cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Arguments for the physical nature of the triggered ion-acoustic waves observed on the Parker Solar Probe
Creators: name: Mozer, Forrest
name: Bale, Stuart
name: Kellogg, Paul
name: Romeo, Orlando
name: Vasko, Ivan
name: Verniero, Jaye
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: Triggered ion-acoustic waves are a pair of coupled waves observed in the previously unexplored plasma regime near the Sun. They may be capable of producing important effects on the solar wind. Because this wave mode has not been observed or studied previously and it is not fully understood, the issue of whether it has a natural origin or is an instrumental artifact can be raised. This paper discusses this issue by examining 13 features of the data such as whether the triggered ion-acoustic waves are electrostatic, whether they are both narrow-band, whether they satisfy the requirement that the electric field is parallel to the k-vector, whether the phase difference between the electric field and the density fluctuations is 90 degrees, whether the two waves have the same phase velocity as they must if they are coupled, whether the phase velocity is that of an ion-acoustic wave, whether they are associated with other parameters such as electron heating, whether the electric field instrument otherwise performed as expected, etc. The conclusion reached from these analyses is that triggered ion-acoustic waves are highly likely to have a natural origin although the possibility that they are artifacts unrelated to processes occurring in the natural plasma cannot be eliminated. This inability to absolutely rule out artifacts as the source of a measured result is a characteristic of all measurements.
description: 21 pages, 9 figures, 1 table. arXiv admin note: substantial text overlap with arXiv:2211.14415
Point Source C-Band Mueller Matrices for the Green Bank Telescope
Creators: name: Fallon, Paul
name: Smits, Derck P
name: Ghosh, Tapasi
name: Salter, Christopher J.
name: Salas, Pedro
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences

description: C-Band Mueller matrices for the Green Bank Telescope are presented here which enable on-sky Stokes parameters for point sources at the beam center to be determined. Standard calibrators, 3C138 and 3C286, were observed using the Spider program to steer the telescope across a broad range of Right Ascensions on both sides of the zenith transit. For this analysis, only the observations at the peak of the Spider pattern were used rather than the full sweep of the runs. Therefore, the results presented here only apply to point sources at the beam center. The Mueller matrices are shown to vary with frequency and with use of the Hi-Cal or Lo-Cal noise diodes, due to the relative calibration gain between the X and Y components of the feed. However, the relative calibration gain can be determined from observations of a source with known polarization. Correcting the data for the relative calibration gain prior to data analysis allows for use of a frequency independent Mueller matrix. This generic Mueller matrix is shown to provide reliable C-Band polarization measurements.
description: Acceptance for publication in The Astronomical Journal
Theoretical tidal evolution constants for stellar models from the pre-main sequence to the white dwarf stage Apsidal motion constants, moment of inertia, and gravitational potential energy
Creators: name: Claret, A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: One of the most reliable means of studying the stellar interior is through the apsidal motion in double line eclipsing binary systems since these systems present errors in masses, radii, and effective temperatures of only a few per cent. On the other hand, the theoretical values of the apsidal motion to be compared with the observed values depend on the stellar masses of the components and more strongly on their radii (fifth power).The main objective of this work is to make available grids of evolutionary stellar models that, in addition to the traditional parameters (e.g. age, mass, log g, T$_{\rm eff}$), also contain the necessary parameters for the theoretical study of apsidal motion and tidal evolution. This information is useful for the study of the apsidal motion in eclipsing binaries and their tidal evolution, and can also be used for the same purpose in exoplanetary systems. All models were computed using the MESA package. We consider core overshooting for models with masses $\ge$ 1.2 M$_\odot$. For the amount of core overshooting we adopted a recent relationship for mass $\times$ core overshooting. We adopted for the mixing-length parameter $α_{\rm MLT}$ the value 1.84 (the solar-calibrated value). Mass loss was taken into account in two evolutionary phases. The models were followed from the pre-main sequence phase to the white dwarf (WD) stage.The evolutionary models containing age,luminosity, log g, and Teff, as well as the first three harmonics of the internal stellar structure (k$_2$, k$_3$, and k$_4$), the radius of gyration $β$ y, and the dimensionless variable $α$, related to gravitational potential energy, are presented in 69 tables covering three chemical compositions: [Fe/H] = -0.50, 0.00, and 0.50. Additional models with different input physics are available.
Quantum optical circulator controlled by a single chirally coupled atom
Creators: name: Scheucher, Michael
name: Hilico, Adèle
name: Will, Elisa
name: Volz, Jürgen
name: Rauschenbeutel, Arno
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We demonstrate a fiber-integrated quantum optical circulator that is operated by a single atom and that relies on the chiral interaction between emitters and transversally confined light. Like its counterparts in classical optics, our circulator exhibits an inherent asymmetry between light propagation in the forward and the backward direction. However, rather than a magnetic field or a temporal modulation, it is the internal quantum state of the atom that controls the operation direction of the circulator. This working principle is compatible with preparing the circulator in a coherent superposition of its operational states. Such a quantum circulator may thus become a key element for routing and processing quantum information in scalable integrated optical circuits. Moreover, it features a strongly nonlinear response at the single-photon level, thereby enabling, e.g., photon number-dependent routing and novel quantum simulation protocols.
description: 22 pages, 5 figures
Evidence of a Quasi-periodic Global-scale Oscillation in the Near-Surface Shear Layer of the Sun
Creators: name: Bogart, Richard S.
name: Baldner, Charles S.
name: Basu, Sarbani
name: Howe, Rachel
name: Soares, Maria Cristina Rabello
Publisher: name: arXiv
Year: 2023
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present evidence of hitherto undiscovered global-scale oscillations in the near-surface shear layer of the Sun. These oscillations are seen as large scale variations of radial shear in both the zonal and meridional flows relative to their mean values. The variations cover all or most of a visible hemisphere, and reverse with a timescale on the order of a solar rotation. A large annual variation in the meridional shear anomaly is understandable in terms of the tilt of the rotation axis, but the rapid oscillations of the shear anomalies in both zonal and the meridional directions appear to be modulated in a more complex, not-quite annual way, although the latter are also strongly modulated by the projected rotational axis angle. Small-scale anomalies in the neighborhood of active regions lend support to their solar origin and physical interpretation. These results were obtained by analyzing ring-diagram fits of low-order modes in high-resolution Doppler data from the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory.
description: Accepted for publication in Astrophysical Journal Letters
In-medium bound-state formation and inhomogeneous condensation in Fermi gases in a hard-wall box
Creators: name: Roscher, Dietrich
name: Braun, Jens
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: Superconductivity (cond-mat.supr-con)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The formation of bosonic bound states underlies the formation of a superfluid ground state in the many-body phase diagram of ultracold Fermi gases. We study bound-state formation in a spin- and mass-imbalanced ultracold Fermi gas confined in a box with hard-wall boundary conditions. Because of the presence of finite Fermi spheres, the center-of-mass momentum of the potentially formed bound states can be finite, depending on the parameters controlling mass and spin imbalance as well as the coupling strength. We exploit this observation to estimate the potential location of inhomogeneous phases in the many-body phase diagram as a function of spin- and mass imbalance as well as the box size. Our results suggest that a hard-wall box does not alter substantially the many-body phase diagram calculated in the thermodynamic limit. Therefore, such a box may serve as an ideal trap potential to bring experiment and theory closely together and facilitate the search for exotic inhomogeneous ground states.
description: 12 pages, 4 figures
Runtime Analysis of Quality Diversity Algorithms
Creators: name: Bossek, Jakob
name: Sudholt, Dirk
Publisher: name: arXiv
Year: 2023
Subjects: subject: Neural and Evolutionary Computing (cs.NE)
subject: FOS: Computer and information sciences

description: Quality diversity~(QD) is a branch of evolutionary computation that gained increasing interest in recent years. The Map-Elites QD approach defines a feature space, i.e., a partition of the search space, and stores the best solution for each cell of this space. We study a simple QD algorithm in the context of pseudo-Boolean optimisation on the ``number of ones'' feature space, where the $i$th cell stores the best solution amongst those with a number of ones in $[(i-1)k, ik-1]$. Here $k$ is a granularity parameter $1 \leq k \leq n+1$. We give a tight bound on the expected time until all cells are covered for arbitrary fitness functions and for all $k$ and analyse the expected optimisation time of QD on \textsc{OneMax} and other problems whose structure aligns favourably with the feature space. On combinatorial problems we show that QD finds a ${(1-1/e)}$-approximation when maximising any monotone sub-modular function with a single uniform cardinality constraint efficiently. Defining the feature space as the number of connected components of a connected graph, we show that QD finds a minimum spanning tree in expected polynomial time.
description: This version fixes a bug in Theorem 6.1 of the paper published at GECCO 2023. It claims an upper bound of $O(nm \log n)$ for the expected time to locate the empty edge set, but the proof arguments were insufficient (thanks to Frank Neumann for spotting this). We now give a bound of $O(nm \log(n w_{\max}))$ for integer edge weights where $w_{\max}$ is the largest edge weight
Content-Based Image Retrieval Using Multiresolution Analysis Of Shape-Based Classified Images
Creators: name: El-Henawy, I. M.
name: Ahmed, Kareem
Publisher: name: arXiv
Year: 2016
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: Content-Based Image Retrieval (CBIR) systems have been widely used for a wide range of applications such as Art collections, Crime prevention and Intellectual property. In this paper, a novel CBIR system, which utilizes visual contents (color, texture and shape) of an image to retrieve images, is proposed. The proposed system builds three feature vectors and stores them into MySQL database. The first feature vector uses descriptive statistics to describe the distribution of data in each channel of RGB channels of the image. The second feature vector describes the texture using eigenvalues of the 39 sub-bands that are generated after applying four levels 2D DWT in each channel (red, green and blue channels) of the image. These wavelets sub-bands perfectly describes the horizontal, vertical and diagonal edges that exist in the multi-resolution analysis of the image. The third feature vector describes the basic shapes that exist in the skeletonization version of the black and white representation of the image. Experimental results on a private MYSQL database that consists of 10000 images, using color, texture, shape and stored relevance feedbacks, showed 96.4% average correct retrieval rate in an efficient recovery time.
Controlling light propagation in multimode fibers for imaging, spectroscopy and beyond
Creators: name: Cao, Hui
name: Čižmár, Tomáš
name: Turtaev, Sergey
name: Tyc, Tomáš
name: Rotter, Stefan
Publisher: name: arXiv
Year: 2023
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Light transport in a highly multimode fiber exhibits complex behavior in space, time, frequency and polarization, especially in the presence of mode coupling. The newly developed techniques of spatial wavefront shaping turn out to be highly suitable to harness such enormous complexity: a spatial light modulator enables precise characterization of field propagation through a multimode fiber, and by adjusting the incident wavefront it can accurately tailor the transmitted spatial pattern, temporal profile and polarization state. This unprecedented control leads to multimode fiber applications in imaging, endoscopy, optical trapping and microfabrication. Furthermore, the output speckle pattern from a multimode fiber encodes spatial, temporal, spectral and polarization properties of the input light, allowing such information to be retrieved from spatial measurements only. This article provides an overview of recent advances and breakthroughs in controlling light propagation in multimode fibers, and discusses newly emerging applications.
description: 81 pages, 39 figures; invited review article for Advances in Optics and Photonics; feedback by the community is very welcome
Addendum to "Super-GCA from $\mathcal{N}=(2,2)$ super-Virasoro": Super-GCA connection with tensionless strings
Creators: name: Mandal, Ipsita
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In this addendum, we consider the connection between certain $2d$ super-GCA, obtained from the parametric contractions of $2d$ SCFTs, which can describe the constraint algebra of null spinning strings.
description: Addendum including a note on how super-SGCA from a different group contraction of SCFTs can relate to tensionless strings
Personalized Classifier for Food Image Recognition
Creators: name: Horiguchi, Shota
name: Amano, Sosuke
name: Ogawa, Makoto
name: Aizawa, Kiyoharu
Publisher: name: arXiv
Year: 2018
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: Multimedia (cs.MM)
subject: FOS: Computer and information sciences

description: Currently, food image recognition tasks are evaluated against fixed datasets. However, in real-world conditions, there are cases in which the number of samples in each class continues to increase and samples from novel classes appear. In particular, dynamic datasets in which each individual user creates samples and continues the updating process often have content that varies considerably between different users, and the number of samples per person is very limited. A single classifier common to all users cannot handle such dynamic data. Bridging the gap between the laboratory environment and the real world has not yet been accomplished on a large scale. Personalizing a classifier incrementally for each user is a promising way to do this. In this paper, we address the personalization problem, which involves adapting to the user's domain incrementally using a very limited number of samples. We propose a simple yet effective personalization framework which is a combination of the nearest class mean classifier and the 1-nearest neighbor classifier based on deep features. To conduct realistic experiments, we made use of a new dataset of daily food images collected by a food-logging application. Experimental results show that our proposed method significantly outperforms existing methods.
description: Accepted to IEEE Transaction on Multimedia. http://ieeexplore.ieee.org/document/8316919/
Inferring redshift and energy distributions of fast radio bursts from the first CHIME/FRB catalog
Creators: name: Tang, Li
name: Lin, Hai-Nan
name: Li, Xin
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: We reconstruct the extragalactic dispersion measure \ -- redshift relation (${\rm DM_E}-z$ relation) from well-localized fast radio bursts (FRBs) using Bayesian inference method. Then the ${\rm DM_E}-z$ relation is used to infer the redshift and energy of the first CHIME/FRB catalog. We find that the distributions of extragalactic dispersion measure and inferred redshift of the non-repeating CHIME/FRBs follow cut-off power law, but with a significant excess at the low-redshift range. We apply a set of criteria to exclude events which are susceptible to selection effect, but find that the excess at low redshift still exists in the remaining FRBs (which we call Gold sample). The cumulative distributions of fluence and energy for both the full sample and the Gold sample do not follow the simple power law, but they can be well fitted by the bent power law. The underlying physical implications remain to be further investigated.
description: 13 pages plus one long table, accepted by Chinese Physics C
Perturbative treatment of the non-linear q-Schrödinger and q-Klein-Gordon equations
Creators: name: Zamora, D. J.
name: Rocca, M. C.
name: Plastino, A.
name: Ferri, G. L.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Interesting nonlinear generalization of both Schrödinger's and Klein-Gordon's equations have been recently advanced by Tsallis, Rego-Monteiro, and Tsallis (NRT) in [Phys. Rev. Lett. {\bf 106}, 140601 (2011)]. There is much current activity going on in this area. The non-linearity is governed by a real parameter $q$. It is a fact that the ensuing non linear q-Schrödinger and q-Klein-Gordon equations are natural manifestations of very high energy phenomena, as verified by LHC-experiments. This happens for $q-$values close to unity [Nucl. Phys. A {\bf 955}, 16 (2016), Nucl. Phys. A {\bf 948}, 19 (2016)]. It is also well known that q-exponential behavior is found in quite different settings. An explanation for such phenomenon was given in [Physica A {\bf 388}, 601 (2009)] with reference to empirical scenarios in which data are collected via set-ups that effect a normalization plus data's pre-processing. Precisely, the ensuing normalized output was there shown to be q-exponentially distributed if the input data display elliptical symmetry, generalization of spherical symmetry, a frequent situation. This makes it difficult, for q-values close to unity, to ascertain whether one is dealing with solutions to the ordinary Schrödinger equation (whose free particle solutions are exponentials, and for which $q=1$) or with its NRT nonlinear q-generalizations, whose free particle solutions are q-exponentials. In this work we provide a careful analysis of the $q \sim 1$ instance via a perturbative analysis of the NRT equations.
description: 30 pages, 5 figures
Beyond Convexity -- Contraction and Global Convergence of Gradient Descent
Creators: name: Wensing, Patrick M.
name: Slotine, Jean-Jacques E.
Publisher: name: arXiv
Year: 2018
Subjects: subject: Optimization and Control (math.OC)
subject: FOS: Mathematics

description: This paper considers the analysis of continuous time gradient-based optimization algorithms through the lens of nonlinear contraction theory. It demonstrates that in the case of a time-invariant objective, most elementary results on gradient descent based on convexity can be replaced by much more general results based on contraction. In particular, gradient descent converges to a unique equilibrium if its dynamics are contracting in any metric, with convexity of the cost corresponding to the special case of contraction in the identity metric. More broadly, contraction analysis provides new insights for the case of geodesically-convex optimization, wherein non-convex problems in Euclidean space can be transformed to convex ones posed over a Riemannian manifold. In this case, natural gradient descent converges to a unique equilibrium if it is contracting in any metric, with geodesic convexity of the cost corresponding to contraction in the natural metric. New results using semi-contraction provide additional insights into the topology of the set of optimizers in the case when multiple optima exist. Furthermore, they show how semi-contraction may be combined with specific additional information to reach broad conclusions about a dynamical system. The contraction perspective also easily extends to time-varying optimization settings and allows one to recursively build large optimization structures out of simpler elements. Extensions to natural primal-dual optimization and game-theoretic contexts further illustrate the potential reach of these new perspectives.
description: author typesetting of extended final version (expanded appendix)
Role of Hydrogen in the Electronic Properties of CaFeAsH-based Superconductors
Creators: name: Huang, Y. N.
name: Liu, D. Y.
name: Zou, L. J.
name: Pickett, W. E.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: The electronic and magnetic properties of the new hydride superconductor CaFeAsH, which superconducts up to 47 K when electron-doped with La, and the isovalent alloy system CaFeAsH$_{1-x}$F$_x$ are investigated using density functional based methods. The $\vec Q = (π,π,0)$ peak of the nesting function $ξ(\vec q)$ is found to be extremely strong and sharp, and additional structure in $ξ(\vec q)$ associated with the near-circular Fermi surfaces (FSs) that may impact low energy excitations is quantified. The unusual band introduced by H, which shows strong dispersion perpendicular to the FeAs layers, is shown to be connected to a peculiar van Hove singularity just below the Fermi level. This band provides a three dimensional electron ellipsoid Fermi surface not present in other Fe-based superconducting materials nor in CaFeAsF. Electron doping by 25\% La or Co has minor affect on this ellipsoid Fermi surface, but suppresses FS nesting strongly, consistent with the viewpoint that eliminating strong nesting and the associated magnetic order allows high T$_c$ superconductivity to emerge. Various aspects of the isovalent alloy system CaFeAsH$_{1-x}$F$_x$ and means of electron doping are discussed in terms of influence of incipient bands.
description: 9 pages, 8 figures
Linear spectropolarimetry across the optical spectrum of Herbig Ae/Be stars
Creators: name: Ababakr, K. M.
name: Oudmaijer, R. D.
name: Vink, J. S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: We present the results of spectropolarimetric observations of 12 Herbig Ae/Be objects. Our data have the largest spectropolarimetric wavelength coverage, 4560 Å to 9480 Å, published to date. A change in linear polarisation across the Hα line, is detected in all objects. Such a line effect reveals the fact that stellar photons are scattered off free electrons that are not distributed in a spherically symmetric volume, suggesting the presence of small disks around these accreting objects. Thanks to the large wavelength coverage, we can report that Hα is the spectral line in the optical wavelength range that is most sensitive to revealing deviations from spherical symmetry, and the one most likely to show a line effect across the polarisation in such cases. Few other spectral lines display changes in polarisation across the line. In addition, Hα is the only line which shows an effect across its absorption component in some sources. We present a scenario explaining this finding and demonstrate that the detection of the line effect strongly relies on the number of photons scattered into our line of sight. We highlight the special case of R Mon, which is the only object in our sample to show many lines with a polarisation effect, which is much stronger than in all other objects. Given that the object and its nebulosity is spatially resolved, we argue that this is due to scattering of the stellar and emission spectrum off circumstellar dust.
description: 22 pages, 13 figures, Accepted for publication in MNRAS
Threshold singularities, dispersion relations and fixed-order perturbative calculations
Creators: name: Beneke, Martin
name: Ruiz-Femenia, Pedro
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: We show how to correctly treat threshold singularities in fixed-order perturbative calculations of the electron anomalous magnetic moment and hadronic pair production processes such as top pair production. With respect to the former, we demonstrate the equivalence of the "non-perturbative", resummed treatment of the vacuum polarization contribution, whose spectral function exhibits bound state poles, with the fixed-order calculation by identifying a threshold localized term in the four-loop spectral function. In general, we find that a modification of the dispersion relation by threshold subtractions is required to make fixed-order calculations well-defined and provide the subtraction term. We then solve the apparent problem of a divergent convolution of the partonic cross section with the parton luminosity in the computation of the top pair production cross section starting from the fourth-order correction. We find that when the computation is performed in the usual way as an integral of real and virtual corrections over phase space at a given order in the expansion in the strong coupling, an additional contribution has to be added at N3LO.
description: 15 pages, 3 figures
The Tiered Radio Extragalactic Continuum (T-RECS) simulation II: HI emission and continuum-HI cross-correlation
Creators: name: Bonaldi, Anna
name: Hartley, Philippa
name: Ronconi, Tommaso
name: De Zotti, Gianfranco
name: Bonato, Matteo
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: In this paper we extend the Tiered Radio Extragalactic Continuum Simulation (T-RECS) to include HI emission. The HI T-RECS model is based on the most recent HI mass function estimates, combined with prescriptions to convert HI mass to total integrated HI flux. It further models source size, morphology and kinematics, including rotational velocity and HI line width. The continuum T-RECS model is updated to improve the agreement with deeper number counts available at 150\,MHz. The model for star-forming galaxies (SFGs) is also modified according to the most recent indications of a star formation rate (SFR)--radio luminosity relation, which depends primarily on stellar mass rather than redshift. We further introduce prescriptions to associate an HI mass to the T-RECS radio continuum SFG and Active Galactic Nuclei (AGN) populations. This gives us a way to meaningfully associate counterparts between HI and continuum catalogues, thus building HI $\times$ continuum simulated observations. Clustering properties of the sources in both HI and continuum are reproduced by associating the galaxies to dark matter haloes of a cosmological simulation. We deliver a set of mock catalogues, as well as the code to produce them, which can be used for simulating observations and predicting results from radio surveys with existing and forthcoming radio facilities, such as the Square Kilometre Array (SKA)
description: 18 pages, 10 figures, accepted by MNRAS
D4.7 – BIMprove Asset Portfolio
Creators: name: Edvardsen, Dag Fjeld
name: Gabor Sziebig
Publisher: name: Zenodo
Year: 2023
Subjects: bimprove
asset portfolio
results
exploitation
impact

description: The deliverable presents a collection of exploitable results achieved by the project, which created impact during its lifetime and with the potential to contribute for further work, research or innovations. This includes all peer-reviewed and technical publications, source code repository, open research data, educational material, and standardisation/ open-source contributions.
Possibilistic simulation of quantum circuits by classical circuits
Creators: name: Wang, Daochen
Publisher: name: arXiv
Year: 2019
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: In breakthrough work, Bravyi, Gosset, and König (BGK) [Science, 2018] unconditionally proved that constant depth quantum circuits are more powerful than their classical counterparts. Their result is equivalent to saying that a particular family of constant depth quantum circuits takes classical circuits at least $Ω(\log n)$ depth to "simulate", in a certain sense. In our paper, we formalise their sense of simulation, which we call "possibilistic simulation" or "p-simulation", and construct explicit classical circuits that can p-simulate any depth-$d$ quantum circuit with Clifford and $t$ $T$-gates in depth $O(d+t)$. Our classical circuits use $\{\text{NOT, AND, OR}\}$ gates of fan-in $\leq 2$.
description: 8 pages; v2: major revision of v1 claims due to circuit depth costing error, cf. footnote 29; v3: reverted title back to v1's, refined main theorem statement, and improved presentation; v4: added comparison to weak and strong simulation, further improved presentation
Probing compressed mass spectra in the type-II seesaw model at the LHC
Creators: name: Ashanujjaman, Saiyad
name: Maharathy, Siddharth P.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: FOS: Physical sciences

description: Despite a great deal of effort in searching for the triplet-like Higgses in the type-II seesaw model, evidence for their production is yet to be found at the LHC. As such, one might be in the balance regarding this model's relevance at the electroweak scale. In this work, we peruse a scenario, akin to compressed mass spectra in Supersymmetry, which might have eluded the experimental searches thus far. We perform a multivariate analysis to distinguish signals with a pair of same-sign leptons with low invariant mass from the SM processes, including those accruing from fake leptons and electron charge misidentification, and find that a significant part of the hitherto unconstrained parameter space could be probed with the already collected Run 2 13 TeV LHC and future HL-LHC data.
description: 10 pages (including references)
On the Representation theory of the Infinite Temperley-Lieb algebra
Creators: name: Moore, Stephen T.
Publisher: name: arXiv
Year: 2019
Subjects: subject: Quantum Algebra (math.QA)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: We begin the study of the representation theory of the infinite Temperley-Lieb algebra. We fully classify its finite dimensional representations, then introduce infinite link state representations and classify when they are irreducible or indecomposable. We also define a construction of projective indecomposable representations for $TL_{n}$ that generalizes to give extensions of $TL_{\infty}$ representations. Finally we define a generalization of the spin chain representation and conjecture a generalization of Schur-Weyl duality.
Finite-size relaxational dynamics of a spike random matrix spherical model
Creators: name: Pimenta, Pedro H. de Freitas
name: Stariolo, Daniel A.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We present a thorough numerical analysis of the relaxational dynamics of the Sherrington-Kirkpatrick spherical model with an additive non-disordered perturbation for large but finite sizes $N$. In the thermodynamic limit and at low temperatures, the perturbation is responsible for a phase transition from a spin glass to a ferromagnetic phase. We show that finite size effects induce the appearance of a distinctive slow regime in the relaxation dynamics, the extension of which depends on the size of the system and also on the strength of the non-disordered perturbation. The long time dynamics is characterized by the two largest eigenvalues of a spike random matrix which defines the model, and particularly by the statistics of the gap between them. We characterize the finite size statistics of the two largest eignevalues of the spike random matrices in the different regimes, sub-critical, critical and super-critical, confirming some known results and anticipating others, even in the less studied critical regime. We also numerically characterize the finite size statistics of the gap, which we hope may encourage analytical work which is lacking. Finally, we compute the finite size scaling of the long time relaxation of the energy, showing the existence of power laws with exponents that depend on the strenght of the non-disordered perturbation, in a way which is governed by the finite size statistics of the gap.
description: 14 pages, 10 figures
Quantifying heterogeneity in ecohydrological partitioning in urban green spaces through the integration of empirical and modelling approaches
Creators: name: Stevenson, Jamie Lee
name: Birkel, Christian
name: Comte, Jean-Christophe
name: Tetzlaff, Doerthe
name: Marx, Christian
name: Neill, Aaron
name: Maneta, Marco
name: Boll, Jan
name: Soulsby, Chris
Publisher: name: Springer Science and Business Media LLC
Year: 2023
Subjects: subject: 500 Naturwissenschaften und Mathematik::550 Geowissenschaften, Geologie::551 Geologie, Hydrologie, Meteorologie
subject: urban ecosystem services
subject: water balances
subject: ecohydrological modelling
subject: precipitation partitioning
subject: infiltration
subject: evapotranspiration

description: Urban green spaces (UGS) can help mitigate hydrological impacts of urbanisation and climate change through precipitation infiltration, evapotranspiration and groundwater recharge. However, there is a need to understand how precipitation is partitioned by contrasting vegetation types in order to target UGS management for specific ecosystem services. We monitored, over one growing season, hydrometeorology, soil moisture, sapflux and isotopic variability of soil water under contrasting vegetation (evergreen shrub, evergreen conifer, grassland, larger and smaller deciduous trees), focussed around a 150-m transect of UGS in northern Scotland. We further used the data to develop a one-dimensional model, calibrated to soil moisture observations (KGE’s generally > 0.65), to estimate evapotranspiration and groundwater recharge. Our results evidenced clear inter-site differences, with grassland soils experiencing rapid drying at the start of summer, resulting in more fractionated soil water isotopes. Contrastingly, the larger deciduous site saw gradual drying, whilst deeper sandy upslope soils beneath the evergreen shrub drained rapidly. Soils beneath the denser canopied evergreen conifer were overall least responsive to precipitation. Modelled ecohydrological fluxes showed similar diversity, with median evapotranspiration estimates increasing in the order grassland (193 mm) < evergreen shrub (214 mm) < larger deciduous tree (224 mm) < evergreen conifer tree (265 mm). The evergreen shrub had similar estimated median transpiration totals as the larger deciduous tree (155 mm and 128 mm, respectively), though timing of water uptake was different. Median groundwater recharge was greatest beneath grassland (232 mm) and lowest beneath the evergreen conifer (128 mm). The study showed how integrating observational data and simple modelling can quantify heterogeneities in ecohydrological partitioning and help guide UGS management.
First test of a high voltage feedthrough for liquid Argon TPCs connected to a 300 kV power supply
Creators: name: Cantini, C.
name: Gendotti, A.
name: Bueno, L. Molina
name: Murphy, S.
name: Radics, B.
name: Regenfus, C.
name: Rigaut, Y-A.
name: Rubbia, A.
name: Sergiampietri, F.
name: Viant, T.
name: Wu, S.
Publisher: name: arXiv
Year: 2016
Subjects: subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: Voltages above a hundred kilo-volt will be required to generate the drift field of future very large liquid Argon Time Projection Chambers. The most delicate component is the feedthrough whose role is to safely deliver the very high voltage to the cathode through the thick insulating walls of the cryostat without compromising the purity of the argon inside. This requires a feedthrough that is typically meters long and carefully designed to be vacuum tight and have small heat input. Furthermore, all materials should be carefully chosen to allow operation in cryogenic conditions. In addition, electric fields in liquid argon should be kept below a threshold to reduce risks of discharges. The combination of all above requirements represents significant challenges from the design and manufacturing perspective. In this paper, we report on the successful operation of a feedthrough satisfying all the above requirements. The details of the feedthrough design and its manufacturing steps are provided. Very high voltages up to unprecedented voltages of -300 kV could be applied during long periods repeatedly. A source of instability was observed, which was specific to the setup configuration which was used for the test and not due to the feedthrough itself.
description: 13 pages, 9 figures
Snapshot Averaged Matrix Pencil Method (SAM) For Direction of Arrival Estimation
Creators: name: Tanti, Harsha A.
name: Datta, Abhirup
name: Ananthakrishnan, S.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences

description: The estimation of the direction of electromagnetic (EM) waves from a radio source using electrically short antennas is one of the challenging problems in the field of radio astronomy. In this paper we have developed an algorithm which performs better in direction and polarization estimations than the existing algorithms. Our proposed algorithm Snapshot Averaged Matrix Pencil Method (SAM) is a modification to the existing Matrix Pencil Method (MPM) based Direction of Arrival (DoA) algorithm. In general, MPM estimates DoA of the incoherent EM waves in the spectra using unitary transformations and least square method (LSM). Our proposed SAM modification is made in context to the proposed Space Electric and Magnetic Sensor (SEAMS) mission to study the radio universe below 16 MHz. SAM introduces a snapshot averaging method to improve the incoherent frequency estimation improving the accuracy of estimation. It can also detect polarization to differentiate between Right Hand Circular Polarlization (RHCP), Right Hand Elliptical Polarlization (RHEP), Left Hand Circular Polarlization (LHCP), Left Hand Elliptical Polarlization (LHEP) and Linear Polarlization (LP). This paper discusses the formalism of SAM and shows the initial results of a scaled version of a DoA experiment at a resonant frequency of ~72 MHz.
Projective covers of flat contramodules
Creators: name: Bazzoni, Silvana
name: Positselski, Leonid
name: Stovicek, Jan
Publisher: name: arXiv
Year: 2019
Subjects: subject: Rings and Algebras (math.RA)
subject: Category Theory (math.CT)
subject: FOS: Mathematics

description: We show that a direct limit of projective contramodules (over a right linear topological ring) is projective if it has a projective cover. A similar result is obtained for $\infty$-strictly flat contramodules of projective dimension not exceeding $1$, using an argument based on the notion of the topological Jacobson radical. Covers and precovers of direct limits of more general classes of objects, both in abelian categories with exact and with nonexact direct limits, are also discussed, with an eye towards the Enochs conjecture about covers and direct limits, using locally split (mono)morphisms as the main technique. In particular, we offer a simple elementary proof of the Enochs conjecture for the left class of an $n$-tilting cotorsion pair in an abelian category with exact direct limits.
description: LaTeX 2e with pb-diagram and xy-pic, 31 pages, 3 commutative diagrams; v.2: a new author joined, the title changed, paper greatly expanded, main result generalized from countable to uncountable direct limits; v.4: Introduction expanded, many references added, several misprints corrected, the numbering of sections shifted to agree with the journal version, former Remark 7.4 is now Corollary 8.4
Homotopy analysis method applied to second-order frequency mixing in nonlinear optical dielectric media
Creators: name: Dawson, Nathan J.
name: Kounta, Moussa
Publisher: name: arXiv
Year: 2019
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: The classical problem of three-wave mixing in a nonlinear optical medium is investigated using the homotopy analysis method (HAM). We show that the power series basis builds a generic polynomial expression that can be used to study three-wave mixing for arbitrary input parameters. The phase-mismatched and perfectly phase matched cases are investigated. Parameters that result in generalized sum- and difference-frequency generation are studied using HAM with a power series basis and compared to an explicit finite-difference approximation. The convergence region is extended by increasing the auxiliary parameter.
description: 4 figures
Connecting the Young Pulsars in Milky Way Globular Clusters with White Dwarf Mergers and the M81 Fast Radio Burst
Creators: name: Kremer, Kyle
name: Fuller, Jim
name: Piro, Anthony L.
name: Ransom, Scott M.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: The detections of four apparently young radio pulsars in the Milky Way globular clusters are difficult to reconcile with standard neutron star formation scenarios associated with massive star evolution. Here we discuss formation of these young pulsars through white dwarf mergers in dynamically-old clusters that have undergone core collapse. Based on observed properties of magnetic white dwarfs, we argue neutron stars formed via white dwarf merger are born with spin periods of roughly $10-100\,$ms and magnetic fields of roughly $10^{11}-10^{13}\,$G. As these neutron stars spin down via magnetic dipole radiation, they naturally reproduce the four observed young pulsars in the Milky Way clusters. Rates inferred from $N$-body cluster simulations as well as the binarity, host cluster properties, and cluster offsets observed for these young pulsars hint further at a white dwarf merger origin. These young pulsars may be descendants of neutron stars capable of powering fast radio bursts analogous to the bursts observed recently in a globular cluster in M81.
description: 5 pages, 2 figures, 1 table. Accepted for publication in MNRAS
Nobeyama 45-m CO J=1-0 Observations of Luminous Type 1 AGNs at $z\approx0.3$
Creators: name: Michiyama, Tomonari
name: Zhuang, Ming-Yang
name: Shangguan, Jinyi
name: Yesuf, Hassen M.
name: Kaneko, Hiroyuki
name: Ho, Luis C.
Publisher: name: arXiv
Year: 2023
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: We have performed CO J =1-0 observations of ten galaxies hosting luminous ($L_{\rm bol} > 10^{46}\,{\rm erg\,s^{-1}}$) type 1 active galactic nuclei (AGNs) with the Nobeyama 45-m radio telescope. The targets are selected because they are expected to be rich in molecular gas based on their high nebular dust extinction ($A_{\rm V}$). However, no significant CO emission lines were detected in any of the targets. The upper limits of the CO J=1-0 luminosities are lower than expected given the molecular gas mass inferred from the nebular $A_{\rm V}$. This inconsistency may be due to overestimated $A_{\rm V}$ values due to the lack of stellar absorption correction. Considering more reliable $A_{\rm V}$ values, the CO J=1-0 non-detections by Nobeyama 45-m are natural. This suggests that our results do not contradict the conversion methods from $A_{\rm V}$ to molecular gas mass proposed in the literature. This survey suggests that careful $A_{\rm V}$ measurements as well as CO observations are still needed to improve the measurements or estimates of the molecular gas content of galaxies hosting luminous AGNs.
description: 8 pages, 6 figures, Accepted for publication in PASJ
Constraints on Undetected Long-Period Binaries in the Known Pulsar Population
Creators: name: Jones, Megan L.
name: Kaplan, David L.
name: McLaughlin, Maura A.
name: Lorimer, Duncan R.
Publisher: name: arXiv
Year: 2023
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences

description: Although neutron star-black hole binaries have been identified through mergers detected in gravitational waves, a pulsar-black hole binary has yet to be detected. While short-period binaries are detectable due to a clear signal in the pulsar's timing residuals, effects from a long-period binary could be masked by other timing effects, allowing them to go undetected. In particular, a long-period binary measured over a small subset of its orbital period could manifest via time derivatives of the spin-frequency incompatible with isolated pulsar properties. We assess the possibility of pulsars having unknown companions in long-period binaries and put constraints on the range of binary properties that may remain undetected in current data, but that may be detectable with further observations. We find that for 35% of canonical pulsars with published higher order derivatives, the precision of measurements is not enough to confidently reject binarity (period greater than ~2 kyr), and that a black-hole binary companion could not be ruled out for a sample of pulsars without published constraints if the period is greater than 1 kyr. While we find no convincing cases in the literature, we put more stringent limits on orbital period and longitude of periastron for the few pulsars with published higher-order frequency derivatives (n greater than 3). We discuss the detectability of candidates and find that a sample pulsar in a 100 yr orbit could be detectable within 5-10 yr.
description: 9 pages, 5 figures. Accepted to ApJ