cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Non-Fermi glasses: fractionalizing electrons at finite energy density
Creators: name: Parameswaran, S. A.
name: Gopalakrishnan, Sarang
Publisher: name: arXiv
Year: 2016
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Non-Fermi liquids are metals that cannot be adiabatically deformed into free fermion states. We argue for the existence of "non-Fermi glasses," which are phases of interacting disordered fermions that are fully many-body localized, yet cannot be deformed into an Anderson insulator without an eigenstate phase transition. We explore the properties of such non-Fermi glasses, focusing on a specific solvable example. At high temperature, non-Fermi glasses have qualitatively similar spectral features to Anderson insulators. We identify a diagnostic, based on ratios of correlation functions, that sharply distinguishes between the two phases even at infinite temperature. We argue that our results and diagnostic should generically apply to the high-temperature behavior of the many-body localized descendants of fractionalized phases.
description: 4 pages, 2 figures, plus supplemental material
Hund's induced Fermi-liquid instabilities and enhanced quasiparticle interactions
Creators: name: Medici, Luca de'
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Hund's coupling is shown to generally favor, in a doped half-filled Mott insulator, an increase in the compressibility culminating in a Fermi-liquid instability towards phase separation. The largest effect is found about the frontier between an ordinary and an orbitally-decoupled ("Hund's") metal. The increased compressibility implies an enhancement of quasiparticle scattering, thus favoring other possible symmetry breakings. This physics is shown to happen in simulations of the 122 Fe-based superconductors, possibly implying the relevance of this mechanism in the enhancement of the the critical temperature for superconductivity.
A New Overview of Secular Period Changes of RR Lyrae stars inM5
Creators: name: Ferro, A. Arellano
name: Ahumada, J. A.
name: Kains, N.
name: Luna, A.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Secular period variations, $β=\dot{P}$, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD $V$ photometry and the historical photometric database available in the literature since 1889. This provides a time baseline of up to 118 years for these variables. The analysis was performed using two independent approaches: first, the classical $O-C$ behaviour of the time of maximum light, and second, via a grid $(P,β)$, where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in $96\%$ of the stars studied no irregular or stochastic variations need to be claimed, but that $66\%$ of the population shows steady period increases or decreases, and that $34\%$ of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of $β$ and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.
description: Accepted in MNRAS, June 3, 2016; 13 pages 3 tables 5 figures
The E-ELT Multi-Object Spectrograph: latest news from MOSAIC
Creators: name: Hammer, F.
name: Morris, S.
name: Kaper, L.
name: Barbuy, B.
name: Cuby, J. G.
name: Roth, M.
name: Jagourel, P.
name: Evans, C. J.
name: Puech, M.
name: Fitzsimons, E.
name: Dalton, G.
name: Rodrigues, M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: There are 8000 galaxies, including 1600 at z larger than 1.6, which could be simultaneously observed in an E-ELT field of view of 40 sq. arcmin. A considerable fraction of astrophysical discoveries require large statistical samples, which can only be obtained with multi-object spectrographs (MOS). MOSAIC will provide a vast discovery space, enabled by a multiplex of 200 and spectral resolving powers of R=5000 and 20000. MOSAIC will also offer the unique capability of more than 10 "high-definition" (multi-object adaptive optics, MOAO) integral-field units, optimised to investigate the physics of the sources of reionization. The combination of these modes will make MOSAIC the world-leading MOS facility, contributing to all fields of contemporary astronomy, from extra-solar planets, to the study of the halo of the Milky Way and its satellites, and from resolved stellar populations in nearby galaxies out to observations of the earliest "first-light" structures in the Universe. It will also study the distribution of the dark and ordinary matter at all scales and epochs of the Universe. Recent studies of critical technical issues such as sky-background subtraction and MOAO have demonstrated that such a MOS is feasible with state-of-the-art technology and techniques. Current studies of the MOSAIC team include further trade-offs on the wavelength coverage, a solution for compensating for the non-telecentric new design of the telescope, and tests of the saturation of skylines especially in the near-IR bands. In the 2020s the E-ELT will become the world's largest optical/IR telescope, and we argue that it has to be equipped as soon as possible with a MOS to provide the most efficient, and likely the best way to follow-up on James Webb Space Telescope (JWST) observations.
description: 10 pages, 3 Figures, in Ground-based and Airborne Instrumentation for Astronomy VI, 2016, Proc. SPIE
Experimental adaptive process tomography
Creators: name: Pogorelov, Ivan
name: Struchalin, Gleb
name: Straupe, Stanislav
name: Radchenko, Igor
name: Kravtsov, Konstantin
name: Kulik, Sergei
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Adaptive measurements were recently shown to significantly improve the performance of quantum state tomography. Utilizing information about the system for the on-line choice of optimal measurements allows to reach the ultimate bounds of precision for state reconstruction. In this article we generalize an adaptive Bayesian approach to the case of process tomography and experimentally show its superiority in the task of learning unknown quantum operations. Our experiments with photonic polarization qubits cover all types of single-qubit channels. We also discuss instrumental errors and the criteria for evaluation of the ultimate achievable precision in an experiment. It turns out, that adaptive tomography provides a lower noise floor in the presence of strong technical noise.
description: 12 pages, 9 figures
The ExoMol project: Software for computing large molecular line lists
Creators: name: Tennyson, Jonathan
name: Yurchenko, S. N.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: The use of variational nuclear motion programs to compute line lists of transition frequencies and intensities is now a standard procedure. The ExoMol project has used this technique to generate line lists for studies of hot bodies such as the atmospheres of exoplanets and cool stars. The resulting line list can be huge: many contain 10 billion or more transitions. This software update considers changes made to our programs during the course of the project to allow for such calculations. This update considers three programs: {\sc Duo} which computed vibronic spectra for diatomics, {\sc DVR3D} which computes rotation-vibration spectra for triatomics, and {\sc TROVE} which computes rotation-vibration spectra for general polyatomic systems. Important updates in functionality include the calculation of quasibound (resonance) states and Landé $g$-factors by {\sc Duo} and the calculation of resonance states by {\sc DVR3D}. Significant algorithmic improvements are reported for both {\sc DVR3D} and {\sc TROVE}. All three programs are publically available from ccpforge.cse.rl.ac.uk. Future developments are also considered.
description: 27 pages, 4 figure, 0 tables. Internat. J Quantum Chem (in press) Software News & Update article
A Study of Ro-vibrational OH Emission from Herbig Ae/Be Stars
Creators: name: Brittain, Sean D.
name: Najita, Joan R.
name: Carr, John S.
name: Ádámkovics, Máté
name: Reynolds, Nickalas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present a study of ro-vibrational OH and CO emission from 21 disks around Herbig Ae/Be stars. We find that the OH and CO luminosities are proportional over a wide range of stellar ultraviolet luminosities. The OH and CO line profiles are also similar, indicating that they arise from roughly the same radial region of the disk. The CO and OH emission are both correlated with the far-ultraviolet luminosity of the stars, while the PAH luminosity is correlated with the longer wavelength ultraviolet luminosity of the stars. Although disk flaring affects the PAH luminosity, it is not a factor in the luminosity of the OH and CO emission. These properties are consistent with models of UV-irradiated disk atmospheres. We also find that the transition disks in our sample, which have large optically thin inner regions, have lower OH and CO luminosities than non-transition disk sources with similar ultraviolet luminosities. This result, while tentative given the small sample size, is consistent with the interpretation that transition disks lack a gaseous disk close to the star.
description: 15 pages, 7 figures, to be published in The Astrophysical Journal
The Dynamical Response of Dark Matter to Galaxy Evolution Affects Direct-Detection Experiments
Creators: name: Petersen, Michael S.
name: Katz, Neal
name: Weinberg, Martin D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Over a handful of rotation periods, dynamical processes in barred galaxies induce non-axisymmetric structure in dark matter halos. Using n-body simulations of a Milky Way-like barred galaxy, we identify both a trapped dark-matter component, a shadow bar, and a strong response wake in the dark-matter distribution that affects the predicted dark-matter detection rates for current experiments. The presence of a baryonic disk together with well-known dynamical processes (e.g. spiral structure and bar instabilities) increase the dark matter density in the disk plane. We find that the magnitude of the combined stellar and shadow bar evolution, when isolated from the effect of the axisymmetric gravitational potential of the disk, accounts for >30% of this overall increase in disk-plane density. This is significantly larger that of previously claimed deviations from the standard halo model. The dark-matter density and kinematic wakes driven by the Milky Way bar increase the detectability of dark matter overall, especially for the experiments with higher $v_{min}$. These astrophysical features increase the detection rate by more than a factor of two when compared to the standard halo model and by a factor of ten for experiments with high minimum recoil energy thresholds. These same features increase (decrease) the annual modulation for low (high) minimum recoil energy experiments. We present physical arguments for why these dynamics are generic for barred galaxies such as the Milky Way rather than contingent on a specific galaxy model.
description: 16 pages, 7 figures, submitted to Phys Rev D
Process for Low-Temperature Metal-Organic Chemical Vapor Deposition of Tungsten Nitride and Tungsten Nitride Films US Pat. 6,884,466
Creators: name: Kaloyeros, Alain E
name: Arkles, Barry C
Publisher: name: Zenodo
Year: 2005
Subjects: Tungsten Nitride
Chemical Vapor Deposition (CVD)

description: Processes for producing tungsten nitride and tungsten nitride films are provided in which a tungsten carbonyl compound and a nitrogen-containing reactant gas are reacted at a temperature below about 600°C. Tungsten nitride precursors are also included which comprise a tungsten carbonyl compound capable of forming a tungsten nitride film in the presence of a nitrogen-containing reactant gas at a temperature of less than about 600°C. A process for forming a film by atomic layer deposition is also provided which includes introducing a substrate having a surface into a deposition chamber and heating the substrate to a temperature sufficient to allow adsorption of a tungsten source precursor or an intermediate thereof, and thereafter sequentially introducing by pulsing: a tungsten source precursor which is absorbed as a monolayer, a purging inert gas, a nitrogen-containing gas for reacting with the monolayer to form a first tungsten nitride layer on the substrate surface, and an inert purging gas, and repeating the sequence to form a film of desired thickness.
Analysis of ionic conductance of carbon nanotubes
Creators: name: Biesheuvel, P. M.
name: Bazant, M. Z.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We use space-charge (SC) theory (also called the capillary pore model) to describe the ionic conductance, $G$, of charged carbon nanotubes (CNTs). Based on the reversible adsorption of hydroxyl ions to CNT pore walls, we use a Langmuir isotherm for surface ionization and make calculations as function of pore size, salt concentration $c$, and pH. Using realistic values for surface site density and pK, SC theory well describes published experimentally data on the conductance of CNTs. At extremely low salt concentration, when the electric potential becomes uniform across the pore, and surface ionization is low, we derive the scaling $G\sim \sqrt{c}$, while for realistic salt concentrations, SC theory does not lead to a simple power law for $G(c)$.
Wave Front Shaping in Quasi-One-Dimensional Waveguides
Creators: name: Böhm, Julian
name: Kuhl, Ulrich
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Using 10 monopole antennas reaching into a rectangular multi mode waveguide we shape the incident wave to create specific transport even after scattering events. Each antenna is attached to an IQ-Modulator, which allows the adjustment of the amplitude and phase in a broad band range of 6-18 GHz. All of them are placed in the near field of the other, thus the excitation of an individual antenna is influenced by the presence of the other antennas. Still these 10 antennas are sufficient to generate any combination of the 10 propagating modes in the far field. At the output the propagating modes are extracted using a movable monopole antenna that is scanning the field. If the modes are scattered in a scattering region, the incident wave can be adjusted in such a way, that the outgoing wave can still be adjusted as long as localization is not present.
description: 6 pages, 8 figures
High Current Density and Low Thermal Conductivity of Atomically Thin Semimetallic WTe2
Creators: name: Mleczko, Michal J.
name: Runjie
name: Xu
name: Okabe, Kye
name: Kuo, Hsueh-Hui
name: Fisher, Ian R.
name: Wong, H. -S. Philip
name: Nishi, Yoshio
name: Pop, Eric
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Two-dimensional (2D) semimetals beyond graphene have been relatively unexplored in the atomically-thin limit. Here we introduce a facile growth mechanism for semimetallic WTe2 crystals, then fabricate few-layer test structures while carefully avoiding degradation from exposure to air. Low-field electrical measurements of 80 nm to 2 um long devices allow us to separate intrinsic and contact resistance, revealing metallic response in the thinnest encapsulated and stable WTe2 devices studied to date (3 to 20 layers thick). High-field electrical measurements and electro-thermal modeling demonstrate that ultra-thin WTe2 can carry remarkably high current density (approaching 50 MA/cm2, higher than most common interconnect metals) despite a very low thermal conductivity (of the order ~3 W/m/K). These results suggest several pathways for air-stable technological viability of this layered semimetal.
On the properties of compact groups identified in different photometric bands
Creators: name: Taverna, Antonela
name: Diaz-Gimenez, Eugenia
name: Zandivarez, Ariel
name: Joray, Francisco
name: Kanagusuku, Maria Jose
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Historically, compact group catalogues vary not only in their identification algorithms and selection functions, but also in their photometric bands. Differences between compact group catalogues have been reported. However, it is difficult to assess the impact of the photometric band in these differences given the variety of identification algorithms. We used the mock lightcone built by Henriques et al. (2012) to identify and compare compact groups in three different photometric bands: $K$, $r$, and $u$. We applied the same selection functions in the three bands, and found that compact groups in the u-band look the smallest in projection, the difference between the two brightest galaxies is the largest in the K-band, while compact groups in the r-band present the lowest compactness. We also investigated the differences between samples when galaxies are selected only in one particular band (pure compact groups) and those that exist regardless the band in which galaxies were observed (common compact groups). We found that the differences between the total samples are magnified, but also some others arise: pure-r compact groups are the largest in projection; pure-u compact groups have the brightest first ranked galaxies, and the most similar two first ranked galaxies; pure-K compact groups have the highest compactness and the most different two first ranked galaxies; and common compact groups show the largest percentage of physically dense groups. Therefore, without a careful selection and identification of the samples, the characteristic features of group properties in a particular photometric band could be overshadowed.
description: 9 pages, 3 figures, 5 tables. Accepted for publication in MNRAS
A Novel Nanoporous Graphite Based on Graphynes: First Principles Structure and Carbon Dioxide Preferential Physisorption
Creators: name: Bartolomei, Massimiliano
name: Giorgi, Giacomo
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Ubiquitous graphene is a stricly 2D material representing an ideal adsorbing platform due to its large specific surface area as well as its mechanical strength and resistance to both thermal and chemical stresses. However, graphene as a bulk material has the tendency to form irreversible agglomerates leading to 3D graphitic structures with a significant decrease of the area available for adsorption and no room for gas intercalation. In this paper a novel nanoporous graphite formed by graphtriyne sheets is introduced: its 3D structure is theoretically assessed by means of electronic structure and molecular dynamics computations within the DFT level of theory. It is found that the novel layered carbon allotrope is almost as compact as pristine graphite but the inherent porosity of the 2D graphyne sheets and its relative stacking leads to nanochannels that cross the material and whose sub-nanometer size could allow the diffusion and storage of gas species. A molecular prototype of the nanochannel is used to accurately determine first principles adsorption energies and enthalpies for CO2, N2, H2O and H2 within the pores. The proposed porous graphite presents no significant barrier for gas diffusion and it shows a high propensity for CO2 physisorption with respect to the other relevant components in both pre- and post-combustion gas streams.
Magnetohydrodynamic DiscWinds and LineWidth Distributions.II
Creators: name: Chajet, L. S.
name: Hall, P. B.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We study AGN emission line profiles combining an improved version of the accretion disc-wind model of Murray & Chiang with the magneto-hydrodynamic model of Emmering et al. (1992). Here we extend our previous work to consider central objects with different masses and/or luminosities. We have compared the dispersions in our model C IV linewidth distributions to observational upper limit on that dispersion, considering both smooth and clumpy torus models. Following Fine et al., we transform that scatter in the profile line-widths into a constraint on the torus geometry and show how the half-opening angle of the obscuring structure depends on the mass of the central object and the accretion rate. We find that the results depend only mildly on the dimensionless angular momentum, one of the two integrals of motion that characterise the dynamics of the self-similar ideal MHD outflows
description: 17 pages, 14 figures, to appear in MNRAS
Spin-glass phase transition and behavior of nonlinear susceptibility in the Sherrington-Kirkpatrick model with random fields
Creators: name: Morais, C. V.
name: Zimmer, F. M.
name: Lazo, M. J.
name: Magalhães, S. G.
name: Nobre, F. D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The behavior of the nonlinear susceptibility $χ_3$ and its relation to the spin-glass transition temperature $T_f$, in the presence of random fields, are investigated. To accomplish this task, the Sherrington-Kirkpatrick model is studied through the replica formalism, within a one-step replica-symmetry-breaking procedure. In addition, the dependence of the Almeida-Thouless eigenvalue $λ_{\rm AT}$ (replicon) on the random fields is analyzed. Particularly, in absence of random fields, the temperature $T_f$ can be traced by a divergence in the spin-glass susceptibility $χ_{\rm SG}$, which presents a term inversely proportional to the replicon $λ_{\rm AT}$. As a result of a relation between $χ_{\rm SG}$ and $χ_3$, the latter also presents a divergence at $T_f$, which comes as a direct consequence of $λ_{\rm AT}=0$ at $T_f$. However, our results show that, in the presence of random fields, $χ_3$ presents a rounded maximum at a temperature $T^{*}$, which does not coincide with the spin-glass transition temperature $T_f$ (i.e., $T^* > T_f$ for a given applied random field). Thus, the maximum value of $χ_3$ at $T^*$ reflects the effects of the random fields in the paramagnetic phase, instead of the non-trivial ergodicity breaking associated with the spin-glass phase transition. It is also shown that $χ_3$ still maintains a dependence on the replicon $λ_{\rm AT}$, although in a more complicated way, as compared with the case without random fields. These results are discussed in view of recent observations in the LiHo$_x$Y$_{1-x}$F$_4$ compound.
description: accepted for publication in PRB
A Dynamical Mechanism for Large Volumes with Consistent Couplings
Creators: name: Abel, Steven
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A mechanism for addressing the 'decompactification problem' is proposed, which consists of balancing the vacuum energy in Scherk-Schwarzed theories against contributions coming from non- perturbative physics. Universality of threshold corrections ensures that, in such situations, the stable minimum will have consistent gauge couplings for any gauge group that shares the same N = 2 beta function for the bulk excitations as the gauge group that takes part in the minimisation. Scherk- Schwarz compactification from 6D to 4D in heterotic strings is discussed explicitly, together with two alternative possibilities for the non-perturbative physics, namely metastable SQCD vacua and a single gaugino condensate. In the former case, it is shown that modular symmetries gives various consistency checks, and allow one to follow soft-terms, playing a similar role to R-symmetry in global SQCD. The latter case is particularly attractive when there is nett Bose-Fermi degeneracy in the massless sector. In such cases, because the original Casimir energy is generated entirely by excited and/or non-physical string modes, it is completely immune to the non-perturbative IR physics. The large separation between UV and IR contributions to the potential greatly simplifies the analysis of stabilisation, and is a general possibility that has not been considered before.
description: 28 pages, 8 figures
Multidomain Skyrmion Lattice State in Cu$_2$OSeO$_3$
Creators: name: Zhang, S. L.
name: Bauer, A.
name: Burn, D. M.
name: Milde, P.
name: Neuber, E.
name: Eng, L. M.
name: Berger, H.
name: Pfleiderer, C.
name: van der Laan, G.
name: Hesjedal, T.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Magnetic skyrmions in chiral magnets are nanoscale, topologically-protected magnetization swirls that are promising candidates for spintronics memory carriers. Therefore, observing and manipulating the skyrmion state on the surface level of the materials are of great importance for future applications. Here, we report a controlled way of creating a multidomain skyrmion state near the surface of a Cu$_{2}$OSeO$_{3}$ single crystal, observed by soft resonant elastic x-ray scattering. This technique is an ideal tool to probe the magnetic order at the $L_{3}$ edge of $3d$ metal compounds giving a depth sensitivity of ${\sim}50$ nm. The single-domain sixfold-symmetric skyrmion lattice can be broken up into domains overcoming the propagation directions imposed by the cubic anisotropy by applying the magnetic field in directions deviating from the major cubic axes. Our findings open the door to a new way to manipulate and engineer the skyrmion state locally on the surface, or on the level of individual skyrmions, which will enable applications in the future.
description: 19 pages, 5 figures
title: Boulder Creek Bridge Replacement
titleType: AlternativeTitle
title: Endangered Species Act Section 7(a)(2) Biological Opinion and Magnuson–Stevens Fishery Conservation and Management Act Essential Fish Habitat Response for the Boulder Creek Bridge Replacement Project; Boulder Creek Subwatershed (HUC 170602100501); Adams County, ID
Creators: name: United States. National Marine Fisheries Service. West Coast Region
Publisher: name: United States. National Marine Fisheries Service. West Coast Region
Year: 2023

description: WCRO-2023-00378
Optical activity of quantum wells
Creators: name: Kotova, L. V.
name: Platonov, A. V.
name: Kats, V. N.
name: Kochereshko, V. P.
name: Sorokin, S. V.
name: Ivanov, S. V.
name: Golub, L. E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: We report on the observation of optical activity of quantum wells resulting in the conversion of the light polarization state controlled by the light propagation direction. The polarization conversion is detected in reflection measurements. We show that a pure $s$-polarized light incident on a quantum well is reflected as an elliptically polarized wave. The signal is drastically enhanced in the vicinity of the light-hole exciton resonance. We show that the polarization conversion is caused by the spin-orbit splitting of the light hole states and the birefringence of the studied structure. The bulk inversion asymmetry constant $β_{h} \approx 0.14$ eVÅ, is determined for the ground light hole subband in a 10 nm ZnSe/ZnMgSSe quantum well.
description: 5 pages, 3 figures and Online Supplemental Material (4 pages, 4 figures)
A parabolic Triebel-Lizorkin space estimate for the fractional Laplacian operator
Creators: name: Yang, Minsuk
Publisher: name: arXiv
Year: 2016
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics

description: In this paper we prove a parabolic Triebel-Lizorkin space estimate for the operator given by \[T^αf(t,x) = \int_0^t \int_{{\mathbb R}^d} P^α(t-s,x-y)f(s,y) dyds,\] where the kernel is \[P^α(t,x) = \int_{{\mathbb R}^d} e^{2πix\cdotξ} e^{-t|ξ|^α} dξ.\] The operator $T^α$ maps from $L^{p}F_{s}^{p,q}$ to $L^{p}F_{s+α/p}^{p,q}$ continuously. It has an application to a class of stochastic integro-differential equations of the type $du = -(-Δ)^{α/2} u dt + f dX_t$.
description: 8 pages
Light-cone sum rule approach for Baryon form factors
Creators: name: Offen, Nils
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We present the state-of-the-art of the light-cone sum rule approach to Baryon form factors. The essence of this approach is that soft Feynman contributions are calculated in terms of small transverse distance quantities using dispersion relations and duality. The form factors are thus expressed in terms of nucleon wave functions at small transverse separations, called distribution amplitudes, without any additional parameters. The distribution amplitudes, therefore, can be extracted from the comparison with the experimental data on form factors and compared to the results of lattice QCD simulations.
description: 8 pages,7 figures accepted for publication in "Few-Body Systems" special issue "Nucleon Resonances"
Chains of topological oscillators with instantons and calculable topological observables in topological quantum mechanics
Creators: name: Baulieu, Laurent
name: Toppan, Francesco
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We extend to a possibly infinite chain the conformally invariant mechanical system that was introduced earlier as a toy model for understanding the topological Yang-Mills theory. It gives a topological quantum model that has interesting and computable zero modes and topological invariants. It confirms the recent conjecture by several authors that supersymmetric quantum mechanics may provide useful tools for understanding robotic mechanical systems (Vitelli et al.) and condensed matter properties (Kane et al.), where trajectories of effective models are allowed or not by the conservation of topological indices. The absences of ground state and mass gaps are special features of such systems.
description: This work will appear in a special Nuclear Physics issue "Memoriam Raymond Stora"
Quanta of Geometry and Unification
Creators: name: Chamseddine, Ali H.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: This is a tribute to Abdus Salam's memory whose insight and creative thinking set for me a role model to follow. In this contribution I show that the simple requirement of volume quantization in space-time (with Euclidean signature) uniquely determines the geometry to be that of a noncommutative space whose finite part is based on an algebra that leads to Pati-Salam grand unified models. The Standard Model corresponds to a special case where a mathematical constraint (order one condition) is satisfied. This provides evidence that Salam was a visionary who was generations ahead of his time.
description: To appear in the Proceedings of Abdus Salam 90th Birthday Memorial meeting, Editors L. Brink, M. Duff and K. Phua, 10 pages
The accretion of migrating giant planets
Creators: name: Dürmann, Christoph
name: Kley, Wilhelm
Publisher: name: arXiv
Year: 2016
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: Most studies concerning the growth and evolution of massive planets focus either on their accretion or their migration only. In this work we study both processes concurrently to investigate how they might mutually affect each other. We modeled a 2-dimensional disk with a steady accretion flow onto the central star and embed a Jupiter mass planet at 5.2 au. The disk is locally isothermal and viscosity is modeled using a constant $α$. The planet is held on a fixed orbit for a few hundred orbits to allow the disk to adapt and carve a gap. After this period, the planet is released and free to move according to the gravitational interaction with the gas disk. The mass accretion onto the planet is modeled by removing a fraction of gas from the inner Hill sphere, and the removed mass and momentum can be added to the planet. Our results show that a fast migrating planet is able to accrete more gas than a slower migrating planet. Utilizing a tracer fluid we analyzed the origin of the accreted gas which comes predominantly originating from the inner disk for a fast migrating planet. In case of slower migration the fraction of gas from the outer disk increases. We also found that even for very high accretion rates in some cases gas crosses the planetary gap from the inner to the outer disk. Our simulations show that the crossing of gas changes during the migration process as the migration rate slows down. Therefore classical type II migration where the planet migrates with the viscous drift rate and no gas crosses the gap is no general process but may only occur for special parameters and at a certain time during the orbital evolution of the planet.
description: 9 pages, 14 figures, accepted for publication in A&A
title: ESA Permit Renewal (14344-3R) to UC Davis for White Abalone Captive Propagation Program
titleType: AlternativeTitle
title: Endangered Species Act Section 7(a)(2) Biological Opinion and Magnuson-Stevens Fishery Conservation and Management Act Essential Fish Habitat Response, for the issuance of Scientific Research and Enhancement Permit 14344-3R to University of California, Davis, Office of Research, for field collection, captive breeding, and research on white abalone (Haliotis sorenseni) in California, pursuant to Section 10(a)(1)(A) of the Endangered Species Act of 1973
Creators: name: United States. National Marine Fisheries Service. West Coast Region
Publisher: name: United States. National Marine Fisheries Service. West Coast Region
Year: 2023

description: WCRO-2023-00532
Extensive degeneracy, Coulomb phase and magnetic monopoles in an artificial realization of the square ice model
Creators: name: Perrin, Yann
name: Canals, Benjamin
name: Rougemaille, Nicolas
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: Artificial spin ice systems have been introduced as a possible mean to investigate frustration effects in a well-controlled manner by fabricating lithographically-patterned two-dimensional arrangements of interacting magnetic nanostructures. This approach offers the opportunity to visualize unconventional states of matter, directly in real space, and triggered a wealth of studies at the frontier between nanomagnetism, statistical thermodynamics and condensed matter physics. Despite the strong efforts made these last ten years to provide an artificial realization of the celebrated square ice model, no simple geometry based on arrays of nanomagnets succeeded to capture the macroscopically degenerate ground state manifold of the corresponding model. Instead, in all works reported so far, square lattices of nanomagnets are characterized by a magnetically ordered ground state consisting of local flux-closure configurations with alternating chirality. Here, we show experimentally and theoretically, that all the characteristics of the square ice model can be observed if the artificial square lattice is properly designed. The spin configurations we image after demagnetizing our arrays reveal unambiguous signatures of an algebraic spin liquid state characterized by the presence of pinch points in the associated magnetic structure factor. Local excitations, i.e. classical analogues of magnetic monopoles, are found to be free to evolve in a massively degenerated, divergence-free vacuum. We thus provide the first lab-on-chip platform allowing the investigation of collective phenomena, including Coulomb phases and ice-like physics.
description: 26 pages, 10 figures
Distributed stochastic optimization via matrix exponential learning
Creators: name: Mertikopoulos, Panayotis
name: Belmega, E. Veronica
name: Negrel, Romain
name: Sanguinetti, Luca
Publisher: name: arXiv
Year: 2016
Subjects: subject: Information Theory (cs.IT)
subject: Machine Learning (cs.LG)
subject: Optimization and Control (math.OC)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics

description: In this paper, we investigate a distributed learning scheme for a broad class of stochastic optimization problems and games that arise in signal processing and wireless communications. The proposed algorithm relies on the method of matrix exponential learning (MXL) and only requires locally computable gradient observations that are possibly imperfect and/or obsolete. To analyze it, we introduce the notion of a stable Nash equilibrium and we show that the algorithm is globally convergent to such equilibria - or locally convergent when an equilibrium is only locally stable. We also derive an explicit linear bound for the algorithm's convergence speed, which remains valid under measurement errors and uncertainty of arbitrarily high variance. To validate our theoretical analysis, we test the algorithm in realistic multi-carrier/multiple-antenna wireless scenarios where several users seek to maximize their energy efficiency. Our results show that learning allows users to attain a net increase between 100% and 500% in energy efficiency, even under very high uncertainty.
description: 31 pages, 3 figures
Mass inversion in graphene by proximity to dichalcogenide monolayer
Creators: name: Alsharari, Abdulrhman M.
name: Asmar, Mahmoud M.
name: Ulloa, Sergio E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Proximity effects resulting from depositing a graphene layer on a TMD substrate layer change the dynamics of the electronic states in graphene, inducing spin orbit coupling (SOC) and staggered potential effects. An effective Hamiltonian that describes different symmetry breaking terms in graphene, while preserving time reversal invariance, shows that an inverted mass band gap regime is possible. The competition of different perturbation terms causes a transition from an inverted mass phase to a staggered gap in the bilayer heterostructure, as seen in its phase diagram. A tight-binding calculation of the bilayer validates the effective model parameters. A relative gate voltage between the layers may produce such phase transition in experimentally accessible systems. The phases are characterized in terms of Berry curvature and valley Chern numbers, demonstrating that the system may exhibit quantum spin Hall and valley Hall effects.
description: 5 pages, 4 figures
Magnetic Effects in the Paraxial Regime of Elastic Electron Scattering
Creators: name: Edström, Alexander
name: Lubk, Axel
name: Rusz, Ján
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Based on a recent claim [Phys. Rev. Lett. 116, 127203 (2016)] that electron vortex can be used to image magnetism at the nanoscale in elastic scattering experiments, using transmission electron microscopy, a comprehensive computational study is performed to study magnetic effects in the paraxial regime of elastic electron scattering in magnetic solids. Magnetic interactions from electron vortex beams, spin polarized electron beams and beams with phase aberrations are considered, as they pass through ferromagnetic FePt or antiferromagnetic LaMnAsO. The magnetic signals are obtained by comparing the intensity over a disk in the diffraction plane for beams with opposite angular momentum or aberrations. The strongest magnetic signals are obtained from vortex beams with large orbital angular momentum, where relative magnetic signals above $10^{-3}$ are indicated for $10\hbar$ orbital angular momentum, meaning that relative signals of one percent could be expected with the even larger orbital angular momenta, which have been produced in experimental setups. All results indicate that beams with low acceleration voltage and small convergence angles yield stronger magnetic signals, which is unfortunately problematic for the possibility of high spatial resolution imaging. Nevertheless, under atomic resolution conditions, relative magnetic signals in the order of $10^{-4}$ are demonstrated, corresponding to an increase with one order of magnitude compared to previous work.
Inflowing gas onto a compact obscured nucleus in Arp 299A: Herschel spectroscopic studies of H2O and OH
Creators: name: Falstad, N.
name: González-Alfonso, E.
name: Aalto, S.
name: Fischer, J.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Aims. We probe the physical conditions in the core of Arp 299A and try to put constraints to the nature of its nuclear power source. Methods. We used Herschel Space Observatory far-infrared and submillimeter observations of H2O and OH rotational lines in Arp 299A to create a multi-component model of the galaxy. In doing this, we employed a spherically symmetric radiative transfer code. Results. Nine H2O lines in absorption and eight in emission as well as four OH doublets in absorption and one in emission, are detected in Arp 299A. No lines of the 18O isotopologues, which have been seen in compact obscured nuclei of other galaxies, are detected. The absorption in the ground state OH doublet at 119 μm is found redshifted by ~175 km/s compared to other OH and H2O lines, suggesting a low excitation inflow. We find that at least two components are required in order to account for the excited molecular line spectrum. The inner component has a radius of 20-25 pc, a very high infrared surface brightness (> 3e13 Lsun/kpc^2), warm dust (Td > 90 K), and a large H2 column density (NH2 > 1e24 cm^-2). The outer component is larger (50-100 pc) with slightly cooler dust (70-90 K). In addition, a much more extended inflowing component is required to also account for the OH doublet at 119 μm. Conclusions. The Compton-thick nature of the core makes it difficult to determine the nature of the buried power source, but the high surface brightness indicates that it is either an active galactic nucleus and/or a dense nuclear starburst. The high OH/H2O ratio in the nucleus indicates that ion-neutral chemistry induced by X-rays or cosmic-rays is important. Finally we find a lower limit to the 16O/18O ratio of 400 in the nuclear region, possibly indicating that the nuclear starburst is in an early evolutionary stage, or that it is fed through a molecular inflow of, at most, solar metallicity.
description: 14 pages, 13 figures, Accepted for publication in Astronomy and Astrophysics
Resonant Elastic X-ray Scattering from the Skyrmion Lattice in Cu$_{2}$OSeO$_{3}$
Creators: name: Zhang, S. L.
name: Bauer, A.
name: Berger, H.
name: Pfleiderer, C.
name: van der Laan, G.
name: Hesjedal, T.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We report the study of the skyrmion state near the surface of Cu$_2$OSeO$_3$ using soft resonant elastic x-ray scattering (REXS) at the Cu $L_3$ edge. Within the lateral sampling area of $200 \times 200$ $μ$m$^2$, we found a long-range-ordered skyrmion lattice phase as well as the formation of skyrmion domains via the multiple splitting of the diffraction spots. In a recent REXS study of the skyrmion phase of Cu$_2$OSeO$_3$ [Phys. Rev. Lett. 112, 167202 (2014)], Langner et al. reported the observation of the unexpected existence of two distinct skyrmion sublattices that arise from inequivalent Cu sites, and that the rotation and superposition of the two periodic structures leads to a moiré pattern. However, we find no energy splitting of the Cu peak in x-ray absorption measurements and, instead, discuss alternative origins of the peak splitting. In particular, we find that for magnetic field directions deviating from the major cubic axes, a multidomain skyrmion lattice state is obtained, which consistently explains the splitting of the magnetic spots into two - and more - peaks.
description: 6 pages, 3 figures
Isospin dependence of nucleon effective masses in neutron-rich matter
Creators: name: Li, Bao-An
name: Cai, Bao-Jun
name: Chen, Lie-Wen
name: Li, Xiao-Hua
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Theory (nucl-th)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: In this talk, we first briefly review the isospin dependence of the total nucleon effective mass $M^{\ast}_{J}$ inferred from analyzing nucleon-nucleus scattering data within an isospin dependent non-relativistic optical potential model, and the isospin dependence of the nucleon E-mass $M^{\ast,\rm{E}}_{J}$ obtained from applying the Migdal-Luttinger theorem to a phenomenological single-nucleon momentum distribution in nuclei constrained by recent electron-nucleus scattering experiments. Combining information about the isospin dependence of both the nucleon total effective mass and E-mass, we then infer the isospin dependence of nucleon k-mass using the well-known relation $M^{\ast}_{J}=M^{\ast,\rm{E}}_{J}\cdot M^{\ast,\rm{k}}_{J}$. Implications of the results on the nucleon mean free path (MFP) in neutron-rich matter are discussed.
description: An invited talk given at the 5th International Workshop on Nuclear Dynamics in Heavy-Ion Reactions (IWND2016), Xinxiang, China, May 15-20, 2016