Wannier-Stark resonances in optical and semiconductor superlattices

In this work, we discuss the resonance states of a quantum particle in a periodic potential plus a static force. Originally this problem was formulated for a crystal electron subject to a static electric field and it is nowadays known as the Wannier-Stark problem. We describe a novel approach to the Wannier-Stark problem developed in recent years. This approach allows to compute the complex energy spectrum of a Wannier-Stark system as the poles of a rigorously constructed scattering matrix and solves the Wannier-Stark problem without any approximation. The suggested method is very efficient from the numerical point of view and has proven to be a powerful analytic tool for Wannier-Stark resonances appearing in different physical systems such as optical lattices or semiconductor superlattices.Comment: 94 pages, 41 figures, typos corrected, references adde

Sea-quark flavor asymmetry in the nucleon from a relativistic analysis of the Drell-Yan scattering off nuclei

It is shown that accounting for the relativistic structure of the deuteron allows to explain the ratio of the Drell-Yan pair production cross-section at the low Bjorken $x$ off the deuteron and the proton. Thus, the sea quark distributions in the nucleon should be studied with accounting for the effects of the relativistic structure of the deuteron. The suggested approach reduces theoretical uncertainty in extracting the ratio $\bar u/\bar d$ from the data and it is important for the clarification of the nature of the sea quark asymmetry in the nucleon.Comment: 4 pages, 1 figures, Chiral Symmetry in Hadron and Nuclear Physics November 13-16, 2007, Osak

Fast computation by block permanents of cumulative distribution functions of order statistics from several populations

The joint cumulative distribution function for order statistics arising from several different populations is given in terms of the distribution function of the populations. The computational cost of the formula in the case of two populations is still exponential in the worst case, but it is a dramatic improvement compared to the general formula by Bapat and Beg. In the case when only the joint distribution function of a subset of the order statistics of fixed size is needed, the complexity is polynomial, for the case of two populations.Comment: 21 pages, 3 figure

High-Sensitivity C Reactive Protein: Associations with Cardiovascular Risk Factors and Tracking in Female Adolescents and Young Adults

Objective. We assessed adolescent anthropometry, lipids, insulin, glucose, and blood pressures to identify factors associated with high-sensitivity C-reactive protein (hsCRP) and its tracking in young adults. Methods. Ten-year prospective study of 589 schoolgirls, 321 black, 268 white. Results. HsCRP did not differ (P > .08) by race or oral contraceptive use. HsCRP tracked from age 16 to 25 (r = 0.77), 16 to 26 (r = 0.50), 24 to 26 (r = 0.66), and 25 to 26 (r = 0.71), all P ≤ .02. By stepwise regression, at age 16, waist circumference accounted for 44.8% of hsCRP variance; BMI accounted for 33.1%, 34.4%, and 31.1% at ages 24, 25, and 26, P < .0001 for all. Changes in cholesterol and BMI were associated with change in hsCRP from age 24–26 (partial R2 = 12.3%  P < .0001, 6.6%  P = .0012). Changes in BMI and triglyceride (partial R2 = 8.5%  P = .0001, 3.3%, P = .0045) were associated with change in hsCRP from age 25 to 26. Conclusions. HsCRP tracks from age 16 to 26, with BMI, waist circumference, and cholesterol as major determinants

Measurement of the Proton Asymmetry Parameter C in Neutron Beta Decay

The proton asymmetry parameter C in neutron decay describes the correlation between neutron spin and proton momentum. In this Letter, the first measurement of this quantity is presented. The result C=-0.2377(26) agrees with the Standard Model expectation. The coefficient C provides an additional parameter for new and improved Standard Model tests. From a differential analysis of the same data (assuming the Standard Model), we obtain lambda=-1.275(16) as ratio of axial-vector and vector coupling constant.Comment: 4 pages, 2 figure

Studies of parton thermalization at RHIC

We consider the evolution of a parton system which is formed in the central region just after a relativistic heavy ion collision. The parton consist of mostly gluons, minijets, which are produced by elastic scattering between constituent partons of the colliding nuclei. We assume the system can be described by a semi-classical Boltzmann transport equation, which we solve by means of the test particle Monte-Carlo method including retardation. The partons proliferate via secondary radiative $gg \to ggg$ processes until the thermalization is reached for some assumptions. The extended system is thermalized at about $t=1.6$ fm/$c$ with $T = 570$ MeV and stays in equilibrium for about 2 fm/$c$ with breaking temperature $T = 360$ MeV in the rapidity central region.Comment: 14 page

Interaction of a TeV Scale Black Hole with the Quark-Gluon Plasma at LHC

If the fundamental Planck scale is near a TeV, then parton collisions with high enough center-of-mass energy should produce black holes. The production rate for such black holes has been extensively studied for the case of a proton-proton collision at \sqrt s = 14 TeV and for a lead-lead collision at \sqrt s = 5.5 TeV at LHC. As the parton energy density is much higher at lead-lead collisions than in pp collisions at LHC, one natural question is whether the produced black holes will be able to absorb the partons formed in the lead-lead collisions and eventually `eat' the quark-gluon plasma formed at LHC. In this paper, we make a quantitative analysis of this possibility and find that since the energy density of partons formed in lead-lead collisions at LHC is about 500 GeV/fm^3, the rate of absorption for one of these black holes is much smaller than the rate of evaporation. Hence, we argue that black holes formed in such collisions will decay very quickly, and will not absorb very many nearby partons. More precisely, we show that for the black hole mass to increase via parton absorption at the LHC the typical energy density of quarks and gluons should be of the order of 10^{10} GeV/fm^3. As LHC will not be able to produce such a high energy density partonic system, the black hole will not be able to absorb a sufficient number of nearby partons before it decays. The typical life time of the black hole formed at LHC is found to be a small fraction of a fm/c.Comment: 7 pages latex (double column), 3 eps figure

Commissioning of the vacuum system of the KATRIN Main Spectrometer

The KATRIN experiment will probe the neutrino mass by measuring the beta-electron energy spectrum near the endpoint of tritium beta-decay. An integral energy analysis will be performed by an electro-static spectrometer (Main Spectrometer), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m^3, and a complex inner electrode system with about 120000 individual parts. The strong magnetic field that guides the beta-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. A system consisting of 6 turbo-molecular pumps and 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300{\deg}C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10^{-11} mbar range. It is demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.Comment: submitted for publication in JINST, 39 pages, 15 figure