共查询到20条相似文献,搜索用时 31 毫秒
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N.V. Shevchenko V.B. Belyaev S.A. Rakityansky S.A. Sofianos W. Sandhas 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):143-146
Elastic ηd-scattering is considered within the Alt-Grassberger-Sandhas (AGS) formalism for various ηN input data. A three-body resonant state is found close to the ηd threshold. This resonance is sustained for different choices of the two-body ηN-scattering length a
ηN. The position of the resonance moves towards the ηd threshold when Rea
ηN is increased, and turns into a quasi-bound state at Rea
ηN∼ 0.7-0.8 fm depending on the choice of Ima
ηN.
Received: 12 June 2000 / Accepted: 3 August 2000 相似文献
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《Physics letters. [Part B]》1999,446(2):125-134
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H. Machner 《中国物理 C》2010,34(9):1218-1223
The η meson can be bound to atomic nuclei.Experimental search is discussed in the form of final state interaction for the reactions dp → 3 Heη and dd → 4 Heη.For the latter case tensor polarized deuterons were used in order to extract the s-wave strength.For both reactions complex scattering lengths are deduced: a 3 Heη = ± 10.7±0.8 +0.1 -0.5 +i· 1.5±2.6 +1.0-0.9 fm and a 4 Heη = [±(3.1±0.5)+i·(0±0.5)] fm.In a two-nucleon transfer reaction under quasi-free conditions,p^ 27 Al → ^3 HeX,was investigated.The system X can be the bound 25 Mg η at rest.When a possible decay of an intermediate N (1535) is required,a highly significant bump shows up in the missing mass spectrum.The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ=4.4±1.3 MeV. 相似文献
5.
H.Machner 《中国物理C(英文版)》2010,34(9)
The η meson can be bound to atomic nuclei.Experimental search is discussed in the form of final state interaction for the reactions dp → 3 Heη and dd → 4 Heη.For the latter case tensor polarized deuterons were used in order to extract the s-wave strength.For both reactions complex scattering lengths are deduced: a 3 Heη = ± 10.7±0.8 +0.1 -0.5 +i· 1.5±2.6 +1.0-0.9 fm and a 4 Heη = [±(3.1±0.5)+i·(0±0.5)] fm.In a two-nucleon transfer reaction under quasi-free conditions,p 27 Al → 3 HeX,was investigated.The system X can be the bound 25 Mg η at rest.When a possible decay of an intermediate N (1535) is required,a highly significant bump shows up in the missing mass spectrum.The data give for a bound state a binding energy of 13.3±1.6 MeV and a width of σ=4.4±1.3 MeV. 相似文献
6.
We calculate the process np → ηd near threshold using a separable potential model of the coupled ηN - πN - ππN subystems, and a relativistic three-body calculation for the ηd scattering amplitude. The ππN channels are represented by an effective σN channel, and we compare the case where the σ and π masses are related by m
σ = 2m
π and no width is considered, to another where the mass and width of the σ -meson are taken from ππ scattering data. The np → ηd cross-section can be well described up to about 60MeV by models where the real part of the ηN scattering length lies between 0.4≤Re(a
ηN)≤0.6 fm which allows us to determine the s -wave ηN scattering amplitude for -60≤E≤60 MeV. 相似文献
7.
In this talk, we present the reduction of the mass of η′-meson at finite temperature which leads to the enhancement of η′ contributions to the dilepton spectra from relativistic heavy ion collisions. QCD low energy theorem, together with the Witten–Veneziano formula, provides the relation of the η′ mass with gluon condensates. 相似文献
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《Nuclear Physics A》1998,632(1):99-108
Within the Glauber formalism and a BUU transport model we analyze the η-photproduction data from nuclei and evaluate the in-medium ηN cross section. Our results indicate that the ηN cross section is almost independent of the η energy up to 200 MeV. 相似文献
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Sibirtsev A. Haidenbauer J. Hanhart C. Niskanen J. A. 《The European Physical Journal A - Hadrons and Nuclei》2004,22(3):495-502
The possible existence of -mesic nuclei poses an interesting and still open issue of research. Since the occurence of such -nucleus bound states is reflected in the corresponding -nucleus scattering length, we critically review the present knowledge for the 3He system. Specifically, we scrutinize the available experimental information for the reaction p + d + 3He which is commonly used to extract the 3He scattering length. We point out several striking discrepancies between the various measurements. Subject to those inconsistencies, we deduce a value a = | 4.3±0.3| + i(0.5±0.5) fm. 相似文献
10.
《Physics letters. [Part B]》1988,209(1):11-13
We show that the binding energy of the η-mesic nucleus does not increase monotonically with the ηNN1 (1535) coupling constant. This feature is a direct consequence of the unitarity constaint on the ηN interaction. 相似文献
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First radial excitations of the scalar-meson nonet and of the pseudoscalar mesons η and η′ are described within a nonlocal chiral quark model of the Nambu-Jona-Lasinio type with ′t Hooft interaction. In this model, simple form factors are used, which allows us to describe first radial excitations of the mesons and to retain the gap equations describing spontaneous breakdown of chiral symmetry in the standard form. The external parameters of form factors are fixed by the masses of excited pseudoscalar mesons, and the same form factors are used to predict the masses of excited scalar mesons. The strong decays of excited scalar mesons and of η and η′ mesons are described in satisfactory agreement with experimental data. 相似文献
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A. Starostin 《The European physical journal. Special topics》2011,198(1):117-131
Decays of the η and the η′ represent a significant portion of the scientific program with the Crystal Ball at MAMI. This review
summarizes the current status of the program and discusses some recent results, such as the slope parameter of the η → 3π0 Dalitz plot, the matrix element of η → π0γγ and the invariant mass of e
+
e
−γ from the η → e
+
e
−γ Dalitz decay. Possible future measurements are discussed. 相似文献
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B. Borasoy 《The European Physical Journal A - Hadrons and Nuclei》2000,7(2):255-259
We compare two different frameworks which have been proposed to include the η′ in chiral perturbation theory. The equivalence
of these two approaches is shown both for the purely mesonic case and in the presence of the ground state baryon octet. The
relation between the different sets of parameters in both Lagrangians is clarified.
Received: 3 November 1999 / Revised version: 10 January 2000 相似文献
16.
Mixing angles of η and η′ mesons are obtained in the scheme of octet-singlet mixing θη = −15.4°, θ′η = −17.9°, and in the scheme connected with expansion in the quark basis $
\bar q
$
\bar q
q − $
\bar s
$
\bar s
s φ = 39.3°. The constants gV
ηγ, g
η′
V
γ of radiative decays η′ → V
γ and V → ηγ (V ≡ ρ, ω, φ) and the ratios of constants of weak decays of η and η′ mesons are calculated. The numerical values that were found
are in agreement with the experimental data. 相似文献
17.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok D. A. Bukin S. V. Burdin A. V. Vasil’ev T. V. Dimova A. A. Drozdetskii V. P. Druzhinin V. B. Golubev V. N. Ivanchenko A. A. Korol’ M. S. Korostelev S. V. Koshuba A. P. Lysenko I. N. Nesterenko E. V. Pakhtusova A. A. Sal’nikov S. I. Serednyakov V. A. Sidorov Z. K. Silagadze A. G. Skripkin Yu. V. Usov V. V. Sharyi Yu. M. Shatunov 《JETP Letters》2001,73(9):451-452
The η→3π0 decay was studied with the SND detector at the VEPP-2Me + e ? collider. The parameter that describes deviation of the Dalitz plot of events from a uniform distribution was found to be α=?0.010±0.021±0.010. 相似文献
18.
An exclusive measurement of the excitation functions for the dd → 3Hep π ? and dd → 3Hen π 0 → 3Hen γ γ reactions was performed at the Cooler Synchrotron COSY-Jülich with the WASA-at-COSY detection system. The data were collected in two dedicated experiments in 2008 and in 2010. The experimental method and the current status of the analysis are presented. 相似文献
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Physics of Atomic Nuclei - A statistical method for extracting the η → γγ signal upon rejecting those γ clusters that form pairs with invariant masses close to that of the... 相似文献
20.
A.V. Anisovich V.V. Anisovich V.A. Nikonov L. Montanet 《The European Physical Journal A - Hadrons and Nuclei》1999,6(3):247-249
We discuss γγ partial widths of pseudoscalar/isoscalar mesons η:(M) in the mass region M∼ 1000–1500 MeV. The transition amplitudes η:(1295) →γγ and η:(1440) →γγ are studied within an assumption that the decaying
mesons are the members of the first radial excitation nonet 21
S
0qˉq. The calculations show that partial widths being of the order of 0.1 keV are dominantly due to the nˉn meson component
while the contribution of the sˉs component is small.
Received: 24 September 1999 相似文献