pinecone/core-2020-05-10-deduplication huggingface dataset:
Precision Measurement of Orthopositronium Decay Rate Using SiO_2 Powder

The intrinsic decay rate of orthopositronium formed in ${\rm SiO_2}$ powder
is measured using the direct $2\gamma$ correction method such that the time
dependence of the pick-off annihilation rate is precisely determined using high
energy-resolution germanium detectors. As a systematic test, two different
types of ${\rm SiO_2}$ powder are used with consistent findings. The intrinsic
decay rate of orthopositronium is found to be $7.0396\pm0.0012 (stat.)\pm0.0011
(sys.)\mu s^{-1}$, which is consistent with previous measurements using ${\rm
SiO_2}$ powder with about twice the accuracy. Results agree well with a recent
$O(\alpha^2)$ QED prediction, varying $3.8-5.6$ experimental standard
deviations from other measurements.Comment: 16 pages, 7 figures included. To be published in Physics Letters
c,b quark masses and f_D_(s), f_B_(s) decay constants from pseudoscalar
  sum rules in full QCD to order alpha_s^2

The pseudoscalar sum rules of the heavy-light quark systems are used for
extracting simultaneously the c,b quark masses and the decay constants
f_D_(s),f_B_(s) of the D_(s),B_(s) mesons. To order alpha_s^2, one obtains the
running quark masses: m_c(m_c)=(1.10 \pm 0.04) GeV, m_b(m_b)=(4.05\pm 0.06)
GeV, the perturbative pole masses: M_c=(1.46\pm 0.04) GeV, M_b=(4.69\pm 0.06)
GeV, and the decay constants: f_D=(205\pm 20) MeV, f_B=(203\pm 23) MeV and
f_D_s=(235\pm 24) MeV, f_B_s=(236\pm 30) MeV, in the normalization where f_\pi=
130.56 MeV. The fitted values of the pole and running masses satisfy quite well
their three-loop perturbative relation. The value f_D = f_B confirms earlier
findings from the sum rule that the 1/M_P^1/2 heavy quark symmetry scaling law
is affected by large 1/M_P corrections.Comment: 9 pages in Latex file including 1 table and 2 Eps figure
The complex geomety of a domain related to $\mu$-synthesis

We describe the basic complex geometry and function theory of the {\em
pentablock} $\mathcal{P}$, which is the bounded domain in $\mathbb{C}^3$ given
by \[ \mathcal{P}= \{(a_{21}, \mathrm{tr} A, \det A): A= \begin{bmatrix}
a_{ij}\end{bmatrix}_{i,j=1}^2 \in \mathbb{B}\} \] where $\mathbb{B}$ denotes
the open unit ball in the space of $2\times 2$ complex matrices. We prove
several characterizations of the domain. We describe its distinguished boundary
and exhibit a $4$-parameter group of automorphisms of $\mathcal{P}$. We show
that $\mathcal{P}$ is intimately connected with the problem of $\mu$-synthesis
for a certain cost function $\mu$ on the space of $2\times 2$ matrices defined
in connection with robust stabilization by control engineers. We demonstrate
connections between the function theories of $\mathcal{P}$ and $\mathbb{B}$. We
show that $\mathcal{P}$ is polynomially convex and starlike.Comment: 36 pages, 2 figures. This version contains corrections of some
  inaccuracies and an expanded argument for Proposition 12.
Game Theory Explorer - Software for the Applied Game Theorist

This paper presents the "Game Theory Explorer" software tool to create and
analyze games as models of strategic interaction. A game in extensive or
strategic form is created and nicely displayed with a graphical user interface
in a web browser. State-of-the-art algorithms then compute all Nash equilibria
of the game after a mouseclick. In tutorial fashion, we present how the program
is used, and the ideas behind its main algorithms. We report on experiences
with the architecture of the software and its development as an open-source
project
Thorotrast and in vivo thorium dioxide: numerical simulation of 30 years
  of alpha radiation absorption by the tissues near a large compact source

Background: The epidemiology of the slightly radioactive contrast agent named
Thorotrast presents a very long latency period between the injection and the
development of the related pathologies. It is an example of the more general
problem posed by a radioactive internal contaminant whose effects are not
noteworthy in the short term but become dramatic in the long period. A point
that is still to be explored is fluctuations (in space and time) in the
localized absorption of radiation by the tissues. Methods: A Monte Carlo
simulation code has been developed to study over a 30 year period the daily
absorption of alpha radiation by micrometer sized portions of tissue placed at
a distance of 0-100 micrometers from a model source, that approximates a
compact thorium dioxide source in liver or spleen whose size is larger or equal
to 20 micrometers. The biological depletion of the daughter nuclei of the
thorium series is taken into account. The initial condition assumes chemically
purified natural thorium. Results: Most of the absorbed dose is concentrated in
a 25 micrometer thick layer of tissue, adjacent to the source boundary.
Fluctuations where a target region with a volume of 1 cube micrometer is hit by
3-5 alpha particles in a day or in a shorter period of time are relevant in a
1-10 micrometer thick layer of tissue adjacent to the source boundary, where
their frequency is larger than the Poisson law prediction.Comment: In press on Physica Medica, available online at the journal site
  since february 21th, 201
U(1)$_{B-L}$ Symmetry Restoration and Effective Neutrino Species

The U(1)$_{B-L}$ symmetry could be restored during inflation, since the
BICEP2 results suggest a GUT-scale inflation with the Hubble parameter, $H_{\rm
inf} \simeq 10^{14}$ GeV, close to the U(1)$_{B-L}$ breaking scale. We consider
a scenario in which the ${B-L}$ Higgs field dominates the Universe after
inflation, and mainly decays into the U(1)$_{B-L}$ gauge bosons, whose
subsequent decays reheat the Universe. Interestingly, if one of the
right-handed neutrinos is extremely light and behaves as dark radiation or hot
dark matter, its abundance is determined by the $B-L$ charge assignment and the
relativistic degree of freedom in plasma. We find that $\Delta N_{\rm eff}$
takes discrete values between $0.188$ and $0.220$ in the standard model plus
three right-handed neutrinos, depending on whether the decay into heavier
right-handed neutrinos are kinematically accessible or not. In the fiveness
U(1)$_{\bf 5}$ case, we find that $\Delta N_{\rm eff}$ takes discrete values
between $0.313$ and $0.423$. The tension between BICEP2 and {\it Planck} can be
partially relaxed by dark radiation.Comment: 14 pages, v2: corrected small errors in calculations, conclusions
  unchange
A Silicon Nanocrystal Tunnel Field Effect Transistor

In this work, we demonstrate a silicon nanocrystal Field Effect Transistor
(ncFET). Its operation is similar to that of a Tunnelling Field Effect
Transistor (TFET) with two barriers in series. The tunnelling barriers are
fabricated in very thin silicon dioxyde and the channel in intrinsic
polycrystalline silicon. The absence of doping eliminates the problem of
achieving sharp doping profiles at the junctions, which has proven a challenge
for large-scale integration and in principle allows scaling down the atomic
level. The demonstrated ncFET features a 10$^4$ on/off current ratio at room
temperature, a low 30 pA/$\mu$m leakage current at a 0.5 V bias, an on-state
current on a par with typical all-Si TFETs and bipolar operation with high
symmetry. Quantum dot transport spectroscopy is used to assess the band
structure and energy levels of the silicon island.Comment: Copyright 2014 American Institute of Physics. This article may be
  downloaded for personal use only. Any other use requires prior permission of
  the author and the American Institute of Physics. The following article
  appeared in Appl. Phys. Lett. 104, 193505 (2014) and may be found at
  http://scitation.aip.org/content/aip/journal/apl/104/19/10.1063/1.4876765. 4
  pages, 3 figure
Old pre-main-sequence Stars: Disc reformation by Bondi-Hoyle accretion

Young stars show evidence of accretion discs which evolve quickly and
disperse with an e-folding time of $\sim$ 3Myr. This is in striking contrast
with recent observations that suggest evidence for numerous $>30$ Myr old stars
with an accretion disc in large star-forming complexes. We consider whether
these observations of apparently old accretors could be explained by invoking
Bondi-Hoyle accretion to rebuild a new disc around these stars during passage
through a clumpy molecular cloud. We combine a simple Monte Carlo model to
explore the capture of mass by such systems with a viscous evolution model to
infer the levels of accretion that would be observed. We find that a
significant fraction of stars may capture enough material via the Bondi-Hoyle
mechanism to rebuild a disc of mass $\gtrsim$ 1 minimum-mass solar nebula, and
$\lesssim 10\%$ accrete at observable levels at any given time. A significant
fraction of the observed old accretors may be explained with our proposed
mechanism. Such accretion may provide a chance for a second epoch of planet
formation, and have unpredictable consequences for planetary evolution.Comment: 5 pages, 2 figures. Accepted by A&
Secular- and merger-built bulges in barred galaxies

(Abridged) We study the incidence, as well as the nature, of composite bulges
in a sample of 10 face-on barred galaxies to constrain the formation and
evolutionary processes of the central regions of disk galaxies. We analyze the
morphological, photometric, and kinematic properties of each bulge. Then, by
using a case-by-case analysis we identify composite bulges and classify every
component into a classical or pseudobulge. In addition, bar-related boxy/peanut
(B/P) structures were also identified and characterised. We find only three
galaxies hosting a single-component bulge (two pseudobulges and one classical
bulge). We find evidence of composite bulges coming in two main types based on
their formation: secular-built and merger- and secular-built. We call
secular-built to composite bulges made of entirely by structures associated
with secular processes such as pseudo bulges, central disks, or B/P bulges. We
find four composite bulges of this kind in our sample. On the other hand,
merger- and secular-built bulges are those where structures with different
formation paths coexist within the same galaxy, i.e., a classical bulge
coexisting with a secular-built structure (pseudobulge, central disk, or B/P).
Three bulges of this kind were found in the sample. We remark on the importance
of detecting kinematic structures such as sigma-drops to identify composite
bulges. A large fraction (80%) of galaxies were found to host sigma-drops or
sigma-plateaus in our sample revealing their high incidence in barred galaxies.
The high frequency of composite bulges in barred galaxies points towards a
complex formation and evolutionary scenario. Moreover, the evidence for
coexisting merger- and secular-built bulges reinforce this idea. We discuss how
the presence of different bulge types, with different formation histories and
timescales, can constrain current models of bulge formation.Comment: 20 pages, 7 figures. Accepted for publication in A&
String Threshold corrections in models with spondaneously broken supersymmetry

We analyse a class of four-dimensional heterotic ground states with N=2 space-time supersymmetry. From the ten-dimensional perspective, such models can be viewed as compactifications on a six-dimensional manifold with SU(2) holonomy, which is locally but not globally K3 x T^2. The maximal N=4 supersymmetry is spontaneously broken to N=2. The masses of the two massive gravitinos depend on the (T,U) moduli of T^2. We evaluate the one-loop threshold corrections of gauge and R^2 couplings and we show that they fall in several universality classes, in contrast to what happens in usual K3 x T^2 compactifications, where the N=4 supersymmetry is explicitly broken to N=2, and where a single universality class appears. These universality properties follow from the structure of the elliptic genus. The behaviour of the threshold corrections as functions of the moduli is analysed in detail: it is singular across several rational lines of the T^2 moduli because of the appearance of extra massless states, and suffers only from logarithmic singularities at large radii. These features differ substantially from the ordinary K3 x T^2 compactifications, thereby reflecting the existence of spontaneously-broken N=4 supersymmetry. Although our results are valid in the general framework defined above, we also point out several properties, specific to orbifold constructions, which might be of phenomenological relevance
The Adjoint Vacuum Sector of Massless QCD2

We consider a "one current" state, obtained by appication of a color current
on the "adjoint" vacuum, in $QCD_2$, with quarks in fundamental representation.
The quarks are taken to be massless. The theory on the light-front can be
"currentized", namely formulated in terms of currents only. The adjoint vacuum
is obtained by applying a current derivative, at zero momentum, on the singlet
vacuum. In general the "one current" states are not eigenstates of
$M^2=2P^+P^-$, except in the large $N_f$ limit. Problems with infra-red
regularizations are pointed out. Connection to fermionic structure is made.Comment: Talk presented by Y. Frishman at the Light Cone Workshop in Cairns,
  Australia, July 200
Quadrics on Complex Riemannian Spaces of Constant Curvature, Separation
  of Variables and the Gaudin Magnet

We consider integrable systems that are connected with orthogonal separation
of variables in complex Riemannian spaces of constant curvature. An isomorphism
with the hyperbolic Gaudin magnet, previously pointed out by one of us, extends
to coordinates of this type. The complete classification of these separable
coordinate systems is provided by means of the corresponding $L$-matrices for
the Gaudin magnet. The limiting procedures (or $\epsilon $ calculus) which
relate various degenerate orthogonal coordinate systems play a crucial result
in the classification of all such systems.Comment: 24 pages, AmsTeX. IMA Preprint Series # 1153, July 199
Non-monotone travelling waves in a single species reaction-diffusion
  equation with delay

We prove the existence of a continuous family of positive and generally
non-monotone travelling fronts in delayed reaction-diffusion equations
$u_t(t,x) = \Delta u(t,x)- u(t,x) + g(u(t-h,x)) (*)$, when $g \in C^2(R_+,R_+)$
has exactly two fixed points: $x_1= 0$ and $x_2= a >0$. Recently, non-monotonic
waves were observed in numerical simulations by various authors. Here, for a
wide range of parameters, we explain why such waves appear naturally as the
delay $h$ grows. For the case of $g$ with negative Schwarzian, our conditions
are rather optimal; we observe that the well known Mackey-Glass type equations
with diffusion fall within this subclass of $(*)$. As an example, we consider
the diffusive Nicholson's blowflies equation.Comment: 23 pages, several important modifications are made. Some references
  and comments added to the previous version. To appear in the Journal of
  Differential Equation
The Angular Momentum of Magnetized Molecular Cloud Cores: A Two-Dimensional-Three-Dimensional Comparison

In this work, we present a detailed study of the rotational properties of magnetized and self-gravitating dense molecular cloud cores formed in a set of two very high resolution three-dimensional molecular cloud simulations with decaying turbulence. The simulations have been performed using the adaptative mesh refinement code RAMSES with an effective resolution of \(4096^3\) grid cells. One simulation represents a mildly magnetically-supercritical cloud and the other a strongly magnetically-supercritical cloud. We identify dense cores at a number of selected epochs in the simulations at two density thresholds which roughly mimick the excitation densities of the \(NH_{3} (J − K)=(1,1)\) transition and the \(N_{2}H^{+}(1-0)\) emission line. A noticeable global difference between the two simulations is the core formation efficiency (CFE) of the high density cores. In the strongly supercritical simulations the CFE is 33 percent per unit free-fall time of the cloud \((t_{ff,cl})\), whereas in the mildly supercritical simulations this value goes down to \(\sim 6\) percent per unit \(t_{ff,cl}\). A comparison of the intrinsic specific angular momentum \((j_{3D})\) distributions of the cores with the specific angular momentum derived using synthetic two-dimensional velocity maps of the cores ((j_{3D})\) , shows that the synthetic observations tend to overestimate the true value of the specific angular momentum by a factor of \(\sim 8−10\). We find that the distribution of the ratio \(j_{3D}/j_{2D}\) of the cores peaks at around \(\sim 0.1\). The origin of this discrepancy lies in the fact that contrary to the intrinsic determination of j which sums up the individual gas parcels contributions to the angular momentum, the determination of the specific angular momentum using the standard observational procedure which is based on a measurement on the global velocity gradient under the hypothesis of uniform rotation smoothes out the complex fluctuations present in the three-dimensional velocity field. Our results may well provide a natural explanation for the discrepancy by a factor ∼ 10 observed between the intrinsic three-dimensional distributions of the specific angular momentum and the corresponding distributions derived in real observations. We suggest that previous and future measurements of the specific angular momentum of dense cores which are based on the measurement of the observed global velocity gradients may need to be reduced by a factor of \(\sim 10\) in order to derive a more accurate estimate of the true specific angular momentum in the cores. We also show that the exponent of the size-specific angular momentum relation are smaller \((\sim 1.4)\) in the synthetic observations than their values derived in the three-dimensional space \((\sim 1.8)\).Astronom
The morphologies of massive galaxies from z~3 - Witnessing the 2
  channels of bulge growth

[abridged] We quantify the morphological evolution of z~0 massive galaxies
($M*/M_\odot\sim10^{11}$) from z~3 in the 5 CANDELS fields. The progenitors are
selected using abundance matching techniques to account for the mass growth.
The morphologies strongly evolve from z~3. At z<1, the population matches the
massive end of the Hubble sequence, with 30% of spheroids, 50% of galaxies with
equally dominant disk and bulge components and 20% of disks. At z~2-3 there is
a majority of irregular systems (~60-70%) with still 30% of spheroids.
  We then analyze the SFRs, gas fractions and structural properties for the
different morphologies independently. Our results suggest two distinct channels
for the growth of bulges in massive galaxies.
  Around 30-40% were already bulges at z~2.5, with low average SFRs and
gas-fractions (10-15%), high Sersic indices (n>3-4) and small effective radii
($R_e$~1 kpc) pointing towards an early formation through gas-rich mergers or
VDI. Between z~ 2.5 and z~0, they rapidly increase their size by a factor of
~4-5, become all passive but their global morphology remains unaltered. The
structural evolution is independent of the gas fractions, suggesting that it is
driven by ex-situ events.
  The remaining 60% experience a gradual morphological transformation, from
clumpy disks to more regular bulge+disks systems, essentially happening at z>1.
It results in the growth of a significant bulge component (n~3) for 2/3 of the
systems possibly through the migration of clumps while the remaining 1/3 keeps
a rather small bulge (n~1.5-2). The transition phase between disturbed and
relaxed systems and the emergence of the bulge is correlated with a decrease of
the star formation activity and the gas fractions. The growth of the effective
radii scales roughly with $H(z)^{-1}$ and it is therefore consistent with the
expected growth of disks in galaxy haloes.Comment: accepted for publication in ApJ - comments welcom
Uniform electron gases: III. Low-density gases on three-dimensional
  spheres

By combining variational Monte Carlo (VMC) and complete-basis-set limit
Hartree-Fock (HF) calculations, we have obtained near-exact correlation
energies for low-density same-spin electrons on a three-dimensional sphere
(3-sphere), i.e.~the surface of a four-dimensional ball. In the VMC
calculations, we compare the efficacies of two types of one-electron basis
functions for these strongly correlated systems, and analyze the energy
convergence with respect to the quality of the Jastrow factor. The HF
calculations employ spherical Gaussian functions (SGFs) which are the
curved-space analogs of cartesian Gaussian functions. At low densities, the
electrons become relatively localized into Wigner crystals, and the natural SGF
centers are found by solving the Thomson problem (i.e. the minimum-energy
arrangement of $n$ point charges) on the 3-sphere for various values of $n$. We
have found 11 special values of $n$ whose Thomson sites are equivalent. Three
of these are the vertices of four-dimensional Platonic solids --- the
hyper-tetrahedron ($n=5$), the hyper-octahedron ($n=8$) and the 24-cell
($n=24$) --- and a fourth is a highly symmetric structure ($n=13$) which has
not previously been reported. By calculating the harmonic frequencies of the
electrons around their equilibrium positions, we also find the first-order
vibrational corrections to the Thomson energy.Comment: 6 pages, 2 figures, accepted for publication in the Journal of
  Chemical Physic
Measurement of neutron induced fission of (235)U, (233)U and (245)Cm with the FIC detector at the CERN n_TOF facility

A series of measurements of neutron induced fission cross section of various TRU isotopes have been performed at the CERN n_TOF spallation neutron facility, in the energy range from thermal to nearly 250 MeV. The experimental apparatus consists in a fast ionization chamber (FIC), used as a fission fragment detector with a high efficiency. Good discrimination between alphas and fission fragments can be obtained with a simple amplitude threshold. In order to allow the monitoring of the neutron beam and to extract the n_TOF neutron flux, the well known cross section of the (235)U(n,f) reaction, considered as a fission standard, has been used. Preliminary results for the cross section are shown for some selected isotopes such as (235)U, (233)U and (245)Cm in the energy range from 0.050 eV to about 2 MeV
Orbital and physical properties of the sigma Ori Aa, Ab, B triple system

We provide a complete characterization of the astrophysical properties of the sigma Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric sigma Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhes method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the sigma Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus other available information on photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the sigma Ori Aa, Ab pair. We provided indirect arguments indicating that sigma Ori B is a fast-rotating early B dwarf. The FASTWIND+BONNSAI analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while sigma Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the sigma Orionis cluster, at 3 +/- 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the s Orionis cluster, the interpretation of the strong X-ray emission detected for sigma Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects