Do Local Governments Engage in Strategic Property-Tax Competition?

This paper uses spatial econometric methods to investigate property-tax competition among local governments. The theoretical model is drawn from the literature on tax competition, in which local jurisdictions choose property-tax rates taking into account the migration of mobile capital in response to tax differentials. Using a "spatial lag" econometric model, the paper estimates the reaction function of the representative community, which relates the community's property-tax rate to its own characteristics and to the tax rates in competing communities. A nonzero reaction-function slope indicates the presence of strategic interaction in the choice of tax rates. The estimation uses cross-section data on property taxes and other socio-economic variables for cities in the Boston metropolitan area. The results, which are presented for two periods before and after imposition of Proposition 2 1/2 (a tax limitation measure), indicate the presence of strategic interaction.

Quasinormal Modes and Stability Criterion of Dilatonic Black Hole in 1+1 and 4+1 Dimensions

We study the stability of black holes that are solutions of the dilaton gravity derived from string-theoretical models in two and five dimensions against to scalar field perturbations, using the Quasinormal Modes (QNMs) approach. In order to find the QNMs corresponding to a black hole geometry, we consider perturbations described by a massive scalar field non-minimally coupled to gravity. We find that the QNM's frequencies turn out to be pure imaginary leading to purely damped modes, that is in agreement with the literature of dilatonic black holes. Our result exhibits the unstable behavior of the considered geometry against the scalar perturbations. We consider both the minimal coupling case, i.e., for which the coupling parameter $\zeta$ vanishes, and the case $\zeta={1/4}$.Comment: sevarl changes, some reference was added, 10 pages, 4 figure

Quasinormal modes and Stability Analysis for 4-dimensional Lifshitz Black Hole

We study the Lifshitz black hole in 4-dimensions with dynamical exponent z=2 and we calculate analytically the quasinormal modes of scalar perturbations. These quasinormal modes allows to study the stability of the Lifshitz black hole and we have obtained that Lifshitz black hole is stable.Comment: 7 pages, 2 figures. arXiv admin note: text overlap with arXiv:1205.058

Production of Single Heavy Charged Leptons at a Linear Collider

A sequential fourth generation of quarks and leptons is allowed by precision electroweak constraints if the mass splitting between the heavy quarks is between 50 and 80 GeV. Although heavy quarks can be easily detected at the LHC, it is very difficult to detect a sequential heavy charged lepton, L, due to large backgrounds. Should the L mass be above 250 GeV, it can not be pair-produced at a 500 GeV ILC. We calculate the cross section for the one-loop process e+e- -> L tau. Although the cross section is small, it may be detectable. We also consider contributions from the two Higgs doublet model and the Randall-Sundrum model, in which case the cross section can be substantially higher.Comment: 14 pages, 7 figure

IceCube3--a new window on the Universe

This paper gives an overview of the scientific goals of IceCube with an emphasis on the importance of atmospheric neutrinos. Status and schedule for completing the detector are presented.Comment: 13 pages, 6 figures, to appear in A.I.P. Conf. Proceedings, 3rd Latin American School on Cosmic Rays, Arequipa, Peru, September, 200

Quantum process reconstruction based on mutually unbiased basis

We study a quantum process reconstruction based on the use of mutually unbiased projectors (MUB-projectors) as input states for a D-dimensional quantum system, with D being a power of a prime number. This approach connects the results of quantum-state tomography using mutually unbiased bases (MUB) with the coefficients of a quantum process, expanded in terms of MUB-projectors. We also study the performance of the reconstruction scheme against random errors when measuring probabilities at the MUB-projectors.Comment: 6 pages, 1 figur

A clean signal for a top-like isosinglet fermion at the Large Hadron Collider

We predict a clean signal at the Large Hadron Collider ($\sqrt s)$=14 TeV for a scenario where there is a top-like, charge +2/3 vectorlike isosinglet fermion. Such a quark, via mixing with the standard model top, can undergo decays via both flavour-changing Z-boson coupling and flavour-changing Yukawa interactions. We concentrate on the latter channel, and study the situation where, following its pair-production, the heavy quark pair gives rise to two tops and two Higgs boson. We show that the case where each Higgs decays in the $b\bar{b}$ channel, there can be a rather distinct and background-free signal that can unveil the existence of the vectorlike isosinglet quark of this kind.Comment: 14 pages, 5 figures, 4 table

Top quark tensor couplings

We compute the real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the $tbW$ vertex in the Standard Model (SM). For both tensorial couplings we find that the real part of the electroweak SM correction is close to 10$$ of the leading contribution given by the QCD gluon exchange. We also find that the electroweak real and imaginary parts for the anomalous right coupling are almost of the same order of magnitude. The one loop SM prediction for the real part of the left coupling is close to the 3$\sigma$ discovery limit derived from $b\rightarrow s \gamma$. Besides, taking into account that the predictions of new physics interactions are also at the level of a few percents when compared with the one loop QCD gluon exchange, these electroweak corrections should be taken into account in order to disentangle new physics effects from the standard ones. These anomalous tensorial couplings of the top quark will be investigated at the LHC in the near future where sensitivity to these contributions may be achieved.Comment: 16 pages, 2 figure

Probing anomalous tbW couplings in single-top production using top polarization at the Large Hadron Collider

We study the sensitivity of the Large Hadron Collider (LHC) to anomalous tbW couplings in single-top production in association with a W^- boson followed by semileptonic decay of the top. We calculate top polarization and the effects of these anomalous couplings to it at two centre-of-mass (cm) energies of 7 TeV and 14 TeV. As a measure of top polarization, we look at various laboratory frame distributions of its decay products, viz., lepton angular and energy distributions and b-quark angular distributions, without requiring reconstruction of the rest frame of the top, and study the effect of anomalous couplings on these distributions. We construct certain asymmetries to study the sensitivity of these distributions to anomalous tbW couplings. We find that 1\sigma limits on real and imaginary parts of the dominant anomalous coupling Ref_{2R} which may be obtained by utilizing these asymmetries at the LHC with cm energy of 14 TeV and an integrated luminosity of 10 fb^{-1} will be significantly better than the expectations from direct measurements of cross sections and some other variables at the LHC and over an order of magnitude better than the indirect limits.Comment: 25 pages, 34 figure

On the generation of asymmetric warps in disk galaxies

The warps in many spiral galaxies are now known to asymmetric. Recent sensitive observations have revealed that asymmetry of warps may be the norm rather than exception. However there exists no generic mechanism to generate these asymmetries in warps. We have derived the dispersion relation in a compact form for the S-shaped warps(described by the m=1 mode) and the bowl-shaped distribution(described by the m=0 mode) in galactic disk embedded in a dark matter halo. We then performed the numerical modal analysis and used the linear and time-dependent superposition principle to generate asymmetric warps in the disk. On doing the modal analysis we find the frequency of the $m=0$ mode is much larger than that of the $m=1$ mode. The linear and time-dependent superposition of these modes with their unmodulated amplitudes(that is, the coefficients of superposition being unity) results in an asymmetry in warps of ~ 20 - 40 %, whereas a smaller coefficient for the m=0 mode results in a smaller asymmetry. The resulting values agree well with the recent observations. We study the dependence of the asymmetry index on the dark matter halo parameters. This approach can also naturally produce U-shaped warps and L-shaped warps. We show that a rich variety of possible asymmetries in the z-distribution of the spiral galaxies can naturally arise due to a dynamical wave interference between the first two bending modes(i.e. m=0 and m=1) in the disk. This is a simple but general method for generating asymmetric warps that is independent of how the individual modes arise in the disk.Comment: Accepted for publication in A &