cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A New Insight on Physical Phenomenology: a Review
Creators: name: Bellucci, Stefano
name: Cardone, Fabio
name: Pistella, Fabio
Publisher: name: arXiv
Year: 2020
Subjects: subject: General Physics (physics.gen-ph)
subject: FOS: Physical sciences

description: After a brief digression on the current landscape of theoretical physics and on some open questions pertaining to coherence with experimental results, still to be settled, it is shown that the properties of the Deformed Minkowski space lead to a plurality of potential physical phenomena that should occur, provided that the resulting formalisms can be considered as useful models for the descrip-tion of some aspects of physical reality. A list is given of available experimental evidences not easy to be interpreted, at present, by means of the more established models, such as the standard model with its variants aimed at overcoming its descriptive limits; these evidences could be candidates to verify the predictions stemming from the properties of the Deformed Minkowski space. The list includes: anomalies in the double-slit-like experiments; nuclear metamorphosis; torsional anten-nas, as well as the physical effect of the "geometric vacuum" (as defined in analogy with quantum vacuum), in the absence of external electromagnetic field, when crossing critical thresholds of energy parameter values, energy density in space and energy density in time.
description: 16 pages, no figures, Keywords: Tevatron; LHC; KEK; DAPHNE; Fermilab; KLOE; LEP. PACS (2010): 13.90.+i; 29.90.+r; 24.10.-i; 12.60.-i
Computational Analysis of Bubble-Structure Interactions in Near-Field Underwater Explosion
Creators: name: Ma, Wentao
name: Zhao, Xuning
name: Gilbert, Christine
name: Wang, Kevin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Applied Physics (physics.app-ph)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The response of underwater structures to a near-field explosion is coupled with the dynamics of the explosion bubble and the surrounding water. This multiphase fluid-structure interaction process is investigated using a model problem that features the yielding and collapse of a thin-walled aluminum cylinder. A recently developed computational framework that couples a compressible fluid dynamics solver with a structural dynamics solver is employed. The fluid-structure and liquid-gas interfaces are tracked using embedded boundary and level set methods. The conservation law across the interfaces is enforced by solving one-dimensional bimaterial Riemann problems. The initial pressure inside the explosion bubble is varied by two orders of magnitude in different test cases. Three different modes of collapse are discovered, including an horizontal collapse (i.e. with one lobe extending towards the explosive charge) that appears counterintuitive, yet has been observed in previous laboratory experiments. Because of the transition of modes, the time it takes for the structure to reach self-contact does not decrease monotonically as the explosion magnitude increases. The flow fields, the bubble dynamics, and the transient structural deformation are visualized to elucidate the cause of each collapse mode and the mode transitions. The result suggests that the pressure pulse resulting from the contraction of the explosion bubble has significant effect on the structure's collapse. The phase difference between the structural vibration and bubble oscillation influences the structure's mode of collapse. Furthermore, the transient structural deformation has clear effect on the bubble dynamics, leading to a two-way interaction. A liquid jet that points away from the structure is observed. Compared to the liquid jets produced by bubbles collapsing near a rigid wall, this jet is in the opposite direction.
Interacting photon pulses in Rydberg medium
Creators: name: Yang, Liu
name: He, Bing
name: Wu, Jin-Hui
name: Zhang, Zhaoyang
name: Xiao, Min
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: The understanding of dynamical evolutions of interacting photon pulses in Rydberg atomic ensemble is the prerequisite for realizing quantum devices with such system. We present an approach that efficiently simulates the dynamical processes, using a set of local functions we construct to reflect the profiles of narrowband pulses. For two counter-propagating photon pulses, our approach predicts the distinct phenomena from the widely concerned Rydberg blockade to the previously less noticed significant absorption in the anomalous dispersion regime, which can occur by respectively setting the pulse frequency to the appropriate values. Our numerical simulations also demonstrate how spatially extending photon pulses become deformed under realistic non-uniform interaction over their distributions.
description: 14 pages, 8 figures including the supplementary material; Optica in press
Stable Big Bang formation for Einstein's equations: The complete sub-critical regime
Creators: name: Fournodavlos, Grigorios
name: Rodnianski, Igor
name: Speck, Jared
Publisher: name: arXiv
Year: 2020
Subjects: subject: Analysis of PDEs (math.AP)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Mathematical Physics (math-ph)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: Primary: 83C75, Secondary: 35A21, 35Q76, 83C05, 83F05

description: For $(t,x) \in (0,\infty)\times\mathbb{T}^D$, the generalized Kasner solutions are a family of explicit solutions to various Einstein-matter systems that start out smooth but then develop a Big Bang singularity as $t \downarrow 0$, i.e., curvature blowup along a spacelike hypersurface. The family is parameterized by the Kasner exponents $\widetilde{q}_1,\cdots,\widetilde{q}_D \in \mathbb{R}$, which satisfy two algebraic constraints. There are heuristics in the mathematical physics literature, going back more than 50 years, suggesting that the Big Bang formation should be stable under perturbations of the Kasner initial data, given say at $\lbrace t = 1 \rbrace$, as long as the exponents are "sub-critical" in the following sense: $\mathop{\max_{I,J,B=1,\cdots,D}}_{I < J} \{\widetilde{q}_I+\widetilde{q}_J-\widetilde{q}_B\}<1$. Previous works have shown the stability of the singularity under stronger assumptions: 1) the Einstein-scalar field system with $D = 3$ and $\widetilde{q}_1 \approx \widetilde{q}_2 \approx \widetilde{q}_3 \approx 1/3$ or 2) the Einstein-vacuum equations for $D \geq 39$ with $\max_{I=1,\cdots,D} |\widetilde{q}_I| < 1/6$. We prove that the Kasner singularity is dynamically stable for \emph{all} sub-critical Kasner exponents, thereby justifying the heuristics in the full regime where stable monotonic-type curvature blowup is expected. We treat the $1+D$-dimensional Einstein-scalar field system for $D \geq3$ and the $1+D$ dimensional Einstein-vacuum equations for $D \geq 10$. Moreover, for the Einstein-vacuum equations in $1+3$ dimensions, where instabilities are in general expected, we prove that all singular Kasner solutions have stable Big Bangs under polarized $U(1)$-symmetric perturbations of their initial data. Our results hold for open sets of initial data in Sobolev spaces without symmetry, apart from our work on polarized $U(1)$-symmetric solutions.
description: 72 pages. This version is equivalent to the published version. Features additional details on some proofs and corrections of minor errors
Birth and Death of Chimera: Interplay of Delay and Multiplexing
Creators: name: Ghosh, Saptarshi
name: Kumar, Anil
name: Zakharova, Anna
name: Jalan, Sarika
Publisher: name: arXiv
Year: 2016
Subjects: subject: Chaotic Dynamics (nlin.CD)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: The chimera state with co-existing coherent-incoherent dynamics has recently attracted a lot of attention due to its wide applicability. We investigate non-locally coupled identical chaotic maps with delayed interactions in the multiplex network framework and find that an interplay of delay and multiplexing brings about an enhanced or suppressed appearance of chimera state depending on the distribution as well as the parity of delay values in the layers. Additionally, we report a layer chimera state with an existence of one layer displaying coherent and another layer demonstrating incoherent dynamical evolution. The rich variety of dynamical behavior demonstrated here can be used to gain further insight into the real-world networks which inherently possess such multi-layer architecture with delayed interactions.
Heteroclinic structure of parametric resonance in the nonlinear Schrödinger equation
Creators: name: Conforti, M.
name: Mussot, A.
name: Kudlinski, A.
name: Rota-Nodari, S.
name: Dujardin, G.
name: De Bievre, S.
name: Armaroli, A.
name: Trillo, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: Exactly Solvable and Integrable Systems (nlin.SI)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: We show that the nonlinear stage of modulational instability induced by parametric driving in the {\em defocusing} nonlinear Schrödinger equation can be accurately described by combining mode truncation and averaging methods, valid in the strong driving regime. The resulting integrable oscillator reveals a complex hidden heteroclinic structure of the instability. A remarkable consequence, validated by the numerical integration of the original model, is the existence of breather solutions separating different Fermi-Pasta-Ulam recurrent regimes. Our theory also shows that optimal parametric amplification unexpectedly occurs outside the bandwidth of the resonance (or Arnold tongues) arising from the linearised Floquet analysis.
Graphicality, C^0 convergence, and the Calabi homomorphism
Creators: name: Usher, Michael
Publisher: name: arXiv
Year: 2016
Subjects: subject: Symplectic Geometry (math.SG)
subject: FOS: Mathematics
subject: 53D22

description: Consider a sequence of compactly supported Hamiltonian diffeomorphisms $ϕ_k$ of an exact symplectic manifold, all of which are "graphical" in the sense that their graphs are identified by a Darboux-Weinstein chart with the image of a one-form. We show by an elementary argument that if the $ϕ_k$ $C^0$-converge to the identity then their Calabi invariants converge to zero. This generalizes a result of Oh, in which the ambient manifold was the two-disk and an additional assumption was made on the Hamiltonians generating the $ϕ_k$. We discuss connections to the open problem of whether the Calabi homomorphism extends to the Hamiltonian homeomorphism group. The proof is based on a relationship between the Calabi invariant of a $C^0$-small Hamiltonian diffeomorphism and the generalized phase function of its graph.
description: 9 pages
Stability of rhombohedral phases in vanadium at high-pressure and high-temperature: first-principles investigations
Creators: name: Wang, Yi X.
name: Wu, Q.
name: Chen, Xiang R.
name: Geng, Hua Y.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Computational Physics (physics.comp-ph)
subject: FOS: Physical sciences

description: The pressure-induced transition of vanadium from BCC to rhombohedral structures is unique and intriguing among transition metals. In this work, the stability of these phases is revisited by using density functional theory. At finite temperatures, a novel transition of rhombohedral phases back to BCC phase induced by thermal electrons is discovered. This reentrant transition is found not driven by phonons, instead it is the electronic entropy that stabilizes the latter phase, which is totally out of expectation. Parallel to this transition, we find a peculiar and strong increase of the shear modulus C44 with increasing temperature. It is counter-intuitive in the sense that it suggests an unusual harding mechanism of vanadium by temperature. With these stability analyses, the high-pressure and finite-temperature phase diagram of vanadium is proposed. Furthermore, the dependence of the stability of RH phases on the Fermi energy and chemical environment is investigated. The results demonstrate that the position of the Fermi level has a significant impact on the phase stability, and follows the band-filling argument. Besides the Fermi surface nesting, we find that the localization/delocalization of the d orbitals also contributes to the instability of rhombohedral distortions in vanadium.
description: 40 pages, 12 figures
Combining Cross Entropy and MADS methods for inequality constrained global optimization
Creators: name: Audet, Charles
name: Couderc, Romain
name: Bigeon, Jean
Publisher: name: arXiv
Year: 2020
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: This paper proposes a way to combine the Mesh Adaptive Direct Search (MADS) algorithm with the Cross-Entropy (CE) method for non smooth constrained optimization. The CE method is used as a Search step by the MADS algorithm. The result of this combination retains the convergence properties of MADS and allows an efficient exploration in order to move away from local minima. The CE method samples trial points according to a multivariate normal distribution whose mean and standard deviation are calculated from the best points found so far. Numerical experiments show an important improvement of this method to reach the feasible region and to escape local minima.
Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators
Creators: name: Smoniewski, J.
name: Sánchez, E.
name: Calvo, I.
name: Pueschel, M. J.
name: Talmadge, J. N.
Publisher: name: arXiv
Year: 2020
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: The linear collisionless damping of zonal flows is calculated for quasi-symmetric stellarator equilibria in flux-tube, flux-surface, and full-volume geometry. Equilibria are studied from the quasi-helical symmetry configuration of the Helically Symmetric eXperiment (HSX), a broken symmetry configuration of HSX, and the quasi-axial symmetry geometry of the National Compact Stellarator eXperiment (NCSX). Zonal flow oscillations and long-time damping affect the zonal flow evolution, and the zonal flow residual goes to zero for small radial wavenumber. The oscillation frequency and damping rate depend on the bounce-averaged radial particle drift in accordance with theory. While each flux tube on a flux surface is unique, several different flux tubes in HSX or NCSX can reproduce the zonal flow damping from a flux-surface calculation given an adequate parallel extent. The flux-surface or flux-tube calculations can accurately reproduce the full-volume long-time residual for moderate $k_x$, but the oscillation and damping time scales are longer in local representations, particularly for small $k_x$ approaching the system size.
description: The following article has been accepted by Physics of Plasmas. After it is published, it will be found at https://aip.scitation.org/journal/php. 33 pages, 18 figures
Spectral extremal graphs for the bowtie
Creators: name: Li, Yongtao
name: Lu, Lu
name: Peng, Yuejian
Publisher: name: arXiv
Year: 2022
Subjects: subject: Combinatorics (math.CO)
subject: Spectral Theory (math.SP)
subject: FOS: Mathematics
subject: 05C50, 05C35

description: Let $F_k$ be the (friendship) graph obtained from $k$ triangles by sharing a common vertex. The $F_k$-free graphs of order $n$ which attain the maximal spectral radius was firstly characterized by Cioabă, Feng, Tait and Zhang [Electron. J. Combin. 27 (4) (2020)], and later uniquely determined by Zhai, Liu and Xue [Electron. J. Combin. 29 (3) (2022)] under the condition that $n$ is sufficiently large. In this paper, we get rid of the condition on $n$ being sufficiently large if $k=2$. The graph $F_2$ is also known as the bowtie. We show that the unique $n$-vertex $F_2$-free spectral extremal graph is the balanced complete bipartite graph adding an edge in the vertex part with smaller size if $n\ge 7$, and the condition $n\ge 7$ is tight. Our result is a spectral generalization of a theorem of Erdős, Füredi, Gould and Gunderson [J. Combin. Theory Ser. B 64 (1995)], which states that $\mathrm{ex}(n,F_2)=\left\lfloor {n^2}/{4} \right\rfloor +1$. Moreover, we study the spectral extremal problem for $F_k$-free graphs with given number of edges. In particular, we show that the unique $m$-edge $F_2$-free spectral extremal graph is the join of $K_2$ with an independent set of $\frac{m-1}{2}$ vertices if $m\ge 8$, and the condition $m\ge 8$ is tight.
description: 22 pages, 6 figures. This is the published version
Searching Personalized $k$-wing in Large and Dynamic Bipartite Graphs
Creators: name: Abidi, Aman
name: Chen, Lu
name: Zhou, Rui
name: Liu, Chengfei
Publisher: name: arXiv
Year: 2021
Subjects: subject: Databases (cs.DB)
subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences
subject: H.2; H.3

description: There are extensive studies focusing on the application scenario that all the bipartite cohesive subgraphs need to be discovered in a bipartite graph. However, we observe that, for some applications, one is interested in finding bipartite cohesive subgraphs containing a specific vertex. In this paper, we study a new query dependent bipartite cohesive subgraph search problem based on $k$-wing model, named as the personalized $k$-wing search problem. We introduce a $k$-wing equivalence relationship to summarize the edges of a bipartite graph $G$ into groups. Therefore, all the edges of $G$ are segregated into different groups, i.e. $k$-wing equivalence class, forming an efficient and wing number conserving index called EquiWing. Further, we propose a more compact version of EquiWing, EquiWing-Comp, which is achieved by integrating our proposed $k$-butterfly loose approach and discovered hierarchy properties. These indices are used to expedite the personalized $k$-wing search with a non-repetitive access to $G$, which leads to linear algorithms for searching the personalized $k$-wing. Moreover, we conduct a thorough study on the maintenance of the proposed indices for evolving bipartite graphs. We discover novel properties that help us localize the scope of the maintenance at a low cost. By exploiting the discoveries, we propose novel algorithms for maintaining the two indices, which substantially reduces the cost of maintenance. We perform extensive experimental studies in real, large-scale graphs to validate the efficiency and effectiveness of EquiWing and EquiWing-Comp compared to the baseline.
description: 13 pages, 10 figures and 4 tables
Search for $^{22}$Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes
Creators: name: Fougères, C.
name: Santos, F. de Oliveira
name: José, J.
name: Michelagnoli, C.
name: Clément, E.
name: Kim, Y. H.
name: Lemasson, A.
name: Guimaraes, V.
name: Barrientos, D.
name: Bemmerer, D.
name: Benzoni, G.
name: Boston, A. J.
name: Bottger, R.
name: Boulay, F.
name: Bracco, A.
name: Celikovic, I.
name: Cederwall, B.
name: Ciemala, M.
name: Delafosse, C.
name: Domingo-Pardo, C.
name: Dudouet, J.
name: Eberth, J.
name: Fulop, Z.
name: Gonzalez, V.
name: Goupil, J.
name: Hess, H.
name: Jungclaus, A.
name: Kaskas, A.
name: Korichi, A.
name: Lenzi, S. M.
name: Leoni, S.
name: Li, H.
name: Ljungvall, J.
name: Lopez-Martens, A.
name: Menegazzo, R.
name: Mengoni, D.
name: Million, B.
name: Mrazek, J.
name: Napoli, D. R.
name: Navin, A.
name: Nyberg, J.
name: Podolyak, Zs.
name: Pullia, A.
name: Quintana, B.
name: Ralet, D.
name: Redon, N.
name: Reiter, P.
name: Rezynkina, K.
name: Saillant, F.
name: Salsac, M. D.
name: Sanchez-Benitez, A. M.
name: Sanchis, E.
name: Senyigit, M.
name: Siciliano, M.
name: Smirnova, N. A.
name: Sohler, D.
name: Stanoiu, M.
name: Theisen, Ch.
name: Valiente-Dobon, J. J.
name: Ujic, P.
name: Zielinska, M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Nuclear Experiment (nucl-ex)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Classical novae are thermonuclear explosions in stellar binary systems, and important sources of $^{26}$Al and $^{22}$Na. While gamma rays from the decay of the former radioisotope have been observed throughout the Galaxy, $^{22}$Na remains untraceable. The half-life of $^{22}$Na (2.6 yr) would allow the observation of its 1.275 MeV gamma-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of the nuclear reactions involved in the production and destruction of this nucleus. The $^{22}$Na($p,γ$)$^{23}$Mg reaction remains the only source of large uncertainty about the amount of $^{22}$Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in $^{23}$Mg. In the present work, a combined analysis of particle-particle correlations and velocity-difference profiles is proposed to measure femtosecond nuclear lifetimes. The application of this novel method to the study of the $^{23}$Mg states, combining magnetic and highly-segmented tracking gamma-ray spectrometers, places strong limits on the amount of $^{22}$Na produced in novae, explains its non-observation to date in gamma rays (flux < 2.5x$10^{-4}$ ph/(cm$^2$s)), and constrains its detectability with future space-borne observatories.
description: 18 pages, 3 figures, 1 table
Tuning for Software Analytics: is it Really Necessary?
Creators: name: Fu, Wei
name: Menzies, Tim
name: Shen, Xipeng
Publisher: name: arXiv
Year: 2016
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: Context: Data miners have been widely used in software engineering to, say, generate defect predictors from static code measures. Such static code defect predictors perform well compared to manual methods, and they are easy to use and useful to use. But one of the "black art" of data mining is setting the tunings that control the miner. Objective:We seek simple, automatic, and very effective method for finding those tunings. Method: For each experiment with different data sets (from open source JAVA systems), we ran differential evolution as anoptimizer to explore the tuning space (as a first step) then tested the tunings using hold-out data. Results: Contrary to our prior expectations, we found these tunings were remarkably simple: it only required tens, not thousands,of attempts to obtain very good results. For example, when learning software defect predictors, this method can quickly find tuningsthat alter detection precision from 0% to 60%. Conclusion: Since (1) the improvements are so large, and (2) the tuning is so simple, we need to change standard methods insoftware analytics. At least for defect prediction, it is no longer enough to just run a data miner and present the resultwithoutconducting a tuning optimization study. The implication for other kinds of analytics is now an open and pressing issue
Erratum to Huang SB, Tian MY & Faille A (2020) Two new species of subterranean ground beetles from China (Coleoptera: Carabidae: Trechinae). Raffles Bulletin of Zoology, Supplement 35: 22–31.
Creators: name: RBZ,
Publisher: name: Lee Kong Chian Natural History Museum
Year: 2020

description: Raffles Bulletin of Zoology, 68, 237
Absolutely maximally entangled state equivalence and the construction of infinite quantum solutions to the problem of 36 officers of Euler
Creators: name: Rather, Suhail Ahmad
name: Ramadas, N.
name: Kodiyalam, Vijay
name: Lakshminarayan, Arul
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Ordering and classifying multipartite quantum states by their entanglement content remains an open problem. One class of highly entangled states, useful in quantum information protocols, the absolutely maximally entangled (AME) ones, are specially hard to compare as all their subsystems are maximally random. While, it is well-known that there is no AME state of four qubits, many analytical examples and numerically generated ensembles of four qutrit AME states are known. However, we prove the surprising result that there is truly only {\em one} AME state of four qutrits up to local unitary equivalence. In contrast, for larger local dimensions, the number of local unitary classes of AME states is shown to be infinite. Of special interest is the case of local dimension 6 where it was established recently that a four-party AME state does exist, providing a quantum solution to the classically impossible Euler problem of 36 officers. Based on this, an infinity of quantum solutions are constructed and we prove that these are not equivalent. The methods developed can be usefully generalized to multipartite states of any number of particles.
description: Rewritten as a regular article and few changes in the title from first version. Close to the published version
Duality and reciprocity of fluctuation-dissipation relations in conductors
Creators: name: Reggiani, Lino
name: Alfinito, Eleonora
name: Kuhn, Tilmann
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: By analogy with linear-response we formulate the duality and reciprocity properties of current and voltage fluctuations expressed by Nyquist relations including the intrinsic bandwidths of the respective fluctuations. For this purpose we individuate total-number and drift-velocity fluctuations of carriers inside a conductor as the microscopic sources of noise. The spectral densities at low frequency of the current and voltage fluctuations and the respective conductance and resistance are related in a mutual exclusive way to the corresponding noise-source. The macroscopic variance of current and voltage fluctuations are found to display a dual property via a plasma conductance that admits a reciprocal plasma resistance. Analogously, the microscopic noise-sources are found to obey a dual property and a reciprocity relation. The formulation is carried out in the frame of the grand canonical (for current noise) and canonical (for voltage noise) ensembles and results are derived which are valid for classical as well as for degenerate statistics including fractional exclusion statistics. The unifying theory so developed sheds new light on the microscopic interpretation of dissipation and fluctuation phenomena in conductors. In particular it is proven that, as a consequence of the Pauli principle, for Fermions non-vanishing single-carrier velocity fluctuations at zero temperature are responsible for diffusion but not for current noise, which vanishes in this limit.
description: 5 pages, 1 figure
Eliminating polarization leakage effect for neutral hydrogen intensity mapping with deep learning
Creators: name: Gao, Li-Yang
name: Li, Yichao
name: Ni, Shulei
name: Zhang, Xin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The neutral hydrogen (HI) intensity mapping (IM) survey is regarded as a promising approach for cosmic large-scale structure (LSS) studies. A major issue for the HI IM survey is to remove the bright foreground contamination. A key to successfully remove the bright foreground is to well control or eliminate the instrumental effects. In this work, we consider the instrumental effect of polarization leakage and use the U-Net approach, a deep learning-based foreground removal technique, to eliminate the polarization leakage effect. The thermal noise is assumed to be a subdominant factor compared with the polarization leakage for future HI IM surveys and ignored in this analysis. In this method, the principal component analysis (PCA) foreground subtraction is used as a preprocessing step for the U-Net foreground subtraction. Our results show that the additional U-Net processing could either remove the foreground residual after the conservative PCA subtraction or compensate for the signal loss caused by the aggressive PCA preprocessing. Finally, we test the robustness of the U-Net foreground subtraction technique and show that it is still reliable in the case of existing constraint error on HI fluctuation amplitude.
description: 13 pages, 13 figures; accepted for publication in MNRAS
A multi-tracer empirically-driven approach to line-intensity mapping lightcones
Creators: name: Sato-Polito, Gabriela
name: Kokron, Nickolas
name: Bernal, José Luis
Publisher: name: arXiv
Year: 2022
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Line-intensity mapping (LIM) is an emerging technique to probe the large-scale structure of the Universe. By targeting the integrated intensity of specific spectral lines, it captures the emission from all sources and is sensitive to the astrophysical processes that drive galaxy evolution. Relating these processes to the underlying distribution of matter introduces observational and theoretical challenges, such as observational contamination and highly non-Gaussian fields, which motivate the use of simulations to better characterize the signal. In this work we present SkyLine, a computational framework to generate realistic mock LIM observations that include observational features and foreground contamination, as well as a variety of self-consistent tracer catalogs. We apply our framework to generate realizations of LIM maps from the MultiDark Planck 2 simulations coupled to the UniverseMachine galaxy formation model. We showcase the potential of our scheme by exploring the voxel intensity distribution and the power spectrum of emission lines such as 21 cm, CO, CII, and Lyman-$α$, their mutual cross-correlations, and cross-correlations with galaxy clustering. We additionally present cross-correlations between LIM and sub-millimeter extragalactic tracers of large-scale structure such as the cosmic infrared background and the thermal Sunyaev-Zel'dovich effect, as well as quantify the impact of galactic foregrounds, line interlopers and instrument noise on LIM observations. These simulated products will be crucial in quantifying the true information content of LIM surveys and their cross-correlations in the coming decade, and to develop strategies to overcome the impact of contaminants and maximize the scientific return from LIM experiments.
description: 16+1 pages, 12 figures. Code and fiducial lightcones available at https://github.com/kokron/skyLine . Reflects published version
Location Management in IP-based Future LEO Satellite Networks: A Review
Creators: name: Darwish, Tasneem
name: Kurt, Gunes
name: Yanikomeroglu, Halim
name: Lamontagne, Guillaume
name: Bellemare, Michel
Publisher: name: arXiv
Year: 2021
Subjects: subject: Networking and Internet Architecture (cs.NI)
subject: Systems and Control (eess.SY)
subject: FOS: Computer and information sciences
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Future integrated terrestrial, aerial, and space networks will involve thousands of Low Earth Orbit (LEO) satellites forming a network of mega-constellations, which will play a significant role in providing communication and Internet services everywhere, at any time, and for everything. Due to its very large scale and highly dynamic nature, future LEO satellite networks (SatNets) management is a very complicated and crucial process, especially the mobility management aspect and its two components location management and handover management. In this article, we present a comprehensive and critical review of the state-of-the-art research in LEO SatNets location management. First, we give an overview of the Internet Engineering Task Force (IETF) mobility management standards (e.g., Mobile IPv6 and Proxy Mobile IPv6) and discuss their location management techniques limitations in the environment of future LEO SatNets. We highlight future LEO SatNets mobility characteristics and their challenging features and describe two unprecedented future location management scenarios. A taxonomy of the available location management solutions for LEO SatNets is presented, where the solutions are classified into three approaches. The "Issues to consider" section draws attention to critical points related to each of the reviewed approaches that should be considered in future LEO SatNets location management. To identify the gaps, the current state of LEO SatNets location management is summarized. Noteworthy future research directions are recommended. This article is providing a road map for researchers and industry to shape the future of LEO SatNets location management.
description: Submitted to the Proceedings of the IEEE
QCD phase transitions via a refined truncation of Dyson-Schwinger equations
Creators: name: Gao, Fei
name: Liu, Yu-xin
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We investigate both the chiral and deconfinement phase transitions of QCD matter in a refined scheme of Dyson-Schwinger equations, which have been shown to be successful in giving the meson mass spectrum and matching the interaction with the results from ab initio computation. We verify the equivalence of the chiral susceptibility criterion with different definitions for the susceptibility and confirm that the chiral susceptibility criterion is efficient to fix not only the chiral phase boundary but also the critical end point (CEP), especially when one could not have the effective thermodynamical potential. We propose a generalized Schwinger function criterion for the confinement. We give the phase diagram of both phase transitions and show that in the refined scheme the position of the CEP shifts to lower chemical potential and higher temperature. Based on our calculation and previous results of the chemical freeze out conditions, we propose that the CEP locates in the states of the matter generated by the Au--Au collisions with $\sqrt{s_{NN}^{}}=9\sim15$ GeV.
description: 12 pages, 6 figures, 1 table
The IMF as a function of supersonic turbulence
Creators: name: Motta, Clio Bertelli
name: Clark, Paul C.
name: Glover, Simon C. O.
name: Klessen, Ralf S.
name: Pasquali, Anna
Publisher: name: arXiv
Year: 2016
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Recent studies seem to suggest that the stellar initial mass function (IMF) in early-type galaxies might be different from a classical Kroupa or Chabrier IMF, i.e. contain a larger fraction of the total mass in low-mass stars. From a theoretical point of view, supersonic turbulence has been the subject of interest in many analytical theories proposing a strong correlation with the characteristic mass of the core mass function (CMF) in star forming regions, and as a consequence with the stellar IMF. Performing two suites of smoothed particles hydrodynamics (SPH) simulations with different mass resolutions, we aim at testing the effects of variations in the turbulent properties of a dense, star forming molecular cloud on the shape of the system mass function in different density regimes. While analytical theories predict a shift of the peak of the CMF towards lower masses with increasing velocity dispersion of the cloud, we observe in the low-density regime the opposite trend, with high Mach numbers giving rise to a top-heavy mass distribution. For the high-density regime we do not find any trend correlating the Mach number with the characteristic mass of the resulting IMF, implying that the dynamics of protostellar accretion discs and fragmentation on small scales is not strongly affected by turbulence driven at the scale of the cloud. Furthermore, we suggest that a significant fraction of dense cores are disrupted by turbulence before stars can be formed in their interior through gravitational collapse. Although this particular study has limitations in its numerical resolution, we suggest that our results, along with those from other studies, cast doubt on the turbulent fragmentation models on the IMF that simply map the CMF to the IMF.
description: 12 pages, 7 figures, accepted by MNRAS
An ultracold, optically trapped mixture of {87}Rb and metastable {4}He atoms
Creators: name: Flores, Adonis Silva
name: Mishra, Hari Prasad
name: Vassen, Wim
name: Knoop, Steven
Publisher: name: arXiv
Year: 2016
Subjects: subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We report on the realization of an ultracold (<25~muK) mixture of rubidium ({87}Rb) and metastable triplet helium ({4}He) in an optical dipole trap. Our scheme involves laser cooling in a dual-species magneto-optical trap, simultaneous MW- and RF-induced forced evaporative cooling in a quadrupole magnetic trap, and transfer to a single-beam optical dipole trap. We observe long trapping lifetimes for the doubly spin-stretched spin-state mixture and measure much shorter lifetimes for other spin-state combinations. We discuss prospects for realizing quantum degenerate mixtures of alkali-metal and metastable helium atoms.
description: 9 pages
The Bonsai algorithm: grow your own fermion-to-qubit mapping
Creators: name: Miller, Aaron
name: Zimborás, Zoltán
name: Knecht, Stefan
name: Maniscalco, Sabrina
name: García-Pérez, Guillermo
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Fermion-to-qubit mappings are used to represent fermionic modes on quantum computers, an essential first step in many quantum algorithms for electronic structure calculations. In this work, we present a formalism to design flexible fermion-to-qubit mappings from ternary trees. We discuss in an intuitive manner the connection between the generating trees' structure and certain properties of the resulting mapping, such as Pauli weight and the delocalisation of mode occupation. Moreover, we introduce a recipe that guarantees Fock basis states are mapped to computational basis states in qubit space, a desirable property for many applications in quantum computing. Based on this formalism, we introduce the Bonsai algorithm, which takes as input the potentially limited topology of the qubit connectivity of a quantum device and returns a tailored fermion-to-qubit mapping that reduces the SWAP overhead with respect to other paradigmatic mappings. We illustrate the algorithm by producing mappings for the heavy-hexagon topology widely used in IBM quantum computers. The resulting mappings have a favourable Pauli weight scaling $\mathcal{O}(\sqrt{N})$ on this connectivity, while ensuring that no SWAP gates are necessary for single excitation operations.
Breather soliton dynamics in microresonators
Creators: name: Yu, Mengjie
name: Jang, Jae K.
name: Okawachi, Yoshitomo
name: Griffith, Austin G.
name: Luke, Kevin
name: Miller, Steven A.
name: Ji, Xingchen
name: Lipson, Michal
name: Gaeta, Alexander L.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The generation of temporal cavity solitons in microresonators results in low-noise optical frequency combs which are critical for applications in spectroscopy, astronomy, navigation or telecommunications. Breather solitons also form an important part of many different classes of nonlinear wave systems with a localized temporal structure that exhibits oscillatory behavior. To date, the dynamics of breather solitons in microresonators remains largely unexplored, and its experimental characterization is challenging. Here, we demonstrate the excitation of breather solitons in two different microresonator platforms based on silicon nitride and on silicon. We investigate the dependence of the breathing frequency on pump detuning and observe the transition from period-1 to period-2 oscillation in good agreement with the numerical simulations. Our study presents experimental confirmation of the stability diagram of dissipative cavity solitons predicted by the Lugiato-Lefever equation and is importance to understanding the fundamental dynamical properties of solitons within the larger context of nonlinear science.
description: 18 pages, 5 figures
On complete monotonicity of the Prabhakar function and non-Debye relaxation in dielectrics
Creators: name: Mainardi, Francesco
name: Garrappa, Roberto
Publisher: name: arXiv
Year: 2016
Subjects: subject: Mathematical Physics (math-ph)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Complex Variables (math.CV)
subject: Classical Physics (physics.class-ph)
subject: FOS: Physical sciences
subject: FOS: Mathematics
subject: 26A33, 26A48, 33E12, 44A10, 65E05, 78A25

description: The three parameters Mittag--Leffler function (often referred as the Prabhakar function) has important applications, mainly in physics of dielectrics, in describing anomalous relaxation of non--Debye type. This paper concerns with the investigation of the conditions, on the characteristic parameters, under which the function is locally integrable and completely monotonic; these properties are essential for the physical feasibility of the corresponding models. In particular the classical Havriliak--Negami model is extended to a wider range of the parameters. The problem of the numerical evaluation of the three parameters Mittag--Leffler function is also addressed and three different approaches are discussed and compared. Numerical simulations are hence used to validate the theoretical findings and present some graphs of the function under investigation.
description: 15 pages, 13 figures
Self-reciprocal polynomials connecting unsigned and signed relative derangements
Creators: name: Chen, Ricky X. F.
name: Ruan, Yu-Chen
Publisher: name: arXiv
Year: 2023
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C05, 05A19, 05A15

description: In this paper, we introduce polynomials (in $t$) of signed relative derangements that track the number of signed elements. The polynomials are clearly seen to be in a sense symmetric. Note that relative derangements are those without any signed elements, i.e., the evaluations of the polynomials at $t=0$. Also, the numbers of all signed relative derangements are given by the evaluations at $t=1$. Then the coefficients of the polynomials connect unsigned and signed relative derangements and show how putting elements with signs affects the formation of derangements. We first prove a recursion satisfied by these polynomials which results in a recursion satisfied by the coefficients. A combinatorial proof of the latter is provided next. We also show that the sequences of the coefficients are unimodal. Moreover, other results are obtained. For instance, a kind of dual of a relation between signed derangements and signed relative derangements previously proved by Chen and Zhang is presented.
description: Comments are all welcome
Causal Collaborative Filtering
Creators: name: Xu, Shuyuan
name: Ge, Yingqiang
name: Li, Yunqi
name: Fu, Zuohui
name: Chen, Xu
name: Zhang, Yongfeng
Publisher: name: arXiv
Year: 2021
Subjects: subject: Information Retrieval (cs.IR)
subject: Artificial Intelligence (cs.AI)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Many of the traditional recommendation algorithms are designed based on the fundamental idea of mining or learning correlative patterns from data to estimate the user-item correlative preference. However, pure correlative learning may lead to Simpson's paradox in predictions, and thus results in sacrificed recommendation performance. Simpson's paradox is a well-known statistical phenomenon, which causes confusions in statistical conclusions and ignoring the paradox may result in inaccurate decisions. Fortunately, causal and counterfactual modeling can help us to think outside of the observational data for user modeling and personalization so as to tackle such issues. In this paper, we propose Causal Collaborative Filtering (CCF) -- a general framework for modeling causality in collaborative filtering and recommendation. We provide a unified causal view of CF and mathematically show that many of the traditional CF algorithms are actually special cases of CCF under simplified causal graphs. We then propose a conditional intervention approach for $do$-operations so that we can estimate the user-item causal preference based on the observational data. Finally, we further propose a general counterfactual constrained learning framework for estimating the user-item preferences. Experiments are conducted on two types of real-world datasets -- traditional and randomized trial data -- and results show that our framework can improve the recommendation performance and reduce the Simpson's paradox problem of many CF algorithms.
description: Accepted by the 2023 ACM SIGIR International Conference on Theory of Information Retrieval
The $q$-neighbor Ising model on multiplex networks with partial overlap of nodes
Creators: name: Krawiecki, Andrzej
name: Gradowski, Tomasz
Publisher: name: arXiv
Year: 2023
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: The $q$-neighbor Ising model for the opinion formation on multiplex networks with two layers in the form of random graphs (duplex networks), the partial overlap of nodes, and LOCAL\&AND spin update rule was investigated by means of the pair approximation and approximate Master equations as well as Monte Carlo simulations. Both analytic and numerical results show that for different fixed sizes of the $q$-neighborhood and finite mean degrees of nodes within the layers the model exhibits qualitatively similar critical behavior as the analogous model on multiplex networks with layers in the form of complete graphs. However, as the mean degree of nodes is decreased the discontinuous ferromagnetic transition, the tricritical point separating it from the continuous transition and the possible coexistence of the paramagnetic and ferromagnetic phases at zero temperature occur for smaller relative sizes of the overlap. Predictions of the simple homogeneous pair approximation concerning the critical behavior of the model under study show good qualitative agreement with numerical results; predictions based on the approximate Master equations are usually quantitatively more accurate, but yet not exact. Two versions of the heterogeneous pair approximation are also derived for the model under study, which, surprisingly, yield predictions only marginally different or even identical to those of the simple homogeneous pair approximation. In general, predictions of all approximations show better agreement with the results of Monte Carlo simulations in the case of continuous than discontinuous ferromagnetic transition.
description: 21 pages, 5 figures
On the generic Conley conjecture
Creators: name: Sugimoto, Yoshihiro
Publisher: name: arXiv
Year: 2021
Subjects: subject: Symplectic Geometry (math.SG)
subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics

description: In this paper, we treat an open problem related to the number of periodic orbits of Hamiltonian diffeomorphisms on closed symplectic manifolds, so-called generic Conley conjecture. Generic Conley conjecture states that generically Hamiltonian diffeomorphisms have infinitely many simple contractible periodic orbits. We prove generic Conley conjecture for very wide classes of symplectic manifolds.