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2016 Vol. 46, No. 4

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Overview of the CMD-3 results at the VEPP-2000 e+e- collider
FEDOTOVICH G.V., AMIRKHANOV A.N., ANISENKOV A.V., AULCHENKO V.M., BANZAROV V.S.
2016, 46(4): 259-271. doi: 10.3969/j.issn.0253-2778.2016.04.001
Article Views:263 Full article PDF
Abstract:
The CMD-3 detector has been taking data since December 2010 at the VEPP-2000 electron-positron collider. The collected data sample corresponds to about 60 inverse picobarn of integrated luminosity in the c.m. energy range from 032 up to 2 GeV. Preliminary results of the analysis of various hadronic cross sections, in particular, e+e-→π+π-, π+π-π0, KLKS, K+K-, ηγ, 3(π+π-), 2(π+π-π0), K+K-π+π-, K+K-η, K+K-π0, ηπ+π-, ωπ+π- and ω→π0e+e- are presented. The processes with multihadron final states have several intermediate states which must be taken into account to correctly describe the angular and invariant mass distributions as well as cross section energy dependence.
Study of e+ e- annihilation into hadrons below 2 GeV with SND
DIMOVA T.V., ACHASOV M.N., BARNYAKOV A.Yu., BELOBORODOV K.I., BERDYUGIN A.V., BOGDANCHIKOV A.G., BOTOV A.A., DRUZHININ V.P., GOLUBEV V.B., KARDAPOLTSEV L.V., KHARLAMOV A.G., KOOP I.A., KOROL A.A., KOSHUBA S.V., KOVRIZHIN D.P., KUPICH A.S., MARTIN K.A., MUCHNOI N.Yu., OBRAZOVSKY A.E., PAKHTUSOVA E.V., SEREDNYAKOV S.I., SHATUNOV Yu.M., SHTOL D.A., SILAGADZE Z.K., SURIN I.K., VASILJIEV A.V.
2016, 46(4): 272-278. doi: 10.3969/j.issn.0253-2778.2016.04.002
Article Views:235 Full article PDF
Abstract:
Beginning from 2010 experiments with the SND detector were carried out at the e+e- -collider VEPP-2000 in the energy range 03~2.0 GeV. New results on the study of the processes of e+e- annihilation into hadrons based on data collected in these experiments are presented.
Experimental study of the e+e-→K+K- process cross section with the SND detector at the VEPP-2000 e+e- collider
BELOBORODOV K.I. (for the SND Collaboration)
2016, 46(4): 279-281. doi: 10.3969/j.issn.0253-2778.2016.04.003
Article Views:239 Full article PDF
Abstract:
In experiments at the VEPP-2000 e+e- collider with the SND detector the e+e-→K+K- process cross section has been measured in the energy range 105~20 GeV. Its value was found to be consistent with previous measurements.
Recent results from the KEDR detector at the VEPP-4M
TODYSHEV K.Yu. (for the KEDR collaboration)
2016, 46(4): 282-285. doi: 10.3969/j.issn.0253-2778.2016.04.004
Article Views:252 Full article PDF
Abstract:
The result is presented of precise measurement the values of Ruds and R at seven points of the center-of-mass energy between 312 and 372 GeV based on the data collected with the KEDR detector at the VEPP-4M e+e- collider in Novosibirsk. Also present is the preliminary result of determination of the product of the electron partial width by the branching fraction into hadrons of J/ψ resonance.
Results on hadronic cross sections at KLOE
DE LEO V. (on behalf of the KLOE
2016, 46(4): 286-291. doi: 10.3969/j.issn.0253-2778.2016.04.005
Article Views:258 Full article PDF
Abstract:
The precise determination of the e+e-→π+π-(γ) cross section is particularly important to evaluate the hadronic loop contribution to the SM calculation of the muon (g-2), where a long-standing 3σ discrepancy with the direct experimental determination is observed. The KLOE experiment studied the production of π+π- in the ISR channel and published three measurements (in 2005, 2008 and 2012) of the π+π- cross section with the ISR photon emitted at small angles and an independent measurement (in 2010) with the ISR photon emitted at large angles and using data at a collision energy of 1 GeV. The combination of the last analysis (KLOE12) with two previously published (KLOE08, KLOE10) together with the preliminary fit by using the Gounaris-Sakurai model is presented.
Status of R Scan at BESIII
LI Yingtian, HU Haiming (for the BESIII Collaboration)
2016, 46(4): 292-300. doi: 10.3969/j.issn.0253-2778.2016.04.006
Article Views:243 Full article PDF
Abstract:
The data samples for the measurement of R values, hadron form factors, the line-shape scan of the high mass charmonium family and new states have been taken in the full energy region that BEPCII can reach, namely between 20 and 46 GeV. The present status of R value measurement is briefly reviewed.
BESIII π+π- form factor measurement and perspective of π+π-π0
WANG Yaqian (for the BESIII Collaboration)
2016, 46(4): 301-307. doi: 10.3969/j.issn.0253-2778.2016.04.007
Article Views:310 Full article PDF
Abstract:
The cross section is measured of e+e-→π+π- in the energy range between 600 and 900 MeV/c2 with a 2.93 fb-1 data set taken at the center-of-mass energy 3773 GeV at BESIII. The initial state radiation technique is used, and the total systematic uncertainty is estimated to be 09%. The squared form factor |Fπ|2 is extracted, and comparisons are made with results from both KLOE and BaBar. The two-pion contribution to the hadronic vacuum polarization contribution to (g-2)μ is calculated to be aππ,LOμ(600~900 MeV/c2)=(3682±25stat±33sys)×10-10.
Threshold phenomenology of nucleon form factors
BALDINI FERROLI Rinaldo, PACETTI Simone, TOMASI-GUSTAFSSON Egle
2016, 46(4): 308-315. doi: 10.3969/j.issn.0253-2778.2016.04.008
Article Views:262 Full article PDF
Abstract:
The complete knowledge of nucleon form factors is a mandatory pass to deeply understand the dynamics of strong interaction at regimes where QCD is still non perturbative. Phenomenology, i.e., the description of the data by means models based of first principles and depending on physical quantities, represents one of the most powerful tools to attain such a degree of knowledge.
Experiments on form factors
JOHANSSON Tord
2016, 46(4): 316-322. doi: 10.3969/j.issn.0253-2778.2016.04.009
Article Views:272 Full article PDF
Abstract:
The experimental situation for ground state baryon electromagnetic form factors in the space-like and the time-like regions is reviewed together with an outlook.
Preliminary results on pion form factor at CMD-3
AKHMETSHIN R.R., AMIRKHANOV A.N., ANISENKOV A.V., AULCHENKO V.M., BANZAROV V.Sh.
2016, 46(4): 323-330. doi: 10.3969/j.issn.0253-2778.2016.04.010
Article Views:222 Full article PDF
Abstract:
The CMD-3 detector has been successfully collecting data at the electron-positron collider VEPP-2000 since December 2010. The first scan below 1 GeV for a π+π- measurement was performed in 2013. The collected data sample corresponds to about 18 pb-1 of integrated luminosity in this energy range. Analysis of the e+e-→π+π- cross section is in progress. Preliminary results of this measurement are presented.
Measurement of the timelike neutron and proton form factors at VEPP-2000
KOROL A.A. (for the CMD- and SND Collaborations)
2016, 46(4): 331-336. doi: 10.3969/j.issn.0253-2778.2016.04.011
Article Views:258 Full article PDF
Abstract:
Results are presented of the study of the e+e-→n and e+e-→p reactions in the energy range from the nucleons production threshold up to 2 GeV. The measurements have been performed at the VEPP-2000 e+e- collider with the SND and CMD-3 detectors using the events collected during the data taking runs of 2011 and 2012. Also discussed here are the obtained electromagnetic form factors of nucleons and future plans of these results improvement.
Baryon form factors at BESIII
WANG Yadi (for BESIII Collaboration)
2016, 46(4): 337-342. doi: 10.3969/j.issn.0253-2778.2016.04.012
Article Views:238 Full article PDF
Abstract:
With the data collected by the BESIII detector at the BEPCII e+e- collider in 2011~2013, the cross section of e+e-→p at 12 center-of-mass energies from 2.232 4 to 3.671 0 GeV was measured. The prospect of new results with the larger e+e- scanning data, collected in 2014 and 2015, is reported. The measurement of p form factor with ISR has also been studied using both tagged and untagged methods. With the good performances of BESIII, the feasibility of n form factor measurement in both ISR mode and scan mode is also reported. The preliminary but unexpected result of form factors of Λ measurement is shown, as well as the expectation from the data collected at the threshold of e+e-→Λcc. Also expected from these data is a measurement of form factors of all the other hyperons by BESIII.
Meson transition form factor studies at WASA-at-COSY
KUPSC A. (for the WASA-at-COSY Collaboration)
2016, 46(4): 343-346. doi: 10.3969/j.issn.0253-2778.2016.04.013
Article Views:238 Full article PDF
Abstract:
Status of the light neutral meson (π0, η and ω) studies carried out by the WASA-at-COSY collaboration is presented, with an emphasis is on the processes related to the light meson transition form factors. The recent results on the η meson branching ratios are presented.

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