Observation of a Fourth Upsilon State in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow><mml:mrow><mml:msup><mml:mrow><mml:mi>e</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Annihilations

A fourth state in the upsilon energy region has been seen in ${e}^{+}{e}^{\ensuremath{-}}$ collisions at the Cornell Electron Storage Ring. A resonance is observed with a mass 1112\ifmmode\pm\else\textpm\fi{}5 MeV above the lowest upsilon state. The 9.6-MeV rms width is greater than the 4.6-MeV energy resolution of the ${e}^{+}{e}^{\ensuremath{-}}$ beams. The observed characteristics of the new state make it a likely candidate for the $4^{3}S$ state of the $b\overline{b}$ system, lying above the threshold for the production of $B$ mesons.