Energy Loss in Nuclear Drell-Yan Process

By means of the nuclear parton distributions which can be used to provide a good explanation for the EMC effect in the whole x range, we investigate the energy loss effect in nuclear Drell-Yan process. When the cross section of lepton pair production is considered varying with the center-of-mass energy of the nucleon-nucleon collision, we find that the nuclear Drell-Yan(DY) ratio is suppressed due to the energy loss, which balances the overestimate of the DY ratio only in consideration of the effect of nuclear parton distributions.Comment: 10 pages, LaTeX, 1 ps figures, To appear in Eur. Phys. J.

The Non-perturbative Effect on R=σL/σTR=\sigma_L /\sigma_T from QCD Vacuum

We investigate the non-perturbative effects on the ratio $R=\sigma_L /\sigma_T$ in lepton-nucleon deep inelastic scattering by taking into account the lowest dimensional condensate contributions from the QCD vacuum. By combining conventional perturbative QCD corrections and the Georgi- Politzer target-mass effects with the non-perturbative effects from the QCD vacuum, we give a good description of the $Q^2$ and $x$ dependences of $R$ in comparison with the recent experimental data.Comment: 13 pages, LaTeX, 2 eps figures, To appear in Phys. Lett.

Next-to-leading order QCD predictions for associated production of top squarks and charginos at the CERN LHC

We present the calculations of the complete next-to-leading order (NLO) inclusive total cross sections for the associated production processes $pp\to \tilde{t}_i\tilde{\chi}_k^-+X$ in the Minimal Supersymmetric Standard Model at the CERN Large Hadron Collider. Our calculations show that the total cross sections for the $\tilde{t}_1\tilde{\chi}_1^-$ production for the lighter top squark masses in the region 100 GeV $< m_{\tilde{t}_1}<$ 160 GeV can reach 1 pb in the favorable parameter space allowed by the current precise experiments, and in other cases the total cross sections generally vary from 10 fb to several hundred fb except both $m_{\tilde{t}_1}>$ 500 GeV and the $\tilde{t}_2\tilde{\chi}_2^-$ production channel. Moreover, we find that the NLO QCD corrections in general enhance the leading order total cross sections significantly, and vastly reduce the dependence of the total cross sections on the renormalization/factorization scale, which leads to increased confidence in predictions based on these results.Comment: 42 pages, 13 figures, RevTex4. Journal-ref adde