9,036 research outputs found
Bound-state/elementary-particle duality in the Higgs sector and the case for an excited 'Higgs' within the standard model
Though being weakly interacting, QED can support bound states. In principle,
this can be expected for the weak interactions in the Higgs sector as well. In
fact, it has been argued long ago that there should be a duality between bound
states and the elementary particles in this sector, at least in leading order
in an expansion in the Higgs condensate. Whether this remains true beyond the
leading order is investigated using lattice simulations, and support is found.
This provides a natural interpretation of peaks in cross sections as bound
states. Unambiguously, this would imply the existence of (possibly very broad)
resonances of Higgs and W and Z bound states within the standard model.Comment: 15 pages, 3 figures v2: added appendix with technical details, some
minor improvement
Infrared-suppressed gluon propagator in 4d Yang-Mills theory in a Landau-like gauge
The infrared behavior of the gluon propagator is directly related to
confinement in QCD. Indeed, the Gribov-Zwanziger scenario of confinement
predicts an infrared vanishing (transverse) gluon propagator in Landau-like
gauges, implying violation of reflection positivity and gluon confinement.
Finite-volume effects make it very difficult to observe (in the minimal Landau
gauge) an infrared suppressed gluon propagator in lattice simulations of the
four-dimensional case. Here we report results for the SU(2) gluon propagator in
a gauge that interpolates between the minimal Landau gauge (for gauge parameter
lambda equal to 1) and the minimal Coulomb gauge (corresponding to lambda = 0).
For small values of lambda we find that the spatially-transverse gluon
propagator D^tr(0,|\vec p|), considered as a function of the spatial momenta
|\vec p|, is clearly infrared suppressed. This result is in agreement with the
Gribov-Zwanziger scenario and with previous numerical results in the minimal
Coulomb gauge. We also discuss the nature of the limit lambda -> 0 (complete
Coulomb gauge) and its relation to the standard Coulomb gauge (lambda = 0). Our
findings are corroborated by similar results in the three-dimensional case,
where the infrared suppression is observed for all considered values of lambda.Comment: 5 pages, 2 figures, one figure with additional results and extended
discussion of some aspects of the results added and some minor
clarifications. In v3: Various small changes and addition
Inertial waves in a rectangular parallelepiped
A study of inertial gyroscopic waves in a rotating homogeneous fluid is undertaken both theoretically and numerically. A novel approach is presented to construct a semi-analytical solution of a linear three-dimensional fluid flow in a rotating rectangular parallelepiped bounded by solid walls. The three-dimensional solution is expanded in vertical modes to reduce the dynamics to the horizontal plane. On this horizontal plane the two dimensional solution is constructed via superposition of 'inertial' analogs of surface Poincar\'{e} and Kelvin waves reflecting from the walls. The infinite sum of inertial Poincar\'{e} waves has to cancel the normal flow of two inertial Kelvin waves near the boundaries. The wave system corresponding to every vertical mode results in an eigenvalue problem. Corresponding computations for rotationally modified surface gravity waves are in agreement with numerical values obtained by Taylor (1921), Rao (1966) and also, for inertial waves, by Maas (2003) upon truncation of an infinite matrix. The present approach enhances the currently available, structurally concise modal solution introduced by Maas (2003). In contrast to Maas' approach, our solution does not have any convergence issues in the interior and does not suffer from Gibbs phenomenon at the boundaries. Additionally, an alternative finite element method is used to contrast these two semi-analytical solutions with a purely numerical one. The main differences are discussed for a particular example and one eigenfrequency
A luminosity monitor for the A4 parity violation experiment at MAMI
A water Cherenkov luminosity monitor system with associated electronics has
been developed for the A4 parity violation experiment at MAMI. The detector
system measures the luminosity of the hydrogen target hit by the MAMI electron
beam and monitors the stability of the liquid hydrogen target. Both is required
for the precise study of the count rate asymmetries in the scattering of
longitudinally polarized electrons on unpolarized protons. Any helicity
correlated fluctuation of the target density leads to false asymmetries. The
performance of the luminosity monitor, investigated in about 2000 hours with
electron beam, and the results of its application in the A4 experiment are
presented.Comment: 22 pages, 12 figures, submitted to NIM
Simulating relative humidity profiles in the tropics with a high resolution regional meteorological model
Investigation of Anaplasma marginale Seroprevalence in a Traditionally Managed Large California Beef Herd.
Recent observations by stakeholders suggested that ecosystem changes may be driving an increased incidence of bovine erythrocytic anaplasmosis, resulting in a reemerging cattle disease in California. The objective of this prospective cohort study was to estimate the incidence of Anaplasma marginale infection using seroconversion in a northern California beef cattle herd. A total of 143 Black Angus cattle (106 prebreeding heifers and 37 cows) were enrolled in the study. Serum samples were collected to determine Anaplasma marginale seroprevalence using a commercially available competitive enzyme-linked immunosorbent assay test kit. Repeat sampling was performed in seronegative animals to determine the incidence density rate from March through September (2013). Seroprevalence of heifers was significantly lower than that of cows at the beginning of the study (P < 0.001) but not at study completion (P = 0.075). Incidence density rate of Anaplasma marginale infection was 8.17 (95% confidence interval: 6.04, 10.81) cases per 1000 cow-days during the study period. Study cattle became Anaplasma marginale seropositive and likely carriers protected from severe clinical disease that might have occurred had they been first infected as mature adults. No evidence was found within this herd to suggest increased risk for clinical bovine erythrocytic anaplasmosis
Unfolding the Pocket, Neutralizing the Lyrical:Contrabass Guitarist Anthony Jackson and the Aesthetics of Modernism
A redefinition of the morphology, range and relationship of Tropodiaptomus schubotzi (Van Douwe) (syn. Tropodiaptomus incognitus Dussart and Gras) and of Tropodiaptomus symoensi Einsle, with notes on Tropodiaptomus loveni (de Guerne and Richard)
L'identitĂ© du #Tropodiaptomus schubotzi est Ă©tablie. Son aire de rĂ©partition comprend le bassin du Chari, y compris le Lac Tchad, oĂč cette espĂšce a Ă©tĂ© Ă©tudiĂ©e en dĂ©tail sous le nom de #Tropodiaptomus incognitus. Une population relique se maintient dans l'oasis de Coufra en Libye. Elle date de l'holocĂšne ancien et a atteint le niveau d'une sous-espĂšce. Dans le bassin du ZaĂŻre l'espĂšce #T. symoensi occupe au moins le sud-est de la rĂ©gion. Elle semble ĂȘtre le taxon le plus proche de #T. schubotzi. Elle est sĂ©parĂ©e de #T. loveni De Guerne & Richard, connu seulement du bas ZaĂŻre, par la forĂȘt inondĂ©e de la partie centrale du ZaĂŻre. La relation entre ces deux espĂšces du ZaĂŻre est plutĂŽt Ă©loignĂ©e, bien qu'elles appartiennent au mĂȘme groupe d'espĂšces, celui de #T. orientalis. Le groupe du #T. schubotzi est lui-mĂȘme en vicariance avec le groupe du #T. kraepelini vers l'est. Dans le sud-est du bassin du ZaĂŻre, l'aire de rĂ©partition du #T. symoensi et du #T. kraepelini se recoupe partiellement. S'il existe aussi des recoupements ou une vicariance avec d'autres membres du complexe #T. schubotzi-symoensi, tel que le #T. kissi et le #T. kieferi$ n'est pas encore prouvĂ©. (RĂ©sumĂ© d'auteur, sic
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