Bulk Gauge Fields in the Randall-Sundrum Model

We explore the consequences of placing the Standard Model gauge fields in the bulk of the recently proposed localized gravity model of Randall and Sundrum. We find that the Kaluza Klein excitations of these fields are necessarily strongly coupled and we demonstrate that current precision electroweak data constrain the lowest states to lie above $\simeq 23$ TeV. Taking the weak scale to be $\sim 1$ TeV, the resulting implications on the model parameters force the bulk curvature, $R_5$, to be larger than the higher dimensional Planck scale, $M$, violating the consistency of the theory. In turn, to preserve |R_5|\lsim M^2, the weak scale must be pushed to \gsim 100 TeV. Hence we conclude that it is disfavored to place the Standard Model gauge fields in the bulk of this model as it is presently formulated.Comment: Improved results, 14 pages, Latex fil

Probing the Universal Randall-Sundrum Model at the ILC

The Randall-Sundrum model with all Standard Model (SM) fields in the bulk, including the Higgs, can be probed by precision measurements at the ILC. In particular, the couplings of the Higgs to the gauge bosons of the SM can be determined with high accuracy at the ILC. Here we examine the deviations in these couplings from their SM values within the framework of the Universal Randall-Sundrum Model (URSM) as well as the corresponding couplings of the first Higgs Kaluza-Klein excitation.Comment: 3 pages, 2 figs, contributed to the 2005 ALCPG and ILC Workshops, Snowmass, CO, 8/14-8/27 2005; small typos remove

Who Bears the Growing Cost of Science at Universities?

Scientific research has come to dominate many American university campuses. The growing importance of science is due to exciting breakthroughs in biology, information technology and advanced materials that have promise of tremendously improving human welfare. Along with the growing importance of science has come a growing flow of external funds to universities to support research. What is not well known, however, is that increasingly the costs of research are being funded at universities are coming out of internal university funds. Over the last three decades of the 20th century the percentage of university research that is funded out of internal funds rose from about 11 to 20 and internal research expenditures per faculty member almost quadrupled in real terms. Our paper sketches the reasons for the tremendous increase in university expenditure on research out of internal funds including changes in federal indirect cost reimbursement policies and the growing cost of start-up funds for new faculty. We present evidence, based upon a survey of department chairs, deans and vice presidents for research at over 200 public and private universities, on the magnitude of start up packages received by researchers in science and engineering disciplines. We then use panel data for 21 years and over 200 universities to estimate the impact of growing internal expenditures on research on student/faculty ratios, the substitution of lecturers for tenure track faculty, on average faculty salaries and on tuition levels at public and private universities. Among our most important findings is that universities whose research expenditures per faculty member out of internal funds has been growing the most rapidly in absolute terms, ceteris paribus, have the greatest increase in student/faculty ratios. So while undergraduate students may benefit from being in close proximity to great researchers, they also bear part of the costs in the form of larger class sizes and fewer full-time faculty members

Higgsless Electroweak Symmetry Breaking in Warped Backgrounds: Constraints and Signatures

We examine the phenomenology of a warped 5-dimensional model based on SU(2)$_L \times$ SU(2)$_R \times$ U(1)$_{B-L}$ model which implements electroweak symmetry breaking through boundary conditions, without the presence of a Higgs boson. We use precision electroweak data to constrain the general parameter space of this model. Our analysis includes independent $L$ and $R$ gauge couplings, radiatively induced UV boundary gauge kinetic terms, and all higher order corrections from the curvature of the 5-d space. We show that this setup can be brought into good agreement with the precision electroweak data for typical values of the parameters. However, we find that the entire range of model parameters leads to violation of perturbative unitarity in gauge boson scattering and hence this model is not a reliable perturbative framework. Assuming that unitarity can be restored in a modified version of this scenario, we consider the collider signatures. It is found that new spin-1 states will be observed at the LHC and measurement of their properties would identify this model. However, the spin-2 graviton Kaluza-Klein resonances, which are a hallmark of the Randall-Sundrum model, are too weakly coupled to be detected.Comment: More detailed analysis, added references, 43 pages, 15 figures, LaTe

The stress-corrosion behavior of Al-Li-Cu alloys: A comparison of test methods

Two powder metallurgy processed (Al-Li-Cu) alloys with and without Mg addition were studied in aqueous 3.5% NaCl solution during the alternate immersion testing of tuning fork specimens, slow crack growth tests using fracture mechanics specimens, and the slow strain rate testing of straining electrode specimens. Scanning electron microscopy and optical metallography were used to demonstrate the character of the interaction between the Al-Li-Cu alloys and the selected environment. Both alloys are susceptible to SC in an aqueous 3.5% NaCl solution under the right electrochemical and microstructural conditions. Each test method yields important information on the character of the SC behavior. Under all conditions investigated, second phase particles strung out in rows along the extrusion direction in the alloys were rapidly attacked, and played principal role in the SC process. With time, larger pits developed from these rows of smaller pits and under certain electrochemical conditions surface cracks initiated from the larger pits and contributed directly to the fracture process. Evidence to support slow crack growth was observed in both the slow strain rate tests and the sustained immersion tests of precracked fracture mechanics specimens. The possible role of H2 in the stress corrosion cracking process is suggested

Who Bears the Growing Cost of Science at Universities?

Scientific research has come to dominate many American universities. Even with growing external support, increasingly the costs of scientific research are being funded out of internal university funds. Our paper explains why this is occuring, presents estimates of the magnitudes of start-up cost packages being provided to scientists and engineers and then uses panel data to estimate the impact of the growing cost of science on student/faculty ratios, faculty salaries and undergraduate tuition.We find that universities whose own expenditures on research are growing the most rapidly, ceteris paribus, have had the greatest increase in student faculty ratios and, in the private sector, higher tuition increases. Thus, undergraduate students bear part of the cost of increased institutional expenditures on research.

Isospin Dynamics in Heavy Ion Collisions: from Coulomb Barrier to Quark Gluon Plasma

Heavy Ion Collisions (HIC) represent a unique tool to probe the in-medium nuclear interaction in regions away from saturation. In this report we present a selection of new reaction observables in dissipative collisions particularly sensitive to the symmetry term of the nuclear Equation of State (Iso-EoS). We will first discuss the Isospin Equilibration Dynamics. At low energies this manifests via the recently observed Dynamical Dipole Radiation, due to a collective neutron-proton oscillation with the symmetry term acting as a restoring force. At higher beam energies Iso-EoS effects will be seen in Imbalance Ratio Measurements, in particular from the correlations with the total kinetic energy loss. For fragmentation reactions in central events we suggest to look at the coupling between isospin distillation and radial flow. In Neck Fragmentation reactions important $Iso-EoS$ information can be obtained from the correlation between isospin content and alignement. The high density symmetry term can be probed from isospin effects on heavy ion reactions at relativistic energies (few AGeV range). Rather isospin sensitive observables are proposed from nucleon/cluster emissions, collective flows and meson production. The possibility to shed light on the controversial neutron/proton effective mass splitting in asymmetric matter is also suggested. A large symmetry repulsion at high baryon density will also lead to an "earlier" hadron-deconfinement transition in n-rich matter. A suitable treatment of the isovector interaction in the partonic EoS appears very relevant.Comment: 18 pages, 12 figures, lecture at the 2008 Erice School on Nuclear Physics, to appear in Progress in Particle and Nuclear Physic

Quenched Computation of the Complexity of the Sherrington-Kirkpatrick Model

The quenched computation of the complexity in the Sherrington-Kirkpatrick model is presented. A modified Full Replica Symmetry Breaking Ansatz is introduced in order to study the complexity dependence on the free energy. Such an Ansatz corresponds to require Becchi-Rouet-Stora-Tyutin supersymmetry. The complexity computed this way is the Legendre transform of the free energy averaged over the quenched disorder. The stability analysis shows that this complexity is inconsistent at any free energy level but the equilibirum one. The further problem of building a physically well defined solution not invariant under supersymmetry and predicting an extensive number of metastable states is also discussed.Comment: 19 pages, 13 figures. Some formulas added corrected, changes in discussion and conclusion, one figure adde

Investigation of Low-Density Symmetry Energy via Nucleon and Fragment Observables

With stochastic transport simulations we study in detail central and peripheral collisions at Fermi energies and suggest new observables, sensitive to the symmetry energy below normal density. As such we identify on one hand the isospin imbalance ratio, i.e. the relative amount of isospin equilibration in binary, peripheral reactions of nuclei with different isospin, as a function of the energy loss, which is sensitive to isospin diffusion; on the other hand the isospin asymmetry of an intermediate mass fragment (IMF) in symmetric collisions in ternary reactions, or more particularly, the ratio of the IMF to the residue asymmetry, which is sensitive to isospin migration.Comment: 6 pages, 6 figures; Contrib. to Int. Symp. on Exotic States of Nuclear Matter (EXOCT2007), Catania, Italy, June 2007, World Scientifc styl