Yazar "Ahmed, S." seçeneğine göre listele
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Öğe 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 AliWe 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))%.Öğe Amplitude analysis and branching fraction measurement of Ds+? K- K+ ?+ ?0(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliThe first amplitude analysis of the decay D-s(+)-> K- K+ pi(+) pi(0) is presented using the data samples, corresponding to an integrated luminosity of 6.32 fb(-1), collected with the BESIII detector at e(+)e(-) center-of-mass energies between 4.178 and 4.226 GeV. More than 3000 events selected with a purity of 97.5% are used to perform the amplitude analysis, and nine components are found necessary to describe the data.Öğe Amplitude analysis and branching-fraction measurement of Ds+ ? KS0?+?0(Springer, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliBy using 6.32 fb(-1) of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay D-s(+) -> K-S(0) pi(+)pi(0) and determine the relative fractions and phase differences of different intermediate processes, which include K-S(0) rho(770)(+), K-S(0)rho(1450)(+), K*(892)(0) pi(+), K* (892)(+) pi(0), and K* (1410)(0) pi(+). With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be B(D-s(+) -> K-S(0) pi(+) pi(0)) = (5.43 +/- 0.30(stat) +/- 0.15(syst)) x 10(-3).Öğe Amplitude analysis and branching-fraction measurement of Ds+ ? KS0K- ?+?+(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing 6.32 fb(-1) of e(+)e(-) collision data collected by the BESIII detector at the center-of-mass energies between 4.178 and 4.226 GeV, an amplitude analysis of the D-s(+) -> (KSK-)-K-0 pi(+)pi(+) decays is performed for the first time to determine the intermediate-resonant contributions. The dominant component is the D-s(+) -> K*(892)(+)(K) over bar*(892)(0) decay with a fraction of (40.6 +/- 2.9(stat) +/- 4.9(sys))%. Our results of the amplitude analysis are used to obtain a more precise measurement of the branching fraction of the D-s(+) -> (KSK-)-K-0 pi(+)pi(+) decay, which is determined to be (1.46 +/- 0.05(stat) +/- 0.05(sys))%.Öğe Cross section measurement of e+e- ? ?+ ?- ? (3686) from ?s=4.0076 GeV to 4.6984 GeV(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing data samples with a total integrated luminosity of 20.1 fb(-1) collected by the BESIII detector operating at the BEPCII collider, the cross section of the process e(+) e(-) -> pi(+) pi(-) psi(3686) is measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, and with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a nonresonant contribution, confirms the existence of the charmonium-like states Y(4220), Y(4390), and Y(4660). This is the first observation of the Y(4660) at the BESIII experiment.Öğe 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 AliThe 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.Öğe 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 AliBased 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.Öğe Cross sections for the reactions e+e- ? K+ K- ?+?- (x0), K+K-K+K- (?0), ?+?-?+?- (x0), pp over bar ?+?- (?0) in the energy region between 3.773 and 4.600 GeV(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing the data samples collected in the energy range from 3.773 to 4.600 GeV with the BESIII detector at the BEPCII collider, we measure the dressed cross sections as a function of center-of-mass energy for e(+)e(-) -> K+K- pi(+)pi(-) (pi(0)), K+K-K+K- (pi(0)), pi(+)pi(-) pi(+)pi(-) (pi(0)), and p (p) over bar pi(+)pi(-)(pi(0)). The cross sections for e(+)e(-) -> K+K-K+K- pi(0), p (p) over bar pi(+)pi(-)(pi(0)) are the first measurements. Cross sections for the other five channels are much more precise than previous results in this energy region. We also search for charmonium and charmonium-like resonances, such as the Y(4230), decaying into the same final states. We find evidence of the psi(4040) decaying to pi(+)pi(-) pi(+)pi(-) pi(0) with a statistical significance of 3.6 sigma. Upper limits are provided for other decays since no clear signals are observed.Öğe Determination of the ?c+ spin via the reaction e+e- ? ?c(?)over-barc(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliWe report on a comparison of two possible Lambda(+)(c) spin hypotheses, J = 1/2 and 3/2, via the process e(+)e(-) -> Lambda(c)(Lambda) over bar (c) using the angular distributions of Lambda(+)(c) decays into pK(S)(0), Lambda pi(+), Sigma(0)pi(+) and Sigma(+)pi(0). The data were recorded at root sp = 4.6 GeV with the BESIII detector and correspond to an integrated luminosity of 587 pb(-1). The. thornc spin is determined to be J = 1/2, with this value favored over the 3 2 hypothesis with a significance corresponding to more than 6 Gaussian standard deviations.Öğe Determination of the absolute branching fractions of D0 ? K-e+?e and D+ ? (K)over-bar0e+?e(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing 2.93 fb(-1) of e(+)e(-) collision data collected with the BESIII detector at a center-of-mass energy of 3.773 GeV, we measure the absolute branching fractions of the decays D-0 -> K(-)e(+)nu(e) and D+ -> (K) over bar (0)e(+)nu(e) to be (3.567 +/- 0.031(stat) +/- 0.025(syst))% and (8.68 +/- 0.14(stat) +/- 0.16(syst))%, respectively. Starting with the process e(+)e(- ) -> D (D) over bar, a new reconstruction method is employed to select events that contain candidates for both D -> (K) over bare(+)nu(e) and (D) over bar -> Ke(-)(nu) over bar (e) decays. The branching fractions reported in this work are consistent within uncertainties with previous BESIII measurements that selected events containing D -> (K) over bare(+)nu(e) and hadronic (D) over bar decays. Combining our results with the lifetimes of the D degrees and D+ mesons and the previous BESIII measurements leads to a ratio of the two decay partial widths of (Gamma) over bar (D0 -> K-e+)(nu e)/(Gamma) over bar (D+ -> (K) over bar 0e+)(nu e) = 1.039 +/- 0.021. This ratio supports isospin symmetry in the D-0 -> K(-)e(+)nu(e) and D+ -> (K) over bar (0)e(+)nu(e) decays within 1.9 sigma.Öğe 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.Öğe Measurement of cross section for e+e- ? ?-(?)over-bar+ near threshold at BESIII(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliThe Born cross sections and effective form factors for process e(+)e(-) -> Xi(-)(Xi) over bar (+) are measured at eight center-of-mass energies between 2.644 and 3.080 GeV, using a total integrated luminosity of 363.9 pb(-1 )e(+) e(-) collision data collected with the BESIII detector at BEPCII. After performing a fit to the Born cross section of e(+)e(-) -> Xi(-)(Xi) over bar (+), no significant threshold effect is observed.Öğe Measurement of cross section for e+e- ? ?0(?)over-bar0 near threshold(Elsevier, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing e(+)e(-) collision data at ten center-of-mass energies between 2.644 and 3.080 GeV collected with the BESIII detector at BEPCII and corresponding to an integrated luminosity of about 500 pb(-1), we measure the cross sections and effective form factors for the process e(+)e(-) -> Xi(0)(Xi) over bar (0) utilizing a single-tag method. A fit to the cross section of e(+)e(-) -> Xi(0)(Xi) over bar (0) with a pQCD-driven power function is performed, from which no significant resonance or threshold enhancement is observed. In addition, the ratio of cross sections for the processes e(+)e(-) -> Xi(0)(Xi) over bar (0) and Xi(0)(Xi) over bar (0) is calculated using recent BESIII measurement and is found to be compatible with expectation from isospin symmetry. (C) 2021 The Author(s). Published by Elsevier B.V.Öğe Measurement of e + e - ? ??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.; Çetin, Serkant AliBESIII 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.Öğe Measurement of proton electromagnetic form factors in the time-like region using initial state radiation at BESIII(Elsevier, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Alekseev, M.; Çetin, Serkant AliThe electromagnetic process e(+)e(-) -> p (p) over bar over bar is studied with the initial-state-radiation technique using 7.5 fb(-1) of data collected by the BESIII experiment at seven energy points from 3.773 to 4.600 GeV. The Born cross section and the effective form factor of the proton are measured from the production threshold to 3.0 GeV/c(2) using the p (p) over bar over bar invariant-mass spectrum. The ratio of electric and magnetic form factors of the proton is determined from the analysis of the proton-helicity angular distribution. (C) 2021 The Author. Published by Elsevier B.V.Öğe Measurement of the absolute branching fraction of ?c+ ? pKS0? decays(Elsevier, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Alekseev, M.; Çetin, Serkant AliBased on 586 pb(-1) of e(+) e(-) annihilation data collected at a center-of-mass energy of root s = 4.6 GeV with the BESIII detector at the BEPCII collider, the absolute branching fraction of Lambda(+)(c) -> pK(S)(0)eta decays is measured for the first time to be B(Lambda(+)(c) -> pK(S)(0)eta) = (0.414 +/- 0.084 +/- 0.028)%, where the first uncertainty is statistical and the second is systematic. The result is compatible with a previous CLEO result on the relative branching fraction B(Lambda(+)(c) -> pK(S)(eta)(0))/B(Lambda(+)(c) -> pK(-)pi(+)), and consistent with theoretical predictions of SU(3) flavor symmetry. (C) 2021 The Author. Published by Elsevier B.V.Öğe Measurement of the Absolute Branching Fraction of Ds+ ? ?+?? via ?+ ? e+?e(?)over-bar?(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliUsing a dataset of 6.32 fb(-1) of e(+)e(-) annihilation data collected with the BESIII detector at center-of-mass energies between 4178 and 4226 MeV, we have measured the absolute branching fraction of the leptonic decay D-s(+) -> tau(+)nu(tau) via tau(+) -> e(+)nu(e)(nu) over bar (tau), and find B-Ds+(->tau+nu tau) = (5.27 +/- 0.10 +/- 0.12) x 10(-2), where the first uncertainty is statistical and the second is systematic. The precision is improved by a factor of 2 compared to the previous best measurement. Combining with f(Ds+) from lattice quantum chromodynamics calculations or the vertical bar V-cs vertical bar from the CKMfitter group, we extract vertical bar V-cs vertical bar = 0.978 +/- 0.009 +/- 0.012 and f(Ds+) = (251.1 +/- 2.4 +/- 3.0) MeV, respectively. Combining our result with the world averages of BDs+->tau+nu tau and BDs+->mu+nu mu, we obtain the ratio of the branching fractions BDs+->tau+nu tau/BDs+->mu+nu mu = 9.72 +/- 0.37, which is consistent with the standard model prediction of lepton flavor universality.Öğe Measurement of the absolute branching fraction of inclusive semielectronic Ds+ decays(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliWe 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.Öğe Measurement of the absolute branching fractions for purely leptonic Ds+ decays(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliWe report new measurements of the branching fraction B(Dv), where lis either mu or tau (-> pi), based on 6.32 fbof electron-positron annihilation data collected by the BESIII experiment at six center-of-mass energy points between 4.178 and 4.226 GeV. Simultaneously floating the Ds -> mu mu components yields B(D -> tau) = (5.21 +/- 0.25 +/- 0.17) x 102, B(D -> mu mu) (5.35 +/- 0.13 +/- 0.16) x 103, and the ratio of decay widths R = Gamma(D -> tau tau)/Gamma -> mu&m)= 9.73-0.58 +/- 0.36, where the first uncertainties are statistical and the second systematic. No evidence of CP asymmetry is observed in the decay rates Ds +/- -> mu +/- v mu and D +/- -> tau +/-= (+2.9 +/- 4.8 +/- 1.0)%. Constraining our measurement to the Standard Model expectation of lepton universality (R = 9.75), we find the more precise results B(D -> tau = (5.22 +/- 0.10 +/- 0.14) x 10-2and A(+/-) = (-0.1 +/- 1.9 +/- 1.0)%. Combining our results with inputs external to our analysis, we determine the C -> (S) over bar quark mixing matrix element, D+ decay constant, and ratio of the decay constants to be vertical bar V vertical bar = 0.973 +/- 0.009 +/- 0.014, f D+ = 249.9 +/- 2.4 +/- 3.5 MeV, and f D+ / f D = 1.232 +/- 0.035, respectively.Öğe Measurement of the Born cross sections for e+e- ? ?'?+ ?- a t center-of-mass energies between 2.00 and 3.08 GeV(Amer Physical Soc, 2021) Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Çetin, Serkant AliThe Born cross sections for the process e(+)e(-) -> eta'pi(+)pi(-) at different center-of-mass energies between 2.00 and 3.08 GeVare reported with improved precision from an analysis of data samples collected with the BESIII detector operating at the BEPCII storage ring. An obvious structure is observed in the Born cross section line shape. Fit as a Breit-Wigner resonance, it has a statistical significance of 6.3 sigma and a mass and width of M = (2111 +/- 43 +/- 25) MeV/c(2) and Gamma = (135 +/- 34 +/- 30) MeV, where the uncertainties are statistical and systematic, respectively. These measured resonance parameters agree with the measurements of BABAR in e(+)e(-) -> eta'pi(+)pi(-) and BESIII in e+e(-) -> omega pi(0) within two standard deviations.
