Measurement of the decay distribution of η′ → π+π−γ and evidence for the box anomaly

Abele, A.; Adomeit, J.; Amsler, C.; Baker, C.A.; Barnett, B. M.; Batty, C.J.; Benayoun, M.; Berdoz, A.; Beuchert, K.; Bischoff, Stefan; Blüm, P.; Braune, K.; Brose, J.; Bugg, D.V.; Case, T.; Cooper, Anthony R.; Cramer, O.; Crowe, K. M.; Degener, T.; Djaoshvili, N.; Dombrowski, S. von; Doser, M.; Dünnweber, W.; Engelhardt, D.; Faessler, M.; Giarritta, P.; Hackmann, R.; Haddock, R. P.; Heinsius, F. H.; Heinzelmann, Michael; Herz, M.; Hessey, N. P.; Hidas, P.; Hodd, C.; Holtzhaußen, C.; Jamnik, D.; Kalinowsky, H.; Kalteyer, B.; Kämmle, B.; Kammel, P.; Kiel, T.; Kisiel, J.; Klempt, E.; Koch, H.; Kolo, Castulus; Kunze, M.; Lakata, M.; Landua, R.; Lüdemann, J.; Matthäy, H.; McCrady, R.; Meier, J.; Meyer, C. A.; Montanet, L.; Ouared, R.; Ould-Saada, F.; Peters, K.; Pietra, C.; Pinder, C. N.; Pintér, G.; Regenfus, C.; Reißmann, J.; Resag, S.; Roethel, W.; Schmidt, P.; Scott, I.; Seibert, R.; Spanier, S.; Stöck, H.; Straßburger, C.; Strohbusch, U.; Suffert, M.; Thoma, U.; Tischhäuser, M.; Urner, D.; Völcker, C.; Frank, Werner; Walther, Dirk; Wiedner, U.; Zou, B. S.

doi:10.1016/s0370-2693(97)00479-6

Cited by 45 publications

(40 citation statements)

References 24 publications

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“…The η-η ′ mixing angle, as given in (40), is in agreement with most of experimental data which concentrate around −20 o [4,5,6]. Also, the values for f 8 /f π , f 9 /f π and θ are consistent with those suggested in the literature, as we show in Table I.…”

Section: The Schwinger and Sakurai Formulae Reexaminedsupporting

confidence: 91%

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New mass and mass-mixing angle relations for pseudoscalar mesons

Burakovsky

Goldman

1998

Physics Letters B

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We study the origins of the inaccuracies of Schwinger's nonet mass, and the Sakurai mass-mixing angle, formulae for the pseudoscalar meson nonet, and suggest new versions of them, modified by the inclusion of the pseudoscalar decay constants. We use these new formulae to determine the pseudoscalar decay constants and mixing angle. The results obtained, f 8 /f π = 1.185± 0.040, f 9 /f π = 1.095 ± 0.020, f η /f π = 1.085 ± 0.025, f η ′ /f π = 1.195 ± 0.035, θ = (−21.4 ± 1.0) o , are in excellent agreement with experiment.

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Section: The Schwinger and Sakurai Formulae Reexaminedsupporting

confidence: 91%

“…However, for the pseudoscalar nonet, one obtains from Eq. (5) with meson masses squared, θ ≈ −11 o , in sharp disagreement with experiment, which favors the η-η ′ mixing angle in the vicinity of −20 o [4,5,6]. Although using linear meson masses in Eq.…”

Section: Introductionmentioning

confidence: 88%

New mass and mass-mixing angle relations for pseudoscalar mesons

Burakovsky

Goldman

1998

Physics Letters B

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“…Previous results on the radiative decay for the η meson from WASA-at-COSY [3] and KLOE [4] would profit from further measurements. Only one measurement exists for the η radiative decay [5]. With the CLAS g11 experiment, both the η and η radiative decay width will be measured.…”

Section: The Radiative Decay Of the η And η Mesonmentioning

confidence: 99%

Light meson decays from photon-induced reactions with CLAS

Kunkel

2016

EPJ Web Conf.

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Abstract. Photoproduction experiments with the CEBAF Large Acceptance Spectrometer CLAS at the Thomas Jefferson National Facility produce data sets with competitive statistics of light mesons. With these data sets, measurements of transition form factors for η, ω, and η mesons via conversion decays can be performed using the invariant mass distribution of the final state dileptons. Tests of fundamental symmetries and information on the light quark mass difference can be performed using a Dalitz plot analysis of the meson decay. An overview of preliminary results, from existing CLAS data, and future prospects within the newly upgraded CLAS12 apparatus are given.

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“…Indeed, what has been fit is not the branching fraction given in Ref. [30], but the corresponding coupling constant which has been extracted by the Crystal Barrel Collaboration in [60]. The reason for this is that the (published) branching fraction for η ′ → ρ 0 γ is influenced by the box anomaly [5,15,17,20,21] for the vertex η ′ π + π − γ which is not accounted for in the VMD model of [10] ; actually this process contributes to the χ 2 for only ≃ 0.5.…”

Section: Estimates For Branching Fractions From Fitsmentioning

confidence: 99%

Radiative Decays, Nonet Symmetry and SU(3) Breaking

O'Connell¹

1999

Self Cite

143

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We re-examine the problem of simultaneously describing in a consistent way all radiative and leptonic decays of light mesons (V → P γ, P → V γ, P → γγ, V → e + e − ). For this purpose, we rely on the Hidden Local Symmetry model in both its anomalous and non-anomalous sectors. We show that the SU(3) symmetry breaking scheme proposed by Bando, Kugo and Yamawaki, supplemented with nonet symmetry breaking in the pseudoscalar sector, allows one to reach a nice agreement with all data, except for the K * ± radiative decay. An extension of this breaking pattern allows one to account for this particular decay mode too. Considered together, the whole set of radiative decays provides a pseudoscalar mixing angle θ P ≃ −11 • and a value for θ V which is ≃ 3 • from that of ideal mixing. We also show that it is impossible, in a practical sense, to disentangle the effects of nonet symmetry breaking and those of glue inside the η ′ , using only light meson decays. * Work supported by Department of Energy contract DE-AC03-76SF00515.When in doubt, tell the truth . . . Mark Twain I. INTRODUCTION.Defining an accurate framework in which the study of all radiative decays of light flavor mesons can be performed successfully is a long standing question. There are a few kinds of different models which have been proposed so far. The most popular modelling is in terms of magnetic moments of quarks [1,2]. It includes, to some extent, SU(3) breaking effects by having a magnetic moment for the s quark, slightly different to that of the d quark. It also depends on overlap integrals which are hard to estimate theoretically, and are thus arbitrarily chosen equal [3]. This, at least, allows one to have a reasonable number of free parameters. Another traditional approach is to use SU(3) relations among coupling constants [4]. However, the assumption of exact SU(3) symmetry still yields reasonable descriptions of radiative decays [5], though the success is never complete.Recently, several models including SU(3) symmetry breaking effects have been proposed [6-8], motivated in part by effective Lagrangian approaches to the interactions of vector mesons [9,10], sometimes with additional SU(2) symmetry breaking effects [7]. Including SU(3) symmetry breaking as per Bando, Kugo and Yamawaki (hereafter referred to as BKY) [11,12], these models give a special role to all decay constants (f K , f η , f η ′ ) in the breaking procedure; some additional corrections are also allowed. More recently, a new kind of model has been proposed [13], where additional symmetry breaking effects are introduced by means of the (measured) leptonic decay constants of vector mesons.The study of radiative decays of light flavor mesons is also connected with the long standing problem of η/η ′ mixing [5,8,[14][15][16][17] and to its possible association with a glue content [13,18]. The two-photon decay of the η(η ′ ) is also connected with the problem of anomalies [18][19][20][21]. Recent developments seem to advocate a more complicated η/η ′ mixing scheme [22,23], which has rece...

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Measurement of the decay distribution of η′ → π+π−γ and evidence for the box anomaly

Cited by 45 publications

References 24 publications

New mass and mass-mixing angle relations for pseudoscalar mesons

New mass and mass-mixing angle relations for pseudoscalar mesons

Light meson decays from photon-induced reactions with CLAS

Radiative Decays, Nonet Symmetry and SU(3) Breaking

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