Pulsar Kicks Induced by Spin Flavor Oscillations of Neutrinos in Gravitational Fields

The origin of pulsar kicks is reviewed in the framework of the spin-flip conversion of neutrinos propagating in the gravitational field of a magnetized protoneutron star. We find that for a mass in rotation with angular velocity {\bbox \omega}, the spin connections entering in the Dirac equation give rise to the coupling term {\bbox \omega}\cdot {\bf p}, being ${\bf p}$ the neutrino momentum. Such a coupling can be responsible of pulsar kicks owing to the neutrino emission asymmetry generated by the relative orientation of ${\bf p}$ with respect to {\bbox \omega}. For our estimations, the large non standard neutrino magnetic momentum, $\mu_\nu \lesssim 10^{-11}\mu_B$, is considered.Comment: 8 pages, no figures. Changed content and references adde

Rigid Limit in N=2 Supergravity and Weak-Gravity Conjecture

We analyze the coupled N=2 supergravity and Yang-Mills system using holomorphy, near the rigid limit where the former decouples from the latter. We find that there appears generically a new mass scale around g M_{pl} where g is the gauge coupling constant and M_{pl} is the Planck scale. This is in accord with the weak-gravity conjecture proposed recently. We also study the scale dependence of the gauge theory prepotential from its embedding into supergravity.Comment: 17 pages, minor correction

Surface Shubnikov-de Hass oscillations and non-zero Berry phases of the topological hole conduction in Tl1−x_{1-x}Bi1+x_{1+x}Se2_2

We report the observation of two-dimensional Shubnikov-de Hass (SdH) oscillations in the topological insulator Tl$_{1-x}$Bi$_{1+x}$Se$_2$. Hall effect measurements exhibited electron-hole inversion in samples with bulk insulating properties. The SdH oscillations accompanying the hole conduction yielded a large surface carrier density of $n_{\rm{s}}=5.1 \times10^{12}$/cm$^2$, with the Landau-level fan diagram exhibiting the $\pi$ Berry phase. These results showed the electron-hole reversibility around the in-gap Dirac point and the hole conduction on the surface Dirac cone without involving the bulk metallic conduction.Comment: 5 pages, 4 figure

Superconformal Algebras and Mock Theta Functions

It is known that characters of BPS representations of extended superconformal algebras do not have good modular properties due to extra singular vectors coming from the BPS condition. In order to improve their modular properties we apply the method of Zwegers which has recently been developed to analyze modular properties of mock theta functions. We consider the case of N=4 superconformal algebra at general levels and obtain the decomposition of characters of BPS representations into a sum of simple Jacobi forms and an infinite series of non-BPS representations. We apply our method to study elliptic genera of hyper-Kahler manifolds in higher dimensions. In particular we determine the elliptic genera in the case of complex 4 dimensions of the Hilbert scheme of points on K3 surfaces K^{[2]} and complex tori A^{[[3]]}.Comment: 28 page

Comments on Non-holomorphic Modular Forms and Non-compact Superconformal Field Theories

We extend our previous work arXiv:1012.5721 [hep-th] on the non-compact N=2 SCFT_2 defined as the supersymmetric SL(2,R)/U(1)-gauged WZW model. Starting from path-integral calculations of torus partition functions of both the axial-type (`cigar') and the vector-type (`trumpet') models, we study general models of the Z_M-orbifolds and M-fold covers with an arbitrary integer M. We then extract contributions of the degenerate representations (`discrete characters') in such a way that good modular properties are preserved. The `modular completion' of the extended discrete characters introduced in arXiv:1012.5721 [hep-th] are found to play a central role as suitable building blocks in every model of orbifolds or covering spaces. We further examine a large M-limit (the `continuum limit'), which `deconstructs' the spectral flow orbits while keeping a suitable modular behavior. The discrete part of partition function as well as the elliptic genus is then expanded by the modular completions of irreducible discrete characters, which are parameterized by both continuous and discrete quantum numbers modular transformed in a mixed way. This limit is naturally identified with the universal cover of trumpet model. We finally discuss a classification of general modular invariants based on the modular completions of irreducible characters constructed above.Comment: 1+40 pages, no figure; v2 some points are clarified with respect to the `continuum limit', typos corrected, to appear in JHEP; v3 footnotes added in pages 18, 23 for the relation with arXiv:1407.7721[hep-th

Precise determination of two-carrier transport properties in the topological insulator TlBiSe2_2

We report the electric transport study of the three-dimensional topological insulator TlBiSe$_2$. We applied a newly developed analysis procedure and precisely determined two-carrier transport properties. Magnetotransport properties revealed a multicarrier conduction of high- and low-mobility electrons in the bulk, which was in qualitative agreement with angle-resolved photoemission results~[K. Kuroda $et~al.$, Phys. Rev. Lett. $\bm{105}$, 146801 (2010)]. The temperature dependence of the Hall mobility was explained well with the conventional Bloch-Gr{\"u}neisen formula and yielded the Debye temperature $\varTheta_{\rm{D}}=113 \pm 14$~K. The results indicate that the scattering of bulk electrons is dominated by acoustic phonons.Comment: 6 pages, 5 figures, to be published in Physical Review

High Sensitivity Search for v_e’s from the Sun and Other Sources at KamLAND

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for ν̅ _e’s in the energy range 8.3 < E_(ν̅e) < 14.8  MeV. No candidates were found for an expected background of 1.1±0.4 events. This result can be used to obtain a limit on ν̅_e fluxes of any origin. Assuming that all ν̅_e flux has its origin in the Sun and has the characteristic ^8B solar ν_e energy spectrum, we obtain an upper limit of 3.7×10^2  cm^(-2) ^(s-1) (90% C.L.) on the ν̅_e flux. We interpret this limit, corresponding to 2.8×10^(-4) of the standard solar model ^8B ν_e flux, in the framework of spin-flavor precession and neutrino decay models

Towards A Topological G_2 String

We define new topological theories related to sigma models whose target space is a 7 dimensional manifold of G_2 holonomy. We show how to define the topological twist and identify the BRST operator and the physical states. Correlation functions at genus zero are computed and related to Hitchin's topological action for three-forms. We conjecture that one can extend this definition to all genus and construct a seven-dimensional topological string theory. In contrast to the four-dimensional case, it does not seem to compute terms in the low-energy effective action in three dimensions.Comment: 15 pages, To appear in the proceedings of Cargese 2004 summer schoo

Large spin-orbit splitting and weakly-anisotropic superconductivity revealed with single-crystalline noncentrosymmetric CaIrSi3

We report normal and superconducting properties of the Rashba-type noncentrosymmetric com- pound CaIrSi3, using single crystalline samples with nearly 100% superconducting volume fraction. The electronic density of states revealed by the hard x-ray photoemission spectroscopy can be well explained by the relativistic first-principle band calculation. This indicates that strong spin-orbit interaction indeed affects the electronic states of this compound. The obtained H - T phase diagram exhibits only approximately 10% anisotropy, indicating that the superconducting properties are almost three dimensional. Nevertheless, strongly anisotropic vortex pinning is observed.Comment: 8 pages, 6 figures, 1 table, accepted for publication in Phys. Rev.