Prospects of discovering stable double-heavy tetraquarks at a Tera-$Z$ factory
Prospects of discovering stable double-heavy tetraquarks at a Tera-$Z$ factory
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Tera-Z 工厂发现稳定双重四夸克的前景
DOI：
10.1016/j.physletb.2018.05.055
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发表时间：
2018
影响因子：
4.4
通讯作者：
Wang Wei
中科院分区：
文献类型：
--
作者：
Ali Ahmed;Parkhomenko Alex;er Ya;Qin Qin;Wang Wei
Motivated by a number of theoretical considerations, predicting the deeply bound double-heavy tetraquarks T [u¯ d¯]{b b}, T [u¯ s¯]{b b} and T [d¯ s¯]{b b}, we explore the potential of their discovery at Tera-Z factories. Using the process Z→ b b¯ b b¯, we calculate, employing the Monte Carlo generators MadGraph5_aMC@ NLO and Pythia6, the phase space configuration in which the bb pair is likely to fragment as a diquark. In a jet-cone, defined by an invariant mass interval m b b< M T [q¯ q¯′]{b b}+ Δ M, the sought-after tetraquarks T [q¯ q¯′]{b b} as well as the double-bottom baryons, Ξ b b 0,−, and Ω b b−, can be produced. Using the heavy quark–diquark symmetry, we estimate B (Z→ T [u¯ d¯]{b b}+ b¯ b¯)=(1.2− 0.3+ 1.0)× 10− 6, and about a half of this for the T [u¯ s¯]{b b} and T [d¯ s¯]{b b}. We also present an estimate of their lifetimes using the heavy quark expansion, yielding τ (T [q¯ q¯′]{b b})≃ 800 fs. Measuring the tetraquark masses would require decays, such as T [u¯ d¯]{b b}−→ B− D− π+, T [u¯ d¯]{b b}−→ J/ψ K‾ 0 B−, T [u¯ d¯]{b b}−→ J/ψ K− B‾ 0, T [u¯ s¯]{b b}−→ Ξ b c 0 Σ−, and T [d¯ s¯]{b b} 0→ Ξ b c 0 Σ¯ 0, with subsequent decay chains in exclusive non-leptonic final states. We estimate a couple of the decay widths and find that the product branching ratios do not exceed 10− 5. Hence, a good fraction of these modes will be required for a discovery of T [q¯ q¯′]{b b} at a Tera-Z factory.
Motivated by a number of theoretical considerations, predicting the deeply bound double-heavy tetraquarks T [u¯ d¯]{b b}, T [u¯ s¯]{b b} and T [d¯ s¯]{b b}, we explore the potential of their discovery at Tera-Z factories. Using the process Z→ b b¯ b b¯, we calculate, employing the Monte Carlo generators MadGraph5_aMC@ NLO and Pythia6, the phase space configuration in which the bb pair is likely to fragment as a diquark. In a jet-cone, defined by an invariant mass interval m b b< M T [q¯ q¯′]{b b}+ Δ M, the sought-after tetraquarks T [q¯ q¯′]{b b} as well as the double-bottom baryons, Ξ b b 0,−, and Ω b b−, can be produced. Using the heavy quark–diquark symmetry, we estimate B (Z→ T [u¯ d¯]{b b}+ b¯ b¯)=(1.2− 0.3+ 1.0)× 10− 6, and about a half of this for the T [u¯ s¯]{b b} and T [d¯ s¯]{b b}. We also present an estimate of their lifetimes using the heavy quark expansion, yielding τ (T [q¯ q¯′]{b b})≃ 800 fs. Measuring the tetraquark masses would require decays, such as T [u¯ d¯]{b b}−→ B− D− π+, T [u¯ d¯]{b b}−→ J/ψ K‾ 0 B−, T [u¯ d¯]{b b}−→ J/ψ K− B‾ 0, T [u¯ s¯]{b b}−→ Ξ b c 0 Σ−, and T [d¯ s¯]{b b} 0→ Ξ b c 0 Σ¯ 0, with subsequent decay chains in exclusive non-leptonic final states. We estimate a couple of the decay widths and find that the product branching ratios do not exceed 10− 5. Hence, a good fraction of these modes will be required for a discovery of T [q¯ q¯′]{b b} at a Tera-Z factory.