125644280
Strong coupling from the tau-lepton hadronic width
The strong coupling is determined using a novel renormalization-group-summed perturbation theory and a non power renormalization-group-summed perturbation theory with a tamed large-order behaviour. In this talk, the main features of these two schemes are presented and are applied to the extraction of αs(M 2 τ ) from the hadronic decay width of the τ lepton. While the renormalizationgroup-summed perturbation theory leads to a value of strong coupling close to that from contourimproved perturbation theory, the non power renormalization-group-summed perturbation theory yields a value closer to the standard fixed-order perturbation theory.
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.
119234670
Gravitational collapse: expanding and collapsing regions
We investigate the expanding and collapsing regions by taking two well-known spherically symmetric spacetimes. For this purpose, the general formalism is developed by using Israel junction conditions for arbitrary spacetimes. This has been used to obtain the surface energy density and the tangential pressure. The minimal pressure provides the gateway to explore the expanding and collapsing regions. We take Minkowski and Kantowski-Sachs spacetimes and use the general formulation to investigate the expanding and collapsing regions of the shell.