Modern Physics Letters A

Cosmic-ray antiprotons are a powerful tool for astroparticle physics. While the bulk of measured antiprotons is consistent with a secondary origin, the precise data of the AMS-02 experiment provides us with encouraging prospects to search for a subdominant primary component, e.g. from dark matter. In this brief review, we discuss recent limits on heavy dark matter as well as a tentative signal from annihilation of dark matter with a mass $\lesssim$100 GeV. We emphasize the special role of systematic errors that can affect the signal. In particular, we discuss recent progress in the modeling of secondary production cross-sections and correlated errors in the AMS-02 data, the dominant ones originating from uncertainties in the cross-sections for cosmic-ray absorption in the detector.

Studies of the mathematical properties of Regge-pole and dual amplitudes are important both for their applications in high energy phenomenology and in their generalizations to strings, superstrings, branes, and other theoretical developments. In this paper, we investigate the similarities and differences between two classes of dual amplitudes: one with Mandelstam analyticity (DAMA) and another one with logarithmic trajectories (Dual-log). By using quantum (q-) deformations, new features of Dual-log amplitude are unveiled, in particular those concerning its asymptotic behavior and the spectrum of resonances. The two classes of dual amplitudes are compared in various kinematic regions: at fixed transferred momenta asymptotic, fixed angle asymptotic, and in the resonance region.

In this study, Einstein’s field equations are derived based on two dissimilar frameworks: the first is based on the concepts of “fractional velocity” and “fractal action” motivated by Calcagni’s approach to fractional spacetime while the second is derived based on fractal calculus which is a generalization of ordinary calculus that include fractal sets and curves. The fractional theory displays a breakdown of Lorentz invariance. It was observed that a spatially dependent cosmological constant emerges in the fractional theory. A connection between the fractional order parameter and the dimensionless parameter $\gamma$ arising in the parameterized post-Newtonian (PPN) formalism is observed. A confrontation with very long-baseline radio interferometry targeting quasars 3C273 and 3C279 is done which proves that the fractional order parameter is within the range $0.99980<\alpha <1.00004$. Moreover, emergence of quantum Hawking radiation is realized in the theory supporting Hawking’s best calculations that black holes are not black. Nevertheless, based on the fractal calculus approach, there is a conservation of the Lorentz invariance and absence of spatially-dependent cosmological constant. The theory depends on the fractal order $0<\beta <1$ and gives rise to a fractal Schwarzschild radius of the massive body greater than the conventional radius besides a fractal Hawking’s temperature less than the standard one. However, the confrontation with radio interferometry targeting quasars 3C273 and 3C279 gives $0.999997444\beta <1.0000128$.

In this paper, we use corrected $f(R)$ gravitational model which is a polynomial function with a logarithmic term. We employ the slow-roll conditions and obtain the number of cosmological parameters. This helps us to verify the swampland conjectures which guarantees validation of low energy quantum field theory. The obtained results show that the corresponding model is consistent with the swampland conjectures. Also, the upper and lower limits of the parameter $n$ are, respectively, 0.15 and 0.0033. Finally, by using scalar spectrum index $n_s$ and tensor-to-scalar ratio $r$ relations and comparing with the Planck 2018 data, we obtain the coefficients $\alpha$, $\beta$ and $\gamma$. Also, the corresponding results are constructed by several figures, literature and also Planck 2018 data.

A class of solutions of Einstein field equations satisfying Karmarkar embedding condition is presented which could describe static, spherical fluid configurations, and could serve as models for compact stars. The fluid under consideration has unequal principal stresses i.e. fluid is locally anisotropic. A certain physically motivated geometry of metric potential has been chosen and codependency of the metric potentials outlines the formation of the model. The exterior spacetime is assumed as described by the exterior Schwarzschild solution. The smooth matching of the interior to the exterior Schwarzschild spacetime metric across the boundary and the condition that radial pressure is zero across the boundary lead us to determine the model parameters. Physical requirements and stability analysis of the model demanded for a physically realistic star are satisfied. The developed model has been investigated graphically by exploring data from some of the known compact objects. The mass-radius (M-R) relationship that shows the maximum mass admissible for observed pulsars for a given surface density has also been investigated. Moreover, the physical profile of the moment of inertia (I) thus obtained from the solutions is confirmed by the Bejger–Haensel concept.

In this paper, we study the thermodynamics properties of noncommutative NC (3 + 1)-dimensional in the spherically symmetric AdS black holes. The solution of equations of motion in AdS spacetime using a general distribution mass is studied. The results show that there exist AdS₄ black holes only for the non-Gaussian distributions, while for the Gaussian distributions, Nariai numbers do not exist in case of small values of cosmological constant $\mathrm{\Lambda }$ while Nariai numbers exist and tend to zero for large values of $\mathrm{\Lambda }$. Moreover, we show that there is an effect of $\mathrm{\Lambda }$ on the Hawking temperature of black hole and this effect disappears when the Hawking temperature tends to zero. Finally, it turns out that the behavior of free energy does not change with the change of $\mathrm{\Lambda }$, but its value increases with increasing $\mathrm{\Lambda }$.

The paper deals with the static spherically symmetric wormhole solutions in $f(R)$-modified gravity theory with anisotropic matter field and for some particular choices for the shape functions. This work may be considered as an extension of the general formalism in [S. Halder, S. Bhattacharya and S. Chakraborty, Phys. Lett. B 791, 270 (2019)] for finding wormhole solutions. For isotropic matter distribution it has been shown that wormhole solutions are possible for zero tidal force and it modifies the claim in [M. Cataldo, L. Leimpi and P. Rodriguez, Phys. Lett. B 757, 130 (2016)]. Finally, energy conditions are examined and it is found that all energy conditions are satisfied in a particular domain with a particular choice of the shape function.

The supersymmetric WKB (SWKB) condition is supposed to be exact for all known exactly solvable quantum mechanical systems with the shape invariance. Recently, it was claimed that the SWKB condition was not exact for the extended radial oscillator, whose eigenfunctions consisted of the exceptional orthogonal polynomial, even the system possesses the shape invariance. In this paper, we examine the SWKB condition for the two novel classes of exactly solvable systems: one has the multi-indexed Laguerre and Jacobi polynomials as the main parts of the eigenfunctions, and the other has the Krein–Adler Hermite, Laguerre and Jacobi polynomials. For all of them, one can always remove the $\hslash$-dependency from the condition, and it is satisfied with a certain degree of accuracy.

Recently, Zang et al. constructed a three-uniform state of eight qubits. In this work, we show that such an eight-qubit entangled state can be used to realize the deterministic quantum teleportation of an arbitrary four-qubit state based on the orthogonal basis measurement.