cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Explicit derivation of the chiral and (generic) helical edge states for the Kane-Mele model: Closed expressions for the wave function, dispersion relation, and spin rotation
Creators: name: Rahmati, Fatemeh
name: Amini, Mohsen
name: Soltani, Morteza
name: Sadeghizadeh, Mozhgan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: While one of the most important and intriguing features of the topological insulators is the presence of edge states, the closed-form expressions for the edge states of some famous topological models are still lacking. Here, we focus on the Kane-Mele model with and without Rashba spin-orbit coupling as a well-known model to describe a two-dimensional version of the $\mathbb{Z}_2$ topological insulator to study the properties of its edge states analytically. By considering the tight-binding model on a honeycomb lattice with zigzag boundaries and introducing a perturbative approach, we derive explicit expressions for the wave functions, energy dispersion relations, and the spin rotations of the (generic) helical edge states. To this end, we first map the edge states of the ribbon geometry into an effective two-leg ladder model with momentum-dependent energy parameters. Then, we split the Hamiltonian of the system into an unperturbed part and a perturbation. The unperturbed part has a flat-band energy spectrum and can be solved exactly which allows us to consider the remaining part of the Hamiltonian perturbatively. The resulting energy dispersion relation within the first-order perturbation, surprisingly, is in excellent agreement with the numerical spectra over a very wide range of wavenumbers. Our perturbative framework also allows deriving an explicit form for the rotation of the spins of the momentum edge states in the absence of axial spin symmetry due to the Rashba spin-orbit interaction.
Quantum spin transistor with a Heisenberg spin chain
Creators: name: Marchukov, O. V.
name: Volosniev, A. G.
name: Valiente, M.
name: Petrosyan, D.
name: Zinner, N. T.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We propose and analyze a scheme for conditional state transfer in a Heisenberg $XXZ$ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also present a possible realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions.
description: 36 pages, 3 figures, including supplements. See journal reference below for refereed and revised version
Optimal Elastostatic Cloaks
Creators: name: Sozio, Fabio
name: Shojaei, Mostafa Faghih
name: Yavari, Arash
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computational Engineering, Finance, and Science (cs.CE)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Numerical Analysis (math.NA)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: An elastic cloak hides a hole or an inhomogeneity from elastic fields. In this paper, a formulation of the optimal design of elastic cloaks based on the adjoint state method, in which the balance of linear momentum is enforced as a constraint, is presented. The design parameters are the elastic moduli of the cloak, while the objective function is a measure of the distance between the solutions in the physical and in the virtual bodies. Both the elastic medium and the cloak are assumed to be made of isotropic linear elastic materials. In order to guarantee smooth inhomogeneous elastic moduli within the cloak a penalization term is added to the objective function. Mixed finite elements are used for discretizing the weak formulation of the optimization problem. Several numerical examples of optimal elastic cloaks designed for both single and multiple loads are presented. We consider different geometries and loading types and observe that in some cases the optimal elastic cloaks for cloaking holes (cavities) are made of auxetic materials.
description: 28 pages, 12 figures
title: Thesaurus psychiatrie et santé mentale
title: Psychiatry and mental health vocabulary
Creators: name: Institut De L’information Scientifique Et Technique (Inist)-CNRS/UAR76
name: Ascodocpsy-Réseau Documentaire En Santé Mentale
Publisher: name: Institut de l’information scientifique et technique (Inist) - CNRS/UAR76
Year: 2022
Subjects: subject: Sciences de la santé
subject: Psychiatrie
subject: Health Sciences
subject: Psychiatry

description: Thesaurus en psychiatrie et en santé mentale. Ce thesaurus francophone est orienté selon la classification internationale des maladies (CIM). Depuis sa première publication, ce thesaurus est utilisé par le réseau Ascodocpsy pour indexer les documents qui viennent alimenter la base documentaire SantéPsy. Le thesaurus SantéPsy couvre les sept champs suivants : psychiatrie, psychologie, psychanalyse, soins infirmiers, gestion administrative et hospitalière, droit de la santé et addiction. La version présentée ici est issue d'une transformation en SKOS du thésaurus.
Role of predator-prey reversal in Rock-Paper-Scissors models
Creators: name: Avelino, P. P.
name: de Oliveira, B. F.
name: Trintin, R. S.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Physics and Society (physics.soc-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: In this letter we consider a single parameter generalization of the standard three species Rock-Paper-Scissors (RPS) model allowing for predator-prey reversal. This model, which shall be referred to as $κ$RPS model, incorporates bidirectional predator-prey interactions between all the species in addition to the unidirectional predator-prey interactions of the standard RPS model. We study the dynamics of a May-Leonard formulation of the $κ$RPS model using lattice based spatial stochastic simulations with random initial conditions. We find that if the simulation lattices are sufficiently large for the coexistence of all three species to be maintained, the model asymptotically leads to the formation of spiral patterns whose evolution is qualitatively similar to that of the standard RPS model, albeit with larger characteristic length and time scales. We show that there are in general two distinct scaling regimes: one transient curvature dominated regime in which the characteristic length of the population network grows with time and another where it becomes a constant. We also estimate the dependence of the asymptotic value of the characteristic length of the population network on the likelihood of predator-prey reversal and show that if the simulation lattices are not sufficiently large then predator-prey reversal can have a significant negative impact on coexistence. Finally, we interpret these results by considering the much simpler dynamics of circular domains.
description: 6 pages, 8 figures
Dissipation of the excess energy of the adsorbate- thermalization via electron transfer
Creators: name: Strak, Paweł
name: Sakowski, Konrad
name: Krukowski, Stanisław
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: A new scenario of thermalization process of the adsorbate attached at solid surfaces is proposed. The scenario is based on existence of electric dipole layer in which the electron wavefunctions extend over the positive ions. Thus the strong local electric field exists which drags electron into the solids and repels the positive ions. The electrons are tunneling conveying the energy into the solid interior. The positive ions are retarded in the field, which allows them to loose excess kinetic energy and to be located smoothly into the adsorption sites. In this way the excess energy is not dissipated locally avoiding melting or creation of defects, in accordance with the experiments. The scenario is supported by the ab intio calculation results including density function theory of the slabs representing AlN surface and the Schrodinger equation for time evolution of hydrogen-like atom at the solid surface.
description: 13 pages, 5figures
Analytical and numerical relaxation results for models in soil mechanics
Creators: name: Behr, Florian
name: Dolzmann, Georg
name: Hackl, Klaus
name: Jezdan, Ghina
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 74-10

description: A variational model of pressure-dependent plasticity employing a time-incremental setting is introduced. A novel formulation of the dissipation potential allows one to construct the condensed energy in a variationally consistent manner. For a one-dimensional model problem, an explicit expression for the quasiconvex envelope can be found which turns out to be essentially independent of the original pressure-dependent yield surface. The model problem can be extended to higher dimensions in an empirical manner. Numerical simulation exhibit well-posed behavior showing mesh-independent results.
description: Submitted to Cont. Mech. Thermodyn
Large-Time Behavior of a Rigid Body of Arbitrary Shape in a Viscous Fluid Under the Action of Prescribed Forces and Torques
Creators: name: Galdi, Giovanni P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: Let $\mathcal B$ be a sufficiently smooth rigid body (compact set of $\mathbb R^3$) of arbitrary shape moving in an unbounded Navier-Stokes liquid under the action of prescribed external force, $\textup{F}$, and torque, $\textup{M}$. We show that if the data are suitably regular and small, and $\textup{F}$ and $\textup{M}$ vanish for large times in the $L^2$-sense, there exists at least one global strong solution to the corresponding initial-boundary value problem. Moreover, this solution converges to zero as time approaches infinity. This type of results was known, so far, only when $\mathcal B$ is a ball.
Improved Separability Criteria Based on Bloch Representation of Density Matrices
Creators: name: Shen, Shu-Qian
name: Yu, Juan
name: Li, Ming
name: Fei, Shao-Ming
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The correlation matrices or tensors in the Bloch representation of density matrices are encoded with entanglement properties. In this paper, based on the Bloch representation of density matrices, we give some new separability criteria for bipartite and multipartite quantum states. Theoretical analysis and some examples show that the proposed criteria can be more efficient than the previous related criteria.
The relationship between cluster environment and molecular gas content of star-forming galaxies in the EAGLE simulation
Creators: name: Manuwal, Aditya
name: Stevens, Adam R. H.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We employ the EAGLE hydrodynamical simulation to uncover the relationship between cluster environment and $\rm H_2$ content of star-forming galaxies at redshifts spanning $0\leq z\leq 1$. To do so, we divide the star-forming sample into those that are bound to clusters and those that are not. We find that, at any given redshift, the galaxies in clusters generally have less $\rm H_2$ than their non-cluster counterparts with the same stellar mass (corresponding to an offset of $\lesssim 0.5$ dex), but this offset varies with stellar mass and is virtually absent at $M_\star\lesssim10^{9.3}~{\rm M}_\odot$. The $\rm H_2$ deficit in star-forming cluster galaxies can be traced back to a decline in their $\rm H_2$ content that commenced after first infall into a cluster, which occurred later than a typical cluster galaxy. Evolution of the full cluster population after infall is generally consistent with `slow-then-rapid' quenching, but galaxies with $M_\star\lesssim 10^{9.5}~{\rm M}_\odot$ exhibit rapid quenching. Unlike most cluster galaxies, star-forming ones were not pre-processed in groups prior to being accreted by clusters. For both of these cluster samples, the star formation efficiency remained oblivious to the infall. We track the particles associated with star-forming cluster galaxies and attribute the drop in $\rm H_2$ mass after infall to poor replenishment, depletion due to star formation, and stripping of $\rm H_2$ in cluster environments. These results provide predictions for future surveys, along with support and theoretical insights for existing molecular gas observations that suggest there is less $\rm H_2$ in cluster galaxies.
description: Accepted for publication in MNRAS
On natural invariants and equivalence of differential operators
Creators: name: Lychagin, Valentin
name: Yumaguzhin, Valeriy
Publisher: name: arXiv
Year: 2022
Subjects: subject: Differential Geometry (math.DG)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We give a description of the field of rational natural differential invariants for a class of nonlinear differential operators of order $k\ge 2$ on a smooth manifold of dimension $n\ge 2$ and show their application to the equivalence problem of such operators.
MPEC 2024-B158 : 2024 BK3
Creators: name: Minor Planet Center Staff
Publisher: name: The Minor Planet Center
Year: 2024
Subjects: subject: Small Solar System bodies
valueUri: http://astrothesaurus.org/uat/1469
subject: 2024 BK3

description: The Minor Planet Electronic Circulars contain information on unusual minor planets, routine data on comets and natural satellites, and occasional editorial announcements.  They are published on behalf of Division F of the International Astronomical Union by the Minor Planet Center, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Single-Tap Precoders and Decoders for Multi-User MIMO FBMC-OQAM under Strong Channel Frequency Selectivity
Creators: name: Rottenberg, François
name: Mestre, Xavier
name: Horlin, François
name: Louveaux, Jérôme
Publisher: name: arXiv
Year: 2016
Subjects: subject: Information Theory (cs.IT)
subject: FOS: Computer and information sciences

description: The design of linear precoders or decoders for multiuser (MU) multiple-input multiple-output (MIMO) filterbank multicarrier (FBMC) modulations in the case of strong channel frequency selectivity is presented. The users and the base station (BS) communicate using space division multiple access (SDMA). The low complexity proposed solution is based on a single tap per-subcarrier precoding/decoding matrix at the base station (BS) in the downlink/uplink. As opposed to classical approaches that assume flat channel frequency selectivity at the subcarrier level, the BS does not make this assumption and takes into account the distortion caused by channel frequency selectivity. The expression of the FBMC asymptotic mean squared error (MSE) in the case of strong channel selectivity derived in earlier works is developed and extended. The linear precoders and decoders are found by optimizing the MSE formula under two design criteria, namely zero forcing (ZF) or minimum mean squared error (MMSE). Finally, simulation results demonstrate the performance of the optimized design. As long as the number of BS antennas is larger than the number of users, it is shown that those extra degrees of freedom can be used to compensate for the channel frequency selectivity.
Impact of Sb degrees of freedom on the charge density wave phase diagram of the kagome metal CsV$_3$Sb$_5$
Creators: name: Ritz, Ethan T.
name: Fernandes, Rafael M.
name: Birol, Turan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Elucidating the microscopic mechanisms responsible for the charge density wave (CDW) instability of the AV$_3$Sb$_5$ (A=Cs, K, Rb) family of kagome metals is critical for understanding their unique properties, including superconductivity. In these compounds, distinct CDW phases with wave-vectors at the $M$ and $L$ points are energetically favorable, opening the possibility of tuning the type of CDW order by appropriate external parameters. Here, we shed light on the CDW landscape of CsV$_3$Sb$_5$ via a combination of first-principles calculations and phenomenology, which consists of extracting the coefficients of the CDW Landau free-energy expansion from density functional theory. We find that while the main structural distortions of the kagome lattice in the staggered tri-hexagonal CDW phase are along the nearest-neighbor V-V bonds, distortions associated with the Sb ions play a defining role in the energy gain in this and all other CDW states. Moreover, the coupling between ionic displacements from different unit cells is small, thus explaining the existence of multiple CDW instabilities with different modulations along the c-axis. We also investigate how pressure and temperature impact the CDW phase of CsV$_3$Sb$_5$. Increasing pressure does not change the staggered tri-hexagonal CDW ground state, even though the $M$-point CDW instability disappears before the $L$-point one, a behavior that we attribute to the large nonlinear coupling between the order parameters. Upon changing the temperature, we find a narrow regime in which another transition can take place, toward a tri-hexagonal Star-of-David CDW phase. We discuss the implications of our results by comparing them with experiments on this compound.
Magnetorotational dynamo chimeras. The missing link to turbulent accretion disk dynamo models?
Creators: name: Riols, A.
name: Rincon, F.
name: Cossu, C.
name: Lesur, G.
name: Ogilvie, G. I.
name: Longaretti, P-Y.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: In Keplerian accretion disks, turbulence and magnetic fields may be jointly excited through a subcritical dynamo process involving the magnetorotational instability (MRI). High-resolution simulations exhibit a tendency towards statistical self-organization of MRI dynamo turbulence into large-scale cyclic dynamics. Understanding the physical origin of these structures, and whether they can be sustained and transport angular momentum efficiently in astrophysical conditions, represents a significant theoretical challenge. The discovery of simple periodic nonlinear MRI dynamo solutions has recently proven useful in this respect, and has notably served to highlight the role of turbulent magnetic diffusion in the seeming decay of the dynamics at low magnetic Prandtl number Pm (magnetic diffusivity larger than viscosity), a common regime in accretion disks. The connection between these simple structures and the statistical organization reported in turbulent simulations remained elusive, though. Here, we report the numerical discovery in moderate aspect ratio Keplerian shearing boxes of new periodic, incompressible, three-dimensional nonlinear MRI dynamo solutions with a larger dynamical complexity reminiscent of such simulations. These "chimera" cycles are characterized by multiple MRI-unstable dynamical stages, but their basic physical principles of self-sustainment are nevertheless identical to those of simpler cycles found in azimuthally elongated boxes. In particular, we find that they are not sustained at low Pm either due to subcritical turbulent magnetic diffusion. These solutions offer a new perspective into the transition from laminar to turbulent instability-driven dynamos, and may prove useful to devise improved statistical models of turbulent accretion disk dynamos.
description: 12 pages, 8 figures, submitted to A&A
The connection between supernova remnants and the Galactic magnetic field: An analysis of quasi-parallel and quasi-perpendicular cosmic ray acceleration for the axisymmetric sample
Creators: name: West, J. L.
name: Safi-Harb, S.
name: Ferrand, G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The mechanism for acceleration of cosmic rays in supernova remnants (SNRs) is an outstanding question in the field. We model a sample of 32 axisymmetric SNRs using the quasi-perpendicular and quasi-parallel cosmic-ray-electron (CRE) acceleration cases. The axisymmetric sample is defined to include SNRs with a double-sided, bilateral morphology, and also those with a one-sided morphology where one limb is much brighter than the other. Using a coordinate transformation technique, we insert a bubble-like model SNR into a model of the Galactic magnetic field. Since radio emission of SNRs is dominated by synchrotron emission and since this emission depends on the magnetic field and CRE distribution, we are able to simulate the SNRs emission and compare this to data. We find that the quasi-perpendicular CRE acceleration case is much more consistent with the data than the quasi-parallel CRE acceleration case, with G327.6+14.6 (SN1006) being a notable exception. We propose that SN1006 may be a case where both quasi-parallel and quasi-perpendicular acceleration are simultaneously at play in a single SNR.
description: 22 pages, 6 figures
A CsI hodoscope on CSHINE for Bremsstrahlung γ-rays in Heavy Ion Reactions
Creators: name: Qin, Yuhao
name: Guo, Dong
name: Xiao, Sheng
name: Wang, Yijie
name: Guan, Fenhai
name: Diao, Xinyue
name: Qin, Zhi
name: Si, Dawei
name: Zhang, Boyuan
name: Zhang, Yaopeng
name: Wei, Xianglun
name: Yang, Herun
name: Ma, Peng
name: Zou, Haichuan
name: Qiu, Tianli
name: Huang, Xinjie
name: Hu, Rongjiang
name: Duan, Limin
name: Duan, Fangfang
name: Hu, Qiang
name: Ma, Junbing
name: Xu, Shiwei
name: Bai, Zhen
name: Yang, Yanyun
name: Xiao, Zhigang
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Bremsstrahlung $γ$ production in heavy ion reactions at Fermi energies carries important physical information including the nuclear symmetry energy at supra-saturation densities. In order to detect the high energy Bremsstrahlung $γ$ rays, a hodoscope consisting of 15 CsI(Tl) crystal read out by photo multiplier tubes has been built, tested and operated in experiment. The resolution, efficiency and linear response of the units to $γ$ rays have been studied using radioactive source and $({\rm p},γ)$ reactions. The inherent energy resolution of $1.6\%+2\%/E_γ^{1/2}$ is obtained. Reconstruction method has been established through Geant 4 simulations, reproducing the experimental results where comparison can be made. Using the reconstruction method developed, the whole efficiency of the hodoscope is about $2.6\times 10^{-4}$ against the $4π$ emissions at the target position, exhibiting insignificant dependence on the energy of incident $γ$ rays above 20 MeV. The hodoscope is operated in the experiment of $^{86}$Kr + $^{124}$Sn at 25 MeV/u, and a full $γ$ energy spectrum up to 80 MeV has been obtained.
description: 9 pages, 19 figures
Holographic thermal propagator for arbitrary scale dimensions
Creators: name: Bajc, Borut
name: Lugo, Adrian R.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Using the AdS/CFT correspondence we model the behaviour of the two point correlator of an operator with arbitrary scale dimension $Δ$ in arbitrary spacetime dimension $d$ for small but non-zero temperature. The obtained propagator coincides in the low temperature regime with the known result for $d=4$ for large $Δ$ at the order $T^d$ as well as with the $T^d$ and $T^{2d}$ terms of the exact all order result for $d=2$. Furthermore, for arbitrary $d$ we explicitly write down the expression for the order $T^{d}$ of the propagator for arbitrary $Δ$, and present a conjecture for the order $T^{2d}$ in the large $Δ$ limit.
description: 23 pages, 4 figures, one important reference added, more comparison with known results, few typos corrected
GMRT 610-MHz observations of the faint radio source population - and what these tell us about the higher-radio-frequency sky
Creators: name: Whittam, I. H.
name: Green, D. A.
name: Jarvis, M. J.
name: Riley, J. M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present 610-MHz Giant Metrewave Radio Telescope observations of 0.84 deg$^2$ of the AMI001 field (centred on $00^{\rm h} 23^{\rm m} 10^{\rm s}$, $+31^{\circ} 53'$) with an r.m.s. noise of 18 $μ$Jy beam$^{-1}$ in the centre of the field. 955 sources are detected, and 814 are included in the source count analysis. The source counts from these observations are consistent with previous work. We have used these data to study the spectral index distribution of a sample of sources selected at 15.7 GHz from the recent deep extension to the Tenth Cambridge (10C) survey. The median spectral index, $α$, (where $S \propto ν^{-α}$) between $0.08 < S_{15.7~\rm GHz} / \rm mJy < 0.2$ is $0.32 \pm 0.14$, showing that star-forming galaxies, which have much steeper spectra, are not contributing significantly to this population. This is in contrast to several models, but in agreement with the results from the 10C ultra-deep source counts; the high-frequency sky therefore continues to be dominated by radio galaxies down to $S_{15.7~\rm GHz} = 0.1$ mJy.
description: 12 pages, 14 figures, accepted for publication in MNRAS
title: Vocabulaire de géographie de l'Amérique du Nord
title: Geography of North America vocabulary
Creators: name: Institut De L’information Scientifique Et Technique (Inist)-CNRS/UAR76
Publisher: name: Institut de l’information scientifique et technique (Inist) - CNRS/UAR76
Year: 2020
Subjects: subject: Sciences humaines et sociales
subject: Géographie
subject: Humanities and social sciences
subject: Geography

description: Vocabulaire contrôlé de "géographie de l’Amérique du Nord" utilisé pour l'indexation des références bibliographiques de la base de données PASCAL (1972 à 2015, http://pascal-francis.inist.fr/). Cette ressource a été alignée avec la base de données géographiques GeoNames.
Bootstrapping Multi-Field Inflation: non-Gaussianities from light scalars revisited
Creators: name: Wang, Dong-Gang
name: Pimentel, Guilherme L.
name: Achúcarro, Ana
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
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: Primordial non-Gaussianities from multi-field inflation are a leading target for cosmological observations, because of the possible large correlations generated between long and short distances. These signatures are captured by the local shape of the scalar bispectrum. In this paper, we revisit the nonlinearities of the conversion process from additional light scalars into curvature perturbations during inflation. We provide analytic templates for correlation functions valid at any kinematical configuration, using the cosmological bootstrap as a main computational tool. Our results include the possibility of large breaking of boost symmetry, in the form of small speeds of sound for both the inflaton and the mediators. We consider correlators coming from the tree-level exchange of a massless scalar field. By introducing a late-time cutoff, we identify that the symmetry constraints on the correlators are modified. This leads to anomalous conformal Ward identities, and consequently the bootstrap differential equations acquire a source term that depends on this cutoff. The solutions to the differential equations are scalar seed functions that incorporate these late-time growth effects. Applying weight-shifting operators to auxiliary "seed" functions, we obtain a systematic classification of shapes of non-Gaussianity coming from massless exchange. For theories with de Sitter symmetry, we compare the resulting shapes with the ones obtained via the $δN$ formalism, identifying missing contributions away from the squeezed limit. For boost-breaking scenarios, we derive a novel class of shape functions with phenomenologically distinct features. Specifically, the new shape provides a simple extension of equilateral non-Gaussianity: the signal peaks at a geometric configuration controlled by the ratio of the sound speeds of the mediator and the inflaton.
description: 65 pages, 8 figures
Vacuum polarization and classical self-action near higher-dimensional defects
Creators: name: Grats, Yuri V.
name: Spirin, Pavel
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We analyze the gravity-induced effects associated with a massless scalar field in a higher-dimensional spacetime being the tensor product of $(d-n)$-dimensional Minkowski space and $n$-dimensional spherically/cylindrically-symmetric space with a solid/planar angle deficit. These spacetimes are considered as simple models for a multidimensional global monopole (if \mbox{$n\geqslant 3$}) or cosmic string (if $n=2$) with $(d-n-1)$ flat extra dimensions. Thus, we refer to them as conical backgrounds. In terms of the angular deficit value, we derive the perturbative expression for the scalar Green's function, valid for any $d\geqslant 3$ and $2\leqslant n\leqslant d-1$, and compute it to the leading order. With the use of this Green's function we compute the renormalized vacuum expectation value of the field square $\langle ϕ^{2}(x)\rangle_{\mathrm{ren}}$ and the renormalized vacuum averaged of the scalar-field's energy-momentum tensor $\langle T_{M N}(x)\rangle_{\mathrm{ren}}$ for arbitrary $d$ and $n$ from the interval mentioned above and arbitrary coupling constant to the curvature $ξ$. In particular, we revisit the computation of the vacuum polarization effects for a non-minimally coupled massless scalar field in the spacetime of a straight cosmic string. The same Green's function enables to consider the old purely classical problem of the gravity-induced self-action of a classical pointlike scalar or electric charge, placed at rest at some fixed point of the space under consideration. To deal with divergences, which appear in consideration of the both problems, we apply the dimensional-regularization technique, widely used in quantum field theory (QFT). The explicit dependence of the results upon the dimensionalities of both the bulk and conical submanifold, is discussed.
description: 25 pages
The Effects of Mergers and Acquisitions on Bank Risks
Creators: name: Ngo, Huyen
Publisher: name: University of Westminster
Year: 2019

description: This thesis examines the effects of bank mergers on acquiring banks' default risk and on their contributions to systemic risk using an international merger sample, covering the period between 1998 and 2015. Furthermore, it investigates whether the changes in acquirers’ default risk after acquisitions have impacts on banking firms’ stockholders (idiosyncratic risk); or whether they spread to other banks (systemic risk) and all listed firms (systematic risk). Also, this thesis extends the established literature by providing original evidence on the determinants of these merger-related changes in acquiring banks' default risk, systemic risk, systematic risk and idiosyncratic risk of shareholders. An ongoing debate in the literature is whether or not bank mergers help to lower bidders’ default risk. Using Distance to Default methodology from Vallascas and Hagendorff (2011), this thesis brings robust evidence that bank mergers reduce the default risk of bidders. The results also show that not all forms of diversification exert an equal effect on the reduction of bidders' default risk. Product diversification is found to reduce bidding banks' default risk meanwhile geographic diversification does not have a statistically significant relationship to the reduction in default risk of acquiring banks. Additionally, this thesis extends the debate regarding the effects of bank mergers on bidders’ contribution to systemic risk. Employing Marginal Expected Shortfall from Acharya et al., (2017) and ΔCoVaR from Adrian and Brunnermeier (2016), the findings suggest that bank mergers, on average, do not impact on acquiring banks’ contribution to systemic risk. However, product-diversifying deals lead to a reduction in acquirers’ contribution to systemic risk for non-US acquirers only. It also transpires that with deals financed by cash only, the acquirers’ contribution to systemic risk increases. Finally, this thesis investigates the impact of the changes in default risk on changes in systematic risk, idiosyncratic risk and systemic risk following mergers, using the empirical framework as in Fiordelisi and Marqués-Ibañez (2013). The results from this thesis suggest that, during a pre-merger period (without M&As), the risk of default on any individual bank does not only affect this bank’s stockholders, but also extends to other banks in the banking system, causing the banking industry to become fragile and volatile. Furthermore, when the effects of bank mergers are taken into consideration, the changes in acquirers’ default risk have direct positive impacts on the changes in their’ own idiosyncratic risk. It is significant to note that bank mergers are proven to reduce the default risk of acquiring banks earlier in this study. Therefore, it is concluded that the reduction in acquirers’ default risk following a merger, also results in the reduction of their idiosyncratic risk, which means that M&As lead to safer banks in general.
Dissipation-based WENO stabilization of high-order finite element methods for scalar conservation laws
Creators: name: Kuzmin, Dmitri
name: Vedral, Joshua
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: We present a new perspective on the use of weighted essentially nonoscillatory (WENO) reconstructions in high-order methods for scalar hyperbolic conservation laws. The main focus of this work is on nonlinear stabilization of continuous Galerkin (CG) approximations. The proposed methodology also provides an interesting alternative to WENO-based limiters for discontinuous Galerkin (DG) methods. Unlike Runge--Kutta DG schemes that overwrite finite element solutions with WENO reconstructions, our approach uses a reconstruction-based smoothness sensor to blend the numerical viscosity operators of high- and low-order stabilization terms. The so-defined WENO approximation introduces low-order nonlinear diffusion in the vicinity of shocks, while preserving the high-order accuracy of a linearly stable baseline discretization in regions where the exact solution is sufficiently smooth. The underlying reconstruction procedure performs Hermite interpolation on stencils consisting of a mesh cell and its neighbors. The amount of numerical dissipation depends on the relative differences between partial derivatives of reconstructed candidate polynomials and those of the underlying finite element approximation. All derivatives are taken into account by the employed smoothness sensor. To assess the accuracy of our CG-WENO scheme, we derive error estimates and perform numerical experiments. In particular, we prove that the consistency error of the nonlinear stabilization is of the order $p+1/2$, where $p$ is the polynomial degree. This estimate is optimal for general meshes. For uniform meshes and smooth exact solutions, the experimentally observed rate of convergence is as high as $p+1$.
Localization in musical steelpans
Creators: name: Bryde, Petur
name: Mahadevan, L.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The steelpan is a pitched percussion instrument that takes the form of a concave bowl with several localized dimpled regions of varying curvature. Each of these localized zones, called notes, can vibrate independently when struck, and produces a sustained tone of a well-defined pitch. While the association of the localized zones with individual notes has long been known and exploited, the relationship between the shell geometry and the strength of the mode confinement remains unclear. Here, we explore the spectral properties of the steelpan modeled as a vibrating elastic shell. To characterize the resulting eigenvalue problem, we generalize a recently developed theory of localization landscapes for scalar elliptic operators to the vector-valued case, and predict the location of confined eigenmodes by solving a Poisson problem. A finite element discretization of the shell shows that the localization strength is determined by the difference in curvature between the note and the surrounding bowl. In addition to providing an explanation for how a steelpan operates as a two-dimensional xylophone, our study provides a geometric principle for designing localized modes in elastic shells.
description: 17 pages, 5 figures
$W$-Boson Mass Anomaly from a General $SU(2)_{L}$ Scalar Multiplet
Creators: name: Wu, Jiajun
name: Huang, Da
name: Geng, Chao-Qiang
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We explain the $W$-boson mass anomaly by introducing an $SU(2)_L$ scalar multiplet with general isospin and hypercharge in the case without its vacuum expectation value. It is shown that the dominant contribution from the scalar multiplet to the $W$-boson mass arises at one-loop level, which can be expressed in terms of the electroweak (EW) oblique parameters $T$ and $S$ at leading order. We firstly rederive the general formulae of $T$ and $S$ induced by a scalar multiplet of EW charges, confirming the results in the literature. We then study several specific examples of great phenomenological interest by applying these general expressions. As a result, it is found that the model with a scalar multiplet in an $SU(2)_L$ real representation with $Y=0$ cannot generate the required $M_W$ correction since it leads to vanishing values of $T$ and $S$. On the other hand, the cases with scalars in a complex representation under $SU(2)_L$ with a general hypercharge can explain the $M_W$ excess observed by CDF-\uppercase\expandafter{\romannumeral2} due to nonzero $T$ and $S$. We further take into account of the strong constraints from the perturbativity and the EW global fit of the precision data, and vary the isospin representation and hypercharge of the additional scalar multiplet, in order to assess the extent of the model to solve the $W$-boson mass anomaly. It turns out that these constraints play important roles in setting limits on the model parameter space. We also briefly describe the collider signatures of the extra scalar multiplet, especially when it contains long-lived heavy highly charged states.
description: 36 pages, 13 figures. Minor modifications, references updated;
Interference effects in polarization controlled Rayleigh scattering in twisted bilayer graphene
Creators: name: Arora, Disha
name: Aggarwal, Deepanshu
name: Ghosh, Sankalpa
name: Narula, Rohit
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We calculate the \tco{polarization}-controlled Rayleigh scattering response of twisted bilayer graphene (tBLG) based on the continuum electronic band model developed by Bistritzer and MacDonald while considering its refinements which address the effects of structural corrugation, doping-dependent Hartree interactions and particle-hole asymmetry. The dominant wave vectors for the Rayleigh scattering process emanate from various regions of the Moiré Brillouin zone (MBZ) in contrast to single-layer graphene (SLG) and AB-stacked bilayer graphene (AB-BLG), where the dominant contributions always stem from the vicinity of the $\bm{K}$ point for optical laser energies and below. Compared to SLG, the integrated Rayleigh intensity is strongly enhanced for small twist angles (\emph{e.g.}, at a twist angle $ θ= 1.2^{\circ} $, the integrated Rayleigh intensity at laser energy $ E_l=2~\si{\electronvolt} $ enhances by a factor of $\sim $ 100 for the case of parallel \tco{polarization}). While for the case of cross-\tco{polarization}, it exhibits a markedly complex \tco{behavior} suggestive of strong interference effects mediated by the optical matrix elements. We find that at small twist angles, \emph{e.g.}, $ θ= 1.05^{\circ} $, the corrugation effects strongly enhances the ratio $ \bm{R}_A = \frac{ \text{integrated Rayleigh intensity for parallel \tco{polarization}}}{\text{integrated Rayleigh intensity for cross-\tco{polarization}}} $ by $ \sim $ $ 1300 $ times \emph{viz a viz} SLG or AB-BLG.
description: 18 latex pages with 21 figures (figures contain subfigures). The actual manuscript abstract is more extended than the one displayed. Accepted for publication in Physical Review B
InAs nanowire superconducting tunnel junctions: spectroscopy, thermometry and nanorefrigeration
Creators: name: Mastomäki, Jaakko
name: Roddaro, Stefano
name: Rocci, Mirko
name: Zannier, Valentina
name: Ercolani, Daniele
name: Sorba, Lucia
name: Maasilta, Ilari J.
name: Ligato, Nadia
name: Fornieri, Antonio
name: Strambini, Elia
name: Giazotto, Francesco
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We demonstrate an original method -- based on controlled oxidation -- to create high-quality tunnel junctions between superconducting Al reservoirs and InAs semiconductor nanowires. We show clean tunnel characteristics with a current suppression by over $4$ orders of magnitude for a junction bias well below the Al gap $Δ_0 \approx 200\,μ{\rm eV}$. The experimental data are in close agreement with the BCS theoretical expectations of a superconducting tunnel junction. The studied devices combine small-scale tunnel contacts working as thermometers as well as larger electrodes that provide a proof-of-principle active {\em cooling} of the electron distribution in the nanowire. A peak refrigeration of about $δT = 10\,{\rm mK}$ is achieved at a bath temperature $T_{bath}\approx250-350\,{\rm mK}$ in our prototype devices. This method opens important perspectives for the investigation of thermoelectric effects in semiconductor nanostructures and for nanoscale refrigeration.
description: 6 pages, 4 color figures
Sensible Signs: Pictures and Not Painting After Conceptual Art
Creators: name: Cumberland, Stuart
Publisher: name: University of Westminster
Year: 2019

description: This PhD by published work contributes to debates regarding aesthetics versus art history and theory. It provides a contextual review of anti-aesthetic legacies of pop and conceptual art developing from an understanding of modern art as de-humanized. The research is concerned with why, how and what to paint after conceptual art and proceeds by making a distinction between postconceptual painting and a return to painting. These themes are tested in the first of two of the author’s solo exhibitions titled ‘Four Circle Paintings’. The show consisted of lo-fi mechanical mono-chrome copies of gestural painting and promotes a conclusion that the label postconceptual painting is applied to artworks that are representations of painting and as such are not real painting. The thesis argues that in its urgency to distinguish itself from (authentic) painting, postconceptual painting demonstrates a contradictory appeal to aesthetics, which prevents the artwork from becoming merely a sign. Therefore, at risk of the same return to painting, the postconceptual painter values sensibility with the intention that the “fake” painting––or sign––is vexed by a ‘real’ aesthetic. In an attempt to circumnavigate the requirement to validate medium, the second exhibition titled ‘Handmade Colour Pictures’ argues for a categorical shift from the making of ‘paintings’ to ‘pictures’. The show consisted of eight mid-sized works, using painting conventions––oil paint on primed linen stretched over rectangular frames––to produce images, derived from a hunting theme, that brought attention to their own pictorial conditions. The author, having outlined visual attention as a premeditated motivation, concludes that the “there” and “not there” quality of the picture that must be consciously switched between to see it as either image or object, provides an “experience of meaning” that is significant for the artwork in its distinction from an anti-aesthetic dominance of rationality.
Conjecture of perturbative QED breakdown at $αχ^{2/3} \gtrsim 1$
Creators: name: Fedotov, A. M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Invited talk given at Symposium "Extreme Light Technologies, Science, and Applications" (LPHYS'16, Yerevan, 11-15 July 2016). The old Ritus-Narozhny conjecture of possible breakdown of Intense Field QED perturbation theory for ultrarelativistic particles passing transversely through a strong electromagnetic field is reviewed with a special emphasis on its possible significance for near-future experiments.
description: Invited talk given at Symposium "Extreme Light Technologies, Science, and Applications" (LPHYS'16, Yerevan, 11-15 July 2016)
Islands in Proliferating de Sitter Spaces
Creators: name: Baek, Jong-Hyun
name: Choi, Kang-Sin
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study two-dimensional de Sitter universe which evolves and proliferates according to the Ginsparg-Perry-Bousso-Hawking mechanism, using Jackiw-Teitelboim gravity coupled to conformal matter. Black holes are generated by quantum gravity effects from pure de Sitter space and then evaporate to yield multiple disjoint de Sitter spaces. The back-reaction from the matter CFT is taken into account for the dilaton as a function of the temperature of the CFT. We discuss the evaporation of black holes and calculate the finite temperature entropy of an inflating region using the island formula. We find that the island moves towards the apparent horizon of the black hole as the temperature increases. The results are applied to the case of multiple evaporating black holes, for which we suggest multiple islands.
description: 26+1 pages, 6 figures, v2: clarified discussion, v3: published version