共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
《Physics letters. [Part B]》1987,184(4):410-416
We calculate the total and differential cross sections for the process e+e−→W+W− including the effects of the extra Z-boson coming from the E8⊗E8 superstring. It is pointed out that the observation of the total and differential cross sections can determine the relative sign of the Weinberg angle τw and the mixing angle τe between Z'0 and Z E. 相似文献
3.
Yu. M. Antipov V. A. Batarin V. A. Bessubov M. S. Bilenky N. P. Budanov D. S. Denisov O. V. Eroshin P. L. Frabetti Yu. P. Gorin Yu. A. Gornushkin V. G. Kartasheva P. A. Kulinich A. A. Nosdrin A. G. Olshevski F. Palombo A. I. Petrukhin R. V. Pirtzkhalava S. A. Polovnikov V. N. Roinishvili D. A. Stoianova A. V. Vishnevski 《Zeitschrift fur Physik C Particles and Fields》1989,42(2):185-187
In the diffraction dissociation of π? into μ+μ?π? on a Cu nucleus at 50 GeV/c, the cross section \(\sigma _{\mu ^ + \mu ^ - \pi ^ - } \) for the 1+S(ρ0π) wave was measured. The branching ratio of ρ0→μ+μ? could be calculated from the ratio of this and the corresponding cross sections in the diffraction dissociation of π? into π+π?π?. The obtained value \(BR_{\rho ^0 \to \mu ^ + \mu ^ - } = (4.6 \pm 0.2_{stat^ \pm } \pm 0.2_{syst} )10^{ - 5} \) is in good agreement with the branching ratio \(BR_{\rho ^0 \to e^ + e^ - } \) , as expected ifeμ universality holds. 相似文献
4.
5.
6.
《Physics letters. [Part B]》1988,205(4):573-575
The reaction e+e−→γW+W− has been studied at TeV energies as a possible background to Higgs production. Our results differ significantly from previous estimates and show that the ratio signal/background can be kept reasonably large. 相似文献
7.
A. I. Él'-Gavkhari 《Russian Physics Journal》1981,24(1):92-95
Polarization effects in the inclusive process e– + p e– + + X due to the neutral current are studied in the framework of the Weinberg-Salam model. Expressions for the asymmetry parameters and the degree of circular polarization of the photons are obtained in the quark-parton picture. It is shown that measurement of such quantities gives additional information about the quark structure of the hadronic weak neutral current.Paper presented at the scientific session of the nuclear physics branch, USSR Academy of Sciences and the Moscow State University on Electromagnetic and Weak Interactions (Moscow, January 16–20, 1979).Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 96–99, January, 1981. 相似文献
8.
A. Antonelli R. Baldini M. E. Biagini S. Calcaterra M. Schioppa D. Bisello G. Busetto A. Castro M. Nigro L. Pescara P. Sartori L. Stanco J. E. Augustin L. Ayach G. Cosme F. Couchot F. Fulda G. Grosdidier B. Jean-Marie V. Lepeltier G. Szklarz 《Zeitschrift fur Physik C Particles and Fields》1992,56(1):15-19
The cross sections fore + e ?→π + π ? π 0 ande + e ?→ωπ + π ? have been measured in the 1.35 ≦ \(\sqrt s \) ≦2.4 GeV range from 1900 nb?1 collected by DM2 at DCI. The second process proceeds via a resonant state at ≈- 1660 MeV/c2, ≈- 280 MeV/c2 wide. The first one is larger than a VDM extrapolation from the ω-? peaks and, although does not show any clear structure, is compatible with the presence of the above resonance. 相似文献
9.
10.
11.
12.
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
13.
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
14.
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
15.
Stefano Moretti 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):653-667
The complete matrix element for e + e? → bb?W+ W? is computed at tree-level within the Minimal Supersymmetric Standard Model. Rates of interest to phenomenological analyses at the Next Linear Collider are given. In particular, we study:
- ? tt? production and decay tt? →(bW +)(b?W ?)
- ? ZH production followed by Z → bb? and H → W + W?
- ? AH production followed by A→ bb? and H → W + W?
- ? hW + W? production followed by h→ bb?.
16.
D. Anchishkin 《Acta Physica Hungarica A》2006,27(4):403-411
We revise the μ+μ? and $q\bar q$ annihilation mechanisms of dilepton production during relativistic nuclear collisions. We focus on the modifications caused by the specific features of in-medium pion and quark states rather than by medium modification of the ρ-meson spectral density. The main ingreditent emerging in our approach is a form-factor of the multi-pion (multi-quark) system. Replacing the usual delta-function the form-factor plays the role of distribution which, in some sense, “connects” the total 4-momenta of the annihilating and outgoing particles. The difference between the c.m.s. velocities attributed to annihilating and outgoing particles is a particular consequence of this replacement and results in the appearance of a new factor in the formula for the lepton pair production rate. We obtained that the form-factor of the multi-pion (multi-quark) system causes broadening of the rate which is most pronounced for small invariant masses, in particular, we obtain a growth of the rate for the invariant masses below two masses of the annihilating particles. 相似文献
17.
A. A. Likhoded 《Physics of Atomic Nuclei》2008,71(3):539-544
The process e + e ? → τ + τ ? v $ \bar \nu $ , which is highly sensitive to anomalous Hττ interaction, is investigated within a model involving a new pseudoscalar Higgs boson. It is shown that the problem of separating the contributions of the scalar and pseudoscalar states of the Higgs boson can be solved via taking into account the polarizations of final-state particles. The inclusion of cascade tau-lepton decays makes it possible to determine reliably the CP state of the Higgs boson and to pinpoint the magnitude and sign of respective coupling constants. 相似文献
18.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov 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 S. I. Serednyakov Z. K. Silagadze A. N. Skrinskii Yu. M. Shatunov 《Journal of Experimental and Theoretical Physics》2011,113(3):433-434
We report on the results of the search for the e + e ? → K ± K S π ? process. Data with an integrated luminosity of 1.36 pb?1 collected in experiment with a spherical neutral detector (SND) on the VEPP-2M e + e ? collider in the energy range from 1.36 to 1.38 GeV have been analyzed. The upper limits of the σ < 150 pb cross sections of the sought process have been established for an energy of 1.37 GeV at a confidence level of 90%. 相似文献
19.
20.
《Nuclear Physics B》1988,309(2):221-258
We examine one-loop radiative corrections to e+e−→W+W− in the standard model with one Higgs doublet, concentrating on the effects of very heavy fermions. These disturb the delicate unitarity cancellation between s- and t-channel diagrams, raising the cross section even well below the fermion threshold and giving a clear experimental signature for the heavy sector. 相似文献