52 research outputs found
The transverse-momentum subtraction method at NLO applied to Higgs boson production at the LHC
We consider the extension of the transverse-momentum () subtraction
method at next-to-next-to-next-to-leading order (NLO) in perturbative QCD.
While all the -subtraction ingredients at are known in
analytical form, the third-order collinear functions and helicity-flip
functions, which contribute only at , are approximated using a
prescription which uses the known result for the total Higgs boson cross
section at this order. As a first application of the third-order
-subtraction method, we present the NLO rapidity distribution of the
Higgs boson at the LHC.Comment: 4 pages, 1 figure, contribution to the 2019 QCD session of the 54th
Rencontres de Moriond. Based on arXiv:1807.1150
NNLO QCD results for diphoton production at the LHC and the Tevatron
We consider direct diphoton production in hadron collisions. We compute the
next-to-next-to-leading order (NNLO) QCD radiative corrections at the
fully-differential level. Our calculation is based on the q_T subtraction
formalism and it is implemented in a parton level Monte Carlo program, which
allows the user to apply arbitrary kinematical cuts on the final-state photons
and the associated jet activity, and to compute the corresponding distributions
in the form of bin histograms. We present selected numerical results related to
Higgs boson searches and diphoton studies performed at the LHC and the
Tevatron, and we show how the NNLO corrections to diphoton production are
relevant to understand the main background of the decay channel (H -> gamma
gamma) of the Higgs boson H.Comment: 8 pages, 3 figures. Contribution to the proceedings of the XXVII
Rencontres de Physique de la Vall\'ee d'Aoste. arXiv admin note: substantial
text overlap with arXiv:1209.3143, arXiv:1207.325
Diphoton isolation studies
We consider the effects of the photon isolation on the production of a pair
of photons in hadron collisions. We study in detail advantages and
disadvantages of the standard and smooth cone isolation criteria, concerning
the theory and the experiment. We put special interest in those kinematic
configurations related to recent Higgs boson studies and searches, and finally
we show the set of isolation parameters proposed by the Les Houches accord
2013, which serves as a guide to understand the comparison of the theoretical
predictions with the data.Comment: 8 pages, 7 figures. Contribution to the Proceedings of the ICHEP 2014
Conference. Accepted in Nuclear and Particle Physics Proceeding
Diphoton production at hadron colliders: transverse-momentum resummation at next-to-next-to-leading logarithmic accuracy
We consider the transverse-momentum (qT) distribution of a diphoton pair
produced in hadron collisions. At small values of qT , we resum the
logarithmically-enhanced perturbative QCD contributions up to
next-to-next-to-leading logarithmic accuracy. At intermediate and large values
of qT, we consistently combine resummation with the known next-to-leading order
perturbative result. All perturbative terms up to order \alpha_S^2 are included
in our computation which, after integration over qT, reproduces the known
next-to-next-to-leading order result for the diphoton pair production total
cross section. We present a comparison with LHC data and an estimate of the
perturbative accuracy of the theoretical calculation by performing the
corresponding variation of scales. In general we observe that the effect of the
resummation is not only to recover the predictivity of the calculation at small
transverse momentum, but also to improve substantially the agreement with the
experimental data.Comment: 17 pages, 16 figures. arXiv admin note: text overlap with
arXiv:1007.235
Master Integrals for double real radiation emission in heavy-to-light quark decay
We evaluate analytically the master integrals for double real radiation
emission in the b --> u W* decay, where b and u are a massive and massless
quark, respectively, while W* is an off-shell charged weak boson. Since the W
boson can subsequently decay in a lepton anti-neutrino pair, the results of the
present paper constitute a further step toward a fully analytic computation of
differential distributions for the semileptonic decay of a b quark at NNLO in
QCD. The latter partonic process plays a crucial role in the study of inclusive
semileptonic charmless decays of B mesons. Our results are expressed in terms
of multiple polylogarithms of maximum weight four.Comment: 21 pages, 6 figures, 2 table
Combining QED and QCD transverse-momentum resummation for Z boson production at hadron colliders
We consider the transverse-momentum () distribution of bosons
produced in hadronic collisions. At small values of , we perform the
analytic resummation of the logarithmically enhanced QED contributions up to
next-to-leading logarithmic accuracy, including the mixed QCD-QED contributions
at leading logarithmic accuracy. Resummed results are consistently matched with
the next-to-leading fixed-order results (i.e. ) at
small, intermediate and large values of . We combine the QED corrections
with the known QCD results at next-to-next-to-leading order
() and next-to-next-to-leading logarithmic accuracy.
We show numerical results at LHC and Tevatron energies, studying the impact of
the QED corrections and providing an estimate of the corresponding perturbative
uncertainty. Our analytic results for the combined QED and QCD resummation,
obtained through an extension of the resummation formalism in QCD, are
valid for the production of generic neutral and colourless high-mass systems in
hadronic collision.Comment: 13 pages, 3 figure
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