Diffractive Quarkonium Production at High Energies

Mairon Melo Machadoa, Maria Beatriz Gay Ducatia, Magno Valério Trindade Machadob

High Energy Phenomenology Group, GFPAE aIF – UFRGS, Porto Alegre,~Rio Grande do Sul

bUNIPAMPA, Bagé, Rio Grande do Sulmelo.machado@ufrgs.br

www.if.ufrgs.br/gfpae

VII Latin American Symposium on High Energy PhysicsIX Argentinian Symposium of Particles and Fields

San Carlos de Bariloche14-21 January 2009

• Study of inclusive and diffractive cross sections

• Pomeron plays a particular and very important role in soft process at high energy strong interaction

• Study of heavy quarkonium production mechanism

• Study the nature of Pomeron in the QCD framework

• Investigation of the effects from multiple Pomeron scattering gap survival probability factor

• Analysis using recent parametrization for Pomeron structure function

Motivations

XJppp /

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

Xppp

H1 Collaboration

• Rapidity (y) gaps no particle production

• Hadron-hadron collisions 1%

• Pomeron carries the quantum numbers of the vacuum

Diffractive Process

z

z

pE

pEy

ln2

1

pz

• DDIS contributes substantially to the cross section 10% of visible low-x events

proton momentum

• Measured also at HERA (DESY) collider (H1 and Zeus Collaboration)

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

Diffractive DIS at HERA

Inclusive DIS: Probes partonic structure of the proton

Diffractive DIS: Probes structure of the exchanged color singlet

X

X

• Q2: 4-momentum exchange

• W: p center of mass energy

• x: fraction of p momentum carried by struck quark

• xIP: fraction of p momentum carried by the Pomeron (IP)

• β: fraction of IP momentum carried by struck quark

IPX x

x

MQ

Q

ppq

Q

22

22

)'(2

22

22)'(

WQ

MQ

pq

ppqx XIP

1

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

1 INGELMAN, G.; SCHLEIN, P. E. Phys. Lett. B 152, 256 (1985)

Inclusive process

td

dxfxfdxdxd bpbapaba

)()(//

81

XJppp /

• Cross section for process in which partons of two hadrons (A and B) interact producing associated J/ψ+γ (ϒ+γ) final states

• xa and xb are the momentum fractions of nucleons carried by the partons

• fi/h is the parton distribution function (PDF) of a parton of flavor i = a,b in the hadron h = A, B

2 COOPER, F. et al PRL 93 (2004) 171801

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

Xppp

Y, P

J/ψ Diffractive cross sections

• fg/IP is the gluon distribution in the Pomeron - experimental parametrization to Pomeron structure function (H1) and fIP/p is the Pomeron flux

• PT distributions of leptons in J/ψ ( ϒ ) diffractive cross section

3 XU, J. S. AND PENG, H. A.. PRD 59 (1999) 014028

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

Y, P

• Partial decay width Γcc = 0.05084

• ec2=4/9; Mψ = 3.096 GeV; αs = gs

2 / 4π, mc = 1.5 GeV,

• To ϒ case mc mb; Mψ MY;mb = 4.5 GeV, MΥ = 9.46 GeV;

• Γbb = 0.0294

Singlet cross sections

5 KIM, C. S., et. al.Phys.Rev. D55 (1997) 5429

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

4 LANSBERG, J. P., Int. J. Mod. Phys. A 21, 3857 (2006)

Gap Survival Probability (GSP)

22

22

2

|),(|

),(|),(|||

bsAbd

sbPbsAbdS

s

• Currently a subject of intense theoretical and experimental research

• GAP region of angular phase space devoid of particles

• Survival probability fulfilling of gap by hadrons produced in interactions of remanescent particles

• A(s,b) is the amplitude (in the parameter space) of the particular process of interest at center-of-mass energy

• PS(s,b) is the probability that no inelastic interactions occur between hadrons scattered

s

6 MACHADO, M. M., GAY DUCATI, M. B. MACHADO, M. V. T. PRD 75, 11403 (2007)

8 CHEHIME, H. et al PLB 286, 392 (1992)

7 BJORKEN, J. D. PRD 47, 101 (1992)

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

• pion-loop insertions in the Pomeron trajectory

• non-exponential form of the proton-Pomeron vertex (t)

• absorptive corrections, associated with eikonalization

• values of GSP 0.15 (0.09) Tevatron (LHC)

KMR models

)(/

)(/

YJ

diff

Winc

YJ

R

• GSP KMR multiple channels

9 Khoze-Martin-Ryskin Eur. Phys. J. C. 26 229 (2002)

0.090.28

0.150.48

RJ/ψ LHC (%)RJ/ψ Tevatron (%)

1.1|| e

1.2||0.4 e

central

forward

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

RY Tevatron (%)

0.24

0.13

Results for J/ψ

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

•Color-octet is predominant to high pt

Results for J/ψ

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

-0.12R LHC (%)

0.380.37R Tevatron (%)

Ref 2This work*

without GPS

R LHC = 0.42%

R Tevatron = 0.61%

* Average of pseudo-rapidity (central and forward)

• J/ψ production is dominated by gluon-gluon fusion

Results for ϒ

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009

Contribution of ϒ is smaller than J/ψ contribution

10 Rybarska, A. et al Phys. Lett. B 660, 126 (2008)

Conclusions

• Calculation of J/ψ ( ϒ ) diffractive hadroproduction process and momentum distributions of produced photon

• Using new Pomeron diffractive parton distributions (H1 Collaboration – DESY – HERA) and theoretical estimate for GSP

• Ratio diffractive/inclusive cross section falls using GSP

• Agreement with another phenomenological prediction of 3, 4

• Application of Gap Survival Probability should be made

• Useful observable to test future extractions of Pomeron PDF’s

• J/ψ production dominates at high energies high partial decay

• Color-Octet contributions will be included in next work

VII Latin American Symposium on High Energy Physics IX Argentinian Symposium of Particles and Fields San Carlos de Bariloche 14-21 Jan 2009