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Improved measurements of the Dalitz decays ?/?? ??e+e-
(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
Based on a data sample of 10 billion J/? events collected with the BESIII detector, improved measurements of the Dalitz decays ?/????e+e- are performed, where the ? and ?? are produced through the radiative decays J/????/??. The branching fractions of ???e+e- and ????e+e- are measured to be (7.07±0.05±0.23)×10-3 and (4.83±0.07±0.14)×10-4, respectively. Within the single-pole model, the parameter of electromagnetic transition form factor for ???e+e- is determined to be ??=(0.749±0.027±0.007) GeV/c2. Within the multipole model, we extract the electromagnetic transition form factors for ????e+e- to be ???=(0.802±0.007±0.008) GeV/c2 and ???=(0.113±0.010±0.002) GeV/c2. The results are consistent with both theoretical predictions and previous measurements. The characteristic sizes of the interaction regions for the ? and ?? are calculated to be (0.645±0.023±0.007) fm and (0.596±0.005±0.006) fm, respectively. In addition, we search for the dark photon in ?/????e+e-, and the upper limits of the branching fractions as a function of the dark photon are given at 90% confidence level. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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.
Measurement of the absolute branching fraction of the three-body decay ? plus c ? ?0K+?0 and search for ? plus c ? nK+ ?0, ?0K+?0, and ?K+ ?0
(Amer Physical Soc, 2024) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Afedulidis, O.; Ai, X. C.; Aliberti, R.; Çetin, Serkant Ali
The Cabbibo-favored decay Lambda thorn c -> Xi 0K thorn pi 0 is studied for the first time using 6.1 fb-1 of e thorn 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 Lambda thorn c -> Xi 0K thorn pi 0 is measured to be o7.79 1.46 0.95 thorn x 10-3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Lambda thorn c -> Xi o1530 thorn 0K thorn is o5.99 1.04 0.32 thorn x 10-3, which is consistent with the previous result of o5.02 0.99 0.31 thorn x 10-3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Lambda thorn c -> nK thorn pi 0 is 7.1 x 10-4 at the 90% confidence level. The upper limits on the branching fractions of Lambda thorn c -> sigma 0K thorn pi 0 and Lambda K thorn pi 0 are also determined to be 1.8 x 10-3 and 2.0 x 10-3, respectively
Measurements of ? electromagnetic form factors in the timelike region using the untagged initial-state radiation technique
(Amer Physical Soc, 2024) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Afedulidis, O.; Ai, X. C.; Aliberti, R.; Çetin, Serkant Ali
The process e thorn e- -> sigma thorn sigma over bar - is studied from threshold up to 3.04 GeV=c2 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 sigma are measured in eleven sigma thorn sigma over bar - invariant mass intervals from threshold to 3.04 GeV=c2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J=psi ->sigma thorn sigma over bar - and psi o3686 thorn -> sigma thorn sigma over bar - are determined and the obtained results are consistent with the previous results of BESIII.
Measurements of Born cross sections for e+e- ? ?c+ ? ¯ c (2595)-+ c. c. and e+e- ? ?c+ ? ¯ c (2625)-+ c. c. at s =4918.0 and 4950.9 MeV
(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
Using e+e- collision data collected with the BESIII detector operating at the BEPCII collider, the Born cross sections of e+e-??c+?¯c(2595)-+c.c. and e+e-??c+?¯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-??c+?¯c(2625)-+c.c. are about 2-3 times greater than those of e+e-??c+?¯c(2595)-+c.c., providing the similar behavior as semileptonic decays of ?b0, but different behavior from that in the hadronic decays of ?b0. The Born cross sections are 15.6±3.1±0.9 pb and 29.4±3.7±2.7 pb for e+e-??c+?¯c(2595)-+c.c., and are 43.4±4.0±4.1 pb and 76.8±6.5±4.2 pb for e+e-??c+?¯c(2625)-+c.c. at s=4918.0 and 4950.9 MeV, respectively. Based on the polar angle distributions of the ?¯c(2625)- and ?c(2625)+, the form-factor ratios |GE|2+3|GM|2/|GC| are determined for e+e-??c+?¯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. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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.
Observation of ? (3686) ?3?
(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
Using (2.712±0.014)×109 ?(3686) events collected by the BESIII detector operating at the BEPCII collider, we report the first observation of ?(3686)?3? decay with a significance larger than 10?. The branching fraction of this decay is determined to be (1.46±0.05±0.17)×10-5, where the first uncertainty is statistical and the second is systematic. No significant structure is observed in the ?? invariant mass spectra. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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.
Observation of a Vector Charmoniumlike State at 4.7 GeV/c2 and Search for Zcs in e+e- ? K+ K- J/?
(Amer Physical Soc, 2023) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Afedulidis, O.; Ai, X. C.; Aliberti, R.; Çetin, Serkant Ali
Using data samples with an integrated luminosity of 5.85 fb(-1) collected at center-of-mass energies from 4.61 to 4.95 GeV with the BESIII detector operating at the BEPCII storage ring, we measure the cross section for the process e(+)e(-) -> K+ K- J/psi. A new resonance with a mass of M = 4708(-15)(+17) +/- 21 MeV/c(2) and a width of Gamma = 126(-23)(+27) +/-+/- 30 MeV is observed in the energy-dependent line shape of the e(+)e(-) -> K+ K- J/psi. cross section with a significance over 5 sigma. The K(+)J/psi system is also investigated to search for charged charmoniumlike states, but no significant Z(cs)(+) states are observed. Upper limits on the Born cross sections for e+e- -> K-Z(cs)(3985)(+)/K-Z(cs)(4000)(+) + c:c: with Z(cs)(3985)(+/-)/Z(cs)(4000)(+/-) -> K(+/-)J/psi are reported at 90% confidence levels. The ratio of branching fractions {[B(Z(cs)(3985)(+) -> K+J/psi)]/B[Z(cs)(3985)(+) -> ((D) over bar D-0(s)*(+) + (D) over bar*D-0(s)+)]} is measured to be less than 0.03 at 90% confidence level.
Search for a massless particle beyond the Standard Model in the ?+???p?+?invisible decay
(Elsevier B.V., 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
A massless particle beyond the Standard Model is searched for in the two-body decay ?+?p+invisible using (1.0087±0.0044)×1010 J/? events collected at a center-of-mass energy of s=3.097GeV with the BESIII detector at the BEPCII collider. No significant signal is observed, and the upper limit on the branching fraction B(?+?p+invisible) is determined to be 3.2×10?5 at the 90% confidence level. This is the first search for a flavor-changing neutral current process with missing energy in hyperon decays which plays an important role in constraining new physics models. © 2024 The Author(s)
Search for a muonphilic scalar X0 or vector X1 via J/? ? ?+?- + invisible decays at BESIII
(Amer Physical Soc, 2024) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Afedulidis, O.; Ai, X. C.; Aliberti, R.; Çetin, Serkant Ali
A light scalar X-0 or vector X-1 particles have been introduced as a possible explanation for the (g - 2)(mu) anomaly and dark matter phenomena. Using (8.998 +/- 0.039) x 10(9) J=psi events collected by the BESIII detector, we search for a light muon philic scalar X-0 or vector X-1 in the processes J=psi -> mu(+)mu X--(0,1) with X-0,X-1 invisible decays. No obvious signal is found, and the upper limits on the coupling g'(0,1) between the muon and the X-0,X-1 particles are set to be between 1.1 x 10(-3) and 1.0 x 10(-2) for the X-0,X-1 mass in the range of 1 < M(X-0,X-1) < 1000 MeV=c(2) at 90% credibility level.
Search for D0 ? KS0 K-e+?e, D+ ? KS0 KS0 e+?e, and D+ ?k+K-e+?e
(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
A search has been performed for the semileptonic decays D0?KS0K-e+?e, D+?KS0KS0e+?e, and D+?K+K-e+?e, using 7.9 fb-1 of e+e- annihilation data collected at the center-of-mass energy s=3.773 GeV by the BESIII detector operating at the BEPCII collider. No significant signals are observed, and upper limits are set at the 90% confidence level of 2.13×10-5, 1.54×10-5, and 2.10×10-5 for the branching fractions of D0?KS0K-e+?e, D+?KS0KS0e+?e, and D+?K+K-e+?e, respectively. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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.
Study of hc?3 (?+?-)?0, hc?2 (?+?-)?, hc?2 (?+?-)?0?, hc?2 (?+?-)?, and hc?p p ¯
(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant Ali
Based on (2712.4±14.1)×106 ?(3686) events collected with the BESIII detector, we study the decays hc?3(?+?-)?0, hc?2(?+?-)?, hc?2(?+?-)?0?, hc?2(?+?-)?, and hc?pp¯ via ?(3686)??0hc. The decay channel hc?3(?+?-)?0 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(?+?-)?0? and hc?2(?+?-)? with significances of 4.8? and 4.7?, 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(?+?-)? 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. © 2024 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"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.

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