cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Large-amplitude rapid X-ray variability in the narrow-line Seyfert 1 galaxy PG 1404$+$226
Creators: name: Mallick, Labani
name: Dewangan, Gulab C.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We present the first results from a detailed analysis of a new, long ($\sim100$ ks) XMM-Newton observation of the narrow-line Seyfert 1 galaxy PG 1404$+$226 which showed a large-amplitude, rapid X-ray variability by a factor of $\sim7$ in $\sim10$ ks with an exponential rise and a sharp fall in the count rate. We investigate the origin of the soft X-ray excess emission and rapid X-ray variability in the source through time-resolved spectroscopy and fractional root-mean-squared (rms) spectral modeling. The strong soft X-ray excess below 1 keV observed both in the time-averaged and time-resolved spectra is described by the intrinsic disk Comptonization model as well as the relativistic reflection model where the emission is intensive merely in the inner regions ($r_{\rm in}<1.7 r_{\rm g}$) of an ionized accretion disk. We detected no significant UV variability while the soft X-ray excess flux varies together with the primary power-law emission (as $F_{\rm primary}\propto F_{\rm excess}^{1.54}$), although with a smaller amplitude, as expected in the reflection scenario. The observed X-ray fractional rms spectrum is approximately constant with a drop at $\sim0.6$ keV and is described by a non-variable emission line component with the observed energy of $\sim0.6$ keV and two variable spectral components: a more variable primary power-law emission and a less variable soft excess emission. Our results suggest the `lamppost geometry' for the primary X-ray emitting hot corona which illuminates the innermost accretion disk due to strong gravity and gives rise to the soft X-ray excess emission.
description: 16 pages, 12 figures, 3 tables, accepted for publication in ApJ
Strong Diffusion Effect of Charm Quarks on $J/ψ$ Production in Pb-Pb collisions at the LHC
Creators: name: Zhao, Jiaxing
name: Chen, Baoyi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We study the $J/ψ$ production based on coalescence model at $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV Pb-Pb collisions. With the colliding energy increasing from 2.76 TeV to 5.02 TeV, the number of charm pairs is enhanced by more than 50%. However, the ratio of $J/ψ$ inclusive nuclear modification factors $R^{5.02TeV}_{AA}/R^{2.76TeV}_{AA}$ is only about 1.1 $\sim$ 1.2. We find that the regeneration of $J/ψ$ is proportional to the densities of charm and anti-charm quarks, instead of their total numbers. The charm quark density is diluted by the strong expansion of quark gluon plasma, which suppresses the combination probability of heavy quarks and $J/ψ$ regeneration. This effect is more important in higher colliding energies where QGP expansion is strong. We also propose the ratio $N_{J/ψ}/(N_D)^2$ as a measurement of $c$ and $\bar c$ coalescence probability, which is only affected by the heavy quark diffusions in QGP, and does not depend on the inputs such as cold nuclear matter effects and cross sections of charm quark production. Further more, we give the predictions at the energy of Future Circular Collider ($\sqrt{s_{NN}}$ = 39 TeV).
The AMBRE project: Iron-peak elements in the solar neighbourhood
Creators: name: Mikolaitis, Š.
name: de Laverny, P.
name: Recio-Blanco, A.
name: Hill, V.
name: Worley, C. C.
name: de Pascale, M.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The aim of this paper is to characterise the abundance patterns of five iron-peak elements (Mn, Fe, Ni, Cu, and Zn) for which the stellar origin and chemical evolution are still debated. We automatically derived iron peak (Mn, Fe, Ni, Cu, and Zn) and alpha element (Mg) chemical abundances for 4666 stars. We used the bimodal distribution of [Mg/Fe] to chemically classify sample stars into different Galactic substructures: thin disc, metal-poor and high-alpha metal rich, high-alpha and low-alpha metal-poor populations. High-alpha and low-alpha metal-poor populations are fully distinct in Mg, Cu, and Zn. Thin disc trends of [Ni/Fe] and [Cu/Fe] are very similar and show a small increase at supersolar metallicities. Thin and thick disc trends of Ni and Cu are very similar and indistinguishable. Mn looks different from Ni and Cu. [Mn/Fe] trends of thin and thick discs actually have noticeable differences: the thin disc is slightly Mn richer than the thick disc. [Zn/Fe] trends look very similar to those of [alpha/Fe] trends. The dispersion of results in both discs is low (approx 0.05 dex for [Mg, Mn, and Cu/Fe]) and is even much lower for [Ni/Fe] (approx 0.035 dex). Zn is an alpha-like element and could be used to separate thin and thick disc stars. [Mn/Mg] ratio could also be a very good tool for tagging Galactic substructures. Some models can partially reproduce the observed Mg, Zn, and, Cu behaviours. Models mostly fail to reproduce Mn and Ni in all metallicity domains, however, models adopting yields normalised from solar chemical properties reproduce Mn and Ni better, suggesting that there is still a lack of realistic theoretical yields of some iron-peak elements. Very low scatter (approx 0.05 dex) in thin and thick disc sequences could provide an observational constrain for Galactic evolutionary models that study the efficiency of stellar radial migration.
description: 21 pages, 20 figures
Improving the Neural GPU Architecture for Algorithm Learning
Creators: name: Freivalds, Karlis
name: Liepins, Renars
Publisher: name: arXiv
Year: 2017
Subjects: subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: Algorithm learning is a core problem in artificial intelligence with significant implications on automation level that can be achieved by machines. Recently deep learning methods are emerging for synthesizing an algorithm from its input-output examples, the most successful being the Neural GPU, capable of learning multiplication. We present several improvements to the Neural GPU that substantially reduces training time and improves generalization. We introduce a new technique - hard nonlinearities with saturation costs- that has general applicability. We also introduce a technique of diagonal gates that can be applied to active-memory models. The proposed architecture is the first capable of learning decimal multiplication end-to-end.
description: Minor edits
Candidates for Universal Measures of Multipartite Entanglement
Creators: name: Hedemann, Samuel R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose and examine several candidates for universal multipartite entanglement measures. The most promising candidate for applications needing entanglement in the full Hilbert space is the ent-concurrence, which detects all entanglement correlations while distinguishing between different types of distinctly multipartite entanglement, and simplifies to the concurrence for two-qubit mixed states. For applications where subsystems need internal entanglement, we develop the absolute ent-concurrence which detects the entanglement in the reduced states as well as the full state.
description: 16 pages, 9 figures. v2: changed "nonlocal correlations" to "entanglement correlations" since that is what was meant and is more accurate since it distinguishes them from nonlocal correlations not involving entanglement. v3: incorporated new term "full k-partite entanglement" defined as "the absence of k-separability" for compatibility with existing terminology. No results affected
Probing subnucleon scale fluctuations in ultraperipheral heavy ion collisions
Creators: name: Mäntysaari, Heikki
name: Schenke, Björn
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We show that introducing subnucleon scale fluctuations constrained by HERA diffractive $J/Ψ$ production data significantly affects the incoherent diffractive $J/Ψ$ production cross section in ultraperipheral heavy ion collisions. We find that the inclusion of the additional fluctuations increases the ratio of the incoherent to the coherent cross section approximately by a factor of $2$, and modifies the transverse momentum spectra of the produced $J/Ψ$ at momenta larger than the scale that corresponds to the distance scale of the subnucleonic fluctuations. We present predictions for $J/Ψ$ production in ultraperipheral heavy ion collisions at $\sqrt{s_{NN}}=5.02\,{\rm TeV}$ at the LHC and $200\,{\rm GeV}$ at RHIC.
description: 9 pages, 8 figures. v2: small clarifications to the text, matches the published version
The Newton constant and gravitational waves in some vector field adjusting mechanisms
Creators: name: Santillan, O.
name: Scornavacche, M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: As is well known, there exist some Lorentz breaking scenarios which explain the smallness of the cosmological constant in the present era. An important aspect to analyze is the propagation of gravitational waves and the screening or enhancement of the Newton constant $G_N$ in these models. The problem is that the Lorentz symmetry breaking terms may induce an unacceptable value of the Newton constant $G_N$ or introduce longitudinal modes in the gravitational waves. Furthermore there may spoil the standard dispersion relation $ω=ck$. In [21] the authors have presented a model for which they suggest that the behavior of the gravitational constant is the correct one for asymptotic times. In the present work, an explicit checking is made and we finally agree with these claims. Furthermore, it is suggested that the gravitational waves are also well behaved for large times. In the process, some new models with the same behavior are obtained, thus enlarging the list of possible adjustment mechanisms.
description: Some subtle detail about the gauge are corrected. No further changes
Functional correlation decay and multivariate normal approximation for non-uniformly expanding maps
Creators: name: Leppänen, Juho
Publisher: name: arXiv
Year: 2017
Subjects: subject: Dynamical Systems (math.DS)
subject: Probability (math.PR)
subject: FOS: Mathematics

description: In the setting of intermittent Pomeau-Manneville maps with time dependent parameters, we show a functional correlation bound widely useful for the analysis of the statistical properties of the model. We give two applications of this result, by showing that in a suitable range of parameters the bound implies the conditions of the normal approximation methods of Stein and Rio. For a single Pomeau-Manneville map belonging to this parameter range, both methods then yield a multivariate central limit theorem with a rate of convergence.
description: 21 pages; v.3: minor corrections according to comments by referee/pre-examiner
DFTBaby: A software package for non-adiabatic molecular dynamics simulations based on long-range corrected tight-binding TD-DFT(B)
Creators: name: Humeniuk, Alexander
name: Mitric, Roland
Publisher: name: arXiv
Year: 2017
Subjects: subject: Chemical Physics (physics.chem-ph)
subject: FOS: Physical sciences

description: A software package, called DFTBaby, is published, which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of charge-consistent tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton's equations of motion for the nuclei together with the electronic Schrödinger equation. Non-adiabatic effects are included by surface hopping. As an example, the program is applied to the optimization of excited states and non-adiabatic dynamics of polyfluorene. The python and Fortran source code is available at http://www.dftbaby.chemie.uni-wuerzburg.de/.
Retirement in Iran: From the Establishment of the Pension System to the Emergence of a New Life Course
Creators: name: Haji Mohammadian, Mehran
Publisher: name: Universität Bielefeld
Year: 2023
Subjects: subject: 300
subject: Iran
subject: Retirement Institution
subject: Early Retirement
subject: Pension
subject: Middle-Income Countries

description: The establishment of the pension system has had some consequences for Iranian society. This study, however, focuses on the framing power of the pension system in the emergence of a new life course for Iranians as retirees. With the implementation of the pension system, the traditional model of working until death or as long as physical ability allows has changed to working until the age of retirement. Taking this transition into consideration, this study investigates retirement as an ‘institution’ in terms of all rules and regulations related to the shift from the work to non-work phase during the later stages of life. By applying a historical and institutional analysis, we begin with the first retirement law, which was replicated from foreign countries in 1922 for the public sector employees. The first group of workers in the private sector was included in pension schemes one decade later. The main institutional change in retirement occurred in the 1970s when the early retirement plans took dominance in Iran and continues to this day. This institutional change is not related to the old-age protection, however, it is more advocated on the political and economic ground.

 With an increasing number of retirees, especially through early retirement plans, we can see that people are withdrawing from work much earlier than before, at least since 2006. The findings from the individual case study of Iran are also contextualized in the international experiences of retirement. This comparative study shows that the Iranian retirement trend is not unique and to some extent occurs in other countries, especially in middle-income countries in terms of timing and policies for its provisions. In conclusion, I argue that the implementation of the retirement institution in Iran over the last century has not been very successful in achieving the aim of old-age protection nor the purposes of early retirement plans. This institution is also unequally implemented for the middle-aged groups rather than the elderly. Today, this Bismarkian social insurance model is vastly used and is the main social policy program for Iranians, though it is financially very unstable.
Possibility to probe negative values of a Wigner function in scattering of a coherent superposition of electronic wave packets by atoms
Creators: name: Karlovets, Dmitry V.
name: Serbo, Valeriy G.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: Within a plane-wave approximation in scattering, an incoming wave packet's Wigner function stays everywhere positive, which obscures such purely quantum phenomena as non-locality and entanglement. With the advent of the electron microscopes with subnanometer-sized beams one can enter a genuinely quantum regime where the latter effects become only moderately attenuated. Here we show how to probe negative values of the Wigner function in scattering of a coherent superposition of two Gaussian packets with a non-vanishing impact-parameter between them (a Schrödinger's cat state) by atomic targets. For hydrogen in the ground $1s$ state, a small parameter of the problem, a ratio $a/σ_{\perp}$ of the Bohr radius $a$ to the beam width $σ_{\perp}$, is no longer vanishing. We predict an azimuthal asymmetry of the scattered electrons, which is found to be up to $10 \%$ and argue that it can be reliably detected. Production of beams with the not-everywhere positive Wigner functions and probing such quantum effects can open new perspectives for non-invasive electron microscopy, quantum tomography, particle physics, etc.
description: to appear in PRL
Vector Invariants For Two-dimensional Orthogonal Groups Over Finite Fields
Creators: name: Chen, Yin
Publisher: name: arXiv
Year: 2016
Subjects: subject: Commutative Algebra (math.AC)
subject: FOS: Mathematics

description: Let $\mathbb{F}_{q}$ be a finite field of characteristic 2 and $O_2(\mathbb{F}_{q})^{+}$ be the 2-dimensional orthogonal group of plus type over $\mathbb{F}_{q}$. Consider the standard representation $V$ of $O_2(\mathbb{F}_{q})^{+}$ and the ring of vector invariants $\mathbb{F}_{q}[mV]^{O_2(\mathbb{F}_{q})^{+}}$ for any $m\in \mathbb{N}^{+}$. We prove a first main theorem for $(O_2(\mathbb{F}_{q})^{+},V)$, i.e., we find a minimal generating set for $\mathbb{F}_{q}[mV]^{O_2(\mathbb{F}_{q})^{+}}$. As a consequence, we derive the Noether number $β_{mV}(O_2(\mathbb{F}_{q})^{+})=\max\{q-1,m\}$. We construct a free basis for $\mathbb{F}_{q}[2V]^{O_2(\mathbb{F}_{q})^{+}}$ over a suitably chosen homogeneous system of parameters. We also obtain a generating set of the Hilbert ideal for $\mathbb{F}_{q}[mV]^{O_2(\mathbb{F}_{q})^{+}}$ which shows that the Hilbert ideal can be generated by invariants of degree $\leqslant q-1=\frac{|O_2(\mathbb{F}_{q})^{+}|}{2}$, confirming Derksen-Kemper's conjecture \cite[Conjecture 3.8.6 (b)]{DK2002} in this particular case.
description: 18 pages. Accepted for publication in Monatshefte f\"ur Mathematik
Interplay between short-range correlated disorder and Coulomb interaction in nodal-line semimetals
Creators: name: Wang, Yuxuan
name: Nandkishore, Rahul M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: In nodal-line semimetals, Coulomb interactions and short-range correlated disorder are both marginal perturbations to the clean non-interacting Hamiltonian. We analyze their interplay using a weak-coupling renormalization group approach. In the clean case, the Coulomb interaction has been found to be marginally irrelevant, leading to Fermi liquid behavior. We extend the analysis to incorporate the effects of disorder. The nodal line structure gives rise to kinematical constraints similar to that for a two-dimensional Fermi surface, which plays a crucial role in the one-loop renor- malization of the disorder couplings. For a two-fold degenerate nodal loop (Weyl loop), we show that disorder flows to strong coupling along a unique fixed trajectory in the space of symmetry inequiv- alent disorder couplings. Along this fixed trajectory, all symmetry inequivalent disorder strengths become equal. For a four-fold degenerate nodal loop (Dirac loop), disorder also flows to strong coupling, however the strengths of symmetry inequivalent disorder couplings remain different. We show that feedback from disorder reverses the sign of the beta function for the Coulomb interaction, causing the Coulomb interaction to flow to strong coupling as well. However, the Coulomb interac- tion flows to strong coupling asymptotically more slowly than disorder. Extrapolating our results to strong coupling, we conjecture that at low energies nodal line semimetals should be described by a noninteracting nonlinear sigma model. We discuss the relation of our results with possible many-body localization at zero temperatures in such materials.
description: 13 pages, 4 figures, to match the published version
Non-universality of front fluctuations for compact colonies of non-motile bacteria
Creators: name: Santalla, Silvia N.
name: Rodríguez-Laguna, Javier
name: Abad, José P.
name: Marín, Irma
name: Espinosa, María del Mar
name: Muñoz-García, Javier
name: Vázquez, Luis
name: Cuerno, Rodolfo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Physical sciences

description: The front of a compact bacterial colony growing on a Petri dish is a paradigmatic instance of non-equilibrium fluctuations in the celebrated Eden, or Kardar-Parisi-Zhang (KPZ), universality class. While in many experiments the scaling exponents crucially differ from the expected KPZ values, the source of this disagreement has remained poorly understood. We have performed growth experiments with B. subtilis 168 and E. coli ATCC 25922 under conditions leading to compact colonies in the classically-alleged Eden regime, where individual motility is suppressed. Non-KPZ scaling is indeed observed for all accessible times, KPZ asymptotics being ruled out for our experiments due to the monotonic increase of front branching with time. Simulations of an effective model suggest the occurrence of transient non-universal scaling due to diffusive morphological instabilities, agreeing with expectations from detailed models of the relevant biological reaction-diffusion processes.
Strong dopant dependence of electric transport in ion-gated MoS2
Creators: name: Piatti, Erik
name: Chen, Qihong
name: Ye, Jianting
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We report modifications of the temperature-dependent transport properties of $\mathrm{MoS_2}$ thin flakes via field-driven ion intercalation in an electric double layer transistor. We find that intercalation with $\mathrm{Li^+}$ ions induces the onset of an inhomogeneous superconducting state. Intercalation with $\mathrm{K^+}$ leads instead to a disorder-induced incipient metal-to-insulator transition. These findings suggest that similar ionic species can provide access to different electronic phases in the same material.
description: 5 pages, 3 figures
Gapped paramagnetic state in a frustrated spin-$\frac{1}{2}$ Heisenberg antiferromagnet on the cross-striped square lattice
Creators: name: Li, P. H. Y.
name: Bishop, R. F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We implement the coupled cluster method to very high orders of approximation to study the spin-$\frac{1}{2}$ $J_{1}$--$J_{2}$ Heisenberg model on a cross-striped square lattice. Every nearest-neighbour pair of sites on the square lattice has an isotropic antiferromagnetic exchange bond of strength $J_{1}>0$, while the basic square plaquettes in alternate columns have either both or neither next-nearest-neighbour (diagonal) pairs of sites connected by an equivalent frustrating bond of strength $J_{2} \equiv αJ_{1} > 0$. By studying the magnetic order parameter (i.e., the average local on-site magnetization) in the range $0 \leq α\leq 1$ of the frustration parameter we find that the quasiclassical antiferromagnetic Néel and (so-called) double Néel states form the stable ground-state phases in the respective regions $α< α_{1a}^{c} = 0.46(1)$ and $α> α_{1b}^{c} = 0.615(5)$. The double Néel state has Néel ($\cdots\uparrow\downarrow\uparrow\downarrow\cdots$) ordering along the (column) direction parallel to the stripes of squares with both or no $J_{2}$ bonds, and spins alternating in a pairwise ($\cdots\uparrow\uparrow\downarrow\downarrow\uparrow\uparrow\downarrow\downarrow\cdots$) fashion along the perpendicular (row) direction, so that the parallel pairs occur on squares with both $J_{2}$ bonds present. Further explicit calculations of both the triplet spin gap and the zero-field uniform transverse magnetic susceptibility provide compelling evidence that the ground-state phase over all or most of the intermediate regime $α_{1a}^{c} < α< α_{1b}^{c}$ is a gapped state with no discernible long-range magnetic order.
R-C3D: Region Convolutional 3D Network for Temporal Activity Detection
Creators: name: Xu, Huijuan
name: Das, Abir
name: Saenko, Kate
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: We address the problem of activity detection in continuous, untrimmed video streams. This is a difficult task that requires extracting meaningful spatio-temporal features to capture activities, accurately localizing the start and end times of each activity. We introduce a new model, Region Convolutional 3D Network (R-C3D), which encodes the video streams using a three-dimensional fully convolutional network, then generates candidate temporal regions containing activities, and finally classifies selected regions into specific activities. Computation is saved due to the sharing of convolutional features between the proposal and the classification pipelines. The entire model is trained end-to-end with jointly optimized localization and classification losses. R-C3D is faster than existing methods (569 frames per second on a single Titan X Maxwell GPU) and achieves state-of-the-art results on THUMOS'14. We further demonstrate that our model is a general activity detection framework that does not rely on assumptions about particular dataset properties by evaluating our approach on ActivityNet and Charades. Our code is available at http://ai.bu.edu/r-c3d/.
description: ICCV 2017 Camera Ready Version
On double-resolution imaging and discrete tomography
Creators: name: Alpers, Andreas
name: Gritzmann, Peter
Publisher: name: arXiv
Year: 2017
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Combinatorics (math.CO)
subject: FOS: Computer and information sciences
subject: FOS: Mathematics
subject: 68R05, 68Q25, 49N45, 94A08

description: Super-resolution imaging aims at improving the resolution of an image by enhancing it with other images or data that might have been acquired using different imaging techniques or modalities. In this paper we consider the task of doubling, in each dimension, the resolution of grayscale images of binary objects by fusion with double-resolution tomographic data that have been acquired from two viewing angles. We show that this task is polynomial-time solvable if the gray levels have been reliably determined. The problem becomes $\mathbb{N}\mathbb{P}$-hard if the gray levels of some pixels come with an error of $\pm1$ or larger. The $\mathbb{N}\mathbb{P}$-hardness persists for any larger resolution enhancement factor. This means that noise does not only affect the quality of a reconstructed image but, less expectedly, also the algorithmic tractability of the inverse problem itself.
description: 26 pages, to appear in SIAM Journal on Discrete Mathematics
Induced density correlations in a sonic black hole condensate
Creators: name: Wang, Yi-Hsieh
name: Jacobson, Ted
name: Edwards, Mark
name: Clark, Charles W.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Analog black/white hole pairs, consisting of a region of supersonic flow, have been achieved in a recent experiment by J. Steinhauer using an elongated Bose-Einstein condensate. A growing standing density wave, and a checkerboard feature in the density-density correlation function, were observed in the supersonic region. We model the density-density correlation function, taking into account both quantum fluctuations and the shot-to-shot variation of atom number normally present in ultracold-atom experiments. We find that quantum fluctuations alone produce some, but not all, of the features of the correlation function, whereas atom-number fluctuation alone can produce all the observed features, and agreement is best when both are included. In both cases, the density-density correlation is not intrinsic to the fluctuations, but rather is induced by modulation of the standing wave caused by the fluctuations.
description: 11 pages, 10 figures
Cosmological Implications of Dark Matter Bound States
Creators: name: Mitridate, Andrea
name: Redi, Michele
name: Smirnov, Juri
name: Strumia, Alessandro
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We present generic formulae for computing how Sommerfeld corrections together with bound-state formation affects the thermal abundance of Dark Matter with non-abelian gauge interactions. We consider DM as a fermion 3plet (wino) or 5plet under SU(2)$_L$. In the latter case bound states raise to 14 TeV the DM mass required to reproduce the cosmological DM abundance and give indirect detection signals such as (for this mass) a dominant $γ$-line around 85 GeV. Furthermore, we consider DM co-annihilating with a colored particle, such as a squark or a gluino, finding that bound state effects are especially relevant in the latter case.
description: 40 pages, 11 figures. v3: post-confinement QCD effects added; O(1) factor fixed
VIKING-AGE COINAGE REVISITED: NEW NORWEGIAN COINS OF ST. OLAVE AND HARALD HARDRADA FROM SMOLENSK, RUSSIA
Creators: name: Petrov, Alexander
name: Grigorieva, Yulia G
name: Galanov, Vladimir
Publisher: name: figshare
Year: 2023
Subjects: classificationCode: 430310
subject: Global and world history
classificationCode: 430316
subject: International history
classificationCode: 430101
subject: Archaeological science

description: We argue that the Russian historical science is undergoing significant changes, and the place of Russia in European and world history is being largely rethought. At the same time, the Russian and international tradition in analyzing the Viking Age has been preserved and strengthened
A proof of concept for scale-adaptive parameterizations: the case of the Lorenz '96 model
Creators: name: Vissio, Gabriele
name: Lucarini, Valerio
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Chaotic Dynamics (nlin.CD)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: Constructing efficient and accurate parameterizations of sub-grid scale processes is a central area of interest in the numerical modelling of geophysical fluids. Using a modified version of the two-level Lorenz '96 model, we present here a proof of concept of a scale-adaptive parameterization constructed using statistical mechanical arguments. By a suitable use of the Ruelle response theory and of the Mori-Zwanzig projection method, it is possible to derive explicitly a parameterization for the fast variables that translates into deterministic, stochastic and non-markovian contributions to the equations of motion of the variables of interest. We show that our approach is computationally parsimonious, has great flexibility, as it is explicitly scale-adaptive, and we prove that it is competitive compared to empirical ad-hoc approaches. While the parameterization proposed here is universal and can be easily analytically adapted to changes in the parameters' values by a simple rescaling procedure, the parameterization constructed with the ad-hoc approach needs to be recomputed each time the parameters of the systems are changed. The price of the higher flexibility of the method proposed here is having a lower accuracy in each individual case.
description: 39 pages, 17 figures; improved discussion of the results and of the theory
Neutrino Flavor Evolution in Neutron Star Mergers
Creators: name: Tian, James Y.
name: Patwardhan, Amol V.
name: Fuller, George M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: We examine the flavor evolution of neutrinos emitted from the disk-like remnant (hereafter called \lq\lq neutrino disk\rq\rq) of a binary neutron star (BNS) merger. We specifically follow the neutrinos emitted from the center of the disk, along the polar axis perpendicular to the equatorial plane. We carried out two-flavor simulations using a variety of different possible initial neutrino luminosities and energy spectra, and for comparison, three-flavor simulations in specific cases. In all simulations, the normal neutrino mass hierarchy was used. The flavor evolution was found to be highly dependent on the initial neutrino luminosities and energy spectra; in particular, we found two broad classes of results depending on the sign of the initial net electron neutrino lepton number (i.e., the number of neutrinos minus the number of antineutrinos). In the antineutrino dominated case, we found that the Matter-Neutrino Resonance (MNR) effect dominates, consistent with previous results, whereas in the neutrino dominated case, a bipolar spectral swap develops. The neutrino dominated conditions required for this latter result have been realized, e.g, in a BNS merger simulation that employs the \lq\lq DD2\rq\rq\ equation of state for neutron star matter[Phys. Rev. D 93, 044019 (2016)]. For this case, in addition to the swap at low energies, a collective Mikheyev-Smirnov-Wolfenstein (MSW) mechanism generates a high-energy electron neutrino tail. The enhanced population of high-energy electron neutrinos in this scenario could have implications for the prospects of $r$-process nucleosynthesis in the material ejected outside the plane of the neutrino disk.
description: Version published in Physical Review D. 22 pages, 16 figures, 9 tables. For movies see Ancillary files in version 1
The Ising Partition Function: Zeros and Deterministic Approximation
Creators: name: Liu, Jingcheng
name: Sinclair, Alistair
name: Srivastava, Piyush
Publisher: name: arXiv
Year: 2017
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Computational Complexity (cs.CC)
subject: Discrete Mathematics (cs.DM)
subject: Combinatorics (math.CO)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We study the problem of approximating the partition function of the ferromagnetic Ising model in graphs and hypergraphs. Our first result is a deterministic approximation scheme (an FPTAS) for the partition function in bounded degree graphs that is valid over the entire range of parameters $β$ (the interaction) and $λ$ (the external field), except for the case $\vertλ\vert=1$ (the "zero-field" case). A randomized algorithm (FPRAS) for all graphs, and all $β,λ$, has long been known. Unlike most other deterministic approximation algorithms for problems in statistical physics and counting, our algorithm does not rely on the "decay of correlations" property. Rather, we exploit and extend machinery developed recently by Barvinok, and Patel and Regts, based on the location of the complex zeros of the partition function, which can be seen as an algorithmic realization of the classical Lee-Yang approach to phase transitions. Our approach extends to the more general setting of the Ising model on hypergraphs of bounded degree and edge size, where no previous algorithms (even randomized) were known for a wide range of parameters. In order to achieve this extension, we establish a tight version of the Lee-Yang theorem for the Ising model on hypergraphs, improving a classical result of Suzuki and Fisher.
description: clarified presentation of combinatorial arguments, added new results on optimality of univariate Lee-Yang theorems
Refined BPS invariants of 6d SCFTs from anomalies and modularity
Creators: name: Gu, Jie
name: Huang, Min-xin
name: Kashani-Poor, Amir-Kian
name: Klemm, Albrecht
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Algebraic Geometry (math.AG)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: F-theory compactifications on appropriate local elliptic Calabi-Yau manifolds engineer six dimensional superconformal field theories and their mass deformations. The partition function $Z_{top}$ of the refined topological string on these geometries captures the particle BPS spectrum of this class of theories compactified on a circle. Organizing $Z_{top}$ in terms of contributions $Z_β$ at base degree $β$ of the elliptic fibration, we find that these, up to a multiplier system, are meromorphic Jacobi forms of weight zero with modular parameter the Kaehler class of the elliptic fiber and elliptic parameters the couplings and mass parameters. The indices with regard to the multiple elliptic parameters are fixed by the refined holomorphic anomaly equations, which we show to be completely determined from knowledge of the chiral anomaly of the corresponding SCFT. We express $Z_β$ as a quotient of weak Jacobi forms, with a universal denominator inspired by its pole structure as suggested by the form of $Z_{top}$ in terms of 5d BPS numbers. The numerator is determined by modularity up to a finite number of coefficients, which we prove to be fixed uniquely by imposing vanishing conditions on 5d BPS numbers as boundary conditions. We demonstrate the feasibility of our approach with many examples, in particular solving the E-string and M-string theories including mass deformations, as well as theories constructed as chains of these. We make contact with previous work by showing that spurious singularities are cancelled when the partition function is written in the form advocated here. Finally, we use the BPS invariants of the E-string thus obtained to test a generalization of the Goettsche-Nakajima-Yoshioka $K$-theoretic blowup equation, as inspired by the Grassi-Hatsuda-Marino conjecture, to generic local Calabi-Yau threefolds.
description: 64 pages; v2: typos corrected
Limits to single photon transduction by a single atom: Non-Markov theory
Creators: name: Yang, Li-Ping
name: Tang, Hong X.
name: Jacob, Zubin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Atomic Physics (physics.atom-ph)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Single atoms form a model system for understanding the limits of single photon detection. Here, we develop a non-Markov theory of single-photon absorption by a two-level atom to place limits on the absorption (transduction) time. We show the existence of a finite rise time in the probability of excitation of the atom during the absorption event which is infinitely fast in previous Markov theories. This rise time is governed by the bandwidth of the atom-field interaction spectrum and leads to a fundamental jitter in time-stamping the absorption event. Our theoretical framework captures both the weak and strong atom-field coupling regimes and sheds light on the spectral matching between the interaction bandwidth and single photon Fock state pulse spectrum. Our work opens questions whether such jitter in the absorption event can be observed in a multi-mode realistic single photon detector. Finally, we also shed light on the fundamental differences between linear and nonlinear detector outputs for single photon Fock state vs. coherent state pulses.
description: 10 pages, 6 figures
Stochastic Runtime Analysis of a Cross Entropy Algorithm for Traveling Salesman Problems
Creators: name: Wu, Zijun
name: Moehring, Rolf
name: Lai, Jianhui
Publisher: name: arXiv
Year: 2016
Subjects: subject: Data Structures and Algorithms (cs.DS)
subject: Artificial Intelligence (cs.AI)
subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: This article analyzes the stochastic runtime of a Cross-Entropy Algorithm on two classes of traveling salesman problems. The algorithm shares main features of the famous Max-Min Ant System with iteration-best reinforcement. For simple instances that have a $\{1,n\}$-valued distance function and a unique optimal solution, we prove a stochastic runtime of $O(n^{6+ε})$ with the vertex-based random solution generation, and a stochastic runtime of $O(n^{3+ε}\ln n)$ with the edge-based random solution generation for an arbitrary $ε\in (0,1)$. These runtimes are very close to the known expected runtime for variants of Max-Min Ant System with best-so-far reinforcement. They are obtained for the stronger notion of stochastic runtime, which means that an optimal solution is obtained in that time with an overwhelming probability, i.e., a probability tending exponentially fast to one with growing problem size. We also inspect more complex instances with $n$ vertices positioned on an $m\times m$ grid. When the $n$ vertices span a convex polygon, we obtain a stochastic runtime of $O(n^{3}m^{5+ε})$ with the vertex-based random solution generation, and a stochastic runtime of $O(n^{2}m^{5+ε})$ for the edge-based random solution generation. When there are $k = O(1)$ many vertices inside a convex polygon spanned by the other $n-k$ vertices, we obtain a stochastic runtime of $O(n^{4}m^{5+ε}+n^{6k-1}m^ε)$ with the vertex-based random solution generation, and a stochastic runtime of $O(n^{3}m^{5+ε}+n^{3k}m^ε)$ with the edge-based random solution generation. These runtimes are better than the expected runtime for the so-called $(μ\!+\!λ)$ EA reported in a recent article, and again obtained for the stronger notion of stochastic runtime.
description: 40 pages, 7 figures
Lefschetz duality for intersection (co)homology
Creators: name: Saralegi-Aranguren, Martintxo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Algebraic Topology (math.AT)
subject: FOS: Mathematics
subject: 55N33, 55M05, 57N80

description: We prove the Lefschetz duality for intersection (co)homology in the framework of $\partial$-pesudomanifolds. We work with general perversities and without restriction on the coefficient ring.
The Structure of the Broad-Line Region In Active Galactic Nuclei. II. Dynamical Modeling of Data from the AGN10 Reverberation Mapping Campaign
Creators: name: Grier, C. J.
name: Pancoast, A.
name: Barth, A. J.
name: Fausnaugh, M. M.
name: Brewer, B. J.
name: Treu, T.
name: Peterson, B. M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We present inferences on the geometry and kinematics of the broad-Hbeta line-emitting region in four active galactic nuclei monitored as a part of the fall 2010 reverberation mapping campaign at MDM Observatory led by the Ohio State University. From modeling the continuum variability and response in emission-line profile changes as a function of time, we infer the geometry of the Hbeta- emitting broad line regions to be thick disks that are close to face-on to the observer with kinematics that are well-described by either elliptical orbits or inflowing gas. We measure the black hole mass to be log (MBH) = 7.25 (+/-0.10) for Mrk 335, 7.86 (+0.20, -0.17) for Mrk 1501, 7.84 (+0.14, -0.19) for 3C 120, and 6.92 (+0.24, -0.23) for PG 2130+099. These black hole mass measurements are not based on a particular assumed value of the virial scale factor f, allowing us to compute individual f factors for each target. Our results nearly double the number of targets that have been modeled in this manner, and investigate the properties of a more diverse sample by including previously modeled objects. We measure an average scale factor f in the entire sample to be log10(f) = 0.54 +/- 0.17 when the line dispersion is used to characterize the line width, which is consistent with values derived using the normalization of the MBH-sigma relation. We find that the scale factor f for individual targets is likely correlated with the black hole mass, inclination angle, and opening angle of the broad line region but we do not find any correlation with the luminosity.
description: 19 pages, 13 Figures. Accepted for publication in ApJ
Frustrated Spin One On A Diamond Lattice
Creators: name: Chamorro, J. R.
name: Ge, L.
name: Flynn, J.
name: Subramanian, M.
name: Mourigal, M.
name: McQueen, T. M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report the discovery of a spin one diamond lattice in NiRh2O4. This spinel undergoes a cubic to tetragonal phase transition at T = 440 K that leaves all nearest neighbor interactions equivalent. In the tetragonal phase, magnetization measurements show a Ni2+ effective moment of p(eff) = 3.3(1) and dominant antiferromagnetic interactions with Θ(CW) = -11.3(7) K. No phase transition to a long-range magnetically ordered state is observed by specific heat measurements down to T = 0.1 K. Inelastic neutron scattering measurements on sub-stoichiometric NiRh2O4 reveal possible valence-bond behavior and show no visible signs of magnetic ordering. NiRh2O4 provides a platform on which to explore the previously unknown and potentially rich physics of spin one interacting on the diamond lattice, including the realization of theoretically predicted quantum spin liquid and topological paramagnet states.
title: Superposition Reasoning About Quantied Bitvector Formulas
Creators: name: Damestani, David
Publisher: name: TU Wien
Year: 2023
Subjects: subject: automate reasoning
subject: quantified bitvectors
subject: memory reasoning
subject: first-order theorem proving

description: Wir beschreiben die Erweiterungen des Theorembeweisers in Logik erster Ordnung Vampire, um Theoreme in der Theorie der Bitvektoren fester Größe zu beweisen, möglicherweise mit Quantoren. Es werden sowohl Details zur Erweiterung des Parsers von Vampire als auch des Argumentationsverfahren von Vampire gegeben. Wir präsentieren unsere experimentellen Ergebnisse, indem wir unseren Ansatz mit SMT-Löser vergleichen und evaluiren. Unsere Experimente berichten auch über einige Beispiele, die nur durch unseren Arbeit bewiesen werden können.
description: We describe extensions to the first-order theorem prover Vampire for proving theorems in the theory of fixed-sized bitvectors, possibly with quantifiers. Details are given on extending both the parser of Vampire as well as the theory reasoning framework of Vampire. We present our experimental results by evaluating and comparing our approach to SMT solvers. Our experiments report also on a few examples that can be solved only by our work.
Quantum Potential induced UV-IR coupling in Analogue Hawking radiation: From Bose-Einstein Condensates to canonical acoustic black holes
Creators: name: Sarkar, Supratik
name: Bhattacharyay, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Other Condensed Matter (cond-mat.other)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: Arising out of a Non-local non-relativistic BEC, we present an Analogue gravity model upto $\mathcal{O}(ξ^{2})$ accuracy in the presence of the quantum potential term for a canonical acoustic BH in $(3+1)$-d spacetime where the series solution of the free minimally coupled KG equation for the large length scale massive scalar modes is derived. We systematically address the issues of the presence of the quantum potential term being the root cause of a UV-IR coupling between short wavelength `primary' modes which are supposedly Hawking radiated through the sonic horizon and the large wavelength `secondary' modes. In the quantum gravity experiments of analogue Hawking radiation in the laboratory, this UV-IR coupling is inevitable and one can not get rid of these large wavelength excitations which would grow over space by gaining energy from the short wavelength Hawking radiated modes. We identify the characteristic feature in the growth rate(s) that would distinguish these primary and secondary modes.
description: 22 pages, 0 figures, version-3