ShantanuT01/DACTYL-Pretraining huggingface dataset:
We study the gamma p ---> K^+ Lambda(1405) reaction at energies close to threshold using a chiral unitary model where the resonance is generated dynamically from K^-p interaction with other channels constructed from the octets of baryons and mesons. Predictions are made for cross sections into several channels and it is shown that the detection of the K^+ is sufficient to determine the shape and strength of the Lambda(1405) resonance. The determination of the resonance properties in nuclei requires instead the detection of the resonance decay channels. Pauli blocking effects on the resonance, which have been shown to be very important for the resonance at rest in the nucleus, are irrelevant here where the resonance is produced with a large momentum. The nuclear modifications here would thus offer information on the resonance and K^- nucleus dynamics complementary to the one offered so far by K^- atoms.
For cyclic totally real number fields $K$ with odd prime degree $n$, odd class number, $2$ inert, and the property that every totally positive unit is a square, the density of rational primes $p$ that satisfy the spin relation spin$(\mathfrak{p},\sigma)$spin$(\mathfrak{p},\sigma^{-1})=1$ for all $\sigma\neq 1 \in$ Gal$(K/\mathbb{Q})$ where $\mathfrak{p}$ is a prime of $K$ above $p$ is given by the formula \[ D_K=\frac{m_Kn+1}{n2^n} \] where $m_K$ is a computable and bounded invariant of the number field $K$. This formula is modified in the erratum from the original version due to an error in the inert case. As the inert case is insubstantial, the strength of the results is not significantly changed.
We derive a semiclassical transport equation for fermions propagating in the presence of a CP-violating planar bubble wall at a first order electroweak phase transition. Starting from the Kadanoff-Baym (KB) equation for the two-point (Wightman) function we perform an expansion in gradients, or equivalently in the Planck constant h-bar. We show that to first order in h-bar the KB equations have a spectral solution, which allows for an on-shell description of the plasma excitations. The CP-violating force acting on these excitations is found to be enhanced by a boost factor in comparison with the 1+1-dimensional case studied in a former paper. We find that an identical semiclassical force can be obtained by the WKB method. Applications to the MSSM are also mentioned.
The origin of the charge density wave (CDW) in transition metal dichalcognides has been in hot debate and no conclusive agreement has been reached. Here, we propose an ab-initio framework for an accurate description of both Fermi surface nesting and electron-phonon coupling (EPC) and systematically investigate their roles in the formation of CDW. Using monolayer 1H-NbSe$_2$ and 1T-VTe$_2$ as representative examples, we show that it is the momentum-dependent EPC softens the phonon frequencies, which become imaginary (phonon instabilities) at CDW vectors (indicating CDW formation). Besides, the distribution of the CDW gap opening (electron instabilities) can be correctly predicted only if EPC is included in the mean-field model. These results emphasize the decisive role of EPC in the CDW formation. Our analytical process is general and can be applied to other CDW systems.
We analyze an adaptive mesh refinement hydrodynamic cosmological simulation of a Milky Way-sized galaxy to study the cold gas in the halo. HI observations of the Milky Way and other nearby spirals have revealed the presence of such gas in the form of clouds and other extended structures, which indicates on-going accretion. We use a high-resolution simulation (136-272 pc throughout) to study the distribution of cold gas in the halo, compare it with observations, and examine its origin. The amount (10^8 Msun in HI), covering fraction, and spatial distribution of the cold halo gas around the simulated galaxy at z=0 are consistent with existing observations. At z=0 the HI mass accretion rate onto the disk is 0.2 Msun/yr. We track the histories of the 20 satellites that are detected in HI in the redshift interval 0.5>z>0 and find that most of them are losing gas, with a median mass loss rate per satellite of 3.1 x 10^{-3} Msun/yr. This stripped gas is a significant component of the HI gas seen in the simulation. In addition, we see filamentary material coming into the halo from the IGM at all redshifts. Most of this gas does not make it directly to the disk, but part of the gas in these structures is able to cool and form clouds. The metallicity of the gas allows us to distinguish between filamentary flows and satellite gas. We find that the former accounts for at least 25-75% of the cold gas in the halo seen at any redshift analyzed here. Placing constraints on cloud formation mechanisms allows us to better understand how galaxies accrete gas and fuel star formation at z=0.
We present dynamical modeling of the broad line region (BLR) for a sample of five Seyfert 1 galaxies using reverberation mapping data taken by the Lick AGN Monitoring Project in 2008. By modeling the AGN continuum light curve and H$\beta$ line profiles directly we are able to constrain the geometry and kinematics of the BLR and make a measurement of the black hole mass that does not depend upon the virial factor, $f$, needed in traditional reverberation mapping analysis. We find that the geometry of the BLR is generally a thick disk viewed close to face-on. While the H$\beta$ emission is found to come preferentially from the far side of the BLR, the mean size of the BLR is consistent with the lags measured with cross-correlation analysis. The BLR kinematics are found to be consistent with either inflowing motions or elliptical orbits, often with some combination of the two. We measure black hole masses of $\log_{10}(M_{\rm\,BH}/M_\odot)=6.62^{+0.10}_{-0.13}$ for Arp 151, $7.42^{+0.26}_{-0.27}$ for Mrk 1310, $7.51^{+0.23}_{-0.14}$ for NGC 5548, $6.42^{+0.24}_{-0.18}$ for NGC 6814, and $6.99^{+0.32}_{-0.25}$ for SBS 1116+583A. The $f$ factors measured individually for each AGN are found to correlate with inclination angle, although not with $M_{\rm\,BH}$, $L_{5100}$, or FWHM/$\sigma$ of the emission line profile.
We will show that if there exists a quantum query algorithm that exactly computes some total Boolean function f by making T queries, then there is a classical deterministic algorithm A that exactly computes f making O(T^3) queries. The best know bound previously was O(T^4) due to Beals et al.
Face detection has achieved significant progress in recent years. However, high performance face detection still remains a very challenging problem, especially when there exists many tiny faces. In this paper, we present a single-shot refinement face detector namely RefineFace to achieve high performance. Specifically, it consists of five modules: Selective Two-step Regression (STR), Selective Two-step Classification (STC), Scale-aware Margin Loss (SML), Feature Supervision Module (FSM) and Receptive Field Enhancement (RFE). To enhance the regression ability for high location accuracy, STR coarsely adjusts locations and sizes of anchors from high level detection layers to provide better initialization for subsequent regressor. To improve the classification ability for high recall efficiency, STC first filters out most simple negatives from low level detection layers to reduce search space for subsequent classifier, then SML is applied to better distinguish faces from background at various scales and FSM is introduced to let the backbone learn more discriminative features for classification. Besides, RFE is presented to provide more diverse receptive field to better capture faces in some extreme poses. Extensive experiments conducted on WIDER FACE, AFW, PASCAL Face, FDDB, MAFA demonstrate that our method achieves state-of-the-art results and runs at $37.3$ FPS with ResNet-18 for VGA-resolution images.
We show that the standard method of introducing the quantum description of the electromagnetic field -- by canonical field quantization -- is not the only one. We have chosen here the relativistic quantum mechanics of the photon as the starting point. The treatment of photons as elementary particles merges smoothly with the description in terms of the quantized electromagnetic field but it also reveals some essential differences. The most striking result is the appearance of various measures of fidelity for quantum states of photons. These measures are used to characterize the localization of photons.
We analyze the asymptotics of crossing a high piecewise linear barriers by a renewal compound process with the subexponential jumps. The study is motivated by ruin probabilities of two insurance companies (or two branches of the same company) that divide between them both claims and premia in some specified proportions when the initial reserves of both companies tend to infinity.
We show that electron transport in disordered quantum wires can be described by a modified Cooperon equation, which coincides in form with the Dirac equation for the massive fermions in a 1+1 dimensional system. In this new formalism, we calculate the DC electric current induced by electromagnetic fields in quasi-one-dimensional rings. This current changes sign, from diamagnetic to paramagnetic, depending on the amplitude and frequency of the time-dependent external electromagnetic field.
We determine the holographic spectra of scalar mesons from the fluctuations of the embedding of flavor D-brane probes in HQCD models. The models we consider include a generalization of the Sakai Sugimoto model at zero temperature and at the "high-temperature intermediate phase", where the system is in a deconfining phase while admitting chiral symmetry breaking and a non-critical 6d model at zero temperature. All these models are based on backgrounds associated with near extremal N_c D4 branes and a set of N_f<<N_c flavor probe branes that admit geometrical chiral symmetry breaking. We point out that the spectra of these models include a 0^{--} branch which does not show up in nature.   At zero temperature we found that the masses of the mesons M_n depend on the "constituent quark mass" parameter m^c_q and on the excitation number n as M_n^2 m^c_q and M^2_n n^{1.7} for the ten dimensional case and as M_n m^c_q and M_n n^{0.75} in the non-critical case. At the high temperature intermediate phase we detect a decrease of the masses of low spin mesons as a function of the temperature similar to holographic vector mesons and to lattice calculations.
The continuous high-precision photometric observations provided by the CoRoT and Kepler space missions have allowed us to better understand the structure and dynamics of red giants using asteroseismic techniques. A small fraction of these stars shows dipole modes with unexpectedly low amplitudes. The reduction in amplitude is more pronounced for stars with higher frequency of maximum power. In this work we want to characterize KIC 8561221 in order to confirm that it is currently the least evolved star among this peculiar subset and to discuss several hypotheses that could help explain the reduction of the dipole mode amplitudes. We used Kepler short- and long-cadence data combined with spectroscopic observations to infer the stellar structure and dynamics of KIC 8561221. We then discussed different scenarios that could contribute to the reduction of the dipole amplitudes such as a fast rotating interior or the effect of a magnetic field on the properties of the modes. We also performed a detailed study of the inertia and damping of the modes. We have been able to characterize 37 oscillations modes, in particular, a few dipole modes above nu_max that exhibit nearly normal amplitudes. We have inferred a surface rotation period of around 91 days and uncovered the existence of a variation in the surface magnetic activity during the last 4 years. As expected, the internal regions of the star probed by the l = 2 and 3 modes spin 4 to 8 times faster than the surface. With our grid of standard models we are able to properly fit the observed frequencies. Our model calculation of mode inertia and damping give no explanation for the depressed dipole modes. A fast rotating core is also ruled out as a possible explanation. Finally, we do not have any observational evidence of the presence of a strong deep magnetic field inside the star.
In this paper we consider a nonlocal viscous Burgers equation and study the well-posedness and asymptotic behaviour of its solutions. We prove that under the smallness assumption on the initial data the solutions behave as the self similar profiles of the Burgers equation with Dirac mass as the initial datum. The first term in the asymptotic expansion of the solutions is obtained by rescaling the solutions and proving the compactness of their trajectories.
We consider driftless stochastic differential equations and the diffusions starting from the positive half line. It is shown that the Feller test for explosions gives a necessary and sufficient condition to hold pathwise uniqueness for diffusion coefficients that are positive and monotonically increasing or decreasing on the positive half line and the value at the origin is zero. Then, stability problems are studied from the aspect of H\"older-continuity and a generalized Nakao-Le Gall condition. Comparing the convergence rate of H\"older-continuous case, the sharpness and stability of the Nakao-Le Gall condition on Cantor stochastic differential equations is confirmed.Furthermore, using the Malliavin calculus, we construct a smooth solution to degenerate second order Fokker-Planck equations under weak conditions on the coefficients.
We present a factorization formula for the inclusive production of the Higgs boson at large transverse momentum $P_T$ that includes all terms with the leading power of $1/P_T^2$. The cross section is factorized into convolutions of parton distributions, infrared-safe hard-scattering cross sections for producing a parton, and fragmentation functions that give the distribution of the longitudinal momentum fraction of the Higgs relative to the fragmenting parton. The infrared-safe cross sections and the fragmentation functions are perturbatively calculable. The factorization formula enables the resummation of large logarithms of $P_T/M_H$ due to final-state radiation by integrating evolution equations for the fragmentation functions. By comparing the cross section for the process $q\bar{q}\to H t\bar t$ from the leading-power factorization formula at leading order in the coupling constants with the complete leading-order cross section, we infer that the error in the factorization formula decreases to less than 5% for $P_T>600$ GeV at a future $100$ TeV collider.
Since Cho and Kim (2005) showed that the competition graph of a doubly partial order is an interval graph, it has been actively studied whether or not the same phenomenon occurs for other variants of competition graph and interesting results have been obtained. Continuing in the same spirit, we study the competition hypergraph, an interesting variant of the competition graph, of a doubly partial order. Though it turns out that the competition hypergraph of a doubly partial order is not always interval, we completely characterize the competition hypergraphs of doubly partial orders which are interval.
In the search of YM instanton sheaves with topological charge two, the rank of beta matrix in the monad construction can be dropped from the bundle case with rank(beta)= 2 to either rank(beta) = 1 [4] or 0 on some points of CP^3 of the sheaf cases. In this paper, we first show that the sheaf case with rank(beta)= 0 does not exist for the previous construction of SU(2) complex YM instantons [3]. We then show that in the new "extended complex YM instantons" discovered in this paper, rank(beta) can be either 2 on the whole CP^3 (bundle) with some given ADHM data or 1, 0 on some points of CP^3 with other ADHM data (sheaves). These extended SU(2) complex YM instantons have no real instanton counterparts.
The validity of the Weak Equivalence Principle relative to a local inertial frame is detailed in a scalar-vector gravitation model with Lorentz-Poincar\'e type interpretation. Given the previously established first Post-Newtonian concordance of dynamics with General Relativity, the principle is to this order compatible with GRT. The gravitationally modified Lorentz transformations, on which the observations in physical coordinates depend, are shown to provide a physical interpretation of \emph{parallel transport}. A development of ``geodesic'' deviation in terms of the present model is given as well.
We study the flavor changing t -> c H^0 decay in the framework of the general two Higgs doublet model, so called model III. Here, we take the Yukawa couplings complex and switch on the CP violating effects. We predict the branching ratio six orders larger compared to the one calculated in the SM, namely BR ~ 10^{-7}, and observe a measurable CP asymmetry, at the order of 10^{-2}.
We propose a method to produce a definite number of ground-state atoms by adiabatic reduction of the depth of a potential well that confines a degenerate Bose gas with repulsive interactions. Using a variety of methods, we map out the maximum number of particles that can be supported by the well as a function of the well depth and interaction strength, covering the limiting case of a Tonks gas as well as the mean-field regime. We also estimate the time scales for adiabaticity and discuss the recent observation of atomic number squeezing (Chuu et al., Phys. Rev. Lett. {\bf 95}, 260403 (2005)).
The temperature driven segregation of Cr to the surface of the tungsten-based WCrY alloy is analysed with low energy ion scattering of He+ ions with an energy of 1 keV in the temperature range from room temperature to 1000 K. Due to the high surface sensitivity, these measurements probe only the composition of the outermost monolayer. The surface concentration of Cr increases slightly when the temperature of the sample is increased up to 700 K and exhibits a much stronger increase when the sample temperature is further raised. The segregation enthalpy for Cr is obtained from the Langmuir-McLean relation and amounts to 0.7 eV. The surface concentration of Y shows a similar behaviour to the Cr concentration. The temperature thresholds between slow and accelerated surface density increases for Cr and Y are nearly the same. At a temperature of 1000 K the low energy ion scattering detects almost no W on the surface. The modified surface composition due to the segregated species, i.e. the mixed Cr/Y layer, stays stable during cool-down of the sample. Preferential sputtering is investigated using ion bombardment of 250 eV D atoms, resulting in an increase of the W surface density at room temperature. This effect is counteracted at elevated temperatures where segregation replenishes the lighter elements on the surface and prevents the formation of an all-W surface layer. The flux of segregating Cr atoms towards the surface is evaluated from the equilibrium between sputter erosion and segregation.
One of the greatest challenges in interpreting the pulsations of rapidly rotating stars is mode identification, i.e. correctly matching theoretical modes to observed pulsation frequencies. Indeed, the latest observations as well as current theoretical results show the complexity of pulsation spectra in such stars, and the lack of easily recognisable patterns. In the present contribution, the latest results on non-adiabatic effects in such pulsations are described, and we show how these come into play when identifying modes. These calculations fully take into account the effects of rapid rotation, including centrifugal distortion, and are based on models from the ESTER project, currently the only rapidly rotating models in which the energy conservation equation is satisfied, a prerequisite for calculating non-adiabatic effects. Non-adiabatic effects determine which modes are excited and play a key role in the near-surface pulsation-induced temperature variations which intervene in multi-colour amplitude ratios and phase differences, as well as line profile variations.
We study RXTE PCA data for the high mass X-ray binary source SMC X-1 between 2003-10 and 2003-12 when the source was in high states. The source is found to be frequently bursting which can be seen as flares in lightcurves on an average of one in every 800 s, with an average of 4-5 X-ray burst per hour of type II. We note that typically burst was short lasting for few tens of seconds in addition few long bursts of more than hundred seconds were also observed. The flares apparently occupied 2.5$\%$ of the total observing time of 225.5 ks. We note a total of 272 flares with mean FWHM of the flare $\backsim$21 s. The rms variability and the aperiodic variability are independent of flares. As observed the pulse profiles of the lightcurves do not change its shape implying that there is no change in the geometry of accretion disk due to burst. The hardness ratio and the rms variability of lightcurves show no correlation with the flares. The flare-fraction shows a positive correlation with the peak-to-peak ratio of the primary and secondary peaks of the pulse profile. The observed hardening or the softening of the spectrum cannot be correlated with the flaring rate but may be due to the interstellar absorption of X-rays as evident from the change in the hydrogen column density ($n_{H}$). It is found that the luminosity of the source increases with the flaring rate. Considering the viscous timescale equal to mean recurrence time of flares we fixed the viscosity parameter $\alpha$ $\backsim$ 0.16.
The mass of unresolved young star clusters derived from spectro-photometric data may well be off by a factor of 2 or more once the migration of massive stars driven by mass segregation is accounted for. We quantify this effect for a large set of cluster parameters, including variations in the stellar IMF, the intrinsic cluster mass, and mean mass density. Gas-dynamical models coupled with the Cambridge stellar evolution tracks allow us to derive a scheme to recover the real cluster mass given measured half-light radius, one-dimensional velocity dispersion and age. We monitor the evolution with time of the ratio of real to apparent mass through the parameter eta. When we compute eta for rich star clusters, we find non-monotonic evolution in time when the IMF stretches beyond a critical cutoff mass of 25.5 solar mass. We also monitor the rise of color gradients between the inner and outer volume of clusters: we find trends in time of the stellar IMF power indices overlapping well with those derived for the LMC cluster NGC 1818 at an age of 30 Myr. We argue that the core region of massive Antennae clusters should have suffered from much segregation despite their low ages. We apply these results to a cluster mass function, and find that the peak of the mass distribution would appear to observers shifted to lower masses by as much as 0.2 dex. The star formation rate (SFR) derived for the cluster population is then underestimated by from 20 to 50 per cent.
We consider in this work the electromagnetic current for a system composed by two charged bosons and show that it has a structure of many bodies even in the impulse approximation, when described in the light front time $x^+$. In terms of the two-body component for the bound state, the current contains two-body operators. We discuss the process of pair creation from the interacting photon and interpret it as a zero mode contribution to the current and its consequences for the components of currents in the light-front.