11,192 research outputs found
On the origin of exponential growth in induced earthquakes in Groningen
The Groningen gas field shows exponential growth in earthquakes event counts
around a magnitude M1 with a doubling time of 6-9 years since 2001. This
behavior is identified with dimensionless curvature in land subsidence, which
has been evolving at a constant rate over the last few decades {essentially
uncorrelated to gas production.} We demonstrate our mechanism by a tabletop
crack formation experiment. The observed skewed distribution of event
magnitudes is matched by that of maxima of event clusters with a normal
distribution. It predicts about one event \,M5 per day in 2025, pointing to
increasing stress to human living conditions.Comment: 12 pages, 7 figures, to appear in Earthquakes and Structure
Screening properties of Gaussian electrolyte models, with application to dissipative particle dynamics
We investigate the screening properties of Gaussian charge models of
electrolyte solutions by analysing the asymptotic behaviour of the pair
distribution functions. We use a combination of Monte-Carlo simulations with
the hyper-netted chain integral equation closure, and the random phase
approximation, to establish the conditions under which a screening length is
well defined and the extent to which it matches the expected Debye length. For
practical applications, for example in dissipative particle dynamics, we are
able to summarise our results in succinct rules-of-thumb which can be used for
mesoscale modeling of electrolyte solutions. We thereby establish a solid
foundation for future work, such as the systematic incorporation of specific
ion effects.Comment: 9 pages, 9 figures, 1 table, RevTeX4-
Applications of Basis Light-Front Quantization to QED
Hamiltonian light-front quantum field theory provides a framework for
calculating both static and dynamic properties of strongly interacting
relativistic systems. Invariant masses, correlated parton amplitudes and
time-dependent scattering amplitudes, possibly with strong external
time-dependent fields, represent a few of the important applications. By
choosing the light-front gauge and adopting an orthonormal basis function
representation, we obtain a large, sparse, Hamiltonian matrix eigenvalue
problem for mass eigenstates that we solve by adapting ab initio no-core
methods of nuclear many-body theory. In the continuum limit, the infinite
matrix limit, we recover full covariance. Guided by the symmetries of
light-front quantized theory, we adopt a two-dimensional harmonic oscillator
basis for transverse modes that corresponds with eigensolutions of the
soft-wall anti-de Sitter/quantum chromodynamics (AdS/QCD) model obtained from
light-front holography. We outline our approach and present results for
non-linear Compton scattering, evaluated non-perturbatively, where a strong and
time-dependent laser field accelerates the electron and produces states of
higher invariant mass i.e. final states with photon emission.Comment: 6 pages, 4 figures, proceedings for Lightcone 2012 conference at
Delhi, Indi
Crucial Role of Quantum Entanglement in Bulk Properties of Solids
We demonstrate that the magnetic susceptibility of strongly alternating
antiferromagnetic spin-1/2 chains is an entanglement witness. Specifically,
magnetic susceptibility of copper nitrate (CN) measured in 1963 (Berger et al.,
Phys. Rev. 132, 1057 (1963)) cannot be described without presence of
entanglement. A detailed analysis of the spin correlations in CN as obtained
from neutron scattering experiments (Xu et al., Phys. Rev. Lett. 84, 4465
(2000)) provides microscopic support for this interpretation. We present a
quantitative analysis resulting in the critical temperature of 5K in both,
completely independent, experiments below which entanglement exists.Comment: 4 pages, 2 figure
First observation of Bs0 â D*s2+XÎŒ-Îœ decays
Using data collected with the LHCb detector in protonâproton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays B0sâD+sXÎŒâÎœ and B0sâD0K+XÎŒâÎœ are detected. Two structures are observed in the D0K+ mass spectrum at masses consistent with the known Ds1(2536)+ and Dâs22573)+ mesons. The measured branching fractions relative to the total B0s semileptonic rate are B(B0sâDâ+s2XÎŒâÎœ)/B(B0sâXÎŒâÎœ) = (3.3±1.0±0.4)%, and B(B0sâD+s1XÎŒâÎœ)/B(B0sâXÎŒâÎœ) = (5.4±1.2±0.5)%, where the ïŹrst uncertainty is statistical and the second is systematic. This is the ïŹrst observation of the Dâ+s2 state in B0s decays; we also measure its mass and width
Asymptotic thermal quark masses and the entropy of QCD in the large-N_f limit
We study the thermodynamics of QCD in the limit of large flavor number (N_f)
and test the proposal to resum the physics of hard thermal loops (HTL) through
a nonperturbative expression for the entropy obtained from a Phi-derivable
two-loop approximation. The fermionic contribution to the entropy involves a
full next-to-leading order evaluation of the asymptotic thermal quark mass,
which is non-local, and for which only a weighted average value was known
previously. For a natural choice of renormalization scale we find remarkably
good agreement of the next-to-leading-order HTL results for the fermion self
energy and in turn for the entropy with the respective exact large-N_f results
even at very large coupling.Comment: REVTEX, 31 pages, 16 figure
The Dynamics of the M87 Globular Cluster System
We present the results from a study of the dynamics of the system of globular
clusters around M87. After eliminating foreground galactic stars and background
galaxies, we end up with a sample of 205 bona fide M87 globular clusters for
which we have radial velocities determined from multi-slit spectra taken with
the LRIS on the Keck Telescope. We find that the mean radial velocity of the
M87 globular clusters agrees well with that of M87 itself, and that the
velocity histogram is well represented by a Gaussian distribution. We find
evidence for rotation in the globular cluster system. We find that the observed
velocity dispersion of the M87 globular cluster system increases with radius
from 270 \kms~ at = 9 kpc to 400 \kms~ at = 40 kpc. The
inferred mass-to-light ratio in solar units increases from 5 at = 9 kpc to
30 at = 40 kpc with . The long slit optical
spectroscopy near the center of M87 and the recent analysis of the ROSAT X-ray
data are in good agreement with this analysis near the nucleus and in the outer
parts of M87 respectively.Comment: 29 pages, TeX, with 6 Figures. Accepted for publication in the Ap
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