ShantanuT01/DACTYL-Pretraining huggingface dataset:
We argue that the description of Feynman loop integrals as integrable systems is intimately connected with their motivic properties and the action of the Cosmic Galois Group. We show how in the case of a family of fishnet graphs, coaction relations between graphs follow directly from iterative constructions of Q-functions in the Quantum Spectral Curve formalism. Using this observation we conjecture a "differential equation for numbers" that enter these periods.
Recent approaches have shown that training deep neural networks directly on large-scale image-text pair collections enables zero-shot transfer on various recognition tasks. One central issue is how this can be generalized to object detection, which involves the non-semantic task of localization as well as semantic task of classification. To solve this problem, we introduce a vision-language embedding alignment method that transfers the generalization capabilities of a pretrained model such as CLIP to an object detector like YOLOv5. We formulate a loss function that allows us to align the image and text embeddings from the pretrained model CLIP with the modified semantic prediction head from the detector. With this method, we are able to train an object detector that achieves state-of-the-art performance on the COCO, ILSVRC, and Visual Genome zero-shot detection benchmarks. During inference, our model can be adapted to detect any number of object classes without additional training. We also find that standard object detection scaling can transfer well to our method and find consistent improvements across various scales of YOLOv5 models and the YOLOv3 model. Lastly, we develop a self-labeling method that provides a significant score improvement without needing extra images nor labels.
The shadow of a black hole can be one of the strong observational evidences for stationary black holes. If we see shadows at the center of galaxies, we would say whether the observed compact objects are black holes. In this paper, we consider a formula for the contour of a shadow in an asymptotically-flat, stationary, and axisymmetric black hole spacetime. We show that the formula is useful for obtaining the contour of the shadow of several black holes such as the Kerr-Newman black hole and rotating regular black holes. Using the formula, we can obtain new examples of the contour of the shadow of rotating black holes if assumptions are satisfied.
We give an alternative proof of the fact that the vertex reinforced jump process on Galton- Watson tree has a phase transition between recurrence and transience as a function of c, the initial local time, see [3]. Further, applying the techniques in [1], we show a phase transition between positive speed and null speed for the discrete time process associated in the transient regime.
Pre-outburst 2MASS and WISE photometry of Nova Sco 2014 (V1534 Sco) have suggested the presence of a cool giant at the location of the nova in the sky. The spectral evolution recorded for the nova did not however support a direct partnership because no flash-ionized wind and no deceleration of the ejecta were observed, contrary to the behavior displayed by other novae which erupted within symbiotic binaries like V407 Cyg or RS Oph. We have therefore obtained an 0.8-2.5 micron spectra of the remnant of Nova Sco 2014 in order to ascertain if a cool giant is indeed present and if it is physically associated with the nova. The spectrum shows the presence of a M6III giant, reddened by E(B-V)=1.20, displaying the typical and narrow emission-line spectrum of a symbiotic star, including HeI 1.0830 $\mu$m with a deep P-Cyg profile. This makes Nova Sco 2014 a new member of the exclusive club of novae that erupt within a symbiotic binary. Nova Sco 2014 shows that a nova erupting witin a symbiotic binary does not always come with a deceleration of the ejecta, contrary to the common belief. Many other similar systems may lay hidden in past novae, expecially in those that erupted prior to the release of the 2MASS all-sky infrared survey, which could be profitably cross-matched now against them.
Very recently a conjecture saying that the so-called structural physical approximations (SPAa) to optimal positive maps (optimal entanglement witnesses) give entanglement breaking (EB) maps (separable states) has been posed [J. K. Korbicz {\it et al.}, Phys. Rev. A {\bf 78}, 062105 (2008)]. The main purpose of this contribution is to explore this subject. First, we extend the set of entanglement witnesses (EWs) supporting the conjecture. Then, we ask if SPAs constructed from other than the depolarizing channel maps also lead to EB maps and show that in general this is not the case. On the other hand, we prove an interesting fact that for any positive map $\Lambda$ there exists an EB channel $\Phi$ such that the SPA of $\Lambda$ constructed with the aid of $\Phi$ is again an EB channel. Finally, we ask similar questions in the case of continuous variable systems. We provide a simple way of construction of SPA and prove that in the case of the transposition map it gives EB channel.
We have studied in this work the effect of increasing structural disorder on the persistent luminescence of Cr$^{3+}$ doped zinc gallate spinel. This disorder was introduced by progressive substitution of Zn$^{2+}$ by Mg$^{2+}$ ions, and was studied by photoluminescence, X-ray diffraction, extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES) and electron paramagnetic resonance (EPR) spectroscopy. It was found that increasing Mg/Zn substitution decreases the number of Cr$^{3+}$ in undistorted sites, and increases the number of Cr$^{3+}$ with neighbouring antisite defects and with neighbouring Cr$^{3+}$ ions (referred as Cr clusters), which in turn decreases the intensity of persistent luminescence. Both XANES and EPR spectra could be simulated by a linear combination of Cr$^{3+}$ spectra with three types of Cr$^{3+}$ environments. The increasing disorder was found to be correlated with a decrease of the average Cr-O bond length and a decrease of crystal field strength experienced by Cr$^{3+}$ ions.
Resonant Raman spectra of single layer WS$_{2}$ flakes are presented. A second order Raman peak (2LA) appears under resonant excitation with a separation from the E$^{1}_{2g}$ mode of only $4$cm$^{-1}$. Depending on the intensity ratio and the respective line widths of these two peaks, any analysis which neglects the presence of the 2LA mode can lead to an inaccurate estimation of the position of the E$^{1}_{2g}$ mode, leading to a potentially incorrect assignment for the number of layers. Our results show that the intensity of the 2LA mode strongly depends on the angle between the linear polarization of the excitation and detection, a parameter which is neglected in many Raman studies.
We present a statistical study of the filamentary structure orientation in the CO emission observations obtained in the Milky Way Imaging Scroll Painting (MWISP) survey in the range $25.8\deg < l < 49.7\deg$, $|b| \leq 1.25\deg$, and $-100 < v_{\rm LSR} < 135$ km/s. We found that most of the filamentary structures in the $^{12}$CO and $^{13}$CO emission do not show a global preferential orientation either parallel or perpendicular to the Galactic plane. However, we found ranges in Galactic longitude and radial velocity where the $^{12}$CO and $^{13}$CO filamentary structures are parallel to the Galactic plane. These preferential orientations are different from those found for the HI emission. We consider this an indication that the molecular structures do not simply inherit these properties from parental atomic clouds. Instead, they are shaped by local physical conditions, such as stellar feedback, magnetic fields, and Galactic spiral shocks.
We present new ALMA observations aimed at mapping molecular gas reservoirs through the CO(3-2) transition in three quasars at $z\simeq2.4$, LBQS 0109+0213, 2QZ J002830.4-281706, and [HB89] 0329-385. Previous [OIII]5007 observations of these quasars showed evidence for ionised outflows quenching star formation in their host galaxies. Systemic CO(3-2) emission has been detected only in one quasar, LBQS 0109+0213, where the CO(3-2) emission is spatially anti-correlated with the ionised outflow, suggesting that most of the molecular gas may have been dispersed or heated in the region swept by the outflow. In all three sources, including the one detected in CO, our constraints on the molecular gas mass indicate a significantly reduced reservoir compared to main-sequence galaxies at the same redshift, supporting a negative feedback scenario. In the quasar 2QZ J002830.4-281706, we tentatively detect an emission line blob blue-shifted by $v\sim-2000$ km/s with respect to the galaxy systemic velocity and spatially offset by 0.2 arcsec (1.7 kpc) with respect to the ALMA continuum peak. Interestingly, such emission feature is coincident in both velocity and space with the ionised outflow as seen in [OIII]5007. This tentative detection must be confirmed with deeper observations but, if real, it could represent the molecular counterpart of the ionised gas outflow driven by the AGN. Finally, in all ALMA maps we detect the presence of serendipitous line emitters within a projected distance $\sim 160$ kpc from the quasars. By identifying these features with the CO(3-2) transition, the serendipitous line emitters would be located within |$\Delta v$|$<$500 km/s from the quasars, hence suggesting an overdensity of galaxies in two out of three quasars.
The Raman scattering spectra from magnetic excitations in an antiferromagnetic spin-1/2 two leg ladder is investigated for weak and strong interladder coupling. In the first case, a cusp in the Raman intensityis obtained at a frequency twice the gap. In the second case, a peak at twice the gap replaces the cusp. We discuss the relevance of our calculation to recent experiments on CaV2O5 and Sr14Cu24O41.
In this work, by applying the redshift tomography method to Joint Light-curve Analysis (JLA) supernova sample, we explore the possible redshift-dependence of stretch-luminosity parameter $\alpha$ and color-luminosity parameter $\beta$. The basic idea is to divide the JLA sample into different redshift bins, assuming that $\alpha$ and $\beta$ are piecewise constants. Then, by constraining the $\Lambda$CDM model, we check the consistency of cosmology-fit results given by the SN sample of each redshift bin. We also adopt the same technique to explore the possible evolution of $\beta$ in various subsamples of JLA. Using the full JLA data, we find that $\alpha$ is always consistent with a constant. In contrast, at high redshift $\beta$ has a significant trend of decreasing, at $\sim 3.5\sigma$ confidence level (CL). Moreover, we find that low-$z$ subsample favors a constant $\beta$; in contrast, SDSS and SNLS subsamples favor a decreasing $\beta$ at 2$\sigma$ and $3.3\sigma$ CL, respectively. Besides, by using a binned parameterization of $\beta$, we study the impacts of $\beta$'s evolution on parameter estimation. We find that compared with a constant $\beta$, a varying $\beta$ yields a larger best-fit value of fractional matter density $\Omega_{m0}$, which slightly deviates from the best-fit result given by other cosmological observations. However, for both the varying $\beta$ and the constant $\beta$ cases, the $1\sigma$ regions of $\Omega_{m0}$ are still consistent with the result given by other observations.
We discuss the magnetic properties of a dimerized and completely frustrated tetrahedral spin-1/2 chain. Using a combination of exact diagonalization and bond-operator theory the quantum phase diagram is shown to incorporate a singlet-product, a dimer, and a Haldane phase. In addition we consider one-, and two-triplet excitations in the dimer phase and evaluate the magnetic Raman cross section which is found to be strongly renormalized by the presence of a two-triplet bound state. The link to a novel tellurate materials is clarified.
We study the properties of the Higgs and supersymmetric particle spectrum associated with the infrared fixed point solution of the top quark mass in the MSSM. We concentrate on the possible detection of these particles, analysing the deviations from the Standard Model predictions for the leptonic and hadronic variables measured at LEP and for the decay rate $b\rightarrow s\gamma$. We consider the low and moderate $\tan \beta$ regime, and we study both, the cases of universal and non--universal soft supersymmetry breaking parameters at high energies. In the first case, for any given value of the top quark mass, the Higgs and sparticle spectra are completely determined as a function of two soft supersymmetry breaking parameters. In the case of non--universality, instead, the strong correlations between the sparticle masses are relaxed, allowing a richer structure for the precision data variables. We show, however, that the requirement that the low energy theory proceeds from a grand unified theory with a local symmetry group including $SU(5)$, strongly constrains the set of possible indirect experimental signatures. As a general feature, whenever a significant deviation from the Standard Model value of the precision data variables is predicted, a light sparticle, visible at LEP2, appears in the spectrum.
We study cosmological perturbations in the framework of Loop Quantum Cosmology, using a hybrid quantization approach and Mukhanov-Sasaki variables. The formulation in terms of these gauge invariants allows one to clarify the independence of the results on choices of gauge and facilitates the comparison with other approaches proposed to deal with cosmological perturbations in the context of Loop Quantum Theory. A kind of Born-Oppenheimer ansatz is employed to extract the dynamics of the inhomogeneous perturbations, separating them from the degrees of freedom of the Friedmann-Robertson-Walker geometry. With this ansatz, we derive an approximate Schr\"odinger equation for the cosmological perturbations and study its range of validity. We also prove that, with an alternate factor ordering, the dynamics deduced for the perturbations is similar to the one found in the so-called "dressed metric approach", apart from a possible scaling of the matter field in order to preserve its unitary evolution in the regime of Quantum Field Theory in a curved background and some quantization prescription issues. Finally, we obtain the effective equations that are naturally associated with the Mukhanov-Sasaki variables, both with and without introducing the Born-Oppenheimer ansatz, and with the different factor orderings that we have studied.
Betelgeuse is an M-type supergiant that presents a circularly polarized (Stokes V) signal in its line profiles, interpreted in terms of a surface magnetic field.   The weak circular polarization signal has been monitored over 7.5 years in order to follow its evolution on different timescales, and eventually to determine its physical origin. Linear polarization measurements have also been obtained regularly in the last few years.   We used both the ESPaDOnS and Narval spectropolarimeters to obtain high signal-to-noise ratio (S/N) spectra, which were processed by means of the least-squares deconvolution (LSD) method. In order to ensure the reality of the very weak circular polarization, special care has been taken to limit instrumental effects. In addition, several tests were performed on the Stokes V signal to establish its stellar and Zeeman origin.   We confirm the magnetic nature of the circular polarization, pointing to a surface magnetic field of the order of 1G. The Stokes V profiles present variations over different timescales, the most prominent one being close to the long secondary period (LSP; around 2000d for Betelgeuse) often invoked in red evolved stars. This long period is also dominant for all the other Stokes parameters. The circular polarization is tentatively modeled by means of magnetic field concentrations mimicking spots, showing in particular that the velocity associated with each "spot" also follows the long timescale, and that this signal is nearly always slightly redshifted.   From the coupled variations of both linear and circular polarization signatures in amplitude, velocity and timescale, we favour giant convection cells as the main engine at the origin of polarization signatures and variations in all the Stokes parameters. This strengthens support for the hypothesis that large convective cells are at the origin of the LSP.
Neutrinos are the only known elementary fermions that can exhibit Majorana nature. As per the "practical Dirac-Majorana confusion theorem" it is impossible to distinguish between Dirac and Majorana neutrinos via any kinematic tests when their masses are very small. However, it is also well known that Majorana neutrino and anti-neutrino present in the final state must obey the Fermi-Dirac statistics, irrespective of how small the mass of neutrino is. We propose a new method to search for Majorana neutrinos by exploiting their quantum statistical property. We analyse `effective' three-body decays of the kind $X \to Y \nu \overline{\nu}$ (e.g.\ $X \left[ B^0 \right] \to \pi^+ \big( \to \mu^+ \nu_{\mu} \big) \mu^- \overline{\nu}_{\mu} \equiv Y \left[ \mu^+ \mu^-\right] \nu_{\mu} \overline{\nu}_{\mu}$), with 4-momenta of $X$ and $Y$ experimentally known, such that the 4-momenta of both neutrino and anti-neutrino can be deduced. For Majorana neutrinos the distribution of events in the `effective' Dalitz plot for such a well chosen process would be fully symmetric under exchange of the neutrino and anti-neutrino. Unlike the neutrinoless double-beta decay or other lepton-number violating modes, this distinction between Majorana and Dirac neutrinos survives even in the almost massless neutrino limit due to the quantum statistical property.
We review and discuss recent advances in the simulation of bulk critical phenomena in model fluids. In particular we emphasise the extensions to finite-size scaling theory needed to cope with the lack of symmetry between coexisting fluid phases. The consequences of this asymmetry for simulation measurements of quantities such as the particle density and the heat capacity are pointed out and the relationship to experiment is discussed. A general simulation strategy based on the finite-size scaling theory is described and its utility illustrated via Monte-Carlo studies of the Lennard-Jones fluid and a two-dimensional spin fluid model. Recent applications to critical polymer blends and solutions are also briefly reviewed. Finally we consider the outlook for future simulation work in the field.
In this paper, we consider a nonlocal parabolic equation associated with initial and Dirichlet boundary conditions. Firstly, we discuss the vacuum isolating behavior of solutions with the help of a family of potential wells. Then we obtain a threshold of global existence and blow up for solutions with critical initial energy. Furthermore, for those solutions satisfy $J(u_0)\leq d$ and $I(u_0)\neq 0$, we show that global solutions decay to zero exponentially as time tends to infinity and the norm of blow-up solutions increase exponentially.
Barrow, and Barrow and collaborators, have put forward theoretical models with variable fundamental constants including JBD theories. The experimental evidence for an accelerating Universe points out to a deceleration parameter approximately equal to -- 1. On the other hand, there is evidence for a time varying fine structure constant alpha . We have included the above results in a JBD cosmological model modified by J.D. Barrow by including a time varying speed of light, thus, finding an exponential inflationary phase with variables G, alpha and c . This means that the primordial value of alpha was exponentially larger than its present value. Planck`s time may not be then approximately 10 to the power - 43 s ; the same may happen to other Planck`s quantities. We found an exponentially time-decaying Cosmological term.
This paper focuses on the nonlinear Milne problem of the radiative heat transfer system on the half-space. The nonlinear model is described by a second order ODE for temperature coupled to transport equation for radiative intensity. The nonlinearity of the fourth power Stefan-Boltzmann law of black body radiation, bring additional difficulty in mathematical analysis, compared to the well-developed theory for Milne problem of linear transport equation. With the help of the monotonicity property of the second order ODE, we prove the existence of the nonlinear Milne problem on a finite interval using monotonic convergence theorems. Then the solution is extended to the half-space using a uniform weighted estimate and the compactness method. Moreover, the solutions are proved to converge to constants as $x\to \infty$. Therefore, the linear stability analysis is used to study the uniqueness of the nonlinear Milne problem. The existence and uniqueness for the linearized system is established under a spectral assumption on the solution of the nonlinear problem. The spectral assumption is shown to be satisfied when the boundary data is close to the well-prepared case by using a generalized Hardy's inequality. The uniqueness of the solution to the half-line nonlinear Milne problem is established in a neighborhood of solutions satisfying a spectral assumption and the energy estimate.The current work extends the study of Milne problem for linear transport equations and provides a comprehensive study on the nonlinear Milne problem of radiative heat transfer systems.
Stellar evolution models are a cornerstone of young star astrophysics, which necessitates that they yield accurate and reliable predictions of stellar properties. Here, I review the current performance of stellar evolution models against young astrophysical benchmarks and highlight recent progress incorporating non-standard physics, such as magnetic field and starspots, to explain observed deficiencies. While addition of these physical processes leads to improved agreement between models and observations, there are several fundamental limitations in our understanding about how these physical processes operate. These limitations inhibit our ability to form a coherent picture of the essential physics needed to accurately compute young stellar models, but provide rich avenues for further exploration.
The recent observation of charge fractionalization in single Tomanga-Luttinger liquids (TLLs) [Kamata et al., Nature Nanotech., 9 177 (2014)] opens new routes for a systematic investigation of this exotic quantum phenomenon. In this Letter we perform measurements on two adjacent TLLs and put forward an accurate theoretical framework to address the experiments. The theory is based on the plasmon scattering approach and can deal with injected charge pulses of arbitrary shape in TLL regions. We accurately reproduce and interpret the time-resolved multiple fractionalization events in both single and double TLLs. The effect of inter-correlations between the two TLLs is also discussed.
Local aspects of singular F-theory compactifications for SUSY GUT model-building are fairly well understood in terms of Higgs bundles and their spectral data. Several global issues remain, however, including a description of G-fluxes, which are key to constructing chiral matter and stabilizing moduli, and the global realization of U(1) symmetries that can forbid phenomenologically unfavorable couplings. In this paper, we sharpen our earlier proposal for describing G-fluxes through "spectral divisors" and introduce a distinguished "Tate divisor", which can be used to describe both G-flux and U(1)s when present. As an application, we give a general discussion of M5-instanton contributions in the presence of G-flux and exemplify this in a concrete example, where we comment on the ability of instanton induced superpotential couplings to stabilize Kahler moduli.