Soft Gluon Resummation Effects in Single Graviton Production at the CERN Large Hadron Collider in the Randall-Sundrum Model

We study QCD effects in single graviton production at the CERN Large Hadron Collider (LHC) in the Randall-Sundrum (RS) Model. We present in detail the complete next-to-leading order (NLO) QCD corrections to the inclusive total cross sections. The NLO QCD corrections enhance significantly the total cross sections and decrease efficiently the dependence of the total cross sections on the factorization and renormalization scales. We also examine the uncertainty of the total cross sections due to the parton distribution function (PDF) uncertainties. For the differential cross sections on the transverse momentum ($q_T$) of the graviton, within the CSS resummation formalism, we resum the logarithmically-enhanced terms at small $q_T$ to all orders up to NLO logatithmic accuracy. Combined with the fixed order calculations, we give consistent predictions for both small $q_T$ and large $q_T$.Comment: 26 pages, 13 figures; minor changes and misprints corrected; version to appear in PR

Soft Gluon Resummation Effects in Single Slepton Production at Hadron Colliders

We investigate QCD effects in the production of a single slepton at hadron colliders in the Minimal Supersymmetric Standard Model without R-parity. We calculate the total cross sections and the transverse momentum distributions at next-to-leading order in QCD. The NLO corrections enhance the total cross sections and decrease the dependence of the total cross sections on the factorization and renormalization scales. For the differential cross sections, we resum all order soft gluon effects to give reliable predictions for the transverse momentum distributions. We also compare two approaches to the non-perturbative parametrization and found that the results are slightly different at the Tevatron and are in good agreement at the LHC. Our results can be useful to the simulation of the events and to the future collider experiments.Comment: 26 pages, 12 figures, RevTeX4; Minor changes; Version to appear in PR

Charged Higgs Production at Linear Colliders in Large Extra Dimensions

In the Two-Higgs-Doublet Model(2HDM) with large extra dimensions(LED), we study the contributions of virtual Kaluza-Klein(KK) gravitons to 2HDM charged Higgs production, especially in the two important production processes $e^+e^-\to H^+H^-$ and $e^+e^-\to H^-t\bar{b}$, at future linear colliders (LC). We find that KK graviton effects can significantly modify these total cross sections and also their differential cross sections compared to their respective 2HDM values and, therefore, can be used to probe the effective scale $\Lambda_T$ up to several TeV. For example, at $\sqrt{s}=2$ TeV, the cross sections for $e^+e^-\to H^+H^-$ and $e^+e^-\to H^-t\bar{b}$ in the 2HDM are 7.4fb for $m_{H^-}=150$ GeV and 0.003fb for $m_{H^-}=1.1$ TeV and $\tan\beta=40$, while in LED they are 12.1fb and 0.01fb, respectively, for $\Lambda_T=4$ Tev.Comment: 18 pages, 11 figures; a version to appear in PR