scholarly journals INADEQUACY OF ZERO-WIDTH APPROXIMATION FOR A LIGHT HIGGS BOSON SIGNAL

2013 ◽  
Vol 28 (20) ◽  
pp. 1330015 ◽  
Author(s):  
NIKOLAS KAUER
Keyword(s):  
Higgs Boson ◽  
Higgs Mass ◽  
Gluon Fusion ◽  
Unstable Particle ◽  
Particle State ◽  
Light Higgs Boson ◽  
Decay Modes ◽  
Precision Level ◽  
Signal Normalization ◽  
Higgs Signal

The zero-width approximation (ZWA) restricts the intermediate unstable particle state to the mass shell and, when combined with the decorrelation approximation, fully factorizes the production and decay of unstable particles. The ZWA uncertainty is expected to be of [Formula: see text], where M and Γ are the mass and width of the unstable particle. We review the ZWA and demonstrate that errors can be much larger than expected if a significant modification of the Breit–Wigner lineshape occurs. A thorough examination of the recently discovered candidate Standard Model Higgs boson is in progress. For MH≈125 GeV, one has ΓH/MH < 10-4, which suggests an excellent accuracy of the ZWA. We show that this is not always the case. The inclusion of off-shell contributions is essential to obtain an accurate Higgs signal normalization at the 1% precision level. For gg→H→VV, V = W, Z, [Formula: see text] corrections occur due to an enhanced Higgs signal in the region MVV > 2MV, where also sizable Higgs-continuum interference occurs. We discuss how experimental selection cuts can be used to suppress this region in search channels where the Higgs mass cannot be reconstructed. We note that H→VV decay modes in non-gluon-fusion channels are similarly affected.

scholarly journals INVESTIGATIONS OF ELECTROWEAK SYMMETRY BREAKING MECHANISM FOR HIGGS BOSON DECAYS INTO FOUR FERMIONS

2020 ◽  
pp. 8-12
Author(s):  
T.V. Obikhod ◽  
E.A. Petrenko
Keyword(s):  
Higgs Boson ◽  
Symmetry Breaking ◽  
Gluon Fusion ◽  
Higgs Doublet ◽  
Electroweak Symmetry Breaking ◽  
Electroweak Symmetry ◽  
Decay Modes ◽  
Significant Difference ◽  
Vector Bosons ◽  
Breaking Mechanism

Models with extended Higgs boson sectors are of prime importance for investigating the mechanism of electroweak symmetry breaking for Higgs decays into four fermions and for Higgs-production in association with a vector bosons. In the framework of the Two-Higgs-Doublet Model using two scenarios obtained from the experimental measurements we presented next-to-leading-order results on the four-fermion decays of light CP-even Higgs boson, h → 4f. With the help of Monte Carlo program Prophecy 4f 3.0, we calculated the values Γ = ΓEW/(ΓEW + ΓSM) and Γ = ΓEW+QCD/(ΓEW+QCD + ΓSM) for Higgs boson decay channels H → νµµeνe, µµee, eeee. We didn’t find significant difference when accounting QCD corrections to EW processes in the decay modes of Higgs boson. Using computer programs Pythia 8.2 and FeynHiggs we calculated the following values: σ(V BH)BR(H → ZZ) and σ(V BF)BR(H → WW) for VBF production processes, σ(ggH)BR(H → WW) and σ(ggH)BR(H → ZZ) for gluon fusion production process at 13 and 14 TeV and found good agreement with experimental data.

scholarly journals Review of physics results from the Tevatron: Higgs boson physics

2015 ◽  
Vol 30 (06) ◽  
pp. 1541006 ◽  
Author(s):  
Thomas R. Junk ◽  
Aurelio Juste
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Vector Boson ◽  
Branching Ratio ◽  
Gluon Fusion ◽  
Mass Range ◽  
Higgs Bosons ◽  
Boson Mass ◽  
Decay Modes ◽  
The Standard Model

We review the techniques and results of the searches for the Higgs boson performed by the two Tevatron collaborations, CDF and DØ. The Higgs boson predicted by the Standard Model was sought in the mass range 90 GeV < mH < 200 GeV in all main production modes at the Tevatron: gluon–gluon fusion, WH and ZH associated production, vector boson fusion, and [Formula: see text] production, and in five main decay modes: [Formula: see text], H→τ+τ-, H→WW(*), H→ZZ(*) and H→γγ. An excess of events was seen in the [Formula: see text] searches consistent with a Standard Model Higgs boson with a mass in the range 115 GeV < mH < 135 GeV . Assuming a Higgs boson mass of mH = 125 GeV , studies of Higgs boson properties were performed, including measurements of the product of the cross section times the branching ratio in various production and decay modes, constraints on Higgs boson couplings to fermions and vector bosons, and tests of spin and parity. We also summarize the results of searches for supersymmetric Higgs bosons, and Higgs bosons in other extensions of the Standard Model.

scholarly journals Boosting invisible Higgs boson searches by tagging a gluon jet for the gluon fusion process

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Won Sang Cho ◽  
Hyung Do Kim ◽  
Dongsub Lee
Keyword(s):  
Higgs Boson ◽  
Gluon Fusion ◽  
Fusion Process

scholarly journals The LHC Higgs boson discovery: Implications for Finite Unified Theories

2014 ◽  
Vol 29 (18) ◽  
pp. 1430032 ◽  
Author(s):  
S. Heinemeyer ◽  
M. Mondragón ◽  
G. Zoupanos
Keyword(s):  
Higgs Boson ◽  
Predictive Power ◽  
Low Energy ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Light Higgs Boson ◽  
Quark Masses ◽  
Grand Unified Theories ◽  
Unified Theories ◽  
Discovery Potential

Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories (GUTs) which can be made finite to all-loop orders, based on the principle of reduction of couplings, and therefore are provided with a large predictive power. We confront the predictions of an SU(5) FUT with the top and bottom quark masses and other low-energy experimental constraints, resulting in a relatively heavy SUSY spectrum, naturally consistent with the nonobservation of those particles at the LHC. The light Higgs boson mass is automatically predicted in the range compatible with the Higgs discovery at the LHC. Requiring a light Higgs boson mass in the precise range of Mh= 125.6 ±2.1 GeV favors the lower part of the allowed spectrum, resulting in clear predictions for the discovery potential at current and future pp, as well as future e+e-colliders.

scholarly journals Higgs boson production via gluon fusion: Squark loops at NLO QCD

2008 ◽  
Vol 790 (1-2) ◽  
pp. 1-27 ◽  
Author(s):  
Margarete Mühlleitner ◽  
Michael Spira
Keyword(s):  
Higgs Boson ◽  
Gluon Fusion ◽  
Boson Production ◽  
Higgs Boson Production

scholarly journals Radiative Corrections toMhfrom Three Generations of Majorana Neutrinos and Sneutrinos

2015 ◽  
Vol 2015 ◽  
pp. 1-26 ◽  
Author(s):  
S. Heinemeyer ◽  
J. Hernandez-Garcia ◽  
M. J. Herrero ◽  
X. Marcano ◽  
A. M. Rodriguez-Sanchez
Keyword(s):  
Higgs Boson ◽  
Higgs Mass ◽  
Critical Discussion ◽  
Full Detail ◽  
Neutrino Masses ◽  
Type I ◽  
Radiative Corrections ◽  
Seesaw Mechanism ◽  
Three Generations ◽  
Majorana Neutrinos

We study the radiative corrections to the mass of the lightest Higgs boson of the MSSM from three generations of Majorana neutrinos and sneutrinos. The spectrum of the MSSM is augmented by three right handed neutrinos and their supersymmetric partners. A seesaw mechanism of type I is used to generate the physical neutrino masses and oscillations that we require to be in agreement with present neutrino data. We present a full one-loop computation of these Higgs mass corrections and analyze in full detail their numerical size in terms of both the MSSM and the new (s)neutrino parameters. A critical discussion on the different possible renormalization schemes and their implications, in particular concerning decoupling, is included.

scholarly journals Two-loop $$ \mathcal{O} $$((αt + αλ + ακ)2) corrections to the Higgs boson masses in the CP-violating NMSSM

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Thi Nhung Dao ◽  
Martin Gabelmann ◽  
Margarete Mühlleitner ◽  
Heidi Rzehak
Keyword(s):  
Higgs Boson ◽  
Higgs Mass ◽  
Goldstone Boson ◽  
Higgs Sector ◽  
Momentum Dependence ◽  
Loop Order ◽  
Fortran Code ◽  
Higher Order Corrections ◽  
Infrared Divergences ◽  
The Impact

Abstract We present our computation of the $$ \mathcal{O} $$ O ((αt + αλ + ακ)2) two-loop corrections to the Higgs boson masses of the CP-violating Next-to-Minimal Supersymmetric Standard Model (NMSSM) using the Feynman-diagrammatic approach in the gaugeless limit at vanishing external momentum. We choose a mixed $$ \overline{\mathrm{DR}} $$ DR ¯ -on-shell (OS) renormalisation scheme for the Higgs sector and apply both $$ \overline{\mathrm{DR}} $$ DR ¯ and OS renormalisation in the top/stop sector. For the treatment of the infrared divergences we apply and compare three different regularisation methods: the introduction of a regulator mass, the application of a small momentum expansion, and the inclusion of the full momentum dependence. Our new corrections have been implemented in the Fortran code NMSSMCALC that computes the Higgs mass spectrum of the CP-conserving and CP-violating NMSSM as well as the Higgs boson decays including the state-of-the-art higher-order corrections. Our numerical analysis shows that the newly computed corrections increase with rising λ and κ, remaining overall below about 3% compared to our previously computed $$ \mathcal{O} $$ O (αt(αt + αs)) corrections, in the region compatible with perturbativity below the GUT scale. The renormalisation scheme and scale dependence is of typical two-loop order. The impact of the CP-violating phases in the new corrections is small. We furthermore show that the Goldstone Boson Catastrophe due to the infrared divergences can be treated in a numerically efficient way by introducing a regulator mass that approximates the momentum-dependent results best for squared mass values in the permille range of the squared renormalisation scale. Our results mark another step forward in the program of increasing the precision in the NMSSM Higgs boson observables.

scholarly journals Fiducial cross sections for the lepton-pair-plus-photon decay mode in Higgs production up to NNLO QCD

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
X. Chen ◽  
T. Gehrmann ◽  
E. W. N. Glover ◽  
A. Huss
Keyword(s):  
Higgs Boson ◽  
Decay Mode ◽  
Cross Sections ◽  
Gluon Fusion ◽  
Lepton Pair ◽  
Distinctive Features ◽  
Photon Decay ◽  
Higgs Decay ◽  
Decay Products ◽  
Three Body

Abstract The rare three-body decay of a Higgs boson to a lepton-antilepton pair and a photon is starting to become experimentally accessible at the LHC. We investigate how higher-order QCD corrections to the dominant gluon-fusion production process impact on the fiducial cross sections in this specific Higgs decay mode for electrons and muons. Corrections up to NNLO QCD are found to be sizeable. They are generally uniform in kinematical variables related to the Higgs boson, but display several distinctive features in the kinematics of its individual decay products.

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