arXiv subjects

Utpal Sarkar

Publications and source records attributed to Utpal Sarkar.

134 records · Page 8Linked to original sources

arXiv1994

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 $\sin^2 θ_W$ and $α_s$ 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.

hep-ph↗

arXiv1994

Potential Minimization in Left-Right Symmetric Models

We study the Higgs potentials in the Left-Right symmetric model for various choices of Higgs fields. We give emphasis to the cases when the Higgs field $ξ=(2,2,15)$ is included to give the correct relations of quark masses and a singlet field $η$ which breaks the left-right parity. As special cases we also include $ξ^\prime=(2,2,15)$ and $χ=(2,2,6)$ (which are interesting in the context of the three lepton decay mode of the proton) and field $δ=(3,3,0)$ none of which acquire {\it vev}. We show that the linear couplings of these fields upon minimization put fine tuning conditions on the parameters of the model. We carry out the minimization of these potentials explicitly. In all the cases the relationship between the {\it vev$\;$}s of the left and right handed triplets $v_L$ and $v_R$ are given. The phenomenological consequences of this minimization regarding the neutrino masses are also studied.

hep-ph↗

arXiv1994

Proton Decay and Related Processes in Unified Models with Gauged Baryon Number:

In unification models based on SU(15) or SU(16), baryon number is part of the gauge symmetry, broken spontaneously. In such models, we discuss various scenarios of important baryon number violating processes like proton decay and neutron-antineutron oscillation. Our analysis depends on the effective operator method, and covers many variations of symmetry breaking, including different intermediate groups and different Higgs boson content. We discuss processes mediated by gauge bosons and Higgs bosons parallely. We show how accidental global or discrete symmetries present in the full gauge invariant Lagrangian restrict baryon number violating processes in these models. In all cases, we find that baryon number violating interactions are sufficiently suppressed to allow grand unification at energies much lower than the usual $10^{16}$ GeV.

hep-ph↗

arXiv1993

Baryogenesis via lepton number violating scalar interactions

We study baryogenesis through lepton number violation in left-right symmetric models. In these models the lepton number and CP violating interactions of the triplet higgs scalars can give rise to lepton number asymmetry through non-equilibrium decays of the $SU(2)_L$ triplet higgs and the right handed neutrinos. This in turn generates baryon asymmetry during the electroweak anomalous processes.

hep-ph↗

arXiv1993

Three lepton decay modes of the proton

We consider the three lepton decay modes of the proton within the proton decay interpretation of the atmospheric neutrino anomaly. We construct higher dimensional operators in the framework of the standard model. The operators which allow the particularly interesting decay mode are of dimension 10 involving $SU(2)_L$ non-singlet higgs. We show how these operators can be comparable to the dimension 9 operators. We then present a simple left-right symmetric model which can give rise to the desired proton decay modes of the right order of magnitude.

hep-ph↗

arXiv1993

Higher Dimensional Operators and Low Energy Left-Right Symmetry

We consider higher dimensional operators due to quantum gravity or spontaneous compactification of extra dimensions in Kaluza-Klein type theory and their effect in the $SO(10)$ Lagrangian. These operators change the boundary conditions at the unification scale. As a result one can allow left-right symmetry to survive till very low energy (as low as $\sim$ TeV) for a wide range of values for the coupling of these higher dimensional operators and still make the theory compatible with the latest values of $\sin^2 θ_W$ and $α_s$ derived from LEP. We consider both non-supersymmetric and supersymmetric cases with standard higgses. Proton lifetime is very large in these theories.

hep-ph↗

arXiv1993

Neutrinoless Double Beta Decay and CP Violation

We study the relation between the Majorana neutrino mass matrices and the neutrinoless double beta decay when CP is not conserved. We give an explicit form of the decay rate in terms of a rephasing invariant quantity and demonstrate that in the presence of CP violation it is impossible to have vanishing neutrinoless double beta decay in the case of two neutrino generations (or when the third generation leptons do not mix with other leptons and hence decouple).

hep-ph↗

arXiv1993

CP Violation and Leptogenesis

Recently a model of chaotic inflation was proposed, where the right handed sneutrinos drive the baryogenesis. We study some of the details of the model, particularly the aspect of CP violation, and determine the number of right handed sneutrinos required for the viability of such models.

hep-ph↗