Recently, the reactor mixing angle 13 θ has been measured precisely by Daya Bay, RENO, and T2K experiments with a moderately large value. However, the standard form of neutrino mixing patterns such as bimaximal, tri-bimaximal, golden ratio of types A and B, hexagonal, etc., which are based on certain flavor symmetries, predict vanishing 13 θ . Using the fact that the neutrino mixing matrix can be represented as V U U P l PMNS † = ν ν , where U l and U ν result from the diagonalization of the charged lepton and neutrino mass matrices and P ν is a diagonal matrix containing Majorana phases, we explore the possibility of accounting for the large reactor mixing angle by considering deviations both in the charged lepton and neutrino sector. In the charged lepton sector we consider the deviation as an additional rotation in the (12) and (13) planes, whereas in the neutrino sector we consider deviations to various neutrino mixing patterns through (13) and (23) rotations. We find that with the inclusion of these deviations it is possible to accommodate the observed large reactor mixing angle 13 θ , and one can also obtain limits on the charge-conjugation parity-violating Dirac phase CP δ and Jarlskog invariant J CP for most of the cases. We then explore whether our findings can be tested in the currently running NuMI Off-axis v e Appearance experiment with three years of data taking in neutrino mode followed by three years with the anti-neutrino mode. PMNS PMNS 12 13 12 13 13 i 12 23 12 13 23 i 12 23 12 13 23 i 13 23 12 23 12 13 23 i 12 23 12 13 23 i 13 23 CP CP CP CP CP

Motivated by the crucial role played by the discrete flavor symmetry groups in explaining the observed neutrino oscillation data, we consider the A 4 realization of linear seesaw by extending the standard model (SM) particle content with two types of right-handed (RH) neutrinos along with the flavon fields, and the SM symmetry with A 4 × Z 4 × Z 3 and a global symmetry U (1) X , which is broken explicitly by the Higgs potential. We scrutinize this model to see if it can explain the recent results from neutrino oscillation experiments, by searching for parameter space that can accommodate the observables such as the reactor mixing angle θ 13 , the CP violating phase δ CP , sum of active neutrino masses i m i , solar and atmospheric mass-squared differences, and the lepton number violating parameter called the effective Majorana mass parameter, in line with recent experimental results. We also discuss the scope of this model to explain the baryon asymmetry of the Universe through leptogenesis. We also investigate the possibility of probing the non-unitarity effect in this scenario, but it is found to be rather small. Commission for financial support. RM acknowledges the support from the Science and Engineering Research Board (SERB), Government of India, through Grant No. SB/S2/HEP-017/2013.

To accommodate the recently observed non-zero reactor mixing angle θ 13 , we consider the lepton mixing matrix as Tri-bimaximal mixing (TBM) form in the leading order along with a perturbation in neutrino sector. The perturbation is taken to be a rotation in 23 plane followed by a rotation in 13 plane, i.e., R 23 (θ 23 )R 13 (θ 13 , φ). We obtain the allowed values of the parameters θ 23 , θ 13 and φ, which can accommodate all the observed mixing angles consistently and calculate the phenomenological observables such as the Dirac CP violating phase (δ CP ), Jarlskog invariant (J CP ), effective majorana mass M ν ee , and m νe , the electron neutrino mass. We find that δ CP can take any values between 0 and −π/2 and M ν ee always comes below its experimental upper limit.

We demonstrate how a class of non-supersymmetric SO(10) GUT with asymmetric left-right theory SU (2) L × U (1) R × U (1) B−L × SU (3) C and Pati-Salam theory SU (2) L × SU (2) R × SU (4) C as intermediate symmetry breaking steps leads to successful gauge coupling unification satisfying proton decay constraints. The motivation behind this work is two fold: firstly to study the renormalization group evolution equations for gauge couplings by keeping right-handed neutral gauge boson Z R around LHC energy range leading interesting dilepton searches at collider while fixing charge partner of the gauge boson W R at very high scale; secondly to explain neutrino masses and associated lepton number violating process like neutrinoless double beta decay in three possible cases depending onThe presence of Pati-Salam symmetry and Pati-Salam symmetry with D-parity (discrete left-right symmetry leading to g L = g R ) at highest scale is to allow two gauge couplings and thereby ensuring precision unification for gauge couplings. We focus on neutrino mass and neutrinoless double beta decay for one particular case where TeV scale asymmetric left-right theory is spontaneously broken down to SM with non-zero VEV of both Higgs doublets with B − L = −1 and Higgs triplets with B − L = 2. We include one extra fermion singlet per generation in order to implement gauged extended seesaw where light neutrino mass is governed by natural type-II seesaw mechanism whereas type-I seesaw contribution is exactly canceled out. Since light neutrino mass formula is independent of Dirac neutrino mass matrix, the value of Dirac neutrino mass is taken to be up-type quark mass matrix which is a characteristics of Pati-Salam symmetry relating quarks with leptons. This large value of Dirac neutrino mass can contribute to neutrinoless double beta decay, non-unitarity effects in leptonic sector and lepton flavor violation. We present analytic relation for effective Majorana mass parameter and corresponding half-life arising from new physics contributions due to purely left-handed currents through exchange of heavy right-handed neutrinos and sterile neutrinos. We numerically estimate effective Majorana mass parameter and half-life vs. lightest neutrino mass and derive lower bound on lightest neutrino mass by saturating with experimental bounds like GERDA Phase-II, KamLANDZen and EXO.

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