Strange-quark mass from combined e+e− and τ-decay data: test of the isospin symmetry and implications on ϵ′/ϵ and mu,d

1999/05/31 by Stéphan Narison, Stephan Narison · 5 citations
Physics and Astronomy · #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #hep-ex #hep-lat #hep-ph #nucl-th

paper · pdf · doi:10.1016/s0370-2693(99)01093-x

published as Phys.Lett.B466:345-354,1999 · Latex2e sources 11 pages + 1 table. Revised version written on July 99 to appear in Phys. Lett. B

arxiv created 1999/09/23 · openalex publication_date 1999/11/01 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28

Abstract

I extract the strange-quark mass using a τ-like decay sum rule for the ϕ-meson, and some other sum rules involving its difference with the vector component of the hadronic τ-decay. As a conservative estimate, one obtains to order α_s³: m_s(1 GeV) = (178± 33) MeV \lrar \~m_s(2 GeV) = (129± 24) MeV, while the positivity of the spectral function leads to the upper bound: m_s(1 \rm GeV)≤ (200± 28) MeV \Longrightarrow~m_s(2~\rm GeV)≤ (145± 20) MeV. These results are in good agreement with the existing sum rule and τ-decay results, and, in particular, with the result from the the sum rule involving the difference of the isoscalar and isovector components of the e⁺e^-\rar hadrons data. This signals small effects of the SU(2) isospin violation due to the ω-ρ mixing parameters, and questions the reliability of the existing sum rule estimates of these parameters. Combining our result with the recent data on ε'/ε, we can estimate, within the standard model, the four-quark weak matrix elements B₆^1/2-0.54 B^3/2₈ to be about (2.8± 1.3). This result may suggest a large violation of the vacuum saturation estimate similarly to the case of the four-quark condensates obtained from the sum rules analysis, and can serve as a guide for a future accurate non-perturbative extraction of such matrix elements. Combining our result with the sum rule estimate of m_u+m_d and with the Dashen formula for the mass ratio, one can deduce the update values: m_d(2 \rm GeV)= (6.4± 1.1) \rm MeV and m_u(2 \rm GeV)= (2.3± 0.4) \rm MeV.

Citations

• Light quark masses in QCD
• The strange quark mass from QCD sum rules

Cited by

• Open charm and beauty chiral multiplets in QCD
• Are the pentaquark sum rules reliable?
• Non-lattice determinations of the light quark masses
• Do the QCD sum rules support four-quark states?
• Strange quark mass frome+e−revisited and present status of light quark masses