arXiv subjects

Chuan-Hung Chen

Publications and source records attributed to Chuan-Hung Chen.

At least 109 records · Page 6Linked to original sources

arXiv2007

Expectations on $B\to (K^_{0}(1430),K^_{2}(1430))ϕ$ decays

As the annihilation contributions play important roles in solving the puzzle of the small longitudinal polarizations in $B\to K^* ϕ$ decays, we examine the similar effects in the decays of $B\to K^*_{0,2}(1430) ϕ$. For the calculations on the annihilated contributions, we adopt that the form factors in $B\to K^{(*)} ϕ$ decays are parameters determined by the observed branching ratios (BRs), polarization fractions (PFs) and relative angles in experiments and we connect the parameters between $B\to K^*_{0(2)} ϕ$ and $B\to K^{(*)}ϕ$ by the ansatz of correlating $\la K^*_n(1430) ϕ| (V-A)_μ|0\ra$ to $\la K^{(*)} ϕ| (V-A)_μ|0\ra$. We find that the BR of $B_d\to K^{*0}_{0}(1430) ϕ$ is $(3.69 \pm 0.47)\times 10^{-6}$. By using the transition form factors of $B\to K^*_2(1430)$ in the light-front quark model (LFQM) and the 2nd version of Isgur-Scora-Grinstein-Wise (ISGW2), we show that BR of $B_d\to K^{*0}_{2}(1430)ϕ$ is a broad allowed value and $(1.70\pm0.80)\times 10^{-6}$, respectively. In terms of the recent BABAR's observations on BRs and PFs in $B_d\to K^{*0}_{2}(1430)ϕ$, the results in the LFQM are found to be more favorable. In addition, due to the annihilation contributions to $B\to K^*_2ϕ$ and $B\to K^*ϕ$ being opposite in sign, we demonstrate that the longitudinal polarization of $B_d\to K^{*0}_2(1430) ϕ$ is always O(1) with or without including the annihilation contributions.

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arXiv2007

Implications of the HyperCP Data on $B$ and $τ$ decays

If the HyperCP three events for the decay of $Σ^+\to pμ^+μ^-$ are explained by a new pseudoscalar (axial-vector) boson $X_{P(A)}$ with a mass of 214.3 MeV, we study the constraints on the couplings between $X_{P(A)}$ and fermions from the experimental data in $K$ and $B$ processes. Some implications of the new particle on flavor changing $B$ and $τ$ decays are given. Explicitly, we show that the decay branching ratios of $B_{s}\toϕX_{P(A)}\to ϕμ^{+}μ^{-}$, $B_{d}\to K_{0}^{*}(1430){P(A)}\to K_{0}^{*}(1430)μ^{+}μ^{-}$ and $τ\toμX_{P(A)}\toμμ^{+}μ^{-}$ can be as large as $2.7 (2.8)\times 10^{-6}$, $7.4 (7.5)\times 10^{-7}$ and $1.7 (0.14)\times 10^{-7}$, respectively.

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arXiv2007

$η^{(\prime)}$ productions in semileptonic B decays

Inspired by the new measurements on $B^{-}\to η^{(\prime)}\ell \barν_{\ell}$ from the BaBar Collaboration, we examine the constraint on the flavor-singlet mechanism, proposed to understand the large branching ratios for $B\to η^{\prime} K$ decays. Based on the mechanism, we study the decays of $\bar B_{d,s}\to η^{(\prime)} \ell^{+} \ell^{-}$ and find that they are sensitive to the flavor-singlet effects. In particular, we show that the decay branching ratios of $\bar B_{d,s}\to η^{\prime} \ell^{+} \ell^{-}$ can be as large as $O(10^{-8})$ and $O(10^{-6})$, respectively.

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arXiv2006

Charged Higgs on $B^{-} \to τ\barν_τ$ and $\bar B\to P(V) \ell \barν_{\ell}$

We study the charged Higgs effects on the decays of $B^{-} \to τ\barν_τ$ and $\bar B\to P(V) \ell \barν_{\ell}$ with $P=π^{+},D^{+}$ and $V=ρ^{+},D^{*+}$. We concentrate on the minimal supersymmetric standard model with nonholomorphic terms at a large $\tanβ$. To extract new physics contributions, we define several physical quantities related to the decay rate and angular distributions to reduce uncertainties from the QCD as well as the CKM elements. With the constraints from the recent measurement on the decay branching ratio of $B^{-} \to τ\barν_τ$, we find that the charged Higgs effects could be large and measurable.

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arXiv2006

Lepton flavor violation in $τ$ decays

We study the lepton flavor violation (LFV) in tau decays in the framework of the supersymmetric seesaw mechanism with nonholomorphic terms for the lepton sector at a large $\tanβ$. In particular, we analyze two new decay modes $τ\to \ell f_0(980)$ and $τ\to \ell K^{+} K^{-}$ arising from the scalar boson exchanges contrast to $τ\to \ellη^{(\prime)}$ from the pseudoscalar ones. We find that the decay branching ratios of the two new modes could be not only as large as the current upper limits of $O(10^{-7})$, but also larger than those of $τ\to \ell η^{(\prime)}$. Experimental searches for the two modes are important for the LFV induced by the scalar-mediated mechanism. In addition, we show that the decay branching ratios of $τ\to \ell μ^{+} μ^{-}$ are related to those of $τ\to \ell η$ and $τ\to \ell f_0(980)$.

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arXiv2006

Production of doubly charmed baryons in B decays

We study the doubly charmed baryonic B decays $B\to Ξ_{c} Λ_{c}$ and $B\to Λ^{+}_{c} Λ^{-}_{c} K$, recently observed by BELLE. We find that the unexpected large branching ratios (BRs) could be ascribed to the final state interactions (FSIs), which are dictated by $B\to DD^{+}_{s}\to Ξ_{c} Λ^{+}_{c}$ and $B\to \bar D^0 D^{0} K\to Λ^{+}_{c} Λ^{-}_{c} K$. By utilizing the same mechanism, we predict that the BRs for $B^{+}\to \bar Ξ^{0}_{c} Σ^{+}_{c}$ and $B^{+} \to Σ^{\mp}_{c} Λ^{\pm}_{c} K^{+}$ decays could be as large as $BR(B^{+}\to \barΞ^{0}_{c} Λ^{+}_{c})$ and $10^{-4}$, respectively. In addition, extending the FSIs to the processes associated with the creation of the $s\bar s$ pair, $BR(B^{+}\to \bar Ω_{c} Ξ^{+}_{c})$ at percent level is achievable.

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arXiv2006

Nonuniversal $Z^{\prime}$ couplings in B decays

We study the impacts of nonuniversal $Z^{\prime}$ model, providing flavor changing neutral current at tree level, on the branching ratios (BRs), CP asymmetries (CPAs) and polarization fractions of B decays. We find that for satisfying the current data, the new left- and right-handed couplings have to be included at the same time. The new introduced effective interactions not only could effectively explain the puzzle of small longitudinal polarization in $B\to K^* ϕ$ decays, but also provide a solution to the small CPA of $B^{\pm}\to π^{0} K^{\pm}$. We also find that the favorable CPA of $B^{\pm}\to π^{0} K^{\pm}$ is opposite in sign to the standard model; meanwhile, the CPA of $B_{d}\to π^{0}K$ has to be smaller than -10%. In addition, by using the values of parameters which are constrained by $B\to πK$, we find that the favorable ranges of BRs, CPAs, longitudinal polarizations, and perpendicular transverse polarizations for $(B^{\pm}\to ρ^{\pm} K^{*}, B_{d}\to ρ^{\mp} K^{*\pm})$ are $(17.1\pm 3.9, 10.0\pm2.0)\times 10^{-6}$, $(3\pm 5, 21\pm 7)%$, $(0.66\pm 0.10, 0.44\pm 0.08)$ and $(0.14\pm 0.10, 0.25\pm 0.09)$, respectively.

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arXiv2006

Probe the effects of split SUSY in rare B decays

We study the decays of $B\to K^{(*)} \ell^{+} \ell^{-}$ in split supersymmetry with R-parity violation. We find that the decay branching ratio of $B\to Kτ^+τ^-$ in the new physics model due to the scalar interactions can be $1.8\times 10^{-6}$ which is about one order of magnitude larger that in the standard model, whereas those of $B\to K\ell^+\ell^-$ ($\ell=e$ and $μ$) and the $K^*$ modes are insensitive to the new physics. On the other hand, the forward-backward asymmetries of $B\to K τ^{+} τ^{-}$ and $Kμ^{+}μ^{-}$, vanishing in the standard model, can be over 10 and 1%, respectively. In addition, we show that the new interactions will significantly change the forward-backward asymmetry in $B\to K^* τ^{+} τ^{-}$.

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arXiv2006

Polarizations of two vector mesons in B decays

Inspired by the small longitudinal polarizations (LPs) of $B\to K^* ϕ$ decays observed by BELLE and BABAR, we revise the theoretical uncertainties of perturbative QCD approach for determining hard scales of B decays, we find that the LPs of $B\to K^* ϕ$ could approach to 60% while the branching ratios (BRs) could be around $9\times 10^{-6}$. In addition, we also study the BRs and polarization fractions of $B\to ρ(ω) ρ(ω)$ and $B\to ρ(ω) K^*$ decays. For those tree dominant and color-allowed processes in $B\to ρ(ω) ρ(ω)$ decays, we get that the BRs of $(ρ^{+} ρ^{-}, ρ^{0} ρ^{+}, ωρ^{+})$ are $(23.06, 11.99, 14.78)\times 10^{-6}$ while their LPs are close to unity. Interestingly, due to significant tree contributions, we find that the BR(LP) of $ρ^{-} K^{*+}$ could be around $10.13 \times 10^{-6}(60%)$; and due to the tree and electroweak penguin, the BR(LP) of $ωK^{*+}$ could be around $5.67 \times 10^{-6}(61%)$.

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arXiv2005

Factorization and polarization in two charmed-meson B decays

We provide a comprehensive test of factorization in the heavy-heavy $B$ decays motivated by the recent experimental data from BELLE and BABAR collaborations. The penguin effects are not negligible in the B decays with two pseudoscalar mesons. The direct CP asymmetries are found to be a few percent. We give estimates on the weak annihilation contributions by analogy to the observed annihilation-dominated processes. The $N_c$ insensitivity of branching ratios indicates that the soft final state interactions are not dominant. We also study the polarizations in $B\to D^*D_{(s)}^*$ decays. The power law shows that the transverse perpendicular polarization fraction is small. The effects of the heavy quark symmetry breaking caused by the perturbative QCD and power corrections on the transverse polarization are also investigated.

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arXiv2005

Productions of $K^*_0(1430)$ and $K_{1}$ in B decays

We study the productions of p-wave mesons $K^*_{0}(1430)$, $K_{1}(1270)$ and $K_{1}(1400)$ in B decays. By the generalized factorization approach, we find that the branching ratios of $B\to K^*_{0}(1430) ϕ$ are similar to those of $B\to K ϕ$ while the branching ratios of $B\to K_{1}(1270) ϕ$ and $B\to K_{1}(1400) ϕ$ are $O(10^{-5})$ and $O(10^{-6})$, respectively. In terms of the observation of $B\to K_{1}(1270) γ$ by BELLE, we can remove the sign ambiguity in the mixing angle for physical states $K_1(1270)$ and $K_{1}(1400)$. In addition, we analyze annihilation contributions in the decays $B\to K_1 ϕ$ and we conclude that they could be neglected.

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arXiv2005

Dilepton decays and oscillation of $B_{s}$ in split supersymmetry with R-parity violation

We study $B$ physics phenomenology in the scenario of split supersymmetry without R-parity. By assuming the constraints of bilinear (trilinear) R-parity violating couplings, which are introduced to solve the problem of the atmospheric (solar) neutrino mass, we show that the decay branching ratios of $B_{s}\to \ell^{+} \ell^{-}$ and the mixing of $B_s-\bar{B}_s$ can be large. Explicitly, we find that $B(B_s\toμ^+μ^-)=O(10^{-7})$ and $Δm_{B_s}=O(10^{-9}) GeV$, which should be observed at future hadron colliders.

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arXiv2005

Looking for forward backward asymmetries in $B\to K μ^+ μ^-$ and $K^+\to π^+μ^+μ^-$

We investigate the possibility of scalar interaction affecting the forward backward asymmetry in the decay mode $B\to K μ^+ μ^-$. Using the scalar contribution and advocating Cheng-Sher type ansatz we obtain sizable forward backward asymmetry. Furthermore, we study the effect of the scalar interaction in $K^+ \to π^+ μ^+ μ^-$. It is pointed out that non-zero forward backward asymmetry in $B\to K l^+ l^-$, if found in future B-factories, may indicate the new physics in the scalar sector.

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arXiv2005

Nonfactorizable contributions to $B$ meson decays into charmonia

We analyze the $B\to (J/ψ, χ_{c0},χ_{c1},η_c)K^{(*)}$ decays, which have small or even vanishing branching ratios in naive factorization assumption (FA). We calculate nonfactorizable corrections to FA in the perturbative QCD approach based on $k_T$ factorization theorem. The charmonium distribution amplitudes are inferred from the non-relativistic heavy quarkonium wave functions. It is found that the nonfactorizable contributions enhance the branching ratios and generate the relative phases among helicity amplitudes of the above modes. Most of the observed branching ratios, polarization fractions, and relative phases, except those of $B\toη_c K$, are explained. Our predictions for the $B\to (χ_{c0},χ_{c1},η_c)K^*$ decays can be compared with future data.

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arXiv2005

Scalar interactions and the polarizations of $B\to ϕK^*$

We try to understand the polarization puzzle in $B\to ϕK^*$ decays with a simple Higgs model associated with flavor changing neutral current at tree level. The new interactions can effectively reduce the longitudinal polarization $|A_0|^2$. In particular, we find that if the couplings of $b$-quark in different chiralities to Higgs are the same, the transverse polarization $|A_\perp|^2$ can receive the largest contribution and its value can be as large as 30%. On the other hand, with opposite sign in the couplings, the other transverse polarization $|A_{\parallel}|^2$ is enhanced.

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arXiv2005

Lepton angular asymmetries in semileptonic charmful B decays

We study the lepton angular distributions in $B\to D^{(*)} \ell ν_{\ell}$ decays. The lepton angular asymmetries in the decays with the general effective interactions are examined. We demonstrate that the asymmetries are sensitive to new physics with a right-handed quark current.

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arXiv2005

Novel two-loop SUSY effects on CP asymmetry in $B\to ϕK_{s}$

Inspired by the exotic measurements on the CP asymmetry in $B\to ϕK_{s}$, we study a new diagram in supersymmetric models which can make the difference $\sin2ϕ^{eff}_{1}(J/ΨK_{s})-\sin2ϕ^{eff}_{1}(ϕK_{s})$ to be $20-50%$ after satisfying the constraint from $b\to s γ$. We also find that the direct CP asymmetry of $b\to s γ$ could be $\sim 10%$ and testable at $B$ factories.

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arXiv2004

Vector-pseudoscalar two-meson distribution amplitudes in three-body $B$ meson decays

We study three-body nonleptonic decays $B\to VVP$ by introducing two-meson distribution amplitudes for the vector-pseudoscalar pair, such that the analysis is simplified into the one for two-body decays. The twist-2 and twist-3 $ϕK$ two-meson distribution amplitudes, associated with longitudinally and transversely polarized $ϕ$ mesons, are constrained by the experimental data of the $τ\toϕKν$ and $B\toϕKγ$ branching ratios. We then predict the $B\toϕKγ$ and $B\toϕϕK$ decay spectra in the $ϕK$ invariant mass. Since the resonant contribution in the $ϕK$ channel is negligible, the above decay spectra provide a clean test for the application of two-meson distribution amplitudes to three-body $B$ meson decays.

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