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1.
V. M. Aulchenko M. N. Achasov S. E. Baru K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin A. V. Vasilev V. B. Golubev T. V. Dimova V. P. Druzhinin V. N. Ivanchenko I. A. Koop A. A. Korol S. V. Koshuba A. P. Lysenko A. V. Otboev E. V. Pakhtusova A. A. Salnikov S. I. Serednyakov V. A. Sidorov Z. K. Silagadze V. V. Shary Yu. M. Shatunov 《Journal of Experimental and Theoretical Physics》2003,97(1):24-33
The process e + e ? → η′γ, η′ → η π0π0, η → γγ is investigated by an SND detector in experiment on a VEPP-2M equipment with colliding electron-positron beams. The analysis of experimental data yields a value of B(? → η′γ)=(6.7 ?4.2 +5.0 ±1.5)×10?5 for the decay probability. Taking into account a previous measurement of this quantity by an SND detector in the decay channel η′ → π+π?η, one finally obtains B(?→η ′γ)=(6.7 ?2.4 +2.8 ±0.8)×10?5. 相似文献
2.
V. M. Aulchenko M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin S. V. Burdin A. V. Vasiljev I. A. Gaponenko V. B. Golubev T. V. Dimova A. A. Drozdetsky V. P. Druzhinin M. S. Dubrovin P. M. Ivanov V. N. Ivanchenko I. A. Koop A. A. Korol S. V. Koshuba G. A. Kukartsev A. P. Lysenko A. V. Otboev E. V. Pakhtusova A. A. Salnikov S. I. Serednyakov V. A. Sidorov Z. K. Silagadze A. N. Skrinsky V. V. Shary Yu. M. Shatunov 《Journal of Experimental and Theoretical Physics》2000,90(6):927-938
The reaction e + e ?→ωπ0 near a Φ resonance was studied with a spherical neutral detector at VEPP-2M e + e ? collider. Both main modes of decay of a ω meson were investigated: ω→π+π?π0 and ω→π 0γ. The probability of decay Φ→ωπ0 was obtained from the magnitude of the interference wave in the cross section for the reaction e + e ?→ωπ0→ π+π?π0π0: B(Φ→ωπ0) = (5.5 ?1.4 +1.6 ±0.3) ×10?5. The ratio of the partial widths of the ω meson was obtained from the ratio of the cross sections for the two modes: Γ(ω→π0γ )/Γ(ω→π+π?π0) = 0.0994 ± 0.0036 ± 0.0038. 相似文献
3.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin S. V. Burdin A. V. Vasil’ev D. I. Ganyushin V. B. Golubev T. V. Dimova A. A. Drozdetskii V. P. Druzhinin P. M. Ivanov V. N. Ivanchenko A. A. Korol’ M. S. Korostelev S. V. Koshuba G. A. Kukartsev E. V. Pakhtusova A. A. Polunin E. É. Pyata A. A. Sal’nikov S. I. Serednyakov V. A. Sidorov Z. K. Silagadze V. V. Sharyi Yu. M. Shatunov 《JETP Letters》2000,71(9):355-358
The e + e ?→π0π0 γreaction was studied in the energy range 0.36–0.97 GeV on a VEPP-2M e + e ? collider with an SND detector. The decay probabilities were found to be B(ω→ π0π0γ)= (7.8 ±2.7±2.0)×10?5 and B(π→ π0π0γ)= (4.8 ?1.8 +3.4 ±0.2)×10?5. 相似文献
4.
H.J. Behrend Ch. Chen H. Fenner J.H. Field V. Schr?der H. Sindt G. DAgostini W.-D. Apel S. Banerjee J. Bodenkamp D. Chrobaczek J. Engler G. Flügge D.C. Fries W. Fues K. Gamerdinger G. Hopp F. Pierre 《Physics letters. [Part B]》1982,114(5):378-382
From the two-photon exchange processes e+e? → e+e?η' (958) → e+e??0γ and e+e? → e+e?A2 (1310) → e+e?π+π?π0 observed using the CELLO detector at PETRA the radiative widths of the η' and A2 have been determined with the results: Γγγ(η') = 5.4 ± 1.0[stat.] ± 0.7[syst.] keV; Γγγ(A2) = 0.59 ± 0.14[stat.] ?0.08+0.31[syst.] keV. 相似文献
5.
M. N. Achasov S. E. Baru K. I. Beloborodov A. V. Berdyugin A. V. Bozhenok A. G. Bogdanchikov D. A. Bukin S. V. Burdin A. V. Vasil’ev Yu. S. Velikzhanin T. V. Dimova V. P. Druzhinin M. S. Dubrovin D. I. Ganyushin I. A. Gaponenko V. B. Golubev V. N. Ivanchenko I. A. Koop A. A. Korol’ S. V. Koshuba G. A. Kukartsev E. V. Pakhtusova A. A. Sal’nikov S. I. Serednyakov V. V. Sharyi Yu. M. Shatunov V. A. Sidorov Z. K. Silagadze 《JETP Letters》2000,72(6):282-285
The e + e ?→ηγ→7γ process was studied in the energy range 2E=600–1060 MeV with an SND detector on a VEPP-2M e + e ? collider. The decay branching ratios B(φ→ηγ)=(1.353±0.011±0.052)×10?2, B(ω→ηγ)=(4.62±0.71±0.18)×10?4, and B(ρ→ηγ)=(2.73±0.31±0.15)×10?4 were measured. 相似文献
6.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin T. V. Dimova V. P. Druzhinin V. B. Golubev I. A. Koop A. A. Korol S. V. Koshuba A. P. Lysenko A. V. Otboev E. V. Pakhtusova S. I. Serednyakov Yu. M. Shatunov V. A. Sidorov Z. K. Silagadze A. N. Skrinsky Yu. A. Tikhonov A. V. Vasiljev 《Journal of Experimental and Theoretical Physics》2005,101(6):1053-1070
The cross section of the process e + e ? → π+π? was measured in the spherical neutral detector experiment at the VEPP-2M collider in the energy region $400 < \sqrt s < 1000 MeV$ . This measurement was based on about 12.4 × 106 selected collinear events, which include 7.4 × 106 e + e ? → e + e ?, 4.5 × 106 e + e ? → π+π?, and 0.5 × 106 e + e ? → μ+μ? selected events. The systematic uncertainty of cross section determination is 1.3%. The ρ-meson parameters were determined as m ρ = 774.9±0.4±0.5 MeV, Γ ρ = 146.5±0.8±1.5 MeV, and σ(ρ → π+π?) = 1220 ± 7 ± 16 nb and the parameters of the G-parity suppressed decay ω → π+π? as σ(ω → π+π?) = 29.9 ± 1.4 ± 1.0 nb and φρω = 113.5±1.3±1.7°. 相似文献
7.
H. Albrecht R. Childers C.W. Darden G. Drews H. Hasemann E. McCliment W. Schmidt-Parzefall H. Schröder H.D. Schulz F. Selonke E. Steinmann R. Wurth W. Hofmann A. Markees D. Wegener K.R. Schubert J. Stiewe R. Waldi Yu. Zaitsev 《Physics letters. [Part B]》1980,93(4):500-504
Using the DASP detector at the DESY storage ring DORIS we have continued measuring e+e? annihilations near and on the ?(9.46) resonance. From the cross sections for e+e? → μ+μ? and e+e? → hadrons we obtain a μ+μ? branching ratio for the ?(9.46) of (2.9 ± 1.3 ± 0.5) %, a leptonic width and a total width of (47?15+37 keV. 相似文献
8.
D. Bollini P. Giusti T. Massam L. Monari F. Palmonari G. Valenti A. Zichichi 《Physics letters. [Part B]》1976,61(1):96-98
The analysis of the reaction e+e?→π+π? measured at the e+e? colliding beam machine ADONE shows that, if ?′ and ?″ exist, the cross sections compare as follows (taking the ? as the reference point): : σ(e+e? → ?′ → π+π?): σ(e+e? → ?″ → π+π?) = 1: (7 ± 4) × 10?3: (1 ± 5) × 10?4. The square of the product of their couplings to the photon (γ?) and the γγ system (g?ππ) are derived. 相似文献
9.
《Zeitschrift fur Physik C Particles and Fields》1997,73(1):73-84
The reaction γp →ωp(ω → π+π?π0 and π0 → γ γ) has been studied in ep interactions using the ZEUS detector at photon-proton centre-of-mass energies between 70 and 90GeV and ∣t∣ < 0.6GeV2, where t is the squared four momentum transferred at the proton vertex. The elastic ω photoproduction cross section has been measured to be σγp → ωp = 1.21 ±0.12 ±0.23 μb. The differential cross section dσγp→ωp/d¦t¦ has an exponential shape e?b∣t∣ with a slope b =10.0 ± 1.2 ± 1.3 GeV?2. The angular distributions of the decay pions are consistent with s-channel helicity conservation. When compared to low energy data, the features of ω photoproduction as measured at HERA energies are in agreement with those of a soft diffractive process. Previous measurements of the ρ0 and ? photoproduction cross sections at HERA show a similar behaviour. 相似文献
10.
P. Brauel Th. Canzler D. Cords G. Felst G. Grindhammer W.-D. Kollmann H. Krehbiel M. Schädlich 《Physics letters. [Part B]》1976,61(1):110-112
The reaction γ + Be → e+e? + X was studied with a bremsstrahlung beam of 7.2 GeV maximum energy. For invariant pair masses 1.8 ? Me+e? 2.6 GeV, no evidence for narrow resonance of width smaller than 40 MeV was found. For the mass interval 2.1 ? Me+e? ? 2.6 GeV, we obtained an upper limit of σ · Be+e? < 2 × 10?35 cm2/nucleon (90% confidence level), assuming a production mechanism similar to the θ (1019) meson. 相似文献
11.
J. Fischer P. Extermann O. Guisan R. Mermod L. Rosselet R. Sachot P. Bloch G. Bunce B. Devaux A.M. Diamant-Berger N. Do-Duc G. Marel R. Turlay 《Physics letters. [Part B]》1978,73(3):359-363
Using a magnetic spectrometer, we have studied 30 000 π0 → e+e?γ events coming from Kπ2+ decays in flight. We find a positive value for the slope of the neutral-pion electromagnetic form factor: a = +0.10 ± 0.03 (or a = +0.05 ± 0.03 without radiative corrections). This value is higher than the predictions of vector meson models. 相似文献
12.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin S. V. Burdin A. A. Valishev A. V. Vasil’ev V. B. Golubev T. V. Dimova V. P. Druzhinin P. M. Ivanov V. N. Ivanchenko A. A. Korol’ S. V. Koshuba A. A. Mamutkin A. V. Otboev E. V. Pakhtusova A. A. Sal’nikov S. I. Serednyakov V. A. Sidorov Z. K. Silagadze A. N. Skrinskii A. G. Skripkin V. V. Sharyi Yu. M. Shatunov 《JETP Letters》2002,75(9):449-451
The measurement of the ? → π0 e + e ? conversion decay probability on the SND detector at the VEPP-2M e + e ? collider gave the value Br(? → π 0 e + e ?) = (1.01 ± 0.28 ± 0.29) × 10?5. 相似文献
13.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. D. Bukin D. A. Bukin A. V. Vasil’ev V. B. Golubev T. V. Dimova V. P. Druzhinin I. A. Koop A. A. Korol’ S. V. Koshuba E. V. Pakhtusova E. A. Perevedentsev S. I. Serednyakov Z. K. Silagadze A. N. Skrinsky Yu. M. Shatunov 《Journal of Experimental and Theoretical Physics》2008,107(1):61-68
The e + e ? → ω, ρ → π0 e + e ? processes have been investigated in the experiments with Spherical Neutral Detector at the VEPP-2M e + e ? collider. The measurements provide the probability ?(ω → π0 e + e ?) = (0.761 ± 0.053 ± 0.064) × 10?3 of the ω → π0 e + e g- conversion decay and the upper limit ?(ρ → π0 e + e ?) < 1.2 × 10?5 (at 90% CL) for the ρ → π0 e + e ? decay. The transition form factor was measured at three values of the 4-momentum transfer squared. 相似文献
14.
W. Braunschweig C.L. Jordan U. Martyn H.G. Sander D. Schmitz W. Sturm W. Wallraff K. Berkelman D. Cords R. Felst E. Gadermann G. Grindhammer H. Hultsching P. Joos W. Koch U. Kötz H. Krehbiel D. Kreinick S. Yamada 《Physics letters. [Part B]》1975,53(5):491-494
We have measured collinear and nearly collinear photon pairs from e+e? annihilation at total energies covering the resonance at 3100 MeV. The observed cross section is in good agreement with the e+e? → γγ cross section expected from quantum electrodynamics. Upper limits for the decay modes (3100) → γγ, πOγ and other modes are derived. 相似文献
15.
C.W. Darden H. Hasemann A. Krolzig W. Schmidt-Parzefall H. Schröder H.D. Schulz F. Selonke E. Steinmann R. Wurth W. Hofmann D. Wegener H. Albrecht K.R. Schubert P. Böckmann L. Jönsson 《Physics letters. [Part B]》1978,76(2):246-248
We observe a narrow resonance in the reaction e+e? → hadrons using the DASP detector at the DORIS storage ring. The mass is found to be (9.46 ± 0.01) GeV and the observed width is compatible with the storage ring resolution of ±8 MeV. The energy-integrated cross section results in an electronic width Γee = (1.3 ± 0.4) keV. 相似文献
16.
L. Baum M. Block A. Böhm F. Ceradini D. Dibitonto J. Irion A. Kernan J. Layter F. Muller A. Nakkasyan B. Naroska F. Navach M. Nussbaum A. Orkin-Lecourtois C. Rubbia M. Sachwitz D. Schinzel H. Seebrunner R. Wojslaw 《Physics letters. [Part B]》1977,68(3):279-282
A search for the reaction p+p → e±μ±+X at the CERN ISR gave no evidence for this process. Upper limits for e±μ?/e+- are presented and are related to the branching fraction for leptonic decay of D(1.87). 相似文献
17.
As a possible explanation of the SLAC anomalous eμ events, we computed the cross section for e+ + e? → V+ + V? → μ± + e± + neutrinos, taking into account the spin correlations of V±. If one assumes that the vector meson has an anomalous magnetic moment (κ ≈ 1), the spin effects are considerable. The V± production hypothesis seems to be a viable alternative to that of the heavy lepton production. 相似文献
18.
M.R. Jane P. Grannis B.D. Jones N.H. Lipman D.P. Owen V.Z. Peterson W.T. Toner E.H. Bellamy M.G. Green J. Kirkby C. Solomonides J.A. Strong D.H. Thomas 《Physics letters. [Part B]》1975,59(1):103-105
In an optical spark chamber experiment we have obtained a sample of 80 eta Dalitz decays (η → e+e?γ) and have measured the eta electromagnetic form factor to be F(X) = 1.0?(0.22 ±0.45)X, where X=Mee2/Mη2, and the branching ratio (η→e+e?γ/(η→π+π?π0)= (0.0082 ± 0.0020). 相似文献
19.
W. Braunschweig H.-U. Martyn H.G. Sander D. Schmitz W. Sturm W. Wallraff K. Berkelman D. Cords R. Felst E. Gadermann H. Hultschig P. Joos W. Koch U. Kötz H. Krehbiel D. Kreinick W.A. McNeely K.C. Moffeit S. Yamada 《Physics letters. [Part B]》1977,67(2):243-248
The three photon final state produced in e+e? collisions has been measured at the mass of the resonance using the nonmagnetic part of the double arm spectrometer DASP. The decays and πoγ were observed and their branching ratios are given. A four standard deviation signal was observed in the γγ mass spectrum at a mass of (2.83 ± 0.03) GeV. An upper limit is given for the direct decay . 相似文献
20.
D.P. Barber U. Becker H. Benda A. Boehm J.G. Branson J. Bron D. Buikman J. Burger C.C. Chang H.S. Chen M. Chen C.P. Cheng Y.S. Chu R. Clare P. Duinker G.Y. Fang H. Fesefeldt D. Fong R.Y. Zhu 《Physics letters. [Part B]》1979,85(4):463-466
We report on the results of the study of e+e? collisions at the highest PETRA energy of √s = 31.57 GeV, using the 4π sr, electromagnetic and calorimetric detector Mark J. Based on 88 hadron events, and an integrated luminosity of 243 nb?1 we obtain R = σ(e+e? → hadrons)/σ(e+e? → μ+μ?) = 4.0 ± 0.5 (statistical) ± 6 (systematic). The R value, the measured thrust distribution and average spherocity show no evidence for the production of new quark flavors. 相似文献