分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： We present a perturbative QCD factorization formula for substructures of an energetic Higgs jet, taking the energy profile resulting from the H→bb¯ decay as an example. The formula is written as a convolution of a hard Higgs decay kernel with two b-quark jet functions and a soft function that links the colors of the two b quarks. We derive an analytical expression to approximate the energy profile within a boosted Higgs jet, which significantly differs from those of ordinary QCD jets. This formalism also extends to boosted W and Z bosons in their hadronic decay modes, allowing an easy and efficient discrimination of fat jets produced from different processes.
分类： 物理学 >> 核物理学 提交时间： 2016-09-13
摘要： We study S-wave resonance contributions to the B0(s)→J/ψπ+π− and Bs→π+π−ℓ+ℓ− decays in the perturbative QCD (PQCD) framework by introducing two-hadron distribution amplitudes for final states. The Breit-Wigner formula for the f0(500), f0(1500) and f0(1790) resonances and the Flatt\'e model for the f0(980)resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes, which include both resonant and nonresonant contributions. The resultant branching fraction and differential branching fraction in the pion-pair invariant mass for each resonance channel are consistent with experimental data. The determined S-wave two-pion distribution amplitudes, containing the information of both resonant and nonresonant rescattering phases, can be employed to predict direct CP asymmetries of other three-body hadronic B meson decays in various localized regions of two-pion phase space.
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