5,380 research outputs found
In-Medium Modifications of Scalar Charm Mesons in Nuclear Matter
Employing QCD sum rules the in-medium modifications of scalar charm mesons in
a cold nuclear matter environment are estimated. The mass splitting of
D*-D*-bar is quantified.Comment: Talk given at QCD 10, Montpelier, France, 27.06.-05.07.201
Evidence for In-Medium Changes of Four-Quark Condensates
Utilizing the QCD sum rule approach to the behavior of the omega meson in
nuclear matter we derive evidence for in-medium changes of particular
four-quark condensates from the recent CB-TAPS experiment for the reaction
gamma + A -> A' + omega (-> pi0 gamma) with A = Nb and LH2.Comment: Submitted to Phys. Rev. Lett., 4 page
The Right Match: A Strong Principal in Every Public School
This report has one central premise: Keeping great principals starts with hiring the right principal. Even as Chicago fights to retain principals long enough to make student learning and school culture gains more permanent, we must recognize some principal attrition is inevitable.More than 70,000 students started the 2016-17 school year with a new principal, and at least 60 schools will need a new principal each year for the foreseeable future. The stakes are high: No great public school exists without great leadership. In fact, variation in principal quality accounts for about 25 percent of a school's total impact on student learning. Yet, more than four out of every 10 public school principals in Chicago leave before they begin their fifth year. To keep great principals, we have to make the right match from the start
Relativistic Langevin Dynamics in Expanding Media
We study the consequences of different realizations of diffusion processes in
relativistic Langevin simulations. We elaborate on the Ito-Stratonovich dilemma
by showing how microscopically calculated transport coefficients as obtained
from a Boltzmann/Fokker-Planck equation can be implemented to lead to an
unambiguous realization of the Langevin process. Pertinent examples within the
pre-point (Ito) and post-point (H\"anggi-Klimontovich) Langevin prescriptions
are worked out explicitly. Deviations from this implementation are shown to
generate variants of the Boltzmann distribution as the stationary (equilibrium)
solutions. Finally, we explicitly verify how the Lorentz invariance of the
Langevin process is maintained in the presence of an expanding medium,
including the case of an "elliptic flow" transmitted to a Brownian test
particle. This is particularly relevant for using heavy-flavor diffusion as a
quantitative tool to diagnose transport properties of QCD matter as created in
ultrarelativistic heavy-ion collisions.Comment: 8 pages, 4 figures; v2: Reference adde
A chiral crystal in cold QCD matter at intermediate densities?
The analogue of Overhauser (particle-hole) pairing in electronic systems
(spin-density waves with non-zero total momentum ) is analyzed in
finite-density QCD for 3 colors and 2 flavors, and compared to the
color-superconducting BCS ground state (particle-particle pairing, =0). The
calculations are based on effective nonperturbative four-fermion interactions
acting in both the scalar diquark as well as the scalar-isoscalar quark-hole
('') channel. Within the Nambu-Gorkov formalism we set up the coupled
channel problem including multiple chiral density wave formation, and evaluate
the resulting gaps and free energies. Employing medium-modified
instanton-induced 't Hooft interactions, as applicable around
GeV (or 4 times nuclear saturation density), we find the 'chiral crystal phase'
to be competitive with the color superconductor.Comment: 14 pages ReVTeX, including 11 ps-/eps-figure
Dileptons in High-Energy Heavy-Ion Collisions
The current status of our understanding of dilepton production in
ultrarelativistic heavy-ion collisions is discussed with special emphasis on
signals from the (approach towards) chirally restored and deconfined phases. In
particular, recent results of the CERN-SPS low-energy runs are compared to
model predictions and interpreted. Prospects for RHIC experiments are given.Comment: Invited talk at ICPAQGP, Jaipur, India, Nov. 26-30, 2001; 1 Latex and
9 eps-/ps-files Reoprt No.: SUNY-NTG-02-0
Hadro-Chemistry and Evolution of (Anti-) Baryon Densities at RHIC
The consequences of hadro-chemical freezeout for the subsequent hadron gas
evolution in central heavy-ion collisions at RHIC and LHC energies are
discussed with special emphasis on effects due to antibaryons. Contrary to
naive expectations, their individual conservation, as implied by experimental
data, has significant impact on the chemical off-equilibrium composition of
hadronic matter at collider energies. This may reflect on a variety of
observables including source sizes and dilepton spectra.Comment: 4 pages ReVTeX incl. 3 ps-figs, submitted to PR
Trouble for MAC
We show that the next-to-leading corrections to the kernel of the gap
equation can be large and of opposite sign to the lowest order kernel, in the
presence of a gauge boson mass. This calls into question the reliability of the
Most Attractive Channel hypothesis.Comment: 8 pages, 1 figure, LaTe
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