Using Kaon Regeneration to Probe the Quark Mixing Parameter <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="normal">cos</mi><mn>2</mn><mi>β</mi></math></span> in <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">B</mi><mi></mi><mo>→</mo><mi>ψ</mi><mi mathvariant="italic">K</mi></math></span> Decays

Helen R. Quinn; Thomas Schietinger; João P. Silva; Arthur E. Snyder

doi:10.1103/PhysRevLett.85.5284

Using Kaon Regeneration to Probe the Quark Mixing Parameter $\cos 2 β$ in $B \to ψ K$ Decays

Helen R. Quinn, Thomas Schietinger, João P. Silva, and Arthur E. Snyder

Phys. Rev. Lett. 85, 5284 – Published 18 December 2000

Abstract

We suggest a novel method to determine the sign of $\cos 2 β$ in the decays $B \to ψ K$ , by creating interference between $K_{L}$ and $K_{S}$ final states via “regeneration,” that is propagation through a matter target region to convert some $K_{L}$ to $K_{S}$ . The determination of this quantity resolves an ambiguity between $β$ and $90 ° - β$ that remains after the standard measurements of $\sin 2 β$ and may turn out to be important in resolving whether the result is in agreement with standard model predictions or indicates the presence of new physics. We find the measurement is feasible at a $B$ factory, but requires several years of high-luminosity running with a regeneration target affecting a significant fraction of the detector.