The distribution of geodesic excursions into the neighborhood of a cone singularity on a hyperbolic 2-orbifold

A generic geodesic on a finite area, hyperbolic 2-orbifold exhibits an infinite sequence of penetrations into a neighborhood of a cone singularity, so that the sequence of depths of maximal penetration has a limiting distribution. The distribution function is the same for all such surfaces and is described by a fairly simple formula.Comment: 20 page

Quantum teardrops

Algebras of functions on quantum weighted projective spaces are introduced, and the structure of quantum weighted projective lines or quantum teardrops are described in detail. In particular the presentation of the coordinate algebra of the quantum teardrop in terms of generators and relations and classification of irreducible *-representations are derived. The algebras are then analysed from the point of view of Hopf-Galois theory or the theory of quantum principal bundles. Fredholm modules and associated traces are constructed. C*-algebras of continuous functions on quantum weighted projective lines are described and their K-groups computed.Comment: 18 page

Detecting the intermediate-mass Higgs boson through the associate production channel pp --> t + anti-t + H + X

We examine the detection of the intermediate-mass Higgs boson (IMH) at LHC through the associate production channel pp-->t+(anti-t)+H+X-->l+photon+ photon+X'. It is shown that by applying kinematic cuts or b-tagging on the final state jets, the main backgrounds of W(-->l+nu)+photon+photon+(n-jet) can be reduced substantially without significant loss of signals. It is possible to detect the Higgs boson at LHC through the pp-->t+(anti-t)+H+X channel using a modest photon detector with mass resolution of about 3% of the photon pair invariant mass.Comment: 10 pages, standard LaTex fil

Equivariant comparison of quantum homogeneous spaces

We prove the deformation invariance of the quantum homogeneous spaces of the q-deformation of simply connected simple compact Lie groups over the Poisson-Lie quantum subgroups, in the equivariant KK-theory with respect to the translation action by maximal tori. This extends a result of Neshveyev-Tuset to the equivariant setting. As applications, we prove the ring isomorphism of the K-group of Gq with respect to the coproduct of C(Gq), and an analogue of the Borsuk-Ulam theorem for quantum spheres.Comment: 21 page

Parity-violating asymmetry in γd→n⃗p\gamma d \to \vec{n}p with a pionless effective theory

Nuclear parity violation is studied with polarized neutrons in the photodisintegration of the deuteron at low energies. A pionless effective field theory with di-baryon fields is used for the investigation. Hadronic weak interactions are treated by parity-violating di-baryon-nucleon-nucleon vertices, which have undetermined coupling contants. A parity-violating asymmetry in the process is calculated for the incident photon energy up to 30 MeV. If experimental data for the parity-violating asymmetry become available in the future, we will be able to determine the unknown coupling contants in the parity-violating vertices.Comment: 4 pages. A contribution to APFB2011, August 22-26, 2011, Seoul, Kore

Demonstration of Feed-Forward Control for Linear Optics Quantum Computation

One of the main requirements in linear optics quantum computing is the ability to perform single-qubit operations that are controlled by classical information fed forward from the output of single photon detectors. These operations correspond to pre-determined combinations of phase corrections and bit-flips that are applied to the post-selected output modes of non-deterministic quantum logic devices. Corrections of this kind are required in order to obtain the correct logical output for certain detection events, and their use can increase the overall success probability of the devices. In this paper, we report on the experimental demonstration of the use of this type of feed-forward system to increase the probability of success of a simple non-deterministic quantum logic operation from approximately 1/4 to 1/2. This logic operation involves the use of one target qubit and one ancilla qubit which, in this experiment, are derived from a parametric down-conversion photon pair. Classical information describing the detection of the ancilla photon is fed-forward in real-time and used to alter the quantum state of the output photon. A fiber optic delay line is used to store the output photon until a polarization-dependent phase shift can be applied using a high speed Pockels cell

ATIC and PAMELA Results on Cosmic e^\pm Excesses and Neutrino Masses

Recently the ATIC and PAMELA collaborations released their results which show the abundant e^\pm excess in cosmic rays well above the background, but not for the \bar{p}. Their data if interpreted as the dark matter particles' annihilation imply that the new physics with the dark matter is closely related to the lepton sector. In this paper we study the possible connection of the new physics responsible for the cosmic e^\pm excesses to the neutrino mass generation. We consider a class of models and do the detailed numerical calculations. We find that these models can natually account for the ATIC and PAMELA e^\pm and \bar{p} data and at the same time generate the small neutrino masses.Comment: 7 pages, 5 figures. Published version with minor corrections and more reference

First-Principles Calculation of the Superconducting Transition in MgB2 within the Anisotropic Eliashberg Formalism

We present a study of the superconducting transition in MgB2 using the ab-initio pseudopotential density functional method and the fully anisotropic Eliashberg equation. Our study shows that the anisotropic Eliashberg equation, constructed with ab-initio calculated momentum-dependent electron-phonon interaction and anharmonic phonon frequencies, yields an average electron-phonon coupling constant lambda = 0.61, a transition temperature Tc = 39 K, and a boron isotope-effect exponent alphaB = 0.31 with a reasonable assumption of mu* = 0.12. The calculated values for Tc, lambda, and alphaB are in excellent agreement with transport, specific heat, and isotope effect measurements respectively. The individual values of the electron-phonon coupling lambda(k,k') on the various pieces of the Fermi surface however vary from 0.1 to 2.5. The observed Tc is a result of both the raising effect of anisotropy in the electron-phonon couplings and the lowering effect of anharmonicity in the relevant phonon modes.Comment: 4 pages, 3 figures, 1 tabl

Microstructure and Optical Properties of Tantalum Modified TiO2 Thin Films Prepared by the Sol-Gel Process

Tantalum doped TiO2 thin films ((TiO2)(1-x) (Ta2O5)(x), x = 0, 0.1%, 0.3%, 0.5%, 0.8%) were prepared on ITO-coated substrates by means of the sol gel method and spin coating technology followed by rapid thermal annealing treatment (RTA). The effects of various processing parameters, including Ta content (x = 0-0.8%) and annealing temperature, on the growth and properties of thin films were investigated. Structural characteristics by X-ray diffraction analysis indicated that the doping of Ta2O5 in the TiO2 without change the anatase structure of TiO2 thin films. The optical transmittance of (TiO2)(1-x) (Ta2O5) thin films decrease from 50% down to 20% with increasing the Ta2O5 concentrations from x = 0.00 to x = 0.8%. The absorption coefficient shows energy gap were decreased with increasing Ta2O5 content from 2.932 eV for x = 0.00 to 2.717 eV for x = 0.8%. Doping TiO2 with Ta2O5 can lower its band gap and shift its optical response to the visible region

Leptogenesis Bound on Spontaneous Symmetry Breaking of Global Lepton Number

We propose a new class of leptogenesis bounds on the spontaneous symmetry breaking of global lepton number. These models have a generic feature of inducing new lepton number violating interactions, due to the presence of the Majorons. We analyzed the singlet Majoron model with right-handed neutrinos and find that the lepton number should be broken above 10^5 GeV to realize a successful leptogenesis because the annihilations of the right-handed neutrinos into the massless Majorons and into the standard model Higgs should go out of equilibrium before the sphaleron process is over. We then argue that this type of leptogenesis constraint should exist in the singlet-triplet Majoron models as well as in a class of R-parity violating supersymmetric Majoron models.Comment: 4 pages, 2 figure