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A measurement of the production cross-section for Z bosons that decay to muons is presented. The data were recorded by the LHCb detector during pp collisions at a centre-of-mass energy of 7 TeV, and correspond to an integrated luminosity of 1.0 fb(-1). The cross-section is measured for muons in the pseudorapidity range 2.0 < eta < 4.5 with transverse momenta p(T) >20 GeV/e. The dimuon mass is restricted to 60 < M mu+mu- < 120 GeV/c(2). The measured cross-section is sigma(Z ->mu+mu-) = (76.0 +/- 0.3 +/- 0.5 +/- 1.0 +/- 1.3) pb where the uncertainties are due to the sample size, systematic effects, the beam energy and the luminosity. This result is in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. The cross-section is also measured differentially as a function of kinematic variables of the Z boson. Ratios of the production cross-sections of electroweak bosons are presented using updated LHCb measurements of W boson production. A precise test of the Standard Model is provided by the measurement of the ratio sigma(W+) -> mu(+) nu(mu) + sigma(W) -> mu(+) (nu) over bar (mu)/sigma(Z ->mu+mu-) = 0.09 +/- 0.12 +/- 0.05, where the uncertainty due to luminosity cancels.
Lesya Shchutska, Olivier Schneider, Yi Zhang, Aurelio Bay, Yi Wang, Guido Haefeli, Frédéric Blanc, Tatsuya Nakada, François Fleuret, Elena Graverini, Renato Quagliani, Federico Betti, Sebastian Schulte, Veronica Sølund Kirsebom, Carina Trippl, Sara Celani, Jian Wang, Mingkui Wang, Zhirui Xu, Zheng Wang, Lei Zhang, Ho Ling Li, Christoph Frei, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Michel De Cian, Maurizio Martinelli, Vladislav Balagura, Liang Sun, Pietro Marino, Luca Pescatore, Mirco Dorigo, Xiaoxue Han, Liupan An, Federico Leo Redi, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Olivier Göran Girard, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Yao Zhou, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Evgenii Shmanin, Simone Meloni, Xiaoqing Zhou, Surapat Ek-In, Dipanwita Dutta, Yiming Li, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Victor Coco, Adam Davis, Paolo Durante, Yu Zheng, Anton Petrov, Maxim Borisyak, Chunhui Chen, Zhipeng Tang, Xuan Li, Alexey Boldyrev, Almagul Kondybayeva, Hossein Afsharnia
Olivier Schneider, Aurelio Bay, Yi Zhang, Yi Wang, Guido Haefeli, Frédéric Blanc, Tatsuya Nakada, François Fleuret, Elena Graverini, Renato Quagliani, Federico Betti, Sebastian Schulte, Veronica Sølund Kirsebom, Jian Wang, Mingkui Wang, Zhirui Xu, Zheng Wang, Lei Zhang, Ho Ling Li, Christoph Frei, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Michel De Cian, Greig Alan Cowan, Maurizio Martinelli, Vladislav Balagura, Liang Sun, Pietro Marino, Luca Pescatore, Mirco Dorigo, Xiaoxue Han, Liupan An, Federico Leo Redi, Chitsanu Khurewathanakul, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Olivier Göran Girard, Axel Kuonen, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Yao Zhou, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Evgenii Shmanin, Simone Meloni, Xiaoqing Zhou, Surapat Ek-In, Dipanwita Dutta, Yiming Li, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Victor Coco, Adam Davis, Paolo Durante, Yu Zheng, Anton Petrov, Maxim Borisyak, Chunhui Chen, Zhipeng Tang, Xuan Li, Alexey Boldyrev, Almagul Kondybayeva, Hossein Afsharnia
Olivier Schneider, Aurelio Bay, Yi Zhang, Yi Wang, Guido Haefeli, Frédéric Blanc, Tatsuya Nakada, François Fleuret, Elena Graverini, Renato Quagliani, Federico Betti, Sebastian Schulte, Veronica Sølund Kirsebom, Jian Wang, Mingkui Wang, Zhirui Xu, Zheng Wang, Lei Zhang, Ho Ling Li, Christoph Frei, Mark Tobin, Minh Tâm Tran, Niko Neufeld, Matthew Needham, Marc-Olivier Bettler, Michel De Cian, Greig Alan Cowan, Maurizio Martinelli, Vladislav Balagura, Liang Sun, Pietro Marino, Luca Pescatore, Mirco Dorigo, Xiaoxue Han, Liupan An, Federico Leo Redi, Chitsanu Khurewathanakul, Plamen Hristov Hopchev, Thibaud Humair, Maxime Schubiger, Hang Yin, Guido Andreassi, Violaine Bellée, Maria Vieites Diaz, Olivier Göran Girard, Axel Kuonen, Preema Rennee Pais, Pavol Stefko, Tara Nanut, Maria Elena Stramaglia, Tommaso Colombo, Vladimir Macko, Guillaume Max Pietrzyk, Albert Puig Navarro, Evgenii Shmanin, Lino Ferreira Lopes, Dipanwita Dutta, Yiming Li, Hans Dijkstra, Gerhard Raven, Peter Clarke, Frédéric Teubert, Victor Coco, Adam Davis, Paolo Durante, Yu Zheng, Anton Petrov, Maxim Borisyak, Chunhui Chen, Zhipeng Tang, Luis Alberto Granado Cardoso, Katharina Müller, Xuan Li