共查询到20条相似文献,搜索用时 15 毫秒
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M.N. Achasov S.E. Baru A.V. Bozhenok A.D. Bukin D.A. Bukin S.V. Burdin T.V. Dimova S.I. Dolinsky V.P. Druzhinin M.S. Dubrovin I.A. Gaponenko V.B. Golubev V.N. Ivanchenko A.A. Korol S.V. Koshuba A.P. Lysenko I.N. Nesterenko E.V. Pakhtusova S.I. Serednyakov V.V. Shary Yu.M. Shatunov V.A. Sidorov Z.K. Silagadze Yu.V. Usov 《The European Physical Journal C - Particles and Fields》2000,12(3):369-374
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S. Fajfer P. Singer J. Zupan 《The European Physical Journal C - Particles and Fields》2003,27(2):201-218
We present a calculation of the rare decay modes and in the framework of the standard model. For the short distance part we have derived QCD corrections to the Wilson coefficients
involved, including C9. The latter is found to be strongly suppressed by the corrections, leading to diminished values for the branching ratios in the 10-10 range. Within SM the exclusive decays are dominated by long distance effects. Non-resonant contributions are estimated using
heavy quark and chiral symmetries to be at the level of , compared to the contributions arising from , with . The total SM branching ratio is predicted to be in the range (1-. We also consider contributions coming from MSSM with and without R parity conservation. The effects from MSSM are significant only for the R parity violating case. Such contributions enhance the branching ratio to , based on appropriately allowed values for C9 and C10. This selects as a possible probe of new physics.
Received: 25 October 2002 / Published online: 24 January 2003 相似文献
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We study the differential branching ratio, the branching ratio and the forward-backward asymmetry for exclusive decay in the two Higgs doublet model. We analyze the dependences of these quantities on the model parameters and show that
these observables are highly sensitive to new physics and hence may provide a powerful probe of the SM and beyond.
Received: 27 March 2002 / Revised version: 3 July 2002 / Published online: 20 September 2002
RID="a"
ID="a" e-mail: gurerk@newton.physics.metu.edu.tr
RID="b"
ID="b" e-mail: gsevgur@metu.edu.tr 相似文献
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S. R. Gevorkyan M. H. Misheva 《The European Physical Journal C - Particles and Fields》2014,74(5):1-5
The rare $K^\pm \rightarrow \pi ^\pm \pi ^0 e^+e^-$ decay, currently under analysis by the NA62 Collaboration, is considered. We have followed two theoretical approaches to calculate the differential decay width—in the kaon rest frame, where we use Cabibbo–Maksymowicz variables, and in the center-of-mass system of the lepton pair. The latter essentially simplifies the computations. A comparison between the two approaches has been performed. We have also found the dependencies of the differential decay rate as a function of the virtual photon and dipion system masses. 相似文献
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The reaction $e^ + e^ - \to \gamma \pi ^0 \to \gamma v\overline v $ is considered. It is shown that this reaction possesses a clear signature, producing in the resonance region practically monochromatic photons, which can easily be distinguished from background bremsstrahlung photons. Since the cross section of the reaction is proportional to the square of the neutrino mass, such a reaction can be used as a probe for neutrino mass. 相似文献
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M.N. Achasov A.V. Berdyugin A.V. Bozhenok D.A. Bukin S.V. Burdin T.V. Dimova V.P. Druzhinin M.S. Dubrovin I.A. Gaponenko V.B. Golubev V.N. Ivanchenko A.A. Korol S.V. Koshuba E.V. Pakhtusova A.A. Salnikov S.I. Serednyakov V.V. Shary Yu.M. Shatunov V.A. Sidorov Z.K. Silagadze 《The European Physical Journal C - Particles and Fields》2000,12(1):25-33
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Y. Kiyo J. Kodaira K. Morii 《The European Physical Journal C - Particles and Fields》2000,18(2):327-332
We discuss top quark production and its subsequent decay as used for searching new physics at lepton colliders. The angular
dependence of the decay leptons is calculated including both QCD corrections and anomalous couplings. The off-diagonal spin basis for the top and anti-top quarks is shown to be useful to probe the anomalous couplings.
Received: 11 August 2000 / Published online: 27 November 2000 相似文献
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S. A. Akimenko V. N. Bolotov G. I. Britvich K. V. Datsko V. A. Duk A. P. Filin E. N. Gushchin A. V. Inyakin V. A. Khmelnikov A. S. Konstantinov V. F. Konstantinov I. Yu. Korolkov S. V. Laptev V. A. Lebedev V. M. Leontiev A. E. Mazurov V. P. Novikov V. F. Obraztsov V. A. Polyakov A. Yu. Polyarush V. E. Postoev V. I. Romanovsky V. I. Shelikhov O. G. Tchikilev V. A. Uvarov O. P. Yushchenko 《Physics of Atomic Nuclei》2007,70(4):702-708
Results of study of the $K^ - \to \pi ^0 e^ - \overline \nu \gamma $ decay at the ISTRA+ setup are presented. We observed 4476 events of this decay. The branching ratio is found to be $R = \frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (1.81±0.03(stat.)±0.07(syst.)) × 10?2 for E*γ > 10 MeV and θ*eγ > 10°. For comparison with the previous experiment the branching ratio with cuts E*γ > 10 MeV, 0.6 < cos θ*eγ < 0.9 is calculated: R = $\frac{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e \gamma )}}{{Br(K^ - \to \pi ^0 e^ - \overline \nu _e )}}$ = (0.47±0.02(stat.) ± 0.03(syst.)) × 10?2. For the cuts E*γ > 30 MeV and θ*eγ > 20°, used in most theoretical papers, Br = (3.06 ± 0.09(stat.) ± 0.14(syst.)) × 10?4. For the asymmetry we get A ξ = ?0.015 ± 0.021. At present it is the best estimate of this asymmetry. 相似文献
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Existence of discrepancies between experimental data and Monte Carlo predictions for angular distributions in four-jet production
via annihilation has been known for some time at LEP1. As such QCD processes constitute significant backgrounds to -jet production at LEP2, we consider the possibility that an erroneous modelling of the helicity structure of the final-state
partons could affect the accuracy of experimental measurements of the boson parameters.
Received: 21 September 1998 / Revised version: 20 January 1999 / Published online: 22 March 1999 相似文献
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J. Bartels M. A. Braun G. P. Vacca 《The European Physical Journal C - Particles and Fields》2004,33(4):511-521
The rates of inclusive photo- and electroproduction of the
meson:
are calculated in the triple Regge region, integrated over the diffractive mass X. For the Regge exchanges we use the hard pomeron and odderon, both being calculated in the framework of perturbative QCD. The integrated cross section depends upon the coupling of the BFKL pomeron to two C = -1 odderons, and it is found to be of the order of 60 pb for photoproduction and 1.5 pb at Q2 = 25 GeV2.Received: 16 April 2003, Published online: 25 February 2004 相似文献