Precision study of the η→μμγ and ω→μ+μμπ0 electromagnetic transition form-factors and of the ρ→μμ line shape in NA60

Abstract : The NA60 experiment studied low-mass muon pair production in proton–nucleus (p–A) collisions using a 400 GeV proton beam at the CERN SPS. The low-mass dimuon spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons η , ρ , ω , η′ and ϕ , and no evidence of in-medium effects is found. A new high-precision measurement of the electromagnetic transition form factors of the η and ω was performed, profiting from a 10 times larger data sample than the peripheral In–In sample previously collected by NA60. Using the pole-parameterisation |F(M)|2=(1−M2/Λ2)−2 we find Λη−2=1.934±0.067 (stat.) ±0.050 (syst.) (GeV/c2)−2 and Λω−2=2.223±0.026 (stat.) ±0.037 (syst.) (GeV/c2)−2 . An improved value of the branching ratio of the Dalitz decay ω→μ+μ−π0 is also obtained, with BR(ω→μ+μ−π0)=[1.41±0.09 (stat.)±0.15 (syst.)]×10−4 . Further results refer to the ρ line shape and a new limit on ρ/ω interference in hadron interactions.
Document type :
Journal articles
Complete list of metadatas

Cited literature [21 references]  Display  Hide  Download

http://hal.in2p3.fr/in2p3-01310244
Contributor : Dominique Girod <>
Submitted on : Monday, May 2, 2016 - 10:57:30 AM
Last modification on : Thursday, July 25, 2019 - 1:14:02 PM
Long-term archiving on : Tuesday, May 24, 2016 - 4:45:58 PM

File

1-s2.0-S0370269316300867-main....
Files produced by the author(s)

Identifiers

Citation

R. Arnaldi, K. Banicz, K. Borer, J. Castor, B. Chaurand, et al.. Precision study of the η→μμγ and ω→μ+μμπ0 electromagnetic transition form-factors and of the ρ→μμ line shape in NA60. Physics Letters B, Elsevier, 2016, 757, pp.437-444. ⟨10.1016/j.physletb.2016.04.013⟩. ⟨in2p3-01310244⟩

Share

Metrics

Record views

610

Files downloads

197