117988552
Parity nonconservation in the gamma decay of polarized 17/2(-) isomers in Tc-93
The determination of the 0 deg. - 180 deg. asymmetry (A{sub {gamma}}), which arises because of the parity nonconserving matrix element, in the 751-keV {gamma} decay of polarized 17/2{sup -} isomers in {sup 93}Tc with respect to the direction of polarization is reported. A combined analysis of the present results together with those from our earlier work yields an effect of two standard deviations.
121183473
Observation of rotating nuclear molecules and determination of their lifetimes
Long-living rotating nuclear molecules (or “dinuclear systems”) have been observed at the velocity filter SHIP at GSI in reactions of 64Ni + 207Pb at Coulomb barrier energies. The rotation was directly revealed by the velocity spectra of deep inelastic target-like transfer products which are formed during the lifetime of the nuclear molecule and emitted after its breakup. The corresponding rotation angles were about 180 degree pointing to long nuclear interaction times or lifetimes of the system, respectively. We deduced the lifetimes from the lines in the velocity spectra originating from two different rotation angles. Further, the unambiguous correlation of a certain transfer product with its individual velocity spectrum allowed us to study the lifetimes as a function of the number of transferred protons.
13153867
Mass measurements of very neutron-deficient Mo and Tc isotopes and their impact on rp process nucleosynthesis.
The masses of ten proton-rich nuclides, including the N=Z+1 nuclides ⁸⁵Mo and ⁸⁷Tc, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical x-ray bursts. Surprisingly low α separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the rp process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the rp process.
16408480
Effective Kaon energy from a novel chiral SU(3) model
Abstract A new chiral SU(3) Lagrangian is proposed to describe the properties of kaons and anti-kaons in the nuclear medium, The saturation properties of nuclear matter are reproduced as well as the results of the Dirac-Briickner theory, After introducing the coupling between the omega meson and the kaon, our results for effective kaon and anti-kaon energy are quite similar as calculated in the one-boson-exchange model.
119438146
The discovery of the heaviest elements
201093324
Proton Radioactivity
119225428
Cascading gravity and degravitation
We construct a cascading brane model of gravity in which the behavior of the gravitational force law interpolates from (n+4)-dimensional to (n+3)-dimensional all the way down to 4-dimensional from longer to shorter length scales. We show that, at the linearized level, this model exhibits the features necessary for degravitation of the cosmological constant. The model is shown to be ghost free with the addition of suitable brane kinetic operators, and we demonstrate this using a number of independent procedures. Consequently this is a consistent infrared (IR) modification of gravity, providing a promising framework for a dynamical, degravitating solution of the cosmological constant problem.
119430795
The Casimir effect in the presence of compactified universal extra dimensions
Abstract The Casimir force in a system consisting of two parallel conducting plates in the presence of compactified universal extra dimensions (UXD) is analyzed. The Casimir force with UXDs differs from the force obtained without extra dimensions. A new power law for the Casimir force is derived. By comparison to experimental data the size R of the universal extra dimensions can be restricted to R ⩽10 nm for one extra dimension.
39970498
Difficulty of detecting minihalos via gamma rays from dark matter annihilation.
Analytical calculations and recent numerical experiments have shown that a sizable amount of the mass of our Galaxy is in a form of clumpy, virialized substructures that, according to Diemand et al., can be as light as 10(-6)M(.). In this work we estimate the gamma-ray flux expected from dark matter annihilation occurring within these minihalos, under the hypothesis that the bulk of dark matter is composed by neutralinos. We generate mock sky maps showing the angular distribution of the expected gamma-ray signal. We compare them with the sensitivities of satellite-borne experiments such as GLAST and find that a possible detection of minihalos is indeed very challenging.
119090594
Lorentz-invariant ensembles of vector backgrounds
We consider gauge field theories in the presence of ensembles of vector backgrounds. While Lorentz invariance is explicitly broken in the presence of any single background, here, the Lorentz invariance of the theory is restored by averaging over a Lorentz-invariant ensemble of backgrounds, i.e., a set of background vectors that is mapped onto itself under Lorentz transformations. This framework is used to study the effects of a non-trivial but Lorentz-invariant vacuum structure or mass dimension two vector condensates by identifying the background with a shift of the gauge field. Up to now, the ensembles used in the literature comprise configurations corresponding to non-zero field tensors together with such with vanishing field strength. We find that even when constraining the ensembles to pure gauge configurations, the usual high-energy degrees of freedom are removed from the spectrum of asymptotic states in the presence of said backgrounds in Euclidean and in Minkowski space. We establish this result not only for the propagators to all orders in the background and otherwise at tree level but for the full propagator.
118464550
Self-protection of massive cosmological gravitons
Relevant deformations of gravity present an exciting window of opportunity to probe the rigidity of gravity on cosmological scales. For a single-graviton theory, the leading relevant deformation constitutes a graviton mass term. In this paper, we investigate the classical and quantum stability of massive cosmological gravitons on generic Friedman backgrounds. For a Universe expanding towards a de Sitter epoch, we find that massive cosmological gravitons are self-protected against unitarity violations by a strong coupling phenomenon.