Search results for "Isospin"
showing 10 items of 264 documents
Observation of the isospin-violating decayJ/ψ→ϕπ0f0(980)
2015
Using a sample of 1.31 x 10(9) J/psi events collected with the BESIII detector at the BEPCII collider, the decays J/psi -> phi pi(+)pi(-)pi(0) and J/psi -> phi pi(0)pi(0)pi(0) are investigated. The isospin- violating decay J/psi -> phi pi(0)f(0)(980) with f(0)(980)-> pi pi is observed for the first time. The width of the f(0)(980) obtained from the dipion mass spectrum is found to be much smaller than the world average value. In the pi(0)f(0)(980) mass spectrum, there is evidence of f(1)(1285) production. By studying the decay J/psi ->eta', the branching fractions of eta' -> pi(+)pi(-)pi(0) and eta' -> pi(0)pi(0)pi(0), as well as their ratio, are also measured.
Measurement of branching fractions andCPand isospin asymmetries forB→K*γ
2004
We present a preliminary analysis of the decays B{sup 0} {yields} K*{sup 0}{gamma} and B{sup +} {yields} K*{sup +}{gamma} using a sample of 383 million B{bar B} events collected with the BABAR detector at the PEP-II asymmetric energy B factory. We measure the branching fractions {Beta}(B{sup 0} {yields} K*{sup 0}{gamma}) = (4.58 {+-} 0.10 {+-} 0.16) x 10{sup -5} and {Beta}(B{sup +} {yields} K*{sup +}{gamma}) = (4.73 {+-} 0.15 {+-} 0.17) x 10{sup -5}. We measure the direct CP asymmetry to be -0.043 < {Alpha}(B {yields} K*{gamma}) < 0.025 and the isospin asymmetry to be -0.021 < {Delta}{sub 0-} < 0.079, where the limits are determined at the 90% confidence interval and include both the statis…
Measurement of theτ−→ηπ−π+π−ντbranching fraction and a search for a second-class current in theτ−→η′(958)π−ντdecay
2008
The τ-→ηπ-π+π-ντ decay with the η→γγ mode is studied using 384 fb-1 of data collected by the BABAR detector. The branching fraction is measured to be (1.60±0.05±0.11)×10-4. It is found that τ-→f1(1285)π-ντ→ηπ-π+π-ντ is the dominant decay mode with a branching fraction of (1.11±0.06±0.05)×10-4. The first error on the branching fractions is statistical and the second systematic. Note that no particle identification algorithm is applied to the charged tracks to distinguish pions from kaons. In addition, a 90% confidence level upper limit on the branching fraction of the τ-→η′(958)π-ντ decay is measured to be 7.2×10-6. This last decay proceeds through a second-class current and is expected to …
Measurements of directCPasymmetries inB→Xsγdecays using sum of exclusive decays
2014
We measure the direct CP violation asymmetry, A_(CP), in B→X_sγ and the isospin difference of the asymmetry, ΔA_(CP), using 429 fb^(−1) of data collected at Υ(4S) resonance with the BABAR detector at the PEP-II asymmetric-energy e^+e^− storage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from ten charged B final states and six neutral B final states. We find A_(CP)=+(1.7±1.9±1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between A_(CP) for charged and neutral decay modes, ΔA_(CP)=+(5.0±3.9±1.5)%. Using the value of ΔA_(CP)…
Measurements of new physics inB→ππdecays
2005
If new physics (NP) is present in B{yields}{pi}{pi} decays, it can affect the isospin I=2 or I=0 channels. In this paper, we discuss various methods for detecting and measuring this NP. The techniques have increasing amounts of theoretical hadronic input. If NP is eventually detected in B{yields}{pi}{pi}--there is no evidence for it at present--one will be able to distinguish I=2 and I=0, and measure its parameters, using these methods.
Empirical parameterization of the K±→π±π0π0 decay Dalitz plot
2010
As first observed by the NA48/2 experiment at the CERN SPS, the π0π0 invariant mass (M00) distribution from K±→π±π0π0 decay shows a cusp-like anomaly at M00=2m+, where m+ is the charged pion mass. An analysis to extract the ππ scattering lengths in the isospin I=0 and I=2 states, a0 and a2, respectively, has been recently reported. In the present work the Dalitz plot of this decay is fitted to a new empirical parameterization suitable for practical purposes, such as Monte Carlo simulations of K±→π±π0π0 decays.
χ c0 (1 P ) decay intoΣ¯ Σπin search of an I = 1, 1/2 − baryon state aroundK¯Nthreshold
2016
Abstract We present the theoretical study of the process χ c 0 ( 1 P ) → Σ ¯ Σ π decay, by taking into account the π Σ and π Σ ¯ final state interactions of the final meson-baryon pair based on the chiral unitary approach. We show that the process filters the isospin I = 1 in the π Σ channel and offers a reaction to test the existence of an I = 1 state with strangeness S = − 1 and spin-parity J p = 1 / 2 − around the K ¯ N threshold predicted by some theories and supported by some experiments.
Study ofBB¯*andB*B¯*interactions inI=1and relationship to theZb(10610),Zb(10650)states
2015
We use the local hidden gauge approach in order to study the $B{\overline{B}}^{*}$ and ${B}^{*}{\overline{B}}^{*}$ interactions for isospin $I=1$. We show that both interactions via one light meson exchange are not allowed by the Okubo-Zweig-Iizuka rule and, for that reason, we calculate the contributions due to the exchange of two pions, interacting and noninteracting among themselves, and also due to the heavy vector mesons. Then, to compare all these contributions, we use the potential related to the heavy vector exchange as an effective potential corrected by a factor which takes into account the contribution of the other light meson exchanges. In order to look for poles, this effective…
Chiral unitary approach to s-wave meson baryon scattering in the strangeness S=0 sector
2001
We study the S-wave interaction of mesons with baryons in the strangeness S=0 sector in a coupled channel unitary approach. The basic dynamics is drawn from the lowest order meson baryon chiral Lagrangians. Small modifications inspired by models with explicit vector meson exchange in the t-channel are also considered. In addition the pi pi N channel is included and shown to have an important repercussion in the results, particularly in the isospin 3/2 sector.
Thresholdπ0photoproduction in relativistic chiral perturbation theory
2013
We present a calculation of $\pi^0$ photoproduction on the proton in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including chiral order $q^4$. With the results we analyze the latest $\pi^0$ photoproduction data in the threshold region obtained at the Mainz Microtron. In the calculation of observables and the fit of the low-energy constants, we take $S$, $P$, and $D$ waves into account. We compare the results for the multipoles with the corresponding single-energy analysis. Furthermore, we also fit the $O(q^4)$ heavy-baryon chiral perturbation theory calculation and compare both results. We provide predictions for several polarization observables for future exper…