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arXiv · 1603.03257

Observation of $D^0\to ρ^0γ$ and search for $CP$ violation in radiative charm decays

Belle Collaboration·T. Nanut·A. Zupanc·I. Adachi·H. Aihara·S. Al Said·D. M. Asner·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·I. Badhrees·A. M. Bakich·V. Bansal·P. Behera·V. Bhardwaj·J. Biswal·A. Bondar·A. Bozek·M. Bračko·T. E. Browder·D. Červenkov·V. Chekelian·A. Chen·B. G. Cheon·R. Chistov·K. Cho·S. -K. Choi·Y. Choi·D. Cinabro·N. Dash·S. Di Carlo·D. Dutta·S. Eidelman·H. Farhat·J. E. Fast·T. Ferber·B. G. Fulsom·V. Gaur·N. Gabyshev·A. Garmash·R. Gillard·P. Goldenzweig·K. Hayasaka·H. Hayashii·W. -S. Hou·T. Iijima·K. Inami·G. Inguglia·A. Ishikawa·Y. Iwasaki·W. W. Jacobs·I. Jaegle·D. Joffe·K. K. Joo·T. Julius·A. B. Kaliyar·K. H. Kang·T. Kawasaki·D. Y. Kim·J. B. Kim·K. T. Kim·M. J. Kim·S. H. Kim·K. Kinoshita·P. Kodyš·P. Krokovny·T. Kuhr·R. Kulasiri·A. Kuzmin·Y. -J. Kwon·J. S. Lange·I. S. Lee·C. H. Li·L. Li·Y. Li·L. Li Gioi·J. Libby·D. Liventsev·M. Lubej·M. Masuda·T. Matsuda·D. Matvienko·K. Miyabayashi·H. Miyata·R. Mizuk·G. B. Mohanty·H. K. Moon·K. J. Nath·M. Nayak·N. K. Nisar·S. Nishida·S. Ogawa·S. Okuno·P. Pakhlov·G. Pakhlova·B. Pal·C. -S. Park·C. W. Park·H. Park
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Abstract

We report the first observation of the radiative charm decay $D^0 \to ρ^0 γ$ and the first search for $CP$ violation in decays $D^0 \to ρ^0 γ$, $ϕγ$, and $\overline{K}{}^{*0} γ$, using a data sample of 943 fb$^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching fraction is measured to be $\mathcal{B}(D^0 \to ρ^0 γ)=(1.77 \pm 0.30 \pm 0.07) \times 10^{-5}$, where the first uncertainty is statistical and the second is systematic. The obtained $CP$ asymmetries, $\mathcal{A}_{CP}(D^0 \to ρ^0 γ)=+0.056 \pm 0.152 \pm 0.006$, $\mathcal{A}_{CP}(D^0 \to ϕγ)=-0.094 \pm 0.066 \pm 0.001$, and $\mathcal{A}_{CP}(D^0 \to \overline{K}{}^{*0} γ)=-0.003 \pm 0.020 \pm 0.000$, are consistent with no $CP$ violation. We also present an improved measurement of the branching fractions $\mathcal{B}(D^0 \to ϕγ)=(2.76 \pm 0.19 \pm 0.10) \times 10^{-5}$ and $\mathcal{B}(D^0 \to \overline{K}{}^{*0} γ)=(4.66 \pm 0.21 \pm 0.21) \times 10^{-4}$.

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Belle Collaboration, T. Nanut, A. Zupanc, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, I. Badhrees, A. M. Bakich, V. Bansal, P. Behera, V. Bhardwaj, J. Biswal, A. Bondar, A. Bozek, M. Bračko, T. E. Browder, D. Červenkov, V. Chekelian, A. Chen, B. G. Cheon, R. Chistov, K. Cho, S. -K. Choi, Y. Choi, D. Cinabro, N. Dash, S. Di Carlo, D. Dutta, S. Eidelman, H. Farhat, J. E. Fast, T. Ferber, B. G. Fulsom, V. Gaur, N. Gabyshev, A. Garmash, R. Gillard, P. Goldenzweig, K. Hayasaka, H. Hayashii, W. -S. Hou, T. Iijima, K. Inami, G. Inguglia, A. Ishikawa, Y. Iwasaki, W. W. Jacobs, I. Jaegle, D. Joffe, K. K. Joo, T. Julius, A. B. Kaliyar, K. H. Kang, T. Kawasaki, D. Y. Kim, J. B. Kim, K. T. Kim, M. J. Kim, S. H. Kim, K. Kinoshita, P. Kodyš, P. Krokovny, T. Kuhr, R. Kulasiri, A. Kuzmin, Y. -J. Kwon, J. S. Lange, I. S. Lee, C. H. Li, L. Li, Y. Li, L. Li Gioi, J. Libby, D. Liventsev, M. Lubej, M. Masuda, T. Matsuda, D. Matvienko, K. Miyabayashi, H. Miyata, R. Mizuk, G. B. Mohanty, H. K. Moon, K. J. Nath, M. Nayak, N. K. Nisar, S. Nishida, S. Ogawa, S. Okuno, P. Pakhlov, G. Pakhlova, B. Pal, C. -S. Park, C. W. Park, H. Park. 2017-04-10. Observation of $D^0\to ρ^0γ$ and search for $CP$ violation in radiative charm decays. https://doi.org/10.1103/physrevlett.118.051801

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