Modern Physics Letters A

After playing a pivotal role in the birth of the Standard Model in the 70s, the study of charm physics has undergone a revival during the last decade, triggered by a wealth of precision measurements from the charm and B factories, and from the CDF and especially the LHCb experiments. In this paper, we sum up how the unique phenomenology of charmed hadrons can be used to test the Standard Model and we review the latest measurements performed in this field by the LHCb experiment. These include the historic first observations of CP violation and of a nonzero mass difference between the charmed neutral-meson mass eigenstates, the most precise determination of their decay-width difference to date, and a search for time-dependent CP violation reaching the unprecedented precision of $10^{-4}$. These results challenge our comprehension of nonperturbative strong interactions, and their interpretation calls for further studies on both the theoretical and experimental sides. The upcoming upgrades of the LHCb experiment will play a leading role in this quest.

Recently, the LHCb collaboration put the upper limit on the ${\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}^{-}\gamma$ decay branching ratio $\mathrm{\text{Br}}({\mathrm{\Xi }}_b^{-}\to {\mathrm{\Xi }}^{-}\gamma )<1.3\times 10^{-4}$. The measured value is below the light-cone sum rule prediction. In this paper, the rare radiative decay of the ${\mathrm{\Xi }}_b^{-}$ baryon is studied in the framework of the relativistic quark model based on the quasipotential approach and QCD. The decay form factors are calculated with the comprehensive account of the relativistic effects. The obtained result for the branching ratio is found to be below the upper limit set by LHCb and is consistent with theoretical predictions based on the SU(3) flavor-symmetry, light-front quark model and light-cone QCD sum rules in full theory within theoretical uncertainties.

In this paper, we investigate the optical properties by a charged rotating braneworld black hole, in the Randall–Sundrum scenario. We study the horizon, the photon region, the shadow of the black hole and other observables. The results show that in addition to the black hole spin parameter $a$, the other two parameters, tidal charge $\beta$ and electric charge $q$, are found to affect the horizon, the photon region and the black hole shadow. We also have researched different observables and found that with the increase of the three parameters, the area and perimeter of the black hole shadow decrease, while the deformation of the shadow intensifies. Finally, through the observations of the oblateness $D$, the circularity deviation $\mathrm{\Delta }C$ and the angular diameter ${𝜃}_d$ and the latest M87${}^{\ast }$ and SgrA${}^{\ast }$ black hole shadows, the three parameters are analyzed to turn out that those observations give different constraints due to the three parameters.

In this paper, we study the shadow of a 4D Einstein–Gauss–Bonnet black hole as photons couple to the Weyl tensor and find that the propagation of light depends on its polarization which leads to the existence of a double shadow. Then, we discuss the effect of the coupling parameter $\lambda$, the polarization of light and the Gauss–Bonnet coupling constant $\alpha$ on the shadow. Further, we explore the influence of the Gauss–Bonnet coupling constant $\alpha$ on the quasinormal modes (QNMs) of massless scalar field and investigate the connection between the real part of QNMs in the eikonal limit and the shadow radius of black holes. We find that in the eikonal limit, the real part of QNMs is inversely proportional to the shadow radius under the case of the photons uncoupled to the Weyl tensor.

We study the holographic dark energy (HDE) with adiabatic matter creation process to explain the present-day accelerated expansion of the Universe. The field equations are discussed and solved analytically for various cosmological parameters such as the Hubble parameter, deceleration parameter and effective equation of state parameter in terms of redshift by considering a more general form of the matter creation rate. The viability of such model is checked using the recent data of Type Ia supernovae Pantheon sample, Hubble function $H(z)$ data, joined data of baryon acoustic oscillations/cosmic microwave background and latest local $H_0$ by SH0ES. We achieve the most fitting values of model parameters by performing the statistical analysis of our model with the three different combination of data sets. The HDE model, with IR cutoff as Hubble horizon, in the absence of matter creation does not show phase transition. While the induction of matter creation to the same model shows the recent transition from a decelerating to an accelerated phase. Our outcomes show that the model with matter creation is compatible with the data sets used. We find that the HDE model with matter creation provides the Hubble function which matches sufficiently well with the observed Hubble data. Finally, we perform geometrical and cosmographic analyses to explicate our model and compare it with the other dark energy models like $\mathrm{\Lambda }$CDM model. It is found that the evolution of model starts from Chaplygin gas region in early times, enters into quintessence region in medieval time and finally approaches to $\mathrm{\Lambda }$CDM model.

We apply the quasi-local stress–energy tensor formalism to the Casimir effect of a scalar field confined between conducting planes located in a static spacetime. We show that the surface energy vanishes for both Neumann and Dirichlet boundary conditions and consequently the volume Casimir energy reduces to the famous zero point energy of the quantum field, i.e. $E^{\mathrm{\text{vol}}}=\sum \frac{\hslash \omega }{2}$. This enables us to reinforce previous results in the literature and extend the calculations to the case of massive and arbitrarily coupled scalar field. We found that there exists a first-order perturbation correction to the Casimir energy contrary to previous claims which state that it vanishes. This shows many orders of magnitude greater than previous estimations for the energy corrections and makes it detectable by near future experiments.

The swampland conjectures from string theory have had some really interesting implications on cosmology, in particular on inflationary models. Some models of inflation have been shown to be incompatible with these criteria while some have been shown to be severely fine-tuned, with most of these problems arising in single field inflationary models in a General relativistic cosmology. Recent works have although optimistically shown that single field models in more general cosmologies can be consistent with these conjectures and hence there is an optimism that not all such models lie in the swampland. However, a paradigm of inflation which has been shown to not be perfectly okay with the conjectures is eternal inflation. So in this work, we discuss tachyonic inflation in the high-energy RS-II Braneworld scenario in the context of the swampland conjectures while also considering the possibility of swampland consistent eternal inflation. We show that our concerned regime evades all the prominent swampland issues for single field inflation being virtually unscathed. After this, we show that the main conflicts of eternal inflation with the swampland can easily be resolved in the considered tachyonic scenario and in particular, we also discuss the exciting prospect of a Generalized Uncertainty Principle facilitating the notion of Swampland consistent eternal inflation. Our work as a whole reignites the possibility that there can be a swampland (and possibly, quantum gravitationally) consistent picture of a “Multiverse”.

We study the temporal evolution of quantum coherence and parameter estimation for two-mode coherent-state superposition by using the master equation. Analytic expressions are provided and numerically displayed, which can illustrate the reliance of the coherence and Fisher information during the dynamics. Generally, we find that the amount of the quantum measures has the same behavior during the time variation, and displays a different order that depends on the different strength regimes of the input radiation fields and then disappears at infinite times. We show that these measures start from maximal value at the initial instant and decrease the time goes on. Moreover, we can observe that these measures can be protected resisted from the environment effect during the dynamics, showing an important feature of coherence and Fisher information. The obtained results can be assumed more practical in the characterization of the behavior of the coherence and Fisher information under the effect of the environment. Our observations can provide significant implications in harnessing these phenomena in quantum optics and information.

A tripartite operation sharing scheme is put forward by employing a five-qubit entangled state [proposed by Brown et al., J. Phys. A 38, 1119 (2005)] as quantum channel. Its sharer asymmetry and its success determinacy are both identified. Moreover, its security is ensured via analyses. In terms of current techniques, its experimental feasibility is discussed and thus confirmed. Furthermore, its comparison with Ye et al.’s scheme [Chin. Phys. Lett. 30, 020301 (2013)] utilizing the same quantum channel is made and shows its distinct advantage of degrading the intensity and difficulty of necessary operations.