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John F. Gunion

Publications and source records attributed to John F. Gunion.

At least 73 records · Page 4Linked to original sources
arXiv2003

The CP-conserving two-Higgs-doublet model: the approach to the decoupling limit

A CP-even neutral Higgs boson with Standard-Model-like couplings may be the lightest scalar of a two-Higgs-doublet model. We study the decoupling limit of the most general CP-conserving two-Higgs-doublet model, where the mass of the lightest Higgs scalar is significantly smaller than the masses of the other Higgs bosons of the model. In this case, the properties of the lightest Higgs boson are nearly indistinguishable from those of the Standard Model Higgs boson. The first non-trivial corrections to Higgs couplings in the approach to the decoupling limit are also evaluated. The importance of detecting such deviations in precision Higgs measurements at future colliders is emphasized. We also clarify the case in which a neutral Higgs boson can possess Standard-Model-like couplings in a regime where the decoupling limit does not apply. The two-Higgs-doublet sector of the minimal supersymmetric model illustrates many of the above features.

hep-ph↗
arXiv2002

Extended Higgs Sectors

I give a brief overview of the motivations for and experimental probes of extended Higgs sectors containing more than the single Higgs doublet field of the Standard Model.

hep-ph↗
arXiv2002

Detecting and Studying Higgs Bosons at a Photon-Photon Collider

We examine the potential for detecting and studying Higgs bosons at a photon-photon collider facility associated with a future linear collider. Our study incorporates realistic $\gam\gam$ luminosity spectra based on the most probable available laser technology. Results include detector simulations. We study the cases of: a) a SM-like Higgs boson; b) the heavy MSSM Higgs bosons; c) a Higgs boson with no $WW/ZZ$ couplings from a general two Higgs doublet model.

hep-ph↗
arXiv2002

Higgs-Boson Interactions within the Randall-Sundrum Model

The scalar sector of the Randall-Sundrum model is discussed. The effective potential for the Standard Model Higgs-boson (h) interacting with Kaluza-Klein excitations of the graviton and the radion (phi) has been derived and it has been shown that only the Standard Model-like vacuum is allowed. The theoretical and experimental consequences of the curvature-scalar mixing xi RHH introduced on the visible brane are considered and simple sum rules that relate the couplings of the mass eigenstates (h) and (phi) to pairs of vector bosons and fermions are derived. The sum rule for the ZZh and ZZ phi couplings in combination with LEP/LEP2 data implies that not both the h and phi can be light. We present explicit results for the still allowed region in the (mh,mphi) plane that remains after imposing the LEP upper limits for non-standard scalar couplings to a ZZ pair. The phenomenological consequences of the mixing are investigated and, in particular, it is shown that the Higgs-boson decay h -> phi phi would provide an experimental signature for non-zero xi and can have a very substantial impact on the Higgs-boson searches, having BR(h->phi phi) as large as 30 - 40 %.

hep-ph↗
arXiv2002

Higgs Sectors in which the only light Higgs boson is CP-odd and Linear Collider Strategies for its Discovery

We survey techniques for finding a CP-odd Higgs boson, A, at the Linear Collider that do not depend upon the presence of other light Higgs bosons. The potential reach in $[m_A,\tanβ]$ parameter space for various production/discovery modes is evaluated and regions where discovery might not be possible at a given $\sqrt{s}$ are delineated. We give, for the first time, results for $\epem\to ν\antiνA$ one-loop $W$ boson fusion production.

hep-ph↗
arXiv2001

Phenomenology of Generalized Higgs Boson Scenarios

I outline some of the challenging issues that could arise in attempting to fully delineate various possible Higgs sectors, with focus on the minimal supersymmetric model, a general two-Higgs-doublet model, and extensions thereof.

hep-ph↗
arXiv2001

Hunting the Higgs Boson(s)

I give a brief review of some of the opportunities and challenges that could arise in our quest to unravel the Higgs sector that very probably underlies electroweak symmetry breaking. In particular, I review scenarios with an extended Higgs sector that allow for a heavy SM-like Higgs boson and/or make discovery more difficult while at the same time maintaining consistency with current limits and precision electroweak constraints.

hep-ph↗
arXiv2000

Do precision electroweak constraints guarantee $\epem$ collider discovery of at least one Higgs boson of a type-II two-Higgs-doublet model?

The manner in which the parameters of a two-Higgs-doublet model can be chosen so that no Higgs boson is discovered at a $\sqrt{s}\leq 800\gev$ $\epem$ collider, while maintaining consistency with current precision electroweak measurements, is described. The importance of a Giga-$Z$ factory and higher collider energies for such a scenario is emphasized.

hep-ph↗
arXiv2000

Testing CP Violation in the Higgs Sector at Muon Colliders

We study the possibility of measuring the muon Yukawa couplings in s-channel Higgs boson production at a muon collider with transversely polarized beams. We investigate sensitivity to the relative size of the CP-odd and CP-even muon Yukawa couplings. Provided the event rate observed justifies the operation of the mu+mu- Higgs boson factory, we find that 40% polarization for both beams is sufficient to resolve the CP nature of a single resonance as well as disentangle it from two overlapping CP conserving resonances.

hep-ph↗
arXiv2000

Measuring the relative CP-even and CP-odd Yukawa couplings of a Higgs boson at a muon-collider Higgs factory

We study a possibility of a measurement of muon Yukawa couplings in s-channel Higgs boson production at a muon collider with transversely polarized beams. We investigate sensitivity to the relative size of the CP-odd and CP-even muon Yukawa couplings. Provided the event rate observed justify the operation of the $μ^+μ^-$ Higgs boson factory, we have found that polarization degree 40% is sufficient to resolve the CP nature of a single resonance as well as disentangle it from two overlapping CP conserving resonances.

hep-ph↗
arXiv1998

Low-Energy Supersymmetry at Future Colliders

We classify the variety of low-energy supersymmetric signatures that can be probed at future colliders. We focus on phenomena associated with the minimal supersymmetric extension of the Standard Model. The structure of the supersymmetry-breaking introduces additional model assumptions. The approaches considered here are supergravity-mediated and gauge-mediated supersymmetry-breaking. Alternative phenomenologies arising in non-minimal and/or R-parity-violating approaches are also briefly examined.

hep-ph↗
arXiv1998

Searching for Low-Energy Supersymmetry

A review of supersymmetry theory and phenomenology is presented. Topics discussed include: gravity-mediated (SUGRA) and gauge-mediated (GMSB) supersymmetry breaking models; an overview of non-universal soft-supersymmetry-breaking masses and the resulting experimental implications; the phenomenology of and constraints on the possibility that a massive gluino is the lightest supersymmetric particle; current status of the phenomenology of the Higgs bosons of the minimal and next-to-minimal supersymmetric models; and, the signals for GMSB and/or R-parity-violating models coming from delayed decays of the lightest supersymmetric partner of the Standard Model particles.

hep-ph↗
arXiv1993

Discovering Supersymmetry with Like-sign Dileptons

Supersymmetry may be discovered at hadron colliders by searching for events similar to the top quark signal of two isolated leptons. In the case of gluino production, the most distinguishing feature is that in half the events the two leading leptons have the same sign. We demonstrate the remarkable sensitivity of this gluino signature at both the Fermilab Tevatron Collider and at the Superconducting Super Collider. Techniques for approximately determining the gluino mass are discussed.

hep-ph↗
arXiv1993

Errata for "The Higgs Hunter's Guide"

Errata are given for "The Higgs Hunter's Guide". These errata should be applied to the second printing of the book, dated 1991. The second printing has already corrected numerous errors and misprints contained in the originally published 1990 edition.

hep-ph↗