Studies on photo- and electro-productions of $\Lambda (1405)$ via ${\gamma }^{(\ast )}p\to K^{\ast +}{\pi }^0{\Sigma }^0$

Abstract

We study the photo- and electro-productions of the vector kaon off the proton, i.e., ${\gamma }^{(\ast )}p\to K^{\ast +}{\pi }^0{\Sigma }^0$, and investigate the line shape of the ${\pi }^0{\Sigma }^0$ invariant mass in an effective Lagrangian approach with the inclusion of a $K^{\ast }N{\Lambda }^{\ast }$ interaction. Relevant electromagnetic form factors for the neutral hyperons and charged strange mesons are constructed by considering experimental and theoretical information. We find that the ${\Lambda }^{\ast }$ peak is clearly observed for the photo- and electro-productions with the finite $K^{\ast }N{\Lambda }^{\ast }$ interaction, whereas the clear peak signals survive only for the electro-production, when we ignore the interaction. These different behaviors can be understood by different $Q^2$ dependences in the $K^{\ast }$ electromagnetic and $K^{\ast }\to \gamma K$ transition form factors. We suggest a photon-polarization asymmetry $\Sigma$ to extract information of the $K^{\ast }N{\Lambda }^{\ast }$ interaction. It turns out that $\Sigma$ near the ${\Lambda }^{\ast }$ peak region becomes negative with a finite $K^{\ast }N{\Lambda }^{\ast }$ interaction while positive without it for $Q^2=0$, due to the different naturalities of $K$ and $K^{\ast }$ exchanges. For $Q^2\ne 0$, we observe more obvious signals in the peak region due to the additional contribution of the longitudinal virtual photon for ${\Lambda }^{\ast }$.

11 pages, 6 figures

References in corpus (10)

• Nucleon Electromagnetic Form Factors
• Lattice QCD Evidence that the Lambda(1405) Resonance is an Antikaon-Nucleon Molecule
• Measurement of the Sigma pi photoproduction line shapes near the Lambda(1405)
• Electromagnetic mean squared radii of Lambda(1405) in chiral dynamics
• The leading-twist pion and kaon distribution amplitudes from the QCD instanton vacuum
• Nucleon resonances in $\gamma p\to K^{\ast +}\Lambda$
• Leading-twist pion and kaon distribution amplitudes in the gauge-invariant nonlocal chiral quark model from the instanton vacuum
• Electromagnetic Decay of the ${\Sigma }^0(1385)$ to $\Lambda \gamma$
• Interference effect between $\varphi$ and $\Lambda (1520)$ production channels in the $\gamma p\to K^{+}{K}^{-}p$ reaction near threshold
• Photo- and electroproduction of $\Lambda (1405)$ via ${\gamma }^{(\ast )}p\to K^{+}{\pi }^{+}{\Sigma }^{-}$