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Double-diffractive production of heavy quarkonia. Roman Pasechnik. Dubna, JINR. based on: R. Pas echnik, A. Szczurek, O. Teryaev Phys. Rev. D78: 014007, 2008. Inclusive heavy quarkonia production. agreement with the data. NLLA BFKL vertex in QMRK. kt-factorization approach.
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Double-diffractive production of heavy quarkonia Roman Pasechnik Dubna, JINR
based on:R. Pasechnik,A. Szczurek, O. Teryaev Phys. Rev. D78: 014007, 2008
Inclusive heavy quarkonia production agreement with the data NLLA BFKL vertex in QMRK kt-factorization approach P. Hagler, R. Kirshner, A. Schafer, L. Szymanowski, O. Teryaev, ‘00,’01 A. 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
production vertex pNRQCD projector to color singlet bound state satisfied! projection to gluon polarizations gluon virtualities are explicitly taken into account !
Large meson mass limit (KMR) correlation of our and KMR approaches in the zeroth approximation!
KMR UGDF hard scale integrated density Sudakov f.f main contribution to the amplitude comes from very small gluon transverse momenta different prescriptions for huge sensitivity to details in non-perturbative domain !!!
isoscalar nucleon f.f. non-perturbative input for QCD evolution
Major uncertainties in KMR approach Dependence on effective transverse momentum in KMR approach Dependence on the lower cut on the gluon transverse momenta Different models for the running coupling Off-shell effect
Our results for different UGDFs different scale choices xF-distribution for Gaussian UGDF Transverse meson momentum distribution for different UGDFs KMR UGDF
Our results for different UGDFs t,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
Main points and results • Strong dependence on factorization scale choice, especially 2. Strong dependence on UGDFs choice. We use non-perturbatively modelled UGDFs, like KL, Gauss etc. Experiments should justify what UGDF is valid. 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. 4. Off-shellness of the intermediate gluons is estimated to be important in the case of charmonium production. 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.