Measurement of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi></mml:math>meson decays into lepton-antilepton pairs

Berłowski, M.; Bargholtz, Chr.; Bashkanov, M.; Bogoslawsky, D.; Bondar, A.; Calén, H.; Cappellaro, F.; Clement, H.; Demiroers, L.; Ekström, C.; Fransson, K.; Gerén, L.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, T.; Keleta, S.; Koch, I.; Kullander, S.; Kupść, A.; Kuzmin, A.; Кузнецов, А. А.; Laukhin, I. V.; Lindberg, K.; Marciniewski, P.; Meier, R.; Morosov, B.; Oelert, W.; Pauly, C.; Pettersson, Henrik; Petukhov, Y.; Povtorejko, A.; Ruber, Roger; Schönning, K.; Scobel, W.; Shafigullin, R.; Shwartz, B.; Skorodko, T.; Sopov, V.; Steṕaniak, J.; Tegnér, P. E.; Engblom, P. Thörngren; Tikhomirov, V.; Turowiecki, A.; Wagner, G. J.; Wolke, M.; Yamamoto, A.; Zabierowski, J.; Zartova, I.; Złomańczuk, J.

doi:10.1103/physrevd.77.032004

Cited by 45 publications

(18 citation statements)

References 30 publications

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“…Competitive constraints on axion hadronic mixing angles could be potentially obtained from dedicated analyses of existing data on other rare meson decays, such as K + → + ν a , K 0 L → ππa , K 0 S → π 0 a , and η, η → ππa . The relevant final states for these observables have been measured in high statistics samples [169][170][171][172][173][174][175][176][177][178][179][180][181], but, to the best of our knowledge, no dedicated searches for e + e − resonances in the few MeV invariant mass range have been performed.…”

Section: Other Constraintsmentioning

confidence: 99%

A viable QCD axion in the MeV mass range

Alves

Weiner

2018

J. High Energ. Phys.

120

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The QCD axion is one of the most compelling solutions of the strong CP problem. There are major current efforts into searching for an ultralight, invisible axion, which is believed to be the only phenomenologically viable realization of the QCD axion. Visible axions with decay constants at or below the electroweak scale are believed to have been long excluded by laboratory searches.Considering the significance of the axion solution to the strong CP problem, we revisit experimental constraints on QCD axions in the O(10 MeV) mass window. In particular, we find a variant axion model that remains compatible with existing constraints. This model predicts new states at the GeV scale coupled hadronically, and a variety of low-energy axion signatures, such as rare meson decays, nuclear de-excitations via axion emission, and production in e + e − annihilation and fixed target experiments. This reopens the possibility of solving the strong CP problem at the GeV scale.

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Section: Other Constraintsmentioning

confidence: 99%

A viable QCD axion in the MeV mass range

Alves

Weiner

2018

J. High Energ. Phys.

120

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“…The 4π geometry of the WASA-at-COSY detector and its availability to work with high luminosities makes it a suitable tool for such studies [13]. Already at the previous location of the WASA detector (see Sec.2.2) the studies on leptonic decays of the η meson were performed [14] leading to the branching ratio estimate for the η → e + e − γ decay 3 [15].…”

Section: Introductionmentioning

confidence: 99%

Study of theη→e⁺e⁻γDecay Using WASA-at-COSY Detector System

Hodana

Moskal

2012

EPJ Web of Conferences

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Abstract. At the turn of October and November 2008, the WASA-at-COSY collaboration performed an experiment to collect data on the η meson decays in pd → 3 He η reactions. This report presents results of a study of the η → e + e − γ conversion decay. The desired feature of this decay is that the final state e + e − pairs come from the conversion of a virtual γ quantum and, therefore, they constitute a rich source of knowledge about the electromagnetic structure of decaying meson. This is a very important characteristic when it comes to study of a short-lived neutral particle like the η meson, because the classical methods of particle scattering are not applicable here. The analysis performed on one third of the p-d data sample collected using the WASA-at-COSY detector, lead to the extraction of the η transition form factor as a function of the e + e − mass and to the calculation of the slope parameter, related to the charge radius of the η meson.

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“…The largest data samples to date consist of (1345 ± 59) and (2.2 × 10 4 ) events [17,18]. This channel was also measured in the pd → 3 He η reaction by the CELSIUS/WASA Collaboration with (435 ± 35) events collected [21].…”

Section: Normalizationmentioning

confidence: 99%

“…[17,[19][20][21]. The largest data samples to date consist of (1345 ± 59) and (2.2 × 10 4 ) events [17,18].…”

Section: Normalizationmentioning

confidence: 99%