ShantanuT01/DACTYL-Pretraining huggingface dataset:
A typical working condition in the study of quantum quenches is that the initial state produces a distribution of quasiparticle excitations with an opposite-momentum-pair structure. In this work we investigate the dynamical and stationary properties of the entanglement entropy after a quench from initial states which do not have such structure: instead of pairs of excitations they generate $\nu$-plets of correlated excitations with $\nu>2$. Our study is carried out focusing on a system of non-interacting fermions on the lattice. We study the time evolution of the entanglement entropy showing that the standard semiclassical formula is not applicable. We propose a suitable generalisation which correctly describes the entanglement entropy evolution and perfectly matches numerical data. We finally consider the relation between the thermodynamic entropy of the stationary state and the diagonal entropy, showing that when there is no pair structure their ratio depends on the details of the initial state and lies generically between $1/2$ and $1$.
We present Monte Carlo results for the two-species trapping reaction $A+B \to B$ with diffusing $A$ and $B$ on lattices in one, two and three dimension. We use a novel algorithm which permits to simulate survival probabilities of $A$ partic les down to $<10^{-30}$ with high accuracy. The results for the survival probability agree much better with the exact asymptotic predictions of Bramson and Lebowitz (Phys. Rev. Lett. {\bf 61}, 2397 (1988)) than with the heuristics of Kang and Redner (J. Phys. A {\bf 17}, L451 (1984)). But there are very large deviations from either which show that even these simulations are far from asymptotia. This is supported by the rms. displacement of $A$ particles which clearly show that the asymptotic regime has not been reached, at least for $d=2$ and $d=3$.
The zero temperature transport properties of two-dimensional lattice systems with static random magnetic flux per plaquette and zero mean are investigated numerically. We study the two-terminal conductance and its dependence on energy, sample size, and magnetic flux strength. The influence of boundary conditions and of the oddness of the number of sites in the transverse direction is also studied. We confirm the existence of a critical chiral state in the middle of the energy band and calculate the critical exponent nu=0.35 +/- 0.03 for the divergence of the localization length. The sample averaged scale independent critical conductance <g>_c turns out to be a function of the amplitude of the flux fluctuations whereas the variance of the respective conductance distributions appears to be universal. All electronic states outside of the band center are found to be localized.
We use hydrodynamic simulations to study the effect of spiral arms on the star formation rate (SFR) occurring in nuclear rings of barred-spiral galaxies. We find that spiral arms can be an efficient means of gas transport from the outskirts to the central parts, provided that the arms are rotating slower than the bar. While the ring star formation in models with no-arm or corotating arms is active only during about the bar growth phase, arm-driven gas accretion makes the ring star formation both enhanced and prolonged significantly in models with slow-rotating arms. The arm-enhanced SFR is larger by a factor of ~ 3-20 than in the no-arm model, with larger values corresponding to stronger and slower arms. Arm-induced mass inflows also make dust lanes stronger. Nuclear rings in slow-arm models are ~ 45% larger than in the no-arm counterparts. Star clusters that form in a nuclear ring exhibit an age gradient in the azimuthal direction only when the SFR is small, whereas no noticeable age gradient is found in the radial direction for models with arm-induced star formation.
We consider the regularity of stationary solutions to the linearized Boltzmann equations in bounded $C^1$ convex domains in $\mathbb{R}^3$ for gases with cutoff hard potential and cutoff Maxwellian gases. We prove that the stationary solutions solutions are H\"{o}lder continuous with order $\frac1{2}^-$ away from the boundary provided the incoming data have the same regularity. The key idea is to partially transfer the regularity in velocity obtained by collision to space through transport and collision.
Kepler ultra-high precision photometry of long and continuous observations provides a unique dataset in which surface rotation and variability can be studied for thousands of stars. Because many of these old field stars also have independently measured asteroseismic ages, measurements of rotation and activity are particularly interesting in the context of age-rotation-activity relations. In particular, age-rotation relations generally lack good calibrators at old ages, a problem that this Kepler sample of old-field stars is uniquely suited to address. We study the surface rotation and photometric magnetic activity of a subset of 540 solar-like stars on the main- sequence and the subgiant branch for which stellar pulsations have been measured. The rotation period was determined by comparing the results from two different analysis methods: i) the projection onto the frequency domain of the time-period analysis, and ii) the autocorrelation function (ACF) of the light curves. Reliable surface rotation rates were then extracted by comparing the results from two different sets of calibrated data and from the two complementary analyses. We report rotation periods for 310 out of 540 targets (excluding known binaries and candidate planet-host stars); our measurements span a range of 1 to 100 days. The photometric magnetic activity levels of these stars were computed, and for 61.5% of the dwarfs, this level is similar to the range, from minimum to maximum, of the solar magnetic activity. We demonstrate that hot dwarfs, cool dwarfs, and subgiants have very different rotation-age relationships, highlighting the importance of separating out distinct populations when interpreting stellar rotation periods. Our sample of cool dwarf stars with age and metallicity data of the highest quality is consistent with gyrochronology relations reported in the literature.
We study the statistics of thermal energy transfer in the nonequilibrium (two-bath) spin-boson model. This quantum many-body impurity system serves as a canonical model for quantum energy transport. Our method makes use of the Majorana fermion representation for the spin operators, in combination with the Keldysh nonequilibrium Green's function approach. We derive an analytical expression for the cumulant generating function of the model in the steady state limit, and show that it satisfies the Gallavotti-Cohen fluctuation symmetry. We obtain analytical expressions for the heat current and its noise, valid beyond the sequential and the co-tunnelling regimes. Our results satisfy the quantum mechanical bound for heat current in interacting nanojunctions. Results are compared with other approximate theories, as well as with a non-interacting model, a fully harmonic thermal junction.
We study the scenario where a sneutrino is the next lightest supersymmetric particle (NLSP) and decays into a gravitino and standard model particles. The daughter particles such as neutrinos and quarks cause electro- and hadronic showers and affect big-bang nucleosynthesis. It is found that despite a small branching ratio, four-body processes including quarks in the final state give the most stringent constraint on the sneutrino abundance for gravitino mass of 1 $-$ 100 GeV. Pion production by high energy neutrinos is important when the sneutrinos decay at $\sim$ 1 sec. We also discuss the thermal leptogenesis in the sneutrino NLSP scenario.
The nature of superluminal photon propagation in the gravitational field describing radiation from a time-dependent, isolated source (the Bondi-Sachs metric) is considered in an effective theory which includes interactions which violate the strong equivalence principle. Such interactions are, for example, generated by vacuum polarisation in conventional QED in curved spacetime. The relation of the resulting light-cone modifications to the Peeling Theorem for the Bondi-Sachs spacetime is explained.
We have made a clear detection of excess power, providing strong evidence for solar-like oscillations in the G2 subgiant beta Hyi. We observed this star over five nights with the UCLES echelle spectrograph on the 3.9-m Anglo-Australian Telescope, using an iodine absorption cell as a velocity reference. The time series of 1196 velocity measurements shows an rms scatter of 3.30 m/s, and the mean noise level in the amplitude spectrum at frequencies above 0.5 mHz is 0.11 m/s. We see a clear excess of power centred at 1.0 mHz, with peak amplitudes of about 0.5 m/s, in agreement with expectations for this star. Fitting the asymptotic relation to the power spectrum indicates the most likely value for the large separation is 56.2 microHz, also in good agreement with the known properties of beta Hyi.
In this paper, we consider a class of models for multiphase fluids, in the framework of mixture theory. The considered system, in its more general form, contains both the gradient of a hydrostatic pressure, generated by an incompressibility constraint, and the gradient of a compressible pressure depending on the volume fractions of some of the different phases. To approach these systems, we define an approximation based on the \emph{Leray} projection, which involves the use of the \emph{Lax} symbolic symmetrizer for hyperbolic systems and paradifferential techniques. In two space dimensions, we prove its well-posedness and convergence to the unique classical solution to the original system. In the last part, we shortly discuss the difficulties in the three dimensional case.
The de-excitation of compound nuclei has been successfully described for several decades by means of statistical models. However, accurate predictions require some fine-tuning of the model parameters. This task can be simplified by studying several entrance channels, which populate different regions of the parameter space of the compound nucleus.   Fusion reactions play an important role in this strategy because they minimise the uncertainty on the entrance channel by fixing mass, charge and excitation energy of the compound nucleus. If incomplete fusion is negligible, the only uncertainty on the compound nucleus comes from the spin distribution. However, some de-excitation channels, such as fission, are quite sensitive to spin. Other entrance channels can then be used to discriminate between equivalent parameter sets.   The focus of this work is on fission and intermediate-mass-fragment emission cross sections of compound nuclei with 70<=A<=240. The statistical de-excitation model is GEMINI++. The choice of the observables is natural in the framework of GEMINI++, which describes fragment emission using a fission-like formalism. Equivalent parameter sets for fusion reactions can be resolved using the spallation entrance channel. This promising strategy can lead to the identification of a minimal set of physical ingredients necessary for a unified quantitative description of nuclear de-excitation.
Skew convolution semigroups play an important role in the study of generalized Mehler semigroups and Ornstein-Uhlenbeck processes. We give a characterization for a general skew convolution semigroup on real separable Hilbert space whose characteristic functional is not necessarily differentiable at the initial time. A connection between this subject and catalytic branching superprocesses is established through fluctuation limits, providing a rich class of non-differentiable skew convolution semigroups. Path regularity of the corresponding generalized Ornstein-Uhlenbeck processes in different topologies is also discussed.
Within a relativistic quantum formalism we examine the role of second-order corrections caused by the application of magnetic fields in two-dimensional topological and Chern insulators. This allows to reach analytical expressions for the change of the Berry curvature, orbital magnetic moment, density of states and energy determining their canonical grand potential and transport properties. The present corrections, which become relevant at relatively low fields due to the small gap characterizing these systems, unveil a zero-field diamagnetic susceptibility which can be tuned by the external magnetic field.
We study the changes in the Fermi surface with electron doping in the LaFeAsO$_{1-x}$F$_x$ superconductors with density-functional supercell calculations using the linearized augmented planewave (LAPW) method. The supercell calculations with explicit F substitution are compared with those obtained from the virtual crystal approximation (VCA) and from a simple rigid band shift. We find significant differences between the supercell results and those obtained from the rigid-band shift with electron doping, although quite remarkably the supercell results are in good agreement with the virtual crystal approximation (VCA) where the nuclear charges of the O atoms are slightly increased to mimic the addition of the extra electrons. With electron doping, the two cylindrical hole pockets along $\Gamma-Z$ shrink in size, and the third hole pocket around $Z$ disappears for an electron doping concentration in excess of about 7-8%, while the two elliptical electron cylinders along $M-A$ expand in size. The spin-orbit coupling does not affect the Fermi surface much except to somewhat reduce the size of the third hole pocket in the undoped case. We find that with the addition of the electrons the antiferromagnetic state becomes energetically less stable as compared to the nonmagnetic state, indicating that the electron doping may provide an extra degree of stability to the formation of the superconducting ground state.
Periodic outbursts are observed in several changing-look (CL) active galactic nuclei (AGNs). \citet{sniegowska_possible_2020} suggested a model to explain the repeating CL in these AGNs, where the periodic outbursts are triggered in a narrow unstable zone between an inner ADAF and outer thin disk. In this work, we intend to investigate the effects of large-scale magnetic fields on the limit cycle behaviors of CL AGNs. The winds driven by magnetic fields can significantly change the structure of thin disk by taking away the angular momentum and energy of the disk. It is found that the period of outburst in repeating CL AGNs can be substantially reduced by the magnetic fields. Conversely, if we keep the period unchanged, the outburst intensity can be raised for several times. These results can help to explain the observational properties of multiple CL AGNs. Besides the magnetic fields, the effects of transition radius $R_{\rm tr}$, the width of transition zone $\Delta R$ and Shakura-Sunyaev parameter $\alpha$ are also explored in this work.
This paper was written in 1982. Ideas and methods of "Clemens C.H., Griffiths Ph. The intermediate Jacobian of a cubic threefold" are applied to a Fano threefold X of genus 6 -- intersection of Grassmann sixfold with two hyperplanes and a quadric. We prove:   1. The Fano surface F(X) of X is smooth and irreducible. Hodge numbers and some other invariants of F(X) are calculated.   2. Tangent bundle theorem for X, and its geometric interpretation. It is shown that F(X) defines X uniquely.   3. The Abel - Jacobi map from the Albanese of F(X) to the middle Jacobian of X is an isogeny.
We present a version of relative locality based on the geometry of twistor space. This can also be thought of as a new kind of deformation of twistor theory based on the construction of a bundle of twistor spaces over momentum space. Locality in space-time is emergent and is deformed in a precise way when a connection on that bundle is non-flat. This gives a precise and controlled meaning to Penrose's hypothesis that quantum gravity effects will deform twistor space in such a way as to maintain causality and relativistic invariance while weakening the notion that interactions take place at points in spacetime.
Light strongly interacting supersymmetric particles may be treated as partonic constituents of nucleons in high energy scattering processes. We construct parton distribution functions for protons in which a light gluino is included along with standard model quark, antiquark, and gluon constituents. A global analysis is performed of a large set of data from deep-inelastic lepton scattering, massive lepton pair and vector boson production, and hadron jet production at large values of transverse momentum. Constraints are obtained on the allowed range of gluino mass as a function of the value of the strong coupling strength alpha_s(M_Z) determined at the scale of the Z boson mass. We find that gluino masses as small as 10 GeV are admissible provided that alpha_s(M_Z) \ge 0.12. Current hadron scattering data are insensitive to the presence of gluinos heavier than ~ 100 - 150 GeV.
Let $X$ be a quasi-compact algebraic stack with quasi-finite and separated diagonal. We classify the thick $\otimes$-ideals of $\mathsf{D}_{\mathrm{qc}}(X)^c$. If $X$ is tame, then we also compute the Balmer spectrum of the $\otimes$-triangulated category of perfect complexes on $X$. In addition, if $X$ admits a coarse space $X_{\mathrm{cs}}$, then we prove that the Balmer spectra of $X$ and $X_{\mathrm{cs}}$ are naturally isomorphic.
In this paper we study the inverse of so-called unfair permutations, and explore various properties of them. Our investigation begins with comparing this class of permutations with uniformly random permutations, and showing that they behave very much alike for locally dependent random variables. As an example of a globally dependent statistic we use the number of inversions, and show that this statistic satisfies a central limit theorem after proper centering and scaling. A secondary example of a globally dependent statistic to be studied will be the number of fixed points. Finally, we introduce two different generalizations of inverse-unfair permutations.
In the context of the effective field theory of dark energy (EFT) we perform agnostic explorations of Horndeski gravity. We choose two parametrizations for the free EFT functions, namely a power law and a dark energy density-like behaviour on a non trivial Chevallier-Polarski-Linder background. We restrict our analysis to those EFT functions which do not modify the speed of propagation of gravitational waves. Among those, we prove that one specific function cannot be constrained by data, since its contribution to the observables is below the cosmic variance, although we show it has a relevant role in defining the viable parameter space. We place constraints on the parameters of these models combining measurements from present day cosmological datasets and we prove that the next generation galaxy surveys can improve such constraints by one order of magnitude. We then verify the validity of the quasi-static limit within the sound horizon of the dark field, by looking at the phenomenological functions $\mu$ and $\Sigma$, associated respectively to clustering and lensing potentials. Furthermore, we notice up to $5\%$ deviations in $\mu, \Sigma$ with respect to General Relativity at scales smaller than the Compton one. For the chosen parametrizations and in the quasi-static limit, future constraints on $\mu$ and $\Sigma$ can reach the $1\%$ level and will allow us to discriminate between certain models at more than $3\sigma$, provided the present best-fit values remain.
Tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH) emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda) introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking's periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.
We report the detection of six discrete, low-luminosity (Lx < 10^33 erg/s) X-ray sources, located within 12 arcsec of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ksec Chandra ACIS-S exposure. Three sources lie within the very small upper limit of 1.9 arcsec on the core radius. The brightest of the three core sources has a luminosity of Lx (0.5-6 keV) = 6x10^32 erg/s and a blackbody-like soft X-ray spectrum, which are both consistent with it being a quiescent low-mass X-ray binary (qLMXB). We have identified optical counterparts to four of the six central sources and a number of the outlying sources, using deep Hubble Space Telescope and ground-based imaging. While the two proposed counterparts that lie within the core may represent chance superpositions, the two identified central sources that lie outside of the core have X-ray and optical properties consistent with being CVs. Two additional sources outside of the core have possible active binary counterparts. We discuss the X-ray source population of M30 in light of its collapsed-core status.
Virial mass is used as an estimator for the mass of a dark matter halo. However, the commonly used constant overdensity criterion does not reflect the dynamical structure of haloes. Here we analyze dark matter cosmological simulations in order to obtain properties of haloes of different masses focusing on the size of the region with zero mean radial velocity. Dark matter inside this region is stationary, and thus the mass of this region is a much better approximation for the virial mass.
We use the computer algebra system Magma to study graded rings of Fano 3-folds of index >=3 in terms of their Hilbert series.
We present measurements of the angular correlation function of galaxies selected from the first field of the H-ATLAS survey. Careful removal of the background from galactic cirrus is essential, and currently dominates the uncertainty in our measurements. For our 250 micron-selected sample we detect no significant clustering, consistent with the expectation that the 250 micron-selected sources are mostly normal galaxies at z<~ 1. For our 350 micron and 500 micron-selected samples we detect relatively strong clustering with correlation amplitudes A of 0.2 and 1.2 at 1', but with relatively large uncertainties. For samples which preferentially select high redshift galaxies at z~2-3 we detect significant strong clustering, leading to an estimate of r_0 ~ 7-11 h^{-1} Mpc. The slope of our clustering measurements is very steep, delta~2. The measurements are consistent with the idea that sub-mm sources consist of a low redshift population of normal galaxies and a high redshift population of highly clustered star-bursting galaxies.