furthermore, by considering the dynamics of a scalar field in the flat spacetime, it is indeed possible to arrive at the area scaling law for black hole entropy. Thus, by using the flat spacetime field theory, one can indeed provide a thermodynamic description of black holes. Implications are also discussed.

In this paper, the spin-one Duffin–Kemmer–Petiau equation in (1 + 3) dimensions with a modified Kratzer potential is considered in the non-commutative space framework. The energy eigenvalue equation and the corresponding eigenfunctions are derived analytically. Furthermore, the energy shift due to the space non-commutativity effect is also obtained using the perturbation theory. In particular, it is shown that the degeneracy of the initial spectral line is broken, where the space non-commutativity plays the role of a magnetic field. This behavior is very similar to the Zeeman effect.

The Klein–Gordon equation with equal scalar and vector potentials $s(\widehat{r})=v(\widehat{r})=V(\widehat{r})/2$ describing the dynamics of a three-dimensional under the modified Coulomb plus inverse-square potential is considered, in the symmetries of noncommutative quantum mechanics (NCQM), using Bopp’s shift method. The new energy of $n$th excited state $E_{nc-n}(a,b,n,j,l,m)$ is obtained as a function of the shift energy $\mathrm{\Delta }{E}_{is}(n,j,l,s,m)$ and $E_n$ is obtained via first-order perturbation theory in the three-dimensional noncommutative real space (NC: 3D-RS) symmetries instead of solving modified Klein–Gordon equation (MKGE) with the Weyl–Moyal star product. It is found that the perturbative solutions of discrete spectrum depended by the Gamma function, the discreet atomic quantum numbers $(j,l,s,m)$ and the potential parameters (A and B), in addition to noncommutativity parameters ($𝜃$ and $\sigma$), which are induced with the effect of (space–space) noncommutativity properties.