Limits on leptonic photon interactions from SN 1987 a

If massless leptonic photons associated to electron, muon or tau leptonic number exist they would have been emitted from supernova 1987a via the annihilation process νν → γ l γ l. By requiring that this process does not carry away most of the energy that can be radiated by the supernova we obtain an upper limit on the leptonic photon coupling constants, α l < 5.4 × 10 −11. Under certain assumptions about γ l-trapping conditions we find that the region of α l = 10 −8 − 10 −7 might be of interest for an experimental search for leptonic photons. Recently, a few papers devoted to leptonic photons, first discussed by Okun in ref. [1], have been published [2, 3, 4, 5]. According to Okun [1, 2], it is assumed that if leptonic quantum numbers corresponding to the three lepton families (ν e , e), (ν µ , µ), (ν τ , τ) are strictly conserved these doublets could carry leptonic charges, which are sources of electronic, muonic and tauonic massless photons, respectively. Okun considered the various consequences of this hypothesis and discussed possible experiments which might indicate the existence of these new vector particles. In particular, he pointed out that the additional gauge symmetries connected with new leptonic photons would produce a problem of triangle anomalies, which need special attention. To avoid this problem an anomaly-free scheme was suggested in which a single leptonic photon γ l had the same coupling, but opposite sign to the (ν µ , µ) and (ν τ , τ) doublets and was decoupled from (ν e , e) [2]. From the existing experimental data on muon magnetic moment upper limit α l ≤ 10 −5 × α could be obtained, where α=1/137 is the fine structure constant (hereafter we assume that α l ≡ α µ ≡ α τ).