15541387
Lower dimensional Yang-Mills theory as a laboratory to study the infrared regime
Lattice studies of the infrared regime of gauge theories are complicated by the required extensive limits, the performed gauge fixing and the demand for high statistics. Using a general power counting scheme for the infrared limit of Landau gauge SU(N) Yang-Mills theory in arbitrary dimensions we show that the infrared behavior of Greens functions is both qualitatively and quantitatively similar in two, three and four spacetime dimensions. Therefore, lower dimensional lattice simulations can serve as a simplified laboratory to analyze the presently applied approximations and to obtain first results for higher correlation functions.
119167811
The infrared behavior of Landau gauge Yang–Mills theory in d=2, 3 and 4 dimensions
Abstract We develop a general power counting scheme for the infrared limit of Landau gauge SU ( N ) Yang–Mills theory in arbitrary dimensions. Employing a skeleton expansion, we find that the infrared behavior is qualitatively independent of the spacetime dimension d . In the cases d = 2 , 3 and 4 even the quantitative results for the infrared exponents of the vertices differ only slightly. Therefore, corresponding lattice simulations provide interesting qualitative information for the physical case. We furthermore find that the loop integrals depend only weakly on the numerical values of the IR exponents.
124472128
Infrared behavior of vertex functions in d-dimensional Yang-Mills theory
7904061
Confinement and Green functions in Landau-gauge QCD
Institut fur Physik, Karl-Franzens-Universitat, Universitatsplatz 5, A-8010 Graz, AustriaIn a functionalapproachto QCD the infraredbehaviourof LandaugaugeGreenfunctionsis inves-tigated. Positivity violation for, and thus conﬁnement of, gluons is demonstrated, and the analyticstructure of the gluon propagator is studied. Quark conﬁnem ent is related to an infrared diver-gence of the quark-gluon vertex. In the latter various components are dynamically induced dueto the spontaneous breaking of chiral symmetry. As a result an infrared ﬁnite running coupling inthe Yang-Mills sector is derived whereas the running coupling related to the quark-gluonvertex isinfrared divergent. Based on a truncation for the quark-gluon vertex Dyson-Schwinger equation,which respects the analytically determined infrared behavior, numerical results for the coupledsystem of the quark propagator and vertex Dyson-Schwinger equations are presented. The result-ing quark mass function as well as the vertex function show only a very weak dependence on thecurrent quark mass in the deep infrared. From this we infer by an analysis of the quark-quarkscattering kernel a linearly rising quark potential with an almost mass independent string tensionin the case of broken chiral symmetry.8th Conference Quark Conﬁnement and the Hadron SpectrumSeptember 1-6, 2008Mainz, Germany
118464834
Infrared Behavior of 3-Point Functions in Landau Gauge Yang-Mills Theory
The three-gluon and ghost-gluon vertices of Landau gauge Yang-Mills theory are investigated in the low momentum regime. Due to ghost dominance in the infrared we can use the known power law behavior for the propagators to determine analytically the complete momentum dependence of the dressing functions. Besides a uniform, i. e. all momenta going to zero, divergence, we find additional singularities, if one momentum alone goes to zero, while the other two remain constant. At these asymmetric points we can extract additional infrared exponents, which corroborate previous results and expand the known fixed point solution of Landau gauge Yang-Mills theory, where the uniform infrared exponents for all vertex functions are known. Calculations in two and three dimensions yield qualitatively similar results.
118645147
Vertex functions of Coulomb gauge Yang-Mills theory
The canonical recursive Dyson--Schwinger equations for the three-gluon and ghost-gluon vertices are solved numerically. The employed truncation includes several previously neglected diagrams and includes back-coupling effects. We find an infrared finite ghost-gluon vertex and an infrared diverging three-gluon vertex. We also compare our results with those obtained in previous calculations, where bare vertices were used in the loop diagrams.
119951571
Relativistic effects and the constituent quark model of heavy quarkonia
AbstractCharmonium
$$c\bar c$$
 and bottomonium
$$b\bar b$$
 are investigated in the framework of a constituent quark model. A scalar confining and a one-gluon exchange (OGE) potential are used in a nonrelativistic reduction to order (p/m)2. Therefore the model includes spin dependent as well as spin independent terms. Their influence on the meson mass spectra and decay widths is analysed. We find that the experimental spectra can be reproduced by using a full model as well as by using a reduced version neglecting the spin independent terms. For both versions we calculate leptonic and radiative decay widths including relativistic corrections for the current operators. We find that for leptonic decays inclusion of all terms of the OGE potential gives better results than the non-relativistic formulas. For radiative transitions relativistic corrections are important.
10985387
First results from the Cryogenic Dark Matter Search in the Soudan Underground Laboratory.
We report the first results from a search for weakly interacting massive particles (WIMPs) in the Cryogenic Dark Matter Search experiment at the Soudan Underground Laboratory. Four Ge and two Si detectors were operated for 52.6 live days, providing 19.4 kg d of Ge net exposure after cuts for recoil energies between 10 and 100 keV. A blind analysis was performed using only calibration data to define the energy threshold and selection criteria for nuclear-recoil candidates. Using the standard dark-matter halo and nuclear-physics WIMP model, these data set the world's lowest exclusion limits on the coherent WIMP-nucleon scalar cross section for all WIMP masses above 15 GeV/c2, ruling out a significant range of neutralino supersymmetric models. The minimum of this limit curve at the 90% C.L. is 4 x 10(-43) cm2 at a WIMP mass of 60 GeV/c2.
14499726
Analysis of the low-energy electron-recoil spectrum of the CDMS experiment
We report on the analysis of the low-energy electron-recoil spectrum from the CDMS II experiment using data with an exposure of 443.2 kg-days. The analysis provides details on the observed counting rate and possible background sources in the energy range of 2–8.5 keV. We find no significant excess of a peaked contribution to the total counting rate above the background model, and compare this observation to the recent DAMA results. In the framework of a conversion of a dark matter particle into electromagnetic energy, our 90% confidence level upper limit of 0.246  events/kg/day at 3.15 keV is lower than the total rate above background observed by DAMA. In absence of any specific particle physics model to provide the scaling in cross section between NaI and Ge, we assume a Z2 scaling. With this assumption the observed rate in DAMA remains higher than the upper limit in CDMS. Under the conservative assumption that the modulation amplitude is 6% of the total rate we obtain upper limits on the modulation amplitude a factor of ~2 lower than observed by DAMA, constraining some possible interpretations of this modulation.
118486774
Quantum gates and multipartite entanglement resonances realized by motion
We demonstrate the presence of genuine multipartite entanglement between the modes of quantum fields in non-uniformly moving cavities. The transformations generated by the cavity motion can be considered as multipartite quantum gates. We present two setups for which multi-mode entanglement can be generated for bosons and fermions. As a highlight we show that the bosonic genuine multipartite correlations can be resonantly enhanced. Our results provide fundamental insights into the structure of Bogoliubov transformations and suggest strong links between quantum information, quantum fields in curved spacetimes and gravitational analogs by way of the equivalence principle.
119842100
The SuperCDMS proposal for dark matter detection
Abstract Presently the CDMS-II collaboration's Weakly Interacting Massive Particle (WIMP) search at the Soudan Underground Laboratory sets the most stringent exclusion limits of any WIMP cold dark matter direct-detection experiment. To extend our reach further, to WIMP-nucleon cross-sections in the range 10 - 46 - 10 - 44 cm 2 , we propose SuperCDMS, which would take advantage of a very deep site. One promising site is the recently approved SNOLab facility in Canada. In this paper we will present our overall program and focus on phase A of SuperCDMS.