119235806
CP-odd weak basis invariants for neutrino mass matrices with a texture zero and a vanishing minor
We construct the CP-odd weak basis invariants in the flavor basis for all the phenomenologically viable neutrino mass matrices with a texture zero and a vanishing minor and, also, find the necessary and sufficient conditions for CP invariance. We examine the interrelationships between different CP-odd weak basis invariants for these texture structures and investigate their implications for Dirac- and Majorana-type CP violation.
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.
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.
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.
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.
117945191
Degeneracies of Neutrino Mass Matrices with two Texture Zeros
We examine the phenomenological implications of the neutrino mass matrices with two texture zeros, especially, in relation to their degeneracies.
120000887
Angular resolution of the Ooty EAS array based on UHE gamma rays from Her X-1
The angular resolution of an extensive air shower array for studies on cosmic sources of ultra-high-energy gamma rays has been determined by most of the experimental groups generally by inter-comparison between sub-arrays, in the absence of the knowledge of any steady and strong discrete source. The sub-arrays have been obtained mostly by dividing the main array into two arrays, one containing the even-numbered detectors and another having the odd-numbered detectors. Using this method the angular resolution of the 24-detector array operated at Ooty during 1984-7 was estimated to be about 1.5 degrees . Recently the Ooty group has reported the detection of four episodes of pulsed emission of ultra-high-energy photons from Her X-1 which have been shown to be phase locked with a period of 1.2357701 s. The authors have made a study of the angular resolution for the Ooty array using this signal from Her X-1 which had a relatively low background. The angular resolution of the array has been determined to be 1.6 degrees +or-0.4 degrees . This is the first direct measurement of angular resolution of an air shower array using a point source of ultra-high-energy photons.
5816018
Variational principle model for the nuclear caloric curve
Following the lead of a recent work, I perform a variational principle model calculation for the nuclear caloric curve. A Skyrme-type interaction with and without momentum dependence is used. The calculation is done for a large nucleus, i.e., in the nuclear matter limit. Thus I address the issue of volume fragmentation only. Nonetheless, the results are similar to the previous, largely phenomenological calculation for a finite nucleus. I find that the onset of fragmentation can be sudden as a function of temperature or excitation energy.
123088134
Proton optical model potential at sub-Coulomb energies for medium weight nuclei
The ($p$,$n$) reaction excitation functions for eleven nuclei from $A=45 \mathrm{to} 80$ measured at proton energies below \ensuremath{\sim}5 MeV have been analyzed utilizing the optical model. The real potential parameters used in the present work have been obtained by suitably combining the proton optical model parameters determined between 3 and 60 MeV. Large energy dependence of the real potential at energies below 5 MeV has been observed. The imaginary potential depths determined in the present analysis exhibit an anomalous behavior when plotted as a function of mass number $A$. By utilizing the low and intermediate energy proton data, an attempt has been made to obtain a "global" set of optical parameters in the proton energy range between 4 and 180 MeV, for medium weight nuclei.
120871108
Can charge correlations be used to signal the formation of a quark-gluon plasma?
We investigate short-range charge anticorrelations in nucleus-nucleus collisions whose suppresion could signal the presence of a quark-gluon plasma. We compute the charge correlations under some minimal assumptions about model parameters, and find that the results are not very sensitive to different parameters of the model.
118889489
Valence quarks in the QCD plasma: Quark number susceptibilities and screening
We investigate the quark sector of quenched QCD for $1.5l~{T/T}_{c}l~3$ in the continuum limit, using two different lattice discretizations of quarks and extrapolating from lattice spacings between $1/4T$ and $1/14T.$ At these temperatures, the flavor off-diagonal susceptibility ${\ensuremath{\chi}}_{\mathrm{ud}}{/T}^{2}$ is compatible with zero at each lattice spacing, and hence also in the continuum limit. In the continuum limit, the light quark susceptibilities are about 10% less than the ideal gas results even at the highest T, in agreement with hard thermal loop predictions but marginally below a resummed perturbative computation. For the mass range appropriate to the strange quark, the flavor diagonal susceptibility is significantly smaller. Our estimate of the Wroblewski parameter is compatible with observations at BNL RHIC and CERN SPS. The continuum limit of screening masses in all (local) quark bilinears is very close to the ideal gas results.