236 research outputs found
Theory on Hadrons in Nuclear Medium
After decades-long attempts to measure the mass shift and understand the
origin of hadron mass, it became clear that one has to analyze hadrons with
small vacuum width. Also, to identify the effect of chiral symmetry breaking,
one has to start by looking at chiral partners. In this talk, I will review why
such consideration inevitably led us to consider and in nuclear
matter [T. Song, T. Hatsuda, S H Lee, PLB792 (2019) 160-169]. With the kaon
beam at JPARC, one could observe the mass shift of both particles in a nuclear
target experiment. Once the masses and mass difference of and
mesons are measured, we will be closer to understanding the origin of the
hadron masses and the effects of chiral symmetry breaking in them.Comment: 8 pages, Plenary talk at QNP-201
The mass of charmonium in nuclear matter
The masses of charmonium states immersed in nuclear matter are calculated in
LO QCD and in QCD sum rules. While the mass shift for are found to be
less than -10 MeV, those for the and and
are found to be more than -40 MeV. We investigate the feasibility
of observing such mass shifts in the future accelerator project at GSI.Comment: 5 pages, proceeding for Hadron 200
Quarkonium-Hadron Interactions in Perturbative QCD
The next to leading order (NLO) quarkonium-hadron cross section is calculated
in perturbative QCD. The corresponding leading order (LO) result was performed
by Peskin more than 20 years ago using the operator product expansion (OPE). In
this work, the calculation is performed using the Bethe-Salpeter amplitude and
the factorization formula. The soft divergence appearing in the intermediate
stages of the calculations are shown to vanish after adding all possible
crossed terms, while the collinear divergences are eliminated by mass
factorization. Applying the result to the Upsilon system, one finds that there
are large higher order correction near the threshold. The relevance of the
present result to the charmonium case is also discussed.Comment: Yonsei University. to be published in PR
Couplings between pion and charmed mesons
We compute the couplings ,,,
using QCD sum rules. These couplings are important inputs in the meson exchange
model calculations used to estimate the amount of absorption due to
pions and rho mesons in heavy ion collisions. Our sum rules are constructed at
the first order in the pion momentum , which give the couplings that are
not trivially related to the soft-pion theorem. Our calculated couplings, which
somewhat depend upon the values of the heavy meson decay constants, are
, , and .Comment: 16 pages including 4 postscript figures. To be published in European
Physical Journal
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