Modern Physics Letters A

Using the method of QCD sum rules, we estimate the energy of lowest energy top quark meson state with a hybrid admixture. This new estimate uses the previous estimates of hybrid charmonium and upsilon states, but with the mass of the top quark mass being much greater than the charm and bottom quark masses. We discuss production of mixed hybrid top quark mesons and possible detection of the creation of the quark–gluon plasma via relativistic heavy ion collisions.

We simulate proton–proton collisions to calculate the energy flow with four different classes of events: hard scattering, diffractive and non-diffractive enriched interactions and inclusive minimum bias. We use cosmic ray Monte Carlo event generator to determine the energy flow for the above-mentioned classes in pseudorapidity range 1.9$<\eta <$ 4.9 at $\sqrt{s}$ = 7 TeV in pp collisions. A comparison of model predictions to the LHCb data, obtained with the same pseudorapidity and center-of-mass energy, is presented and discussed. While predictions of the models are compatible with the experimental measurements, none of them is able to completely reproduce all the results.

The holographic principle provides a deep insight into quantum gravity and resolves the fine-tuning crisis concerning the cosmological constant. Holographic dark energy introduces new ultraviolet (UV) and infrared (IR) cutoffs into quantum gravity which are necessarily strongly related. The equation of state for dark energy $\omega =p/\rho$ is discussed from the holographic point of view. The phantom option of $\omega <-1$ is resurrected, as in an earlier cyclic cosmology. Such a cyclic model can, however, equally use the cosmological constant with $\omega =-1$.

One perceives same response of a single-atom detector when placed at a point outside the horizon in Schwarzschild spacetime to that of a static single-atom detector in thermal Minkowski spacetime. So one cannot distinguish Schwarzschild spacetime from thermal Minkowski spacetime by using a single-atom detector. We show that, for Schwarzschild spacetime, beyond a characteristic length scale which is proportional to the inverse of the surface gravity $\kappa$, the Resonance Casimir–Polder interaction (RCPI) between two entangled atoms is characterized by a 1/L² power-law provided the atoms are located close to the horizon. However, the RCPI between two entangled atoms follows a 1/L power-law decay for the thermal Minkowski spacetime. Seemingly, it appears that the spacetimes can be distinguished from each other using the RCPI behavior. But our further exploration leads to the conclusion that the length scale limit beyond a characteristic value is not compatible with the local flatness of the spacetime.

We develop a technique relating scalar fields with different masses in different conformally flat spacetimes. We apply this technique to the case of FRW spacetimes, with $k=\pm 1,0$, and discuss several examples. We also study various energy conditions and discuss how they constrain the spacetimes related by this technique. We calculate the two-point scalar correlator in the radiation-dominated universe with a hyperbolic spatial section from the one in the Milne universe using the above mapping. Finally, we consider trace anomaly and renormalized stress tensor for conformally flat spacetimes, especially Milne and radiation-dominated universe (with $k=-1$) using the transformation.

This paper studies the dynamics of thin-shell for (2 + 1)-dimensional rotating and charged rotating Bañados–Teitelboim–Zanelli black holes by using Israel thin-shell formalism. We consider the matter distribution located at thin-shell associated with a scalar field and analyze its effects on the dynamics of thin-shell through equations of motion and effective potential. The corresponding dynamical equations are numerically studied for both massless as well as massive scalar fields. For rotating case, the rate of expansion and collapse increases with massless scalar shell but decreases for massive case. For charged rotating, the rate of expansion and collapse decreases by increasing angular momentum for both massless as well as massive case. We conclude that the rate of expansion and collapse of the rotating case is greater than charged rotating black hole.

We discuss the existence of compact stars in the context of $f(R)=R+\alpha R^2+\beta R^{2}ln(\beta R)$ gravity model, where additional logarithmic corrections are assumed. Here, $R$ is the Ricci scalar and $\alpha$, $\beta$ are constant values. Further, the compact stars are considered to be anisotropic in nature, due to the spherical symmetry and high density. For this purpose, we derive the Einstein field equations by considering Krori–Barua spacetime. For our proposed model, the physical acceptability is verified by employing several physical tests like the energy conditions, Herrera cracking concept and stability condition. In addition to this, we also discuss some important properties such as mass–radius relation, surface redshift and the speed of sound are analyzed. Our results are compared with observational stellar mass data, namely, 4U 1820-30, Cen X-3, EXO 1785-248 and LMC X-4. The graphical representation of obtained solutions provide strong evidences for more realistic and viable stellar model.

In this paper, a controlled quantum dialogue (CQD) scheme based on different unspecific two-particle entangled state is proposed, in which legitimate users can exchange their secret messages according to unitary operations they chose and measurement results published by Charlie, realizing transmitting unspecific secrets by using unspecific entangled state. We insert decoy particles twice and get rid of useless secret messages carried by F particles to ensure security of the whole communication system, realizing the three-times channel detection. Compared to previous CQD protocols, the proposed scheme is proved to stand attack from third-party controller, and it is very secure.

Some observable consequences that follow from a fiber bundle description of a tight binding condensed matter system on a lattice are described. The geometrical picture can be extended to describe non-periodic lattice structures, where a single Brillouin zone is predicted.