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Ai-Jun Ma

Publications and source records attributed to Ai-Jun Ma.

22 records · Page 2Linked to original sources
arXiv2017

$S$-wave resonance contributions to the $B^0_{(s)}\to η_c{(2S)}π^+π^-$ in the perturbative QCD factorization approach

By employing the perturbative QCD (PQCD) factorization approach, we study the quasi-two-body $B^0_{(s)}\to η_c{(2S)}π^+π^-$ decays, where the pion pair comes from the $S$-wave resonance $f_0(X)$. The Breit$-$Wigner formula for the $f_0(500)$ and $f_0(1500)$ resonances, and the Flatté model for the $f_0(980)$ resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes. As a comparison, Bugg's model is also used for the wide $f_0(500)$ in this work. For decay rates, we found the following PQCD predictions: (a) $ {\cal B}(B^0_s\to η_c(2S) f_0(X)[π^+π^-]_s )=\left ( 2.67^{+1.78}_{-1.08} \right )\times 10^{-5}$ when the contributions from $f_0(980)$ and $f_0(1500)$ are all taken into account; (b) ${\cal B}(B^0\to η_c(2S) f_0(500)[π^+π^-]_s)= \left ( 1.40 ^{+0.92}_{-0.56} \right ) \times 10^{-6}$ in the Breit-Wigner model and $ \left ( 1.53 ^{+0.97}_{-0.61} \right ) \times 10^{-6}$ in the Bugg's model.

hep-ph↗
arXiv2017

Quasi-two-body decays $B_{(s)}\to Pρ\to Pππ$ in perturbative QCD approach

In this work, we calculate the $CP$-averaged branching ratios and the direct $CP$-violating asymmetries of the quasi-two-body decays $B_{(s)} \to P (ρ\to) ππ$ by employing the perturbative QCD (PQCD) approach (here $P$ stands for a light pseudoscalar meson $π, K, η$ or $η^{\prime}$). The vector current time-like form factor $F_π$, which contains the final state interactions between the pion pair in the resonant region associated with the $P$-wave states $ρ(770)$ along with the two-pion distribution amplitudes, are employed to describe the interactions between the $ρ$ and the pion pair under the hypothesis of the conserved vector current. We found that (a) the PQCD predictions for the branching ratios and the direct $CP$-violating asymmetries for most considered $B_{(s)} \to P (ρ\to) ππ$ decays agree with currently available data within errors; (b) for ${\cal B}(B \to π^0 ρ^0 \to π^0(π^+ π^-)$, the PQCD prediction is much smaller than the measured one; and (c) for $B^+ \to π^+(ρ^0\to)π^+ π^-$ decay mode, we found a negative $CP$ asymmetry $(-27.5^{+3.0}_{-3.7})\%$, which agrees with other theoretical predictions but different in sign from those as reported by BaBar and LHCb Collaboration.

hep-ph↗
arXiv2016

The $S$-wave resonance contributions to the three-body decays $B^0_{(s)}\to η_c f_0(X)\to η_cπ^+π^-$ in perturbative QCD approach

In this paper, we study the three-body decays $B^0/B^0_s \to η_c f_0(X)\to η_c π^+π^-$ by employing the perturbative QCD (PQCD) factorization approach. We evaluate the $S$-wave resonance contributions by using the two-pion distribution amplitude $Φ_{ππ}^{\rm S}$. The Breit-Wigner formula for the $f_0(500)$, $f_0(1500)$, and $f_0(1790)$ resonances and the Flatté model for the $f_0(980)$ resonance are adopted to parameterize the time-like scalar form factors $F_{s}(ω^2)$. We also use the D.~V.~Bugg model to parameterize the $f_0(500)$ and compare the relevant theoretical predictions from different models. We found the following results: (a) the PQCD predictions for the branching ratios are ${\cal B}(B^0\to η_c f_0(500)[π^+π^-])= \left ( 1.53 ^{+0.76}_{-0.35} \right ) \times 10^{-6}$ for Breit-Wigner model and ${\cal B}(B^0\to η_c f_0(500)[π^+π^-])= \left ( 2.31 ^{+0.96}_{-0.48} \right ) \times 10^{-6}$ for D.~V.~Bugg model; (b) $ {\cal B}(B_s\to η_c f_0(X)[π^+π^-] ) =\left ( 5.02^{+1.49}_{-1.08} \right )\times 10^{-5}$ when the contributions from $f_0(X)=(f_0(980),f_0(1500),f_0(1790))$ are all taken into account; and (c) The considered decays could be measured at the ongoing LHCb experiment, consequently, the formalism of two-hadron distribution amplitudes could also be tested by such experiments.

hep-ph↗
arXiv2014

$\bar{B}^0_s \to (π^0 η^{(*)}, η^{(*)}η^{(*)})$ decays and the effects of next-to-leading order contributions in the perturbative QCD approach

In this paper, we calculate the branching ratios and CP violating asymmetries of the five $\bar{B}^0_s \to (π^0η^{(*)},η^{(*)}η^{(*)})$ decays, by employing the perturbative QCD (pQCD) factorization approach and with the inclusion of all currently known next-to-leading order (NLO) contributions. We find that (a) the NLO contributions can provide about 100% enhancements to the LO pQCD predictions for the decay rates of $\bar{B}_s^0 \to ηη^\prime$ and $η^\prime η^\prime$ decays, but result in small changes to $Br(\bar{B}_s \to π^0 η^{(*)})$ and $Br(\bar{B}_s \to ηη)$; (b) the newly known NLO twist-2 and twist-3 contributions to the relevant form factors can provide about 10% enhancements to the decay rates of the considered decays; (c) for $\bar{B}_s \to π^0 η^{(*)}$ decays, their direct CP-violating asymmetries $\cala_f^{dir}$ could be enhanced significantly by the inclusion of the NLO contributions; and (d) the pQCD predictions for $Br(\bar{B}_s \to ηη^{(*)})$ and $Br(\bar{B}_s \to η^\prime η^\prime)$ can be as large as $4\times 10^{-5}$, which may be measurable at LHCb or the forthcoming super-B experiments.

hep-ph↗