First Observation of the $\Lambda (1405)$ Line Shape in Electroproduction

Abstract

We report the first observation of the line shape of the $\Lambda (1405)$ from electroproduction, and show that it is not a simple Breit-Wigner resonance. Electroproduction of $K^{+}\Lambda (1405)$ off the proton was studied by using data from CLAS at Jefferson Lab in the range $1.0<Q^2<3.0$ (GeV/c)${}^2$. The analysis utilized the decay channels ${\Sigma }^{+}{\pi }^{-}$ of the $\Lambda (1405)$ and $p{\pi }^0$ of the ${\Sigma }^{+}$. Neither the standard (PDG) resonance parameters, nor free parameters fitting to a single Breit-Wigner resonance represent the line shape. In our fits, the line shape corresponds approximately to predictions of a two-pole meson-baryon picture of the $\Lambda (1405)$, with a lower mass pole near 1368 MeV/c${}^2$ and a higher mass pole near 1423 MeV/c${}^2$. Furthermore, with increasing photon virtuality the mass distribution shifts toward the higher mass pole.

8 pages, 8 figures. Version 2 has some added references; submitted to Phys. Rev. C

References in corpus (5)

• Measurement of the Sigma pi photoproduction line shapes near the Lambda(1405)
• New insights into antikaon-nucleon scattering and the structure of the Lambda(1405)
• Lineshape of the Lambda(1405) Hyperon Measured Through its Sigma0 pion0 Decay
• Photoproduction of Lambda(1405) and Sigma^{0}(1385) on the proton at E_γ= 1.5-2.4 GeV
• Kaonic production of Lambda(1405) off deuteron target in chiral dynamics

Cited by in corpus (23)

• Comprehensive analysis of the wave function of a hadronic resonance and its compositeness
• Two-pole structures in QCD: Facts, not fantasy!
• On the isospin 0 and 1 resonances from $\pi \Sigma$ photoproduction data
• Review of the $\mathbf{\Lambda }$(1405): A curious case of a strange-ness resonance
• QCD and the Strange Baryon Spectrum
• A chiral covariant approach to $\rho \rho$ scattering
• Interactions between vector mesons and dynamically generated resonances
• Cross-channel constraints on resonant antikaon-nucleon scattering
• Hyperon resonances coupled to pseudoscalar- and vector-baryon channels
• Photoproduction of $\Lambda (1405)$ with the $N^{\ast }$ and $t$-channel Regge contributions
• Antineutrino induced Lambda(1405) production off the proton
• Are the chiral based $\bar{K}N$ potentials really energy dependent?
• Photoproduction of ${\Lambda }^{\ast }$ and ${\Sigma }^{\ast }$ resonances with $J^P=1/2^{-}$ off the proton
• Determination of compositeness of the Lambda(1405) resonance from its radiative decay
• Pole position of $\Lambda (1405)$ measured in $d(K^{-},n)\pi \Sigma$ reactions
• Investigation of the Lambda(1405) line shape observed in pp collisions
• Decay properties of $N^{\ast }(1895)$
• Pole trajectories of the $\Lambda (1405)$ helps establish its dynamical nature
• Faddeev approach to the reaction $K^{-}d\to \pi \Sigma n$ at $p_K=1$ GeV/c
• Photo- and electroproduction of $\Lambda (1405)$ via ${\gamma }^{(\ast )}p\to K^{+}{\pi }^{+}{\Sigma }^{-}$
• Exotic properties of N^*(1895) and its impact on photoproduction of light hyperons
• The $\bar{K}N$ interaction in higher partial waves
• Studies on photo- and electro-productions of $\Lambda (1405)$ via ${\gamma }^{(\ast )}p\to K^{\ast +}{\pi }^0{\Sigma }^0$