NLL soft and Coulomb resummation for squark and gluino production at the LHC

Abstract

We present predictions of the total cross sections for pair production of squarks and gluinos at the LHC, including the stop-antistop production process. Our calculation supplements full fixed-order NLO predictions with resummation of threshold logarithms and Coulomb singularities at next-to-leading logarithmic (NLL) accuracy, including boundstate effects. The numerical effect of higher-order Coulomb terms can be as big or larger than that of soft-gluon corrections. For a selection of benchmark points accessible with data from the 2010-2012 LHC runs, resummation leads to an enhancement of the total inclusive squark and gluino production cross section in the 15-30% range. For individual production processes of gluinos, the corrections can be much larger. The theoretical uncertainty in the prediction of the hard-scattering cross sections is typically reduced to the ±10% level.

Phenomenology of QCD threshold resummation for gluino pair production at NNLL

“…For gluino pair production, this has been analyzed in ref. [10]. Finally, we note that the choice of the soft scale actually determines what is being resummed.…”

“…At next-to-next-to-leadinglogarithmic (NNLL) precision, one needs the color decomposition of the NLO cross section near the threshold, where higher powers of β are skipped. For gluino pair production, the state of the art in the momentum-space formalism is a combined soft and Coulomb resummation up to NLL accuracy [10]. Within the Mellin-space approach, the NLL results of ref.…”

“…Below the threshold, one has a discrete spectrum of bound-states. If these are taken into account, J should be expressed as a function of the energy E = √ŝ − 2m g relative to the threshold [9,10,29].…”

“…(3.2) is set to η = 2a Γ (µ s , µ f ) after performing the derivative. It contains single logarithms [10] which can be seen by expanding η = 4 a s (…”

“…At LO, it is related to the partonic Born cross section [9,10,29] 14) where the approximations are valid in the limitŝ → 4m 2 g . Near the threshold, the LO cross section is factored out from higher order contributions, where, apart from an overall factor β due to the Born term, all positive powers of β are set to zero.…”