Estimating the diffractive heavy quark production in heavy ion collisions at the LHC *

1. Mairon Melo Machado GFPAE – IF – UFRGS www.if.ufrgs.br/gfpae melo.machado@ufrgs.br Estimating the diffractive heavy quark production in heavy ion collisions at the LHC*

2. 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 Outlook

3. 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) Motivation • 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 signal background

4. 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) Introduction Diffractive structure function Gap Survival Probability (GSP)

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 Φof the final state phase space 4 G. Ingelman and P. Schlein, Phys. Lett. 152B (1985) 256. Diffractive events Ingelman-Schlein Model Rapidity gaps

6. Diffractive ratios as a function of energy center-mass ECM 5 M. L. Mangano et al, Nucl. Phys. B 373, 295 (1992) Heavy quark hadroproduction • Focus on the following single diffractive processes • Diagrams contributing to the lowest order cross section5

7. 5 M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295 LO hadroproduction 5 Total cross section are the parton distributions inner the hadron i=1 and j=2 Partonical cross section factorisation (renormalization) scale

8. 6 M. L. Mangano arXiv:hep-ph/9711337v1 (1997) Partonic cross section 6 is the coupling constant m is the heavy quark mass p1,2 are the parton momenta Dimension of the SU(N) gauge group (number of gluons) N = 3 (4) to charm (bottom)

9. 5 M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295 NLO Production 5 Running of the coupling constant n1f = 3 (4) charm (bottom)

10. 7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607 NLO functions • Using a physical motivation fit to the numerically integrated result 7 • Error of 1%

11. 7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607 NLO Production Auxiliary functions 7

12. 6 H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 7 V. A. Khoze, A. D. Martin, M. G. Ryskin, Eur. Phys. J. C18, 167 (2000) Diffractive cross section Pomeron flux factor Pomeron Structure Function (H1) 6 KKMR model <|S|2> = 0.06 at LHC single diffractive events 7

13. 6 H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715 H1 Gluon distribution 6 • In this work we use FIT A. Similar results with FIT B

14. 8 N. M. Agababyan et al Phys. Atom. Nucl. 62, 1572 (1999) 9 K. Tuchin, arXiv:0812.1519v2 [hep-ph] (2009) Diffractive Nuclear heavy quark production single diffraction 8 • 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

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 • Mc = 1.5 GeV Inclusive quarks/gluons Inclusive gluons Diffractive

16. Diffractive comparison Inclusive Diffractive wt/GSP Diffractive wh/GSP • Diffractive cross sections to bottom-antibottom hadroproduction • Relevant contribution of GSP value in the total diffractive cross section • <|S|2> = 0.06 • Mb = 4.7 GeV

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

18. Results for heavy quark production Cross sections in NLO for heavy quarks hadroproduction GSP value decreases the diffractive rate <|S|2> = 0.06 Cross sections in NLO to inclusive nuclear cross section ACa = 40 APb = 208

19. 11 E. Levin; J. Miller arXiv:0801.3593v1 [hep-ph] (2008) Incoherent results • There are not values of <|S|2> to single diffraction in AA collisions • Estimatives to Higgs central production11 <|S|2> ~ 1 x 10-4 • Values of diffractive cross section in a region possible to be verified

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

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 ECM • Diffractive ratio is computed using hard diffractive factorization and absorptive corrections (NLO) • There are not predictions to <|S|2> 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