9,991 research outputs found
Will at least one of the Higgs bosons of the next-to-minimal supersymmetric extension of the Standard Model be observable at LEP2 or the LHC?
We demonstrate that there are regions of parameter space in the
next-to-minimal (i.e. two-Higgs-doublet, one-Higgs-singlet superfield)
supersymmetric extension of the SM for which none of the Higgs bosons are
observable either at LEP2 with and an integrated luminosity
of or at the LHC with .Comment: 6 pages, full postscript file also available via anonymous ftp at
ftp://ucdhep.ucdavis.edu/gunion/nmssm_sm96.ps To appear in ``Proceedings of
the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics'
Radio Frequency Interference /RFI/ design guide for aerospace communications systems
Radio frequency interference design guide for aerospace communications system
Mass-degenerate Higgs bosons at 125 GeV in the Two-Higgs-Doublet Model
The analysis of the Higgs boson data by the ATLAS and CMS Collaborations
appears to exhibit an excess of h --> gamma\gamma events above the Standard
Model (SM) expectations; whereas no significant excess is observed in h --> ZZ*
--> {four lepton} events, albeit with large statistical uncertainty due to the
small data sample. These results (assuming they persist with further data)
could be explained by a pair of nearly mass-degenerate scalars, one of which is
a SM-like Higgs boson and the other is a scalar with suppressed couplings to
W+W- and ZZ. In the two Higgs doublet model, the observed \gamma\gamma and ZZ*
--> {four lepton} data can be reproduced by an approximately degenerate CP-even
(h) and CP-odd (A) Higgs boson for values of \sin(\beta-\alpha) near unity and
0.7 < \tan\beta < 1. An enhanced \gamma\gamma signal can also arise in cases
where m_h ~ m_H, m_H ~ m_A, or m_h ~ m_H ~ m_A. Since the ZZ* --> {four lepton}
signal derives primarily from a SM-like Higgs boson whereas the \gamma\gamma
signal receives contributions from two (or more) nearly mass-degenerate states,
one would expect a slightly different invariant mass peak in the ZZ* --> {four
lepton} and \gamma\gamma channels. The phenomenological consequences of such
models can be tested with additional Higgs data that will be collected at the
LHC in the near future.Comment: 18 pages, 19 pdf figures, v2: references added, v3&v4: added refs and
explanation
Charginos and Neutralinos Production at 3-3-1 Supersymmetric Model in Scattering
The goal of this article is to derive the Feynman rules involving charginos,
neutralinos, double charged gauge bosons and sleptons in a 3-3-1 supersymmetric
model. Using these Feynman rules we will calculate the production of a double
charged chargino with a neutralino and also the production of a pair of single
charged charginos, both in an electron- electron process.Comment: 18 pages, 8 figures, 2 table
Probing wrong-sign Yukawa couplings at the LHC and a future linear collider
We consider the two-Higgs-doublet model as a framework in which to evaluate
the viability of scenarios in which the sign of the coupling of the observed
Higgs boson to down-type fermions (in particular, -quark pairs) is opposite
to that of the Standard Model (SM), while at the same time all other tree-level
couplings are close to the SM values. We show that, whereas such a scenario is
consistent with current LHC observations, both future running at the LHC and a
future linear collider could determine the sign of the Higgs coupling
to -quark pairs. Discrimination is possible for two reasons. First, the
interference between the -quark and the -quark loop contributions to the
coupling changes sign. Second, the charged-Higgs loop contribution to the
coupling is large and fairly constant up to the largest
charged-Higgs mass allowed by tree-level unitarity bounds when the -quark
Yukawa coupling has the opposite sign from that of the SM (the change in sign
of the interference terms between the -quark loop and the and loops
having negligible impact).Comment: 28 pages, 21 figure
Scrutinizing the Alignment Limit in Two-Higgs-Doublet Models. Part 2: GeV
In the alignment limit of a multi-doublet Higgs sector, one of the Higgs mass
eigenstates aligns in field space with the direction of the scalar field vacuum
expectation values, and its couplings approach those of the Standard Model (SM)
Higgs boson. We consider CP-conserving Two-Higgs-Doublet Models (2HDMs) of Type
I and Type II near the alignment limit in which the heavier of the two CP-even
Higgs bosons, , is the SM-like state observed with a mass of 125 GeV, and
the couplings of to gauge bosons approach those of the SM. We review the
theoretical structure and analyze the phenomenological implications of this
particular realization of the alignment limit, where decoupling of the extra
states cannot occur given that the lighter CP-even state must, by
definition, have a mass below 125 GeV. For the numerical analysis, we perform
scans of the 2HDM parameter space employing the software packages 2HDMC and
Lilith, taking into account all relevant pre-LHC constraints, constraints from
the measurements of the 125 GeV Higgs signal at the LHC, as well as the most
recent limits coming from searches for heavy Higgs-like states. Implications
for Run 2 at the LHC, including expectations for observing the other scalar
states, are also discussed.Comment: 44 pages, 27 figures; v2: references added, some updated constraint
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