The phi--> pi^+ pi^-and phi radiative decays within a chiral unitary approach (original) (raw)

The phi to pi+ pi- decay within a chiral unitary approach

2000

Starting from the Chiral Perturbation Theory Lagrangian, but keeping different masses for the charged and neutral mesons, and using a previously developed non-perturbative unitary scheme that generates the lightest meson-meson resonances, we construct K Kbar to K Kbar and K Kbar to pi+ pi- in the vector channel. This allows us to obtain the kaon-loop contribution to the phi-rho mixing and study the phi to pi+pi- decay. The dominant contribution to this decay comes from the phi to gamma to pi+pi- process. However, there can be large interferences with the subdominant contributions coming from phi-rho and phi-omega mixing, or of these two contributions among themselves. As a consequence, a reliable measurement of phi to pi+pi- decay could be used to differentiate between some phi-omega mixing scenarios proposed in the literature.

Φ→π+π- Decay Within a Chiral Unitary Approach

Physical Review D, 2000

Starting from the Chiral Perturbation Theory Lagrangian, but keeping different masses for the charged and neutral mesons (mu = m d ), and using a previously developed non-perturbative unitary scheme that generates the lightest meson-meson resonances, we construct KK → KK and KK → π + π − in the vector channel. This allows us to obtain the kaon-loop contribution to the φ−ρ mixing and study the φ → π + π − decay. The dominant contribution to this decay comes from the φ → γ → π + π − process. However, there can be large interferences with the subdominant contributions coming from φ − ρ and φ − ω mixing, or of these two contributions among themselves. As a consequence, a reliable measurement of φ → π + π − decay could be used to differentiate between some φ − ω mixing scenarios proposed in the literature.

Η→Π0ΓΓ Decay Within a Chiral Unitary Approach

Physical Review D, 2003

We improve the calculations of the η → π 0 γγ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a 0 (980) resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition we ensure the consistency of the approach with other processes. First, by using vector meson dominance couplings normalized to agree with radiative vector meson decays. And, second, by checking the consistency of the calculations with the related γγ → π 0 η reaction. We find an η → π 0 γγ decay width of 0.47 ± 0.10 eV, in clear disagreement with published data but in remarkable agreement with the most recent measurement.

Η→Π^0 Γγ Decay Within Unitarized Chiral Perturbation Theory

2003

We improve the calculations of the η→π^0 γγ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a_0(980) resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition we ensure the consistency of the approach with other processes. First, by using vector meson dominance couplings normalized to agree with radiative vector meson decays. And, second, by checking the consistency of the calculations with the related γγ→π^0 η reaction. We find an η→π^0 γγ decay width of 0.47± 0.10 eV, in clear disagreement with published data but in remarkable agreement with the most recent measurement.

Η [Over→] Π^{0} Γγ Decay Within a Chiral Unitary Approach

2003

Discussion of the eta to pi^ 0 gamma gamma decay within a chiral unitary approach

2005

We improve the calculations of the η → π 0 γγ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a0(980) resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition we ensure the consistency of the approach with other processes. First, by using vector meson dominance couplings normalized to agree with radiative vector meson decays. And, second, by checking the consistency of the calculations with the related γγ → π 0 η reaction. We find an η → π 0 γγ decay width of 0.47 ± 0.10 eV, in clear disagreement with published data but in remarkable agreement with the most recent measurement.

Η→ Π^{0} Γγ Decay Within a Chiral Unitary Approach Revisited

2008

In view of the recent experimental developments on the experimental side in the η → π 0 γγ decay, and the fact that the Particle Data Group in the on line edition of 2007 reports sizable changes of the radiative decay widths of vector mesons used as input in the theoretical calculations of [1], a reevaluation of the decay width of the η in this channel has been done, reducing its uncertainty by almost a factor of two. The new input of the PDG is used and invariant mass distributions and total widths are compared with the most recent results from AGS, MAMI and preliminary ones of KLOE. The agreement of the theory with the AGS and MAMI data is very good, both for the total rates as well as for the invariant mass distributions of the two photons.

decays, chiral dynamics and OZI violation

Nuclear Physics A, 2001

We have studied the invariant mass distributions of the ππ and KK systems for invariant masses up to 1.2 GeV from the J/Ψ → φ ππ(KK) decays. The approach exploits the connection between these processes and the ππ and KK strange and non-strange scalar form factors by considering the φ meson as a spectator. The calculated scalar form factors are then matched with the ones from next-to-leading order chiral perturbation theory, including the calculation of the the KK scalar form factors. Final state interactions in the J/Ψ → φππ(KK) processes are taken into account as rescattering effects in the system of the two pseudoscalar mesons. A very good agreement with the experimental data from DM2 and MARK-III is achieved. Furthermore, making use of SU(3) symmetry, the S-wave contribution to the π + π − event distribution in the J/Ψ → ωπ + π − reaction is also given and the data up to energies of about 0.7 GeV are reproduced. These decays of the J/Ψ to a vector and a pair of pseudoscalars turn out to be very sensitive to OZI violating physics which we parameterize in terms of a direct OZI violation parameter and the chiral perturbation theory low energy constants L r 4 and L r 6. These constants all come out very different from zero, lending further credit to the statement that the OZI rule is subjected to large corrections in the scalar 0 ++ channel.

Scalar meson and glueball decays within a effective chiral approach

Physics Letters B, 2005

We study the strong and electromagnetic decay properties of scalar mesons above 1 GeV within a chiral approach. The scalar-isoscalar states are treated as mixed states of quarkonia and glueball configurations. A fit to the experimental decay rates listed by the Particle Data group is performed to extract phenomenological constraints on the nature of the scalar resonances. A comparison to other theoretical approaches in the scalar meson sector is discussed.

Hyperon weak radiative decays in chiral perturbation theory

Physical Review D, 1996

We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara's theorem is violated. The data for the decays of charged hyperons can be easily accounted for. However, at this order in the chiral expansion, the four amplitudes for the decays of neutral hyperons satisfy relations which are in disagreement with the data. The asymmetry parameters for all the decays can not be accounted for without higher-order terms. We shortly comment on the effect of the 27-plet part of the weak interaction.

The phi--> pi^+ pi^-and phi radiative decays within a chiral unitary approach (original) (raw)

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