Sudakov Logarithm Resummation for Vector Boson Production at Hadron Colliders

A complete description of W and Z boson production at high-energy colliders requires the resummation of large Sudakov logarithms which dominate the production at small transverse momentum. Currently there are two techniques for performing this resummation: impact parameter space and transverse momentum space. We argue that the latter can be formulated in a way which retains the advantages of the former, while at the same time allowing a smooth transition to finite order dominance at high transverse momentum.Comment: 5 pages, LaTeX, 2 figures, epsfig, contribution to the proceedings of the UK Phenomenology Workshop on Collider Physics, 19-24 September 1999, Durham, to be published in J. Phys.

Shaped nozzles for cryogenic buffer gas beam sources

Cryogenic buffer gas beams are important sources of cold molecules. In this work we explore the use of a converging-diverging nozzle with a buffer-gas beam. We find that, under appropriate circumstances, the use of a nozzle can produce a beam with improved collimation, lower transverse temperatures, and higher fluxes per solid angle

Precision Measurement of a Particle Mass at the Linear Collider

Precision measurement of the stop mass at the ILC is done in a method based on cross-sections measurements at two different center-of-mass energies. This allows to minimize both the statistical and systematic errors. In the framework of the MSSM, a light stop, compatible with electro-weak baryogenesis, is studied in its decay into a charm jet and neutralino, the Lightest Supersymmetric Particle(LSP), as a candidate of dark matter. This takes place for a small stop-neutralino mass difference.Comment: 6 pages, 4 figures, 3tables, Conference(Workshop)-LCWS/ILC2007-June,2,200

Superconducting Microwave Cavity Made of Bulk MgB2

We report the successful manufacture and characterization of a microwave resonant cylindrical cavity made of bulk MgB2 superconductor (Tc = 38.5 K), which has been produced by the Reactive Liquid Mg Infiltration technique. The quality factor of the cavity for the TE011 mode, resonating at 9.79 GHz, has been measured as a function of the temperature. At T = 4.2 K, the unloaded quality factor is 2.2x10^5; it remains of the order of 10^5 up to T ~ 30 K. We discuss the potential performance improvements of microwave cavities built from bulk MgB2 materials produced by reactive liquid Mg infiltration.Comment: 7 pages, 2 embedded figures, accepted for publication in Supercond. Sci. Techno

Nonclassical correlation in a multipartite quantum system: two measures and evaluation

There is a commonly recognized paradigm in which a multipartite quantum system described by a density matrix having no product eigenbasis is considered to possess nonclassical correlation. Supporting this paradigm, we define two entropic measures of nonclassical correlation of a multipartite quantum system. One is defined as the minimum uncertainty about a joint system after we collect outcomes of particular local measurements. The other is defined by taking the maximum over all local systems about the minimum distance between a genuine set and a mimic set of eigenvalues of a reduced density matrix of a local system. The latter measure is based on an artificial game to create mimic eigenvalues of a reduced density matrix of a local system from eigenvalues of a density matrix of a global system. Numerical computation of these measures for several examples is performed.Comment: v1: 10 pages, 8 figures, IOPART, v2: introduction modified, figure 7 replaced, v3: 10 pages, 10 figures, RevTeX4, major revision with an additional measure introduced, title changed (previous title: Non-classical correlation in a multi-partite quantum system reconsidered), to appear in Phys. Rev.

Search for long lived charged massive particles in pp collisions at s-hat = 1.8TeV

We report a search for the production of long-lived charged massive particles in a data sample of 90   pb-1 of √s=1.8   TeV pp̅ collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of O(1) pb are derived using two reference models, a stable quark and a stable scalar lepton

The effects of diet on the growth energetics of postlarval lobsters (Homarus americanus)

The growth energetics of postlarval lobsters (Homarus americanus) fed a brine shrimp diet (Artemia salina; 51% protein, protein:carbohydrate = 5.1) were compared with the energetics of lobsters fed three artificial diets. The artificial diets were pelletized shrimp meal diets, varying in both protein (16.65-23.30%) and carbohydrate content (22.85-31.27%) and the protein:carbohydrate ratio (0.5-1.0). The best growth was measured among lobsters fed the brine shrimp diet and the 23.30% protein diet, followed by the two lower protein diets. The protein efficiency ratios (g wet wt. gain/ g dry wt. protein fed) were inversely related to the protein level of each diet. All diets were assimilated at the same level (~ 9 0% ) but there were significant differences in food consumption rates, respiration rates and ammonia excretion rates among lobsters from the four experimental groups. Although all lobsters were given equal rations in grams, the artificial diets were lower in caloric content than the brine shrimp and the pellets were fragmented by the lobsters during the feeding process, resulting in significantly lower (P <0.01) food consumption rates of the artificial diets. Respiration rates measured immediately after feeding were significantly lower among lobsters fed the three artificial diets than those fed the brine shrimp diet; the increased respiration rate of the latter group of lobsters reflects an increased calorigenic effect due to the higher protein level of the brine shrimp diet. Ammonia excretion rates of lobsters from the four groups were significantly different from one another ( P <0 . 01) and were directly correlated with the protein level of each diet. The O:N ratios (atomic ratio of oxygen consumed to NH+ -N excreted) measured in the four experimental groups were inversely related to the protein level of the four diets, indicating an increased dependence on carbohydrate catabolism for energy production with low dietary protein levels. The reduced growth rates of lobsters fed the two lower protein diets were apparently a result of differences in the amounts of food consumed and not increased energy expenditures or reduced assimilation efficiencies.Prepared for the Department of Commerce, NOAA Office of Sea Grant under Grant #04-7-158- 44104

Wireless recording of the calls of Rousettus aegyptiacus and their reproduction using electrostatic transducers

Bats are capable of imaging their surroundings in great detail using echolocation. To apply similar methods to human engineering systems requires the capability to measure and recreate the signals used, and to understand the processing applied to returning echoes. In this work, the emitted and reflected echolocation signals of Rousettus aegyptiacus are recorded while the bat is in flight, using a wireless sensor mounted on the bat. The sensor is designed to replicate the acoustic gain control which bats are known to use, applying a gain to returning echoes that is dependent on the incurred time delay. Employing this technique allows emitted and reflected echolocation calls, which have a wide dynamic range, to be recorded. The recorded echoes demonstrate the complexity of environment reconstruction using echolocation. The sensor is also used to make accurate recordings of the emitted calls, and these calls are recreated in the laboratory using custom-built wideband electrostatic transducers, allied with a spectral equalization technique. This technique is further demonstrated by recreating multi-harmonic bioinspired FM chirps. The ability to record and accurately synthesize echolocation calls enables the exploitation of biological signals in human engineering systems for sonar, materials characterization and imaging