123206542
First Gamma-Ray Spectroscopy and Isospin Symmetry Study of the N = Z-2 Nucleus V-44
Excited states in the T-z = -1 nucleus V-44 have been observed for the first time. The states have been identified through recoil-gamma-gamma coincidences and comparison with analogue states in the mirror nucleus Sc-44. Mirror energy differences have been extracted and compared to state-of-the-art fp shell-model calculations which include charge symmetry breaking forces.
95039655
Lifetime measurements of unbound nuclear states
A Differential Plunger device for measuring the lifetimes of Unbound Nuclear States (DPUNS) is currently being built at the University of Manchester. The plunger has been designed to be able to work with the proton-, alpha-, beta- and isomer-tagging methods using the JUROGAM II - RITU - GREAT setup at the University of Jyvaskyla, Finland. Valuable nuclear-structure information can be investigated from the measurement of lifetimes in proton-and alpha-unbound nuclei. To date, nuclear structure information from proton emission has been obtained from a comparison of the experimentally measured half-life with that predicted from various tunnelling calculations. A crucial parameter required to perform these calculations is the deformation of the parent nucleus involved in the decay, which in all cases to date, has only ever been estimated or calculated from theory. DPUNS aims to address this logical weakness through the measurement of the lifetimes of excited states in these unbound nuclei. The first measurement of a lifetime in a proton-unbound nucleus was recently obtained for 109I. The results from this measurement were discussed along with the future physics programme that can be performed with DPUNS.
120497533
Isobaric Analogue States Studied in Mirrored Fragmentation and Knockout Reactions
A Gamma-ray spectroscopic study of excited states of isobaric multiplets has been performed in recent years, with a view to gaining a quantitative understanding of energy differences between excited states in terms of a range of Coulomb and other isospin breaking phenomena. Recently, the experimental programme has been augmented by a study of isobaric analogue states of mirror nuclei populated in mirrored fragmentation reactions. In this presentation, recent results on the $T =\frac{3}{2}$ analogue states in the $T_z =\pm \frac{3}{2}$ mirror pair 53Ni/53Mn will be summarised. In this work, further strong evidence is found for the need to include an anomalous isospin-breaking two-body matrix element for angular-momentum couplings of J = 2, in addition the expected Coulomb contribution, in order to account for the experimental data.
94646277
The nature of subvalent gallium and indium in aqueous media
Subvalent gallium can exist in aqueous solutions as Ga-Ga bonded gallium(II) species stabilised by halide ligands in the form of the complex anions Ga2X62- (X = Cl, Br or I) whose formation and rea ...
207879155
Isospin purity of T = 1 states in the A = 38 nuclei studied via lifetime measurements in 38
The Doppler Shift Attenuation Method has been used to measure lifetimes for levels in K at excitation energies of 1698, 2404, 2830, 2996 and 3671 keV, populated using the Ca(d,α)K reaction at a beam energy of 4.5 MeV. Values of 109(29), 95(22), 457(63), 130(40) and 160(50) fs respectively were measured and are compared with previous values obtained using different stopping powers. The matrix element for the transition between the Jπ = 2+T=1 and 0 + T=1 states in this Tz=0 nucleus is compared with the analogous transition in the other nuclei in the T=1 triplet, Ca (Tz=-1) and Ar (Tz=+1), and with the results of shell-model calculations. PACS numbers: 21.10.-k, 21.10.Tg, 21.60.Cs, 23.20.Js,27.30.+t Current address: Department of Physics, University of York, Heslington, York, YO10 5DD, UK. Current address: Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA. Current address: Department of Physics, University of Richmond, Richmond, VA 23173, USA.
55086351
Competing single-particle and collective states in the low-energy structure of $^{113}$I
To understand the low-energy structure of the neutron deficient iodine isotopes, lifetimes for the low-lying 9/2(+) and 11/2(+) positive-parity states in I-113 have been measured as tau = 28(4) ps and tau = 3.7(7) ps, respectively. The lifetime for the 11/2(-) state, which feeds the 9/2(+) and 11/2(+) states, was remeasured with improved accuracy as tau = 216(7) ps. The reduced transition probability, B(E2) = 32(5) W.u., for the 9/2(+) -> 5/2(+) transition agrees with that calculated within the shell model using a Hamiltonian based on the charge-dependent Bonn nucleon-nucleon interaction. In contrast, the much larger transition probability, B(E2) = 209(39) W.u., measured for the 11/2(+) -> 7/2(+) transition has been interpreted, with the aid of configuration-constrained total Routhian surface calculations, as resulting from a slightly gamma-soft rotor with an associated quadrupole deformation of beta(2) approximate to 0.18. Remarkably similar reduced E1 transition probabilities of 5.5(5) x 10(-4) and 4.9(5) x 10(-4) W.u. were deduced for the 11/2(-) -> 9/2(+) and 11/2(-) -> 11/2(+) transitions, respectively, which feed apparently dissimilar but competing structures.
15966377
Open strings in the plane wave background II: Superalgebras and spectra
In [6] we started a systematic investigation of open strings in the plane wave background. In this paper we continue the analysis by discussing the superalgebras of conserved charges, the spectra of open strings, and the spectra of DBI fluctuations around D-brane embeddings. We also derive the gluing conditions for corresponding boundary states and analyze their symmetries. All results are consistent with each other, and confirm the existence of additional supersymmetries as previously discussed. We further show that for every symmetry current one can construct a (countably) infinite number of related currents that contain more worldsheet derivatives, and discuss non-local symmetries.
52263753
Inhomogeneity simplified
We study models of translational symmetry breaking in which inhomogeneous matter field profiles can be engineered in such a way that black-brane metrics remain isotropic and homogeneous. We explore novel Lagrangians involving square root terms and show how these are related to massive gravity models and to tensionless limits of branes. Analytic expressions for the DC conductivity and for the low frequency scaling of the optical conductivity are derived in phenomenological models, and the optical conductivity is studied in detail numerically. The square root Lagrangians are associated with linear growth in the DC resistivity with temperature and also lead to minima in the optical conductivity at finite frequency, suggesting that our models may capture many features of heavy fermion systems.
119200425
Holography for Einstein-Maxwell-dilaton theories from generalized dimensional reduction
A bstractWe show that a class of Einstein-Maxwell-Dilaton (EMD) theories are re- lated to higher dimensional AdS-Maxwell gravity via a dimensional reduction over com- pact Einstein spaces combined with continuation in the dimension of the compact space to non-integral values (‘generalized dimensional reduction’). This relates (fairly complicated) black hole solutions of EMD theories to simple black hole/brane solutions of AdS-Maxwell gravity and explains their properties. The generalized dimensional reduction is used to infer the holographic dictionary and the hydrodynamic behavior for this class of theories from those of AdS. As a specific example, we analyze the case of a black brane carrying a wave whose universal sector is described by gravity coupled to a Maxwell field and two neutral scalars. At thermal equilibrium and finite chemical potential the two operators dual to the bulk scalar fields acquire expectation values characterizing the breaking of con- formal and generalized conformal invariance. We compute holographically the first order transport coefficients (conductivity, shear and bulk viscosity) for this system.
56151350
The holographic fluid dual to vacuum Einstein gravity
We present an algorithm for systematically reconstructing a solution of the (d + 2)-dimensional vacuum Einstein equations from a (d + 1)-dimensional fluid, extending the non-relativistic hydrodynamic expansion of Bredberg et al. in arXiv:1101.2451 to arbitrary order. The fluid satisfies equations of motion which are the incompressible Navier-Stokes equations, corrected by specific higher-derivative terms. The uniqueness and regularity of this solution is established to all orders and explicit results are given for the bulk metric and the stress tensor of the dual fluid through fifth order in the hydrodynamic expansion. We establish the validity of a relativistic hydrodynamic description for the dual fluid, which has the unusual property of having a vanishing equilibrium energy density. The gravitational results are used to identify transport coefficients of the dual fluid, which also obeys an interesting and exact constraint on its stress tensor. We propose novel Lagrangian models which realise key properties of the holographic fluid.
119251878
Holographic realization of gauge mediated supersymmetry breaking
A bstractThe general gauge mediation scenario provides a framework in which properties of a visible sector with soft supersymmetry breaking are computed from current correlation functions in the supersymmetry breaking hidden sector. In this paper we will use holography to model strongly coupled hidden sectors by weakly curved geometries and describe how the current correlators relevant for general gauge mediation are computed by holographic methods. We illustrate the general setup by a toy example which captures most of the relevant features.