Symmetry characterization of the collective modes of the phase diagram of the ν=0\nu=0 quantum Hall state in graphene: Mean-field and spontaneously broken symmetries

We devote this work to the study of the mean-field phase diagram of the $\nu=0$ quantum Hall state in bilayer graphene and the computation of the corresponding neutral collective modes, extending the results of recent works in the literature. Specifically, we provide a detailed classification of the complete orbital-valley-spin structure of the collective modes and show that phase transitions are characterized by singlet modes in orbital pseudospin, which are independent of the Coulomb strength and suffer strong many-body corrections from short-range interactions at low momentum. We describe the symmetry breaking mechanism for phase transitions in terms of the valley-spin structure of the Goldstone modes. For the remaining phase boundaries, we prove that the associated exact $SO(5)$ symmetry existing at zero Zeeman energy and interlayer voltage survives as a weaker mean-field symmetry of the Hartree-Fock equations. We extend the previous results for bilayer graphene to the monolayer scenario. Finally, we show that taking into account Landau level mixing through screening does not modify the physical picture explained above.Comment: 44 pages, 10 figure

Violation of Cauchy-Schwarz inequalities by spontaneous Hawking radiation in resonant boson structures

The violation of a classical Cauchy-Schwarz (CS) inequality is identified as an unequivocal signature of spontaneous Hawking radiation in sonic black holes. This violation can be particularly large near the peaks in the radiation spectrum emitted from a resonant boson structure forming a sonic horizon. As a function of the frequency-dependent Hawking radiation intensity, we analyze the degree of CS violation and the maximum violation temperature for a double barrier structure separating two regions of subsonic and supersonic condensate flow. We also consider the case where the resonant sonic horizon is produced by a space-dependent contact interaction. In some cases, CS violation can be observed by direct atom counting in a time-of-flight experiment. We show that near the conventional zero-frequency radiation peak, the decisive CS violation cannot occur.Comment: 10 pages, 6 figure

Entanglement and violation of classical inequalities in the Hawking radiation of flowing atom condensates

We consider a sonic black-hole scenario where an atom condensate flows through a subsonic-supersonic interface. We discuss several criteria that reveal the existence of nonclassical correlations resulting from the quantum character of the spontaneous Hawking radiation. We unify previous general work as applied to Hawking radiation analogs. We investigate the measurability of the various indicators and conclude that, within a class of detection schemes, only the violation of quadratic Cauchy-Schwarz inequalities can be discerned. We show numerical results that further support the viability of measuring deep quantum correlations in concrete scenarios.Comment: 15 pages, 6 figure

Measuring the muon's anomalous magnetic moment to 0.14 ppm

The anomalous magnetic moment (g-2) of the muon was measured with a precision of 0.54 ppm in Experiment 821 at Brookhaven National Laboratory. A difference of 3.2 standard deviations between this experimental value and the prediction of the Standard Model has persisted since 2004; in spite of considerable experimental and theoretical effort, there is no consistent explanation for this difference. This comparison hints at physics beyond the Standard Model, but it also imposes strong constraints on those possibilities, which include supersymmetry and extra dimensions. The collaboration is preparing to relocate the experiment to Fermilab to continue towards a proposed precision of 0.14 ppm. This will require 20 times more recorded decays than in the previous measurement, with corresponding improvements in the systematic uncertainties. We describe the theoretical developments and the experimental upgrades that provide a compelling motivation for the new measurement.Comment: 5 pages, 1 figure, presented at International Nuclear Physics Conference 2010 (INPC 2010

Habitat Requirements of Breeding Scaled Quail in Texas

Habitat variables were correlated with scaled quail (Callipep/,a squamata) whistle counts on 133 (24-km) random transects in Texas. Whether or not a particular habitat variable was correlated with whistle counts appeared to depend upon abundance and distribution of other habitat types and structural features. If \u3e= 1 requisite for quail survival and reproduction (food, water, cover, nest sites) was limited, habitat types and structural features were usually positively correlated with whistle counts (P \u3c 0.10). Conversely, abundant habitat types which did not provide all of these requisites were usually negatively correlated with whistle counts (P\u3c 0.10). Correlations indicated breeding scaled quail selected the more dense, shorter shrub habitats. Mesquite (Prosopsis spp.) habitats were especially important to scaled quail in the Trans-Pecos region

Use of Portable Infrared Cameras to Facilitate Detection and Capture Success of Montezuma Quail

Survey and trapping methods for Montezuma quail (Cyrtonyx montezumae) require means not traditionally used for other quail species (e.g., northern bobwhite, Colinus virginianus). Trapping Montezuma quail is most effective using pointing dogs at night when coveys can be located and captured by net during roosting. However, reduced visibility at night, cryptic coloration of plumage, and behavioral adaptive stillness reduce detection rates and increase accidental flushing of birds while searching for roost locations. Forward-looking infrared (FLIR) cameras have been used to aid in detection of cryptic wildlife, including avifauna roosting sites. We conducted 25 survey and night-trapping sessions for Montezuma quail in southeast Arizona using a combination of trained pointing dogs and a portable FLIR camera. Detection of coveys on a roost was less successful when ambient climate conditions were freezing (below 3.88 8C), when residual heat signatures from surrounding soils and rocks were greater than 18.33 8C, or when density of grass cover exceeded 40% and the distance to covey was . 2.5 m. The small thermal signatures of quail were often obstructed by vegetative cover or confused with residual thermal signatures reflected by inanimate objects (e.g., rocks, bare ground). Successful detection of coveys combining the use of dogs and FLIR before trapping was 6.06%. Trapping success and detection of coveys with FLIR was improved when used with radiotelemetry and coveys which included radio-marked individuals. Proper tuning of FLIR camera sensitivity to a limited thermal bandwidth, or isotherm range, may effectively narrow covey locations approximated by a pointing dog. The FLIR camera was of limited benefit when actively trapping coveys with dogs and a team of 2–3 people, but may be beneficial for non-invasive monitoring and estimating covey size of marked birds on roosts in landscapes with reduced vegetative cover