angular distributions at Z0 peak at the LHC Tomasz Stebel with Leszek Motyka and Mariusz Sadzikowski M Smoluchowski Institute of Physics Jagiellonian University Drell ID: 1044291
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1. What can we learn from dilepton angular distributions at Z0 peak at the LHC? Tomasz Stebel (with Leszek Motyka and Mariusz Sadzikowski)M. Smoluchowski Institute of Physics, Jagiellonian University
2. Drell –Yan process 2
3. Angular coefficients3ATLAS, arXiv:1606.00689
4. 4Lam – Tung relation: collinear approachPhys. Rev. D 21 (1980) 2712It is valid up to NLO, at the leading twist.Checked for the DY dipole model approach Motyka, Sadzikowski, TS, JHEP 1505 (2015) 087 NNLO corrections nonzero L-T rel. breakingMirkes and Ohnemus, Phys. Rev. D 51, 4891 (1995).Boer, Phys. Rev. D 60, 014012 (1999)Boer and Mulders, Phys. Rev. D 57, 5780 (1998)Peng, Chang, McClellan, Teryaev, Phys.Lett. B758 (2016) 384-388
5. Recent ATLAS analysis for 8 TeV5ATLAS data and collinear approachJHEP 1608 (2016) 159, arXiv:1606.00689
6. Parton shower:6ATLAS data and colinear approach
7. NNLO does not describe the data sufficiently well.What can we do?- Try NNNLO.- Try -factorization approach. 7We miss something…GribovBalitsky, Fadin, Kuraev, Lipatov, Levin, RyskinCatani, Ciafaloni, Collins, ElliskT approach in DY:Brodsky, Habecker, QuackKopeliovichNefedov, Nikolaev, SaleevBaranov, Lipatov, Zotov
8. Following: Nefedov, Nikolaev, Saleev; Phys.Rev. D87 (2013) no.1, 014022; arXiv:1211.5539.8First approach in formalism Quark Parton Reggeization ApproachGluon Transverse-momentum-dependent distribution (TDM)Hautmann, Hentschinski, Jung, arXiv:1207.6420
9. 9First approach in -formalism Gluon TDM: Jung, Hautmann, arXiv:1312.7875
10. Two channels:Approximate NNLO in -formalism 2 diagramsApproximate NNLO = no gluon emission includedBrodsky, Arthur Hebecker, E. Quack; Phys.Rev. D55 (1997) 2584-2590Schäfer, Szczurek, Phys.Rev. D93 (2016) no.7, 0740148 diagrams NEWContain Contain 10: Lipatov et al.
11. Jung, Hautmann (JH)LO BFKL solution for TMD (with GBW initial condition):11Gluon TMDsarXiv:1207.6420Mellin tr.Weisacker–Williams-type gluon: Inspired by behavior of non-uniform term of in Kwiecinski, Martin, Stasto unified evolution equation, Phys.Rev. D56 (1997) 3991-4006; hep-ph/9703445.
12. 12Comparison with ATLAS data
13. 13Comparison with data: and WWJHBFKLReggeized
14. 14How sensitive to the form of TDM this observable is?
15. 15What can we learn from these results?For enough to describe the data we need: diagrams in -formalism Proper gluon TMD – very important - dependence.
16. ATLAS data for 7 TeV, small dilepton mass (photon mediated).16Total cross-sectionarXiv:1404.1212 Fixing normalization of the model Martin, Ryskin, Watt, Phys. Rev. D 70, 014012 (2004);Lipatov, Malyshev, Zotov, JHEP 1112, 117 (2011).
17. Good overall description of DY observables from the LHC was obtained in - factorization framework with and channels. - factorization approach could explain high behavior of Lam Tung relation breaking much better than collinear NNLO QCD approximation.Hard behavior of gluon TMD at moderate favored by dataThis could be very sensitive tool for testing gluon TMD.Further improvement is possible (problem with loops in approach). Summary15
18. Thank you