Hadronic structure functions in thee+e−→Λ¯

Abstract

Cross-section distributions are calculated for the reaction e + e − → J/ψ →Λ(→pπ + )Λ(→ pπ − ), and related annihilation reactions mediated by vector mesons. The hyperon-decay distributions depend on a number of structure functions that are bilinear in the, possibly complex, psionic form factors G ψ M and G ψ E of the Lambda hyperon. The relative size and relative phase of these form factors can be uniquely determined from the unpolarized joint-decay distributions of the Lambda and anti-Lambda hyperons. Also the decay-asymmetry parameters of Lambda and anti-Lambda hyperons can be determined.

Measurement of the weak mixing angle at a Super Charm-Tau factory with data-driven monitoring of the average electron beam polarization

“…As in ref. [8], we introduce the basis vectors of the right-handed coordinate system in the rest frame of the Λ-hyperon (Λ frame)…”

Sequential hyperon decays in the reaction e+e−→Σ0Σ¯0

“…In Ref. [5] annihilation in the region of the J/ψ and ψ(2S) masses is considered. The photon propagator of Fig.1 is then replaced by the appropriate vector-meson propagator.…”

Production and sequential decay of charmed hyperons

“…To this end we consider the reaction e þ e − → Λ þ cΛ − c , which is analyzed in detail in Refs. [1,2]. In order to describe such an annihilation process two hadronic form factors are needed, commonly denoted G E and G M .…”

“…For their precise definitions we refer to Ref. [2]. At the Λ cΛc threshold G E ¼ G M leading to a vanishing ΔΦ.…”

“…In our application, however, we sum over the decay products of the antihyperonΛ The scattering distribution function for the Λ þ c hyperon production becomes, according to Refs. [1,2], proportional to…”