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.
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.
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 ...
120317800
First {$\gamma$}-ray spectroscopy of Fe49 and Ni53: Isospin-breaking effects at large proton excess
Isospin-breaking effects have been studied for the first time in T=(3/2) isobaric analog states. Gamma decays have been observed from T{sub z}=-(3/2) nuclei, {sup 49}Fe and {sup 53}Ni, presented here in new level schemes, and mirror energy differences have been computed following observation of analog states in {sup 49}V and {sup 53}Mn, respectively. Shell-model calculations in the fp shell are in good agreement with the data and reveal the importance of non-Coulomb isospin-breaking effects in T=(3/2) isobaric analog states. A two-step fragmentation process was developed to allow access to highly proton-rich nuclei and to produce each member of a mirror pair via mirrored fragmentation of a {sup 56}Ni secondary beam. This work represents the first study using this technique and demonstrates the power of this approach for future studies of isobaric analog states in very proton-rich systems.
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.
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.
2574105
Holographic anatomy of fuzzballs
We present a comprehensive analysis of 2-charge fuzzball solutions, that is, horizon-free non-singular solutions of IIB supergravity characterized by a curve on R4. We propose a precise map that relates any given curve to a specific superposition of R ground states of the D1-D5 system. To test this proposal we compute the holographic 1-point functions associated with these solutions, namely the conserved charges and the vacuum expectation values of chiral primary operators of the boundary theory, and find perfect agreement within the approximations used. In particular, all kinematical constraints are satisfied and the proposal is compatible with dynamical constraints although detailed quantitative tests would require going beyond the leading supergravity approximation. We also discuss which geometries may be dual to a given R ground state. We present the general asymptotic form that such solutions must have and present exact solutions which have such asymptotics and therefore pass all kinematical constraints. Dynamical constraints would again require going beyond the leading supergravity approximation.
3319486
Lifshitz as a deformation of Anti-de Sitter
A bstractWe consider holography for Lifshitz spacetimes with dynamical exponent z = 1+ϵ2, where ϵ is small. We show that the holographically dual field theory is a specific deformation of the relativistic CFT, corresponding to the z = 1 theory. Treating ϵ as a small expansion parameter we set up the holographic dictionary for Einstein-Proca models up to order ϵ2 in three and four bulk dimensions. We explain how renormalization turns the relativistic conformal invariance into non-relativistic Lifshitz invariance with dynamical exponent z = 1 + ϵ2. We compute the two-point function of the conserved spin two current for the dual two-dimensional field theory and verify that it is Lifshitz invariant. Using only QFT arguments, we show that a particular class of deformations of CFTs generically leads to Lifshitz scaling invariance and we construct examples of such deformations.
3270626
Lifshitz from AdS at finite temperature and top down models
A bstractWe construct analytically an asymptotically Lifshitz black brane with dynamical exponent z = 1 + ∈2 in an Einstein-Proca model, where ∈ is a small parameter. In previous work we showed that the holographic dual QFT is a deformation of a CFT by the time component of a vector operator and the parameter ∈ is the corresponding deformation parameter. In the black brane background this operator additionally acquires a vacuum expectation value. We explain how the QFT Ward identity associated with Lifshitz invariance leads to a conserved mass and compute analytically the thermodynamic quantities showing that they indeed take the form implied by Lifshitz invariance. In the second part of the paper we consider top down Lifshitz models with dynamical exponent close to one and show that they can be understood in terms of vector deformations of conformal field theories. However, in all known cases, both the conformal field theory and its Lifshitz deformations have modes that violate the Breitenlohner-Freedman bound.
9516472
Worldvolume supersymmetries for branes in plane waves
We study the worldvolume supersymmetries of M2 branes in the maximally supersymmetric plane wave background of M theory. For certain embeddings the standard probe analysis indicates that the worldvolume theory has less than 16 supersymmetries. We show that at the quadratic level the worldvolume theory admits additional linearly realized supersymmetries, and that the spectra of the branes are organized into multiplets of these symmetries. We find however that these supersymmetries are not respected by worldvolume interactions. Our analysis was motivated by recent work showing that D-branes in the maximally supersymmetric plane wave background of IIB string theory admit supersymmetries beyond those of the probe analysis. The construction of the additional supercharges in this case was specific to a string worldsheet that is a strip and the present results suggest that string interactions do not preserve these symmetries.