RAT0455+1305: another pulsating hybrid sdB star

RAT0455+1305 was discovered during the Rapid Temporal Survey which aims in finding any variability on timescales of a few minutes to several hours. The star was found to be another sdBV star with one high amplitude mode and relatively long period. These features along with estimation of T_eff and log g makes this star very similar to Balloon 090100001. Encouraged by prominent results obtained for the latter star we have decided to perform white light photometry on RAT0455+1305. In 2009 we used the 1.5m telescope located in San Pedro Martir Observatory in Mexico. Fourier analysis confirmed the dominant mode found in the discovery data, uncovered another peak close to the dominant one, and three peaks in the low frequency region. This shows that RAT0455+1305 is another hybrid sdBV star pulsating in both p- and g-modes.Comment: Proceedings of The Fourth Meeting on Hot Subdwarf Stars and Related Objects held in China, 20-24 July 2009. Accepted for publication in Astrophysics & Space Scienc

Estimations for the Single Diffractive production of the Higgs boson at the Tevatron and the LHC

The single diffractive production of the standard model Higgs boson is computed using the diffractive factorization formalism, taking into account a parametrization for the Pomeron structure function provided by the H1 Collaboration. We compute the cross sections at next-to-leading order accuracy for the gluon fusion process, which includes QCD and electroweak corrections. The gap survival probability ($$) is also introduced to account for the rescattering corrections due to spectator particles present in the interaction, and to this end we compare two different models for the survival factor. The diffractive ratios are predicted for proton-proton collisions at the Tevatron and the LHC for the Higgs boson mass of $M_H$ = 120 GeV. Therefore, our results provide updated estimations for the diffractive ratios of the single diffractive production of the Higgs boson in the Tevatron and LHC kinematical regimes.Comment: 20 pages, 6 figures, 3 table

Type O pure radiation metrics with a cosmological constant

In this paper we complete the integration of the conformally flat pure radiation spacetimes with a non-zero cosmological constant $\Lambda$, and $\tau \ne 0$, by considering the case $\Lambda +\tau\bar\tau \ne 0$. This is a further demonstration of the power and suitability of the generalised invariant formalism (GIF) for spacetimes where only one null direction is picked out by the Riemann tensor. For these spacetimes, the GIF picks out a second null direction, (from the second derivative of the Riemann tensor) and once this spinor has been identified the calculations are transferred to the simpler GHP formalism, where the tetrad and metric are determined. The whole class of conformally flat pure radiation spacetimes with a non-zero cosmological constant (those found in this paper, together with those found earlier for the case $\Lambda +\tau\bar\tau = 0$) have a rich variety of subclasses with zero, one, two, three, four or five Killing vectors

Fractional Hamiltonian analysis of higher order derivatives systems

The fractional Hamiltonian analysis of 1+1 dimensional field theory is investigated and the fractional Ostrogradski's formulation is obtained. The fractional path integral of both simple harmonic oscillator with an acceleration-squares part and a damped oscillator are analyzed. The classical results are obtained when fractional derivatives are replaced with the integer order derivatives.Comment: 13 page

On the renormalization group flow of f(R)-gravity

We use the functional renormalization group equation for quantum gravity to construct a non-perturbative flow equation for modified gravity theories of the form $S = \int d^dx \sqrt{g} f(R)$. Based on this equation we show that certain gravitational interactions monomials can be consistently decoupled from the renormalization group (RG) flow and reproduce recent results on the asymptotic safety conjecture. The non-perturbative RG flow of non-local extensions of the Einstein-Hilbert truncation including $\int d^dx \sqrt{g} \ln(R)$ and $\int d^dx \sqrt{g} R^{-n}$ interactions is investigated in detail. The inclusion of such interactions resolves the infrared singularities plaguing the RG trajectories with positive cosmological constant in previous truncations. In particular, in some $R^{-n}$-truncations all physical trajectories emanate from a Non-Gaussian (UV) fixed point and are well-defined on all RG scales. The RG flow of the $\ln(R)$-truncation contains an infrared attractor which drives a positive cosmological constant to zero dynamically.Comment: 55 pages, 7 figures, typos corrected, references added, version to appear in Phys. Rev.

Lagrangian formulation of classical fields within Riemann-Liouville fractional derivatives

The classical fields with fractional derivatives are investigated by using the fractional Lagrangian formulation.The fractional Euler-Lagrange equations were obtained and two examples were studied.Comment: 9 page