International Journal of Modern Physics a最新文献

We consider a minimal renormalizable non-supersymmetric $E_6$ Grand Unified Theory using fundamental representation 27 for fermions and scalars. The scalar with adjoint representation 78 is also taken for direct breaking of $E_6$ to SM. The proposed model, guided by TeV-scale vector-like fermions and scalar leptoquark, offers successful gauge unification even in the absence of any intermediate symmetry. Embedded with threshold corrections, it is shown to be compatible with the present experimental limit on proton decay lifetime. The unique feature of the model shows that the GUT threshold corrections to the unification mass is controlled by superheavy gauge bosons only, thereby minimizing the uncertainty of the GUT predictions. The scalar leptoquark and vector-like fermions residing in 27 representation can explain flavor physics anomalies like $R_{D^{(\ast )}}$ as reported by the LHCb collaboration and the muon anomalous magnetic moment reported by the recent muon $g-2$ experiment at Fermilab. The model can also predict a sub-eV scale neutrino at one-loop level via exchange of W and Z gauge bosons through MRIS mechanism.

Using the formalism of generalized fractional derivatives, a two-dimensional nonrelativistic meson system is studied. The mesons are interacting by a Cornell potential. The system is formulated in the domain of the symplectic quantum mechanics by means of the generalized fractional Nikiforov–Uvarov method. The corresponding Wigner function and the energy eigenvalues are then derived. The effect of fractional parameters $\alpha$ and $\beta$ with the ground state solution is analyzed through the Wigner function for the charm–anticharm, bottom–antibottom and $b\overline{c}$ mesons. One of the fundamental achievements of such Cornell model is the determination of heavy quarkonia mass spectra. We have computed these masses and the present results are in agreement with the experimental data, improving previous theoretical results.

We analyze the Axion Electrodynamics in a two-dimensional slab of finite width L containing a homogeneous and isotropic dielectric medium with constant permittivity and permeability. We start from the known decomposition of modes in the nonaxion case and then solve perturbatively the governing equations for the electromagnetic fields to which the axions are also coupled. This is a natural approach, since the finiteness of L destroys the spatial invariance of the theory in the z-direction normal to the plates. In this way, we derive the value of the axion-generated rotation angle of the electric and magnetic fields after their passage through the slab, and use the obtained results to calculate the Casimir force between the two conducting plates. Our calculations make use of the same method as previously outlined by [J. S. Høye and I. Brevik, Eur. Phys. J. Plus 135, 271 (2020)] for the case of Casimir calculations in chiral media and extend former results on the Casimir force in Axion Electrodynamics.

The holographic principle and its realization as the anti-de Sitter/conformal field theory (AdS/CFT) correspondence leads to the existence of the so-called precursor operators. These are boundary operators that carry nonlocal information regarding events occurring deep inside the bulk and which cannot be causally connected to the boundary. Such nonlocal operators can distinguish nonvacuum-like excitations within the bulk that cannot be observed by any local gauge invariant operators in the boundary. The boundary precursors are expected to become increasingly nonlocal the further the bulk process is from the boundary. Such phenomena are expected to be related to the extended nature of the strings. Standard gauge invariance in the boundary theory equates to quantum error correction which furthermore establishes localization of bulk information. I show that when double field theory quantum error correction prescriptions are considered in the bulk, gauge invariance in the boundary manifests residual effects associated to stringy winding modes. Also, an effect of double field theory quantum error correction is the appearance of positive cosmological constant. The emergence of space–time from the entanglement structure of a dual quantum field theory appears in this context to generalize for de Sitter space–times as well.

Machine learning has blossomed in recent decades and has become essential in many fields. It significantly solved some problems in particle physics — particle reconstruction, event classification, etc. However, it is now time to break the limitation of conventional machine learning with quantum computing. A support-vector machine algorithm with a quantum kernel estimator (QSVM-Kernel) leverages high-dimensional quantum state space to identify a signal from backgrounds. In this study, we have pioneered employing this quantum machine learning algorithm to study the $e^{+}{e}^{-}\to ZH$ process at the Circular Electron–Positron Collider (CEPC), a proposed Higgs factory to study electroweak symmetry breaking of particle physics. Using 6 qubits on quantum computer simulators, we optimized the QSVM-Kernel algorithm and obtained a classification performance similar to the classical support-vector machine algorithm. Furthermore, we have validated the QSVM-Kernel algorithm using 6-qubits on quantum computer hardware from both IBM and Origin Quantum: the classification performances of both are approaching noiseless quantum computer simulators. In addition, the Origin Quantum hardware results are similar to the IBM Quantum hardware within the uncertainties in our study. Our study shows that state-of-the-art quantum computing technologies could be utilized by particle physics, a branch of fundamental science that relies on big experimental data.

In a previous paper, we showed theoretically that the total cross-section of the top-quark pair production by electron–positron annihilation is strongly reduced by the presence of a circularly polarized laser field. In this paper, we present the result for the case of a linearly polarized laser field. This time, the total cross-section is significantly enhanced by the laser field.

In high-energy heavy-ion collisions, a nearly perfect fluid, the so-called strongly coupled quark–gluon plasma (QGP), forms. After the short period of thermalization, the evolution of this medium can be described by the laws of relativistic hydrodynamics. The time evolution of the QGP can be understood through direct photon spectra measurements, which are sensitive to the entire period between the thermalization and the freeze-out of the medium. I present a new analytic formula that describes the thermal photon radiation and it is derived from an exact and finite solution of relativistic hydrodynamics with accelerating velocity field. Then I compare my calculations to the most recent nonprompt spectrum of direct photons for $\mathrm{\text{Au}}+\mathrm{\text{Au}}$ at $\sqrt{s_{NN}}=200$$$GeV collisions. I have found a convincing agreement between the model and the data, which allows to give an estimate of the initial temperature in the center of the fireball. My results predict hydrodynamic scaling behavior for the thermal photon spectra of high-energy heavy-ion collisions.

In this paper, we shall study the phase transition of nonminimal coupling of Einstein–Hilbert gravity and electric field of Yang–Mills type in AdS space–time. We couple the Ricci scalar to the Yang–Mills invariant to obtain a modified theory of gravity. A black brane solution is introduced up to the first order of the term $R{F}_{\mu \alpha }^{(a)}{F}^{(a)\mu \alpha }$ in this model. Then, the phase transition of this solution will be investigated in canonical ensemble. Our investigation shows that only the second-order phase transition behavior is seen in this model. Also, due to the coupling of the Yang–Mills field and Ricci scalar, there are differences with the phase transitions of the usual minimal models. We shall show that in the absence of nonminimal coupling there is not any phase transition.

In this short note, we present analysis of the tachyon kink solution on the world-volume of unstable Dp-brane in general background as the solution of the Hamiltonian equations of motion. We also find Hamiltonian for simplified system of Dp-brane and anti-Dp-brane and study its properties.

In this paper, we explore the noncommutative space–time to revive the idea that gamma-ray excess in the galactic center may stem from the annihilation of particle dark matter. In the noncommutative theory, the photon spectrum is produced by direct emission during this annihilation wherein a photon can be embed in the final state together with other direct products in new vertices. In the various configurations of dark matter phenomenology, we pursue the most prevalent model known as singlet scalar. Calculating the relevant aspects of the model and determining the parameters phase space, we derive the photon flux in the galactic center. This region, known for its high density and occasional existence of robust magnetic fields, serves as an ideal location for investigating theories that encompass the concept of Lorentz symmetry breaking. Upon comparing our numerical achievements with experimental data, it becomes evident that noncommutative space–time can be a reliable framework to explain the gamma-ray excess.