Electromagnetic decays of light mesons

“…KLOE has started to study the decays of the η into four charged particles, using 1.7 fb −1 of data. This decay is interesting because it allows us to probe the η internal structure exploiting the conversion of the virtual photon into a lepton pair [12]. It is also interesting because a non-CKM CP violating mechanism has been suggest to be present in this decay [13], and should manifest as an angular asymmetry A φ , between the pion and the electron decay planes in the η rest frame.…”

Section: Pseudoscalar Physicsmentioning

confidence: 99%

Hadronic physics at KLOE

Versaci

2009

AIP Conference Proceedings

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Abstract. New KLOE results on scalar mesons, γγ physics and η physics are presented.Keywords: Scalar mesons, γγ physics, η meson. PACS: 13.25. Es, 13.25.Jx, 13.66.Bc, 14.40.Aq, 14.40.Cs SCALAR PHYSICSThe structure of the scalars below 1 GeV needs to be further clarified. Several models have been proposed to describe them (e.g. qq, four quarks, KK molecules, etc.). The decay of the scalars into two pseudoscalars (S → PP ′ ) can be used to investigate their nature because the branching ratios and the invariant mass of the two pseudoscalars are sensitive to the scalar structure.For this measurement about 400 pb −1 of KLOE collected data have been used. The analysis has been performed for two different η final states, i.e. η → γγ and η → π + π − π 0 . A kinematic fit has been performed imposing the four momentum conservation, the photon velocity and the invariant masses of both η and π 0 . The ηπ 0 invariant mass distribution has been fitted with the "no-structure" [2] and the "kaon loop"[3] models after background subtraction. The results of the fit are shown in table 1. It is interesting to note that both models give a large coupling of the a 0 (980) with the φ meson, indicating a sizable strange quark content in the a 0 (980). The branching ratio obtained for the two different decay chains are in agreement: BR(φ → ηπ 0 γ) = (7.01 ± 0.10 stat. ± 0.20 syst. ) × 10 −5 for the η → γγ final state and BR(φ → ηπ 0 γ) = (7.12 ± 0.13 stat. ± 0.22 syst. ) × 10 −5 for the η → π + π − π 0 final state. [4]. This decay allegedly proceeds through the intermediateThe kaon pair is produced in a J PC = 0 ++ state, so the two kaons are both K S or K L . We have searched for a final state with a K S K S , with both K S ' decaying to π + π − . This request

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“…In addition, we compare our results to similar approaches from the literature, namely to the VectorMeson Dominance (VMD) correlator [11,[14][15][16] …”

Section: Two-hadron Saturation For the Pvv Correlatormentioning

confidence: 99%

Decays of neutral pions: Electromagnetic transition form factor and radiative corrections

Husek

2017

EPJ Web Conf.

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Abstract. We briefly summarize experimental and theoretical results on the rare decay π 0 → e + e − . The notorious 3.3 σ discrepancy between the Standard Model prediction and the experimental value provided by KTeV collaboration is discussed in the view of a complete set of next-to-leading-order QED radiative corrections. We also present the Two-Hadron Saturation (THS) scenario for the PVV correlator and apply it to the decay under discussion. The discrepancy under discussion then reduces down to 1.8 σ. Finally, we turn our attention the the Dalitz decay π 0 → e + e − γ. We have recalculated the Mikaelian and Smith radiative corrections beyond the soft-photon approximation, i.e. over the whole range of the Dalitz plot and with no restrictions on the radiative photon. In contrast to the previous calculations, we also included the one-photon irreducible contribution at one-loop level. Our results can be also used for a further treatment of the processes with heavier particles in the final state.

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Electromagnetic decays of light mesons

Cited by 430 publications

References 79 publications

Enhanced Production of Direct Photons inAu+AuCollisions atsNN=200 GeVand Imp

Enhanced Production of Direct Photons inAu+AuCollisions atsNN=200 GeVand Imp

Hadronic physics at KLOE

Decays of neutral pions: Electromagnetic transition form factor and radiative corrections

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