428 research outputs found
What is the Natural Size of Supersymmetric Violation?
It is well known that if phases and masses in the Minimal Supersymmetric
Standard Model (MSSM) are allowed to have general values, the resulting neutron
EDM () exceeds the experimental upper limit by about . We assume
that the needed suppression is not due to a fine-tuning of phases or masses,
and ask what natural size of violation (CPV) results. We show that (1) the
phase of one of the superpotential parameters, , does not contribute to
any CPV in the MSSM and so is not constrained by \dn; (2) the MSSM contribution
to is tiny, just coming from the CKM phase; (3) the phases in the MSSM
cannot be used to generate a baryon asymmetry at the weak scale, given our
assumptions; and (4) in non-minimal SUSY models, an effective phase can enter
at one loop giving \ecm, \ecm, and
allowing a baryon asymmetry to be generated at the weak scale, without
fine-tunings. Our results could be evaded by a SUSY breaking mechanism which
produced phases for the SUSY breaking parameters that somehow were naturally of
order .Comment: 13pp (no figs), REVTEX (LATEX), TRI-PP-93-
Measuring the Supersymmetry Lagrangian
The parameters of the supersymmetry Lagrangian are the place where experiment
and theory will meet. We show that measuring them is harder than has been
thought, particularly because of large unavoidable dependences on phases.
Measurements are only guaranteed if a lepton collider with a polarized beam and
sufficient energy to produce the relevant sparticles is available. Current
limits on superpartner masses, WIMPs, and the supersymmetric Higgs are not
general, and need re-evaluation. We also tentatively define the MRM (Minimum
Reasonable Model), whose parameters may be measurable at LEP, FNAL and LHC.Comment: 10 pages, 1 figure; a typographical error corrected in eq. (1) and
one reference adde
Supersymmetric with Large Chargino Contributions
Supersymmetric (SUSY) theories are often thought to give large branching
ratios for from charged Higgs loops. We show that in
many cases chargino loop contributions can cancel those of the Higgs, and SUSY
can give at or below the \SM\ prediction. We show
this occurs because the large stop mass splittings usually found in SUSY break
a GIM mechanism suppression. These effects are strongly enhanced by large
, so that is very sensitive to the value
of , contrary to what has been claimed. We also note that the
supergravity relation is somewhat disfavored over the general
case.Comment: TRI-PP-93-66. 12pp (Plain LATEX)+4 fig not incl. PostScript file of
figs available (~3MB), contact Corrie Kost [email protected]. Request hardcopy
or FAX of figures through [email protected]
Heavy quark polarizations of in the general two Higgs doublet model
The polarizations of the heavy quark ( or ) in the process have been calculated in the general two Higgs doublet model.
The CP violating normal polarization of the top quark can reach 8%, and for the bottom quark, while it is zero in the standard model. The
longitudinal and transverse polarizations of the bottom quark can be
significantly different from those in SM and consequently could aslo be used as
the probe of the new physics.Comment: 12 pages, discussion on statistic significance added, version to
appear in PR
What can the L3 events be?
We consider the 4 () events reported by the L3
collaboration, and go through the logical possibilities which could explain the
events. If they are not coincidental bremsstrahlung events, we find that the
physics which they could point to is extremely limited. One possibility would
be to have a new 60 GeV scalar (or pseudoscalar) particle with an
off-diagonal coupling to a and which is non-perturbative (), where the couplings to are suppressed. One could also
construct a model involving , and a second scalar with a large
coupling. We do not promote either of these models, but hope they would
prove to be useful guidelines, should the L3 events turn out to be new physics.Comment: 7 pp (3 fig avail. on request), LATEX, TRI-PP-92-12
More on Electric Dipole Moment Constraints on Phases in the Constrained MSSM
We reconsider constraints on \cp-violating phases in the Constrained
Minimal Supersymmetric Standard Model. We include the recent calculations of
Ibrahim and Nath on the chromoelectric and purely gluonic contributions to the
quark electric dipole moment and combine cosmological limits on gaugino masses
with experimental bounds on the neutron (and electron) electric dipole moments.
The constraint on the phase of the Higgs mixing mass , |\thm|, is
dependent on the value of the trilinear mass parameter, , in the model and
on . For values of |A| < 300 \gev at the GUT scale, we find
|\thm|/\pi \la 0.05, while for |A| < 1500 \gev, |\thm|/\pi \la 0.3. Thus,
we find that in principle, large CP violating phases are compatible with the
bounds on the electric dipole moments of the neutron and electron, as well as
remaining compatible with the cosmological upper bound on the relic density of
neutralinos. The other \cp-violating phase \tha is essentially
unconstrained.Comment: 11 pages in LaTeX + 4 postscript figures, uses epsf.sty. Added two
references, clarified figures. Accepted to Physics Letter
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