scholarly journals Fully exclusive heavy quark-antiquark pair production from a colourless initial state at NNLO in QCD

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Gábor Somogyi ◽  
Francesco Tramontano
Keyword(s):  
Bottom Quarks ◽  
Standard Model Higgs Boson ◽  
Leading Order ◽  
Initial State ◽  
Order Accuracy ◽  
Massive Quark ◽  
Subtraction Scheme ◽  
Fully Differential ◽  
The Standard Model ◽  
Analytic Expressions

Abstract We present a local subtraction scheme for computing next-to-next-to-leading order QCD corrections to the production of a massive quark-antiquark pair from a colourless initial state. The subtraction terms are built following the CoLoRFulNNLO method and refined in such a way that their integration gives rise to compact, fully analytic expressions. All ingredients necessary for a numerical implementation of our subtraction scheme are provided in detail. As an example, we calculate the fully differential decay rate of the Standard Model Higgs boson to massive bottom quarks at next-to-next-to-leading order accuracy in perturbative QCD.

scholarly journals Dual subtractions

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Renato Maria Prisco ◽  
Francesco Tramontano
Keyword(s):  
Field Theory ◽  
Quantum Field ◽  
Matrix Elements ◽  
Leading Order ◽  
Initial State ◽  
Final State ◽  
Dual Representation ◽  
Subtraction Scheme ◽  
Theoretical Predictions ◽  
Perturbative Quantum

Abstract We propose a novel local subtraction scheme for the computation of Next-to-Leading Order contributions to theoretical predictions for scattering processes in perturbative Quantum Field Theory. With respect to well known schemes proposed since many years that build upon the analysis of the real radiation matrix elements, our construction starts from the loop diagrams and exploits their dual representation. Our scheme implements exact phase space factorization, handles final state as well as initial state singularities and is suitable for both massless and massive particles.

scholarly journals Search for the standard model Higgs boson produced in association with aWor aZboson and decaying to bottom quarks

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
S. Chatrchyan ◽  
V. Khachatryan ◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Bottom Quarks ◽  
Standard Model Higgs Boson ◽  
The Standard Model

scholarly journals Search for the standard model Higgs boson decaying to bottom quarks in pp collisions at s=7 TeV

2012 ◽  
Vol 710 (2) ◽  
pp. 284-306 ◽  
Author(s):  
S. Chatrchyan ◽  
V. Khachatryan ◽  
A.M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Bottom Quarks ◽  
Standard Model Higgs Boson ◽  
Pp Collisions ◽  
Higgs Boson Decaying ◽  
The Standard Model

scholarly journals Improving the theoretical prediction for the Bs - B̅s width difference: matrix elements of next-to-leading order ΔB = 2 operators

2018 ◽  
Vol 175 ◽  
pp. 13023 ◽  
Author(s):  
Christine Davies ◽  
Judd Harrison ◽  
G Peter Lepage ◽  
Christopher Monahan ◽  
Junko Shigemitsu ◽  
...  
Keyword(s):  
Standard Model Prediction ◽  
Bottom Quarks ◽  
Matrix Elements ◽  
Leading Order ◽  
Physical Point ◽  
Difference Matrix ◽  
Strange Quarks ◽  
Width Difference ◽  
The Standard Model ◽  
The Matrix

We present lattice QCD results for the matrix elements of R2 and other dimension-7, ΔB = 2 operators relevant for calculations of Δs, the Bs - B̅s width difference. We have computed correlation functions using 5 ensembles of the MILC Collaboration’s 2+1 + 1-flavour gauge field configurations, spanning 3 lattice spacings and light sea quarks masses down to the physical point. The HISQ action is used for the valence strange quarks, and the NRQCD action is used for the bottom quarks. Once our analysis is complete, the theoretical uncertainty in the Standard Model prediction for ΔΓs will be substantially reduced.

scholarly journals Complete leading-order standard model corrections to quantum leptogenesis

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Paul Frederik Depta ◽  
Andreas Halsch ◽  
Janine Hütig ◽  
Sebastian Mendizabal ◽  
Owe Philipsen
Keyword(s):  
Standard Model ◽  
Gauge Coupling ◽  
Thermal Bath ◽  
Leading Order ◽  
Boltzmann Equations ◽  
The Standard Model ◽  
Majorana Neutrinos ◽  
Infinite Loop ◽  
First Time ◽  
The Universe

Abstract Thermal leptogenesis, in the framework of the standard model with three additional heavy Majorana neutrinos, provides an attractive scenario to explain the observed baryon asymmetry in the universe. It is based on the out-of-equilibrium decay of Majorana neutrinos in a thermal bath of standard model particles, which in a fully quantum field theoretical formalism is obtained by solving Kadanoff-Baym equations. So far, the leading two-loop contributions from leptons and Higgs particles are included, but not yet gauge corrections. These enter at three-loop level but, in certain kinematical regimes, require a resummation to infinite loop order for a result to leading order in the gauge coupling. In this work, we apply such a resummation to the calculation of the lepton number density. The full result for the simplest “vanilla leptogenesis” scenario is by $$ \mathcal{O} $$ O (1) increased compared to that of quantum Boltzmann equations, and for the first time permits an estimate of all theoretical uncertainties. This step completes the quantum theory of leptogenesis and forms the basis for quantitative evaluations, as well as extensions to other scenarios.

scholarly journals Search for π0 decays to invisible particles

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
E. Cortina Gil ◽  
◽  
A. Kleimenova ◽  
E. Minucci ◽  
S. Padolski ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Ratio ◽  
Standard Model Higgs Boson ◽  
Scalar Mixing ◽  
Upper Limit ◽  
Upper Limits ◽  
The Standard Model ◽  
Model Independent

Abstract The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 109 tagged π0 mesons from K+ → π+π0(γ), searching for the decay of the π0 to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4.4 × 10−9 is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay K+ → π+X, where X is a particle escaping detection with mass in the range 0.110–0.155 GeV/c2 and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming X to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.

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