\Lambda_b Lifetime from the HQET Sum Rule

The HQET sum rule analysis for the \Lambda_b matrix element of the four-quark operator relevant to its lifetime is reported. Our main conclusion is that the lifetime ratio \tau(\Lambda_b)/\tau(B^0) can be as low as 0.91.Comment: 5 pages, latex, no figures, uses sprocl.sty (included). Talk by C. Liu at Int. Conf. on Flavor Phys., Zhang-Jia-Jie, 31/5-6/6 200

g-2 in composite models of leptons

Based on the bound state description of the muon and general relativistic covariant quantum field theory, we illustrate with a simple composite model that the observed deviation of (g-2)_\mu can be a demonstration of the substructure of the muon and give the constraints on the radius of the muon in different cases of light constituents and heavy constituents.Comment: 14 pages, 4 eps figures, revtex, several arguments and some references renewe

Twist-3 contribution to the pion electromagnetic form factor

Non-leading contribution to the pion electromagnetic form factor which comes from the pion twist-3 wave function is analyzed in the modified hard scattering approach (MHSA) proposed by Li and Sterman. This contribution is enhanced significantly due to bound state effect (the twist-3 wave function is independent of the fractional momentum carried by the parton and has a large factor $\sim m_\pi^2/m_0$ with $m_\pi$ being the pion meson mass and $m_0$ being the mean u- and d-quark masses). Consequently, although it is suppressed by the factor $1/Q^2$, the twist-3 contribution is comparable with and even larger than the leading twist (twist-2) contribution at intermediate energy region of $Q^2$ being $2 \sim 40 {GeV}^2$.Comment: 10 pages, 2 fgures, latex. More discussions on the Sudakov effect added, references added. To appear in European Physical Journal C (Zeitschrift fur Physik C