23 research outputs found
US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report
This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in
Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference
The Two-Photon Exchange Experiment at DESY
We propose a new measurement of the ratio of positron-proton to
electron-proton elastic scattering at DESY. The purpose is to determine the
contributions beyond single-photon exchange, which are essential for the
Quantum Electrodynamic (QED) description of the most fundamental process in
hadronic physics. By utilizing a 20 cm long liquid hydrogen target in
conjunction with the extracted beam from the DESY synchrotron, we can achieve
an average luminosity of
cmssr ( times the luminosity
achieved by OLYMPUS). The proposed TPEX experiment entails a commissioning run
at 2 GeV, followed by measurements at 3 GeV, thereby providing new data up to
(GeV/) (twice the range of current measurements). We present
and discuss the proposed experimental setup, run plan, and expectations.Comment: 10 pages, 14 figures. arXiv admin note: substantial text overlap with
arXiv:2301.0470
Comparing proton momentum distributions in and 3 nuclei via H H and He measurements
We report the first measurement of the reaction cross-section
ratios for Helium-3 (He), Tritium (H), and Deuterium (). The
measurement covered a missing momentum range of
MeV, at large momentum transfer (
(GeV)) and , which minimized contributions from non
quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave
impulse approximation (PWIA) calculations using realistic spectral functions
and momentum distributions. The measured and PWIA-calculated cross-section
ratios for He and H extend to just above the typical nucleon
Fermi-momentum ( MeV) and differ from each other by , while for He/H they agree within the measurement accuracy of
about 3\%. At momenta above , the measured He/H ratios differ from
the calculation by . Final state interaction (FSI) calculations
using the generalized Eikonal Approximation indicate that FSI should change the
He/H cross-section ratio for this measurement by less than 5\%. If
these calculations are correct, then the differences at large missing momenta
between the He/H experimental and calculated ratios could be due to the
underlying interaction, and thus could provide new constraints on the
previously loosely-constrained short-distance parts of the interaction.Comment: 8 pages, 3 figures (4 panels