32,015 research outputs found
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
Explicit Actions for Electromagnetism with Two Gauge Fields with Only one Electric and one Magnetic Physical Fields
We extend the work of Mello et al. based in Cabbibo and Ferrari concerning
the description of electromagnetism with two gauge fields from a variational
principle, i.e. an action. We provide a systematic independent derivation of
the allowed actions which have only one magnetic and one electric physical
fields and are invariant under the discrete symmetries and . We conclude
that neither the Lagrangian, nor the Hamiltonian, are invariant under the
electromagnetic duality rotations. This agrees with the weak-strong coupling
mixing characteristic of the duality due to the Dirac quantization condition
providing a natural way to differentiate dual theories related by the duality
rotations (the energy is not invariant). Also the standard electromagnetic
duality rotations considered in this work violate both and by inducing
Hopf terms (theta terms) for each sector and a mixed Maxwell term. The
canonical structure of the theory is briefly addressed and the 'magnetic' gauge
sector is interpreted as a ghost sector.Comment: v2: 12 pages; References added, discussion concerning degrees of
freedom corrected; v3: is now used the standard normalization of 1/4 in the
actions; the possibility of theta being a pseudo-scalar implied a title
changing; eq (23) added; signs corrected in equations (39,45-47); references
adde
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
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
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
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