Amplitude Analysis of and

Physical Review D

We present the first observation of the singly Cabibbo-suppressed decay Λ c+→ Λ K+ π 0 with a significance of 5.7 σ and the first evidence of Λ c+→ Λ K+ π+ π− decay with a significance of 3.1 σ, based on e+ e− annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to an integrated luminosity of 6.4 fb− 1, in the center-of-mass energy range from 4.600 to 4.950 GeV. We determine the branching fractions of Λ c+→ Λ K+ π 0 and Λ c+→ Λ K+ π+ π− relative to their Cabibbo-favored counterparts to be B (Λ c+→ Λ K+ π 0) B (Λ c+→ Λ π+ π 0)=(2.09±0.3 9 stat±0.0 7 syst)× 10− 2 and B (Λ c+→ Λ K+ π+ π−) B (Λ c+→ Λ π+ π+ π−)=(1.13±0.4 1 stat±0.0 6 syst)× 10− 2, respectively. Moreover, by combining our measured result with the world average of B (Λ c+→ Λ π+ π 0), we obtain the branching fraction B (Λ c+→ Λ K+ π 0)=(1.49±0.2 7 stat±0.0 5 syst±0.0 8 ref)× 10− 3. This result …

arXiv preprint arXiv:2401.17873

Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process , normalized by the total cross section of , is measured at eight center-of-mass energy points from 2.0000 GeV to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy from calculations with the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well.

Physical Review D

The process e+ e−→ Σ+ Σ− is studied from threshold up to 3.04 GeV/c 2 via the initial-state radiation technique using data with an integrated luminosity of 12.0 fb− 1, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of Σ are measured in eleven Σ+ Σ− invariant mass intervals from threshold to 3.04 GeV/c 2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J/ψ→ Σ+ Σ− and ψ (3686)→ Σ+ Σ− are determined and the obtained results are consistent with the previous results of BESIII.

arXiv preprint arXiv:2404.13840

Using data samples with an integrated luminosity of collected by the BESIII detector at center-of-mass energies ranging from 4.66 to 4.95 GeV, we study the processes of and . With the process, the branching fraction ratio is measured to be ( at 90\% confidence level). In addition, we measure the ratio of the average cross section of to to be $\sigma_{\omega X(3872)}/\sigma_{\omega\chi_{c1}}~(\sigma_{\omega X(3872)}/\sigma_{\omega\chi_{c2}})=5.2\pm1.0_\text{stat.}\pm1.9_\text{syst.}~ (5.5\pm1.1_\text{stat.}\pm2.4_\text{syst.})$. Finally, we search for the process of , and no obvious signal is observed. The upper limit on the ratio of the average cross section of to is set as at 90\% confidence level.

arXiv preprint arXiv:2404.07436

The Born cross sections for the process are measured at 22 center-of-mass energies from 2.000 to 3.080 GeV using data collected with the BESIII detector at the BEPCII collider. A resonant structure is observed with a statistical significance of 9.6. A Breit-Wigner fit determines its mass to be and its width to be , where the first uncertainties are statistical and the second are systematic.

arXiv preprint arXiv:2403.06766

The number of events collected by the BESIII detector during the 2021 run period is determined to be by counting inclusive hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of events collected during the 2009 and 2012 run periods are updated to be and , respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of events in the three data samples is .

PHYSICAL REVIEW D

Using a sample of 10 billion J/psi events collected with the BESIII detector, the decays eta' -> pi())pi(-)pi())pi(-), eta' -> pi())pi(-)pi(0)pi(0 )and eta'-> 4 pi(0 )are studied via the process J/psi -> gamma eta'. The branching fractions of eta'->pi())pi(-)pi())pi(- )and eta'->pi())pi(-)pi(0)pi(0 )are measured to be(8.56 +/- 0.25(stat)+/- 0.23(syst))x10(-5 )and (2.12 +/- 0.12(stat)+/- 0.10(syst))x10(-4), respectively, which are consistent with previous measurements but with improved precision. No significant eta'-> 4 pi(0 )signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than 1.24x10(-5 )at the 90% confidence level. In addition, an amplitude analysis of eta'->pi)pi-pi)pi-is performed to extract the doubly virtual isovector form factor alpha for the first time. The measured value of alpha = 1.22 +/- 0.33(stat) +/- 0.04(syst), is in agreement with the prediction of the vector meson dominance model.

Journal of High Energy Physics

Based on e+ e− collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the process e+ e−→ π 0. The results allow the Born cross sections of the process e+ e−→ π 0, as well as its subprocesses e+ e−→ K∗(892) 0 0 and(1430) 0 0 to be measured. The Born cross sections for e+ e−→ π 0 are consistent with previous measurements by BaBar, but with substantially improved precision. The Born cross section lineshape of the process e+ e− K∗(892) 0 0 is consistent with a vector meson state around 2.2 GeV with a significance of 3.2σ. A Breit-Wigner fit determines its mass as M Y=(2164. 7±9. 1±3. 1) MeV/c 2 and its width as Γ Y=(32. 4±21. 0±1. 8) MeV.

Journal of High Energy Physics

Using (10087±44)× 10 6 J/ψ events collected with the BESIII detector at the BEPCII e+ e− storage ring at the center-of-mass energy of= 3.097 GeV, we present a search for the rare semi-muonic charmonium decay J/ψ→ D− μ+ ν μ+ cc. Since no significant signal is observed, we set an upper limit of the branching fraction to be(J/ψ→ D− μ+ ν μ+ cc)< 5.6× 10− 7 at 90% confidence level. This is the first search for the weak decay of charmonium with a muon in the final state.

arXiv preprint arXiv:2401.09225

The absolute branching fraction of the decay is measured for the first time to be with 368.48 pb of collision data collected by the BESIII detector at the center-of-mass energies of and GeV. This result is lower than the naive prediction of 67\%, obtained from isospin symmetry, by more than , thereby indicating that the novel mechanism referred to as the \textit{threshold effect}, proposed for the strong decays of , also applies to . This measurement is necessary to obtain the coupling constants for the transitions between -wave and -wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay . No significant signal is observed, and the upper limit on its branching fraction is determined to be 80.8\% at the 90\% confidence level.

Physical review letters

Using a sample of (10087±44)×10^{6} J/ψ events, which is about 45 times larger than that was previously analyzed, a further investigation on the J/ψ→γ3(π^{+}π^{-}) decay is performed. A significant distortion at 1.84 GeV/c^{2} in the line shape of the 3(π^{+}π^{-}) invariant mass spectrum is observed for the first time, which could be resolved by two overlapping resonant structures, X(1840) and X(1880). The new state X(1880) is observed with a statistical significance larger than 10σ. The mass and width of X(1880) are determined to be 1882.1±1.7±0.7 MeV/c^{2} and 30.7±5.5±2.4 MeV, respectively, which indicates the existence of a pp[over ¯] bound state.

PHYSICAL REVIEW D

Using a sample of 10 billion J/psi events collected with the BESIII detector, the decays eta' -> pi())pi(-)pi())pi(-), eta' -> pi())pi(-)pi(0)pi(0 )and eta'-> 4 pi(0 )are studied via the process J/psi -> gamma eta'. The branching fractions of eta'->pi())pi(-)pi())pi(- )and eta'->pi())pi(-)pi(0)pi(0 )are measured to be(8.56 +/- 0.25(stat)+/- 0.23(syst))x10(-5 )and (2.12 +/- 0.12(stat)+/- 0.10(syst))x10(-4), respectively, which are consistent with previous measurements but with improved precision. No significant eta'-> 4 pi(0 )signal is observed, and the upper limit on the branching fraction of this decay is determined to be less than 1.24x10(-5 )at the 90% confidence level. In addition, an amplitude analysis of eta'->pi)pi-pi)pi-is performed to extract the doubly virtual isovector form factor alpha for the first time. The measured value of alpha = 1.22 +/- 0.33(stat) +/- 0.04(syst), is in agreement with the prediction of the vector meson dominance model.

Physical Review D

Using E1 radiative transitions ψ (3686)→ γ χ c J from a sample of (448.1±2.9)× 10 6 ψ (3686) events collected with the BESIII detector, the decays χ c J→ Σ+ p K S 0+ c. c.(J= 0, 1, 2) are studied. The decay branching fractions are measured to be B (χ c 0→ Σ+ p K S 0+ c. c.)=(3.52±0.19±0.21)× 10− 4, B (χ c 1→ Σ+ p K S 0+ c. c.)=(1.53±0.10±0.08)× 10− 4, and B (χ c 2→ Σ+ p K S 0+ c. c.)=(8.25±0.83±0.49)× 10− 5, where the first and second uncertainties are the statistical and systematic ones, respectively. No evident intermediate resonances are observed in the studied processes.

arXiv preprint arXiv:2401.08252

Using events collected with the BESIII detector at BEPCII, the decay of is observed for the first time. The branching fraction of this decay is measured to be $\mathcal{B}_{\psi(3686) \to \Omega^- K^+ \bar{\Xi}^0 +c.c.}=(2.78 \pm 0.40 \pm 0.18 ) \times 10^{-6}$, where the first uncertainty is statistical and the second is systematic. Possible baryon excited states are searched for in this decay, but no evident intermediate state is observed with the current sample size.

arXiv preprint arXiv:2402.11207

Using a data sample of collision data corresponding to an integrated luminosity of 19 fb collected with the BESIII detector at the BEPCII collider, we search for the production of deuterons and antideuterons via for the first time at center-of-mass energies between 4.13 and 4.70 GeV. No significant signal is observed and the upper limit of the cross section is determined to be from 9.0 to 145 fb depending on the center-of-mass energy at the confidence level.

Very recently, the Large High Altitude Air Shower Observatory (LHAASO) reported the observation of the very early TeV afterglow of the brightest-of-all-time GRB 221009A, recording the highest photon statistics in the TeV band ever from a gamma-ray burst. We use this unique observation to place stringent constraints on an energy dependence of the speed of light in vacuum, a manifestation of Lorentz invariance violation (LIV) predicted by some quantum gravity (QG) theories. Our results show that the 95% confidence level lower limits on the QG energy scales are times of the Planck energy for the linear, and for the quadratic LIV effects, respectively. Our limits on the quadratic LIV case improve previous best bounds by factors of 5--7.

arXiv preprint arXiv:2403.06766

The number of events collected by the BESIII detector during the 2021 run period is determined to be by counting inclusive hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of events collected during the 2009 and 2012 run periods are updated to be and , respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of events in the three data samples is .

Physical Review Letters

Using a data sample of e+ e− collisions corresponding to an integrated luminosity of 567 pb− 1 collected at a center-of-mass energy of s= 4.6 GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic Λ c+ decay with a double-tag method. We obtain B (Λ c+→ X e+ ν e)=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λ c+ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D 0 and D+), we obtain the ratio of the inclusive semileptonic decay widths Γ (Λ c+→ X e+ ν e)/Γ (D→ X e+ ν e)= 1.26±0.12.

Physical Review D

With a data sample corresponding to an integrated luminosity of 11.5 fb− 1 collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay χ c 1 (3872)→ π+ π− η is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for σ [e+ e−→ γ χ c 1 (3872)] B [χ c 1 (3872)→ π+ π− η] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the χ c 1 (3872)→ π+ π− J/ψ decay channel, a 90% confidence level upper limit for the branching fraction ratio R= B [χ c 1 (3872)→ π+ π− η]/B [χ c 1 (3872)→ π+ π− J/ψ]< 0.12 is given. These measurements provide important inputs for understanding the internal structure of the χ c 1 (3872) resonance.

Physical Review D

Using a data sample of (10087±44)× 10 6 J/ψ events collected by the BESIII detector in 2009, 2012, 2018 and 2019, the electromagnetic Dalitz process J/ψ→ e+ e− η (1405) is observed via the decay η (1405)→ π 0 f 0 (980), f 0 (980)→ π+ π−, with a significance of about 9.8 σ. The branching fraction of this decay is measured to be B (J/ψ→ e+ e− η (1405)→ e+ e− π 0 f 0 (980)→ e+ e− π 0 π+ π−)=(2.04±0.20 (stat)±0.08 (syst))× 10− 7. The branching fraction ratio B (J/ψ→ e+ e− η (1405))/B (J/ψ→ γ η (1405)) is determined to be (1.36±0.17 (stat)±0.06 (syst))× 10− 2. Furthermore, an e+ e− invariant mass dependent transition form factor of J/ψ→ e+ e− η (1405) is presented for the first time. The obtained result provides input for different theoretical models and is valuable for the improved understanding the intrinsic structure of the η (1405) meson.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.

arXiv preprint arXiv:2312.02524

Using annihilation data corresponding to an integrated luminosity of 2.93 taken at the center-of-mass energy ~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays and (non-). The fit fractions of individual components are obtained, and large interferences among the dominant components of , , and are found in both channels. With the obtained amplitude model, the -even fractions of and (non-) are determined to be and , respectively. The branching fractions of and (non-) are measured to be and , respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of when used to determine the CKM angle via the decay.