[ Upcoming Event
| Events This Semester
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Unless otherwise
stated, all seminars are Tuesdays at 4:00 pm in room
101 of Corcoran Hall.
| Upcoming
Event |
16 December 2008 (Tu), 16:00
am
in
Corcoran 101
Tom
Luu (Lawrence Livermore National Lab)
Using LQCD to extract hadronic interaction
parameters
I discuss current efforts to extract hadronic
interaction parameters from LQCD, enumerating current difficulties
placed by available computer resources and algorithm limitations.
I will also talk about future possibilities coming from (soon to come)
increased computer resources and algorithm development. Finally,
I will discuss the role that national labs, and in particular Lawrence
Livermore National Lab, can and should play in the area of LQCD.
[
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| Events
This Semester |
An
incomplete and never-up-to-date list of spectacular events.
Any similarities between the abstract and the
talk itself
are purely
incidental and may be intended.
Organisers: Dr.
Harald
W. Griesshammer (theory, 202-994-3849) and Dr.
Allena Opper (experiment, 202-994-0723)
Some seminars are coordinated with
the joint
seminars of the Experimental
Nuclear Physics Group and the Theory Group for Quarks,
Hadrons and Nuclei of the University of
Maryland at College Park. Their ENP/TQHN
Seminars (schedule)
are
Wednesdays
at 3:00 pm in room 1201 of the Physics Building
at UMd (directions).
| Date |
Speaker
(link
to SPIRES) |
Title
(abstract) |
02 Sep 2008
(Tu) |
|
No Seminar |
09
Sep 2008
(Tu) |
|
No Seminar |
16
Sep 2008
(Tu) |
|
No Seminar |
23
Sep 2008
(Tu) |
Barry
L. Berman (local) |
Determination
of the Azimuthal
Asymmetry in Deuteron Disintegration by Linearly Polarized Photons in
the GeV Energy region (.pdf file)
The
g13 experiment has recently been performed in Hall B at Jefferson
Lab.
In it, a liquid-deuterium target was bombarded by tagged polarized
photons in the energy range Egamma = 1.1-2.3 GeV, and the product
particles were detected in the CEBAF Large-Acceptance
Spectrometer.
The data, unprecedented in both quantity (52 billion events) and
quality (high resolution, very large kinematic coverage), are now being
reduced. We shall analyze these data to determine the
azimuthal
asymmetry in deuteron disintegration by linearly polarized
photons.
Our aim is to search for quark and gluon degrees of freedom in the
deuteron. This measurement will provide (a) novel
spin-dependent
information on the underlying mechanism of the reaction
gamma+d->p+n; (b) an improved understanding of the role of pQCD
at
low and intermediate energies; and (c) stringent constraints on the
nonperturbative QCD-based models of photonuclear reactions.
|
30
Sep 2008
(Tu) |
|
No Seminar (ECT workshop) |
07
Oct 2008
(Tu) |
Jacobus
Verbaarschot
(SUNY Stony Brook)
|
The Sign
Problem in QCD at Nonzero Baryon Density (.pdf file)
We give an introduction to the sign problem in QCD at nonzero chemical
potential and discuss physical effects of the sign of the fermion
determinant. Among others we show that the sign is responsible for
the discontinuity of the chiral condensate and is therefore essential
for the gross structure of the QCD phase diagram. The severity of
the sign problem is analyzed using chiral perturbation theory which
allows
us to extract not only the average value of the phase but
also its complete statistical distribution. A severe sign
problem does
not necessarily imply that observables cannot be calculated. We point
out the existence of a class of Teflon plated observables to support
this statement. |
14
Oct 2008
(Tu) |
Chung
Wen Kao
(Chung Yuan Christian U, Taiwan)
|
Two is
Too Many: Personal View of Two-Photon Physics (.pdf file) |
21
Oct 2008
(Tu) |
|
No Seminar (preparation for
DNP meeting) |
28
Oct 2008
(Tu) |
Ahmad
Idilbi (Duke U) |
Factorization and Resummation for
Color Octet Production at the LHC in Effective Theory (.pdf file)
We discuss the
production of heavy
colored particles at the Large Hadron Collider LHC through gluon-gluon
fusion process. A factorization theorem is obtained for this process
using soft collinear Effective Theory. Out factorization formula does
not depend on any assumptions related to the physics above the heavy
particle colored mass. In this sense it is universal.
Due to the large mass of the heavy particle and near the kinematic
threshold for production of such particles as resummation of large
logarithms must be performed. The matching coefficient at the heavy
particle mass scale depends obviously on the (unknown) physics above
that scale. In our work we unitlize the Manohar-Wick model to perform
the phenomenological study of the process considered. |
04
Nov 2008
(Tu) |
|
No Seminar |
11
Nov 2008
(Tu) |
|
No Seminar |
18
Nov 2008
(Tu) |
Nadia
Fomin
(U of Tennessee) |
Inclusive
Scattering from Nuclei at x>1 and High Q^2 with a 6 GeV
beam
(.pdf file)
Inclusive electron
scattering from nuclei at
large x
and $Q^2$
is the result of a
reaction
mechanism that includes both
quasi--elastic scattering from nucleons
and deep
inelastic scattering from the
quark
consitituents of the
nucleons. Consequently, it provides
an
opportunity to investigate
the transition from a regime
where
nucleon degrees of freedom
dominate to one where
the more
fundamental QCD interactions are
exposed. Data in this regime can be used to study a wide variety of
topics, including the extraction of nuclear
momentum
distributions,
the influence of final state interactions and the
approach
to y-scaling,
the strength of nucleon-nucleon correlations, and the
approach to
x- scaling, to name a few.
We recently peformed an experiment in
Jefferson Lab's Hall C
using a 6 GeV beam and a range of both light and heavy nuclei
which was
designed to significantly extend the kinematic region at high momentum
transfer and large (negative) y, previously explored in
SLAC experiment NE3 and Jefferson Lab experiment E89-008.
|
25
Nov 2008
(Tu) |
Elke
Aschenauer
(Jefferson Lab) |
The Spin of the Nucleon -- Highlights from HERMES
The
question after the individual parton
(quarks and gluons) contributions to the spin of the nucleon is even
after 20 years of experimental efforts not yet solved. After several
very precise measurements in polarized deep inelastic scattering it is
clear, that the spin of the nucleon can not be explained by the
contribution of the quarks alone. This is affirmed by the newest
results from HERMES on the inclusive spin structure function g1 and on
the individual contributions from the different quark flavors from
semi-inclusive deep inelastic scattering data. Recently HERMES has
started to measure the gluon polarization by isolating the photon gluon
fusion process in semi-inclusive deep inelastic scattering; latest
results on the contribution of the gluons to the nucleon spin will be
discussed. The clear experimental evidence of exclusive reactions,
especially DVCS, allows in the formalism of generalized parton
distributions the study of an other component of the nucleon spin the
orbital angular momentum. The most recent results on indications of the
size of the orbital angular momentum of quarks will be presented. To
complete the picture on the spin-structure of the nucleon it is
indispensable to measure the till now completely unknown spin structure
function called transversity. Results from measurements with a
transversely polarized hydrogen target give first insights to this
quantity. |
02
Dec 2008
(Tu) |
|
No Seminar |
| 16 Dec 2008 (Tu) |
Tom
Luu
(Lawrence Livermore National Lab) |
Using LQCD to extract hadronic interaction
parameters
I discuss current efforts to extract hadronic
interaction parameters from LQCD, enumerating current difficulties
placed by available computer resources and algorithm limitations.
I will also talk about future possibilities coming from (soon to come)
increased computer resources and algorithm development. Finally,
I will discuss the role that national labs, and in particular Lawrence
Livermore National Lab, can and should play in the area of LQCD. |
An asterisk * indicates seminars coordinated with UMd, i.e. usually a
seminar by the same speaker at UMd the day before; see their
schedule.
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