6533b861fe1ef96bd12c4d31

RESEARCH PRODUCT

Spectroscopy, lifetime and decay modes of the Tbb− tetraquark

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Abstract We present the first full-fledged study of the flavor-exotic isoscalar T b b − ≡ b b u ¯ d ¯ tetraquark with spin and parity J P = 1 + . We report accurate solutions of the four-body problem in a quark model, characterizing the structure of the state as a function of the ratio M Q / m q of the heavy to light quark masses. For such a standard constituent model, T b b − lies approximately 150 MeV below the strong decay threshold B − B ⁎ ¯ 0 and 105 MeV below the electromagnetic decay threshold B − B ¯ 0 γ . We evaluate the lifetime of T b b − , identifying the promising decay modes where the tetraquark might be looked for in future experiments. Its total decay width is Γ ≈ 87 × 10 − 15 GeV and therefore its lifetime τ≈ 7.6 ps. The promising final states are B ⁎ − D ⁎ + l − ν ¯ l and B ⁎ ¯ 0 D ⁎ 0 l − ν ¯ l among the semileptonic decays, and B ⁎ − D ⁎ + D s ⁎ − , B ⁎ ¯ 0 D ⁎ 0 D s ⁎ − , and B ⁎ − D ⁎ + ρ − among the nonleptonic ones. The semileptonic decay to the isoscalar J P = 0 + tetraquark T b c 0 is also relevant but it is not found to be dominant. There is a broad consensus about the existence of this tetraquark, and its detection will validate our understanding of the low-energy realizations of Quantum Chromodynamics (QCD) in the multiquark sector.