Modern Physics Letters A

The nature of dark matter is one of the most fundamental scientific unknowns. Particle physicists have spent decades searching for evidence of dark matter particles. The PandaX project is a staged xenon-based dark matter direct detection experiment located at the China Jinping Underground Laboratory. In this paper, we give an overview of the PandaX experiment, discuss its recent scientific results, and outline the plan for the future.

We investigate the nonstandard neutrino interactions (NSI) in the rare decays of $B_c^{+}$ mesons involving neutrinos in the final state. It is suggested that the interference between Standard Model and nonstandard interaction can provide sizeable contribution. We calculate the limits on NSI free parameters (${𝜖}_{\tau \tau }^{uL}$, ${𝜖}_{\tau \tau }^{dL}$) and compare them with experimental data.

Based on the coherent state (S1) and the operator ${(x{a}^{†}+ya)}^m$, we induce other three quantum states (here we abbreviate them as S2, S3 and S4). S2 is obtained by operating the operator on S1 directly. S3 is an orthogonal state of S1 constructed from the orthogonalizer relevant with that operator. S4 is a continuous-variable (CV) qubit state superposed from S1 and S3. We study and compare the mathematical and physical properties of such four quantum states. We demonstrate some statistical properties for S1–S4, including the mean photon number (MPN), anti-bunching effect, quadrate squeezing, photon number distribution, Husimi Q-function and Wigner function. The numerical results show some interesting non-classical characters for such states. It is worthy to note that the photon-added coherent state introduced by Agarwal and Tara is only a special case of our considered states.

After having obtained previously an extended first approximation of Maxwell’s equations in Fock’s nonlinear relativity, we propose here the corresponding exact form. In order to achieve this goal, we were inspired mainly by the special relativistic version of Feynman’s proof from which we constructed a formal approach more adapted to the noncommutative algebra. This reasoning lets us establish the exact form of the generalized first group of Maxwell’s equations. To deduce the second one, we have imposed the electric–magnetic duality. As in the k-Minkowski spacetime, the generalized Lorentz force depends on the mass of the particle. After having restored the R-Lorentz algebra symmetry, we have used the perturbative treatment to find the exact form of the generalized Dirac’s magnetic monopole in our context. As consequence, the Universe could locally contain the magnetic charge but in its totality it is still neutral.

The neutrino masses can be ascribed to some operators of higher dimension than the Weinberg operator, so that the energy scale of underlying theory can be lowered to an accessible level for the ongoing or upcoming colliders. We hereby consider an interesting model in this connection where quintuplet fermions with hypercharge $-$2 are introduced and therefore the neutrino masses are produced by dimension-11 operators. These exotic fermions can be pairly produced at the LHC via electroweak interactions and subsequently decay to multiple leptons. We simulate the relevant signal and backgrounds of the triply charged fermion in this model, and give the needed integrated luminosity to observe such a particle at the 13 TeV LHC.

The extended thermodynamics of Reissner–Nordström charged black holes in D-dimensional anti-de Sitter spacetime has a phase structure in the (T, p) plane that includes a line of first-order phase transitions ending in a second-order transition point. For each D$\ge$4, properties of the critical black hole at that point are explored, motivated by the observation that in D$=$4 its neighborhood plays a core role in defining a very special class of heat engines that asymptote to Carnot efficiency in the large charge limit. This new limit provides a model of a novel low-temperature thermodynamic system. The double limit of approaching the horizon while sending the charge large at an appropriate rate yields a fully decoupled D-dimensional Rindler spacetime with zero cosmological constant.