Gravitational quasinormal modes of AdS black branes in d spacetime dimensions

The AdS/CFT duality has established a mapping between quantities in the bulk AdS black-hole physics and observables in a boundary finite-temperature field theory. Such a relationship appears to be valid for an arbitrary number of spacetime dimensions, extrapolating the original formulations of Maldacena's correspondence. In the same sense properties like the hydrodynamic behavior of AdS black-hole fluctuations have been proved to be universal. We investigate in this work the complete quasinormal spectra of gravitational perturbations of $d$-dimensional plane-symmetric AdS black holes (black branes). Holographically the frequencies of the quasinormal modes correspond to the poles of two-point correlation functions of the field-theory stress-energy tensor. The important issue of the correct boundary condition to be imposed on the gauge-invariant perturbation fields at the AdS boundary is studied and elucidated in a fully $d$-dimensional context. We obtain the dispersion relations of the first few modes in the low-, intermediate- and high-wavenumber regimes. The sound-wave (shear-mode) behavior of scalar (vector)-type low-frequency quasinormal mode is analytically and numerically confirmed. These results are found employing both a power series method and a direct numerical integration scheme.Comment: added references, typos corrected, minor changes, final version for JHE

Energy-momentum/Cotton tensor duality for AdS4 black holes

We consider the theory of gravitational quasi-normal modes for general linear perturbations of AdS4 black holes. Special emphasis is placed on the effective Schrodinger problems for axial and polar perturbations that realize supersymmetric partner potential barriers on the half-line. Using the holographic renormalization method, we compute the energy-momentum tensor for perturbations satisfying arbitrary boundary conditions at spatial infinity and discuss some aspects of the problem in the hydrodynamic representation. It is also observed in this general framework that the energy-momentum tensor of black hole perturbations and the energy momentum tensor of the gravitational Chern-Simons action (known as Cotton tensor) exhibit an axial-polar duality with respect to appropriately chosen supersymmetric partner boundary conditions on the effective Schrodinger wave-functions. This correspondence applies to perturbations of very large AdS4 black holes with shear viscosity to entropy density ratio equal to 1/4\pi, thus providing a dual graviton description of their hydrodynamic modes. We also entertain the idea that the purely dissipative modes of black hole hydrodynamics may admit Ricci flow description in the non-linear regime.Comment: 38 pages; minor typos corrected, a few extra references and a note adde

Exploring fusion at extreme sub barrier energies with weakly bound nuclei

Accepted for publication in Physical Review LettersResults of measurement of residues formed in fusion of 6Li with 198Pt in the energy range of 0.68< E/$V_b$ <1.3 using a new sensitive off-beam technique are reported. The fusion excitation function and the derived average angular momenta do not indicate a change of slope at deep sub-barrier energies, contrary to recent observations. The present results for a system with weakly bound projectile confront the current understanding of the fusion hindrance at these low energies, underlying the role of internal re-organization on the dynamical path towards fusion

Modern Rutherford experiment: Tunneling of the most neutron-rich nucleus

Expérience GANIL/SPIRALA modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of 197Au by extremely neutronrich 8He nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving re-accelerated unstable beams are reported. The results show unusual behavior of the tunneling of 8He compared to that for lighter helium isotopes, highlighting the role of the intrinsic structure of composite many-body quantum systems and pairing correlations

1n- and 2n-transfer with the Borromean nucleus 6^{6}He near the Coulomb barrier

Accepetd for publication in Physical Review LettersAngular distributions for 1n- and 2n-transfer are reported for the 6He + 65Cu system at Elab = 22.6 MeV. For the first time, triple coincidences between particles, neutrons and characteristic rays from the target-like residues were used to separate the contributions arising from 1n- and 2n-transfer. The differential cross sections for these channels, elastic scattering, and fusion were analyzed using a Coupled Reaction Channels approach. The large measured ratio of the 2n/1n cross section and the strong influence of 2n-transfer on other channels indicate that the di-neutron configuration of 6He plays a dominant role in the reaction mechanism

Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.

The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity

Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts

Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partial-wave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of $P$-matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G-matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determine the natural scale of the density for a possible phase transition into the MQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernova models. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom. Nuc

Gamma-ray studies of 119, 121, 123Sn isomers formed in deep inelastic heavy ion collisions

Yrast isomers in 119Sn, 121Sn and 123Sn have been identified among products of heavy ion collisions with 124Sn targets 10-15% above the Coloumb barrier. Isomeric decay schemes are reported, and further evidence for half-filling of the νh11 2 subshell at N = 73 is presented. For (νh11 2nseniority-3 states, observed level energies agree well with results of fractional parentage calculations

Conversion electron spectroscopy at the fragment mass analyzer focal plane: Studies of isomeric decays near the proton drip line

The decays of seniority isomers in the N=82 nuclei Er150 and Yb152 and in their respective N=81 isotopes Er149 and Yb151 were studied following mass separation by the Argonne Fragment Mass Analyzer. Conversion electrons were detected with Si p-i-n diodes operated at room temperature. The low-energy isomeric transitions in Yb151,152 have been observed for the first time in the electron spectra. Multipolarity assignments were made for many of the decay rays of the four nuclei

Reconciling Supersymmetric Grand Unification with αs(mZ)≈0.11\alpha_s(m_Z)\approx 0.11

We argue that supersymmetric grand unification of gauge couplings is not incompatible with small $\alpha_s$, even without large GUT-scale corrections, if one relaxes a usual universal gaugino mass assumption. A commonly assumed relation $M_2\simeq m_{\rm gluino}/3$ is in gross contradiction with $\alpha_s\approx 0.11$. Instead, small $\alpha_s$ favors $M_2\gg m_{\rm gluino}$. If this is indeed the case our observation casts doubt on another commonly used relation $M_1\simeq 0.5 M_2$ which originates from the same constraint of a common gaugino mass at the GUT scale. One firm prediction emerging within the small $\alpha_s$ scenario with the unconstrained gaugino masses is the existence of a relatively light gluino below $\sim$ 200\gev.Comment: 18 pages, LaTex format for text; epsf.sty needed for including 3 Postscript figures in the text. CHANGES: Comments on dark matter and non-minimal supergravity (see end of Sec. 2.3) and several references added; also some minor corrections made