分类: 物理学 提交时间: 2016-05-08
摘要: The percolation phase transitions of two-dimensional lattice networks under a generalized Achlioptas process (GAP) are investigated. During the GAP, two edges are chosen randomly from the lattice and the edge with minimum product of the two connecting cluster sizes is taken as the next occupied bond with a probability p. At p = 0.5, the GAP becomes the random growth model and leads to the minority product rule at p = 1. Using the finite-size scaling analysis, we find that the percolation phase transitions of these systems with 0.5 <= p <= 1 are always continuous and their critical exponents depend on p. Therefore, the universality class of the critical phenomena in two-dimensional lattice networks under the GAP is related to the probability parameter p in addition.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We recalculate the two-loop beta functions for three gauge couplings taking into account all low energy threshold corrections in split supersymmetry(split-SUSY) which assumes a very high scalar mass scale M-S. We find that in split-SUSY with a gaugino mass unification assumption and with a large M-S the gauge coupling unification requires a lower bound on the gaugino mass. Combined with the constraints from the dark matter relic density and direct detection limits, we find that split-SUSY is very restricted and for dark matter mass below 1 TeV the allowed parameter space can be fully covered by XENON-1T(2017).
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: Cosmic ray anomalies observed by PAMELA and Fermi-LAT experiments may be interpreted by heavy (TeV-scale) dark matter annihilation enhanced by Sommerfeld effects mediated by a very light (sub-GeV) U(1)_X gauge boson, while the recent direct searches from
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We propose to split the sparticle spectrum from the hierarchy between the GUT scale and the Planck scale. A split supersymmetric model, which gives non-universal gaugino masses, is built with proper high dimensional operators in the framework of SO(10) GUT. Based on a calculation of two-loop beta functions for gauge couplings (taking into account all weak scale threshold corrections), we check the gauge coupling unification and dark matter constraints (relic density and direct detections). We find that our scenario can achieve the gauge coupling unification and satisfy the dark matter constraints in some part of parameter space. We also examine the sensitivity of the future XENON1T experiment and find that the currently allowed parameter space in our scenario can be covered for a neutralino dark matter below about 1.0 TeV.
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: To understand the origin of the left–right symmetry, we study a partial unification model based on SU ( 4 ) W × U ( 1 ) B ? L which can be broken down to the minimal left–right model either through the Higgs mechanism in four dimensions or through the fiv