Hyperfine splittings in bottomonium
نویسندگان
چکیده
A universal description of the hyperfine splittings (HFS) in bottomonium and the Bq (q 1⁄4 n, s, c) mesons is obtained with a universal strong coupling constant sð Þ 1⁄4 0:310 in a spin-spin potential. Other characteristics are calculated within the field correlator method, taking the freezing value of the strong coupling independent of nf. The HFS MðB Þ MðBÞ 1⁄4 45:5ð1Þ MeV, MðB sÞ MðBsÞ 1⁄4 46:2ð1Þ MeV are obtained in full agreement with experiment both for nf 1⁄4 3 and nf 1⁄4 4. In bottomonium, Mð ð9460ÞÞ Mð bÞ 1⁄4 71:1 MeV for nf 1⁄4 5 agrees with the BABAR data, while a smaller HFS, equal to 63.4(5) MeV, is obtained for nf 1⁄4 4. We predict HFS Mð ð2SÞÞ Mð bð2SÞÞ 1⁄4 36ð1Þ MeV, Mð ð3SÞÞ Mð ð3SÞÞ 1⁄4 28ð1Þ MeV, and the mass difference MðB cÞ MðBcÞ 1⁄4 58ð1Þ MeV, which gives MðB cÞ 1⁄4 6334ð1Þ MeV. If a coupling with open channels is neglected, for higher states the masses MðBcð2S0ÞÞ 1⁄4 6865ð5Þ MeV and MðB cð2SS1ÞÞ 1⁄4 6901ð5Þ MeV are calculated.
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