Nuclear Physics Seminar

semester, 2009


Thursday, January 22nd 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, January 29th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, February 5th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, February 12th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
To be announced.

Thursday, February 19th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, February 26th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Laurens Keek, University of Minnesota
Subject: Recurring X-ray bursts from neutron stars

Hydrogen and helium accreted on a neutron star can undergo unstablethermonuclear burning, which is observable as a flash of X-rays. When fuel is accreted continuously, X-ray bursts occur with recurrence times of hours or days. We discuss what determines this timescale and show the puzzling observations of bursts with recurrence times of only minutes. Hydrogen and helium flashes build up a carbon-rich layer that extends down to the neutron star crust. When this layer burns in a flash, a so-called superburst can be observed. These are much rarer events than ordinary bursts. We place constraints on the superburst recurrence time of nine sources and show how they can be used to constrain models of the neutron star interior.


Thursday, March 5th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, March 12th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Yong-Zhong Qian, University of Minnesota
Subject: Chemical Evolution of the Early Universe

There is now a large database on high-resolution observations of elemental abundances in old stars that reside in the halo of our Galaxy. This represents an exquisite record of chemical evolution of the early universe and has important implications for the stellar sources producing the various elements. The observational data will be reviewed, as well as the current stellar models for nucleosynthesis. It will be shown that three different types of massive stellar sources are required to explain the data. In particular, hypernovae with large explosion energies and Fe yields are an important player.


Thursday, March 19th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, April 2nd 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, April 9th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Evan Frodermann, University of Minnesota
Subject: Sources of photons in heavy-ion collisions at both forward and mid-rapidity.

Thursday, April 16th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, April 23rd 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Todd Springer, University of Minnesota
Subject: Second Order Hydrodynamics from the Gravity Dual

I discuss the use of gauge/gravity duality in computing hydrodynamic dispersion relations for strongly coupled plasmas. I present recent work which has extended the computation of the sound mode dispersion relation up to third order in the momentum of the perturbation. Resulting formulas for the speed of sound, bulk viscosity, as well as some second order transport coefficients are presented for a specific class of gravity duals.


Thursday, April 30th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Projjwal Banerjee
Subject: Supernova Nucelosynthesis in Population III 13-50 Solar Mass Stars and Abundance Patterns of Extremely Metal-Poor Stars

Thursday, May 7th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Thursday, May 14th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week. Finals week.

Wednesday, September 9th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Organizational Meeting

Thursday, September 17th 2009
2:30 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Wednesday, September 23rd 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Purnendu Chakraborty , University of Minnesota
Subject: Viscosities from Linear Sigma Model

Wednesday, September 30th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Laurens Keek, University of Minnesota
Subject: Type-I X-ray bursts with too short recurrence times.

Wednesday, October 7th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Ke-Jung Chen, University of Minnesota
Subject: Multi-Dimensional Simulations of Pair-Instability Supernovae

Wednesday, October 14th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Wednesday, October 21st 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Joe Kapusta, University of Minnesota
Subject: Equation of State and Phase Fluctuations near the Chiral Critical Point

The thermodynamics and critical exponents and amplitudes of high temperature and dense matter near the chiral critical point is studied. The parameterized equation of state matches on to that calculated with lattice QCD at zero chemical potential and to the known properties of nuclear matter at zero temperature. The extent to which finite size effects wash out the phase separation near the critical point is determined. The degree to which the critical point acts as an attractor in high energy heavy ion collisions is also investigated.


Wednesday, October 28th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Zohreh Davoudi, University of Minnesota
Subject: The effect of second order dissipation on the sound velocity in the QCD plasma using the effective potential of the linear sigma model

The heavy ion collision experiments are in progress in order to
investigate how the Universe has evolved after the Big Bang. The recent
observations show that a nearly perfect fluid is produced after heavy
ion collisions. An appropriate incorporation of the relativistic
hydrodynamics and the field theory would help us to describe the
dynamics of QCD (Quantum Chromodynamics) matter under extreme
conditions, and to survey the expected phase transitions. Some efforts
to investigate the characteristics of the QCD plasma are devoted to an
ideal, non-dissipative one. To get the results which are highly in
accordance with the experiment, it is necessary to bring also in mind
the role of dissipation, particularly the second order dissipation,
because the first order dissipation will result in instabilities and
causality violation. We are to couple the field theory and the
hydrodynamics of the dissipative fluid in such a way that the effect of
second order dissipative coefficients in addition to the effect of the
fields will emerge in the properties of the quark-gluon plasma (QGP)
such as sound velocity. In this seminar, after deriving the
thermodynamical potential using the effective potential of the linear
sigma model, we will study the effect of second order dissipation on the
sound velocity in the QGP and its variation near the chiral phase
transition.


Wednesday, November 4th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Thomas Kelley, University of Minnesota
Subject: Holography in Finite-Temperature Field Theory

I use the AdS/CFT correspondence to explore the non-perturbative realms of a QCD-like theory at finite temperatures. One hopes the strongly-coupled Quark-Gluon Plasma (sQGP) could be succinctly described by such a model.


Wednesday, November 11th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Meng-Ru Wu, University of Minnesota
Subject: Spectral split of supernova neutrinos

The spectral split is the most interesting feature of neutrino
flavor transformation from the neutrino-neutrino interaction, which is dominant in a supernovae environment. A simple model to explain this phenomenon will be discussed.


Wednesday, November 18th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Projjwal Banerjee, University of Minnesota
Subject: Detection of Supernova Neutrinos by Neutrino-Proton Elastic Scattering

Wednesday, November 25th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
There will be no seminar this week.

Wednesday, December 2nd 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Sener Ozonder, University of Minnesota
Subject: Chiral Magnetic Effect

The vacuum of QCD is infinitely degenerate, but perturbative processes such as scattering or particle annihilation/creation do not change the vacuum of the gluons. However, nonperturbative topological solutions of the gluon field such as sphalerons, which are not suppressed at finite temperature, bring about transitions between different vacua. The Chern-Simons winding number associated with those transitions controls the anomaly of the U(1) axial current of the quarks. As a result of nonconservation of the axial current, sphalerons produce more left handed quarks and antiquarks than right handed ones, or vice versa. Under the influence of the strong magnetic field produced by off-central heavy-ion collisions, quark matter with nonzero net chirality (or handedness) polarizes along the axis of the magnetic field so that positively and negatively charged quarks accumulate oppositely, i.e., an electric current is produced parallel to the magnetic field. All these relate to the electric dipole moment of quark gluon plasma, P and CP violation, and the E.B term which has no effect in classical electromagnetism. Modification of the hydrodynamic equations for incorporation of the axial anomaly is also considered along with the calculation of the new kinetic coefficient appearing with the additional term of vorticity added to the current.


Wednesday, December 9th 2009
1:25 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Sean Bartz, University of Minnesota
Subject: Masses of the mesons from a soft wall AdS/QCD model

The AdS/CFT correspondence establishes an effective dictionary between strongly coupled theories and higher-dimensional gravitational theories. This has led to five-dimensional phenomonological models to describe quantum chromodynamics, known as AdS/QCD. Because of the running coupling constant, these models must have a cutoff in the fifth conformal dimension. The specific model studied here is known as a soft wall model, and it uses a dilaton field as an effective cutoff. This results in a realistic mass spectrum for the radial excitations of the lowest-lying mesons.I will describe our model and its successful modeling of the scalar, vector, and axial meson masses. I will also discuss I will also discuss my ongoing work on the pions, and the unique challenges of this sector.

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