Weak radiative decays of the B mesons belong to the most important flavor changing processes that provide constraints on physics at the TeV scale. In the derivation of such constraints, accurate ...standard model predictions for the inclusive branching ratios play a crucial role. In the current Letter we present an update of these predictions, incorporating all our results for the O(α_{s}^{2}) and lower-order perturbative corrections that have been calculated after 2006. New estimates of nonperturbative effects are taken into account, too. For the CP- and isospin-averaged branching ratios, we find B_{sγ}=(3.36±0.23)×10^{-4} and B_{dγ}=(1.73_{-0.22}^{+0.12})×10^{-5}, for E_{γ}>1.6 GeV. Both results remain in agreement with the current experimental averages. Normalizing their sum to the inclusive semileptonic branching ratio, we obtain R_{γ}≡(B_{sγ}+B_{dγ})/B_{cℓν}=(3.31±0.22)×10^{-3}. A new bound from B_{sγ} on the charged Higgs boson mass in the two-Higgs-doublet-model II reads M_{H^{±}}>480 GeV at 95% C.L.
samurai
is a tool for the automated numerical evaluation of one-loop corrections to any scattering amplitudes within the dimensional-regularization scheme. It is based on the decomposition of the ...integrand according to the OPP -approach, extended to accommodate an implementation of the generalized
d
-dimensional unitarity-cuts technique, and uses a polynomial interpolation exploiting the Discrete Fourier Transform.
samurai
can process integrands written either as numerator of Feynman diagrams or as product of tree-level amplitudes. We discuss some applications, among which the 6-and 8-photon scattering in QED, and the 6-quark scattering in QCD.
samurai
has been implemented as a
Fortran90
library, publicly available, and it could be a useful module for the systematic evaluation of the virtual corrections oriented towards automating next-to-leading order calculations relevant for the LHC phenomenology.
We report on the calculation of the cross section for Higgs boson production in association with three jets via gluon fusion, at next-to-leading-order (NLO) accuracy in QCD, in the infinite top-mass ...approximation. After including the complete NLO QCD corrections, we observe a strong reduction in the scale dependence of the result, and an increased steepness in the transverse momentum distributions of both the Higgs boson and the leading jets. The results are obtained with the combined use of GOSAM, SHERPA, and the MADDIPOLE-MADEVENT framework.
We present a new approach to the reduction of one-loop amplitudes obtained by reconstructing the tensorial expression of the scattering amplitudes. The reconstruction is performed at the integrand ...level by means of a sampling in the integration momentum. There are several interesting applications of this novel method within existing techniques for the reduction of one-loop multi-leg amplitudes: to deal with numerically unstable points, such as in the vicinity of a vanishing Gram determinant; to allow for a sampling of the numerator function based on real values of the integration momentum; to optimize the numerical reduction in the case of long expressions for the numerator functions.
We present the full NLO QCD corrections to the production of a W+W− pair in association with two jets in hadronic collisions, which is an important background to New Physics and Higgs boson searches. ...We include leptonic decays of the W-bosons with full spin correlations. We find NLO corrections of the order of 10% for standard cuts at the LHC. The scale dependence is considerably reduced by the NLO corrections.
We present the calculation of the cross section for Higgs boson production in association with a top quark pair plus one jet, at next-to-leading-order accuracy in QCD. All mass dependence is retained ...without recurring to any approximation. After including the complete next-to-leading-order QCD corrections, we observe a strong reduction in the scale dependence of the result. We also show distributions for the invariant mass of the top quark pair, with and without the additional jet, and for the transverse momentum and the pseudorapidity of the Higgs boson. Results for the virtual contributions are obtained with a novel reduction approach based on integrand decomposition via the Laurent expansion, as implemented in the library, NINJA. Cross sections and differential distributions are obtained with an automated setup which combines the GOSAM and SHERPA frameworks.
We present the calculation of the NLO QCD corrections to the associated production of a Higgs boson and two jets, in the infinite top-mass limit. We discuss the technical details of the computation ...and we show the numerical impact of the radiative corrections on several observables at the LHC. The results are obtained by using a fully automated framework for fixed order NLO QCD calculations based on the interplay of the packages GoSam and Sherpa. The evaluation of the virtual corrections constitutes an application of the d-dimensional integrand-level reduction to theories with higher dimensional operators. We also present first results for the one-loop matrix elements of the partonic processes with a quark-pair in the final state, which enter the hadronic production of a Higgs boson together with three jets in the infinite top-mass approximation.
Theory for muon-electron scattering @ 10 ppm Banerjee, P; Carloni Calame, C. M; Chiesa, M ...
The European physical journal. C, Particles and fields,
06/2020, Letnik:
80, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We review the current status of the theory predictions for elastic Formula omitted-e scattering, describing the recent activities and future plans of the theory initiative related to the proposed ...MUonE experiment.
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