scholarly journals Higgs-like spectator field as the origin of structure

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Alexandros Karam ◽  
Tommi Markkanen ◽  
Luca Marzola ◽  
Sami Nurmi ◽  
Martti Raidal ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Scalar Field ◽  
Standard Model ◽  
Direct Coupling ◽  
Quartic Potential ◽  
The Standard Model ◽  
The Spectator

AbstractWe show that the observed primordial perturbations can be entirely sourced by a light spectator scalar field with a quartic potential, akin to the Higgs boson, provided that the field is sufficiently displaced from vacuum during inflation. The framework relies on the indirect modulation of reheating, which is implemented without any direct coupling between the spectator field and the inflaton and does not require non-renormalisable interactions. The scenario gives rise to local non-Gaussianity with $$f_{\mathrm{NL}}\simeq 5$$ f NL ≃ 5 as the typical signal. As an example model where the indirect modulation mechanism is realised for the Higgs boson, we study the Standard Model extended with right-handed neutrinos. For the Standard Model running we find, however, that the scenario analysed does not seem to produce the observed perturbation.

scholarly journals Novel mechanism for primordial perturbations in minimal extensions of the Standard Model

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Alexandros Karam ◽  
Tommi Markkanen ◽  
Luca Marzola ◽  
Sami Nurmi ◽  
Martti Raidal ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Phase Space ◽  
Lower Bound ◽  
Standard Model ◽  
Quartic Coupling ◽  
Decay Products ◽  
Indirect Mechanism ◽  
The Standard Model ◽  
The Spectator ◽  
Eigenvalue Expansion

Abstract We demonstrate that light spectator fields in their equilibrium can source sizeable CMB anisotropies through modulated reheating even in the absence of direct couplings to the inflaton. The effect arises when the phase space of the inflaton decay is modulated by the spectator which generates masses for the decay products. We call the mechanism indirect modulation and using the stochastic eigenvalue expansion show that it can source perturbations even four orders of magnitude larger than the observed amplitude. Importantly, the indirect mechanism is present in the Standard Model extended with right- handed neutrinos. For a minimally coupled Higgs boson this leads to a novel lower bound on the quartic coupling and constrains the neutrino Yukawas below unity.

scholarly journals HIGGS BOSON AND WLWL SCATTERING AT e−e− COLLIDERS

1996 ◽  
Vol 11 (09) ◽  
pp. 1541-1550 ◽  
Author(s):  
TAO HAN
Keyword(s):  
Higgs Boson ◽  
Scalar Field ◽  
Standard Model ◽  
Cross Section ◽  
Field Model ◽  
Higgs Sector ◽  
Boson Production ◽  
Standard Model Higgs Boson ◽  
Higgs Boson Production ◽  
The Standard Model

We discuss the Standard-Model Higgs boson production in the channels e−e−→e−e−H, e−νW−H, and e−e−ZH. We also illustrate the enhancements in the W–W– cross section that would result from a strongly-interacting Higgs sector or from a H−− resonance in a doublet + triplet scalar field model.

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.

scholarly journals Search for dark photons in Higgs boson production via vector boson fusion in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
A. M. Sirunyan ◽  
◽  
A. Tumasyan ◽  
W. Adam ◽  
T. Bergauer ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Confidence Level ◽  
Branching Fraction ◽  
Vector Boson ◽  
Boson Mass ◽  
Higgs Boson Mass ◽  
Vector Boson Fusion ◽  
Upper Limit ◽  
The Standard Model

Abstract A search is presented for a Higgs boson that is produced via vector boson fusion and that decays to an undetected particle and an isolated photon. The search is performed by the CMS collaboration at the LHC, using a data set corresponding to an integrated luminosity of 130 fb−1, recorded at a center-of-mass energy of 13 TeV in 2016–2018. No significant excess of events above the expectation from the standard model background is found. The results are interpreted in the context of a theoretical model in which the undetected particle is a massless dark photon. An upper limit is set on the product of the cross section for production via vector boson fusion and the branching fraction for such a Higgs boson decay, as a function of the Higgs boson mass. For a Higgs boson mass of 125 GeV, assuming the standard model production rates, the observed (expected) 95% confidence level upper limit on the branching fraction is 3.5 (2.8)%. This is the first search for such decays in the vector boson fusion channel. Combination with a previous search for Higgs bosons produced in association with a Z boson results in an observed (expected) upper limit on the branching fraction of 2.9 (2.1)% at 95% confidence level.

scholarly journals A search for the dimuon decay of the Standard Model Higgs boson with the ATLAS detector

2021 ◽  
Vol 812 ◽  
pp. 135980
Author(s):  
G. Aad ◽  
B. Abbott ◽  
D.C. Abbott ◽  
A. Abed Abud ◽  
K. Abeling ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Atlas Detector ◽  
Standard Model Higgs Boson ◽  
The Standard Model

scholarly journals Indirect $$ \mathcal{CP} $$ probes of the Higgs-top-quark interaction: current LHC constraints and future opportunities

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Henning Bahl ◽  
Philip Bechtle ◽  
Sven Heinemeyer ◽  
Judith Katzy ◽  
Tobias Klingl ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Top Quark ◽  
Decay Channel ◽  
New Physics ◽  
Current Data ◽  
Quark Interaction ◽  
The Standard Model ◽  
Vector Bosons ◽  
Selection Of

Abstract The $$ \mathcal{CP} $$ CP structure of the Higgs boson in its coupling to the particles of the Standard Model is amongst the most important Higgs boson properties which have not yet been constrained with high precision. In this study, all relevant inclusive and differential Higgs boson measurements from the ATLAS and CMS experiments are used to constrain the $$ \mathcal{CP} $$ CP -nature of the top-Yukawa interaction. The model dependence of the constraints is studied by successively allowing for new physics contributions to the couplings of the Higgs boson to massive vector bosons, to photons, and to gluons. In the most general case, we find that the current data still permits a significant $$ \mathcal{CP} $$ CP -odd component in the top-Yukawa coupling. Furthermore, we explore the prospects to further constrain the $$ \mathcal{CP} $$ CP properties of this coupling with future LHC data by determining tH production rates independently from possible accompanying variations of the $$ t\overline{t}H $$ t t ¯ H rate. This is achieved via a careful selection of discriminating observables. At the HL-LHC, we find that evidence for tH production at the Standard Model rate can be achieved in the Higgs to diphoton decay channel alone.

scholarly journals Search for the Standard Model Higgs boson in e+e− collisions at up to 202 GeV

2001 ◽  
Vol 508 (3-4) ◽  
pp. 225-236 ◽  
Author(s):  
M. Acciarri ◽  
P. Achard ◽  
O. Adriani ◽  
M. Aguilar-Benitez ◽  
J. Alcaraz ◽  
...  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Standard Model Higgs Boson ◽  
The Standard Model

scholarly journals Production and decay of the Standard Model Higgs boson at LEP200

1994 ◽  
Vol 63 (3) ◽  
pp. 417-425 ◽  
Author(s):  
Eilam Gross ◽  
Bernd A. Kniehl ◽  
Gustavo Wolf
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Standard Model Higgs Boson ◽  
The Standard Model

The sircular polarization of γ-quanta in the radiative decay H Þ`ffγ (II)

2021 ◽  
pp. 134-141
Author(s):  
S.K. Abdullayev ◽  
◽  
E.Sh. Omarova ◽  
Keyword(s):  
Higgs Boson ◽  
Standard Model ◽  
Circular Polarization ◽  
Invariant Mass ◽  
Decay Width ◽  
Radiative Decay ◽  
W Boson ◽  
Decay Channel ◽  
Fermion Pair ◽  
The Standard Model

Within the framework of the Standard Model, the radiative decay channel of the Higgs boson into fermion-antifermion pair is investigated: H Þ` ff γ. Taking into account the fermion and W -boson loop diagrams an analytical expression for the decay width is obtained, the circular polarization of the γ-quanta is studied in dependence of the angle θ and invariant mass of the fermion pair.

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