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Charmonium production: J/ , ’,  c J/  production cross section Differential distributions, polarisation Nuclear dependence Production ratios ’/ J/ ,  c / J/  Hidden and open beauty production: ( ), (ns) production cross section  production cross section.

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heavy flavor production at hera b in 920 gev proton nucleus interactions

Charmonium production: J/, ’, c

    • J/ production cross section
    • Differential distributions, polarisation
    • Nuclear dependence
    • Production ratios ’/ J/, c/ J/
  • Hidden and open beauty production: ( ), (ns)
    • production cross section
    •  production cross section
Heavy Flavor Production at HERA-B in 920 GeV Proton-Nucleus Interactions

Hermann Kolanoski

Humboldt Universität zu Berlin and DESY Zeuthen

for the HERA-B Collaboration

Brookhaven, 4.April 2006

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

the hera b experiment
The HERA-B Experiment

920 GeV protons

p + A  X @ spN = 41.6 GeV

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

models of heavy flavour production in hadronic interactions
Models of Heavy Flavour Production in Hadronic Interactions

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

factorisation
Factorisation

PDF

  • hadronization
  • Long distance (~1/(mcv)) process
  • non-perturbative calculations +

input from experiments

qq formation

short distance (~1/mc) / high momentum process

 perturbative calculations

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

perturbative generation color singlet or octet
Perturbative Generation:Color Singlet or Octet?

JPC

0-+

0++

2++

JPC

1--

1--

1++

  • Color Singlet Model (CSM): pair is produced as a color singlet

with quantum numbers of the final charmonium state.

 absolute predictions, but: not supported by experiment

  • Color Evaporation Model (CEM): pair production is the same

for all charmonium states; quantum numbers arranged by

“evaporation” of soft gluons.

 predicts the same production dynamics of all states;

cross section differences only from phase space and wave functions.

  • Non-Relativistic QCD Model (NRQCD): more rigorous (?) QCD treatment

(singlet + octet + non-perturbative ME)

 free parameters adjusted to data,

predictions tested in different models, energies, final states, …

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

study of charmonium suppression

J/

e+

p

e-

Study of Charmonium Suppression
  • State formation effects:
  • nuclear absorption
  • comover absorption
  • multiple scattering + energy loss
  • Initial state effects:
  • shadowing (nuclear PDFs)
  • parton energy loss
  • intrinsic charm

Measurement of a for 2 wire materials:

a ≠ 1 “suppression”

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

x f dependence of nuclear suppression

J/

e+

formation time and length:

(xF) =   c 

p

e-

 = (xF)boost of J/ w.r.t. nucleus

xF-Dependence of Nuclear Suppression

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

the hera b detector trigger and data samples
The HERA-B Detector, Trigger and Data Samples

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

the hera b detector

184W

p-beam

12C

48Ti

z [cm]

The HERA-B Detector

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

the dilepton trigger

5 MHz

Pretriggers: ECAL cluster or muon hit coincidence as trigger seed (custom hardware)

3 MHz

First Level Trigger (FLT): Track trigger in hardware using tracking detectors, seeding by pretriggers

20 kHz

100 Hz

Second Level Trigger (SLT):FLT tracking confirmed, extrapolation to vertex detector, vertex fit (PC farm)

Fourth Level Trigger (4LT):online reconstruction (and filtering) on PC farm

100 Hz

The Dilepton Trigger

HERA-B detector: data is read out and buffered for 12s(proton bunches cross every 96 ns, 0.5 interactions/BX)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

data samples

J/ collection

Data samples

Data taking has finished in 2003;

analysis is close to be finalized

Data samples:

  • 150 M di-lepton trigger events (300 000 J/ψ)
  • 210 M minimum bias events
  • 35 M hard photon trigger events

10 more was planned!

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

topics of di lepton trigger analysis

J/

e+ e-

+ -

(2s)

c

bb

(1-3s)

Topics of di-lepton trigger analysis

1) pt distribution

xF distribution

A-dependence

polarisation

2) (2s) production ratio

3) c/J/production ratio

4) bb cross section

5)  production

6) (D0  )

Most results are final or close to final

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j production di lepton triggered
J/ Production: di-lepton triggered

J/→ 

~ 177,000 σ= 44 MeV/c2

J/→ e+e-

~ 108,000 J/

σ= 64 MeV/c2

J/

~ 3000 (2S)

/

(2S)

~ 1600 (2S)

  • absolute cross sections from di-lepton triggered data

need reference cross section

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

interlude j cross section from minimum bias data
Interlude:J/cross sectionfrom Minimum Bias data

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j cross section from minimum bias data
J/cross sectionfrom Minimum Bias data

Important for cross section normalisationof di-lepton triggered data

+-

e+e-

  • low statistics
  • but: efficiency and luminosity well understood
  •  systematic uncertainties small (usually dominant)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j y minb a dependence and results

C

Ti

Results:

W

J/y (MinB): A-Dependence and Results

α = 0.96  0.01

(fixed to E866)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j y minb comparison with other results
J/y (MinB): Comparison with other Results

Result from both decay channels:

HERA-B ~2X higherthan E771/789

in this energy region (!?)

Mesurements are in general

not very consistent

with each other

How to get a reference cross section ???

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

nrqcd based evaluation of j y and y cross sections
NRQCD Based Evaluation of J/y and y’ Cross Sections
  • Towards a ‚reference cross section‘:
    • include all measurements (J/y, y’,c)
    • combine by ‚QCD-inspired‘ fit

F. Maltoni et al. (= HERA-B Collaborators),

‚Analysis of charmonium production

at fixed-target experiments in the NRQCD approach‘,

hep-ph/0601203

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

qcd based evaluation of j y and y cross sections fit results

Fit results at HERA-B energy

s = 41.6 GeV:

QCD Based Evaluation of J/y and y’ Cross Sections:Fit Results

F. Maltoni et al., ‚Analysis of charmonium production at fixed-target experiments in the NRQCD approach‘, hep-ph/0601203

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

back to two lepton triggered data charmonium production
… back to two-lepton triggered data:Charmonium Production

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j differential cross sections preliminary
J/ differential cross sections(preliminary)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j p t distributions nucl dep

(×10-4)

E789 (Au)

(×10-3)

(×10-2)

(×10-1)

HERA-B (W)

W

Au

Be

C

Si

Ti

[GeV-2]

<pT>[GeV/c]

(×10)

E771 (Si)

HERA-B (Ti)

HERA-B (C)

E672/E706 (Be)

A

pT[GeV]

J/ pT distributions (nucl.dep.)

standard fit:

preliminary data (di-electron only), compared with p-A results at similar energy (√s = 38.8 GeV)

<pT> grows logarithmically with A:

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j p t distributions nucl dep1
J/ pT distributions (nucl.dep.)

Cronin effect

<pT> grows with s:

<pT>  0.8 + 0.01·s

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j y x f distribution
J/y xF distribution

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j a dependence x f
J/ψ: A-dependence (xF)

First measurement at xF < -0.1:

constant small suppression

preliminary result:

R.Vogt, [Nucl.Phys.A700(2002)539.]

 = 0.969 ± 0.003stat± 0.021sys

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

j polarisation
J/ Polarisation

usually only  is given;

polarisation depends

on reference system

(polarisation axis in

rest frame of J/) :

E771, E672/E706

(Gottfried-Jackson)

E866

(Collins-Soper)

hadron CM

(target system)

CDF

+ (hadron CM)

tan  = pT/MJ/  only for pT  0 are the systems different

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

preliminary polarisation results

±

±

±

±

±

±

HCM

GJ

CS

±

±

±

Preliminary Polarisation Results

HCM

GJ

CS

large

polarisation

at pT=0

 max. in CS frame  „natural“ system ?

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

y j production ratio
y’/J/ production ratio

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

y production x f distributions
y’ production: xF distributions

Tungsten

Carbon

J/→

J/→

, ee

A-dependence:(xF) =‘- 

CEM for color-1 nuclear absorption

NRQCD for color-1 & -8 nuclear absorption

fit with const: (E866)=-0.026±0.005

All consistent with no xF dependence.

We use average of E866 and NA50:

(E866, NA50)=-0.030±0.004

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

y production x f distributions1
y’ production: xF distributions

all targets included,

corrected for nuclear effects with

(E866, NA50)

NRQCD

CEM

Data are consistent

with both models

(and with no xF dependence)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

y production p t distributions
y’ production: pT distributions

Carbon

Tungsten

J/→

J/→

  • tendency for a wider pT distribution of ′

(increasing with A?)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

y production polarisation
y’ production: polarisation

Result:

compatible with no polarisation difference

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

production ratio y j y
Production ratio y’/ J/y

A

√s

CEM

NRQCD

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

c j production ratio
c /J/ production ratio

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

c production

preliminary

2002/2003 data

(di-muon sample)

background: mixed events

after background subtraction

entries/(10 MeV/c2)

m(μ+μ-γ)-m(μ+μ-) [GeV/c2]

c production

selection:

  • measurement:
  • fraction of J/ψ’s from χc:
  • kinematical distributions

from the 2000 data, with

370 ± 74 χc’s(μ+μ- + e+e-):

R(c) = 0.32 ± 0.06 ± 0.04

[Phys. Lett. B 561, 61 (2003)]

new data: 40bigger χcstatistics

(the largest ever analyzed)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

c1 c2 separation

preliminary

(a fraction of the

di-muon sample)

ET(γ) > 0.4 GeV

background: mixed events

entries/(1 MeV/c2)

c2

c1

after background subtraction

m(μ+μ-γ)-m(μ+μ-) [GeV/c2]

c1 - c2 separation

further step (?):

separate different states by varying the selection cuts

measure the

c2/c1production ratio

interesting constraints

on the QCD models

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

slide37

E771 (p-Si)

E369/ 610/ 673 (p-Be)

π-A

ISR (p-p)

2000

expected final precision

2002/3 prelim.

E705 (p-Li)

CDF (p-p)

HERA-B

R(c)

preliminary evaluation (2002/2003 data):

(21 ± 5)% of the produced J/ψ’s come from χc decays

based on 1300 χc’s

reconstructed in the di-muon channel

(less than 10% of the total statistics)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

beauty production open hidden beauty
Beauty production:open& hiddenbeauty

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

open and hidden beauty production

RD: =5314 m

Open and Hidden Beauty Production

Detached vertex analysis

open

pA bb + X

J/ + X’

e+ e- , +-

Cross sections normalised to prompt J/

using the ‘NRQCD supported’ evaluation:

(pN  J/ X) = (502  44) nb/nucleon

(with  = 0.96  0.01)

hidden

pA  (ns) + X

e+ e- , +-

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

open beauty production
Open beauty production

Analysis of 2002/03 data:

  • e+e- and +- triggered data
  • C, W, Ti targets (1 for bb)
  • J/ acceptance: -0.35 < xF < 0.15

(90% of bb cross section)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

b flavour confirmation
B Flavour Confirmation

t = 1.39 ± 0.19 ps

Long lived candidates around J/ψ mass

B lifetime compatible with expected 1.54 ps (PDG)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

open beauty production r

-0.35 < xF< 0.1

0 < pT < 6 GeV

Open beauty production: R

Relative to prompt J/

to minimize uncertainties

from efficiencies, luminosity …

2000 data

Combined result of 2000 and 2002/3 data:

R = 0.032  0.005stat  0.004sys

(syst. error mainly from B(bJ/))

PHYSICAL REVIEW D 73, 052005 (2006)

2000 data: Eur. Phys.J. C26 (2003) 345

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

production cross section
Production Cross section

Normalizing to J/from Maltoni et al.:

(pN  J/ X) = (502  44) nb/N

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

hidden beauty production 1s 2s 3s
Hidden beauty production(1S) + (2S) + (3S)

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

hidden beauty 1s 2s 3s
Hidden beauty: (1S) + (2S) + (3S)

30.8±7.4

75±14

DY

DY

comb

comb

Fit: A· ((1S) + (2S) + (3S)) + B· Drell-Yan + Combinatorial

(1S) : (2S) : (3S)

ratio fixed to E605 results

shape from MC

from like-sign pairs

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

hidden beauty production results

Fit “modified Craigie”:

 NLO CEM

data are compatible with =1

Hidden beauty production: Results

Normalized to J/

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404

summary
Summary
  • HERA-B collected 300k J/ and 200M min.bias events on various nuclei
  • Results on charmonium production (partly preliminary):
    • J/  cross section (and QCD evaluation)
    • J/ : xF and pT distributions in a new negative xF range
    • J/ A dependence demonstrate a flat behavior in this region
    • Fraction of c and (2S) yields relative to J/
    • Open and hidden beauty cross sections
  • Final results on J/ , c and (2S) in 2006

The end of HERA-B is close

Hermann Kolanoski HU Berlin - HERA-B Results - BNL060404