cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Modeling compressed turbulent plasma with rapid viscosity variations
Creators: name: Thévenin, Sébastien
name: Valade, Nicolas
name: Gréa, Benoit-Joseph
name: Kluth, Gilles
name: Soulard, Olivier
Publisher: name: arXiv
Year: 2022
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: We propose two-equations models in order to capture the dynamics of a turbulent plasma undergoing compression and experiencing large viscosity variations. The models account for possible relaminarization phases and rapid viscosity changes through closures dependent on the turbulent Reynolds and on the viscosity Froude numbers. These closures are determined from a data-driven approach using eddy-damped quasi normal markovian simulations. The best model is able to mimic the various self-similar regimes identified in \citet{Viciconte2018} and to recover the rapid transition limits identified by \citet{Coleman1991}.
Numerical Computation of approximate Generalized Polarization Tensors
Creators: name: Capdeboscq, Yves
name: Karrman, Anton Bongio
name: Nédélec, Jean-Claude
Publisher: name: arXiv
Year: 2011
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: In this paper we describe a method to compute Generalized Polarization Tensors. These tensors are the coefficients appearing in the multipolar expansion of the steady state voltage perturbation caused by an inhomogeneity of constant conductivity. As an alternative to the integral equation approach, we propose an approximate semi-algebraic method which is easy to implement. This method has been integrated in a Myriapole, a matlab routine with a graphical interface which makes such computations available to non-numerical analysts.
Pulsars in AstroSat-CZTI: Detection in sub-MeV bands and Estimation of Spectral Index from Hardness Ratios
Creators: name: Anusree, K. G.
name: Bhattacharya, Dipankar
name: Bhalerao, Varun
name: Anumarlapudi, Akash
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: The Cadmium Zinc Telluride Imager (CZTI) onboard AstroSat, an open detector above $\sim$100 keV, is a promising tool for the investigation of hard X-ray characteristics of $γ$-ray pulsars. A custom algorithm has been developed to detect pulsars from long integration ($\sim$years) of archival data, as reported by us earlier. Here we extend this method to include in the analysis an additional $\sim$20% of the CZTI pixels that were earlier ignored due to their lower gain values. Recent efforts have provided better and more secure calibration of these pixels, demonstrating their higher thresholds and extended energy range up to $\sim$1 MeV. Here we use the additional information provided by these pixels, enabling the construction of pulse profiles over a larger energy range. We compare the profiles of the Crab pulsar at different sub-bands and show that the behaviour is consistent with the extended energy coverage. As detailed spectroscopy over this full band remains difficult due to the limited count rate, we construct hardness ratios which, together with AstroSat Mass Model simulations, are able to constrain the power-law index of the radiation spectrum. We present our results for the phase-resolved spectrum of PSR J0534+2200 and for the total pulsed emission of PSR J1513-5908. The recovered photon indices are found to be accurate to within $\sim 20$%.
description: Accepted for publication in the Journal of Astrophysics and Astronomy, 11 pages, 5 figures, 7 tables
Theory of Half-metallic Ferrimagnetism in Double Perovskites
Creators: name: Erten, Onur
name: Meetei, O. Nganba
name: Mukherjee, Anamitra
name: Randeria, Mohit
name: Trivedi, Nandini
name: Woodward, Patrick
Publisher: name: arXiv
Year: 2011
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: We present a comprehensive theory of the temperature- and disorder-dependence of half-metallic ferrimagnetism in the double perovskite Sr$_2$FeMoO$_6$ (SFMO) with $T_c$ above room temperature. We show that the magnetization $M(T)$ and conduction electron polarization $P(T)$ are both proportional to the magnetization $M_S(T)$ of localized Fe spins. We derive and validate an effective spin Hamiltonian, amenable to large-scale three-dimensional simulations. We show how $M(T)$ and $T_c$ are affected by disorder, ubiquitous in these materials. We suggest a way to enhance $T_c$ in SFMO without sacrificing polarization.
Bent & Broken Bicycles: Leveraging synthetic data for damaged object re-identification
Creators: name: Piano, Luca
name: Pratticò, Filippo Gabriele
name: Russo, Alessandro Sebastian
name: Lanari, Lorenzo
name: Morra, Lia
name: Lamberti, Fabrizio
Publisher: name: arXiv
Year: 2023
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Graphics (cs.GR)
subject: Machine Learning (cs.LG)
subject: FOS: Computer and information sciences

description: Instance-level object re-identification is a fundamental computer vision task, with applications from image retrieval to intelligent monitoring and fraud detection. In this work, we propose the novel task of damaged object re-identification, which aims at distinguishing changes in visual appearance due to deformations or missing parts from subtle intra-class variations. To explore this task, we leverage the power of computer-generated imagery to create, in a semi-automatic fashion, high-quality synthetic images of the same bike before and after a damage occurs. The resulting dataset, Bent & Broken Bicycles (BBBicycles), contains 39,200 images and 2,800 unique bike instances spanning 20 different bike models. As a baseline for this task, we propose TransReI3D, a multi-task, transformer-based deep network unifying damage detection (framed as a multi-label classification task) with object re-identification. The BBBicycles dataset is available at https://huggingface.co/datasets/GrainsPolito/BBBicycles
Compositional Turbulence and Layering in the Gaseous Envelopes of Forming Planets
Creators: name: Menou, Kristen
name: Zhang, Hong Tao
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Differential settling and growth of dust grains impact the structure of the radiative envelopes of gaseous planets during formation. Sufficiently rapid dust growth can result in envelopes with substantially reduced opacities for radiation transport, thereby facilitating planet formation. We revisit the problem and establish that dust settling and grain growth also lead to outer planetary envelopes that are prone to compositional instabilities, by virtue of their inverted mean-molecular weight gradients. Under a variety of conditions, we find that the radiative envelopes of forming planets experience compositional turbulence driven by a semi-transparent version of the thermohaline instability ('fingering convection'). The compositional turbulence seems efficient at mixing dust in the radiative envelopes of planets forming at super-AU distances (say $5$ AU) from a Sun-like star, but not so at sub-AU distances (say $0.2$ AU). We also address the possibility of compositional layering in this context. Distinct turbulent regimes for planetary envelopes growing at sub-AU vs. super-AU distances could leave an imprint on the final planets formed.
description: 9 pages, MNRAS accepted
New results on twinlike models
Creators: name: Bazeia, D.
name: Menezes, R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: In this work we study the presence of kinks in models described by a single real scalar field in bidimensional spacetime. We work within the first-order framework, and we show how to write first-order differential equations that solve the equations of motion. The first-order equations strongly simplify the study of linear stability, which is implemented on general grounds. They also lead to a direct investigation of twinlike theories, which is used to introduce a family of models that support the same defect structure, with the very same energy density and linear stability.
description: 6 pages, 1 figure
Black Holes and the Third Law of Thermodynamics Revisited
Creators: name: Socolovsky, Miguel
Publisher: name: arXiv
Year: 2023
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: Black holes contradict the Nernst-Planck (N/P) version of the 3rd. law of thermodynamics, but agree with its unattainability (U) version. This happens without contradiction, because the N/P and U versions are not equivalent, namely, N/P implies U but U does not imply N/P. So, black holes obey the weaker version of the 3rd. law, but not the stronger one.
description: 5 pages, 4 figures
Quantum Fidelity of the Aubry-André Model and the Exponential Orthogonality Catastrophe
Creators: name: Vahedi, Javad
name: Kettemann, Stefan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We consider the orthogonality catastrophe in the (extended) Aubry-André (AA)-Model, by calculating the overlap $F$ between the ground state of the Fermi liquid in that quasi-crystalline model and the one of the same system with an added potential impurity, as function of the size of that impurity. Recently, the typical fidelity $F_{\rm typ}$ was found in quantum critical phases to decay exponentially with system size $L$ as $F \sim \exp(-c L^{z η})$\cite{Kettemann2016} as found in an analytical derivation due to critical correlations. For the critical AA model $η= 1/2$ is the power of multifractal intensity correlations, and $z$ the dynamical exponent due to the fractal structure of the density of states which is numerically found to be $z \gg 1$. Surprisingly, however, we find for a weak single site impurity that the fidelity decays with a power law, in the critical phase. Even though it is found to be smaller and decays faster than in the metallic phase, it does not decay exponentially as predicted. We find an exponential AOC however in the insulator phase for which we give a statistical explanation, a mechanism which is profoundly different from the AOC in metals, where it is the coupling to a continuum of states which yields there the power law suppression of the fidelity. By reexamination of the analytical derivation we identify nonperturbative corrections due to the impurity potential and multipoint correlations among wave functions as possible causes for the absence of the exponential AOC in the critical phase. For an extended impurity, however, we find indications of an exponential AOC at the quantum critical point of the AA model and at the mobility edge of the extended AA model and suggest an explanation for this finding.
description: 16 pages including 20 multi-panel figures
Comparison of Techniques for Distillation of Entanglement over a Lossy Channel
Creators: name: Mauron, Caroline
name: Ralph, Timothy C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We analyze three quantum communication protocols that have been proposed in the literature, and compare how well they communicate single-rail entanglement. We use specific metrics for output state purity and probability of success and include the presence of imperfect photon source and detection components. We find that a distributed noiseless linear amplification (NLA) protocol with a relay point placed half-way between Alice and Bob outperforms NLA at Bob's end and a recently proposed purification protocol under most conditions, unless the distance is very small or the photon source component is very good.
Improved Heat and Particle Flux Mitigation in High Core Confinement, Baffled, Alternate Divertor Configurations in the TCV tokamak
Creators: name: Raj, Harshita
name: Theiler, C.
name: Thornton, A.
name: Fevrier, O.
name: Gorno, S.
name: Bagnato, F.
name: Blanchard, P.
name: Colandrea, C.
name: de Oliveira, H.
name: Duval, B. P.
name: Labit, B.
name: Perek, A.
name: Reimerdes, H.
name: Sheikh, U.
name: Vallar, M.
name: Vincent, B.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: FOS: Physical sciences

description: Nitrogen seeded detachment has been achieved in the Tokamak a Configuration Variable (TCV) in advanced divertor configurations (ADCs), namely X-divertor and X-point target, with and without baffles in H-mode plasmas with high core confinement. Both ADCs show a remarkable reduction in the inter-ELM particle and heat fluxes to the target compared to the standard divertor configuration. 95-98% of the peak heat flux to the target is mitigated as a synergetic effect of ADCs, baffling, and nitrogen seeded detachment. The effect of divertor geometry and baffles on core-divertor compatibility is investigated in detail. The power balance in these experiments is also investigated to explore the physics behind the observed reduction in heat fluxes in the ADCs.
Signatures of the superfluid to Mott insulator transition in equilibrium and in dynamical ramps
Creators: name: Pekker, D.
name: Wunsch, B.
name: Kitagawa, T.
name: Manousakis, E.
name: Sørensen, A. S.
name: Demler, E.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We investigate the equilibrium and dynamical properties of the Bose-Hubbard model and the related particle-hole symmetric spin-1 model in the vicinity of the superfluid to Mott insulator quantum phase transition. We employ the following methods: exact-diagonalization, mean field (Gutzwiller), cluster mean-field, and mean-field plus Gaussian fluctuations. In the first part of the paper we benchmark the four methods by analyzing the equilibrium problem and give numerical estimates for observables such as the density of double occupancies and their correlation function. In the second part, we study parametric ramps from the superfluid to the Mott insulator and map out the crossover from the regime of fast ramps, which is dominated by local physics, to the regime of slow ramps with a characteristic universal power law scaling, which is dominated by long wavelength excitations. We calculate values of several relevant physical observables, characteristic time scales, and an optimal protocol needed for observing universal scaling.
description: 23 pages, 13 figures
Exploring the Use of Collaborative Robots in Cinematography
Creators: name: Praveena, Pragathi
name: Cagiltay, Bengisu
name: Gleicher, Michael
name: Mutlu, Bilge
Publisher: name: arXiv
Year: 2023
Subjects: subject: Robotics (cs.RO)
subject: Human-Computer Interaction (cs.HC)
subject: FOS: Computer and information sciences

description: Robotic technology can support the creation of new tools that improve the creative process of cinematography. It is crucial to consider the specific requirements and perspectives of industry professionals when designing and developing these tools. In this paper, we present the results from exploratory interviews with three cinematography practitioners, which included a demonstration of a prototype robotic system. We identified many factors that can impact the design, adoption, and use of robotic support for cinematography, including: (1) the ability to meet requirements for cost, quality, mobility, creativity, and reliability; (2) the compatibility and integration of tools with existing workflows, equipment, and software; and (3) the potential for new creative opportunities that robotic technology can open up. Our findings provide a starting point for future co-design projects that aim to support the work of cinematographers with collaborative robots.
description: Article accepted at CHI LBW 2023. Pragathi Praveena and Bengisu Cagiltay contributed equally to the work
Very Large Array Observations of Ammonia in Infrared-Dark Clouds II: Internal Kinematics
Creators: name: Ragan, Sarah E.
name: Heitsch, Fabian
name: Bergin, Edwin A.
name: Wilner, David
Publisher: name: arXiv
Year: 2012
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Infrared-dark clouds (IRDCs) are believed to be the birthplaces of rich clusters and thus contain the earliest phases of high-mass star formation. We use the Green Bank Telescope (GBT) and Very Large Array (VLA) maps of ammonia (NH3) in six IRDCs to measure their column density and temperature structure (Paper 1), and here, we investigate the kinematic structure and energy content. We find that IRDCs overall display organized velocity fields, with only localized disruptions due to embedded star formation. The local effects seen in NH3 emission are not high velocity outflows but rather moderate (few km/s) increases in the line width that exhibit maxima near or coincident with the mid-infrared emission tracing protostars. These line width enhancements could be the result of infall or (hidden in NH3 emission) outflow. Not only is the kinetic energy content insufficient to support the IRDCs against collapse, but also the spatial energy distribution is inconsistent with a scenario of turbulent cloud support. We conclude that the velocity signatures of the IRDCs in our sample are due to active collapse and fragmentation, in some cases augmented by local feedback from stars.
description: 15 pages, 12 figures, accepted for publication in ApJ
Late time acceleration in Palatini gravity
Creators: name: Antoniadis, Ignatios
name: Guillen, Anthony
name: Tamvakis, Kyriakos
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate the effect of the quadratic correction $αR^2$ and non-minimal coupling $ξϕ^2 R$ on a quintessence model with an exponential potential $V(ϕ) = M^4\exp(-λϕ)$ in the Palatini formulation of gravity. We use dynamical system techniques to analyze the attractor structure of the model and uncover the possible trajectories of the system. We find that the quadratic correction cannot play a role in the late time dynamics, except for unacceptably large values of the parameter $α$; although it can play a role at early times. We find viable evolutions, from a matter-dominated phase to an accelerated expansion phase, with the dynamics driven by the non-minimal coupling. These evolutions correspond to trajectories where the field ends up frozen, thus acting as a cosmological constant.
description: 25 pages, 3 figures, some paragraphs added
S-folds and $AdS_{3}$ flows from the D3-brane
Creators: name: Guarino, Adolfo
name: Suh, Minwoo
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We investigate supersymmetric flows in type IIB supergravity that preserve an $SO(2,2)$ space-time symmetry and asymptote to $AdS_{5} \times S^5$ at both endpoints. The flows are constructed as Janus-type $\mathbb{R} \times AdS_{3}$ BPS domain-walls in the effective four-dimensional $[SO(1,1)\times{S}O(6)]\ltimes\mathbb{R}^{12}$ gauged maximal supergravity describing the massless sector of type IIB supergravity compactified on $S^1 \times S^{5}$. The compactification includes an S-duality hyperbolic twist along the $S^1$ which, when combined with an appropriate choice of boundary conditions for the running scalars, generates special flows that develop an S-fold regime at their core, thus enhancing the space-time symmetry there to $SO(2,3)$. Via the AdS/CFT correspondence, the flows constructed here are conjectured to describe conformal interfaces in a circle compactification of $\mathcal{N}=4$ $\textrm{SYM}_{4}$.
description: v2: 32 pages, 9 figures, published version
Acoustic solitons in a periodic waveguide: theory and experiments
Creators: name: Sougleridis, Ioannis Ioannou
name: Richoux, Olivier
name: Achilleos, Vassos
name: Theocharis, Georgios
name: Desjouy, Cyril
name: Frantzeskakis, Dimitrios J.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Pattern Formation and Solitons (nlin.PS)
subject: FOS: Physical sciences

description: We study the propagation of high-amplitude sound waves, in the form of pulse-like solitary waves, in an air-filled acoustic waveguide of periodically varying cross section. Our numerical simulations, solving the compressible Navier-Stokes equations in two dimensions, as well as our experimental results, strongly suggest that nonlinear losses, originated from vortex shedding (at the segment changes) are crucial in the dynamics of high amplitude pulses. We find that, even in the presence of strong dissipation, the solitary wave roughly retains its characteristics (as described by the amplitude-velocity-width relations), obtained by the derivation and analysis of an effective Boussinesq equation. In addition, we propose a transmission-line based numerical scheme, able to capture well the experimental results. The proposed design offers a new playground for the study of the combined effects of dispersion, nonlinearity and dissipation in air-borne acoustics, while, due to its simplicity, it can be extended to higher dimensions.
Leptogenesis and Dark Matter Through Relativistic Bubble Walls with Observable Gravitational Waves
Creators: name: Borah, Debasish
name: Dasgupta, Arnab
name: Saha, Indrajit
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study a scenario where both dark matter and heavy right handed neutrino (RHN) responsible for leptogenesis acquire masses by crossing the relativistic bubble walls formed as a result of a TeV scale supercooled first order phase transition (FOPT). While this leads to a large out-of-equilibrium abundance of right handed neutrino inside the bubble sufficient to produce the required lepton asymmetry, the dark matter being lighter can still remain in equilibrium with its relic being set by subsequent thermal freeze-out. A classical conformal symmetry ensures the origin of mass via FOPT induced by a singlet scalar while also ensuring supercooling leading to enhanced gravitational wave amplitude within the sensitivity of the LISA experiment. A minimal scenario with three RHN, one inert scalar doublet and one singlet scalar as additional fields beyond the standard model is sufficient to realize this possibility which also favours inert RHN dark matter over inert scalar doublet.
description: 32 pages, 8 captioned figures, matches version accepted for publication in JHEP
Cool and warm dust emission from M33 (HerM33es)
Creators: name: Xilouris, E. M.
name: Tabatabaei, F. S.
name: Boquien, M.
name: Kramer, C.
name: Buchbender, C.
name: Bertoldi, F.
name: Anderl, S.
name: Braine, J.
name: Verley, S.
name: Relano, M.
name: Quintana-Lacaci, G.
name: Akras, S.
name: Beck, R.
name: Calzetti, D.
name: Combes, F.
name: Gonzalez, M.
name: Gratier, P.
name: Henkel, C.
name: Israel, F.
name: Koribalski, B.
name: Lord, S.
name: Mookerjea, B.
name: Rosolowsky, E.
name: Stacey, G.
name: Tilanus, R. P. J.
name: van der Tak, F.
name: van der Werf, P.
Publisher: name: arXiv
Year: 2012
Subjects: subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We study the far-infrared emission from the nearby spiral galaxy M33 in order to investigate the dust physical properties such as the temperature and the luminosity density across the galaxy. Taking advantage of the unique wavelength coverage (100, 160, 250, 350 and 500 micron) of the Herschel Space Observatory and complementing our dataset with Spitzer-IRAC 5.8 and 8 micron and Spitzer-MIPS 24 and 70 micron data, we construct temperature and luminosity density maps by fitting two modified blackbodies of a fixed emissivity index of 1.5. We find that the 'cool' dust grains are heated at temperatures between 11 and 28 K with the lowest temperatures found in the outskirts of the galaxy and the highest ones in the center and in the bright HII regions. The infrared/submillimeter total luminosity (5 - 1000 micron) is estimated to be 1.9x10^9 Lsun. 59% of the total luminosity of the galaxy is produced by the 'cool' dust grains (~15 K) while the rest 41% is produced by 'warm' dust grains (~55 K). The ratio of the cool-to-warm dust luminosity is close to unity (within the computed uncertainties), throughout the galaxy, with the luminosity of the cool dust being slightly enhanced in the center of the galaxy. Decomposing the emission of the dust into two components (one emitted by the diffuse disk of the galaxy and one emitted by the spiral arms) we find that the fraction of the emission in the disk in the mid-infrared (24 micron) is 21%, while it gradually rises up to 57% in the submillimeter (500 micron). We find that the bulk of the luminosity comes from the spiral arm network that produces 70% of the total luminosity of the galaxy with the rest coming from the diffuse dust disk. The 'cool' dust inside the disk is heated at a narrow range of temperatures between 18 and 15 K (going from the center to the outer parts of the galaxy).
description: 12 pages, 14 figures, accepted for publication in A&A
Quantum computing with incoherent resources and quantum jumps
Creators: name: Santos, Marcelo F.
name: Cunha, Marcelo Terra
name: Chaves, Rafael
name: Carvalho, Andre R. R.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Quantum Physics (quant-ph)
subject: Other Condensed Matter (cond-mat.other)
subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Spontaneous emission and the inelastic scattering of photons are two natural processes usually associated with decoherence and the reduction in the capacity to process quantum information. Here we show that when suitably detected, these photons are sufficient to build all the fundamental blocks needed to perform quantum computation in the emitting qubits while protecting them from deleterious dissipative effects. We exemplify by showing how to teleport an unknown quantum state and how to efficiently prepare graph states for the implementation of measurement-based quantum computation.
description: 5 pages, 5 figures
Density-clustering of continuous gravitational wave candidates from large surveys
Creators: name: Steltner, Benjamin
name: Menne, Thorben
name: Papa, Maria Alessandra
name: Eggenstein, Heinz-Bernd
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: Searches for continuous gravitational waves target nearly monochromatic gravitational wave emission from e.g. non-axysmmetric fast-spinning neutron stars. Broad surveys often require to explicitly search for a very large number of different waveforms, easily exceeding $\sim10^{17}$ templates. In such cases, for practical reasons, only the top, say $\sim10^{10}$, results are saved and followed-up through a hierarchy of stages. Most of these candidates are not completely independent of neighbouring ones, but arise due to some common cause: a fluctuation, a signal or a disturbance. By judiciously clustering together candidates stemming from the same root cause, the subsequent follow-ups become more effective. A number of clustering algorithms have been employed in past searches based on iteratively finding symmetric and compact over-densities around candidates with high detection statistic values. The new clustering method presented in this paper is a significant improvement over previous methods: it is agnostic about the shape of the over-densities, is very efficient and it is effective: at a very high detection efficiency, it has a noise rejection of $99.99\%$ , is capable of clustering two orders of magnitude more candidates than attainable before and, at fixed sensitivity it enables more than a factor of 30 faster follow-ups. We also demonstrate how to optimally choose the clustering parameters.
description: 7 pages, 3 figures
Linearized Off-shell 4+7 Supergeometry of 11D Supergravity
Creators: name: Becker, Katrin
name: Butter, Daniel
name: Sengupta, Anindya
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We describe the linearized supergeometry of eleven dimensional supergravity with four off-shell local supersymmetries. We start with a background Minkowski 11D, N=1 superspace, and an additional ingredient of a global, constant, $G_2$-structure which facilitates the definition of a $4|4+7$ background superspace. A bottom-up construction of linear fluctuations of the geometric constituents (such as supervielbein, spin connection, and the super 3-form of 11D supergravity) is given in terms of 4D, N=1 prepotential superfields. This is complemented by a top-down description of the linearized supergeometry of the $4|4+7$ superspace dealing directly with torsion, curvature, and Bianchi identities. Torsion constraints that (combined with the Bianchi identities) lead to the preceding prepotential expressions of the gauge fields are identified. All irreducible consequences of the torsion and 4-form Bianchi identities are systematically derived except for dimension 2 Bianchi identities of the 4-form, and dimension $\tfrac 52$ Bianchi identities of torsion, which set bosonic curls of components of one lower dimension to zero.
description: 49 pages
M2GNN: Metapath and Multi-interest Aggregated Graph Neural Network for Tag-based Cross-domain Recommendation
Creators: name: Huai, Zepeng
name: Yang, Yuji
name: Zhang, Mengdi
name: Zhang, Zhongyi
name: Li, Yichun
name: Wu, Wei
Publisher: name: arXiv
Year: 2023
Subjects: subject: Information Retrieval (cs.IR)
subject: FOS: Computer and information sciences

description: Cross-domain recommendation (CDR) is an effective way to alleviate the data sparsity problem. Content-based CDR is one of the most promising branches since most kinds of products can be described by a piece of text, especially when cold-start users or items have few interactions. However, two vital issues are still under-explored: (1) From the content modeling perspective, sufficient long-text descriptions are usually scarce in a real recommender system, more often the light-weight textual features, such as a few keywords or tags, are more accessible, which is improperly modeled by existing methods. (2) From the CDR perspective, not all inter-domain interests are helpful to infer intra-domain interests. Caused by domain-specific features, there are part of signals benefiting for recommendation in the source domain but harmful for that in the target domain. Therefore, how to distill useful interests is crucial. To tackle the above two problems, we propose a metapath and multi-interest aggregated graph neural network (M2GNN). Specifically, to model the tag-based contents, we construct a heterogeneous information network to hold the semantic relatedness between users, items, and tags in all domains. The metapath schema is predefined according to domain-specific knowledge, with one metapath for one domain. User representations are learned by GNN with a hierarchical aggregation framework, where the intra-metapath aggregation firstly filters out trivial tags and the inter-metapath aggregation further filters out useless interests. Offline experiments and online A/B tests demonstrate that M2GNN achieves significant improvements over the state-of-the-art methods and current industrial recommender system in Dianping, respectively. Further analysis shows that M2GNN offers an interpretable recommendation.
Macroscopic quantum coherence in spinor condensates confined in an anisotropic potential
Creators: name: Huang, Yixiao
name: Zhang, Yunbo
name: Lü, Rong
name: Wang, Xiaoguang
name: Yi, Su
Publisher: name: arXiv
Year: 2012
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We investigate the macroscopic quantum coherence of a spin-1 Rb condensate confined in an anisotropic potential. Under the single-mode approximation, we show that the system can be modeled as a biaxial quantum magnet due to the interplay between the magnetic dipole-dipole interaction and the anisotropic potential. By applying a magnetic field along the hard-axis, we show that the tunneling splitting oscillates as a function of the field strength. We also propose an experimental scheme to detect the oscillatory behavior of the tunneling splitting by employing the Landau-Zener tunneling.
description: 5 pages, 4 figures
Photons generated by gravitional waves in the near-zone of a neutron star
Creators: name: Feng, Chao-Jun
name: Guo, Ao
name: Xie, Zhong-Ming
name: Li, Miao
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: When a gravitational wave or a graviton travels through an electric or magnetic background, it could convert into a photon with some probability. In this paper, a dipole magnetic field is considered as this kind of background in both the Minkowski spacetime and the curved spacetime in the near-zone of a neutron star. In the former case, we find that the graviton traveling vertically rather than parallel to the background magnetic field could be more effectively converted into an electromagnetic radiation field. In the latter case, we focus on the situation, in which the graviton travels along the radial direction near a neutron star. The radius of a neutron star is about ten kilometers, so the gravitational wave with long wavelength or low frequency may bypass neutron stars by diffraction. For high frequency gravitational wave, the conversion probability is proportional to the distance square as that in the static electric or magnetic background case. The smaller the inclination angle between the dipole field and the neutron star north pole is, the larger magnetic amplitude will be. The term that described curved spacetime will slightly enhance this kind of probability. We estimate that this value is about the order of $\sim 10^{-14}- 10^{-10}$. Therefore, it is expectable that this kind of conversion process may have a potential to open a window for observing high frequency gravitational waves.
description: 17pages,2figures
A Model of Habitability Within the Milky Way Galaxy
Creators: name: Gowanlock, Michael G.
name: Patton, David R.
name: McConnell, Sabine M.
Publisher: name: arXiv
Year: 2011
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We present a model of the Galactic Habitable Zone (GHZ), described in terms of the spatial and temporal dimensions of the Galaxy that may favour the development of complex life. The Milky Way galaxy is modelled using a computational approach by populating stars and their planetary systems on an individual basis using Monte-Carlo methods. We begin with well-established properties of the disk of the Milky Way, such as the stellar number density distribution, the initial mass function, the star formation history, and the metallicity gradient as a function of radial position and time. We vary some of these properties, creating four models to test the sensitivity of our assumptions. To assess habitability on the Galactic scale, we model supernova rates, planet formation, and the time required for complex life to evolve. Our study improves on other literature on the GHZ by populating stars on an individual basis and by modelling SNII and SNIa sterilizations by selecting their progenitors from within this preexisting stellar population. Furthermore, we consider habitability on tidally locked and non-tidally locked planets separately, and study habitability as a function of height above and below the Galactic midplane. In the model that most accurately reproduces the properties of the Galaxy, the results indicate that an individual SNIa is ~5.6 \times more lethal than an individual SNII on average. In addition, we predict that ~1.2% of all stars host a planet that may have been capable of supporting complex life at some point in the history of the Galaxy. Of those stars with a habitable planet, ~75% of planets are predicted to be in a tidally locked configuration with their host star. The majority of these planets that may support complex life are found towards the inner Galaxy, distributed within, and significantly above and below, the Galactic midplane.
description: Accepted for publication in Astrobiology. 40 pages, 12 figures, 3 tables
Chiral approach to massive higher spins
Creators: name: Ochirov, Alexander
name: Skvortsov, Evgeny
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We propose a new, chiral description for massive higher-spin particles in four spacetime dimensions, which facilitates the introduction of consistent interactions. As proof of concept, we formulate three theories, in which higher-spin matter is coupled to electrodynamics, non-Abelian gauge theory or gravity. The theories are chiral and have simple Lagrangians, resulting in Feynman rules analogous to those of massive scalars. Starting from these Feynman rules, we derive tree-level scattering amplitudes with two higher-spin matter particles and any number of positive-helicity photons, gluons or gravitons. The amplitudes reproduce the arbitrary-multiplicity results that were obtained via on-shell recursion in a parity-conserving setting, and which chiral and non-chiral theories thus have in common. The presented theories are currently the only examples of consistent interacting field theories with massive higher-spin fields.
description: 7 pages + refs; v2 minor improvements, journal version + footnotes
Simplified Method for the Identification of Low Mass Ratio Contact Binary Systems that are Potential Red Nova Progenitors
Creators: name: Wadhwa, Surjit S.
name: De Horta, Ain Y.
name: Filipovic, Miroslav D.
name: Tothill, Nick F. H.
name: Arbutina, Bojan
name: Petrovic, Jelena
name: Djurasevic, Gojko
Publisher: name: arXiv
Year: 2022
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The study presents a simplified method to identify potential bright red nova progenitors based on the amplitude of the light curve and infrared (J-H) colour of a contact binary system. We employ published criteria for contact binary orbital instability to show that the amplitude of the light curve for a given contact system with a low mass (< 1.4Msun) primary must be less than a specified value for it to be potentially unstable. Using this we search the photometric data of a large survey to identify about 50 potential bright red nova progenitors. We analyse the survey photometry of each to determine the mass ratio and from the estimated mass of the primary other physical parameters of the systems. We show that each system has physical characteristics indicating potential orbital instability. Using the absolute parameters from our sample we model the expected instability separation and period for low mass contact binary systems
description: Accepted - Journal of Astrophysics and Astronomy
Electroweak Symmetry Breaking Beyond the Standard Model
Creators: name: Bhattacharyya, Gautam
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: In this talk, I shall address two key issues related to electroweak symmetry breaking. First, how fine-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, I shall first review the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios. I shall then compare and contrast the little Higgs, composite Higgs and the Higgsless models. Finally, I shall summarize by giving a broad overview on where we stand at the end of 2011.
description: Plenary talk at the International Lepton-Photon Conference, Mumbai, August 2011. To appear in the proceedings (special issue of PRAMANA)
Electroweak production of $χ_{Q1}$ states in $e^+e^-$ collisions: A brief review
Creators: name: Achasov, N. N.
name: Kiselev, A. V.
name: Shestakov, G. N.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: A brief review of the available experimental and theoretical results on the production of the $χ_{Q1}$ states in $e^+e^-$ annihilation and photon-photon $γγ^*$ interactions is presented. Future data on the production of the $χ_{c1}(1P)$, $χ_{c1}(3872)$, $χ_{c1} (4140)$, $χ_{c1}(4274)$, $χ_{c1}(4685)$, $χ_{b1} (1P)$, $χ_{b1}(2P )$, and $χ_{b1}(3P)$ resonances in $e^+e^-$ annihilation and $γγ^*$ interactions will help the development and unification of theoretical predictions related to the electroweak decays of heavy quarkonia, the reduction of their spread and model uncertainties.
description: 6 pages; v2: published version, corrections and clarifications made, new references and a paragraph on polarized electron beam added
Short-range correlations in dilute atomic Fermi gases with spin-orbit coupling
Creators: name: Yu, Zhenhua
Publisher: name: arXiv
Year: 2012
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We study the short-range correlation strength of three dimensional spin half dilute atomic Fermi gases with spin-orbit coupling. The interatomic interaction is modeled by the contact pseudopotential. In the high temperature limit, we derive the expression for the second order virial expansion of the thermodynamic potential via the ladder diagrams. We further evaluate the second order virial expansion in the limit that the spin-orbit coupling constants are small, and find that the correlation strength between the fermions increases as the forth power of the spin-orbit coupling constants. At zero temperature, we consider the cases in which there are symmetric spin-orbit couplings in two or three directions. In such cases, there is always a two-body bound state of zero net momentum. In the limit that the average interparticle distance is much larger than the dimension of the two-body bound state, the system primarily consists of condensed bosonic molecules that fermions pair to form; we find that the correlation strength also becomes bigger compared to that in the absence of spin-orbit coupling. Our results indicate that generic spin-orbit coupling enhances the short-range correlations of the Fermi gases. Measurement of such enhancement by photoassociation experiment is also discussed.
description: 7 pages, 4 figures
Interaction Driven Topological Phase Transition in Monolayer CrCl$_2$(pyrazine)$_2$
Creators: name: Ji, Xuecong
name: Gao, Jiacheng
name: Yue, Changming
name: Wang, Zhijun
name: Wu, Hua
name: Dai, Xi
name: Weng, Hongming
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The quadratic band crossing points (QBCPs) at Fermi level in two-dimension have been proposed to be unstable under electron-electron interaction. The possible interaction driven states include quantum anomalous Hall (QAH) state and various nematic ordered states. In this work, motivated by the discovery of ferromagnetic van der Waals layered metal-organic framework CrCl$_2$(pyrazine)$_2$, we theoretically propose that the single layer of CrCl$_2$(pyrazine)$_2$ might realize one or some of these interaction driven states based on the QBCP protected by $C_4$ symmetry. By introducing the short-range density-density type repulsion interactions into this system, we have found the phase diagram depending on different interaction range and strength. The exotic phases include the staggered chiral flux state manifesting QAH effect, the site-nematic insulator and the site-nematic Dirac semimetal state. The QAH state is robust against perturbations breaking the QBCP but it is weakened by increasing temperature. The metal-organic framework is tunable by changing the transition-metal elements, which might improve the gap size and stability of this interaction induced QAH state.
Time-dependent strain-tuning topological magnon phase transition
Creators: name: Vidal-Silva, Nicolas
name: Troncoso, Roberto E.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: Collinear magnets in honeycomb lattices under the action of time-dependent strains are investigated. Given the limits of high-frequency periodically varying deformations, we derive an effective Floquet theory for spin system that results in the emergence of a spin chirality. We find that the coupling between magnons and spin chirality depends on the details of the strain such as the spatial dependence and applied direction. Magnonic fluctuations about the ferromagnetic state are determined, and it is found that spatially homogeneous strains drive the magnon system into topologically protected phases. In particular, we show that certain uniform strain fields play the role of an out-of-plane next-neighbor Dzyaloshinskii-Moriya interaction. Furthermore, we explore the application of nonuniform strains, which lead to a confinement of magnon states that for uniaxial strains, propagates along the direction that preserves translational symmetry. Our work demonstrates a direct and novel way in which to manipulate the magnon spectrum based on time-dependent strain engineering that is relevant for exploring topological transitions in quantum magnonics.
RAELLA: Reforming the Arithmetic for Efficient, Low-Resolution, and Low-Loss Analog PIM: No Retraining Required!
Creators: name: Andrulis, Tanner
name: Emer, Joel S.
name: Sze, Vivienne
Publisher: name: arXiv
Year: 2023
Subjects: subject: Hardware Architecture (cs.AR)
subject: FOS: Computer and information sciences
subject: C.1.3

description: Processing-In-Memory (PIM) accelerators have the potential to efficiently run Deep Neural Network (DNN) inference by reducing costly data movement and by using resistive RAM (ReRAM) for efficient analog compute. Unfortunately, overall PIM accelerator efficiency is limited by energy-intensive analog-to-digital converters (ADCs). Furthermore, existing accelerators that reduce ADC cost do so by changing DNN weights or by using low-resolution ADCs that reduce output fidelity. These strategies harm DNN accuracy and/or require costly DNN retraining to compensate. To address these issues, we propose the RAELLA architecture. RAELLA adapts the architecture to each DNN; it lowers the resolution of computed analog values by encoding weights to produce near-zero analog values, adaptively slicing weights for each DNN layer, and dynamically slicing inputs through speculation and recovery. Low-resolution analog values allow RAELLA to both use efficient low-resolution ADCs and maintain accuracy without retraining, all while computing with fewer ADC converts. Compared to other low-accuracy-loss PIM accelerators, RAELLA increases energy efficiency by up to 4.9$\times$ and throughput by up to 3.3$\times$. Compared to PIM accelerators that cause accuracy loss and retrain DNNs to recover, RAELLA achieves similar efficiency and throughput without expensive DNN retraining.
description: 16 pages; 15 figures; Accepted at ISCA 2023 (the International Symposium on Computer Architecture)