pdgLive

LIGHT UNFLAVORED MESONS
($\mathit S$ = $\mathit C$ = $\mathit B$ = 0)
For $\mathit I = 1$ (${{\mathit \pi}}$, ${{\mathit b}}$, ${{\mathit \rho}}$, ${{\mathit a}}$): ${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit d}}}$, (${\mathit {\mathit u}}$ ${\mathit {\overline{\mathit u}}}−{\mathit {\mathit d}}$ ${\mathit {\overline{\mathit d}}})/\sqrt {2 }$, ${\mathit {\mathit d}}$ ${\mathit {\overline{\mathit u}}}$;
for $\mathit I = 0$ (${{\mathit \eta}}$, ${{\mathit \eta}^{\,'}}$, ${{\mathit h}}$, ${{\mathit h}^{\,'}}$, ${{\mathit \omega}}$, ${{\mathit \phi}}$, ${{\mathit f}}$, ${{\mathit f}^{\,'}}$): ${\mathit {\mathit c}}_{{\mathrm {1}}}({{\mathit u}}{{\overline{\mathit u}}}$ $+$ ${{\mathit d}}{{\overline{\mathit d}}}$) $+$ ${\mathit {\mathit c}}_{{\mathrm {2}}}({{\mathit s}}{{\overline{\mathit s}}}$)

INSPIRE JSON PDGID:

${{\mathit b}_{{{1}}}{(1235)}}$

$I^G(J^{PC})$ = $1^+(1^{+ -})$

${{\mathit b}_{{{1}}}{(1235)}}$ MASS

$1229.5$ $\pm3.2$ MeV (S = 1.6)

${{\mathit b}_{{{1}}}{(1235)}}$ WIDTH

$142$ $\pm9$ MeV (S = 1.2)

${{\mathit b}_{{{1}}}{(1235)}}{\mathit D}{\mathrm -wave}/{\mathit S}{\mathrm -wave}$ AMPLITUDE RATIO IN DECAY OF ${{\mathit b}_{{{1}}}{(1235)}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit \pi}}$

$0.277$ $\pm0.027$ (S = 2.4)

${{\mathit b}_{{{1}}}{(1235)}}{\mathit D}{\mathrm -wave}/{\mathit S}{\mathrm -wave}$ AMPLITUDE PHASE DIFFERENCE IN DECAY OF ${{\mathit b}_{{{1}}}{(1235)}}$ $\rightarrow$ ${{\mathit \omega}}{{\mathit \pi}}$

$10$ $\pm5$ $^\circ{}$

${{\mathit b}_{{{1}}}{(1235)}}$ DECAY MODES

Mode

Fraction ($\Gamma_i$ / $\Gamma$)

Scale Factor/
Conf. Level

P(MeV/c)

${{\mathit \omega}}{{\mathit \pi}}$

${{\mathit \pi}^{\pm}}{{\mathit \gamma}}$

($1.6$ $\pm0.4$) $ \times 10^{-3}$

${{\mathit \eta}}{{\mathit \rho}}$

${{\mathit \pi}^{+}}{{\mathit \pi}^{+}}{{\mathit \pi}^{-}}{{\mathit \pi}^{0}}$

${{\mathit K}^{*}{(892)}^{\pm}}{{\mathit K}^{\mp}}$

${{\mathit K}{\overline{\mathit K}}}$ ${{\mathit \pi}^{0}}$

${{\mathit K}_S^0}$ ${{\mathit K}_L^0}$ ${{\mathit \pi}^{\pm}}$

${{\mathit K}_S^0}$ ${{\mathit K}_S^0}$ ${{\mathit \pi}^{\pm}}$

${{\mathit \phi}}{{\mathit \pi}}$

Except where otherwise noted, content of the 2025 Review of Particle Physics is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) license. The publication of the Review of Particle Physics is supported by US DOE, MEXT (Japan), INFN (Italy) and CERN. Individual collaborators receive support for their PDG activities from their respective institutes or funding agencies. © 2025. See LBNL disclaimers.