Threshold resummation for pair production of coloured heavy (s)particles at hadron colliders

Abstract

We derive a factorization formula for the production of pairs of heavy coloured particles in hadronic collisions near the production threshold that establishes factorization of soft and Coulomb effects. This forms the basis for a combined resummation of Coulomb and soft corrections, including the non-trivial interference of the two effects. We develop a resummation formalism valid at NNLL accuracy using the momentum-space approach to soft gluon resummation. We present numerical results for the NLL resummed squark-antisquark production cross section at the LHC and Tevatron, including also the contribution of squark-antisquark bound states below threshold. The total correction on top of the next-to-leading order approximation is found to be sizeable, and amounts to (4-20)% in the squark mass region 200 GeV -3 TeV at the 14 TeV LHC. The scale dependence of the total cross section is also reduced.

Associated production of a top pair and a Higgs boson beyond NLO

“…We obtain the approximate NNLO corrections from the perturbative information contained in a soft-gluon resummation formula valid to next-to-next-to-leading logarithmic (NNLL) accuracy. The derivation of this formula is based on the soft-collinear effective theory (SCET) methods 1 used to study differential top-quark pair production (tt) cross sections at NNLL in [15,17,18] (see [19][20][21][22] for SCET-based studies of the total tt cross section). In fact, since both tt and ttH production contain four colored partons, the study of soft-gluon corrections to these processes is conceptually identical and differs only because of the underlying kinematics.…”

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

“…We note that in general Coulomb corrections can also be resummed [46][47][48][49][50]. A combined resummation of Coulomb and soft corrections is, however, beyond the scope of this paper.…”

Top quark pair production beyond NNLO

“…In particular, it was shown in ref. [36] that Coulomb singularities and soft singularities factorize in Mellin space in the N → ∞ limit and in the singlet-octet basis: 9) where the factor…”

“…[2,56]. Here we give the final result: The Coulomb functions J I (N, α s ) are computed by taking a Mellin transform of the resummed momentum-space results obtained in the context of pNRQCD [36,38]. For more details about the procedure of this Mellin transformation, see ref.…”