1. Seminários GFPAE – 02/2009 1 Diffractive heavy quark production at the LHC Mairon Melo Machado melo.machado@ufrgs.br

2. Seminários GFPAE – 02/2009 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

3. Seminários GFPAE – 02/2009 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 signal background

4. Seminários GFPAE – 02/2009 4 Introduction  Diffractive processes rapidity gap  Exchange of a Pomeron with vacuum quantum numbers  Pomeron 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) Diffractive structure function Gap Survival Probability (GSP)

5. Seminários GFPAE – 02/2009 5  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 Diffractive events Rapidity gaps Ingelman-Schlein Model

6. Seminários GFPAE – 02/2009 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

7. Seminários GFPAE – 02/2009 7 LO hadroproduction Total cross section Partonical cross section are the parton distributions inner the hadron i=1 and j=2 factorisation (renormalisation) scale

8. Seminários GFPAE – 02/2009 8 Partonic cross section N = 3 (4) to charm (bottom) m is the heavy quark mass is the coupling constant Dimension of the SU(N) gauge group (number of gluons) p 1,2 are the parton momenta

9. Seminários GFPAE – 02/2009 9 NLO Production Running of the coupling constant n 1f = 3 (4) charm (bottom)

10. Seminários GFPAE – 02/2009 10 NLO functions 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  Error of 1%

11. Seminários GFPAE – 02/2009 11 NLO Production Auxiliary functions

12. Seminários GFPAE – 02/2009 12 Diffractive cross section Pomeron flux factor Pomeron Structure Function (H1) KKMR model = 0.06 at LHC single diffractive events FIT A Similar results with FIT B

13. Seminários GFPAE – 02/2009 13 Incoherent diffractive is a process where A* denotes the excited nucleus that subsequently decays into a system of colorless hadrons Diffractive incoherent ratio Coherent diffractive is a process where Stronger dependence on energy and atomic number Diffractive Nuclear heavy quark production single diffraction

14. Seminários GFPAE – 02/2009 14 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

15. Seminários GFPAE – 02/2009 15 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

16. Seminários GFPAE – 02/2009 16 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

17. Seminários GFPAE – 02/2009 17 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

18. Seminários GFPAE – 02/2009 18 Incoherent results  There are not values of to single diffraction in AA collisions  Estimatives to Higgs central production ~ 1 x 10 -4  Values of diffractive cross section in a region possible to be verified

19. Seminários GFPAE – 02/2009 19 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

20. Seminários GFPAE – 02/2009 20 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

21. Seminários GFPAE – 02/2009 21 References M. B. Gay Ducati, M. M. Machado, M. V. T. Machado, arXiv:0908.0507 [hep-ph] (2009) M. B. Gay Ducati, M. M. Machado, M. V. T. Machado, PRD 75, 114013 (2007) P. D. Collins, An Introduction to Regge Theory and High Energy Physics (1977) G. Ingelman and P. Schlein, Phys. Lett. B 152 (1985) 256. M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295 M. L. Mangano arXiv:hep-ph/9711337v1 (1997) H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 V. A. Khoze, A. D. Martin, M. G. Ryskin, Eur. Phys. J. C18, 167 (2000) N. M. Agababyan et al Phys. Atom. Nucl. 62, 1572 (1999) K. Tuchin, arXiv:0812.1519v2 [hep-ph] (2009) E. Levin; J. Miller arXiv:0801.3593v1 [hep-ph] (2008) P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607