Diffractive Quarkonium Production at High Energies
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Transcript of Diffractive Quarkonium Production at High Energies
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 [email protected]
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