ShantanuT01/DACTYL-Pretraining huggingface dataset:
The single top production proceeds through different channels at LHC. The t-channel production which has a cross section at the level of one third of the ttbar, can be regarded as a source of light charged Higgs boson through top quark decay to charged Higgs. Due to the low jet multiplicity and characteristic kinematic features of this process, a signal selection can be designed to extract charged Higgs signal from the background processes. In this paper, taking MSSM as the theoretical framework, The light charged Higgs signal from single top events is analyzed. The charged Higgs is assumed to decay to tau nu and the hadronic decay of tau leptons is analyzed. Different charged Higgs mass hypotheses are analyzed and a scan over the parameter space (mH+,tanbeta) is performed. It is shown that this process has the potential to exclude large areas of parameter space, while with enough data, a 5 sigma discovery would also be possible. Finally 95% C.L. exclusion and 5 sigma contours are provided for different integrated luminosities of LHC.
Evidence has mounted that Type Ia and core-collapse (CC) supernovae (SNe) can have substantial deviations from spherical symmetry; one such piece of evidence is the complex morphologies of supernova remnants (SNRs). However, the relative role of the explosion geometry and the environment in shaping SNRs remains an outstanding question. Recently, we have developed techniques to quantify the morphologies of SNRs, and we have applied these methods to the extensive X-ray and infrared archival images available of Milky Way and Magellanic Cloud SNRs. In this proceeding, we highlight some results from these studies, with particular emphasis on SNR asymmetries and whether they arise from "nature" versus "nurture".
Thanks to a variety of pertinent wide-angle facilities (WFI-slitless mode, VLT-FLAMES (Pasquini et al. 2002), SPITZER, 2MASS) it is possible to comprehensively study the nature of early-type objects in star-forming regions like the Eagle Nebula and Carina on large spatial scales. In them, the young open clusters NGC 6611, Trumpler 14, Trumpler 15, Trumpler 16, and their vicinities are of particular interest. With the WFI in its slitless mode (Baade et al. 1999), one can reliably and with little extra effort discriminate in thousands of spectra between intrinsic circumstellar emission as in HBe/Ae stars and diffuse interstellar line emission. The only bias results from the need of the equivalent width and absolute strength of the line emission to be sufficient for detection. VLT-FLAMES spectra combined with infrared data from SPITZER and 2MASS permit the nature of the objects with and without emission-lines to be derived. Following this approach, we report on the discovery and classification of new Herbig Be/Ae stars, pre-main sequence objects, and main sequence stars in these regions. Based on line-width measurements in VLT-FLAMES spectra, the evolution of the rotational velocities between pre-main sequence and main sequence phases is also discussed.
A novel method for robust estimation, called Graph-Cut RANSAC, GC-RANSAC in short, is introduced. To separate inliers and outliers, it runs the graph-cut algorithm in the local optimization (LO) step which is applied when a so-far-the-best model is found. The proposed LO step is conceptually simple, easy to implement, globally optimal and efficient. GC-RANSAC is shown experimentally, both on synthesized tests and real image pairs, to be more geometrically accurate than state-of-the-art methods on a range of problems, e.g. line fitting, homography, affine transformation, fundamental and essential matrix estimation. It runs in real-time for many problems at a speed approximately equal to that of the less accurate alternatives (in milliseconds on standard CPU).
Fermi surface of the two-dimensional t-J model is studied using the variational Monte Carlo method. We study the Gutzwiller projected d-wave superconducting state with an additional variational parameter t'_v corresponding to the next-nearest neighbor hopping term. It is found that the finite t'_v<0 gives the lowest variational energy in the wide range of hole-doping rates. The obtained momentum distribution function shows that the Fermi surface deforms spontaneously. It is also shown that the van Hove singularity is always located very close to the Fermi energy. Using the Gutzwiller approximation, we show that this spontaneous deformation is due to the Gutzwiller projection operator or the strong correlation.
In a superhigh magnetic field, direct Urca reactions can proceed for an arbitrary proton concentration. Since only the electrons with high energy $E$ ($E > Q$, $Q$ is the threshold energy of inverse $\beta-$decay) at large Landau levels can be captured, we introduce the Landau level effect coefficient $q$ and the effective electron capture rate $\Gamma_{\rm eff}$. By using $\Gamma_{\rm eff}$, the values of $L_{\rm X}$ and $L_{\rm \nu}$ are calculated, where and $L_{\rm \nu}$, $L_{\rm X}$ are the average neutrino luminosity of Anomalous X-ray Pulsars (AXPs) and the average X-ray luminosity of AXPs, respectively. The complete process of electron capture inside a magnetar is simulated numerically.
We study a class of N=1 Supergravity inflationary models in which the evolution of the inflaton dynamics is controlled by a single power in the inflaton field at the point where the observed density fluctuations are produced, in the context of the braneworld scenario, in light of WMAP results. In particular, we find that the bounds on the spectral index and its running constrain the parameter space both for models where the inflationary potential is dominated by a quadratic term and by a cubic term in the inflaton field. We also find that $\alpha_s>0$ is required for the quadratic model whereas $\alpha_s<0 $ for the cubic model. Moreover, we have determined an upper bound on the five-dimensional Planck scale, $M_5 \lsim 0.019$ M, for the quadratic model. On the other hand, a running spectral index with $n_s>1$ on large scales and $n_s<1$ on small scales is not possible in either case.
Most recent semi-supervised video object segmentation (VOS) methods rely on fine-tuning deep convolutional neural networks online using the given mask of the first frame or predicted masks of subsequent frames. However, the online fine-tuning process is usually time-consuming, limiting the practical use of such methods. We propose a directional deep embedding and appearance learning (DDEAL) method, which is free of the online fine-tuning process, for fast VOS. First, a global directional matching module, which can be efficiently implemented by parallel convolutional operations, is proposed to learn a semantic pixel-wise embedding as an internal guidance. Second, an effective directional appearance model based statistics is proposed to represent the target and background on a spherical embedding space for VOS. Equipped with the global directional matching module and the directional appearance model learning module, DDEAL learns static cues from the labeled first frame and dynamically updates cues of the subsequent frames for object segmentation. Our method exhibits state-of-the-art VOS performance without using online fine-tuning. Specifically, it achieves a J & F mean score of 74.8% on DAVIS 2017 dataset and an overall score G of 71.3% on the large-scale YouTube-VOS dataset, while retaining a speed of 25 fps with a single NVIDIA TITAN Xp GPU. Furthermore, our faster version runs 31 fps with only a little accuracy loss. Our code and trained networks are available at https://github.com/YingjieYin/Directional-Deep-Embedding-and-Appearance-Learning-for-Fast-Video-Object-Segmentation.
In the last decade, X-ray spectroscopy has enabled a wealth of discoveries of photoionised absorbers in X-ray binaries. Studies of such accretion disc atmospheres and winds are of fundamental importance to understand accretion processes and possible feedback mechanisms to the environment. In this work, we review the current observational state and theoretical understanding of accretion disc atmospheres and winds in low-mass X-ray binaries, focusing on the wind launching mechanisms and on the dependence on accretion state. We conclude with issues that deserve particular attention.
In this paper we develop a theory of Grothendieck's six operations for adic constructible sheaves on Artin stacks continuing the study of the finite coefficients case in math.AG/0512097.
The recent discovery that for large Hilbert spaces, almost all (that is, typical) Hamiltonians have eigenstates that place small subsystems in thermal equilibrium, has shed much light on the origins of irreversibility and thermalization. Here we give numerical evidence that many-body lattice systems generically approach typicality as the number of subsystems is increased, and thus provide further support for the eigenstate thermalization hypothesis. Our results indicate that the deviation of many-body systems from typicality decreases exponentially with the number of systems. Further, by averaging over a number of randomly-selected nearest-neighbor interactions, we obtain a power-law for the atypicality as a function of the Hilbert space dimension, distinct from the power-law possessed by random Hamiltonians.
In this study, a multiple hypothesis tracking (MHT) algorithm for multi-target multi-camera tracking (MCT) with disjoint views is proposed. Our method forms track-hypothesis trees, and each branch of them represents a multi-camera track of a target that may move within a camera as well as move across cameras. Furthermore, multi-target tracking within a camera is performed simultaneously with the tree formation by manipulating a status of each track hypothesis. Each status represents three different stages of a multi-camera track: tracking, searching, and end-of-track. The tracking status means targets are tracked by a single camera tracker. In the searching status, the disappeared targets are examined if they reappear in other cameras. The end-of-track status does the target exited the camera network due to its lengthy invisibility. These three status assists MHT to form the track-hypothesis trees for multi-camera tracking. Furthermore, they present a gating technique for eliminating of unlikely observation-to-track association. In the experiments, they evaluate the proposed method using two datasets, DukeMTMC and NLPR-MCT, which demonstrates that the proposed method outperforms the state-of-the-art method in terms of improvement of the accuracy. In addition, they show that the proposed method can operate in real-time and online.
After years of research into colossal magnetoresistant (CMR) manganites using bulk techniques, there has been a recent upsurge in experiments directly probing the electronic states at or near the surface of the bilayer CMR materials La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ using angle-resolved photoemission or scanning probe microscopy. Here we report new, temperature dependent, angle resolved photoemission data from single crystals with a doping level of $x=0.36$. The first important result is that there is no sign of a pseudogap in the charge channel of this material for temperatures below the Curie temperature $T_C$. The second important result concerns the temperature dependence of the electronic states. The temperature dependent changes in the Fermi surface spectra both at the zone face and zone diagonal regions in $k$-space indicate that the coherent quasiparticle weight disappears for temperatures significantly above $T_C$, and that the $k$-dependence of the T-induced changes in the spectra invalidate an interpretation of these data in terms of the superposition of a `universal' metallic spectrum and an insulating spectrum whose relative weight changes with temperature. In this sense, our data are not compatible with a phase separation scenario.
In the paper, the results of analysis of elastic scattering and breakup processes in interactions of the $^{11}$Li nucleus with protons are presented. The hybrid model of the microscopic optical potential (OP) is applied. This OP includes the single-folding real part, while its imaginary part is derived within the high-energy approximation (HEA) theory. For the $^{11}$Li$+p$ elastic scattering, the microscopic large-scale shell model (LSSM) density of $^{11}$Li is used. The depths of the real and imaginary parts of OP are fitted to the elastic scattering data at 62, 68.4, and 75 MeV/nucleon, being simultaneously adjusted to reproduce the true energy dependence of the corresponding volume integrals. The role of the spin-orbit potential is studied and predictions for the total reaction cross sections are made. Also, the cluster model, in which $^{11}$Li consists of $2n$-halo and the $^{9}$Li core having its own LSSM form of density, is adopted. The respective microscopic proton-cluster OP's are calculated and folded with the density probability of the relative motion of both clusters to get the whole $^{11}$Li$+p$ optical potential. The breakup cross sections of $^{11}$Li at 62 MeV/nucleon and momentum distributions of the cluster fragments are calculated. An analysis of the single-particle density of $^{11}$Li within the same cluster model accounting for the possible geometric forms of the halo-cluster density distribution is performed.
Quantum dots are nanostructures made of semiconducting materials that are engineered to hold a small amount of electric charge (a few electrons) that is controlled by external gate and may hence be considered as tunable artificial atoms. A quantum dot may be contacted by conductive leads to become the active part of a single-electron transistor, a device that is highly conductive only at very specific gate voltages. In recent years a significant attention has been given to more complex hybrid devices, in particular superconductor-semiconductor heterostructures. Here I review the theoretical and experimental studies of small quantum-dot devices contacted by one or several superconducting leads. I focus on the research on the low-lying localized electronic excitations that exist inside the superconducting gap (Yu-Shiba-Rusinov states) and determine the transport properties of these devices. The sub-gap states can be accurately simulated using the numerical renormalization group technique, often providing full quantitative understanding of the observed phenomena.
In this paper we investigate Gaussian risk models which include financial elements such as inflation and interest rates. For some general models for inflation and interest rates, we obtain an asymptotic expansion of the finite-time ruin probability for Gaussian risk models. Furthermore, we derive an approximation of the conditional ruin time by an exponential random variable as the initial capital tends to infinity.
If G is a finite graph, then the largest eigenvalue L of the adjacency matrix of G is a totally real algebraic integer (L is the Perron-Frobenius eigenvalue of G). We say that G is abelian if the field generated by L^2 is abelian. Given a fixed graph G and a fixed set of vertices of G, we define a spider graph to be a graph obtained by attaching to each of the chosen vertices of G some 2-valent trees of finite length. The main result is that only finitely many of the corresponding spider graphs are both abelian and not Dynkin diagrams, and that all such spiders can be effectively enumerated; this generalizes a previous result of Calegari, Morrison, and Snyder. The main theorem has applications to the classification of finite index subfactors. We also prove that the set of Salem numbers of "abelian type" is discrete.
We report the discovery of a new cataclysmic variable MASTER OT J161700.81+620024.9 which is identical to the faint ROSAT X-ray source 1RXS J161659.5+620014. The object was observed in outbursts to 14.4m on 2012 Sep. 11 by MASTER-Tunka and to 14.3m on 2013 Jan. 21/22 by MASTER-Kislovodsk, but was not detected by the routine search procedures. Analysis of the archival MASTER data and CRTS light curve shows the variability from 17.8m at quiescence to 14.3m in outbursts, confirming that the new variable is a dwarf nova. SDSS colors suggest a small contribution from the secondary component and are telling in favor of the short orbital period.
In this work, two new axisymmetric models for the Galactic mass distribution are presented. Motivated by recent results, these two models include the contribution of a stellar thin disc and of a thick disc, as massive as the thin counterpart but with a shorter scale-length. Both models satisfy a number of observational constraints: stellar densities at the solar vicinity, thin and thick disc scale lengths and heights, rotation curve(s), and the absolute value of the perpendicular force Kz as a function of distance to the Galactic centre. We numerically integrate into these new models the motion of all Galactic globular clusters for which distances, proper motions, and radial velocities are available, and the orbits of about one thousand stars in the solar vicinity. The retrieved orbital characteristics are compared to those obtained by integrating the clusters and stellar orbits in pure thin disc models. We find that, due to the possible presence of a thick disc, the computed orbital parameters of disc stars can vary by as much as 30-40%. We also show that the systematic uncertainties that affect the rotation curve still plague computed orbital parameters of globular clusters by similar amounts.
The paper deals with local well-posedness, global existence and blow-up results for reaction--diffusion equations coupled with nonlinear dynamical boundary conditions.
The recent launch of Solar Orbiter and BepiColombo opened a brief window in which these two spacecraft were positioned in a constellation that allows for the detailed sampling of any Earth-directed CMEs. Fortunately, two such events occurred with in situ detections of an ICME by Solar Orbiter on the 19th of April and the 28th of May 2020. These two events were subsequently also observed in situ by BepiColombo and Wind around a day later. We attempt to reconstruct the observed in situ magnetic field measurements for all three spacecraft simultaneously using an empirical magnetic flux rope model. This allows us to test the validity of our flux rope model on a larger and more global scale and allows for cross-validation of the analysis with different spacecraft combinations. Finally, we can also compare the results from the in situ modeling to remote observations obtained from the STEREO-A heliospheric imagers. We make use of the 3D coronal rope ejection model in order to simulate the ICME evolution. We adapt a previously developed ABC-SMC fitting algorithm for the application to multi point scenarios. We show that we are able to generally reconstruct the flux ropes signatures at three different spacecraft positions simultaneously using our model in combination with the flux rope fitting algorithm. For the well-behaved 19th of April ICME our approach works very well. The 28th of May ICME, on the other hand, shows the limitations of our approach. Unfortunately, the usage of multi-point observations for these events does not appear to solve inherent issues, such as the estimation of the magnetic field twist or flux rope aspect-ratios due to the specific constellation of the spacecraft positions. As our general approach can be used for any fast forward simulation-based model we give a blueprint for future studies using more advanced ICME models.
One of the most basic results in graph theory states that every graph with at least two vertices has two vertices with the same degree. Since there are graphs without $3$ vertices of the same degree, it is natural to ask if for any fixed $k$, every graph $G$ is ``close'' to a graph $G'$ with $k$ vertices of the same degree. Our main result in this paper is that this is indeed the case. Specifically, we show that for any positive integer $k$, there is a constant $C=C(k)$, so that given any graph $G$, one can remove from $G$ at most $C$ vertices and thus obtain a new graph $G'$ that contains at least $\min\{k,|G|-C\}$ vertices of the same degree.   Our main tool is a multidimensional zero-sum theorem for integer sequences, which we prove using an old geometric approach of Alon and Berman.
In this paper, we consider the solvability problems for the fully coupled forward-backward stochastic difference equations (FBS{\Delta}Es) on spaces related to discrete time, finite state processes. On one hand, we provide the necessary and sufficient condition for the solvability of the linear FBS{\Delta}Es. On the other hand, under the assumption that the coefficients satisfy the monotone condition, we investigate the existence and uniqueness theorems for the general nonlinear FBS{\Delta}Es.
There is gathering indirect evidence suggesting non-conservative evolutions in Algols. However, the systemic mass-loss rate is poorly constrained by observations and generally set as a free parameter in binary-star evolution simulations. Moreover, systemic mass loss may lead to observational signatures that are still to be found. We investigate the impact of the outflowing gas and the possible presence of dust grains on the spectral energy distribution (SED). We used the 1D plasma code Cloudy and compared the results with the 3D Monte-Carlo radiative transfer code Skirt for dusty simulations. The circumbinary mass-distribution and binary parameters are computed with state-of-the-art binary calculations done with the Binstar evolution code. The outflowing material reduces the continuum flux-level of the stellar SED in the optical and UV. Due to the time-dependence of this effect, it may help to distinguish between different ejection mechanisms. Dust, if present, leads to observable infrared excesses even with low dust-to-gas ratios and traces the cold material at large distances from the star. By searching for such dust emission in the WISE catalogue, we found a small number of Algols showing infrared excesses, among which the two rather surprising objects SX Aur and CZ Vel. We find that some binary B[e] stars show the same strong Balmer continuum as we predict with our models. However, direct evidence of systemic mass loss is probably not observable in genuine Algols, since these systems no longer eject mass through the hotspot mechanism. Furthermore, owing to its high velocity, the outflowing material dissipates in a few hundred years. If hot enough, the hotspot may produce highly ionised species such as SiIV and observable characteristics that are typical of W Ser systems.
The developments summarized with the name ``weak gravitational lensing'' have led to exciting possibilities to study the (statistical properties of the) dark matter distribution in the Universe. Concentrating on those aspects which require deep wide-field imaging surveys, we describe the basic principles of weak lensing and discuss its future applications in view of NGST (a) to determine the statistical properties of the dark matter halos of individual galaxies, (b) to determine the mass and the mass profile of very low-mass clusters and groups at medium redshift and/or of more massive clusters at very high redshift, and (c) to measure the power spectrum of the matter distribution in the Universe in the non-linear regime, thereby also obtaining a mass-selected sample of halos and providing a means to investigate the scale- and redshift dependence of the bias `factor'.
Higher-derivative theories of free higher-spin fields are investigated focusing on their symmetries. Generalizing familiar two-derivative constrained formulations, we first construct less-constrained Einstein-like and Maxwell-like higher-derivative actions. Then, we construct Weyl-like actions - the actions admitting constrained Weyl symmetries - with different numbers of derivatives. They are presented in a factorized form making use of Einstein-like and Maxwell-like tensors. The last (highest-derivative) member of the hierarchy of the Weyl-like actions coincides with the Fradkin-Tseytlin conformal higher-spin action in four dimensions.