ShantanuT01/DACTYL-Pretraining huggingface dataset:
We report multi-wavelength observations of the unidentified Fermi object 2FGL J1653.6-0159. With the help of high-resolution X-ray observation, we have identified an X-ray and optical counterpart of 2FGL J1653.6-0159. The source exhibits a periodic modulation of 75 min in optical and possibly also in X-ray. We suggest that 2FGL J1653.6-0159 is a compact binary system with an orbital period of 75 min. Combining the gamma-ray and X-ray properties, 2FGL J1653.6-0159 is potentially a black widow/redback type gamma-ray millisecond pulsar (MSP). The optical and X-ray lightcurve profiles show that the companion is mildly heated by the high-energy emission and the X-rays are from intrabinary shock. Although no radio pulsation has been detected yet, we estimated that the spin period of the MSP is ~2ms based on a theoretical model. If pulsation can be confirmed in the future, 2FGL J1653.6-0159 will become the first ultracompact rotation-powered MSP.
We examine neutral-current quasi-elastic neutrino-nucleus reactions on $^{12}$C and $^{208}$Pb targets. We use the relativistic mean field theory approach to describe the nuclear dynamics. We compute the cross sections for the scattering of 150-MeV, 500-MeV and 1000-MeV neutrinos on a $^{12}$C target and study the effect of the strange-quark content of the nucleon which appears in these reactions via the isoscalar weak current. We compare our results with the data of the MiniBooNE experiment for mineral oil (CH$_2$). We also calculate the cross section for the quasi-elastic neutron knockout reaction of 20 to 60-MeV neutrinos on a $^{208}$Pb target which is relevant to plans to use lead as a target material in future supernova neutrino detectors.
We consider the moduli spaces of representations of the fundamental group of a surface of genus g greater than 2 in the Lie groups SU(2,2) and Sp(4,R). It is well known that there is a characteristic number of such a representation, whose absolute value is less than or equal to 2g-2. This allows one to write the moduli space as a union of subspaces indexed by the characteristic number, each of which is a union of connected components. The main result of this paper is that the subspaces with characteristic number plus or minus 2g-2 are connected in the case of representations in SU(2,2), while they break up into 2^{2g+1}+2g-3 connected components in the case of representations in Sp(4,R). We obtain our results using the interpretation of the moduli space of representations as a moduli space of Higgs bundles, and an important step is an identification of certain subspaces as moduli spaces of stable triples, as studied by Bradlow and Garcia-Prada.
We study the coefficients of a natural basis for the space of weak harmonic Maass forms of weight $5/2$ on the full modular group. The non-holomorphic part of the first element of this infinite basis encodes the values of the partition function $p(n)$. We show that the coefficients of these harmonic Maass forms are given by traces of singular invariants. These are values of non-holomorphic modular functions at CM points or their real quadratic analogues: cycle integrals of such functions along geodesics on the modular curve. The real quadratic case relates to recent work of Duke, Imamo\=glu, and T\'oth on cycle integrals of the $j$-function, while the imaginary quadratic case recovers the algebraic formula of Bruinier and Ono for the partition function.
Cosmological solutions for homogeneous isotropic models in the framework of the Poincar\'e gauge theory of gravity based on gravitational Lagrangian adopted in the paper by Kun-Feng Shie, James M. Nester and Hwei-Jang Yo (Phys. Rev. D \textbf{78}, 023522 (2008)) are discussed. Cosmological solutions for accelerating Universe obtained in referred paper are compared with corresponding solutions of standard $\Lambda CDM$-model and also with cosmological solution obtained by authors of this Comment.
We demonstrate equilibration of isolated many-body systems in the sense that, after initial transients have died out, the system behaves practically indistinguishable from a time-independent steady state, i.e., non-negligible deviations are unimaginably rare in time. Measuring the distinguishability in terms of quantum mechanical expectation values, results of this type have been previously established under increasingly weak assumptions about the initial disequilibrium, the many-body Hamiltonian, and the considered observables. Here, we further extend these results with respect to generalized distinguishability measures which fully take into account the fact that the actually observed, primary data are not expectation values but rather the probabilistic occurrence of different possible measurement outcomes.
In this paper we show that the family of stable vector bundles gives a set of generators for the Chow ring, the K-theory and the derived category of any smooth projective variety.
We present a new method for modeling inhomogeneous cosmic reionization on large scales. Utilizing high-resolution radiation-hydrodynamic simulations with 2048^3 dark matter particles, 2048^3 gas cells, and 17 billion adaptive rays in a L = 100 Mpc/h box, we show that the density and reionization-redshift fields are highly correlated on large scales (>~ 1 Mpc/h). This correlation can be statistically represented by a scale-dependent linear bias. We construct a parametric function for the bias, which is then used to filter any large-scale density field to derive the corresponding spatially varying reionization-redshift field. The parametric model has three free parameters which can be reduced to one free parameter when we fit the two bias parameters to simulations results. We can differentiate degenerate combinations of the bias parameters by combining results for the global ionization histories and correlation length between ionized regions. Unlike previous semi-analytic models, the evolution of the reionization-redshift field in our model is directly compared cell by cell against simulations and preforms well in all tests. Our model maps the high-resolution, intermediate-volume radiation-hydrodynamic simulations onto lower-resolution, larger-volume N-body simulations (>~ 2 Gpc/h) in order to make mock observations and theoretical predictions.
Tidal disruption events involve numerous physical processes (fluid dynamics, magnetohydrodynamics, radiation transport, self-gravity, general relativistic dynamics) in highly nonlinear ways, and, because TDEs are transients by definition, frequently in non-equilibrium states. For these reasons, numerical solution of the relevant equations can be an essential tool for studying these events. In this chapter, we present a summary of the key problems of the field for which simulations offer the greatest promise and identify the capabilities required to make progress on them. We then discuss what has been---and what cannot be---done with existing numerical methods. We close with an overview of what methods now under development may do to expand our ability to understand these events.
Structure learning for 3D shapes is vital for 3D computer vision. State-of-the-art methods show promising results by representing shapes using implicit functions in 3D that are learned using discriminative neural networks. However, learning implicit functions requires dense and irregular sampling in 3D space, which also makes the sampling methods affect the accuracy of shape reconstruction during test. To avoid dense and irregular sampling in 3D, we propose to represent shapes using 2D functions, where the output of the function at each 2D location is a sequence of line segments inside the shape. Our approach leverages the power of functional representations, but without the disadvantage of 3D sampling. Specifically, we use a voxel tubelization to represent a voxel grid as a set of tubes along any one of the X, Y, or Z axes. Each tube can be indexed by its 2D coordinates on the plane spanned by the other two axes. We further simplify each tube into a sequence of occupancy segments. Each occupancy segment consists of successive voxels occupied by the shape, which leads to a simple representation of its 1D start and end location. Given the 2D coordinates of the tube and a shape feature as condition, this representation enables us to learn 3D shape structures by sequentially predicting the start and end locations of each occupancy segment in the tube. We implement this approach using a Seq2Seq model with attention, called SeqXY2SeqZ, which learns the mapping from a sequence of 2D coordinates along two arbitrary axes to a sequence of 1D locations along the third axis. SeqXY2SeqZ not only benefits from the regularity of voxel grids in training and testing, but also achieves high memory efficiency. Our experiments show that SeqXY2SeqZ outperforms the state-ofthe-art methods under widely used benchmarks.
The lattice thermal expansion and conductivity in bulk Mo and W-based transition metal dichalcogenides are investigated by means of density functional and Boltzmann transport theory calculations. To this end, a recent van der Waals density functional (vdW-DF-CX) is employed, which is shown to yield excellent agreement with reference data for the structural parameters. The calculated in-plane thermal conductivity compares well with experimental room temperature values, when phonon-phonon and isotopic scattering are included. To explain the behavior over the entire available temperature range one must, however, include additional (temperature independent) scattering mechanisms that limit the mean free path. Generally, the primary heat carrying modes have mean free paths of $1\,\mu\text{m}$ or more, which makes these materials very susceptible to structural defects. The conductivity of Mo and W-based TMDs is primarily determined by the chalcogenide species and increases in the order Te-Se-S. While for the tellurides and selenides the transition metal element has a negligible effect, the conductivity of WS$_2$ is notably higher than for MoS$_2$, which can be traced to the much larger phonon band gap of the former. Overall the present study provides a consistent set of thermal conductivities that reveal chemical trends and constitute the basis for future investigations of van der Waals solids.
This is a Bachelor's thesis on quantum key distribution in the non-asymptotic regime submitted to the Leibniz Universit\"at Hannover, Germany. It deals with the question how to generate a key to encrypt messages between two honest parties that an eavesdropper does not gain any information about. The purpose of this thesis is to give an overview over the current state of the prepare and measure quantum key distribution protocol and its security proof with a specific focus on the non-asymptotic case. Therefore, we present the different steps of the protocol and retrace them with the help of the BB84-protocol. Afterwards, the security proof of this protocol is introduced and in the end, we have a closer look at the quantum capacity and calculate it for the amplitude damping channel.
Quantum Spin Hall (QSH) insulators with a large topologically nontrivial bulk gap are crucial for future applications of the QSH effect. Among these, group III-V monolayers and their halides with chair structure (regular hexagonal framework, RHF) were widely studied. Using first-principles calculations, we propose a new structure model for the functionalized group III-V monolayers, which consist of rectangular GaBi-X2 (X=I, Br, Cl) monolayers with a distorted hexagonal framework (DHF). These structures have a much lower energy than the GaBi-X2 monolayers with chair structure. Remarkably, the DHF GaBi-X2 monolayers are all QSH insulators, which exhibit sizeable nontrivial band gaps ranging from 0.17 eV to 0.39 eV. Those band gaps can be widely tuned by applying different spin-orbit coupling (SOC) strengths, resulting in a distorted Dirac cone.
We study the effects of channel coupling in the excitation dynamics of giant resonances in relativistic heavy ions collisions. For this purpose, we use a semiclassical approximation to the Coupled-Channels problem and separate the Coulomb and the nuclear parts of the coupling into their main multipole components. In order to assess the importance of multi-step processes, we neglect the resonance widths and solve the set of coupled equations exactly. Finite widths are then considered. In this case, we handle the coupling of the ground state with the dominant Giant Dipole Resonance exactly and study the excitation of the remaining resonances within the Coupled-Channels Born Approximation. A comparison with recent experimental data is made.
We discuss invariance principles for autoregressive tempered fractionally integrated moving averages in $\alpha$-stable $(1< \alpha \le 2)$ i.i.d. innovations and related tempered linear processes with vanishing tempering parameter $\lambda \sim \lambda_*/N$. We show that the limit of the partial sums process takes a different form in the weakly tempered ($\lambda_* = 0$), strongly tempered ($\lambda_* = \infty$), and moderately tempered ($0<\lambda_* < \infty$) cases. These results are used to derive the limit distribution of the OLS estimate of AR(1) unit root with weakly, strongly, and moderately tempered moving average errors.
We study ergodic properties of stochastic geometric wave equations on a particular model with the target being the 2D sphere while considering the space variable-independent solutions only. This simplification leads to a degenerate stochastic equation in the tangent bundle of the 2D sphere. Studying this equation, we prove existence and non-uniqueness of invariant probability measures for the original problem and we obtain also results on attractivity towards an invariant measure. We also present a suitable numerical scheme for approximating the solutions subject to a sphere constraint.
We study some divisibility properties related to the factors of the discriminant of the characteristic polynomial of generalized Fibonacci sequences $(G_n)_{n\ge0}$ defined by $G_0=0$, $G_1=1$ and $G_n=pG_{n-1}+qG_{n-2}$ for $n\ge2$, where $p,q$ are given integers. As corollaries, we give some divisibility properties on some well known sequences.
In this work, Krein space quantization method is applied to eliminate the Ultraviolet divergence of Green functions. This paper shows that the power spectrum of scalar field fluctuations can be calculated in the limit of short distance physics, trans-Planckian physics, without using the usual re-normalization process.
The McMullen Correspondence gives a linear dependence between M-sequences of length |d/2|+1 and f-vectors of simplical d-polytopes. Denote the transfer matrix between g and f by M_d. Recently, Bjorner proved that any 2x2-minor of M_d is nonnegative and conjectured that the same would be true for arbitrary minors. In this paper we answer the question in the affirmative.
We show the existence of the growth exponent for loop-erased random walk in three dimensions.
Employing mainly numerical methods, we explore the ground-state phase diagram of an anisotropic $S=1/2$ ladder, in which leg interactions are uniform and isotropic, while rung interactions are alternating and have a common Ising-type anisotropy. We determine the phase diagram in the case where $J_{\rm leg}=0.2$ (antiferromagnetic), $J_{\rm rung}=-1.0$ (ferromagnetic) and $|J_{\rm rung}'|\!\leq\!1.0$, the first one being the magnitude of the leg interaction and the second and third ones those of the rung interactions, which are alternating. It is emphasized that the system has a frustration when $J_{\rm rung}'$ is positive. We find that, in the frustrated region, the Haldane state appears as the ground state even when the Ising character of rung interactions is strong. This appearance of the Haldane phase is contrary to the ordinary situation, and it is called the inversion phenomenon concerning the interaction anisotropy. We also find that an incommensurate state becomes the ground state in a portion of the Haldane phase region.
A general technique of exact calculation of any correlation functions for the special class of one-dimensional spin models containing small clusters of quantum spins assembled to a chain by alternating with the single Ising spins is proposed. The technique is a natural generalization of that in the models solved by a classical transfer matrix. The general expressions for corresponding matrix operators which are the key components of the technique are obtained. As it is clear from the general principles, the decay of the correlation functions of various types is explicitly shown to be governed by a single correlation length. The technique is illustrated by two examples: symmetric diamond chain and asymmetric sawtooth chain.
Tl2Mn2O7 exhibits important differences with other colossal magnetoresistance (CMR) compounds, like the Mn-perovskites, in its crystal structure and electronic properties, indicating the possibility of different mechanisms for CMR being present. The larger experimental background now existent, has received diverse interpretations. We aim to contribute to the understanding of the properties of Tl2Mn2O7 through the study of a generic model for the compound, including Hund and superexchange couplings as well as hybridization effects. It includes two kinds of electronic orbitals, as widely believed to be present: one, directly related to magnetism, involving localized Mn magnetic moments, and a narrow band strongly Hund-coupled to them. Also, more extended electronic orbitals, related to the carriers in Tl2Mn2O7, appear and hybridize with the narrow band. The possibility of a superexchange coupling between the localized spins is also allowed for. This generic model allows exploration of many of the proposals put forward by other researchers for Tl2Mn2O7. As a first approach to the problem, we study the phase diagram and electronic structure employing simplifications, for sets of parameters including previous suggestions for the compound. Furthermore, we are able to exhibit similarities with results obtained in 1997 using an intermediate valence model for Tl2Mn2O7, in particular, for the electronic structure in the ferromagnetic phase.
We prove that if $X$ is a smooth projective variety of dimension greater than 1 over a field $K$ of characteristic zero such that $\operatorname{Pic}(X_{\bar{K}}) = \mathbb{Z}$ and $X_{\bar{K}}$ is simply connected, then the natural map $\rho: \operatorname{Aut}(X) \to \operatorname{Aut}(\operatorname{Sym}^d(X))$ is an isomorphism for every $d > 0$. We also partially compute the motivic zeta function of a Severi-Brauer surface and explain some relations between the classes of Severi-Brauer varieties in the Grothendieck ring of varieties.
Ultraluminous infrared galaxies (ULIRGs) represent a critical stage in the merger-driven evolution of galaxies when AGN activity is common and AGN feedback is expected. We present high sensitivity and large field of view intergral field spectroscopy of the ULIRG Mrk 273 using new data from the Keck Cosmic Web Imager (KWCI). The KCWI data captures the complex nuclear region and the two extended nebulae in the northeast (NE) and southwest (SW) to $\sim 20$ kpc scales. Kinematics in the nuclear region show a fast, extended, bipolar outflow in the direction of the previously reported nuclear superbubbles spanning $\sim 5$ kpc, two to three times greater than the previously reported size. The larger scale extended nebulae on $\sim 20$ kpc show fairly uniform kinematics with FWHM $\sim 300 ~\kmps$ in the SW nebula and FWHM $\sim 120 ~\kmps$ in the NE nebula. We detect for the first time high ionization [NeV]3426, [OIII]4363 and HeII4684 emission lines in the extended NE nebula. Emission line ratios in the nuclear region correlate with the kinematic structures, with the bipolar outflow and the less collimated "outflow regions" showing distinct line ratio trends. Line ratio diagnostics of high ionization emission lines reveal non-trivial contribution from shock plus precursor ionization in the NE nebula and the nuclear region, mixed with AGN photoionization. These data are highly constraining for models of cool ionized gas existing ~20 kpc from a galactic nucleus.
Recent experimental results revealed large elliptic flow of the charmed hadrons at LHC energies, unexpectedly similar to that of the charged pions. The mentioned measurements are often interpreted using transport models, which incorporate dissociation and recombination mechanisms for charm quarks. In this report, a modified version of the Monte Carlo model with string repulsion is used to calculate azimuthal correlations with charmed hadrons. The string repulsion mechanism may provide significant angular correlations and can be considered as an alternative to thermalization picture.
We present a detailed study in the paramagnetic regime of the frustrated $s$ = 1/2 spin-compound linarite, PbCuSO$_4$(OH)$_2$, with competing ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor exchange interactions. Our data reveal highly anisotropic values for the saturation field along the crystallographic main directions, with $\sim$ 7.6, $\sim$ 10.5 and $\sim$ 8.5\,T for the $a$, $b$, and $c$ axes, respectively. In the paramagnetic regime, this behavior is explained mainly by the anisotropy of the \textit{g}-factor but leaving room for an easy-axis exchange anisotropy. Within the isotropic $J_1$-$J_2$ spin model our experimental data are described by various theoretical approaches yielding values for the exchange interactions $J_1$ $\sim$ -100\,K and $J_2$ $\sim$ 36\,K. These main intrachain exchange integrals are significantly larger as compared to the values derived in two previous studies in the literature and shift the frustration ratio $\alpha = J_2/|J_1|$ $\approx$ 0.36 of linarite closer to the 1D critical point at 0.25. Electron spin resonance (ESR) and nuclear magnetic resonance (NMR) measurements further prove that the static susceptibility is dominated by the intrinsic spin susceptibility. The Knight shift as well as the broadening of the linewidth in ESR and NMR at elevated temperatures indicate a highly frustrated system with the onset of magnetic correlations far above the magnetic ordering temperature $T_\mathrm{N}$ = 2.75(5)\,K, in agreement with the calculated exchange constants.
For a fixed graph $F,$ the minimum number of edges in an edge-maximal $F$-free subgraph of $G$ is called the $F$-saturation number. The asymptotics of the $F$-saturation number of the binomial random graph $G(n,p)$ for constant $p\in(0,1)$ is known for complete graphs $F=K_m$ and stars $F=K_{1,m}.$ This paper is devoted to the case when the pattern graph $F$ is a simple cycle $C_m.$ We prove that, for $m\geqslant 5,$ whp $\mathrm{sat}\left(G\left(n,p\right),C_m\right) = n+\Theta\left(\frac{n}{\ln n}\right).$ Also we find $c=c(p)$ such that whp $\frac{3}{2}n(1+o(1))\leqslant\mathrm{sat}\left(G\left(n,p\right),C_4\right)\leqslant cn(1+o(1)).$ In particular, whp $\mathrm{sat}\left(G\left(n,\frac{1}{2}\right),C_4\right)\leqslant\frac{27}{14}n(1+o(1)).$
We present universal factorization formulas describing the behavior of one-loop QCD amplitudes as external momenta become either soft or collinear. Our results are valid to all orders in the dimensional regularization parameter, $\eps$. Terms through $\Ord(\eps^2)$ can contribute in infrared divergent phase space integrals associated with next-to-next-to-leading order jet cross-sections.
The present work is concerned with existence of positive solutions for a class of fractional equation involving a Kirchhoff term and singular potential.