pinecone/core-2020-05-10-deduplication huggingface dataset:
Top-pair production and decay at NLO matched with parton showers.

We present a next-to-leading order (NLO) calculation of   tt¯  production in hadronic collisions interfaced to shower generators according to the POWHEG method. We start from an NLO result from previous work, obtained in the zero width limit, where radiative corrections to both production and decays are included. The POWHEG interface required an extension of the POWHEG BOX framework, in order to deal with radiation from the decay of resonances. This extension is fully general (i.e. it can be applied in principle to any process considered in the zero width limit), and is here applied for the first time. In order to perform a realistic simulation, we introduce finite width effects using different approximations, that we validated by comparing with published exact NLO results. We have interfaced our POWHEG code to the PYTHIA8 shower Monte Carlo generator. At this stage, we dealt with novel issues related to the treatment of resonances, especially with regard to the initial scale for the shower that needs to be set appropriately. This procedure affects, for example, the fragmentation function of the b quark, that we have studied with particular attention. We believe that the tool presented here improves over previous generators for all aspects that have to do with top decays, and especially for the study of issues related to top mass measurements that involve B hadrons or b jets. The work presented here also constitutes a first step towards a fully consistent matching of NLO calculations involving intermediate resonances decaying into coloured particles, with parton showers
Solar origin of heliospheric magnetic field inversions: evidence for coronal loop opening within pseudostreamers

The orientation of the heliospheric magnetic field (HMF) in near‒Earth space is generally a good indicator of the polarity of HMF foot points at the photosphere. There are times, however, when the HMF folds back on itself (is inverted), as indicated by suprathermal electrons locally moving sunward, even though they must ultimately be carrying the heat flux away from the Sun. Analysis of the near‒Earth solar wind during the period 1998–2011 reveals that inverted HMF is present approximately 5.5% of the time and is generally associated with slow, dense solar wind and relatively weak HMF intensity. Inverted HMF is mapped to the coronal source surface, where a new method is used to estimate coronal structure from the potential‒field source‒surface model. We find a strong association with bipolar streamers containing the heliospheric current sheet, as expected, but also with unipolar or pseudostreamers, which contain no current sheet. Because large‒scale inverted HMF is a widely accepted signature of interchange reconnection at the Sun, this finding provides strong evidence for models of the slow solar wind which involve coronal loop opening by reconnection within pseudostreamer belts as well as the bipolar streamer belt. Occurrence rates of bipolar‒ and pseudostreamers suggest that they are equally likely to result in inverted HMF and, therefore, presumably undergo interchange reconnection at approximately the same rate. Given the different magnetic topologies involved, this suggests the rate of reconnection is set externally, possibly by the differential rotation rate which governs the circulation of open solar flux
Revisiting GRACE Antarctic ice mass trends and accelerations considering autocorrelation

Previous GRACE-derived ice mass trends and accelerations have almost entirely been based on an assumption that the residuals to a regression model (including also semi-annual, annual and tidal aliasing terms) are not serially correlated. We consider ice mass change time series for Antarctica and show that significant autocorrelation is, in fact, present. We examine power-law and autoregressive models and compare them to those that assume white (uncorrelated) noise. The data do not let us separate autoregressive and power-law models but both indicate that white noise uncertainties need to be scaled up by a factor of up to 4 for accelerations and 6 for linear rates, depending on length of observations and location. For the whole of Antarctica, East Antarctica and West Antarctica the scale factors are 1.5, 1.5 and 2.2 respectively for the trends and, for the accelerations, 1.5, 1.5 and 2.1. Substantially lower scale-factors are required for offshore time series, suggesting much of the time-correlation is related to continental mass changes. Despite the higher uncertainties, we find significant (2-sigma) accelerations over much of West Antarctica (overall increasing mass loss) and Dronning Maud Land (increasing mass gain) as well as a marginally significant acceleration for the ice sheet as a whole (increasing mass loss)
Evidence of hot high velocity photoionized plasma falling on actively accreting T Tauri stars

The He II (1640 angstrom) line and the resonance doublet of N V (UV1) provide a good diagnostic tool to constrain the excitation mechanism of hot (T-e > 40,000 K) atmospheric/magnetospheric plasmas in T Tauri stars (TTSs). Making use of the data available in the Hubble Space Telescope archive, this work shows that there are at least two distinct physical components contributing to the radiation in these tracers: the accretion flow sliding on the magnetosphere and the atmosphere. The N V profiles in most sources are symmetric and at rest with respect to the star. The velocity dispersion of the profile increases from non-accreting (sigma = 40 km s (1)) to accreting (sigma = 120 km s (1)) TTSs, suggesting that the macroturbulence field in the line formation region decreases as the stars approach the main sequence. Evidence of the N V line being formed in a hot solar-like wind has been found in RW Aur, HN Tau, and AA Tau. The He II profile has a strong narrow component that dominates the line flux; the dispersion of this component ranges from 20 to 60 km s (1). Current data suggest that both accretion shocks and atmospheric emission might contribute to the line flux. In some sources, the He II line shows a broad and redward-shifted emission component often accompanied by semiforbidden O III] emission that has a critical electron density of similar to 3.4 x 10(10) cm(3). In spite of their different origins (inferred from the kinematics of the line formation region), N V and He II fluxes are strongly correlated, with only the possible exception of some of the heaviest accretors
Non-equilibrium self-assembly of a filament coupled to ATP/GTP
  hydrolysis

We study the stochastic dynamics of growth and shrinkage of single actin
filaments or microtubules taking into account insertion, removal, and ATP/GTP
hydrolysis of subunits. The resulting phase diagram contains three different
phases: a rapidly growing phase, an intermediate phase and a bound phase. We
analyze all these phases, with an emphasis on the bound phase. We also discuss
how hydrolysis affects force-velocity curves. The bound phase shows features of
dynamic instability, which we characterize in terms of the time needed for the
ATP/GTP cap to disappear as well as the time needed for the filament to reach a
length of zero, i.e., (to collapse) for the first time. We obtain exact
expressions for all these quantities, which we test using Monte Carlo
simulations.Comment: 34 page
Nitrosopersulfide (SSNO) accounts for sustained NO bioactivity of S-nitrosothiols following reaction with sulfide

Funding: Susanne-Bunnenberg-Stiftung of the Düsseldorf Heart Center (to MK), the COSTaction BM1005 (European Network on Gasotransmitters), the FP7 Marie Curie International Reintegration program (PIRG08-GA-2010-277006, to PN) and the Faculty of Medicine, University of Southampton (to MF).Sulfide salts are known to promote the release of nitric oxide (NO) from S-nitrosothiols and potentiate their vasorelaxant activity, but much of the cross-talk between hydrogen sulfide and NO is believed to occur via functional interactions of cell regulatory elements such as phosphodiesterases. Using RFL-6 cells as an NO reporter system we sought to investigate whether sulfide can also modulate nitrosothiol-mediated soluble guanylyl cyclase (sGC) activation following direct chemical interaction. We find a U-shaped dose response relationship where low sulfide concentrations attenuate sGC stimulation by S-nitrosopenicillamine (SNAP) and cyclic GMP levels are restored at equimolar ratios. Similar results are observed when intracellular sulfide levels are raised by pre-incubation with the sulfide donor, GYY4137. The outcome of direct sulfide/nitrosothiol interactions also critically depends on molar reactant ratios and is accompanied by oxygen consumption. With sulfide in excess, a 'yellow compound' accumulates that is indistinguishable from the product of solid-phase transnitrosation of either hydrosulfide or hydrodisulfide and assigned to be nitrosopersulfide (perthionitrite, SSNO; λ 412nm in aqueous buffers, pH 7.4; 448nm in DMF). Time-resolved chemiluminescence and UV-visible spectroscopy analyses suggest that its generation is preceded by formation of the short-lived NO-donor, thionitrite (SNO). In contrast to the latter, SSNO is rather stable at physiological pH and generates both NO and polysulfides on decomposition, resulting in sustained potentiation of SNAP-induced sGC stimulation. Thus, sulfide reacts with nitrosothiols to form multiple bioactive products; SSNO rather than SNO may account for some of the longer-lived effects of nitrosothiols and contribute to sulfide and NO signaling.Publisher PDFPeer reviewe
Response of Unruh-DeWitt detector with time-dependent acceleration

It is well known that a detector, coupled linearly to a quantum field and
accelerating through the inertial vacuum with a constant acceleration $g$, will
behave as though it is immersed in a radiation field with temperature
$T=(g/2\pi)$. We study a generalization of this result for detectors moving
with a time-dependent acceleration $g(\tau)$ along a given direction. After
defining the rate of excitation of the detector appropriately, we evaluate this
rate for time-dependent acceleration, $g(\tau)$, to linear order in the
parameter $\eta = \dot g / g^2$. In this case, we have three length scales in
the problem: $g^{-1}, (\dot g/g)^{-1}$ and $\omega^{-1}$ where $\omega$ is the
energy difference between the two levels of the detector at which the spectrum
is probed. We show that: (a) When $\omega^{-1} \ll g^{-1} \ll (\dot g/g)^{-1}$,
the rate of transition of the detector corresponds to a slowly varying
temperature $T(\tau) = g(\tau)/2 \pi $, as one would have expected. (b)
However, when $ g^{-1}\ll \omega^{-1} \ll (\dot g/g)^{-1}$, we find that the
spectrum is modified \textit{even at the order $\mathcal{O}(\eta)$}. This is
counter-intuitive because, in this case, the relevant frequency does not probe
the rate of change of the acceleration since $(\dot g/g) \ll \omega$ and we
certainly do not have deviation from the thermal spectrum when $\dot g =0$.
This result shows that there is a subtle discontinuity in the behaviour of
detectors with $\dot g = 0$ and $\dot g/g^2$ being arbitrarily small. We
corroborate this result by evaluating the detector response for a particular
trajectory which admits an analytic expression for the poles of the Wightman
function.Comment: v1, 7 pages, no figures; v2, an Acknowledgment and some clarifying
  comments added, matches version accepted for publication in Physics Letters
Stochastic Resonance in an Extended FitzHugh-Nagumo System: the Role of
  Selective Coupling

Here we present a study of stochastic resonance in an extended
FitzHugh-Nagumo system with a field dependent activator diffusion. We show that
the system response (here measured through the output signal-to-noise ratio) is
enhanced due to the particular form of the non-homogeneous coupling. Such a
result supports previous ones obtained in a simpler scalar reaction-diffusion
system and shows that such an enhancement, induced by the field dependent
diffusion -or selective coupling-, is a robust phenomenon.Comment: 14 pages, 19 figure
Evolution of twist-three parton distributions in QCD beyond the large
  N_c limit

We formulate a consistent 1/N_c^2 expansion of the QCD evolution equations
for the twist-three quark distributions g_2(x,Q^2), h_L(x,Q^2) and e(x,Q^2)
based on the interpretation of the evolution as a three-particle
quantum-mechanical problem with hermitian Hamiltonian. Each distribution
amplitude can be decomposed in contributions of partonic components with
DGLAP-type scale dependence. We calculate the 1/N_c^2 corrections to the
evolution of the dominant component with the lowest anomalous dimension - the
only one that survives in the large-N_c limit - and observe a good agreement
with the exact numerical results for N_c=3. The 1/N_c^2 admixture of operators
with higher anomalous dimensions is shown to be concentrated at a few lowest
partonic components and in general is rather weak.Comment: 14 pages, LaTeX style, 2 figure
One-loop weak corrections to the $b\bar b$ cross section at TeV energy
  hadron colliders

We investigate one-loop weak corrections to the production cross section of
two $b$-jets at Tevatron and Large Hadron Collider (LHC). We establish that
they are small at inclusive level but dominant in exclusive observables that
have a non-trivial dependence on the helicity structure of the hard
subprocesses. Such effects can serve as a test of the Standard Model (SM) and,
conversely, they should be taken into account in future experimental analyses
aiming at extracting possible signals of new physics.Comment: 12 pages, latex, 3 figure
Supersymmetry for Gauged Double Field Theory and Generalised
  Scherk-Schwarz Reductions

Previous constructions of supersymmetry for double field theory have relied
on the so called strong constraint. In this paper, the strong constraint is
relaxed and the theory is shown to possess supersymmetry once the generalised
Scherk-Schwarz reduction is imposed. The equivalence between the generalised
Scherk-Schwarz reduced theory and the gauged double field theory is then
examined in detail for the supersymmetric theory. As a byproduct we write the
generalised Killing spinor equations for the supersymmetric double field
theory.Comment: 29 pages, LateX, v2 typos fixed and some improved discussion, version
  as in Journa
Embedding inflation into the Standard Model - more evidence for
  classical scale invariance

If cosmological inflation is due to a slowly rolling single inflation field
taking trans-Planckian values as suggested by the BICEP2 measurement of
primordial tensor modes in CMB, embedding inflation into the Standard Model
challenges standard paradigm of effective field theories. Together with an
apparent absence of Planck scale contributions to the Higgs mass and to the
cosmological constant, BICEP2 provides further experimental evidence for the
absence of large $M_{\rm P}$ induced operators. We show that classical scale
invariance, the paradigm that all fundamental scales in Nature are induced by
quantum effects, solves the problem and allows for a remarkably simple
scale-free Standard Model extension with inflaton without extending the gauge
group. Due to trans-Planckian inflaton values and vevs, a dynamically induced
Coleman-Weinberg-type inflaton potential of the model can predict
tensor-to-scalar ratio $r$ in a large range, converging around the prediction
of chaotic $m^2\phi^2$ inflation for a large trans-Planckian value of the
inflaton vev. Precise determination of $r$ in future experiments will single
out a unique scale-free inflation potential, allowing to test the proposed
field-theoretic framework.Comment: 20 pages, 6 figures, revised version published on JHE
First measurement of the deep-inelastic structure of proton diffraction

A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton scattering. The diffractive contribution to the proton structure function is evaluated as a function of the appropriate deep-inelastic scattering variables using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. The dependence of this contribution on x-pomeron is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of a factorised structure function is presented. This structure function is observed to be consistent with scale invariance
Cosmological Density Perturbations From A Quantum Gravitational Model Of Inflation

We derive the implications for anisotropies in the cosmic microwave background following from a model of inflation in which a bare cosmological constant is gradually screened by an infrared process in quantum gravity. The model predicts that the amplitude of scalar perturbations is $A_S = (2.0 \pm .2) \times 10^{-5}$, that the tensor-to-scalar ratio is $r \approx 1.7 \times 10^{-3}$, and that the scalar and tensor spectral indices are $n \approx .97$ and $n_T \approx -2.8 \times 10^{-4}$, respectively. By comparing the model's power spectrum with the COBE 4-year RMS quadrupole, the mass scale of inflation is determined to be $M = (.72 \pm .03) \times 10^{16}~{\rm GeV}$. At this scale the model produces about $10^8$ e-foldings of inflation, so another prediction is $\Omega = 1$
Toda Chains with type $A_{m}$ Lie Algebra for Multidimensional $m$-Component Perfect Fluid Cosmology

We consider a D-dimensional cosmological model describing an evolution of Ricci-flat factor spaces, M_1,...M_n (n > 2), in the presence of an m-component perfect fluid source (n > m > 1). We find characteristic vectors, related to the matter constants in the barotropic equations of state for fluid components of all factor spaces. We show that, in the case where we can interpret these vectors as the root vectors of a Lie algebra of Cartan type A_m=sl(m+1,C), the model reduces to the classical open m-body Toda chain. Using an elegant technique by Anderson (J. Math. Phys. 37 (1996) 1349) for solving this system, we integrate the Einstein equations for the model and present the metric in a Kasner-like form
Non-commutative Bloch theory

For differential operators which are invariant under the action of an abelian
group Bloch theory is the preferred tool to analyze spectral properties. By
shedding some new non-commutative light on this we motivate the introduction of
a non-commutative Bloch theory for elliptic operators on Hilbert C*-modules. It
relates properties of C*-algebras to spectral properties of module operators
such as band structure, weak genericity of cantor spectra, and absence of
discrete spectrum. It applies e.g. to differential operators invariant under a
projective group action, such as Schroedinger, Dirac and Pauli operators with
periodic magnetic field, as well as to discrete models, such as the almost
Matthieu equation and the quantum pendulum.Comment: 37 pages, 2 figure
Rota-Baxter Algebras and Dendriform Algebras

In this paper we study the adjoint functors between the category of
Rota-Baxter algebras and the categories of dendriform dialgebras and
trialgebras. In analogy to the well-known theory of the adjoint functor between
the category of associative algebras and Lie algebras, we first give an
explicit construction of free Rota-Baxter algebras and then apply it to obtain
universal enveloping Rota-Baxter algebras of dendriform dialgebras and
trialgebras. We further show that free dendriform dialgebras and trialgebras,
as represented by binary planar trees and planar trees, are canonical
subalgebras of free Rota-Baxter algebras.Comment: Typos corrected and the last section on analog of
  Poincare-Birkhoff-Witt theorem deleted for a gap in the proo
Double $\pi^0$ Photoproduction off the Proton at Threshold

The reaction $\gamma p \to \pi^0 \pi^0 p$ has been measured using the TAPS
BaF$_2$ calorimeter at the tagged photon facility of the Mainz Microtron
accelerator. Chiral perturbation theory (ChPT) predicts that close to threshold
this channel is significantly enhanced compared to double pion final states
with charged pions. In contrast to other reaction channels, the lower order
tree terms are strongly suppressed in 2$\pi^0$ photoproduction. The consequence
is the dominance of pion loops in the 2$\pi^0$ channel close to threshold - a
result that opens new prospects for the test of ChPT and in particular its
inherent loop terms. The present measurement is the first which is sensitive
enough for a conclusive comparison with the ChPT calculation and is in
agreement with its prediction. The data also show good agreement with a
calculation in the unitary chiral approach.Comment: Submitted to PL
Kink excitation spectra in the (1+1)-dimensional $\varphi^8$ model

We study excitation spectra of BPS-saturated topological solutions -- the
kinks -- of the $\varphi^8$ scalar field model in $(1+1)$ dimensions, for three
different choices of the model parameters. We demonstrate that some of these
kinks have a vibrational mode, apart from the trivial zero (translational)
excitation. One of the considered kinks is shown to have three vibrational
modes. We perform a numerical calculation of the kink-kink scattering in one of
the considered variants of the $\varphi^8$ model, and find the critical
collision velocity $v_{\scriptsize \mbox{cr}}$ that separates the different
collision regimes: inelastic bounce of the kinks at $v_{\scriptsize
\mbox{in}}\ge v_{\scriptsize \mbox{cr}}$, and capture at $v_{\scriptsize
\mbox{in}}<v_{\scriptsize \mbox{cr}}$. We also observe escape windows at some
values of $v_{\scriptsize \mbox{in}}<v_{\scriptsize \mbox{cr}}$ where the kinks
escape to infinity after bouncing off each other two or more times. We analyse
the features of these windows and discuss their relation to the resonant energy
exchange between the translational and the vibrational excitations of the
colliding kinks.Comment: 20 pages, 14 figures; V2: minor changes to match version published in
  JHE
From self to social cognition : theory of mind mechanisms and their relation to executive functioning

This work was supported by the Economic and Social Research Council [grant number ES/J500136/1] in the form of a three-year PhD studentship awarded to Elisabeth Bradford.‘Theory of Mind’ refers to the ability to attribute mental states to oneself and other people (Premack & Woodruff, 1978). This study examined the extent to which ‘Self’ and ‘Other’ belief-attribution processes within the Theory of Mind (ToM) mechanism could be distinguished behaviourally, and whether these separable components differentially related to Executive Functioning (EF) abilities. A computerized false-belief task, utilizing a matched-design to allow direct comparison of self-oriented vs. other-oriented belief-attribution, was used to assess ToM, and a face-image Stroop task was employed to assess EF, within a population of typically-developed adults. Results revealed significantly longer reaction times when attributing beliefs to other people as opposed to recognizing and attributing beliefs to oneself. Intriguingly, results revealed that ‘perspective-shift’ requirements (i.e. changing from adoption of the ‘self’ perspective to the perspective of the ‘other’, or vice versa) across false-belief trials influenced reaction times. Reaction times were significantly longer when the perspective shift was from self-to-other than from other-to-self. It is suggested that the ‘self’ forms the stem of understanding the ‘other’, and is therefore processed regardless of ultimate task demands; in contrast, the ‘other’ perspective is only processed when explicitly required. We conclude that adopting another person’s perspective, even when their belief state is matched to one’s own, requires more cognitive effort than recalling and reflecting on self-oriented belief-states.Publisher PDFPeer reviewe