cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Effective Evaluation using Logged Bandit Feedback from Multiple Loggers
Creators: name: Agarwal, Aman
name: Basu, Soumya
name: Schnabel, Tobias
name: Joachims, Thorsten
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: Accurately evaluating new policies (e.g. ad-placement models, ranking functions, recommendation functions) is one of the key prerequisites for improving interactive systems. While the conventional approach to evaluation relies on online A/B tests, recent work has shown that counterfactual estimators can provide an inexpensive and fast alternative, since they can be applied offline using log data that was collected from a different policy fielded in the past. In this paper, we address the question of how to estimate the performance of a new target policy when we have log data from multiple historic policies. This question is of great relevance in practice, since policies get updated frequently in most online systems. We show that naively combining data from multiple logging policies can be highly suboptimal. In particular, we find that the standard Inverse Propensity Score (IPS) estimator suffers especially when logging and target policies diverge -- to a point where throwing away data improves the variance of the estimator. We therefore propose two alternative estimators which we characterize theoretically and compare experimentally. We find that the new estimators can provide substantially improved estimation accuracy.
description: KDD 2018
Multidimensional Rational Covariance Extension with Approximate Covariance Matching
Creators: name: Ringh, Axel
name: Karlsson, Johan
name: Lindquist, Anders
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optimization and Control (math.OC)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 42A70, 30E05, 49N45, 90C25, 62M15, 74E25

description: In our companion paper "Multidimensional rational covariance extension with applications to spectral estimation and image compression" we discussed the multidimensional rational covariance extension problem (RCEP), which has important applications in image processing, and spectral estimation in radar, sonar, and medical imaging. This is an inverse problem where a power spectrum with a rational absolutely continuous part is reconstructed from a finite set of moments. However, in most applications these moments are determined from observed data and are therefore only approximate, and RCEP may not have a solution. In this paper we extend the results to handle approximate covariance matching. We consider two problems, one with a soft constraint and the other one with a hard constraint, and show that they are connected via a homeomorphism. We also demonstrate that the problems are well-posed and illustrate the theory by examples in spectral estimation and texture generation.
description: 31 pages (single column). Revision: minor corrections
Dark Photons from Captured Inelastic Dark Matter Annihilation: Charged Particle Signatures
Creators: name: Smolinsky, Jordan
name: Tanedo, Philip
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The dark sector may contain a dark photon that kinetically mixes with the Standard Model photon, allowing dark matter to interact weakly with normal matter. In previous work we analyzed the implications of this scenario for dark matter capture by the Sun. Dark matter will gather in the core of the Sun and annihilate to dark photons. These dark photons travel outwards from the center of the Sun and may decay to produce positrons that can be detected by the Alpha Magnetic Spectrometer (AMS-02) on the ISS. We found that the dark photon parameter space accessible to this analysis is largely constrained by strong limits on the spin-independent WIMP-nucleon cross section from direct detection experiments. In this paper we build upon previous work by considering the case where the dark sector contains two species of Dirac fermion that are nearly degenerate in mass and couple inelastically to the dark photon. We find that for small values of the mass splitting $Δ\sim 100 ~\text{keV}$, the predicted positron signal at AMS-02 remains largely unchanged from the previously considered elastic case while constraints from direct detection are relaxed, leaving a region of parameter space with dark matter mass $100 ~\text{GeV} \lesssim m_X \lesssim 10 ~\text{TeV}$, dark photon mass $1 ~\text{MeV} \lesssim m_{A'} \lesssim 100 ~\text{MeV}$, and kinetic mixing parameter $10^{-9} \lesssim \varepsilon \lesssim 10^{-8}$ that is untouched by supernova observations and fixed target experiments but where an inelastic dark sector may still be discovered using existing AMS-02 data.
description: 18 pages, 5 figures; v2: minor revisions to match published version; v3: updated direct detection and CMB constraints and corrected decay length in code, moving the region of experimental sensitivity to values of epsilon that are lower by an order of magnitude
Mesoscopic quantum superpositions in bimodal Bose-Einstein condensates: decoherence and strategies to counteract it
Creators: name: Pawlowski, Krzysztof
name: Fadel, Matteo
name: Treutlein, Philipp
name: Castin, Yvan
name: Sinatra, Alice
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We study theoretically the interaction-induced generation of mesoscopic coherent spin state superpositions (small cat states) from an initial coherent spin state in bimodal Bose-Einstein condensates and the subsequent phase revival, including decoherence due to particle losses and fluctuations of the total particle number. In a full multimode description, we propose a preparation procedure of the initial coherent spin state and we study the effect of preexisting thermal fluctuations on the phase revival, and on the spin and orbito-spinorial cat fidelities.
description: 26 pages, 12 figures; published version
Non-local thermodynamic equilibrium stellar spectroscopy with 1D and <3D> models - I. Methods and application to magnesium abundances in standard stars
Creators: name: Bergemann, Maria
name: Collet, Remo
name: Amarsi, Anish M.
name: Kovalev, Mikhail
name: Ruchti, Gregory
name: Magic, Zazralt
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We determine Mg abundances in 6 Gaia benchmark stars using theoretical one-dimensional (1D) hydrostatic model atmospheres, as well as temporally- and spatially-averaged 3D model atmospheres (<3D>). The stars cover a range of Teff from 4700 to 6500 K, log g from 1.6 to 4.4 dex, and [Fe/H] from -3.0 dex to solar. Spectrum synthesis calculations are performed in local thermodynamic equilibrium (LTE) and in non-LTE (NLTE) using the oscillator strengths recently published by Pehlivan Rhodin et al. We find that: a) Mg abundances determined from the infrared spectra are as accurate as the optical diagnostics, b) the NLTE effects on Mg I line strengths and abundances in this sample of stars are minor (although for a few Mg I lines the NLTE effects on abundance exceed 0.6 dex in <3D> and 0.1 dex in 1D, c) the solar Mg abundance is 7.56 +/- 0.05 dex (total error), in the excellent agreement with the Mg abundance measured in CI chondritic meteorites, d) the 1D NLTE and <3D> NLTE approach can be used with confidence to analyse optical Mg I lines in spectra of dwarfs and sub-giants, but for red giants the Mg I 5711 A line should be preferred, e) low-excitation Mg I lines are sensitive to the atmospheric structure; for these lines, LTE calculations with <3D> models lead to significant systematic abundance errors. The methods developed in this work will be used to study Mg abundances of a large sample of stars in the next paper in the series.
description: 25 pages, accepted for publication in ApJ
Structure, Kinematics, and Observability of the Large Magellanic Cloud's Dynamical Friction Wake in Cold vs. Fuzzy Dark Matter
Creators: name: Foote, Hayden R.
name: Besla, Gurtina
name: Mocz, Philip
name: Garavito-Camargo, Nicolás
name: Lancaster, Lachlan
name: Sparre, Martin
name: Cunningham, Emily C.
name: Vogelsberger, Mark
name: Gómez, Facundo A.
name: Laporte, Chervin F. P.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The Large Magellanic Cloud (LMC) will induce a dynamical friction (DF) wake on infall to the Milky Way (MW). The MW's stellar halo will respond to the gravity of the LMC and the dark matter (DM) wake, forming a stellar counterpart to the DM wake. This provides a novel opportunity to constrain the properties of the DM particle. We present a suite of high-resolution, windtunnel-style simulations of the LMC's DF wake that compare the structure, kinematics, and stellar tracer response of the DM wake in cold DM (CDM), with and without self-gravity, vs. fuzzy DM (FDM) with $m_a = 10^{-23}$ eV. We conclude that the self-gravity of the DM wake cannot be ignored. Its inclusion raises the wake's density by $\sim 10\%$, and holds the wake together over larger distances ($\sim$ 50 kpc) than if self-gravity is ignored. The DM wake's mass is comparable to the LMC's infall mass, meaning the DM wake is a significant perturber to the dynamics of MW halo tracers. An FDM wake is more granular in structure and is $\sim 20\%$ dynamically colder than a CDM wake, but with comparable density. The granularity of an FDM wake increases the stars' kinematic response at the percent level compared to CDM, providing a possible avenue of distinguishing a CDM vs. FDM wake. This underscores the need for kinematic measurements of stars in the stellar halo at distances of 70-100 kpc.
description: 38 pages, 31 figures. Updated to published version
Electron Electric Dipole Moment in Mirror Fermion Model with Electroweak Scale Non-sterile Right-handed Neutrinos
Creators: name: Chang, Chia-Feng
name: Hung, P. Q.
name: Nugroho, Chrisna Setyo
name: Tran, Van Que
name: Yuan, Tzu-Chiang
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The electric dipole moment of the electron is studied in detail in an extended mirror fermion model with the following unique features of (a) right-handed neutrinos are non-sterile and have masses at the electroweak scale, and (b) a horizontal symmetry of the tetrahedral group is used in the lepton and scalar sectors. We study the constraint on the parameter space of the model imposed by the latest ACME experimental limit on electron electric dipole moment. Other low energy experimental observables such as the anomalous magnetic dipole moment of the muon, charged lepton flavor violating processes like muon decays into electron plus photon and muon-to-electron conversion in titanium, gold and lead are also considered in our analysis for comparison. In addition to the well-known CP violating Dirac and Majorana phases in the neutrino mixing matrix, the dependence of additional phases of the new Yukawa couplings in the model is studied in detail for all these low energy observables.
description: 27 pages, 6 figures, 1 table, and 1 appendix. Version to appear in NPB
On the Table of Marks of a Direct Product of Finite Groups
Creators: name: Masterson, Brendan
name: Pfeiffer, Götz
Publisher: name: arXiv
Year: 2017
Subjects: subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 19A22, 06A11

description: We present a method for computing the table of marks of a direct product of finite groups. In contrast to the character table of a direct product of two finite groups, its table of marks is not simply the Kronecker product of the tables of marks of the two groups. Based on a decomposition of the inclusion order on the subgroup lattice of a direct product as a relation product of three smaller partial orders, we describe the table of marks of the direct product essentially as a matrix product of three class incidence matrices. Each of these matrices is in turn described as a sparse block diagonal matrix. As an application, we use a variant of this matrix product to construct a ghost ring and a mark homomorphism for the rational double Burnside algebra of the symmetric group~$S_3$.
description: 28 pages; added references
Lepton-flavor universality violation in $R_K$ and $R_{D^{(*)}}$ from warped space
Creators: name: Megias, Eugenio
name: Quiros, Mariano
name: Salas, Lindber
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Some anomalies in the processes $b\to s\ell\ell$ ($\ell=μ,e$) and $b\to c \ell\barν_\ell$ ($\ell=τ,μ,e$), in particular in the observables $R_K$ and $R_{D^{(\ast)}}$, have been found by the BaBar, LHCb and Belle Collaborations, leading to a possible lepton flavor universality violation. If these anomalies were confirmed they would inevitably lead to physics beyond the Standard Model. In this paper we try to accommodate the present anomalies in an extra dimensional theory, solving the naturalness problem of the Standard Model by means of a warped metric with a strong conformality violation near the infra-red brane. The $R_K$ anomaly can be accommodated provided that the left-handed bottom quark and muon lepton have some degree of compositeness in the dual theory. The theory is consistent with all electroweak and flavor observables, and with all direct searches of Kaluza-Klein electroweak gauge bosons and gluons. The fermion spectrum, and fermion mixing angles, can be reproduced by mostly elementary right-handed bottom quarks, and tau and muon leptons. Moreover the $R_{D^{(\ast)}}$ anomaly requires a strong degree of compositeness for the left-handed tau leptons, which turns out to be in tension with experimental data on the $g_{τ_L}^Z$ coupling, possibly unless some degree of fine-tuning is introduced in the fixing of the CKM matrix.
description: 40 pages, 20 figures; v2: Extended version with analyses of non-observation of FUV in the mu/e sector, LFU tests in tau decays, B->K nu nu and B->K tau tau; v3: Revised version where radiative corrections to observables $\tau\to\ell \nu\nu$ and the $Z\bar\ell\ell$ couplings ($\ell=\tau,\mu$), as well as the LHC dilepton resonance from bottom-bottom fusion, are considered. Some conclusions changed
Linear feedback stabilization of a dispersively monitored qubit
Creators: name: Patti, Taylor Lee
name: Chantasri, Areeya
name: García-Pintos, Luis Pedro
name: Jordan, Andrew N.
name: Dressel, Justin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record for dispersive energy measurements directly back into a coherent Rabi drive amplitude. Such feedback turns the competition cooperative, and effectively stabilizes the qubit state near a target state. We derive the conditions for obtaining such dispersive state stabilization and verify the stabilization conditions numerically. We include common experimental nonidealities, such as energy decay, environmental dephasing, detector efficiency, and feedback delay, and show that the feedback delay has the most significant negative effect on the feedback protocol. Setting the measurement collapse timescale to be long compared to the feedback delay yields the best stabilization.
description: 16 pages, 7 figures
Decay of correlations, quantitative recurrence and logarithm law for contracting Lorenz attractors
Creators: name: Galatolo, Stefano
name: Nisoli, Isaia
name: Pacifico, Maria José
Publisher: name: arXiv
Year: 2017
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37C10, 37C45 (Primary), 37C40, 37D25 (secondary)

description: In this paper we prove that a class of skew products maps with non uniformly hyperbolic base has exponential decay of correlations. We apply this to obtain a logarithm law for the hitting time associated to a contracting Lorenz attractor at all the points having a well defined local dimension, and a quantitative recurrence estimation.
description: 23 pages, 3 figures
OrthoBoXY: A Simple Way to Compute True Self-Diffusion Coefficients from MD Simulations with Periodic Boundary Conditions Without Prior Knowledge of the Viscosity
Creators: name: Busch, Johanna
name: Paschek, Dietmar
Publisher: name: arXiv
Year: 2023
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Recently, an analytical expression for the system size dependence and direction-dependence of self-diffusion coefficients for neat liquids due to hydrodynamic interactions has been derived for molecular dynamics (MD) simulations using orthorhombic unit cells. Based on this description, we show that for systems with a "magic" box length ratio of $L_z/L_x\!=\!L_z/L_y\!=\!2.7933596497$ the computed self-diffusion coefficients $D_x$ and $D_y$ in $x$- and $y$-direction become system-size independent and represent the true self-diffusion coefficient $D_0\!=\!(D_x+D_y)/2$. Moreover, by using this particular box geometry, the viscosity can be determined with a reasonable degree of accuracy from the difference of components of the diffusion coefficients in $x$-,$y$- and $z$-direction using the simple expression $η\!=\!k_\mathrm{B}T\cdot 8.1711245653/[3πL_z(D_{x}+D_{y}-2D_z)]$, where $k_\mathrm{B}$ denotes Boltzmann's constant, and $T$ represents the temperature. MD simulations of TIP4P/2005 water for various system-sizes using both orthorhombic and cubic box geometries are used to test the approach.
description: 5 pages, 1 figure, 2 tables
Gauged Floreanini-Jackiw type chiral boson and its BRST quantization
Creators: name: Rahaman, Anisur
name: Yasmin, Safia
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The gauged model of Siegel type chiral boson is considered. It has been shown that the action of gauged model of Floreanini-Jackiw (FJ) type chiral boson is contained in it in an interesting manner. A BRST invariant action corresponding to the action of gauged FJ type chiral boson has been formulated using Batalin, Fradkin and Vilkovisky based improved Fujiwara, Igarishi and Kubo (FIK) formalism. An alternative quantization of the gauge symmetric action has been made with a Lorentz gauge and an attempt has been made to establish the equivalence between the gauge symmetric version of the extended phase space and original gauge non-invariant version of the usual phase space.
description: 13 pages latex, slight changes in references and minor changesin the body
Yay for Determinants!
Creators: name: Amdeberhan, Tewodros
name: Koutschan, Christoph
name: Zeilberger, Doron
Publisher: name: arXiv
Year: 2023
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: In this {\it case study}, we hope to show why Sheldon Axler was not just wrong, but {\em wrong}, when he urged, in 1995: ``Down with Determinants!''. We first recall how determinants are useful in enumerative combinatorics, and then illustrate three versatile tools (Dodgson's condensation, the holonomic ansatz and constant term evaluations) to operate in tandem to prove a certain intriguing determinantal formula conjectured by the first author. We conclude with a postscript describing yet another, much more efficient, method for evaluating determinants: `ask determinant-guru, Christian Krattenthaler', but advise people only to use it as a last resort, since if we would have used this last method right away, we would not have had the fun of doing it all by ourselves.
description: 15 pages; 2 new sections added beyond the first version; dedicated to Christian Krattenthaler on his 65th birthday; this paper appeared (in a revised form) in the journal, SLC (S\'eminaire Lotharingien de Combinatoire), under a new title "A case study in determinant evaluations"; {\tt https://www.mat.univie.ac.at/~slc/wpapers/s89amdkozeil.pdf}
Dolgopyat's method and the fractal uncertainty principle
Creators: name: Dyatlov, Semyon
name: Jin, Long
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Analysis of PDEs (math.AP)
subject: Dynamical Systems (math.DS)
subject: Spectral Theory (math.SP)
subject: Chaotic Dynamics (nlin.CD)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We show a fractal uncertainty principle with exponent $1/2-δ+ε$, $ε>0$, for Ahflors-David regular subsets of $\mathbb R$ of dimension $δ\in (0,1)$. This improves over the volume bound $1/2-δ$, and $ε$ is estimated explicitly in terms of the regularity constant of the set. The proof uses a version of techniques originating in the works of Dolgopyat, Naud, and Stoyanov on spectral radii of transfer operators. Here the group invariance of the set is replaced by its fractal structure. As an application, we quantify the result of Naud on spectral gaps for convex co-compact hyperbolic surfaces and obtain a new spectral gap for open quantum baker maps.
description: 31 pages, 2 figures; revised according to comments of the referee. To appear in Analysis&PDE
HETDEX Public Source Catalog 1 -- Stacking 50K Lyman Alpha Emitters
Creators: name: Davis, Dustin
name: Gebhardt, Karl
name: Cooper, Erin Mentuch
name: Bowman, William P.
name: Castanheira, Barbara Garcia
name: Chisholm, John
name: Ciardullo, Robin
name: Fabricius, Maximilian
name: Farrow, Daniel J.
name: Finkelstein, Steven L.
name: Gronwall, Caryl
name: Gawiser, Eric
name: Hill, Gary J.
name: Hopp, Ulrich
name: House, Lindsay R.
name: Jeong, Donghui
name: Kollatschny, Wolfram
name: Komatsu, Eiichiro
name: Liu, Chenxu
name: Niemeyer, Maja Lujan
name: Saldana-Lopez, Alberto
name: Saito, Shun
name: Schneider, Donald P.
name: Snigula, Jan
name: Tuttle, Sarah
name: Weiss, Laurel H.
name: Wisotzki, Lutz
name: Zeimann, Gregory
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We describe the ensemble properties of the $1.9 < z < 3.5$ Lyman Alpha Emitters (LAEs) found in the HETDEX survey's first public data release, HETDEX Public Source Catalog 1 (Mentuch Cooper et al. 2023). Stacking the low-resolution ($R \sim$ 800) spectra greatly increases the signal-to-noise ratio, revealing spectral features otherwise hidden by noise, and we show that the stacked spectrum is representative of an average member of the set. The flux limited, Ly$α$ signal-to-noise ratio restricted stack of 50K HETDEX LAEs shows the ensemble biweight ``average" $z \sim 2.6$ LAE to be a blue (UV continuum slope $\sim -2.4$ and E(B-V) $< 0.1$), moderately bright (M$_{\text{UV}} \sim -19.7$) star forming galaxy with strong Ly$α$ emission (log $L_{Lyα}$ $\sim$ 42.8 and $W_λ$(Ly$α$) $\sim$ 114Å), and potentially significant leakage of ionizing radiation. The restframe UV light is dominated by a young, metal poor stellar population with an average age 5-15 Myr and metallicity of 0.2-0.3 Z$_{\odot}$.
description: 17 pages, 11 figures, 2 data files (ApJ Accepted)
A Model for the Origin of Bursty Star Formation in Galaxies
Creators: name: Faucher-Giguere, C. -A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We propose a simple analytic model to understand when star formation is time-steady versus bursty in galaxies. Recent models explain the observed Kennicutt-Schmidt relation between star formation rate and gas surface densities in galaxies as resulting from a balance between stellar feedback and gravity. We argue that bursty star formation occurs when such an equilibrium cannot be stably sustained, and identify two regimes in which galaxy-scale star formation should be bursty: i) at high redshift (z>~1) for galaxies of all masses, and ii) at low masses (depending on gas fraction) for galaxies at any redshift. At high redshift, characteristic galactic dynamical timescales become too short for supernova feedback to effectively respond to gravitational collapse in galactic discs (an effect recently identified for galactic nuclei), whereas in dwarf galaxies star formation occurs in too few bright star-forming regions to effectively average out. Burstiness is also enhanced at high redshift owing to elevated gas fractions in the early Universe. Our model can thus explain the bursty star formation rates predicted in these regimes by recent high-resolution galaxy formation simulations, as well as the bursty star formation histories observationally-inferred in both local dwarf and high-redshift galaxies. In our model, bursty star formation is associated with particularly strong spatio-temporal clustering of supernovae. Such clustering can promote the formation of galactic winds and our model may thus also explain the much higher wind mass loading factors inferred in high-redshift massive galaxies relative to their z~0 counterparts.
description: 18 pages, including 9 figures. To appear in MNRAS
Lattice thermal expansion and anisotropic displacements in urea, bromomalonic aldehyde, pentachloropyridine and naphthalene
Creators: name: George, Janine
name: Wang, Ruimin
name: Englert, Ulli
name: Dronskowski, Richard
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Anisotropic displacement parameters (ADPs) are commonly used in crystallography, chemistry and related fields to describe and quantify thermal motion of atoms. Within the very recent years, these ADPs have become predictable by lattice dynamics in combination with first-principles theory. Here, we study four very different molecular crystals, namely urea, bromomalonic aldehyde, pentachloropyridine, and naphthalene, by first-principles theory to assess the quality of ADPs calculated in the quasi-harmonic approximation. In addition, we predict both thermal expansion and thermal motion within the quasi-harmonic approximation and compare the predictions with experimental data. Very reliable ADPs are calculated within the quasi-harmonic approximation for all four cases up to at least 200 K, and they turn out to be in better agreement with experiment than the harmonic ones. In one particular case, ADPs can even reliably be predicted up to room temperature. Our results also hint at the importance of normal-mode anharmonicity in the calculation of ADPs.
Toolbox for the design of $LiNbO_3$-based passive and active integrated quantum circuits
Creators: name: Sharapova, P. R.
name: Luo, K. H.
name: Herrmann, H.
name: Reichelt, M.
name: Meier, T.
name: Silberhorn, C.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present and discuss perspectives of current developments on advanced quantum optical circuits monolithically integrated in the lithium niobate platform. A set of basic components comprising photon pair sources based on parametric down conversion (PDC), passive routing elements and active electro-optically controllable switches and polarisation converters are building blocks of a toolbox which is the basis for a broad range of diverse quantum circuits. We review the state-of-the-art of these components and provide models that properly describe their performance in quantum circuits. As an example for applications of these models we discuss design issues for a circuit providing on-chip two-photon interference. The circuit comprises a PDC section for photon pair generation followed by an actively controllable modified Mach-Zehnder structure for observing Hong-Ou-Mandel (HOM) interference. The performance of such a chip is simulated theoretically by taking even imperfections of the properties of the individual components into account.
On the nature of the generating series of walks in the quarter plane
Creators: name: Dreyfus, Thomas
name: Hardouin, Charlotte
name: Roques, Julien
name: Singer, Michael F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: In the present paper, we introduce a new approach, relying on the Galois theory of difference equations, to study the nature of the generating series of walks in the quarter plane. Using this approach, we are not only able to recover many of the recent results about these series, but also to go beyond them. For instance, we give for the first time hypertranscendency results, {\it i.e.}, we prove that certain of these generating series do not satisfy any nontrivial nonlinear algebraic differential equation with rational coefficients.
description: To appear in Inventiones Mathematicae
Integrals of motion from quantum toroidal algebras
Creators: name: Feigin, B.
name: Jimbo, M.
name: Mukhin, E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Algebra (math.QA)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: We identify the Taylor coefficients of the transfer matrices corresponding to quantum toroidal algebras with the elliptic local and non-local integrals of motion introduced by Kojima, Shiraishi, Watanabe, and one of the authors. That allows us to prove the Litvinov conjectures on the Intermediate Long Wave model. We also discuss the (gl(m),gl(n)) duality of XXZ models in quantum toroidal setting and the implications for the quantum KdV model. In particular, we conjecture that the spectrum of non-local integrals of motion of Bazhanov, Lukyanov, and Zamolodchikov is described by Gaudin Bethe ansatz equations associated to affine sl(2).
description: Latex, 28 pages, minor revision, some misprints corrected
Ionizing spectra of stars that lose their envelope through interaction with a binary companion: role of metallicity
Creators: name: Gotberg, Y.
name: de Mink, S. E.
name: Groh, J. H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Understanding ionizing fluxes of stellar populations is crucial for various astrophysical problems including the epoch of reionization. Massive short-lived Wolf-Rayet stars are generally considered as the main ionizing sources. We examine the role of less massive stars that lose their envelope through interaction with a companion. We use the evolutionary code MESA and the radiative transfer code CMFGEN to investigate stripped stars as a function of metallicity (Z). We show that typical progenitors, initially 12$M_{\odot}$, produce hot and compact stars (~4$M_{\odot}$, 60-80 kK, ~1$R_{\odot}$) that copiously produce ionizing photons, emitting 60-85% and 30-60% of their energy as HI and HeI ionizing radiation, for Z=0.0001-0.02. This is comparable to a typical massive Wolf-Rayet star, when accounting for their longer lifetimes and the favoring initial mass function. Stripped stars further emit their ionizing photons with a delay (~20Myrs after star formation for this progenitor), allowing time for stellar feedback to disperse the birth clouds. This increases the fraction that can escape and contribute to ionization of the intergalactic medium. We further find that Roche stripping fails to fully remove the H-rich envelope at low Z. This questions the common treatment of stripped stars in rapid population synthesis simulations as pure helium stars. We expect implications for the rate of type Ib/c supernova at low Z and for the advanced evolutionary channels for type Ia supernova and gravitational wave sources. We discuss how the characteristic spectral features of stripped stars can be used to increase the observed sample, which is urgently needed to test the models.
Giant non-volatile electric field control of proximity induced magnetism in the spin-orbit semimetal SrIrO3
Creators: name: Jaiswal, Arun Kumar
name: Eder, Robert
name: Wang, Di
name: Wollersen, Vanessa
name: Tacon, Matthieu Le
name: Fuchs, Dirk
Publisher: name: arXiv
Year: 2023
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: With its potential for drastically reduced operation power of information processing devices, electric field control of magnetism has generated huge research interest. Recently, novel perspectives offered by the inherently large spin-orbit coupling of 5d transition metals have emerged. Here, we demonstrate non-volatile electrical control of the proximity induced magnetism in SrIrO3 based back-gated heterostructures. We report up to a 700 % variation of the anomalous Hall conductivity σ_AHE and Hall angle θ_AHE as function of the applied gate voltage Vg. In contrast, the Curie temperature TC = 100K and magnetic anisotropy of the system remain essentially unaffected by Vg indicating a robust ferromagnetic state in SrIrO3 which strongly hints to gating-induced changes of the anomalous Berry curvature. The electric-field induced ferroelectric-like state of SrTiO3 enables non-volatile switching behavior of σ_AHE and θ_AHE below 60 K. The large tunability of this system, opens new avenues towards efficient electric-field manipulation of magnetism.
description: 13 pages, 5 figures, to be published in Advanced Functional Materials
Hybrid stochastic-deterministic calculation of the second-order perturbative contribution of multireference perturbation theory
Creators: name: Garniron, Yann
name: Scemama, Anthony
name: Loos, Pierre-François
name: Caffarel, Michel
Publisher: name: arXiv
Year: 2017
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: A hybrid stochastic-deterministic approach for computing the second-order perturbative contribution $E^{(2)}$ within multireference perturbation theory (MRPT) is presented. The idea at the heart of our hybrid scheme --- based on a reformulation of $E^{(2)}$ as a sum of elementary contributions associated with each determinant of the MR wave function --- is to split $E^{(2)}$ into a stochastic and a deterministic part. During the simulation, the stochastic part is gradually reduced by dynamically increasing the deterministic part until one reaches the desired accuracy. In sharp contrast with a purely stochastic MC scheme where the error decreases indefinitely as $t^{-1/2}$ (where $t$ is the computational time), the statistical error in our hybrid algorithm displays a polynomial decay $\sim t^{-n}$ with $n=3-4$ in the examples considered here. If desired, the calculation can be carried on until the stochastic part entirely vanishes. In that case, the exact result is obtained with no error bar and no noticeable computational overhead compared to the fully-deterministic calculation. The method is illustrated on the F$_2$ and Cr$_2$ molecules. Even for the largest case corresponding to the Cr$_2$ molecule treated with the cc-pVQZ basis set, very accurate results are obtained for $E^{(2)}$ for an active space of (28e,176o) and a MR wave function including up to $2 \times 10^7$ determinants.
description: 8 pages, 5 figures
Non-Ideal Program-Time Conservation in Charge Trap Flash for Deep Learning
Creators: name: Shrivastava, Shalini
name: Saraswat, Vivek
name: Dash, Gayatri
name: Chakrabarty, Samyak
name: Ganguly, Udayan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Neural and Evolutionary Computing (cs.NE)
subject: Emerging Technologies (cs.ET)
subject: FOS: Computer and information sciences

description: Training deep neural networks (DNNs) is computationally intensive but arrays of non-volatile memories like Charge Trap Flash (CTF) can accelerate DNN operations using in-memory computing. Specifically, the Resistive Processing Unit (RPU) architecture uses the voltage-threshold program by stochastic encoded pulse trains and analog memory features to accelerate vector-vector outer product and weight update for the gradient descent algorithms. Although CTF, offering high precision, has been regarded as an excellent choice for implementing RPU, the accumulation of charge due to the applied stochastic pulse trains is ultimately of critical significance in determining the final weight update. In this paper, we report the non-ideal program-time conservation in CTF through pulsing input measurements. We experimentally measure the effect of pulse width and pulse gap, keeping the total ON-time of the input pulse train constant, and report three non-idealities: (1) Cumulative V_T shift reduces when total ON-time is fragmented into a larger number of shorter pulses, (2) Cumulative V_T shift drops abruptly for pulse widths < 2 μs, (3) Cumulative V_T shift depends on the gap between consecutive pulses and the V_T shift reduction gets recovered for smaller gaps. We present an explanation based on a transient tunneling field enhancement due to blocking oxide trap-charge dynamics to explain these non-idealities. Identifying and modeling the responsible mechanisms and predicting their system-level effects during learning is critical. This non-ideal accumulation is expected to affect algorithms and architectures relying on devices for implementing mathematically equivalent functions for in-memory computing-based acceleration.
The B-type Binaries Characterisation Programme II. VFTS 291: A stripped star from a recent mass transfer phase
Creators: name: Villaseñor, J. I.
name: Lennon, D. J.
name: Picco, A.
name: Shenar, T.
name: Marchant, P.
name: Langer, N.
name: Dufton, P. L.
name: Nardini, F.
name: Evans, C. J.
name: Bodensteiner, J.
name: de Mink, S. E.
name: Götberg, Y.
name: Soszyński, I.
name: Taylor, W. D.
name: Sana, H.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recent studies of massive binaries with putative black hole companions have uncovered a phase of binary evolution that has not been observed before, featuring a bloated stripped star that very recently ceased transferring mass to a main-sequence companion. In this study, we focus on the candidate system VFTS 291, a binary with an orbital period of 108 d and a high semi-amplitude velocity ($K_1=93.7\pm0.2$ km s$^{-1}$). Through our analysis of the disentangled spectra of the two components, together with dynamical and evolutionary arguments, we identify a narrow-lined star of ~1.5-2.5 $M_\odot$ dominating the spectrum, and an early B-type main-sequence companion of $13.2\pm1.5$ $M_\odot$. The low mass of the narrow-lined star, and the high mass ratio, suggest that VFTS 291 is a post-mass-transfer system, with the narrow-lined star being bloated and stripped of its hydrogen-rich envelope, sharing many similarities with other recently discovered stripped stars. Our finding is supported by our detailed binary evolution models, which indicate that the system can be well explained by an initial configuration consisting of an 8.1 $M_\odot$ primary with an 8 $M_\odot$ companion in a 7 d orbital period. While some open questions remain, particularly concerning the surface helium enrichment of the stripped star and the rotational velocity of the companion, we expect that high-resolution spectroscopy may help reconcile our estimates with theory. Our study highlights the importance of multi-epoch spectroscopic surveys to identify and characterize binary interaction products, and provides important insights into the evolution of massive binary stars.
description: 25 pages, 17 figures. Published by MNRAS, Advance Access
The singly-charmed pentaquark molecular states via the QCD sum rules
Creators: name: Xin, Qi
name: Yang, Xiao-Song
name: Wang, Zhi-Gang
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this work, we systematically investigate the singly-charmed pentaquark molecular states $D^{(*)}N$, $D^{(*)}Ξ^{(*)}$ and $D_s^{(*)}Ξ^{(*)}$ with the QCD sum rules by carrying out the operator product expansion up to the vacuum condensates of dimension 13 and taking fully account of the light-flavor $SU(3)$ breaking effects. The numerical results favor assigning the $Ω_c(3185)$ as the $DΞ$ molecular state with the $J^P=\frac{1}{2}^-$ and $| I,I_3 \rangle=| 0,0 \rangle$, assigning the $Ω_c(3327)$ as the $D^*Ξ$ molecular state with the $J^P=\frac{3}{2}^-$ and $|I,I_3 \rangle=| 0,0 \rangle$, assigning the $Σ_c(2800)$ as the $DN$ molecular state with the $J^P=\frac{1}{2}^-$ and $| I,I_3 \rangle=| 1,0 \rangle$, and assigning the $Λ_c(2940)/Λ_c(2910)$ as the $D^*N$ molecular state with the $J^P=\frac{3}{2}^-$ and $| I,I_3 \rangle=| 0,0 \rangle$. Other potential molecule candidates are also predicted, which may be observed in future experiments. For example, we can search for the $DΞ$ and $D^*Ξ$ molecular states with the isospin $| I,I_3 \rangle=| 1,\pm1 \,\rangle$ in the $Ξ_c^+\bar{K}^0$ and $Ξ_c^0\bar{K}^-$ mass spectrum respectively in the future, which could shed light on the nature of the $Ω_c(3185/3327)$.
description: 23 pages, 6 figures
Development of a CsI Calorimeter for the Compton-Pair (ComPair) Balloon-Borne Gamma-Ray Telescope
Creators: name: Shy, Daniel
name: Woolf, Richard S.
name: Sleator, Clio C.
name: Wulf, Eric A.
name: Johnson-Rambert, Mary
name: Kong, Emily
name: Davis, J. Mitch
name: Caligiure, Thomas J.
name: Grove, J. Eric
name: Phlips, Bernard F.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: There is a growing interest in astrophysics to fill in the observational gamma-ray MeV gap. We, therefore, developed a CsI:Tl calorimeter prototype as a subsystem to a balloon-based Compton and Pair-production telescope known as ComPair. ComPair is a technology demonstrator for a gamma-ray telescope in the MeV range that is comprised of 4 subsystems: the double-sided silicon detector, virtual Frisch grid CdZnTe, CsI calorimeter, and a plastic-based anti-coincidence detector. The prototype CsI calorimeter is composed of thirty CsI logs, each with a geometry of $1.67 \times 1.67 \times 10 \ \mathrm{cm^3}$. The logs are arranged in a hodoscopic fashion with 6 in a row that alternate directions in each layer. Each log has a resolution of around $8 \%$ full-width-at-half-maximum (FWHM) at $662 \ \mathrm{keV}$ with a dynamic energy range of around $250\ \mathrm{keV}-30 \ \mathrm{MeV}$. A $2\times2$ array of SensL J-series SiPMs read out each end of the log to estimate the depth of interaction and energy deposition with signals read out with an IDEAS ROSSPAD. We also utilize an Arduino to synchronize with the other ComPair subsystems that comprise the full telescope. This work presents the development and performance of the calorimeter, its testing in thermal and vacuum conditions, and results from irradiation by $2-25 \ \mathrm{MeV}$ monoenergetic gamma-ray beams. The CsI calorimeter will fly onboard ComPair as a balloon experiment in the summer of 2023.
Fermi LAT AGN classification using supervised machine learning
Creators: name: Cooper, Nathaniel
name: Dainotti, Maria Giovanna
name: Narendra, Aditya
name: Liodakis, Ioannis
name: Bogdan, Malgorzata
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Classifying Active Galactic Nuclei (AGN) is a challenge, especially for BL Lac Objects (BLLs), which are identified by their weak emission line spectra. To address the problem of classification, we use data from the 4th Fermi Catalog, Data Release 3. Missing data hinders the use of machine learning to classify AGN. A previous paper found that Multiple Imputation by Chain Equations (MICE) imputation is useful for estimating missing values. Since many AGN have missing redshift and the highest energy, we use data imputation with MICE and K-nearest neighbor (kNN) algorithm to fill in these missing variables. Then, we classify AGN into the BLLs or the Flat Spectrum Radio Quasars (FSRQs) using the SuperLearner, an ensemble method that includes several classification algorithms like logistic regression, support vector classifiers, Random Forests, Ranger Random Forests, multivariate adaptive regression spline (MARS), Bayesian regression, Extreme Gradient Boosting. We find that a SuperLearner model using MARS regression and Random Forests algorithms is 91.1% accurate for kNN imputed data and 91.2% for MICE imputed data. Furthermore, the kNN-imputed SuperLearner model predicts that 892 of the 1519 unclassified blazars are BLLs and 627 are Flat Spectrum Radio Quasars (FSRQs), while the MICE-imputed SuperLearner model predicts 890 BLLs and 629 FSRQs in the unclassified set. Thus, we can conclude that both imputation methods work efficiently and with high accuracy and that our methodology ushers the way for using SuperLearner as a novel classification method in the AGN community and, in general, in the astrophysics community.
description: 15 pages, 8 figures, to be published in Monthly Notices of the Royal Astronomical Society
Predicted Measurements of the Tensor-to-Scalar Transition in the CLAS12 Nuclear Targets Experiment
Creators: name: Seroka, Erin Marshall
name: Schmidt, Axel
Publisher: name: arXiv
Year: 2023
Subjects: subject: Nuclear Theory (nucl-th)
subject: Nuclear Experiment (nucl-ex)
subject: FOS: Physical sciences

description: Short-range correlated (SRC) nucleon pairs, which are strongly interacting nucleons at short inter-particle distances, can reveal properties of the effective nucleon-nucleon (\textit{NN}) interaction at short distance scales. The relative abundance of proton-proton (\textit{pp}) pairs and proton-neutron (\textit{pn}) pairs, for example, is sensitive to the tensor contribution to the \textit{NN} interaction. Generalized Contact Formalism (GCF) theory, when used with realistic phenomenological \textit{NN} potential models, predicts a transition from a tensor-dominated regime -- at relative momenta of approximately 400~MeV/\textit{c} where \textit{pp} pairs are suppressed relative to \textit{pn} pairs -- to a scalar-dominated regime at higher momenta with no preferred isospin projection. While an increase in the prevalence of \textit{pp} pairs with increasing momentum has been observed in a few experiments, difficulties associated with neutron detection have so far hindered the observation of a corresponding reduction in the abundance of \textit{pn} pairs. High-precision measurements showing a simultaneous increase in the abundance of \textit{pp} pairs and change in the abundance of \textit{pn} pairs with increasing momentum would conclusively demonstrate the existence of the tensor-to-scalar transition. In this work, we study the potential impact of the recently conducted Nuclear Targets Experiment at the CLAS12 detector at Jefferson Lab, using GCF simulations. We model the expected yields and relevant observables for a carbon target with a beam energy of 6 GeV and show that sufficient statistical precision can be obtained from the experimental data, both for \textit{pp} and \textit{pn} pairs, to observe the tensor-to-scalar transition.
description: 23 pages, 6 figures