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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 1 Estimating the diffractive heavy quark production in heavy ion collisions at the LHC* Mairon Melo Machado GFPAE – IF – UFRGS www.if.ufrgs.br/gfpae melo.machado@ufrgs.br

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 2 Outlook Motivation Diffractive Physics Hadroproduction of heavy quarks at LO Hadroproduction of heavy quarks at NLO Coherent and incoherent heavy quark production Pomeron Structure Function Multiple Pomeron Scattering Results Conclusions

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 3 Cross section for heavy quark production allows to probe the gluon densities Pomeron with substructure Ingelman-Schlein Ingelman-Schlein predictions Absorptive corrections multiple Pomeron Scattering Gap survival probability to AA single diffractive collisions Coherent and incoherent diffraction is a powerful tool for studying the low-x processes (gluon saturation) HQ are important signals of possible new physics Motivation 1, 2 1 M. B. Gay Ducati, M. M. Machado, M. V. T. Machado, PRD 75, 114013 (2007) 2 M. B. Gay Ducati, M. M. Machado, M. V. T. Machado, arXiv:0908.0507 [hep-ph] (2009) signal background

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 4 Introduction Diffractive processes rapidity gap Exchange of a Pomeron with vacuum quantum numbers Pomeron 3 not completely known Parton content in the Pomeron DPDFs Diffractive distributions of singlet quarks and gluons in the Pomeron Coherent (small-x dynamics) and incoherent cases (color field fluctuations) 3 P. D. Collins, An Introduction to Regge Theory and High Energy Physics (1977) Diffractive structure function Gap Survival Probability (GSP)

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 5 Diffractive events Single diffraction in hadronic collisions One of the colliding hadrons emits Pomeron Partons in the the Pomeron interact with partons from the another hadron Absence of hadronic energy in angular regions Φ of the final state phase space Rapidity gaps Ingelman-Schlein Model 4 G. Ingelman and P. Schlein, Phys. Lett. 152B (1985) 256.

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 6 o Focus on the following single diffractive processes Heavy quark hadroproduction o Diffractive ratios as a function of energy center-mass E CM o Diagrams contributing to the lowest order cross section 5 5 M. L. Mangano et al, Nucl. Phys. B 373, 295 (1992)

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 7 LO hadroproduction Total cross section Partonical cross section are the parton distributions inner the hadron i=1 and j=2 5 5 M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295 factorisation (renormalization) scale

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 8 6 M. L. Mangano arXiv:hep-ph/9711337v1 (1997) Partonic cross section N = 3 (4) to charm (bottom) m is the heavy quark mass is the coupling constant 6 Dimension of the SU(N) gauge group (number of gluons) p 1,2 are the parton momenta

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 9 NLO Production 5 5 M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295 Running of the coupling constant n 1f = 3 (4) charm (bottom)

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 10 NLO functions 7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607 a0a0 0.108068 a1a1 -0.114997 a2a2 0.0428630 a3a3 0.131429 a4a4 0.0438768 a5a5 -0.0760996 a6a6 -0.165878 a7a7 -0.158246 Using a physical motivation fit to the numerically integrated result 7 Error of 1%

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 11 NLO Production 7 Auxiliary functions 7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 12 Diffractive cross section Pomeron flux factor Pomeron Structure Function (H1) 6 6 H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 KKMR model = 0.06 at LHC single diffractive events 7 7 V. A. Khoze, A. D. Martin, M. G. Ryskin, Eur. Phys. J. C18, 167 (2000)

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 H1 Gluon distribution In this work we use FIT A. Similar results with FIT B 6 H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 6

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 14 Incoherent diffractive is a process where A* denotes the excited nucleus that subsequently decays into a system of colorless hadrons 9 Diffractive incoherent ratio Coherent diffractive is a process where Stronger dependence on energy and atomic number Diffractive Nuclear heavy quark production 8 N. M. Agababyan et al Phys. Atom. Nucl. 62, 1572 (1999) 9 K. Tuchin, arXiv:0812.1519v2 [hep-ph] (2009) single diffraction 8

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 15 qq vs. gg Inclusive cross section and diffractive cross section Charm-anticharm hadroproduction Contribution of qq anihillation at high energies not important Diffractive cross section without GSP M c = 1.5 GeV Inclusive quarks/gluons Inclusive gluons Diffractive

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 16 Diffractive comparison Diffractive cross sections to bottom-antibottom hadroproduction Relevant contribution of GSP value in the total diffractive cross section = 0.06 M b = 4.7 GeV Inclusive Diffractive wt/GSP Diffractive wh/GSP

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 17 Comparison LO and NLO Predictions for inclusive cross sections in pp collisions (LHC) NLO cross section is 1.5 higher than LO cross section at high energies

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 18 Cross sections in NLO to inclusive nuclear cross section A Ca = 40 A Pb = 208 Results for heavy quark production Cross sections in NLO for heavy quarks hadroproduction GSP value decreases the diffractive rate = 0.06

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 19 Incoherent results 11 E. Levin; J. Miller arXiv:0801.3593v1 [hep-ph] (2008) There are not values of to single diffraction in AA collisions Estimatives to Higgs central production 11 ~ 1 x 10 -4 Values of diffractive cross section in a region possible to be verified

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 20 Coherent results Predictions to diffractive cross section in a region possible to be verified Diffractive cross section without GSP is consistent with the literature Very small single diffractive ratio

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Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009 21 Conclusions Theoretical predictions for inclusive and single diffractive heavy quarks production at LHC energies in pp and AA collisions Estimates for cross sections as a function of energy center mass E CM Diffractive ratio is computed using hard diffractive factorization and absorptive corrections (NLO) There are not predictions to in AA collisions Important contribution of the absolute value of absorptive corrections Diffractive cross section for AA collisions in a region that is possible to be verified Evaluation of the gap survival probability for single diffraction in AA collisions

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