J production at high p T at STAR

J/ production at high p. T at STAR Zebo Tang (for STAR Collaboration) University of Science and Technology of China (USTC) Brookhaven National Laboratory (BNL) Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

Outline l l Motivation High-p. T J/ production in 200 Ge. V p+p collisions u u l High-p. T J/ production in heavy-ion collisions u u l J/ p. T spectra J/ -hadron correlations (New with higher statistics) Cu+Cu @ 200 Ge. V Au+Au @ 39 Ge. V (New) Summary Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 2

High p. T J/ in p+p collisions • Baseline for A+A 1. 8 Te. V • Production mechanism Color singlet model (CSM): LO Co lo lor Co underpredicted CDF data by order of magnitude r oc te t gle sin Color octet model (COM): NRQCD t good agreement with CDF cross section disagreement with CDF polarization Both have improvements by including NLO and/or NNLO* But only applicable and more distinguishable at intermediate/high p. T (p. T>3 -7 Ge. V/c) CDF measurement: PRL 79, 572 J/ 3 S • Feeddown J/ B J/ through J/ -hadron correlation LO CSM Zebo Tang, USTC/BNL 1 LO COM Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

STAR detector MTD EMC Barrel EMC End Cap FMS BBC FPD TPC PMD FTPC trigger TPC+BEMC+(MRPC-TOF) in this analysis HLT 2 coverage at mid-rapidity (|h|<1) Zebo Tang, USTC/BNL computing COMPLETE Ongoing Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 R&D

High p. T J/ signals 2005& 2006 2009 2005 STAR, PRC 80, 041902(R), 2009 • Tight cuts for correlation study • Spectra in progress Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

J/ p. T spectra STAR, PRC 80, 041902(R), 2009 Color singlet model: direct NNLO* still miss the high p. T part. P. Artoisenet et al. , Phys. Rev. Lett. 101, 152001 (2008), and J. P. Lansberg private communication. LO CS+CO: better agreement with the measurements, leave little room for higher charmonium states and B feeddown. G. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D 68, 034003 (2003), and private communication. J/ x. T scaling at high p. T: n=5. 6± 0. 2 (close to CS+CO prediction) Soft processes affect low p. T J/ production Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 6

Constrain bottom contribution STAR, PRL 95, 152301 (2005) J/ -h correlation STAR, PRC 80, 041902(R), 2009 STAR Preliminary h-h correlation • No significant near side J/ -hadron azimuthal angle correlation • Correlation show low B contribution (13 5) % Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 7

Correlations from Run 9 Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

B J/ / inclusive J/ PRC 80, 041902(R), 2009 PLB 200, 380, 1988 PLB 370, 239, 1996 PRD 71, 032001, 2005 • Consistent with previous results • No significant beam energy dependence • Can be used to constrain B production Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

Associated hadron p. T spectra STAR, PRL 95, 152301 (2005) Near side: Consistent with no associated hadron production Away side: Consistent with h-h correlation away-side seems to come from gluon/light quark fragmentation Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 10

High p. T J/ in A+A collisions • As a probe of the hot dense medium J/ dissociation due to color screening Signature of the T. Matsui and H. Satz, PLB 178, 416 (1986) QGP formation • Test hot wind dissociation temperature decreases as p. T • Investigate heavy quark energy loss Ad. S/CFT calculation open charm vs. hidden charm J/ /c H. Liu, K. Rajagopal and U. A. Wiedemann PRL 98, 182301(2007) and hep-ph/0607062 Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 11

Nuclear Modification Factor RAA STAR, PRC 80, 041902(R), 2009 l STAR Cu+Cu 0 -20%: RAA(p. T>5) = 1. 4 0. 2 u The only hadron measured to be not suppressed at high p. T in RHIC Heavy-ion collisions u Contrast to open charm. CS vs. CO? CNM effect？Formation A. Adil and I. Vitev, Phys. Lett. B 649, 139 (2007), and I. Vitev private communication; Time? S. Wicks et al. , Nucl. Phys. A 784, 426 (2007), and W. A. Horowitz private communication. H. Liu, K. Rajagopal and U. A. Wiedemann PRL 98, 182301(2007); l RAA>Ad. S/CFT+Hydro, 99% C. L. T. Gunji, J. Phys. G 35, 104137 (2008) Contrast to Ad. S/CFT+Hydro prediction l 2 -component models describes the overall trend Cu is too small? Zebo Tang, USTC/BNL X. Zhao and R. Rapp, Phys. Lett. B 664: 253, 2008; Y. P. Liu, et al. , Phys. Lett. B 678: 72 -76, 2009 Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

J/ from High Level Trigger Online histograms • Commission of online HLT in HIC • Significantly reduced the data volume and processing time for rare probes • J/ v 2 in progress H. Qiu, RHIC&AGS Users’ meeting 2010 Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

J/ in Au+Au @ 39 Ge. V 91± 22 4 s 82± 13 6 s • Clear signal seen in 39 Ge. V Au+Au • Expect ~1000 (13 s) J/ from full MB data • Able to cover p. T range (0, 5) Ge. V/c Reference data available from Fermi Lab Experiments and ISR Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

Summary u In 200 Ge. V p+p collisions l Extended previous spectra measurements to 14 Ge. V/c l Large S/B ratio allows correlation study l B has sizeable (not dominant) contribution at high p. T l high-p. T J/ away side hadron production consistent with gluon/quark fragmentation u In heavy-ion collisions l First observation of no suppression for hadron at high p. T at STAR in 200 Ge. V Cu+Cu collisions l Clear signals seen in 39 Ge. V Au+Au, covers p. T from 0 to 5 Ge. V/c Thank you! Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

Backup slides Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010 16

Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010

Associated hadron p. T spectra Fragmentation on away side Zebo Tang, USTC/BNL Hard Probes 2010, Eilat, Israel, Oct. 10 -15, 2010