186 research outputs found
Higgs + 2 jets: Compact Analytic Results
This report describes the recent efforts to compute analytic formulae for the
Next-to-Leading-Order (NLO) QCD corrections to Higgs plus two jet production at
hadron colliders. In these calculations the Higgs boson couples to gluons via a
top-quark loop which is integrated out to form an effective vertex. The
amplitudes are further simplified by splitting the real Higgs scalar into the
sum of two complex scalars phi and phi^dagger. Four-dimensional unitarity is
used to construct the cut-containing pieces of the amplitude, while a variety
of bootstrap and Feynman diagram techniques are used to construct the rational
pieces. The results described here are valid in the limit of a large top quark
mass and when the transverse momenta of the jets are less than mt.Comment: Talk given at RADCOR 2009 - 9th International Symposium on Radiative
Corrections (Applications of Quantum Field Theory to Phenomenology) October
25 - 30 2009. 6 page
at Next-to-Next-to-Leading Order Accuracy
We present the calculation of the decay at
next-to-next-to-leading order (NNLO) accuracy. We consider contributions in
which the Higgs boson couples directly to bottom quarks, i.e. our predictions
are accurate to order . We calculate the
various components needed to construct the NNLO contribution, including an
independent calculation of the two-loop amplitudes. We compare our results for
the two-loop amplitudes to an existing calculation finding agreement. We
present multiple checks on our two-loop expression using the known infrared
factorization properties as the emitted gluon becomes soft or collinear. We use
our results to construct a Monte Carlo implementation of and present jet rates and differential distributions in the
Higgs rest frame using the Durham jet algorithm.Comment: 42 pages, 5 figures. v3: matches published version, attached
supplementary file with two-loop amplitude
Triphoton production at hadron colliders
We present next-to-leading order predictions for the production of triphoton
final states at the LHC and the Tevatron. Our results include the effect of
photon fragmentation for the first time and we are able to quantify the impact
of different isolation prescriptions. We find that calculations accounting for
fragmentation effects at leading order, and those employing a smooth cone
isolation where no fragmentation contribution is required, are in reasonable
agreement with one another. However, larger differences in the predicted rates
arise when higher order corrections to the fragmentation functions are
included. In addition we present full analytic results for the
and jet one-loop amplitudes. These
amplitudes, which are particularly compact, may be useful to future
higher-order calculations. Our results are available in the Monte Carlo code
MCFM.Comment: 16 pages, 4 figure
production at NNLO including anomalous couplings
In this paper we present a next-to-next-to-leading order (NNLO) QCD
calculation of the processes and that we have implemented in MCFM. Our calculation includes
QCD corrections at NNLO both for the Standard Model (SM) and additionally in
the presence of and anomalous couplings. We compare
our implementation, obtained using the jettiness slicing approach, with a
previous SM calculation and find broad agreement. Focusing on the sensitivity
of our results to the slicing parameter, we show that using our setup we are
able to compute NNLO cross sections with numerical uncertainties of about
, which is small compared to residual scale uncertainties of a few
percent. We study potential improvements using two different jettiness
definitions and the inclusion of power corrections. At TeV we
present phenomenological results and consider as a background to
production. We find that, with typical cuts, the inclusion of
NNLO corrections represents a small effect and loosens the extraction of limits
on anomalous couplings by about .Comment: 30 pages, 14 figure
Hadronic productions of a Higgs boson in association with two jets at next-to-leading order
We present the calculation of hadronic production of a Higgs boson in association with two jets at next-to-leading order in perturbation theory. We consider amplitudes in an effective theory in which the Higgs couples to gluons in the limit of a large top quark mass. We treat the Higgs as the real part of the complex field φ that couples to the self-dual field strengths. We use modern on-shell inspired methods to calculate helicity amplitudes and we give a detailed review of unitarity based and on-shell methods. Using these unitarity methods we derive the cut-constructible pieces of the general φ-MHV amplitudes in which the positions of the two negative gluons are arbitrary. We then generate the cut-constructible pieces of the φ-NMHV four parton amplitudes. We generate the rational pieces of these amplitudes and the four-gluon φ-MHV amplitude using Feynman diagrams. For the φ-MHV amplitude we also use the unitarity-boostrap method to calculate the rational pieces. We then implement these, and analytic results from previous calculations, into MCFM. Using this
program we are able to perform some phenomenological studies at the Tevatron and LHC
NLO predictions for a lepton, missing transverse momentum and dijets at the Tevatron
n this letter we investigate the various processes that can contribute to a
final state consisting of a lepton, missing transverse momentum and two jets at
Next to Leading Order (NLO) at the Tevatron. In particular we consider the
production of W/Z + 2 jets, diboson pairs, single top and the tt process with
both fully leptonic and semi-leptonic decays. We present distributions for the
invariant mass of the dijet system and normalisations of the various processes,
accurate to NLO.Comment: 4 pages, 5 figure
Hadronic production of a Higgs boson and two jets at next-to-leading order
We perform an update of the next-to-leading order calculation of the rate for
Higgs boson production in association with two jets. Our new calculation
incorporates the full analytic result for the one-loop virtual amplitude. This
new theoretical information allows us to construct a code including the decay
of the Higgs boson without incurring a prohibitive penalty in computer running
time. Results are presented for the Tevatron, where implications for the Higgs
search are sketched, and also for a range of scenarios at the LHC.Comment: 16 pages, 4 figure
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