209866467
CP violation in the Cabibbo suppressed decay tau ---> K pi tau-neutrino with polarized tau leptons
118428627
Leptogenesis in a seesaw model with Fritzsch-type lepton mass matrices
We investigate how the baryon asymmetry of our Universe via leptogenesis can be achieved within the framework of the seesaw model with Fritzsch-type lepton mass matrices proposed by Fukugita et al. We study the cases with $CP$-violating phases in charged-lepton Yukawa matrix, however, with and without Dirac neutrino Yukawa phases. We consider both flavor-independent and flavor-dependent leptogenesis, and demonstrate how they lead to different amounts of lepton asymmetries in detail. In particular, it is shown that flavor-dependent leptogenesis in this model can be achieved only for very tiny or zero values of $CP$ phases in Dirac neutrino Yukawa matrix at the grand unified theory scale. In addition to the $CP$ phases, for successful leptogenesis in the model it is required that the degeneracy of the heavy Majorana neutrino mass spectrum should be broken and we also show that the breakdown of the degeneracy can be radiatively induced.
119056575
mu- tau Symmetry and Radiatively Generated Leptogenesis
We consider a $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetry in neutrino sectors realized at the GUT scale in the context of a seesaw model. In our scenario, the exact $\ensuremath{\mu}\ensuremath{-}\ensuremath{\tau}$ symmetry realized in the basis where the charged lepton and heavy Majorana neutrino mass matrices are diagonal leads to vanishing lepton asymmetries. We find that, in the minimal supersymmetric extension of the seesaw model with large $\mathrm{tan}﻿\ensuremath{\beta}$, the renormalization group (RG) evolution from the GUT scale to seesaw scale can induce a successful leptogenesis even without introducing any symmetry breaking terms by hand, whereas such RG effects lead to tiny deviations of ${\ensuremath{\theta}}_{23}$ and ${\ensuremath{\theta}}_{13}$ from $\ensuremath{\pi}/4$ and zero, respectively. It is shown that the right amount of the baryon asymmetry ${\ensuremath{\eta}}_{B}$ can be achieved via so-called resonant leptogenesis, which can be realized at rather low seesaw scale with large $\mathrm{tan}﻿\ensuremath{\beta}$ in our scenario so that the well-known gravitino problem is safely avoided.
867013
Quark-Lepton Complementarity with Renormalization Effects through Threshold Corrections
The recent experimental measurements of the solar neutrino mixing angle θ sol and the Cabibbo mixing angle θ C reveal a surprising relation, θ sol+ θ C ’ π 4 . While this empirical relation has been interpreted as a support of the idea of grand unification, it may be merely accidental in the sense that reproducing the relation at a low energy in the framework of grand unification may depend strongly on the renormalization effects whose size can vary with the choice of parameter space. We note that the lepton mixing matrix derived from quark-lepton unification can lead to a shift of the complementarity relation at low energy. While the renormalization group effects generally lead to additive contribution on top of the shift, we show that the threshold corrections which may exist in some intermediate scale new physics such as supersymmetric standard model can diminish it, so we can achieve the complementarity relation at a low energy.
6266850
Systematic Investigation of Possibilities for New Physics Effects in b → s Penguin Processes
Although recent experimental results in b → s penguin process seem to be roughly consistent with the standard model predictions, there may be still large possibilities of new physics hiding in these processes. Therefore, here we investigate systematically the potential new physics effects that may appear in time-dependent CP asymmetries of B → φK 0 , B → η � K 0 and B → K 0 π 0 decay modes, by classifying the cases for the values of the mixinginduced indirect CP asymmetries, SφK0 ,S ηK0 ,S K0π0 which are compared to SJ/ψK0 .W e also show that several Bs decay modes may help to resolve the ambiguities in such an analysis. Through combining analysis with the time-dependent CP asymmetries of Bs decay modes such as Bs → φη � , Bs → η � π 0 and Bs → K 0 K 0
118146740
The intrinsic and oscillated astrophysical neutrino flavor ratios
The pp interactions taking place in the cosmos around us are a source of the astrophysical neutrinos of all the three flavors. In these interactions, the electron and the muon neutrinos mainly come from the production and the decay of the \pi^{\pm} mesons, whereas the tau neutrinos mainly come from the production and the decay of the D^{\pm}_{S} mesons. We estimate the three intrinsic neutrino flavor ratios for 1 GeV 10^{-10} in the presence of neutrino oscillations, where L is the distance to the astrophysical neutrino source in units of parsecs.
126185345
Invariant-mass distribution of c anti-c in Upsilon(1S) ---> c anti-c + X
209835401
Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton–proton collision data with the ATLAS detector
A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb(-1) of proton-proton collision data at root s = 7 TeV recorded with the ...
15236719
Global and local D-vortices
Codimension-two objects on a system of brane-antibrane are studied in the context of Born-Infeld type effective field theory with a complex tachyon and U(1) × U(1) gauge fields. When the radial electric field is turned on in D2 ¯ D2, we find static regular global and local D-vortex solutions which could be candidates of straight cosmic D-strings in a superstring theory. A natural extension to DF-strings is briefly discussed.
15929904
The Spatial Distribution of the Hard X-Ray Spectral Index and the Local Magnetic Reconnection Rate
The rare phenomenon of ribbon-like hard X-ray (HXR) sources up to 100 keV found in the 2005 May 13 M8.0 flare observed with the Reuven Ramaty High Energy Solar Spectroscopic Imager provides detailed information on the spatial distribution of flare HXR emission. In this Letter, we further investigate the characteristics of HXR emission in this event using imaging spectroscopy, from which we obtain spatially resolved HXR spectral maps during the flare impulsive phase. As a result we found, along a flare ribbon, an anticorrelation relationship between the local HXR flux and the local HXR spectral index. We suggest that this can be regarded as a spatial analog of the well-known temporal soft-hard-soft spectral evolution pattern of the integrated HXR flux. We also found an anticorrelation between the HXR spectral index and the local electric field along the ribbon, which suggests electron acceleration by the electric field during flares.
120805024
Search for First Generation Scalar Leptoquarks in pp Collisions at $\sqrt{s}=7$ TeV with the ATLAS Detector
We report a search for first generation scalar leptoquarks using 1.03 fb−1 of proton–proton collisions data produced by the Large Hadron Collider at and recorded by the ATLAS experiment. Leptoquarks are sought via their decay into an electron or neutrino and a quark, producing events with two oppositely charged electrons and at least two jets, or events with an electron, missing transverse momentum and at least two jets. Control data samples are used to validate background predictions from Monte Carlo simulation. In the signal region, the observed event yields are consistent with the background expectations. We exclude at 95% confidence level the production of first generation scalar leptoquark with masses when assuming the branching fraction of a leptoquark to a charged lepton is equal to 1.0 (0.5).