cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Combinatorial Entropy Power Inequalities: A Preliminary Study of the Stam region
Creators: name: Madiman, Mokshay
name: Ghassemi, Farhad
Publisher: name: arXiv
Year: 2017
Subjects: subject: Probability (math.PR)
subject: Information Theory (cs.IT)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: We initiate the study of the Stam region, defined as the subset of the positive orthant in $\mathbb{R}^{2^n-1}$ that arises from considering entropy powers of subset sums of $n$ independent random vectors in a Euclidean space of finite dimension. We show that the class of fractionally superadditive set functions provides an outer bound to the Stam region, resolving a conjecture of A. R. Barron and the first author. On the other hand, the entropy power of a sum of independent random vectors is not supermodular in any dimension. We also develop some qualitative properties of the Stam region, showing for instance that its closure is a logarithmically convex cone.
description: 16 pages
title: Geochronology, Geochemistry, and Geodynamic Implications of Permo-Triassic Back-Arc Basin Successions in the North Pamir, Central Asia
Creators: name: Rembe, Johannes
name: Sobel, Edward R.
name: Kley, Jonas
name: Terbishalieva, Baiansulu
name: Musiol, Antje
name: Chen, Jie
name: Zhou, Renjie
Publisher: name: Universitätsverlag Potsdam
Year: 2023
Subjects: subject: 550 Geowissenschaften

description: The Permo-Triassic period marks the time interval between Hercynian (Variscan) orogenic events in the Tien Shan and the North Pamir, and the Cimmerian accretion of the Gondwana-derived Central and South Pamir to the southern margin of the Paleo-Asian continent. A well-preserved Permo-Triassic volcano-sedimentary sequence from the Chinese North Pamir yields important information on the geodynamic evolution of Asia’s pre-Cimmerian southern margin. The oldest volcanic rocks from that section are dated to the late Guadalupian epoch by a rhyolite and a dacitic dike that gave zircon U-Pb ages of ~260 Ma. Permian volcanism was largely pyroclastic and mafic to intermediate. Upsection, a massive ignimbritic crystal tuff in the Chinese Qimgan valley was dated to 244.1 +/- 1.1 Ma, a similar unit in the nearby Gez valley to 245 +/- 11 Ma, and an associated rhyolite to 233.4 +/- 1.1 Ma. Deposition of the locally ~200 m thick crystal tuff unit follows an unconformity and marks the onset of intense, mainly mafic to intermediate, calc-alkaline magmatic activity. Triassic volcanic activity in the North Pamir was coeval with the major phase of Cimmerian intrusive activity in the Karakul-Mazar arc-accretionary complex to the south, caused by northward subduction of the Paleo-Tethys. It also coincided with the emplacement of basanitic and carbonatitic dikes and a thermal event in the South Tien Shan, to the north of our study area. Evidence for arc-related magmatic activity in a back-arc position provides strong arguments for back-arc extension or transtension and basin formation. This puts the Qimgan succession in line with a more than 1000 km long realm of extensional Triassic back-arc basins known from the North Pamir in the Kyrgyz Altyn Darya valley (Myntekin formation), the North Pamir of Tajikistan and Afghanistan, and the Afghan Hindukush (Doab formation) and further west from the Paropamisus and Kopet Dag (Aghdarband, NE Iran).
description: Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1309
The adiabatic theorem and linear response theory for extended quantum systems
Creators: name: Bachmann, Sven
name: De Roeck, Wojciech
name: Fraas, Martin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: The adiabatic theorem refers to a setup where an evolution equation contains a time-dependent parameter whose change is very slow, measured by a vanishing parameter $ε$. Under suitable assumptions the solution of the time-inhomogenous equation stays close to an instantaneous fixpoint. In the present paper, we prove an adiabatic theorem with an error bound that is independent of the number of degrees of freedom. Our setup is that of quantum spin systems where the manifold of ground states is separated from the rest of the spectrum by a spectral gap. One important application is the proof of the validity of linear response theory for such extended, genuinely interacting systems. In general, this is a long-standing mathematical problem, which can be solved in the present particular case of a gapped system, relevant e.g.~for the integer quantum Hall effect.
description: 25 pages; v1-->v2 minor typos, change in abstract, references; v2-->v3 remark added after main theorem on p.6; v3-->v4 Lemma 4.8 added, minor changes, one additional reference
A Convergent Crank-Nicolson Galerkin Scheme for the Benjamin-Ono Equation
Creators: name: Galtung, Sondre Tesdal
Publisher: name: arXiv
Year: 2016
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics
subject: 35Q53, 65M60 (Primary), 35Q51, 65M12 (Secondary)

description: In this paper we prove the convergence of a Crank-Nicolson type Galerkin finite element scheme for the initial value problem associated to the Benjamin-Ono equation. The proof is based on a recent result for a similar discrete scheme for the Korteweg-de Vries equation and utilizes a local smoothing effect to bound the $H^{1/2}$-norm of the approximations locally. This enables us to show that the scheme converges strongly in $L^{2}(0,T;L^{2}_{\text{loc}}(\mathbb{R}))$ to a weak solution of the equation for initial data in $L^{2}(\mathbb{R})$ and some $T > 0$. Finally we illustrate the method with some numerical examples.
description: 25 pages, 1 figure, accepted for publication in Discrete and Continuous Dynamical Systems - Series A
Probing the excited-state quantum phase transition through statistics of Loschmidt echo and quantum work
Creators: name: Wang, Qian
name: Quan, H. T.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: By analyzing the probability distributions of the Loschmidt echo (LE) and quantum work, we examine the nonequilibrium effects of a quantum many-body system, which exhibits an excited-state quantum phase transition (ESQPT). We find that depending on the value of the controlling parameter the distribution of the LE displays different patterns. At the critical point of the ESQPT, both the averaged LE and the averaged work show a cusplike shape. Furthermore, by employing the finite-size scaling analysis of the averaged work, we obtain the critical exponent of the ESQPT. Finally, we show that at the critical point of ESQPT the eigenstate is a highly localized state, further highlighting the influence of the ESQPT on the properties of the many-body system.
description: 10 pages, 13 figures; accepted for publication in Physical Review E
Measurements of the charm jet cross section and nuclear modification factor in pPb collisions at sqrt(s[NN]) = 5.02 TeV
Creators: name: CMS Collaboration
Publisher: name: arXiv
Year: 2016
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: The CMS Collaboration presents the first measurement of the differential cross section of jets from charm quarks produced in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of sqrt(s[NN]) = 5.02 TeV, as well as results from charm quark jets in proton-proton (pp) collisions at sqrt(s) = 2.76 and 5.02 TeV. By comparing the yields of the pPb and pp collision systems at the same energy, a nuclear modification factor for charm jets from 55 to 400 GeV/c in pPb collisions at sqrt(s[NN]) = 5.02 TeV of R[pA] = 0.92 +/- 0.07 (stat) +/- 0.11 (syst) is obtained. This is consistent with an absence of final-state energy loss for charm quarks in pPb collisions. In addition, the fraction of jets coming from charm quarks is found to be consistent with that predicted by PYTHIA 6 for pp collisions at sqrt(s)= 2.76 and 5.02 TeV, and is independent of the jet transverse momentum from 55 to 400 GeV/c.
description: Replaced with the published version. Added the journal reference and DOI. All the figures can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/HIN-15-012 (CMS Public Pages)
Multinomial method for option pricing under Variance Gamma
Creators: name: Cantarutti, Nicola
name: Guerra, João
Publisher: name: arXiv
Year: 2017
Subjects: subject: Pricing of Securities (q-fin.PR)
subject: Computational Finance (q-fin.CP)
subject: Mathematical Finance (q-fin.MF)
subject: FOS: Economics and business
subject: 91G20, 60G51, 60G57, 60J75, 60J22, 60J10, 45K05

description: This paper presents a multinomial method for option pricing when the underlying asset follows an exponential Variance Gamma process. The continuous time Variance Gamma process is approximated by a discrete time Markov chain with the same firsts four cumulants. This approach is particularly convenient for pricing American and Bermudan options, which can be exercised at any time up to expiration date. Numerical computations of European and American options are presented, and compared with results obtained with finite differences methods and with the Black Scholes model.
A non-parametric consistency test of the $Λ$CDM model with Planck CMB data
Creators: name: Aghamousa, Amir
name: Hamann, Jan
name: Shafieloo, Arman
Publisher: name: arXiv
Year: 2017
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: Non-parametric reconstruction methods, such as Gaussian process (GP) regression, provide a model-independent way of estimating an underlying function and its uncertainty from noisy data. We demonstrate how GP-reconstruction can be used as a consistency test between a given data set and a specific model by looking for structures in the residuals of the data with respect to the model's best-fit. Applying this formalism to the Planck temperature and polarisation power spectrum measurements, we test their global consistency with the predictions of the base $Λ$CDM model. Our results do not show any serious inconsistencies, lending further support to the interpretation of the base $Λ$CDM model as cosmology's gold standard.
description: 11 pages, 4 figures; v2: matches version published in JCAP
Small unions of affine subspaces and skeletons via Baire category
Creators: name: Chang, Alan
name: Csörnyei, Marianna
name: Héra, Kornélia
name: Keleti, Tamás
Publisher: name: arXiv
Year: 2017
Subjects: subject: Metric Geometry (math.MG)
subject: Classical Analysis and ODEs (math.CA)
subject: FOS: Mathematics
subject: 28A78, 54E52

description: Our aim is to find the minimal Hausdorff dimension of the union of scaled and/or rotated copies of the $k$-skeleton of a fixed polytope centered at the points of a given set. For many of these problems, we show that a typical arrangement in the sense of Baire category gives minimal Hausdorff dimension. In particular, this proves a conjecture of R. Thornton. Our results also show that Nikodym sets are typical among all sets which contain, for every point x of R^n, a punctured hyperplane H\{x} through x. With similar methods we also construct a Borel subset of R^n of Lebesgue measure zero containing a hyperplane at every positive distance from every point.
description: to appear in Advances in Mathematics
MUSE: Modularizing Unsupervised Sense Embeddings
Creators: name: Lee, Guang-He
name: Chen, Yun-Nung
Publisher: name: arXiv
Year: 2017
Subjects: subject: Computation and Language (cs.CL)
subject: FOS: Computer and information sciences

description: This paper proposes to address the word sense ambiguity issue in an unsupervised manner, where word sense representations are learned along a word sense selection mechanism given contexts. Prior work focused on designing a single model to deliver both mechanisms, and thus suffered from either coarse-grained representation learning or inefficient sense selection. The proposed modular approach, MUSE, implements flexible modules to optimize distinct mechanisms, achieving the first purely sense-level representation learning system with linear-time sense selection. We leverage reinforcement learning to enable joint training on the proposed modules, and introduce various exploration techniques on sense selection for better robustness. The experiments on benchmark data show that the proposed approach achieves the state-of-the-art performance on synonym selection as well as on contextual word similarities in terms of MaxSimC.
Search for the third-generation scalar leptoquarks and heavy right-handed neutrinos in final states with two tau leptons and two jets in proton-proton collisions at sqrt(s) = 13 TeV
Creators: name: CMS Collaboration
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: A search is performed for third-generation scalar leptoquarks and heavy right-handed neutrinos in events containing one electron or muon, one hadronically decaying tau lepton, and at least two jets, using a sqrt(s) = 13 TeV pp collision data sample corresponding to an integrated luminosity of 12.9 inverse femtobarns collected with the CMS detector at the LHC in 2016. The number of observed events is found to be in agreement with the standard model prediction. A limit is set at 95% confidence level on the product of the leptoquark pair production cross section and beta squared where beta is the branching fraction of leptoquark decay to a tau lepton and a bottom quark. Assuming beta = 1, third-generation leptoquarks with masses below 850 GeV are excluded at 95% confidence level. An additional search based on the same event topology involves heavy right-handed neutrinos, N[R], and right-handed W bosons, W[R] , arising in a left-right symmetric extension of the standard model. In this search, W[R] bosons are assumed to decay to a tau lepton and N[R] followed by the decay of the N[R] to a tau lepton and an off-shell W[R] boson. Assuming the mass of the right-handed neutrino to be half of the mass of the right-handed W boson, W[R] boson masses below 2.9 TeV are excluded at 95% confidence level. These results improve on the limits from previous searches for third-generation leptoquarks and heavy right-handed neutrinos with tau leptons in the final state.
description: Replaced with the published version. Added the journal reference and DOI. All the figures and tables, including additional supplemental figures, can be found at http://cms-results.web.cern.ch/cms-results/public-results/publications/EXO-16-023
Non-collinear magnetic structure and multipolar order in Eu$_2$Ir$_2$O$_7$
Creators: name: Wang, Yilin
name: Weng, Hongming
name: Fu, Liang
name: Dai, Xi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The magnetic properties of the pyrochlore iridate material Eu$_2$Ir$_2$O$_7$ (5$d^5$) have been studied based on the first principle calculations, where the crystal field splitting $Δ$, spin-orbit coupling (SOC) $λ$ and Coulomb interaction $U$ within Ir 5$d$ orbitals are all playing significant roles. The ground state phase diagram has been obtained with respect to the strength of SOC and Coulomb interaction $U$, where a stable anti-ferromagnetic ground state with all-in/all-out (AIAO) spin structure has been found. Besides, another anti-ferromagnetic states with close energy to AIAO have also been found to be stable. The calculated nonlinear magnetization of the two stable states both have the d-wave pattern but with a $π/4$ phase difference, which can perfectly explain the experimentally observed nonlinear magnetization pattern. Compared with the results of the non-distorted structure, it turns out that the trigonal lattice distortion is crucial for stabilizing the AIAO state in Eu$_2$Ir$_2$O$_7$. Furthermore, besides large dipolar moments, we also find considerable octupolar moments in the magnetic states.
description: 6 pages, 4 figures, supplemental material is included in the source file, accepted for publication in PRL
Global Evolution of an Accretion Disk with Net Vertical Field: Coronal Accretion, Flux Transport, and Disk Winds
Creators: name: Zhu, Zhaohuan
name: Stone, James M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We report new global ideal MHD simulations for thin accretion disks (with thermal scale height H/R=0.1 and 0.05) threaded by net vertical magnetic fields. Our computations span three orders of magnitude in radius, extend all the way to the pole, and are evolved for more than one viscous time over the inner decade in radius. Static mesh refinement is used to properly resolve MRI. We find that:(1) inward accretion occurs mostly in the upper magnetically dominated regions of the disk, similar to the predictions from some previous analytical work and the "coronal accretion" in previous GRMHD simulations. Rapid inflow in the upper layers combined with slow outflow at the midplane creates strong $Rϕ$ and $zϕ$ stresses in the mean field; the vertically integrated $α\sim 0.5-1$ when the initial field has $β_{0}=10^3$ at the midplane. (2) A quasi-static global field geometry is established in which flux transport by inflows at the surface is balanced by turbulent diffusion. The field is strongly pinched inwards at the surface. A steady-state advection-diffusion model, with turbulent magnetic Prandtl number of order unity, reproduces this geometry well. (3) Weak unsteady disk winds are launched at $z/R\sim1$ with the Alfven radius $R_{A}/R_{0}\sim3$. Although the wind is episodic, the time averaged properties are well described by steady wind theory. Wind is not efficient at transporting angular momentum. Even with $β_{0}=10^3$, only 5% of the angular momentum transport is driven by torque from the wind, and the wind mass flux from the inner decade of radius is only $\sim$ 0.4% of the mass accretion rate. With weaker fields or thinner disks, the wind contributes even less. (4) Most of the disk accretion is driven by the $Rϕ$ stress from the MRI and global magnetic fields. Our simulations have many applications to astrophysical accretion disk systems.
description: Two additional figures, accepted by the AAS Journals
Detecting axions via induced electron spin precession
Creators: name: Alexander, Stephon
name: Sims, Robert
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We propose a new window to detect axion-like particle (ALP) dark matter from electrically charged fermions, such as electrons and quarks. We specifically consider a direct interaction between the axion and the electron and find that the non-relativistic quantum dynamics induces a spin precession due to the axion and is enhanced by the application of an external electric field. This precession gives a change in magnetic flux which under certain circumstances can yield a detectable signal for SQUID magnetometers.
description: v4: Matches version to appear in PRD
An Aposteriorical Clusterability Criterion for $k$-Means++ and Simplicity of Clustering
Creators: name: Kłopotek, Mieczysław A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: We define the notion of a well-clusterable data set combining the point of view of the objective of $k$-means clustering algorithm (minimising the centric spread of data elements) and common sense (clusters shall be separated by gaps). We identify conditions under which the optimum of $k$-means objective coincides with a clustering under which the data is separated by predefined gaps. We investigate two cases: when the whole clusters are separated by some gap and when only the cores of the clusters meet some separation condition. We overcome a major obstacle in using clusterability criteria due to the fact that known approaches to clusterability checking had the disadvantage that they are related to the optimal clustering which is NP hard to identify. Compared to other approaches to clusterability, the novelty consists in the possibility of an a posteriori (after running $k$-means) check if the data set is well-clusterable or not. As the $k$-means algorithm applied for this purpose has polynomial complexity so does therefore the appropriate check. Additionally, if $k$-means++ fails to identify a clustering that meets clusterability criteria, with high probability the data is not well-clusterable.
description: 58 pages
Non-negative matrix factorization for self-calibration of photometric redshift scatter in weak lensing surveys
Creators: name: Zhang, Le
name: Yu, Yu
name: Zhang, Pengjie
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Photo-z error is one of the major sources of systematics degrading the accuracy of weak lensing cosmological inferences. Zhang et al. (2010) proposed a self-calibration method combining galaxy-galaxy correlations and galaxy-shear correlations between different photo-z bins. Fisher matrix analysis shows that it can determine the rate of photo-z outliers at a level of 0.01-1% merely using photometric data and do not rely on any prior knowledge. In this paper, we develop a new algorithm to implement this method by solving a constrained nonlinear optimization problem arising in the self-calibration process. Based on the techniques of fixed-point iteration and non-negative matrix factorization, the proposed algorithm can efficiently and robustly reconstruct the scattering probabilities between the true-z and photo-z bins. The algorithm has been tested extensively by applying it to mock data from simulated stage IV weak lensing projects. We find that the algorithm provides a successful recovery of the scatter rates at the level of 0.01-1%, and the true mean redshifts of photo-z bins at the level of 0.001, which may satisfy the requirements in future lensing surveys.
description: 12 pages, 6 figures. Accepted for publication in ApJ. Updated to match the published version
Pseudo-topological Quasi-local Energy of Torsion Gravity
Creators: name: Ko, Sheng-Lan
name: Lin, Feng-Li
name: Ning, Bo
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Torsion gravity is a natural extension to Einstein gravity in the presence of the fermion matter sources. In this paper we adopt Wald's covariant method of Noether charge to construct the quasi-local energy of the Einstein-Cartan-fermion system, and find that its explicit expression is formally independent of the coupling constant between torsion and axial current. This seemingly topological nature is unexpected and is reminiscent of similar nature of quantum Hall effect and topological insulator. However, the coupling dependence does enter when evaluating it on-shell, and thus the topological nature is pseudo. Based on the expression of the quasi-local energy, we evaluate it for a particular solution on the entanglement wedge and find the agreement with the holographic relative entropy obtained before. This shows that the equivalence of these two quantities in the Einstein-Cartan-fermion system. Moreover, the quasi-local energy in this case is not always positive definite so that it provides an example of swampland in torsion gravity. Based on the covariant Noether charge, we also derive the nonzero fermion effect on Komar angular momentum. The implication of our results to the tests of torsion gravity in the future gravitational wave astronomy is also discussed.
description: 30 pages; v2. new discussion section on GW added and texts restructured to match PRD version, but main conclusion remains intact
Revisiting arithmetic solutions to the $W=0$ condition
Creators: name: Kanno, Keita
name: Watari, Taizan
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The gravitino mass is expected not to be much smaller than the Planck scale for a large fraction of vacua in flux compactifications. There is no continuous parameter to tune even by hand, and it seems that the gravitino mass can be small only as a result of accidental cancellation among period integrals weighted by integer-valued flux quanta. DeWolfe et.al. (2005) proposed to pay close attention to vacua where the Hodge decomposition is possible within a number field, so that the precise cancellation takes place as a result of algebra. We focus on a subclass of those vacua---those with complex multiplications---and explore more on the idea in this article. It turns out, in Type IIB compactifications, that those vacua admit non-trivial supersymmetric flux configurations if and only if the reflex field of the Weil intermediate Jacobian is isomorphic to the quadratic imaginary field generated by the axidilaton vacuum expectation value. We also found that flux statistics is highly enriched on such vacua, as F-term conditions become linearly dependent.
description: 28+25 pages, a few references added and a few typos corrected
Nonabelian Cohen-Lenstra Moments
Creators: name: Wood, Melanie Matchett
name: Wood, Philip Matchett
Publisher: name: arXiv
Year: 2017
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: In this paper we give a conjecture for the average number of unramified $G$-extensions of a quadratic field for any finite group $G$. The Cohen-Lenstra heuristics are the specialization of our conjecture to the case that $G$ is abelian of odd order. We prove a theorem towards the function field analog of our conjecture, and give additional motivations for the conjecture including the construction of a lifting invariant for the unramified $G$-extensions that takes the same number of values as the predicted average and an argument using the Malle-Bhargava principle. We note that for even $|G|$, corrections for the roots of unity in $\mathbb{Q}$ are required, which can not be seen when $G$ is abelian.
description: main article by Melanie Matchett Wood, appendix by Melanie Matchett Wood and Philip Matchett Wood, to appear in Duke Mathematical Journal
Probing the Gas Density in our Galactic Center: Moving Mesh Simulations of G2
Creators: name: Steinberg, Elad
name: Sari, Re'em
name: Gnat, Orly
name: Gillessen, Stefan
name: Plewa, Philipp
name: Genzel, Reinhard
name: Eisenhauer, Frank
name: Ott, Thomas
name: Pfuhl, Oliver
name: Habibi, Maryam
name: Waisberg, Idel
name: von Fellenberg, Sebastiano
name: Dexter, Jason
name: Bauböck, Michi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: The G2 object has recently passed its pericenter passage in our Galactic Center. While the $Br_γ$ emission shows clear signs of tidal interaction, the change in the observed luminosity is only of about a factor of 2, in contention with all previous predictions. We present high resolution simulations performed with the moving mesh code, RICH, together with simple analytical arguments that reproduce the observed $Br_γ$ emission. In our model, G2 is a gas cloud that undergoes tidal disruption in a dilute ambient medium. We find that during pericenter passage, the efficient cooling of the cloud results in a vertical collapse, compressing the cloud by a factor of $\sim5000$. By properly taking into account the ionization state of the gas, we find that the cloud is UV starved and are able to reproduce the observed $Br_γ$ luminosity. For densities larger than $\approx500\;\mathrm{cm}^{-3}$ at pericenter, the cloud fragments, due to cooling instabilities and the emitted radiation is inconsistent with observations. For lower densities, the cloud survives the pericenter passage intact and its emitted radiation matches the observed lightcurve. From the duration of $Br_γ$ emission which contains both redshifted and blueshifted components, we show that the cloud is not spherical but rather elongated with a size ratio of 4 at year 2001. The simulated cloud's elongation grows as it travels towards pericenter and is consistent with observations, due to viewing angles. The simulation is also consistent with having a spherical shape at apocenter.
Hierarchical invasion of cooperation in complex networks
Creators: name: Vilone, Daniele
name: Capraro, Valerio
name: Ramasco, José J.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Physics and Society (physics.soc-ph)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: The emergence and survival of cooperation is one of the hardest problems still open in science. Several factors such as the existence of punishment, fluctuations in finite systems, repeated interactions and the formation of prestige may all contribute to explain the counter-intuitive prevalence of cooperation in natural and social systems. The characteristics of the interaction networks have been also signaled as an element favoring the persistence of cooperators. Here we consider the invasion dynamics of cooperative behaviors in complex topologies. The invasion of a heterogeneous network fully occupied by defectors is performed starting from nodes with a given number of connections (degree) $k_0$. The system is then evolved within a Prisoner's Dilemma game and the outcome is analyzed as a function of $k_0$ and the degree $k$ of the nodes adopting cooperation. Carried out using both numerical and analytical approaches, our results show that the invasion proceeds following preferentially a hierarchical order in the nodes from those with higher degree to those with lower degree. However, the invasion of cooperation will succeed only when the initial cooperators are numerous enough to form a cluster from which cooperation can spread. This implies that the initial condition must be a suitable equilibrium between high degree and high numerosity, which usually takes place, when possible, at intermediate values of $k_0$. These findings have potential applications, as they suggest that, in order to promote cooperative behavior on complex networks, one should infect with cooperators \emph{high but not too high} degree nodes.
description: 19 pages, 9 figures
Complexity and Boost Symmetry
Creators: name: Zhao, Ying
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We find that the time dependence of holographic complexity is controlled by the Rindler boost symmetry across the horizon. By studying the collision energy experienced by an infalling object, we see the breaking of this boost symmetry is closely related to firewalls, which in turn shows the connection between the time dependence of complexity and firewalls. We further identify the black and white hole interiors as two tapes storing different parts of the minimal circuit preparing the state. Depending on whether the quantum gates are being laid on the tape at a particular moment, each tape can be in two states: working, or locked. We interpret the existence of firewalls as the locking of tapes.
description: 28 pages, 27 figures
From Coarse-Graining to Holography in Loop Quantum Gravity
Creators: name: Livine, Etera R.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We discuss the relation between coarse-graining and the holographic principle in the framework of loop quantum gravity and ask the following question: when we coarse-grain arbitrary spin network states of quantum geometry, are we integrating out physical degrees of freedom or gauge degrees of freedom? Focusing on how bulk spin network states for bounded regions of space are projected onto boundary states, we show that all possible boundary states can be recovered from bulk spin networks with a single vertex in the bulk and a single internal loop attached to it. This partial reconstruction of the bulk from the boundary leads us to the idea of realizing the Hamiltonian constraints at the quantum level as a gauge equivalence reducing arbitrary spin network states to one-loop bulk states. This proposal of "dynamics through coarse-graining" would lead to a one-to-one map between equivalence classes of physical states under gauge transformations and boundary states, thus defining holographic dynamics for loop quantum gravity.
description: 6 pages; v2: added explicit examples of holographic dynamics with the BF case and an "area-preserving" dynamics
Computation of the asymptotic states of modulated open quantum systems with a numerically exact realization of the quantum trajectory method
Creators: name: Volokitin, V.
name: Liniov, A.
name: Meyerov, I.
name: Hartmann, M.
name: Ivanchenko, M.
name: Hänggi, P.
name: Denisov, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Quantum systems out of equilibrium are presently a subject of active research, both in theoretical and experimental domains. In this work we consider time-periodically modulated quantum systems which are in contact with a stationary environment. Within the framework of a quantum master equation, the asymptotic states of such systems are described by time-periodic density operators. Resolution of these operators constitutes a non-trivial computational task. To go beyond the current size limits, we use the quantum trajectory method which unravels master equation for the density operator into a set of stochastic processes for wave functions. The asymptotic density matrix is calculated by performing a statistical sampling over the ensemble of quantum trajectories, preceded by a long transient propagation. We follow the ideology of event-driven programming and construct a new algorithmic realization of the method. The algorithm is computationally efficient, allowing for long 'leaps' forward in time, and is numerically exact in the sense that, being given the list of uniformly distributed (on the unit interval) random numbers, $\{η_1, η_2,...,η_n\}$, one could propagate a quantum trajectory (with $η_i$'s as norm thresholds) in a numerically exact way. %Since the quantum trajectory method falls into the class of standard sampling problems, performance of the algorithm %can be substantially improved by implementing it on a computer cluster. By using a scalable $N$-particle quantum model, we demonstrate that the algorithm allows us to resolve the asymptotic density operator of the model system with $N = 2000$ states on a regular-size computer cluster, thus reaching the scale on which numerical studies of modulated Hamiltonian systems are currently performed.
Rare $Λ_b\toΛl^+l^-$ and $Λ_b\toΛγ$ decays in the relativistic quark model
Creators: name: Faustov, R. N.
name: Galkin, V. O.
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: Rare $Λ_b\toΛl^+l^-$ and $Λ_b\toΛγ$ decays are investigated in the relativistic quark model based on the quark-diquark picture of baryons. The decay form factors are calculated with the account of all relativistic effects including relativistic transformations of baryon wave functions from rest to moving reference frame and the contribution of the intermediate negative energy states. The momentum transfer squared dependence of the form factors is explicitly determined in the whole accessible kinematical range. The calculated decay branching fractions, various forward-backward asymmetries for the rare decay $Λ_b\toΛμ^+μ^-$ are found to be consistent with recent detailed measurements by the LHCb Collaboration. Predictions for the $Λ_b\toΛτ^+τ^-$ decay observables are given.
description: 26 pages, 9 figures, published version
Piecewise Deterministic Markov Processes for Scalable Monte Carlo on Restricted Domains
Creators: name: Bierkens, Joris
name: Bouchard-Côté, Alexandre
name: Doucet, Arnaud
name: Duncan, Andrew B.
name: Fearnhead, Paul
name: Lienart, Thibaut
name: Roberts, Gareth
name: Vollmer, Sebastian J.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Methodology (stat.ME)
subject: Computation (stat.CO)
subject: FOS: Computer and information sciences

description: Piecewise Deterministic Monte Carlo algorithms enable simulation from a posterior distribution, whilst only needing to access a sub-sample of data at each iteration. We show how they can be implemented in settings where the parameters live on a restricted domain.
Almost finiteness for general etale groupoids and its applications to stable rank of crossed products
Creators: name: Suzuki, Yuhei
Publisher: name: arXiv
Year: 2017
Subjects: subject: Operator Algebras (math.OA)
subject: Dynamical Systems (math.DS)
subject: Group Theory (math.GR)
subject: FOS: Mathematics
subject: 46L05, 54H20

description: We extend Matui's notion of almost finiteness to general etale groupoids and show that the reduced groupoid C*-algebras of minimal almost finite groupoids have stable rank one. The proof follows a new strategy, which can be regarded as a local version of the large subalgebra argument. The following three are the main consequences of our result. (i) For any group of (local) subexponential growth and for any its minimal action admitting a totally disconnected free factor, the crossed product has stable rank one. (ii) Any countable amenable group admits a minimal action on the Cantor set all whose minimal extensions form the crossed product of stable rank one. (iii) For any amenable group, the crossed product of the universal minimal action has stable rank one.
description: Minor revision, 25 pages, to appear in IMRN
An isoperimetric inequality for diffused surfaces
Creators: name: Menne, Ulrich
name: Scharrer, Christian
Publisher: name: arXiv
Year: 2016
Subjects: subject: Differential Geometry (math.DG)
subject: Analysis of PDEs (math.AP)
subject: FOS: Mathematics
subject: 53A07 (Primary), 46E35, 49Q15 (Secondary)

description: For general varifolds in Euclidean space, we prove an isoperimetric inequality, adapt the basic theory of generalised weakly differentiable functions, and obtain several Sobolev type inequalities. We thereby intend to facilitate the use of varifold theory in the study of diffused surfaces.
description: Awaiting publication in Kodai Math. J. The final printed version will be different. 14 pages, no figures
Chiral heat wave in cold Fermi liquid and modified zero sound
Creators: name: Frenklakh, D.
name: Gorsky, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We discuss kinetic equations involving the anomalous terms responsible for the chiral anomaly. The general chiral heat wave in cold Fermi liquid is described and the modification of the anomalous zero sound at small temperature and vorticity is found.
description: 13 pages
The (Im)perfect Automation Schema: Who Is Trusted More, Automated or Human Decision Support?
Creators: name: Rieger, Tobias
name: Kugler, Luisa
name: Manzey, Dietrich
name: Roesler, Eileen
Publisher: name: SAGE Publications
Year: 2023
Subjects: subject: 300 Sozialwissenschaften::300 Sozialwissenschaften, Soziologie::301 Soziologie, Anthropologie
subject: human-automation interaction
subject: trust in automation
subject: expert systems
subject: expert-novice differences
subject: decision making

description: Objective: This study’s purpose was to better understand the dynamics of trust attitude and behavior in human-agent interaction. Background: Whereas past research provided evidence for a perfect automation schema, more recent research has provided contradictory evidence. Method: To disentangle these conflicting findings, we conducted an online experiment using a simulated medical X-ray task. We manipulated the framing of support agents (i.e., artificial intelligence (AI) versus expert versus novice) between-subjects and failure experience (i.e., perfect support, imperfect support, back-to-perfect support) within subjects. Trust attitude and behavior as well as perceived reliability served as dependent variables. Results: Trust attitude and perceived reliability were higher for the human expert than for the AI than for the human novice. Moreover, the results showed the typical pattern of trust formation, dissolution, and restoration for trust attitude and behavior as well as perceived reliability. Forgiveness after failure experience did not differ between agents. Conclusion: The results strongly imply the existence of an imperfect automation schema. This illustrates the need to consider agent expertise for human-agent interaction. Application: When replacing human experts with AI as support agents, the challenge of lower trust attitude towards the novel agent might arise.
Balancing the Migration of Virtual Network Functions with Replications in Data Centers
Creators: name: Carpio, Francisco
name: Jukan, Admela
name: Pries, Rastin
Publisher: name: arXiv
Year: 2017
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: FOS: Computer and information sciences

description: The Network Function Virtualization (NFV) paradigm is enabling flexibility, programmability and implementation of traditional network functions into generic hardware, in form of the so-called Virtual Network Functions (VNFs). Today, cloud service providers use Virtual Machines (VMs) for the instantiation of VNFs in the data center (DC) networks. To instantiate multiple VNFs in a typical scenario of Service Function Chains (SFCs), many important objectives need to be met simultaneously, such as server load balancing, energy efficiency and service execution time. The well-known \emph{VNF placement} problem requires solutions that often consider \emph{migration} of virtual machines (VMs) to meet this objectives. Ongoing efforts, for instance, are making a strong case for migrations to minimize energy consumption, while showing that attention needs to be paid to the Quality of Service (QoS) due to service interruptions caused by migrations. To balance the server allocation strategies and QoS, we propose using \emph{replications} of VNFs to reduce migrations in DC networks. We propose a Linear Programming (LP) model to study a trade-off between replications, which while beneficial to QoS require additional server resources, and migrations, which while beneficial to server load management can adversely impact the QoS. The results show that, for a given objective, the replications can reduce the number of migrations and can also enable a better server and data center network load balancing.
Stability of a $d$-dimensional thin-shell wormhole surrounded by quintessence
Creators: name: Banerjee, Ayan
name: Jusufi, Kimet
name: Bahamonde, Sebastian
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We study the stability of different higher dimensional thin--shell wormholes (HDTSW) in general relativity with a cosmological constant. We show that a $d$--dimensional thin--shell wormhole surrounded by quintessence can have three different throat geometries: spherical, planar and hyperbolic. Unlike the spherical geometry, the planar and hyperbolic geometries allow different topologies that can be interpreted as higher-dimensional domain walls or branes connecting two universes. To construct these geometries, we use the cut-and-paste procedure by joining two identical vacuum spacetime solutions. Properties such as the null energy condition and geodesics are also studied. A linear stability analysis around the static solutions is carried out. Our stability analysis takes into account a more general HDTSW geometry than previous works so it is possible to recover other well-known stability HDTSW conditions.
description: 10 pages; 3 figures; matches the accepted version, to appear in Gravitation and Cosmology
Many-body dynamics of chemically propelled nanomotors
Creators: name: Colberg, Peter H.
name: Kapral, Raymond
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: The collective behavior of chemically propelled sphere-dimer motors made from linked catalytic and noncatalytic spheres in a quasi-two-dimensional confined geometry is studied using a coarse-grained microscopic dynamical model. Chemical reactions at the catalytic spheres that convert fuel to product generate forces that couple to solvent degrees of freedom as a consequence of momentum conservation in the microscopic dynamics. The collective behavior of the many-body system is influenced by direct intermolecular interactions among the motors, chemotactic effects due to chemical gradients, hydrodynamic coupling, and thermal noise. Segregation into high and low density phases and globally homogeneous states with strong fluctuations are investigated as functions of the motor characteristics. Factors contributing to this behavior are discussed in the context of active Brownian models.
description: 13 pages, 12 figures
QCD-Aware Recursive Neural Networks for Jet Physics
Creators: name: Louppe, Gilles
name: Cho, Kyunghyun
name: Becot, Cyril
name: Cranmer, Kyle
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: Machine Learning (stat.ML)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Recent progress in applying machine learning for jet physics has been built upon an analogy between calorimeters and images. In this work, we present a novel class of recursive neural networks built instead upon an analogy between QCD and natural languages. In the analogy, four-momenta are like words and the clustering history of sequential recombination jet algorithms is like the parsing of a sentence. Our approach works directly with the four-momenta of a variable-length set of particles, and the jet-based tree structure varies on an event-by-event basis. Our experiments highlight the flexibility of our method for building task-specific jet embeddings and show that recursive architectures are significantly more accurate and data efficient than previous image-based networks. We extend the analogy from individual jets (sentences) to full events (paragraphs), and show for the first time an event-level classifier operating on all the stable particles produced in an LHC event.
description: 16 pages, 5 figures, 3 appendices, corresponding code at https://github.com/glouppe/recnn
Spectral asymptotics for infinite order pseudo-differential operators
Creators: name: Pilipović, Stevan
name: Prangoski, Bojan
name: Vindas, Jasson
Publisher: name: arXiv
Year: 2017
Subjects: subject: Spectral Theory (math.SP)
subject: Analysis of PDEs (math.AP)
subject: Functional Analysis (math.FA)
subject: FOS: Mathematics
subject: 35P20, 35S05, 46F05, 47D03

description: We study spectral properties of a class of global infinite order pseudo-differential operators and obtain the asymptotic behaviour of the spectral counting functions of such operators. Unlike their finite order counterparts, their spectral asymptotics are not of power-log-type but of log-type. The ultradistributional setting of such operators of infinite order makes the theory more complex so that the standard finite order global Weyl calculus cannot be used in this context.
description: 32 pages