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. 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 Motivations Mairon Machado – CBPF – july 2008

3. Rapidity (y) gaps no particle production Hadron-hadron collisions 1% Pomeron exchange of vacuum quantum numbers Diffractive Process pzpz 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) Mairon Machado – CBPF – july 2008

4. Diffractive DIS at HERA Inclusive DIS: Probes partonic structure of the proton Diffractive DIS: Probes structure of the exchanged color singlet X X Q 2 : 4-momentum exchange W:  p center of mass energy x: fraction of p momentum carried by struck quark x IP : fraction of p momentum carried by the Pomeron (IP) β: fraction of IP momentum carried by struck quark Ingelman-Schlein model Mairon Machado – CBPF – july 2008 1 COVOLAN, R. J. M., SOARES, M. PRD 60, 054005 (1998)

5. Inclusive process Cross section for a process in which partons of two hadrons (A and B) interact for assoc iated J/ψ+γ production x a and x b are the momentum fraction of nucleons carried by the partons f i/h is the parton distribution function (PDF) of a parton of flavor i = a,b in the hadron h = A, B Mairon Machado – CBPF – july 2008 2 COOPER, F. et al PRL 93 (2004) 171801

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

7. Partial decay width  = 0.05084 e c 2 =2/3; M ψ = 3.096 GeV; α s = g s 2 / 4π Singlet and octet cross sections Mairon Machado – CBPF – july 2008 4 CHO, P., LEIBOVICH, A. PRD 53, 6203 (1995)

8. Gap Survival Probability (GSP) 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 P S (s,b) is the probability that no inelastic interactions occurs between hadrons scattered Mairon Machado – ENFPC - 27/09/2007 5 MACHADO, M. M., GAY DUCATI, M. B. MACHADO, M. V. T. PRD 75, 11403 (2007)

9. KMR and GLM models 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 Mairon Machado – CBPF – july 2008 6 Khoze-Martin-Ryskin Eur. Phys. J. C. 26 229 (2002) 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 %

10. Results Mairon Machado – CBPF – july 2008 LHC diff tot 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%) Tevatron Black upper lines (inclusive singlet) red dashed bottom lines (diffractive singlet) Octet contibution domains (near of total value) inc tot

11. Conclusions Analysis of J/ψ diffractive 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