3,326 research outputs found
Three-particle systems with resonant subprocesses in a finite volume
In previous work, we have developed a relativistic, model-independent
three-particle quantization condition, but only under the assumption that no
poles are present in the two-particle K matrices that appear as scattering
subprocesses. Here we lift this restriction, by deriving the quantization
condition for identical scalar particles with a G-parity symmetry, in the case
that the two-particle K matrix has a pole in the kinematic regime of interest.
As in earlier work, our result involves intermediate infinite-volume quantities
with no direct physical interpretation, and we show how these are related to
the physical three-to-three scattering amplitude by integral equations. This
work opens the door to study processes such as , in which the is rigorously treated as a resonance state.Comment: 46 pages, 9 figures, JLAB-THY-18-2819, CERN-TH-2018-21
Facilitating Humanitarian Access to Pharmaceutical and Agricultural Innovation
Calls for intellectual property licensing strategies in the pharmaceutical and agricultural sectors that promote humanitarian access to product innovations for the benefit of the disadvantaged. Includes profiles of successful and promising strategies
Progress in three-particle scattering from LQCD
We present the status of our formalism for extracting three-particle
scattering observables from lattice QCD (LQCD). The method relies on relating
the discrete finite-volume spectrum of a quantum field theory with its
scattering amplitudes. As the finite-volume spectrum can be directly determined
in LQCD, this provides a method for determining scattering observables, and
associated resonance properties, from the underlying theory. In a pair of
papers published over the last two years, two of us have extended this approach
to apply to relativistic three-particle scattering states. In this talk we
summarize recent progress in checking and further extending this result. We
describe an extension of the formalism to include systems in which two-to-three
transitions can occur. We then present a check of the previously published
formalism, in which we reproduce the known finite-volume energy shift of a
three-particle bound state.Comment: 9 pages, 3 figures, proceedings for XIIth Quark Confinement and the
Hadron Spectrum (CONF12
Numerical study of the relativistic three-body quantization condition in the isotropic approximation
We present numerical results showing how our recently proposed relativistic
three-particle quantization condition can be used in practice. Using the
isotropic (generalized -wave) approximation, and keeping only the leading
terms in the effective range expansion, we show how the quantization condition
can be solved numerically in a straightforward manner. In addition, we show how
the integral equations that relate the intermediate three-particle
infinite-volume scattering quantity, , to the
physical scattering amplitude can be solved at and below threshold. We test our
methods by reproducing known analytic results for the expansion of the
threshold state, the volume dependence of three-particle bound-state energies,
and the Bethe-Salpeter wavefunctions for these bound states. We also find that
certain values of lead to unphysical finite-volume
energies, and give a preliminary analysis of these artifacts.Comment: 32 pages, 21 figures, JLAB-THY-18-2657, CERN-TH-2018-046; version 2:
corrected typos, updated references, minor stylistic changes---consistent
with published versio
Unitarity of the infinite-volume three-particle scattering amplitude arising from a finite-volume formalism
In a previous publication, two of us derived a relation between the
scattering amplitude of three identical bosons, , and a real
function referred to as the {divergence-free} K matrix and denoted . The result arose in the context of a relation between
finite-volume energies and , derived to all orders in
the perturbative expansion of a generic low-energy effective field theory. In
this work we set aside the role of the finite volume and focus on the
infinite-volume relation between and .
We show that, for any real choice of ,
satisfies the three-particle unitarity constraint to all orders. Given that
is also free of a class of kinematic divergences,
the function may provide a useful tool for parametrizing three-body scattering
data. Applications include the phenomenological analysis of experimental data
(where the connection to the finite volume is irrelevant) as well as
calculations in lattice quantum chromodynamics (where the volume plays a key
role).Comment: 19 pages, 4 figures, JLAB-THY-19-2945, CERN-TH-2019-07
Progress report on the relativistic three-particle quantization condition
We describe recent work on the relativistic three-particle quantization
condition, generalizing and applying the original formalism of Hansen and
Sharpe, and of Brice\~no, Hansen and Sharpe. In particular, we sketch three
recent developments: the generalization of the formalism to include K-matrix
poles; the numerical implementation of the quantization condition in the
isotropic approximation; and ongoing work extending the description of the
three-particle divergence-free K matrix beyond the isotropic approximation.Comment: 7 pages, 1 figure, Proceedings of Lattice 201
Three-Particle Systems With Resonant Subprocesses in a Finite Volume
In previous work, we have developed a relativistic, model-independent three-particle quantization condition, but only under the assumption that no poles are present in the two-particle K matrices that appear as scattering subprocesses [M.âT. Hansen and S.âR. Sharpe, Phys. Rev. D 90, 116003 (2014); M.âT. Hansen and S.âR. Sharpe, Phys. Rev. D 92, 114509 (2015); R.âA. Briceño et al., Phys. Rev. D 95, 074510 (2017).]. Here we lift this restriction, by deriving the quantization condition for identical scalar particles with a G-parity symmetry, in the case that the two-particle K matrix has a pole in the kinematic regime of interest. As in earlier work, our result involves intermediate infinite-volume quantities with no direct physical interpretation, and we show how these are related to the physical three-to-three scattering amplitude by integral equations. This work opens the door to study processes such as a2âÏÏâÏÏÏ, in which the Ï is rigorously treated as a resonance state
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Preliminary Results of American Eel Sampling Efforts in Gulf of Mexico Drainages of Texas
American Eel Anguilla rostrata has a unique and complex life history that is fairly well-studied on the eastern coast of the United States, but few studies have been done on Gulf of Mexico drainages. To inform conservation and management decisions, efforts to better understand the population structure, seasonal dynamics, and life history of American Eel are underway. The primary objectives of our efforts are to assess the current and historical distribution and abundance, habitat use, movement patterns, parasite occurrence, diet and population structure of American Eel across all life stages in Gulf of Mexico drainages of Texas.Texas State Wildlife Grant Program grants T-173-R-1 and T-172-R-1 in cooperation with the U.S. Fish and Wildlife Service, Wildlife and Sport Fish Restoration ProgramIntegrative Biolog
Numerical Study of the Relativistic Three-Body Quantization Condition in the Isotropic Approximation
We present numerical results showing how our recently proposed relativistic three-particle quantization condition can be used in practice. Using the isotropic (generalized s-wave) approximation, and keeping only the leading terms in the effective range expansion, we show how the quantization condition can be solved numerically in a straightforward manner. In addition, we show how the integral equations that relate the intermediate three-particle infinite-volume scattering quantity, Kdf,3, to the physical scattering amplitude can be solved at and below threshold. We test our methods by reproducing known analytic results for the 1/L expansion of the threshold state, the volume dependence of three-particle bound-state energies, and the Bethe-Salpeter wave functions for these bound states. We also find that certain values of Kdf;3 lead to unphysical finite-volume energies, and give a preliminary analysis of these artifacts
Scaling properties of a low-actuation pressure microfluidic valve
Using basic physical arguments, we present a design and method for the fabrication of microfluidic valves using multilayer soft lithography. These on-off valves have extremely low actuation pressures and can be used to fabricate active functions, such as pumps and mixers in integrated microfluidic chips. We characterized the performance of the valves by measuring both the actuation pressure and flow resistance over a wide range of design parameters, and compared them to both finite element simulations and alternative valve geometries
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