Ψ(2S)/J/ψ ratio at HERA

Transcription

1 Blois Workshop 017 Prague, June 6 th -30 th 017 Ψ(S)/J/ψ ratio at HERA Marta Ruspa Univ. Piemonte Orientale & INFN-Torino, Italy

2 Inclusive and exclusive diffraction Inclusive Exclusive VM= ρ,ω,ϕ,j/ψ,ψ,ϒ,γ GAP GAP p e e p à e X p e p à e J/ψ p J/ψ à μ + μ -

3 Inclusive and exclusive diffraction Inclusive Exclusive VM= ρ,ω,ϕ,j/ψ,ψ,ϒ,γ GAP Q = virtuality of photon = = (4-momentum exchanged at e vertex) W = invariant mass of γ * -p system t = (4-momentum exchanged at p vertex) typically: t <1 GeV Single diffraction/elastic: N=proton Double diffraction: proton-dissociative system N M X = invariant mass of γ * -IP system x IP = fraction of proton s momentum carried by IP ß = Bjorken s variable for the IP = fraction of IP momentum carried by struck quark = x/x IP - Scattered electron - VM decay products and nothing else in the central detector - Proton undetected 3

4 Motivation Ψ(S) wave function different from J/ψ wave function Ratio sensitive to radial wave function of charmonium pqcd models predict R 0.17 (photoproduction) and rise of R with Q 4

5 Samples Ψ(S) à J/ψ π + π - J/ψ à µ + µ - Ψ(S) à µ + µ - J/ψ à µ + µ - Data sample: all ZEUS data ( ) integrated luminosity 468 pb Monte Carlo samples: - signal DIFFVM exclusive VM production - background GRAPE Bethe-Heitler elastic and proton dissociative dimuon production 5

6 Event selection Scattered electron detected 30 W GeV Q 80 GeV t 1 GeV Scattered proton undetected Two reconstructed tracks identified as muons and nothing else in the detector above noise level Ψ(S) à µ + µ - J/ψ à µ + µ - Two reconctructed tracks identified as muons, two pion tracks and nothing else in the detector above noise level Ψ(S) à J/ψ π + π -- J/ψ à µ + µ - à Proton dissociative events removed above masses ~ M N 4 GeV Assuming cross section ratio does not vary with M N, results not affected by proton dissociation background 6

7 Entries 4 Signal extraction ZEUS J/!(1S) Ψ(S) à µ + µ - J/ψ à µ + µ - 3!(S) Background fit M!! (GeV) 7

8 Entries 4 Signal extraction ZEUS J/!(1S) Ψ(S) à µ + µ - J/ψ à µ + µ - 3!(S) Background fit M!! (GeV) Dimuon background fit to straight line for < M μ+ µ- <.6 GeV and 4.05 < M μ+ µ- < 5 GeV Function used for the fit and M μ+ µ- window varied as systematic checks 8

9 Entries 4 Signal extraction ZEUS J/!(1S) Ψ(S) à µ + µ - J/ψ à µ + µ - 3!(S) Number of events above background in the ranges 3.59 < M µ+ µ- < 3.79 GeV à N ψ(s) 3.0 < M µ+ µ- < 3.17 GeV à N J/ψ Background fit M!! (GeV) Dimuon background fit to straight line for < M μ+ µ- <.6 GeV and 4.05 < M μ+ µ- < 5 GeV Function used for the fit and M μ+ µ- window varied as systematic checks 9

10 Signal extraction Ψ(S) à J/ψ π + π - J/ψ à µ + µ -! M (GeV) ZEU M!! (GeV) ΔM = M μμππ - M μμ

11 Signal extraction Ψ(S) à J/ψ π + π - J/ψ à µ + µ -! M (GeV) ZEUS Entries M!! (GeV) ! M (GeV) ΔM = M μμππ - M ΔM = M μμ μμππ - M μμ Entries M!!"" (GeV) 11

12 Signal extraction Ψ(S) à J/ψ π + π - J/ψ à µ + µ -! M (GeV) ZEUS Entries M!! (GeV) ! M (GeV) ΔM = M μμππ - M μμ No background (upper limit of 3 events at 90% C.L. estimated) 0.5 < ΔM < 0.7 GeV à N ψ(s) Entries M!!"" (GeV) Cut applied above: 3.0 < M µµ < 3.17 GeV 1

13 Measured ratios = combination of and BR[ψ(S) à J/ψ ππ] = (33.6±0.4)% BR[ψ(S) à µµ] = (7.7±0.8)x -3 % BR[J/ψ à µµ] = (5.93±0.06)% 13

14 Measured ratios 30 W GeV Q 80 GeV t 1 GeV 14

15 R comb R comb Ratios vs Q, W and t ZEUS ZEUS t (GeV ) R comb ZEUS W (GeV) à Independent of W and t à Increasing with Q Q (GeV ) 15

16 Comparison with models and with H1 ZEUS R HIKT: GBW-BT HIKT: GBW-LOG AR: b-cgc AR: IP-Sat KMW: $ FFJS KNNPZZ LM KMW: $ = 0 = " R =! " (S) J/!(1S) H1 7 pb H1 #p: 6.3 pb Q (GeV ) HIKT, Hüfner et al.: dipole model, dipole-proton constrained by inclusive DIS data AR, Armesto and Rezaeian: impact parameter dependent CGC and IP-Sat model KMW,Kowalski Motyka Watt: QCD description and universality of quarkonia production FFJS, Fazio et al.: two component Pomeron model KNNPZZ, Nemchik et al.: dipole cross section derived from BFKL generalised eq. LM, Lappi and Mäntysaari : dipole picture in IP-Sat model 16

17 HIKT calculation [J. Hüfner et al., Phys. Rev. D 6, 0940 (000)] Two parameterization of the ccbar-dipole cross section (GBW and KST) Four phenomenological potentials of the wave functions: - BT, LOG with m c 1.5 GeV - COR and POW with m c 1.8 GeV à BT predictions larger than the data 17

18 Comparison with models and with H1 ZEUS R HIKT: GBW-BT HIKT: GBW-LOG AR: b-cgc AR: IP-Sat KMW: $ FFJS KNNPZZ LM KMW: $ = 0 = " R =! " (S) J/!(1S) H1 7 pb H1 #p: 6.3 pb Q (GeV ) HIKT, Hüfner et al.: dipole model, dipole-proton constrained by inclusive DIS data AR, Armesto and Rezaeian: impact parameter dependent CGC and IP-Sat model KMW,Kowalski Motyka Watt: QCD description and universality of quarkonia production FFJS, Fazio et al.: two component Pomeron model KNNPZZ, Nemchik et al.: dipole cross section derived from BFKL generalised eq. LM, Lappi and Mäntysaari : dipole picture in IP-Sat model 18

19 AR calculation [N. Armesto and A. H. Reazeian, Phys. Rev. D 90, (014)] Impact-parameter-dependent Color Glass Condensate model (b-cgc) or Saturation model (IP-Sat) for the calculation of the ccbar-dipole cross section àip-sat prediction about 30% lower and gives a better description of the data 19

20 Comparison with models and with H1 ZEUS R HIKT: GBW-BT HIKT: GBW-LOG AR: b-cgc AR: IP-Sat KMW: $ FFJS KNNPZZ LM KMW: $ = 0 = " R =! " (S) J/!(1S) H1 7 pb H1 #p: 6.3 pb Q (GeV ) HIKT, Hüfner et al.: dipole model, dipole-proton constrained by inclusive DIS data AR, Armesto and Rezaeian: impact parameter dependent CGC and IP-Sat model KMW,Kowalski Motyka Watt: QCD description and universality of quarkonia production FFJS, Fazio et al.: two component Pomeron model KNNPZZ, Nemchik et al.: dipole cross section derived from BFKL generalised eq. LM, Lappi and Mäntysaari : dipole picture in IP-Sat model 0

21 KMW calculation [H. Kowalski et al., Phys. Rev. D 74, (006)] Assumes universality of production of vector quarkonia states. Parameter δ depends on the choice of the charmonium wave function à δ = 0 provides a better description of the data 1

22 Comparison with models and with H1 ZEUS R HIKT: GBW-BT HIKT: GBW-LOG AR: b-cgc AR: IP-Sat KMW: $ FFJS KNNPZZ LM KMW: $ = 0 = " R =! " (S) J/!(1S) H1 7 pb H1 #p: 6.3 pb Q (GeV ) HIKT, Hüfner et al.: dipole model, dipole-proton constrained by inclusive DIS data AR, Armesto and Rezaeian: impact parameter dependent CGC and IP-Sat model KMW,Kowalski Motyka Watt: QCD description and universality of quarkonia production FFJS, Fazio et al.: two component Pomeron model KNNPZZ, Nemchik et al.: dipole cross section derived from BFKL generalised eq. LM, Lappi and Mäntysaari : dipole picture in IP-Sat model

23 Summary J/ψ(S)/J/ψ measured by ZEUS with full HERA statistics J/ψ(S)/J/ψ rises with Q and is constant in W and t Discrimination of different models possible DESY , Nucl. Phys. B 909 (016) 934 3

24 Backup 4

25 FFJS calculation [S. Fazio et al., Phys. Rev. D 90, (014)] Two-component Pomeron model 5

26 KNNPZZ calculation [B. Kopeliovich et al., Phys. Rev D 44, 3466 (1991), B. Kopeliovich et Al., Phys. Lett. B 34, 469 (1994) J. Nemchik et al., Phys. Lett. B 341, 8 (1994) J. Nemchik et al., J. Exp. Theor. Phys. 86, 54 (1998)] Generalized BFKL equation for ccba- dipole cross section 6

27 LM calculation [T. Lappi and H. Mäntysaari, Phys. Rev. C 83, 0650 (011), T. Lappi and H. Mäntysaari, PoS (DIS014), 069 (014)] BFKL equation + IP-Sat model 7

28 Data/MC Entries J/ψ à µ + µ - ZEUS Q (GeV ) Entries W (GeV) Entries J/"(1S)!!! DIFFVM + BH BH t (GeV ) Monte Carlo reweigthed in t, Q and angular distributions 8

29 Data/MC Entries Ψ(S) à µ + µ - ZEUS Entries Q (GeV ) W (GeV) Entries "(S)!!! DIFFVM + BH BH t (GeV ) Monte Carlo reweigthed in t, Q and angular distributions 9

30 Data/MC Entries Ψ(S) à J/ψ π + π - J/ψ à µ + µ - ZEUS Entries Q (GeV ) W (GeV) Entries "(S) # J/"(1S)! DIFFVM -! t (GeV ) Monte Carlo reweigthed in t, Q and angular distributions 30

31 Comparison with H1 earlier measurement à Much larger luminosity in ZEUS measurement (HERA I + HERA II) 31