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Öğe Improved measurement of the decays ?? ??+?-?+ (0)?- (0) and search for the rare decay ?? ?4?0(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliUsing a sample of 10 billion J/? events collected with the BESIII detector, the decays ????+?-?+?-, ????+?-?0?0 and ???4?0 are studied via the process J/?????. The branching fractions of ????+?-?+?- and ????+?-?0 ?0 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 ???4?0 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 ????+?-?+?- is performed to extract the doubly virtual isovector form factor ? for the first time. The measured value of ?=1.22±0.33(stat)±0.04(syst), is in agreement with the prediction of the vector meson dominance model. © 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.Öğe 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 AliBased 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.Öğe Measurement of branching fractions for ?c+ ?n KS0 ?+ and ?c+ ?n KS0 K+(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliBased 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 ?c+?nKS0?+ with the precision improved by a factor of 2.8 and report the first evidence for the singly-Cabibbo-suppressed decay ?c+?nKS0K+. The branching fractions for ?c+?nKS0?+ and ?c+?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. © 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.Öğe Measurement of the cross sections for e+e- ???+?- at center-of-mass energies between 2.00 and 3.08 GeV(American Physical Society, 2023) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliUsing data samples collected at center-of-mass energies between 2.000 and 3.080 GeV with the BESIII detector operating at the BEPCII collider, a partial-wave analysis is performed on the process e+e-???+?-. In addition to the dominant e+e-??? component, the e+e-?a2(1320)? process is also sizable, contributing up to 24% of the total reaction. The measured cross sections of the process e+e-???+?- are systematically higher than those of BABAR by more than 3? at center-of-mass energies between 2.000 and 2.300 GeV. In the cross section line shape for e+e-?a2(1320)?, a resonant structure is observed with a significance of 5.5?, with M=(2044±31±4) MeV/c2, ?=(163±69±24) MeV, and BR·?e+e-R=(34.6±17.1±6.0) eV or (137.1±73.3±2.1) eV. In the cross section line shape for e+e-???, an evidence of a dip structure around 2180 MeV/c2 is observed with statistical significance of 3.0?. © 2023 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.Öğe 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 AliUsing 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.Öğe Observation of ? (3686) ?3?(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Afedulidis, O.; Ai, X.C.; Aliberti, R.; Çetin, Serkant AliUsing (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.Öğe Observation of D+ ? KS0 a0 (980)+ in the Amplitude Analysis of D+ ? KS0 ?+?(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliWe perform for the first time an amplitude analysis of the decay D+?KS0?+? and report the observation of the decay D+?KS0a0(980)+ using 2.93 fb-1 of e+e- collision data taken at a center-of-mass energy of 3.773 GeV with the BESIII detector. As the only W-annihilation-free decay among D to a0(980) pseudoscalar, D+?KS0a0(980)+ is the ideal decay in extracting the contributions of the W-emission amplitudes involving a0(980) and to study the final-state interactions. The absolute branching fraction of D+?KS0?+? is measured to be (1.27±0.04stat±0.03syst)%. The branching fractions of intermediate processes D+?KS0a0(980)+ with a0(980)+??+? and D+??+K?0?(1430)0 with K?0?(1430)0?KS0? are measured to be (1.33±0.05stat±0.04syst)% and (0.14±0.03stat±0.01syst)%, 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.Öğe Observation of Structures in the Processes e+e- ???c1 and ??c2(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliWe present measurements of the Born cross sections for the processes e+e-???c1 and ??c2 at center-of-mass energies s from 4.308 to 4.951 GeV. The measurements are performed with data samples corresponding to an integrated luminosity of 11.0 fb-1 collected with the BESIII detector operating at the Beijing Electron Positron Collider storage ring. Assuming the e+e-???c2 signals come from a single resonance, the mass and width are determined to be M=(4413.6±9.0±0.8) MeV/c2 and ?=(110.5±15.0±2.9) MeV, respectively, which is consistent with the parameters of the well-established resonance ?(4415). In addition, we also use one single resonance to describe the e+e-???c1 line shape and determine the mass and width to be M=(4544.2±18.7±1.7) MeV/c2 and ?=(116.1±33.5±1.7) MeV, respectively. The structure of this line shape, observed for the first time, requires further understanding. © 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.Öğe Observation of the Anomalous Shape of X (1840) in J/? ??3 (?+?-) Indicating a Second Resonance Near p p ¯ Threshold(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliUsing a sample of (10087±44)×106 J/? events, which is about 45 times larger than that was previously analyzed, a further investigation on the J/???3(?+?-) decay is performed. A significant distortion at 1.84 GeV/c2 in the line shape of the 3(?+?-) 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 10?. The mass and width of X(1880) are determined to be 1882.1±1.7±0.7 MeV/c2 and 30.7±5.5±2.4 MeV, respectively, which indicates the existence of a pp¯ bound state. © 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.Öğe Observation of the singly Cabibbo-suppressed decay ?c+ ? ?-K+?+(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliThe singly Cabibbo-suppressed decay ?c+??-K+?+ is observed for the first time with a statistical significance of 5.4? by using 4.5 fb-1 of e+e- collision data collected at center-of-mass energies between 4.600 and 4.699 GeV with the BESIII detector at BEPCII. The absolute branching fraction of ?c+??-K+?+ is measured to be (3.8±1.2stat±0.2syst)×10-4 in a model-independent approach. This is the first observation of a Cabibbo-suppressed ?c+ decay involving ?- in the final state. The ratio of branching fractions between ?c+??-K+?+ and the Cabibbo-favored decay ?c+??-?+?+ is observed to be (0.4±0.1)sc2, where scsin?c=0.2248 with ?c the Cabibbo mixing angle. © 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.Öğe 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 AliA 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)Öğe 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 AliA 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.Öğe Search for the decay ?c1 (3872) ??+?-?c1(American Physical Society, 2024) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ai, X.C.; Aliberti, R.; Amoroso, A.; Çetin, Serkant AliUsing a data sample corresponding to an integrated luminosity of 10.9 fb-1 collected at center-of-mass energies from 4.16 to 4.34 GeV with the BESIII detector, we search for the decay ?c1(3872)??+?-?c1 in the radiative production e+e-???c1(3872). No significant signal is observed, and the ratio for the branching fraction of ?c1(3872)??+?-?c1 to ?c1(3872)??+?-J/? is measured as RB[?c1(3872)??+?-?c1]B[?c1(3872)??+?-J/?]<0.18 at 90% confidence level. An upper limit on the product of the cross section ?[e+e-???c1(3872)] and the branching fraction B[?c1(3872)??+?-?c1] at each center-of-mass energy is also given. These measurements favor the nonconventional charmonium nature of the ?c1(3872) state. © 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.Öğe 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 AliBased 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.
