Precise predictions for the angular coefficients in Z-boson production at the LHC
Abstract The angular distributions of lepton pairs in the Drell-Yan process can provide rich information on the underlying QCD production mechanisms. These dynamics can be parameterised in terms of a set of frame dependent angular coefficients, A i=0,…,7, which depend on the invariant mass, transver...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
SpringerOpen
2017-11-01
|
| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP11(2017)003 |
| _version_ | 1811218040889540608 |
|---|---|
| author | R. Gauld A. Gehrmann-De Ridder T. Gehrmann E.W.N. Glover A. Huss |
| author_facet | R. Gauld A. Gehrmann-De Ridder T. Gehrmann E.W.N. Glover A. Huss |
| author_sort | R. Gauld |
| collection | DOAJ |
| description | Abstract The angular distributions of lepton pairs in the Drell-Yan process can provide rich information on the underlying QCD production mechanisms. These dynamics can be parameterised in terms of a set of frame dependent angular coefficients, A i=0,…,7, which depend on the invariant mass, transverse momentum, and rapidity of the lepton pair. Motivated by recent measurements of these coefficients by ATLAS and CMS, and in particular by the apparent violation of the Lam-Tung relation A 0 − A 2 = 0, we perform a precision study of the angular coefficients at Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$ in perturbative QCD. We make predic-tions relevant for pp collisions at s=8 $$ \sqrt{s}=8 $$ TeV, and perform comparisons with the available ATLAS and CMS data as well as providing predictions for a prospective measurement at LHCb. To expose the violation of the Lam-Tung relationship we propose a new observable ΔLT = 1 − A 2 /A 0 that is more sensitive to the dynamics in the region where A 0 and A 2 are both small. We find that the Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$ corrections have an important impact on the p T,Z distributions for several of the angular coefficients, and are essential to provide an adequate description of the data. The compatibility of the available ATLAS and CMS data is reassessed by performing a partial χ 2 test with respect to the central theoretical prediction which shows that χ 2 /N data is significantly reduced by going from Oαs2 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^2\right) $$ to Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$. |
| first_indexed | 2024-04-12T07:04:25Z |
| format | Article |
| id | doaj.art-16f7b96b13e945af82710ec7622b2297 |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-04-12T07:04:25Z |
| publishDate | 2017-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-16f7b96b13e945af82710ec7622b22972022-12-22T03:42:52ZengSpringerOpenJournal of High Energy Physics1029-84792017-11-0120171112610.1007/JHEP11(2017)003Precise predictions for the angular coefficients in Z-boson production at the LHCR. Gauld0A. Gehrmann-De Ridder1T. Gehrmann2E.W.N. Glover3A. Huss4Institute for Theoretical Physics, ETHInstitute for Theoretical Physics, ETHDepartment of Physics, University of ZürichInstitute for Particle Physics Phenomenology, Durham UniversityInstitute for Theoretical Physics, ETHAbstract The angular distributions of lepton pairs in the Drell-Yan process can provide rich information on the underlying QCD production mechanisms. These dynamics can be parameterised in terms of a set of frame dependent angular coefficients, A i=0,…,7, which depend on the invariant mass, transverse momentum, and rapidity of the lepton pair. Motivated by recent measurements of these coefficients by ATLAS and CMS, and in particular by the apparent violation of the Lam-Tung relation A 0 − A 2 = 0, we perform a precision study of the angular coefficients at Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$ in perturbative QCD. We make predic-tions relevant for pp collisions at s=8 $$ \sqrt{s}=8 $$ TeV, and perform comparisons with the available ATLAS and CMS data as well as providing predictions for a prospective measurement at LHCb. To expose the violation of the Lam-Tung relationship we propose a new observable ΔLT = 1 − A 2 /A 0 that is more sensitive to the dynamics in the region where A 0 and A 2 are both small. We find that the Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$ corrections have an important impact on the p T,Z distributions for several of the angular coefficients, and are essential to provide an adequate description of the data. The compatibility of the available ATLAS and CMS data is reassessed by performing a partial χ 2 test with respect to the central theoretical prediction which shows that χ 2 /N data is significantly reduced by going from Oαs2 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^2\right) $$ to Oαs3 $$ \mathcal{O}\left({\alpha}_{\mathrm{s}}^3\right) $$.http://link.springer.com/article/10.1007/JHEP11(2017)003QCD Phenomenology |
| spellingShingle | R. Gauld A. Gehrmann-De Ridder T. Gehrmann E.W.N. Glover A. Huss Precise predictions for the angular coefficients in Z-boson production at the LHC Journal of High Energy Physics QCD Phenomenology |
| title | Precise predictions for the angular coefficients in Z-boson production at the LHC |
| title_full | Precise predictions for the angular coefficients in Z-boson production at the LHC |
| title_fullStr | Precise predictions for the angular coefficients in Z-boson production at the LHC |
| title_full_unstemmed | Precise predictions for the angular coefficients in Z-boson production at the LHC |
| title_short | Precise predictions for the angular coefficients in Z-boson production at the LHC |
| title_sort | precise predictions for the angular coefficients in z boson production at the lhc |
| topic | QCD Phenomenology |
| url | http://link.springer.com/article/10.1007/JHEP11(2017)003 |
| work_keys_str_mv | AT rgauld precisepredictionsfortheangularcoefficientsinzbosonproductionatthelhc AT agehrmannderidder precisepredictionsfortheangularcoefficientsinzbosonproductionatthelhc AT tgehrmann precisepredictionsfortheangularcoefficientsinzbosonproductionatthelhc AT ewnglover precisepredictionsfortheangularcoefficientsinzbosonproductionatthelhc AT ahuss precisepredictionsfortheangularcoefficientsinzbosonproductionatthelhc |