Study on Tunnelling Radiation in 4 Dimension Black Holes Vector Particles

Recent studies show that the tunnelling radiation of vector particles has been studied successfully by WKB approximation and Hamilton-Jacobi method. In view of this, the main purpose of this paper is to study the Proca equation and the vector particles tunnelling radiation in a 4-dimensional black hole. Finally, the results here show that the temperature of the vector particle is the same as that of the Dirac particle.

Pauli approximation for a vector particle with anomalous magnetic moment in an external Coulomb field

Herein, a spin 1 particle with anomalous magnetic moment in an external Coulomb field is studied. We start with the relativistic tensor system of the Proca type in Cartesian coordinates. In these equations the Γ parameter is present related to an additional characteristic of the particle. In the case of an external magnetic field, it is interpreted as an anomalous magnetic moment. In the presence of an external electric field, additional interaction terms are presented as well; moreover, the terms of the first and second orders in parameter Γ appear. The case of an external Coulomb field is considered in detail. In the nonrelativistic approximation a Pauli type equation is obtained. In the nonrelativistic equation the separation of the variables with the use of spherical vectors is realized. One separate 2-nd order differential equation is found, in which additional interaction terms are missing. Besides, we derive systems of two coupled 2-nd order equations wherein linear and quadratic in parameter Γ interaction terms are presented. Previously, another approach was developed for analyzing the vector particle with anomalous magnetic moment. It was based on the use of tetrad formalism and separation of the variables in the Duffin – Kemmer equation with the help of the Wigner function. The nonrelativistic approximation was performed directly in the system of radial equations. Besides, previously formal Frobenius type solutions for an arising 4-th order differential equation were constructed; however, physically interpretable energy spectra were not found. We have proved that the radial equations derived by different methods are the same up to a simple liner transformation over two radial functions. In this paper, we have obtained a simpler 4-th order equation, the construction of Frobenius solutions becomes technically easier, but physical energy spectra are not found either.

Cosmological constraint on vector mediator of neutrino-electron interaction in light of XENON1T excess

Recently, the XENON1T collaboration reported an excess in the electron recoil energy spectrum. One of the simplest new physics interpretation is a new neutrino-electron interaction mediated by a light vector particle. However, for the parameter region favored by this excess, the constraints from the stellar cooling are severe. Still, there are astrophysical uncertainties on those constraints. In this paper, we discuss the constraint on the light mediator from the effective number of neutrino Neff in the CMB era, which provides an independent constraint. We show that Neff is significantly enhanced and exceeds the current constraint in the parameter region favored for the XENON1T excess. As a result, the interpretation by a light mediator heavier than about 1 eV is excluded by the Neff constraint.

Collider constraints on a dark matter interpretation of the XENON1T excess

In light of the excess in the low-energy electron recoil events reported by XENON1T, many new physics scenarios have been proposed as a possible origin of the excess. One possible explanation is that the excess is a result of a fast moving dark matter (DM), with velocity $$v\sim $$ v ∼ 0.05–0.20 and mass between 1 MeV and 10 GeV, scattering off an electron. Assuming the fast moving DM-electron interaction is mediated by a vector particle, we derive collider constraints on the said DM-electron interaction. The bounds on DM-electron coupling is then used to constrain possible production mechanisms of the fast moving DM. We find that the preferred mass of the vector mediator is relatively light ($$\lesssim $$ ≲ 1 GeV) and the coupling of the vector to the electron is much smaller than the coupling to the fast moving DM.

Numerical Study of Heat Transfer in Gravity-Driven Particle Flow around Tubes with Different Shapes

In the present paper, the heat transfer of gravity-driven dense particle flow around five different shapes of tubes is numerically studied using discrete element method (DEM). The velocity vector, particle contact number, particle contact time and heat transfer coefficient of particle flow at different particle zones around the tube are carefully analyzed. The results show that the effect of tube shape on the particle flow at both upstream and downstream regions of different tubes are remarkable. A particle stagnation zone and particle cavity zone are formed at the upstream and downstream regions of all the tubes. Both the stagnation and cavity zones for the circular tube are the largest, and they are the smallest for the elliptical tube. As the particle outlet velocity (vout) changes from 0.5 mm/s to 8 mm/s at dp = 1.72 mm/s, when compared with the circular tube, the heat transfer coefficient of particle flow for the elliptical tube and flat elliptical tube can increase by 20.3% and 15.0% on average, respectively. The proper design of the downstream shape of the tube can improve the overall heat transfer performance more efficiently. The heat transfer coefficient will increase as particle diameter decreases.

PARTICLE SWARM OPTIMIZATION BERBASIS CO-EVOLUSIONER DALAM EVALUASI KINERJA ASISTEN DOSEN

Assessment of the performance of the teaching assistant as a form of real behavior displayed by each assistant as a work achievement is carried out every year. The evaluation parameters of lecturer assistant performance are taken from the UCI Machine Repository where these parameters are English speakers, course instructors, courses, summer or regular semesters and class sizes. The evaluation process requires a model as the best feature selection, in this case we propose a co-evolutionary particle swarm optimization method to improve the accuracy of the mechine vector supprot method. Testing the dataset using the Rapid Miner software of various validation criteria starting from the accuracy test, precission test, recall test and then presented in the AUC curve. The results of the development of co-evolution based mechine vector-particle swarm optimization methods provide good classification and increase the validation value so that it can be used as a periodic control in evaluating the performance of the teaching assistant.

Search for dark forces at KLOE-2

During the last years several Dark Sector Models have been proposed in order to address striking and puzzling astrophysical observations which fail standard interpretations. In the minimal case a new vector particle, the so called dark photon or U-boson, is introduced, with small coupling with Standard Model particles. Also, the existence of a dark Higgs boson h’ is postulated, in analogy with the Standard Model, to give mass to the U-boson through the Spontaneous Symmetry Breaking mechanism. The discovery of such a Dark Force Mediator would belong to a new field of Physics Beyond the Standard Model. The KLOE experiment, working on the DAΦNE e+e− collider in Frascati, searched for the existence of the U-boson in a quite complete way, investigating several different processes and final states. Tight limits on the model parameters have been set at 90%CL. Further improvements are expected in terms of sensitivity and discovery potential with the new KLOE-2 detector working on the improved DAΦNE e+e− collider, which has collected more than 5 fb−1.