arXiv subjects

Fei Wang

Publications and source records attributed to Fei Wang.

796 records · Page 45Linked to original sources

arXiv2005

Pressure Raman Effects and Internal Stress in Network Glasses

Raman scattering from binary GexSe1-x glasses under hydrostatic pressure shows onset of a steady increase in the frequency of modes of corner-sharing GeSe4 tetrahedral units when the external pressure P exceeds a threshold value Pc. The threshold pressure Pc(x) decreases with x in the 0.15 < x < 0.20 range, nearly vanishes in the 0.20 < x < 0.25 range, and then increases in the 0.25 < x < 1/3 range. These Pc(x) trends closely track those in the non-reversing enthalpy, DeltaHnr(x), near glass transitions (Tgs), and in particular, both DeltaHnr(x) and Pc(x) vanish in the reversibility window (0.20 < x < 0.25). It is suggested that Pc provides a measure of stress at the Raman active units; and its vanishing in the reversibility window suggests that these units are part of an isostatically rigid backbone. Isostaticity also accounts for the non-aging behavior of glasses observed in the reversibility window.

cond-mat.dis-nn↗

arXiv2004

SuperWIMP dark matter scenario in light of WMAP

The heavy gravitinos in minimal supergravity (mSUGRA) models couple gravitionally and can naturally be the Superweakly Interacting Massive Particle (SuperWIMP). As plausible candidates for the cold dark matter in the universe, such gravitino SuperWIMPs can naturally evade the current dark matter detection experiments due to their superweak couplings. However, this scenario must subject to the constraints from the Big Bang nucleosynthesis (BBN) predictions for light element abundances as well as the Wilkinson Mircrowave Anisotropy Probe (WMAP) data for the relic density. Our study shows that requiring BBN predictions to agree with the WMAP data of light element abundances can impose upper and lower mass bounds for both the gravitino and the next-to-lightest supersymmetric particle (NLSP). From a scan over the mSUGRA parameter space subjected to the BBN constraints and the WMAP data, we find that in the neutralino NLSP case, the low tan-beta (< 40) region as well as the region accessible at CERN Large Hadron Colldier (LHC) will be severely restrained.

hep-ph↗

arXiv2003

Supersymmetric effects in top quark decay into polarized W-boson

We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak (SUSY-EW) corrections to the top quark decay into a b-quark and a longitudinal or transverse W-boson. The corrections are presented in terms of the longitudinal ratio Γ(t-->W_L b)/Γ(t--> W b) and the transverse ratio Γ(t-->W_- b)/Γ(t--> W b). In most of the parameter space, both SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1% in magnitude and they tend to have opposite signs. The corrections to the total width Γ(t-->W b) are also presented for comparison with the existing results in the literature. We find that our SUSY-EW corrections to the total width differ significantly from previous studies: the previous studies give a large correction of more than 10% in magnitude for a large part of the parameter space while our results reach only few percent at most.

hep-ph↗

arXiv2003

Note on the asymptotic approximation of a double integral with an angular spectrum representation

In this note, we are concerned with the asymptotic approximation of a class of double integrals which can be represented as an angular spectrum superposition. These double integrals typically appear in electromagnetic scattering problems. Based on the synthetic manipulation of the method of steepest descent path, approximate expressions of the double integrals are derived in terms of the leading term of the contribution to the asymptotic expansions.

math-ph↗