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1.
《Physics letters. [Part B]》1987,184(1):114-118
We compare the pT dependence of pion, kaon and proton production cross sections in the central rapidity region in e+e annihilation events and in proton-proton collisions at ISR energies. We find similarities both in the pT dependence of cross sections and in the particle composition as a function of pT, in agreement with the hypothesis of a universal mechanism of particle production.  相似文献   

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K ±e ± νπ 0 decays have been studied using the KMN setup at the Institute for High Energy Physics (Protvino). The experiment has been performed in the 36-GeV/c hadron beams of the IHEP accelerator. The accumulated data allow us to select ~1.08M candidates for K e3 decays. Analyzing the Dalitz plot of these events, we estimate the linear slope of the charge form factor to be λ + = [30.44 ± 0.83(stat.) ± 0.74(syst.)] × 10?3.  相似文献   

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We report measurements of the branching fractions and CP asymmetries for B(±)→ηh(±) (h=K or π) and the observation of the decay B(0)→ηK(0) from the final data sample of 772×10(6) B ?B pairs collected with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. The measured branching fractions are B(B(±)→ηK(±))=(2.12±0.23±0.11)×10(-6), B(B(±)→ηπ(±))=(4.07±0.26±0.21)×10(-6), and B(B(0)→ηK(0))=(1.27(-0.29)(+0.33)±0.08)×10(-6), where the last decay is observed for the first time with a significance of 5.4 standard deviations (σ). We also find evidence for CP violation in the charged B modes, A(CP)(B(±)→ηK(±))=-0.38±0.11±0.01 and A(CP)(B(±)→ηπ(±))=-0.19±0.06±0.01 with significances of 3.8 σ and 3.0 σ, respectively. For all measurements, the first and second uncertainties are statistical and systematic, respectively.  相似文献   

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Elastic scattering differential cross section data of ± d at 65 MeV and ± 4He at 51 MeV are presented and compared respectively to fully relativistic 3-body and optical potential calculations including true pion absorption.Presented at the symposium Mesons and Light Nuclei, Liblice, Czechoslovakia, June 1981.  相似文献   

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The joint production of ? mesons andπ ±,π 0,p, \(\bar p\) ,K s 0 andK ± is investigated using a sample of 600,000 inclusive ? meson events obtained in hadron Be interactions with incidentπ ±,p, \(\bar p\) andK ± beams. Evidence is presented for the joint production of ? mesons and strange particles produced with non-strange incident beams. With incidentK ± beam the number of additional strange particles is suppressed. The results are found to be in agreement with the qualitative predictions of a parton fusion model. The comparison with the Lund model for lowp T processes is fair.  相似文献   

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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   

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Data on fast protons and antiprotons produced byπ ± incident on hydrogen and nuclear targets at 30 GeV/c are presented. The results covering the kinematic range 0.32 F <0.54 andp T >0.2 GeV/c, complete our previous paper. We give results on inclusive cross-sections as a function ofx F , ofp T 2 and on cross-section ratios. A search for effects of nuclear matter on the production of protons and antiprotons has yielded no major effects beyond final state absorption.  相似文献   

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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   

12.
We analyze the B → ππ, πK modes in the light of the most recent B-factory data, and obtain the following new results: (i) the modes prefer γ = (74±6)°, which - together with |Vub/Vcb| - allows us to determine the "true" unitarity triangle and to search for CP-violating new-physics contributions to B0d- mixing; (ii) the B → πK puzzle reflected in particular by the low experimental value of the ratio Rn of the neutral B → πK rates persists and still favors new physics in the electroweak penguin sector with a new CP-violating phase ϕ ~ –90°, although now also ϕ ~ +90° can bring us rather close to the data; (iii) the mixing-induced CP asymmetry is a sensitive probe of the sign of this phase, and would currently favor ϕ ~ +90°, as well as the direct CP asymmetry of , which suffers, however, from large hadronic uncertainties; (iv) we investigate the sensitivity of our B → πK analysis to large non-factorizable SU(3)-breaking effects and find that their impact is surprisingly small so that it is indeed exciting to speculate on new physics; (v) assuming that new physics enters through Z0 penguins, we study the interplay between B → πK and rare B, K decays and point out that the most recent B-factory constraints for the latter have interesting implications, bringing us to a few scenarios for the future evolution of the data, where also the mixing-induced CP violation in plays a prominent r?le.  相似文献   

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Significant mixing is expected between the neutral bottom mesons \(B_s^0 - \bar B_s^0 \) in the standard model of weak interactions. We propose measurements of the processes \(\left\{ {\begin{array}{*{20}c} {e^ + e^ - } \\ {p\bar p} \\ \end{array} } \right\} \to \begin{array}{*{20}c} {b\bar b} \\ {} \\ \end{array} \to l^ + K^ - K^ - X\) as a measure of such mixing. Rates are presented for energetic bottom quark jets, produced ine + e ? annihilation.  相似文献   

14.
《Physics letters. [Part B]》1987,189(3):363-368
The decays KL,S → π0γγ are calculated within the framework of chiral perturbation theory. The amplitude for KL → π0γγ is found to be finite at the one-loop level yielding a branching ratio of 6.8 × 10−7. The decay spectra of both decays are very characteristic and provide good tests of the effective chiral symmetry realization of the standard model.  相似文献   

15.
We have analyzed theK 1 0 K ± π? system in the reactions π+/pp→π+/p(K 1 0 K ± π?)p. A spin-parity analysis of theK 1 0 K ± π? system in the “4C” channel confirms the existence of the 1++ E meson which decays mainly throughK * \(\bar K\) . The data allow the presence of a 0?+ wave at a level of 14% of theE/ι signal. The production ofD andE mesons in the channels where theK 1 0 K ± π? system is produced along with a π0 or π+π? system is suppressed.  相似文献   

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A detailed theoretical analysis of spin degrees of freedom in carbon isotopes is performed, probing them by electron scattering, pion photoproduction and radiative pion capture from the mesoatomic orbits.Dedicated by the co-authors to the memory of J. Gmitro.The present paper is one of the last works made together with our colleague Marian Gmitro. We had to complete it without him. We mourn for his sudden death and we will always keep alive the memory of his bright personality.  相似文献   

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The development in treating K- and -induced hypernuclear production reactions is reviewed, including the application of DWIA to the (K, K+) reaction to produce . After summarizing the conventional DWIA treatment without spin-dependence, we discuss the calculational method of strength functions up to the continuum. Finally the process is reformulated starting from the elementary amplitudes with the spin-flip component as well as the spin-nonflip one. The new treatment is shown to be powerful and the emphasis is put on the production of polarized hypernuclei, which provides a useful spectroscopic tool for the weak-decay mechanism.Dedicated to our distinguished collaborator, Professor Jan ofka (1943–1991), to the memory of his inspiration in hypernuclear physics and his wide, friendly activities in our community.The authors are very grateful to the late Professor Jan ofka who was a distinguished collaborator for a long time. He coordinated many collaborations between e and Japan. We will miss his scientific and organizational activities in hypernuclear physics. The authors express their thanks to O. Richter, M. Sotona, R. Wünsch, H. Ejiri and T. Kishimoto for collaboration and discussion on several parts of the calculated results. This work has been supported by the Grant-in-Aid for Scientific Research (C) and also by A Grant under The Monbusho International Scientific Research program (Joint Research 1990–1991).  相似文献   

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