A
bstract
We present the first NLO QCD+EW predictions for Higgs boson production in association with a
ℓν
ℓ
or
ℓ
+
ℓ
−
pair plus zero or one jets at the LHC. Fixed-order NLO QCD+EW calculations are ...combined with a QCD+QED parton shower using the recently developed resonance-aware method in the POWHEG framework. Moreover, applying the improved MiNLO technique to
Hℓν
ℓ
+jet and
Hℓ
+
ℓ
−
+jet production at NLO QCD+EW, we obtain predictions that are NLO accurate for observables with both zero or one resolved jet. This approach permits also to capture higher-order effects associated with the interplay of EW corrections and QCD radiation. The behavior of EW corrections is studied for various kinematic distributions, relevant for experimental analyses of Higgsstrahlung processes at the 13 TeV LHC. Exact NLO EW corrections are complemented with approximate analytic formulae that account for the leading and next-to-leading Sudakov logarithms in the high-energy regime. In the tails of transverse-momentum distributions, relevant for analyses in the boosted Higgs regime, the Sudakov approximation works well, and NLO EW effects can largely exceed the ten percent level. Our predictions are based on the POWHEG BOX RES+OpenLoops framework in combination with the Pythia 8.1 parton shower.
Vbfnlo is a fully flexible parton level Monte Carlo program for the simulation of vector boson fusion, double and triple vector boson production in hadronic collisions at next-to-leading order in the ...strong coupling constant.
Vbfnlo includes Higgs and vector boson decays with full spin correlations and all off-shell effects. In addition,
Vbfnlo implements
CP
-even and
CP
-odd Higgs boson via gluon fusion, associated with two jets, at the leading-order one-loop level with the full top- and bottom-quark mass dependence in a generic two-Higgs-doublet model.
A variety of effects arising from beyond the Standard Model physics are implemented for selected processes. This includes anomalous couplings of Higgs and vector bosons and a Warped Higgsless extra dimension model. The program offers the possibility to generate Les Houches Accord event files for all processes available at leading order.
Program title:
Vbfnlo
Catalogue identifier: AEDO_v1_0
Program summary URL:
http://cpc.cs.qub.ac.uk/summaries/AEDO_v1_0.html
Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland
Licensing provisions: GPL version 2
No. of lines in distributed program, including test data, etc.: 339 218
No. of bytes in distributed program, including test data, etc.: 2 620 847
Distribution format: tar.gz
Programming language: Fortran, parts in C++
Computer: All
Operating system: Linux, should also work on other systems
Classification: 11.1, 11.2
External routines: Optionally Les Houches Accord PDF Interface library and the GNU Scientific library
Nature of problem: To resolve the large scale dependence inherent in leading order calculations and to quantify the cross section error induced by uncertainties in the determination of parton distribution functions, it is necessary to include NLO corrections. Moreover, whenever stringent cuts are required on decay products and/or identified jets the question arises whether the scale dependence and a k-factor, defined as the ratio of NLO to LO cross section, determined for the inclusive production cross sections are valid for the search region one is interested in.
Solution method: The problem is best addressed by implementing the one-loop QCD corrections in a fully flexible NLO parton-level Monte Carlo program, where arbitrary cuts can be specified as well as various scale choices. In addition, any currently available parton distribution function set can be used through the LHAPDF library.
Running time: Depending on the process studied. Usually from minutes to hours.
We present an update of the Binoth Les Houches Accord (BLHA) to standardise the interface between Monte Carlo programs and codes providing one-loop matrix elements.
Many highly developed Monte Carlo tools for the evaluation of cross sections based on tree matrix elements exist and are used by experimental collaborations in high energy physics. As the evaluation ...of one-loop matrix elements has recently been undergoing enormous progress, the combination of one-loop matrix elements with existing Monte Carlo tools is on the horizon. This would lead to phenomenological predictions at the next-to-leading order level. This note summarises the discussion of the next-to-leading order multi-leg (NLM) working group on this issue which has been taking place during the workshop on Physics at TeV Colliders at Les Houches, France, in June 2009. The result is a proposal for a standard interface between Monte Carlo tools and one-loop matrix element programs.
Dedicated to the memory of, and in tribute to, Thomas Binoth, who led the effort to develop this proposal for Les Houches 2009. Thomas led the discussions, set up the subgroups, collected the contributions, and wrote and edited this paper. He made a promise that the paper would be on the arXiv the first week of January, and we are faithfully fulfilling his promise. In his honour, we would like to call this the Binoth Les Houches Accord.
Real emission corrections to Higgs production via gluon-fusion, at order
α
s
4, lead to a Higgs plus two-jet final state. We present the calculation of these scattering amplitudes, as induced by ...top-quark triangle-, box- and pentagon-loop diagrams. These diagrams are evaluated analytically for arbitrary top mass
m
t
. We study the renormalization and factorization scale-dependence of the resulting
H+2 jet cross section, and discuss phenomenologically important distributions at the LHC. The gluon-fusion results are compared to expectations for weak-boson fusion cross sections.
We present the
O(α
s
4)
virtual QCD corrections to gluon–gluon scattering due to the interference of tree- and two-loop amplitudes. We work in conventional dimensional regularisation and give ...analytic expressions renormalised in the
MS
scheme. The structure of the infrared divergences agrees with that predicted by Catani while formulae for the finite remainder are given in terms of logarithms and polylogarithms that are real in the physical region. These results, together with those previously obtained for quark–quark and quark–gluon scattering, complete the two-loop matrix elements needed for the next-to-next-to-leading order contribution to inclusive jet production at hadron colliders.
Real-emission corrections to gg-->H, which lead to H+2 jet events, are calculated at order alpha(4)(s). Contributions include top-quark triangles, boxes, and pentagon diagrams and are evaluated ...analytically for arbitrary top mass m(t). This new source of H+2 jet events is compared to the weak-boson fusion cross section for a range of Higgs boson masses. The heavy top-mass approximation appears to work well for intermediate Higgs-boson masses, provided that the transverse momenta of the final-state partons are smaller than the top-quark mass.
The Standard Model from LHC to future colliders Forte, S.; Nisati, A.; Passarino, G. ...
European physical journal. C, Particles and fields,
11/2015, Letnik:
75, Številka:
11
Journal Article
Recenzirano
Odprti dostop
This review summarizes the results of the activities which have taken place in 2014 within the Standard Model Working Group of the “What Next” Workshop organized by INFN, Italy. We present a ...framework, general questions, and some indications of possible answers on the main issue for Standard Model physics in the LHC era and in view of possible future accelerators.
We present the
O(α
4
s)
virtual QCD corrections to the scattering process of massless quark
q
q
̄
→gg
due to the interference of tree and two-loop amplitudes and to the self-interference of one-loop ...amplitudes. We work in conventional dimensional regularisation and our results are renormalised in the
MS
scheme. The structure of the infrared divergences agrees with that predicted by Catani while expressions for the finite remainder are given for the
q
q
̄
→gg
and the
qg→
qg (
g
q
̄
→g
q
̄
) scattering processes in terms of logarithms and polylogarithms that are real in the physical region. These results, together with those previously obtained for quark–quark scattering, are important ingredients in the next-to-next-to-leading order contribution to inclusive jet production at hadron colliders.
We present the two-loop virtual QCD corrections to the scattering of distinct massless quarks,
q
q
̄
→q′
q
̄
′
, in conventional dimensional regularisation. The structure of the infrared divergences ...agrees with that predicted by Catani while expressions for the finite remainder are given for each of the
s-,
t- and
u-channels in terms of polylogarithms. The results presented here form a vital part of the next-to-next-to-leading order contribution to inclusive jet production in hadron colliders and will play a crucial role in improving the theoretical prediction for jet cross sections in hadron–hadron collisions.
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