اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدDecay $D^+ to K^- pi^+ pi^+$: chiral symmetry and scalar resonances
107
0
0.0
(
0
)
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The low-energy S-wave component of the decay $D^+ to K^- pi^+ pi^+$ is studied by means of a chiral SU(3)XSU(3) effective theory. As far as the primary vertex is concerned, we allow for the possibility of either direct production of three pseudoscalar mesons or a meson and a scalar resonance. Special attention is paid to final state interactions associated with elastic meson-meson scattering. The corresponding two-body amplitude is unitarized by ressumming s-channel diagrams and can be expressed in terms of the usal phase shifts $delta$. This procedure preserves the chiral properties of the amplitude at low-energies. Final state interactions also involve another phase $omega$, which describes intermediate two-meson propagation and is theoretically unambiguous. This phase is absent in the K-matrix approximation. Partial contributions to the decay amplitude involve a real term, another one with phase $delta$ and several others with phases $delta+omega$. Our main result is a simple and almost model independent chiral generalization of the usual Breit-Wigner expression, suited to be used in analyses of production data involving scalar resonances.
قيم البحث
اقرأ أيضاً
We propose a model for $D^+ to pi^+ pi^- pi^+$ decays following experimental results which indicate that the two-pion interaction in the $S$-wave is dominated by the scalar resonances $f_0(600)/sigma$ and $f_0(980)$. The weak decay amplitude for $D^+
to R pi^+$, where $R$ is a resonance that subsequently decays into $pi^+pi^-$, is constructed in a factorization approach. In the $S$-wave, we implement the strong decay $Rto pi^-pi^+$ by means of a scalar form factor. This provides a unitary description of the pion-pion interaction in the entire kinematically allowed mass range $m_{pipi}^2$ from threshold to about 3 GeV$^2$. In order to reproduce the experimental Dalitz plot for $Dppp$, we include contributions beyond the $S$-wave. For the $P$-wave, dominated by the $rho(770)^0$, we use a Breit-Wigner description. Higher waves are accounted for by using the usual isobar prescription for the $f_2(1270)$ and $rho(1450)^0$. The major achievement is a good reproduction of the experimental $m_{pipi}^2$ distribution, and of the partial as well as the total $Dppp$ branching ratios. Our values are generally smaller than the experimental ones. We discuss this shortcoming and, as a byproduct, we predict a value for the poorly known $Dto sigma$ transition form factor at $q^2=m_pi^2$.
We study the Dalitz plot of the decay D^+ --> K^- pi^+ pi^+ with a sample of 15090 events from Fermilab experiment E791. Modeling the decay amplitude as the coherent sum of known K pi resonances and a uniform nonresonant term, we do not obtain an acc
eptable fit. If we allow the mass and width of the K^*_0(1430) to float, we obtain values consistent with those from PDG but the chi^2 per degree of freedom of the fit is still unsatisfactory. A good fit is found when we allow for the presence of an additional scalar resonance, with mass 797 +/- 19 +/- 43 MeV/c^2 and width 410 +/- 43 +/- 87 MeV/c^2. The mass and width of the K^*_0(1430) become 1459 +/- 7 +/- 5 MeV/c^2 and 175 +/- 12 +/- 12 MeV/c^2, respectively. Our results provide new information on the scalar sector in hadron spectroscopy.
Using $2.93 rm fb^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-pi^0$ is reported. After removing decays tha
t contain narrow intermediate resonances, including $D^+to K^+eta$, $D^+to K^+omega$, and $D^+to K^+phi$, the branching fraction of the decay $D^+to K^+pi^+pi^-pi^0$ is measured to be $(1.13 pm 0.08_{rm stat} pm 0.03_{rm syst})times 10^{-3}$. The ratio of branching fractions of $D^+to K^+pi^+pi^-pi^0$ over $D^+to K^-pi^+pi^+pi^0$ is found to be $(1.81pm0.15)$%, which corresponds to $(6.28pm0.52)tan^4theta_C$, where $theta_C$ is the Cabibbo mixing angle. This ratio is significantly larger than the corresponding ratios for other doubly Cabibbo-suppressed decays. The asymmetry of the branching fractions of charge-conjugated decays $D^pmto K^pmpi^pmpi^mppi^0$ is also determined, and no evidence of $CP$ violation is found. In addition, the first evidence of the $D^+to K^+omega$ decay, with a statistical significance of 3.3$sigma$, is presented and its decay branching fraction is determined to be $({5.7^{+2.5}_{-2.1}}_{rm stat}pm0.2_{rm syst})times10^{-5}$.
We briefly review the recent results obtained by Fermilab experiment E791 on the Dalitz plot analysis of the decay D+ -> K- pi+ pi+, where indication for a light Kpi scalar resonance, the kappa, was found. We also present preliminary studies providin
g further information on the phase behavior of the scalar components at low mass, supporting the previous indication for the kappa.
The N*(1440) -> N pi pi decay is studied by making use of the chiral reduction formula. This formula suggests a scalar-isoscalar pion-baryon contact interaction which is absent in the recent study of Hern{a}ndez et al. The contact interaction is intr
oduced into their model, and is found to be necessary for the simultaneous description of g_{RN pi pi} and the pi-pi and pi-N invariant mass distributions.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
