共查询到20条相似文献,搜索用时 46 毫秒
1.
Y.C. Shin M.K. Cheoun K.S. Kim T.K. Choi 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):87-93
A role of the axial-vector mesons, such as K1 and a1, on the emitted-photon spectrum in hot hadronic matter is studied through the channels πρ→a
1→πγ and Kρ→K
1→Kγ. Both channels could be dominant over the region lower than E
γ∼ 0.5 GeV, while the role of the K1 meson is diminished in the higher E
γ region. This study is carried out with an SU
L(3) ⊗SU
R(3) effective chiral Lagrangian which includes vector and axial-vector mesons systematically and explains well their hadronic
and radiative decays simultaneously.
Received: 8 August 2001 / Accepted: 4 February 2002 相似文献
2.
The effects of final-state interactions (FSI) in hadronic B decays are investigated. The model for FSI, based on Regge phenomenology of high-energy hadronic interactions, is proposed.
It is shown that this model explains the pattern of phases in matrix elements of B → ππ and B → ρρ decays. These phases play an important role for CP violation in B decays. The most precise determination of the unitarity triangle angle α from B
d
→ ρπ decays is performed. The relation between CP asymmetries in B → Kπ decays is discussed. It is emphasized that the large-distance FSI can explain the structure of polarizations of the vector
mesons in B decays and other puzzles like a very large branching ratio of the B decay to $
\bar \Xi
$
\bar \Xi
c
Λ
c
. 相似文献
3.
The decays η → 3π
0 and η → π
0
π
+
π
− are considered within the isobar model. It is shown that, in order to explain the branching ratio and the shape of the Dalitz
plot for the decay η′ → 3π
0, it is sufficient to take into account the contributions of the σ and a
0 mesons. The inclusion of the σ meson is necessary for reproducing the shape of the distribution over the Dalitz plot. The branching ratio for the decay
η′ → π
0
π
+
π
− is obtained. The predictions for the distributions over the Dalitz plot for this decay are presented. These predictions depend
strongly on model parameters. 相似文献
4.
The widths with respect to the radiative decays f
0(980) → ργ and a
0(980) → ωγ were calculated within the local Nambu-Jona-Lasinio model. The contributions of both quark and meson loops were taken into
account. The latter and the former play a dominant role for the radiative decays of, respectively, the f
0(980) and the a
0(980) meson. 相似文献
5.
S. Schadmand 《Pramana》2010,75(2):225-234
The WASA Detector Facility is an internal experiment at the cooler synchrotron (COSY) in Jülich, Germany. The COSY accelerator
provides proton and deuteron beams with momenta up to 3.7 GeV/c giving access to hadron physics including the strange quark
sector. The physics program with the WASA detector involves hadron dynamics and hadron structure. Key experiments address
fundamental symmetries and symmetry violations via the study of rare and not-so-rare meson decays. From the very first production
run, results on the Dalitz plot slope parameter in the isospin violating η → 3π
0 decay have been obtained. The 3π
0 final state is also used to study meson production mechanisms. Investigations of other decay modes of the η-meson address C, P, and T symmetries and combinations. Higher orders in chiral perturbation theory are probed with the η → π
0 decay. The status and plans for studying hadron structure with Dalitz decays of mesons are presented. 相似文献
6.
Hai-Yang Cheng 《Zeitschrift fur Physik C Particles and Fields》1995,69(1):647-653
The parametersχ
1,2, which measure nonfactorizable soft gluon contributions to hadronic weak decays of mesons, are updated by extracting them
from the data ofD, B→PP, VP decays (P: pseudoscalar meson,V: vector meson). It is found thatχ
2 ranges from −0.36 to −0.60 in the decays fromD→Kπ toD
+→φπ
+,D→K*π, while it is of order 10% with a positive sign inB→ψK, Dπ, D*π, Dρ decays. Therefore, the effective parametera
2 is process dependent in charm decay, whereas it stays fairly stable inB decay. This is in accordance with the picture that nonfactorizable soft gluon effects become stronger when the relative momentum
of the decay particles becomes smaller. As forD, B→VV decays, the presence of nonfactorizable terms in general prevents a possible definition of effectivea
1 anda
2. This is reinforced by the observation of a large longitudinal polarization fraction inB→ψK* decay, implying nonfactorizable effects contributing differently toS-, P- andD-wave amplitudes. We found thatA
1
nf
/A
1>0>A
2
nf
/A
2,V
nf/V (nf standing for nonfactorization) forB→ψK* decay and 0>A
1
nf
/A
1>A
2
nf
/A
2,V
nf/V forD→K*ρ decay. A measurement of longitudinally and transversely polarized decay rates Γ
L
and Γ
T
in color-suppressed decay modesB
0→D*0
ρ
0,D*0
ω andD
+→φρ
+ is urged. 相似文献
7.
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
8.
9.
Alberto Filipuzzi Gino Isidori 《The European Physical Journal C - Particles and Fields》2009,64(1):55-62
We analyse the violations of lepton-flavour universality in the ratios ℬ(P→ℓ
ν)/ℬ(P→ℓ
′
ν) using a general effective theory approach, discussing various flavour-symmetry breaking patterns of physics beyond the SM.
We find that in models with Minimal Lepton Flavour Violation the effects are too small to be observed in the next generations
of experiments in all relevant meson systems (P=π,K,B). In a Grand Unified framework with minimal breaking of the flavour symmetry, the effects remain small in π and K decays, while large violations of lepton-flavour universality are possible in B→ℓ
ν decays. 相似文献
10.
S. S. Bulanov 《Physics of Atomic Nuclei》2004,67(2):314-327
The dependence of K
S, L
→ π
+
π
−
γ decay probabilities on photon polarization is calculated. The phases of the terms of the amplitude that arise from the pion-pion
interaction are obtained by using a simple realistic model of pion-pion interaction via virtual ρ meson, instead of chiral perturbation theory (ChPT). The results are compared with those of other authors and the origin
of the discrepancies is explained. It is shown that the standard ChPT approach for K
S, L
→ π
+
π
−
γ decays cannot reproduce the contribution of the ρ meson to the P-wave ππ interaction. The departure of the photon spectrum from pure bremsstrahlung due to the pion-loop contribution to the electric
direct emission amplitude is calculated. It is shown that the interference between the terms of amplitude with different CP parity appears only when the photon is polarized (linearly or circularly). Instead of measuring the linear polarization,
the angular correlation between the π
+
π
− and e
+
e
− planes in K
S, L
→ π
+
π
−
e
+
e
− decay can be studied.
From Yadernaya Fizika, Vol. 67, No. 2, 2004, pp. 332–345.
Original English Text Copyright ? 2004 by Bulanov.
This article was submitted by the author in English. 相似文献
11.
In the framework of the chiral perturbation theory we obtain the phenomenological relations between decay branches of rare
radiative kaon to pion and leptons K
+ → π+
l
+
l
− and K
S
0 → π0
l
+
l
− and meson form factors. The comparison of these results with the present-day experimental data shows us that the ChPT relations
for a charge kaon can determine meson form factors from already measured decay rates at high precision level. However, in
the case of the neutral kaon decays K
0 → π0
e
+
e
−(μ+μ−) the form factor data are known to a higher precision than data on the differential rates of radiative kaon decay K
0 π0
e
+
e
−(μ+μ−). 相似文献
12.
Properties of a scalar a meson are investigated in the two-flavor Nambu-Jona-Lasinio model with the Polyakov loop (PNJL).
Model analysis of the phase diagram of strong interacting matter is performed. The temperature dependence of the σ → ππ decay
width is studied at the zero chemical potential and near the critical end point. The calculated strong coupling constant g
σππ and the decay width are compared with available experimental data and other model results. Nonthermal enhancement of the
total decay width is noted for the σ meson near the critical end point when the condition m
σ ≥ 2m
π is broken. 相似文献
13.
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
14.
Harpreet Kaur 《Pramana》1999,52(4):389-393
The beauty-conserving strangeness-changing decays ofB
s meson are examined. In the charm sector, charm-conserving strangeness changing (Δc = 0, Δs ≠ 0) decays are Cabibbo suppressed and are governed by the CKM elementV
us which is much smaller than the CKM diagonal elementV
cs, so may be of little interest. On the other hand, in theb-sector, beauty-conserving strangeness changing (Δb = 0, Δs ≠ 0) decays are CKM allowed as the CKM matrix elementV
us governing such decays is much larger thanV
bc orV
bu which govern respectively theb →c orb →u transitions. The phase space available, however, is too small for the decays considered here. The numerical estimates for
the decay widths of two such modes ofB
s meson are presented. 相似文献
15.
A. V. Anisovich V. V. Anisovich M. A. Matveev V. A. Nikonov J. Nyiri A. V. Sarantsev 《Physics of Atomic Nuclei》2010,73(7):1254-1265
We consider as an example the two-pion decay of the ρ meson, the 3
S
1
q
$
\bar q
$
\bar q
state of the constituent quarks—the decay being determined by the transition q
$
\bar q
$
\bar q
→ ππ contains information about confinement interactions. One can specify in this decay two types of transitions: (i) the bremsstrahlung
radiation of a pion q → q + π (or $
\bar q
$
\bar q
→ $
\bar q
$
\bar q
+ π) with a subsequent fusion q
$
\bar q
$
\bar q
→ π, and (ii) the direct transition q
$
\bar q
$
\bar q
→ ππ. We demonstrate how in the amplitudes of the corresponding transitions the quark singularities have to disappear, i.e., what
is the way the quark confinement at relatively short distances can be realized. We calculate and estimate the contributions
of processes with bremsstrahlung radiation of the pion and of the direct transition q
$
\bar q
$
\bar q
→ ππ. The estimates demonstrate that the processes involving the direct transition q
$
\bar q
$
\bar q
→ ππ are necessary, but they cannot be determined unambiguously by the decay ρ(775) → ππ. We conclude that for the determination of the q
$
\bar q
$
\bar q
→ ππ transition more complete data on the resonance decays into the ππ channels are needed than those available at the moment. 相似文献
16.
17.
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
18.
T. Branz T. Gutsche V. Lyubovitskij 《The European Physical Journal A - Hadrons and Nuclei》2008,37(3):303-317
We discuss a possible interpretation of the f
0(980)-meson as a hadronic molecule —a bound state of K and mesons. Using a phenomenological Lagrangian approach we calculate the strong f
0(980) → ππ and electromagnetic f
0(980) → γγ decays. The compositeness condition provides a self-consistent method to determine the coupling constant between
f
0 and its constituents, K and . Form factors governing the decays of the f
0(980) are calculated by evaluating the kaon loop integrals. The predicted f
0(980) → ππ and f
0(980) → γγ decay widths are in good agreement with available data and results of other theoretical approaches. 相似文献
19.
E. P. Shabalin 《Physics of Atomic Nuclei》2010,73(11):1908-1915
The unitarization of the amplitude for the decay process K
10 → π+π− and allowance for the rescattering of final-state pions in the decay process K
+ → π+π+π− make it possible to evaluate, by using the parameters extracted from data on K → 2π decays, the K
+ → π+π+π− decay width. The result agrees with the experimental width value at a level of a few percent. Allowance for corrections for
higher order terms of the momentum expansion of the amplitude for the decay process K
+ → π+π+π− leads to the slope-parameter value of g
++−th = 0.2182, which agrees with its experimental counterpart, g
++−exp = 0.2154 ± 0.0035. 相似文献
20.
E. P. Shabalin 《Physics of Atomic Nuclei》2005,68(1):88-93
The amplitudes of the K
± → 3π and K→ 2π decays are expressed in terms of different combinations of one and the same set of CP-conserving and CP-odd parameters. Extracting the magnitudes of these parameters from the data on K → 2π decays, we estimate an expected CP-odd difference between the values of the slope parameters g
+ and g
− of the energy distributions of “odd” pions in K
+ → π+π+π− and K
− → π−π−π+ decays.
From Yadernaya Fizika, Vol. 68, No. 1, 2005, pp. 89–94.
Original English Text Copyright ? 2005 by Shabalin.
This article was submitted by the author in English. 相似文献