Y(4260) as a mixed charmonium-tetraquark state

Using the QCD sum rule approach we study the Y(4260) state assuming that it can be described by a mixed charmonium-tetraquark current with $J^{PC}=1^{--}$ quantum numbers. For the mixing angle around $\theta \approx (53.0\pm 0.5)^{0}$, we obtain a value for the mass which is in good agreement with the experimental mass of the Y(4260). However, for the decay width we find the value \Ga_Y \approx (1.0\pm 0.2) MeV which is not compatible with the experimental value \Ga \approx (88\pm 23) MeV. Therefore, we conclude that, although we can explain the mass of the Y(4260), this state cannot be described as a mixed charmonium-tetraquark state since, with this assumption, we can not explain its decay width.Comment: 9 pages, 6 figure

Weak interactions and quasi-stable particle energy loss

We discuss the interplay between electromagnetic energy loss and weak interactions in the context of quasistable particle particle propagation through materials. As specific examples, we consider staus, where weak interactions may play a role, and taus, where they don't.Comment: 4 pages, 4 figures, to appear in the proceedings of the Second Workshop on TeV Particle Astrophysics (August 2006, Madison, WI

Anisotropic Lifshitz Point at O(ϵL2)O(\epsilon_L^2)

We present the critical exponents $\nu_{L2}$, $\eta_{L2}$ and $\gamma_{L}$ for an $m$-axial Lifshitz point at second order in an $\epsilon_{L}$ expansion. We introduced a constraint involving the loop momenta along the $m$-dimensional subspace in order to perform two- and three-loop integrals. The results are valid in the range $0 \leq m < d$. The case $m=0$ corresponds to the usual Ising-like critical behavior.Comment: 10 pages, Revte

Consequences of short range interactions between dark matter and protons in galaxy clusters

Protons gain energy in short range collisions with heavier dark matter particles (DMPs) of comparable velocity dispersion. We examine the conditions under which the heating of baryons by scattering off DMPs can offset radiative cooling in the cores of galaxy clusters. Collisions with a constant cross section independent of the relative velocity of the colliding particles, cannot produce stable thermal balance. In this case, avoiding an unrealistic increase of the central temperatures yields the upper bound on the cross-section, \sigma_xp<10^-25 cm^2 (m_x/m_p), where m_x and m_p are the DMP and proton mass, respectively. A stable balance, however, can be achieved for a power law dependence on the relative velocity, V, of the form \sigma_xp \propto V^a with a<-3. An advantage of this heating mechanism is that it preserves the metal gradients observed in clusters.Comment: 7 pages, new calculations include

Geographic patterns of vertebrate diversity and identification of relevant areas for conservation in Europe

The ‘EU Council conclusions on biodiversity post–2010′ re–enforced Europe’s commitment to halt biodiversity loss by 2020. Identifying areas of high–value for biodiversity conservation is an important issue to meet this target. We investigated the geographic pattern of terrestrial vertebrate diversity status in Europe by assessing the species richness, rarity, vulnerability (according to IUCN criteria), and a combined index of the three former for the amphibians, reptiles, bird and mammals of this region. We also correlated the value of all indices with climate and human influence variables. Overall, clear geographic gradients of species diversity were found. The combined biodiversity index indicated that high–value biodiversity areas were mostly located in the Mediterranean basin and the highest vulnerability was found in the Iberian peninsula for most taxa. Across all indexes, the proportion of variance explained by climate and human influence factors was moderate to low. The results obtained in this study have the potential to provide valuable support for nature conservation policies in Europe and, consequently, might contribute to mitigate biodiversity decline in this region