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An explanation of the recently discovered 7 s pulsations from the isolated neutron star RX J1856.5-3754 is presented. It is assumed that the real spin period of this source is $\approx1$ s, whereas the observed spin-modulation is caused by the presence of a nearly transverse, very low frequency drift waves in the pulsar magnetosphere. It is supposed that the period of the drift wave is equal to a recently observed one. The simulated lightcurve is plotted, the angular parameters are defined and the value of the pulsed fraction of only $\sim 1.2%$ is explained.
Recently, an interesting gravitational model was proposed in order to mimic the effect of Dark Matter. Chamseddine and Mukhanov in the arXiv preprint 1308.5410 have separated the conformal mode of a physical metric in the form of a squared gradient of an auxiliary scalar field. Notably, the variational principle has given a more general equation of motion than that of purely Einsteinian relativity theory, with a possibility of reproducing an effective Dark Matter. In this short paper, we explain the nature of this phenomenon in terms of the class of functions on which the variation takes place. Then we give a more transparent equivalent formulation of the model without an auxiliary metric. Finally, we speculate a bit about possible extensions.
A recently proposed integral representation for permanents is rederived using only elementary combinatorics. For this proof the assumption that the matrix, for which the permanent is calculated, has an inverse is not necessary.
Ward and Kellis (Reports, September 5 2012) identify regulatory regions in the human genome exhibiting lineage-specific constraint and estimate the extent of purifying selection. There is no statistical rationale for the examples they highlight, and their estimates of the fraction of the genome under constraint are biased by arbitrary designations of completely constrained regions.
We provide an algebraic unification of the spectral gap proofs of the convergence of the renormalised model for regularity structures. We show that the key recentering map used in the literature for adjusting the recentering of the model is given via equivalent characterisations.
Earth's climate stability, characterized by the global radiative feedback parameter ($λ$), varies decadally due to changing surface temperature patterns. Recent variations in $λ$ are poorly understood as coordinated model simulations typically end in 2014. We apply a convolutional neural network trained on climate model simulations to observation-based surface temperature reconstructions to estimate variations in $λ$ up to 2025. We find that $λ$ reached a minimum (maximum stability) around the mid 1990s ($λ\simeq -3 {\rm Wm^{-2}/K}$), but has since weakened significantly ($λ\simeq -2\, {\rm Wm^{-2}/K}$). We confirm these results with climate model simulations extended to 2022. The recent $λ$ weakening is not significantly affected by El Niño Southern Oscillation or Pacific Decadal Oscillation. Attribution reveals that warming in the subtropical Northeast Pacific is an important driver of the recently weakened feedback, confirmed by targeted experiments in E3SMv2. Our approach enables near real-time monitoring of Earth's climate stability.
Recently, Kaur and Rana introduced the partition function denoted by $ρ(n)$, where the largest part $λ$ appears exactly once, and the remaining parts constitute a partition of $λ$. In this paper, we establish new generating functions for certain variants of $ρ(n)$. Further, we obtain a linear recurrence relation for our new generating function.
In this note, we establish the validity of a conjecture recently proposed in Mathematics Magazine and connect it to the existing interesting results
The analyses of states with double $cs$ content and the search for exotics have recently gained much attention. The Belle experiment collected roughly 1 ab$^{-1}$ integrated luminosity data. While Belle II data-taking is in progress, we have performed a new search for exotic states and cross-section measurements with the full Belle data sets. Here we review the recent analysis of: (a) $e^+e^-\to D_s^{(*)+}+D_{sJ}^-$ + $c.c$. from both $Υ(2S)$ decays and continuum production at 10.52 GeV, using the Belle detector at KEKB; (b) the analysis of $e^+e^- \to η_c J/ψ$ + $c.c.$ and search for double charmonium states; (c) the study of $e^+e^- \to D_s^+D_{s0}(2317)^-$ + $c.c.$ and $e^+e^- \to D_s^+D_{s1}(2460)^-$ + $c.c.$ + anything else, in the continuum. Born cross-sections are evaluated, and a possible confirmation of the states seen in the invariant mass system of $J/ψφ$ by LHCb in $B$ decays has been investigated.
Gaussian process (GP) methods have been widely studied recently, especially for large-scale systems with big data and even more extreme cases when data is sparse. Key advantages of these methods consist in: 1) the ability to provide inherent ways to assess the impact of uncertainties (especially in the data, and environment) on the solutions, 2) have efficient factorisation based implementations and 3) can be implemented easily in distributed manners and hence provide scalable solutions. This paper reviews the recently developed key factorised GP methods such as the hierarchical off-diagonal low-rank approximation methods and GP with Kronecker structures. An example illustrates the performance of these methods with respect to accuracy and computational complexity.
We review recent results for heterotic moduli and the Hull--Strominger system. In particular, we discuss mathematical properties of the recently derived deformation operator $\bar D$ associated to the deformation complex of heterotic $SU(3)$ solutions. We review results on Serre duality, showing that the operator has a vanishing index, and discuss a notion of Čech cohomology and a particular instance of a Dolbeault theorem for $\bar D$. Specifically, the cohomology parametrising infinitesimal deformations is isomorphic to the first Čech cohomology of an associated cochain complex. This will be useful for future research, as it provides a more algebraic handle on the heterotic moduli problem, which is useful for understanding notions of stability, geometric invariants, and enumerative geometry for the Hull--Strominger system.
In this proceeding, the xFitter project is presented. xFitter is an open-source package that provides a framework for the determination of the parton distribution and fragmentation functions for many different kinds of analyses in Quantum Chromodynamics. xFitter version 2.2.0 has recently been released and offers an expanded set of tools and options. xFitter has been used for a number of analyses performed recently. An emphasis is given on the recently published study performed by the xFitter Developers' team of the pion fragmentation functions.
Many exotic resonances have been recently observed at the LHC and other experiments. In this report, CMS studies of exotic multiquark states are reported using the data collected in pp collisions at $\sqrt{s}$ = 13 TeV.
The concept of matrix rigidity was introduced by Valiant(independently by Grigoriev) in the context of computing linear transformations. A matrix is rigid if it is far(in terms of Hamming distance) from any matrix of low rank. Although we know rigid matrices exist, obtaining explicit constructions of rigid matrices have remained a long-standing open question. This decade has seen tremendous progress towards understanding matrix rigidity. In the past, several matrices such as Hadamard matrices and Fourier matrices were conjectured to be rigid. Very recently, many of these matrices were shown to have low rigidity. Further, several explicit constructions of rigid matrices in classes such as $E$ and $P^{NP}$ were obtained recently. Among other things, matrix rigidity has found striking connections to areas as disparate as communication complexity, data structure lower bounds and error-correcting codes. In this survey, we present a selected set of results that highlight recent progress on matrix rigidity and its remarkable connections to other areas in theoretical computer science.
HERA $ep$ collider provides unique information on the proton structure. High center of mass energy $s=320$ GeV gives access to both the low Bjorken-$x$ domain and regime of high momentum transfers $Q$. Recently the H1 collaboration reported a high precision measurement of the structure function $F_2$ at low $x$ leading to tight constraints on the sea quark and gluon densities. Both the H1 and ZEUS collaborations measure the structure function $F_L$ which provides an important cross check of the conventional QCD picture. This measurement is recently extended by H1 to low $Q^2$ where small $x$ corrections may play important role. An ultimate precision of the deep inelastic scattering cross section measurement is achieved by combining the measurements of the H1 and ZEUS collaborations. The combined data are used as a sole input to a QCD fit to obtained HERA PDF set. New measurements of inclusive $e^-p$ neutral and charged current scattering cross sections by the ZEUS collaboration at high $Q^2$ improve precision in this kinematic domain. H1 analysis of the DIS high $P_t$ jet production cross section is used for a determination of the strong coupling constant $α_S$. Separation of the s
Space-time wormholes were introduced in Wheeler's idea of space-time foam. Traversible wormholes as defined by Morris & Thorne became popular as potential short cuts across the universe and even time machines. More recently, the author proposed a general theory of wormhole dynamics, unified with black-hole dynamics. This article gives a brief review of the above ideas and summarizes progress on wormhole dynamics in the last year. Firstly, a numerical study of dynamical perturbations of the first Morris-Thorne wormhole showed it to be unstable, either collapsing to a black hole or exploding to an inflationary universe. This provides a mechanism for inflating a wormhole from space-time foam to usable size. Intriguing critical behaviour was also discovered. Secondly, a wormhole solution supported by pure radiation was discovered and used to find analytic examples of dynamic wormhole processes which were also recently found in a two-dimensional dilaton gravity model: the construction of a traversible wormhole from a Schwarzschild black hole and vice versa, and the enlargement or reduction of the wormhole.
The ring-diagram technique was developed by Frank Hill 25 years ago and developed quickly during the late 1990s. It is nowadays one of the most commonly used techniques in local helioseismology. The method consists in the power spectral analysis of solar acoustic oscillations on small regions (2 to 30 degrees) of the solar surface. The power spectrum resembles a set of trumpets nested inside each other and, for a given frequency, it looks like a ring, hence the technique's name. It provides information on the horizontal flow field and thermodynamic structure in the layers immediately below the photosphere. With data regularly provided by MDI (on board SOHO), GONG+ network and more recently HMI (on SDO), many important results have been achieved. In recently years, these results include estimations of the meridional circulation and its evolution with solar cycle; flows associated with active regions, as well as, flow divergence and vorticity; and thermal structure beneath and around active regions. Much progress is expected with data now provided by HMI's high spatial resolution observations and high duty cycle. There are two data processing pipelines (GONG and HMI) providing free a
NASA says a long-running air leak aboard the ISS recently worsened, leading engineers to investigate new suspected crack locations and consider a riskier repair strategy。 Astronauts were temporarily moved into a safe haven as a precaution before the repair was postponed for further analysis
I review recent developments in POWHEG, a method for interfacing parton-shower generators with NLO QCD computations. I illustrate recent progress in understanding several features of the method, and in clarifying similarity and differences with respect to MC@NLO. Furthermore, I briefly describe a recently introduced framework, the POWHEG BOX, that allows the automatic POWHEG implementation of any given NLO calculation, and has been recently applied to Z+jet production and to Higgs production via vector-boson fusion.