10,909 research outputs found
High scale perturbative gauge coupling in R-parity conserving SUSY SO(10) with longer proton lifetime
It is well known that in single step breaking of R-parity conserving SUSY
SO(10) that needs the Higgs representations the GUT-gauge
coupling violates the perturbative constraint at mass scales few times larger
than the GUT scale. Therefore, if the SO(10) gauge coupling is to remain
perturbative up the Planck scale(=2x10^{18} GeV), the scale of GUT
symmetry breaking is to be bounded from below. The bound depends upon specific
Higgs representations used for SO(10) symmetry breaking but, as we find, can
not be lower than GeV. In order to obtain such high unification
scale we propose a two-step SO(10) breaking through
intermediate gauge
symmetry. We estimate potential threshold and gravitational corrections to the
running of gauge couplings and show that they can make the picture of
perturbative GUT- gauge coupling running consistent at least up to the Planck
scale. We also show that when by ,
gravitational corrections alone with negligible threshold effects may guarantee
such perturbative gauge coupling. The lifetime of the proton is found to
increase by nearly 6 orders over the current experimental limit for . For the proton decay mediated by dim.5 operator a wide range of
lifetimes is possible extending from the current experimental limit up to
values 2-3 orders longer.Comment: 11 pages epjc LaTex as per specifications of European Physical
Journal
New Formulas and Predictions for Running Masses at Higher Scales in MSSM
Including contributions of scale-dependent vacuum expectation values of Higgs
scalars, we derive new one-loop formulas analytically for running quark-lepton
masses at higher scales in MSSM. Apart from the gauge-coupling dependence being
different from earlier formulas, the third-generation- Yukawa-coupling effects
are absent in the masses of the first two generations. While predicting the
masses and numerically, we also include two-loop effects.Comment: 9 pages Latex.Typos correcte
New Formulas and Predictions for Running Fermion Masses at Higher Scales in SM, 2HDM, and MSSM
Including contributions of scale-dependent vacuum expectation values, we
derive new analytic formulas and obtain substantially different numerical
predictions for the running masses of quarks and charged-leptons at higher
scales in the SM, 2HDM and MSSM. These formulas exhibit significantly different
behaviours with respect to their dependence on gauge and Yukawa couplings than
those derived earlier. At one-loop level the masses of the first two
generations are found to be independent of Yukawa couplings of the third
generation in all the three effective theories in the small mixing limit.
Analytic formulas are also obtained for running in 2HDM and
MSSM. Other numerical analyses include study of the third generation masses at
high scales as functions of low-energy values of and SUSY scale
GeV.Comment: 42 pages RevTeX, including 16 figures. Typos corrected and one
reference adde
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