ShantanuT01/DACTYL-Pretraining huggingface dataset:
A finite non-classical framework for physical theory is described which challenges the conclusion that the Bell Inequality has been shown to have been violated experimentally, even approximately. This framework postulates the universe as a deterministic locally causal system evolving on a measure-zero fractal-like geometry $I_U$ in cosmological state space. Consistent with the assumed primacy of $I_U$, and $p$-adic number theory, a non-Euclidean (and hence non-classical) metric $g_p$ is defined on cosmological state space, where $p$ is a large but finite Pythagorean prime. Using number-theoretic properties of spherical triangles, the inequalities violated experimentally are shown to be $g_p$-distant from the CHSH inequality, whose violation would rule out local realism. This result fails in the singular limit $p=\infty$, at which $g_p$ is Euclidean. Broader implications are discussed.
AGILE (Astrorivelatore Gamma a Immagini LEggero) is an Italian Space Agency (ASI) mission launched on April 23rd, 2007. The AGILE-GRID instrument onboard of the AGILE satellite is devoted to gamma-ray astrophysics in the 30 MeV - 50 GeV energy range. This paper presents the results of a systematic study performed on the first three years of AGILE-GRID data to search for GeV and sub-GeV counterparts (or derive flux upper limits) of sources detected at very high-energy by TeV experiments. Many of the TeV sources are still unidentified and deep observations at lower energies are needed to identify their possible counterparts.
We associate to each algebraic variety defined over $\mathbb{R}$ a filtered cochain complex, which computes the cohomology with compact supports and $\mathbb{Z}\_2$-coefficients of the set of its real points. This filtered complex is additive for closed inclusions and acyclic for resolution of singularities, and is unique up to filtered quasi-isomorphism. It is represented by the dual filtration of the geometric filtration on semialgebraic chains with closed supports defined by McCrory and Parusi\'nski, and leads to a spectral sequence which computes the weight filtration on cohomology with compact supports. This spectral sequence is a natural invariant which contains the additive virtual Betti numbers. We then show that the cross product of two varieties allows us to compare the product of their respective weight complexes and spectral sequences with those of their product, and prove that the cup and cap products in cohomology and homology are filtered with respect to the real weight filtrations.
Modelling of adiabatic gravity wave propagation in the solar atmosphere showed that mode conversion to field guided acoustic waves or Alfv\'en waves was possible in the presence of highly inclined magnetic fields. This work aims to extend the previous adiabatic study, exploring the consequences of radiative damping on the propagation and mode conversion of gravity waves in the solar atmosphere. We model gravity waves in a VAL-C atmosphere, subject to a uniform, and arbitrarily orientated magnetic field, using the Newton cooling approximation for radiatively damped propagation. The results indicate that the mode conversion pathways identified in the adiabatic study are maintained in the presence of damping. The wave energy fluxes are highly sensitive to the form of the height dependence of the radiative damping time. While simulations starting from 0.2 Mm result in modest flux attenuation compared to the adiabatic results, short damping times expected in the low photosphere effectively suppress gravity waves in simulations starting at the base of the photosphere. It is difficult to reconcile our results and observations of propagating gravity waves with significant energy flux at photospheric heights unless they are generated in situ, and even then, why they are observed to be propagating as low as 70 km where gravity waves should be radiatively overdamped.
We study the late time behavior of the boundary state representing the rolling tachyon constructed by Sen. It is found that the coupling of the rolling tachyon to massive modes of the closed string grows exponentially as the system evolves. We argue that the description of rolling tachyon by a boundary state is valid during the finite time determined by string coupling, and that energy could be dissipated to the bulk beyond this time. We also comment on the relation between the rolling tachyon boundary state and the spacelike D-brane boundary state.
A month-long observation of two horizontal ZnS(Ag) scintillating screens, 1 m^2 in area and located one above the other a certain distance apart, revealed about 10 correlated signals, whose time shift corresponds to an average velocity of only ~10-15 km/s. We assign the origin of these signals to the negative daemons, i.e. electrically charged Planckian particles, which supposedly form a part of the DM in the Galactic disk and were captured into the near-Earth orbits. The estimated flux of daemons is >=10^-4 m^-2 s^-1. The key part in the detection of daemons is played apparently by two processes: (i) the daemon shedding the captured heavy nucleus in a few tens of mks as a result of a relatively rapid decay of the daemon-containing nucleons, and (ii) emission of numerous Auger electrons and nuclear particles occurring in the next capture or recapture of a (heavier) nucleus by the daemon.
We show that the formalism commonly used to implement Bose-Einstein correlations in Monte-Carlo simulations can lead to values of the two-particle correlator significantly smaller than unity, in the case of sources with strong position-momentum correlations. This is more pronounced when the phase space of the emitted particles is strongly reduced by experimental acceptance or kinematic analysis selections. It is inconsistent with general principles according to which the Bose-Einstein correlator is larger than unity. This inconsistency seems to be rooted in the fact that quantum mechanical localization properties are not taken into account properly.
We have identified an optical/X-ray binary with orbital period P_b=5.47h as the likely counterpart of the Fermi source 2FGL J2039.6-5620. GROND, SOAR and DES observations provide an accurate orbital period and allow us to compare with the light curve of an archival XMM exposure. Like many short-period optical X-ray binaries associated with LAT sources this may be a interacting (black widow/redback) millisecond pulsar binary. The X-ray light curve is consistent with the emission associated with an intrabinary shock. The optical light curve shows evidence of companion heating, but has a peculiar asymmetric double peak. The nature of this optical structure is not yet clear; additional optical studies and, especially, detection of an orbital modulation in a gamma-ray pulsar are needed to elucidate the nature of this peculiar source.
We study when a non--local unitary operation acting on two $d$--level systems can probabilistically simulate another one when arbitrary local operations and classical communication are allowed. We provide necessary and sufficient conditions for the simulation to be possible. Probabilistic interconvertability is used to define an equivalence relation between gates. We show that this relation induces a finite number of classes, that we identify. In the case of two qubits, two classes of non--local operations exist. We choose the CNOT and SWAP as representatives of these classes. We show how the CNOT [SWAP] can be deterministically converted into any operation of its class. We also calculate the optimal probability of obtaining the CNOT [SWAP] from any operation of the corresponding class and provide a protocol to achieve this task.
We employ a long XMM-Newton observation of the core of the Perseus cluster to validate claims of a non-thermal component discovered with Chandra. From a meticulous analysis of our dataset, which includes a detailed treatment of systematic errors, we find the 2-10 keV surface brightness of the non-thermal component to be smaller than about 5x10^-16 erg cm^-2s^-1arcsec^-2. The most likely explanation for the discrepancy between the XMM-Newton and Chandra estimates is a problem in the effective area calibration of the latter. Our EPIC based magnetic field lower limits are not in disagreement with Faraday rotation measure estimates on a few cool cores and with a minimum energy estimate on Perseus. In the not too distant future Simbol-X may allow detection of non-thermal components with intensities more than 10 times smaller than those that can be measured with EPIC; nonetheless even the exquisite sensitivity within reach for Simbol-X might be insufficient to detect the IC emission from Perseus.
In 2018, the ESA \Gaia\ satellite discovered a remarkable spiral pattern ("phase spiral") in the $z-V_z$ phase plane throughout the solar neighbourhood, where $z$ and $V_z$ are the displacement and velocity of a star perpendicular to the Galactic disc. In response to Binney \& Sch\"onrich's analytic model of a disc-crossing satellite to explain the \Gaia\ data, we carry out a high-resolution, N-body simulation (N$\:\approx 10^8$ particles) of an impulsive mass ($2\times 10^{10}$ \Msun) that interacts with a cold stellar disc at a single transit point. The disc response is complex since the impulse triggers a superposition of two distinct bisymmetric ($m=2$) modes $-$ a density wave and a corrugated bending wave $-$ that wrap up at different rates. Stars in the {\it faster} density wave wrap up with time $T$ according to $\phi_D(R,T)=(\Omega_D(R) + \Omega_{\rm o})\:T$ where $\phi_D$ describes the spiral pattern and $\Omega_D =\Omega(R) -\kappa(R)/2$, where $\kappa$ is the epicyclic frequency. While the pattern speed $\Omega_{\rm o}$ is small, it is non-zero. The {\it slower} bending wave wraps up according to $\Omega_B\approx\Omega_D/2$ producing a corrugated wave. The bunching effect of the density wave triggers the phase spiral as it rolls up and down on the bending wave ("rollercoaster" model). The phase spiral emerges slowly about $\Delta T \approx 400$ Myr after impact. It appears to be a long-lived, disc-wide phenomenon that continues to evolve over most of the 2~Gyr simulation. Thus, given Sagittarius' (Sgr) low total mass today ($M_{\rm tot}\sim 3\times 10^8$ \Msun\ within 10 kpc diameter), we believe the phase spiral was excited by the disc-crossing dwarf some $1-2$ Gyr {\it before} the recent transit. For this to be true, Sgr must be losing mass at 0.5-1 dex per orbit loop.
We show that the recent world-sheet analysis of the quantum fluctuations of a short flux tube in type II string theory leads to a simple and precise description of a pair of stuck D0branes in an orientifold compactification of the type I' string theory. The existence of a stable type I' flux tube of sub-string-scale length is a consequence of the confinement of quantized flux associated with the scalar dualized ten-form background field strength *F_{10}, evidence for a -2brane in the BPS spectrum of M theory. Using heterotic-type I duality, we infer the existence of an M2brane of finite width O(\sqrt{\alpha'}) in M-theory, the strong coupling resolution of a spacetime singularity in the D=9 twisted and toroidally compactified E_8 x E_8 heterotic string. This phenomenon has a bosonic string analog in the existence of a stable short electric flux tube arising from the confinement of photons due to tachyon field dynamics. The appendix clarifies the appearance of nonperturbative states and enhanced gauge symmetry in toroidal compactifications of the type I' string. We account for all of the known disconnected components of the moduli space of theories with sixteen supercharges, in striking confirmation of heterotic-type I duality.
Starting from a realistic one--boson--exchange--model fitted to the amplitudes of elastic nucleon--nucleon scattering and the process $NN\rightarrow N\Delta$ we perform a fully relativistic and gauge invariant calculation for the dilepton production in nucleon--nucleon collisions, including the important effect of propagating the $\Delta$--resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic formfactors for the hadrons in our calculations without loosing gauge--invariance and discuss their influence on dilepton spectra.
In this paper, we study the gravitational wave polarization modes for some particular $f(R)$ models using Newman-Penrose formalism. We find two extra scalar modes of gravitational wave (longitudinal and transversal modes) in addition to two tensor modes of general relativity. We conclude that gravitational waves correspond to class $II_{6}$ under the Lorentz-invariant E(2) classification of plane null waves for these $f(R)$ models.
Cosmological hydrodynamical simulations are studied in order to analyse generic trends for the stellar, baryonic and halo mass assembly of low-mass galaxies (M_* < 3 x 10^10 M_sun) as a function of their present halo mass, in the context of the Lambda-CDM scenario and common subgrid physics schemes. We obtain that smaller galaxies exhibit higher specific star formation rates and higher gas fractions. Although these trends are in rough agreement with observations, the absolute values of these quantities tend to be lower than observed ones since z~2. The simulated galaxy stellar mass fraction increases with halo mass, consistently with semi-empirical inferences. However, the predicted correlation between them shows negligible variations up to high z, while these inferences seem to indicate some evolution. The hot gas mass in z=0 halos is higher than the central galaxy mass by a factor of ~1-1.5 and this factor increases up to ~5-7 at z~2 for the smallest galaxies. The stellar, baryonic and halo evolutionary tracks of simulated galaxies show that smaller galaxies tend to delay their baryonic and stellar mass assembly with respect to the halo one. The Supernova feedback treatment included in this model plays a key role on this behaviour albeit the trend is still weaker than the one inferred from observations. At z>2, the overall properties of simulated galaxies are not in large disagreement with those derived from observations.
We study the Mott transition as a function of interaction strength in the half-filled Hubbard chain with next-nearest-neighbor hopping t' by calculating the response to an external electric field using the Density Matrix Renormalization Group. The electric susceptibility chi diverges when approaching the critical point from the insulating side. We show that the correlation length xi characterizing this transition is directly proportional to fluctuations of the polarization and that chi ~ xi^2. The critical behavior shows that the transition is infinite-order for all t', whether or not a spin gap is present, and that hyperscaling holds.
The cross section of the reaction $^3$He$(\gamma,pn)p_{spec}$ in the energy range 150 - 450 MeV has been calculated in a quasifree two-body model and compared with a recent kinematically complete experiment. In comparison with free deuteron disintegration the cross section is increased by a factor of about 1.5 in reasonable agreement with the data for photon energies above 200 MeV. At lower energies the data deviate from the two-body behaviour and thus suggest a more important role of the spectator requiring a more exact treatment.
In this paper we prove the existence, regularity and symmetry of a ground state for a nonlinear equation in the whole space, involving a pseudo-relativistic Schr\"odinger operator.
In this paper, we study two Energy Balance Models with Memory arising in climatology, which consist in a 1D degenerate nonlinear parabolic equation involving a memory term, and possibly a set-valued reaction term (of Sellers type and of Budyko type, in the usual terminology). We provide existence and regularity results, and obtain uniqueness and stability estimates that are useful for the determination of the insolation function in Sellers' model with memory.
We present a new method of solving the probability distribution for baryons, antibaryons and mesons at the hadronization of constituent quark and antiquark system. The hadronization is governed by the quark combination rule in the quark combination model developed by the Shandong Group. We use the method of the generating function to derive the outcome of the quark combination rule, which is much simpler and easier to be generalized than the original method. Furthermore, we use the formula of the quark combination rule and its generalization to study the property of multiplicity distribution of net-protons. Taking a naive case of quark number fluctuations and correlations at hadronization, we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potential applicability of quark combination model in studying hadronic multiplicity fluctuations and the underlying phase transition property in relativistic heavy-ion collisions.
We propose a method for setting upper limits to the extragalactic background light (EBL). Our method uses simultaneous {\em Fermi}-LAT and ground-based TeV observations of blazars and is based on the assumption that the intrinsic spectral energy distribution (SED) of TeV blazars lies below the extrapolation of the {\em Fermi}-LAT SED from GeV to TeV energies. By extrapolating the {\em Fermi}-LAT spectrum, which for TeV blazars is practically unattenuated by photon-photon pair production with EBL photons, a firm upper limit on the intrinsic SED at TeV energies is provided. The ratio of the extrapolated spectrum to the observed TeV spectrum provides upper limits to the optical depth for the propagation of the TeV photons due to pair production on the EBL, which in turn sets firm upper limits to EBL models. We demonstrate our method using simultaneous observations from {\em Fermi}-LAT and ground-based TeV telescopes of the blazars \object{PKS 2155-304} and \object{1ES 1218+304}, and show that high EBL density models are disfavored. We also discuss how our method can be optimized and how {\em Fermi} and X-ray monitoring observations of TeV blazars can guide future TeV campaigns, leading to potentially much stronger constraints on EBL models.
This paper is concerned with the Fokker-Planck (FP) description of classical stochastic systems with discrete time delay. The non-Markovian character of the corresponding Langevin dynamics naturally leads to a coupled infinite hierarchy of FP equations for the various $n$-time joint distribution functions. Here we present a novel approach to close the hierarchy at the one-time level based on a linearization of the deterministic forces in all members of the hierarchy starting from the second one. This leads to a closed equation for the one-time probability density in the steady state. Considering two generic nonlinear systems, a colloidal particle in a sinusoidal or bistable potential supplemented by a linear delay force, we demonstrate that our approach yields a very accurate representation of the density as compared to quasi-exact numerical results from direct solution of the Langevin equation. Moreover, the results are significantly improved against those from a small-delay approximation and a perturbation-theoretical approach. We also discuss the possibility of accessing transport-related quantities, such as escape times, based on an additional Kramers approximation. Our approach applies to a wide class of models with nonlinear deterministic forces.
Using self dual Ashtekar variables, we investigate (at the effective level) the spherically symmetry reduced model of loop quantum gravity, both in vacuum and when coupled to a scalar field. Within the real Ashtekar-Barbero formulation, the system scalar field coupled to spherically symmetric gravity is known to possess a non closed (quantum) algebra of constraints once the holonomy corrections are introduced, which forbids the loop quantization of the model. Moreover, the vacuum case, while not anomalous, introduces modifications which are usually interpreted as an effective signature change of the metric in the deep quantum region. We show in this paper that both those complications disappear when working with self dual Ashtekar variables, both in the vacuum case and in the case of gravity minimally coupled to a scalar field. In this framework, the algebra of the holonomy corrected constraints is anomaly free and reproduces the classical hypersurface deformation algebra without any deformations. A possible path towards quantization of this model is briefly discussed.
Exploiting the similarity between the bunched single-particle energy levels of nuclei and of random distributions around the Fermi surface, pairing properties of the latter are calculated to establish statistically-based bounds on the basic characteristics of the pairing phenomenon. When the most probable values for the pairing gaps germane to the BCS formalism are used to calculate thermodynamic quantities, we find that while the ratio of the critical temperature Tc to the zero-temperature pairing gap is close to its BCS Fermi gas value, the ratio of the superfluid to the normal phase specific heats at Tc differs significantly from its Fermi gas counterpart. The largest deviations occur when a few levels lie closely on either side of the Fermi energy but other levels are far away from it. The influence of thermal fluctuations, expected to be large for systems of finite number of particles, were also investigated using a semiclassical treatment of fluctuations. When the average pairing gaps along with those differing by one standard deviations are used, the characteristic discontinuity of the specific heat at Tc in the BCS formalism was transformed to a shoulder-like structure indicating the suppression of a second order phase transition as experimentally observed in nano-particles and several nuclei. Contrasting semiclassical and quantum treatments of fluctuations for the random spacing model is currently underway.
This is a survey article on the theory of lattice points in large planar domains and bodies of dimensions 3 and higher, with an emphasis on recent developments and new methods, including a lot of results established only during the last few years. It deals with the classic circle and sphere problems, as well as with the present state-of-the-art concerning lattice points in more general regions and bodies. Furthermore, a thorough account is given on divisor problems and related arithmetic functions.
Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu$_{2-x}$Fe$_{x}$Si$_{2}$ single crystals for various values of the Fe concentration $x$ in both the hidden order (HO) and large moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. For Fe concentrations near the boundary between the HO and LMAFM phases at $x_c$ ~ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase. These two features have not been observed in other measurements such as specific heat or neutron scattering. In addition, the uniaxial pressure derivative of the transition temperature, based on a calculation using thermal expansion and specific heat data, changes dramatically when crossing from the HO to the LMAFM phase.
Refereed version to appear in Michigan Mathematical Journal. A mistake in the last section of the previous version has been corrected. The new title exactly describes the main result obtained. Building on the geometry of cubic surfaces and on a theorem of Dolgachev, the rationality of the moduli space R mentioned in the title is proved. Let M be the moduli space of 6 points in the plane, modulo the natural involution induced by double-six configurations on cubic surfaces. It is proved that R is birational to a tower of locally trivial projective bundles ending onto M. The rationality of R then follows from Dolgachev's theorem that M is rational.