共查询到20条相似文献,搜索用时 797 毫秒
1.
Sayipjamal Dulat Bing-Song Zou 《The European Physical Journal A - Hadrons and Nuclei》2005,26(1):125-134
With accumulation of high statistics data at BES and CLEO-c, many new interesting channels can get enough statistics for partial-wave
analysis (PWA). Among them, ψ↦γpˉ,γΛˉ,γΣˉ,γΞˉ channels provide a good place for studying baryon-antibaryon interactions; the double radiative decays ψ↦γγV with V ≡ ρ,ω,φ have a potential to provide information on the flavor content of any meson resonances (R) with positive charge parity
(C = +) and mass above 1 GeV through ψ↦γR↦γγV; ψ(2s)↦γχc0,1,2 with χc0,1,2↦Kˉπ+π- and 2π+2π- decays are good processes to study χcJ charmonium decays. Using the covariant tensor formalism, here we provide theoretical PWA formulae for these channels. 相似文献
2.
It is pointed out that the coupling characterizing theψ-γ vertex must change substantially between the limits,ψ on mass-shell which occurs inψ→e
+
e
− and photon on mass-shell which is relevant in radiative decays likeψ→ππγ, ψ→ηγ and photoproduction ofψ. This has the consequence that the value ofψN total cross section must be larger than what is inferred from the use of naive vector dominance in photoproduction. 相似文献
3.
WeiGuo Li 《中国科学G辑(英文版)》2008,51(6):567-576
Recent experimental results from Beijing Spectroscopy (BES) are reviewed, including the hadron spectroscopy from J/ψ decays, and a number of new states are found or confirmed, including σ, κ, X(1835), ωφ threshold enhancement in J/ψ→γωφ, a broad resonance in J/ψ→K
+
K
−
π
0, decay studies of ψ(2S) and χ
CJ
, as well as the results of ψ(3770) non-D
decays. The current status of BEPCII/BESIII, the major upgrade of BEPC/BESII, is also reported.
Supported by the National Natural Science Foundation of China (Grant No. 10491300) 相似文献
4.
Gui-Jun Ding Rong-Gang Ping Mu-Lin Yan 《The European Physical Journal A - Hadrons and Nuclei》2006,28(3):351-360
X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us
to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with pˉ, η′ππ. The processes ϒ(1S) → γX(1835) and J/ψ → ωX(1835) have been examined. It has been found that Br(ϒ(1S) → γX(1835))Br(X(1835) → pˉ) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br(J/ψ → ωX(1835)), Br(J/ψ → ρX(1835)) with X(1835) → pˉ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations
are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production
branching fractions is presented. 相似文献
5.
Preliminary data on the reactions e
+
e
−→φ→γ f
0(980)→γπ0π0 together with data on ππ scattering and the reactions J/ψ→φπ+π− and K
−
p→π +π−(Λ,Σ) are analyzed. The analysis shows that the mass of the f
0(980) meson is
= 950 MeV, and BR(φ→γf
0→γπ0π0)≃ 1× 10−4, indicating that the f
0(980) resonance is of a four-quark nature.
Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 445–449 (10 April 1998) 相似文献
6.
A ππ, ˉKK, and ρρ(ωω) fully coupled channel model is used to predict the lowest isospin S, P, D, F-wave phase shifts and inelasticities
for elastic ππ scattering from threshold to 2.0 GeV. As input the S-matrix is required to exhibit poles corresponding to the
meson resonance table of the Particle Data Group. As expected, the ππ inelasticity is very strongly related to the opening
of the ˉK channel near 1 GeV, and the opening of ρρ(4π) and ωω(6π) channels in the 1.5 GeV region. The predictions of this model are
compared to the various elastic ππ→ππ amplitudes, that were obtained from analyses of π− p →π−π+n data. The role of the various resonances, in particular the glueball candidate f
0(1500) and the f
J(1710) is investigated.
Received: 19 November 1997 相似文献
7.
V. Dorofeev R. Dzhelyadin A. Ekimov Yu. Gavrilov Yu. Gouz A. Ivashin V. Kabachenko I. Kachaev A. Karyukhin Yu. Khokhlov V. Konstantinov M. Makouski V. Matveev A. Myagkov V. Nikolaenko A. Ostankov B. Polyakov D. Ryabchikov N. Shalanda M. Soldatov A. A. Solodkov A. V. Solodkov O. Solovianov E. Starchenko A. Zaitsev 《The European Physical Journal A - Hadrons and Nuclei》2008,38(2):149-154
The isospin-violating decay f
1(1285) → π+π-π0 has been studied at the VES facility. This study is based on the statistics acquired in π-
Be interactions at 27, 36.6 and 41 GeV/c in the diffractive reaction π-
N → (f
1π-)N . The f
1(1285) → π+π-π0 decay is observed. The preliminary ratio of decay probabilities BR(f
1(1285) → π+π-π0) to BR(f
1(1285) → ηπ+π-).
BR(η → γγ) is ∼ 2% .
Original article based on material presented at HADRON 2007. 相似文献
8.
Ya.I. Azimov 《The European Physical Journal A - Hadrons and Nuclei》2003,16(2):209-219
Isospin-violating mixing of ρ- and ω-mesons is reconsidered in terms of propagators. Its influence on various pairs of (ρ,ω)-decays
to the same final states is demonstrated. Some of them, (ρ,ω)↦π+π- and (ρ,ω)↦πγ, have been earlier discussed in the literature, others (e.g., (ρ,ω)↦ηγ and (ρ,ω)↦e
+
e
-) are new in this context. Changes in partial widths for all the decay pairs are shown to be correlated. The set of present
experimental data, though yet inconclusive, provides some limits for the direct (ρω)-coupling and indirectly supports enhancement
of ρ↦πγ in comparison with ρ±↦π±γ, though not so large as in some previous estimates.
Received: 16 September 2002 / Accepted: 23 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: azimov@pa1400.spb.edu
Communicated by V.V. Anisovich 相似文献
9.
R. Fleischer 《The European Physical Journal C - Particles and Fields》2007,52(2):267-281
Several years ago, it was pointed out that the U-spin-related decays Bd→π+π-, Bs→K+K- and Bd→π∓K±, Bs→π±K∓ offer interesting strategies for the extraction of the angle γ of the unitarity triangle. Using the first results from the
Tevatron on the Bs decays and the B-factory data on Bu,d modes, we compare the determinations of γ from both strategies, study the sensitivity on U-spin-breaking effects, discuss
the resolution of discrete ambiguities, predict observables that were not yet measured but will be accessible at LHCb, explore
the extraction of the width difference ΔΓs from untagged Bs→K+K- rates, and address the impact of new physics. The data for the Bd→π+π-, Bs→K+K- system favour the BaBar measurement of direct CP violation in Bd→π+π-, which will be used in the numerical analysis and result in a fortunate situation, yielding γ=(66.6+4.3+4.0
-5.0-3.0)°, where the latter errors correspond to a generous estimate of U-spin-breaking effects. On the other hand, the Bd→π∓K±, Bs→π±K∓ analysis leaves us with 26°≤γ≤70°, and points to a value of the Bs→π±K∓ branching ratio that is larger than the current Tevatron result. An important further step will be the measurement of mixing-induced
CP violation in Bs→K+K-, which will also allow us to extract the B0
s–B̄0
s mixing phase unambiguously with the help of Bs→J/ψφ at the LHC. Finally, the measurement of direct CP violation in Bs→K+K- will make the full exploitation of the physics potential of the Bs,d→ππ,πK,KK modes possible. 相似文献
10.
X.-J. Wang J.-H. Jiang M.-L. Yan 《The European Physical Journal A - Hadrons and Nuclei》2002,14(2):219-224
In terms of effective field theory and mixed-propagator approach, we show that there is a larger hidden effect of isospin
breaking in ρ→πγ decay due to a ω exchange, ρ→ω→πγ. The branching ratio is predicted as B(ρ→πγ) = (11.67±2.0)×10-4, which is much larger than Particle Data Group's datum (6.8±1.7)×10-4 and one of charged mode, B(ρ±→π±γ) = (4.5±0.5)×10-4.
Received: 7 January 2002 / Accepted: 2 April 2002 相似文献
11.
B.S. Zou G.X. Peng R.G. Ping H.C. Chiang W.X. Ma P.N. Shen 《The European Physical Journal A - Hadrons and Nuclei》2001,11(3):341-344
For J/Ψ↦
pπ0 and
pπ+π-, the π0
p and pπ+π- systems are limited to be pure isospin-(1/2) due to isospin conservation. This is a big advantage in studying N* resonances from J/Ψ decays, compared with πN and γN experiments. The process J/Ψ↦
N
* or p
provides a new way to probe the internal structure of the N* resonances. Here we report a quark model calculation for J/Ψ↦
p,
N
*(1440) and
N
*. The implication for the internal structure of N
*(1440) is discussed.
Received: 1 June 2001 / Accepted: 20 June 2001 相似文献
12.
We review the cross-sections for low-energy π-γ reactions in the framework of chiral perturbation theory. Charged-pion Compton scattering, π-γ → π-γ , is considered up to one-loop order where the pion's internal structure enters through the difference of the electric and
magnetic pion polarizability, απ - βπ . The ongoing COMPASS experiment aims at measuring this important structure constant with high statistics using the Primakoff
effect. In the same way, the reaction π-γ → π-π0 serves as a test of the QCD chiral anomaly (via the γ3π -coupling constant F
γ3π . Furthermore, we calculate the total cross-sections for neutral and charged pion-pair production, π-γ → π-π0π0 and π-γ → π-π+π- , which are governed by the chiral ππ -interaction. Finally, we investigate the radiative (correction) process π-γ → π-γγ and calculate the corresponding two-photon mass spectrum. This information will be useful for analyzing the π- Primakoff scattering events with photons in the final state. 相似文献
13.
G. Puddu 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):171-181
We extend the recently presented formalism for Monte Carlo calculations of the partition function, for both even and odd particle
number systems (Phys. Rev. C 59, 2500 (1999)), to the calculation of many-body matrix elements of the type <ψ| e
- βℋ|ψ> where |ψ> is a many-body state with a definite angular momentum, parity, neutron and proton numbers. For large β such
matrix elements are dominated by the lowest eigenstate of the many-body Hamiltonian ℋ, corresponding with a given angular
momentum parity and particle number. Emphasis is placed on odd-mass nuclei. Negligible sign fluctuations in the Monte Carlo
calculation are found provided the neutron and proton chemical potentials are properly adjusted. The formalism is applied
to the J
π = 0+ state in 166
Er and to the J
π = 9/2-, 13/2+, 5/2- states in 165
Er using the pairing-plus-quadrupole model.
Received: 28 April 2000 / Accepted: 20 September 2000 相似文献
14.
G. Pancheri O. Shekhovtsova G. Venanzoni 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):458-460
Effects due to the non-pointlike behaviour of pions in the process e
+
e
-→π
+
π
-
γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution
of the direct decay φ→π
+
π
-
γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE
analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a
model-independent way is proposed. 相似文献
15.
Xiao-Gang He Xue-Qian Li Xiang Liu Jian-Ping Ma 《The European Physical Journal C - Particles and Fields》2007,49(3):731-736
Recently the BES collaboration has announced the observation of a resonant state in the π+π-η’ spectrum in J/ψ→γπ+π-η’ decay. Fitting the data with a 0-+ state, the mass is determined to be 1833.7 MeV with 7.7σ statistic significance. This state is consistent with the one extracted
from previously reported pp̄ threshold enhancement data in J/ψ→γpp̄. We study the properties of this state using QCD anomaly
and QCD sum rules, assuming X(1835) to be a pseudoscalar, and we show that it is consistent with the data. We find that this
state has a sizeable matrix element , leading to branching ratios of (2.61–7.37)×10-3 and (2.21–10.61)×10-2 for J/ψ→γGp and for Gp→π+π-η′, respectively. Combining the calculated branching ratio of J/ψ→γGp and data on threshold enhancement in J/ψ→γpp̄, we determine the coupling for the Gp–p–p̄ interaction. We finally study the branching ratios of the other J/ψ→γ+three mesons decay modes. We find that J/ψ→γGp→γ(π+π-η,KKπ0) can provide useful tests for the mechanism proposed.
PACS 11.55.Hx; 12.39.Fe; 12.39.Mk; 13.25.Gv 相似文献
16.
Yun Chang Shin Bong Soo Han Myung Ki Cheoun K.S. Kim Il-Tong Cheon 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):269-276
A SU(2) effective Lagrangian is extended to a SU
L(3) ⊗SU
R(3) by including the vector and axial vector meson. With this effective Lagrangian, electromagnetic form factors of charged
pion and kaon are calculated in both time- and space-like regions. The pseudoscalar meson loops are taken into account. Good
agreement with experimental data is obtained for those form factors and charged pseudoscalar meson radii. Decay widths of
ρ→ππ and φ→K
+
K
- are also calculated and shown to agree with experimental data very well.
Received: 20 December 1999 / Accepted: 12 October 2000 相似文献
17.
M. Koll R. Ricken D. Merten B.C. Metsch H.R. Petry 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):73-94
We present new results of a relativistic quark model based on the Bethe-Salpeter equation in its instantaneous approximation.
Assuming a linearly rising confinement potential with an appropriate spinorial structure in Dirac space and adopting a residual
interaction based on instanton effects, we can compute masses of the light mesons up to highest observed angular momenta with
a natural solution of the U
A(1) problem. The calculated ground states masses and the radial excitations describe the experimental results well. In this
paper, we will also discuss our results concerning numerous meson decay properties. For processes like π+/K
+↦e
+υeγ and 0-↦γγ at various photon virtualities, we find a good agreement with experimental data. We will also comment on the form factors
of the K
?3 decay and on the decay constants of the π, K and η mesons. For the sake of completeness, we will furthermore present the electromagnetic form factors of the charged π
and K mesons as well as a comparison of the radiative meson decay widths with the most recent experimental data.
Received: 28 August 2000 / Accepted: 12 September 2000 相似文献
18.
J. Junkersfeld A. V. Anisovich G. Anton R. Bantes O. Bartholomy R. Beck Yu. Beloglazov R. Bogendörfer R. Castelijns V. Crede A. Ehmanns J. Ernst I. Fabry H. Flemming A. Fösel M. Fuchs Ch. Funke R. Gothe A. Gridnev E. Gutz St. Höffgen I. Horn J. Hößl H. Kalinowsky F. Klein E. Klempt H. Koch M. Konrad B. Kopf B. Krusche J. Langheinrich H. Löhner I. Lopatin J. Lotz H. Matthäy D. Menze J. Messchendorp V. A. Nikonov D. Novinski M. Ostrick H. van Pee A. Radkov A. V. Sarantsev S. Schadmand C. Schmidt H. Schmieden B. Schoch G. Suft V. Sumachev T. Szczepanek U. Thoma D. Walther Ch. Weinheimer 《The European Physical Journal A - Hadrons and Nuclei》2007,31(3):365-372
Differential and total cross-sections for photoproduction of γp→pπ
0
ω and γp→Δ
+
ω were determined from measurements of the CB-ELSA experiment, performed at the electron accelerator ELSA in Bonn. The measurements
covered the photon energy range from the production threshold up to 3GeV. 相似文献
19.
20.
G.I. Lykasov W. Cassing A. Sibirtsev M.V. Rzjanin 《The European Physical Journal A - Hadrons and Nuclei》1999,6(1):71-81
We calculate the elastic and inelastic ωN→ωN, →πN, →ρN, →ρπN, →ππN, →σN reactions within a boson exchange approximation where the ωρπ coupling constant and form factor are fixed by the reaction
πN→ωN in comparison to the experimental data. We find rather large ωN cross sections at low relative momenta of the ω-meson which
leads to a substantial broadening of the ω-meson width in nuclear matter. The implications of the ωN final state interactions are studied for ω production in 12C +12C, 40Ca +40Ca and 58Ni +58Ni reactions at about 2 · A GeV within the HSD transport approach; the drastic changes of the transverse mass spectra relative
to a general m
T-scaling (for π0 and η mesons) might be controlled experimentally by the TAPS Collaboration.
Received: 28 April 1999 / Revised version: 7 June 1999 相似文献