122 research outputs found

### Corrections to mass scale predictions in SO(10) GUT with higher dimensional operators

We calculate the two loop contribution to the predictions of the mass scales
in an SO(10) grand unified theory. We consider the modified unification scale
boundary conditions due to the non-renormalizable higher dimensional terms
arising from quantum gravity or spontaneous compactification of extra
dimensions in Kaluza-Klein type theory. We find the range of these couplings
which allows left-right symmetry to survive till very low energy (as low as
$\sim$ TeV) and still be compatible with the latest values of $\sin^2 \theta_W$
and $\alpha_s$ derived from LEP. We consider both the situation when the
left-right parity is broken and conserved.We consider both supersymmetric and
non-supersymmertic versions of the SO(10) theory.Taking the D-conserved
non-susy case as an example we calculate the effects of moderate threshold
uncertainties at the heavy scale, due to the unknown higgs masses,on the
gravity induced couplings.Comment: 18 pages with three figures available on
request([email protected]),UH-511-780-9

### Lorentz Invariance Violation and IceCube Neutrino Events

The IceCube neutrino spectrum shows a flux which falls of as $E^{-2}$ for sub
PeV energies but there are no neutrino events observed above $\sim 3$ PeV. In
particular the Glashow resonance expected at 6.3 PeV is not seen. We examine a
Planck scale Lorentz violation as a mechanism for explaining the cutoff of
observed neutrino energies around a few PeV. By choosing the one free parameter
the cutoff in neutrino energy can be chosen to be between 2 and 6.3 PeV. We
assume that neutrinos (antineutrinos) have a dispersion relation $E^2=p^2 -
(\xi_3/M_{Pl})~p^3$, and find that both $\pi^+$ and $\pi^-$ decays are
suppressed at neutrino energies of order of few PeV. We find that the $\mu^-$
decay being a two-neutrino process is enhanced, whereas $\mu^+$ decay is
suppressed. The $K^+\rightarrow \pi^0 e^+ \nu_e$ is also suppressed with a
cutoff neutrino energy of same order of magnitude, whereas $K^-\rightarrow
\pi^0 e^- \bar \nu_e$ is enhanced. The $n \rightarrow p^+ e^- \bar \nu_e$ decay
is suppressed (while the $\bar n \rightarrow p^- e^+ \nu_e$ is enhanced). This
means that the $\bar \nu_e$ expected from $n$ decay arising from $p+\gamma
\rightarrow \Delta \rightarrow \pi^+ n$ reaction will not be seen. This can
explain the lack of Glashow resonance events at IceCube. If no Glashow
resonance events are seen in the future then the Lorentz violation can be a
viable explanation for the IceCube observations at PeV energies.Comment: v2, 16 pages, Version accepted for publication in JHE

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