共查询到20条相似文献,搜索用时 903 毫秒
1.
A. Z. Dubničková S. Dubnička E. Goudzovski V. N. Pervushin M. Sečanský 《Physics of Particles and Nuclei Letters》2008,5(2):76-84
We analyze the possibility of experimental investigation of new low-energy relations between the values of resonance masses
in the meson form factors and the differential rate of radiative kaon decay K
+ → π+
e
+
e
−(μ+μ−) at the current level of the experimental precision. A set of arguments is listed in favor that these relations can be a
consequence of weak static interactions in the Standard Model.
The results were presented at the 5th NA48 Mini-Workshop on Kaon Physics, CERN, Dec. 12, 2006.
The text was submitted by the authors in English. 相似文献
2.
V. P. Efrosinin 《Physics of Atomic Nuclei》2008,71(2):285-288
With usage of the Low theorem, the general expression for the amplitude of radiative kaon decay K
+ → π
+
π
0
γ is determined. The possible reason of suppression for the branching ratio of kaon decay K
+ → π
+
π
0 is considered.
The text was submittedby the authors in English. 相似文献
3.
4.
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
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.
7.
B. Kubis E.H. Müller J. Gasser M. Schmid 《The European Physical Journal C - Particles and Fields》2007,50(3):557-571
We re-investigate the radiative charged kaon decay K±→π0e±νeγ [Ke3γ
±] in chiral perturbation theory, merging the chiral expansion with Low’s theorem. We thoroughly analyze the precision of the
predicted branching ratio relative to the non-radiative decay channel. Structure dependent terms and their impact on differential
decay distributions are investigated in detail, and the possibility to see effects of the chiral anomaly in this decay channel
is emphasized.
PACS 13.20.Eb; 11.30.Rd; 12.39.Fe 相似文献
8.
Inequality of the rates for K
0 → π+
e
− υ− and K
0 → π−
e
+
ν transitions, reported by CPLEAR, and an asymmetry in the distribution of the dihedral angle between the π+π− and e
+
e
− planes in K
L → π+π−
e
+
e
− decays, found by KTeV, have been announced as demonstrations of T-noninvariance. These results are critically interpreted and compared as proofs of the failure of reciprocity. 相似文献
9.
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
10.
L. Cappiello O. Catà G. D’Ambrosio Dao-Neng Gao 《The European Physical Journal C - Particles and Fields》2012,72(1):1872
We study the decay K
+→π
+
π
0
e
+
e
−, currently under analysis by the NA62 Collaboration at CERN. In particular, we provide a detailed analysis of the Dalitz
plot for the long-distance, γ
∗-mediated, contributions (Bremsstrahlung, direct emission and its interference). We also examine a set of asymmetries to isolate
genuine short-distance effects. While we show that charge asymmetries are not required to test short distances, they provide
the best environment for its detection. This constitutes by itself a strong motivation for NA62 to study K
− decays in the future. We therefore provide a detailed study of different charge asymmetries and the corresponding estimated
signals. Whenever possible, we make contact with the related processes K
+→π
+
π
0
γ and K
L
→π
+
π
−
e
+
e
− and discuss the advantages of K
+→π
+
π
0
e
+
e
− over them. 相似文献
11.
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
12.
S. Pacetti 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):665-671
We define a general procedure, based on analyticity and dispersion relations, to estimate low-energy amplitudes for processes
like: φ→e
+
e
-
M and φ→γM, starting from cross-section data on e
+
e
-→φM, where M is a generic light scalar or pseudoscalar meson. In particular this procedure is constructed to obtain predictions on the
radiative decay rate which are crucially linked on the assumed quark structure for the meson M under consideration. Three cases are analyzed: M = η, M = f
0(qˉ) and M = f
0(qqˉ). While in the η case the estimate of the branching fraction for the radiative decay φ→ηγ is in agreement with the data, in the case of f
0, such agreement is obtained only under the hypothesis of a tetraquark scalar meson. 相似文献
13.
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
14.
Kotar M. Kijima 《Indian Journal of Physics》2011,85(1):201-204
The PHENIX experiment at RHIC has measured ω and ϕ meson production using di-electron decay mode over a psude-rapidity range of |η| ≤ 0.35 and a transverse momentum range of
0 < p
T
< 5 GeV/c in proton + proton collisions at $
\sqrt s
$
\sqrt s
= 200 GeV. The spectra of production cross section as a function of p
T
for ω and ϕ → e
+
e
− show good agreement with other hadornic decay channels ω → π
0
γ, ω
0
π
+
π
− and ϕ → K
+
K
−, respectively. 相似文献
15.
M. N. Achasov K. I. Beloborodov A. V. Berdyugin A. G. Bogdanchikov A. V. Bozhenok A. D. Bukin D. A. Bukin T. V. Dimova V. P. Druzhinin V. B. Golubev A. A. Korol S. V. Koshuba E. V. Pakhtusova S. I. Serednyakov Yu. M. Shatunov V. A. Sidorov Z. K. Silagadze A. N. Skrinsky Yu. A. Tikhonov A. V. Vasiljev 《Journal of Experimental and Theoretical Physics》2006,103(3):380-384
The corrected cross section of the e
+
e
− → π+π− process measured in the spherical neutral detector experiment at the VEPP-2M e
+
e
− collider is presented. The update is necessary due to a flaw in the e
+
e
− → π+π− and e
+
e
− → μ+μ− Monte Carlo event generators used previously in data analysis.
The text was submitted by the authors in English. 相似文献
16.
《The European Physical Journal C - Particles and Fields》2008,53(1):1-14
We report measurements of charmonia produced in two-photon collisions and decaying to four-meson final states, where the meson
is either a charged pion or a charged kaon. The analysis is based on a 395 fb-1 data sample accumulated with the Belle detector at the KEKB electron–positron collider. We observe signals for the three
C-even charmonia ηc(1S), χc0(1P) and χc2(1P) in the π+π-π+π-, K+K-π+π- and K+K-K+K- decay modes. No clear signals for ηc(2S) production are found in these decay modes. We have also studied resonant structures in charmonium decays to two-body
intermediate meson resonances. We report the products of the two-photon decay width and the branching fractions, , for each of the charmonium decay modes.
PACS 13.25.Gv; 13.66.Bc; 14.40.Gx 相似文献
17.
A.E. Dorokhov E.A. Kuraev Yu.M. Bystritskiy M. Sečanský 《The European Physical Journal C - Particles and Fields》2008,55(2):193-198
We reconsider QED radiative corrections (RC) to the π0→e+e- decay width. One kind of RC investigated earlier has a renormalization group origin and can be associated with the final
state interaction of electron and positron. It determines the distribution of lepton pair invariant masses in the whole kinematic
region. The other type of RC has a double-logarithmic character and is related to almost on-mass-shell behavior of the lepton
form factors. The total effect of RC for π0→e+e- decay is estimated to be 3.2%, and for η→e+e- decay it is 4.3%.
PACS 13.25.Cq; 12.38.Lg; 12.38.-t 相似文献
18.
Using the data of about 33 pb-1 collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we have studied the exclusive semileptonic
decays D+→K-π+e+νe, D0→K̄0π-e+νe, D+→K̄*0e+νe and D0→K*-e+νe. The absolute branching fractions for the decays are measured to be BF(D+→K-π+e+νe)=(3.50±0.75±0.27)%, BF(D0→K̄0π-e+νe)=(2.61±1.04±0.28)%, BF(D+→K̄*0e+νe)=(5.06±1.21±0.40)% and BF(D0→K*-e+νe)=(2.87±1.48±0.39)%. The ratio of the vector to pseudoscalar semileptonic decay rates Γ(D+→K̄*0e+νe)/Γ(D+→K̄0e+νe) is determined to be 0.57±0.17±0.02. 相似文献
19.
The Mellin-Barnes representation is used to improve the theoretical estimate of mass corrections to the width of a light pseudoscalar
meson decay into a lepton pair, P → l
+
l
−. The full resummation of the terms ln(m
l
2/Λ2)(m
l
2/Λ2)
n
and (m
l
2/Λ2)
n
to the decay amplitude is performed, where m
l
is the lepton mass and Λ ≈ m
ρ is the characteristic scale of the P → γ*γ* form factor. The total effect of the mass corrections for the e
+
e
− channel is negligible and, for the μ+μ−channel, its order is of a few percent.
The text was submitted by the authors in English. 相似文献
20.
High-statistics data on the γγ → π0η reaction will make it possible to conclude whether the K
+
K
−-loop rescattering mechanism, γγ → K
+
K
− → a
0(980) → π0η, is the main mechanism of the production of a
0(980) isovector resonance. This mechanism provides a reasonable value of 20–30 nb at the maximum for the manifestation of
a
0(980) in the γγ → π0η cross section. It also gives rise to a noticeable narrowing of the a
0(980) peak to its effective (observed) width ≈20–30 MeV in the γγ → π0η channel. The decay width averaged over the resonance mass distribution is 〈Γα
0 → K
+
K
− → γγ〉πη ≈ 0.13 keV. The experimental confirmation of this scenario would be important evidence in favor of the q
2
$
\bar q
$
\bar q
2 nature of light scalar mesons. 相似文献