10,756 research outputs found
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
Preserving the validity of the Two-Higgs Doublet Model up to the Planck scale
We examine the constraints on the two Higgs doublet model (2HDM) due to the
stability of the scalar potential and absence of Landau poles at energy scales
below the Planck scale. We employ the most general 2HDM that incorporates an
approximately Standard Model (SM) Higgs boson with a flavor aligned Yukawa
sector to eliminate potential tree-level Higgs-mediated flavor changing neutral
currents. Using basis independent techniques, we exhibit robust regimes of the
2HDM parameter space with a 125 GeV SM-like Higgs boson that is stable and
perturbative up to the Planck scale. Implications for the heavy scalar spectrum
are exhibited.Comment: 36 pages, 4 figures, 4 tables (Version 3: typographical error in eq.
(A.28) corrected
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
Implications of symmetries in the scalar sector
Symmetries play a very important r\^ole in Particle Physics. In extended
scalar sectors, the existence of symmetries may permit the models to comply
with the experimental constraints in a natural way, and at the same time reduce
the number of free parameters. There is a strong interplay among internal
symmetries of the scalar potential, its CP properties and mass degeneracies of
the physical scalars. Some of these aspects were discussed in this talk.Comment: 8 pages, to be published in the Proceedings of DISCRETE2018: 6th
Symposium on Prospects in the Physics of Discrete Symmetries, 26-30 Nov 2018.
Vienna, Austri
Basis invariant conditions for supersymmetry in the two-Higgs-doublet model
The minimal supersymmetric standard model involves a rather restrictive Higgs
potential with two Higgs fields. Recently, the full set of classes of
symmetries allowed in the most general two Higgs doublet model was identified;
these classes do not include the supersymmetric limit as a particular class.
Thus, a physically meaningful definition of the supersymmetric limit must
involve the interaction of the Higgs sector with other sectors of the theory.
Here we show how one can construct basis invariant probes of supersymmetry
involving both the Higgs sector and the gaugino-higgsino Higgs interactions.Comment: RevTex, 11 pages, v2-small section adde
Symmetries and Mass Degeneracies in the Scalar Sector
We explore some aspects of models with two and three SU(2) scalar doublets
that lead to mass degeneracies among some of the physical scalars. In Higgs
sectors with two scalar doublets, the exact degeneracy of scalar masses,
without an artificial fine-tuning of the scalar potential parameters, is
possible only in the case of the inert doublet model (IDM), where the scalar
potential respects a global U(1) symmetry that is not broken by the vacuum. In
the case of three doublets, we introduce and analyze the replicated inert
doublet model, which possesses two inert doublets of scalars. We then
generalize this model to obtain a scalar potential, first proposed by Ivanov
and Silva, with a CP4 symmetry that guarantees the existence of pairwise
degenerate scalar states among two pairs of neutral scalars and two pairs of
charged scalars. Here, CP4 is a generalized CP symmetry with the property that
is the identity operator only for integer values that are
multiples of 4. The form of the CP4-symmetric scalar potential is simplest when
expressed in the Higgs basis, where the neutral scalar field vacuum expectation
value resides entirely in one of the scalar doublet fields. The symmetries of
the model permit a term in the scalar potential with a complex coefficient that
cannot be removed by any redefinition of the scalar fields within the class of
Higgs bases (in which case, we say that no real Higgs basis exists). A striking
feature of the CP4-symmetric model is that it preserves CP even in the absence
of a real Higgs basis, as illustrated by the cancellation of the contributions
to the CP violating form factors of the effective ZZZ and ZWW vertices.Comment: 52 pages, 2 figures, second revised version with new material, as
published by JHE
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
The CP-conserving 2HDM after the 8 TeV run
We confront the most common CP-conserving 2HDM with the LHC data analysed so
far while taking into account all previously available experimental data. A
special allowed corner of the parameter space is analysed - the so-called
wrong-sign scenario where the Higgs coupling to down-type quarks changes sign
relative to the Standard Model while the coupling to the massive vector bosons
does not.Comment: 6 pages, 2 figures, to appear in the proceedings of the 22nd
International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS
2014), 28 April - 2 May 2014 Warsaw (Poland
The Wrong Sign limit in the 2HDM
A sign change in the Higgs couplings to fermions and massive gauge bosons is
still allowed in the framework of two-Higgs doublet models (2HDM). In this work
we discuss the possible sign changes in the Higgs couplings to fermions and
gauge bosons, while reviewing the status of the 8-parameter CP-conserving 2HDM
after the Large Hadron Collider 8 TeV run.Comment: 6 pages, 3 figures. Proceedings of the Second Annual Conference on
Large Hadron Collider Physics, Columbia University, New York, U.S.A, June
2-7, 2014. arXiv admin note: text overlap with arXiv:1407.439
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
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