HEP Monday Seminar Abstracts

November 15, 2010
Antoine Calvez, UCLA, Energy-Dependent Composition of UHECRs and the Future of Charged Particle Astronomy

Recent results from the Pierre Auger Observatory show an energy dependent chemical composition of
ultrahigh-energy cosmic rays (UHECRs), with a growing fraction of heavy elements at high energies. These results
suggest a possible non-negligible contribution from galactic sources. We show that in the case of UHECRs produced by gamma-ray bursts (GRBs), or by rare types of supernova explosions that took place in the Milky Way in the past; the change in the composition of the UHECRs can be the result of the difference
in diffusion times between different species. The anisotropy in the direction of the Galactic Center is
expected to be a few per cent on average, and the locations of the most recent/closest bursts can be
associated with observed clustering of UHECRs.

Januray 24, 2011
           Guennadi Borissov, Lancaster Univ, Searches for new sources of CP violation with DZero detector

I will review the latest results of the DZero experiment on the search for
new sources of CP violation and will discuss in detail the measurement of
the like-sign dimuon charge asymmetry. This result will be compared with
other Tevatron studies of CP violation in Bs system.

February 14, 2011
           Stephen Hsu, University of Oregon, Physical consequences of the QED theta angle

http://arxiv.org/abs/1012.2906

We describe a simple gedanken experiment which illustrates the
physical effects of the QED theta angle, a fundamental parameter of
Nature that has yet to be measured. The effects are manifest in
quantum phases analogous to those in the Aharonov-Bohm effect,
although they are not intrinsically topological. We also derive the
quantum phases using a functional Schrodinger approach, and generalize
the results to non-Abelian gauge theories

March 7, 2011
    Xin Qian, Caltech, Measurement of Single Target-Spin Asymmetry in Semi-Inclusive Pion Electroproduction on a Transversely Polarized $^3$He

Measuring parton distribution functions (PDF) which represent the flavor and spin structure of nucleon is important to reveal the information of quantum
chromodynamics in the confinement region. In particular, in parton model, the cross-section in the semi-inclusive deep inelastic scattering (SIDIS), can be
written as the product of PDF and fragmentation function which describe the parton hadronized process due to color force.

The JLab experiment E06-010 is focusing on measuring the target single spin asymmetry in the semi-inclusive deep inelastic
$\overrightarrow{^{3}\rm He}(e,e'\pi^{+,-})X$ reaction with a transversely polarized $^3\rm He$ target at JLab Hall A with a 5.89 GeV electron beam.
The leading pions and scattered electrons were detected in coincidence by the left High-Resolution Spectrometers ($HRS_L$) at $16^o$ and BigBite
spectrometer at $30^o$, respectively. Kinematic coverage was focused on the valence quark region, x $\sim$0.1-0.4, at
$Q2$ $\sim$ 1-3 (GeV/c)$^2$. The Collins and Sivers asymmetries of $^3\rm He$ and neutron were extracted. The overview of the experiment and the
preliminary results will be presented. Furthermore, the 12 GeV program with SoLID spectrometer and future possibilities at an EIC will be introduced.