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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Probing Naturalness with Searches for Supersymmetric Higgs Partners at the Large Hadron Collider

The discovery of the Higgs boson at the Large Hadron Collider completed the standard model of particle physics and led to the 2013 Nobel Prize. While it has been extremely successful in describing a wide variety of phenomena, the standard model cannot be the final theory of nature because it is unable to explain why the Higgs boson mass lies at the electroweak scale rather than 16 orders of magnitude larger at the Planck scale, a theoretical flaw known as the ``hierarchy problem.'' Supersymmetry is a standard model extension that could provide a natural solution to the hierarchy problem by introducing light supersymmetric Higgs partners. This proposal focused on searches that are sensitive to supersymmetric Higgs partners in data collected by the ATLAS experiment, which were carried out by the University of Illinois high-energy physics group led by PI Ben Hooberman as part of his Department of Energy Early Career Research Program award from 2017-2023. The searches were complemented by improvements to particle identification algorithms and the ATLAS trigger system that extend the sensitivity of future supersymmetry searches.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2026

Study of Unboosted Higgs Pair Production with HH to bbWW Decay with the CMS experiment at the LHC

Measurement of the Higgs boson self-interaction through the production of Higgs boson (H) pairs is critical for understanding the shape of the Higgs potential and the stability of the universe. Higgs pair production (HH) where one H decays to b quarks (H to bb) and the other to hadronically decaying W bosons (H to WW*→qqqq) has a large branching fraction with the cost of high background from jets produced through quantum chromodynamics (QCD). While previous all-hadronic HH→bbWW analyses focused on the few percent of highly energetic HH events with collimated decay products, this first study of its kind targets the more challenging 95$\%$ of HH to bbWW* in which decay products can be reconstructed as separate jets providing sensitivity to a complementary region of phase space. This poster focuses on generator level measurements of the fractions of HH to bbWW* signal events are fully or partially reconstructed and what fraction are impacted by contamination from high momentum jets from initial or final state radiation. Partially reconstructed events are further classified according to whether the H to bb, H to WW*, or W to qq are fully reconstructed

Gillespie, Emma [U. Louisville]↗
DOE OSTI2010

Higgs Searches at the Tevatron

We present combined CDF and D0 searches for the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) Higgs boson using up to 6.7 fb$^{-1}$ of integrated luminosity from 1.96 TeV proton-antiproton collisions at the Tevatron. Specialized searches for Higgs bosons produced via gluon fusion, associated boson production, and vector boson fusion, decaying to $b\bar{b}$, $W^{+}W^{-}$, $\tau^{+}\tau^{-}$, and $\gamma\gamma$ are combined to produce 95\% CL upper limits on SM Higgs production as a function of mass. Current Tevatron limits are shown, including a new exclusion for SM Higgs masses between 158 and 175 GeV$/c^2$. We also present prospects for future sensitivity.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Charged and neutral Higgs bosons in final states with 6 bottom quarks

In extensions of two Higgs doublet models with vectorlike quarks, the decays of vectorlike quarks may be easily dominated by cascade decays through charged or neutral Higgs bosons leading to signatures with 6 top or bottom quarks. Since top quark decays also contain bottom quarks, the 6 bottom quarks in final states is a common signature to a large class of possible decay chains. We present a search strategy focusing on this final state and find the mass ranges of vectorlike quarks and Higgs bosons that can be explored at the Large Hadron Collider. Among other results the sensitivity to the charged Higgs boson, extending above 2 TeV, stands out when compared to models without vectorlike matter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Natural SM-like 126 GeV Higgs boson via nondecoupling D terms

Accommodating both a 126 GeV mass and standard model (SM)-like couplings for the Higgs has a fine-tuning price in supersymmetric models. Examples are the minimal supersymmetric standard model, in which SM-like couplings are natural, but raising the Higgs mass to 126 GeV requires a considerable tuning, and the nonminimal supersymmetric standard model, in which the situation is reversed: the Higgs is naturally heavier, but being SM-like requires some tuning. We show that models with nondecoupling D terms alleviate this tension—a 126 GeV SM-like Higgs comes out basically with no fine-tuning cost. In addition, the analysis of the fine-tuning of the extended gauge sector shows that naturalness requires the heavy gauge bosons to likely be within the reach of LHC run II.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS2020

An inflationary probe of cosmic Higgs switching

A scalar Higgs field can be repeatedly switched on and off when it couples to a classically oscillating scalar modulus field. The modulus flips the Higgs mass term between stable and tachyonic values. We study a cosmological scenario in which such repeated phase transitions occur during inflation. An irrelevant operator coupling the Higgs field to the inflaton can then imprint the pattern of phase transitions in the correlation functions of the inflaton. Using both numerical and analytic studies, we show that the inflaton 2-point function carries characteristic imprints of the modulus oscillation and its effect on the Higgs boson. We briefly remark on the potential observability of such patterns and how they might be distinguished from other dynamics in the early universe.

JiJi Fan↗
DOE OSTI2011

Higgs searches at the Tevatron

We report on the status of Higgs boson searches at the Tevatron collider as of summer 2011. CDF and DØ perform Higgs searches in numerous final states corresponding to different potential production and decay modes of the Higgs in the context of both standard model (SM) production and other theoretical models. Based on current datasets we observe no excesses consistent with a Higgs signal and proceed to set upper limits on the potential production rate. For SM production we are able to exclude the 100-109 GeV/c2 and 156-177 GeV/c2 mass ranges at 95% C.L. Prospects for Tevatron search sensitivities using the full 10 fb-1 datsets are also discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Higgs Physics at the HL-LHC and HE-LHC

The discovery of the Higgs boson in 2012, by the ATLAS and CMS experiments, was a success achieved with only a percent of the entire dataset foreseen for the LHC. It opened a landscape of possibilities in the study of Higgs boson properties, Electroweak Symmetry breaking and the Standard Model in general, as well as new avenues in probing new physics beyond the Standard Model. Six years after the discovery, with a conspicuously larger dataset collected during LHC Run 2 at a 13 TeV centre-of-mass energy, the theory and experimental particle physics communities have started a meticulous exploration of the potential for precision measurements of its properties. This includes studies of Higgs boson production and decays processes, the search for rare decays and production modes, high energy observables, and searches for an extended electroweak symmetry breaking sector. This report summarises the potential reach and opportunities in Higgs physics during the High Luminosity phase of the LHC, with an expected dataset of pp collisions at 14 TeV, corresponding to an integrated luminosity of 3~ab$^{-1}$. These studies are performed in light of the most recent analyses from LHC collaborations and the latest theoretical developments. The potential of an LHC upgrade, colliding protons at a centre-of-mass energy of 27 TeV and producing a dataset corresponding to an integrated luminosity of 15~ab$^{-1}$, is also discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

The Gold-Plated Channel for Supersymmetric Higgs via Higgsphilic Z'

The lightest CP-even Higgs boson in weak-scale supersymmetry can be discovered spectacularly early, even from 1 inverse fb of data at 7 TeV LHC, if it decays to a pair of light Z', which in turn, decays to a pair of hard and 'isolated' leptons. These Z' must have infinitesimal couplings to light fermions in order to be consistent with precision electroweak constraints, while they have mild to moderate couplings to Higgs. Hence they are Higgsphilic. A Z' with these properties appears at the electroweak scale in the 'viable' gravity mediated supersymmetry breaking. We construct an effective model to extract the Z' phenomenology. Even in a decoupled limit where all gauginos and sfermions are heavy and supersymmetry production is purely electroweak, we find that the Higgs boson as well as supersymmetry can be found early through the discovery of Z' in samples of events with 4 leptons and 4 leptons + missing energy respectively. Additionally, in cases where the Z' is long-lived, we show that the trigger menus employed at the ATLAS detector to find long lived particles are capable of finding thousands of Higgs events from 1 inverse fb of data.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Combined CDF and D0 Upper Limits on Fermiophobic Higgs Boson Production with up to 8.2 fb$^{-1}$ of $p\bar{p}$ data

We combine the results of searches by the CDF and D0 collaborations for a fermiophobic Higgs boson (H_f) produced via the processes WH_f, ZH_f, and vector-boson fusion in ppbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron collider. The analyses seek Higgs boson decays to W^+W^- and gamma gamma. With up to 8.2 fb-1 of integrated luminosity analyzed at CDF and up to 8.2 fb-1 at D0, we obtain a 95% CL lower bound on the mass of the Higgs boson in the fermiophobic Higgs model of 119 GeV/c^2.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Highlights of Current Higgs Boson Searches

Over the last years the Tevatron Run-II has extended several limits on Higgs boson masses and coupling which were pioneered during the LEP accelerator operation between 1989 and 2000. Higgs boson searches will also be at the forefront of research at the LHC. This review concisely discusses the experimental constraints set by the CDF and D0 collaborations in summer 2010 at the beginning of the LHC era. Model-independent and model-dependent limits on Higgs boson masses and couplings have been set and interpretations are discussed both in the Standard Model and in extended models. Recently, the Tevatron has extended the excluded SM Higgs boson mass range (158-175 GeV) beyond the LEP limit at 95% CL. The experimental sensitivities are estimated for the completion of the Tevatron programme.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Constraints on standard model effective field theory for a Higgs boson produced in association with W or Z bosons in the H → $\textrm{b}\overline{\textrm{b}}$ decay channel in proton-proton collisions at $\sqrt{s}$ = 13 TeV

A standard model effective field theory (SMEFT) analysis with dimension-six operators probing nonresonant new physics effects is performed in the Higgs-strahlung process, where the Higgs boson is produced in association with a W or Z boson, in proton-proton collisions at a center-of-mass energy of 13 TeV. The final states in which the W or Z boson decays leptonically and the Higgs boson decays to a pair of bottom quarks are considered. The analyzed data were collected by the CMS experiment between 2016 and 2018 and correspond to an integrated luminosity of 138 fb −1 . An approach designed to simultaneously optimize the sensitivity to Wilson coefficients of multiple SMEFT operators is employed. Likelihood scans as functions of the Wilson coefficients that carry SMEFT sensitivity in this final state are performed for different expansions in SMEFT. The results are consistent with the predictions of the standard model.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

The one and a half monopoles solution of the SU(2) Yang–Mills–Higgs field theory

Recently we have reported on the existence of finite energy SU(2) Yang–Mills–Higgs particle of one-half topological charge. In this paper, we show that this one-half monopole can co-exist with a ’t Hooft–Polyakov monopole. The magnetic charge of the one-half monopole is of opposite sign to the magnetic charge of the ’t Hooft–Polyakov monopole. However the net magnetic charge of the configuration is zero due to the presence of a semi-infinite Dirac string along the positive z-axis that carries the other half of the magnetic monopole charge. The solution possesses gauge potentials that are singular along the z-axis, elsewhere they are regular. The total energy is found to increase with the strength of the Higgs field self-coupling constant λ. However the dipole separation and the magnetic dipole moment decrease with λ. This solution is non-BPS even in the BPS limit when the Higgs self-coupling constant vanishes. -- Highlights: •This one-half monopole can co-exist with a ’t Hooft–Polyakov monopole. •The magnetic charge of the one-half monopole and one monopole is of opposite sign. •This solution is non-BPS. •The net magnetic charge of the configuration is zero. •This solution upon Cho decomposition is only singular along the negative z-axis.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

The spectrum of an SU(3) gauge theory with a fundamental Higgs field

In gauge theories, the physical, experimentally observable spectrum consists only of gauge-invariant states. This spectrum can be different from the elementary spectrum even at weak coupling and in the presence of the Brout–Englert–Higgs effect. We demonstrate this for an SU(3) gauge theory with a single fundamental Higgs, a toy theory for grand-unified theories. The manifestly gauge-invariant approach of lattice gauge theory is used to determine the spectrum in four different channels. It is found to be qualitatively different from the elementary one, and especially from the one predicted by standard perturbation theory. The result can be understood in terms of the Fröhlich–Morchio–Strocchi mechanism. In fact, we find that analytic methods based on this mechanism, a gauge-invariant extension of perturbation theory, correctly determine the spectrum, and give already at leading order a reasonably good quantitative description. Together with previous results this supports that this approach is the analytic method of choice for theories with a Brout–Englert–Higgs effect.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Single and Central Diffractive Higgs Production at the LHC

The single and central diffractive production of the Standard Model Higgs boson is computed using the diffractive factorization formalism, taking into account a parametrization for the Pomeron structure function provided by the H1 Collaboration. We compute the cross sections at NLO accuracy for the gluon fusion process, since it is the leading mechanism for the Higgs boson production. The gap survival probability is also introduced to include the rescattering corrections due to spectator particles present in the interaction. The diffractive ratios are predicted for proton-proton collisions at the LHC, since the beam luminosity is favorable to the Higgs boson detection. These results provide updated estimations for the fraction of single and central diffractive events in the LHC kinematical regime.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

Search for the MSSM Higgs boson in pp̄ collisions at DO/

We present searches for Higgs bosons (φ) in the framework of MSSM models using up to 7.3 fb{sup −1} of data collected with the DO/ detector in proton-antiproton collisions at a center of mass energy of 1.96 TeV at the Fermilab Tevatron collider. In addition, we discuss searches for doubly-charged Higgs bosons and fermiophobic Higgs bosons.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Recent Higgs results from the ATLAS experiment

This paper presents recent results on the Higgs boson from the ATLAS experiment at the Large Hadron Collider. The Collaboration reports on measurements of the signal strength, couplings, and spin of the Higgs in several decay channels. We find all measurements to be consistent with Standard Model predictions. The Higgs branching fraction to invisible particles is constrained and no evidence of physics beyond the Standard Model is found.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Natural SUSY and the Higgs boson

Supersymmetry (SUSY) solves the hierarchy problem by introducing a super partner to each Standard Model(SM) particle. SUSY must be broken in nature, which means the fine-tuning is reintroduced to some level. Natural SUSY models enjoy low fine-tuning by featuring a small super potential parameter μ ~ 125 GeV, while the third generation squarks have mass less than 1.5 TeV. First and second generation sfermions can be at the multi-TeV level which yields a decoupling solution to the SUSY flavor and CP problem. However, models of Natural SUSY have difficulties in predicting a m{sub h} at 125 GeV, because the third generation is too light to give large radiative correction to the Higgs mass. The models of Radiative Natural SUSY (RNS) address this problem by allowing for high scale soft SUSY breaking Higgs mass m{sub Hu} > m{sub 0}, which leads to automatic cancellation by the Renormalization Group (RG) running effect. Coupled with the large mixing in the stop sector, RNS allows low fine-tuning at 3-10 % level and a 125 GeV SM-like Higgs. RNS can be reached at the LHC, and a linear collider. If the strong CP problem is solved by the Peccei-Quinn mechanism, then RNS accommodates mixed axion-Higgsino cold dark matter, where the Higgsino-like WIMPs, which in this case make up only a fraction of the relic abundance, can be detectable at future WIMP detectors.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗