Subhaditya Bhattacharya

Effective Lagrangian approach to neutrinoless double beta decay and neutrino masses

A bstractNeutrinoless double beta (0νββ) decay can in general produce electrons of either chirality, in contrast with the minimal Standard Model (SM) extension with only the addition of the Weinberg operator, which predicts two left-handed electrons in the final state. We classify the lepton number violating (LNV) effective operators with two leptons of either chirality but no quarks, ordered according to the magnitude of their contribution to 0νββ decay. We point out that, for each of the three chirality assignments, eLeL, eLeR and eReR, there is only one LNV operator of the corresponding type to lowest order, and these have dimensions 5, 7 and 9, respectively. Neutrino masses are always induced by these extra operators but can be delayed to one or two loops, depending on the number of RH leptons entering in the operator. Then, the comparison of the 0νββ decay rate and neutrino masses should indicate the effective scenario at work, which confronted with the LHC searches should also eventually decide on the specific model elected by nature. We also list the SM additions generating these operators upon integration of the heavy modes, and discuss simple realistic examples of renormalizable theories for each case.

A realistic model of neutrino masses with a large neutrinoless double beta decay rate

A bstractThe minimal Standard Model extension with the Weinberg operator does accommodate the observed neutrino masses and mixing, but predicts a neutrinoless double beta (0νββ) decay rate proportional to the effective electron neutrino mass, which can be then arbitrarily small within present experimental limits. However, in general 0νββ decay can have an independent origin and be near its present experimental bound; whereas neutrino masses are generated radiatively, contributing negligibly to 0νββ decay. We provide a realization of this scenario in a simple, well defined and testable model, with potential LHC effects and calculable neutrino masses, whose two-loop expression we derive exactly. We also discuss the connection of this model to others that have appeared in the literature, and remark on the significant differences that result from various choices of quantum number assignments and symmetry assumptions. In this type of models lepton flavor violating rates are also preferred to be relatively large, at the reach of foreseen experiments. Interestingly enough, in our model this stands for a large third mixing angle,

Dark vector-gauge-boson model

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Supersymmetric left–right model with radiative neutrino mass and multipartite dark matter

smash{scriptscriptstylethicksim}

Pionic dark matter

}}{ > }}0.00{8}

Nonuniversal supergravity at the LHC: Prospects and discovery potential

, when μ→eee is required to lie below its present experimental limit.

Neutrinoless double β decay with small neutrino masses

A model based on

Constraints on Two-Component Dark Matter

SU(3{)}_{C}ifmmodetimeselsetexttimesfi{}SU(2{)}_{L}ifmmodetimeselsetexttimesfi{}U(1{)}_{Y}ifmmodetimeselsetexttimesfi{}SU(2{)}_{N}

Supersymmetry Signals at the LHC under the most favorable SUGRA scenario

has recently been proposed, where the

Dark Matter Pions

SU(2{)}_{N}