cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
Homomorphic Encryption Experiments on IBM's Cloud Quantum Computing Platform
Creators: name: Huang, He-Liang
name: Zhao, You-Wei
name: Li, Tan
name: Li, Feng-Guang
name: Du, Yu-Tao
name: Fu, Xiang-Qun
name: Zhang, Shuo
name: Wang, Xiang
name: Bao, Wan-Su
Publisher: name: arXiv
Year: 2016
Subjects: subject: Cryptography and Security (cs.CR)
subject: Data Analysis, Statistics and Probability (physics.data-an)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Quantum computing has undergone rapid development in recent years. Owing to limitations on scalability, personal quantum computers still seem slightly unrealistic in the near future. The first practical quantum computer for ordinary users is likely to be on the cloud. However, the adoption of cloud computing is possible only if security is ensured. Homomorphic encryption is a cryptographic protocol that allows computation to be performed on encrypted data without decrypting them, so it is well suited to cloud computing. Here, we first applied homomorphic encryption on IBM's cloud quantum computer platform. In our experiments, we successfully implemented a quantum algorithm for linear equations while protecting our privacy. This demonstration opens a feasible path to the next stage of development of cloud quantum information technology.
description: 5 pages, 5 figures
Inverse cascades and resonant triads in rotating and stratified turbulence
Creators: name: Oks, D.
name: Mininni, P. D.
name: Marino, R.
name: Pouquet, A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Atmospheric and Oceanic Physics (physics.ao-ph)
subject: FOS: Physical sciences

description: Kraichnan seminal ideas on inverse cascades yielded new tools to study common phenomena in geophysical turbulent flows. In the atmosphere and the oceans, rotation and stratification result in a flow that can be approximated as two-dimensional at very large scales, but which requires considering three-dimensional effects to fully describe turbulent transport processes and non-linear phenomena. Motions can thus be classified into two classes: fast modes consisting of inertia-gravity waves, and slow quasi-geostrophic modes for which the Coriolis force and horizontal pressure gradients are close to balance. In this paper we review previous results on the strength of the inverse cascade in rotating and stratified flows, and then present new results on the effect of varying the strength of rotation and stratification (measured by the ratio $N/f$ of the Brunt-Väisäla frequency to the Coriolis frequency) on the amplitude of the waves and on the flow quasi-geostrophic behavior. We show that the inverse cascade is more efficient in the range of $N/f$ for which resonant triads do not exist, $1/2 \le N/f \le 2$. We then use the spatio-temporal spectrum, and characterization of the flow temporal and spatial scales, to show that in this range slow modes dominate the dynamics, while the strength of the waves (and their relevance in the flow dynamics) is weaker.
description: 17 pages, 13 figures, new version has all changes in the paper published in the Two Dimensional Turbulence Focus Issue of Physics of Fluids
A universal minimal mass scale for present-day central black holes
Creators: name: Alexander, Tal
name: Bar-Or, Ben
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: FOS: Physical sciences

description: Intermediate-mass black holes (IMBHs) of mass $M_{\bullet} \approx 10^{2} - 10^{5}$ solar masses, $M_{\odot}$, are the long-sought missing link between stellar black holes, born of supernovae, and massive black holes, tied to galaxy evolution by the empirical $M_{\bullet}/σ_{\star}$ correlation. We show that low-mass black hole seeds that accrete stars from locally dense environments in galaxies following a universal $M_{\bullet}/σ_{\star}$ relation grow over the age of the Universe to be above ${\mathcal{M}}_{0}\approx3\times10^{5}M_{\odot}$ ($5\%$ lower limit), independent of the unknown seed masses and formation processes. The mass ${\mathcal{M}}_{0}$ depends weakly on the uncertain formation redshift, and sets a universal minimal mass scale for present-day black holes. This can explain why no IMBHs have yet been found, and it implies that present-day galaxies with ${σ_{\star}
description: Published in Nature Astronomy (http://www.nature.com/articles/s41550-017-0147). This is the Authors' final version, which is identical in content to the published version but slightly different in the presentation
Applications of some special numbers obtained from a difference equation of degree three
Creators: name: Flaut, Cristina
name: Savin, Diana
Publisher: name: arXiv
Year: 2017
Subjects: subject: Rings and Algebras (math.RA)
subject: Information Theory (cs.IT)
subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences

description: In this paper we present applications of some special numbers obtained from a difference equation of degree three, especially in the Coding Theory. As a particular case, we obtain the generalized Pell-Fibonacci-Lucas numbers, which were extended to the generalized quaternions.
Coupling coefficients of $su_q(1,1)$ and multivariate $q$-Racah polynomials
Creators: name: Genest, Vincent X.
name: Iliev, Plamen
name: Vinet, Luc
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: Mathematical Physics (math-ph)
subject: Quantum Algebra (math.QA)
subject: FOS: Mathematics
subject: FOS: Physical sciences

description: Gasper & Rahman's multivariate $q$-Racah polynomials are shown to arise as connection coefficients between families of multivariate $q$-Hahn or $q$-Jacobi polynomials. The families of $q$-Hahn polynomials are constructed as nested Clebsch--Gordan coefficients for the positive-discrete series representations of the quantum algebra $su_q(1,1)$. This gives an interpretation of the multivariate $q$-Racah polynomials in terms of $3nj$ symbols. It is shown that the families of $q$-Hahn polynomials also arise in wavefunctions of $q$-deformed quantum Calogero--Gaudin superintegrable systems.
description: comments and references added
A holographic stress-energy tensor near the Cauchy horizon inside a rotating black hole
Creators: name: Ishibashi, Akihiro
name: Maeda, Kengo
name: Mefford, Eric
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Theory (hep-th)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: We investigate a stress-energy tensor for a CFT at strong coupling inside a small five-dimensional rotating Myers-Perry black hole with equal angular momenta by using the holographic method. As a gravitational dual, we perturbatively construct a black droplet solution by applying the "derivative expansion" method, generalizing the work of Haddad (arXiv:1207.2305), and analytically compute the holographic stress-energy tensor for our solution. We find that the stress-energy tensor is finite at both the future and past outer (event) horizons, and that the energy density is negative just outside the event horizons due to the Hawking effect. Furthermore, we apply the holographic method to the question of quantum instability of the Cauchy horizon since, by construction, our black droplet solution also admits a Cauchy horizon inside. We analytically show that the null-null component of the holographic stress-energy tensor negatively diverges at the Cauchy horizon, suggesting that a singularity appears there, in favor of strong cosmic censorship.
description: v1: 12+2 pages, 5 figures; v2: 13+2 pages, some clarifications made, version to appear in PRD
Quantum Griffiths phase inside the ferromagnetic phase of Ni$_{1-x}$V$_x$
Creators: name: Wang, Ruizhe
name: Gebretsadik, Adane
name: Ubaid-Kassis, Sara
name: Schroeder, Almut
name: Vojta, Thomas
name: Baker, Peter J.
name: Pratt, Francis L.
name: Blundell, Stephen J.
name: Lancaster, Tom
name: Franke, Isabel
name: Möller, Johannes S.
name: Page, Katharine
Publisher: name: arXiv
Year: 2016
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: FOS: Physical sciences

description: We study by means of bulk and local probes the d-metal alloy Ni$_{1-x}$V$_x$ close to the quantum critical concentration, $x_c \approx 11.6\%$, where the ferromagnetic transition temperature vanishes. The magnetization-field curve in the ferromagnetic phase takes an anomalous power-law form with a nonuniversal exponent that is strongly $x$-dependent and mirrors the behavior in the paramagnetic phase. Muon spin rotation experiments demonstrate inhomogeneous magnetic order and indicate the presence of dynamic fluctuating magnetic clusters. These results provide strong evidence for a quantum Griffiths phase on the ferromagnetic side of the quantum phase transition.
description: 6 pages + 3 pages supplemental material, final version as published
Validity of Sound-Proof Approaches in Rapidly-Rotating Compressible Convection: Marginal Stability vs. Turbulence
Creators: name: Verhoeven, Jan
name: Glatzmaier, Gary A.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: FOS: Physical sciences

description: The validity of the anelastic approximation has recently been questioned in the regime of rapidly-rotating compressible convection in low Prandtl number fluids (Calkins et al. 2015). Given the broad usage and the high computational efficiency of sound-proof approaches in this astrophysically relevant regime, this paper clarifies the conditions for a safe application. The potential of the alternative pseudo-incompressible approximation is investigated, which in contrast to the anelastic approximation is shown to never break down for predicting the point of marginal stability. Its accuracy, however, decreases close to the parameters corresponding to the failure of the anelastic approach, which is shown to occur when the sound-crossing time of the domain exceeds a rotation time scale, i.e. for rotational Mach numbers greater than one. Concerning the supercritical case, which is naturally characterised by smaller rotational Mach numbers, we find that the anelastic approximation does not show unphysical behaviour. Growth rates computed with the linearised anelastic equations converge toward the corresponding fully compressible values as the Rayleigh number increases. Likewise, our fully nonlinear turbulent simulations, produced with our fully compressible and anelastic models and carried out in a highly supercritical, rotating, compressible, low Prandtl number regime show good agreement. However, this nonlinear test example is for only a moderately low convective Rossby number of 0.14.
description: 23 pages, 8 figures
ViHOPE: Visuotactile In-Hand Object 6D Pose Estimation with Shape Completion
Creators: name: Li, Hongyu
name: Dikhale, Snehal
name: Iba, Soshi
name: Jamali, Nawid
Publisher: name: arXiv
Year: 2023
Subjects: subject: Robotics (cs.RO)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences

description: In this letter, we introduce ViHOPE, a novel framework for estimating the 6D pose of an in-hand object using visuotactile perception. Our key insight is that the accuracy of the 6D object pose estimate can be improved by explicitly completing the shape of the object. To this end, we introduce a novel visuotactile shape completion module that uses a conditional Generative Adversarial Network to complete the shape of an in-hand object based on volumetric representation. This approach improves over prior works that directly regress visuotactile observations to a 6D pose. By explicitly completing the shape of the in-hand object and jointly optimizing the shape completion and pose estimation tasks, we improve the accuracy of the 6D object pose estimate. We train and test our model on a synthetic dataset and compare it with the state-of-the-art. In the visuotactile shape completion task, we outperform the state-of-the-art by 265% using the Intersection of Union metric and achieve 88% lower Chamfer Distance. In the visuotactile pose estimation task, we present results that suggest our framework reduces position and angular errors by 35% and 64%, respectively. Furthermore, we ablate our framework to confirm the gain on the 6D object pose estimate from explicitly completing the shape. Ultimately, we show that our framework produces models that are robust to sim-to-real transfer on a real-world robot platform.
description: Accepted by RA-L
Structure coefficients of the Hecke algebra of $(S_{2n},B_n)$
Creators: name: Tout, Omar
Publisher: name: arXiv
Year: 2012
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05E15

description: The Hecke algebra of the pair $(S_{2n},B_n)$, where $B_n$ is the hyperoctahedral subgroup of $S_{2n}$, was introduced by James in 1961. It is a natural analogue of the center of the symmetric group algebra. In this paper, we give a polynomiality property of its structure coefficients. Our main tool is a combinatorial universal algebra which projects on the Hecke algebra of $(S_{2n},B_n)$ for every $n$. To build it, we introduce new objects called partial bijections.
description: 32 pages, 15 figures
Quantum criticality of spinons
Creators: name: He, Feng
name: Jiang, Yu-Zhu
name: Yu, Yi-Cong
name: Lin, Hai-Qing
name: Guan, Xi-Wen
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The free fermion nature of interacting spins in one dimensional (1D) spin chains still lacks a rigorous study. In this letter we show that the length-$1$ spin strings significantly dominate critical properties of spinons, magnons and free fermions in the 1D antiferromagnetic spin-1/2 chain. Using the Bethe ansatz solution we analytically calculate exact scaling functions of thermal and magnetic properties of the model, providing a rigorous understanding of the quantum criticality of spinons. It turns out that the double peaks in specific heat elegantly mark two crossover temperatures fanning out from the critical point, indicating three quantum phases: the Tomonaga-Luttinger liquid (TLL), quantum critical and fully polarized ferromagnetic phases. For the TLL phase, the Wilson ratio $R_W=4K_s$ remains almost temperature-independent, here $K_s$ is the Luttinger parameter. Furthermore, applying our results we precisely determine the quantum scalings and critical exponents of all magnetic properties in the ideal 1D spin-1/2 antiferromagnet Cu(C${}_4$H${}_4$N${}_2$)(NO${}_3$)${}_2$ recently studied in Phys. Rev. Lett. {\bf 114}, 037202 (2015)]. We further find that the magnetization peak used in experiments is not a good quantity to map out the finite temperature TLL phase boundary.
description: 6 pages + 10 pages, 4 figures + 4 figures
The 4-girth-thickness of the complete graph
Creators: name: Rubio-Montiel, Christian
Publisher: name: arXiv
Year: 2017
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05C10

description: In this paper, we define the $4$-girth-thickness $θ(4,G)$ of a graph $G$ as the minimum number of planar subgraphs of girth at least $4$ whose union is $G$. We obtain the $4$-girth-thickness of the arbitrary complete graph $K_n$ getting that $θ(4,K_n)=\left\lceil \frac{n+2}{4}\right\rceil$ for $n\not=6,10$ and $θ(4,K_6)=3$.
description: 9 pages, 8 figures
Influence of microstructure on superconductivity in K$_x$Fe$_{2-y}$Se$_2$ and evidence for a new parent phase K$_2$Fe$_7$Se$_8$
Creators: name: Ding, Xiaxin
name: Fang, Delong
name: Wang, Zhenyu
name: Yang, Huan
name: Liu, Jianzhong
name: Deng, Qiang
name: Ma, Guobin
name: Meng, Chong
name: Hu, Yuhui
name: Wen, Hai-Hu
Publisher: name: arXiv
Year: 2013
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: The search for new superconducting materials has been spurred on by the discovery of iron-based superconductors whose structure and composition is qualitatively different from the cuprates. The study of one such material, K$_x$Fe$_{2-y}$Se$_2$ with a critical temperature of 32 K, is made more difficult by the fact that it separates into two phases: a dominant antiferromagnetic insulating phase with a K$_2$Fe$_4$Se$_5$ structure, and a minority superconducting phase whose precise structure is as yet unclear. Here we perform electrical and magnetization measurements, scanning electron microscopy and microanalysis, X-ray diffraction, and scanning tunnelling microscopy on K$_x$Fe$_{2-y}$Se$_2$ crystals prepared under different quenching processes to better understand the relationship between its microstructure and its superconducting phase. We identify a 3D network of superconducting filaments within this material and present evidence to suggest that the superconducting phase consists of a single Fe vacancy for every eight Fe-sites arranged in a $\sqrt{10}\times\sqrt{8}$ parallelogram structure.
description: 26 pages, 7 figures including the main text and the Supplementary as corrections for the original Figure 4
A network model for cellular aging
Creators: name: Qin, Hong
Publisher: name: arXiv
Year: 2013
Subjects: subject: Molecular Networks (q-bio.MN)
subject: Populations and Evolution (q-bio.PE)
subject: FOS: Biological sciences

description: What is aging? Mechanistic answers to this question remain elusive despite decades of research. Here, we propose a mathematical model of cellular aging based on a model gene interaction network. Our network model is made of only non-aging components - the biological functions of gene interactions decrease with a constant mortality rate. Death of a cell occurs in the model when an essential gene loses all of its interactions to other genes, equivalent to the deletion of an essential gene. Gene interactions are stochastic based on a binomial distribution. We show that the defining characteristic of biological aging, the exponential increase of mortality rate over time, can arise from this gene network model during the early stage of aging. Hence, we demonstrate that cellular aging is an emergent property of this model network. Our model predicts that the rate of aging, defined by the Gompertz coefficient, is approximately proportional to the average number of active interactions per gene and that the stochastic heterogeneity of gene interactions is an important factor in the dynamics of the aging process. This theoretic framework offers a mechanistic foundation for the pleiotropic nature of aging and can provide insights on cellular aging.
Time crystals: a review
Creators: name: Sacha, Krzysztof
name: Zakrzewski, Jakub
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications of discrete (or Floquet) time crystals -- the structures that appear in the time domain due to spontaneous breaking of discrete time translation symmetry. The struggle to observe discrete time crystals is reviewed here together with propositions that generalize this concept introducing condensed matter like physics in the time domain. We shall also revisit the original Wilczek's idea and review strategies aimed at spontaneous breaking of continuous time translation symmetry.
description: VIDEO ABSTRACT: https://youtu.be/5uaUEWH0x60
Spontaneous flux concentrations from the negative effective magnetic pressure instability beneath a radiative stellar surface
Creators: name: Perri, Barbara
name: Brandenburg, Axel
Publisher: name: arXiv
Year: 2017
Subjects: subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences

description: The formation of sunspots requires the concentration of magnetic flux near the surface. The negative magnetic pressure instability (NEMPI) might be a possible mechanism for accomplishing this, but it has mainly been studied in simple systems using an isothermal equation of state without a natural free surface. We study NEMPI in a stratified Cartesian mean-field model where turbulence effects are parameterized. We use an ideal equation of state and include radiation transport, which establishes selfconsistently a free surface. We use a Kramers-type opacity with adjustable exponents chosen such that the deeper layers are approximately isentropic. No convection is therefore possible in this model, allowing us to study NEMPI with radiation in isolation. We restrict ourselves to two-dimensional models. We use artificially enhanced mean-field coefficients to allow NEMPI to develop, making it therefore possible to study the reason why it is much harder to excite in the presence of radiation. NEMPI yields moderately strong magnetic flux concentrations a certain distance beneath the surface where optical depth is unity. The instability is oscillatory and in the form of upward travelling waves. This seems to be a new effect that has not been found in earlier models without radiative transport. The horizontal wavelength is about ten times smaller than what has been found previously in more idealized isothermal models. In our models, NEMPI saturates at field strengths too low to explain sunspots. Furthermore, the structures appear too narrow and too far beneath the surface to cause significant brightness variations at the radiative surface. We speculate that the failure to reproduce effects resembling sunspots may be related to the neglect of convection.
description: 10 pages, 10 figures
Model-independent constraints on hadronic form factors with above-threshold poles
Creators: name: Caprini, Irinel
name: Grinstein, Benjamin
name: Lebed, Richard F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: FOS: Physical sciences

description: Model-independent constraints on hadronic form factors, in particular those describing exclusive semileptonic decays, can be derived from the knowledge of field correlators calculated in perturbative QCD, using analyticity and unitarity. The location of poles corresponding to below-threshold resonances, i.e., stable states that cannot decay into a pair of hadrons from the crossed channel of the form factor, must be known a priori, and their effect, accounted for through the use of Blaschke factors, is to reduce the strength of the constraints in the semileptonic region. By contrast, above-threshold resonances appear as poles on unphysical Riemann sheets, and their presence does not affect the original model-independent constraints. We discuss the possibility that the above-threshold poles can provide indirect information on the form factors on the first Riemann sheet, either through information from their residues or by constraining the discontinuity function. The bounds on form factors can be improved by imposing, in an exact way, the additional information in the extremal problem. The semileptonic $K\to π\ell ν$ and $D\to π\ellν$ decays are considered as illustrations.
description: 9 pages, 1 pdf figure. Illustrative numerical results included. Version accepted for publication in Phys. Rev. D
A Multidimensional Szemerédi Theorem in the primes
Creators: name: Cook, Brian
name: Magyar, Ákos
name: Titichetrakun, Tatchai
Publisher: name: arXiv
Year: 2013
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics

description: Let $A$ be a subset of positive relative upper density of $\PP^d$, the $d$-tuples of primes. We prove that $A$ contains an affine copy of any finite set $F\subs\Z^d$, which provides a natural multi-dimensional extension of the theorem of Green and Tao on the existence of long arithmetic progressions in the primes. The proof uses the hypergraph approach by assigning a pseudo-random weight system to the pattern $F$ on a $d+1$-partite hypergraph; a novel feature being that the hypergraph is no longer uniform with weights attached to lower dimensional edges. Then, instead of using a transference principle, we proceed by extending the proof of the so-called hypergraph removal lemma to our settings, relying only on the linear forms condition of Green and Tao.
description: "via combinatorics" added in the title to link article with paper appeared in print
Probing the Early Universe using the Most Distant Quasars
Creators: name: Yang, Jinyi
Publisher: name: Zenodo
Year: 2023
Subjects: Galaxy Surveys at High Redshift

description: The growth of the earliest supermassive black holes (SMBHs), the assembly of early massive galaxies, and the history of cosmic reionization are the most important open questions. As the most luminous non-transit objects, quasars at z > 6 are indispensable probes of the early Universe. The recent high-z quasar surveys have pushed quasar frontier to z>7.5. I will summarize the recent studies of high-redshift quasars with JWST and present predictions on future quasar investigation with the upcoming Nancy Grace Roman space telescope. JWST opens a new era of the study of early quasars, with new wavelength coverage, high sensitivity, and high spatial resolution. The investigations cover new measurements of BH mass and growth, direct image of UV/optical emission in quasar host galaxy, AGN feedback, quasar environment, and the reionization history. JWST also offers a first chance to systematically search for obscured and faint AGN/quasar at high redshift. In the near future, the Roman telescope will lead the next generation wide-field surveys of first quasars. Its deep near-infrared photometric and spectroscopic observations will allow us to deeply search and investigate quasars to redshift z~9-10, with a significantly expanded quasar sample, which will revolutionize our understanding of the earliest quasars and the cosmic reionization.
On uniqueness and non-degeneracy of anisotropic polarons
Creators: name: Ricaud, Julien
Publisher: name: arXiv
Year: 2014
Subjects: subject: Mathematical Physics (math-ph)
subject: Analysis of PDEs (math.AP)
subject: FOS: Physical sciences
subject: FOS: Mathematics

description: We study the anisotropic Choquard--Pekar equation which de-scribes a polaron in an anisotropic medium. We prove the uniqueness and non-degeneracy of minimizers in a weakly anisotropic medium. In addition, for a wide range of anisotropic media, we derive the symmetry properties of minimizers and prove that the kernel of the associated linearized operator is reduced, apart from three functions coming from the translation invariance, to the kernel on the subspace of functions that are even in each of the three principal directions of the medium.
Phase space mass bound for fermionic dark matter from dwarf spheroidal galaxies
Creators: name: Di Paolo, Chiara
name: Nesti, Fabrizio
name: Villante, Francesco L.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Astrophysics of Galaxies (astro-ph.GA)
subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We reconsider the lower bound on the mass of a fermionic dark matter (DM) candidate resulting from the existence of known small Dwarf Spheroidal galaxies, in the hypothesis that their DM halo is constituted by degenerate fermions, with phase-space density limited by the Pauli exclusion principle. By relaxing the common assumption that the DM halo scale radius is tied to that of the luminous stellar component and by marginalizing on the unknown stellar velocity dispersion anisotropy, we prove that observations lead to rather weak constraints on the DM mass, that could be as low as tens of eV. In this scenario, however, the DM halos would be quite large and massive, so that a bound stems from the requirement that the time of orbital decay due to dynamical friction in the hosting Milky Way DM halo is longer than their lifetime. The smallest and nearest satellites Segue I and Willman I lead to a final lower bound of $m\gtrsim100$ eV, still weaker than previous estimates but robust and independent on the model of DM formation and decoupling. We thus show that phase space constraints do not rule out the possibility of sub-keV fermionic DM.
description: 14 pages, updated figures, clarified discussion, results unchanged. Version to appear in MNRAS
A Frobenius formula for the structure coefficients of double-class algebras of Gelfand pairs
Creators: name: Tout, Omar
Publisher: name: arXiv
Year: 2015
Subjects: subject: Combinatorics (math.CO)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 05E15

description: We generalise some well known properties of irreducible characters of finite groups to zonal spherical functions of Gelfand pairs. This leads to a Frobenius formula for Gelfand pairs. For a given Gelfand pair, the structure coefficients of its associated double-class algebra can be written in terms of zonal spherical functions. This is a generalisation of the Frobenius formula which writes the structure coefficients of the center of a finite group algebra in terms of irreducible characters.
Itineraries for Inverse Limits of Tent Maps: a Backward View
Creators: name: Boyland, Philip
name: de Carvalho, André
name: Hall, Toby
Publisher: name: arXiv
Year: 2017
Subjects: subject: Dynamical Systems (math.DS)
subject: FOS: Mathematics
subject: 37B10, 37E05

description: Previously published admissibility conditions for an element of $\{0,1\}^{\mathbb{Z}}$ to be the itinerary of a point of the inverse limit of a tent map are expressed in terms of forward orbits. We give necessary and sufficient conditions in terms of backward orbits, which is more natural for inverse limits. These backward admissibility conditions are not symmetric versions of the forward ones: in particular, the maximum backward itinerary which can be realised by a tent map mode locks on intervals of kneading sequences.
description: To appear in Topol. Appl. Author accepted manuscript. Includes some corrections - thanks to the referee
A general framework for the polynomiality property of the structure coefficients of double-class algebras
Creators: name: Tout, Omar
Publisher: name: arXiv
Year: 2015
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 05E15

description: Take a sequence of couples $(G_n,K_n)_n$, where $G_n$ is a group and $K_n$ is a sub-group of $G_n.$ Under some conditions, we are able to give a formula that shows the form of the structure coefficients that appear in the product of double-classes of $K_n$ in $G_n.$ We show how this can give us a similar result for the structure coefficients of the centers of group algebras. These formulas allow us to re-obtain the polynomiality property of the structure coefficients in the cases of the center of the symmetric group algebra and the Hecke algebra of the pair $(\mathcal{S}_{2n},\mathcal{B}_{n}).$ We also give a new polynomiality property for the structure coefficients of the center of the hyperoctahedral group algebra and the double-class algebra $\mathbb{C}[diag(\mathcal{S}_{n-1})\setminus \mathcal{S}_n\times \mathcal{S}^{opp}_{n-1}/ diag(\mathcal{S}_{n-1})].$
Magnon Condensation and Spin Superfluidity
Creators: name: Bunkov, Yury M.
name: Safonov, Vladimir L.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Gases (cond-mat.quant-gas)
subject: FOS: Physical sciences

description: We consider the phenomenon of Bose-Einstein condensation of quasi-equilibrium magnons which leads to a spin superfluidity, the coherent quantum transfer of magnetization in magnetic materials. These phenomena are beyond the classical Landau-Lifshitz-Gilbert paradigm. The critical conditions for excited magnon density for ferro- and antiferromagnets, bulk and thin films are estimated and discussed. The BEC should occur in the antiferromagnetic hematite at much lower excited magnon density compared to the ferromagnetic YIG.
description: 0 figures
Symmetry breaking in the periodic Thomas--Fermi--Dirac--von Weizs{ä}cker model
Creators: name: Ricaud, Julien
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We consider the Thomas--Fermi--Dirac--von~Weizs{ä}cker model for a system composed of infinitely many nuclei placed on a periodic lattice and electrons with a periodic density. We prove that if the Dirac constant is small enough, the electrons have the same periodicity as the nuclei. On the other hand if the Dirac constant is large enough, the 2-periodic electronic minimizer is not 1-periodic, hence symmetry breaking occurs. We analyze in detail the behavior of the electrons when the Dirac constant tends to infinity and show that the electrons all concentrate around exactly one of the 8 nuclei of the unit cell of size 2, which is the explanation of the breaking of symmetry. Zooming at this point, the electronic density solves an effective nonlinear Schrödinger equation in the whole space with nonlinearity $u^{7/3}-u^{4/3}$. Our results rely on the analysis of this nonlinear equation, in particular on the uniqueness and non-degeneracy of positive solutions.
Forward two-photon exchange in elastic lepton-proton scattering and hyperfine-splitting correction
Creators: name: Tomalak, Oleksandr
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: Nuclear Experiment (nucl-ex)
subject: Nuclear Theory (nucl-th)
subject: Atomic Physics (physics.atom-ph)
subject: FOS: Physical sciences

description: We relate the forward two-photon exchange (TPE) amplitudes to integrals of the inclusive lepton-proton scattering cross sections. These relations yield an alternative way for the evaluation of the TPE correction to hyperfine-splitting (HFS) in the hydrogen-like atoms with an equivalent to the standard approach (Iddings, Drell and Sullivan) result implying the Burkhardt-Cottingham sum rule. For evaluation of the individual effects (e.g., elastic contribution) our approach yields a distinct result. We compare both methods numerically on examples of the elastic contribution and the full TPE correction to HFS in electronic and muonic hydrogen.
description: 27 pages, 7 figures, correct description of corrections
Kähler manifolds with geodesic holomorphic gradients
Creators: name: Derdzinski, Andrzej
name: Piccione, Paolo
Publisher: name: arXiv
Year: 2017
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C55

description: A vector field on a Riemannian manifold is called geodesic if its integral curves are reparametrized geodesics. We classify compact Kähler manifolds admitting nontrivial real-holomorphic geodesic gradient vector fields that satisfy an additional integrability condition. They are all biholomorphic to bundles of complex projective spaces.
description: 52 pages
Gene length as a regulator for ribosome recruitment and protein synthesis: theoretical insights
Creators: name: Fernandes, Lucas D.
name: de Moura, Alessandro P. S.
name: Ciandrini, Luca
Publisher: name: arXiv
Year: 2017
Subjects: subject: Subcellular Processes (q-bio.SC)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: Protein synthesis rates are determined, at the translational level, by properties of the transcript's sequence. The efficiency of an mRNA can be tuned by varying the ribosome binding sites controlling the recruitment of the ribosomes, or the codon usage establishing the speed of protein elongation. In this work we propose transcript length as a further key determinant of translation efficiency. Based on a physical model that considers the kinetics of ribosomes advancing on the mRNA and diffusing in its surrounding, as well as mRNA circularisation and ribosome drop-off, we explain how the transcript length may play a central role in establishing ribosome recruitment and the overall translation rate of an mRNA. According to our results, the proximity of the 3' end to the ribosomal recruitment site of the mRNA could induce a feedback in the translation process that would favour the recycling of ribosomes. We also demonstrate how this process may be involved in shaping the experimental ribosome density-gene length dependence. Finally, we argue that cells could exploit this mechanism to adjust and balance the usage of its ribosomal resources.
Non-destructively probing the thermodynamics of quantum systems with qumodes
Creators: name: Elliott, Thomas J.
name: Gu, Mile
name: Thompson, Jayne
name: Liu, Nana
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: Quantum Gases (cond-mat.quant-gas)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences

description: Quantum systems are by their very nature fragile. The fundamental backaction on a state due to quantum measurement notwithstanding, there is also in practice often a destruction of the system itself due to the means of measurement. This becomes acutely problematic when we wish to make measurements of the same system at multiple times, or generate a large quantity of measurement statistics. One approach to circumventing this is the use of ancillary probes that couple to the system under investigation, and through their interaction, enable properties of the primary system to be imprinted onto and inferred from the ancillae. Here we highlight means by which continuous variable quantum modes (qumodes) can be employed to probe the thermodynamics of quantum systems in and out of equilibrium, including thermometry, reconstruction of the partition function, and reversible and irreversible work. We illustrate application of our results with the example of a spin-1/2 system in a transverse field.
description: 11 pages, 3 figures. Invited submission to Jonathan P. Dowling Memorial Special Issue
A local Langlands correspondence for unipotent representations
Creators: name: Solleveld, Maarten
Publisher: name: arXiv
Year: 2018
Subjects: subject: Representation Theory (math.RT)
subject: FOS: Mathematics

description: Let G be a connected reductive group over a non-archimedean local field K, and assume that G splits over an unramified extension of K. We establish a local Langlands correspondence for irreducible unipotent representations of G. It comes as a bijection between the set of such representations and the collection of enhanced L-parameters for G, which are trivial on the inertia subgroup of the Weil group of K. We show that this correspondence has many of the expected properties, for instance with respect to central characters, tempered representations, the discrete series, cuspidality and parabolic induction. The core of our strategy is the investigation of affine Hecke algebras on both sides of the local Langlands correspondence. When a Bernstein component of G-representations is matched with a Bernstein component of enhanced L-parameters, we prove a comparison theorem for the two associated affine Hecke algebras. This generalizes work of Lusztig in the case of adjoint K-groups.
description: Minor changes in version 2, in particular Lemma 1.1.b
Simple scheme for extracting work with a single bath
Creators: name: Piccione, Nicolò
name: Militello, Benedetto
name: Napoli, Anna
name: Bellomo, Bruno
Publisher: name: arXiv
Year: 2018
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We propose a simple protocol exploiting the thermalization of a $\textit{storage}$ bipartite system $S$ to extract work from a $\textit{resource}$ system $R$. The protocol is based on a recent work definition involving only a single bath. A general description of the protocol is provided without specifying the characteristics of $S$. We quantify both the extracted work and the ideal efficiency of the process also giving maximum bounds for them. Then, we apply the protocol to two cases: two interacting qubits and the Rabi model. In both cases, for very strong couplings, an extraction of work comparable with the bare energies of the subsystems of $S$ is obtained and its peak is reached for finite values of the bath temperature, $T$. We finally show, in the Rabi model at $T=0$, how to transfer the work stored in $S$ to an external device, permitting thus a cyclic implementation of the whole work-extraction protocol. Our proposal makes use of simple operations not needing fine control.
description: 13 pages, 9 figures. Updated version close to the published one
The center of the wreath product of symmetric groups algebra
Creators: name: Tout, Omar
Publisher: name: arXiv
Year: 2018
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics

description: We consider the wreath product of two symmetric groups as a group of blocks permutations and we study its conjugacy classes. We give a polynomiality property for the structure coefficients of the center of the wreath product of symmetric groups algebra. This allows us to recover an old result of Farahat and Higman about the polynomiality of the structure coefficients of the center of the symmetric group algebra and to generalize our recent result about the polynomiality property of the structure coefficients of the center of the hyperoctahedral group algebra. A particular attention is paid to the cases when the blocks contain two or three elements.
Pocket Guide to Solve Inverse Problems with GlobalBioIm
Creators: name: Soubies, Emmanuel
name: Soulez, Ferréol
name: McCann, Michael T.
name: Pham, Thanh-an
name: Donati, Laurène
name: Debarre, Thomas
name: Sage, Daniel
name: Unser, Michael
Publisher: name: arXiv
Year: 2018
Subjects: subject: Mathematical Software (cs.MS)
subject: FOS: Computer and information sciences

description: GlobalBioIm is an open-source MATLAB library for solving inverse problems. The library capitalizes on the strong commonalities between forward models to standardize the resolution of a wide range of imaging inverse problems. Endowed with an operator-algebra mechanism, GlobalBioIm allows one to easily solve inverse problems by combining elementary modules in a lego-like fashion. This user-friendly toolbox gives access to cutting-edge reconstruction algorithms, while its high modularity makes it easily extensible to new modalities and novel reconstruction methods. We expect GlobalBioIm to respond to the needs of imaging scientists looking for reliable and easy-to-use computational tools for solving their inverse problems. In this paper, we present in detail the structure and main features of the library. We also illustrate its flexibility with examples from multichannel deconvolution microscopy.
Maximally-warped metrics with harmonic curvature
Creators: name: Derdzinski, Andrzej
name: Piccione, Paolo
Publisher: name: arXiv
Year: 2018
Subjects: subject: Differential Geometry (math.DG)
subject: FOS: Mathematics
subject: 53C25 (Primary), 53B20 (Secondary)

description: We describe the local structure of Riemannian manifolds with harmonic curvature which admit a maximum number, in a well-defined sense, of local warped-product decompositions, and at the same time their Ricci tensor has, at some point, only simple eigenvalues. We also prove that, in every given dimension greater than two, the local-isometry types of such manifolds form a finite-dimensional moduli space, and a nonempty open subset of this moduli space is realized by locally irreducible complete metrics which are neither Ricci-parallel, nor -- for dimensions greater than three -- conformally flat.
description: Numerous typos corrected; Remark 7.3 rephrased as a theorem with a detailed proof; the discussion of the compact case made more complete by expanding the Introduction and bibliography, and adding Theorem 1.4
Modeling Charmonium-$η$ Decays of $J^{PC}=1^{--}$ Higher Charmonia
Creators: name: Anwar, Muhammad Naeem
name: Lu, Yu
name: Zou, Bing-Song
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: We propose a new model to create a light meson in the heavy quarkonium transition, which is inspired by the Nambu$-$Jona-Lasinio (NJL) model. Hadronic transitions of $J^{PC}=1^{--}$ higher charmonia with the emission of an $η$ meson are studied in the framework of the proposed model. The model shows its potential to reproduce the observed decay widths and make predictions for the unobserved channels. We present our predictions for the decay width of $Ψ\to J/ψη$ and $Ψ\to h_{c}(1P)η$, where $Ψ$ are higher $S$ and $D$ wave vector charmonia, which provide useful references to search for higher charmonia and determine their properties in forthcoming experiments. The predicted branching fraction $\mathcal B(ψ(4415)\to h_{c}(1P)η)=4.62\times 10^{-4}$ is one order of magnitude smaller than the $J/ψη$ channel. Estimates of partial decay width $Γ(Y \to J/ψη)$ are given for $Y(4360)$, $Y(4390)$ and $Y(4660)$ by assuming them as $c\bar{c}$ bound states with quantum numbers $3 ^3D_1$, $3 ^3D_1$ and $5 ^3S_1$, respectively. Our results are in favor of these assignments for $Y(4360)$ and $Y(4660)$. The corresponding experimental data for these $Y$ states has large statistical errors which do not provide any constraint on the mixing angle if we introduce $S-D$ mixing. To identify $Y(4390)$, precise measurements on its hadronic branching fraction are required which are eagerly awaited from BESIII.
description: version published in Phys. Rev. D
$k$-partial permutations and the center of the wreath product $\mathcal{S}_k\wr \mathcal{S}_n$ algebra
Creators: name: Tout, Omar
Publisher: name: arXiv
Year: 2019
Subjects: subject: Combinatorics (math.CO)
subject: Representation Theory (math.RT)
subject: FOS: Mathematics
subject: 05E05, 05E10, 05E15, 20C30

description: We generalize the concept of partial permutations of Ivanov and Kerov and introduce $k$-partial permutations. This allows us to show that the structure coefficients of the center of the wreath product $\mathcal{S}_k\wr \mathcal{S}_n$ algebra are polynomials in $n$ with non-negative integer coefficients. We use a universal algebra $\mathcal{I}_\infty^k$ which projects on the center $Z(\mathbb{C}[\mathcal{S}_k\wr \mathcal{S}_n])$ for each $n.$ We show that $\mathcal{I}_\infty^k$ is isomorphic to the algebra of shifted symmetric functions on many alphabets.
Weak Galerkin finite element method for second order problems on curvilinear polytopal meshes with Lipschitz continuous edges or faces
Creators: name: Guan, Qingguang
name: Queisser, Gillian
name: Zhao, Wenju
Publisher: name: arXiv
Year: 2019
Subjects: subject: Numerical Analysis (math.NA)
subject: FOS: Mathematics

description: In this paper, we propose new basis functions defined on curved sides or faces of curvilinear elements (polygons or polyhedrons with curved sides or faces) for the weak Galerkin finite element method. Those basis functions are constructed by collecting linearly independent traces of polynomials on the curved sides/faces. We then analyze the modified weak Galerkin method for the elliptic equation and the interface problem on curvilinear polytopal meshes with Lipschitz continuous edges or faces. The method is designed to deal with less smooth complex boundaries or interfaces. Optimal convergence rates for $H^1$ and $L^2$ errors are obtained, and arbitrary high orders can be achieved for sufficiently smooth solutions. The numerical algorithm is discussed and tests are provided to verify theoretical findings.