Measurement of τ polarisation in Z/ γ∗→ ττ decays in proton–proton collisions at √s=8 TeV with the ATLAS detector

ATLAS Collaboration

doi:10.1140/epjc/s10052-018-5619-1

Measurement of τ polarisation in Z/ γ^∗→ ττ decays in proton–proton collisions at √s=8 TeV with the ATLAS detector

ATLAS Collaboration

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

This paper presents a measurement of the polarisation of τ leptons produced in Z/ γ^∗→ ττ decays which is performed with a dataset of proton—proton collisions at s=8 TeV, corresponding to an integrated luminosity of 20.2 fb^{- 1} recorded with the ATLAS detector at the LHC in 2012. The Z/ γ^∗→ ττ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z/ γ^∗ mass range of 66 <mZ/ 116 GeV is found to be P_τ= - 0.14 ± 0.02 (stat) ± 0.04 (syst). It is in agreement with the Standard Model prediction of P_τ= - 0.1517 ± 0.0019 , which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.

Original language	English
Article number	163
Journal	European Physical Journal C
Volume	78
Issue number	2
DOIs	https://doi.org/10.1140/epjc/s10052-018-5619-1
State	Published - 1 Feb 2018

Funding

Funders	Funder number
Agence Nationale de la Recherche
Australian Research Council
Centre National pour la Recherche Scientifique et Technique
Fundação para a Ciência e a Tecnologia
Comisión Nacional de Investigación Científica y Tecnológica
Narodowe Centrum Nauki
CEA-DRF
H2020 Marie Skłodowska-Curie Actions
Région Auvergne
Wal-lenberg Foundation
Japan Society for the Promotion of Science
Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Ministry of Science and Technology, Taiwan
Israel Science Foundation
Leverhulme Trust
Arizona-Nevada Academy of Science
Javna Agencija za Raziskovalno Dejavnost RS
Generalitat de Catalunya, Generalitat Valen-ciana
Instituto Nazionale di Fisica Nucleare
Bundesministerium für Wissenschaft, Forschung und Wirtschaft
Austrian Science Fund
Department of Science and Technology, Ministry of Science and Technology, India
MSMT
MSSR
Ministerio de Economía y Competitividad
Bundesministerium für Bildung und Forschung
Canada Foundation for Innovation
Helmholtz-Gemeinschaft
Danmarks Grundforskningsfond
Conselho Nacional de Desenvolvimento Científico e Tecnológico
Czech Republic
Singapore Eye Research Institute
Canarie
Ontario Innovation Trust
MIZŠ
Deutsche Forschungsgemeinschaft
United States-Israel Binational Science Foundation
Neurosurgical Research Foundation
MESTD
U.S. Department of Energy
EU-ESF
RGC
Fundação de Amparo à Pesquisa do Estado de São Paulo
Israeli Centers for Research Excellence
Biomedical Research Foundation
COLCIEN-CIAS
MES of Russia
National Research Center "Kurchatov Institute"
Institutul de Fizică Atomică
Natural Sciences and Engineering Research Council of Canada
General Secretariat for Research and Technology
Nella and Leon Benoziyo Center for Neurological Diseases, Weizmann Institute of Science
Fonds Québécois de la Recherche sur la Nature et les Technologies
Cantons of Bern and Geneva
Canada Council for the Arts
Chinese Academy of Sciences
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
VSC CR
Glycemic Index Foundation
CRC Health Group
Compute Canada
Shota Rustaveli National Science Foundation
MNE
Agencia Nacional de Promoción Científica y Tecnológica
Royal Society
Minerva Foundation
European Research Council
European Regional Development Fund
Ministerstwo Nauki i Szkolnictwa Wyższego
IRFU
CERN
Joint Institute for Nuclear Research
Fondation Partager le Savoir
National Research Council Canada
Alexander von Humboldt-Stiftung
Council on grants of the President of the Russian Federation
Horizon 2020
British Columbia Knowledge Development Fund
Ministry of Education, Culture, Sports, Science and Technology
National Natural Science Foundation of China
DNSRC	IN2P3-CNRS
Science and Technology Facilities Council	ST/P002439/1, ST/N000447/1, PP/E000452/1, ST/H001158/1, 1653101, ST/N000331/1, ST/H001158/2, GRIDPP, ST/N000277/1, ST/R002444/1, 1668509
National Science Foundation	1624739
Seventh Framework Programme	246806

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10.1140/epjc/s10052-018-5619-1

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@article{93081974a12c4a5488c457994a5058c9,

title = "Measurement of τ polarisation in Z/ γ∗→ ττ decays in proton–proton collisions at √s=8 TeV with the ATLAS detector",

abstract = "This paper presents a measurement of the polarisation of τ leptons produced in Z/ γ∗→ ττ decays which is performed with a dataset of proton—proton collisions at s=8 TeV, corresponding to an integrated luminosity of 20.2 fb- 1 recorded with the ATLAS detector at the LHC in 2012. The Z/ γ∗→ ττ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z/ γ∗ mass range of 66 τ= - 0.14 ± 0.02 (stat) ± 0.04 (syst). It is in agreement with the Standard Model prediction of Pτ= - 0.1517 ± 0.0019 , which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.",

author = "{ATLAS Collaboration} and M. Aaboud and G. Aad and B. Abbott and O. Abdinov and B. Abeloos and Abidi, {S. H.} and AbouZeid, {O. S.} and Abraham, {N. L.} and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and Acharya, {B. S.} and S. Adachi and L. Adamczyk and J. Adelman and M. Adersberger and T. Adye and Affolder, {A. A.} and Y. Afik and T. Agatonovic-Jovin and C. Agheorghiesei and Aguilar-Saavedra, {J. A.} and Ahlen, {S. P.} and F. Ahmadov and G. Aielli and S. Akatsuka and H. Akerstedt and {\AA}kesson, {T. P.A.} and E. Akilli and Akimov, {A. V.} and Alberghi, {G. L.} and J. Albert and P. Albicocco and {Alconada Verzini}, {M. J.} and Alderweireldt, {S. C.} and M. Aleksa and Aleksandrov, {I. N.} and G. Alexander and A. Ashkenazi and L. Barak and G. Bella and Y. Benhammou and T. Cao and E. Etzion and O. Kuprash and Lutz, {M. S.} and Y. Oren and M. Pitt and A. Soffer",

note = "Publisher Copyright: {\textcopyright} 2018, CERN for the benefit of the ATLAS collaboration.",

year = "2018",

month = feb,

day = "1",

doi = "10.1140/epjc/s10052-018-5619-1",

language = "אנגלית",

volume = "78",

journal = "European Physical Journal C",

issn = "1434-6044",

publisher = "Springer Nature",

number = "2",

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T1 - Measurement of τ polarisation in Z/ γ∗→ ττ decays in proton–proton collisions at √s=8 TeV with the ATLAS detector

AU - ATLAS Collaboration

AU - Aaboud, M.

AU - Aad, G.

AU - Abbott, B.

AU - Abdinov, O.

AU - Abeloos, B.

AU - Abidi, S. H.

AU - AbouZeid, O. S.

AU - Abraham, N. L.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Abulaiti, Y.

AU - Acharya, B. S.

AU - Adachi, S.

AU - Adamczyk, L.

AU - Adelman, J.

AU - Adersberger, M.

AU - Adye, T.

AU - Affolder, A. A.

AU - Afik, Y.

AU - Agatonovic-Jovin, T.

AU - Agheorghiesei, C.

AU - Aguilar-Saavedra, J. A.

AU - Ahlen, S. P.

AU - Ahmadov, F.

AU - Aielli, G.

AU - Akatsuka, S.

AU - Akerstedt, H.

AU - Åkesson, T. P.A.

AU - Akilli, E.

AU - Akimov, A. V.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Albicocco, P.

AU - Alconada Verzini, M. J.

AU - Alderweireldt, S. C.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexander, G.

AU - Ashkenazi, A.

AU - Barak, L.

AU - Bella, G.

AU - Benhammou, Y.

AU - Cao, T.

AU - Etzion, E.

AU - Kuprash, O.

AU - Lutz, M. S.

AU - Oren, Y.

AU - Pitt, M.

AU - Soffer, A.

PY - 2018/2/1

Y1 - 2018/2/1

N2 - This paper presents a measurement of the polarisation of τ leptons produced in Z/ γ∗→ ττ decays which is performed with a dataset of proton—proton collisions at s=8 TeV, corresponding to an integrated luminosity of 20.2 fb- 1 recorded with the ATLAS detector at the LHC in 2012. The Z/ γ∗→ ττ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z/ γ∗ mass range of 66 τ= - 0.14 ± 0.02 (stat) ± 0.04 (syst). It is in agreement with the Standard Model prediction of Pτ= - 0.1517 ± 0.0019 , which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.

AB - This paper presents a measurement of the polarisation of τ leptons produced in Z/ γ∗→ ττ decays which is performed with a dataset of proton—proton collisions at s=8 TeV, corresponding to an integrated luminosity of 20.2 fb- 1 recorded with the ATLAS detector at the LHC in 2012. The Z/ γ∗→ ττ decays are reconstructed from a hadronically decaying τ lepton with a single charged particle in the final state, accompanied by a τ lepton that decays leptonically. The τ polarisation is inferred from the relative fraction of energy carried by charged and neutral hadrons in the hadronic τ decays. The polarisation is measured in a fiducial region that corresponds to the kinematic region accessible to this analysis. The τ polarisation extracted over the full phase space within the Z/ γ∗ mass range of 66 τ= - 0.14 ± 0.02 (stat) ± 0.04 (syst). It is in agreement with the Standard Model prediction of Pτ= - 0.1517 ± 0.0019 , which is obtained from the ALPGEN event generator interfaced with the PYTHIA 6 parton shower modelling and the TAUOLA τ decay library.

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SN - 1434-6044

VL - 78

JO - European Physical Journal C

JF - European Physical Journal C

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M1 - 163

ER -

Measurement of τ polarisation in Z/ γ^∗→ ττ decays in proton–proton collisions at √s=8 TeV with the ATLAS detector

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