180 research outputs found
Symmetries and Symmetry Breaking
In understanding the world of matter, the introduction of symmetry principles
following experimentation or using the predictive power of symmetry principles
to guide experimentation is most profound. The conservation of energy, linear
momentum, angular momentum, charge, and CPT involve fundamental symmetries. All
other conservation laws are valid within a restricted subspace of the four
interactions: the strong, the electromagnetic, the weak, and the gravitational
interaction. In this paper comments are made regarding parity violation in
hadronic systems, charge symmetry breaking in two nucleon and few nucleon
systems, and time-reversal-invariance in hadronic systems.Comment: 5 Pages, LaTeX, 2 PostScript figures. Talk at 17th International
IUPAP Conference on Few-body Problems in Physics, June 5-10, 2003, Durham,
North Carolina, US
A Monitor of Beam Polarization Profiles for the TRIUMF Parity Experiment
TRIUMF experiment E497 is a study of parity violation in pp scattering at an
energy where the leading term in the analyzing power is expected to vanish,
thus measuring a unique combination of weak-interaction flavour conserving
terms. It is desired to reach a level of sensitivity of 2x10^-8 in both
statistical and systematic errors. The leading systematic errors depend on
transverse polarization components and, at least, the first moment of
transverse polarization. A novel polarimeter that measures profiles of both
transverse components of polarization as a function of position is described.Comment: 19 pages LaTeX, 10 PostScript figures. To appear in Nuclear
Instruments and Methods in Physics Research, Section
Parity Violation in Proton-Proton Scattering at 221 MeV
TRIUMF experiment 497 has measured the parity violating longitudinal
analyzing power, A_z, in pp elastic scattering at 221.3 MeV incident proton
energy. This paper includes details of the corrections, some of magnitude
comparable to A_z itself, required to arrive at the final result. The largest
correction was for the effects of first moments of transverse polarization. The
addition of the result, A_z=(0.84 \pm 0.29 (stat.) \pm 0.17 (syst.)) \times
10^{-7}, to the pp parity violation experimental data base greatly improves the
experimental constraints on the weak meson-nucleon coupling constants
h^{pp}_\rho and h^{pp}_\omega, and has implications for the interpretation of
electron parity violation experiments.Comment: 17 pages RevTeX, 14 PostScript figures. Revised version with
additions suggested by Phys. Rev.
Parity nonconserving observables in thermal neutron capture on a proton
We calculate parity nonconserving observables in the processes where a
neutron is captured on a proton at the threshold energy radiating a photon.
Various potential models such as Paris, Bonn and Argonne are used for the
strong interactions, and the meson-exchange description is employed for the
weak interactions between hadrons. The photon polarization in the
unpolarized neutron capture process and photon asymmetry in the
polarized neutron capture process are obtained in terms of the weak
meson-nucleon coupling constants. turns out to be basically
insensitive to the employed strong interaction models and thus can be uniquely
determined in terms of the weak coupling constants, but depends
significantly on the strong interaction models.Comment: 13 pages, 11 eps figure
Parity Violation in Proton-Proton Scattering at 221 MeV
The parity-violating longitudinal analyzing power, Az, has been measured in
pp elastic scattering at an incident proton energy of 221 MeV. The result
obtained is Az =(0.84 +/- 0.29 (stat.) +/- 0.17 (syst.)) x 10^{-7}. This
experiment is unique in that it selects a single parity violating transition
amplitude, 3P2-1D2, and consequently directly constrains the weak meson-nucleon
coupling constant h^pp_rho When this result is taken together with the existing
pp parity violation data, the weak meson-nucleon coupling constants h^pp_rho
and h^pp_omega can, for the first time, both be determined.Comment: 8 pages RevTeX4, 3 PostScript figures. Conclusion revised. New
information about weak coupling constants adde
Parity nonconserving two-pion exchange in elastic proton-proton scattering
Parity nonconserving two-pion exchange in elastic pp scattering is
investigated in the presence of phenomenological strong distortions in various
models. Parity violation is included in the nucleon-pion vertex considering NN
and N Delta(1232) intermediate states in box and crossed box diagrams. Using
the derived parity nonconserving two-pion exchange potential we calculate the
longitudinal analyzing power A_L in elastic scattering. The predicted
effect is of the same order as vector meson exchanges.Comment: 13 pages, 8 eps figure
Cooler Experiment Preparation
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Measurement of the Total Cross Section for the Reaction p + p → p + p + pio
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Nuclear Parity-Violation in Effective Field Theory
We reformulate the analysis of nuclear parity-violation (PV) within the
framework of effective field theory (EFT). To order Q, the PV nucleon-nucleon
(NN) interaction depends on five a priori unknown constants that parameterize
the leading-order, short-range four-nucleon operators. When pions are included
as explicit degrees of freedom, the potential contains additional medium- and
long-range components parameterized by PV piNN couplings. We derive the form of
the corresponding one- and two-pion-exchange potentials. We apply these
considerations to a set of existing and prospective PV few-body measurements
that may be used to determine the five independent low-energy constants
relevant to the pionless EFT and the additional constants associated with
dynamical pions. We also discuss the relationship between the conventional
meson-exchange framework and the EFT formulation, and argue that the latter
provides a more general and systematic basis for analyzing nuclear PV.Comment: 67 Page Latex file with typos correcte
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