Yazar "Uman, Igor" seçeneğine göre listele

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    Measurement of the Born cross section for e+e- →ηhc at center-of-mass energies between 4.1 and 4.6 GeV
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    We measure the Born cross section for the reaction e+e-→ηhc from s=4.129 to 4.600 GeV using datasets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross-section line shape near 4.200 GeV is observed with a statistical significance of 7σ. The parameters of this resonance are measured to be M=4188.8±4.7±8.0 MeV/c2 and Γ=49±16±19 MeV, where the first uncertainties are statistical and the second systematic. © 2025 authors. Published by the American Physical Society.
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    Observation of Λc+ → Λa0 (980)+ and Evidence for ς (1380)+ in Λc+ → Λπ+η
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    Based on 6.1 fb-1 of e+e- annihilation data collected at center-of-mass energies from 4.600 to 4.843 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis of Λc+→Λπ+η is performed, and branching fractions and decay asymmetry parameters of intermediate processes are determined. The process Λc+→Λa0(980)+ is observed for the first time, and evidence for the pentaquark candidate ς(1380)+ decaying into Λπ+ is found with statistical significance larger than 3σ with mass and width fixed to theoretical predictions. The branching fraction product B[Λc+→Λa0(980)+]B[a0(980)+→π+η] is determined to be (1.05±0.16stat±0.05syst±0.07ext)%, which is larger than theoretical calculations by 1-2 orders of magnitude. Here the third (external) systematic is from B(Λc+→Λπ+η). Finally, we precisely obtain the absolute branching fraction B(Λc+→Λπ+η)=(1.94±0.07stat±0.11syst)%. © 2025 authors. Published by the American Physical Society.
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    Search for a massless dark photon in c →uγ′ decays
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    Using 7.9fb-1 of e+e- collision data collected at s=3.773 GeV with the BESIII detector at the BEPCII collider, we search for the massless dark photon with the flavor-changing neutral current processes D0→ωγ′ and D0→γγ′ for the first time. No significant signals are observed, and the upper limits at the 90% confidence level on the massless dark photon branching fraction are set to be 1.1×10-5 and 2.0×10-6 for D0→ωγ′ and D0→γγ′, respectively. These results provide the most stringent constraint on the new physics energy scale associated with cuγ′ coupling in the world, with the new physics energy scale related parameter |C|2+|C5|2<8.2×10-17 GeV-2 at the 90% confidence level. © 2025 authors. Published by the American Physical Society.
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    Search for ηc (2S) →k+K-η′ decay
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    Using (2.712±0.014)×109 ψ(2S) events collected with the BESIII detector operating at the BEPCII, we search for the ηc(2S)→K+K-η′ decay. Its decay branching fraction is measured to be (11.11±4.67(stat)±1.82(syst)±4.24(extr))×10-4, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is from the branching fraction of the ψ(2S)→γηc(2S) decay. The statistical significance is 2.8σ. The upper limit on the product branching fraction B[ψ(2S)→γηc(2S)]×B[ηc(2S)→K+K-η′] is set to be 0.94×10-6 at 90% confidence level. In addition, the branching fractions of χc1→K+K-η′ and χc2→K+K-η′ are updated to be (8.48±0.10(stat)±0.47(syst))×10-4 and (1.53±0.04(stat)±0.08(syst))×10-4, respectively. The precision is improved by twofold. © 2025 authors. Published by the American Physical Society.
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    Study of Ds+ →f0 (980)ρ+ and φπ+ Decays through Ds+ →π+π+π-π0
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    We perform the first amplitude analysis of Ds+→π+π+π-π0 decays based on data samples of electron-positron collisions recorded with the BESIII detector at center-of-mass energies between 4.128 and 4.226 GeV, corresponding to an integrated luminosity of 7.33 fb-1. We report the observation of Ds+→f0(980)ρ(770)+ with a statistical significance greater than 10σ and determine the branching fractions B(Ds+→π+π+π-π0|non-η)=(2.04±0.08stat±0.05syst)% and B(Ds+→ηπ+)=(1.56±0.09stat±0.04syst)%. Moreover, we measure the relative branching fraction between φ→π+π-π0 and φ→K+K- to be [B(φ(1020)→π+π-π0)/B(φ(1020)→K+K-)]=0.230±0.014stat±0.010syst., which deviates from the world average value by more than 4σ. © 2025 authors. Published by the American Physical Society.
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    Test of Lepton Universality and Measurement of the Form Factors of D0 →k∗ (892)-μ+νμ
    (American Physical Society, 2025) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Çetin, Serkant Ali; Kolcu, Onur Buğra; Uman, Igor
    One of the main goals of studying semileptonic decays in flavor physics is to gain a better understanding of hadronic transitions in the nonperturbative region of Quantum Chromodynamics. This involves measuring Cabibbo-Kobayashi-Maskawa matrix elements, understanding form factors, and comparing them with theoretical predictions. We report a first study of the semileptonic decay D0→K-π0μ+νμ by analyzing an e+e- annihilation data sample of 7.93 fb-1 collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. The absolute branching fraction of D0→K-π0μ+νμ is measured for the first time, providing necessary input for extracting the c→s Cabibbo-Kobayashi-Maskawa matrix element through this process. This measurement allows us to test lepton flavor universality, with no indication of violation found. Furthermore, a series of hadronic form factors have been determined and compared with theoretical predictions, which will impose stricter constraints on theoretical models. © 2025 authors. Published by the American Physical Society.