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Diffractive J/ ψ + γ Production at Collider Energies

Diffractive J/ ψ + γ Production at Collider Energies. Mairon Melo Machado High Energy Phenomenology Group, GFPAE IF – UFRGS, Porto Alegre melo.machado@ufrgs.br www.if.ufrgs.br/gfpae. Motivations. Study of inclusive and diffractive cross section

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Diffractive J/ ψ + γ Production at Collider Energies

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  1. Diffractive J/ψ+γ Production at Collider Energies Mairon Melo Machado High Energy Phenomenology Group, GFPAE IF – UFRGS, Porto Alegre melo.machado@ufrgs.br www.if.ufrgs.br/gfpae

  2. Motivations • Study of inclusive and diffractive cross section • Study of the color-octect mechanism based on the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) • Study of Pomeron trajectory phenomenology describes the diffractive scattering • Study of hard diffractive process Ingelman-Schlein model • Investigation of the effects from multiple Pomeron scattering gap survival probability factor • Analysis using recent parametrization for Pomeron structure function H1 Collaboration Mairon Machado – CBPF – july 2008

  3. Diffractive Process • Rapidity (y) gaps no particle production • Hadron-hadron collisions 1% • Pomeron exchange of vacuum quantum numbers pz proton momentum • Measured also at HERA (DESY) collider (H1 and Zeus Collaboration) • DDIS contributes substantially to the cross section  10% of visible low-x events Mairon Machado – CBPF – july 2008

  4. DiffractiveDIS at HERA 1COVOLAN, R. J. M., SOARES, M. PRD 60, 054005 (1998) • 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 Inclusive DIS: Probes partonic structure of the proton X Diffractive DIS: Probes structure of the exchanged color singlet X Ingelman-Schlein model Mairon Machado – CBPF – july 2008

  5. Inclusive process • Cross section for a process in which partons of two hadrons (A and B) interact for associated J/ψ+γproduction • xa and xb are the momentum fraction 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 2COOPER, F. et al PRL 93 (2004) 171801 Mairon Machado – CBPF – july 2008

  6. J/ψ Diffractive cross sections 3XU, J. S. AND PENG, H. A.. PRD 59 (1999) 014028 • PT distributions of leptons in J/ψ diffractive cross section • fg/IP is the gluon distribution in the Pomeron - experimental parametrization to Pomeron structure function (H1) and fIP/p is the Pomeron flux • Inclusive cross section xIP = 1 Mairon Machado – CBPF – july 2008

  7. Singlet and octet cross sections • Partial decay width  = 0.05084 • ec2=2/3;Mψ = 3.096 GeV; αs = gs2 / 4π 4CHO, P., LEIBOVICH, A. PRD 53, 6203 (1995) Mairon Machado – CBPF – july 2008

  8. Gap Survival Probability (GSP) 5MACHADO, M. M., GAY DUCATI, M. B. MACHADO, M. V. T. PRD 75, 11403 (2007) • Currently a subject of intense theoretical and experimental interest • 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 occurs between hadrons scattered Mairon Machado – ENFPC - 27/09/2007

  9. KMR and GLM models 6Khoze-Martin-Ryskin Eur. Phys. J. C. 26 229 (2002) • GSP KMR multiple channels • pion-loop insertions in the Pomeron trajectory • non-exponential form of the proton-Pomeron vertex  (t) • absorptive corrections, associated with eikonalization • Average to diffractive ratio predicton for LHC (central) = 0.15 % • Average to diffractive ratio predicton for LHC (forward) = 0.09 % • Average to diffractive ratio predicton for Tevatron (central) = 0.48 % • Average to diffractive ratio predicton for Tevatron (forward) = 0.28 % Mairon Machado – CBPF – july 2008

  10. Results LHC Tevatron inctot difftot • Black upper lines (inclusive singlet) red dashed bottom lines (diffractive singlet) • Octet contibution domains (near of total value) • Average to diffractive ratio predicton for LHC (central + forward) = 0.12 % • Average to diffractive ratio predicton for Tevatron (central) = 0.37 % • Average without GPS - (LHC = 0.42%) and (Tevatron = 0.61%) Mairon Machado – CBPF – july 2008

  11. Conclusions • Analysis of J/ψdiffractive hadroproduction process and rapidity distributions of produced leptons • Using new Pomeron diffractive parton distributions (H1 Collaboration – DESY – HERA) and theoretical estimate for gap survival factor • Agreement with another theoretical prediction • Improvement of data description using gap survival probability • Useful place to test future extractions of Pomeron PDF’s • Verification of the factorizatin formalism of NRQCD • Application of Gap Survival Probability should be made Mairon Machado – CBPF – july 2008

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