arXiv subjects

Chuan-Hung Chen

Publications and source records attributed to Chuan-Hung Chen.

At least 127 records · Page 7Linked to original sources

arXiv2004

Are there significant scalar resonances in $B^{-}\to D^{(*)0} K^{-} {K}^{0}$ decays?

We study the indication of large different branching ratios between $B^{-}\to D^{(*)0} K^{-} {K}^{0}$ and $\bar{B}_{d}\to D^{(*)+} K^{-} {K}^{0}$ observed by Belle. Interestingly, the same situation is not found in the decays $B\to D^{(*)} K^{-} {K}^{*0}$. If there exist no intermediate resonances in the decays $B^{-}\to D^{(*)0} K^{-} {K}^{0}$, a puzzle will be arisen. We find that the color-suppressed processes $B^{-}\to D^{(*)0}a^{-}_{0}(1450)$ with $a^{-}_{0}(1450)\to K^{-} {K}^{0}$ could be one of the candidates to enhance the BRs of $B^{-}\to D^{(*)0} K^{-} {K}^{0}$. Our conjecture can be examined by the Dalitz plot technique and the analysis of angular dependence on $K^{-} {K}^{0}$ state at $B$ factories.

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arXiv2003

Search of $D^{*}_{sJ}$ mesons in $B$ meson decays

We propose that the search of the $B\to D^{*}_{sJ}M$ decays, $M=D$, $π$ and $K$, can discriminate the different theoretical postulations for the nature of the recently observed $D^{*}_{sJ}$ mesons. The ratio of the branching ratios $B(B\to D^{*}_{sJ}M)/B(B\to D^{(*)}_{s}M)\approx 1$ (0.1) supports that the $D^{*}_{sJ}$ mesons are quark-antiquark (multi-quark) bound states. The Belle measurement of the $B\to D^{*}_{sJ}D$ branching ratios seems to indicate an unconventional picture.

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arXiv2003

The difficulty in the decay constants and spectra of $D^{*}_{sJ}$

We examine the compatibility in predicted masses and the decay constants of $D^{*}_{sJ}$ mesons in terms of two-quark contents. We find that the results of a specific model, which is governed by heavy quark limit, will encounter a challenge to fit both spectra and decay constants simultaneously.

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arXiv2003

Impact of CP phases on a light sbottom and gluino sector

We study a scenario in which light bottom squarks and light gluinos with masses in the range $2-5.5$ GeV and 12-16 GeV, respectively, can coexist in the MSSM, without being in conflict with flavor-conserving low-energy observables. We find that in such a scenario, the anomalous magnetic moment of a muon could be as large as $10^{-9}$, if the theory conserves CP. However, if the theory violates CP, we conclude that not both, the gluino and bottom squark, can be light at the same time, after the neutron electric dipole moment constraint on Weinberg's 3-gluon operator has been taken into account.

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arXiv2003

Study of $B\to D^{**} π$ decays

We investigate the production of the novel $P$-wave mesons $D^{*}_{0}$ and $D^{\prime}_{1} (D_{1})$, identified as $J^{P}=0^+$ and $1^+$, in heavy $B$ meson decays, respectively. With the heavy quark limit, we give our modelling wave functions for the scalar meson $D^{*}_{0}$. Based on the assumptions of color transparency and factorization theorem, we estimate the branching ratios of $B\to D^{*}_{0} π$ decays in terms of the obtained wave functions. Some remarks on $D^{(\prime)}_{1}$ productions are also presented.

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arXiv2003

Three-body nonleptonic B decays in perturbative QCD

We develop perturbative QCD formalism for three-body nonleptonic $B$ meson decays. Leading contributions are identified by defining power counting rules for various topologies of amplitudes. The analysis is simplified into the one for two-body decays by introducing two-meson distribution amplitudes. This formalism predicts both nonresonant and resonant contributions, and can be generalized to baryonic decays.

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arXiv2003

Evidence for two-quark content of $f_{0}(980)$ in exclusive $b\to c$ decays

Inspired by a large decay branching ratio (BR) of $B^{+}\to f_{0}(980)K^{+}$ measured by Belle recently, we propose that a significant evidence of the component of $n\bar{n}=(u\bar{u}+d\bar{d})/\sqrt{2}$ in $f_{0}(980)$ could be demonstrated in exclusive $b\to c$ decays by the observation of $f_{0}(980)$ in the final states $\bar{B}\to D^{0(*)} π^{+} π^{-}(KK)$ and $\bar{B}\to J/Ψπ^{+} π^{-}(KK)$. We predict the BRs of $\bar{B}\to D^{0(*)} (J/Ψ) f_{0}(980)$ to be ${\cal {O}}(10^{-4})$ (${\cal {O}}(10^{-5})$) while the unknown wave functions of $D^{(*)0}$ ($J/Ψ$) are chosen to fit the observed decays of $\bar{B}\to D^{(*)0} π^{0} (J/ΨK^{0(*)})$.

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arXiv2003

What can we learn from $B^{+}\to D^{()-}_{s} K^{+} π^{+}$, $B_{d}\to D_{s}^{()-} K^{0} π^{+}$ and $B_{d}\to D_{s}^{()-} K^{+}$ decays?

We study the nonresonant three-body decays of $B^{+}\to D^{(*)-}_{s} K^{+} π^{+}$ and $B_{d}\to D_{s}^{(*)-} K^{0} π^{+}$. We find that these decays can provide the information on the time-like form factors of $D^{(*)}_{s} K$. We also explicitly investigate $B_{d}\to D_{s}^{(*)-} K^{*+}$ decays by discriminating the nonresonant contributions with the unknown $D^{(*)}_{s}$ wave functions being fixed by the measured mode of $B_{d}\to D_{s}^{-} K^{+}$.

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arXiv2003

Forward-backward Asymmetry in $K^+\toπ^+ \ell^+\ell^-$

We study the forward-backward asymmetries in the decays of $K^+\toπ^+\ell^+ \ell^-$ ($\ell=e$ and $μ$) in the presence of scalar or tensor terms. We find that with the scalar (tensor) type interaction the asymmetry can be up to ${\cal O}(10^{-3})$ (${\cal O}(10^{-1}))$ and arbitrary large for the electron and muon modes, respectively, without conflict with the experimental data. We also discuss the cases in the minimal supersymmetric standard model where the scalar terms can be induced. In particular we show that the asymmetry in $K^+\toπ^+μ^+μ^-$ can be as large as ${\cal O}(10^{-3})$ in the large $\tanβ$ limit, which can be tested in future experiments such as CKM at Fermilab.

hep-ph↗

arXiv2002

$B\to f_{0}(980) K^{(*)}$ decays and final state interactions

We study the exclusive decays of $B\to f_{0}(980) K^{(*)}$ in the framework of the perturbative QCD by identifying the $f_{0}(980)$ as the composition of $\bar{s} s$ and $\bar{n}n=(\bar{u}u+\bar{d}d)/\sqrt{2}$. We find that the influence of the $\bar{n} n$ content on the predicted branching ratios is crucial. We discuss the possible rescattering and gluonium states which could enhance the branching ratios of considered decays. We point out that the CP asymmetry in $B\to f_{0}(980) K_{S,L}$ could be a new explorer of $\sin2ϕ_{1}$.

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arXiv2002

T violation in $Λ_b\toΛ\ell^+\ell^-$ decays

We examine the T-odd transverse lepton and $Λ$ polarizations in the baryonic decays of $Λ_b\toΛl^+l^- (l=e ,μ)$ to study the T violating effects. We show that the lepton polarizations are suppressed but the $Λ$ ones can be as large as 50% in CP violating theories beyond the standard model such as the SUSY models, which can be tested in various future hadron colliders.

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arXiv2002

Probing New Physics in $B\to K^{(*)} \ell^+\ell^-$ decays

We study the exclusive decays of $B\to K^{(*)}\ell^+ \ell^-$ by the results in the perturbative QCD with the heavy quark effective theory and lattice calculations. We obtain the form factors for the $B\to K^{(*)}$ transitions in the whole allowed region. Our predictions on the branching ratios of $B\to K \ell^{+} \ell^{-}$, $B\to K^{*} e^{+}e^{-}$, and $B\to K^{*} μ^{+} μ^{-}$ are $0.53\pm 0.05 ^{+0.10}_{-0.07}$, $1.68\pm 0.17^{+0.14}_{-0.09}$, and $1.34\pm 0.13 ^{+0.11}_{-0.06}\times 10^{-6}$, where the errors are from the quark mixing elements and hadronic effects, respectively. We also find that our definitions of the T-odd observable and the up-down asymmetry of the $K$ meson in $B\to K^*\ell^+ \ell^-\to Kπ\ell^+ \ell^-$ can be used to probe new physics.

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arXiv2002

Perturbative QCD analysis of $B \to ϕK^* $ decays

We study the first observed charmless $B\to VV$ modes, the $B\toϕK^*$ decays, in perturbative QCD formalism. The obtained branching ratios $B(B\toϕK^*)\sim 15 \times 10^{-6}$ are larger than $\sim 9\times 10^{-6}$ from QCD factorization. The comparison of the predicted magnitudes and phases of the different helicity amplitudes, and branching ratios with experimental data can test the power counting rules, the evaluation of annihilation contributions, and the mechanism of dynamical penguin enhancement in perturbative QCD, respectively.

hep-ph↗

arXiv2002

Long distance contributions in $B\toK^\ell^+\ell^-$ decays with polarized $K^$

We use momentum correlations as physical observables in $B\to K^{*}l^{+}l^{-}$ decays with $K^{*}$ polarized to study the long distance contributions. We show that these observables are sensitive to the scenarios of the long distance parametrizations. We find that the T-odd observable is directly related to the nonfactorizable effect in the standard model.

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arXiv2002

Rare kaon decays in SUSY with non-universal A terms

We study the rare kaon decays in the framework of general SUSY models. Unlike the results in the literature, we find the contributions from the gluino exchange to the branching ratio of $K^+\to π^+ ν\barν$ can reach the central value ($\sim 1.5 \times 10^{-10}$) of the new E787 data while the predicted value of standard model is less than $10^{-10}$. We also find that the same effects also enhance the decays of $K_{L}\to π^0 ν\barν$, $K_L\toπ^0e^{+} e^{-}$ and $K_L\toμ^+ μ^-$.

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arXiv2002

Implication of scalar-pseudoscalar mixing on $ε'/ε$ in SUSY models

We study the effects of scalar-pseudoscalar mixing induced from quantum loop on $ε'/ε$ in SUSY models with $\tanβ\sim m_{t}/m_{b}$. We find that even the non-universal soft ${\cal A}^{d}$ term and Yukawa matrix, $Y^{d}$, are hermitian, the predicted value of $|ε'/ε|$ can be consistent with the measured results of NA48 and KTeV. And also the EDMs are compatible with experimental bounds.

hep-ph↗

arXiv2002

Analysis of $B\to K^* \ell^+ \ell^-$ decays at large recoil

We study the exclusive decays of $B\to K^{*}\ell^+ \ell^-$ within the framework of the perturbative QCD (PQCD). We obtain the form factors for the $B\to K^{*}$ transition in the large recoil region, where the PQCD for heavy $B$ meson decays is reliable. We find that our results for the form factors at $q^2=0$ are consistent with those from most of the other QCD models in the literature. Via the decay chain of $B\to K^* (Kπ) \ell^+ \ell^-$, we obtain many physical observables related to the different helicity combinations of $B\to K^* \ell^+ \ell^-$. In particular, we point out that the T violating effect suppressed in the standard model can be up to $O(10%)$ in some CP violating models with new physics.

hep-ph↗

arXiv2002

T violation in $B\to K^* \ell^+ \ell^-$ from SUSY

We propose to use T-odd momentum correlations as physical observables to study T violation in $B\to K^{*}l^{+}l^{-} (l=e,μ)$ decays. We show that these observables are zero in the standard model but sizable at the level of 10% in the supersymmetric model. These large T violating effects are measurable at the B-factories in KEK and SLAC and future hadron colliders. We also point out that the T violating effects are insensitive to nonperturbative QCD contributions.

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