57 research outputs found
Minimal supersymmetric SU(5) model with nonrenormalizable operators: Seesaw mechanism and violation of flavour and CP
Flavour and CP violations that the neutrino-seesaw couplings of types I, II,
and III induce radiatively in the soft massive parameters of the minimal
supersymmetric SU(5) model, made realistic by nonrenormalizable operators, are
analyzed. Effective couplings are used to parametrize the couplings of
renormalizable operators and of the corrections that nonrenormalizable ones
provide at the tree level. It is found that for a limited, but sufficient
accuracy in the calculations of such violations, it is possible to extend the
picture of effective couplings to the quantum level, all the way to the cutoff
scale. The arbitrariness introduced by nonrenormalizable operators is analyzed
in detail. It is shown that it can be drastically reduced in the Yukawa sector
if the effective Yukawa couplings involving colored triplet Higgs bosons are
tuned to suppress the decay rate of the proton. In the supersymmetry-breaking
sector, the usual requirement of independence of flavour and field type for the
mechanism of mediation of supersymmetry breaking is not sufficient to forbid
arbitrary flavour and CP violations at the tree level. Special conditions to be
added to this requirement, under which such violations can be avoided, are
identified. Depending on how and whether these conditions are implemented,
different phenomenological scenarios emerge. Flavour and CP violations of soft
massive parameters induced by neutrino-seesaw couplings are discussed
explicitly for the simplest scenario, in which no such violations are present
at the tree level. Guidelines for studying them in other, less simple scenarios
are given. Lists of all renormalization group equations needed for their
calculations are provided for each of the three types of seesaw mechanism, at
all energies between the TeV scale and Planck scale.Comment: 108 pages, 4 figs. v4: Minor improvements. Published version. The
RGEs of App E can be found in a very explicit form at
http://www.tuhep.phys.tohoku.ac.jp/~francescaB/rges.htm
Addendum to ``Threshold corrections to and the production in CP-violating SUSY scenarios''
In hep-ph/0401024: ``Threshold corrections to and the production in CP-violating SUSY scenarios'', we have pointed out that
the production cross sections of the three neutral Higgs bosons through
fusion can deviate substantially from those obtained in CP
conserving scenarios, thanks to the nontrivial role played by the threshold
corrections to combined with the CP-violating mixing in the
neutral-Higgs-boson sector. The deviations are largest for values of the
CP-violating phases that maximize the mixing among at least two of the three
neutral Higgs bosons. We complement our previous work focussing explicitly on
the values of masses and widths of the three neutral Higgs bosons in this
region of parameter space. We then address the issue of whether the three
different peaks in the invariant mass distribution of the Higgs-decay products
can be experimentally disentangled at the LHC.Comment: 1+6 pages, 3 figure
The Higgs boson and the International Linear Collider
The Higgs boson will be subject of intense experimental searches in future
high-energy experiments. In addition to the effort made at the Large Hadron
Collider, where it was discovered, it will be the major subject of study at the
International Linear Collider. We review here the reasons for that and some of
the issues to be tackled at this future accelerator, in particular that of the
precision of the Higgs-boson couplings.Comment: 7 pages, 4 figure
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