Accurate decay-constant ratios $f_{B^{\ast }}/f_B$ and $f_{B_s^{\ast }}/f_{B_s}$ from Borel QCD sum rules

Abstract

We present our analysis of the decay constants of the beauty vector mesons $B^{\ast }$ and $B_s^{\ast }$ within the framework of dispersive sum rules for the two-point correlator of vector currents in QCD. While the decay constants of the vector mesons $f_{B^{\ast }}$ and $f_{B_s^{\ast }}$ $-$ similar to the decay constants of the pseudoscalar mesons $f_B$ and $f_{B_s}$ $-$ individually have large uncertainties induced by theory parameters not known with a satisfactory precision, these uncertainties almost entirely cancel out in the ratios of vector over pseudoscalar decay constants. These ratios may be thus predicted with very high accuracy due to the good control over the systematic uncertainties of the decay constants gained upon application of our hadron-parameter extraction algorithm. Our final results read $f_{B^{\ast }}/f_B=0.944\pm 0.011_{\mathrm{OPE}}\pm 0.018_{\mathrm{syst}}$ and $f_{B_s^{\ast }}/f_{B_s}=0.947\pm 0.023_{\mathrm{OPE}}\pm 0.020_{\mathrm{syst}}$. Thus, both $f_{B^{\ast }}/f_B$ and $f_{B_s^{\ast }}/f_{B_s}$ are less than unity at 2.5$\sigma$ and 2$\sigma$ level, respectively.

10 pages. arXiv admin note: text overlap with arXiv:1404.0293

References in corpus (6)

• Relativistic treatment of the decay constants of light and heavy mesons
• Decay constants of the charmed vector mesons $D^{\ast }$ and $D_s^{\ast }$ from QCD sum rules
• Decay constants of heavy pseudoscalar mesons from QCD sum rules
• Systematic uncertainties of hadron parameters obtained with QCD sum rules
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• Decay Constants of Beauty Mesons from QCD Sum Rules

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• On the description of exotic hadron states within QCD sum rules