Nuclear Theory Seminars at Texas A&M: Spring 2016
Location: Cyclotron Conference Room (CYCL300)

January 25, 4:00pm
C.Y. Wong (Oak Ridge)
"The Hadron p_T Distribution in HighEnergy pp Collisions and its Implications "
Abstract
Transverse momentum distribution of jets and hadrons provide useful
information on the collision mechanisms and their subsequent dynamics.
It was found recently that the hadron spectra spanning over 14 decades
of magnitude from the lowest of 0.5 GeV/c to the highest $p_T$ of a
few hundred GeV/c at central rapidity in pp collisions at LHC can be
adequately described by a single Tsallis distribution with only three
apparent degrees of freedom [1]. The simplicity of the p_T spectrum
suggests that a single mechanism dominates over a large pT domain at
central rapidity in these highenergy collisions. As the high$p_T$
region is known to arise from the relativistic hardscattering process
at high pT, one is led to the suggestion that the hardscattering
process dominates over a very large pT domain in these highenergy pp
collisions. We shall explore the implications of the pT distribution
on many related topics of the diminishing role of the competing
fluxtube fragmentation [2] and the initial conditions for the
momentum kick model of the nearside ridge in pp collisions [3].
[1] C.Y.Wong and G.Wilk, Acta Phys. Pol. {B43}, 2047 (2012);
C.Y.Wong and G.Wilk, Phys. Rev. {D87},114007 (2013);
C. Y. Wong, G. Wilk, L. J. L. Cirto and C. Tsallis,
Phys. Rev. {D91}, 114027 (2015).
[2] C.Y.Wong, Phys.Rev. {D92}, 074007 (2015).
[3] C.Y.Wong, Phys.Rev. {C84}, 024901 (2011).

January 27, 11:00am (CYCL228)
W.C. Chen (Florida State)
"Relativistic Mean Field Models for Finite Nuclei and Neutron Stars"
Abstract
Relativistic mean field (RMF) theory provides a natural framework to describe nuclear systems, ranging
from finite nuclei, nuclear matter, to neutron stars, in a single unified way. In this talk I will
introduce a calibration scheme to build RMF models using only real physical observables; properties of
nuclear matter, such as incompressibility and symmetry energy, become genuine model predictions. Moreover,
I will demonstrate how a followup covariance analysis can extract information content of the models,
including theoretical uncertainties and correlations.
This calibration scheme has been applied to study the elusive isovector sector and related physics.
Comparing with experimental and theoretical constraints, we find that the neutronskin thickness in 208Pb
should be (0.16 ± 0.1) fm, implying a soft symmetry energy with J = ( 30.92 ± 0.47 ) MeV and
L = (51.0 ± 1.5) MeV, respectively. The optimal model can also correctly locate the neutron drip line of
oxygen at 24O and predicts that of calcium to be at 60Ca. Then, I will turn to discuss the recent tension
between dense matter theory and the observation of neutron stars with very small radius (less than 10.6 km).
We find that in order to support twosolarmass neutron stars while preserving causality, the typical stellar
radius must be greater than 10.7 km—barely consistent with recent analyses.

February 1, 4:00pm
S. Cho (Kangwon National University, Korea)
"Reduction of the K* meson abundance and freezeout conditions in heavy ion collisions"
Abstract
We discuss the reduction of the K* meson abundance during the hadronic stage in heavy ion collisions. We also investigate the freezeout conditions of a particle in order to understand the productions of resonances, hadronic molecules and light nuclei in heavy ion collisions. Applying the kinetic freezeout condition to the daughter particles of K* mesons, we find that the larger suppression of the yield ratio of K*/K at LHC than at RHIC compared to the expectations from the statistical hadronization model reflects the lower kinetic freezeout temperature at LHC than at RHIC. Furthermore, we argue that for the light nuclei or hadronic molecules that are bound, the yields are affected by the freezeout condition of the respective particle in the hadronic matter, which leads to the observation that the deuteron production yields are independent of the size of deuteron, and depend only on the number of ground state constituents.

February 3, 4:00pm
S.H. Lee (Yonsei University, Korea)
"Few recent results on D meson in matter and dibaryons in constituent quark model"
Abstract
We probe effects of the partial chiral symmetry restoration to the mass of heavylight mesons in a constituent quark model by changing the constituent quark mass of the light quark. Due to the competing effect between the quark mass and the linearly rising potential, whose contribution to the energy increases as the quark mass decreases, the heavylight meson mass has a minimum value near the constituent quark mass typically used in the vacuum. Hence, the meson mass increases as one decreases the constituent quark mass consistent with recent QCD sum rule analyses, which show an increasing $D$ meson mass as the chiral order parameter decreases. We will also present some recent result on dibaryons in a constituent quark model.
Previous seminars
2015
Fall 2014
Spring 2014
Spring 2013
Spring 2012
Fall 2011
Spring 2011
Fall 2010
Spring 2010
Fall 2009
Spring 2009
Fall 2008
Spring 2008
Fall 2007
Spring 2007
Fall 2006
Spring 2006
Fall 2005
Spring 2005
Fall 2004
Spring 2004
Fall 2003
Nuclear
theory group home page
Last updated: Jan 12, 2016
Maintained by Ralf Rapp