2,218 research outputs found
A Conformal Truncation Framework for Infinite-Volume Dynamics
We present a new framework for studying conformal field theories deformed by
one or more relevant operators. The original CFT is described in infinite
volume using a basis of states with definite momentum, , and conformal
Casimir, . The relevant deformation is then considered using
lightcone quantization, with the resulting Hamiltonian expressed in terms of
this CFT basis. Truncating to states with , one can numerically find the resulting spectrum, as well
as other dynamical quantities, such as spectral densities of operators. This
method requires the introduction of an appropriate regulator, which can be
chosen to preserve the conformal structure of the basis. We check this
framework in three dimensions for various perturbative deformations of a free
scalar CFT, and for the case of a free CFT deformed by a mass term and a
non-perturbative quartic interaction at large-. In all cases, the truncation
scheme correctly reproduces known analytic results. We also discuss a general
procedure for generating a basis of Casimir eigenstates for a free CFT in any
number of dimensions.Comment: 48+37 pages, 17 figures; v2: references added, small clarification
Solidification in soft-core fluids: disordered solids from fast solidification fronts
Using dynamical density functional theory we calculate the speed of
solidification fronts advancing into a quenched two-dimensional model fluid of
soft-core particles. We find that solidification fronts can advance via two
different mechanisms, depending on the depth of the quench. For shallow
quenches, the front propagation is via a nonlinear mechanism. For deep
quenches, front propagation is governed by a linear mechanism and in this
regime we are able to determine the front speed via a marginal stability
analysis. We find that the density modulations generated behind the advancing
front have a characteristic scale that differs from the wavelength of the
density modulation in thermodynamic equilibrium, i.e., the spacing between the
crystal planes in an equilibrium crystal. This leads to the subsequent
development of disorder in the solids that are formed. For the one-component
fluid, the particles are able to rearrange to form a well-ordered crystal, with
few defects. However, solidification fronts in a binary mixture exhibiting
crystalline phases with square and hexagonal ordering generate solids that are
unable to rearrange after the passage of the solidification front and a
significant amount of disorder remains in the system.Comment: 18 pages, 14 fig
RG Flow from Theory to the 2D Ising Model
We study 1+1 dimensional theory using the recently proposed method
of conformal truncation. Starting in the UV CFT of free field theory, we
construct a complete basis of states with definite conformal Casimir,
. We use these states to express the Hamiltonian of the full
interacting theory in lightcone quantization. After truncating to states with
, we numerically diagonalize the
Hamiltonian at strong coupling and study the resulting IR dynamics. We compute
non-perturbative spectral densities of several local operators, which are
equivalent to real-time, infinite-volume correlation functions. These spectral
densities, which include the Zamolodchikov -function along the full RG flow,
are calculable at any value of the coupling. Near criticality, our numerical
results reproduce correlation functions in the 2D Ising model.Comment: 31+12 page
Cloud-resolving simulations of mercury scavenging and deposition in thunderstorms
This study examines dynamical and microphysical features of convective clouds that affect mercury (Hg) wet scavenging and concentrations in rainfall. Using idealized numerical model simulations in the Regional Atmospheric Modeling System (RAMS), we diagnose vertical transport and scavenging of soluble Hg species – gaseous oxidized mercury (GOM) and particle-bound mercury (HgP), collectively Hg(II) – in thunderstorms under typical environmental conditions found in the Northeast and Southeast United States (US). Mercury scavenging efficiencies from various initial altitudes are diagnosed for a case study of a typical strong convective storm in the Southeast US. Assuming that soluble mercury concentrations are initially vertically uniform, the model results suggest that 60% of mercury deposited to the surface in rainwater originates from above the boundary layer (> 2 km). The free troposphere could supply a larger fraction of mercury wet deposition if GOM and HgP concentrations increase with altitude. We use radiosonde observations in the Northeast and Southeast to characterize three important environmental characteristics that influence thunderstorm morphology: convective available potential energy (CAPE), vertical shear (0–6 km) of horizontal wind (SHEAR) and precipitable water (PW). The Southeast US generally has lower SHEAR and higher CAPE and PW. We then use RAMS to test how PW and SHEAR impact mercury scavenging and deposition, while keeping the initial Hg(II) concentrations fixed in all experiments. We found that the mercury concentration in rainfall is sensitive to SHEAR with the nature of sensitivity differing depending upon the PW. Since CAPE and PW cannot be perturbed independently, we test their combined influence using an ensemble of thunderstorm simulations initialized with environmental conditions for the Northeast and Southeast US. These simulations, which begin with identical Hg(II) concentrations, predict higher mercury concentrations in rainfall from thunderstorms forming in the environmental conditions over the Southeast US compared to the Northeast US. A final simulation of a stratiform rain event produces lower mercury concentrations than in thunderstorms forming in environments typical of the Southeast US. The stratiform cloud scavenges mercury from the lowest ~ 4 km of the atmosphere, while thunderstorms scavenge up to ~ 10 km
The magnetic properties of Hf and Hf in the strong coupling deformed model
This paper reports NMR measurements of the magnetic dipole moments of two
high-K isomers, the 37/2, 51.4 m, 2740 keV state in Hf and the
8, 5.5 h, 1142 keV state in Hf by the method of on-line nuclear
orientation. Also included are results on the angular distributions of gamma
transitions in the decay of the Hf isotope. These yield high
precision E2/M1 multipole mixing ratios for transitions in bands built on the
23/2, 1.1 s, isomer at 1315 keV and on the 9/2, 0.663 ns, isomer at 321
keV. The new results are discussed in the light of the recently reported
finding of systematic dependence of the behavior of the g parameter
upon the quasi-proton and quasi-neutron make up of high-K isomeric states in
this region.Comment: 9 pages, 9 figures, accepted for publication in Physical Review
Nonperturbative dynamics of (2+1)d -theory from Hamiltonian truncation
We use Lightcone Conformal Truncation (LCT) -- a version of Hamiltonian
truncation -- to study the nonperturbative, real-time dynamics of
-theory in 2+1 dimensions. This theory has UV divergences that need to
be regulated. We review how, in a Hamiltonian framework with a total energy
cutoff, renormalization is necessarily \emph{state-dependent}, and UV
sensitivity cannot be canceled with standard local operator counterterms. To
overcome this problem, we present a prescription for constructing the
appropriate state-dependent counterterms for (2+1)d -theory in
lightcone quantization. We then use LCT with this counterterm prescription to
study -theory, focusing on the symmetry-preserving
phase. Specifically, we compute the spectrum as a function of the coupling and
demonstrate the closing of the mass gap at a (scheme-dependent) critical
coupling. We also compute Lorentz-invariant two-point functions, both at
generic strong coupling and near the critical point, where we demonstrate IR
universality and the vanishing of the trace of the stress tensor.Comment: 33 pages + appendices, 14 figures; references adde
Selective laser ionization of N 82 indium isotopes: the new r-process nuclide In
Production yields and beta-decay half-lives of very neutron-rich indium isotopes were determined at CERN/ISOLDE using isobaric selectivity of a resonance-ionization laser ion-source. Beta-delayed neutron multiscaling measurements have yielded improved half-lives for 206(6)~ms In, 165(3)~ms In and 141(5)~ms In. With 92(10)~ms In, a new r-process nuclide has been identified which acts as an important `waiting-point' in the In isotopic chain for neutron densities in the range n--10 n/cm, where the r-matter flow has already passed the abundance-peak region
Cancer symptom awareness and barriers to symptomatic presentation in England – Are we clear on cancer?
Background: Low cancer awareness may contribute to delayed diagnosis and poor cancer survival. We aimed to quantify socio-demographic differences in cancer symptom awareness and barriers to symptomatic presentation in the English population.
Methods: Using a uniquely large data set (n=49?270), we examined the association of cancer symptom awareness and barriers to presentation with age, gender, marital status and socio-economic position (SEP), using logistic regression models to control for confounders.
Results: The youngest and oldest, the single and participants with the lowest SEP recognised the fewest cancer symptoms, and reported most barriers to presentation. Recognition of nine common cancer symptoms was significantly lower, and embarrassment, fear and difficulties in arranging transport to the doctor’s surgery were significantly more common in participants living in the most deprived areas than in the most affluent areas. Women were significantly more likely than men to both recognise common cancer symptoms and to report barriers. Women were much more likely compared with men to report that fear would put them off from going to the doctor.
Conclusions: Large and robust socio-demographic differences in recognition of some cancer symptoms, and perception of some barriers to presentation, highlight the need for targeted campaigns to encourage early presentation and improve cancer outcomes
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