Yazar "Amoroso, A." seçeneğine göre listele

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    Amplitude analysis and branching fraction measurement of Ds+ ? K+K-?+
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    We report an amplitude analysis and branching fraction measurement of D-s(+) -> K+K-pi(+) decay using a data sample of 3.19 fb(-1) recorded with BESIII detector at a center-of-mass energy of 4.178 GeV. We perform a model-independent partial wave analysis in the low K+K- mass region to determine the K+K- S-wave line shape, followed by an amplitude analysis of our very pure high-statistics sample. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be B(D-s(+) -> K+K-pi(+)) = (5.47 +/- 0.08(stat) +/- 0.13(sys))%.
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    Cross section measurement of e+e- ? KS0KL0 at ?s=2.00-3.08 GeV
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    The cross sections of the process e(+)e(-) -> (KSKL0)-K-0 are measured at fifteen center-of-mass energies root s from 2.00 to 3.08 GeV with a total integrated luminosity of 582 pb(-1) and using the BESIII detector at the Beijing Electron Positron Collider. The results are found to be consistent with those obtained by BABAR. A resonant structure around 2.2 GeV is observed, with a mass and width of 2273.7 +/- 5.7 +/- 19.3 MeV/c(2) and 86 +/- 44 +/- 51 MeV, respectively, where the first uncertainties are statistical and the second ones are systematic. The product of its radiative width (Gamma(e+e-)) with its branching fraction to (KSKL0)-K-0 (Br-KS0KL0) is 0.9 +/- 0.6 +/- 0.7 eV.
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    Cross section measurement of e+e- ? p(p)over-bar? and e+e- ? p(p)over-bar? at center-of-mass energies between 3.773 GeV and 4.6 GeV
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    Based on 14.7 fb(-1) of e(+)e(-) annihilation data collected with the BESIII detector at the BEPCII collider at 17 different center-of-mass energies between 3.7730 GeV and 4.5995 GeV, Born cross sections of the two processes e(+)e(-) -> p (p) over bar eta and e(+)e(-) -> p (p) over bar omega are measured for the first time. No indication of resonant production through a vector state V is observed, and upper limits on the Born cross sections of e(+)e(-) -> p (p) over bar eta and e(+)e(-) -> p (p) over bar omega at the 90% confidence level are calculated for a large parameter space in resonance masses and widths. For the current world average parameters of the psi(4230) of m = 4.2187 GeV=c(2) and Gamma = 44 MeV, we find upper limits on resonant production of the p (p) over bar eta and p (p) over bar omega final states of 7.5 pb and 10.4 pb at the 90% CL, respectively.
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    Direct Measurement of the Branching Fractions B(?(3686) ? J/?X) and B(?(3770) ? J/?X), and Observation of the State R(3760) in e+e- ? J/?X
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; An, Q.
    We report a measurement of the observed cross sections of e(+)e(-) -> J/psi X based on 3.21 fb(-1) of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. In analysis of the cross sections, we measured the decay branching fractions of B(psi(3686 -> J/psi X) = (64.4 +/- 0.6 +/- 1.6)% and B(psi(3770) -> J/psi X) = (0.5 +/- 0.2 +/- 0.1)% for the first time. The energy-dependent line shape of these cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays psi(3686) -> J/psi X and psi(3770) -> J/psi X. Instead, it can be better described with one more BW amplitude of the decay R(3760) -> J/psi X. Under this assumption, we extracted the R(3760) mass M-R(3760) = 3766.2 +/- 3.8 +/- 0.4 MeV/c(2), total width Gamma(tot)(R(3760)) = 22.2 +/- 5.9 +/- 1.4 MeV, and product of leptonic width and decay branching fraction Gamma(ee)(R(3760)) B[R(3760) -> J/psi X] = (79.4 +/- 85.5 +/- 11.7) eV. The significance of the R(3760) is 5.3 sigma. The first uncertainties of these measured quantities are from fits to the cross sections and second systematic.
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    Measurement of the branching fraction of and search for a CP-violating asymmetry in ?? ? ?+ ?- e+ e- at BESIII
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    Therare decay eta' -> pi(+) pi(-) e(+) e(-) is studied using a sample of1.3 x 10(9) J/Psi events collected with the BESIII detector at BEPCII in 2009 and 2012. The branching fraction is measured with improved precision to be (2.42 +/- 0.05(stat) +/- 0.08(syst)) x 10(-3). Due to the inclusion of new data, this result supersedes the last BESIII result on this branching fraction. In addition, the CP-violating asymmetry in the angle between the decay planes of the pi(+)pi(-)-pair and the e(+)e(-)-pair is investigated. A measurable value would indicate physics beyond the standard model; the result is A(CP) = (2.9 +/- 3.7(stat) +/- 1.1(syst))%, which is consistent with the standard model expectation of no CP-violation. The precision is comparable to the asymmetry measurement in the K-L(0) -> pi(+) pi(-) e(+) e(-) decay where the observed (14 +/- 2)% effect is driven by a standard model mechanism.
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    Measurements of ?+ and ?- time-like electromagnetic form factors for center-of-mass energies from 2.3864 to 3.0200 GeV
    (Elsevier, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    The Born cross sections of the e(+)e(-) -> Sigma(+)(Sigma) over bar (-) and e(+)e(-)-> Sigma(-)(Sigma) over bar (+) processes are determined for centerof-mass energy from 2.3864 to 3.0200 GeV with the BESIII detector. The cross section lineshapes can be described properly by a pQCD function and the resulting ratio of effective form factors for the Sigma(+) and Sigma(-) is consistent with 3. In addition, ratios of the Sigma(+) electric and magnetic form factors, vertical bar G(E)/G(M)vertical bar. are obtained at three center-of-mass energies through an analysis of the angular distributions. These measurements, which are studied for the first time in the off-resonance region, provide precision experimental input for understanding baryonic structure. The observed new features of the Sigma(+/-) form factors require more theoretical discussions for the hyperons. (C) 2021 The Author(s). Published by Elsevier B.V.
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    Model-Independent Determination of the Spin of the ?- and Its Polarization Alignment in ?(3686) ? ?-(?)over-bar+
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    We present an analysis of the process psi(3686) -> Omega(-)(Omega) over bar (+)(Omega(-). K-Lambda, (Omega) over bar (+) K+ (Lambda) over bar,(Omega) over bar (+) Lambda -> p pi(-), (Lambda) over bar -> p (p) over bar pthorn) based on a dataset of 448 x 10(6) psi(o3686) decays collected with the BESIII detector at the BEPCII electron-positron collider. The helicity amplitudes for the process psi(368)-> O-O thorn and the decay parameters of the subsequent decay O-. K-. oO thorn. Kthorn. THORN are measured for the first time by a fit to the angular distribution of the complete decay chain, and the spin of the O- is determined to be 3=2 for the first time since its discovery more than 50 years ago.
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    Observation of ?? ? ?+?-?+?-
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    Using (1310.6 +/- 7.0) x 10(6) J/psi events acquired with the BESIII detector at the BEPCII storage rings, the decay eta' -> pi(+)pi(-)mu(+)mu(-) is observed for the first time with a significance of 8 sigma via the process J/psi -> gamma eta'. We measure the branching fraction of eta' -> pi(+)pi(-)mu(+)mu(-) to be B(eta' -> pi(+)pi(-)mu(+)mu(-)) = (1.97 +/- 0.33(stat) +/- 0.19(syst)) x 10(-5), where the first and second uncertainties are statistical and systematic, respectively.
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    Observation of a resonant structure in e+e-? ?? and another in e+e-? ??0 at center-of-mass energies between 2.00 and 3.08 GeV
    (Elsevier, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    Born cross sections for the processes e(+)e(-) -> omega eta and e(+)e(-) -> omega pi(0) have been determined for centerof-mass energies between 2.00 and 3.08GeVwith the BESIII detector at the BEPCII collider. The results obtained in this work are consistent with previous measurements but with improved precision. Two resonant structures are observed. In the e(+)e(-) -> omega eta cross sections, a resonance with a mass of (2176 +/- 24 +/- 3) MeV/c(2) and a width of (89 +/- 50 +/- 5) MeV is observed with a significance of 6.2 sigma. Its properties are consistent with the phi(2170). In the e(+)e(-) -> omega pi(0) cross sections, a resonance denoted Y (2040) is observed with a significance of more than 10 sigma. Its mass and width are determined to be (2034 +/- 13 +/- 9) MeV/c(2) and (234 +/- 30 +/- 25) MeV, respectively, where the first uncertainties are statistical and the second ones are systematic. (C) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license.
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    Polarization and entanglement in baryon-antibaryon pair production in electron-positron annihilation
    (Nature Portfolio, 2019) Ablikim, M.; Achasov, M. N.; Ahmed, S.; Albrecht, M.; Alekseev, M.; Amoroso, A.; Çetin, Serkant Ali
    Particles directly produced at electron-positron colliders, such as the J/psi meson, decay with relatively high probability into a baryon-antibaryon pair(1). For spin-1/2 baryons, the pair can have the same or opposite helicites. A non-vanishing phase Delta Phi between the transition amplitudes to these helicity states results in a transverse polarization of the baryons(2-4). From the joint angular distribution of the decay products of the bary-ons, this phase as well as the parameters characterizing the baryon and the antibaryon decays can be determined. Here, we report the measurement of Delta Phi = 42.4 +/- 0.6 +/- 0.5 degrees using Lambda -> p pi(-) and (Lambda) over bar -> (p) over bar pi(+), (n ) over bar pi(0) decays at BESIII. We find a value for the Lambda -> p pi(-) decay parameter of alpha(-) = 0.750 +/- 0.009 +/- 0.004, 17 +/- 3% higher than the current world average, which has been used as input for all Lambda polarization measurements since 1978(5,6). For (Lambda) over bar -> (p) over bar pi(+) we find alpha(+) = -0.758 +/- 0.010 +/- 0.007, giving A(CP) = (alpha(-) + alpha(+))/(alpha(-) - alpha(+)) = -0.006 +/- 0.012 +/- 0.007, a precise direct test of charge-parity symmetry (CP) violation in Lambda decays.
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    Search for the reaction e+ e- ? ?cJ?+?- and a charmoniumlike structure decaying to ?cJ?± between 4.18 and 4.60 GeV
    (Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    We search for the process e(+)e(-) -> chi(cJ)pi(+) pi(-) (J = 0, 1, 2) and for a charged charmoniumlike state in the chi(cJ)pi +/- subsystem. The search uses datasets collected with the BESIII detector at the BEPCII storage ring at center-of-mass energies between 4.18 GeV and 4.60 GeV. No significant chi(cJ)pi(+) pi(-) signals are observed at any center-of-mass energy, and thus upper limits are provided which also serve as limits for a possible charmoniumlike structure in the invariant chi(cJ)pi +/- mass.
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    Search for the semileptonic decay D0(+) ? b1 (1235)-(0)e+ve
    (Amer Physical Soc, 2020) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant Ali
    Using 2.93 fb-1 of e(+)e(-) data collected at a center-of-mass energy root s = 3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the semileptonic D0(+) decays into a b(1)(1235)(-(0)) axial-vector meson for the first time. No significant signal is observed for either charge combination. The upper limits on the product branching fractions are BD0 -> b1(1235)-e+ve. Bb1(1235)-->omega pi- < 1.12 x 10(-4) and BD+-> b1(1235)0e+ve center dot B-b1(1235)0 ->omega pi 0 < 1.75 x 10(-4) at the 90% confidence level.