Recent Developments in Quarkonium and Open Flavour Production - PowerPoint PPT Presentation

Recent Developments in Quarkonium and Open Flavour Production Calculations Mathias Butenschön (Hamburg University) XIV International Conference on Hadron Spectroscopy

Production and decay rates of Heavy Quarkonia Heavy Quarkonia: Bound states of heavy quark and antiquark. Charmonia ( cc ̅ ) and Bottomonia ( bb ̅ )  Top decays to fast for bound state.  The classic approach: Color-singlet model Calculate cross section for heavy quark pair in physical  (=color neutral) state. In case of J/ ψ : cc ̅ [ 3 S 1 color singlet [1] ] Multiply by quarkonium wave function (or its derivative) at origin  Mid 90’s: Strong disagreement with Tevatron data apparent  Nonrelativistic QCD (NRQCD): Rigorous effective field theory: Bodwin, Braaten, Lepage (1995)  Based on factorization of soft and hard scales  (Scale hierarchy: Mv 2 , Mv << Λ QCD << M ) Could explain hadroproduction at Tevatron  M. Butenschön Recent developments in quarkonium and open flavour production calculations 1/20

J/ ψ Production with NRQCD Factorization theorem: n : Every possible Fock state, including color-octet states.  : Production rate of cc ̅ [ n ], calculated in perturbative QCD σ cc ̅ [ n ]  <O J/ ψ [ n ] > : Long distance matrix elements (LDMEs): describe cc ̅ [ n ] ➙ J/ ψ ,  universal, extracted from experiment. ≈ Scaling rules : LDMEs scale with definite power of v ( v 2 0.2): v 3 v 7 v 11 scaling n 3 S 1 1 S 0 [8] , 3 S 1 [8] , 3 P J ... [1] [8] and α s Double expansion in v  Leading term in v ( n = 3 S 1 [1] ) equals color-singlet model .  M. Butenschön Recent developments in quarkonium and open flavour production calculations 2/20

J/ ψ Production with NRQCD: Knowledge until 2005 Hadroproduction Photoproduction γγ Scattering at Tevatron: at HERA: at LEP: e + e − → e + e − J/ ψ X at LEP2 NRQCD d σ ( γ p → J/ ψ X)/dz (nb) 10 ZEUS (38 pb -1 ) ← DELPHI prelim. _ → J/ ψ +X)/dp T (nb/GeV) [ 8 ] BR(J/ ψ→µ + µ - ) d σ (pp 3 P J H1 (80 pb -1 ) (scaled) [ 1 ] 3 P J ← MRST98 fit 10 2 H1 (80 pb -1 ) high W √ s =1.8 TeV; |η| < 0.6 ← [ 8 ] 1 S 0 CTEQ5 fit ← 1 10 total ⎯ S = 197 GeV √ colour-octet 1 S 0 + 3 P J colour-octet 3 S 1 2 (pb/GeV 2 ) − 2 < y J/ ψ < 2 NRQCD LO colour-singlet colour-singlet frag. -1 10 50 < W < 180 GeV 1 p T > 1 GeV d σ /dp T 10 -2 KZSZ (LO, CS+CO) 10 -1 10 KZSZ (NLO, CS) 0.117 < α s (M Z ) < 0.121 [ 8 ] 1.3 < m c < 1.6 GeV 3 S 1 ← -3 CSM 10 -2 5 10 15 20 10 1 p T (GeV) 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 0.8 z 2 (GeV 2 ) p T CO LDMEs extracted from Born fit to Tevatron (one linear combination).  Used for predictions at HERA and LEP. No NLO calculations for color-octet (CO) contributions yet!  Universality of CO LDMEs open question.  M. Butenschön Recent developments in quarkonium and open flavour production calculations 3/20

NLO Corrections to Color Octet Contributions Petrelli, Cacciari, Greco, Maltoni, Mangano (1998):  Photo- and hadroproduction (Only 2 → 1 processes) Klasen, Kniehl, Mihaila, Steinhauser (2005):  γγ scattering at LEP (neglecting resolved photons) M.B., Kniehl (2009):  Photoproduction at HERA (neglecting resolved photons) Zhang, Ma, Wang, Chao (2009):  e + e − scattering at B factories Ma, Wang, Chao (2010):  Hadroproduction (including feed-down contributions) M.B., Kniehl (2010):  Hadroproduction (combined HERA-Tevatron fit) Necessary: A rigorous global data analysis! Only recently: Fit CO LDMEs to 194 data points from 10 experiments. Test LDME universality. [M.B., Kniehl (2011)] M. Butenschön Recent developments in quarkonium and open flavour production calculations 4/20