Modern Physics Letters A

When hadron-quark continuity is formulated in terms of a topology change at a density higher than twice the nuclear matter density $(n_0)$, the core of massive compact stars can be described in terms of quasiparticles of fractional baryon charges, behaving neither like pure baryons nor like deconfined quarks. Hidden symmetries, both local gauge and pseudo-conformal (or broken scale), emerge and give rise both to the long-standing “effective $g_A^{\ast }\approx 1$” in nuclear Gamow–Teller (GT) transitions at $\lesssim n_0$ and to the pseudo-conformal sound velocity $v_{\mathrm{\text{pcs}}}^2/c^2\approx 1/3$ at $\gtrsim 3n_0$. It is suggested that what has been referred to, since a long time, as “quenched $g_A$” in light nuclei reflects what leads to the dilaton-limit $g_A^{\mathrm{\text{DL}}}=1$ at near the (putative) infrared fixed point of scale invariance. These properties are confronted with the recent observations in GT transitions and in astrophysical observations.

The flavor mixing of the quarks is described by the CKM matrix, which is parametrized by three mixing angles and one phase parameter. We discuss a new texture for the two mass matrices of the six quarks. The three flavor mixing angles can be calculated — they are functions of the ratios of the quark masses. The third mixing angle is given by the CKM matrix element $\left|V_{cb}\right|$. We find: $\left|V_{cb}\right|\simeq 2(m_s/m_b)$. The calculated mixing angles agree with the mixing angles, measured in many experiments.

The neutrino oscillation probabilities at the long-baseline accelerator neutrino experiments are expected to be modified by matter effects. We search for evidence of such modification in the data of T2K and NO$\nu$A, by fitting the data to the hypothesis of (a) matter modified oscillations and (b) vacuum oscillations. We find that vacuum oscillations provide as good a fit to the data as matter modified oscillations. Even extended runs of T2K and NO$\nu$A, with five years in neutrino mode $(5\nu )$ and five years in anti-neutrino mode $(5\bar{\nu })$, cannot make a $3\sigma$ distinction between vacuum and matter modified oscillations. The future experiment DUNE, with neutrino and anti-neutrino runs of five years each $(5\nu +5\bar{\nu })$, can rule out vacuum oscillations by itself at $5\sigma$ if the hierarchy is normal. If the hierarchy is inverted, a $5\sigma$ discrimination against vacuum oscillations requires the combination of $(5\nu +5\bar{\nu })$ runs of T2K, NO$\nu$A and DUNE.

In this paper, we analyze some properties regarding singular spinors and how they are connected. The method employed here consists of mapping the spinorial structure and also the adjoint structure. Such a mathematical device is useful to determine propagators without invoking the vacuum expected value of the quantum field time-ordered product.

The binary system AR Scorpii hosts an M-type main sequence cool star orbiting around a magnetic white dwarf in the Milky Way Galaxy. The broadband non-thermal emission over radio, optical and X-ray wavebands observed from AR Scorpii indicates strong modulations on the spin frequency of the white dwarf as well as the spin-orbit beat frequency of the system. Therefore, AR Scorpii is also referred to as a white dwarf pulsar wherein a fast spinning white dwarf star plays very crucial role in the broadband non-thermal emission. Several interpretations for the observed features of AR Scorpii appear in the literature without firm conclusions. In this paper, we investigate connection between some of the important physical properties like spin-down power, surface magnetic field, equation of state, temperature and gravity associated with the white dwarf in the binary system AR Scorpii and its observational characteristics. We explore the plausible effects of white dwarf surface magnetic field on the absence of substantial accretion in this binary system and also discuss the gravitational wave emission due to magnetic deformation mechanism.

Making use of the generalized form of the Ghost dark energy density, which has the functional form ${\rho }_G=f(H,H^2)$ where $H$ represents the Hubble expanding rate, the present accelerated enlargement behavior of the cosmos is investigated from the Rastall theory perspective. After finding a relation for the Hubble cosmic expansion rate, we consider recent cosmology-independent measurements calculated for the expansion history of the cosmos to fit the model via the ${\chi }^2$-analysis. Moreover, we discuss the cosmographic properties of the model with the help of some cosmological quantities. We show that our model is stable and consistent with the recent astrophysical data. Also, for our model, we investigate cosmological interpretations of thermodynamics.

For the first time, we choose non-flat vacuum mode for background spacetime based on the minimum number of created particles during early non-de Sitter inflation. In conventional methods for calculating the number of created particles, the flat background is selected automatically and causes a negative number problem for created particles during asymptotic-de Sitter inflation. In a covariant approach to curved spacetime, both real and background spacetimes should be selected, curved and consequently the relation for particle creation should be modify. As an interesting finding from this research, flat space does not include minimum number of particles and there are some asymptotic de Sitter spacetimes with fewer number. Therefore, in the generalized formula for particle creation, we choose a non-flat background containing the minimum number of created particles.

We study some aspects of dynamical compactification scenario where stabilization of extra dimensions occurs due to the presence of Gauss–Bonnet term and nonzero spatial curvature. In the framework of the model under consideration, there exists two-stages scenario of evolution of a Universe: in the first stage, the space evolves from a totally anisotropic state to the state with three-dimensional (corresponding to our “real” world) expanding and $D$-dimensional contracting isotropic subspaces; on the second stage, constant curvature of extra dimensions begins to play role and provide compactification of extra dimensions. It is already known that such a scenario is realizable when constant curvature of extra dimensions is negative. Here we show that a range of coupling constants for which exponential solutions with three-dimensional expanding and $D$-dimensional contracting isotropic subspaces are stable is located in a zone where compactification solutions with positively curved extra space are unstable, so that two-stage scenario analogous to the one described above is not realizable. Also we study “nearly-Friedmann” regime for the case of arbitrary constant curvature of extra dimensions and describe new parametrization of the general solution for the model under consideration which provide elegant way of describing areas of existence over parameters space.

In this investigation report, we present a perfect charged fluid solution for a static and spherically symmetric spacetime; for its construction, we suppose a metric potential, $g_{tt}$, and a specific form of the electric field’s intensity, $E$, in such a manner that the resulting stellar model is physically acceptable and stable. The model presented depends on two parameters $(w,\alpha )$ related to the compactness and the magnitude of the electric field and these same parameters will generate different possibilities for the behavior of the speed of sound. For the particular case in which $\alpha =0$, we obtain once more a chargeless model constructed previously, the compactness for the charged model case is greater than in the chargeless case. As an effect of the charge, the model admits two regions for the parameter $\alpha$, in one of these the speed of sound is a monotonic decreasing function and in the other it is a monotonic increasing function. By means of a numerical analysis, it is shown that the orders of magnitude associated to the pressure and density are characteristic of the compact stars. In particular for $w=0.3691670568$, the range of $\alpha \in [55.57286,674.5349]$, which implies that the radius of an object with mass $1M_{\odot }$ is found between 6554.620 m and 7672.702 m with a maximum central density of ${\rho }_b=4.354076\times 10^{18}{\mathrm{\text{kg/m}}}^3$.