scholarly journals Sensitivity to BSM effects in the Higgs pT spectrum within SMEFT

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Marco Battaglia ◽  
Massimiliano Grazzini ◽  
Michael Spira ◽  
Marius Wiesemann
Keyword(s):  
Top Quark ◽  
Gluon Fusion ◽  
Effective Field ◽  
Three Dimension ◽  
Linear Quadratic ◽  
Effective Coupling ◽  
Dipole Operator ◽  
The Standard Model ◽  
Light Scalar ◽  
Scalar Top

Abstract The study of Higgs boson production at large transverse momentum is one of the new frontiers for the LHC Higgs physics programme. This paper considers boosted Higgs production in the Standard Model Effective Field Theory (SMEFT). We focus on the gluon fusion and t$$ \overline{t} $$ t ¯ H production processes and study the effects of three dimension-6 operators: the top Yukawa operator, the gluon-Higgs effective coupling and the chromomagnetic dipole operator of the top quark. We perform a detailed study of the sensitivity of current and future LHC data to the corresponding Wilson coefficients, consistently accounting for their renormalisation group evolution. We compare the sensitivities obtained with only linear and linear + quadratic terms in the SMEFT by using the spectrum shape and the addition of the Higgs signal yields. We also consider fits of pT spectra in models with heavy-top partners and in MSSM scenarios with a light scalar top and study the validity of the SMEFT assumptions as a function of the new-particle masses and the Higgs pT range. Finally, we extract constraints on the Wilson coefficients for gluon fusion from a simultaneous fit to the ATLAS and CMS data and compare our results with those obtained in global SMEFT analyses.

SCALAR TOP PRODUCTION VIA BOSON-GLUON FUSION AT HERA

1992 ◽  
Vol 07 (14) ◽  
pp. 1209-1218 ◽  
Author(s):  
TETSURO KOBAYASHI ◽  
TADASHI KON ◽  
KEIICHIRO NAKAMURA ◽  
TAKESHI SUZUKI
Keyword(s):  
Total Cross Section ◽  
Cross Section ◽  
Top Quark ◽  
Gluon Fusion ◽  
Top Quarks ◽  
Tree Level ◽  
Mixing Angle ◽  
Light Scalar ◽  
Scalar Top ◽  
Level Calculation

We investigate the production of the light scalar top quark [Formula: see text] via boson-gluon fusion at ep collider HERA, based on the minimal supersymmetric standard model. The cross-section is obtained by both an exact tree level calculation and the Weizsäcker-Williams approximation. It is shown that the total cross-section is larger than 0.1pb if [Formula: see text] and does not depend on the mixing angle θt of scalar top quarks. This enables us to search a possible region of parameters for existence of light scalar top at HERA in a wider parameter space [Formula: see text] than LEP.

scholarly journals SMEFTsim 3.0 — a practical guide

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Ilaria Brivio
Keyword(s):  
Top Quark ◽  
Gluon Fusion ◽  
Effective Field ◽  
Monte Carlo Event ◽  
Quark Sector ◽  
Unstable Particles ◽  
Link Type ◽  
The Standard Model ◽  
Electroweak Sector ◽  
New Feature

Abstract The SMEFTsim package [1] is designed to enable automated computations in the Standard Model Effective Field Theory (SMEFT), where the SM Lagrangian is extended with a complete basis of dimension six operators. It contains a set of models written in FeynRules and pre-exported to the UFO format, for usage within Monte Carlo event generators. The models differ in the flavor assumptions and in the input parameters chosen for the electroweak sector. The present document provides a self-contained, pedagogical reference that collects all the theoretical and technical aspects relevant to the use of SMEFTsim and it documents the release of version 3.0. Compared to the previous release, the description of Higgs production via gluon-fusion in the SM has been significantly improved, two flavor assumptions for studies in the top quark sector have been added, and a new feature has been implemented, that enables the treatment of linearized SMEFT corrections to the propagators of unstable particles.SMEFTsim 3.0 is available on the Github website https://SMEFTsim.github.io and on the FeynRules database http://feynrules.irmp.ucl.ac.be/wiki/SMEFT.

Light scalar top quark ate+e−colliders

1987 ◽  
Vol 36 (3) ◽  
pp. 724-732 ◽  
Author(s):  
Ken-ichi Hikasa ◽  
Makoto Kobayashi
Keyword(s):  
Top Quark ◽  
Light Scalar ◽  
Scalar Top

scholarly journals Anomalous couplings in Higgs-boson pair production at approximate NNLO QCD

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Daniel de Florian ◽  
Ignacio Fabre ◽  
Gudrun Heinrich ◽  
Javier Mazzitelli ◽  
Ludovic Scyboz
Keyword(s):  
Higgs Boson ◽  
Pair Production ◽  
Top Quark ◽  
Gluon Fusion ◽  
Effective Field ◽  
Boson Pair ◽  
Anomalous Couplings ◽  
Boson Pair Production ◽  
Coupling Parameters ◽  
The Impact

Abstract We combine NLO predictions with full top-quark mass dependence with approximate NNLO predictions for Higgs-boson pair production in gluon fusion, including the possibility to vary coupling parameters within a non-linear Effective Field Theory framework containing five anomalous couplings for this process. We study the impact of the anomalous couplings on various observables, and present Higgs-pair invariant-mass distributions at seven benchmark points characterising different mhh shape types. We also provide numerical coefficients for the approximate NNLO cross section as a function of the anomalous couplings at $$ \sqrt{s} $$ s = 14 TeV.

scholarly journals Exclusion Limits on a Scalar Decaying to Photons and Distinguishing Its Production Mechanisms

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Tanumoy Mandal
Keyword(s):  
Cross Sections ◽  
Effective Field Theory ◽  
Gluon Fusion ◽  
Effective Field ◽  
Beyond The Standard Model ◽  
Theory Approach ◽  
The Standard Model ◽  
Resonance Search ◽  
Model Independent ◽  
Production Mechanisms

LHC run-II has a great potential to search for new resonances in the diphoton channel. Latest 13 TeV data already put stringent limits on the cross sections in the diphoton channel assuming the resonance is produced through the gluon-gluon fusion. Many beyond the Standard Model (SM) theories predict TeV-scale scalars, which copiously decay to diphotons. Apart from the gluon-gluon fusion production, these scalars can also be dominantly produced in other ways too at the LHC, namely, through the quark-quark fusion or the gauge boson fusions like the photon-photon, photon-Z, WW, or ZZ fusions. In this paper we use an effective field theory approach where a heavy scalar can be produced in various ways and recast the latest ATLAS diphoton resonance search to put model-independent limits on its mass and effective couplings to the SM particles. If a new scalar is discovered at the LHC, it would be very important to identify its production mechanism in order to probe the nature of the underlying theory. We show that combining various kinematic variables in a multivariate analysis can be very powerful to distinguish different production mechanisms from one another.

scholarly journals A Monte Carlo global analysis of the Standard Model Effective Field Theory: the top quark sector

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Nathan P. Hartland ◽  
Fabio Maltoni ◽  
Emanuele R. Nocera ◽  
Juan Rojo ◽  
Emma Slade ◽  
...  
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Standard Model ◽  
Effective Field Theory ◽  
Top Quark ◽  
Global Analysis ◽  
Effective Field ◽  
Quark Sector ◽  
The Standard Model

scholarly journals Gluon-fusion Higgs production in the Standard Model Effective Field Theory

2017 ◽  
Vol 2017 (12) ◽  
Author(s):  
Nicolas Deutschmann ◽  
Claude Duhr ◽  
Fabio Maltoni ◽  
Eleni Vryonidou
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Gluon Fusion ◽  
Effective Field ◽  
Higgs Production ◽  
The Standard Model

scholarly journals Non-relativistic and potential non-relativistic effective field theories for scalar mediators

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Simone Biondini ◽  
Vladyslav Shtabovenko
Keyword(s):  
Effective Field ◽  
Field Theories ◽  
Dirac Fermions ◽  
Full Generality ◽  
Relativistic Limit ◽  
Cosmological Observations ◽  
The Standard Model ◽  
Light Scalar ◽  
Model Independent ◽  
Yukawa Theory

Abstract Yukawa-type interactions between heavy Dirac fermions and a scalar field are a common ingredient in various extensions of the Standard Model. Despite of that, the non-relativistic limit of the scalar Yukawa theory has not yet been studied in full generality in a rigorous and model-independent way. In this paper we intend to fill this gap by initiating a series of investigations that make use of modern effective field theory (EFT) techniques. In particular, we aim at constructing suitable non-relativistic and potential non-relativistic EFTs of Yukawa interactions (denoted as NRY and pNRY respectively) in close analogy to the well known and phenomenologically successful non-relativistic QCD (NRQCD) and potential non-relativistic QCD (pNRQCD). The phenomenological motivation for our study lies in the possibility to explain the existing cosmological observations by introducing heavy fermionic dark matter particles that interact with each other by exchanging a light scalar mediator. A systematic study of this compelling scenario in the framework of non-relativistic EFTs (NREFTs) constitutes the main novelty of our approach as compared to the existing studies.

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