estimating the diffractive heavy quark production in heavy ion collisions at the lhc *
DESCRIPTION
Mairon Melo Machado GFPAE – IF – UFRGS www.if.ufrgs.br/gfpae [email protected]. Estimating the diffractive heavy quark production in heavy ion collisions at the LHC *. Motivation Diffractive Physics Hadroproduction of heavy quarks at LO Hadroproduction of heavy quarks at NLO - PowerPoint PPT PresentationTRANSCRIPT
1Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
Estimating the diffractive heavy quark production in heavy ion
collisions at the LHC*
Mairon Melo MachadoGFPAE – IF – UFRGSwww.if.ufrgs.br/gfpae
2Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
3Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
Motivation1, 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)
BBH BBgg signal background
4Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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)
5Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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.
6Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
o Focus on the following single diffractive processes
Heavy quark hadroproduction
o Diffractive ratios as a function of energy center-mass ECM
X+CC+ppp X+BB+ppp
o Diagrams contributing to the lowest order cross section 5
5 M. L. Mangano et al, Nucl. Phys. B 373, 295 (1992)
Q+Qg+g
7Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
LO hadroproductionTotal 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 RF μμ
8Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
V=N 2− 1 Dimension of the SU(N) gauge group
(number of gluons)
p1,2 are the parton momenta
Sα
9Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
NLO Production
5
5 M. L. Mangano, P. Nason, G. Ridolfi Nucl. Phys. B373 (1992) 295
g+Q+Qg+g
Running of the coupling constant
n1f = 3 (4) charm (bottom)
10Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
NLO functions
7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607
a0 0.108068
a1 -0.114997
a2 0.0428630
a3 0.131429
a4 0.0438768
a5 -0.0760996
a6 -0.165878
a7 -0.158246
Using a physical motivation fit to the numerically integrated result 7
Error of 1%
11Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
NLO Production
7Auxiliary functions
7 P. Nason, S. Dawson, R. K. Ellis Nucl. Phys. B303 (1988) 607
12Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
Diffractive cross section
Pomeron flux factor
Pomeron Structure Function (H1) 6
β=xxIP
6 H1 Coll. A. Aktas et al, Eur. J. Phys. J. C48 (2006) 715
KKMR model <|S|2> = 0.06 at LHC single diffractive events 7
7 V. A. Khoze, A. D. Martin, M. G. Ryskin, Eur. Phys. J. C18, 167 (2000)
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
14Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
*A+[LRG]+A+XA+A
8 N. M. Agababyan et al Phys. Atom. Nucl. 62, 1572 (1999)
9 K. Tuchin, arXiv:0812.1519v2 [hep-ph] (2009)
single diffraction 8
A+[LRG]+A+XA+A
15Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
16Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
Diffractive comparison
• 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
Inclusive
Diffractive wt/GSP
Diffractive wh/GSP
17Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
18Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
Cross sections in NLO to inclusive nuclear cross section
ACa = 40 APb = 208
Results for heavy quark production
Cross sections in NLO for heavy quarks hadroproduction
GSP value decreases the diffractive rate
<|S|2> = 0.06
19Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
Incoherent results
11 E. Levin; J. Miller arXiv:0801.3593v1 [hep-ph] (2008)
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
20Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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
21Workshop on Diffractive Physics at the LHC – Rio de Janeiro – Sep. 2009
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