cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Field-induced compensation of magnetic exchange as the possible origin of reentrant superconductivity in UTe$_2$
Creators: name: Helm, Toni
name: Kimata, Motoi
name: Sudo, Kenta
name: Miyata, Atsuhiko
name: Stirnat, Julia
name: Förster, Tobias
name: Hornung, Jacob
name: König, Markus
name: Sheikin, Ilya
name: Pourret, Alexandre
name: Lapertot, Gérard
name: Aoki, Dai
name: Knebel, Georg
name: Wosnitza, Jochen
name: Brison, Jean-Pascal
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The potential spin-triplet heavy-fermion superconductor UTe$_2$ exhibits signatures of multiple distinct superconducting phases. For field aligned along the $b$ axis, a metamagnetic transition occurs at $μ_0 H_\mathrm{m}\approx35\,$T. It is associated with magnetic fluctuations that may be beneficial for the field-reinforced superconductivity surviving up to $H_\mathrm{m}$. Once the field is tilted away from the $b$ towards the $c$ axis, a reentrant superconducting phase emerges just above $H_\mathrm{m}$. In order to better understand this remarkably field-resistant superconducting phase, we conducted magnetic-torque and magnetotransport measurements in pulsed magnetic fields. We determine the record-breaking upper critical field of $μ_0 H_\mathrm{c2}\approx 73\,$T and its evolution with angle. Furthermore, the normal-state Hall effect experiences a drastic suppression indicative of a reduced band polarization above $H_\mathrm{m}$ in the angular range around $30^\circ$ caused by a partial compensation between the applied field and an exchange field. This promotes the Jaccarino-Peter effect as a likely mechanism for the reentrant superconductivity above $H_\mathrm{m}$.
description: Main text: 29 pages, 4 figure; Supplement: 12 pages, 6 figures
Quantum Corrections to Non-Abelian SUSY Theories on Orbifolds
Creators: name: Nibbelink, Stefan Groot
name: Hillenbach, Mark
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider supersymmetric non-Abelian gauge theories coupled to hyper multiplets on five and six dimensional orbifolds, S^1/Z_2 and T^2/Z_N, respectively. We compute the bulk and local fixed point renormalizations of the gauge couplings. To this end we extend supergraph techniques to these orbifolds by defining orbifold compatible delta functions. We develop their properties in detail. To cancel the bulk one-loop divergences the bulk gauge kinetic terms and dimension six higher derivative operators are required. The gauge couplings renormalize at the Z_N fixed points due to vector multiplet self interactions; the hyper multiplet renormalizes only non-Z_2 fixed points. In 6D the Wess-Zumino-Witten term and a higher derivative analogue have to renormalize in the bulk as well to preserve 6D gauge invariance.
Future state of the Universe
Creators: name: Dabrowski, Mariusz P.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Following the observational evidence for cosmic acceleration which may exclude a possibility for the universe to recollapse to a second singularity, we review alternative scenarios of its future evolution. Although the de Sitter asymptotic state is still an option, some other asymptotic states which allow new types of singularities such as Big-Rip (due to a phantom matter) and sudden future singularities are also admissible and are reviewed in detail. The reality of these singularities which comes from the relation to observational characteristics of the universe expansion are also revealed and widely discussed.
description: 12 pages, 1 figure, a contribution to Pomeranian Workshop in Fundamental Cosmology (COSMOFUN'05), Pobierowo, Poland, 1-6 September 2005
Assessing the brittle crust thickness from strike-slip fault segments on Earth, Mars and Icy Moons
Creators: name: Donze, Frederic-Victor
name: Klinger, Yann
name: Bonilla-Sierra, Viviana
name: Duriez, Jerome
name: Jiao, Liqing
name: Scholtes, Luc
Publisher: name: arXiv
Year: 2020
Subjects: subject: Geophysics (physics.geo-ph)
subject: FOS: Physical sciences

description: Segment lengths along major strike-slip faults exhibit a size dependency related to the brittle crust thickness. These segments result in the formation of the localized 'P-shear' deformation crossing and connecting the initial Riedels structures (i.e. en-echelon fault structures) which formed during the genesis stage of the fault zone. Mechanical models show that at all scales, the geometrical characteristics of the Riedels exhibit dependency on the thickness of the brittle layer. Combining the results of our mechanical discrete element model with several analogue experiments using sand, clay and gypsum, we have formulated a relationship between the orientation and spacing of Riedels and the thickness of the brittle layer. From this relationship, we derive that for a pure strike-slip mode, the maximum spacing between the Riedels are close to three times the thickness. For a transtensional mode, as the extensive component becomes predominant, the spacing distance at the surface become much smaller than the thickness. Applying this relationship to several well-characterized strike-slip faults on Earth, we show that the predicted brittle thickness is consistent with the seismogenic depth. Supposing the ubiquity of this phenomenon, we extent this relationship to characterize en-echelon structures observed on Mars, in the Memnonia region located West of Tharsis. Assuming that the outer ice shells of Ganymede, Enceladus and Europa, exhibit a brittle behavior, we suggest values of the corresponding apparent brittle thicknesses.
description: 23 pages, 14 figures, submitted to Tectonophysics Journal
Microstructure, morphology and lifetime of armored bubbles exposed to surfactants
Creators: name: Subramaniam, Anand Bala
name: Mejean, Cecile
name: Abkarian, Manouk
name: Stone, Howard A.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: We report the behavior of particle-stabilized bubbles (armored bubbles) when exposed to various classes and concentrations of surfactants. The bubbles are non-spherical due to the jamming of the particles on the interface and are stable to dissolution prior to the addition of surfactant. We find that the dissolving bubbles exhibit distinct morphological, microstructural, and lifetime changes, which correlate with the concentration of surfactant employed. For low concentrations of surfactant an armored bubble remains non-spherical while dissolving, while for concentrations close to and above the surfactant CMC a bubble reverts to a spherical shape before dissolving. We propose a microstructural interpretation, supported by our experimental observations of particle dynamics on the bubble interface, that recognizes the role of interfacial jamming and stresses in particle stabilization and surfactant-mediated destabilization of armored bubbles.
description: 8 pages, 4 figures, 1 supplementary figure
Exact solution of the geometrically frustrated spin-1/2 Ising-Heisenberg model on the triangulated Kagome (triangles-in-triangles) lattice
Creators: name: Strecka, Jozef
name: Canova, Lucia
name: Jascur, Michal
name: Hagiwara, Masayuki
Publisher: name: arXiv
Year: 2008
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: The geometric frustration of the spin-1/2 Ising-Heisenberg model on the triangulated Kagome (triangles-in-triangles) lattice is investigated within the framework of an exact analytical method based on the generalized star-triangle mapping transformation. Ground-state and finite-temperature phase diagrams are obtained along with other exact results for the partition function, Helmholtz free energy, internal energy, entropy, and specific heat, by establishing a precise mapping relationship to the corresponding spin-1/2 Ising model on the Kagome lattice. It is shown that the residual entropy of the disordered spin liquid phase is for the quantum Ising-Heisenberg model significantly lower than for its semi-classical Ising limit (S_0/N_T k_B = 0.2806 and 0.4752, respectively), which implies that quantum fluctuations partially lift a macroscopic degeneracy of the ground-state manifold in the frustrated regime. The investigated model system has an obvious relevance to a series of polymeric coordination compounds Cu_9X_2(cpa)_6 (X=F, Cl, Br and cpa=carboxypentonic acid) for which we made a theoretical prediction about the temperature dependence of zero-field specific heat.
description: 13 pages, 7 figures, submitted to Phys. Rev. B
Disentangled (Un)Controllable Features
Creators: name: Kooi, Jacob E.
name: Hoogendoorn, Mark
name: François-Lavet, Vincent
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Artificial Intelligence (cs.AI)
subject: FOS: Computer and information sciences

description: In the context of MDPs with high-dimensional states, downstream tasks are predominantly applied on a compressed, low-dimensional representation of the original input space. A variety of learning objectives have therefore been used to attain useful representations. However, these representations usually lack interpretability of the different features. We present a novel approach that is able to disentangle latent features into a controllable and an uncontrollable partition. We illustrate that the resulting partitioned representations are easily interpretable on three types of environments and show that, in a distribution of procedurally generated maze environments, it is feasible to interpretably employ a planning algorithm in the isolated controllable latent partition.
description: 14 pages (8 main paper pages), 15 figures
Friedmann Equations of FRW Universe in Scalar-tensor Gravity, f(R) Gravity and First Law of Thermodynamics
Creators: name: Akbar, M.
name: Cai, Rong-Gen
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In the paper, hep-th/0501055 (R.G. Cai and S.P. Kim, JHEP {\bf 0502}, 050 (2005)), it is shown that by applying the first law of thermodynamics to the apparent horizon of an FRW universe and assuming the geometric entropy given by a quarter of the apparent horizon area, one can derive the Friedmann equations describing the dynamics of the universe with any spatial curvature; using the entropy formula for the static spherically symmetric black holes in Gauss-Bonnet gravity and in more general Lovelock gravity, where the entropy is not proportional to the horizon area, one can also obtain the corresponding Friedmann equations in each gravity. In this note we extend the study of hep-th/0501055 to the cases of scalar-tensor gravity and $f(R)$ gravity, and discuss the implication of results.
description: Latex, 9 pages, to appear in PLB; v2: typos corrected, a reference added
The gravitational path integral for $ N=4$ BPS black holes from black hole microstate counting
Creators: name: Cardoso, Gabriel Lopes
name: Kidambi, Abhiram
name: Nampuri, Suresh
name: Reys, Valentin
name: Rosselló, Martí
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We use the exact degeneracy formula of single-centred $\frac14$ BPS dyonic black holes with unit torsion in 4D $N=4$ toroidally compactified heterotic string theory to improve on the existing formulation of the corresponding quantum entropy function obtained using supersymmetric localization. The result takes the form of a sum over Euclidean backgrounds including orbifolds of the Euclidean $AdS_2 \times S^2$ attractor geometry. Using an $N=2$ formalism, we determine the explicit form of the Abelian gauge potentials supporting these backgrounds. We further show how a rewriting of the degeneracy formula is amenable, at a semi-classical level, to a gravitational interpretation involving 2D Euclidean wormholes. This alternative picture is useful to elucidate different aspects of the gravitational path integral capturing the microstate degeneracies. We also comment on the relation between the associated 1D holographic models.
description: 32 pages, 1 figure; v2: clarifications and references added, minor typos corrected
Cosmography of f(R) gravity
Creators: name: Capozziello, S.
name: Cardone, V. F.
name: Salzano, V.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: It is nowadays accepted that the universe is undergoing a phase of accelerated expansion as tested by the Hubble diagram of Type Ia Supernovae (SNeIa) and several LSS observations. Future SNeIa surveys and other probes will make it possible to better characterize the dynamical state of the universe renewing the interest in cosmography which allows a model independent analysis of the distance - redshift relation. On the other hand, fourth order theories of gravity, also referred to as $f(R)$ gravity, have attracted a lot of interest since they could be able to explain the accelerated expansion without any dark energy. We show here how it is possible to relate the cosmographic parameters (namely the deceleration $q_0$, the jerk $j_0$, the snap $s_0$ and the lerk $l_0$ parameters) to the present day values of $f(R)$ and its derivatives $f^{(n)}(R) = d^nf/dR^n$ (with $n = 1, 2, 3$) thus offering a new tool to constrain such higher order models. Our analysis thus offers the possibility to relate the model independent results coming from cosmography to the theoretically motivated assumptions of $f(R)$ cosmology.
description: 18 pages, 4 figures
Neutrinos in a Sterile Throat
Creators: name: Gripaios, Ben
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We consider field-theoretic models of a warped extra dimension with multiple throats, in which fermions that are singlets of the Standard Model gauge group propagate in a separate throat from the Standard Model fields, which we call the sterile throat. The singlets mix with Standard Model fields via interactions localized on the UV brane that connects the two throats. This leads to three, light, mostly-active, Majorana neutrinos via a higher-dimensional see-saw mechanism, together with Kaluza-Klein towers of mostly-sterile neutrinos, whose scale is set by the warp factor in the sterile throat and can be very low if the throat is deep. We suggest that a model of this kind may explain all the neutrino data, reconciling the LSND result with astrophysical constraints.
description: 27 pages, 1 figure. Sign error corrected
Picosecond Spin-Orbit Torque Induced Coherent Magnetization Switching in a Ferromagnet
Creators: name: Polley, Debanjan
name: Pattabi, Akshay
name: Rastogi, Ashwin
name: Jhuria, Kaushalya
name: Diaz, Eva
name: Singh, Hanuman
name: Lemaitre, Aristide
name: Hehn, Michel
name: Gorchon, Jon
name: Bokor, Jeffrey
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Electrically controllable non-volatile magnetic memories show great potential for the replacement of semiconductor-based technologies. Recently there has been strong interest in spin-orbit torque (SOT) induced magnetization reversal due to the device's increased lifetime and speed of operation. However, recent SOT switching studies reveal an incubation delay in the ~ns range due to stochasticity in the nucleation of a magnetic domain during reversal. Here, we experimentally demonstrate ultrafast SOT-induced magnetization switching dynamics of a ferromagnet with no incubation delay by avoiding the nucleation process and driving the magnetization coherently. We employ an ultrafast photo-conducting switch and a co-planar strip line to generate and guide ~ps current pulses into the heavy metal/ferromagnet layer stack and induce ultrafast SOT. We use magneto-optical probing to investigate the magnetization switching dynamics with sub-picosecond time resolution. Depending on the relative current pulse and in-plane magnetic field polarities, we observe either an ultrafast demagnetization and subsequent recovery along with a SOT-induced precessional oscillation, or ultrafast SOT switching. The magnetization zero-crossing occurs in ~70 ps, which is approximately an order of magnitude faster than previous studies. Complete switching needs ~250 ps and is limited by the heat diffusion to the substrate. We use a macro-magnetic simulation coupled with an ultrafast heating model to analyze the effect of ultrafast thermal anisotropy torque and current-induced torque in the observed dynamics. Good agreement between our experimental results and the macro-spin model shows that the switching dynamics are coherent and present no noticeable incubation delay. Our work suggests a potential pathway toward dramatically increasing the writing speed of SOT magnetic random-access memory devices.
description: 17 pages, 4 figures, Supplemental Material
Magnetic cycles of the planet-hosting star tauBootis
Creators: name: Donati, J. F.
name: Moutou, C.
name: Fares, R.
name: Bohlender, D.
name: Catala, C.
name: Deleuil, M.
name: Shkolnik, E.
name: Cameron, A. C.
name: Jardine, M. M.
name: Walker, G. A. H.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: We have obtained new spectropolarimetric observations of the planet-hosting star tauBootis, using the ESPaDOnS and NARVAL spectropolarimeters at the Canada-France-Hawaii Telescope and Telescope Bernard-Lyot. With this data set, we are able to confirm the presence of a magnetic field at the surface of tauBoo and map its large-scale structure over the whole star. The overall polarity of the magnetic field has reversed with respect to our previous observation (obtained a year before), strongly suggesting that tauBoo is undergoing magnetic cycles similar to those of the Sun. This is the first time that a global magnetic polarity switch is observed in a star other than the Sun; we speculate that the magnetic cycle period of tauBoo is much shorter than that of the Sun. Our new data also allow us to confirm the presence of differential rotation from the latitudinal shearing that the magnetic structure is undergoing. The differential rotation surface shear that tauBoo experiences is found to be 6 to 10 times larger than that of the Sun. We propose that the short magnetic cycle period is due to the strong level of differential rotation. With a rotation period of 3.0 and 3.9 d at the equator and pole respectively, tauBoo appears as the first planet-hosting star whose rotation (at intermediate latitudes) is synchronised with the orbital motion of its giant planet (period 3.3 d). Assuming that this synchronisation is not coincidental, it suggests that the tidal effects induced by the giant planet can be strong enough to force the thin convective enveloppe (though not the whole star) into corotation and thus to play a role in the activity cycle of tauBoo.
description: MNRAS, in press
Charge density of light exotic nuclei and $ρNN$ tensor coupling
Creators: name: Jiang, W. Z.
name: Zhao, Y. L.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: We use a relativistic mean field model to study the charge density distributions of exotic oxygen isotopes. Nonlinear isoscalar-isovector terms which are not constrained by the present data are considered and the $ρNN$ tensor coupling that does not affect the symmetry energy in the mean field model is included. Strong correlations between the neutron radius of $^{208}$Pb and the charge radius of $^{12,13,23,24}$O are found. The $ρNN$ tensor coupling explicitly enhances the radius correlations between $^{23,24}$O and $^{208}$Pb. This enhancement is due to the neutron occupation of the orbital $2s_{1/2}$. The charge radius is sensitive to the change of the density dependence of the symmetry energy as the isotope goes towards the proton drip line.
description: 13 pages, 4 figures
Tidal mass loss in the Fornax dwarf spheroidal galaxy through N-body simulations with Gaia DR3-based orbits
Creators: name: Di Cintio, Pierfrancesco
name: Iorio, Giuliano
name: Calura, Francesco
name: Nipoti, Carlo
name: Cantari, Marcello
Publisher: name: arXiv
Year: 2024
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The Fornax dwarf spheroidal galaxy (dSph) represents a challenge for some globular cluster (GC) formation models, because an exceptionally high fraction of its stellar mass is locked in its GC system. In order to shed light on our understanding of GC formation, we aim to constrain the amount of stellar mass that Fornax has lost via tidal interaction with the Milky Way (MW). Exploiting the flexibility of effective multi-component $N$-body simulations and relying on state-of-the-art estimates of Fornax's orbital parameters, we study the evolution of the mass distribution of the Fornax dSph in observationally justified orbits in the gravitational potential of the MW over 12 Gyr. We find that, though the dark-matter mass loss can be substantial, the fraction of stellar mass lost by Fornax to the MW is always negligible, even in the most eccentric orbit considered. We conclude that stellar-mass loss due to tidal stripping is not a plausible explanation for the unexpectedly high stellar mass of the GC system of the Fornax dSph and we discuss quantitatively the implications for GC formation scenarios.
description: 15 pages, 12 figures. Version accepted in A&A
Time-limited Balanced Truncation for Data Assimilation Problems
Creators: name: König, Josie
name: Freitag, Melina A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: Systems and Control (eess.SY)
subject: FOS: Mathematics
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: 62F15, 65L99, 93A15, 93B11

description: Balanced truncation is a well-established model order reduction method which has been applied to a variety of problems. Recently, a connection between linear Gaussian Bayesian inference problems and the system-theoretic concept of balanced truncation has been drawn. Although this connection is new, the application of balanced truncation to data assimilation is not a novel idea: it has already been used in four-dimensional variational data assimilation (4D-Var). This paper discusses the application of balanced truncation to linear Gaussian Bayesian inference, and, in particular, the 4D-Var method, thereby strengthening the link between systems theory and data assimilation further. Similarities between both types of data assimilation problems enable a generalisation of the state-of-the-art approach to the use of arbitrary prior covariances as reachability Gramians. Furthermore, we propose an enhanced approach using time-limited balanced truncation that allows to balance Bayesian inference for unstable systems and in addition improves the numerical results for short observation periods.
description: 24 pages, 5 figures
Convexity of noncontextual wirings and how they order the set of correlations
Creators: name: Santos, Tiago
name: Wagner, Rafael
name: Amaral, Bárbara
Publisher: name: arXiv
Year: 2024
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The resource theory of contextuality considers resourceful objects to be probabilistic data-tables, known as correlations or behaviors, that fail to have an explanation in terms of Kochen-Specker noncontextual models. In this work, we advance this resource theory, considering free operations to be noncontextual wirings (NCW). We show that all such wirings form a convex set. When restricted to Bell scenarios, we show that such wirings are not equivalent to local operations assisted by a common source of classical shared randomness (LOSR). The set of all NCW operations contains LOSR, but is strictly larger. We also prove several elementary facts about how different resources can be converted via NCW. As a concrete example, we show that there are pairs of behaviors that cannot be converted one into the other using NCW. Since resource conversion mathematically induces a pre-order over the set of all behaviors, our results reveal the intricate ordering induced by NCW in scenarios beyond Bell scenarios.
description: 23 pages, 7 figures; supersedes arXiv:2210.03268. Comments are welcome
Anomalous magnetic moment and vortex structure of the electron
Creators: name: Tiwari, S C
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: The electron magnetic moment decomposition calculated in QED is proposed to have origin in a multi-vortex internal structure of the electron. This proposition is founded on two important contributions of the present work. First, a critical review on Weyl model of electron, Einstein-Rosen bridge and Wheeler's wormholes leads to a new idea of a topological defect in cylindrical space-time geometry as a natural representation of the electron. A concrete realization of this idea in terms of the derivation of a new vortex-metric, and its physical interpretation to establish the geometric origin of the electron magnetic moment decomposition constitute the second contribution. Remarkable occurrence of a vortex structure in the basis mode function used in BLFQ is also pointed out indicating wider ramification of the proposed electron model.
description: 10 pages
Goodness-of-Fit Tests for Symmetric Stable Distributions -- Empirical Characteristic Function Approach
Creators: name: Matsui, Muneya
name: Takemura, Akimichi
Publisher: name: arXiv
Year: 2006
Subjects: subject: Statistics Theory (math.ST)
subject: FOS: Mathematics
subject: 60E07:62F03

description: We consider goodness-of-fit tests of symmetric stable distributions based on weighted integrals of the squared distance between the empirical characteristic function of the standardized data and the characteristic function of the standard symmetric stable distribution with the characteristic exponent $α$ estimated from the data. We treat $α$ as an unknown parameter, but for theoretical simplicity we also consider the case that $α$ is fixed. For estimation of parameters and the standardization of data we use maximum likelihood estimator (MLE) and an equivariant integrated squared error estimator (EISE) which minimizes the weighted integral. We derive the asymptotic covariance function of the characteristic function process with parameters estimated by MLE and EISE. For the case of MLE, the eigenvalues of the covariance function are numerically evaluated and asymptotic distribution of the test statistic is obtained using complex integration. Simulation studies show that the asymptotic distribution of the test statistics is very accurate. We also present a formula of the asymptotic covariance function of the characteristic function process with parameters estimated by an efficient estimator for general distributions.
Bayesian posterior approximation with stochastic ensembles
Creators: name: Balabanov, Oleksandr
name: Mehlig, Bernhard
name: Linander, Hampus
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences

description: We introduce ensembles of stochastic neural networks to approximate the Bayesian posterior, combining stochastic methods such as dropout with deep ensembles. The stochastic ensembles are formulated as families of distributions and trained to approximate the Bayesian posterior with variational inference. We implement stochastic ensembles based on Monte Carlo dropout, DropConnect and a novel non-parametric version of dropout and evaluate them on a toy problem and CIFAR image classification. For both tasks, we test the quality of the posteriors directly against Hamiltonian Monte Carlo simulations. Our results show that stochastic ensembles provide more accurate posterior estimates than other popular baselines for Bayesian inference.
description: 19 pages, CVPR 2023
Spin Coherent Manipulation in Josephson Weak Links
Creators: name: Cerrillo, Javier
name: Hays, Max
name: Fatemi, Valla
name: Yeyati, Alfredo Levy
Publisher: name: arXiv
Year: 2020
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: Novel designs of Josephson weak links based on semiconducting nanowires combined with circuit QED techniques have enabled the resolution of their fine structure due to spin-orbit interactions, opening a path towards Andreev spin qubits. Nevertheless, direct manipulation of the spin within a given Andreev state is in general suppressed compared to inter-doublet manipulation in the absence of Zeeman effects. In addition, noisy spin-flip mechanisms limit any coherent manipulation protocol to spin post-selection. We propose a combination of a spin polarization protocol analogous to sideband cooling with stimulated Raman adiabatic passage specifically tailored for these systems. We show this approach is robust for a large range of design parameters, including the currently rather stringent coherence times.
description: 10 pages, 6 figures
Boundedness of families of canonically polarized manifolds: A higher dimensional analogue of Shafarevich's conjecture
Creators: name: Kovacs, Sandor J.
name: Lieblich, Max
Publisher: name: arXiv
Year: 2006
Subjects: subject: Algebraic Geometry (math.AG)
subject: FOS: Mathematics
subject: 14J10

description: We show that the number of deformation types of canonically polarized manifolds over an arbitrary variety with proper singular locus is finite, and that this number is uniformly bounded in any finite type family of base varieties. As a corollary we show that a direct generalization of the geometric version of Shafarevich's original conjecture holds for infinitesimally rigid families of canonically polarized varieties.
description: 19 pages, v2: minor changes; one reference added to make a step cleaner and one name added to acknowledgements, v3: final version to appear in Annals of Mathematics
Isothermal and isentropic speed of sound in (2+1)-flavor QCD at non-zero baryon chemical potential
Creators: name: Clarke, D. A.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: Recently interest in calculations of the speed of sound in QCD under conditions like constant temperature $c^2_T$ or constant entropy per net baryon number $c^2_s$ arose in the discussion of experimental results coming from heavy ion experiments. It has been stressed that the former in particular is closely related to higher order cumulants of conserved charge fluctuations that are calculated in lattice QCD. We present here results on $c^2_T$ and $c^2_s$ and compare results at vanishing strangeness chemical potential and vanishing net strangeness number with hadron resonance gas model calculations. We stress the difference of both observables at low temperature arising from the light meson sector, which does not contribute to $c^2_T$.
description: 10 pages, 4 figures, presented at the 39th International Symposium on Lattice Field Theory. For the HotQCD Collaboration
Experimental Realization of an Optical One-Way Barrier for Neutral Atoms
Creators: name: Thorn, Jeremy J.
name: Schoene, Elizabeth A.
name: Li, Tao
name: Steck, Daniel A.
Publisher: name: arXiv
Year: 2008
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We demonstrate an asymmetric optical potential barrier for ultracold 87 Rb atoms using laser light tuned near the D_2 optical transition. Such a one-way barrier, where atoms impinging on one side are transmitted but reflected from the other, is a realization of Maxwell's demon and has important implications for cooling atoms and molecules not amenable to standard laser-cooling techniques. In our experiment, atoms are confined to a far-detuned dipole trap consisting of a single focused Gaussian beam, which is divided near the focus by the barrier. The one-way barrier consists of two focused laser beams oriented almost normal to the dipole-trap axis. The first beam is tuned to have a red (blue) detuning from the F=1 -> F' (F=2 -> F') hyperfine transitions, and thus presents a barrier only for atoms in the F=2 ground state, while letting F=1 atoms pass. The second beam pumps the atoms to F=2 on the reflecting side of the barrier, thus producing the asymmetry.
description: 5 pages, 4 figures; includes changes to address referee comments
Reading Yamada Eimi
Creators: name: Spies, Alwyn
Publisher: name: University of British Columbia
Year: 2009

description: The Japanese novelist Yamada Eimi has published many controversial and popular books. As she herself lives openly and controversially in the same way that she writes, Yamada Eimi the person is often confused with the narrators of her stories. This essay is not only a reading of her texts, but also an analysis of how "Yamada Eimi," the author, is embedded into these texts and then consumed by the reader. Starting first with two examples of diametrically opposed readings by the North American critics Richard Okada and Kuwahara Yasue, I then outline my reading which falls somewhere in between Okada's and Kuwahara's. Several Japanese readings of Yamada's writings indicate that Yamada creates her own world with its own value system and then draws the readers into this system. In Chapter One, a close reading of three of Yamada's works shows that this system is an aesthetic code that defines the behaviour, dress and attitude of the female characters in the stories. Chapter Two then shows how this code is communicated to the readers. The homosocial "sister" relationships that allow this communication are also part of how the readers are drawn in. In Chapter Thriee I combine the aesthetic code with the "sister structure" to illustrate how the reader is also included in a sister relationship with Yamada Eimi.. Back full circle, I then show how different readings of the same texts become possible.
Differential forms on $C^\infty$-ringed spaces
Creators: name: Lerman, Eugene
Publisher: name: arXiv
Year: 2022
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics

description: We construct a complex of differential forms on a local $C^\infty$-ringed space. The two main classes of spaces we have in mind are differential spaces in the sense of Sikorski and $C^\infty$-schemes. Just as in the case of manifolds the construction is functorial. Consequently forms can be integrated over simplices and Stokes' theorem holds.
description: v3: 38 pages. Paper shortened by removal of expository material
Influences of magnetic coupling process on the spectrum of a disk covered by the corona
Creators: name: Ma, R. Y.
name: Wang, D. X.
name: Zuo, X. Q.
Publisher: name: arXiv
Year: 2006
Subjects: subject: Astrophysics (astro-ph)
subject: FOS: Physical sciences

description: Recently, much attention has been paid to the magnetic coupling (MC) process, which is supported by very high emissivity indexes observed in Seyfert 1 galaxy MCG-6-30-15 and GBHC XTE J1650-500. But the rotational energy transferred from a black hole is simply assumed to be radiated away from the surrounding accretion disk in black-body spectrum, which is obviously not consistent with the observed hard power-law X-ray spectra. We intend to introduce corona into the MC model to make it more compatible with the observations. We describe the model and the procedure of a simplified Monte Carlo simulation, compare the output spectra in the cases with and without the MC effects, and discuss the influences of three parameters involved in the MC process on the output spectra. It is shown that the MC process augments radiation fluxes in the UV or X-ray band. The emergent spectrum is affected by the BH spin and magnetic field strength at the BH horizon, while it is almost unaffected by the radial profile of the magnetic field at the disk. Introducing corona into the MC model will improve the fitting of the output spectra from AGNs and GBHCs.
description: 15 pages, 5 figures, accepted by A&A
Magnetic oxides
Creators: name: Khomskii, D. I.
name: Streltsov, S. V.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: In this article we give a general survey of the main properties of magnetic oxides - mostly the oxides of transition metals, but sometime also containing rare earths ions. This is a very rich class of materials, among which there are insulators and metals, systems with insulator-metal transitions, and there are among them even high-temperature superconductors. One of the main features of these compounds, which attract to them special attention and which serve as a basis of many applications, are their rich magnetic properties. In this article we discuss the main physical effects determining their behaviour, and describe in detail especially their magnetic properties, but not only. After shortly discussing the basic structure of isolated magnetic ions, we concentrate on the collective effects depending on the interaction between sites, especially exchange interaction, giving rise to different magnetic properties: different types of magnetic ordering in conventional systems, but also more exotic states such as spin liquid states in frustrated systems. We also cover related phenomena in magnetic oxides, such as magnetoelectric and multiferroic behaviour, and discuss at the end their diverse useful properties serving as a basis of many applications.
description: Chapter to Encyclopedia of Condensed Matter Physics, 2nd edition
Spatiotemporal patterns in the active cyclic Potts model
Creators: name: Noguchi, Hiroshi
name: Fournier, Jean-Baptiste
Publisher: name: arXiv
Year: 2024
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: The nonequilibrium dynamics of a cycling three-state Potts model is studied on a square lattice using Monte Carlo simulations and continuum theory. This model is relevant to chemical reactions on a catalytic surface and to molecular transport across a membrane. Several characteristic modes are formed depending on the flipping energies between successive states and the contact energies between neighboring sites. Under cyclic symmetry conditions, cycling homogeneous phases and spiral waves form at low and high flipping energies, respectively. In the intermediate flipping energy regime, these two modes coexist temporally in small systems and/or at low contact energies. Under asymmetric conditions, we observed small biphasic domains exhibiting amoeba-like locomotion and temporal coexistence of spiral waves and a dominant non-cyclic one-state phase. An increase in the flipping energy between two successive states, say state 0 and state 1, while keeping the other flipping energies constant, induces the formation of the third phase (state 2), owing to the suppression of the nucleation of state 0 domains. Under asymmetric conditions regarding the contact energies, two different modes can appear depending on the initial state, due to a hysteresis phenomenon.
description: 14 pages, 15 figures
Predicting permeability via statistical learning on higher-order microstructural information
Creators: name: Röding, Magnus
name: Ma, Zheng
name: Torquato, Salvatore
Publisher: name: arXiv
Year: 2020
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Computational Physics (physics.comp-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Physical sciences

description: Quantitative structure-property relationships are crucial for the understanding and prediction of the physical properties of complex materials. For fluid flow in porous materials, characterizing the geometry of the pore microstructure facilitates prediction of permeability, a key property that has been extensively studied in material science, geophysics and chemical engineering. In this work, we study the predictability of different structural descriptors via both linear regressions and neural networks. A large data set of 30,000 virtual, porous microstructures of different types is created for this end. We compute permeabilities of these structures using the lattice Boltzmann method, and characterize the pore space geometry using one-point correlation functions (porosity, specific surface), two-point surface-surface, surface-void, and void-void correlation functions, as well as the geodesic tortuosity as an implicit descriptor. Then, we study the prediction of the permeability using different combinations of these descriptors. We obtain significant improvements of performance when compared to a Kozeny-Carman regression with only lowest-order descriptors (porosity and specific surface). We find that combining all three two-point correlation functions and tortuosity provides the best prediction of permeability, with the void-void correlation function being the most informative individual descriptor. Moreover, the combination of porosity, specific surface, and geodesic tortuosity provides very good predictive performance. This shows that higher-order correlation functions are extremely useful for forming a general model for predicting physical properties of complex materials. Additionally, our results suggest that neural networks are superior to the more conventional regression methods for establishing quantitative structure-property relationships.
Counterfactual universal quantum computation
Creators: name: Cao, Zhu
Publisher: name: arXiv
Year: 2020
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Universal quantum computation is usually associated with interaction among two-level quantum subsystems, as this interaction is commonly viewed as a necessity to achieve universal quantum computation. In this work, we show that, contrary to this intuition, universal quantum computation can be achieved without interaction among initially independent two-level quantum subsystems. We call it counterfactual universal quantum computation. As special cases, we show how to achieve counterfactual communication of quantum states, counterfactual quantum swapping, and counterfactual quantum erasure codes. To ease practical implementation, we analyze counterfactual universal quantum computation with realistic devices, including the effects of finite execution time, photon loss, and atom missing. Besides the theoretical interest of illustrating the mysterious and counterintuitive nature of quantum physics, our work has practical applications to color imaging of ancient arts, upon which light is forbidden to shine.
description: 12 pages, 9 figures
Implementation and Empirical Evaluation of a Quantum Machine Learning Pipeline for Local Classification
Creators: name: Zardini, Enrico
name: Blanzieri, Enrico
name: Pastorello, Davide
Publisher: name: arXiv
Year: 2022
Subjects: subject: Emerging Technologies (cs.ET)
subject: Quantum Physics (quant-ph)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: In the current era, quantum resources are extremely limited, and this makes difficult the usage of quantum machine learning (QML) models. Concerning the supervised tasks, a viable approach is the introduction of a quantum locality technique, which allows the models to focus only on the neighborhood of the considered element. A well-known locality technique is the k-nearest neighbors (k-NN) algorithm, of which several quantum variants have been proposed. Nevertheless, they have not been employed yet as a preliminary step of other QML models, whereas the classical counterpart has already proven successful. In this paper, we present (i) an implementation in Python of a QML pipeline for local classification, and (ii) its extensive empirical evaluation. Specifically, the quantum pipeline, developed using Qiskit, consists of a quantum k-NN and a quantum binary classifier. The results have shown the quantum pipeline's equivalence (in terms of accuracy) to its classical counterpart in the ideal case, the validity of locality's application to the QML realm, but also the strong sensitivity of the chosen quantum k-NN to probability fluctuations and the better performance of classical baseline methods like the random forest.
description: 33 pages, 8 figures, 9 tables
Probing the Feasibility of Multilingual Speaker Anonymization
Creators: name: Meyer, Sarina
name: Lux, Florian
name: Vu, Ngoc Thang
Publisher: name: arXiv
Year: 2024
Subjects: subject: Computation and Language (cs.CL)
subject: Sound (cs.SD)
subject: Audio and Speech Processing (eess.AS)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: In speaker anonymization, speech recordings are modified in a way that the identity of the speaker remains hidden. While this technology could help to protect the privacy of individuals around the globe, current research restricts this by focusing almost exclusively on English data. In this study, we extend a state-of-the-art anonymization system to nine languages by transforming language-dependent components to their multilingual counterparts. Experiments testing the robustness of the anonymized speech against privacy attacks and speech deterioration show an overall success of this system for all languages. The results suggest that speaker embeddings trained on English data can be applied across languages, and that the anonymization performance for a language is mainly affected by the quality of the speech synthesis component used for it.
description: accepted at Interspeech 2024
Model Independent Bounds on Magnetic Moments of Majorana Neutrinos
Creators: name: Bell, Nicole F.
name: Gorchtein, Mikhail
name: Ramsey-Musolf, Michael J.
name: Vogel, Petr
name: Wang, Peng
Publisher: name: arXiv
Year: 2006
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We analyze the implications of neutrino masses for the magnitude of neutrino magnetic moments. By considering electroweak radiative corrections to the neutrino mass, we derive model-independent naturalness upper bounds on neutrino magnetic moments, $μ_ν$, generated by physics above the electroweak scale. For Dirac neutrinos, the bound is several orders of magnitude more stringent than present experimental limits. However, for Majorana neutrinos the magnetic moment contribution to the mass is Yukawa suppressed. The bounds we derive for magnetic moments of Majorana neutrinos are weaker than present experimental limits if $μ_ν$ is generated by new physics at ~ 1 TeV, and surpass current experimental sensitivity only for new physics scales > 10 -- 100 TeV. The discovery of a neutrino magnetic moment near present limits would thus signify that neutrinos are Majorana particles.
description: 8 pages, 5 figures