Cosmological constraints on neutrino plus axion hot dark matter: Update after WMAP-5

We update our previous constraints on two-component hot dark matter (axions and neutrinos), including the recent WMAP 5-year data release. Marginalising over sum m_nu provides m_a < 1.02 eV (95% C.L.) for the axion mass. In the absence of axions we find sum m_nu < 0.63 eV (95% C.L.).Comment: 4 pages, 1 figure, uses iopart.cls; v2 matches published versio

Simple predictions from ALCOR_c for rehadronisation of charmed quark matter

We study the production of charmed hadrons with the help of ALCOR_c, the algebraic coalescence model for rehadronisation of charmed quark matter. Mesonic ratios are introduced as factors connecting various antibaryon to baryon ratios. The resulting simple relations could serve as tests of quark matter formation and coalescence type rehadronization in heavy ion collisions.Comment: 7 pages in Latex, 1 PS figur

Aspects of Axion Phenomenology in a slice of AdS_5

Motivated by multi-throat considerations, we study the phenomenological implications of a bulk axion in a slice of AdS_5 with a large extra dimension: k~0.01 eV, kR > 1. In particular, we compare axion physics with a warped geometry to axions in flat compactifications. As in flat compactification scenarios, we find that the mass of the axion can become independent from the underlying Peccei-Quinn scale. Surprisingly, we find that in warped extra dimensions the axion's invisibility, cosmological viability, and basic phenomenology remain essentially unaltered in comparison to axions in flat compactifications.Comment: 25 pages, 9 figure

Antihyperon-Production in Relativistic Heavy Ion Collision

Recently it has been shown that the observed antiproton yield in heavy-ion collisions at CERN-SpS energies can be understood by multi-pionic interactions which enforce local chemical equilibrium of the antiprotons with the nucleons and pions. Here we show that antihyperons are driven towards local chemical equilibrium with pions, nucleons and kaons on a timescale of less than 3 fm/c when applying a similar argument for the antihyperons by considering the inverse channel of annihilation reactions anti-Y + p to pions + kaons. These multi-mesonic reactions easily explain the antihyperon yields at CERN-SpS energies as advertised in pure thermal, hadronic models without the need of a quark gluon plasma phase. In addition, the argument also applies for AGS energies.Comment: 4 pages using RevTeX, 1 eps figur

Supersymmetric Large Extra Dimensions and the Cosmological Constant Problem

This article briefly summarizes and reviews the motivations for - and the present status of - the proposal that the small size of the observed Dark Energy density can be understood in terms of the dynamical relaxation of two large extra dimensions within a supersymmetric higher-dimensional theory.Comment: Talk presented to Theory Canada I, Vancouver, June 2005. References added in V

Leptonic CP violation: zero, maximal or between the two extremes

Discovery of the CP-violation in the lepton sector is one of the challenges of the particle physics. We search for possible principles, symmetries and phenomenological relations that can lead to particular values of the CP-violating Dirac phase, $\delta$. In this connection we discuss two extreme cases: the zero phase, $\delta = 0$, and the maximal CP-violation, $\delta = \pm \pi/2$, and relate them to the peculiar pattern of the neutrino mixing. The maximal CP-violation can be related to the $\nu_\mu - \nu_\tau$ reflection symmetry. We study various aspects of this symmetry and introduce a generalized reflection symmetry that can lead to an arbitrary phase that depends on the parameter of the symmetry transformation. The generalized reflection symmetry predicts a simple relation between the Dirac and Majorana phases. We also consider the possibility of certain relations between the CP-violating phases in the quark and lepton sectors.Comment: 34 pages, no figures; v3: version appeared in JHE

Enabling quantitative data analysis through e-infrastructures

This paper discusses how quantitative data analysis in the social sciences can engage with and exploit an e-Infrastructure. We highlight how a number of activities which are central to quantitative data analysis, referred to as ‘data management’, can benefit from e-infrastructure support. We conclude by discussing how these issues are relevant to the DAMES (Data Management through e-Social Science) research Node, an ongoing project that aims to develop e-Infrastructural resources for quantitative data analysis in the social sciences

Fragmentation of exotic oxygen isotopes

Abrasion-ablation models and the empirical EPAX parametrization of projectile fragmentation are described. Their cross section predictions are compared to recent data of the fragmentation of secondary beams of neutron-rich, unstable 19,20,21O isotopes at beam energies near 600 MeV/nucleon as well as data for stable 17,18O beams

Theoretical predictions for the direct detection of neutralino dark matter in the NMSSM

We analyse the direct detection of neutralino dark matter in the framework of the Next-to-Minimal Supersymmetric Standard Model. After performing a detailed analysis of the parameter space, taking into account all the available constraints from LEPII, we compute the neutralino-nucleon cross section, and compare the results with the sensitivity of detectors. We find that sizable values for the detection cross section, within the reach of dark matter detectors, are attainable in this framework. For example, neutralino-proton cross sections compatible with the sensitivity of present experiments can be obtained due to the exchange of very light Higgses with m_{h_1^0}\lsim 70 GeV. Such Higgses have a significant singlet composition, thus escaping detection and being in agreement with accelerator data. The lightest neutralino in these cases exhibits a large singlino-Higgsino composition, and a mass in the range 50\lsim m_{\tilde\chi_1^0}\lsim 100 GeV.Comment: Final version to appear in JHEP. References added. LaTeX, 53 pages, 23 figure

Magnon delocalization in ferromagnetic chains with long-range correlated disorder

We study one-magnon excitations in a random ferromagnetic Heisenberg chain with long-range correlations in the coupling constant distribution. By employing an exact diagonalization procedure, we compute the localization length of all one-magnon states within the band of allowed energies $E$. The random distribution of coupling constants was assumed to have a power spectrum decaying as $S(k)\propto 1/k^{\alpha}$. We found that for $\alpha < 1$, one-magnon excitations remain exponentially localized with the localization length $\xi$ diverging as 1/E. For $\alpha = 1$ a faster divergence of $\xi$ is obtained. For any $\alpha > 1$, a phase of delocalized magnons emerges at the bottom of the band. We characterize the scaling behavior of the localization length on all regimes and relate it with the scaling properties of the long-range correlated exchange coupling distribution.Comment: 7 Pages, 5 figures, to appear in Phys. Rev.