cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Three length scales colloidal gels: the clusters of clusters versus the interpenetrating clusters approach
Creators: name: Bouthier, Louis-Vincent
name: Gibaud, Thomas
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Typically, in quiescent conditions, attractive colloids at low volume fractions form fractal gels structured into two length scales: the colloidal and the fractal cluster scales. However when flow interfere with gelation colloidal fractal gels may display three distinct length scales [Dagès, et al., Soft Matter 18, 6645 (2022)]. Following those recent experimental investigations, we derive two models that account for the structure and the rheological properties of such atypical colloidal gels. The gel elasticity is inferred from scaling arguments and the structure is translated into scattering intensities following the global scattering functions approach proposed by Beaucage and typically measured in small angle X-ray scattering (SAXS). In both models, we consider that the colloids condensate into fractal clusters. In the clusters of clusters model, the clusters form superagregates which then build the gel network. In the interpenetrating clusters model, the clusters interpenetrate one-another to form the gel network. Those two models are then utilised to analyse rheo-SAXS experiments carried out on carbon black gels formed through flow cessation. The results of the analysis vouch for the clusters of clusters model with a densification of the structures as the gel characteristic length scales increase.
Effective action of a self-interacting scalar field on brane
Creators: name: Li, Cheng-Chen
name: Cui, Zheng-Quan
name: Sui, Tao-Tao
name: Liu, Yu-Xiao
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In extra dimensional theories, the four-dimensional field theory is reduced from a fundamental field theory in the bulk spacetime by integrating the extra dimensional part. In this paper we investigate the effective action of a self-interacting scalar field on a brane in the five-dimensional thick braneworld scenario. We consider two typical thick brane solutions and obtain the Pöschl-Teller and harmonic potentials of the Kaluza-Klein (KK) modes, respectively. The analytical mass spectra and wave functions along extra dimension of the KK modes are obtained. Further, the effective coupling constant between different KK particles, cross section, and decay rate for some processes of the KK particles are related to the fundamental coupling in five dimensions and the new physics energy scale. Some interesting properties of these interactions are found with these calculations. The KK particles with higher mode have longer lifetime, and they almost do not interact with ordinary matter on the brane if their mode numbers are large enough. Thus, these KK particles with higher modes might be a candidate of dark matter.
description: 10 pages, 6 figures
Einstein-Vlasov system with equal-angular momenta in $\text{AdS}_5$
Creators: name: Asami, Hiroki
name: Yoo, Chul-Moon
name: Kitaku, Ryo
name: Uemichi, Keiya
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We investigate solutions of the $5$--dimensional rotating Einstein-Vlasov system with an $R \times SU(2) \times U(1)$ isometry group. In a five-dimensional spacetime, there are two independent planes of rotation, thus, considering $U(1)$ symmetry on each rotation plane, we may impose an $R\times U(1) \times U(1)$ isometry to a stationary spacetime. Furthermore, when the values of the two angular momenta are equal to each other, the spatial symmetry gets enhanced to $R\times SU(2)\times U(1)$ symmetry, and the spacetime has a cohomogeneity-1 structure. Imposing the same symmetry to the distribution function of the particles of which the Vlasov system consists, the distribution function can be dependent on three mutually independent and commutative conserved charges for particle motion (energy, total angular momentum on $SU(2)$ and $U(1)$ angular momentum). We consider the distribution function which exponentially depends on the $U(1)$ angular momentum and reduces to the thermal equilibrium state in spherical symmetry. Then, in this paper, we numerically construct solutions of the asymptotically AdS Einstein--Vlasov system.
description: 21 pages
Correlating microscopic viscoelasticity and structure of an aging colloidal gel using active microrheology and cryogenic scanning electron microscopy
Creators: name: Biswas, Rajkumar
name: Parmar, Vaibhav Raj Singh
name: Thambi, Anson G
name: Bandyopadhyay, Ranjini
Publisher: name: arXiv
Year: 2022
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: FOS: Physical sciences

description: Optical tweezers (OTs) can detect pico-Newton range forces operating on a colloidal particle trapped in a medium and have been successfully utilized to investigate complex systems with internal structures. Laponite clay particles in an aqueous medium self-assemble to form microscopic networks over time as electrostatic interactions between the particles gradually evolve in a physical aging process. We investigate the forced movements of an optically trapped micron-sized colloidal probe particle, suspended in an aging Laponite suspension, as the underlying Laponite microstructures gradually develop. Our OT-based oscillatory active microrheology experiments allow us to investigate the mechanical responses of the evolving microstructures in aging aqueous clay suspensions of concentrations ranging from 2.5% w/v to 3.0% w/v and at several aging times between 90 and 150 minutes. We repeat such oscillatory measurements for a range of colloidal probe particle diameters and investigate the effect of probe size on the microrheology of the aging suspensions. Using cryogenic field emission scanning electron microscopy (cryo-FESEM), we examine the average pore areas of the Laponite suspension microstructures for various sample concentrations and aging times. By combining our OT and cryo-FESEM data, we report here for the first time to the best of our knowledge, an inverse correlation between the crossover modulus and the average pore diameter of the aging suspension microstructures for the different suspension concentrations and probe particle sizes studied here.
description: 11 pages, 6 figures and supplementary information included
Experimental measurement of binding energy, selectivity and allostery using fluctuation theorems
Creators: name: Camunas-Soler, Joan
name: Alemany, Anna
name: Ritort, Felix
Publisher: name: arXiv
Year: 2017
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Chemical Physics (physics.chem-ph)
subject: Biomolecules (q-bio.BM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Thermodynamic bulk measurements of binding reactions critically rely on the validity of the law of mass action and the assumption of a dilute solution. Yet important biological systems such as allosteric ligand-receptor binding, macromolecular crowding, or misfolded molecules may not follow this fundamental law and require a particular reaction model. Here we introduce a fluctuation theorem for ligand binding and an experimental approach using single-molecule force-spectroscopy to determine binding energies, selectivity and allostery of nucleic acids, proteins and peptides in a model-independent fashion. This work extends the use of fluctuation theorems beyond unimolecular folding reactions, bridging the thermodynamics of small systems and the basic laws of chemical equilibrium.
$X(3872)$, $X(4014)$, and their bottom partners at finite temperature
Creators: name: Montaña, Gloria
name: Ramos, Angels
name: Tolos, Laura
name: Torres-Rincon, Juan M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: The properties of the $X(3872)$ and its spin partner, the $X(4014)$, are studied both in vacuum and at finite temperature. Using an effective hadron theory based on the hidden-gauge Lagrangian, the $X(3872)$ is dynamically generated from the $s$-wave rescattering of a pair of pseudoscalar and vector charm mesons. By incorporating the thermal spectral functions of open charm mesons, the calculation is extended to finite temperature. Similarly, the properties of the $X(4014)$ are obtained out of the scattering of charm vector mesons. By applying heavy-quark flavor symmetry, the properties of their bottom counterparts in the axial-vector and tensor channels are also predicted. All the dynamically generated states show a decreasing mass and acquire an increasing decay width with temperature, following the trend observed in their meson constituents. These results are relevant in relativistic heavy-ion collisions at high energies, in analyses of the collective medium formed after hadronization or in femtoscopic studies, and can be tested in lattice-QCD calculations exploring the melting of heavy mesons at finite temperature.
description: 32 pages, 7 figures, 3 tables
Cohomogeneity-1 solutions in Einstein-Maxwell-dilaton gravity
Creators: name: Lim, Yen-Kheng
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: The field equations for Einstein-Maxwell-dilaton gravity in $D$ dimensions are reduced to an effective one-dimensional system under the influence of exponential potentials. Various cases where exact solutions can be found are explored. With this procedure, we present interesting solutions such as a one-parameter generalisation of the dilaton-Melvin spacetime and a three-parameter solution that interpolates between the Reissner-Nordström and Bertotti-Robinson solution. This procedure also allows simple, alternative derivations of known solutions such as the Lifshitz spacetime and the planar Anti-de Sitter naked singularity. In the latter case, the metric is cast in a simpler form which reveals the presence of an additional curvature singularity.
description: Typos corrected, 20 pages, no figures
Fragmentation and correlations in a rotating Bose-Einstein condensate undergoing breakup
Creators: name: Dutta, Sunayana
name: Lode, Axel U. J.
name: Alon, Ofir E.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The theoretical investigation of rotating Bose-Einstein condensates has mainly focused on the emergence of quantum vortex states and the condensed properties of such systems. In the present work, we concentrate on other facets by examining the impact of rotation on the ground state of weakly interacting bosons confined in anharmonic potentials computed both at the mean-field level and particularly at the many-body level of theory. For the many-body computations, we employ the well-established many-body method known as the multiconfigurational time-dependent Hartree method for bosons (MCTDHB). We present how various degrees of fragmentation can be generated following the breakup of the ground state densities in anharmonic traps without ramping up a potential barrier for strong rotations. The breakup of the densities is found to be associated with the acquisition of angular momentum in the condensate due to the rotation. In addition to fragmentation, the presence of many-body correlations is examined by computing the variances of the many-particle position and momentum operators. For strong rotations, the many-body variances become smaller than their mean-field counterparts, and one even finds a scenario with opposite anisotropies of the mean-field and many-body variances. Further, it is observed that for higher discrete symmetric systems of order k, namely three-fold and four-fold symmetry, breakup to k sub-clouds and emergence of k-fold fragmentation take place. All in all, we provide a thorough many-body investigation of how and which correlations build up when a trapped Bose-Einstein condensate breaks up under rotation.
Examining Ibn 'Umar's stance during Fitan times and its impact : Re-reading his approaches to peace and conflict
Creators: name: Farman, Mursal
Publisher: name: Australian Catholic University
Year: 2022
Subjects: fitan
Ibn 'Umar
Early Islam civil wars
peace
Islamic history
seerah

description: Conflict over the Caliphate after the assassination of the third Caliph, ʿUthmān b. ʿAffān (d. 35/656), has remained a matter of serious concern amongst the Muslim academia and intellectual circles. This conflict resulted in schism among Muslims and caused two series of civil wars. These wars seem to have been a conflict of approaches (theological, socio-political and tribal) towards the Caliphate. ʿAbd Allāh b. ʿUmar (610 – 73/693), a famous companion of the Prophet, opted for an approach distinct from the prevailing various approaches. Besides his meritorious active role in restoration of peace and harmony, Ibn ʿUmar is a prominent scholar too. His command over the traditional Islamic disciplines (tafsīr, ḥadīth, fiqh, sīrah, tārīkh, etc) is exemplary. His life, traditions, viewpoints, and activities are prominently highlighted in the Islamic literatures. Despite the mention of Ibn ʿUmar in many sources reporting his peace promoting efforts, however, there is no comprehensive analytical research focusing on his role for the restoration of peace and harmony, its impact upon contemporary people and legacy in post-Ibn ʿUmar period. There seems to be a gap which this study aims to fill through a critical analysis of his views, activities and dealing with fitan through different measures. This dissertation deals with three aspects of Ibn ʿUmar’s life. First, the positive role that he played during the period of fitan. On the ground of the extensive Islamic literature in Arabic, English and Urdu languages, an attempt has been made to examine the nuances of his approaches to fitan through a chronological study of his life. Second, the impact of Ibn ʿUmar’s role during post-Ibn ʿUmar period. Based on the analysis of the comments on his approaches in fitan and on the comparison of his views with that of Ahl al-Sunnah, an effort has been exerted to measure his influence on later Muslim generations. Third is the leadership model that Ibn ʿUmar offers. On the account of the analysis of his leadership moments specially in fitan times and its comparison with leadership styles, it is aimed to examine his leadership style. Thus, this study argues that with his thoughts and leadership in the times of fitan, Ibn ʿUmar left deep impression on future generations.
Phase Transitions and Criticality in the Collective Behavior of Animals -- Self-organization and biological function
Creators: name: Romanczuk, Pawel
name: Daniels, Bryan C.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Biological Physics (physics.bio-ph)
subject: Soft Condensed Matter (cond-mat.soft)
subject: Populations and Evolution (q-bio.PE)
subject: Quantitative Methods (q-bio.QM)
subject: FOS: Physical sciences
subject: FOS: Biological sciences

description: Collective behaviors exhibited by animal groups, such as fish schools, bird flocks, or insect swarms are fascinating examples of self-organization in biology. Concepts and methods from statistical physics have been used to argue theoretically about the potential consequences of collective effects in such living systems. In particular, it has been proposed that such collective systems should operate close to a phase transition, specifically a (pseudo-)critical point, in order to optimize their capability for collective computation. In this chapter, we will first review relevant phase transitions exhibited by animal collectives, pointing out the difficulties of applying concepts from statistical physics to biological systems. Then we will discuss the current state of research on the "criticality hypothesis", including methods for how to measure distance from criticality and specific functional consequences for animal groups operating near a phase transition. We will highlight the emerging view that de-emphasizes the optimality of being exactly at a critical point and instead explores the potential benefits of living systems being able to tune to an optimal distance from criticality. We will close by laying out future challenges for studying collective behavior at the interface of physics and biology.
description: to appear in "Order, disorder, and criticality", vol. VII, World Scientific Publishing
D6.6 Electronic newsletter –  First Release
Creators: name: Youthmakers Hub - YMH
Publisher: name: AfriConEU
Year: 2021
Subjects: Africa
Europe
AfriConEU
Trasncontinentalpartnership
DIH

description: Youthmakers Hub, with the contribution of all partners, has produced the first newsletter; more will follow, one every semester. The newsletter was circulated in an electronic format to the interested public through the Mailchimp platform, and it was also uploaded to the official project webpage (https://africoneu.eu/newsletter/). The first newsletter of the project was released and sent on 16th July 2021. A database with e-mails has been developed during the last months with all people subscribed to our newsletter. 165 people received the newsletter.

Four main categories have been included in the newsletter: About the project, Opportunities & News, Participation in Events, and Completed AfriConEU activities. The issue published illustrated the achievements reached during the reported period, both in terms of projects developments as well as peripheral activities, such as participation in external events. Given the importance of the newsletter, it has to be concise, avoid jargon, clarify, and make the final text attractive enough to make all kinds of readers want to find out more about the project.
Hall Effect in Doped Mott-Hubbard Insulator
Creators: name: Kuchinskii, E. Z.
name: Kuleeva, N. A.
name: Sadovskii, M. V.
name: Khomskii, D. I.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Superconductivity (cond-mat.supr-con)
subject: FOS: Physical sciences

description: We present theoretical analysis of Hall effect in doped Mott-Hubbard insulator, considered as a prototype of cuprate superconductor. We consider the standard Hubbard model within DMFT approximation. As a typical case we consider the partially filled (hole doping) lower Hubbard band. We calculate the doping dependence of both the Hall coefficient and Hall number and determine the value of carrier concentration, where Hall effect changes its sign. We obtain a significant dependence of Hall effect parameters on temperature. Disorder effects are taken into account in a qualitative way.We also perform a comparison of our theoretical results with some known experiments on doping dependence of Hall number in the normal state of YBCO and Nd-LSCO, demonstrating rather satisfactory agreement of theory and experiment. Thus the doping dependence of Hall effect parameters obtained within Hubbard model can be considered as an alternative to a popular model of the quantum critical point.
description: 10 pages, 10 figures, extended paper, short communication appeared as arXiv:2203.00542
Cooling in a Dissipative Dark Sector
Creators: name: Rosenberg, Eliott
name: Fan, JiJi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: The possibility of a subdominant component of dark matter dissipating energy could lead to dramatic new phenomenology such as the formation of a dark disk. One rigorous way to assess this possibility and settle the debate on its feasibility is to include the dissipative dark component in a numerical hydrodynamical simulation. A necessary input to such a simulation is a prescription including energy dissipation rates of different processes and rates of processes that change the number densities of dark ions and atoms. In this article, we study the simplest dissipative dark sector which consists of a dark electron and proton, both charged under a dark gauged U(1). We present approximate analytic formulas for energy loss rates due to Compton scattering, bremsstrahlung, recombination, collisional ionization and collisional excitation as well as the rates of number density change. We also include the heating rate due to photoionization. The work serves as the first step to realize a numerical simulation including a dissipative dark sector, which hopefully can shed more light on the formation and properties of a dark disk originating from dark matter self-interactions.
description: 25 pages, 5 figures
Chaos and multifold complexity for an inverted harmonic oscillator
Creators: name: Qu, Le-Chen
name: Jiang, Hong-Yue
name: Liu, Yu-Xiao
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We examine the multifold complexity and Loschmidt echo for an inverted harmonic oscillator. We give analytic expressions for any number of precursors, implementing multiple backward and forward time evolutions of the quantum state, at the leading order in the perturbation. We prove that complexity is dominated by the longest permutation of the given time combination in an alternating ``zig-zag'' order, the exact same result obtained with holography. We conjecture that the general structure for multifold complexity should hold true universally for generic quantum systems, in the limit of a large number of precursors.
description: 24 pages, 9 figures
High efficiency 'plug & play' source of heralded single photons
Creators: name: Montaut, Nicola
name: Sansoni, Linda
name: Meyer-Scott, Evan
name: Ricken, Raimund
name: Quiring, Viktor
name: Herrmann, Harald
name: Silberhorn, Christine
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Reliable generation of single photons is of key importance for fundamental physical experiments and to demonstrate quantum technologies. Waveguide-based photon pair sources have shown great promise in this regard due to their large degree of spectral tunability, high generation rates and long photon coherence times. However, for such a source to have real world applications it needs to be efficiently integrated with fiber-optic networks. We answer this challenge by presenting an alignment-free source of photon pairs in the telecommunications band that maintains heralding efficiency > 50 % even after fiber pigtailing, photon separation, and pump suppression. The source combines this outstanding performance in heralding efficiency and brightness with a compact, stable, and easy-to-use 'plug & play' package: one simply connects a laser to the input and detectors to the output and the source is ready to use. This high performance can be achieved even outside the lab without the need for alignment which makes the source extremely useful for any experiment or demonstration needing heralded single photons.
description: 7 pages, 5 figures
A Light shed on Lepton Flavor Universality in B decays
Creators: name: Patnaik, Sonali
name: Singh, Rajeev
Publisher: name: arXiv
Year: 2022
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: At the back of succeeding measurements of anomalies in semileptonic decays at LHCb and several collider experiments hinting at the possible violation of lepton flavor universality, we undertake a concise review of theoretical foundations of the tree- and loop-level $b$-hadron decays, $b \to c l ν_l$ and $b \to s l^+ l^-$ along with experimental environments. We revisit the world averages for $R_{D(D^*)}$, $R_{K(K^*)}$, $R_{J/ψ}$, and $R_{η_c}$, for the semileptonic transitions and provide results within the framework of the relativistic independent quark model in addition to the results from model-independent studies. If the ongoing evaluation of the data of LHC Run 2 confirms the measurements of Run 1, then the statistical significance of the effect in each decay channel is likely to reach 5~$σ$. A confirmation of these measurements would soon turn out to be the first remarkable observation of physics beyond the Standard Model providing a wider outlook on the understanding of New Physics.
description: Updated, revised, and journal version. This article belongs to the Special Issue Search for New Physics at the LHC and Future Colliders
Supplementary figures from A wrap-around movement path randomization method to distinguish social and spatial drivers of animal interactions
Creators: name: Gahm, Kaija
name: Nguyen, Ryan
name: Acácio, Marta
name: Anglister, Nili
name: Vaadia, Gideon
name: Spiegel, Orr
name: Pinter-Wollman, Noa
Publisher: name: The Royal Society
Year: 2024
Subjects: classificationCode: 310901
subject: Animal behaviour

description: This file contains five additional figures and three tables referenced in the main text, and their captions.
Continuum limit of the vibrational properties of amorphous solids
Creators: name: Mizuno, Hideyuki
name: Shiba, Hayato
name: Ikeda, Atsushi
Publisher: name: arXiv
Year: 2017
Subjects: subject: Soft Condensed Matter (cond-mat.soft)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: The low-frequency vibrational and low-temperature thermal properties of amorphous solids are markedly different from those of crystalline solids. This situation is counter-intuitive because any solid material is expected to behave as a homogeneous elastic body in the continuum limit, in which vibrational modes are phonons following the Debye law. A number of phenomenological explanations have been proposed, which assume elastic heterogeneities, soft localized vibrations, and so on. Recently, the microscopic mean-field theories have been developed to predict the universal non-Debye scaling law. Considering these theoretical arguments, it is absolutely necessary to directly observe the nature of the low-frequency vibrations of amorphous solids and determine the laws that such vibrations obey. Here, we perform an extremely large-scale vibrational mode analysis of a model amorphous solid. We find that the scaling law predicted by the mean-field theory is violated at low frequency, and in the continuum limit, the vibrational modes converge to a mixture of phonon modes following the Debye law and soft localized modes following another universal non-Debye scaling law.
description: 19 pages, 5 figures
D6.7 Electronic newsletter – Second Release
Creators: name: Youthmakers Hub - YMH
Publisher: name: AfriConEU
Year: 2022
Subjects: Africa
Europe
DIH
Transcontinentalpartnership
AfriConEU

description: Youthmakers Hub, with the contribution of all partners, has produced the second newsletter; more will follow, one every semester. The newsletter was circulated in an electronic format to the interested public through the Mailchimp platform, and it was also uploaded to the official project webpage (https://africoneu.eu/newsletter/). The second newsletter of the project was released and sent on 21st January 2022. A database with e-mails has been developed during the last months with all people subscribed to our newsletter. 259 people received the newsletter. Four main categories have been included in the newsletter: About the project, Opportunities & News, Completed AfriConEU activities, Coming-up Online Workshop. 

The issue published illustrated the achievements reached during the reported period, both interms of projects developments as well as peripheral activities, such as participation in external events. Given the importance of the newsletter, concise, clear and simple sentences are important to spark and sustain interest in readers on the project.
Magnetic excitations from the two-dimensional interpenetrating Cu framework in Ba$_2$Cu$_3$O$_4$Cl$_2$
Creators: name: Babkevich, P.
name: Shaik, N. E.
name: Lançon, D.
name: Kikkawa, A.
name: Enderle, M.
name: Ewings, R. A.
name: Walker, H. C.
name: Adroja, D. T.
name: Manuel, P.
name: Khalyavin, D. D.
name: Taguchi, Y.
name: Tokura, Y.
name: Soda, M.
name: Masuda, T.
name: Rønnow, H. M.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: We report detailed neutron scattering studies on Ba$_2$Cu$_3$O$_4$Cl$_2$. The compound consists of two interpenetrating sublattices of Cu, labeled as Cu$_{\rm A}$ and Cu$_{\rm B}$, each of which forms a square-lattice Heisenberg antiferromagnet. The two sublattices order at different temperatures and effective exchange couplings within the sublattices differ by an order of magnitude. This yields an inelastic neutron spectrum of the Cu$_{\rm A}$ sublattice extending up to 300 meV and a much weaker dispersion of Cu$_{\rm B}$ going up to around 20 meV. Using a single-band Hubbard model we derive an effective spin Hamiltonian. From this, we find that linear spin-wave theory gives a good description to the magnetic spectrum. In addition, a magnetic field of 10 T is found to produce effects on the Cu$_{\rm B}$ dispersion that cannot be explained by conventional spin-wave theory.
description: 13 pages, 9 figures
An intermediate-mass black hole in the centre of the globular cluster 47 Tucanae
Creators: name: Kızıltan, Bülent
name: Baumgardt, Holger
name: Loeb, Abraham
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: Applications (stat.AP)
subject: FOS: Physical sciences
subject: FOS: Computer and information sciences

description: Intermediate mass black holes play a critical role in understanding the evolutionary connection between stellar mass and super-massive black holes. However, to date the existence of these species of black holes remains ambiguous and their formation process is therefore unknown. It has been long suspected that black holes with masses $10^{2}-10^{4}M_{\odot}$ should form and reside in dense stellar systems. Therefore, dedicated observational campaigns have targeted globular cluster for many decades searching for signatures of these elusive objects. All candidates found in these targeted searches appear radio dim and do not have the X-ray to radio flux ratio predicted by the fundamental plane for accreting black holes. Based on the lack of an electromagnetic counterpart upper limits of $2060 M_{\odot}$ and $470 M_{\odot}$ have been placed on the mass of a putative black hole in 47 Tucanae (NGC 104) from radio and X-ray observations respectively. Here we show there is evidence for a central black hole in 47 Tuc with a mass of M$_{\bullet}\sim2300 M_{\odot}$$_{-850}^{+1500}$ when the dynamical state of the globular cluster is probed with pulsars. The existence of an intermediate mass black hole in the centre of one of the densest clusters with no detectable electromagnetic counterpart suggests that the black hole is not accreting at a sufficient rate and therefore contrary to expectations is gas starved. This intermediate mass black hole might be a member of electromagnetically invisible population of black holes that are the elusive seeds leading to the formation of supermassive black holes in galaxies.
description: Published in Nature, Corrigendum added
D6.8 Electronic newsletter – Third Release
Creators: name: Youthmakers Hub - YMH
Publisher: name: AfriConEU
Year: 2022
Subjects: Africa
Europe
DIH
Transcontinentalpartnership
AfriConEU

description: Youthmakers Hub, with the contribution of all partners, has produced the third newsletter; more will follow, one every semester. The newsletter was circulated in an electronic format to the interested public through the Mailchimp platform, and it was also uploaded to the official project webpage (https://africoneu.eu/newsletter/). The third newsletter of the project was released and sent on the 22nd of July 2022. A database with e-mails has been developed during the last months with all people subscribed to our newsletter. 500 people received the newsletter. Three main categories have been included in the newsletter:Opportunities & News, Completed AfriConEU activities & Coming-up. 

Besides disseminating our third newsletter through the Mailchimp platform and the AfriConEU Website, it was also published through the AfriConEU LinkedIn Page, expanding our digital audience and community and boosting our brand awareness, building credibility and generating leads to our social media pages.

The published issue illustrated the achievements reached during the reported period regarding the project’s developments and peripheral activities, such as participation in external events. Part of the newsletter was the AfriConEU Networking Academy, the launch of the Brokerage Event, and the brand new AfriConEU Vidcast Series, Digital Innovation Talks. Given the importance of the newsletter, concise, clear and straightforward sentences are essential to spark and sustain interest in readers on the project.
Current-driven skyrmion dynamics in disordered films
Creators: name: Kim, Joo-Von
name: Yoo, Myoung-Woo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: A theoretical study of the current-driven dynamics of magnetic skyrmions in disordered perpendicularly-magnetized ultrathin films is presented. The disorder is simulated as a granular structure in which the local anisotropy varies randomly from grain to grain. The skyrmion velocity is computed for different disorder parameters and ensembles. Similar behavior is seen for spin-torques due to in-plane currents and the spin Hall effect, where a pinning regime can be identified at low currents with a transition towards the disorder-free case at higher currents, similar to domain wall motion in disordered films. Moreover, a current-dependent skyrmion Hall effect and fluctuations in the core radius are found, which result from the interaction with the pinning potential.
description: 5 pages, 5 figures
Target Mass Effects in Parton Quasi-Distributions
Creators: name: Radyushkin, Anatoly
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Lattice (hep-lat)
subject: FOS: Physical sciences

description: We study the impact of non-zero (and apparently large) value of the nucleon mass $M$ on the shape of parton quasi-distributions $Q(y,p_3)$, in particular on its change with the change of the nucleon momentum $p_3$. We observe that the usual target-mass corrections induced by the $M$-dependence of the twist-2 operators are rather small. Moreover, we show that within the framework based on parametrizations by transverse momentum dependent distribution functions (TMDs) these corrections are canceled by higher-twist contributions. We identify a novel source of kinematic target-mass dependence of TMDs and build models corrected for such dependence. We find that resulting changes may be safely neglected for $p_3 \gtrsim 2M$.
description: 9 pages, 5 figures, to appear in Physics Letters B
The topological natures of the Gauss-Bonnet black hole in AdS space
Creators: name: Liu, Conghua
name: Wang, Jin
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: In the recent proposal [Phys. Rev. Lett. 129, 191101 (2022)], the black holes were viewed as topological thermodynamic defects by using the generalized off-shell free energy. In this paper, we follow such proposal to study the local and global topological natures of the Gauss-Bonnet black holes in AdS space. The local topological natures are reflected by the winding numbers, where the positive and negative winding numbers correspond to the stable and unstable black hole branches. The global topological natures are reflected by the topological numbers, which are defined as the sum of the winding numbers for all black hole branches and can be used to classify the black holes into different classes. When the charge is present, we find that the topological number is independent on the values of the parameters, and the charged Gauss-Bonnet AdS black holes can be divided into the same class of the RNAdS black holes with the same topological number 1. However, when the charge is absent, we find that the topological number has certain dimensional dependence. This is different from the previous studies, where the topological number is found to be a universal number independent of the black hole parameters. Furthermore, the asymptotic behaviors of curve τ(r_h) in small and large radii limit can be a simple criterion to distinguish the different topological number. We find a new asymptotic behavior as τ(r_h \to 0) = 0 and τ(r_h \to \infty) = 0 in the black hole system, which shows topological equivalency with the asymptotic behaviors τ(r_h \to 0)=\infty and τ(r_h \to \infty)=\infty. We also give an intuitional proof of why there are only three topological classes in the black hole system under the condition (\partial_{r_h} S)P > 0.
Periodic Eclipses of the Young Star PDS 110 Discovered with WASP and KELT Photometry
Creators: name: Osborn, H. P.
name: Rodriguez, J. E.
name: Kenworthy, M. A.
name: Kennedy, G. M.
name: Mamajek, E. E.
name: Robinson, C. E.
name: Espaillat, C. C.
name: Armstrong, D. J.
name: Shappee, B. J.
name: Bieryla, A.
name: Latham, D. W.
name: Anderson, D. R.
name: Beatty, T. G.
name: Berlind, P.
name: Calkins, M. L.
name: Esquerdo, G. A.
name: Gaudi, B. S.
name: Hellier, C.
name: Holoien, T. W. -S.
name: James, D.
name: Kochanek, C. S.
name: Kuhn, R. B.
name: Lund, M. B.
name: Pepper, J.
name: Pollacco, D. L.
name: Prieto, J. L.
name: Siverd, R. J.
name: Stassun, K. G.
name: Stevens, D. J.
name: Stanek, K. Z.
name: West, R. G.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: We report the discovery of eclipses by circumstellar disc material associated with the young star PDS 110 in the Ori OB1a association using the SuperWASP and KELT surveys. PDS 110 (HD 290380, IRAS 05209-0107) is a rare Fe/Ge-type star, a ~10 Myr-old accreting intermediate-mass star showing strong infrared excess (L$_{\rm IR}$/L$_{\rm bol}$ ~ 0.25). Two extremely similar eclipses with a depth of ~30\% and duration ~25 days were observed in November 2008 and January 2011. We interpret the eclipses as caused by the same structure with an orbital period of $808\pm2$ days. Shearing over a single orbit rules out diffuse dust clumps as the cause, favouring the hypothesis of a companion at ~2AU. The characteristics of the eclipses are consistent with transits by an unseen low-mass (1.8-70M$_{Jup}$) planet or brown dwarf with a circum-secondary disc of diameter ~0.3 AU. The next eclipse event is predicted to take place in September 2017 and could be monitored by amateur and professional observatories across the world.
description: 10 pages, 6 figures, submitted to MNRAS 9th Feb 2017. Accepted 18th May 2017
Transport in p-wave interacting Fermi gases
Creators: name: Maki, Jeff
name: Enss, Tilman
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: The scattering properties of spin-polarized Fermi gases are dominated by p-wave interactions. Besides their inherent angular dependence, these interactions differ from their s-wave counterparts as they also require the presence of a finite effective range in order to understand the low-energy properties of the system. In this article we examine how the shear viscosity and thermal conductivity of a three-dimensional spin-polarized Fermi gas in the normal phase depend on the effective range and the scattering volume in both the weakly and strongly interacting limits. We show that although the shear viscosity and thermal conductivity both explicitly depend on the effective range near resonance, the Prandtl number which parametrizes the ratio of momentum to thermal diffusivity does not have an explicit interaction dependence both at resonance and for weak interactions in the low-energy limit. In contrast to s-wave systems, p-wave scattering exhibits an additional resonance at weak attraction from a quasi-bound state at positive energies, which leads to a pronounced dip in the shear viscosity at specific temperatures.
description: 12 pages, 7 figures; published version
ContextCLIP: Contextual Alignment of Image-Text pairs on CLIP visual representations
Creators: name: Grover, Chanda
name: Mastan, Indra Deep
name: Gupta, Debayan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: State-of-the-art empirical work has shown that visual representations learned by deep neural networks are robust in nature and capable of performing classification tasks on diverse datasets. For example, CLIP demonstrated zero-shot transfer performance on multiple datasets for classification tasks in a joint embedding space of image and text pairs. However, it showed negative transfer performance on standard datasets, e.g., BirdsNAP, RESISC45, and MNIST. In this paper, we propose ContextCLIP, a contextual and contrastive learning framework for the contextual alignment of image-text pairs by learning robust visual representations on Conceptual Captions dataset. Our framework was observed to improve the image-text alignment by aligning text and image representations contextually in the joint embedding space. ContextCLIP showed good qualitative performance for text-to-image retrieval tasks and enhanced classification accuracy. We evaluated our model quantitatively with zero-shot transfer and fine-tuning experiments on CIFAR-10, CIFAR-100, Birdsnap, RESISC45, and MNIST datasets for classification task.
description: 11 Pages, 7 Figures, 2 Tables, ICVGIP
Giving RSEs a Larger Stage through the Better Scientific Software Fellowship
Creators: name: Godoy, William F.
name: Arora, Ritu
name: Beattie, Keith
name: Bernholdt, David E.
name: Bratt, Sarah E.
name: Katz, Daniel S.
name: Laguna, Ignacio
name: Maji, Amiya K.
name: Thakur, Addi Malviya
name: Mudafort, Rafael M.
name: Sukhija, Nitin
name: Rouson, Damian
name: Rubio-González, Cindy
name: Vahi, Karan
Publisher: name: arXiv
Year: 2022
Subjects: subject: Software Engineering (cs.SE)
subject: FOS: Computer and information sciences

description: The Better Scientific Software Fellowship (BSSwF) was launched in 2018 to foster and promote practices, processes, and tools to improve developer productivity and software sustainability of scientific codes. BSSwF's vision is to grow the community with practitioners, leaders, mentors, and consultants to increase the visibility of scientific software production and sustainability. Over the last five years, many fellowship recipients and honorable mentions have identified as research software engineers (RSEs). This paper provides case studies from several of the program's participants to illustrate some of the diverse ways BSSwF has benefited both the RSE and scientific communities. In an environment where the contributions of RSEs are too often undervalued, we believe that programs such as BSSwF can be a valuable means to recognize and encourage community members to step outside of their regular commitments and expand on their work, collaborations and ideas for a larger audience.
description: submitted to Computing in Science & Engineering (CiSE), Special Issue on the Future of Research Software Engineers in the US
Boundary Hilbert spaces and trace operators
Creators: name: Barbero, J. Fernando G.
name: Juárez-Aubry, Benito A.
name: Margalef-Bentabol, Juan
name: Villaseñor, Eduardo J. S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We discuss the introduction of boundary Hilbert spaces for a class of physical systems for which it is not possible to factor their state spaces as tensor products of Hilbert spaces naturally associated to their boundaries and bulks respectively. In order to do this we make use of the so called trace operators that play a relevant role in the analysis of PDE's in bounded regions. By taking advantage of these operators and some functorial aspects of the construction of Fock spaces, we will show how to obtain quantum dynamics at the boundaries defined in appropriate Hilbert spaces associated with them.
description: 13 pages. Accepted for publication in Classical and Quantum Gravity
Exploring the nanoscale origin of performance enhancement in Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$ batteries due to chemical doping
Creators: name: Thersleff, Thomas
name: Biendicho, Jordi Jacas
name: Prakasha, Kunkanadu
name: Moreno, Elias Martinez
name: Jøsang, Leif Olav
name: Grins, Jekabs
name: Jaworski, Aleksander
name: Svensson, Gunnar
Publisher: name: arXiv
Year: 2022
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: FOS: Physical sciences

description: Despite significant potential as energy storage materials for electric vehicles due to their combination of high energy density per unit cost and reduced environmental and ethical concerns, Co-free lithium ion batteries based off layered Mn oxides presently lack the longevity and stability of their Co-containing counterparts. Here, we demonstrate a reduction in this performance gap via chemical doping, with Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$ achieving an initial discharge capacity of 159 mAhg$^{-1}$ at C/3 rate and a corresponding capacity retention of 94.3% after 150 cycles. We subsequently explore the nanoscale origins of this improvement through a combination of advanced diffraction, spectroscopy, and electron microscopy techniques, finding that optimized doping profiles lead to an improved structural and chemical compatibility between the two constituent sub-phases that characterize the layered Mn oxide system, resulting in the formation of unobstructed lithium ion pathways between them. We also directly observe a structural stabilization effect of the host compound near the surface using aberration corrected scanning transmission electron microscopy and integrated differential phase contrast imaging.
description: 20 pages, 8 figures