Large N reduction on group manifolds

We show that the large N reduction holds on group manifolds. Large N field theories defined on group manifolds are equivalent to some corresponding matrix models. For instance, gauge theories on S^3 can be regularized in a gauge invariant and SO(4) invariant manner.Comment: 21 pages, 4 figures, typos corrected, a reference adde

First search for double-beta decay of 184Os and 192Os

A search for double-beta decay of osmium has been realized for the first time with the help of an ultra-low background HPGe gamma detector at the underground Gran Sasso National Laboratories of the INFN (Italy). After 2741 h of data taking with a 173 g ultra-pure osmium sample limits on double-beta processes in 184Os have been established at the level of T_{1/2} about 10^{14}-10^{17} yr. Possible resonant double-electron captures in 184Os were searched for with a sensitivity T_{1/2} about 10^{16} yr. A half-life limit T_{1/2} > 5.3 10^{19} yr was set for the double-beta decay of 192Os to the first excited level of 192Pt. The radiopurity of the osmium sample has been investigated and radionuclides 137Cs, 185Os and 207Bi were detected in the sample, while activities of 40K, 60Co, 226Ra and 232Th were limited at the mBq/kg level.Comment: 12 pages, 7 figures, 2 table

Search for 2\beta\ decays of 96Ru and 104Ru by ultra-low background HPGe gamma spectrometry at LNGS: final results

An experiment to search for double beta decay processes in 96Ru and 104Ru, which are accompanied by gamma rays, has been realized in the underground Gran Sasso National Laboratories of the I.N.F.N. (Italy). Ruthenium samples with masses of about (0.5-0.7) kg were measured with the help of ultra-low background high purity Ge gamma ray spectrometry. After 2162 h of data taking the samples were deeply purified to reduce the internal contamination of 40K. The last part of the data has been accumulated over 5479 h. New improved half life limits on 2\beta+/\epsilon \beta+/2\epsilon\ processes in 96Ru have been established on the level of 10^{20} yr, in particular for decays to the ground state of 96Mo: T1/2(2\nu 2\beta+) > 1.4 10^{20} yr, T1/2(2\nu \epsilon\beta+) > 8.0 10^{19} yr and T1/2(0\nu 2K) > 1.0 10^{21} yr (all limits are at 90% C.L.). The resonant neutrinoless double electron captures to the 2700.2 keV and 2712.7 keV excited states of 96Mo are restricted as: T1/2(0\nu KL) > 2.0 10^{20} yr and T1/2(0\nu 2L) > 3.6 10^{20} yr, respectively. Various two neutrino and neutrinoless 2\beta\ half lives of 96Ru have been estimated in the framework of the QRPA approach. In addition, the T1/2 limit for 0\nu 2\beta- transitions of 104Ru to the first excited state of 104Pd has been set as > 6.5 10^{20} yr.Comment: 14 pages, 5 figures, 2 tables; version accepted for publication on Phys. Rev.

Non-Perturbative Planar Equivalence and the Absence of Closed String Tachyons

We consider 'orbifold' and 'orientifold' field theories from the dual closed string theory side. We argue that a necessary condition for planar equivalence to hold is the absence of a closed string tachyonic mode in the dual non-supersymmetric string. We analyze several gauge theories on R3xS1. In the specific case of U(N) theories with symmetric/anti-symmetric fermions ('orientifold field theories') the relevant closed string theory is tachyon-free at large compactification radius (due to winding modes), but it develops a tachyonic mode below a critical radius. Our finding is with agreement with field theory expectations of a phase transition from a C-parity violating phase to a C-parity preserving phase as the compactification radius increases. In the case of U(N)xU(N) theories with bi-fundamental matter ('orbifold field theories') a tachyon is always present in the string spectrum, at any compactification radius. We conclude that on R4 planar equivalence holds for 'orientfiold field theories', but fails for 'orbifold field theories' daughters of N=4 SYM and suggest the same for daughters of N=1 SYM. We also discuss examples of SO/Sp gauge theories with symmetric/anti-symmetric fermions. In this case planar equivalence holds at any compactification radius -in agreement with the absence of tachyons in the string dual.Comment: 14 pages, Latex. 3 eps figures. v2: ref. added. v3: clarifying sentences added in the abstract and at the end of section 4. version accepted to JHE

Quantum critical transport, duality, and M-theory

We consider charge transport properties of 2+1 dimensional conformal field theories at non-zero temperature. For theories with only Abelian U(1) charges, we describe the action of particle-vortex duality on the hydrodynamic-to-collisionless crossover function: this leads to powerful functional constraints for self-dual theories. For the n=8 supersymmetric, SU(N) Yang-Mills theory at the conformal fixed point, exact hydrodynamic-to-collisionless crossover functions of the SO(8) R-currents can be obtained in the large N limit by applying the AdS/CFT correspondence to M-theory. In the gravity theory, fluctuating currents are mapped to fluctuating gauge fields in the background of a black hole in 3+1 dimensional anti-de Sitter space. The electromagnetic self-duality of the 3+1 dimensional theory implies that the correlators of the R-currents obey a functional constraint similar to that found from particle-vortex duality in 2+1 dimensional Abelian theories. Thus the 2+1 dimensional, superconformal Yang Mills theory obeys a "holographic self duality" in the large N limit, and perhaps more generally.Comment: 35 pages, 4 figures; (v2) New appendix on CFT2, corrected normalization of gauge field action, added ref

Maternal and newborn infants amino acid concentrations in obese women born themselves with normal and small for gestational age birth weight

This study was undertaken to compare amino acid concentrations in maternal and newborn infants’ serum in normal pregnancy and two groups of obese women who were born themselves with normal and small for gestational age (SGA) birth weight. Maternal cholesterol, lipoproteins concentrations and maternal and infants amino acid concentrations were evaluated at the time of delivery in 28 normal pregnancies, 46 obese pregnant women with normal birth weight (Ob-AGA group) and 44 obese pregnant women born themselves SGA (Ob-SGA group). Mean birth weight of newborn infants in Ob-SGA group was significantly less than in normal and Ob-AGA groups. Cholesterol and lipoproteins were significantly elevated in obese women (more prominent in Ob-SGA group). Most amino acid concentrations and fetal–maternal amino acid gradients were significantly lower in Ob-SGA group. These data suggest significant changes in placental amino acid transport/synthetic function in obese women who were born themselves SGA

Membrane Paradigm and Horizon Thermodynamics in Lanczos-Lovelock gravity

We study the membrane paradigm for horizons in Lanczos-Lovelock models of gravity in arbitrary D dimensions and find compact expressions for the pressure p and viscosity coefficients \eta and \zeta of the membrane fluid. We show that the membrane pressure is intimately connected with the Noether charge entropy S_Wald of the horizon when we consider a specific m-th order Lanczos-Lovelock model, through the relation pA/T=(D-2m)/(D-2)S_Wald, where T is the temperature and A is the area of the horizon. Similarly, the viscosity coefficients are expressible in terms of entropy and quasi-local energy associated with the horizons. The bulk and shear viscosity coefficients are found to obey the relation \zeta=-2(D-3)/(D-2)\eta.Comment: v1: 13 pages, no figure. (v2): refs added, typos corrected, new subsection added on the ratio \eta/s. (v3): some clarification added, typos corrected, to appear in JHE

Heavy Quark diffusion from lattice QCD spectral functions

We analyze the low frequency part of charmonium spectral functions on large lattices close to the continuum limit in the temperature region $1.5\lesssim T/T_c\lesssim 3$ as well as for $T \simeq 0.75T_c$. We present evidence for the existence of a transport peak above $T_c$ and its absence below $T_c$. The heavy quark diffusion constant is then estimated using the Kubo formula. As part of the calculation we also determine the temperature dependence of the signature for the charmonium bound state in the spectral function and discuss the fate of charmonium states in the hot medium.Comment: 4 pages, Proceedings for Quark Matter 2011 Conference, May 23-28, 2011, Annecy, Franc

Hydrodynamics at RHIC -- how well does it work, where and how does it break down?

I review the successes and limitations of the ideal fluid dynamic model in describing hadron emission spectra from Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC).Comment: 8 pages, 4 figures. Invited talk presented at Strange Quark Matter 2004 (Cape Town, Sep. 15-20, 2004). Proceedings to appear in Journal of Physics