共查询到20条相似文献,搜索用时 12 毫秒
1.
Bastian Kubis Sebastian P. Schneider 《The European Physical Journal C - Particles and Fields》2009,62(3):511-523
Strong final-state interactions create a pronounced cusp in η′→η
π
0
π
0 decays. We adapt and generalize the non-relativistic effective field theory framework developed for the extraction of π
π scattering lengths from K→3π decays to this case. The cusp effect is predicted to have an effect of more than 8% on the decay spectrum below the π
+
π
− threshold. 相似文献
2.
Christoph?Ditsche Bastian?Kubis Ulf-G.?Mei?ner 《The European Physical Journal C - Particles and Fields》2009,60(1):83-105
We re-evaluate the electromagnetic corrections to η→3π decays at next-to-leading order in the chiral expansion, arguing that effects of order e
2(m
u
−m
d
) disregarded so far are not negligible compared to other contributions of order e
2 times a light-quark mass. Despite the appearance of the Coulomb pole in η→π
+
π
−
π
0 and cusps in η→3π
0, the overall corrections remain small. 相似文献
3.
4.
Bochao?Liu Markus?Büscher Feng-Kun?Guo Christoph?Hanhart Ulf-G.?Mei?ner 《The European Physical Journal C - Particles and Fields》2009,63(1):93-99
We investigate the interplay between crossed channel final state interactions and the constraints from two-particle unitarity
for the reactions J/ψ→V
π
π and
VK[`(K)]VK\bar{K}
, where V is either ω or φ. Using a model where the parameters are largely constrained by other sources, we find that, although small, crossed channel
final state interaction can influence the amplitudes considerably, in special areas of phase space. These results cast doubt
on the inapplicability of unitarity constraints on production amplitudes as recently claimed in the literature. 相似文献
5.
The rare decay \(B\rightarrow {K^{*}}\ell ^+\ell ^-\) is a very significant mode to search for physics beyond the Standard Model (SM). The mode provides a very rich spectrum of observables obtained from the angular distribution of its decay products. The recent LHCb measured values of these observables are used to conclude an evidence of right-handed currents at the kinematic endpoint of this decay mode. As the conclusion is drawn at the maximum dilepton invariant mass square (\(q^2\)) kinematic endpoint, it relies only on heavy quark symmetries where it is valid without significant corrections. 相似文献
6.
7.
The process γ*γ → σ is investigated in the framework of the SU(2)×SU(2) chiral NJL model. The form factor of the process is derived for arbitrary virtuality of γ* in the Euclidean kinematic domain. The asymptotic behavior of this form factor resembles the asymptotic behavior of the γ*γ → π form factor. 相似文献
8.
Ya. I. Azimov 《Physics of Atomic Nuclei》2003,66(11):1989-1993
The influence of isospin-violating (ρ0, ω) mixing is discussed for any pair of decays of ρ0, ω into the same final state. It is demonstrated, in analogy to the CP violation in neutral kaon decays, that isospin violation can manifest itself in various forms: direct violation in amplitudes and/or violation due to mixing. In addition to the known decays (ρ0, ω) → π+π? and (ρ0, ω) → π0γ, the pair of decays to e+e? and the whole set of radiative decays with participation of ρ0, ω (in initial or final states) are also shown to be useful and promising for studies. Existing data on these decays agree with the universal character of the mixing parameter and indirectly support enhancement of ρ0 → π0γ in respect to ρ± → π±γ. Future precise measurements will allow one to separate different forms of isospin violation and elucidate their mechanisms. 相似文献
9.
The hyperfine splittings in heavy quarkonia are studied in a model-independent way using experimental data on dielectron widths.
Relativistic correlations are taken into account together with the smearing of spin-spin interaction. The radius of smearing
is fixed by known G/ψ−η
c(1S), ψ(2S)−η
c′(2S) splittings, which appears to be small, r
ss ≅ 0.06 fm. Nevertheless, even with such a small radius, substantial suppression of hyperfine splittings (∼50%) is observed
in bottomonium. For nS b
states (n = 1, 2, ..., 6), our predicted splittings (in MeV) are 28, 12, 10, 5, 6, 3. For the 3S and 4S charmonium states, the splittings 16(2) and 12(4) MeV are obtained.
The text was submitted by the authors in English. 相似文献
10.
A. Margaryan O. Hashimoto V. Kakoyan S. Knyazyan L. Tang 《Physics of Atomic Nuclei》2011,74(2):216-220
A new “tagged-weak π method” is proposed for determination of electromagnetic transition probabilities B(E2) and B(M1) of the hypernuclear states with lifetimes of ∼10−10 s. With this method, we are planning to measure B(E2) and B(M1) for light hypernuclei at JLab. The results of Monte Carlo simulations for the case of E2(5/2+, 3/2+ → 1/2+) transitions in Λ7He hypernuclei are presented. 相似文献
11.
12.
13.
Theoretically motivated smallness of the penguin amplitude in B → ππ decays allows one to calculate the value of the unitarity-triangle angle α(ø 2) with good accuracy. The relatively large branching ratio of the decay into π 0 π 0 is explained by the large value of FSI phase difference between decay amplitudes with I = 0 and I = 2. 相似文献
14.
15.
Behnam Mohammadi 《Physics of Particles and Nuclei Letters》2017,14(6):886-891
I present estimates of CP-violating asymmetries in the non-leptonic charmonium two-body B0→ψ(2S)π0 decay and the same decays of B+→ψ(2S)π+ and B+→ψ(2S)K+ These estimates are based on QCD and improved QCD factorization approach making use of next-to-leading order (NLO) contributions. The CP-violating asymmetry for B0→ψ(2S)π0 decay is not available, according to the same calculations, it is expected if it can be measured in the future its value will be Sψ(2S)π0(B0 → ψ(2S)π0)= 0.662 ± 0.197 and Cψ(2S)π0(B0 → ψ(2S)π0)= 0.024 ± 0.007. 相似文献
16.
We study the effect of Z′-mediated flavor-changing neutral current on the B → ππ decays. The branching ratios of these decays can be enhanced remarkably in the nonuniversal Z′ model. Our estimated branching ratios B(B 0 → π 0 π 0) are enhanced significantly from their standard model (SM) value. For g′/g = 1, the branching ratios B(B 0 → π 0 π 0) are very close to the recently observed experimental values and for higher values of g′/g branching ratios are more. Our calculated branching ratios B(B 0 → π + π ?) and B(B + → π + π 0) are also enhanced from the SM value as well as the recently observed experimental values. These enhancements of branching ratios from their SM value give the possibility of new physics. 相似文献
17.
S. P. Baranov A. V. Lipatov N. P. Zotov 《The European Physical Journal C - Particles and Fields》2011,71(4):1631
We investigate the inclusive photoproduction of J/ψ mesons at HERA within the framework of the k
T
-factorization QCD approach. Our study is based on the color singlet model supplemented with the relevant off-shell matrix
elements and the CCFM and KMR unintegrated gluon densities in a proton and in a photon. Both the direct and resolved photon
contributions are taken into account. Our predictions are compared with the recent experimental data taken by the H1 and ZEUS
collaborations. Special attention is put on the J/ψ polarization parameters λ and ν, which are sensitive to the production dynamics. 相似文献
18.
Xiang Liu Zheng-Tao Wei Xue-Qian Li 《The European Physical Journal C - Particles and Fields》2009,59(3):683-689
To test the validity of perturbative QCD (pQCD) and investigate its range of application, one should look for a suitable process.
B→J/ψ
D is a promising candidate. The linear momentum of the products is relatively small, so that there may exist a region where
exchanged gluons are soft and the perturbative treatment may fail, so that the non-perturbative effect would be significant.
We attribute such non-perturbative QCD effects to the long-distance final-state interaction (FSI) which is estimated in this
work. We find that the contribution from the FSI to the branching ratio is indeed sizable and may span the rather wide range
of 10−6∼10−5 and cover a region where the pQCD prediction is of the same order. A more accurate measurement of its branching ratio may
provide important information about the application region of pQCD and help to clarify the picture of inelastic rescattering
(i.e. FSI), which is generally believed to play an important role in B decays. 相似文献
19.
Francesco Renga 《Hyperfine Interactions》2018,239(1):58
The quest for μ → eγ is one of the most important endeavors to search for New Physics beyond the Standard Model. In this talk I will review the current status of the experimental searches by the MEG Collaboration at PSI. I will also present a study of the experimental limiting factors that will define the ultimate performances, and hence the sensitivity, in the search for μ → eγ with continuous muon beams of extremely high rate (one or even two orders of magnitude larger than the present beams), whose construction is under consideration for the next decade. 相似文献
20.
V. Ya. Kirpichenkov N. V. Kirpichenkova O. I. Lozin A. A. Postnikov 《Bulletin of the Russian Academy of Sciences: Physics》2016,80(5):533-535
A formula for the relaxation time of Josephson plasmons on random quantum jumpers, i.e., quantum resonant-percolation trajectories (QRPT) in a disordered I-layer of a tunnel S–I–S junction is derived. Domain Ωr (μ ? E0, c), in which the strongest plasmon damping takes place, is plotted in the plane of parameters (μ ? E0, c). 相似文献