diffractive quarkonium production at high energies
DESCRIPTION
Diffractive Quarkonium Production at High Energies. Mairon Melo Machado a , Maria Beatriz Gay Ducati a , Magno Valério Trindade Machado b High Energy Phenomenology Group, GFPAE a IF – UFRGS, Porto Alegre,~Rio Grande do Sul b UNIPAMPA, Bagé, Rio Grande do Sul [email protected] - PowerPoint PPT PresentationTRANSCRIPT
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