Quark and lepton masses and mixing in the landscape

Even if quark and lepton masses are not uniquely predicted by the fundamental theory, as may be the case in the string theory landscape, nevertheless their pattern may reveal features of the underlying theory. We use statistical techniques to show that the observed masses appear to be representative of a scale invariant distribution, rho(m) ~ 1/m. If we extend this distribution to include all the Yukawa couplings, we show that the resulting CKM matrix elements typically show a hierarchical pattern similar to observations. The Jarlskog invariant measuring the amount of CP violation is also well reproduced in magnitude. We also apply this framework to neutrinos using the seesaw mechanism. The neutrino results are ambiguous, with the observed pattern being statistically allowed even though the framework does not provide a natural explanation for the observed two large mixing angles. Our framework highly favors a normal hierarchy of neutrino masses. We also are able to make statistical predictions in the neutrino sector when we specialize to situations consistent with the known mass differences and two large mixing angles. Within our framework, we show that with 95% confidence the presently unmeasured MNS mixing angle sin theta_{13} is larger than 0.04 and typically of order 0.1. The leptonic Jarlskog invariant is found to be typically of order 10^{-2} and the magnitude of the effective Majorana mass m_{ee} is typically of order 0.001 eV.Comment: 32 pages, 17 figures, some references adde

Fibers on a graph with local load sharing

We study a random fiber bundle model with tips of the fibers placed on a graph having co-ordination number 3. These fibers follow local load sharing with uniformly distributed threshold strengths of the fibers. We have studied the critical behaviour of the model numerically using a finite size scaling method and the mean field critical behaviour is established. The avalanche size distribution is also found to exhibit a mean field nature in the asymptotic limit.Comment: 9 pages, 6 figures, To appear in International Journal of Modern Physics

N—H⋯N hydrogen bonding in 4,6-diphenyl-2-pyrimidinylamine isolated from the plant Justicia secunda (Acanthaceae)

The title compound, C₁₆H₁₃N₃, isolated from Justicia secunda (Acanthaceae), comprises two molecules (which differ slightly in conformation) in the asymmetric unit of space group P\overline 1. Intermolecular Namino-H...Npyrm interactions (Npyrm is a pyrimidine ring N atom) involve only one of the two donor amino H atoms and pyrimidine N atoms per molecule, forming dimeric units via R²₂(8) rings, with N...N distances of 3.058 (2) and 3.106 (3) Å, and N-H...N angles of 172.7 (18) and 175.8 (17)°. The dimers are linked by C-H...π(arene) contacts, with an H...centroid distance of 2.77 Å and a C-H...centroid angle of 141°

A Classical Treatment of Island Cosmology

Computing the perturbation spectrum in the recently proposed Island Cosmology remains an open problem. In this paper we present a classical computation of the perturbations generated in this scenario by assuming that the NEC-violating field behaves as a classical phantom field. Using an exactly-solvable potential, we show that the model generates a scale-invariant spectrum of scalar perturbations, as well as a scale-invariant spectrum of gravitational waves. The scalar perturbations can have sufficient amplitude to seed cosmological structure, while the gravitational waves have a vastly diminished amplitude.Comment: 8 pages, 1 figur

Enhanced signal of astrophysical tau neutrinos propagating through Earth

Earth absorbs \nue and \numu of energies above about 100 TeV. As is well-known, although \nutau will also disappear through charged-current interactions, the \nutau flux will be regenerated by prompt tau decays. We show that this process also produces relatively large fluxes of secondary \nube and \nubmu, greatly enhancing the detectability of the initial \nutau. This is particularly important because at these energies \nutau is a significant fraction of the expected astrophysical neutrino flux, and only a tiny portion of the atmospheric neutrino flux.Comment: Four pages, two inline figure

Non-isotropy in the CMB power spectrum in single field inflation

Contaldi et al. [1] have suggested that an initial period of kinetic energy domination in single field inflation may explain the lack of CMB power at large angular scales. We note that in this situation it is natural that there also be a spatial gradient in the initial value of the inflaton field, and that this can provide a spatial asymmetry in the observed CMB power spectrum, manifest at low multipoles. We investigate the nature of this asymmetry and comment on its relation to possible anomalies at low multipoles.Comment: 25 pages, 12 figures. In this revised version, we include the Integrated Sachs-Wolfe effect, which was missing from the original. This modifies some results in the low multipoles. The comparison with experiment is slightly better but the change is not statistically significan