TopoAna: A generic tool for the event type analysis of inclusive Monte-Carlo samples in high energy physics experiments

Using 10.1 × 109J/ψ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy $$ \sqrt{s} $$ s = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(J/ψ → D−e+νe + c. c.) < 7.1 × 10−8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.

Section: Event Selection and Data Analysismentioning

confidence: 56%

Search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c.

Ablikim

Ачасов

Adlarson

et al. 2021

“…These requirements can also suppress backgrounds from D * + decays, for which the momentum of pions from D * + is low. No peaking backgrounds are found in M (ΛK − ), M (Σ 0 K − ), and M (Σ + K 0 S ) distributions from generic simulated samples [47].…”

Section: Jhep06(2021)160mentioning

confidence: 85%

Measurements of branching fractions and asymmetry parameters of $$ {\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0} $$, $$ {\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0} $$, and $$ {\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -} $$ decays at Belle

Jia¹,

Tang²,

Shen³

et al. 2021

Using a data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric-energy e+e− collider, we study the processes of $$ {\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0} $$ Ξ c 0 → Λ K ¯ ∗ 0 , $$ {\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0} $$ Ξ c 0 → Σ 0 K ¯ ∗ 0 , and $$ {\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -} $$ Ξ c 0 → Σ + K ∗ − for the first time. The relative branching ratios to the normalization mode of $$ {\Xi}_c^0\to {\Xi}^{-}{\pi}^{+} $$ Ξ c 0 → Ξ − π + are measured to be$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.18\pm 0.02\left(\mathrm{stat}.\right)\pm 0.01\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.69\pm 0.03\left(\mathrm{stat}.\right)\pm 0.03\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.34\pm 0.06\left(\mathrm{stat}.\right)\pm 0.02\left(\mathrm{syst}.\right),\end{array}} $$ B Ξ c 0 → Λ K ¯ ∗ 0 / B Ξ c 0 → Ξ − π + = 0.18 ± 0.02 stat . ± 0.01 syst . , B Ξ c 0 → Σ 0 K ¯ ∗ 0 / B Ξ c 0 → Ξ − π + = 0.69 ± 0.03 stat . ± 0.03 syst . , B Ξ c 0 → Σ + K ∗ − / B Ξ c 0 → Ξ − π + = 0.34 ± 0.06 stat . ± 0.02 syst . , where the uncertainties are statistical and systematic, respectively. We obtain$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)=\left(3.3\pm 0.3\left(\mathrm{stat}.\right)\pm 0.2\left(\mathrm{syst}.\right)\pm 1.0\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}\right)=\left(12.4\pm 0.5\left(\mathrm{stat}.\right)\pm 0.5\left(\mathrm{syst}.\right)\pm 3.6\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast 0}\right)=\left(6.1\pm 1.0\left(\mathrm{stat}.\right)\pm 0.4\left(\mathrm{syst}.\right)\pm 1.8\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\end{array}} $$ B Ξ c 0 → Λ K ¯ ∗ 0 = 3.3 ± 0.3 stat . ± 0.2 syst . ± 1.0 ref . × 10 − 3 , B Ξ c 0 → Σ 0 K ¯ ∗ 0 = 12.4 ± 0.5 stat . ± 0.5 syst . ± 3.6 ref . × 10 − 3 , B Ξ c 0 → Σ + K ∗ 0 = 6.1 ± 1.0 stat . ± 0.4 syst . ± 1.8 ref . × 10 − 3 , where the uncertainties are statistical, systematic, and from $$ \mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right) $$ B Ξ c 0 → Ξ − π + , respectively. The asymmetry parameters $$ \alpha \left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right) $$ α Ξ c 0 → Λ K ¯ ∗ 0 and $$ \alpha \left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}\right) $$ α Ξ c 0 → Σ + K ∗ − are 0.15 ± 0.22(stat.) ± 0.04(syst.) and −0.52 ± 0.30(stat.) ± 0.02(syst.), respectively, where the uncertainties are statistical followed by systematic.

“…For the decay χ cJ → nK 0 S Λ + c.c., a special generator based on results of Helicity Partial Wave Analysis (HelPWA) [23][24][25] is used (see appendix A). The background MC samples are obtained from inclusive MC samples, in which the signal channels are removed with TopoAna [26], and the samples are normalized to the data sample based on luminosity.…”

Section: Detector and Data Setsmentioning

confidence: 99%

“…By analyzing the ψ(3686) inclusive MC samples with TopoAna [26], the only significant peaking background is found to be caused by the decays χ cJ → Σ ± Λπ ∓ + c.c. with Σ ± → nπ ± .…”

Section: Event Selection and Background Analysismentioning

confidence: 99%

Observation of the decays χcJ → $$ {\mathrm{nK}}_{\mathrm{S}}^0\overline{\Lambda} $$ + c.c.

Ablikim¹,

Ачасов²,

Adlarson³

et al. 2021

By analyzing 4.48 × 108ψ(3686) events collected with the BESIII detector, we observe the decays χcJ → $$ {nK}_S^0\overline{\Lambda} $$ nK S 0 Λ ¯ + c.c. (J = 0, 1, 2) for the first time, via the radiative transition ψ(3686) → γχcJ. The branching fractions are determined to be (6.65 ± 0.26stat ± 0.41syst) × 10−4, (1.66 ± 0.12stat ± 0.12syst) × 10−4, and (3.58 ± 0.16stat ± 0.23syst) × 10−4 for J = 0, 1, and 2, respectively.