Nuclear recoil energy scale in liquid xenon with application to the direct detection of dark matter

We show for the first time that the quenching of electronic excitation from nuclear recoils in liquid xenon is well-described by Lindhard theory, if the nuclear recoil energy is reconstructed using the combined (scintillation and ionization) energy scale proposed by Shutt {\it et al.}. We argue for the adoption of this perspective in favor of the existing preference for reconstructing nuclear recoil energy solely from primary scintillation. We show that signal partitioning into scintillation and ionization is well-described by the Thomas-Imel box model. We discuss the implications for liquid xenon detectors aimed at the direct detection of dark matter

Effect of resonance decays on hadron elliptic flows

The influence of resonance decays on the elliptic flows of stable hadrons is studied in the quark coalescence model. Although difference between the elliptic flow of pions from resonance decays, except the rho meson, and that of directly produced pions is appreciable, those for other stable hadrons are small. Since there are more pions from the decays of rho mesons than from other resonances, including resonance decays can only account partially the deviation of final pion elliptic flow from the observed scaling of hadron elliptic flows, i.e., the hadron elliptic flow per quark is the same at same transverse momentum per quark. The remaining deviation can be explained by including the effect due to the quark momentum distribution inside hadrons.Comment: 13 pages and 5 figures, version pubblished in PRC, updated references and figure

Observation of modified hadronization in relativistic Au+Au collisions: a promising signature for deconfined quark-gluon matter

Measurements of identified particles from Au+Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV are reviewed. Emphasis is placed on nuclear modification, baryon-to-meson ratios, and elliptic flow at intermediate transverse momentum ($1.5 < p_T < 5$ GeV/c). Possible connections between (1) these measurements, (2) the running coupling for static quark anti-quark pairs at finite temperature, and (3) the creation of a deconfined quark-gluon phase are presented. Modifications to hadronization in Au+Au collisions are proposed as a likely signature for the creation of deconfined colored matter.Comment: 8 pages, 5 figures, invited talk at the Strange Quark Matter 2004 conference, Cape Town, South Afric

SU(2)-invariant spin-1/2 Hamiltonians with RVB and other valence bond phases

We construct a family of rotationally invariant, local, S=1/2 Klein Hamiltonians on various lattices that exhibit ground state manifolds spanned by nearest-neighbor valence bond states. We show that with selected perturbations such models can be driven into phases modeled by well understood quantum dimer models on the corresponding lattices. Specifically, we show that the perturbation procedure is arbitrarily well controlled by a new parameter which is the extent of decoration of the reference lattice. This strategy leads to Hamiltonians that exhibit i) $Z_2$ RVB phases in two dimensions, ii) U(1) RVB phases with a gapless ``photon'' in three dimensions, and iii) a Cantor deconfined region in two dimensions. We also construct two models on the pyrochlore lattice, one model exhibiting a $Z_2$ RVB phase and the other a U(1) RVB phase.Comment: 16 pages, 15 figures; 1 figure and some references added; some minor typos fixe

Evidence from Identified Particles for Active Quark and Gluon Degrees of Freedom

Measurements of intermediate pT (1.5 < pT < 5.0 GeV/c) identified particle distributions in heavy ion collisions at SPS and RHIC energies display striking dependencies on the number of constituent quarks in the corresponding hadron. One finds that elliptic flow at intermediate pT follows a constituent quark scaling law as predicted by models of hadron formation through coalescence. In addition, baryon production is also found to increase with event multiplicity much faster than meson production. The rate of increase is similar for all baryons, and seemingly independent of mass. This indicates that the number of constituent quarks determines the multiplicity dependence of identified hadron production at intermediate pT. We review these measurements and interpret the experimental findings.Comment: 8 pages, 5 figures, proceedings for SQM2006 conference in Los Angele

Longitudinal Current Dissipation in Bose-glass Superconductors

A scaling theory of vortex motion in Bose glass superconductors with currents parallel to the common direction of the magnetic field and columnar defects is presented. Above the Bose-glass transition the longitudinal DC resistivity $\rho_{||}(T)\sim (T-T_{BG})^{\nu' z'}$ vanishes much faster than the corresponding transverse resistivity $\rho_{\perp}(T)\sim (T-T_{BG})^{\nu' (z'-2)}$, thus {\it reversing} the usual anisotropy of electrical transport in the normal state of layered superconductors. In the presence of a current $\bf J$ at an angle $\theta_J$ with the common field and columnar defect axis, the electric field angle $\theta_E$ approaches $\pi/2$ as $T\rightarrow T_{BG}^+$. Scaling also predicts the behavior of penetration depths for the AC currents as $T\rightarrow T_{BG}^-$, and implies a {\it jump discontinuity} at $T_{BG}$ in the superfluid density describing transport parallel to the columns.Comment: 5 pages, revte

The Stellar Content of Obscured Galactic Giant HII Regions V: G333.1--0.4

We present high angular resolution near--infrared images of the obscured Galactic Giant HII (GHII) region G333.1--0.4 in which we detect an OB star cluster. For G333.1--0.4, we find OB stars and other massive objects in very early evolutionary stages, possibly still accreting. We obtained $K$--band spectra of three stars; two show O type photospheric features, while the third has no photospheric features but does show CO 2.3 $\mu$m band--head emission. This object is at least as hot as an early B type star based on its intrinsic luminosity and is surrounded by a circumstellar disc/envelope which produces near infrared excess emission. A number of other relatively bright cluster members also display excess emission in the $K$--band, indicative of disks/envelopes around young massive stars. Based upon the O star photometry and spectroscopy, the distance to the cluster is 2.6 $\pm$ 0.4 kpc, similar to a recently derived kinematic (near side) value. The slope of the $K$--band luminosity function is similar to those found in other young clusters. The mass function slope is more uncertain, and we find $-1.3 \pm 0.2 < \Gamma < -1.1 \pm 0.2$- for stars with M $> 5$ M$_\odot$ where the upper an lower limits are calculated independently for different assumptions regarding the excess emission of the individual massive stars. The number of Lyman continuum photons derived from the contribution of all massive stars in the cluster is 0.2 $\times$ $10^{50}$ $s^{-1}$ $< NLyc < 1.9$ $\times$ $10^{50}$ $s^{-1}$. The integrated cluster mass is 1.0 $\times$ $10^{3}$ $M_\odot < M_{cluster} < 1.3$ $\times$ $10^{3}$ $M_\odot$.Comment: 31 pages, including 12 figures and 3 tables. Accepted for publication in the A

Bloch-Nordsieck violating electroweak corrections to inclusive TeV scale hard processes

We point out that, since the colliders initial states (e+ e-,p p, p pbar, ... ) carry a definite nonabelian flavor, electroweak radiative corrections to inclusive hard cross sections at the TeV scale are affected by peculiar Bloch-Nordsieck violating double logs. We recall the setup of soft cancellation theorems, and we analyze the magnitude of the noncancelling terms in the example of electron - positron annihilation into hadrons.Comment: Minor typos corrected, references added. Final version to appear on Phys. Rev. Let

Exploring the properties of the phases of QCD matter - research opportunities and priorities for the next decade

This document provides a summary of the discussions during the recent joint QCD Town Meeting at Temple University of the status of and future plans for the research program of the relativistic heavy-ion community. A list of compelling questions is formulated, and a number of recommendations outlining the greatest research opportunities and detailing the research priorities of the heavy-ion community, voted on and unanimously approved at the Town Meeting, are presented. They are supported by a broad discussion of the underlying physics and its relation to other subfields. Areas of overlapping interests with the "QCD and Hadron Structure" ("cold QCD") subcommunity, in particular the recommendation for the future construction of an Electron-Ion Collider, are emphasized. The agenda of activities of the "hot QCD" subcommunity at the Town Meeting is attached.Comment: 34 pages of text, 254 references,16 figure