1,674 research outputs found
Hyperon masses in nuclear matter
We analyze hyperon and nucleon mass shifts in nuclear matter using chiral perturbation theory. Expressions for the mass shifts that include strong interaction effects at leading order in the density are derived. Corrections to our results are suppressed by powers of the Fermi momentum divided by either the chiral symmetry breaking scale or the nucleon mass. Our work is relevant for neutron stars and for large hypernuclei
A New Expansion for Nucleon-Nucleon Interactions
We introduce a new and well defined power counting for the effective field
theory describing nucleon-nucleon interactions. Because of the large NN
scattering lengths it differs from other applications of chiral perturbation
theory and is facilitated by introducing an unusual subtraction scheme and
renormalization group analysis. Calculation to subleading order in the
expansion can be done analytically, and we present the results for both the 1S0
and 3S1-3D1 channels.Comment: 10 pages, 3 figures, latex. Corrected typo, small change to tex
Housing Assistance Payment: Potential impacts on financial incentives to work. ESRI WP610, January 2019
Since March 2017, a new income-related housing support for those with a long-term housing need called Housing Assistance Payment (HAP) has been available throughout the state. This paper examines the potential impact on financial work incentives of transferring long-run Rent Supplement recipients onto HAP with tenants’ rental contributions assessed through a national Differential Rents scheme, initially proposed by the Housing Agency but yet to be implemented. While such a system would strengthen the financial incentive for most long-term Rent Supplement claimants to be in full-time paid work, a small minority would continue to face quite weak incentives. This is driven by the receipt of multiple means-tested benefits – in particular, jobseekers allowance and one-parent family payment – which results in some low-income individuals facing very high effective marginal tax rates from relatively low levels of earnings
Heavy Quark Fragmentation to Baryons Containing Two Heavy Quarks
We discuss the fragmentation of a heavy quark to a baryon containing two
heavy quarks of mass . In this limit the heavy quarks
first combine perturbatively into a compact diquark with a radius small
compared to , which interacts with the light hadronic
degrees of freedom exactly as does a heavy antiquark. The subsequent evolution
of this diquark to a baryon is identical to the fragmentation of a
heavy antiquark to a meson. We apply this analysis to the production of baryons
of the form , , and .Comment: 9 pages, 1 figure included, uses harvmac.tex and epsf.tex, UCSD/PTH
93-11, CALT-68-1868, SLAC-PUB-622
An Effective Field Theory Calculation of the Parity Violating Asymmetry in n+p -> d+gamma
Weak interactions are expected to induce a parity violating pion-nucleon
coupling, h_{\pi NN}^{(1)}. This coupling should be measurable in a proposed
experiment to study the parity violating asymmetry A_\gamma in the process \vec
n + p \to d+\gamma. We compute the leading dependence of A_\gamma on the
coupling h_{\pi NN}^{(1)} using recently developed effective field theory
techniques and find an asymmetry of A_\gamma = +0.17 h_{\pi NN}^{(1)} at
leading order. This asymmetry has the opposite sign to that given by
Desplanques, Donoghue and Holstein.Comment: 7 pages, 2 figures from 3 eps files, late
- …