Density matrix for polarization of high-spin particles

Could large CP-violation be detected at colliders?

“…Background from production of Z + g(→ bb) will necessarily be present but will not produce a CP-violation effect. The analysis is similar to that for bW + → th, with the Z polarization vector replacing the top spin direction, and in practice the Z polarization is analyzed by its decay into l + l − or into qq [18]. For qq → Zh at FNAL, the initial q andq carry approximately equal fractions of the beam momentum so that it is necessary to use observables independent of the directions of the incoming momenta as written in Table 1.…”

Erratum: Polarization effects inB→K1(1270)+J/ψKrämer1, Song2, Yu3 2002Phys. Rev. DSelf Cite2010View full textAdd to dashboardCite

“…Following the earlier work the angular correlation for the decay chain B → K 1 J/ψ, K 1 → Kρ and J/ψ → l + l − can be derived as well either in the helicity or the transversity basis. Since the matrix elements of the two decay processes B → K * J/ψ and B → K 1 J/ψ have the same Lorentz covariant form, although the invariant form factors can be different in size and CP properties, it is more convenient to apply the method of covariant density matrices [11] instead. Then it is quite simple to incorporate the fact that the two subsequent decays K * → Kπ and K 1 → Kρ produce different contributions in the decay density matrix of the J/ψ.…”

“…Here, the ensemble averaged value ǫ µ (q)ǫ * ν (q) can be replaced by the covariant density matrix ρ µν of the J/ψ which is obtained explicitly from the B decay process into the J/ψ. The most general form of ρ µν can be written as [11] …”

Choice of heavy baryon currents in QCD sum rules

“…In the heavy quark limit, the matrix element of current J can be parameterized by one or two scalar functions of y. Those scalar functions are called Isgur-Wise functions [19] and can be defined as…”