118520803
Corrections for tribimaximal, bimaximal and democratic neutrino mixing matrices
A bstractIn this work we analyze the corrections to tribimaximal (TBM), bimaximal (BM) and democratic (DC) mixing matrices for explaining large reactor mixing angle θ13 and checking the consistency with other neutrino mixing angles. The corrections are parameterized in terms of small orthogonal rotations (R) with corresponding modified PMNS matrix of the form Rij·U·Rkl where Rij is rotation in ij sector and U is any one of these special matrices. We showed the rotations R13·U·R23, R12·U·R13 for BM and R13·U·R13 for TBM perturbative case successfully fit all neutrino mixing angles within 1σ range. The perturbed PMNS matrix R12·U·R13 for DC, TBM and R23·U·R23 for TBM case is successful in producing mixing angles at 2σ level. The other rotation schemes are either excluded or successful in producing mixing angles at 3σ level.
119261053
Renormalization Group Evolution of Neutrino Parameters in Presence of Seesaw Threshold Effects and Majorana Phases
We examine the renormalization group evolution (RGE) for different mixing scenarios in the presence of seesaw threshold effects from high energy scale (GUT) to the low electroweak (EW) scale in the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM). We consider four mixing scenarios namely Tri–Bimaximal Mixing, Bimaximal Mixing, Hexagonal Mixing and Golden Ratio Mixing which come from different flavor symmetries at the GUT scale. We find that the Majorana phases play an important role in the RGE running of these mixing patterns along with the seesaw threshold corrections. We present a comparative study of the RGE of all these mixing scenarios both with and without Majorana CP phases when seesaw threshold corrections are taken into consideration. We find that in the absence of these Majorana phases both the RGE running and seesaw effects may lead to θ13<5° at low energies both in the SM and MSSM. However, if the Majorana phases are incorporated into the mixing matrix the running can be enhanced both in the SM and MSSM. Even by incorporating non-zero Majorana CP phases in the SM, we do not get θ13 in its present 3σ range. The current values of the two mass squared differences and mixing angles including θ13 can be produced in the MSSM case with tan⁡β=10 and non-zero Majorana CP phases at low energy. We also calculate the order of effective Majorana mass and Jarlskog Invariant for each scenario under consideration.
119300069
Parallel hybrid textures of lepton mass matrices
We analyse the parallel hybrid texture structures in the charged lepton and the neutrino sector. These parallel hybrid texture structures have physical implications as they cannot be obtained from arbitrary lepton mass matrices through weak basis transformations. The total sixty parallel hybrid texture structures can be grouped into twelve classes, and all the hybrid textures in the same class have identical physical implications. We examine all the twelve classes under the assumption of non-factorizable phases in the neutrino mass matrix. Five out of the total twelve classes are found to be phenomenologically disallowed. We study the phenomenological implications of the allowed classes for 1-3 mixing angle, Majorana and Dirac-type CP violating phases. Interesting constraints on effective Majorana mass are obtained for all the allowed classes.
2063566
Phenomenology of Two-Texture Zero Neutrino Mass Matrices
The generic predictions of two-texture zero neutrino mass matrices in the flavor basis have been examined especially in relation to the degeneracies between mass matrices within a class and interesting constraints on the neutrino parameters have been obtained. It is shown that the knowledge of the octant of ${\ensuremath{\theta}}_{23}$, the sign of $\mathrm{cos}﻿\ensuremath{\delta}$, and neutrino mass hierarchy can be used to lift these degeneracies.
119252719
Near maximal atmospheric mixing in neutrino mass matrices with two vanishing minors
Abstract In the flavor basis there are seven cases of two vanishing minors in the neutrino mass matrix which can accommodate the present neutrino oscillation data including the recent T2K data. It is found that two of these cases, namely B 5 and B 6 predict near maximal atmospheric neutrino mixing in the limit of large effective neutrino mass. This feature remains irrespective of the values of solar and reactor mixing angles. A non-zero reactor mixing angle is naturally accommodated in these textures.
16189897
PHENOMENOLOGICAL IMPLICATIONS OF A CLASS OF LEPTON MASS MATRICES
Phenomenological implications of a class of lepton mass matrices with parallel texture structure have been examined and phenomenologically interesting constraints on charged lepton and neutrino mass matrix parameters have been obtained.
119638891
Delayed energetic events in extensive air showers
Production of massive (> or =10 GeV/c/sup 2/) strongly interacting particles in very-high-energy interactions has been suggested by many theories. These particles, if produced in the cores of extensive air showers in the upper atmosphere, would arrive at the observational level delayed by tens of nanoseconds relative to all other known particles of similar energy, provided they are relatively stable (lifetime >10/sup -6/ s). Experiments searching for such particles have reported observing delayed (>20 ns) energetic (>40 GeV) events. However several anomalous features observed for these events have precluded their interpretation in terms of massive particles with ordinary hadronic interaction characteristics in a conclusive manner. We report here the details of a new experiment carried out at the Ooty laboratory during 1978--1981 where we have attempted to study the delayed energetic events with a multidetector system placed inside the large Ooty multiplate cloud chamber. Our observations show that the delayed energetic events could not be ascribed to high-energy hadronlike interactions of a massive strongly interacting particle. We have observed one delayed event showing a high-energy cascade in cloud chamber but inadequate timing information does not make a convincing case for this event to be due to a high-energy delayed massivemore » hadron. However this event combined with observation of two similar events earlier by Tonwar et al. suggest the existence of some interesting phenomenon requiring observations over a long period of time. We have obtained a 99% C.L. upper limit of 1.7 x 10/sup -11/ cm/sup -2/ s/sup -1/ sr/sup -1/ for the flux of massive particles in extensive air showers of size approx.(5 x 10/sup 4/)--(5 x 10/sup 6/) particles which corresponds to an upper limit of 2.5 x 10/sup -33/ cm/sup 2/ for the production cross section for particles of mass >10 GeV/c/sup 2/ at energies of approx.10/sup 5/--10/sup 7/ GeV.« less
118646248
Predictions from High Scale Mixing Unification Hypothesis
We investigate the renormalization group evolution of masses and mixing angles of Majorana neutrinos under the ``high scale mixing unification'' hypothesis. Assuming the unification of quark-lepton mixing angles at a high scale, we show that all the experimentally observed neutrino oscillation parameters can be obtained, within the $3\text{\ensuremath{-}}\ensuremath{\sigma}$ range, through the running of corresponding renormalization group equations provided neutrinos have the same charge parity and are quasidegenerate. One of the novel results of our analysis is that ${\ensuremath{\theta}}_{23}$ turns out to be nonmaximal and lies in the second octant. Furthermore, we derive new constraints on the allowed parameter space for the unification scale, supersymmetry breaking scale and $\mathrm{tan}\ensuremath{\beta}$, for which the high scale mixing unification hypothesis works.
18872395
Quarkonium polarization in nonrelativistic QCD and the quark-gluon plasma
We examine angular distributions of leptons arising from the decay of $J/\ensuremath{\psi}$ in inclusive hadroproduction. Taking into account feed-down contributions from ${\ensuremath{\chi}}_{1,2},$ a flat distribution emerges without fine tuning parameters. Changes in the ratio of direct to total $J/\ensuremath{\psi}$ cross sections would change this distribution significantly. Such angular distributions are, therefore, confirmatory tests of the $J/\ensuremath{\psi}$ suppression signal for the production of a quark-gluon plasma. Related effects are predicted for the $\ensuremath{\Upsilon}.$
119297909
High Scale Mixing Unification for Dirac Neutrinos
Starting with high scale mixing unification hypothesis, we investigate the renormalization group evolution of mixing parameters and masses for Dirac type neutrinos. Following this hypothesis, the PMNS mixing angles and phase are taken to be identical to the CKM ones at a unifying high scale. Then, they are evolved to a low scale using renormalization-group equations. The notable feature of this hypothesis is that renormalization group evolution with quasi-degenerate mass pattern can explain largeness of leptonic mixing angles even for Dirac neutrinos. The renormalization group evolution "naturally" results in a non-zero and small value of leptonic mixing angle $\theta_{13}$. One of the important predictions of this work is that the mixing angle $\theta_{23}$ is non-maximal and lies only in the second octant. We also derive constraints on the allowed parameter range for the SUSY breaking and unification scales for which this hypothesis works. The results are novel and can be tested by present and future experiments.
119240200
Properties of the SU(Nc) Gluon Plasma
We investigate the deconfinement transition in SU(Nc) gauge theories, and properties of the deconfined phase. A detailed lattice study of SU(4) and SU(6) gauge theories are conducted, and finite volume and cutoff effects on thermodynamic observables are studied. The scaling of the deconfinement transition point with lattice spacing is used to calculate the scale, Lambda_MSbar. The continuum estimates of the thermodynamic quantities are used to study properties of the gluon plasma. In particular, the approach to conformal limit is studied. We do not find any evidence of a strongly coupled, conformal phase in these theories.