ShantanuT01/DACTYL-Pretraining huggingface dataset:
Dimensionality reduction induced metal-insulator transitions in oxide heterostructures are usually coupled with structural and magnetic phase transitions, which complicate the interpretation of the underlying physics. Therefore, achieving isostructural MIT is of great importance for fundamental physics and even more for applications. Here, we report an isostructural metal-insulator transition driven by dimensional-crossover in spin-orbital coupled SrIrO3 films. By using in-situ pulsed laser deposition and angle-resolved photoemission spectroscopy, we synthesized and investigated the electronic structure of SrIrO3 ultrathin films with atomic-layer precision. Through inserting orthorhombic CaTiO3 buffer layers, we demonstrate that the crystal structure of SrIrO3 films remains bulk-like with similar oxygen octahedra rotation and tilting when approaching the ultrathin limit. We observe that a dimensional-crossover metal-insulator transition occurs in isostructural SrIrO3 films. Intriguingly, we find the bandwidth of Jeff=3/2 states reduces with lowering the dimensionality and drives the metal-insulator transition. Our results establish a bandwidth controlled metal-insulator transition in the isostructural SrIrO3 thin films.
We use K-band spectroscopic data from the Multi-Object Spectroscopic Emission Line (MOSEL) survey to analyze the kinematic properties of galaxies at z>3. Our sample consists of 34 galaxies at 3.0<zspec<3.8 between 9.0<log(M_star)<11.0. We find that galaxies with log(M_star) > 10.2 at z > 3 have 56 +/- 21 km/s lower integrated velocity dispersion compared to galaxies at z ~ 2 of similar stellar mass. Massive galaxies at z > 3 have either a flat or declining star formation history (SFH), whereas similar stellar mass galaxies at z~2.0 exhibit a slight peak in the past 500 Myrs. Comparing with the IllustrisTNG cosmological simulation, we find that (i) the dynamical mass of massive galaxies in simulations (log(M_star) > 10.0) increases by ~0.1 dex at a fixed stellar mass between z=2.0-3.0, and (ii) dynamical mass growth is coupled with a rapid rise in the ex-situ stellar mass fraction (stars accreted from other galaxies) for massive galaxies at z < 3.5. We speculate that the rising contribution of ex-situ stellar mass to the total stellar mass growth of massive galaxies is driving the higher integrated velocity dispersion and rising SFHs of massive galaxies at z~2.0 compared to galaxies of similar stellar masses at z > 3.
We introduce and study filtrations of a matroid on a linearly ordered ground set, which are particular sequences of nested sets. A given basis can be decomposed into a uniquely defined sequence of bases of minors, such that these bases have an internal/external activity equal to 1/0 or 0/1 (in the sense of Tutte polynomial activities). This decomposition, which we call the active filtration/partition of the basis, refines the known partition of the ground set into internal and external elements with respect to a given basis. It can be built by a certain closure operator, which we call the active closure. It relies only on the fundamental bipartite graph of the basis and can be expressed also as a decomposition of general bipartite graphs on a linearly ordered set of vertices.   From this, first, structurally, we obtain that the set of all bases can be canonically partitioned and decomposed in terms of such bases of minors induced by filtrations. Second, enumeratively, we derive an expression of the Tutte polynomial of a matroid in terms of beta invariants of minors. This expression refines at the same time the classical expressions in terms of basis activities and orientation activities (if the matroid is oriented), and the well-known convolution formula for the Tutte polynomial. Third, in a companion paper of the same series (No. 2.b), we use this decomposition of matroid bases, along with a similar decomposition of oriented matroids, and along with a bijection in the 1/0 activity case from a previous paper (No. 1), to define the canonical active bijection between orientations/signatures/reorientations and spanning trees/simplices/bases of a graph/real hyperplane arrangement/oriented matroid, as well as various related bijections.
In this paper we propose a measure of anisotropy as a quality parameter to estimate the amount of noise in noisy images. The anisotropy of an image can be determined through a directional measure, using an appropriate statistical distribution of the information contained in the image. This new measure is achieved through a stack filtering paradigm. First, we define a local directional entropy, based on the distribution of 0's and 1's in the neigborhood of every pixel location of each stack level. Then the entropy variation of this directional entropy is used to define an anisotropic measure. The empirical results have shown that this measure can be regarded as an excellent image noise indicator, which is particularly relevant for quality assessment of denoising algorithms. The method has been evaluated with artificial and real-world degraded images.
This work is devoted to the variational derivation of a reduced model for brittle membranes in finite elasticity. The main mathematical tools we develop for our analysis are: (i) a new density result in $GSBV^{p}$ of functions satisfying a maximal-rank constraint on the subgradients, which can be approximated by $C^{1}$-local immersions on regular subdomains of the cracked set, and (ii) the construction of recovery sequences by means of suitable $W^{1,\infty}$ diffeomorphisms mapping the regular subdomains onto the fractured configuration.
An exact closed equation for s - particle equilibrium distribution function (s<N) of the system of N>>1 interacting particles is obtained. This integra-differential {\beta} - convolution equation ({\beta}=1/k_{B}T) follows from the Bloch equation for the canonical distribution function by applying the projection operator integrating off the coordinates of N-s irrelevant particles. The method of expansion of the obtained equation kernel in the particle density n is suggested. The solution to this equation in the linear in n approximation for the kernel is found.
The generalized Langevin equation is widely used to model the influence of a heat bath upon a reactive system. This equation will here be studied from a geometric point of view. A dynamical phase space that represents all possible states of the system will be constructed, the generalized Langevin equation will be formally rewritten as a pair of coupled ordinary differential equations, and the fundamental geometric structures in phase space will be described. It will be shown that the phase space itself and its geometric structure depend critically on the preparation of the system: A system that is assumed to have been in existence for ever has a larger phase space with a simpler structure than a system that is prepared at a finite time. These differences persist even in the long-time limit, where one might expect the details of preparation to become irrelevant.
This paper was withdrawn by the authors due an error in the elimination of the front in the linearized interior equations (28)-(29).
We study ground states and beta decay properties of the proton rich isotope chains Ge, Se, Kr, and Sr. We use a deformed selfconsistent HF+RPA approach with density-dependent effective interactions of Skyrme type. We find that most of the isotopes present two HF minima corresponding to two different shapes. In addition to static quadrupole moments and other ground state band properties, we present results for Gamow-Teller strength distributions, as well as for half-lives and summed strengths. The role of deformation is particularly emphasized.
We derive the hydrodynamic limit of Glauber-Kawasaki dynamics. The Kawasaki part is simple and describes independent movement of the particles with hard core exclusive interactions. It is speeded up in a diffusive space-time scaling. The Glauber part describes the birth and death of particles. It is set to favor two levels of particle density with a preference for one of the two. It is also speeded up in time, but at a lesser rate than the Kawasaki part. Under this scaling, the limiting particle density instantly takes either of the two favored density values. The interface which separates these two values evolves with constant speed (Huygens' principle).   Similar hydrodynamic limits have been derived in four recent papers. The crucial difference with these papers is that we consider Glauber dynamics which has a preferences for one of the two favored density values. As a result, we observe limiting dynamics on a shorter time scale, and the evolution is different from the mean curvature flow obtained in the four previous papers. While several steps in our proof can be adopted from these papers, the proof for the propagation of the interface is new.
In the noncommutative (Moyal) plane, we relate exact U(1) sigma-model solitons to generic scalar-field solitons for an infinitely stiff potential. The static k-lump moduli space C^k/S_k features a natural K"ahler metric induced from an embedding Grassmannian. The moduli-space dynamics is blind against adding a WZW-like term to the sigma-model action and thus also applies to the integrable U(1) Ward model. For the latter's two-soliton motion we compare the exact field configurations with their supposed moduli-space approximations. Surprisingly, the two do not match, which questions the adiabatic method for noncommutative solitons.
To clarify the transport property mediated by bound magnons in a spin nematic state, we investigate the spin Drude weight of a spin-1/2 $J_{1}$-$J_{2}$ Heisenberg chain with ferromagnetic $J_{1}$ and antiferromagnetic $J_{2}$ in a magnetic field by numerical diagonalization. At zero magnetic field, numerical results with up to 24 sites suggest that the spin Drude weight would be zero in the thermodynamic limit, indicating diffusive spin transport. With increasing the magnetic field, the spin Drude weight is enhanced at low temperatures, indicating that bound magnons would contribute to the spin transport.
RCW~38 is a uniquely young ($<$1 Myr), embedded ($A_V \sim 10$) stellar cluster surrounding a pair of early O stars ($\sim$O5.5) and is one of the few regions within 2 kpc other than Orion to contain over 1000 members. X-ray and deep near-infrared observations reveal a dense cluster with over 200 X-ray sources and 400 infrared sources embedded in a diffuse hot plasma within a 1 pc diameter. The central O star has evacuated its immediate surroundings of dust, creating a wind bubble $\sim$0.1 pc in radius that is confined by the surrounding molecular cloud, as traced by millimeter continuum and molecular line emission. The interface between the bubble and cloud is a region of warm dust and ionized gas, which shows evidence for ongoing star formation. Extended warm dust is found throughout a 2--3 pc region and coincides with extended X-ray plasma. This is evidence that the influence of the massive stars reaches beyond the confines of the O star bubble. RCW~38 appears similar in structure to RCW~49 and M~20 but is at an earlier evolutionary phase. RCW~38 appears to be a blister compact H{\small II} region lying just inside the edge of a giant molecular cloud.
The distributions of the bottom quark in the process $e^+ e^- \to t \, \bar{t} \to b \, W^+ \, \bar{t}$ are considered at the $e^+ e^-$ energy corresponding to the first construction stage of the Compact Linear Collider. The cross sections of $e^+ e^- \to b \ldots$, as functions of the $b$-quark energy and angle with respect to the direction of the electron beam, are derived and calculated. The effects of physics beyond the Standard Model are included via the modified $\gamma t \bar{t}$ and $Z t \bar{t}$ couplings which naturally appear in effective field theories. In addition to the cross sections, the energy and angular asymmetries are calculated. The dependence of these observables on the $e^+ e^-$ energy is calculated, and features of this dependence are investigated.
Timing analysis of PSR J1705$-$1906 using data from Nanshan 25-m and Parkes 64-m radio telescopes, which span over fourteen years, shows that the pulsar exhibits significant proper motion, and rotation instability. We updated the astrometry parameters and the spin parameters of the pulsar. In order to minimize the effect of timing irregularities on measuring its position, we employ the Cholesky method to analyse the timing noise. We obtain the proper motion of $-$77(3) \,mas\,yr$^{-1}$ in right ascension and $-$38(29) \,mas\,yr$^{-1}$ in declination. The power spectrum of timing noise is analyzed for the first time, which gives the spectral exponent $\alpha=-5.2$ for the power-law model indicating that the fluctuations in spin frequency and spin-down rate dominate the red noise. We detect two small glitches from this pulsar with fractional jump in spin frequency of $\Delta \nu/\nu\sim2.9\times10^{-10}$ around MJD~55199 and $\Delta \nu/\nu\sim2.7\times10^{-10}$ around MJD~55953. Investigations of pulse profile at different time segments suggest no significant changes in the pulse profiles around the two glitches.
Given any non-polynomial $G$-function $F(z)=\sum\_{k=0}^\infty A\_k z^k$ of radius of convergence $R$, we consider the $G$-functions $F\_n^{[s]}(z)=\sum\_{k=0}^\infty \frac{A\_k}{(k+n)^s}z^k$ for any integers $s\geq 0$ and $n\geq 1$. For any fixed algebraic number $\alpha$ such that $0 \textless{} \vert \alpha \vert \textless{} R$ and any number field $\mathbb{K}$ containing $\alpha$ and the $A\_k$'s, we define $\Phi\_{\alpha, S}$ as the $\mathbb{K}$-vector space generated by the values $F\_n^{[s]}(\alpha)$, $n\ge 1$ and $0\leq s\leq S$. We prove that $u\_{\mathbb{K},F}\log(S)\leq \dim\_{\mathbb{K}}(\Phi\_{\alpha, S})\leq v\_F S$ for any $S$, with effective constants $u\_{\mathbb{K},F}\textgreater{}0$ and $v\_F\textgreater{}0$, and that the family $(F\_n^{[s]}(\alpha))\_{1\le n \le v\_F, s \ge 0}$ contains infinitely many irrational numbers. This theorem applies in particular when $F$ is an hypergeometric series with rational parameters or a multiple polylogarithm, and it encompasses a previous result by the second author and Marcovecchio in the case of polylogarithms. The proof relies on an explicit construction of Pad\'e-type approximants. It makes use of results of Andr\'e, Chudnovsky and Katz on $G$-operators, of a new linear independence criterion \`a la Nesterenko over number fields, of singularity analysis as well as of the saddle point method.
The long carrier lifetime and defect tolerance in metal halide perovskites (MHPs) are major contributors to the superb performance of MHP optoelectronic devices. Large polarons were reported to be responsible for the long carrier lifetime. Yet microscopic mechanisms of the large polaron formation including the so-called phonon melting, are still under debate. Here, time-of-flight (TOF) inelastic neutron scattering (INS) experiments and first-principles density-functional theory (DFT) calculations were employed to investigate the lattice vibrations (or phonon dynamics) in methylammonium lead iodide ($\rm{MAPbI_3}$), a prototypical example of MHPs. Our findings are that optical phonons lose temporal coherence gradually with increasing temperature which vanishes at the orthorhombic-to-tetragonal structural phase transition. Surprisingly, however, we found that the spatial coherence is still retained throughout the decoherence process. We argue that the temporally decoherent and spatially coherent vibrations contribute to the formation of large polarons in this metal halide perovskite.
The process of stimulated Raman adiabatic passage (STIRAP) provides a possible route for the generation of a coherent molecular Bose-Einstein condensate (BEC) from an atomic BEC. We analyze this process in a three-dimensional mean-field theory, including atom-atom interactions and non-resonant intermediate levels. We find that the process is feasible, but at larger Rabi frequencies than anticipated from a crude single-mode lossless analysis, due to two-photon dephasing caused by the atomic interactions. We then identify optimal strategies in STIRAP allowing one to maintain high conversion efficiencies with smaller Rabi frequencies and under experimentally less demanding conditions.
We study the interplay between the discrete geometry of Bruhat poset intervals and subword complexes of finite Coxeter systems. We establish connections between the cones generated by cover labels for Bruhat intervals and of root configurations for subword complexes, culminating in the notion of brick polyhedra for general subword complexes.
The paper studies explicitly the Hitchin system restricted to the Higgs fields on a fixed very stable rank 2 bundle in genus 2 and 3. The associated families of quadrics relate to both the geometry of Penrose's twistor spaces and several classical results.
For the inertial Qian-Sheng model of nematic liquid crystals in the $Q$-tensor framework, we illustrate the roles played by the entropy inequality and energy dissipation in the well-posedness of smooth solutions when we employ energy method. We first derive the coefficients requirements from the entropy inequality, and point out the entropy inequality is insufficient to guarantee energy dissipation. We then introduce a novel Condition (H) which ensures the energy dissipation. We prove that when both the entropy inequality and Condition (H) are obeyed, the local in time smooth solutions exist for large initial data. Otherwise, we can only obtain small data local solutions. Furthermore, to extend the solutions globally in time and obtain the decay of solutions, we require at least one of the two conditions: entropy inequality, or $\tilde{\mu}_2= \mu_2$, which significantly enlarge the range of the coefficients in previous works.
The cross section of $e^+e^- \rightarrow \eta J/\psi$ has been measured by BESIII and Belle experiments. Fit to the $e^+e^- \rightarrow \eta J/\psi$ line shape, three resonant structures are evident. The parameters for the three resonant structures are $M_{1}=(3980\pm17\pm7)$ MeV/$c^{2}$, $\Gamma_{1}=(104\pm32\pm13)$ MeV; $M_{2}=(4219\pm5\pm4)$ MeV/$c^{2}$, $\Gamma_{2}=(63\pm9\pm3)$ MeV; $M_{3}=(4401\pm12\pm4)$ MeV/$c^{2}$, $\Gamma_{3}=(49\pm19\pm4)$ MeV, where the first uncertainties are statistical and the second systematic. We attribute the three structures to $\psi(4040)$, $Y(4220)$ and $\psi(4415)$ states. The branching fractions $\mathcal{B}(\psi(4040) \rightarrow \eta J/\psi)$ and $\mathcal{B}(\psi(4415) \rightarrow \eta J/\psi)$ are given. If $Y(4220)$ is taken as $\psi(4S)$ state, the branching fraction $\mathcal{B}(\psi(4S) \rightarrow \eta J/\psi)$ is also given. Combining all $Y(4220)$ parameters obtained from different decays, we give average parameters for $Y(4220)$, which are $M_{Y(4220)}=(4220.8\pm2.4)$ MeV/$c^{2}$, $\Gamma_{Y(4220)}=(54.8\pm3.3)$ MeV.
The first V Rc Ic bands light curves of MQ UMa are presented and analyzed using the Wilson-Devinney (W-D) program. It is discovered that MQ UMa is an A-subtype contact binary with a high fill-out (f=82 %) and a low mass ratio (q = 0:195), which indicates that it is in the late evolutionary stage of latetype tidal-locked binary stars. The mass of the primary and secondary stars are estimated and the evolutionary status of the two components are placed in the H-R diagram. The W-D solutions also indicates that MQ UMa may be a triple system with an F5V type additional component. A sample of sixteen high fillout, low mass ratio overcontact binaries are collected and their possible evolution scenarios are discussed. Using the five times of light minimum recently observed together with those collected from literatures, the authors find that the observedcalculate (O-C) curve exhibits a cyclic period variation. The cyclic period change also reveals the presence of a tertiary component, which may play an important role in the formation and evolution of this binary system by drawing angular momentum from the central system.
Amongst $d$-regular $r$-uniform hypergraphs on $n$ vertices, which ones have the largest number of independent sets? While the analogous problem for graphs (originally raised by Granville) is now well-understood, it is not even clear what the correct general conjecture ought to be; our goal here is propose such a generalisation. Lending credence to our conjecture, we verify it within the class of `quasi-bipartite' hypergraphs (a generalisation of bipartite graphs that seems natural in this context) by adopting the entropic approach of Kahn.
This article is a review of Soft Gamma Repeaters and Anomalous X-ray Pulsars. It contains a brief historical record of the emergence of these classes of neutron stars, a thorough overview of the observational data, a succinct summary of the magnetar model, and suggested directions for future research in this field.
Highly polarized mixtures of atomic Fermi gases constitute a novel Fermi liquid. We demonstrate how information on thermodynamic properties may be used to calculate quasiparticle scattering amplitudes even when the interaction is resonant and apply the results to evaluate the damping of the spin dipole mode. We estimate that under current experimental conditions, the mode would be intermediate between the hydrodynamic and collisionless limits.
The one-photon absorption cross section of nanocrystals (NCs) of the inorganic perovskite CsPbBr$_{3}$ is studied theoretically using a multiband $\mathbf{k}\cdot\mathbf{p}$ envelope-function model combined with a treatment of intercarrier correlation by many-body perturbation theory. A confined exciton is described first within the Hartree-Fock (HF) approximation, and correlation between the electron and hole is then included in leading order by computing the first-order vertex correction to the electron-photon interaction. The vertex correction is found to give an enhancement of the near-threshold absorption cross section by a factor of up to 4 relative to the HF (mean-field) value of the cross section, for NCs with an edge length $L=9$-12 nm (regime of intermediate confinement). The vertex-correction enhancement factors are found to decrease with increasing exciton energy; the absorption cross section for photons of energy $\omega=3.1$ eV (about 0.7 eV above threshold) is enhanced by a factor of only 1.4-1.5 relative to the HF value. The $\mathbf{k}\cdot\mathbf{p}$ corrections to the absorption cross section are also significant; they are found to increase the cross section at an energy $\omega=3.1$ eV by about 30% relative to the value found in the effective-mass approximation. The theoretical absorption cross section at $\omega=3.1$ eV, assuming a Kane parameter $E_{P}=20$ eV, is found to be intermediate among the set of measured values (which vary among themselves by nearly an order of magnitude) and to obey a power-law dependence $\sigma^{(1)}(\omega)\propto L^{2.9}$ on the NC edge length $L$, in good agreement with experiment. The dominant contribution to the theoretical exponent 2.9 is shown to be the density of final-state excitons. The main theoretical uncertainty in these calculations is in the value of the Kane parameter $E_{P}$.