QCD thermodynamics with nonzero chemical potential at Nt=6N_t=6 and effects from heavy quarks

We extend our work on QCD thermodynamics with 2+1 quark flavors at nonzero chemical potential to finer lattices with $N_t=6$. We study the equation of state and other thermodynamic quantities, such as quark number densities and susceptibilities, and compare them with our previous results at $N_t=4$. We also calculate the effects of the addition of the charm and bottom quarks on the equation of state at zero and nonzero chemical potential. These effects are important for cosmological studies of the early Universe.Comment: 27 pages, 17 figures. Some small text and figure change

String Breaking in Non-Abelian Gauge Theories with Fundamental Matter Fields

We present clear numerical evidence for string breaking in three-dimensional SU(2) gauge theory with fundamental bosonic matter through a mixing analysis between Wilson loops and meson operators representing bound states of a static source and a dynamical scalar. The breaking scale is calculated in the continuum limit. In units of the lightest glueball we find $r_{\rm b} m_G\approx13.6$. The implications of our results for QCD are discussed.Comment: 4 pages, 2 figures; equations (4)-(6) corrected, numerical results and conclusions unchange

A comparison of three fingerstick, whole blood antibody tests for Helicobacter pylori infection: a United States, multicenter trial

We compared three whole blood antibody tests for Helicobacter pylori ( H. pylori ) in a United States, multicenter trial. Methods Patients referred for EGD at three medical centers were recruited. During EGD, biopsies were taken for histology and rapid urease testing (RUT). Immediately after endoscopy, patients underwent the antibody tests (FlexPack HP, Abbott Diagnostics; QuikVue, Quidel Corporation; AccuMeter, ChemTrak) using whole blood obtained by two to three fingersticks. Performance characteristics were calculated for each antibody test using the biopsy-based methods as a gold standard. Results A total of 131 patients participated; 50 (38%) patients had histological evidence of H. pylori infection. Using histology as a gold standard, the sensitivities of FlexPack HP, QuikVue, and Accumeter were 76%, 78%, and 84%, respectively. Specificity was 79% with FlexPack HP and 90% with QuikVue and Accumeter. There were no significant differences in the performance of the three antibody tests though there was a trend toward superior performance for AccuMeter compared to FlexPack HP ( p = 0.019 ). However, RUT proved superior to FlexPack HP using histology as a gold standard ( p = 0.008 ). Using either concordant histology and RUT results or a positive histology or RUT to define active H. pylori infection, there was no statistically significant difference between the antibody tests. Conclusions There were no statistically significant differences in the performance of the three antibody tests. These tests proved only marginally sensitive in detecting patients infected with H. pylori . Clinicians should be aware of the limitations of these tests, particularly when using them as a sole means of testing for H. pylori .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72148/1/j.1572-0241.1999.1135_x.x.pd

Colour-electric spectral function at next-to-leading order

The spectral function related to the correlator of two colour-electric fields along a Polyakov loop determines the momentum diffusion coefficient of a heavy quark near rest with respect to a heat bath. We compute this spectral function at next-to-leading order, O(alpha_s^2), in the weak-coupling expansion. The high-frequency part of our result (omega >> T), which is shown to be temperature-independent, is accurately determined thanks to asymptotic freedom; the low-frequency part of our result (omega << T), in which Hard Thermal Loop resummation is needed in order to cure infrared divergences, agrees with a previously determined expression. Our result may help to calibrate the overall normalization of a lattice-extracted spectral function in a perturbative frequency domain T << omega << 1/a, paving the way for a non-perturbative estimate of the momentum diffusion coefficient at omega -> 0. We also evaluate the colour-electric Euclidean correlator, which could be directly compared with lattice simulations. As an aside we determine the Euclidean correlator in the lattice strong-coupling expansion, showing that through a limiting procedure it can in principle be defined also in the confined phase of pure Yang-Mills theory, even if a practical measurement could be very noisy there.Comment: 38 page

Flavour physics constraints in the BMSSM

We study the implications of the presence of the two leading-order, non-renormalizable operators in the Higgs sector of the MSSM to flavour physics observables. We identify the constraints of flavour physics on the parameters of the BMSSM when we: a) focus on a region of parameters for which electroweak baryogenesis is feasible, b) use a CMSSM-like parametrization, and c) consider the case of a generic NUHM-type model. We find significant differences as compared to the standard MSSM case.Comment: 22 pages, 7 figure

Storage Qubits and Their Potential Implementation Through a Semiconductor Double Quantum Dot

In the context of a semiconductor based implementation of a quantum computer the idea of a quantum storage bit is presented and a possible implementation using a double quantum dot structure is considered. A measurement scheme using a stimulated Raman adiabatic passage is discussed.Comment: Revised version accepted for publication in Phys.Rev. B. 19 pages, 4 eps figure