410 research outputs found
-- and ordinary-exotic fermion mixings revisited using some special observables
We investigate the mixing of an extra with the standard
and mixings of exotic fermions with their standard counterparts through some
precisely measured electroweak observables. These observables are geared to
search for physics beyond the Standard Model. We observe that although most of
such mixings are severely constrained by the recent LEP data, some of the
mixing angles could still be rather large, awaiting future tests.Comment: 11 pages, CERN-TH. 7196/94, Late
LEP- and low energy-bounds on R-parity-violating supersymmetric Yukawa couplings
Electroweak precision data at LEP are used to place bounds on some
-type (-violating) and -type (-violating) -parity
violating supersymmetric Yukawa couplings. We consider one-loop corrections
(triangles and self-energies) induced by these couplings to the -partial
widths. The couplings involving the top quark induce stronger loop effects and
hence are more strongly constrained than others. On the other hand, information
on - and -decays are used to constrain some of the -type
couplings which are complementary to the ones constrained from LEP. Among the
bounds we have derived, many are new from a phenomenological view-point.Comment: 2 pages, postscript (uucompressed), to appear in the Proceedings of
the International Europhysics Conference on High Energy Physics, Brussels, 27
July - 2 August, 199
Nondecoupling of charged scalars in Higgs decay to two photons and symmetries of the scalar potential
A large class of two- and three-Higgs-doublet models with discrete symmetries
has been employed in the literature to address various aspects of flavor
physics. We analyse how the precision measurement of the Higgs to diphoton
signal strength would severely constrain these scenarios due to the
nondecoupling behavior of the charged scalars, to the extent that the number of
additional scalar doublets can be constrained no matter how heavy the
nonstandard scalars are. We demonstrate that if the scalar potential is endowed
with appropriate global continuous symmetries together with soft breaking
parameters, decoupling can be achieved thanks to the unitarity constraints on
the mass-square differences of the heavy scalars.Comment: 9 pages, 2 figures, several clarifying remarks and references added,
to appear in Phys Rev
Chasing the light-gluino scenario through
We investigate the impact of a light gluino, which might have escaped
detection at colliders, on inclusive radiative -decays mediated through
penguin-like diagrams. We find that the viability of the scenario depends
largely on the magnitude of the flavour-violating -parameter. Some
previously allowed regions of parameter space are now ruled out.Comment: Latex, 8 pages + 1 Figure available upon request, CERN-TH. 7245/94,
DAMTP 94-3
New constraints on R-parity violation from K and B systems
We have derived new upper limits on several products (two at a time) of
lepton number violating -type couplings from the consideration of
and box graphs. Each box contains one scalar
lepton and one W-boson or one charged-Higgs-boson as internal lines. Most of
these bounds are more stringent than previously obtained. Some of these product
couplings drive (and some other ) decays to two charged leptons at
enhanced rates. Some of them can explain the rare
event recently observed at BNL.Comment: Latex, 6 pages, no figures; revised and published version with minor
changes in the Table caption and a few cosmetic changes in the tex
Pushing the SUSY Higgs mass towards 125 GeV with a color adjoint
We show that inclusion of a TeV scale chiral superfield transforming in the
adjoint representation of the color SU(3) to the MSSM particle content modifies
the renormalization group running of some parameters in such a way that a 125
GeV mass of the light Higgs boson is accommodated more comfortably than in
cMSSM / mSUGRA. Put differently, the introduction of a color adjoint TeV scale
superfield helps resurrecting lighter choices for the stop and gluino which are
otherwise disfavored in cMSSM / mSUGRA.Comment: v2: 6 pages, 4 figures, estimate of fine-tuning and some more
clarifying remarks added, published in PR
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