Quarkonia in Media Production Charmonium Production in Media

Quarkonia in Media / Production Charmonium Production in Media International Workshop on Heavy Quarkonia 2008 December 2 – 5 2008, Nara Women University, Japan Martin zur Nedden Humboldt-Universität zu Berlin for the HERA-B Collaboration Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 1

The HERA-B Experiment Spectrometer at the HERA storage ring: proton-fixed target data taking up to march 2003 p + A X , s = 41. 6 Ge. V s oton r p e. V 920 G Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 2

Contents • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 3

Contents: Part 1 • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 4

Hadronic Production of Heavy Quarks Parton-Density-Function within the hadron partonic cross setion hadronisation: formation of hadrons with heavy quarks or quarkonia stats factorisation of the process production in hadronic interaction Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 5

Quarkonia Formation PDF Hadronization: formation of Quarkonia (J/ψ, ψ’, χc, Υ) long distance (~1/(mcv)) process: non-perturbative calculations and input from experiments needed, model dependence: CSM, COM, CEM, NRQCD qq formation: production of heavy quarks in media short distance (~1/mc) / high momentum process: perturbative calculation Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 6

Nuclear Effects for Charmonium Production J/ p μ/e+ μ/efinal state formation effects: • nuclear absorption • comover absorption • multiple scattering + energy loss initial state effects: • shadowing (nuclear PDFs) • parton energy loss • intrinsic charm HERA-B: acsess to production in media measurement of a using C and W wires: based on Glauber-model: a≠ 1 „dependence” Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 7

x. F-Dependence of Nuclear Effects J/ p μ/e+ μ/e- formation time and length: for c = 0. 5 fm x. F [fm] 0. 2 30 0 10 -0. 2 4 (x. F) = c = (x. F) boost of J/ w. r. t. nucleus Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 8

Contents: Part 2 • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 9

HERA-B Detector and Trigger Electron-Trigger Muon-Trigger W pbeam C Ti z [cm] Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 10

HERA-B Data Samples • 150 M di-lepton trigger events (e+e- / μ+μ- triggers) § ~ 300 000 J/ψ § ~ 15 000 c § ~ 5 000 ψ’ entries/(25 Me. V/c 2) μ+ μ 104 absolute cross section measurements for di-lepton triggered data need independent reference cross section measured with min. Bias events: σ(J/ψ) = (502 ± 44) nb/nucl. ~ 170 000 J/ψ ~ 3 000 ψ′ σJ/ψ ~ 44 Me. V J/ψ 103 3. 2 3. 6 + m(μ μ ) [Ge. V/c 2] Martin zur Nedden, HU Berlin 104 4. 0 ~ 120 000 J/ψ ~ 2 200 ψ′ σJ/ψ ~ 64 Me. V J/ψ 103 ψ′ 2. 8 e +e entries/(30 Me. V/c 2) • 210 M minimum bias events Three target materials: p. C, p. W and p. Ti collisions ψ′ 2. 5 Charmonium Production in Media 3. 0 3. 5 4. 0 + m(e e ) [Ge. V/c 2] QWG Meeting, Nara 2008, p. 11

Contents: Part 3 • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 12

J/ p. T Distributions HERA-B combined result HERA-B E 672/706/771/789 NA 50 Increase of <p. T 2> with A (radius of nucleus): linear dependence on the nuclear path length of the incident parton Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 13

J/ψ x. F - Distribution HERA-B combined result wx. F : width Δx. F : shift width increasing with Radius of nucleus shift increasing with Radius of nucleus • p. T distribution: • increase of <p. T 2> with radius • x. F distribution: • increasing width and shift with radius both effects compatible with initial state energy loss Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 14

Contents: Part 4 • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 15

Measurement of Nuclear Dependence nuclear dependence parameter α extracted from the ratio of carbon and tungsten J/ψ production cross sections Final result form HERA-B: result based on double wire runs only Measurement of the x. F and p. T dependence of α based on full data sample: Using the measured kinematical distributions of carbon and tungsten (normalized) (full data sample of single and double wire runs) Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 16

Nuclear Dependence Measurement: p. T Good agreement of E 866 an HERA-B measurement in the common region of p. T broadening effect as seen by E 866 confirmed Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 17

Theoretical Models for x. F Dependence Separate description and integration: • final state absorption • interaction with co-movers • energy loss (EL) • shadowing of nuclear PDFs • intrinsic charm quark components (IC) Initial state energy loss: • Gavin, Milana (GM, Phys. Rev. Lett. 68(1992)1834) • based on multiple scattering approach • elastic scatterings of quarks and gluons • Brodsky, Hoyer (BH, Phys. Lett. B 298(1993)165) • modification of GM Nuclear Parton Density Functions: Model calculation by R. Vogt: - Phys. Rev. C 61(2000)035203 - Phys. Rev. C 71(2005)054902 - Private communication Martin zur Nedden, HU Berlin • Eskola, Kolhinen, Salgado (EKS, Eur. Phys. JC 9(1999)61) • scale dependence of a proton within a nucleon via DGLAP • initial PDF from CTEQ 4 L and LO-GRV • Eskola, Paukkunen, Salgado (EPS, ar. Xiv: 0802. 0139) • improved leading order DGLAP including NLO • Hirai, Kumano, Nagai (HKN, Phys. Rev. C 70(2004)044905) • nuclear structure functions and Drell-Yan cross sections • weak anti-shadowing at negative x. F Charmonium Production in Media QWG Meeting, Nara 2008, p. 18

Theoretical Descriptions: Overview All calculations done by Ramona Vogt in 2007/2008 Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 19

Nuclear Dependence Measurement: x. F average α measurement form HERA-B: Final result form HERA-B, to be published in Eur. Phys. J Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 20

Reggeon Phenomenology Model Boreskov and Kaidalov (JEPT Lett. D 77(2003)599): predicts anti-screening effects in negative x. F region - color less state containing quarks (i. e. D-Mesons) propagates trough the nucleus - large size (consisting of D-mesons), large interaction cross section: energy loss - J/ψ projected out of energy dependent color-less state HERA-B result within uncertainties qualitatively compatible HERA-B E 866 Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 21

Contents: Part 5 • Introduction • HERA-B Detector • J/ψ: Kinematical Distributions • J/ψ: Nuclear Dependence • χc Production Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 22

χc Production HERA-B: Selection by γ Selection (Eγ) and invariant mass measurement: Relative measurement of χc to J/ψ production • making use of J/ψ production cross section from min. Bias data • disentangle χc 1 and χc 2 by double Gaussian fits: separate cross section measurements • background subtraction by mixed events • separate analysis for electrons and muons • full statistics in both channels: 15000 Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 23

χc Event Counting Separation of χc 1 and χc 2 in the ΔM spectra: • double Gaussian fit with some fixed parameters predicted by MC • free parameters are the ratio and sum of event numbers electrons muons Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 24

A-Dependence Atomic mass number dependence: • same principle as for J/ψ • no significant difference in A-dependence within the statistical limits averaged result of HERA-B: Δα = 0. 05 ± 0. 04 Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 25

Production Cross Section Ratio R( c) Final result: Rχc = (18. 8 ± 2. 8)% available statistics: of the produced J/ψ’s come from χc decays E 771 (p-Si) E 369/ 610/ 673 (p- Be) π-A HERA-B 2000 E 705 (p -Li) Martin zur Nedden, HU Berlin HERA-B ISR (p-p) 2002/3 final Charmonium Production in Media CDF (p -p) QWG Meeting, Nara 2008, p. 26

Final Results of χc Final result form HERA-B, accepted for Phys. Rev. D (ar. Xiv: 0807. 2167) Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 27

Summary HERA-B collected 300000 J/ , 15000 χc and 220 Mio minimum bias events on nuclear targets (mainly carbon and tungsten) Final Results on charmonium production: • J/ : inclusive production cross section • J/ : x. F and p. T distributions in a new negative x. F range J/ : nuclear dependence: tendency of enhancement in at x. F <0 • c : production ratio, disentanglement of χc 1 and χc 2 Final results on kinematics of J/ production, nuclear dependence of J/ψ and c production are final and published (during 2008) Martin zur Nedden, HU Berlin Charmonium Production in Media QWG Meeting, Nara 2008, p. 28