19 research outputs found
NNLOPS accurate associated HW production
We present a next-to-next-to-leading order accurate description of associated
HW production consistently matched to a parton shower. The method is based on
reweighting events obtained with the HW plus one jet NLO accurate calculation
implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO
accurate Born distributions. Since the Born kinematics is more complex than the
cases treated before, we use a parametrization of the Collins-Soper angles to
reduce the number of variables required for the reweighting. We present
phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross
Section Working Group.Comment: Minor changes, plots updated, matches the version published in JHE
Analytic double-soft integrated subtraction terms for two massive emitters in a back-to-back kinematics
We consider the double-soft limit of QCD amplitudes with two massive quarks
in a back-to-back kinematics accompanied by two soft partons. We integrate
analytically the respective double-soft eikonal functions over the phase space
of the two soft partons. Within the context of the nested soft-collinear
subtraction scheme, our results may serve as one of the integrated subtraction
terms needed for the analytic and fully-differential description of
next-to-next-to-leading order (NNLO) QCD corrections to colour-singlet decay
into massive partons or to heavy-quark pair production
Momentum-space resummation for transverse observables and the Higgs at NLL+NNLO
We present an approach to the momentum-space resummation of global, recursive
infrared and collinear safe observables featuring kinematic zeros away from the
Sudakov limit. In the hadro-production of a generic colour singlet, we consider
the family of inclusive observables which do not depend on the rapidity of the
radiation, prime examples being the transverse momentum of the singlet, and
in Drell-Yan pair production. We derive a resummation formula valid up
to next-to-next-to-next-to-leading-logaritmic accuracy for the considered
observables. This formula reduces exactly to the customary resummation
performed in impact-parameter space in the known cases, and it also predicts
the correct power-behaved scaling of the cross section in the limit of small
value of the observable. We show how this formalism is efficiently implemented
by means of Monte Carlo techniques in a fully exclusive generator that allows
one to apply arbitrary cuts on the Born variables for any colour singlet, as
well as to automatically match the resummed results to fixed-order
calculations. As a phenomenological application, we present state-of-the-art
predictions for the Higgs-boson transverse-momentum spectrum at the LHC at
next-to-next-to-next-to-leading-logarithmic accuracy matched to fixed
next-to-next-to-leading order.Comment: Journal versio
On the interference of and Higgs production mechanisms and the determination of charm Yukawa coupling at the LHC
Higgs boson production in association with a charm-quark jet proceeds through
two different mechanisms - one that involves the charm Yukawa coupling and the
other that involves direct Higgs coupling to gluons. The interference of the
two contributions requires a helicity flip and, therefore, cannot be computed
with massless charm quarks. In this paper, we consider QCD corrections to the
interference contribution starting from charm-gluon collisions with massive
charm quarks and taking the massless limit, . The behavior of QCD
cross sections in that limit differs from expectations based on the canonical
QCD factorization. This implies that QCD corrections to the interference term
necessarily involve logarithms of the ratio whose resummation is
currently unknown. Although the explicit next-to-leading order QCD computation
does confirm the presence of up to two powers of in the
interference contribution, their overall impact on the magnitude of QCD
corrections to the interference turns out to be moderate due to a cancellation
between double and single logarithmic terms.Comment: 28 pages, 4 figure
Bottom quark mass effects in associated production with decay through NNLO QCD
We present a computation of NNLO QCD corrections to the production of a Higgs
boson in association with a boson at the LHC followed by the decay of the
Higgs boson to a pair. At variance with previous NNLO QCD studies of
the same process, we treat quarks as massive. An important advantage of
working with massive quarks is that it makes the use of flavor jet
algorithms unnecessary and allows us to employ conventional jet algorithms to
define jets. We compare NNLO QCD descriptions of the associated
production with massive and massless quarks and also
contrast them with the results provided by parton showers. We find differences in fiducial cross sections computed with massless and
massive quarks. We also observe that much larger differences between
massless and massive results, as well as between fixed-order and parton-shower
results, can arise in selected kinematic distributions.Comment: 30 pages, 9 figure