Abstract
We re-examine the possibility to measure the photon polarization in B → K ∗γ decays, via decays in which the photon subsequently undergoes nuclear conversion to a lepton pair. We obtain compact expressions for the full decay-plus-conversion amplitude. With these results we show that interference between the B → (K ∗ → Kπ)γ decay and the γN → ℓ + ℓ − N conversion permits both the ratio and relative weak phase between the left- and right-handed photon amplitudes to be probed by an angular observable, constructed from the final state dilepton, kaon and pion kinematic configuration. Exploiting this technique will be experimentally challenging. However, we present special kinematic cuts that enhance the statistical power of this technique by an \( \mathcal{O}(1) \) factor. We verify this effect and extract pertinent angular kinematic distributions with dedicated numerical simulations.
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M. Gronau, Y. Grossman, D. Pirjol and A. Ryd, Measuring the photon polarization in B → Kππγ, Phys. Rev. Lett. 88 (2002) 051802 [hep-ph/0107254] [INSPIRE].
M. Gronau and D. Pirjol, Photon polarization in radiative B decays, Phys. Rev. D 66 (2002) 054008 [hep-ph/0205065] [INSPIRE].
LHCb collaboration, Observation of photon polarization in the b → sγ transition, Phys. Rev. Lett. 112 (2014) 161801 [arXiv:1402.6852] [INSPIRE].
T. Mannel and S. Recksiegel, Probing the helicity structure of b → sγ in Λ b → Λ γ , Acta Phys. Polon. B 28 (1997) 2489 [hep-ph/9710287] [INSPIRE].
G. Hiller and A. Kagan, Probing for new physics in polarized Λ b decays at the Z, Phys. Rev. D 65 (2002) 074038 [hep-ph/0108074] [INSPIRE].
D. Atwood, M. Gronau and A. Soni, Mixing induced CP asymmetries in radiative B decays in and beyond the standard model, Phys. Rev. Lett. 79 (1997) 185 [hep-ph/9704272] [INSPIRE].
F. Krüger, L.M. Sehgal, N. Sinha and R. Sinha, Angular distribution and CP asymmetries in the decays \( \overline{B}\to {K}^{-}{\pi}^{+}{e}^{-}{e}^{+} \) and \( \overline{B}\to {\pi}^{-}{\pi}^{+}{e}^{-}{e}^{+} \), Phys. Rev. D 61 (2000) 114028 [Erratum ibid. D 63 (2001) 019901] [hep-ph/9907386] [INSPIRE].
C.S. Kim, Y.G. Kim, C.-D. Lu and T. Morozumi, Azimuthal angle distribution in B → K ∗(→Kπ)ℓ + ℓ − at low invariant m ℓ+ℓ− region, Phys. Rev. D 62 (2000) 034013 [hep-ph/0001151] [INSPIRE].
D. Melikhov, N. Nikitin and S. Simula, Probing right-handed currents in B → K ∗ ℓ + ℓ − transitions, Phys. Lett. B 442 (1998) 381 [hep-ph/9807464] [INSPIRE].
Particle Data Group collaboration, K.A. Olive et al., Review of particle physics, Chin. Phys. C 38 (2014) 090001 [INSPIRE].
B. Grinstein, Y. Grossman, Z. Ligeti and D. Pirjol, The photon polarization in B → Xγ in the standard model, Phys. Rev. D 71 (2005) 011504 [hep-ph/0412019] [INSPIRE].
Y. Grossman and D. Pirjol, Extracting and using photon polarization information in radiative B decays, JHEP 06 (2000) 029 [hep-ph/0005069] [INSPIRE].
F. Bishara et al., Probing CP-violation in h → γγ with converted photons, JHEP 04 (2014) 084 [arXiv:1312.2955] [INSPIRE].
BaBar collaboration, D. Boutigny et al., BaBar technical design report, SLAC-R-0457, (1995) [INSPIRE].
LHCb collaboration, LHCb detector performance, Int. J. Mod. Phys. A 30 (2015) 1530022 [arXiv:1412.6352] [INSPIRE].
Belle-II collaboration, T. Abe et al., Belle II technical design report, arXiv:1011.0352 [INSPIRE].
D. Bernard, HARPO-A gaseous TPC for high angular resolution γ-ray astronomy and polarimetry from the MeV to the TeV, Nucl. Instrum. Meth. A 718 (2013) 395 [arXiv:1210.4399] [INSPIRE].
J.W. Motz, H.A. Olsen and H.W. Koch, Pair production by photons, Rev. Mod. Phys. 41 (1969) 581 [INSPIRE].
Y.-S. Tsai, Pair production and bremsstrahlung of charged leptons, Rev. Mod. Phys. 46 (1974) 815 [Erratum ibid. 49 (1977) 421] [INSPIRE].
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ArXiv ePrint: 1505.00376
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Bishara, F., Robinson, D.J. Probing the photon polarization in B → K ∗γ with conversion. J. High Energ. Phys. 2015, 13 (2015). https://doi.org/10.1007/JHEP09(2015)013
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DOI: https://doi.org/10.1007/JHEP09(2015)013