We consider X(3872) and Y(4140) as the vector tetraquark states of
Xc0≡ccˉuuˉ(ddˉ) and ccˉssˉ, respectively. By
connecting Λb→Xc0Λ to B−→Xc0K−, we predict that
the branching ratios of Λb→Λ(X(3872)0→)J/ψπ+π−
and Λb→Λ(Y(4140)→)J/ψϕ are (5.2±1.8)×10−6 and (4.7±2.6)×10−6, which are accessible to the
experiments at the LHCb, respectively. The measurements of these Λb
modes would be the first experimental evidences for the XYZ states in
baryonic decays.Comment: 7 pages, 1 figure
We study the structure-dependent contributions to the radiative baryonic B
decays of B→BBˉ′γ in the standard model. We show
that the decay branching ratios of Br(B→BBˉ′γ) are
O(10−7), which are larger than the estimated values of O(10−9)
induced from inner bremsstrahlung effects of the corresponding two-body modes.
In particular, we find that Br(B−→Λpˉγ) is around 1×10−6, which is close to the pole model estimation but smaller than
the experimental measurement from BELLE.Comment: 11 pages, 2 figures, Revtex4, new fitting is include
We study the three-body Λb decays of Λb→J/ψpM with
M=K− and π−. The two new states Pc1≡Pc(4380)+ and Pc2≡Pc(4450)+ observed recently as
the resonances in the J/ψp invariant mass spectrum of Λb→J/ψpK− can be identified to consist of five quarks, uudccˉ, being
consistent with the existence of the pentaquark states. We argue that, in the
doubly charmful Λb decays of Λb→J/ψpK− through b→ccˉs, apart from those through the non-resonant Λb→pK− and
resonant Λb→Λ∗→pK− transitions, the third contribution
with the non-factorizable effects is not the dominant part for the resonant
Λb→K−Pc1,c2,Pc1,c2→J/ψp processes,
such that we propose that the Pc1,c2 productions are mainly from
the charmless Λb decays through b→uˉus, in which the ccˉ content in Pc1,c2 arises from the intrinsic charms within the
Λb baryon. We hence predict the observables related to the branching
ratios and the direct CP violating asymmetries to be B(Λb→π−(Pc1,c2→)J/ψp)/B(Λb→K−(Pc1,c2→)J/ψp)=0.8±0.1, ACP(Λb→π−(Pc1,c2→)J/ψp)=(−3.9±0.2)%, and ACP(Λb→K−(Pc1,c2→)J/ψp)=(5.8±0.2)%, which can alleviate the
inconsistency between the theoretical expectations from the three contributions
in the doubly charmful Λb decays and the observed data.Comment: 10 pages, 2 figures, revised version accepted by PL
We examine the nature of the unknown enhancement around 3 GeV observed by the
BABAR collaboration in the mppˉ spectrum of the Bˉ0→ppˉD0 decay. Suspecting that the peak is a resonance, which can be neither
identified as a charmonium state, such as ηc or J/ψ, nor classified
as one of the light-flavor mesons, we conclude that it corresponds to a
glueball fitted as X(3020) with (mX,ΓX)=(3020±8,107±30)MeV, which could be the first glueball state above 3 GeV. This
state also appears in the mppˉ spectrum of the Bˉ0→ppˉD∗0 decay.Comment: 11 pages, 2 figure, title changed, revised version accepted by PL
We extract the Cabibbo-Kobayashi-Maskawa matrix element Vcb from the
exclusive decays of Λb→Λcℓνˉℓ and Λb→ΛcM(c) with M=(π−,K−) and Mc=(D−,Ds−), where the
branching ratios of Λb→ΛM(c) measured with high
precisions have not been used in the previous studies. Explicitly, we find
∣Vcb∣=(44.0±3.5)×10−3, which agrees with the value of
(42.11±0.74)×10−3 from the inclusive B→Xcℓνˉℓ
decays. Furthermore, based on the most recent ratio of ∣Vub∣/∣Vcb∣ from
the exclusive Λb decays, we obtain ∣Vub∣=(4.2±0.4)×10−3, which is close to the value of (4.49±0.24)×10−3 from
the inclusive B→Xuℓνˉℓ decays. We conclude that our
determinations of ∣Vcb∣ and ∣Vub∣ from the exclusive Λb
decays favor the inclusive extractions in the B decays.Comment: 8 pages, i figur
We study the four-body baryonic B→B1Bˉ2M1M2 decays with
B1,2 (M1,2) being charmless baryons (mesons). In accordance with
the recent LHCb observations, each decay is considered to proceed through the
B→M1M2 transition together with the production of a baryon pair. We
obtain that B(B−→Λpˉπ+π−)=(3.7−1.0+1.5)×10−6 and B(Bˉ0→ppˉπ+π−,ppˉπ+K−)=(3.0±0.9,6.6±2.4)×10−6, in agreement with the data. We
also predict B(B−→ΛpˉK+K−)=(3.0−0.9+1.3)×10−6, which is accessible to the LHCb and BELLE experiments.Comment: 11 pages, 3 figure