[Jlab-seminars] Physics Seminar Announcement

[Luci Collins]

*Physics Seminar
**Aug.24, 2012
11:00 AM
CEBAF Center AUD.
Cookies and Coffee 10:45AM
*
*"Heavy Quarkonium Production at Hadron Colliders"

Prof. Guangda Chao
Peking University, China *

  Abstract: One of the long standing challenging problem in heavy flavor 
physics is the production of heavy quarkonia at hadron colliders. The 
J/psi and psi' production cross sections at high p_T observed by CDF at 
the Tevatron are about two orders of magnitude larger than conventional 
QCD predictions. In the framework of nonrelativistic QCD (NRQCD), the 
color-octet gluon fragmentation might increase the cross sections, but 
the predicted trasverse polarizations of J/psi and psi' are in 
contradiction with the measurements. We show that the next-to-leading 
order (NLO) QCD corrections including both the color-singlet and 
color-octet channels may essentially change the large p_T behavior of 
J/psi, and that the predicted cross sections can be in good agreement 
with the Tevatron data and the newly observed LHC data at large p_T. 
Moreover, the J/psi polarization puzzle may also be explained. However, 
we find that the long-distance matrix elements (LDMEs) extracted from 
hadron colliders are not compatible with that extracted from the e+e- 
annihilation data observed by Bell at the B factory. Possible reasons 
for this disagreement are suggested. Furhther theoretical investigation 
and experimental measurement are also needed. Puzzles in the P-wave 
charmonium states chi_cJ are also discussed.

The seminar is based on the work:  Phys.Rev.Lett.106,042002(2011),  
Phys.Rev.D83,111503(2011), Phys.Rev.D84,114001(2011), 
Phys.Rev.Lett.108,242004(2012), Phys.Rev.D85,114003(2012) as well as 
some previous works.





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