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Register a new userRemarkable virtual SUSY effects in $W^{pm}$ production at high energy hadron colliders
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We present a complete 1-loop study of the electroweak corrections to the process $ugto dW^+$ in MSSM and SM. The occurrence of a number of remarkable properties in the behavior of the helicity amplitudes at high energies is stressed, and the crucial role of the virtual SUSY contributions in establishing them, is emphasized. The approach to asymptopia of these amplitudes is discussed, comparing the effects of the logarithmic and constant contributions to the mass suppressed ones, which are relevant at lower energies. Applying crossing to $ugto d W^+$, we obtain all subprocesses needed for the 1-loop electroweak corrections to $W^pm$-production at LHC. The SUSY model dependence of such a production is then studied, and illustrations are given for the transverse $W^{pm}$ momentum distribution, as well as the angular distribution in the subprocess center of mass.
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We report on the first computation of the next-to-next-to-leading order (NNLO) QCD corrections to $W^{pm}Z$ production in proton collisions. We consider both the inclusive production of on-shell $W^{pm}Z$ pairs at LHC energies and the total $W^{pm}Z$ rates including off-shell effects of the $W$ and $Z$ bosons. In the off-shell computation, the invariant mass of the lepton pairs from the $Z$ boson decay is required to be in a given mass window, and the results are compared with the corresponding measurements obtained by the ATLAS and CMS collaborations. The NNLO corrections range from 8% at $sqrt{s}$=7 TeV to 11% at $sqrt{s}$=14 TeV and significantly improve the agreement with the LHC data at $sqrt{s}$=7 and 8 TeV.
We study the effects of O(alpha_s) supersymmetric QCD (SQCD) corrections on the total production rate and kinematic distributions of polarized and unpolarized top-pair production in pp and p anti-p collisions. At the Fermilab Tevatron p anti-p collider, top-quark pairs are mainly produced via quark-antiquark annihilation, q anti-q -> t anti-t, while at the CERN LHC pp collider gluon-gluon scattering, g g -> t anti-t, dominates. We compute the complete set of O(alpha_s) SQCD corrections to both production channels and study their dependence on the parameters of the Minimal Supersymmetric Standard Model. In particular, we discuss the prospects for observing strong, loop-induced SUSY effects in top-pair production at the Tevatron Run II and the LHC.
We calculate the SUSY-QCD corrections to the inclusive total cross sections of the associated production processes $ppto W^{pm}H^{mp}+X$ in the Minimal Supersymmetric Standard Model(MSSM) at the CERN Large Hadron Collider(LHC). The SUSY-QCD corrections can increase and decrease the total cross sections depending on the choice of the SUSY parameters. When $mu<0$ the SUSY-QCD corrections increase the leading-order (LO) total cross sections significantly for large tan$beta$ ($sim 40$), which can exceed 10% and have the opposite sign with respect to the QCD and the SUSY-EW corrections, and thus cancel with them to some extent. Moreover, we also investigate the effects of the SUSY-QCD on the differential distribution of cross sections in transverse momentum $p_T$ and rapidity Y of W-boson, and the invariant mass $M_{W^+H^-}$.
A general review of the latest results about single and double vector boson production in the multipurpose experiments at LHC (ATLAS and CMS) and at Tevatron (CDF and D0) will be presented. The review will focus on boson production, while a more detailed report about W and Z properties can be found elsewhere. Only leptonic decays into electrons and muons will be considered.
In LHC searches for new and rare phenomena the top-associated channel $pp to toverline{t}W^pm +X$ is a challenging background that multilepton analyses must overcome. Motivated by sustained measurements of enhanced rates of same-sign and multi-lepton final states, we reexamine the importance of higher jet multiplicities in $pp to toverline{t}W^pm +X$ that enter at $mathcal{O}(alpha_s^3alpha)$ and $mathcal{O}(alpha_s^4alpha)$, i.e., that contribute at NLO and NNLO in QCD in inclusive $toverline{t}W^pm$ production. Using fixed-order computations, we estimate that a mixture of real and virtual corrections at $mathcal{O}(alpha_s^4alpha)$ in well-defined regions of phase space can arguably increase the total $toverline{t}W^pm$ rate at NLO by at least $10%-14%$. However, by using non-unitary NLO multi-jet matching, we estimate that these same corrections are at most $10%-12%$, and at the same time exhibit the enhanced jet multiplicities that are slightly favored by data. This seeming incongruity suggests a need for the full NNLO result. We comment on implications for the $toverline{t}Z$ process.
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