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Title: Precision study of the η → μ +μ -γ and ω → μ +μ -π 0 electromagnetic transition form-factors and of the ρ → μ +μ - line shape in NA60

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 - M 22) -2 we find Λ -2 η = 1.934 ± 0.067 (stat.) ±0.050(syst.) (GeV/c 2) -2 and Λ -2 ω = 2.223 ± 0.026(stat.) ± 0.037(syst.) (GeV/c 2) -2. An improved value of the branching ratio of the Dalitz decay ω → μ +μ -π 0 is also obtained, with BR(ω → μ +μ -π 0) = [1.41 ± 0.09(stat.) ± 0.15(syst.)] ×10 -4. Finally, further results refer to the ρ line shape and a new limit on ρ/ω interference in hadron interactions.
Authors:
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Publication Date:
Report Number(s):
BNL-113815-2017-JA
Journal ID: ISSN 0370-2693; R&D Project: PO 024; KA2501032
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 757; Journal ID: ISSN 0370-2693
Publisher:
Elsevier
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
NA60 Collaboration
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Lepton pairs; Transition form factor; Conversion decays; Rho meson
OSTI Identifier:
1354708

Arnaldi, R., Banicz, K., Borer, K., Castor, J., Chaurand, B., Chen, W., Cicalò, C., Colla, A., Cortese, P., Damjanovic, S., David, A., de Falco, A., Devaux, A., Ducroux, L., En'yo, H., Fargeix, J., Ferretti, A., Floris, M., Förster, A., Force, P., Guettet, N., Guichard, A., Gulkanian, H., Heuser, J. M., Jarron, P., Keil, M., Kluberg, L., Li, Z., Lourenço, C., Lozano, J., Manso, F., Martins, P., Masoni, A., Neves, A., Ohnishi, H., Oppedisano, C., Parracho, P., Pillot, P., Poghosyan, T., Puddu, G., Radermacher, E., Ramalhete, P., Rosinsky, P., Scomparin, E., Seixas, J., Serci, S., Shahoyan, R., Sonderegger, P., Specht, H. J., Tieulent, R., Uras, A., Usai, G., Veenhof, R., and Wöhri, H. K.. Precision study of the η → μ+μ-γ and ω → μ+μ-π0 electromagnetic transition form-factors and of the ρ → μ+μ- line shape in NA60. United States: N. p., Web. doi:10.1016/j.physletb.2016.04.013.
Arnaldi, R., Banicz, K., Borer, K., Castor, J., Chaurand, B., Chen, W., Cicalò, C., Colla, A., Cortese, P., Damjanovic, S., David, A., de Falco, A., Devaux, A., Ducroux, L., En'yo, H., Fargeix, J., Ferretti, A., Floris, M., Förster, A., Force, P., Guettet, N., Guichard, A., Gulkanian, H., Heuser, J. M., Jarron, P., Keil, M., Kluberg, L., Li, Z., Lourenço, C., Lozano, J., Manso, F., Martins, P., Masoni, A., Neves, A., Ohnishi, H., Oppedisano, C., Parracho, P., Pillot, P., Poghosyan, T., Puddu, G., Radermacher, E., Ramalhete, P., Rosinsky, P., Scomparin, E., Seixas, J., Serci, S., Shahoyan, R., Sonderegger, P., Specht, H. J., Tieulent, R., Uras, A., Usai, G., Veenhof, R., & Wöhri, H. K.. Precision study of the η → μ+μ-γ and ω → μ+μ-π0 electromagnetic transition form-factors and of the ρ → μ+μ- line shape in NA60. United States. doi:10.1016/j.physletb.2016.04.013.
Arnaldi, R., Banicz, K., Borer, K., Castor, J., Chaurand, B., Chen, W., Cicalò, C., Colla, A., Cortese, P., Damjanovic, S., David, A., de Falco, A., Devaux, A., Ducroux, L., En'yo, H., Fargeix, J., Ferretti, A., Floris, M., Förster, A., Force, P., Guettet, N., Guichard, A., Gulkanian, H., Heuser, J. M., Jarron, P., Keil, M., Kluberg, L., Li, Z., Lourenço, C., Lozano, J., Manso, F., Martins, P., Masoni, A., Neves, A., Ohnishi, H., Oppedisano, C., Parracho, P., Pillot, P., Poghosyan, T., Puddu, G., Radermacher, E., Ramalhete, P., Rosinsky, P., Scomparin, E., Seixas, J., Serci, S., Shahoyan, R., Sonderegger, P., Specht, H. J., Tieulent, R., Uras, A., Usai, G., Veenhof, R., and Wöhri, H. K.. 2016. "Precision study of the η → μ+μ-γ and ω → μ+μ-π0 electromagnetic transition form-factors and of the ρ → μ+μ- line shape in NA60". United States. doi:10.1016/j.physletb.2016.04.013. https://www.osti.gov/servlets/purl/1354708.
@article{osti_1354708,
title = {Precision study of the η → μ+μ-γ and ω → μ+μ-π0 electromagnetic transition form-factors and of the ρ → μ+μ- line shape in NA60},
author = {Arnaldi, R. and Banicz, K. and Borer, K. and Castor, J. and Chaurand, B. and Chen, W. and Cicalò, C. and Colla, A. and Cortese, P. and Damjanovic, S. and David, A. and de Falco, A. and Devaux, A. and Ducroux, L. and En'yo, H. and Fargeix, J. and Ferretti, A. and Floris, M. and Förster, A. and Force, P. and Guettet, N. and Guichard, A. and Gulkanian, H. and Heuser, J. M. and Jarron, P. and Keil, M. and Kluberg, L. and Li, Z. and Lourenço, C. and Lozano, J. and Manso, F. and Martins, P. and Masoni, A. and Neves, A. and Ohnishi, H. and Oppedisano, C. and Parracho, P. and Pillot, P. and Poghosyan, T. and Puddu, G. and Radermacher, E. and Ramalhete, P. and Rosinsky, P. and Scomparin, E. and Seixas, J. and Serci, S. and Shahoyan, R. and Sonderegger, P. and Specht, H. J. and Tieulent, R. and Uras, A. and Usai, G. and Veenhof, R. and Wöhri, H. K.},
abstractNote = {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 Λ-2η = 1.934 ± 0.067 (stat.) ±0.050(syst.) (GeV/c2)-2 and Λ-2ω = 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. Finally, further results refer to the ρ line shape and a new limit on ρ/ω interference in hadron interactions.},
doi = {10.1016/j.physletb.2016.04.013},
journal = {Physics Letters. Section B},
number = ,
volume = 757,
place = {United States},
year = {2016},
month = {4}
}