Vector mesons and electromagnetic form factor of the $\Lambda$ hyperon

TL;DR

This paper investigates the electromagnetic form factors of the Lambda hyperon in the time-like region, explaining deviations from pQCD predictions through contributions from vector mesons and exotic states.

Contribution

It introduces a model incorporating below-threshold and wide vector meson contributions to explain experimental data on Lambda hyperon form factors.

Findings

Non-vanishing cross section near threshold attributed to $ ext{phi}(2170)$ state.

Significant role of a 2.34 GeV vector meson above threshold.

Model successfully describes existing data without altering pQCD expectations.

Abstract

The measured electromagnetic form factors of $\Lambda$ hyperon in the time-like region are significantly deviated from pQCD prediction. We attribute the non-vanishing cross section near threshold to be the contribution of below-threshold $\phi$(2170) state, supporting its exotic structure. Above the threshold, we find significant role of a wide vector meson with the mass of around 2.34 GeV, which would be the same state present in $p\bar{p}$ annihilation reactions. As a result, we give a satisfactory description of the behavior of existing data without modifying pQCD expectation.