S.R. Choudhury

Bounds on the neutrino magnetic moment from SN 1987 A

Abstract We examine the emission of wrong helicity neutrinos from SN 1987 A due to neutrino magnetic moment (μv). We consider the case when the core of nascent neutron star is on the verge of pion condensation. The relevant processes are the p + π − → n + ν l,r ν l,r and πν l ( ν r ) → πν r ( ν l ) . We have also studied the case where the core is assumed to have undergone a phase transition to quark matter. The important process here is q + ν l ( ν r ) → q + ν r ( ν l ) . By imposing a bound on νr luminosity, we get a limit on μv≲(0.3−0.05)×10−12 μb depending on the temperature and composition of the core.

A note on low scale unification and gamma–gamma scattering

Abstract In this note we study an interesting effect of low energy gravity on photon-photon scattering at high energies.In this note we study an interesting effect of low energy gravity on photon-photon scattering at high energies.

Tests of second-class currents

Abstract We argue that the presence of second-class neutral currents can be tested from the observations of η→π 0 ν l ν l and electron polarisation in η→π0e+e-. Consequences of this model in η→π±e∓νe,τ±→ηπ±ντ and τ±→ωπ±ντ decays which would establish second-class charged currents are also discussed.

Weak scale quantum gravity effects for γγ→ZZ in the TeV region

We consider the effect of massive spin-2 gravitons that occur as Kaluza-Klein excitations of the graviton in a Weak scale Quantum Gravity scenario on the process

TRIVIALITY BOUND ON LIGHTEST HIGGS MASS IN NEXT TO MINIMAL SUPERSYMMETRIC MODEL

\gamma \gamma \to ZZ

ON PION COOLING IN THE SUPERNOVA CORE

, which in the Standard Model can proceed through loop diagrams. For a wide range of parameters, we show that the massive gravitons leave behind signatures that should be verifiable in a TeV scale scattering experiment.We consider the effect of massive spin-2 gravitons that occur as Kaluza-Klein excitations of the graviton in a Weak scale Quantum Gravity scenario on the process

Einstein-Podolsky-Rosen paradox, statistical locality and the time-energy uncertainty relation

\gamma \gamma \to ZZ

Neutrino lensing and modification of Newtonian gravity at large distances.

, which in the Standard Model can proceed through loop diagrams. For a wide range of parameters, we show that the massive gravitons leave behind signatures that should be verifiable in a TeV scale scattering experiment.

Study of the flavor changing neutral current decay mode B ---> K gamma gamma

We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that the mass of the lightest Higgs boson in NMSSM has an upper bound ∼10MW which is of the same order as that in the standard model.We study the implication of triviality on Higgs sector in next to minimal su-persymmetric model (NMSSM) using variational field theory. It is shown that mass of the lightest Higgs boson in NMSSM has an upper bound ∼ 10 M W which is of the same order as that in standard model.

Study of the flavor changing neutral current decay mode B → K γ γ

We examine the cooling mechanism of a nascent neutron star core by the emission of wrong helicity neutrinos, when the core is at the verge of pion condensation. We study the dominant process due to neutrino magnetic moment in terms of the model-independent multipole amplitudes based on dispersion relation theory. This calculation gives a more realistic emission rate for neutrinos and hence an upper bound for neutrino magnetic moment