cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Analysis of rescattering effects in $3π$ final states
Creators: name: Stamen, Dominik
name: Isken, Tobias
name: Kubis, Bastian
name: Mikhasenko, Mikhail
name: Niehus, Malwin
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: Decays into three particles are often described in terms of two-body resonances and a non-interacting spectator particle. To go beyond this simplest isobar model, crossed-channel rescattering effects need to be accounted for. We quantify the importance of these rescattering effects in three-pion systems for different decay masses and angular-momentum quantum numbers. We provide the amplitude decompositions for four decay processes with total $J^{PC} = 0^{--}$, $1^{--}$, $1^{-+}$, and $2^{++}$, all of which decay predominantly as $ρπ$ states. Two-pion rescattering is described in terms of an Omnès function, which incorporates the $ρ$ resonance. Inclusion of crossed-channel effects is achieved by solving the Khuri-Treiman integral equations. The unbinned log-likelihood estimator is used to determine the significance of the rescattering effects beyond two-body resonances; we compute the minimum number of events necessary to unambiguously find these in future Dalitz-plot analyses. Kinematic effects that enhance or dilute the rescattering are identified for the selected set of quantum numbers and various masses.
description: 22 pages, 13 figures; v2: reconstruction theorem for 2++ channel corrected
Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies
Creators: name: Hamdi, Mohammad
name: Posva, Ferdinand
name: Grundler, Dirk
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Low magnetic damping and high group velocity of spin waves (SWs) or magnons are two crucial parameters for functional magnonic devices. Magnonics research on signal processing and wave-based computation at GHz frequencies focussed on the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report on spin-wave spectroscopy studies performed on the natural mineral hematite ($α\text{-Fe}_2\text{O}_3$) which is a canted antiferromagnet. By means of broadband GHz spectroscopy and inelastic light scattering, we determine a damping coefficient of $1.1\times10^{-5}$ and magnon group velocities of a few 10 km/s, respectively, at room temperature. Covering a large regime of wave vectors up to $k\approx 24~{\rm rad}/μ$m, we find the exchange stiffness length to be relatively short and only about 1 Å. In a small magnetic field of 30 mT, the decay length of SWs is estimated to be 1.1 cm similar to the best YIG. Still, inelastic light scattering provides surprisingly broad and partly asymmetric resonance peaks. Their characteristic shape is induced by the large group velocities, low damping and distribution of incident angles inside the laser beam. Our results promote hematite as an alternative and sustainable basis for magnonic devices with fast speeds and low losses based on a stable natural mineral.
The ALPINE-ALMA [CII] survey: double stellar population and AGN activity in a galaxy at $z\sim5.5$
Creators: name: Barchiesi, L.
name: Dessauges-Zavadsky, M.
name: Vignali, C.
name: Pozzi, F.
name: Marques-Chaves, R.
name: Feltre, A.
name: Faisst, A.
name: Béthermin, M.
name: Cassata, P.
name: Charlot, S.
name: Fudamoto, Y.
name: Ginolfi, M.
name: Ibar, E.
name: Jones, G. C.
name: Romano, M.
name: Schaerer, D.
name: Vallini, L.
name: Vanzella, E.
name: Yan, L.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: GDS J033218.92-275302.7 (here GS-14) is a $z\sim5.5$ galaxy detected in [CII] as part of the ALPINE survey with unusual UV spectral features that have been interpreted as signatures of either a double stellar population or of an active galactic nucleus (AGN). We exploited the multi-wavelength coverage of GS-14 to investigate the properties and the origin of its emission. We performed UV-to-NIR SED-fitting, with single/double stellar population and/or AGN component. We analyzed the VIMOS spectrum, which shows highly-ionized emission lines (Ovi, Nv, and Niv). The line properties have been compared with those observed in galaxies and AGN, and with the predictions from radiation transfer models for star-forming galaxies, AGN, and shocks. The SED-fitting provides a total stellar mass of $M_*=(4 \pm 1) \times 10^{10} M_\odot$, an age of the main stellar population of $\sim670 Myr$ and a recent short (8 Myr) burst of star formation (SF) of $\sim 90 M_\odot yr^{-1}$. The Nv line has a characteristic P-Cygni profile, which suggests a $\sim 3 Myr$ old population of stars with a mass of $\sim 5 \times10^{7} M_\odot$. The Nv profile also shows evidence for an additional component of nebular emission. The comparison of the line ratios with theoretical models allows us to associate the emission with SF or AGN, but the strong radiation field required to ionize the Ovi is more commonly related to AGN activity. We found evidence for an old and already evolved stellar population at $z\sim 5.5$ and show that the galaxy is experiencing a second short burst of SF. In addition, GS-14 carries signatures of obscured AGN activity. The AGN could be responsible for the short depletion time of this galaxy, thus making GS-14 one of the two ALPINE sources with hints of an active nucleus and an interesting target for future follow-ups.
description: Accepted in A&A, 10 pages, 4 figures
Genuine many-body quantum scars along unstable modes in Bose-Hubbard systems
Creators: name: Hummel, Quirin
name: Richter, Klaus
name: Schlagheck, Peter
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The notion of many-body quantum scars is associated with special eigenstates, usually concentrated in certain parts of Hilbert space, that give rise to robust persistent oscillations in a regime that globally exhibits thermalization. Here we extend these studies to many-body systems possessing a true classical limit characterized by a high-dimensional chaotic phase space, which are not subject to any particular dynamical constraint. We demonstrate genuine quantum scarring of wave functions concentrated in the vicinity of unstable classical periodic mean-field modes in the paradigmatic Bose-Hubbard model. These peculiar quantum many-body states exhibit distinct phase-space localization about those classical modes. Their existence is consistent with Heller's scar criterion and appears to persist in the thermodynamic long-lattice limit. Launching quantum wave packets along such scars leads to observable long-lasting oscillations, featuring periods that scale asymptotically with classical Lyapunov exponents, and displaying intrinsic irregularities that reflect the underlying chaotic dynamics, as opposed to regular tunnel oscillations.
description: 17 pages, 10 figures
Pattern recognition in the ALFALFA.70 and Sloan Digital Sky Surveys: A catalog of $\sim$ 500,000 HI gas fraction estimates based on artificial neural networks
Creators: name: Teimoorinia, Hossen
name: Ellison, Sara L.
name: Patton, David R.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The application of artificial neural networks (ANNs) for the estimation of HI gas mass fraction (\fgas) is investigated, based on a sample of 13,674 galaxies in the Sloan Digital Sky Survey (SDSS) with HI detections or upper limits from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA). We show that, for an example set of fixed input parameters ($g-r$ colour and $i$-band surface brightness), a multidimensional quadratic model yields \fgas\ scaling relations with a smaller scatter (0.22 dex) than traditional linear fits (0.32 dex), demonstrating that non-linear methods can lead to an improved performance over traditional approaches. A more extensive ANN analysis is performed using 15 galaxy parameters that capture variation in stellar mass, internal structure, environment and star formation. Of the 15 parameters investigated, we find that $g-r$ colour, followed by stellar mass surface density, bulge fraction and specific star formation rate have the best connection with \fgas. By combining two control parameters, that indicate how well a given galaxy in SDSS is represented by the ALFALFA training set (\pr) and the scatter in the training procedure (\sigf), we develop a strategy for quantifying which SDSS galaxies our ANN can be adequately applied to, and the associated errors in the \fgas\ estimation. In contrast to previous works, our \fgas\ estimation has no systematic trend with galactic parameters such as M$_{\star}$, $g-r$ and SFR. We present a catalog of \fgas\ estimates for more than half a million galaxies in the SDSS, of which $\sim$ 150,000 galaxies have a secure selection parameter with average scatter in the \fgas\ estimation of 0.22 dex.
description: Accepted for publication in MNRAS. 16 pages, 22 figures, 2 tables
Galaxies with conspicuous optical warps
Creators: name: Reshetnikov, Vladimir P.
name: Mosenkov, Aleksandr V.
name: Moiseev, Alexei V.
name: Kotov, Sergey S.
name: Savchenko, Sergey S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: In this paper, we present results of a photometric and kinematic study for a sample of 13 edge-on spiral galaxies with pronounced integral-shape warps of their stellar discs. The global structure of the galaxies is analyzed on the basis of the Sloan Digital Sky Survey (SDSS) imaging, in the g, r and i passbands. Spectroscopic observations are obtained with the 6-m Special Astrophysical Observatory telescope. In general, galaxies of the sample are typical bright spiral galaxies satisfying the Tully-Fisher relation. Most of the galaxies reside in dense spatial environments and, therefore, tidal encounters are the most probable mechanism for generating their stellar warps. We carried out a detailed analysis of the galaxies and their warps and obtained the following main results: (i) maximum angles of stellar warps in our sample are about 20°; (ii) warps start, on average, between 2 and 3 exponential scale lengths of a disc; (iii) stronger warps start closer to the center, weak warps start farther; (iv) warps are asymmetric, with the typical degree of asymmetry of about several degrees (warp angle); (v) massive dark halo is likely to preclude the formation of strong and asymmetric warps.
description: 15 pages, 8 figures, accepted for publication in MNRAS
Supplementary Material 2 from Coupling of coastal activity with tidal cycles is stronger in tool-using capuchins (Cebus capucinus imitator)
Creators: name: Goldsborough, Zoë
name: Crofoot, Margaret C.
name: Alavi, Shauhin E.
name: Del Rosario-Vargas, Evelyn
name: Garza, Sylvia F.
name: Tiedeman, Kate
name: Barrett, Brendan J.
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: Ecology
subject: Animal Behaviour

description: Spanish translation of abstract
Quadrupole partial orders and triple-$q$ states on the face-centered cubic lattice
Creators: name: Hattori, Kazumasa
name: Ishitobi, Takayuki
name: Tsunetsugu, Hirokazu
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We study $Γ_3$ quadrupole orders in a face-centered cubic lattice. The $Γ_3$ quadrupole moments under cubic symmetry possess a unique cubic invariant in their free energy in the uniform ($q=0$) sector and the triple-q sector for the X points $q=(2π,0,0),(0,2π,0)$, and $(0,0,2π)$. Competition between this cubic anisotropy and anisotropic quadrupole-quadrupole interactions causes a drastic impact on the phase diagram both in the ground state and at finite temperatures. We show details about the model construction and its properties, the phase diagram, and the mechanism of the various triple-$q$ quadrupole orders reported in our preceding letter [J. Phys. Soc. Jpn. 90, 43701 (2021), arXiv:2102.06346]. By using a mean-field approach, we analyze a quadrupole exchange model that consists of a crystalline-electric field scheme with the ground-state $Γ_3$ non-Kramers doublet and the excited singlet $Γ_1$ state. We find various triple-$q$ orders in the four-sublattice mean-field approximation. A few partial orders of quadrupoles are stabilized in a wide range of parameter space at a higher transition temperature than single-$q$ orders. With lowering the temperature, these partial orders undergo phase transitions into further symmetry broken phases in which nonvanishing quadrupole moments emerge at previously disordered sites. The obtained phases in the mean-field approximation are investigated by a phenomenological Landau theory, which clearly shows that the cubic invariant plays an important role for stabilizing the triple-$q$ states. We also discuss its implications for recent experiments in a few f- and d-electron compounds.
description: 28 pages, 20 figures
Las TICs que llegaron a la Universidad como un tsunami
Creators: name: García-Peñalvo, F. J.
Publisher: name: Zenodo
Year: 2022
Subjects: Tecnologías para el aprendizaje; Ecosistema tecnológico; Transformación digital

description: Conferencia invitada en la edición XXI del Aula de Verano «Ortega y Gasset» de Iniciación a la Universidad, que en esta ocasión lleva el título de “Todo lo que aprendemos y más”. Como es habitual, este evento está programado en dentro de los Cursos de Verano de la Universidad Internacional Menéndez Pelayo (UIMP), celebrándse del 15 a 19 de agosto de 2022 en el Palacio de la Magdalena, Santander. El objetivo de la conferencia es presentar cómo la tecnología educativa ha pasado a ser habitual en nuestras universidades, entrando actualmente en una fase imparable de transformación digital. No obstante, como el curso está orientado a bachilleres de excelencia, se busca transmitir también de una forma motivadora la trayectoria académica, por lo que se ha utilizado la metáfora de la playlist de música, dando a la conferencia el título alternativo de “Dream on. La playlist de una vocación”.
Topological Phases in Coupled Polyyne Chains
Creators: name: Ara, Nisa
name: Basu, Rudranil
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: We study the electronic properties of coupled parallel Polyyne chains in a couple of symmetric stacking arrangements, namely the AA stacking and the stacking AB, with the single and triple carbon bonds of one chain aligned (AA) and anti-aligned (AB) with those of the other chain. Both these arrangements described by tight binding Hamiltonians, whose parameters are calibrated by matching low energy dispersion provided by first principle calculations, fall in the BDI class of topological classification scheme. We calculate the topological invariants for all the three topological phases of the system: one for the AA stacking and 2 for the AB one. In the AA stacking, both the insulating and the metallic phase belongs to the same topological phase. Whereas, the model exhibits two different values of the topological invariant in the two different insulating phases (structurally differentiated by transverse strain). In this later stacking though transition between two distinct topological phases with the closure of the gap is practically unachievable due requirement of high amount of transverse strain. We also show existence of 4 non-zero energy edge modes in the AA stacking and that of 2 zero energy edge modes in one of the topological phases for the AB stacking.
description: 3 figures
Supplementary Material 1 from Coupling of coastal activity with tidal cycles is stronger in tool-using capuchins (Cebus capucinus imitator)
Creators: name: Goldsborough, Zoë
name: Crofoot, Margaret C.
name: Alavi, Shauhin E.
name: Del Rosario-Vargas, Evelyn
name: Garza, Sylvia F.
name: Tiedeman, Kate
name: Barrett, Brendan J.
Publisher: name: The Royal Society
Year: 2023
Subjects: subject: Evolutionary Biology
subject: FOS: Biological sciences
subject: Ecology
subject: Animal Behaviour

description: Supplementary figures and tables, including timing of tides, overview of camera deployments, posterior mean model estimates and supplementary figures for all models
Quasinormal Modes in Near-Extremal Spinning C-Metric
Creators: name: Gwak, Bogeun
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate the quasinormal modes of the spinning C-metric with a massless scalar field conformally coupled with gravity. Conformal transformation is employed to separate and subsequently solve the massless scalar field equations. As the outer and acceleration horizons approach each other, the potential term of the field equation is reduced to the Pöshl-Teller potential because the acceleration horizon is similar to the cosmological horizon of de Sitter spacetime. Finally, we obtain the analytical quasinormal frequency at which the decay rate is quantized.
description: 13 pages, 2 figures
Longitudinal Face Modeling via Temporal Deep Restricted Boltzmann Machines
Creators: name: Duong, Chi Nhan
name: Luu, Khoa
name: Quach, Kha Gia
name: Bui, Tien D.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Modeling the face aging process is a challenging task due to large and non-linear variations present in different stages of face development. This paper presents a deep model approach for face age progression that can efficiently capture the non-linear aging process and automatically synthesize a series of age-progressed faces in various age ranges. In this approach, we first decompose the long-term age progress into a sequence of short-term changes and model it as a face sequence. The Temporal Deep Restricted Boltzmann Machines based age progression model together with the prototype faces are then constructed to learn the aging transformation between faces in the sequence. In addition, to enhance the wrinkles of faces in the later age ranges, the wrinkle models are further constructed using Restricted Boltzmann Machines to capture their variations in different facial regions. The geometry constraints are also taken into account in the last step for more consistent age-progressed results. The proposed approach is evaluated using various face aging databases, i.e. FG-NET, Cross-Age Celebrity Dataset (CACD) and MORPH, and our collected large-scale aging database named AginG Faces in the Wild (AGFW). In addition, when ground-truth age is not available for input image, our proposed system is able to automatically estimate the age of the input face before aging process is employed.
description: in The IEEE Conference on Computer Vision and Pattern Recognition (CVPR) 2016
The activated scaling behavior of quantum Griffiths singularity in two-dimensional superconductors
Creators: name: Cui, Zihan
name: Pan, Longxin
name: Fang, Jingchao
name: Qi, Shichao
name: Xing, Ying
name: Liu, Haiwen
name: Liu, Yi
name: Wang, Jian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Quantum Griffiths singularity is characterized by the divergence of the dynamical critical exponent with the activated scaling law and has been widely observed in various two-dimensional superconductors. Recently, the direct activated scaling analysis with the irrelevant correction has been proposed and successfully used to analyze the experimental data of crystalline PdTe2 and polycrystalline \b{eta}-W films, which provides new evidence of quantum Griffiths singularity. Here we show that the direct activated scaling analysis is applicable to the experimental data in different superconducting films, including tri-layer Ga films and LaAlO3/SrTiO3 interface superconductor. When taking the irrelevant correction into account, we calculate the corrected sheet resistance at ultralow temperatures. The scaling behavior of the corrected resistance in a comparably large temperature regime and the theoretical fitting of the phase boundary give unambiguous evidence of quantum Griffiths singularity. Compared to the previous method based on the finite size scaling, the direct activated scaling analysis represents a more direct and precise way to analyze the experimental data of quantum Griffiths singularity in diverse two-dimensional superconductors.
Reliability of the two-point measurement of the spatial correlation length from Gaussian-shaped fluctuating signals in fusion-grade plasmas
Creators: name: Kim, Jaewook
name: Nam, Y. U.
name: Lampert, M.
name: Ghim, Y. -c.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: A statistical method for the estimation of spatial correlation lengths of Gaussian-shaped fluctuating signals with two measurement points is examined to quantitatively evaluate its reliability (variance) and accuracy (bias error). The standard deviation of the correlation value is analytically derived for randomly distributed Gaussian shaped fluctuations satisfying stationarity and homogeneity, allowing us to evaluate, as a function of fluctuation-to-noise ratios, sizes of averaging time windows and ratios of the distance between the two measurement points to the true correlation length, the goodness of the two-point measurement for estimating the spatial correlation length. Analytic results are confirmed with numerically generated synthetic data and real experimental data obtained with the KSTAR beam emission spectroscopy diagnostic. Our results can be applied to Gaussian-shaped fluctuating signals where a correlation length must be measured with only two measurement points.
description: This paper is submitted to Nuclear Fusion, 13 pages, 15 figures, submitted to Nuclear Fusion
A Space-time Nonlocal Traffic Flow Model: Relaxation Representation and Local Limit
Creators: name: Du, Qiang
name: Huang, Kuang
name: Scott, James
name: Shen, Wen
Publisher: name: arXiv
Year: 2022
Subjects: subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics

description: We propose and study a nonlocal conservation law modelling traffic flow in the existence of inter-vehicle communication. It is assumed that the nonlocal information travels at a finite speed and the model involves a space-time nonlocal integral of weighted traffic density. The well-posedness of the model is established under suitable conditions on the model parameters and by a suitably-defined initial condition. In a special case where the weight kernel in the nonlocal integral is an exponential function, the nonlocal model can be reformulated as a $2\times2$ hyperbolic system with relaxation. With the help of this relaxation representation, we show that the Lighthill-Whitham-Richards model is recovered in the equilibrium approximation limit.
description: 32 pages
Geometry-dependent viscosity reduction in sheared active fluids
Creators: name: Słomka, Jonasz
name: Dunkel, Jörn
Publisher: name: arXiv
Year: 2016
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: We investigate flow pattern formation and viscosity reduction mechanisms in active fluids by studying a generalized Navier-Stokes model that captures the experimentally observed bulk vortex dynamics in microbial suspensions. We present exact analytical solutions including stress-free vortex lattices and introduce a computational framework that allows the efficient treatment of previously intractable higher-order shear boundary conditions. Large-scale parameter scans identify the conditions for spontaneous flow symmetry breaking, geometry-dependent viscosity reduction and negative-viscosity states amenable to energy harvesting in confined suspensions. The theory uses only generic assumptions about the symmetries and long-wavelength structure of active stress tensors, suggesting that inviscid phases may be achievable in a broad class of non-equilibrium fluids by tuning confinement geometry and pattern scale selection.
description: supplementary movies available on request
Rubidium Focused Ion Beam Induced Platinum Deposition
Creators: name: Li, Yang
name: Xu, Sheng
name: Sezen, Meltem
name: Misirlioglu, Feray Bakan
name: Vredenbregt, Edgar
Publisher: name: arXiv
Year: 2022
Subjects: subject: Applied Physics (physics.app-ph)
subject: FOS: Physical sciences

description: This work presents characterization of focused ion beam induced deposition (FIBID) of platinum using both rubidium and gallium ions. Under similar beam energies, 8.5 keV for Rb$^+$ and 8.0 keV for Ga$^+$, and beam current near 10 pA, the two ion species deposited Pt films at similar rates. Energy-dispersive x-ray spectroscopy shows that the Rb$^+$ FIBID-Pt consists of similar Pt contents with much lower primary ion contents (5% Rb and 27% Ga) than the Ga$^+$ FIBID-Pt. The deposited material was also measured to have a resistivity of $8.1\times 10^4$ $\mathrm{μΩ\cdot cm}$ for the Rb$^+$ FIBID-Pt and $5.7\times 10^3$ $\mathrm{μΩ\cdot cm}$ for the Ga$^+$ FIBID-Pt.
description: 5 pages, 5 figures
Engineering the Frequency Spectrum of Bright Squeezed Vacuum via Group Velocity Dispersion in an SU(1,1) Interferometer
Creators: name: Lemieux, Samuel
name: Manceau, Mathieu
name: Sharapova, Polina R.
name: Tikhonova, Olga V.
name: Boyd, Robert W.
name: Leuchs, Gerd
name: Chekhova, Maria V.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Bright squeezed vacuum, a promising tool for quantum information, can be generated by high-gain parametric down-conversion. However, its frequency and angular spectra are typically quite broad, which is undesirable for applications requiring single-mode radiation. We tailor the frequency spectrum of high-gain parametric down-conversion using an SU(1,1) interferometer consisting of two nonlinear crystals with a dispersive medium separating them. The dispersive medium allows us to select a narrow band of the frequency spectrum to be exponentially amplified by high-gain parametric amplification. The frequency spectrum is thereby narrowed from (56.5 +- 0.1) to (1.22 +- 0.02) THz and, in doing so, the number of frequency modes is reduced from approximately 50 to 1.82 +- 0.02. Moreover, this method provides control and flexibility over the spectrum of the generated light through the timing of the pump.
description: 6 pages, 5 figures
Modular Hamiltonian of the scalar field in the semi infinite line: dimensional reduction for spherically symmetric regions
Creators: name: Huerta, Marina
name: van der Velde, Guido
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We focus our attention on the one dimensional scalar theories that result from dimensionally reducing the free scalar field theory in arbitrary d dimensions. As is well known, after integrating out the angular coordinates, the free scalar theory can be expressed as an infinite sum of theories living in the semi-infinite line, labeled by the angular modes $\{l, \vec{m}\}$. We show that their modular Hamiltonian in an interval attached to the origin is, in turn, the one obtained from the dimensional reduction of the modular Hamiltonian of the conformal parent theory in a sphere. Remarkably, this is a local expression in the energy density, as happens in the conformal case, although the resulting one dimensional theories are clearly not conformal. We support this result by analyzing the symmetries of these theories, which turn out to be a portion of the original conformal group, and proving that the reduced modular Hamiltonian is in fact the operator generating the modular flow in the interval. By studying the spectrum of these modular Hamiltonians, we also provide an analytic expression for the associated entanglement entropy. Finally, extending the radial regularization scheme originally introduced by Srednicki, we sum over the angular modes to successfully recover the conformal anomaly in the entropy logarithmic coefficient in even dimensions, as well as the universal constant $F$ term in $d = 3$.
description: 21 pages, 4 figures, v2: reference added and v3: corrected typo in eq.(77)
Second order time dependent tangent bundles and their applications
Creators: name: Suri, Ali
Publisher: name: arXiv
Year: 2016
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 58B20, 58A05

description: The aim of this paper is to geometrize time dependent Lagrangian mechanics in a way that the framework of second order tangent bundles plays an essential role. To this end, we first introduce the concepts of time dependent connections and time dependent semisprays on a manifold $M$ and their induced vector bundle structures on the second order time dependent tangent bundle $\R\times T^2M$. Then we turn our attention to regular time Lagrangians and their interaction with $\R\times T^2M$ in different situations such as mechanical systems with potential fields, external forces and holonomic constraints. Finally we propose an examples to support our theory.
Mapping smallholder cashew plantations to inform sustainable tree crop expansion in Benin
Creators: name: Yin, Leikun
name: Ghosh, Rahul
name: Lin, Chenxi
name: Hale, David
name: Weigl, Christoph
name: Obarowski, James
name: Zhou, Junxiong
name: Till, Jessica
name: Jia, Xiaowei
name: Mao, Troy
name: Kumar, Vipin
name: Jin, Zhenong
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Machine Learning (cs.LG)
subject: Applications (stat.AP)
subject: FOS: Computer and information sciences

description: Cashews are grown by over 3 million smallholders in more than 40 countries worldwide as a principal source of income. As the third largest cashew producer in Africa, Benin has nearly 200,000 smallholder cashew growers contributing 15% of the country's national export earnings. However, a lack of information on where and how cashew trees grow across the country hinders decision-making that could support increased cashew production and poverty alleviation. By leveraging 2.4-m Planet Basemaps and 0.5-m aerial imagery, newly developed deep learning algorithms, and large-scale ground truth datasets, we successfully produced the first national map of cashew in Benin and characterized the expansion of cashew plantations between 2015 and 2021. In particular, we developed a SpatioTemporal Classification with Attention (STCA) model to map the distribution of cashew plantations, which can fully capture texture information from discriminative time steps during a growing season. We further developed a Clustering Augmented Self-supervised Temporal Classification (CASTC) model to distinguish high-density versus low-density cashew plantations by automatic feature extraction and optimized clustering. Results show that the STCA model has an overall accuracy over 85% and the CASTC model achieved an overall accuracy of 76%. We found that the cashew area in Benin almost doubled from 2015 to 2021 with 60% of new plantation development coming from cropland or fallow land, while encroachment of cashew plantations into protected areas has increased by 55%. Only half of cashew plantations were high-density in 2021, suggesting high potential for intensification. Our study illustrates the power of combining high-resolution remote sensing imagery and state-of-the-art deep learning algorithms to better understand tree crops in the heterogeneous smallholder landscape.
Holography of information in massive gravity using Dirac brackets
Creators: name: Chakravarty, Joydeep
name: Jain, Diksha
name: Sivakumar, Akhil
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The principle of holography of information states that in massless gravity, it is possible to extract bulk information using asymptotic boundary operators. In our work, we study this principle in a linearized setting about empty flat space and formulate it using Dirac brackets between boundary Hamiltonian and bulk operators. We then address whether the storage of bulk information in flat space linearized massive gravity resembles that of massless gravity. For linearized massless gravity, using Dirac brackets, we recover the necessary criteria for the holography of information. In contrast, we show that the Dirac bracket of the relevant boundary observable with bulk operators vanishes for massive gravity. We use this important distinction to outline the canonical Hilbert space. This leads to split states, and consequently, one cannot use asymptotic boundary observables to extract bulk information in massive gravity. We also argue the split property directly without an explicit reference to the Hilbert space. The result reflects that we can construct local bulk operators in massive gravity, which are obscured from boundary observables due to the lack of diffeomorphism invariance. Our analysis sheds some light on evaporating black holes in the context of the islands proposal.
description: 23 pages + Appendices. Version published in JHEP
Formation of metastable phases by spinodal decomposition
Creators: name: Alert, Ricard
name: Tierno, Pietro
name: Casademunt, Jaume
Publisher: name: arXiv
Year: 2016
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Metastable phases may be spontaneously formed from other metastable phases through nucleation. Here we demonstrate the spontaneous formation of a metastable phase from an unstable equilibrium by spinodal decomposition, which leads to a transient coexistence of stable and metastable phases. This phenomenon is generic within the recently introduced scenario of the landscape-inversion phase transitions, which we experimentally realize as a structural transition in a colloidal crystal. This transition exhibits a rich repertoire of new phase-ordering phenomena, including the coexistence of two equilibrium phases connected by two physically different interfaces. In addition, this scenario enables the control of sizes and lifetimes of metastable domains. Our findings open a new setting that broadens the fundamental understanding of phase-ordering kinetics, and yield new prospects of applications in materials science.
Threshold effects in high-energy vortex state collisions
Creators: name: Liu, Bei
name: Ivanov, Igor P.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Collisions of particles prepared in non--plane-wave states with a non-trivial phase structure, such as vortex states carrying an adjustable orbital angular momentum (OAM), open novel opportunities in atomic, nuclear, and high-energy physics unavailable for traditional scattering experiments. Recently, it was argued that photoinduced processes such as $γd \to pn$ and $γp \to Δ^+$ initiated by a high-energy vortex photon should display a remarkable threshold shift and a sizable cross section enhancement as the impact parameter $b$ of the target hadron with respect to the vortex photon axis goes to zero. In this work, we theoretically explore whether this effect exists within the quantum-field-theoretic treatment of the scattering process. We do not rely on the semiclassical assumption of pointlike, non-spreading target particle and, instead, consider the toy process of heavy particle pair production in collision of two light particles prepared as a Laguerre-Gaussian and a compact Gaussian wave packets, paying special attention to the threshold behavior of the cross section. We do observe threshold smearing due to non-monochromaticity of the wave packets, but we do not confirm the near-threshold enhancement. Instead we find an OAM-related dip at $b\to 0$ as compared with the two Gaussian wave packet collision.
description: 17 pages, 6 figures; v2: clarifications added, matches the published version
Twin-field quantum key distribution without phase locking
Creators: name: Li, Wei
name: Zhang, Likang
name: Lu, Yichen
name: Li, Zheng-Ping
name: Jiang, Cong
name: Liu, Yang
name: Huang, Jia
name: Li, Hao
name: Wang, Zhen
name: Wang, Xiang-Bin
name: Zhang, Qiang
name: You, Lixing
name: Xu, Feihu
name: Pan, Jian-Wei
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Twin-field quantum key distribution (TF-QKD) has emerged as a promising solution for practical quantum communication over long-haul fiber. However, previous demonstrations on TF-QKD require the phase locking technique to coherently control the twin light fields, inevitably complicating the system with extra fiber channels and peripheral hardware. Here we propose and demonstrate an approach to recover the single-photon interference pattern and realize TF-QKD \emph{without} phase locking. Our approach separates the communication time into reference frames and quantum frames, where the reference frames serve as a flexible scheme for establishing the global phase reference. To do so, we develop a tailored algorithm based on fast Fourier transform to efficiently reconcile the phase reference via data post-processing. We demonstrate no-phase-locking TF-QKD from short to long distances over standard optical fibers. At 50-km standard fiber, we produce a high secret key rate (SKR) of 1.27 Mbit/s, while at 504-km standard fiber, we obtain the repeater-like key rate scaling with a SKR of 34 times higher than the repeaterless secret key capacity. Our work provides a scalable and practical solution to TF-QKD, thus representing an important step towards its wide applications.
description: Published version
Enhancing Perovskite Electrocatalysis through Strain Tuning of the Oxygen Deficiency
Creators: name: Petrie, Jonathan R.
name: Jeen, Hyoungjeen
name: Barron, Sara C.
name: Meyer, Tricia L.
name: Lee, Ho Nyung
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Oxygen vacancies in transition metal oxides facilitate catalysis critical for energy storage and generation. However, it has proven elusive to promote vacancies at the lower temperatures required for operation in devices such as metal-air batteries and portable fuel cells. Here, we use thin films of the perovskite-based strontium cobaltite (SrCoOx) to show that epitaxial strain is a powerful tool towards manipulating the oxygen content under conditions consistent with the oxygen evolution reaction, yielding increasingly oxygen deficient states in an environment where the cobaltite would normally be fully oxidized. The additional oxygen vacancies created through tensile strain enhance the cobaltite catalytic activity towards this important reaction by over an order of magnitude, equaling that of precious metal catalysts, including IrO2. Our findings demonstrate that strain in these oxides can dictate oxygen stoichiometry independent of ambient conditions, allowing unprecedented control over oxygen vacancies essential in catalysis near room temperature.
Recollapsing spacetimes with $Λ<0$
Creators: name: Fajman, David
name: Kraft, Maximilian
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We show that any homogeneous initial data set with $Λ<0$ on a product 3-manifold of the orthogonal form $(F\times \mathbb S^1,a_0^2dz^2+b_0^2σ^2,c_0dz^2+d_0σ)$, where $(F,σ)$ is a closed 2-surface of constant curvature and $a_0,..., d_0$ are suitable constants, recollapses under the Einstein-flow with a negative cosmological constant and forms crushing singularities at the big bang and the big crunch, respectively. Towards certain singularities among those the Kretschmann scalar remains bounded, hence these are not curvature singularities. We then show that the presence of a massless scalar field causes the Kretschmann scalar to blow-up towards both ends of spacetime for all solutions in the corresponding class. By standard arguments this recollapsing behaviour extends to an open neighborhood in the set of initial data sets and is in this sense generic close to the homogeneous regime.
description: 28 pages, 3 figures
Quiver diagonalization and open BPS states
Creators: name: Jankowski, Jakub
name: Kucharski, Piotr
name: Larraguível, Hélder
name: Noshchenko, Dmitry
name: Sułkowski, Piotr
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Quantum Algebra (math.QA)
subject: Representation Theory (math.RT)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We show that motivic Donaldson-Thomas invariants of a~symmetric quiver $Q$, captured by the generating function $P_Q$, can be encoded in another quiver $Q^{(\infty)}$ of (almost always) infinite size, whose only arrows are loops, and whose generating function $P_{Q^{(\infty)}}$ is equal to $P_Q$ upon appropriate identification of generating parameters. Consequences of this statement include a generalization of the proof of integrality of Donaldson-Thomas and Labastida-Mariño-Ooguri-Vafa invariants that count open BPS states, as well as expressing motivic Donaldson-Thomas invariants of an arbitrary symmetric quiver in terms of invariants of $m$-loop quivers. In particular, this means that the already known combinatorial interpretation of invariants of $m$-loop quivers extends to arbitrary symmetric quivers.
description: 37 pages
IIB Explored: Reflection 7-Branes
Creators: name: Dierigl, Markus
name: Heckman, Jonathan J.
name: Montero, Miguel
name: Torres, Ethan
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The Swampland Cobordism Conjecture successfully predicts the supersymmetric spectrum of 7-branes of IIB / F-theory. Including reflections on the F-theory torus, it also predicts the existence of new non-supersymmetric objects, which we dub reflection 7-branes (R7-branes). We present evidence that these R7-branes only exist at strong coupling. R7-branes serve as end of the world branes for 9D theories obtained from type IIB asymmetric orbifold and Dabholkar-Park orientifold backgrounds, and an anomaly inflow analysis suggests the existence of a gapless Weyl fermion, which would have the quantum numbers of a goldstino. Using general arguments, we conclude that different kinds of branes are able to end on the R7, and accounting for their charge requires exotic localized degrees of freedom, for which the simplest possibility is a massless 3-form field on the R7-brane worldvolume. We also show how to generalize the standard F-theory formalism to account for reflections.
description: v2: 45 pages, 3 figures, typos corrected, reference added
Geometric quantum discord and coherence in a dipolar interacting magnetic system
Creators: name: Cruz, Clebson
name: Anka, Maron F.
name: Rastegar-Sedehi, Hamid-Reza
name: Castro, Cleidson
Publisher: name: arXiv
Year: 2023
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The study of low-dimensional metal complexes has revealed fascinating characteristics regarding the ground-state crossover shown by spin-gaped systems. In this context, this work explores the effect of the quantum-level crossing, induced by the magnetic anisotropies of dipolar interacting systems, on the quantum discord and coherence of the system. The analytical expressions for the quantum discord, based on Schatten 1-norm, and the $l_1$ trace-norm quantum coherence for dinuclear spin-1/2 systems, are provided in terms of the magnetic anisotropies. The results show that, while the quantum discord has a clear signature of the quantum level-crossing, the basis dependence of the quantum coherence hides the crossover regarding the measured basis. In addition, the global quantum coherence is wholly stored within the correlations of the system, regardless of its reference basis.
GRB Observational Properties
Creators: name: Zhang, Bing
name: Lü, Hou-Jun
name: Liang, En-Wei
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We summarize basic observational properties of gamma-ray bursts (GRBs), including prompt emission properties, afterglow properties, and classification schemes. We also briefly comment on the current physical understanding of these properties.
description: 36 pages, 6 figures. To be published in Space Science Review and Chapter 1 of ISSI-Beijing book "Gamma-ray bursts: a tool to explore the young universe"
Multiple injections of energetic electrons associated with the flare/CME event on 9 October 2021
Creators: name: Jebaraj, Immanuel Christopher
name: Kouloumvakos, Athanasios
name: Dresing, Nina
name: Warmuth, Alexander
name: Wijsen, Nicolas
name: Palmroos, Christian
name: Gieseler, Jan
name: Vainio, Rami
name: Krupar, Vratislav
name: Magdalenic, Jasmina
name: Wiegelmann, Thomas
name: Schuller, Frederic
name: Battaglia, Andrea
name: Fedeli, Annamaria
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: We study the solar energetic particle (SEP) event observed on 9 October 2021, by multiple spacecraft including Solar Orbiter (SolO). The event was associated with an M1.6 flare, a coronal mass ejection (CME) and a shock wave. During the event, high-energy protons and electrons were recorded by multiple instruments located within a narrow longitudinal cone. An interesting aspect of the event was the multi-stage particle energization during the flare impulsive phase and also what appears to be a separate phase of electron acceleration detected at SolO after the flare maximum. We aim to investigate and identify the multiple sources of energetic electron acceleration. We utilize SEP electron observations from the Energetic Particle Detector (EPD) and hard X-ray (HXR) observations from the Spectrometer/Telescope for Imaging X-rays (STIX) on-board SolO, in combination with radio observations at a broad frequency range. We focus on establishing an association between the energetic electrons and the different HXR and radio emissions associated with the multiple acceleration episodes. We have found that the flare was able to accelerate electrons for at least 20 minutes during the nonthermal phase observed in the form of five discrete HXR pulses. We also show evidence that the shock wave has contributed to the electron acceleration during and after the impulsive flare phase. The detailed analysis of EPD electron data shows that there was a time difference in the release of low- and high-energy electrons, with the high-energy release delayed. Also, the observed electron anisotropy characteristics suggest different connectivity during the two phases of acceleration.
description: 17 pages, 10 figures (main text). 3 pages, 3 figures (appendix). In review