Strange quark mass from the invariant mass distribution of Cabibbo-suppressed tau decays

Abstract

Quark mass corrections to the τ hadronic width play a significant role only for the strange quark, hence providing a method for determining its mass. The experimental input is the vector plus axial-vector strange spectral function derived from a complete study of tau decays into strange hadronic final states performed by ALEPH. New results on strange decay modes from other experiments are also incorporated. The present analysis determines the strange quark mass at the Mτ mass scale using moments of the spectral function. Justified theoretical constraints are applied to the nonperturbative components and careful attention is paid to the treatment of the perturbative expansions of the moments which exhibit convergence problems. The result obtained, ms(M 2 τ ) = (120 ± 11exp ± 8V us ± 19 th ) MeV = (120 +21 −26 ) MeV, is stable over the scale from Mτ down to about 1.4 GeV. Evolving this result to customary scales yields ms(1 GeV 2 ) = (160 +28 −35 ) MeV and ms(4 GeV 2 ) = (116 +20 −25 ) MeV.

Tau Physics 2006: Summary & Outlook

“…The separate measurement of the |∆S| = 0 and |∆S| = 1 τ decay widths allows us to pin down the SU(3) breaking effect induced by the strange quark mass [55,56,57,58,59,60,61], through the differences [56] …”

τ − →K − η (′) ν τ decays in Chiral Perturbation Theory with resonances

“…At the (semi-)inclusive level this allows to extract fundamental parameters of the Standard Model, most importantly the strong coupling α S [9][10][11][12]. Tau decays containing Kaons have been split into the Cabibbo-allowed and suppressed decays [13,14] rendering possible determinations of the quark-mixing matrix element |V us | [15,16] and the mass of the strange quark [17][18][19][20][21][22][23][24][25] at high precision.…”

Light quark masses from scalar sum rules

“…Until today, two main methods have been employed to determine the strange quark mass. QCD sum rules [4][5][6][7] have been applied to various channels containing strange quantum numbers, in particular the scalar channel that will be the subject of this work [8][9][10][11][12][13][14][15], the pseudoscalar channel [16], the Cabibbo suppressed τ -decay width [17][18][19][20][21][22][23], as well as the total e + e − cross section [24][25][26][27]. Also lower bounds on the strange mass have been determined in the framework of QCD sum rules [16,[28][29][30][31].…”