We present an analysis of the process e(+)e(-) -> pi(+)pi(-)Gamma(nS) (where n = 1, 2, or 3) reconstructed in 19.6 fb(-1) of Belle II data during a special run of the SuperKEKB collider at four energy points near the peak of the Gamma(10753) resonance. By analyzing the mass distribution of the pi(+)pi(-)Gamma(nS) system and the Born cross sections of the e(+)e(-) -> pi(+)pi(-)Gamma(nS) process, we report the first observation of Gamma(10753) decays to the pi(+)pi(-)Gamma(1S) and pi(+)pi(-)Gamma(2S) final states, and find no evidence for decays to pi(+)pi(-)Gamma(3S). Possible intermediate states in the pi(+)pi(-)Gamma(1S, 2S) transitions are also investigated, and no evidence for decays proceeding via the pi -/+ Zb +/- or f(0)(980)Gamma(nS) intermediate states is found. We measure Born cross sections for the e(+)e(-) -> pi(+)pi(-)Gamma(nS) process that, combined with results from Belle, obtain the mass and width of Gamma(10753) to be (10756.6 +/- 2.7 +/- 0.9) MeV/c(2) and (29.0 +/- 8.8 +/- 1.2) MeV, respectively. The relative ratios of the Born cross sections at the Gamma(10753) resonance peak are also reported for the first time.
Study of Υ(10753) decays to π+π−Υ(nS) final states at Belle II
Bettarini, S.;Casarosa, G.;Forti, F.;Massaccesi, L.;Rizzo, G.;Tenchini, F.;
2024-01-01
Abstract
We present an analysis of the process e(+)e(-) -> pi(+)pi(-)Gamma(nS) (where n = 1, 2, or 3) reconstructed in 19.6 fb(-1) of Belle II data during a special run of the SuperKEKB collider at four energy points near the peak of the Gamma(10753) resonance. By analyzing the mass distribution of the pi(+)pi(-)Gamma(nS) system and the Born cross sections of the e(+)e(-) -> pi(+)pi(-)Gamma(nS) process, we report the first observation of Gamma(10753) decays to the pi(+)pi(-)Gamma(1S) and pi(+)pi(-)Gamma(2S) final states, and find no evidence for decays to pi(+)pi(-)Gamma(3S). Possible intermediate states in the pi(+)pi(-)Gamma(1S, 2S) transitions are also investigated, and no evidence for decays proceeding via the pi -/+ Zb +/- or f(0)(980)Gamma(nS) intermediate states is found. We measure Born cross sections for the e(+)e(-) -> pi(+)pi(-)Gamma(nS) process that, combined with results from Belle, obtain the mass and width of Gamma(10753) to be (10756.6 +/- 2.7 +/- 0.9) MeV/c(2) and (29.0 +/- 8.8 +/- 1.2) MeV, respectively. The relative ratios of the Born cross sections at the Gamma(10753) resonance peak are also reported for the first time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.