We search for the di-photon decay of a light pseudoscalar axion-like particle, a, in radiative J/ψ decays, using 10 billion J/ψ events collected with the BESIII detector. We find no evidence of a signal and set upper limits at the 95% confidence level on the product branching fraction ℬ(J/ψ→γ a) ×ℬ(a →γγ) and the axion-like particle photon coupling constant g_a γγ in the ranges of (3.7-48.5) × 10^-8 and (2.2 -101.8)× 10^-4 GeV^-1, respectively, for 0.18 ≤ m_a ≤ 2.85 GeV/c^2. These are the most stringent limits to date in this mass region.

Based on (27.12±0.14)×108 ψ(2S) events collected by the BESIII detector, we search for the decay ηc(2S)→π+π−ηc via ψ(2S)→γηc(2S). No significant signal is observed, and the upper limit on the product branching fraction B(ψ(2S)→γηc(2S))×B(ηc(2S)→π+π−ηc) is determined to be 2.21×10−5 at the 90% confidence level. In addition, the ηc(2S)→π+π−KS0K±π∓ decay is studied via ψ(2S)→γηc(2S) and is observed with a statistical significance of 10σ for the first time. The branching fraction of ηc(2S)→π+π−KS0K±π∓ is determined to be (1.33±0.11±0.40±0.95)×10−2, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is due to the quoted B(ψ(2S)→γηc(2S)).Received 10 January 2024Accepted 21 March 2024DOI:https://doi.org/10.1103/PhysRevD.109.072017Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsQuantum electrodynamicsParticles & Fields

Based on a data sample of (2712.4±14.3)×106ψ(3686) events collected with the BESIII detector at the BEPCII collider, the M1 transition ψ(3686)→γηc(2S) with ηc(2S)→KK¯π is studied, where KK¯π is K+K−π0 or KS0K±π∓. The mass and width of the ηc(2S) are measured to be (3637.8±0.8(stat)±0.2(syst)) MeV/c2 and (10.5±1.7(stat)±3.5(syst)) MeV, respectively. The product branching fraction B(ψ(3686)→γηc(2S))×B(ηc(2S)→KK¯π) is determined to be (0.97±0.06(stat)±0.09(syst))×10−5. Using B(ηc(2S)→KK¯π)=(1.86−0.49+0.68)%, we obtain the branching fraction of the radiative transition to be B(ψ(3686)→γηc(2S))=(5.2±0.3(stat)±0.5(syst)−1.4+1.9(extr))×10−4, where the third uncertainty is due to the quoted B(ηc(2S)→KK¯π).Received 26 September 2023Accepted 8 January 2024DOI:https://doi.org/10.1103/PhysRevD.109.032004Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionLeptonic, semileptonic & radiative decaysQuark modelPhysical SystemsQuarkoniaParticles & Fields

Based on (10087±44)×10^{6} J/ψ events collected with the BESIII detector, a partial wave analysis of the decay J/ψ→γK_{S}^{0}K_{S}^{0}η^{'} is performed. The mass and width of the X(2370) are measured to be 2395±11(stat)_{-94}^{+26}(syst) MeV/c^{2} and 188_{-17}^{+18}(stat)_{-33}^{+124}(syst) MeV, respectively. The corresponding product branching fraction is B[J/ψ→γX(2370)]×B[X(2370)→f_{0}(980)η^{'}]×B[f_{0}(980)→K_{S}^{0}K_{S}^{0}]=(1.31±0.22(stat)_{-0.84}^{+2.85}(syst))×10^{-5}. The statistical significance of the X(2370) is greater than 11.7σ and the spin parity is determined to be 0^{-+} for the first time. The measured mass and spin parity of the X(2370) are consistent with the predictions of the lightest pseudoscalar glueball.

Six $C$-even states, denoted as $X$, with quantum numbers $J^{PC}=0^{-+}$, $1^{\pm+}$, or $2^{\pm+}$, are searched for via the $e^+e^-\to\gamma D_{s}^{\pm}D_{s}^{*\mp}$ process using $(1667.39\pm8.84)~\mathrm{pb}^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energy of $\sqrt{s}=(4681.92\pm0.30)~\mathrm{MeV}$. No statistically significant signal is observed in the mass range from $4.08$ to $4.32~\mathrm{GeV}/c^{2}$. The upper limits of $\sigma[e^+e^-\to\gamma X]\cdot \mathcal{B}[X \to D_{s}^{\pm}D_{s}^{*\mp}]$ at a $90\%$ confidence level are determined.

Based on (2712.4±14.1)×106 ψ(3686) events collected with the BESIII detector, we study the decays hc→3(π+π−)π0, hc→2(π+π−)ω, hc→2(π+π−)π0η, hc→2(π+π−)η, and hc→pp¯ via ψ(3686)→π0hc. The decay channel hc→3(π+π−)π0 is observed for the first time, and its branching fraction is determined to be (9.28±1.14±0.77)×10−3, where the first uncertainty is statistical and the second is systematic. In addition, first evidence is found for the modes hc→2(π+π−)π0η and hc→2(π+π−)ω with significances of 4.8σ and 4.7σ, and their branching fractions are determined to be (7.55±1.51±0.77)×10−3 and (4.00±0.86±0.35)×10−3, respectively. No significant signals of hc→2(π+π−)η and hc→pp¯ are observed, and the upper limits of the branching fractions of these decays are determined to be <6.19×10−4 and <4.40×10−5 at the 90% confidence level, respectively.Received 6 March 2024Accepted 4 April 2024DOI:https://doi.org/10.1103/PhysRevD.109.072018Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle decaysParticles & Fields

Using a data sample of e^+e^- collisions corresponding to an integrated luminosity of 7.93 fb^-1 collected with the BESIII detector at the center-of-mass energy 3.773 GeV, we perform the first amplitude analysis of the decay D^+→ K_S^0 K_S^0π^+. The absolute branching fraction of D^+→ K_S^0K_S^0π^+ is measured to be (2.97 ± 0.09_ stat.± 0.05_ syst.)×10^-3. The dominant intermediate process is D^+→ K_S^0K^*(892)^+, whose branching fraction is determined to be (8.72 ± 0.28_ stat.± 0.15_ syst.) × 10^-3, including all the K^*(892)^+ decays.

Using a sample of 10 billion J/ψ events collected with the BESIII detector, the decays η′→π+π−π+π−, η′→π+π−π0π0 and η′→4π0 are studied via the process J/ψ→γη′. The branching fractions of η′→π+π−π+π− and η′→π+π−π0 π0 are measured to be (8.56±0.25(stat)±0.23(syst))×10−5 and (2.12±0.12(stat)±0.10(syst))×10−4, respectively, which are consistent with previous measurements but with improved precision. No significant η′→4π0 signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than 1.24×10−5 at the 90% confidence level. In addition, an amplitude analysis of η′→π+π−π+π− is performed to extract the doubly virtual isovector form factor α for the first time. The measured value of α=1.22±0.33(stat)±0.04(syst), is in agreement with the prediction of the vector meson dominance model.Received 23 November 2023Accepted 23 January 2024DOI:https://doi.org/10.1103/PhysRevD.109.032006Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Physical SystemsLight mesonsPropertiesForm factorsParticles & Fields

Based on 4.5 fb−1 of e+e− collision data accumulated at center-of-mass energies between 4599.53 and 4698.82 MeV with the BESIII detector, we measure the absolute branching fraction of the Cabibbo-favored decay Λc+→nKS0π+ with the precision improved by a factor of 2.8 and report the first evidence for the singly-Cabibbo-suppressed decay Λc+→nKS0K+. The branching fractions for Λc+→nKS0π+ and Λc+→nKS0K+ are determined to be (1.86±0.08±0.04)×10−2 and (3.9−1.4+1.7±0.3)×10−4, respectively, where the first uncertainties are statistical and the second ones are systematic.Received 30 November 2023Accepted 23 February 2024DOI:https://doi.org/10.1103/PhysRevD.109.072010Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionHadronic decaysPhysical SystemsCharmed baryonsNeutronsTechniquesLepton collidersAccelerators & BeamsParticles & FieldsStatistical Physics & ThermodynamicsNuclear Physics

Using e+e− collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of e+e−→Λc+Λ¯c(2595)−+c.c. and e+e−→Λc+Λ¯c(2625)−+c.c. are measured for the first time at center-of-mass energies of s=4918.0 and 4950.9 MeV. Nonzero cross sections are observed very close to the production threshold. The measured Born cross sections of e+e−→Λc+Λ¯c(2625)−+c.c. are about 2–3 times greater than those of e+e−→Λc+Λ¯c(2595)−+c.c., providing the similar behavior as semileptonic decays of Λb0, but different behavior from that in the hadronic decays of Λb0. The Born cross sections are 15.6±3.1±0.9 pb and 29.4±3.7±2.7 pb for e+e−→Λc+Λ¯c(2595)−+c.c., and are 43.4±4.0±4.1 pb and 76.8±6.5±4.2 pb for e+e−→Λc+Λ¯c(2625)−+c.c. at s=4918.0 and 4950.9 MeV, respectively. Based on the polar angle distributions of the Λ¯c(2625)− and Λc(2625)+, the form-factor ratios |GE|2+3|GM|2/|GC| are determined for e+e−→Λc+Λ¯c(2625)−+c.c. for the first time, which are 5.95±4.07±0.15 and 0.94±0.32±0.02 at s=4918.0 and 4950.9 MeV, respectively. All of these first uncertainties are statistical and second systematic. Published by the American Physical Society 2024

The Cabbibo-favored decay Λc+→Ξ0K+π0 is studied for the first time using 6.1 fb−1 of e+e− collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay Λc+→Ξ0K+π0 is measured to be (7.79±1.46±0.95)×10−3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Λc+→Ξ(1530)0K+ is (5.99±1.04±0.32)×10−3, which is consistent with the previous result of (5.02±0.99±0.31)×10−3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Λc+→nK+π0 is 7.1×10−4 at the 90% confidence level. The upper limits on the branching fractions of Λc+→Σ0K+π0 and ΛK+π0 are also determined to be 1.8×10−3 and 2.0×10−3, respectively.1 MoreReceived 7 November 2023Accepted 23 January 2024DOI:https://doi.org/10.1103/PhysRevD.109.052001Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHadronic decaysPhysical SystemsCharmed baryonsParticles & Fields

We measure the absolute branching fractions of semileptonic D^+_s decays via the e^+e^-→ D_s^*+D_s^*- process using e^+e^- collision data corresponding to an integrated luminosity of 10.64 fb^-1 collected by the BESIII detector at center-of-mass energies between 4.237 and 4.699 GeV. The branching fractions are ℬ(D_s^+→η e^+ν_e)=(2.35±0.11_ stat± 0.10_ syst)%, ℬ(D_s^+→η^' e^+ν_e)=(0.82±0.09_ stat± 0.04_ syst)%, ℬ(D_s^+→ϕ e^+ν_e)=(2.21±0.16_ stat± 0.11_ syst)%, ℬ(D_s^+→ f_0(980) e^+ν_e,f_0(980)→π^+π^-)=(0.15±0.02_ stat± 0.01_ syst)%, ℬ(D_s^+→ K^0 e^+ν_e)=(0.24±0.04_ stat± 0.01_ syst)%, and ℬ(D_s^+→ K^*0 e^+ν_e)=(0.19±0.03_ stat± 0.01_ syst)%. These results are consistent with those measured via the e^+e^-→ D_s^*±D_s^∓ process by BESIII and CLEO. The hadronic transition form factors D^+_s→η e^+ν_e, D^+_s→η^' e^+ν_e, and D^+_s→ K^0 e^+ν_e at four-momentum transfer squared q^2 = 0 are determined to be f^η_+(0) = 0.482 ± 0.011_ stat± 0.009_ syst±0.004_ input, f^η^'_+(0) = 0.562 ± 0.031_ stat± 0.014_ syst±0.003_ input, and f^K^0_+(0) = 0.624 ± 0.052_ stat± 0.013_ syst±0.002_ input.

Using data samples of e+e− collisions collected with the BESIII detector at eight center-of-mass energy points between 3.49 and 3.67 GeV, corresponding to an integrated luminosity of 670 pb−1, we present the upper limits of Born cross sections and the effective form factor for the process e+e−→Ω−¯Ω+. A fit to the cross sections using a perturbative QCD-derived energy-dependent function shows no significant threshold effect. The upper limit on the measured effective form factor is consistent with a theoretical prediction within the uncertainty of 1σ. These results provide new experimental information on the production mechanism of Ω.Received 7 December 2022Accepted 5 January 2023DOI:https://doi.org/10.1103/PhysRevD.107.052003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Particle interactionsResearch AreasParticle phenomenaParticle interactionsResearch AreasForm factorsParticle interactionsTotal cross sectionsParticles & Fields

Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, the Born cross section of the process e+e- -> eta J=psi at a center-of-mass energy pffisffi = 3.773 GeV is measured to be (8.88 +/- 0.87 +/- 0.42) pb. We fit the cross section line shape before correcting for the initial state radiation ffiffifromps = 3.773 to 4.600 GeV to obtain the branching fraction B(psi(3770) -> eta J=psi). We obtain B(psi(3770) -> eta J=psi) = (11.3 +/- 5.9 +/- 1.1) x 10-4 when the psi(3770) decay amplitude is added coher-ently to the other contributions, and (8.7 +/- 1.0 +/- 0.8) x 10-4 when it is added incoherently. Here the quoted uncertainties are statistical and systematic, respectively. In both cases, the statistical significance of psi(3770) resonance is above 7 sigma. This is the first time the decay psi(3770) -> eta J=psi is observed with a statistical significance greater than 5 sigma.

Using $e^+e^-$ collision data corresponding to an integrated luminosity of 7.33 ${\rm fb^{-1}}$ recorded by the BESIII detector at center-of-mass energies between 4.128 and 4.226 ${\rm GeV}$, we present an analysis of the decay $D_{s}^{+} \to f_{0}(980)e^{+}\nu_{e}$ with $f_{0}(980) \to \pi^{+}\pi^{-}$, where the $D_s^+$ is produced via the process $e^+e^- \to D_{s}^{*\pm}D_{s}^{\mp}$. We observe the $f_{0}(980)$ in the $\pi^+\pi^-$ system and the branching fraction of the decay $D_{s}^{+} \to f_{0}(980)e^{+}\nu_{e}$ with $f_0(980)\to\pi^+\pi^-$ is measured to be $(1.72 \pm 0.13_{\rm stat} \pm 0.10_{\rm syst}) \times10^{-3}$, where the uncertainties are statistical and systematic, respectively. The dynamics of the $D_{s}^{+} \to f_{0}(980)e^{+}\nu_{e}$ decay are studied with the simple pole parameterization of the hadronic form factor and the Flatt\'e formula describing the $f_0(980)$ in the differential decay rate, and the product of the form factor $f^{f_0}_{+}(0)$ and the $c\to s$ Cabibbo-Kobayashi-Maskawa matrix element $|V_{cs}|$ is determined for the first time to be $f^{f_0}_+(0)|V_{cs}|=0.504\pm0.017_{\rm stat}\pm0.035_{\rm syst}$.

Based on a data sample of (10087±44)×106 J/ψ events collected with the BESIII detector, the branching fraction of J/ψ→Λ¯π+Σ−+c.c. is measured to be (1.221±0.002±0.038)×10−3, and the branching fraction of its isospin partner mode J/ψ→Λ¯π−Σ++c.c. is measured to be (1.244±0.002±0.045)×10−3 with improved precision. Here the first uncertainties are statistical and the second ones systematic. The isospin symmetry of the Σ baryon in charmonium hadronic decay and the “12% rule” are tested, and no violation is found. The potential of using these channels as Σ baryon sources for nuclear physics research is studied, and the momentum and angular distributions of these sources are provided.Received 21 June 2023Accepted 5 October 2023DOI:https://doi.org/10.1103/PhysRevD.108.112012Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasParticle interactionsPhysical SystemsHadronsParticles & Fields

We present the first experimental search for the rare charm decay ${D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\nu}\overline{\ensuremath{\nu}}$. It is based on an ${e}^{+}{e}^{\ensuremath{-}}$ collision sample consisting of $10.6\ifmmode\times\else\texttimes\fi{}{10}^{6}$ pairs of ${D}^{0}{\overline{D}}^{0}$ mesons collected by the BESIII detector at $\sqrt{s}=3.773\text{ }\text{ }\mathrm{GeV}$, corresponding to an integrated luminosity of $2.93\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. A data-driven method is used to ensure the reliability of the background modeling. No significant ${D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ signal is observed in data and an upper limit of the branching fraction is set to be $2.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ at the 90% confidence level. This is the first experimental constraint on charmed-hadron decays into dineutrino final states.

By analyzing $(448.1\ifmmode\pm\else\textpm\fi{}2.9)\ifmmode\times\else\texttimes\fi{}{10}^{6}\text{ }\text{ }\ensuremath{\psi}(3686)$ events collected with the BESIII detector operating at the BEPCII collider, the decays of ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\overline{\mathrm{\ensuremath{\Lambda}}}\ensuremath{\eta}$ ($J=0$, 1, and 2) are observed for the first time with statistical significances of $13.9\ensuremath{\sigma}$, $6.7\ensuremath{\sigma}$, and $8.2\ensuremath{\sigma}$, respectively. The product branching fractions of $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}$ and ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\overline{\mathrm{\ensuremath{\Lambda}}}\ensuremath{\eta}$ are measured. Dividing by the world averages of the branching fractions of $\ensuremath{\psi}(3686)\ensuremath{\rightarrow}\phantom{\rule{0ex}{0ex}}\ensuremath{\gamma}{\ensuremath{\chi}}_{cJ}$, the branching fractions of ${\ensuremath{\chi}}_{cJ}\ensuremath{\rightarrow}\mathrm{\ensuremath{\Lambda}}\overline{\mathrm{\ensuremath{\Lambda}}}\ensuremath{\eta}$ decays are determined to be $(2.31\ifmmode\pm\else\textpm\fi{}0.30\ifmmode\pm\else\textpm\fi{}0.21)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, $(5.86\ifmmode\pm\else\textpm\fi{}1.38\ifmmode\pm\else\textpm\fi{}0.68)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$, and $(1.05\ifmmode\pm\else\textpm\fi{}0.21\ifmmode\pm\else\textpm\fi{}0.15)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ for $J=0$, 1 and 2, respectively, where the first uncertainties are statistical and the second systematic.

We report the first measurements of the absolute branching fractions of $D^0\to K_L^0ϕ$, $D^0\to K_L^0η$, $D^0\to K_L^0ω$, and $D^0\to K_L^0η^{\prime}$, obtained by analyzing $2.93\,\rm fb^{-1}$ of $e^+e^-$ collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. Taking the world averages of the branching fractions of $D^0\to K_S^0ϕ$, $D^0\to K_S^0η$, $D^0\to K_S^0ω$, and $D^0\to K_S^0η^{\prime}$, the $K_S^0$-$K_L^0$ asymmetry $\mathcal{R}(D^0)$ in these decay modes are obtained. The CP asymmetries in these decays are also determined. No significant $CP$ violation is observed.

Abstract Using 448.1 × 106ψ(3686) decays collected with the BESIII detector at the BEPCII e+e− storage rings, the branching fractions and angular distributions of the decays χcJ→ Ξ−$$ \overline{\Xi} $$ Ξ ¯ + and Ξ0$$ \overline{\Xi} $$ Ξ ¯ 0 (J = 0, 1, 2) are measured based on a partial-reconstruction technique. The decays χc1→ Ξ0$$ \overline{\Xi} $$ Ξ ¯ 0 and χc2→ Ξ0$$ \overline{\Xi} $$ Ξ ¯ 0 are observed for the first time with statistical significances of 7σ and 15σ, respectively. The results of this analysis are in good agreement with previous measurements and have significantly improved precision.