International Journal of Theoretical Physics最新文献

Since the SM Higgs boson, h, is the superposition of two unequal-mass neutral Higgs bosons in 2HDM, therefore the associated production cross section for h and Z in SM and 2HDM can be different. In this paper, the possibility of using this difference to discover or constrain 2HDM is studied. As a main result, the allowed parameter space of 2HDM type-II is found in the light of possible precise measurements from the LHC experiments. It is shown that combination of the constraints from these measurements with the previous constraints on 2HDM, from direct search and flavour physics, can rule out the main part of the 2HDM parameter space.

We investigated the quantum speed limit (QSL) time of a spin qubit coupled to an XXZ Heisenberg spin chain environment. The spins of the environment are coupled to the system qubit through Heisenberg like interaction. We carried out our investigations under approximate solution and we evaluate the minimal evolution time from initial state to one of its final target state. QSL time becomes uniform in the low temperature limit and at higher temperature different oscillatory behaviors are observed. Maximal speed of evolution of quantum systems is determined by QSL time. We use Margolus-Levitin (ML) types bound to investigate the minimal evolution time of quantum states. We also discuss the dependence of QSL time upon temperature, driving time and anisotropy of spin chain environment.

The standard proposal within the context of General relativity and its weak field Newtonian limit for the nature of dark matter is that it consists of dark matter particles of unknown type. In the present work and specifically for spiral galaxy rotation curves, an alternative possibility is explored, in the form of an axially symmetric vortex mass distribution of finite extent threading the centre of the galaxy and perpendicular to its disk. Some general considerations are developed and characteristic properties are identified, pointing to the potential interest of such an alternative to be studied in earnest.

A new wave of relativistic nature is derived from the classical Hamilton-Jacobi equation on a curved space-time. The gravitational time dilation in the neighbourhood of an almost point-like mass is responsible for its existence. In order to obtain such type of wave (interpretable as a matter field), one has to resort to an old idea due to de Broglie according to which the physical ({textbf {3}})-dimensional space behaves as if it were covered with an infinity of clocks. The resulting particle field, that propagates in the physical ({textbf {3}})-dimensional space and is due to the interaction with the (classic) gravitational field of the mass, is shown to be associated with the usual scalar particle wave function of quantum mechanics. Therefore, the model here described, by linking Einstein’s general relativity to the wave-like behaviour of particles via the viewpoint of de Broglie’s Double Solution Theory rather than via the standard mechanisms of field quantisation, provides a new approach to quantum gravity. Finally, it is shown that this model provides a new interpretation of the single-particle interference and explains non-locality in terms of a novel quantum communication channel.

This paper investigates the Ricci solitons of a sub-class of Bianchi type-I spacetimes in f(T) theory of gravity in the presence of perfect fluid. It is found that special sub-classes of perfect fluid Bianchi type-I metrics admit steady, shrinking and expanding Ricci solitons. To tackle the problem, RS equations are explored along with their integrability conditions. Field equations in f(T) theory are derived for the spacetime metric. By solving the field equations we derived general form for f(T). Ricci soliton equations and field equations are solved simultaneously to explore the corresponding Ricci soliton vector fields. We found Ricci soliton vector fields of dimension 4, 5, 6, 7, 8, 10 and 11. In some cases the corresponding metrics are Einstein metrics while in other cases non-Einstein metrics are also obtained which admit Ricci soliton vector fields. The physical quantities (rho ), p, T and f(T) related to each solution are also calculated. Another interesting aspect of our results is that we obtained some non-linear f(T) functions for which field equations possess solutions and those solutions admit Ricci soliton vector fields.

This article explores the analysis of modified holographic Ricci dark energy (MHRDE) in the context of (varvec{f(T)}) theory of gravity, with a focus on the validity of thermodynamics for homogenous and isotropic Friedmann-Robertson-Walker (FRW) universe by using hybrid expansion law (HEL) represented as (varvec{a(t)} varvec{=} varvec{e}^{varvec{mt}} varvec{t}^{varvec{n}}), where (varvec{m, n}) are constants. The study investigates the dynamics of the accelerating universe across the established (varvec{f(T)}) model, (varvec{f(T)} varvec{=} varvec{xi }_{varvec{1}} varvec{T} varvec{+} varvec{xi }_{varvec{2}} varvec{T}^{varvec{xi }_{varvec{3}}} varvec{log } varvec{T}), where (varvec{xi }_{varvec{1}}varvec{,} varvec{xi }_{varvec{2}}varvec{,} varvec{xi }_{varvec{3}}) are constants. The fundamental equations of thermodynamics features of the model have been deliberated. Additionally, the entropy density and temperature of the model are determined. We use the energy conditions in our solutions to identify a range of values for free parameters of the model, ensuring a stable and well-behaved scenario. Furthermore, a detailed examination of the physical and geometrical characteristics of the model has been conducted.

We study the transformation between quantum states under incoherent operations and unitary incoherent operations. In high dimensional systems, we show any two pure states can be transformed into each other under incoherent operations if and only if they can be transformed into each other under unitary incoherent operations. For mixed states, we show any two incoherent states can be transformed into each other under incoherent operations. Furthermore, we show any incoherent states can be transformed by any mixed states under incoherent operations. In qubit systems, we prove the necessary and sufficient condition for the transformation between any two mixed states by incoherent operations alternatively and obtain the corresponding incoherent operations. Moreover we prove any two mixed qubit states with nonzero coherence can be transformed into each other under incoherent operations if and only if they can be transformed into each other under unitary incoherent operations.

This paper is devoted to calculating the Fisher and Shannon information parameters of the Feshbach-Villars oscillator (FVO) for spin-0 particles. Instead of the Klein-Gordon equation, the Feshbach-Villars formalism provides a positive probability density. By determining Fisher information and Shannon entropy, we assess the sensitivity of probability distributions to parameter changes and the degree of uncertainty. Our research provides insights into the dynamics and information-theoretic characteristics of spin-0 particles in both spatial and momentum configurations. This work advances our understanding of the quantum information properties of spin-0 particles and lays the groundwork for future developments in quantum computing and information theory. Finally, the Stam, Cramer–Rao, and Bialynicki–Birula–Mycielski (BBM) inequalities have been verified, and we demonstrated that the BBM inequality remains valid in the form (S_{x}+S_{p}ge 1+ln pi ), consistent with ordinary quantum mechanics.

We compute quasinormal modes of test fields around spherically symmetric black holes with a global monopole in bumblebee gravity. The frequency of oscillation and the damping rate exhibit significant decreasing as the global monopole parameter is increased. An intriguing observation arises in the extreme limit, where the quasinormal modes manifest a form of universal behavior: the actual oscillation frequency remains unaltered despite variations in the Lorentz symmetry breaking (LSB) parameter. Our calculations are conducted through two distinct methods, both of which yield results that align remarkably well. Furthermore, we derive an analytical formula for quasinormal modes within the eikonal approximation and beyond it. In the limits of either vanishing deficit angle or bumblebee parameters, the compact and sufficiently accurate analytic expressions for quasinormal modes are obtained.

This paper considers a set of equations describing the static isotropic gravitational field of a macroscopic body within the framework of the theory of gravity with a constraint. It is shown that for any static solid body, the energy of the gravitational field created by it is equal in magnitude to its rest energy, and the energy density defined in this theory is positive everywhere. A general approximate solution of the gravitational field equations is obtained. A nonsingular solution exists only at certain values for the three integration constants. The out-of-body metric coincides with the Schwarzschild metric, but unlike the general relativity theory (GR), the curvature tensor invariants have a certain finite value everywhere. It is claimed that a generally covariant theory of gravity, constructed on the basis of GR, is not physical since it violates the principle of material unity of the world.