# Top arXiv papers

• We explore spacetime symmetries and topologies of the two metric sectors in Hassan-Rosen bimetric theory. We show that, in vacuum, the two sectors can either share or have separate spacetime symmetries. If stress-energy tensors are present, a third case can arise, with different spacetime symmetries within the same sector. This raises the question of the best definition of spacetime symmetry in Hassan-Rosen bimetric theory. We emphasize the possibility of imposing ansätze and looking for solutions having different Killing vector fields or different isometries in the two sectors, which has gained little attention so far. We also point out that the topology of spacetime imposes a constraint on possible metric combinations.
• We study the nucleon electromagnetic form factors (EM FFs) using a recently developed method combining Chiral Effective Field Theory ($\chi$EFT) and dispersion analysis. The spectral functions on the two-pion cut at $t > 4 M_\pi^2$ are constructed using the elastic unitarity relation and an $N/D$ representation. $\chi$EFT is used to calculate the real functions $J_\pm^1 (t) = f_\pm^1(t)/F_\pi(t)$ (ratios of the complex $\pi\pi \rightarrow N \bar N$ partial-wave amplitudes and the timelike pion FF), which are free of $\pi\pi$ rescattering. Rescattering effects are included through the empirical timelike pion FF $|F_\pi(t)|^2$. The method allows us to compute the isovector EM spectral functions up to $t \sim 1$ GeV$^2$ with controlled accuracy (LO, NLO, and partial N2LO). With the spectral functions we calculate the isovector nucleon EM FFs and their derivatives at $t = 0$ (EM radii, moments) using subtracted dispersion relations. We predict the values of higher FF derivatives with minimal uncertainties and explain their collective behavior. We estimate the individual proton and neutron FFs by adding an empirical parametrization of the isoscalar sector. Excellent agreement with the present low-$Q^2$ FF data is achieved up to $\sim$0.5 GeV$^2$ for $G_E$, and up to $\sim$0.2 GeV$^2$ for $G_M$. Our results can be used to guide the analysis of low-$Q^2$ elastic scattering data and the extraction of the proton charge radius.
• Measuring and calibrating relations between cluster observables is critical for resource-limited studies. The mass-richness relation of clusters offers an observationally inexpensive way of estimating masses. Its calibration is essential for cluster and cosmological studies, especially for high-redshift clusters. Weak gravitational lensing magnification is a promising and complementary method to shear studies, that can be applied at higher redshifts. We employed the weak lensing magnification method to calibrate the mass-richness relation up to a redshift of 1.4. We used the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS) galaxy cluster candidates ($0.2<z<1.4$) and optical data from the Canada France Hawaii Telescope (CFHT) to test whether magnification can be effectively used to constrain the mass of high-redshift clusters. Lyman-Break Galaxies (LBGs) selected using the $u$-band dropout technique and their colours were used as a background sample of sources. LBG positions were cross-correlated with the centres of the sample of SpARCS clusters to estimate the magnification signal measured for cluster sub-samples, binned in both redshift and richness. We detected a weak lensing magnification signal for all bins at a detection significance of 2.6-5.5$\sigma$. In particular, the significance of the measurement for clusters with $z>1.0$ is 4.1$\sigma$; for the entire cluster sample we obtained an average M$_{200}$ of $1.28^{+0.23}_{-0.21}$ $\times 10^{14} \, \textrm{M}_{\odot}$. Our measurements demonstrated the feasibility of using weak lensing magnification as a viable tool for determining the average halo masses for samples of high redshift galaxy clusters. The results also established the success of using galaxy over-densities to select massive clusters at $z > 1$. Additional studies are necessary for further modelling of the various systematic effects we discussed.
• The C III] 1907,1909 emission doublet has been proposed as an alternative to Lyman-alpha in redshift confirmations of galaxies at z > 6 since it is not attenuated by the largely neutral intergalactic medium at these redshifts and is believed to be strong in the young, vigorously star-forming galaxies present at these early cosmic times. We present a statistical sample of 17 C III]-emitting galaxies beyond z~1.5 using 30 hour deep VLT/MUSE integral field spectroscopy covering 2 square arcminutes in the Hubble Deep Field South (HDFS) and Ultra Deep Field (UDF), achieving C III] sensitivities of ~2e-17 erg/s/cm^2 in the HDFS and ~7e-18 erg/s/cm^2 in the UDF. The rest-frame equivalent widths range from 2 to 19 Angstroms. These 17 galaxies represent ~3% of the total sample of galaxies found between 1.5 < z < 4. They also show elevated star formation rates, lower dust attenuation, and younger mass-weighted ages than the general population of galaxies at the same redshifts. Combined with deep slitless grism spectroscopy from the HST/WFC3 in the UDF, we can tie the rest-frame ultraviolet C III] emission to rest-frame optical emission lines, namely [O III] 5007, finding a strong correlation between the two. Down to the flux limits that we observe (~1e-18 erg/s/cm^2 with the grism data in the UDF), all objects with a rest-frame [O III] 4959,5007 equivalent width in excess of 250 Angstroms, the so-called Extreme Emission Line Galaxies, have detections of C III] in our MUSE data. More detailed studies of the C III]-emitting population at these intermediate redshifts will be crucial to understand the physical conditions in galaxies at early cosmic times and to determine the utility of C III] as a redshift tracer.
• Thermal emission spectra of exoplanets provide constraints on the chemical compositions, pressure-temperature (P-T) profiles, and energy transport in exoplanetary atmospheres. Accurate inferences of these properties rely on the robustness of the atmospheric retrieval methods employed. While extant retrieval codes have provided significant constraints on molecular abundances and temperature profiles in several exoplanetary atmospheres, the constraints on their deviations from thermal and chemical equilibria have yet to be fully explored. Our present work is a step in this direction. We report HyDRA, a disequilibrium retrieval framework for thermal emission spectra of exoplanetary atmospheres. The retrieval code uses the standard architecture of a parametric atmospheric model coupled with Bayesian statistical inference using the Nested Sampling algorithm. For a given dataset, the retrieved compositions and P-T profiles are used in tandem with the GENESIS self-consistent atmospheric model to constrain layer-by-layer deviations from chemical and radiative-convective equilibrium in the observable atmosphere. We demonstrate HyDRA on the Hot Jupiter WASP-43b with a high-precision emission spectrum. We retrieve an H2O mixing ratio of log(H_2O) = -3.54^+0.82_-0.52, consistent with previous studies. We detect H2O and a combined CO/CO2 at 8-sigma significance. We find the dayside P-T profile to be consistent with radiative-convective equilibrium within the 1-sigma limits and with low day-night redistribution, consistent with previous studies. The derived compositions are also consistent with thermochemical equilibrium for the corresponding distribution of P-T profiles. In the era of high precision and high resolution emission spectroscopy, HyDRA provides a path to retrieve disequilibrium phenomena in exoplanetary atmospheres.
• Construction of silicon neutron interferometers requires a perfect crystal silicon ingot (5 cm to 30 cm long) be machined such that Bragg diffracting "blades" protrude from a common base. Leaving the interferometer blades connected to the same base preserves Bragg plane alignment, but if the interferometer contains crystallographic misalignments of greater than about 10 nrad between the blades, interference fringe visibility begins to suffer. Additionally, the parallelism, thickness, and distance between the blades must be machined to micron tolerances. Traditionally, interferometers do not exhibit usable interference fringe visibility until 30 $\mu$m to 60 $\mu$m of machining surface damage is chemically etched away. However, if too much material is removed, the uneven etch rates across the interferometer cause the shape of the crystal blades to be outside of the required tolerances. As a result, the ultimate interference fringe visibility varies widely among neutron interferometers that are created under similar conditions. We find that annealing a previously etched interferometer at $800^\circ \mathrm{C}$ dramatically increased interference fringe visibility from 23 % to 90 %. The Bragg plane misalignments were also measured before and after annealing using neutron rocking curve interference peaks, showing that Bragg plane alignment was improved across the interferometer after annealing. This suggests that current interferometers with low fringe visibility may be salvageable and that annealing may become an important step in the fabrication process of future neutron interferometers, leading to less need for chemical etching and larger, more exotic neutron interferometers.
• First and second order non-equilibrium thermodynamics are studied in the context of particle creation mechanism for homogeneous and isotropic FLRW model and a general formulation of the emergent scenario is investigated. Finally, the stability of the non-equilibrium thermodynamics is examined.
• In this paper, we study the $P-V$ criticality of a specific charged AdS type black hole (SBH) in $f(R)$ gravity coupled with Yang-Mills field. In the extended phase space, we treat the cosmological constant as a thermodynamic pressure. After we study the various thermodynamical quantities, we show that the thermodynamic properties of the SBH behave as a van der Waals liquid-gas system at the critical points and there is a first order phase transition between small-large SBH.
• The paper deals with an extensive study of null and timelike geodesics in the background of wormhole geometries. Starting with a spherically symmetric spacetime, null geodesics are analyzed for the Morris-Thorne wormhole(WH) and photon spheres are examined in WH geometries. Both bounded and unbounded orbits are discussed for timelike geodesics. Similar analysis has been done for trajectories in a dynamic spherically symmetric WH and rotating WH. Finally, invariant angle method of Rindler and Ishak has been used to calculate the angle between radial and tangential vectors at any point on the photon's trajectory.
• Partial differential equations (PDE) are often dependent on input quantities which are inherently uncertain. To quantify this uncertainty these PDEs must be solved over a large ensemble of parameters. Even for a single realization this can a computationally intensive process. In the case of flows governed by the Navier-Stokes equation, a method has been devised for computing an ensemble of solutions. Recently a reduced order model derived from a proper orthogonal decomposition (POD) was incorporated into the ensemble algorithm. Although the ensemble-POD method was successful in the numerical simulation of laminar flows, it yields numerical inaccuracies for convection-dominated flows. In this work we put forth a regularized model, the Leray ensemble-POD model, for the numerical simulation of convection-dominated flows. The Leray ensemble-POD model employs spatial filtering to smooth (regularize) the convection term in the Navier-Stokes. For the new Leray ensemble-POD algorithm, we also propose a numerical discretization with better stability properties than those of the numerical scheme for the standard ensemble-POD method. For this new numerical discretization, we prove its stability and convergence. Furthermore, we show that the Leray ensemble-POD method is more accurate than the standard ensemble-POD method in the numerical simulation of a two-dimensional flow between two offset circles.
• We report $^{23}$Na nuclear magnetic resonance (NMR) measurements of the Mott insulator with strong spin-orbit interaction Ba$_{2}$NaOsO$_{6}$ as a function of temperature in different magnetic fields ranging from 7 T to 29 T. The measurements, intended to concurrently probe spin and orbital/lattice degrees of freedom, are an extension of our work at lower fields reported in Nat. Commun., v 8, 14407 (2017). We have identified clear quantitative NMR signatures that display the appearance of a canted ferromagnetic phase, which is preceded by local point symmetry breaking. We have compiled the field temperature phase diagram extending up to 29 T. We find that the broken local point symmetry phase extends over a wider temperature range as magnetic field increases.
• Supervisor localization procedure can be employed to construct local controllers corresponding to component agents in discrete-event systems. This proposed method in [11] is based on state reduction of a monolithic supervisor with respect to each set of controllable events corresponding to each component agent. A supervisor is localizable if state cardinality can be reduced from the reduced supervisor to each local controller. Although event reduction is an important property, the original supervisor localization procedure did not guarantee event reduction in each local controller comparing to the reduced supervisor. In this paper, we propose a method to localize a supervisor with event reduction in each local controller comparing to the reduced supervisor. State reduction facilitates the implementation of local controllers on industrial systems, whereas event reduction reduces communication traffic between each pair of local controllers.
• We describe the macroscopic behavior of evolutions by crystalline curvature of planar sets in a chessboard--like medium, modeled by a periodic forcing term. We show that the underlying microstructure may produce both pinning and confinement effects on the geometric motion.
• The longstanding notion of stripe incommensurability being proportional to doping, \delta(x) ~ x, in lanthanum transition-metal oxides, La_2-xSr_xTmO_4 (Tm = Cu, Ni, Co), is partly borne out by experiment but also plagued with exceptions. Future neutron-scattering experiments on cobaltates could provide a clear distinction whether a linear or square-root dependence, \delta(x) ~ sqrt(x - x_0), is valid.
• We proof the consistency of the different approaches for deriving the black-hole radiation for the spherically symmetric case inside the theory of massive gravity. By comparing the results obtained by using the Bogoliubov transformations with those obtained by using the path-integral formulation, we find that in both cases the presence of the extra-degrees of freedom create the effect of extra-particles creation due to the distortions on the notions of time defined by the different observers at large scales. This however does not mean extra-particle creation at the horizon level.
• The Liquids Reflectometer at Oak Ridge National Laboratory provides neutron reflectivity capability for an average of about 30 experiments each year. In recent years, there has been a large effort to streamline the data processing and analysis for the instrument. While much of the data reduction can be automated, data analysis remains something that needs to be done by scientists. For this purpose, we present a reflectivity fitting web interface that captures the process of setting up and executing fits while reducing the need for installing software or writing Python scripts.
• We develop a time-ordered data simulator and map-maker for the proposed PIXIE Fourier transform spectrometer and use them to investigate the impact of polarization leakage, imperfect collimation, elliptical beams, sub-pixel effects, correlated noise and spectrometer mirror jitter on the PIXIE data analysis. We find that PIXIE is robust to all of these effects, with the exception of mirror jitter which could become the dominant source of noise in the experiment if the jitter is not kept significantly below $0.1\mu m\sqrt{s}$. Source code is available at https://github.com/amaurea/pixie.
• This paper contains a reformulation of any $n$-player finite, static game into a framework of distributed, dynamical system based on agents' payoff-based deviations. The reformulation generalizes the method employed in the second part of the study of countries' relation formation problem in Li and Morse (2017) to the case of any finite, static game. In the paper two deviation rules are provided and possible applications of this framework are discussed.
• A reliable wireless connection between the operator and the teleoperated Unmanned Ground Vehicle (UGV) is critical in many Urban Search and Rescue (USAR) missions. Unfortunately, as was seen in e.g. the Fukushima disaster, the networks available in areas where USAR missions take place are often severely limited in range and coverage. Therefore, during mission execution, the operator needs to keep track of not only the physical parts of the mission, such as navigating through an area or searching for victims, but also the variations in network connectivity across the environment. In this paper, we propose and evaluate a new teleoperation User Interface (UI) that includes a way of estimating the Direction of Arrival (DoA) of the Radio Signal Strength (RSS) and integrating the DoA information in the interface. The evaluation shows that using the interface results in more objects found, and less aborted missions due to connectivity problems, as compared to a standard interface. The proposed interface is an extension to an existing interface centered around the video stream captured by the UGV. But instead of just showing the network signal strength in terms of percent and a set of bars, the additional information of DoA is added in terms of a color bar surrounding the video feed. With this information, the operator knows what movement directions are safe, even when moving in regions close to the connectivity threshold.
• This paper studies sheaf cohomology on coarse spaces.
• Using data from the Geostationary Operational Environmental Satellites (GOES) spacecraft in the 1-8 Å wavelength range for Solar Cycles 23, 24, and part of Cycles 21 and 22, we compare mean temporal parameters (rising, decay times, duration) and the proportion of impulsive short-duration events (SDE) and gradual long-duration events (LDE) among C- and $\geq$M1.0-class flares. It is found that the fraction of the SDE $\geq$M1.0-class flares (including spikes) in Cycle 24 exceeds that in Cycle 23 in all three temporal parameters at the maximum phase and in the decay time during the ascending cycle phase. However, Cycles 23 and 24 barely differ in the fraction of the SDE C-class flares. The temporal parameters of SDEs, their fraction, and consequently the relationship between the SDE and LDE flares do not remain constant, but they reveal regular changes within individual cycles and during the transition from one cycle to another. In all phases of all four cycles, these changes have the character of pronounced, large-amplitude "quasi-biennial" oscillations (QBOs). In different cycles and at the separate phases of individual cycles, such QBOs are superimposed on various systematic trends displayed by the analyzed temporal flare parameters. In Cycle 24, the fraction of the SDE $\geq$M1.0-class flares from the N- and S-hemispheres displays the most pronounced synchronous QBOs. The QBO amplitude and general variability of the intense $\geq$M1.0-class flares almost always markedly exceeds those of the moderate C-class flares. The ordered quantitative and qualitative variations of the flare type revealed in the course of the solar cycles are discussed within the framework of the concept that the SDE flares are associated mainly with small sunspots (including those in developed active regions) and that small and large sunspots behave differently during cycles and form two distinct populations.
• For $\varepsilon\in(0,1/2)$ and a natural number $d\ge 2$, let $N$ be a natural number with $N \,\ge\u20092^9\,\log_2(d)\u2009\left(\frac\log_2(1/\varepsilon)\varepsilon\right)^2.$We prove that there is a set of $N$ points in the unit cube $[0,1]^d$, which intersects all axis-parallel boxes with volume $\varepsilon$. That is, the dispersion of this point set is bounded from above by $\varepsilon$.
• In this paper, we revisit a central concept in Kolmogorov complexity in which one would equate program-size complexity with information content. Despite the fact that Kolmogorov complexity has been widely accepted as an objective measure of the information content of a string, it has been the subject of many criticisms including the fundamental one directed by logicians and philosophers towards the statistical and semantical theories of information, which is about confusing an object and its name. In this paper, we clarify a number of subtle issues that are at the center of this debate.
• The problem of Shannon entropy estimation in countable infinite alphabets is revisited from the adoption of convergence results of the entropy functional. Sufficient conditions for the convergence of the entropy are used, including scenarios with both finitely and infinitely supported distributions. From this angle, four plug-in histogram-based estimators are studied showing strong consistency and rate of convergences results for the case of finite and unknown supported distributions and families of distributions with summable tail bounded conditions.

Siddhartha Das Oct 06 2017 03:18 UTC

Here is a work in related direction: "Unification of Bell, Leggett-Garg and Kochen-Specker inequalities: Hybrid spatio-temporal inequalities", Europhysics Letters 104, 60006 (2013), which may be relevant to the discussions in your paper. [https://arxiv.org/abs/1308.0270]

Bin Shi Oct 05 2017 00:07 UTC

Welcome to give the comments for this paper!

Bassam Helou Sep 22 2017 17:21 UTC

The initial version of the article does not adequately and clearly explain how certain equations demonstrate whether a particular interpretation of QM violates the no-signaling condition.
A revised and improved version is scheduled to appear on September 25.

James Wootton Sep 21 2017 05:41 UTC

What does this imply for https://scirate.com/arxiv/1608.00263? I'm guessing they still regard it as valid (it is ref [14]), but just too hard to implement for now.

Ben Criger Sep 08 2017 08:09 UTC

Oh look, there's another technique for decoding surface codes subject to X/Z correlated errors: https://scirate.com/arxiv/1709.02154

Aram Harrow Sep 06 2017 07:54 UTC

The paper only applies to conformal field theories, and such a result cannot hold for more general 1-D systems by 0705.4077 and other papers (assuming standard complexity theory conjectures).

Felix Leditzky Sep 05 2017 21:27 UTC

Thanks for the clarification, Philippe!

Philippe Faist Sep 05 2017 21:09 UTC

Hi Felix, thanks for the good question.

We've found it more convenient to consider trace-nonincreasing and $\Gamma$-sub-preserving maps (and this is justified by the fact that they can be dilated to fully trace-preserving and $\Gamma$-preserving maps on a larger system). The issue arises because

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