8,146 research outputs found
Radiative corrections for few-nucleon systems
We use a combination of effective field theory and the renormalization group
to determine the impact of radiative corrections on the nucleon-nucleon
potential. In order to do so, we present a modified version of pionless
effective field theory inspired by earlier work in nonrelativistic quantum
electrodynamics. The renormalization group analysis of corrections in the
deuteron indicate that radiative corrections generate of the binding
energy. This work serves as an important starting point for the study of
radiative corrections in few-body systems relevant for precision tests of the
Standard Model.Comment: 5 pages, 3 figure
Implications of Large- QCD for the NN Interaction
We present a method for ordering two-nucleon interactions based upon their
scaling with the number of QCD colors, , in the limit that becomes
large. Available data in the two-nucleon sector shows general agreement with
this ordering, indicating that the method may be useful in other contexts where
data is less readily available. However, several caveats and potential pitfalls
can make the large- ordering fragile and/or vulnerable to
misinterpretation. We discuss the application of the large- analysis to
two- and three-nucleon interactions, including those originating from weak and
beyond-the-standard-model interactions, as well as two-nucleon external
currents. Finally, we discuss some open questions in the field.Comment: 23 pages, 1 figure, submitted to Ann. Rev. Nucl. Part. Sc
Markov equivalence for ancestral graphs
Ancestral graphs can encode conditional independence relations that arise in
directed acyclic graph (DAG) models with latent and selection variables.
However, for any ancestral graph, there may be several other graphs to which it
is Markov equivalent. We state and prove conditions under which two maximal
ancestral graphs are Markov equivalent to each other, thereby extending
analogous results for DAGs given by other authors. These conditions lead to an
algorithm for determining Markov equivalence that runs in time that is
polynomial in the number of vertices in the graph.Comment: Published in at http://dx.doi.org/10.1214/08-AOS626 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Worldline Monte Carlo method for few body nuclear physics
In this work we introduce a worldline based fermion Monte Carlo algorithm for
studying few body quantum mechanics of self-interacting fermions in the
Hamiltonian lattice formulation. Our motivation to construct the method comes
from our interest in studying renormalization of chiral nuclear effective field
theory with lattice regularization. In particular we wish to apply our method
to compute the lattice spacing dependence of local lattice interactions as we
take the continuum limit of the lattice theory. Our algorithm can compute
matrix elements of the operator where is the lattice
Hamiltonian and is a free real parameter. These elements help us
compute deep bound states that are well separated from scattering states even
at values of which are not very large. Computing these bound state
energies accurately can help us study renormalization of the lattice theory. In
addition to developing the algorithm, in this work we also introduce a finite
volume renormalization scheme for the lattice Hamiltonian of the leading
pionless effective field theory and show how it would work in the one and two
body sectors.Comment: 23 pages, 8 figures, 17 table
Basic mathematical programming applications to weed control in forestry
Many studies document herbicide performance for Heed and hardwood control in forestry. Few studies, hoHever, attemp t to develop optima l application strategies. Stand-level optindzation is presently limited due to lack of groHth and yield information. Forest-level optimization is possible, however, and has great potential to aid in planning forestry weed control prog rams
Revisiting the helium isotope-shift puzzle with improved uncertainties from nuclear structure corrections
Measurements of the difference between the squared charge radii of the helion
(He nucleus) and the -particle (He nucleus) have been
characterized by longstanding tensions, recently spotlighted in the 3.6
discrepancy of the extractions from ordinary atoms versus those from
muonic atoms. Here, we present a novel analysis of uncertainties in nuclear
structure corrections that must be supplied by theory to enable the extraction
of the difference in radii from spectroscopic experiments. We use modern
Bayesian inference techniques to quantify uncertainties stemming from the
truncation of the chiral effective field theory expansion of the nuclear force
for both muonic and ordinary atoms. With the new nuclear structure input, the
helium isotope-shift puzzle cannot be explained, rather it is reinforced to a 4
discrepancy.Comment: 5 pages, 3 figures, 2 table
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