ShantanuT01/DACTYL-Pretraining huggingface dataset:
We develop in this article a microscopic version of the successful phenomenological hydrodynamic Bohr-Davydov-Faessler-Greiner (BDFG) model for the collective rotation-vibration motion of a deformed nucleus. The model derivation is not limited to small oscillation amplitudes. The model generalizes the author's previous model to include interaction between collective oscillations in each pair of spatial directions, and to remove many of the previous-model approximations. To derive the model, the nuclear Schrodinger equation is canonically transformed to collective coordinates and then linearized using a constrained variational method. The associated transformation constraints are imposed on the wavefunction and not on the particle co-ordinates. This approach yields four self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. To facilitate comparison with the BDFG model, simplify the solution of the equations, and gain physical insight, we restrict in this article the collective oscillations to only two space dimensions. For harmonic oscillator mean-field potentials, the equations are then solved in closed forms and applied to the ground-state rotational bands in some even-even light and rare-earth nuclei. The computed ground-state rotational band excitation energy, quadrupole moment and electric quadrupole transition probabilities are found to agree favourably with measured data and the results from mean-field, Sp(3,R), and SU(3) models.
Various large-scale processes induced by triaxial potentials and able to alter stellar and gaseous abundance profiles are reviewed. In particular, strong bars can quickly and efficiently blend stars through chaotic mixing, and entail intricate inflows/outflows of gas. Bar-generated abundance features include flattenings, breaks, and plateaus in radial gradients as well as box- or peanut-like morphologies.
This article deals with the starting and stopping problem under Knightian uncertainty, i.e., roughly speaking, when the probability under which the future evolves is not exactly known. We show that the lower price of a plant submitted to the decisions of starting and stopping is given by a solution of a system of two reflected backward stochastic differential equations (BSDEs for short). We solve this latter system and we give the expression of the optimal strategy. Further we consider a more general system of $m$ ($m\geq 2$) reflected BSDEs with interconnected obstacles. Once more we show existence and uniqueness of the solution of that system.
We review in detail recent advances in our understanding of the phase structure and the phase transitions of hadronic matter in strong magnetic fields $B$ and zero quark chemical potentials $\mu_f$. Many aspects of QCD are described using low-energy effective theories and models such as the MIT bag model, the hadron resonance gas model, chiral perturbation theory, the Nambu-Jona-Lasinio (NJL) model, the quark-meson (QM) model and Polyakov-loop extended versions of the NJL and QM models. We critically examine their properties and applications. This includes mean-field calculations as well as approaches beyond the mean-field approximation such as the functional renormalization group (FRG). Renormalization issues are discussed and the influence of the vacuum fluctuations on the chiral phase transition is pointed out. Magnetic catalysis at $T=0$ is covered as well. We discuss recent lattice results for the thermodynamics of nonabelian gauge theories with emphasis on $SU(2)_c$ and $SU(3)_c$. In particular, we focus on inverse magnetic catalysis around the transition temperature $T_c$ as a competition between contributions from valence quarks and sea quarks resulting in a decrease of $T_c$ as a function of $B$. Finally, we discuss recent efforts to modify models in order to reproduce the behavior observed on the lattice.
We criticize the Hameroff Penrose model in the context of quantum brain model by gravitational collapse orchestrated objective reduction, orch. OR, assumed by Penrose, and we propose instead that the decoherence process is caused by interaction with the environment. We consider it useful to exploit this possibility because of the growing importance of decoherence theory in quantum measurement, and also because quantum mechanics can be applied to brain study independently of the Hameroff Penrose model for mind and consciousness. Our conclusion is that the Hameroff Penrose model is not compatible with decoherence, but nevertheless quantum brain can still be considered if we replace gravitational collapse orch .OR with decoherence.
Context: The structure of the inner disk of Herbig Be stars is not well understood. The continuum disks of several Herbig Be stars have inner radii that are smaller than predicted by models of irradiated disks with optically thin holes.   Aims: We study the size of the inner disk of the Herbig B[e] star HD 85567 and compare the model radii with the radius suggested by the size-luminosity relation.   Methods: The object was observed with the AMBER instrument of the Very Large Telescope Interferometer. We obtained K-band visibilities and closure phases. These measurements are interpreted with geometric models and temperature-gradient models.   Results: Using several types of geometric star-disk and star-disk-halo models, we derived inner ring-fit radii in the K band that are in the range of 0.8 - 1.6 AU. Additional temperature-gradient modeling resulted in an extended disk with an inner radius of $0.67^{+0.51}_{-0.21}$ AU, a high inner temperature of $2200^{+750}_{-350}$ K, and a disk inclination of $53^{+15}_{-11}$$^\circ$.   Conclusions: The derived geometric ring-fit radii are approximately 3 - 5 times smaller than that predicted by the size-luminosity relation. The small geometric and temperature-gradient radii suggest optically thick gaseous material that absorbs stellar radiation inside the dust disk.
Lanthanum family of high-temperature cuprate superconductors is known to exhibit both spin and charge electronic modulations around doping level 1/8. We assume that these modulations have the character of two-dimensional spin-vortex checkerboard and investigate whether this assumption is consistent with the Fermi surface and the pseudogap measured by angle-resolved photo-emission spectroscopy. We also explore the possibility of observing quantum oscillations of transport coefficients in such a background. These investigations are based on a model of non-interacting spin-1/2 fermions hopping on a square lattice and coupled through spins to a magnetic field imitating spin-vortex checkerboard. The main results of this article include (i) calculation of Fermi surface containing Fermi arcs at the positions in the Brillouin zone largely consistent with experiments; (ii) identification of factors complicating the observations of quantum oscillations in the presence of spin modulations; and (iii) investigation of the symmetries of the resulting electronic energy bands, which, in particular, indicates that each band is double-degenerate and, in addition, has at least one conical point, where it touches another double-degenerate band. We discuss possible implications these cones may have for the transport properties and the pseudogap.
The HAWC Collaboration has reported the detection of an extended $\gamma$-ray emission around the Geminga and Monogem pulsars of a few degree extension. Very recently, the LHAASO Collaboration released also the data for an extended $\gamma$-ray emission around the pulsar PSR J0622+3749. This flux can be explained with electrons and positrons injected from these sources and their inverse Compton Scattering on the interstellar radiation fields. So far the size of such $\gamma-$ray halos has been interpreted as the result of the diffusion coefficient around the sources being about two orders of magnitude smaller than the average in the Galaxy. However, this conclusion is driven by the assumption that particles propagate diffusively right away after the injection without taking into account the ballistic propagation. The propagation of cosmic-ray leptons in the proximity of the Geminga, Monogem and PSR J0622+3749 pulsars is examined here considering the transition from the quasi-ballistic, valid for the most recently injected particles, to the diffusive transport regime. For typical interstellar values of the diffusion coefficient, the quasi-ballistic regime dominates the lepton distribution up to distances of a few tens of parsec from the pulsar for particle energies above $\sim 10$ TeV. In this regime the resulting $\gamma-$ray source tends to be rather compact, despite particles travel a long distance. Indeed, for larger values of the diffusion coefficient, particles propagate ballistically up to larger distances with the result of a more point-like $\gamma-$ray source. When such transition is taken into account, a good fit to the HAWC and LHAASO $\gamma-$ray data around Geminga, Monogem and PSR J0622+3749 is obtained without the need to invoke a strong suppression of the diffusion coefficient.
Given an integer $q$ and a polynomial $f\in \mathbb Z_{q}[X]$ of degree $d$ with coefficients in the residue ring $\mathbb Z_q=\mathbb Z/q\mathbb Z,$ we obtain new results concerning the number of solutions to congruences of the form $$y\equiv f(x) \pmod{q},$$ with integer variables lying in some cube $\mathcal B$ of side length $H$. Our argument uses ideas of Cilleruelo, Garaev, Ostafe and Shparlinski which reduces the problem to the Vinogradov mean value theorem and a lattice point counting problem. We treat the lattice point problem differently using transference principles from the Geometry of Numbers. We also use a variant of the main conjecture for the Vinogradov mean value theorem of Bourgain, Demeter and Guth and of Wooley which allows one to deal with rather sparse sets.
We investigated the fraction of [OII] emitters in galaxies at z~0.9 as a function of the local galaxy density in the Hubble Space Telescope (HST) COSMOS 2 square degree field. [OII] emitters are selected by the narrow-band excess technique with the NB711-band imaging data taken with Suprime-Cam on the Subaru telescope. We carefully selected 614 photo-z selected galaxies with M_U3500 < -19.31 at z=0.901-0.920, which includes 195 [OII] emitters, to directly compare results with our previous study at z~1.2. We found that the fraction is almost constant at 0.3 Mpc^-2 < Sigma_10th < 10 Mpc^-2. We also checked the fraction of galaxies with blue rest-frame colors of NUV-R < 2 in our photo-z selected sample, and found that the fraction of blue galaxies does not significantly depend on the local density. On the other hand, the semi-analytic model of galaxy formation predicted that the fraction of star-forming galaxies at z~0.9 decreases with increasing the projected galaxy density even if the effects of the projection and the photo-z error in our analysis were taken into account. The fraction of [OII] emitters decreases from ~60% at z~1.2 to ~30% at z~0.9 independent of the galaxy environment. The decrease of the [OII] emitter fraction could be explained mainly by the rapid decrease of the star formation activity in the universe from z~1.2 to z~0.9.
In this paper, we study the Cauchy problem for a generalized integrable Camassa-Holm equation with both quadratic and cubic nonlinearity. By overcoming the difficulties caused by the complicated mixed nonlinear structure, we firstly establish the local well-posedness result in Besov spaces, and then present a precise blow-up scenario for strong solutions. Furthermore, we show the existence of single peakon by the method of analysis.
We assemble 3524 quasars from Sloan Digital Sky Survey (SDSS) with repeated observations to search for variations of narrow C IV1548,1551 and Mg II2796,2803 absorption doublets in spectral regions shortward of 7000 Ang at the observed frame, which corresponds to time-scales of about 150 ~ 2643 days at quasar rest frame. In these quasar spectra, we detect 3580 C IV absorption systems with z_{abs} = 1.5188 ~ 3.5212, and 1809 Mg II absorption systems with z_{abs} = 0.3948 ~ 1.7167. In term of the absorber velocity (beta) distribution at quasar rest frame, we find a substantial number of C IV absorbers with beta<0.06, which might be connected to the absorptions of quasar outflows. The outflow absorptions peak at v~2000 km/s and drop rapidly below the peak value. Among 3580 C IV absorption systems, 52 systems (~ 1.5%) show obvious variations in equivalent widths at the absorber rest frame (Wr): 16 enhanced, 16 emerged, 12 weaken, and 8 disappeared systems, respectively. We find that changes in Wr548 are neither related to time-scales of the two SDSS observations, nor to absorber velocities at the quasar rest frame. Variable absorptions in low-ionization species are important to constraint the physical conditions of absorbing gas. There are two variable Mg II absorption systems measured from SDSS spectra detected by Hacker et al. However, in our Mg II$ absorption sample, we find that neither shows variable absorption with confident levels of >4sigma for lambda2796 lines and >3sigma for lambda2803 lines.
To study the Reynolds stresses which describe turbulent momentum transport from turbulence affected by large-scale shear and rotation. Three-dimensional numerical simulations are used to study turbulent transport under the influences of large-scale shear and rotation in homogeneous, isotropically forced turbulence. We study three cases: one with only shear, and two others where in addition to shear, rotation is present. These cases differ by the angle (0 or 90\degr) the rotation vector makes with respect to the z-direction. Two subsets of runs are performed with both values of \theta where either rotation or shear is kept constant. When only shear is present, the off-diagonal stress can be described by turbulent viscosity whereas if the system also rotates, nondiffusive contributions (\Lambda-effect) to the stress can arise. Comparison of the direct simulations are made with analytical results from a simple closure model. We find that the turbulent viscosity is of the order of the first order smoothing result in the parameter regime studied and that for sufficiently large Reynolds numbers the Strouhal number, describing the ratio of correlation to turnover times, is roughly 1.5. This is consistent with the closure model based on the minimal tau-approximation which produces a reasonable fit to the simulation data for similar Strouhal numbers. In the cases where rotation is present, separating the diffusive and nondiffusive components of the stress turns out to be challenging but taking the results at face value, we can obtain nondiffusive contributions of the order of 0.1 times the turbulent viscosity. We also find that the simple closure model is able to reproduce most of the qualitative features of the numerical results provided that the Strouhal number is of the order of unity.
Spectral signatures of surface spots were recently discovered from high cadence observations of the A star Vega. We aim at constraining the surface distribution of these photospheric inhomogeneities, and investigating a possible short term evolution of the spot pattern. Using data collected over five consecutive nights, we employ the Doppler Imaging method to reconstruct three different maps of the stellar surface, from three consecutive subsets of the whole time-series. The surface maps display a complex distribution of dark and bright spots, covering most of the visible fraction of the stellar surface. A number of surface features are consistently recovered in all three maps, but other features seem to evolve over the time span of observations, suggesting that fast changes can affect the surface of Vega within a few days at most. The short-term evolution is observed as emergence or disappearance of individual spots, and may also show up as zonal flows, with low-latitude and high latitude belts rotating faster than intermediate latitudes. It is tempting to relate the surface brightness activity to the complex magnetic field topology previously reconstructed for Vega, although strictly simultaneous brightness and magnetic maps will be necessary to assess this potential link.
Solar eruptions are explosive release of coronal magnetic field energy as manifested in solar flares and coronal mass ejection. Observations have shown that the core of eruption-productive regions are often a sheared magnetic arcade, i.e., a single bipolar configuration, and, particularly, the corresponding magnetic polarities at the photosphere are elongated along a strong-gradient polarity inversion line (PIL). It remains unclear what mechanism triggers the eruption in a single bipolar field and why the one with a strong PIL is eruption-productive. Recently, using high accuracy simulations, we have established a fundamental mechanism of solar eruption initiation that a bipolar field as driven by quasi-static shearing motion at the photosphere can form an internal current sheet, and then fast magnetic reconnection triggers and drives the eruption. Here we investigate the behavior of the fundamental mechanism with different photospheric magnetic flux distributions, i.e., magnetograms, by combining theoretical analysis and numerical simulation. Our study shows that the bipolar fields of different magnetograms, as sheared continually, all exhibit similar evolutions from the slow storage to fast release of magnetic energy in accordance with the fundamental mechanism, which demonstrates the robustness of the mechanism. We further found that the magnetograms with stronger PIL produce larger eruptions, and the key reason is that the sheared bipolar fields with stronger PIL can achieve more non-potentiality, and their internal current sheet can form at a lower height and with a larger current density, by which the reconnection can be more efficient. This also provides a viable trigger mechanism for the observed eruptions in active region with strong PIL.
In a recent paper, T. Austin has proved an analogous theorem for the continuous torus of the original Junta theorem proved by Friedgut in the case of the Boolean cube. Analogous statements have been established recently in discrete cases such as the discrete Tori by Ellis et.al., and in the case of slices of the Boolean cube by Wimmer and Filmus. In the continuous case, through the notion of geometric influences, a statement has also been established by Keller, Mossel and Sen for Boltzmann probability measures. In this article, we broaden the scope of the arguments of T. Austin to get an unified proof of these results, removing the restriction to Boolean functions. Indeed, the proof of T. Austin relies on semigroup arguments and can be performed in a general framework that covers both Cayley or Schreier graphs or product of log-concave probability measures.
We study the typical behavior of the harmonic measure of balls in large critical Galton-Watson trees whose offspring distribution has finite variance. The harmonic measure considered here refers to the hitting distribution of height $n$ by simple random walk on a critical Galton-Watson tree conditioned to have height greater than $n$. We prove that, with high probability, the mass of the harmonic measure carried by a random vertex uniformly chosen from height $n$ is approximately equal to $n^{-\lambda}$, where the constant $\lambda>1$ does not depend on the offspring distribution. This universal constant $\lambda$ is equal to the first moment of the asymptotic distribution of the conductance of size-biased Galton-Watson trees minus 1.
We start by providing an explicit characterization and analytical properties, including the persistence phenomena, of the distribution of the extinction time $\mathbb{T}$ of a class of non-Markovian self-similar stochastic processes with two-sided jumps that we introduce as a stochastic time-change of Markovian self-similar processes. For a suitably chosen time-changed, we observe, for classes with two-sided jumps, the following surprising facts. On the one hand, all the $\mathbb{T}$'s within a class have the same law which we identify in a simple form for all classes and reduces, in the spectrally positive case, to the Fr\'echet distribution. On the other hand, each of its distribution corresponds to the law of an extinction time of a single Markov process without positive jumps, leaving the interpretation that the time-changed has annihilated the effect of positive jumps. The example of the non-Markovian processes associated to L\'evy stable processes is detailed.
We extend the analysis of Bok et al. (2020) in which the HI content of isolated galaxies from the AMIGA sample and selected paired galaxies from ALFALFA were examined as a potential driver of galaxy location on the WISE mid-infrared SFR-Mstar sequence. By further characterizing the isolated and pair galaxy samples, i.e. in terms of optical galaxy morphology, a more detailed and quantitative description of local galaxy environment by way of the local number density (eta) and tidal strength (Q) parameters, star formation efficiency (SFE(HI)), and HI integrated profile asymmetries, we present plausible pathways for the broadening of the pair sample HI deficiency distribution towards both high and low deficiencies compared to the narrower isolated galaxy sample distribution (i.e. sigma_pairs = 0.34 versus sigma_AMIGA = 0.28). We associate the gas-rich tail of the pair deficiency distribution with the highest Q values, large profile asymmetries, and low SFEs. From this we infer that merger activity is enhancing gas supplies, as well as disrupting the efficiency of star formation, via strong gravitational torques. The gas-poor wing of the deficiency distribution appears to be populated with galaxies in denser environments (with larger eta values on average), more akin to groups. Despite our gas-rich selection criterion, there is a small population of early-type galaxies in the pair sample, which primarily fall in the positive deficiency wing of the distribution. These results suggest that a combination of a denser galaxy environment, early-type morphology, and higher stellar mass, is contributing to the broadening of the deficiency distribution towards larger deficiencies.
In this review we present our model which is an example of the self consistent approach that incorporates our theoretical understanding of long distance physics, based both on N=4 SYM for strong coupling and on the matching with the perturbative QCD approach. We demonstrate how important and decisive the LHC data were on strong interactions which led us to a set of the phenomenological parameters that fully confirmed our theoretical expectations, and produced a new picture of the strong interaction at high energy. We also show how far we have come towards creating a framework for the description of minimal bias events for high energy scattering without generating Monte Carlo codes.
The purpose of the present paper is to establish moment estimates of Rosenthal type for a rather general class of random variables satisfying certain bounds on the cumulants. We consider sequences of random variables which satisfy a central limit theorem and estimate the speed of convergence of the corresponding moments to the moments of a standard normally distributed variable. The examples of random objects we discuss include those where a dependency graphs or a weighted dependency graph encodes the dependency structure. We give applications to subgraph-counting statistics in Erd\H{o}s-R\'enyi random graphs of type $G(n,p)$ and $G(n,m)$, crossings in uniform random pair partitions and spins in the $d$-dimensional Ising model. Moreover, we prove moment estimates for certain statistics appearing in random matrix theory, namely characteristic polynomials of random unitary matrices as well as the determinants of certain random matrix ensembles. We add estimates for the $p(n)$-dimensional volume of the simplex with $p(n)+1$ points in ${\mathbb R}^n$ distributed according to special distributions, since it is strongly connected to Gram matrix ensembles.