Javier Mazzitelli

Higgs Boson pair production at next-to-next-to-leading order in QCD.

We compute the next-to-next-to-leading order QCD corrections for standard model Higgs boson pair production inclusive cross section at hadron colliders within the large top-mass approximation. We provide numerical results for the LHC, finding that the corrections are large, resulting in an increase of O(20%) with respect to the next-to-leading order result at c.m. energy sqrt[sH]=14  TeV. We observe a substantial reduction in the scale dependence, with overlap between the current and previous order prediction. All our results are normalized using the full top- and bottom-mass dependence at leading order. We also provide analytical expressions for the K factors as a function of sH.

Two-loop virtual corrections to Higgs pair production

Abstract We present the two-loop virtual corrections to Standard Model Higgs boson pair production via gluon fusion g g → H H in the heavy top quark limit. Based on this result, we evaluate the corresponding cross section at the LHC at 14 TeV in the next-to-next-to-leading order soft-virtual approximation. We find an inclusive K-factor of about 2.4, resulting in an increase close to 23% with respect to the previous available calculation at next-to-leading order. As expected, we observe a considerable reduction in the renormalization and factorization scale dependence.

Higgs pair production at next-to-next-to-leading logarithmic accuracy at the LHC

A bstractWe perform the threshold resummation for Higgs pair production in the dominant gluon fusion channel to next-to-next-to-leading logarithmic (NNLL) accuracy.The calculation includes the matching to the next-to-next-to-leading order (NNLO) cross section obtained in the heavy top-quark limit, and results in an increase of the inclusive cross section up to 7% at the LHC with centre-of-mass energy Ecm = 14 TeV, for the choice of factorization and renormalization scales μF = μR = Q, being Q the invariant mass of the Higgs pair system.After the resummation is implemented, we estimate the theoretical uncertainty from the perturbative expansion to be reduced to about ±5.5%, plus ∼ 10% from finite top-mass effects. The resummed cross section turns out to be rather independent of the value chosen for the central factorization and renormalization scales in the usual range (Q/2, Q).

Approximate N3LO Higgs-boson production cross section using physical-kernel constraints

A bstractThe single-logarithmic enhancement of the physical kernel for Higgs production by gluon-gluon fusion in the heavy top-quark limit is employed to derive the leading so far unknown contributions, ln 5, 4, 3(1−z), to the N3LO coefficient function in the threshold expansion. Also using knowledge from Higgs-exchange DIS to estimate the remaining terms not vanishing for z = mH2/ŝ → 1, these results are combined with the recently completed soft + virtual contributions to provide an uncertainty band for the complete N3LO correction. For the 2008 MSTW parton distributions these N3LO contributions increase the cross section at 14 TeV by (10 ±2)% and (3 ±2.5)% for the standard choices μR = mH and μR = mH/2 of the renormalization scale. The remaining uncertainty arising from the hard-scattering cross sections can be quantified as no more than 5%, which is smaller than that due to the strong coupling and the parton distributions.

Differential Higgs boson pair production at next-to-next-to-leading order in QCD

A bstractWe report on the first fully differential calculation for double Higgs boson production through gluon fusion in hadron collisions up to next-to-next-to-leading order (NNLO) in QCD perturbation theory. The calculation is performed in the heavy-top limit of the Standard Model, and in the phenomenological results we focus on pp collisions at s=14

Quark and gluon spin-2 form factors to two-loops in QCD

\sqrt{s}=14

Higgs boson pair production at NNLO in QCD including dimension 6 operators

TeV. We present differential distributions through NNLO for various observables including the transverse-momentum and rapidity distributions of the two Higgs bosons. NNLO corrections are at the level of 10%-25% with respect to the next-to-leading order (NLO) prediction with a residual scale uncertainty of 5%-15% and an overall mild phase-space dependence. Only at NNLO the perturbative expansion starts to converge yielding overlapping scale uncertainty bands between NNLO and NLO in most of the phase-space. The calculation includes NLO predictions for pp → HH + jet + X. Corrections to the corresponding distributions exceed 50% with a residual scale dependence of 20%-30%.

Two-loop corrections to the triple Higgs boson production cross section

A bstractWe compute the next-to-next-to-leading order (NNLO) soft and virtual QCD corrections for the partonic cross section of colourless-final state processes in hadronic collisions. The results are valid to all orders in the dimensional regularization parameter ϵ. The dependence of the results on a particular process is given through finite contributions to the one and two-loop amplitudes, which have to be computed in a process-by-process basis. To evaluate the accuracy of the soft-virtual approximation we compare it with the full NNLO result for Drell-Yan and Higgs boson production via gluon fusion. We also provide a universal expression for the hard coefficient needed to perform threshold resummation up to next-to-next-to-leading logarithmic (NNLL) accuracy.