Search results for "Functional analysis"
showing 10 items of 1059 documents
The χ decay to ϕK⁎K¯,ϕh1(1380) testing the nature of axial vector meson resonances
2019
Abstract We perform a theoretical study of the χ c J → ϕ K ⁎ K ¯ → ϕ K π K ¯ reaction taking into account the K ⁎ K ¯ final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the h 1 ( 1380 ) given the selection of quantum numbers. Based on this picture we can easily explain why in the χ c 0 decay the h 1 ( 1380 ) resonance is not produced, and, in the case of χ c 1 and χ c 2 decay, why a dip in the K + π 0 K − mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the resc…
Search for muoproduction of X(3872) at COMPASS and indication of a new state X˜(3872)
2018
Abstract We have searched for exclusive production of exotic charmonia in the reaction μ + N → μ + ( J / ψ π + π − ) π ± N ′ using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J / ψ π + π − mass distribution we observe a signal with a statistical significance of 4.1 σ. Its mass and width are consistent with those of the X ( 3872 ) . The shape of the π + π − mass distribution from the observed decay into J / ψ π + π − shows disagreement with previous observations for X ( 3872 ) . The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X ( 3872 ) with C = − 1 predicted b…
ON THE NATURE OF THE X(3872)
2010
We present recent studies of charmonium multiquark states. We use different interacting models and numerical methods to study deeply bound four-quark states and meson-meson molecules. No deeply bound four-quark states are found in our analysis. A nice description of the X(3872) is obtained as a $D\bar{D}^*-J/\Psi\omega$ coupled channel state.
The g-factor of the J?=12+ isomeric state in188Hg
1983
Using the reaction175Lu(19F, 6n) theg-factor of the188Hg isomeric state (Jπ=12+,T1/2=135 ns) has been measured with the TDPAD method. The experimental value g=−0.168(10) supports the interpretation of an almost pure (vi13/2)−2 configuration for this isomer.
Character of an 8− isomer of 130Ba
2002
Abstract The static moments and isomer shift of the J π = K π =8 − isomeric state in 130 56 Ba have been measured using the technique of collinear laser spectroscopy. The isomer has been found to have a magnetic dipole moment of −0.043(28) μ N and a static quadrupole moment of +2.77(30) b. These values have been used to assign the state as a two neutron 7 2 + [404]⊗ 9 2 − [514] configuration corresponding to a prolate shape. The half-life of the isomer has been confirmed as 9.54(14) ms. The change in the mean square charge radius was found to be 〈 r 2 〉 130m −〈 r 2 〉 130g–s =−0.0473(30) fm 2 .
Chiral unitary approach to hadron spectroscopy
2002
The s-wave meson-baryon interaction in the $S = -1$, $S= 0$ and $S= -2$ sectors is studied by means of coupled channels, using the lowest-order chiral Lagrangian and the N/D method or equivalently the Bethe-Salpeter equation to implement unitarity. This chiral approach leads to the dynamical generation of the $\Lambda (1405)$, $\Lambda(1670)$ and $\Sigma(1620)$ states for $S = -1$, the $N^*(1535)$ for $S= 0$ and the $\Xi(1620)$ for $S= -2$. We look for poles in the complex plane and extract the couplings of the resonances to the different final states. This allows identifying the $\Lambda (1405)$ and the $\Lambda(1670)$ resonances with $\bar{K}N$ and $K\Xi$ quasibound states, respectively. …
High-statistics measurement of the β-delayed α spectrum of 20Na
2013
A measurement of the 20Na β-delayed alpha spectrum with a high-granularity setup has allowed the decay scheme to be revised on several points. Three new transitions of low intensity are found at low α -particle energy. An R-matrix fit of the complete spectrum gives an improved description of the decay and indicates feeding to the broad 2+ α-cluster state close to 9MeV. c Societa Italiana di Fisica / Springer-Verlag 2013
Experimental review of e + e − →ππh c
2016
We review the recent BESIII measurement of e+e− → ππhc in which its line shape is studied between the center-of-mass energies of 3.9 to 4.42 GeV and an iso-vector charmonium-like state Zc(4020) is observed in the invariant mass of πhc at the BESIII experiment. The charged Zc(4020)± is the second observed Zc state following Zc(3900), while the Zc(4020)0 is the first observed neutral Zc state. The line shape of σ(e+e− → ππhc) is also re-analyzed in view of searching for the Y state and the existence of the Y(4220) state is confirmed and compared with the previous work of the BESIII experiment.
Reanalysis of thee+e−→(D*D¯*)±π∓reaction and the claim for theZc(4025)resonance
2014
In this paper we study the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{({D}^{*}{\overline{D}}^{*})}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}$ in which the BESIII collaboration has claimed the existence of a ${1}^{+}$ resonance, named ${Z}_{c}(4025)$, in the ${D}^{*}{\overline{D}}^{*}$ invariant mass spectrum with a mass around 4026 MeV and width close to 26 MeV . We determine the ${D}^{*}{\overline{D}}^{*}$ invariant mass distribution and find that although the explanation considered by the BESIII collaboration is plausible, there are others which are equally possible, like a ${2}^{+}$ resonance or a bound state. Even more, we find that the data …
The electroweak sector of the NMSSM at the one-loop level
2010
We present the electroweak spectrum for the Next-to-Minimal Supersymmetric Standard Model at the one-loop level, e. g. the masses of Higgs bosons, sleptons, charginos and neutralinos. For the numerical evaluation we present a mSUGRA variant with non-universal Higgs mass parameters squared and we compare our results with existing ones in the literature. Moreover, we briefly discuss the implications of our results for the calculation of the relic density.