Double-diffractive production of heavy quarkonia

Double-diffractive production Double-diffractive production of heavy quarkoniaof heavy quarkonia

Dubna, JINR

Roman Pasechnik

based on:R. Pasechnik, A. Szczurek, O. Teryaev Phys. Rev. D78: 014007, 2008

Inclusive heavy quarkonia production

kt-factorizationapproach

NLLA BFKL vertexin QMRK

agreement with the data

P. Hagler, R. Kirshner, A. Schafer, L. Szymanowski, O. Teryaev, ‘00,’01A. Lipatov, V. Saleev, N. Zotov, ‘01, ‘03

Kaidalov-Khose-Martin-Ryskin (KKMR) approach

Exclusive diffractive Higgs production in terms of UGDFs

Our goal:

• to apply this QCD mechanism to heavy quarkonia production• to explore related uncertainties

c.m.s. frame

production vertex

pNRQCD projector to color singlet bound state

gluon virtualities are explicitly taken into account !

satisfied! projection to gluon polarizations

correlation of our and KMR approaches in the zeroth approximation!

Large meson mass limit (KMR)

or

KMR UGDF

Sudakov f.fintegrated

density

main contribution to the amplitude comes fromvery small gluon transverse momenta

huge sensitivity to details in non-perturbative domain !!!

hard scale

different prescriptions for

isoscalar nucleon f.f.

non-perturbative input for QCD evolution

Major uncertainties in KMR approachDependence on effective transverse momentum in KMR approach

Dependence on the lower cut on the gluon transverse momenta Off-shell effect Different models for

the running coupling

Our results for different UGDFs

xF-distribution for Gaussian UGDF

different scale choices

Transverse meson momentumdistribution for different UGDFs

KMR UGDF

Our results for different UGDFst,xF,y-distributions for different UGDFs:KL – dashed; GBW – dotted; BFKL – dash-dotted; KMR – solid (in min, max eff Qt-prescriptions)

Off-shell effect at different rapidities and meson masses

Energy dependence and total cross section

RHIC

LHC

Main points and results1. Strong dependence on factorization scale choice, especially

3. We don’t use KMR UGDF based on Sudakov because of very restricted region of gluon momentum fractions allowed by Sudakov formfactor. We would need in extrapolation to other regions that is mainly arbitrary.

5. Significant contribution to cross section comes from non-perturbative region (order of fraction of GeV), unlike Higgs production – a sort of continuation of perturbative result to the region where its applicability cannot be rigorously proven.

2. Strong dependence on UGDFs choice. We use non-perturbativelymodelled UGDFs, like KL, Gauss etc. Experiments should justify whatUGDF is valid.

4. Off-shellness of the intermediate gluons is estimated to be important in the case of charmonium production.