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arXiv · 1809.06496

Observation of $D^+ \to f_0(500) e^+ν_e$ and Improved Measurements of $D \toρe^+ν_e$

M. Ablikim·M. N. Achasov·S. Ahmed·M. Albrecht·M. Alekseev·A. Amoroso·F. F. An·Q. An·Y. Bai·O. Bakina·R. Baldini Ferroli·Y. Ban·K. Begzsuren·D. W. Bennett·J. V. Bennett·N. Berger·M. Bertani·D. Bettoni·F. Bianchi·E. Boger·I. Boyko·R. A. Briere·H. Cai·X. Cai·A. Calcaterra·G. F. Cao·S. A. Cetin·J. Chai·J. F. Chang·W. L. Chang·G. Chelkov·G. Chen·H. S. Chen·J. C. Chen·M. L. Chen·P. L. Chen·S. J. Chen·X. R. Chen·Y. B. Chen·W. Cheng·X. K. Chu·G. Cibinetto·F. Cossio·H. L. Dai·J. P. Dai·A. Dbeyssi·D. Dedovich·Z. Y. Deng·A. Denig·I. Denysenko·M. Destefanis·F. De Mori·Y. Ding·C. Dong·J. Dong·L. Y. Dong·M. Y. Dong·Z. L. Dou·S. X. Du·P. F. Duan·J. Fang·S. S. Fang·Y. Fang·R. Farinelli·L. Fava·S. Fegan·F. Feldbauer·G. Felici·C. Q. Feng·E. Fioravanti·M. Fritsch·C. D. Fu·Q. Gao·X. L. Gao·Y. Gao·Y. G. Gao·Z. Gao·B. Garillon·I. Garzia·A. Gilman·K. Goetzen·L. Gong·W. X. Gong·W. Gradl·M. Greco·L. M. Gu·M. H. Gu·Y. T. Gu·A. Q. Guo·L. B. Guo·R. P. Guo·Y. P. Guo·A. Guskov·Z. Haddadi·S. Han·X. Q. Hao·F. A. Harris·K. L. He·X. Q. He·F. H. Heinsius
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Abstract

Using a data sample corresponding to an integrated luminosity of 2.93~fb$^{-1}$ recorded by the BESIII detector at a center-of-mass energy of $3.773$ GeV, we present an analysis of the decays $\bar{D}^0\toπ^+π^0 e^-\barν_e$ and $D^+\toπ^-π^+ e^+ν_e$. By performing a partial wave analysis, the $π^+π^-$ $S$-wave contribution to $D^+\toπ^-π^+ e^+ν_e$ is observed to be $(25.7\pm1.6\pm1.1)$% with a statistical significance greater than 10$σ$, besides the dominant $P$-wave contribution. This is the first observation of the $S$-wave contribution. We measure the branching fractions $\mathcal{B}(D^{0} \to ρ^- e^+ ν_e) = (1.445\pm 0.058 \pm 0.039) \times10^{-3}$, $\mathcal{B}(D^{+} \to ρ^0 e^+ ν_e) = (1.860\pm 0.070 \pm 0.061) \times10^{-3}$, and $\mathcal{B}(D^{+} \to f_0(500) e^+ ν_e, f_0(500)\toπ^+π^-) = (6.30\pm 0.43 \pm 0.32) \times10^{-4}$. An upper limit of $\mathcal{B}(D^{+} \to f_0(980) e^+ ν_e, f_0(980)\toπ^+π^-) < 2.8 \times10^{-5}$ is set at the 90% confidence level. We also obtain the hadronic form factor ratios of $D\to ρe^+ν_e$ at $q^{2}=0$ assuming the single-pole dominance parameterization: $r_{V}=\frac{V(0)}{A_{1}(0)}=1.695\pm0.083\pm0.051$, $r_{2}=\frac{A_{2}(0)}{A_{1}(0)}=0.845\pm0.056\pm0.039$.

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M. Ablikim, M. N. Achasov, S. Ahmed, M. Albrecht, M. Alekseev, A. Amoroso, F. F. An, Q. An, Y. Bai, O. Bakina, R. Baldini Ferroli, Y. Ban, K. Begzsuren, D. W. Bennett, J. V. Bennett, N. Berger, M. Bertani, D. Bettoni, F. Bianchi, E. Boger, I. Boyko, R. A. Briere, H. Cai, X. Cai, A. Calcaterra, G. F. Cao, S. A. Cetin, J. Chai, J. F. Chang, W. L. Chang, G. Chelkov, G. Chen, H. S. Chen, J. C. Chen, M. L. Chen, P. L. Chen, S. J. Chen, X. R. Chen, Y. B. Chen, W. Cheng, X. K. Chu, G. Cibinetto, F. Cossio, H. L. Dai, J. P. Dai, A. Dbeyssi, D. Dedovich, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, Y. Ding, C. Dong, J. Dong, L. Y. Dong, M. Y. Dong, Z. L. Dou, S. X. Du, P. F. Duan, J. Fang, S. S. Fang, Y. Fang, R. Farinelli, L. Fava, S. Fegan, F. Feldbauer, G. Felici, C. Q. Feng, E. Fioravanti, M. Fritsch, C. D. Fu, Q. Gao, X. L. Gao, Y. Gao, Y. G. Gao, Z. Gao, B. Garillon, I. Garzia, A. Gilman, K. Goetzen, L. Gong, W. X. Gong, W. Gradl, M. Greco, L. M. Gu, M. H. Gu, Y. T. Gu, A. Q. Guo, L. B. Guo, R. P. Guo, Y. P. Guo, A. Guskov, Z. Haddadi, S. Han, X. Q. Hao, F. A. Harris, K. L. He, X. Q. He, F. H. Heinsius. 2019-02-20. Observation of $D^+ \to f_0(500) e^+ν_e$ and Improved Measurements of $D \toρe^+ν_e$. https://doi.org/10.1103/physrevlett.122.062001

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