### Yazar "Ahmed, S." seçeneğine göre listele

Listeleniyor 1 - 20 / 36

###### Sayfa Başına Sonuç

###### Sıralama seçenekleri

Öğe Amplitude analysis and branching fraction measurement of the decay D-s(+) -> pi(+)pi(0)pi(0)(SPRINGER, 2022) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Kolcu, Onur BuğraDaha fazla Using a data set corresponding to an integrated luminosity of 6.32fb(-1) recorded by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, an amplitude analysis of the decay D-s(+) -> pi(+)pi(0)pi(0 ) is performed, and the relative fractions and phases of different intermediate processes are determined. The absolute branching fraction of the decay D-s(+) -> pi(+)pi(0)pi(0)is measured to be (0.50 +/- 0.04(stat) 0.02(syst) )%. The absolute branching fraction of the intermediate process D-s(+) -> f(0)(980)pi(+), f(0)(980) ->pi(0)pi(0 ), is determined to be (0.28 +/- 0.04(stat) +/- 0.04(syst))%.Daha fazla Öğe Amplitude analysis of Ds+ ? ?+ ?- ?+(Amer Physical Soc, 2022) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliDaha fazla Utilizing the data set corresponding to an integrated luminosity of 3.19 fb(-1) collected by the BESIII detector at a center-of-mass energy of 4.178 GeV, we perform an amplitude analysis of the D-s(+) -> pi(+) pi(-) pi(+) decay. The sample contains 13,797 candidates with a signal purity of similar to 80%. The amplitude and phase of the contributing pi pi S wave are measured based on a quasi-model-independent approach, along with the amplitudes and phases of the P and D waves parametrized by Breit-Wigner models. The fit fractions of different intermediate decay channels are also reported.Daha fazla Öğe Measurement of A baryon polarization in e(+) e(-) -> Lambda(Lambda)over-bar at root s=3.773 GeV(AMER PHYSICAL SOC, 2022) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Using a data sample of psi(3770) events collected with the BESIII detector at BEPCII corresponding to an integrated luminosity of 2.9 fb-1, we report a measurement of A spin polarization in e+ e- -> Lambda(Lambda) over bar at = root s = 3.773 GeV. The significance of polarization is found to be 2 sigma including the systematic uncertainty, which implies a zero phase between the transition amplitudes of the Lambda(Lambda) over bar helicity states. This phase can be interpreted in terms of psionic form factors, and is determined to be Delta Phi(Psi) = Phi(Psi)(E) - Phi(Psi)(M) = (71(-46)(+66) +/- 5)degrees. Similarly, the ratio between the form factors is found to be R-psi = vertical bar G(E)(Psi)/G(M)(Psi)vertical bar = 0.48(-0.35)(+0.21) +/- 0.03. The first uncertainties are statistical and the second systematic.Daha fazla Öğe Measurement of branching fractions of J/psi and psi(3686) decays to Sigma(+) and (Sigma)over-bar(-)(SPRINGER, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Using 1310.6 x 10(6) J/psi and 448.1 x 10(6) psi(3686) events collected with the BESIII detector, the branching fractions of J/psi decays to Sigma(+)(Sigma) over bar (-) is measured to be (10.61 +/- 0.04 +/- 0.36) x 10(-4), which is significantly more precise than the current world average. The branching fractions of psi(3686) decays to Sigma(+)(Sigma) over bar (-) is measured to be (2.52 +/- 0.04 +/- 0.09) x 10(-4), which is consistent with the previous measurements. In addition, the ratio of beta(psi(3686) -> Sigma(+)(Sigma) over bar (-)) / beta(J/psi -> Sigma(+)(Sigma) over bar (-)) is determined to be (23.8 +/- 1.1)% which violates the "12% rule".Daha fazla Öğe Measurement of e (+) e (-) -> gamma chi(c0,c1,c2) cross sections at center-of-mass energies between 3.77 and 4.60 GeV(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Amoroso, A.; Kolcu, Onur BuğraDaha fazla BESIII detector at BEPCII. We observe for the first time e(+)e(-)->gamma chi(c1; c2) signals at root s = 4.180 GeV with statistical significances of 7.6s and 6.0s, respectively. The production cross section of e(+)e(-)->gamma chi(c1; c2) at each center-of-mass energy is also measured. We find that the line shape of the e(+)e(-) ->gamma chi(c1) cross section can be described with conventional charmonium states psi(3686), psi(3770), psi(4040), psi(4160). Compared with this, for the e(+)e(-) ->gamma chi(c2) channel, one more additional resonance is added to describe the cross section line shape. Its mass and width are measured to be M = 4371.7 +/- 7.5 +/- 1.8 MeV=c(2) and G(tot) 1/4 =51.1 +/- 17.6 +/- 1.9 MeV, where the first uncertainties are statistical and the second systematic. The significance of this resonance is estimated to be 5.8s, and its parameters agree with the Yo4360THORN resonance previously reported in e(+)e(-)-> pi+pi(-)psi(3686), and the Y(4390) in e(+)e(-). pi(+)pi(-) h(c) within uncertainties. No significant signal for the e(+)e(-->)gamma chi(c0) process is observed, and the upper limits of Born cross sections sigma(B)(e(+)e(-)->gamma chi(c0)) at 90% confidence level are reported.Daha fazla Öğe Measurement of e(+)e(-)-> K+K-pi(0) cross section and observation of a resonant structure(SPRINGER, 2022) Ablikim, M; Achasov, MN; Adlarson, P.; Ahmed, S.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Based on e(+)e(-) collision data collected by the BESIII detector at the BEPCII collider at center-of-mass energies from 2.000 to 3.080 GeV, a partial-wave analysis is performed for the process e(+)e(-)-> K+K-pi(0). The Born cross section of the process e(+)e(-)-> K+K-pi(0) and its subprocesses e(+)e(-)-> phi pi(0), K*+(892)K- and K2*+(1430)K- are measured. The results for e(+)e(-)-> K+K-pi(0) and phi pi(0) are consistent with the BaBar measurements and with improved precision. By analyzing the cross sections of the subprocesses e(+)e(-)-> K*+(892)K- and K2*+(1430)K-, a structure with mass M-R = (2190 +/- 19 +/- 37) MeV/c(2) and width Gamma(R) = (191 +/- 28 +/- 60) MeV is observed with a combined statistical significance of 7.1 sigma. The measured resonance parameters suggest it can be identified as the phi(2170), thus the results provide valuable input to understand the internal nature of this state.Daha fazla Öğe Measurement of e+e- ? ??+?- cross section at s=2.000 to 3.080 GeV(Springer, 2023) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliDaha fazla A partial wave analysis on the process e(+)e(-) -> omega(+)pi(-) is performed using 647 pb(-1) of data sample collected by using the BESIII detector operating at the BEPCII storage ring at center-of-mass (c.m.) energies from 2.000 GeV to 3.080 GeV. The Born cross section of the e(+)e(-) -> omega pi(+)pi(-) process is measured, with precision improved by a factor of 3 compared to that of previous studies. A structure near 2.25 GeV is observed in the energy-dependent cross sections of e(+)e(-) -> omega pi(+)pi(-) and omega pi(0)pi(0) with a statistical significance of 7.6 sigma, and its determined mass and width are 2232 +/- 19 +/- 27 MeV/c(2) and 93 +/- 53 +/- 20 MeV, respectively, where the first and second uncertainties are statistical and systematic, respectively. By analyzing the cross sections of subprocesses e(+)e(-) -> omega f(0)(500), omega f(0)(980), omega f(0)(1370), omega f(2)(1270), and b(1)(1235)pi, a structure, with mass M = 2200 +/- 11 +/- 17 MeV/c(2) and width Gamma = 74 +/- 20 +/- 24 MeV, is observed with a combined statistical significance of 7.9 sigma. The measured resonance parameters will help to reveal the nature of vector states around 2.25 GeV.Daha fazla Öğe Measurement of e+e- ? ?p+p- cross section at ?s = 2.000 to 3.080 GeV (vol 01, 111, 2023)(Springer, 2023) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliDaha fazla [Abstract Not Available]Daha fazla Öğe Measurement of integrated luminosities at BESIII for data samples at center-of-mass energies between 4.0 and 4.6 GeV*(IOP Publishing Ltd, 2022) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.Daha fazla The integrated luminosities of data samples collected in the BESIII experiment in 2016-2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010-2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur.Daha fazla Öğe Measurement of the absolute branching fraction of inclusive semielectronic D-s(+) decays(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Amoroso, A.; Kolcu, Onur BuğraDaha fazla We measure the inclusive semielectronic decay branching fraction of the D-s(+) meson. A double-tag technique is applied to e(+)e(-) annihilation data collected by the BESIII experiment at the BEPCII collider, operating in the center-of-mass energy range 4.178-4.230 GeV. We select positrons from D (+)(s) -> Xe+nu(e) with momenta greater than 200 MeV/c and determine the laboratory momentum spectrum, accounting for the effects of detector efficiency and resolution. The total positron yield and semielectronic branching fraction are determined by extrapolating this spectrum below the momentum cutoff. We measure the D-s(+) semielectronic branching fraction to be (6.30 +/- 0.13(stat.) +/- 0.09(syst.) +/- 0.04(ext.))%, showing no evidence for unobserved exclusive semielectronic modes. We combine this result with external data taken from literature to determine the ratio of the D-s(+) and D-0 semielectronic widths, Gamma(D-s(+) -> X-e(+)nu(e))/Gamma(D-0 -> X-e(+)nu(e))=0.790 +/- 0.016(stat.) +/- 0.011(syst.) +/- 0.016(ext.). Our results are consistent with and more precise than previous measurements.Daha fazla Öğe Measurement of the absolute branching fractions of J/psi -> gamma eta and eta decay modes(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Based on a data sample of (1.0087 +/- 0.0044) x 10(10) J/psi events collected by the BESIII detector at the BEPCII accelerator, the absolute branching fraction (BF) of the decay J/psi -> gamma eta is measured with high precision using events in which the radiative photon converts to e(+)e(-). Using the measured absolute BF of J/psi -> gamma eta, the absolute BFs of four dominant. decay modes are measured for the first time. The results are B(J/psi -> gamma eta) = (1.067 +/- 0.005 +/- 0.023) x 10(-3), B(eta ->gamma gamma) = (39.86 +/- 0.04 +/- 0.99)%, B(eta ->pi(0)pi(0)pi(0)) = (31.96 +/- 0.07 +/- 0.84)%, B(eta -> pi(+)pi(-)pi(0)) = (23.04 +/- 0.03 +/- 0.54)%, and B(eta -> pi(+)pi(-)gamma) = (4.38 +/- 0.02 +/- 0.10)%, where the first and second uncertainties are statistical and systematic, respectively. The results are consistent with the world average values within two standard deviations.Daha fazla Öğe Measurement of the cross section for e(+)e(-) -> Lambda(Lambda)over-bar and evidence of the decay psi(3770) -> Lambda(Lambda)over-bar(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla The Born cross section of the process e(+)e(-) ->Lambda(Lambda) over bar over line is measured at 33 center-of-mass energies between 3.51 and 4.60 GeV using data corresponding to the total integrated luminosity of 20.0 fb(-1) collected with the BESIII detector at the BEPCII collider. Describing the energy dependence of the cross section requires a contribution from the psi(3770) -> Lambda(Lambda) over bar decay, which is fitted with a significance of 4.6 - 4.9 sigma including the systematic uncertainty. The lower bound on its branching fraction is 2.4 x 10(-6) at the 90% confidence level (C.L.), at least an order of magnitude larger than expected from predictions using a scaling based on observed electronic widths. This result indicates the importance of effects from vector charmonium(like) states when interpreting data in terms of e.g., electromagnetic structure observables. The data do not allow for definite conclusions on the interplay with other vector charmonium(like) states, and we set 90% C.L. upper limits for the products of their electronic widths and the branching fractions.Daha fazla Öğe Measurement of the Cross Section for e+e- ?Hadrons at Energies from 2.2324 to 3.6710 GeV(American Physical Society, 2022) Ablikim, M.; Achasov, M.N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Based on electron-positron collision data collected with the BESIII detector operating at the Beijing Electron-Positron Collider II storage rings, the value of R?(e+e-?hadrons)/?(e+e-??+?-) is measured at 14 center-of-mass energies from 2.2324 to 3.6710 GeV. The resulting uncertainties are less than 3.0% and are dominated by systematic uncertainties. © 2022 authors. Published by the American Physical Society.Daha fazla Öğe Measurement of the inclusive branching fraction for psi (3686) -> K-S(0) + anything(ELSEVIER, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Amoroso, A.; Kolcu, Onur BuğraDaha fazla Using 5.9 pb(-1) of e(+)e(-) annihilation data collected at center-of-mass energies from 3.640 to 3.701 GeV with the BESIII detector at the BEPCII Collider, we measure the observed cross sections of e(+)e(-) -> (KSX)-X-0 (where X = anything). From a fit to these observed cross sections with the sum of continuum and psi(3686) and J/psi Breit-Wigner functions and considering initial state radiation and the BEPCII beam energy spread, we obtain for the first time the product of psi(3686) leptonic width and inclusive decay Physics Letters 820 (2021) 136576 branching fraction Gamma B-ee(psi)(3686)(psi(3686) -> (KSX)-X-0) = (373.8 +/- 6.7 +/- 20.0) eV, and assuming Gamma(ee)(psi)((3686)) is (2.33 +/- 0.04) keV from PDG value, we measure B(psi(3686) ->(KSX)-X-0) = (16.04 +/- 0.29 +/- 0.90)%, where the first uncertainty is statistical and the second is systematic. (C) 2021 The Author(s). Published by Elsevier B.V.Daha fazla Öğe Measurements of the absolute branching fractions of hadronic D -meson decays involving kaons and pions(American Physical Society, 2022) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.Daha fazla By analyzing an electron-positron collision data sample corresponding to an integrated luminosity of 2.93 fb-1 taken at the center-of-mass energy of 3.773 GeV with the BESIII detector, we obtain for the first time the absolute branching fractions for seven D0 and D+ hadronic decay modes and search for the hadronic decay D0?KS0KS0?0 with much improved sensitivity. The results are B(D0?KS0?0?0?0)=(7.64±0.30±0.29)×10-3, B(D0?K-?+?0?0?0)=(9.54±0.30±0.31)×10-3, B(D0?KS0?+?-?0?0)=(12.66±0.45±0.43)×10-3, B(D+?KS0?+?0?0)=(29.04±0.62±0.87)×10-3, B(D+?KS0?+?+?-?0)=(15.28±0.57±0.60)×10-3, B(D+?KS0?+?0?0?0)=(5.54±0.44±0.32)×10-3, B(D+?K-?+?+?0?0)=(4.95±0.26±0.19)×10-3, and B(D0?KS0KS0?0)<1.45×10-4 at the 90% confidence level. Here, the first uncertainties are statistical, and the second ones are systematic. The newly studied decays greatly enrich the knowledge of the D?K???? and D?K????? hadronic decays and open a bridge to access more two-body hadronic D decays containing scalar, vector, axial, and tensor mesons in the charm sector. © 2022 authors. Published by the American Physical Society.Daha fazla Öğe Observation of ?(3770) ? ?J/?(Amer Physical Soc, 2023) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Amoroso, A.; Çetin, Serkant AliDaha fazla Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, the Born cross section of the process e+e- -> eta J=psi at a center-of-mass energy pffisffi = 3.773 GeV is measured to be (8.88 +/- 0.87 +/- 0.42) pb. We fit the cross section line shape before correcting for the initial state radiation ffiffifromps = 3.773 to 4.600 GeV to obtain the branching fraction B(psi(3770) -> eta J=psi). We obtain B(psi(3770) -> eta J=psi) = (11.3 +/- 5.9 +/- 1.1) x 10-4 when the psi(3770) decay amplitude is added coher-ently to the other contributions, and (8.7 +/- 1.0 +/- 0.8) x 10-4 when it is added incoherently. Here the quoted uncertainties are statistical and systematic, respectively. In both cases, the statistical significance of psi(3770) resonance is above 7 sigma. This is the first time the decay psi(3770) -> eta J=psi is observed with a statistical significance greater than 5 sigma.Daha fazla Öğe Observation of a State X(2600) in the ?^{+}?^{-}?' System in the Process J/????^{+}?^{-}?'(NLM (Medline), 2022) Ablikim, M.; An, M.R.; Ahmed, S.; Bai, X.H.; Kolcu, Onur Buğra; Çetin, Serkant Ali; Shang, K. Y.; Shangguan, L.; Shi, H.; Schoenning, M.Daha fazla Based on (10087±44)×10^{6}??J/? events collected with the BESIII detector, the process J/????^{+}?^{-}?^{'} is studied using two largest decay channels of the ?^{'} meson, ?^{'}???^{+}?^{-} and ?^{'}???^{+}?^{-}, ????. A new resonance, which we denote as the X(2600), is observed with a statistical significance larger than 20? in the ?^{+}?^{-}?^{'} invariant mass spectrum, and it has a connection to a structure around 1.5??GeV/c^{2} in the ?^{+}?^{-} invariant mass spectrum. A simultaneous fit on the ?^{+}?^{-}?^{'} and ?^{+}?^{-} invariant mass spectra with the two ?^{'} decay modes indicates that the mass and width of the X(2600) state are 2618.3±2.0_{-1.4}^{+16.3}??MeV/c^{2} and 195±5_{-17}^{+26}??MeV, where the first uncertainties are statistical, and the second systematic.Daha fazla Öğe Observation of psi (3686) ->Xi (1530)(0) (Xi)over-bar (1530)(0) and Xi (1530)(0) (Xi)over-bar(0)(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla Using (448.1 +/- 2.9) x 10(6) psi (3686) events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays psi(3686)-> Xi (1530)(0) (Xi) over bar (1530)(0) and Xi (1530)(0) (Xi) over bar (0). The branching fractions are measured to be B psi (3686)-> Xi (1530)(0) (Xi) over bar (1530)(0)) = (6.77 +/- 0.14 +/- 0.39 x 10(- 5) and B (psi(3686)-> Xi (1530)(0) (Xi) over bar (0) = (0.53 +/- 0.04 +/- 0.03) x 10(-5). Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay psi (3686) ->Xi (1530)(0) (Xi) over bar (1530)(0) is determined to be alpha= 1/4 0.32 +/- 0.19 +/- 0.07, in agreement with theoretical predictions within one standard deviation.Daha fazla Öğe Observation of the decay D-0 -> rho - mu + nu(mu)(AMER PHYSICAL SOC, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla By analyzing an e(+)e(-) annihilation data sample corresponding to an integrated luminosity of 2.93 fb(- 1) collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the branching fraction of the D-0 ->rho(-) mu(+)nu(mu) decay for the first time. We obtain BD0 ->rho(-) mu(+)nu(mu) = (1.35 +/- 0.09(stat) +/- 0.09(syst)) x 10(-3). Using the world average of BD0 ->(rho)- epsilon(+)nu(epsilon), we find a branching fraction ratio of BD0 ->rho(-) mu(+)nu(mu)/ BD0 ->rho(-)e(+) nu(epsilon) = 0.90 +/- 0.11, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. Combining the world average of BD+->rho(0)mu+(.nu)(mu) and the lifetimes of D0(+), we obtain a partial decay width ratio of Gamma D-0 ->rho(-)mu(+)nu mu/2 Gamma D-0 ->rho(0)mu(+)nu(mu) ) = 0.71 +/- 0.14, which is consistent with the isospin symmetry expectation of unity within 2.1s. For the reported values of BD0 ->rho(-) mu(+)nu(mu)/BD0 ->rho(-)e+nu(e) and Gamma D-0 ->rho(-) mu(+nu)(mu) /2 Gamma(+)(D) ->rho(0)mu(+) nu(mu), the uncertainty is the quadratic sum of the statistical and systematic uncertainties.Daha fazla Öğe Observation of the decays chi(cJ) -> nK(S)(0) (Lambda)over-bar + c.c.(SPRINGER, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant Ali; Kolcu, Onur BuğraDaha fazla By analyzing 4.48 x 10(8) psi(3686) events collected with the BESIII detector, we observe the decays chi(cJ) -> nK(S)(0) (Lambda) over bar + c.c. (J = 0, 1, 2) for the first time, via the radiative transition psi(3686) -> gamma chi(cJ). The branching fractions are determined to be (6.65 +/- 0.26(stat)+/- 0.41(syst)) x 10(-4), (1.66 +/- 0.12(stat) +/- 0.12(syst)) x 10(-4), and (3.58 +/- 0.16(stat) +/- 0.23(syst)) x 10(-4) for J = 0, 1, and 2, respectively.Daha fazla