Threshold Resummation for Squark-Antisquark and Gluino-Pair Production at the LHC

Abstract

We study the effect of soft gluon emission in the hadroproduction of squark-antisquark and gluino-gluino pairs at the next-to-leading logarithmic (NLL) accuracy within the framework of the minimal supersymmetric model. The one-loop soft anomalous dimension matrices controlling the colour evolution of the underlying hard-scattering processes are calculated. We present the resummed total cross sections and show numerical results for proton-proton collisions at 14 TeV.The size of the NLL contribution to the cross section and the reduction of the scale dependence of the theoretical predictions due to including soft gluon effects are discussed. † anna.kulesza@desy.de,

Soft gluon resummation for associated t t ¯ H $$ \mathrm{t}\overline{\mathrm{t}}\mathrm{H} $$ production at the LHC

“…(2.5), (2.6) reproduce the known results for heavy quark-antiquark (squark-antisquark) pair-production soft anomalous dimension [32,33,[38][39][40] in the limit p B → 0. Also, our result for Γ qq→klB agrees with the result obtained in the SCET framework in [41,42].…”

“…The evolution of the colour exchange at NLL is governed by the one-loop soft anomalous dimension [28,[32][33][34][35][36]. Starting from four coloured partons in the process, the soft anomalous dimension is a matrix and is known for heavyquark [32,33,37], dijet [34][35][36] and supersymmetric particle production [38][39][40]43], as well as for the general case of 2 → n QCD processes [28][29][30]. Here we adopt the calculations of the soft anomalous dimension for the case of 2 → 3 processes with two coloured massive particles in the final state.…”

Search for new phenomena in events with a photon and missing transverse momentum inppcollisions ats=8 TeVwith the ATLAS detecto

“…Only the first two generations of squarks are considered, and they are assumed to be degenerate in mass. Signal cross sections are calculated to next-to-leading order in the strong coupling constant including the resummation of soft gluon emission at nextto-leading-logarithm accuracy when available [46][47][48][49][50]. The nominal cross section and its uncertainty are taken from an envelope of cross-section predictions using different PDF sets and factorization and renormalization scales, as described in Ref.…”

Search for supersymmetry in events with four or more leptons ins=8 TeVppcollisions with the ATLAS detector

“…The inclusion of the resummation of soft gluon emission at next-to-leading-logarithmic (NLL) accuracy (NLO þ NLL) [49][50][51][52][53] is performed in the case of strong sparticle pair production. For neutralino, chargino, slepton and sneutrino production, the NLO cross sections used are in agreement with the NLO þ NLL calculation within ∼2% [54][55][56].…”