ShantanuT01/DACTYL-Pretraining huggingface dataset:
Particle and photon production is analyzed in the presence of transverse flow using two approximations to describe the properties of the hadronic medium, one containing only $\pi, \rho, \omega$, and $\eta$ mesons (simplified equation of state) and the other containing hadrons and resonances from the particle data table. Both are considered with and without initial quark gluon plasma formation. In each case the initial temperature is fixed by requiring $dN_{ch}/dy \sim$ 550 in the final state. It is shown that most observables are very sensitive to the equation of state. This is particularly evident when comparing the results of the simplified equation of state in the scenarios with and without phase transition. The hadronic gas scenario leads to a substantially higher rate for the $p_T$-distribution of all particles. In the complete equation of state with several hundreds of hadronic resonances, the difference between the scenarios with and without phase transition is rather modest. Both photon and particle spectra, in a wide $p_T$ range, show very similar behavior. It is therefore concluded that from the $p_T$ spectra it will be hard to disentangle quark gluon plasma formation in the initial state. It is to be stressed however, that there are conceptual difficulties in applying a pure hadronic gas equation of state at SPS-energies. The phase transition scenario with a quark gluon plasma present in the initial state seems to be the more natural one.
Recent development in the reconstruction of the large-scale structure (LSS) has seen significant improvement in restoring the linear baryonic acoustic oscillation (BAO) from at least the non-linear matter field. This outstanding performance is achieved by iteratively solving the Monge-Ampere equation of the mass conservation. However, this technique also relies on several assumptions that are not valid in reality, namely the longitudinal displacement, the absence of shell-crossing and homogeneous initial condition. In particular, the conservation equation of the tracers comprises the biasing information that breaks down the last assumption. Consequently, direct reconstruction would entangle the non-linear displacement with complicated bias parameters and further affect the BAO. In this paper, we formulate a theoretical model describing the reconstructed biased map by matching the tracer overdensity with an auxiliary fluid with vanishing initial perturbation. Regarding the performance of the reconstruction algorithm, we show that even though the shot noise is still the most significant limiting factors in a realistic survey, inappropriate treatment of the bias could also shift the reconstructed frame and therefore broaden the BAO peak. We suggest that, in principle, this bias-related BAO smearing effect could be used to independently self-calibrate the bias parameters.
Flares and coronal mass ejections are powered by magnetic energy stored in coronal electric currents. Here, we explore the nature of coronal currents in observed and model active region (ARs) by studying manifestations of these currents in photospheric vector magnetograms. We employ Gauss's separation method, recently introduced to the solar physics literature, to partition the photospheric field into three distinct components, each arising from a separate source: (i) currents passing through the photosphere, (ii) currents flowing below it, and (iii) currents flowing above it. We refer to component (iii) as the photospheric imprint of coronal currents. In both AR 10930 and AR 11158, photospheric imprints exhibit large-scale, spatially coherent structures along these regions' central, sheared polarity inversion lines (PILs) that are consistent with coronal currents flowing horizontally above these PILs, similar to recent findings in AR 12673 by Schuck et al. (2022). We find similar photospheric imprints in a simple model of a non-potential AR with known currents. We find that flare-associated changes in photospheric imprints in AR 11158 accord with earlier reports that near-PIL fields become more horizontal, consistent with the "implosion" scenario. We hypothesize that this evolution effectively shortens, in an overall sense, current-carrying coronal fields, leading to decreased inductive energy (DIE) in the coronal field. We further hypothesize that, in the hours prior to flares, parts of the coronal field slowly expand, in a process we deem coronal inflation (CI) -- essentially, the inverse of the implosion process. Both of these hypotheses are testable with non-potential coronal field extrapolations.
The X-ray flares have usually been ascribed to long-lasting activities of the central engine of gamma-ray bursts (GRBs), e.g., fallback accretion. The GRB X-ray plateaus, however, favor a millisecond magnetar central engine. The fallback accretion can be significantly suppressed due to the propeller effect of a magnetar. Therefore, if the propeller regime cannot resist the mass flow onto the surface of the magnetar efficiently, the X-ray flares raise upon the magnetar plateau would be hinted. In this work, such peculiar cases are connected to the accretion process of a magnetar, and an implication for magnetar-disc structure is given. We investigate the repeating accretion process with multi-flare GRB 050730, and give a discussion for the accreting induced variation of the magnetic field in GRB 111209A. Two or more flares exhibit in the GRB 050730, GRB 060607A, and GRB 140304A; by adopting magnetar mass $M=1.4~ M_\odot$ and radius $R=12~\rm km$, the average mass flow rates of the corresponding surrounding disk are $3.53\times 10^{-4}~M_\odot~\rm s^{-1}$, $4.23\times 10^{-4}~M_\odot~\rm s^{-1}$, and $4.33\times 10^{-4}~M_\odot~\rm s^{-1}$, and the corresponding average sizes of the magnetosphere are $5.01~\rm \times10^{6} cm$, $6.45~\rm \times10^{6} cm$, and $1.09~\rm \times10^{7} cm$, respectively. A statistic analysis that contains 8 GRBs within 12 flares shows that the total mass loading in single flare is $\sim 2\times 10^{-5}~M_{\odot}$. In the lost mass of a disk, there are about 0.1% used to feed a collimated jet.
We discuss a $\lambda\varphi^{4}+\rho\varphi^{6}$ scalar field model defined in the Euclidean section of the Schwarzschild solution of the Einstein equations in the presence of multiplicative noise. The multiplicative random noise is a model for fluctuations of the Hawking temperature. We adopt the standard procedure of averaging the noise dependent generating functional of connected correlation functions of the model. The dominant contribution to this quantity is represented by a series of the moments of the generating functional of correlation functions of the system. Positive and negative effective coupling constants appear in these integer moments. Fluctuations in the Hawking temperature are able to generate first-order phase transitions. Using the Gaussian approximation, we compute $\langle\varphi^{2}\rangle$ for arbitrary values of the strength of the noise. Due to the presence of the multiplicative noise, we show that $\langle\varphi^{2}\rangle$ near the horizon must be written as a series of the the renormalized two-point correlation functions associated to a free scalar field in Euclidean Rindler manifold.
By means of relativistic density functional theory (DFT) calculations we study electron band structure of the topological insulator (TI) Bi$_2$Se$_3$ thin films deposited on the ferromagnetic insulator (FMI) EuS substrate. In the Bi$_2$Se$_3$/EuS heterostructure, the gap opened in the spectrum of the topological state has a hybridization character and is shown to be controlled by the Bi$_2$Se$_3$ film thickness, while magnetic contribution to the gap is negligibly small. We also analyzed the effect of Eu doping on the magnetization of the Bi$_2$Se$_3$ film and demonstrated that the Eu impurity induces magnetic moments on neighboring Se and Bi atoms an order of magnitude larger than the substrate-induced moments. Recent magnetic and magneto-transport measurements in EuS/Bi$_2$Se$_3$ heterostructure are discussed.
Assuming that alpha particles are described by a scalar-isoscalar chiral invariant heavy field it is shown how chiral symmetry determines the alpha-alpha interaction at long distances unambiguously from dimensional power counting of an effective chiral Lagrangean. The leading strong contribution is given by a two pion exchange potential which turns out to be attractive and singular at the origin, hence demanding renormalization. When 8Be is treated as a resonance state a model independent correlation between the Q-factor and lifetime 1/Gamma for the decay into two alpha particles arises. For parameters compatible with potential model analyses of low energy pi-alpha scattering it is found a Breit-Wigner width Gamma = 4.3(3) eV very close to the experimental value, Gamma= 5.57 (25)eV.
The baryonic mass composition of ultrahigh energy ($\gtrsim 10^{18}$ eV) cosmic rays (UHECRs) at injection accompanied by their interactions on universal photon backgrounds during propagation directly governs the UHECR flux on the Earth. Secondary neutrinos and photons produced in these interactions serve as crucial astrophysical messengers of UHECR sources. A modeling of the latest data obtained by the Pierre Auger Observatory (PAO) suggests a mixed element composition of UHECRs with the sub-ankle spectrum being explained by a different class of sources than the super-ankle region ($> 10^{18.7}$ eV). In this work, we obtain two kinds of fit to the UHECR spectrum -- one with a single population of sources comprising of $^1$H and $^2$He, over an energy range commencing at $\approx 10^{18}$ eV -- another for a mixed composition of representative nuclei $^1$H, $^4$He, $^{14}$N and $^{28}$Si at injection, for which a fit is obtained from above $\approx 10^{18.7}$ eV. In both cases, we consider the source emissivity evolution to be a simple power-law in redshift. We test the credibility of H+He composition by varying the source properties over a wide range of values and compare the results to that obtained for H+He+N+Si composition, using the Monte Carlo simulation tool CRPropa 3. The secondary electrons and photons are propagated using the cosmic ray transport code DINT. We place limits on the source spectral index, source evolution index and cutoff rigidity of the source population in each case by fitting the UHECR spectrum. Cosmogenic neutrino fluxes can further constrain the abundance fraction and maximum source redshift in case of light nuclei injection model.
X-ray magnetic circular and linear dichroism (XMCD and XMLD) have been used to investigate the Fe magnetic response during the spin reorientation transition (SRT) in TmFeO3. These experiments are complemented with resonant magnetic diffraction experiments at the Tm M5 edge to study simultaneously the induced magnetic order in the Tm 4f shell and the behavior of the Tm orbitals through the SRT. Comparing the Fe XMLD results with neutron diffraction and magnetization measurements on the same sample indicate that the SRT has an enhanced temperature range in the near surface region. This view is supported by the resonant soft x-ray diffraction results at the Tm M5 edge. These find an induced magnetic moment on the Tm sites, which is well-described by a dipolar mean field model originating from the Fe moments. Even though such a model can describe the 4f response in the experiments, it is insufficient to describe the SRT even when considering a change in the 4f anisotropy. Moreover, the results of the Fe XMCD are indicative of a decoupling of spin canting and antiferromagnetic spin rotation in the near surface regime close to the SRT, which remains to be understood.
This is a reply to the comment by M. Kastner and M. Promberger [cond-mat/0011516] on the paper published in J. Stat. Phys. 99, 691 (2000) and also in cond-mat/0002176. We show that all their criticisms do not apply.
We present a framework dedicated to modelling the resistive switching operation of Valence Change Memory (VCM) cells. The method combines an atomistic description of the device structure, a Kinetic Monte Carlo (KMC) model for the creation and diffusion of oxygen vacancies in the central oxide under an external field, and an ab-initio quantum transport method to calculate electrical current and conductance. As such, it reproduces a realistically stochastic device operation and its impact on the resulting conductance. We demonstrate this framework by simulating a switching cycle for a TiN/HfO$_2$/TiN VCM cell, and see a clear current hysteresis between high/low resistance states, with a conductance ratio of one order of magnitude. Additionally, we observe that the changes in conductance originate from the creation and recombination of vacancies near the active electrode, effectively modulating a tunnelling gap for the current. This framework can be used to further investigate the mechanisms behind resistive switching at an atomistic scale and optimize VCM material stacks and geometries.
The Janis-Newman-Winicour and Papapetrou metrics represent counterparts to the Schwarzschild black hole with scalar and antiscalar background fields, correspondingly (where "anti" is to be understood as in "anti-de Sitter"). There is also a scalar counterpart (the Krori-Bhattacharjee metric) to the Kerr black hole. Here we study analytical connections between these solutions and obtain the exact rotational generalization of the antiscalar Papapetrou spacetime as a viable alternative to the Kerr black hole. The antiscalar metrics appear to be the simplest ones as they do not reveal event horizons and ergospheres, and they do not involve an extra parameter for scalar charge. Static antiscalar field is thermodynamically stable and self-consistent, but this is not the case for the scalar Janis-Newman-Winicour solution; besides, antiscalar thermodynamics is reducible to black-hole thermodynamics. Lensing, geodetic and Lense-Thirring effects are found to be practically indistinguishable between antiscalar and vacuum solutions in weak fields. Only strong-field observations might provide a test for the existence of antiscalar background. In particular, the antiscalar solution predicts 5% larger shadows of supermassive compact objects, as compared to the vacuum solution. Another measurable aspect is the 6.92% difference in the frequency of the innermost stable circular orbit, characterizing the upper cut-off in the gravitational wave spectrum.
Using first-principles calculations we determine the role of compressive and tensile uniaxial and equibiaxial strain on the structural, electronic and magnetic properties of V$_2$O$_3$. We find that compressive strain increases the energy cost to transition from the high-temperature paramagnetic metallic phase to the low-temperature antiferromagnetic insulating phase. This shift in the energy difference can be explained by changes in the V-V bond lengths that are antiferromagnetically aligned in the low temperature structure. The insights that we have obtained provide a microscopic explanation for the shifts in the metal-insulator transition temperature that have been observed in experiments of V$_2$O$_3$ films grown on different substrates.
In this paper, by providing the uniform gradient estimates for a sequence of the approximating equations, we prove the existence, uniqueness and regularity of the conical parabolic complex Monge-Amp\`ere equation with weak initial data. As an application, we prove a regularity estimates, that is, any $L^{\infty}$-solution of the conical complex Monge-Amp\`ere equation admits the $C^{2,\alpha,\beta}$-regularity.
The problem of spectra formation in hydrodynamic approach to A+A collisions is discussed. It is analyzed in terms of the two different objects: distribution and emission functions. We show that though the process of particle liberation, described by the emission function, is, usually, continuous in time, the observable spectra can be also expressed by means of the Landau/Cooper-Frye prescription. We argue that such an approximate duality results from some symmetry properties that systems in A+A collisions reach to the end of hydrodynamic evolution and reduction of the collision rate at post hydrodynamic stage
For a $C^2$ function $u$ and an elliptic operator $L$, we prove a quantitative estimate for the derivative $du$ in terms of local bounds on $u$ and $Lu$. An integral version of this estimate is then used to derive a condition for the zero-mean value property of $\Delta u$. An extension to differential forms is also given. Our approach is probabilistic and could easily be adapted to other settings.
We discuss the way in which field theory quantities assemble the spatial geometry of three-dimensional anti-de Sitter space (AdS3). The field theory ingredients are the entanglement entropies of boundary intervals. A point in AdS3 corresponds to a collection of boundary intervals, which is selected by a variational principle we discuss. Coordinates in AdS3 are integration constants of the resulting equation of motion. We propose a distance function for this collection of points, which obeys the triangle inequality as a consequence of the strong subadditivity of entropy. Our construction correctly reproduces the static slice of AdS3 and the Ryu-Takayanagi relation between geodesics and entanglement entropies. We discuss how these results extend to quotients of AdS3 -- the conical defect and the BTZ geometries. In these cases, the set of entanglement entropies must be supplemented by other field theory quantities, which can carry the information about lengths of non-minimal geodesics.
Over the past years observations of young and populous star clusters have shown that the stellar initial mass function (IMF) can be conveniently described by a two-part power-law with an exponent alpha_2 = 2.3 for stars more massive than about 0.5 Msol and an exponent of alpha_1 = 1.3 for less massive stars. A consensus has also emerged that most, if not all, stars form in stellar groups and star clusters, and that the mass function of these can be described as a power-law (the embedded cluster mass function, ECMF) with an exponent beta ~2. These two results imply that the integrated galactic IMF (IGIMF) for early-type stars cannot be a Salpeter power-law, but that they must have a steeper exponent. An application to star-burst galaxies shows that the IGIMF can become top-heavy. This has important consequences for the distribution of stellar remnants and for the chemo-dynamical and photometric evolution of galaxies. In this contribution the IGIMF theory is described, and the accompanying contribution by Pflamm-Altenburg, Weidner & Kroupa (this volume) documents the applications of the IGIMF theory to galactic astrophysics.
In this paper, we study singular solutions of linear problems with fractional Laplacian. First, we establish B\^ocher type theorems on a punctured ball via distributional approach. Then, we develop a few interesting maximum principles on a punctured ball. Our distributional approach only requires the basic local L-1 integrability. We also introduce several simple and useful lemmas, which enable us to unify the treatments for both Laplacian and fractional Laplacian. These theorems, lemmas and the methods introduced here can be adapted and applied in other situations.
A p-divisible group over a complete local domain determines a Galois representation on the Tate module of its generic fibre. We determine the image of this representation for the universal deformation in mixed characteristic of a bi-infinitesimal group and for the p-rank strata of the universal deformation in positive characteristic of an infinitesimal group. The method is a reduction to the known case of one-dimensional groups by a deformation argument based on properties of the stratification by Newton polygons.
In this paper, we introduce the notion of representation of Bol algebra. We prove an analogue of the classical Engel's theorem and the ex- tension of Ado-Iwasawa theorem for Bol Algebras. We study the category of representations of Bol algebras and show that it is a tensor category. In the case of regular representations of Bol algebras, we give a complete classification of them for all two-dimensional Bol algebras.
Spectra that cover 0.63 - 0.69um with a spectral resolution ~ 17000 are presented of the W Serpentis system V367 Cygni. Absorption lines of FeII and SiII that form in a circumsystem shell are prominent features, and the depths of these are stable with time, suggesting that the shell is smoothly distributed and well-mixed. Further evidence of uniformity comes from modest radial velocity variations measured in the deepest parts of the shell lines. It is suggested that motions previously attributed to rotation of the shell are instead artifacts of contamination from the donor star spectrum. A donor star spectrum is extracted that is consistent with that of an early to mid-A giant. The depths of metallic lines in the donor spectrum vary with orbital phase, suggesting that spot activity covers a large fraction of the surface of that star. A spectrum of the accretion disk that surrounds the second star is also extracted, and similarities are noted with the emission spectra of Herbig Ae/Be stars. In addition to variations with orbital phase, H$\alpha$ changes with time over timescales of no more than two orbits. A tentative detection of HeI 6678 emission is made near primary minimum, but not at other phases. Finally, projected emission from hot dust in and around V367 Cyg is more-or-less symmetric and extends over 28 arcsec, or 0.09 pc at the distance of the system -- V367 Cyg is thus expelling matter into a large volume of the surrounding space.
Aiming to perform a study of the warm dust and gas in the luminous blue variable star G79.29+0.46 and its associated nebula, we present infrared Spitzer imaging and spectroscopy, and new CO J=2-->1 and 4-->3 maps obtained with the IRAM 30m radio telescope and with the Submillimeter Telescope, respectively. We have analyzed the nebula detecting multiple shells of dust and gas connected to the star. Using Infrared Spectrograph-Spitzer spectra, we have compared the properties of the central object, the nebula, and their surroundings. These spectra show a rich variety of solid-state features (amorphous silicates, polycyclic aromatic hydrocarbons, and CO2 ices) and narrow emission lines, superimposed on a thermal continuum. We have also analyzed the physical conditions of the nebula, which point to the existence of a photo-dissociation region.
We prove a global in time existence theorem for the initial value problem for the Einstein-Boltzmann system, with positive cosmological constant and arbitrarily large initial data, in the spatially homogeneous case, in a Robertson-Walker space-time.
We present the results of our numerical experiments on stellar scattering in the galactic disc under the influence of the perturbed galactic gravitation field connected with the spiral density waves and show that the point of view according to which stars do not migrate far from their birthplace, in general, is incorrect. Despite close initial locations and the same velocities after 4.6 Gyrs members of an open cluster are scattered over a very large part of the galactic disc. If we adopt that the parental solar cluster had $\sim 10^3$ stars, it is unlikely to reveal the solar siblings within 100 pc from the Sun. The problem stands a good chance to be solved if the cluster had $\sim 10^4$ stars.   We also demonstrate that unbound open clusters disperse off in a short period of time under the influence of spiral gravitation field. Their stars became a part of the galactic disc. We have estimated typical times of the cluster disruption in radial and azimuth directions and the corresponding diffusion coefficients.
Amato et al.[arXiv:1205.6418] maintain that certain data published in Carpinteri et al.[2] are not the result of independent measurements, and are in any case affected by uncertainties such that our conclusions are not valid. We will provide clarification regarding the validity of the disputed analyses, showing that they, like the others reported in the original article, are independent and that the uncertainties affecting them in no way invalidate our conclusions.