2019 Vol. 43, No. 8
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In this paper we present a comparative study between PYTHIA, EPOS, QGSJET, and SIBYLL generators. The global event observables considered are the charged energy flow, charged particle distributions, charged hadron production ratios and V0 ratios. The study is performed in the LHCb and TOTEM fiducial phase spaces on minimum bias simulated data samples for pp collisions at
We study the hadronic decays of
In this paper, we compute the relativistic corrections of the fragmentation functions (FFs) for a heavy quark to Bc and
A hypergeometric function is proposed to calculate the scalar integrals of Feynman diagrams. In this study, we verify the equivalence between the Feynman parametrization and the hypergeometric technique for the scalar integral of the three-loop vacuum diagram with four propagators. The result can be described in terms of generalized hypergeometric functions of triple variables. Based on the triple hypergeometric functions, we establish the systems of homogeneous linear partial differential equations (PDEs) satisfied by the scalar integral of three-loop vacuum diagram with four propagators. The continuation of the scalar integral from its convergent regions to entire kinematic domains can be achieved numerically through homogeneous linear PDEs by applying the element method.
In past years, several hints of lepton flavor universality (LFU) violation have emerged from the
During the past few years, signs of lepton flavor universality (LFU) violation have been observed in
We investigate the static, spherically symmetric regular black hole solutions in the generalized Rastall gravity. In particular, the prescription of Rastall gravity implies that the present approach does not necessarily involve nonlinear electrodynamics. Subsequently, the resulting regular black hole solutions can be electrically and magnetically neutral. The general properties of the regular black hole solutions are explored. Moreover, specific solutions are derived and discussed, particularly regarding the parameter related to the degree of violation of the energy-momentum conservation in the Rastall theory.
We give the Buchdahl stability bound in Eddington-inspired Born-Infeld (EiBI) gravity. We show that this bound depends on an energy condition controlled by the model parameter
In the excitation of the resonant state followed by the sequential cluster-decay, the in-plane angular correlation method is usually employed to determine the spin of the mother nucleus. However, the correlation pattern exhibited in a two-dimensional angular-correlation spectrum depends on the selected coordinate system. In particular, the parity-symmetric and axial-symmetric processes should be presented in a way to enhance the correlation pattern, whereas the non-symmetric process should be plotted separately to reduce the background. In this study, three coordinate systems previously adopted for correlation patterns in the literature are described and compared to each other. The consistency among these systems is evaluated based on the experimental data analysis for the 10.29-MeV state in 18O. A spin-parity of 4+ is obtained for all three coordinate systems.
The collective rotations of the
We propose a novel self-consistent mean field approximation method by means of a Fierz transformation, taking the Nambu-Jona-Lasinio model as an example. This new self-consistent mean field approximation introduces a new free parameter α to be determined experimentally. When α assumes the value of 0.5, the approximation reduces to the mean field calculation commonly used in the past. Subsequently, we study the influence of the undetermined parameter α on the phase diagram of the two-flavor strong interaction matter. The value of α plays a crucial role in the strong interaction phase diagram, as it not only changes the position of the phase transition point of strong interaction matter, but also affects the order of the phase transition. For example, when α is greater than the critical value
We explore the Kibble-Zurek scaling of conserved charge using stochastic diffusion dynamics. The characteristic scales
We investigate the extinction coefficients of the surface atmospheric aerosol over the Large High Altitude Air Shower Observatory (LHAASO), located at the Haizi Mountain, Daocheng County, China. To this end, we utilize the Longtin model, Mie scattering theory, and experimental data obtained by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). Our theoretical calculations show that the total extinction coefficients of the atmospheric aerosol at the wavelength of 200–500 nm are inversely proportional to the laser wavelength, and influenced by the wind speed. From July 2015 to October 2016, the extinction coefficient of the surface atmospheric aerosols at 532 nm wavelength reached 0.04 km−1 with no wind, while it increased to 0.1 km−1 with gusts. In this period, the extinction coefficients of the surface atmospheric aerosol at 532 nm wavelength, obtained by the CALIPSO, change from 0.01 to 0.07 km−1, which is less than the values obtained the theoretical calculation and larger than the average of Tibetan Plateau in 2006−2016. These calculations and experimental evidence provide important arguments to the model of atmospheric aerosol to be applied in the calibration of LHAASO. Our results suggest that the extinction coefficients over LHAASO require further study, including research on the size distribution, shape, concentration of aerosols particles, wind dependence, relative humidity dependence, etc.
The precise spectrum of electrons and positrons at high energies plays an important role in understanding their origin. DArk Matter Particle Explorer has reported their first measurement of the
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