cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
SCENAR2020: Future of European Agriculture under Different Policy Options, the economic modelling framework
Creators: name: Banse, Martin
name: Helming, John F.M.
name: Van Meijl, Hans
name: Nowicki, Peter
name: Banse, Martin
name: Helming, John F.M.
name: Van Meijl, Hans
name: Nowicki, Peter
Publisher: name: Unknown
Year: 2008
Subjects: subject: Agricultural and Food Policy
subject: International Relations/Trade
subject: Livestock Production/Industries
subject: Economic Modelling
subject: Future
subject: CAP Policy Options
subject: Structural Change

description: This paper identifies major future trends and driving factors and perspectives and challenges resulting from them for European agriculture and food sectors until the year 2020. The focus of the paper is an analysis of key driving forces and the provision of a well developed reference scenario under the assumption of continued CAP reform and taking into account the framework discussions in the Doha Development Round. To assess the impact of policies the paper also examines a liberalisation (no support) and regionalisation (max support) scenario. In terms of policy options the paper shows that structural change process in agriculture is a long-term process that continues with or without policy changes. EU is facing an increasing diversity of structure and structural adjustment. The livestock sector faces important challenges and restructuring. Alternative policy settings may not produce very different effect on the overall production. However, the regional impact may prove to be more significant.
Analysis of Stops With Small Stop-Neutralino Mass Difference at a LC
Creators: name: Milstene, C.
name: Carena, M.
name: Finch, A.
name: Freitas, A.
name: Nowak, H.
name: Sopczak, A.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: A compelling framework to explain dark matter and electroweak baryogenesis is supersymmetry with light scalar top quarks (stops) and a small mass difference between the stop and the lightest neutralino. In this work, the stop detection capability at the ILC for small mass differences between the stop and the neutralino is studied. The analysis is based on a fast and realistic detector simulation. Significant sensitivity for mass differences down to 5 GeV is obtained. It is discussed how the relevant parameters of the scalar tops can be extracted and used to compute the dark matter density in the universe.
description: 6pp, to appear in the proceedings of the 2005 International Linear Collider Workshop (LCWS 05), Stanford, California, 18-22 March 2005
Mean-field dynamics of infinite-dimensional particle systems: global shear versus random local forcing
Creators: name: Agoritsas, Elisabeth
Publisher: name: arXiv
Year: 2020
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: In infinite dimension, many-body systems of pairwise interacting particles provide exact analytical benchmarks for features of amorphous materials, such as the stress-strain curve of glasses under quasistatic shear. Here, instead of a global shear, we consider an alternative driving protocol as recently introduced in Ref. [1], which consists of randomly assigning a constant local displacement on each particle, with a finite spatial correlation length. We show that, in the infinite-dimension limit, the mean-field dynamics under such a random forcing is strictly equivalent to that under global shear, upon a simple rescaling of the accumulated strain. Moreover, the scaling factor is essentially given by the variance of the relative local displacements on interacting pairs of particles, which encodes the presence of a finite spatial correlation. In this framework, global shear is simply a special case of a much broader family of local forcing, that can be explored by tuning its spatial correlations. We discuss specifically the implications on the quasistatic driving of glasses -- initially prepared at a replica-symmetric equilibrium -- and how the corresponding 'stress-strain'-like curves and the elastic moduli can be rescaled onto their quasistatic-shear counterparts. These results hint at a unifying framework for establishing rigourous analogies, at the mean-field level, between different driven disordered systems.
Two-dimensional topological superconductivity candidate in van der Waals layered material
Creators: name: You, Jing-Yang
name: Gu, Bo
name: Su, Gang
name: Feng, Yuan Ping
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Two-dimensional (2D) topological superconductors are highly desired because they not only offer opportunities for exploring novel exotic quantum physics, but also possesses potential applications in quantum computation. However, there are few reports on 2D superconductors, let alone topological superconductors. Here, we find a 2D monolayer W$_2$N$_3$, which can be exfoliated from its real van der Waals bulk material with much lower exfoliation energy than MoS$_2$, to be a topological metal with exotic topological states at different energy level. Due to the Van Hove singularities, the density of states near Fermi level are high, making the monolayer a compensate metal. Moreover, the monolayer W$_2$N$_3$ is unveiled to be a superconductor with the superconducting transition temperature Tc $\sim$ 22 K and a superconducting gap of about 5 meV based on the anisotropic Migdal-Eliashberg formalism, arising from the strong electron-phonon coupling around the $Γ$ point. Because of the strong electron and lattice coupling, the monolayer displays a non-Fermi liquid behavior in its normal states at temperatures lower than 80 K, where the specific heat exhibit T$^3$ behavior and the Wiedemann-Franz law dramatically violates. Our findings not only provide the platform to study the emergent phenomena in 2D topological superconductors, but also open a door to discover more 2D high-temperature topological superconductors in van der Waals materials.
Frequency-independent terahertz anomalous Hall effect in DyCo$_{5}$, Co$_{32}$Fe$_{68}$ and Gd$_{27}$Fe$_{73}$ thin films from DC to 40 THz
Creators: name: Seifert, Tom S.
name: Martens, Ulrike
name: Radu, Florin
name: Ribow, Mirkow
name: Berritta, Marco
name: Nádvorník, Lukas
name: Starke, Ronald
name: Jungwirth, Tomas
name: Wolf, Martin
name: Radu, Ilie
name: Münzenberg, Markus
name: Oppeneer, Peter M.
name: Woltersdorf, Georg
name: Kampfrath, Tobias
Publisher: name: arXiv
Year: 2020
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The anomalous Hall effect (AHE) is a fundamental spintronic charge-to-charge-current conversion phenomenon and closely related to spin-to-charge-current conversion by the spin Hall effect. Future high-speed spintronic devices will crucially rely on such conversion effects at terahertz (THz) frequencies. Here, we reveal that the AHE remains operative from DC up to 40 THz with a flat frequency response in thin films of three technologically relevant magnetic materials: DyCo$_{5}$, Co$_{32}$Fe$_{68}$ and Gd$_{27}$Fe$_{73}$. We measure the frequency-dependent conductivity-tensor elements $σ_{xx}$ and $σ_{yx}$ and find good agreement with DC measurements. Our experimental findings are fully consistent with ab-initio calculations of $σ_{yx}$ for CoFe and highlight the role of the large Drude scattering rate (~100 THz) of metal thin films, which smears out any sharp spectral features of the THz AHE. Finally, we find that the intrinsic contribution to the THz AHE dominates over the extrinsic mechanisms for the Co$_{32}$Fe$_{68}$ sample. The results imply that the AHE and related effects such as the spin Hall effect are highly promising ingredients of future THz spintronic devices reliably operating from DC to 40 THz and beyond.
Observations of time delayed all-optical routing in a slow light regime
Creators: name: Ham, B. S.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We report an observation of a delayed all-optical routing/switching phenomenon based on ultraslow group velocity of light via nondegenerate four-wave mixing processes in a defected solid medium. Unlike previous demonstrations of enhanced four-wave mixing processes using the slow light effects, the present observation demonstrates a direct retrieval of the resonant Raman-pulse excited spin coherence into photon coherence through coherence conversion processes.
description: 5 pages with 3 figures included
Transcription of the narration of Reel #3 (collection LA 256)
Creators: name: Parker, Verdena
name: Lee-Wynant, Tyler
name: Spence, Justin
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2020
Subjects: subject: hup

description: Audio files VP-201217-07a and VP-201217-08a/c: transcription of VP-180317-09 (narration of Reel #3 from the LA 256 collection at SCOIL, one of six reels of 8mm film created by Verdena in the 1960s, featuring scenes of everyday life around Hoopa Valley as well as Brush Dances), from 4:01 to approximately 5:35 (VP-201217-07a) and from 5:35 to 7:03 (VP-201217-08a/c). Due to re-numbering, Reel #3 has been assigned the CLA item number LA 256.042.
Bearing-Only Navigation with Field of View Constraints
Creators: name: Karimian, Arman
name: Tron, Roberto
Publisher: name: arXiv
Year: 2020
Subjects: subject: Systems and Control (eess.SY)
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: This paper addresses the problem of navigation using only relative direction measurements (i.e., relative distances are unknown) under field of view constraints. We present a novel navigation vector field for the bearing-based visual homing problem with respect to static visual landmarks in 2-D and 3-D environments. Our method employs two control fields that are tangent and normal to ellipsoids having landmarks as their foci. The tangent field steers the robot to a set of points where the average of observed bearings is parallel to the average of the desired bearings, and the normal field uses the angle between a pair of bearings as a proxy to adjust the robot's distance from landmarks and to satisfy the field of view constraints. Both fields are blended together to construct an almost globally stable control law. Our method is easy to implement, as it requires only comparisons between average bearings, and between angles of pairs of vectors. We provide simulations that demonstrate the performance of our approach for a double integrator system and unicycles.
Electron spin-orbit splitting in InGaAs/InP quantum well studied by means of the weak antilocalization and spin-zero effects in tilted magnetic fields
Creators: name: Studenikin, S. A.
name: Coleridge, P. T.
name: Yu, G.
name: Poole, P. J.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The coupling between Zeeman spin splitting and Rashba spin-orbit terms has been studied experimentally in a gated InGaAs/InP quantum well structure by means of simultaneous measurements of the weak antilocalization (WAL) effect and beating in the SdH oscillations. The strength of the Zeeman splitting was regulated by tilting the magnetic field with the spin-zeros in the SdH oscillations, which are not always present, being enhanced by the tilt. In tilted fields the spin-orbit and Zeeman splittings are not additive, and a simple expression is given for the energy levels. The Rashba parameter and the electron g-factor were extracted from the position of the spin zeros in tilted fields. A good agreement is obtained for the spin-orbit coupling strength from the spin-zeros and weak antilocalization measurements.
description: Accepted for publication in Semiconductors Science and Technology
Passive Sliders on Fluctuating Surfaces: Strong-Clustering States
Creators: name: Nagar, Apoorva
name: Barma, Mustansir
name: Majumdar, Satya N.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We study the clustering properties of particles sliding downwards on a fluctuating surface evolving through the Kardar-Parisi-Zhang equation, a problem equivalent to passive scalars driven by a Burgers fluid. Monte Carlo simulations on a discrete version of the problem in one dimension reveal that particles cluster very strongly: the two point density correlation function scales with the system size with a scaling function which diverges at small argument. Analytic results are obtained for the Sinai problem of random walkers in a quenched random landscape. This equilibrium system too has a singular scaling function which agrees remarkably with that for advected particles.
description: To be published in Physical Review Letters
An explainable deep vision system for animal classification and detection in trail-camera images with automatic post-deployment retraining
Creators: name: Moallem, Golnaz
name: Pathirage, Don D.
name: Reznick, Joel
name: Gallagher, James
name: Sari-Sarraf, Hamed
Publisher: name: arXiv
Year: 2020
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: This paper introduces an automated vision system for animal detection in trail-camera images taken from a field under the administration of the Texas Parks and Wildlife Department. As traditional wildlife counting techniques are intrusive and labor intensive to conduct, trail-camera imaging is a comparatively non-intrusive method for capturing wildlife activity. However, given the large volume of images produced from trail-cameras, manual analysis of the images remains time-consuming and inefficient. We implemented a two-stage deep convolutional neural network pipeline to find animal-containing images in the first stage and then process these images to detect birds in the second stage. The animal classification system classifies animal images with overall 93% sensitivity and 96% specificity. The bird detection system achieves better than 93% sensitivity, 92% specificity, and 68% average Intersection-over-Union rate. The entire pipeline processes an image in less than 0.5 seconds as opposed to an average 30 seconds for a human labeler. We also addressed post-deployment issues related to data drift for the animal classification system as image features vary with seasonal changes. This system utilizes an automatic retraining algorithm to detect data drift and update the system. We introduce a novel technique for detecting drifted images and triggering the retraining procedure. Two statistical experiments are also presented to explain the prediction behavior of the animal classification system. These experiments investigate the cues that steers the system towards a particular decision. Statistical hypothesis testing demonstrates that the presence of an animal in the input image significantly contributes to the system's decisions.
Localization of Gauged Linear Sigma Model for KK5-branes
Creators: name: Hiraga, Yuki
name: Sato, Yuki
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study quantum aspects of the target space of the non-linear sigma model which is a low-energy effective theory of the gauged linear sigma model (GLSM). As such, we especially compute the exact sphere partition function of GLSM for KK$5$-branes whose background geometry is a Taub-NUT space, using the supersymmetric localization technique on the Coulomb branch. From the sphere partition function, we distill the world-sheet instanton effects. In particular, we show that concerning the single-centered Taub-NUT space, the instanton contributions exist only if the asymptotic radius of the $S^1$ fiber in the Taub-NUT space is zero.
description: 33 pages, multi-centered case corrected, appendix F added, typos corrected, matching version to be published in PTEP
Spin-Triplet Excitons in the $S=1/2$ Gapped Antiferromagnet BaCuSi$_2$O$_6$: Electron Paramagnetic Resonance Studies
Creators: name: Zvyagin, S. A.
name: Wosnitza, J.
name: Krzystek, J.
name: Stern, R.
name: Jaime, M.
name: Sasago, Y.
name: Uchinokura, K.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Other Condensed Matter (cond-mat.other)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: BaCuSi$_2$O$_6$, a $S=1/2$ quantum antiferromagnet with a double-layer structure of Cu$^{2+}$ ions in a distorted planar-rectangular coordination and with a dimerized spin singlet ground state, is studied by means of the electron paramagnetic resonance technique. It is argued that multiple absorptions observed at low temperatures are intimately related to a thermally-activated spin-triplet exciton superstructure. Analysis of the angular dependence of exciton modes in BaCuSi$_2$O$_6$ allows us to accurately estimate anisotropy parameters. In addition, the temperature dependence of EPR intensity and linewidth is discussed.
description: Submitted to Phys. Rev. B
Majorana bound states in vortex lattices on iron-based superconductors
Creators: name: Pathak, Vedangi
name: Plugge, Stephan
name: Franz, Marcel
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Majorana quasi-particles may arise as zero-energy bound states in vortices on the surface of a topological insulator that is proximitized by a conventional superconductor. Such a system finds its natural realization in the iron-based superconductor FeTe$_{0.55}$Se$_{0.45}$ that combines bulk $s$-wave pairing with spin helical Dirac surface states, and which thus comprises the ingredients for Majorana modes in absence of an additional proximitizing superconductor. In this work, we investigate the emergence of Majorana vortex modes and lattices in such materials depending on parameters like the magnetic field strength and vortex lattice disorder. A simple 2D square lattice model here allows us to capture the basic physics of the underlying materials system. To address the problem of disordered vortex lattice, which occurs in real systems, we adopt the technique of the singular gauge transformation which we modify such that it can be used in a system with periodic boundary conditions. This approach allows us to go to larger vortex lattices than otherwise accessible, and is successful in replicating several experimental observations of Majorana vortex bound states in the FeTe$_{0.55}$Se$_{0.45}$ platform. Finally it can be related to a simple disordered Majorana lattice model that should be useful for further investigations on the role of interactions, and towards topological quantum computation.
description: 36 + 5 pages (single column), 16 + 2 figures, comments welcome. v2: fixed typos, minor changes. Accepted for publication in the Annals of Physics special issue in memory of Phil Anderson
Geometrically constrained statistical systems on regular and random lattices: From folding to meanders
Creators: name: Di Francesco, P.
name: Guitter, E.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: We review a number a recent advances in the study of two-dimensional statistical models with strong geometrical constraints. These include folding problems of regular and random lattices as well as the famous meander problem of enumerating the topologically inequivalent configurations of a meandering road crossing a straight river through a given number of bridges. All these problems turn out to have reformulations in terms of fully packed loop models allowing for a unified Coulomb gas description of their statistical properties. A number of exact results and physically motivated conjectures are presented in detail, including the remarkable meander configuration exponent alpha=(29+sqrt(145))/12.
description: 112 pages, 82 figures, harvmac, mssymb, epsf. Review article
Renormalized Stress Tensor for trans-Planckian Cosmology
Creators: name: Nacir, D. Lopez
name: Mazzitelli, F. D.
name: Simeone, C.
Publisher: name: arXiv
Year: 2005
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Finite expressions for the mean value of the stress tensor corresponding to a scalar field with a generalized dispersion relation in a Friedman--Robertson--Walker universe are obtained using adiabatic renormalization. Formally divergent integrals are evaluated by means of dimensional regularization. The renormalization procedure is shown to be equivalent to a redefinition of the cosmological constant and the Newton constant in the semiclassical Einstein equations.
description: 14 pages. Minor changes; version published in Physical Review D
An information-theoretic security proof for QKD protocols
Creators: name: Renner, R.
name: Gisin, N.
name: Kraus, B.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a new technique for proving the security of quantum key distribution (QKD) protocols. It is based on direct information-theoretic arguments and thus also applies if no equivalent entanglement purification scheme can be found. Using this technique, we investigate a general class of QKD protocols with one-way classical post-processing. We show that, in order to analyze the full security of these protocols, it suffices to consider collective attacks. Indeed, we give new lower and upper bounds on the secret-key rate which only involve entropies of two-qubit density operators and which are thus easy to compute. As an illustration of our results, we analyze the BB84, the six-state, and the B92 protocol with one-way error correction and privacy amplification. Surprisingly, the performance of these protocols is increased if one of the parties adds noise to the measurement data before the error correction. In particular, this additional noise makes the protocols more robust against noise in the quantum channel.
description: 18 pages, 3 figures
On the chiral perturbation theory for two-flavor two-color QCD at finite chemical potential
Creators: name: Brauner, Tomas
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We construct the chiral perturbation theory for two-color QCD with two quark flavors as an effective theory on the SO(6)/SO(5) coset space. This formulation turns out to be particularly useful for extracting the physical content of the theory when finite baryon and isospin chemical potentials are introduced, and Bose--Einstein condensation sets on.
description: 10 pages, 1 eps figure, to be published in Mod. Phys. Lett. A
Supergap and subgap enhanced currents in asymmetric {S_1FS_2} Josephson junctions
Creators: name: Alidoust, Mohammad
name: Halterman, Klaus
Publisher: name: arXiv
Year: 2020
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We have theoretically studied the supercurrent profiles in three-dimensional normal metal and ferromagnetic Josephson configurations, where the magnitude of the superconducting gaps in the superconducting leads are unequal, i.e., $Δ_1\neq Δ_2$, creating asymmetric $S_1NS_2$ and $S_1FS_2$ systems. Our results reveal that by increasing the ratio of the superconducting gaps $Δ_2/Δ_1$, the critical supercurrent in a ballistic $S_1NS_2$ system can be enhanced by more than $100\%$, and reaches a saturation point, or decays away, depending on the junction thickness, magnetization strength, and chemical potential. The total critical current in a diffusive $S_1NS_2$ system was found to be enhanced by more than $50\%$ parabolically, and reaches saturation by increasing one of the superconducting gaps. In a uniform ferromagnetic junction, the supercurrent undergoes reversal by increasing $Δ_2/Δ_1>1$. Through decomposing the total supercurrent into its supergap and subgap components, our results illustrate their crucial relative contributions to the Josephson current flow. It was found that the competition of subgap and supergap currents in a $S_1FS_2$ junction results in the emergence of second harmonics in the current-phase relation. In contrast to a diffusive asymmetric Josephson configuration, the behavior of the supercurrent in a ballistic system with $Δ_2/Δ_1=1$ can be properly described by the subgap current component only, in a wide range of parameter sets, including Fermi level mismatch, magnetization strength, and junction thickness. Interestingly, when $Δ_2/Δ_1>1$, our results have found multiple parameter sets where the total supercurrent is driven by the supergap component. Therefore, our comprehensive study highlights the importance of subgap and supergap supercurrent components in both the ballistic and diffusive regimes.
description: 18 pages, 16 figures
On Number of Nflation Fields
Creators: name: Ahmad, Iftikhar
name: Piao, Yun-Song
name: Qiao, Cong-Feng
Publisher: name: arXiv
Year: 2008
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We study the Nflation model, in which a collection of massive scalar fields drive the inflation simultaneously. We find, when the number of fields is larger than the square of ratio of the Planck scale $M_p$ to the average value $\bar m$ of fields masses, the slow roll inflation region will disappear. This suggests that in order to make Nflation responsible for our observable universe, the number of fields driving the Nflation must be bounded by the above ratio. This result is also consistent with recent arguments from black hole physics.
description: 13 pages, 3 figures;added more comments,to publish in JCAP
Discovery of very high energy gamma-rays associated with an X-ray binary
Creators: name: Collaboration, H. E. S. S.
name: :
name: Aharonian, F.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and X-ray observations have led to the presumption that some X-ray binaries called microquasars behave as scaled down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission >100 GeV from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.
description: 9 pages, 3 figures (including Science Online Material). HESS collaboration homepage at http://www.mpi-hd.mpg.de/hfm/HESS/HESS.html
Hadron Spectroscopy - A 2005 Snapshot
Creators: name: Rosner, Jonathan L.
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Some aspects of hadron spectroscopy are reviewed as of summer 2005.
description: 15 pages, 8 figures, invited talk presented at Physics in Collision 2005, Prague, Czech Republic, July 7-9, 2005. Proceedings to be published by AIP. Uses AIP style files. Typo corrected
Survey of Effectiveness of Transportation Services
Creators: name: Pigman, Jerry G.
name: Agent, Kenneth R.
name: Crabtree, Joseph D.
Publisher: name: Kentucky Transportation Center, University of Kentucky
Year: 1981
Subjects: subject: Transportation Engineering

description: With increased emphasis on public accountability and program evaluation, the need for effectiveness measures to indicate the extent to which an agency's goals and objectives are being met is increasingly apparent. A research study was undertaken to establish and implement a procedure for monitoring the effectiveness of transportation services in Kentucky. Quantitative data for many of the effectiveness measures were obtainable only through responses from the public. Surveys of licensed drivers and bus riders were selected as data sources. This report addresses the procedures and results of the two surveys. Responses were received from 35.5 percent of the 10,000 licensed drivers who were sent questionnaires and 26.0 percent of the 4,560 bus riders. Results from the surveys were summarized into the following areas: (l) survey response, (2) personal information, (3) satisfaction with transportation services, (4) inadequate transportation services, (5) drivers' complaints and compliments, (6) future government spending for transportation, (7) problems getting to various destinations, (8) use of other modes of transportation, (9) opinions on laws or government regulations, and (10) bus rider survey.
Controlling Chaos through Compactification in Cosmological Models with a Collapsing Phase
Creators: name: Wesley, Daniel H.
name: Steinhardt, Paul J.
name: Turok, Neil
Publisher: name: arXiv
Year: 2005
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We consider the effect of compactification of extra dimensions on the onset of classical chaotic "Mixmaster" behavior during cosmic contraction. Assuming a universe that is well-approximated as a four-dimensional Friedmann-Robertson--Walker model (with negligible Kaluza-Klein excitations) when the contraction phase begins, we identify compactifications that allow a smooth contraction and delay the onset of chaos until arbitrarily close the big crunch. These compactifications are defined by the de Rham cohomology (Betti numbers) and Killing vectors of the compactification manifold. We find compactifications that control chaos in vacuum Einstein gravity, as well as in string theories with N = 1 supersymmetry and M-theory. In models where chaos is controlled in this way, the universe can remain homogeneous and flat until it enters the quantum gravity regime. At this point, the classical equations leading to chaotic behavior can no longer be trusted, and quantum effects may allow a smooth approach to the big crunch and transition into a subsequent expanding phase. Our results may be useful for constructing cosmological models with contracting phases, such as the ekpyrotic/cyclic and pre-big bang models.
description: 1 figure. v2/v3: minor typos corrected
Off-shell Noether currents and potentials for first-order general relativity
Creators: name: Montesinos, Merced
name: Gonzalez, Diego
name: Romero, Rodrigo
name: Celada, Mariano
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We report off-shell Noether currents obtained from off-shell Noether potentials for first-order general relativity described by $n$-dimensional Palatini and Holst Lagrangians including the cosmological constant. These off-shell currents and potentials are achieved by using the corresponding Lagrangian and the off-shell Noether identities satisfied by diffeomorphisms generated by arbitrary vector fields, local $SO(n)$ or $SO(n-1,1)$ transformations, `improved diffeomorphisms', and the `generalization of local translations' of the orthonormal frame and the connection. A remarkable aspect of our approach is that we do {\it not} use Noether's theorem in its direct form. By construction, the currents are off-shell conserved and lead naturally to the definition of off-shell Noether charges. We also study what we call the `half off-shell' case for both Palatini and Holst Lagrangians. In particular, we find that the resulting diffeomorphism and local $SO(3,1)$ or $SO(4)$ off-shell Noether currents and potentials for the Holst Lagrangian generically depend on the Immirzi parameter, which holds even in the `half off-shell' and on-shell cases. We also study Killing vector fields in the `half off-shell' and on-shell cases. The current theoretical framework is illustrated for the `half off-shell' case in static spherically symmetric and Friedmann--Lemaitre--Robertson--Walker spacetimes in four dimensions.
description: Published version
Phase transitions in TGFT: Functional renormalization group in the cyclic-melonic potential approximation and equivalence to O$(N)$ models
Creators: name: Pithis, Andreas G. A.
name: Thürigen, Johannes
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In the group field theory approach to quantum gravity, continuous spacetime geometry is expected to emerge via phase transition. However, understanding the phase diagram and finding fixed points under the renormalization group flow remains a major challenge. In this work we tackle the issue for a tensorial group field theory using the functional renormalization group method. We derive the flow equation for the effective potential at any order restricting to a subclass of tensorial interactions called cyclic melonic and projecting to a constant field in group space. For a tensor field of rank $r$ on U$(1)$ we explicitly calculate beta functions and find equivalence with those of O$(N)$ models but with an effective dimension flowing from $r-1$ to zero. In the $r-1$ dimensional regime, the equivalence to O$(N)$ models is modified by a tensor specific flow of the anomalous dimension with the consequence that the Wilson-Fisher type fixed point solution has two branches. However, due to the flow to dimension zero, fixed points describing a transition between a broken and unbroken phase do not persist and we find universal symmetry restoration. To overcome this limitation, it is necessary to go beyond compact configuration space.
description: 38 pages + 8 appendix, 8 figures, 4 tables, typos corrected, consistent with published version
Understanding the Nuclear Gas Dispersion in Early-Type Galaxies in the Context of Black Hole Demographics
Creators: name: Kleijn, Gijs Verdoes
name: van der Marel, Roeland
name: Noel-Storr, Jacob
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: (abridged) We analyze and model HST /STIS observations of a sample of 27 galaxies; 16 Fanaroff & Riley Type I radio galaxies and 11 (more) normal early-type galaxies. We focus here on what can be learned from the nuclear velocity dispersion (line width) of the gas as a complement to the many studies dealing with gas rotation velocities. We find that the dispersion in a STIS aperture of ~0.1''-0.2'' generally exceeds the large-scale stellar velocity dispersion of the galaxy. This is qualitatively consistent with the presence of central BHs, but raises the question whether the excess gas dispersion is of gravitational or non-gravitational origin and whether the implied BH masses are consistent with our current understanding of BH demography(as predicted by the M-sigma relation between BH mass and stellar velocity dispersion). To address this we construct dynamical models for the gas, both thin disk models and models with more general axis ratios and velocity anisotropies. For the normal galaxies the nuclear gas dispersions are adequately reproduced assuming disks around BHs with masses that follow the M-sigma relation. In contrast, the gas dispersions observed for the radio galaxies generally exceed those predicted by any of the models. We attribute this to the presence of non-gravitational motions in the gas that are similar to or larger than the gravitational motions. The non- gravitational motions are presumably driven by the active galactic nucleus (AGN), but we do not find a relation between the radiative output of the AGN and the non-gravitational dispersion. It is not possible to uniquely determine the BH mass for each galaxy from its nuclear gas dispersion. However, for the sample as a whole the observed dispersions do not provide evidence for significant deviations from the M-sigma relation.
description: accepted for publication in the Astronomical Journal
Weakly coupled alternating $S=1/2$ chains in the distorted honeycomb lattice compound Na$_2$Cu$_2$TeO$_6$
Creators: name: Gao, Shang
name: Lin, Ling-Fang
name: May, Andrew F.
name: Rai, Binod K.
name: Zhang, Qiang
name: Dagotto, Elbio
name: Christianson, Andrew D.
name: Stone, Matthew B.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Spin-1/2 chains with alternating antiferromagnetic (AF) and ferromagnetic (FM) couplings exhibit quantum entanglement like the integer-spin Haldane chains and might be similarly utilized for quantum computations. Such alternating AF-FM chains have been proposed to be realized in the distorted honeycomb-lattice compound Na$_2$Cu$_2$TeO$_6$, but to confirm this picture a comprehensive understanding of the exchange interactions including terms outside of the idealized model is required. Here we employ neutron scattering to study the spin dynamics in Na$_2$Cu$_2$TeO$_6$ and accurately determine the coupling strengths through the random phase approximation and density functional theory (DFT) approaches. We find the AF and FM intrachain couplings are the dominant terms in the spin Hamiltonian, while the interchain couplings are AF but perturbative. This hierarchy in the coupling strengths and the alternating signs of the intrachain couplings can be understood through their different exchange paths. Our results establish Na$_2$Cu$_2$TeO$_6$ as a weakly-coupled alternating AF-FM chain compound and reveal the robustness of the gapped ground state in alternating chains under weak interchain couplings.
description: 9 pages, 7 figures
Meron, skyrmion, and vortex crystals in centrosymmetric tetragonal magnets
Creators: name: Wang, Zhentao
name: Su, Ying
name: Lin, Shi-Zeng
name: Batista, Cristian D.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: The recent experimental confirmation of a transformation between meron and skyrmion topological spin textures in the chiral magnet Co$_8$Zn$_9$Mn$_3$ [S.-Z. Lin et al., Phys. Rev. B 91, 224407 (2015); X. Z. Yu et al., Nature 564, 95 (2018)] confirms that the skyrmion crystals discovered in 2009 [S. Mühlbauer et al., Science 323, 915 (2009)] are just the tip of the iceberg. Crystals of topological textures, including skyrmions, merons, vortices, and monopoles, can be stabilized by combining simple physical ingredients, such as lattice symmetry, frustration, and spin anisotropy. The current challenge is to find the combinations of these ingredients that produce specific topological spin textures. Here we report a simple mechanism for the stabilization of meron, skyrmion, and vortex crystals in centrosymmetric tetragonal magnets. In particular, the meron/skyrmion crystals can form even in absence of magnetic field. The application of magnetic field leads to a rich variety of topological spin textures that survive in the long wavelength limit of the theory. When conduction electrons are coupled to the spins, these topological spin textures twist the electronic wave functions to induce Chern insulators and Weyl semimetals for specific band filling fractions.
description: 13 pages, 10 figures
On the horizon entropy of a causal set
Creators: name: Machet, Ludovico
name: Wang, Jinzhao
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We discuss how to define a kinematical horizon entropy on a causal set. We extend a recent definition of horizon molecules to a setting with a null hypersurface crossing the horizon. We argue that, as opposed to the spacelike case, this extension fails to yield an entropy local to the hypersurface-horizon intersection in the continuum limit when the causal set approximates a curved spacetime. We then investigate the entropy defined via the Spacetime Mutual Information between two regions of a causal diamond truncated by a causal horizon, and find it does limit to the area of the intersection.
description: 26 pages, 9 figures. Updated to v2 to match the accepted manuscript
title: Evaluation of Raised Pavement Markers in Kentucky:
title: Statewide Installations;
titleType: Subtitle
title: 1975-1979
titleType: Subtitle
Creators: name: Pigman, Jerry G.
name: Agent, Kenneth R.
name: Rizenbergs, Rolands L.
Publisher: name: Kentucky Transportation Center, University of Kentucky
Year: 1981
Subjects: subject: Transportation Engineering

description: Raised markers have become commonplace in delineation on highways in states where snowfall is minimal and snowplows are not needed. They have proven to be especially effective for wet, nighttime, and other poor visibility conditions when paint stripes are least effective. In Kentucky, over one million raised markers have been installed and damage from snowplowing has been significant during some of the more severe winters. As a result of costs associated with replacing damaged markers and requirements of the Pavement Marking Demonstration Program, an evaluation of all installations was undertaken.  Between 1975 and 1979, a total of 1,082,250 markers were installed on approximately 3,000 miles (4,827 km) of highway at a cost of $1,931,059. The average cost per marker was $1.78. A summary of replacement frequencies showed that 473,437 (62 percent) of the original markers remained in service, 264,880 (35 percent) have been replaced once, and 26,351 (3 percent) have been replaced twice. Even though the winter of1978-1979 was one of the more severe during recent years, only one-third of the markers installed on new sections of highway in 1978 were in need of replacement in 1979.  A 20-percent reduction in wet-night accidents and a 10-percent reduction in dry-night accidents could be used as an estimate of the effect of raised markers for systemwide installations. For the interstate system, this corresponded to a four-percent reduction in all accidents. If the four-percent reduction was applied to sections of highway for the first five raised marker installation contracts (700,000 markers on approximately 1,500 miles (2,400 km)), the resulting benefit-cost ratio would be 6.03.
Transcription of story about Verdena meeting Otis
Creators: name: Parker, Verdena
name: Lee-Wynant, Tyler
name: Spence, Justin
Publisher: name: California Language Archive, University of California, Berkeley
Year: 2020
Subjects: subject: hup

description: Audio file VP-201217-05: continued transcription of story about how Verdena met Otis, file VP-011011-10.
Generation and verification of 27-qubit Greenberger-Horne-Zeilinger states in a superconducting quantum computer
Creators: name: Mooney, Gary J.
name: White, Gregory A. L.
name: Hill, Charles D.
name: Hollenberg, Lloyd C. L.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Generating and detecting genuine multipartite entanglement (GME) of sizeable quantum states prepared on physical devices is an important benchmark for highlighting the progress of near-term quantum computers. A common approach to certify GME is to prepare a Greenberger-Horne-Zeilinger (GHZ) state and measure a GHZ fidelity of at least 0.5. We measure the fidelities using multiple quantum coherences of GHZ states on 11 to 27 qubits prepared on the IBM Quantum ibmq_montreal device. Combinations of quantum readout error mitigation (QREM) and parity verification error detection are applied to the states. A fidelity of $0.546 \pm 0.017$ was recorded for a 27-qubit GHZ state when QREM was used, demonstrating GME across the full device with a confidence level of 98.6%. We benchmarked the effect of parity verification on GHZ fidelity for two GHZ state preparation embeddings on the heavy-hexagon architecture. The results show that the effect of parity verification, while relatively modest, led to a detectable improvement of GHZ fidelity.
description: 16 pages, 7 figures. V3 includes a revised analysis of the data in Figures 5 and 6
Nonlinear dynamics of a shear banding interface
Creators: name: Fielding, Suzanne M.
name: Olmsted, Peter D.
Publisher: name: arXiv
Year: 2005
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We study numerically the nonlinear dynamics of a shear banding interface in two dimensional planar shear flow, within the non-local Johnson Segalman model. Consistent with a recent linear stability analysis, we find that an initially flat interface is unstable with respect to small undulations for sufficiently small ratio of the interfacial width $\ell$ to cell length $L_x$. The instability saturates in finite amplitude interfacial fluctuations. For decreasing $\ell/L_x$ these undergo a non equilibrium transition from simple travelling interfacial waves with constant average wall stress, to periodically rippling waves with a periodic stress response. When multiple shear bands are present we find erratic interfacial dynamics and a stress response suggesting low dimensional chaos.
description: 4 pages, 6 figures
Singularities of thermal correlators at strong coupling
Creators: name: Dodelson, Matthew
name: Ooguri, Hirosi
Publisher: name: arXiv
Year: 2020
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We analyze the singularities of the two-point function in a conformal field theory at finite temperature. In a free theory, the only singularity is along the boundary light cone. In the holographic limit, a new class of singularities emerges since two boundary points can be connected by a nontrivial null geodesic in the bulk, encircling the photon sphere of the black hole. We show that these new singularities are resolved by tidal effects due to the black hole curvature, by solving the string worldsheet theory in the Penrose limit. Singularities in the asymptotically flat black hole geometry are also discussed.
description: 26 pages; minor corrections, references added