120311197
Rotation-aligned coupling in Fe 61
New levels have been established above the 861-keV, $9/{2}^{+}$ isomeric state in $^{61}\mathrm{Fe}$. The observations can be reproduced satisfactorily by shell model calculations, but only after a significant lowering of the $\ensuremath{\nu}{g}_{9/2}$ single-particle energy with respect to the value determined empirically from levels outside a $^{48}\mathrm{Ca}$ core. The results are also described well within the scope of the particle-triaxial-rotor model assuming a deformation ${\ensuremath{\beta}}_{2}~0.24$. The present findings, together with the recently measured magnetic and quadrupole moments of this state, point toward a structure possibly associated with a prolate shape.
122206593
Observation of Octupole Structures in Radon and Radium Isotopes and Their Contrasting Behavior at High Spin
Multinucleon transfer reactions have been used, for the first time, to populate high-spin bands of alternating parity states in {sup 218,220,222}Rn and {sup 222,224,226}Ra. The behavior of the angular momentum alignment with rotational frequency for the Rn isotopes is very different when compared with Ra and Th isotopes with N{approx}134, indicating a transition from octupole vibrational to stable octupole deformation. Throughout the measured spin range the values of {vert_bar}D{sub 0}/Q{sub 0}{vert_bar} remain constant for {sup 222}Ra and {sup 226}Ra and have a very small value for {sup 224}Ra, suggesting that the charge and mass distributions are not affected appreciably by rotations. {copyright} {ital 1997} {ital The American Physical Society}
7752926
Possible dynamic effects in the particle decay of 59Cu compound nuclei.
The slopes of the energy spectra of {ital p}, {ital d}, {ital t}, and {alpha} particles emitted from {sup 59}Cu nuclei formed in the reaction of {sup 32}S+{sup 27}Al at a bombarding energy of 150 MeV are described by statistical-model calculations in which the deformation is frozen during the first two steps of the deexcitation chain. The resultant fits to the high-energy portions of the spectra are comparable to those previously obtained by modifying the spin dependence of the level density, suggesting that dynamic effects may be important in evaporation from light nuclei.
9087855
Gamma ray studies of neutron-rich sdf shell nuclei produced in heavy ion collisions.
Reanalysis of [ital ichproductsofbinaryreactio] [ital nsof]$[sup 34]S, [sup 36]S, and [sup 37]Cl beams on [sup 160]Gd targets. Gates set on known [ital amma]$[ital raysin]$[ital A][similar to]160 products selected individual react ion channels and identified coincident [ital amma]$[ital raysin]$[ital A][similar to]36 partner products. Transfers of protons from projectile to target and of neutrons from target to projectile were generally favored, leading to excited neutron-rich light nuclei, including some difficult to reach by other means. Notable results include the observation of [ital amma]$[ital raycascadesup][sup [ital t][ital h][ital e]][ital high] [ital e] [ital stknownyraststatesinfour]$[ital N]=20 isotones. In two [ital N]=19 nuclei, [sup 33]Si and [sup 34]P, the two [ital N]=22 nuclei, [sup 38]S and [sup 39]Cl, previously unknown yrast states were identified.
122546814
Single-particle and collective structures in Cr 55 and V 55
Excited states in {sup 55}V and {sup 55}Cr have been populated via pn and 2n evaporation channels, respectively, following the fusion of a {sup 48}Ca beam at 172 MeV with a {sup 9}Be target. Level schemes have been deduced for the two nuclides to excitation energies of 7467 ({sup 55}V) and 12226 keV ({sup 55}Cr), with spins of 27/2{sup +} and 33/2{sup +}, respectively. Negative-parity states are compared with shell-model calculations using three different effective interactions in the full fp model space. Negative-parity levels of {sup 55}Cr are explained in terms of single-particle fp-shell configurations outside N=28 and N=32 cores. Positive-parity states in both isotopes show evidence for the involvement of neutron g{sub 9/2} configurations. In the case of {sup 55}Cr, a quasirotational structure based on the 1/2{sup +}[440] Nilsson orbital is observed up to the terminating state. In {sup 55}V, positive-parity states do not exhibit well-developed collective features, and the observation of octupole decays is an indication of their importance in transitions from neutron g{sub 9/2} configurations to the fp shell. Experimental results are compared with the predictions of a traditional shell model, the projected shell model, and total-Routhian-surface calculations.
118027838
Structure of Co-65,Co-67 studied through the beta decay of Fe-65,Fe-67 and a deep-inelastic reaction
The neutron-rich isotopes {sup 65,67}Fe and {sup 65}Co have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of {sup 238}U. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of {sup 65}Co have also been populated in the {sup 64}Ni+{sup 238}U reaction at Argonne National Laboratory. The level structure of {sup 65}Co could be investigated by combining all the information from both the {sup 65}Fe and {sup 65}Co{beta} decay and the deep-inelastic reaction. The {sup 65}Fe, {sup 65}Co, and {sup 67}Fe decay schemes and the {sup 65}Co yrast structure are fully established. The {sup 65,67}Co level structures can be interpreted as resulting from the coexistence of core-coupled states with levels based on a low-energy proton-intruder configuration.
34406165
Standard model with compactified spatial dimensions
We analyze the structure of the standard model coupled to gravity with spatial dimensions compactified on a three-torus. We find that there are no stable one-dimensional vacua at zero temperature, although there does exist an unstable vacuum for a particular set of Dirac neutrino masses.
119194544
Prospects and constraints for vector-like MFV matter at LHC
We examine the prospects for LHC discovery of SU(2)L singlet vector-like quarks that obey Minimal Flavour Violation (MFV) and are consistent with lower energy phenomenology. We study models where the vector-like quarks have the same quantum numbers as uR or dR, allowing mixing, which generally leads to significant low energy constraints. We find that at leading order in the MFV expansion there are two naturally phenomenologically viable MFV models of this type when the Weyl spinor components of the vector-like quarks are flavour triplets. We examine direct production bounds, flavour and electroweak precision data constraints for these models and determine the cross section for allowed values of the model parameters at LHC. For the models we identify as naturally phenomenologically viable, large amounts of parameter space afford a significant early discovery reach at LHC while being consistent with lower energy phenomenology.
1772638
Color octet scalars and high p_T four-jet events at the LHC
We study the effect of color octet scalars on the high transverse momenta four-jet cross section at the LHC. We consider both weak singlet and doublet scalars, concentrating on the case of small couplings to quarks. We find that a relatively early discovery at the LHC is possible for a range of scalar masses.
118615935
Supersymmetric dark matter sectors
We investigate the properties of a dark matter sector where supersymmetry is a good symmetry. In this context we find that the stability of the dark matter candidate is possible even when R-parity is broken in the visible sector. In order to illustrate the idea we investigate a simple scenario where the dark matter candidate is the lightest scalar field in the dark sector which annihilates mainly into two sfermions when these channels are available. We study the relic density constraints and the predictions for the dark matter detection experiments.