409 research outputs found
Higgs boson production through annihilation at threshold in NLO QCD
We present threshold enhanced NLO QCD corrections to inclusive Higgs
production through bottom anti-bottom annihilation at hadron colliders using
threshold resummed cross section. The resummed cross section is obtained using
factorization properties and Sudakov resummation of the inclusive cross
section. We use the recent results on threshold NLO corrections in QCD for
Drell-Yan production and three loop QCD corrections to Higgs form factor with
bottom anti-bottom quark to achieve this task. This is the first step towards
the evaluation of complete NLO result. We have numerically demonstrated the
importance of such corrections at the LHC.Comment: 15 pages, 1 figur
Massive three loop form factors in the planar limit
We present the color planar and complete light quark QCD contributions to the
three loop heavy quark form factors in the case of vector, axial-vector, scalar
and pseudo-scalar currents. We evaluate the master integrals applying a new
method based on differential equations for general bases, which is applicable
for any first order factorizing systems. The analytic results are expressed in
terms of harmonic polylogarithms and real-valued cyclotomic harmonic
polylogarithms.Comment: 10 pages; Proceedings of the Loops and Legs in Quantum Field Theory,
29th April 2018 - 4th May 2018, St. Goar, Germany; Report number modifie
Two-Loop QCD Corrections to Higgs Amplitude
Exclusive observables involving Higgs boson in association with jets are
often well suited to study the Higgs boson properties. They are rates involving
cuts on the final state jets or differential distributions of rapidity,
transverse momentum of the observed Higgs boson. While they get dominant
contributions from gluon initiated partonic subprocesses, it is important to
include the subdominant ones coming from other channels. In this article, we
study one such channel namely the Higgs production in association with a jet in
bottom anti-bottom annihilation process. We compute relevant amplitude
up to two loop level in QCD where Higgs couples
to bottom quark through Yukawa coupling. We use projection operators to obtain
the coefficients for each tensorial structure appearing in this process. We
have demonstrated that the renormalized amplitudes do have the right infrared
structure predicted by the QCD factorization in dimensional regularization. The
finite parts of the one and two loop amplitudes are presented after subtracting
the infrared poles using Catani's subtraction operators.Comment: Published version; 25 pages, 2 figures; v2: analytically continued
result added, typos are correcte
Spin-2 Form Factors at Three Loop in QCD
Spin-2 fields are often candidates in physics beyond the Standard Model
namely the models with extra-dimensions where spin-2 Kaluza-Klein gravitons
couple to the fields of the SM. Also, in the context of Higgs searches, spin-2
fields have been studied as an alternative to the scalar Higgs boson. In this
article, we present the complete three loop QCD radiative corrections to the
spin-2 quark-antiquark and spin-2 gluon-gluon form factors in SU(N) gauge
theory with light flavors. These form factors contribute to both
quark-antiquark and gluon-gluon initiated processes involving spin-2 particle
in the hadronic reactions at the LHC. We have studied the structure of infrared
singularities in these form factors up to three loop level using Sudakov
integro-differential equation and found that the anomalous dimensions
originating from soft and collinear regions of the loop integrals coincide with
those of the electroweak vector boson and Higgs form factors confirming the
universality of the infrared singularities in QCD amplitudes.Comment: 20 pages, 2 figure
Pseudo-scalar Higgs Boson Production at Threshold NLO and NLL QCD
We present the first results on the production of pseudo-scalar through gluon
fusion at the LHC to NLO in QCD taking into account only soft gluon
effects. We have used the effective Lagrangian that describes the coupling of
pseudo-scalar with the gluons in the large top quark mass limit. We have used
recently available quantities namely the three loop pseudo-scalar form factor
and the third order universal soft function in QCD to achieve this. Along with
the fixed order results, we also present the process dependent resummation
coefficient for threshold resummation to NLL in QCD. Phenomenological
impact of these threshold NLO corrections to pseudo-scalar production at
the LHC is presented and their role to reduce the renormalisation scale
dependence is demonstrated.Comment: 34 pages, 17 figure
NNLO EW⊗QCD corrections to on-shell Z production
In this proceeding, we outline the computational details and present
the results for NNLO mixed EW\otimes⊗QCD
corrections to on-shell production of Z boson at the LHC. We use the
method of differential equation to obtain all the master integrals
analytically, appearing in virtual and real-emission contributions.
These results increase the accuracy of the predictions and contribute to
reduce the theoretical uncertainties
Pseudo-scalar Higgs boson production at NLO+NLL
We consider the production of a pseudo-scalar particle at the LHC, and
present accurate theoretical predictions for its inclusive cross section in
gluon fusion. The prediction is based on combining fixed-order perturbation
theory and all-order threshold resummation. At fixed order we include the exact
next-to-next-to-leading order (NNLO) plus an approximate
next-to-next-to-next-to-leading order (NLO) which is based on the
recent computation at this order for the scalar case. We then add threshold
resummation at next-to-next-to-next-to leading logarithmic accuracy
(NLL). Various forms of threshold resummation are considered,
differing by the treatment of subleading terms, allowing a robust estimate of
the theoretical uncertainties due to missing higher orders. With particular
attention to pseudo-scalar masses of GeV and GeV, we also observe
that perturbative convergence is much improved when resummation is included.
Additionally, results obtained with threshold resummation in direct QCD are
compared with analogous results as computed in soft-collinear effective theory,
which turn out to be in good agreement. We provide precise predictions for
pseudo-scalar inclusive cross section at TeV LHC for a wide range of
masses. The results are available through updated versions of the public codes
ggHiggs and TROLL.Comment: 14 pages, 7 figures, 1 table. Now includes a more precise assessment
of the uncertainty on the approximate N3LO. Final version accepted by EPJ
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