Predicted Branching Ratios Research Articles

Two-body non-leptonic heavy-to-heavy decays at NNLO in QCD factorization

We evaluate in the framework of QCD factorization the two-loop vertex corrections to the decays $\bar{B}_{(s)}\to D_{(s)}^{(\ast)+} \, L^-$ and $\Lambda_b \to \Lambda_c^+ \, L^-$, where $L$ is a light meson from the set $\{\pi,\rho,K^{(\ast)},a_1\}$. These decays are paradigms of the QCD factorization approach since only the colour-allowed tree amplitude contributes at leading power. Hence they are sensitive to the size of power corrections once their leading-power perturbative expansion is under control. Here we compute the two-loop ${\cal O}(\alpha_s^2)$ correction to the leading-power hard scattering kernels, and give the results for the convoluted kernels almost completely analytically. Our newly computed contribution amounts to a positive shift of the magnitude of the tree amplitude by $\sim 2$\%. We then perform an extensive phenomenological analysis to NNLO in QCD factorization, using the most recent values for non-perturbative input parameters. Given the fact that the NNLO perturbative correction and updated values for form factors increase the theory prediction for branching ratios, while experimental central values have at the same time decreased, we reanalyze the role and potential size of power corrections by means of appropriately chosen ratios of decay channels.

Novel nonperturbative approach for radiativeB¯0(B¯s0)→J/ψγdecays

Radiative $\bar{B}^0(\bar{B}^0_s)\rightarrow J/\psi \gamma$ decays provide an interesting case to test our understanding of (non)perturbative QCD and eventually to probe physics beyond the standard model. Recently, the LHCb Collaboration has reported an upper bound, updating the results of the BABAR Collaboration. Previous theoretical predictions based on QCD factorization or perturbative QCD have shown large variations due to different treatment of nonfactorizable contributions and meson-photon transitions. In this paper, we report on a novel approach to estimate the decay rates, which is based on a recently proposed model for $B$ decays and the vector meson dominance hypothesis, widely tested in the relevant energy regions. The predicted branching ratios are $\mathrm{Br}[\bar{B}^0\rightarrow J/\psi\gamma]=\left(3.50\pm0.34^{+1.12}_{-0.63}\right)\times10^{-8}$ and $\mathrm{Br}[\bar{B}^0_s\rightarrow J/\psi\gamma]=\left(7.20\pm0.68^{+2.31}_{-1.30}\right)\times10^{-7}$. The first uncertainty is systematic and the second is statistical, originating from the experimental $\bar{B}^0_s\rightarrow J/\psi \phi$ branching ratio.

Testing QCD factorization with phase determinations inB→Kπ,Kρ, andK*πdecays

The success of QCD factorization(QCDF) in predicting branching ratios for charmless $B$ decays to light pseudoscalar and vector mesons and the small CP asymmetries measured at $BABAR$, Belle and LHCb show that the phase in these decays, as predicted by QCDF, are not large. For a precise test of QCDF one needs to extract from the measured decay rates, the phase of the decay amplitude which appears in the interference terms between the tree and penguin contribution. Since the tree amplitude is known at the leading order in $\Lambda_{\rm QCD}/m_{b}$ and is consistent with the measured tree-dominated decay rates, the QCDF value for the tree amplitude can be used with the measured decay rates to obtain the phases in $B\to K\pi$,$K\rho$, and $ K^{*}\pi$ decay rates. This is similar to the extraction of the final-state interaction phases in the interference term between $p\bar{p}\to J/\Psi\to e^{+}e^{-}$ and $p\bar{p}\to e^{+}e^{-} $ and in $J/\Psi\to 0^{-}0^{-}$ done previously. In this paper, we present a determination of the phase between the $I=3/2$ tree and $I=1/2$ penguin amplitudes in $B\to K\pi$,$K\rho$ , and $ K^{*}\pi$ decays using the measured decay rates and the QCDF $I=3/2$ tree amplitude obtained from the $I=2$ $B^{+}\to \pi^{+}\pi^{0},\rho^{0}\pi^{+}, \rho^{+}\pi^{0 tree-dominated decays and compare the result with the phase given by QCDF. It is remarkable that the phase extracted from experiments differs only slightly from the QCDF values. This shows that there is no large final-state interaction strong phase in $B\to K\pi$,$K\rho$, and $ K^{*}\pi$ decays.

CharmlessBc→PP,PVDecays in the QCD Factorization Approach

The charmlessBc→PP,PVdecays (wherePandVdenote the light pseudoscalar and vector mesons, resp.) can occur only via the weak annihilation diagrams within the Standard Model. In this paper, we study these kinds of decays in the framework of QCD factorization, by adopting two different schemes: scheme I is similar to the method usually adopted in the QCD factorization approach, while scheme II is based on the infrared behavior of gluon propagator and running coupling. For comparison, in our calculation, we adopt three kinds of wave functions forBcmeson. The branching ratios based on the two schemes are given. It is found that (a) the predicted branching ratios in scheme I are, however, quite small and almost impossible to be measured at the LHCb experiment and (b) in scheme II, by assigning a dynamical gluon mass to the gluon propagator, we can avoid enhancements of the contribution from soft endpoint region. The strength of annihilation contributions predicted in scheme II is enhanced compared to that obtained in scheme I.

Investigations on the charmless decays of Y(4260)**Supported by National Natural Science Foundation of China (11275113,11205164)

Apart from the charmful decay channels of Y(4260), the charmless decay channels of Y(4260) also provide us a good platform to study the nature and the decay mechanism of Y(4260). In this paper, we propose to probe the structure of Y(4260) through the charmless decays Y(4260)→VP via intermediate meson loops, where V and P stand for light vector and pseudoscalar mesons, respectively. Under the molecule ansatz of Y(4260), the predicted total branching ratio BRVP for all Y(4260)→VP processes are about (0.34+0.32−0.23)% to (0.75+0.72−0.52)% with the cutoff parameter α = 2−3. Numerical results show that the intermediate meson loops may be a possible transition mechanism in the Y(4260)→VP decays. These predicted branching ratios are the same order to that of Y(4260)→Z+c(3900)π−, which may be an evidence of D1D molecule and can be examined by the forthcoming BESIII data in the near future.

KL -> 0 Formula decay correlating with K in high-scale SUSY

We have studied the contribution of high-scale SUSY to the |$K_L \to \pi ^0 \nu {\bar {\nu }}$| and |$K^+ \to \pi ^+ \nu {\bar {\nu }}$| processes by correlating with the CP-violating parameter |$\epsilon _K$|⁠. Taking account of the recent LHC results for Higgs discovery and SUSY searches, we consider high-scale SUSY at the |$10$|–|$50$|TeV scale in the framework of non-minimal squark (slepton) flavor mixing. The Z penguin mediated chargino dominates the SUSY contribution for these decays. At the |$10$|TeV SUSY scale, the chargino contribution can enhance the branching ratio of |$K_L \to \pi ^0 \nu {\bar {\nu }}$| by eight times compared with SM predictions, whereas the predicted branching ratio |${\textit {BR}}(K^+ \to \pi ^+ \nu {\bar {\nu }})$| increases by up to three times that of the SM. The gluino box diagram dominates the SUSY contribution of |$\epsilon _K$| up to |$30{\%}$|⁠. If down-squark mixing is neglected compared with up-squark mixing, the Z penguin mediated chargino dominates both SUSY contributions of |${\textit {BR}}(K_L \to \pi ^0 \nu {\bar {\nu }})$| and |$\epsilon _K$|⁠. Then, a correlation between them is found, but the chargino contribution to |$\epsilon _K$| is at most |$3{\%}$|⁠. Even if the SUSY scale is |$50$|TeV, the chargino process still enhances the branching ratio of |$K_L \to \pi ^0 \nu {\bar {\nu }}$| from the SM prediction by a factor of two, and |$\epsilon _K$| is deviated from the SM prediction by |$\mathcal {O}(10{\%})$|⁠. We also discuss the chargino contribution to the |$K_L \to \pi ^0 e^+e^-$| process.

Combined Crossed Molecular Beam and Ab Initio Investigation of the Reaction of Boron Monoxide (BO; X2Σ+) with 1,3-Butadiene (CH2CHCHCH2; X1Ag) and Its Deuterated Counterparts

The reactions of the boron monoxide ((11)BO; X(2)Σ(+)) radical with 1,3-butadiene (CH2CHCHCH2; X(1)Ag) and its partially deuterated counterparts, 1,3-butadiene-d2 (CH2CDCDCH2; X(1)Ag) and 1,3-butadiene-d4 (CD2CHCHCD2; X(1)Ag), were investigated under single collision conditions exploiting a crossed molecular beams machine. The experimental data were combined with the state-of-the-art ab initio electronic structure calculations and statistical RRKM calculations to investigate the underlying chemical reaction dynamics and reaction mechanisms computationally. Our investigations revealed that the reaction followed indirect scattering dynamics through the formation of (11)BOC4H6 doublet radical intermediates via the barrierless addition of the (11)BO radical to the terminal carbon atom (C1/C4) and/or the central carbon atom (C2/C3) of 1,3-butadiene. The resulting long-lived (11)BOC4H6 intermediate(s) underwent isomerization and/or unimolecular decomposition involving eventually at least two distinct atomic hydrogen loss pathways to 1,3-butadienyl-1-oxoboranes (CH2CHCHCH(11)BO) and 1,3-butadienyl-2-oxoboranes (CH2C ((11)BO)CHCH2) in overall exoergic reactions via tight exit transition states. Utilizing partially deuterated 1,3-butadiene-d2 and -d4, we revealed that the hydrogen loss from the methylene moiety (CH2) dominated with 70 ± 10% compared to an atomic hydrogen loss from the methylidyne group (CH) of only 30 ± 10%; these data agree nicely with the theoretically predicted branching ratio of 80% versus 19%.

An experimental and theoretical study of the gas phase kinetics of atomic chlorine reactions with CH3NH2, (CH3)2NH, and (CH3)3N.

The rate coefficients for the reactions of Cl((2)PJ) with methylamine (R1), dimethylamine (R2) and trimethylamine (R3) have been measured using the laser flash photolysis - resonance fluorescence technique as a function of temperature (274-435 K) and pressure (25-400 Torr N2). The experimental data are well-represented by the following temperature- and pressure-independent rate coefficients (10(10) × k/cm(3) molecule(-1) s(-1)): kR1 = 2.90 ± 0.44, kR2 = 3.89 ± 0.58, kR3 = 3.68 ± 0.55; the uncertainties are estimates of accuracy at the 95% confidence level. Potential energy surfaces (PES) for the reactions have been characterized at the MP2/cc-pVTZ level and improved single point energies of stationary points obtained in CCSD(T)-F12a calculations. The PES for all reactions are characterized by the formation of pre and post reaction complexes and submerged barriers. Rate coefficients for the reactions were calculated as a function of temperature and pressure using a master equation model based on the coupled cluster theory results. The calculated rate coefficients are in good agreement with experiment; the overall rate coefficients are relatively insensitive to variations of the barrier heights within typical chemical accuracy, but the predicted branching ratios vary significantly. The inclusion of tunnelling has no effect.

Atmospheric oxidation mechanism of toluene.

The atmospheric oxidation mechanism of toluene initiated by OH radical addition is investigated by quantum chemistry calculations at M06-2X, G3MP2-RAD, and ROCBS-QB3 levels and by kinetics calculation by using transition state theory and unimolecular reaction theory coupled with master equation (RRKM-ME). The predicted branching ratios are 0.15, 0.59, 0.05, and 0.14 for OH additions to ipso, ortho, meta, and para positions (forming R1-R4 adducts), respectively. The fate of R2, R4, and R1 is investigated in detail. In the atmosphere, R2 reacts with O2 either by irreversible H-abstraction to form o-cresol (36%), or by reversible recombination to R2-1OO-syn and R2-3OO-syn, which subsequently cyclize to bicyclic radical R2-13OO-syn (64%). Similarly, R4 reacts with O2 with branching ratios of 61% for p-cresol and 39% for R4-35OO-syn, while reaction of R1 and O2 leads to R1-26OO-syn. RRKM-ME calculations show that the reactions of R2/R4 with O2 have reached their high-pressure limits at 760 Torr and the formation of R2-16O-3O-s is only important at low pressure, i.e., 5.4% at 100 Torr. The bicyclic radicals (R2-13OO-syn, R4-35OO-syn, and R1-26OO-syn) will recombine with O2 to produce bicyclic alkoxy radicals after reacting with NO. The bicyclic alkoxy radicals would break the ring to form products methylglyoxal/glyoxal (MGLY/GLY) and their corresponding coproducts butenedial/methyl-substituted butenedial as proposed in earlier studies. However, a new reaction pathway is found for the bicyclic alkoxy radicals, leading to products MGLY/GLY and 2,3-epoxybutandial/2-methyl-2,3-epoxybutandial. A new mechanism is proposed for the atmospheric oxidation mechanism of toluene based on current theoretical and previous theoretical and experimental results. The new mechanism predicts much lower yield of GLY and much higher yield of butenedial than other atmospheric models and recent experimental measurements. The new mechanism calls for detection of proposed products 2,3-epoxybutandial and 2-methyl-2,3-epoxybutandial.

Can contributions to Bs → l+l−γ from the magnetic-penguin operator with real photons in the standard model be neglected?

Using the Bs meson wave function extracted from non-leptonic Bs decays, we reevaluate the rare decays Bs → l+l− γ, (l=e, μ) in the Standard Model, including two kinds of contributions from the magnetic-penguin operator with virtual and real photons. We find that contributions to the exclusive decays from the magnetic-penguin operator b → sγ with real photons, which were regarded as negligible in the previous literature, are large and the branching ratios Bs → l+l− γ are enhanced by a factor of almost 2. With the predicted branching ratios of the order of 10−8, it is expected that these radiative dileptonic decays will be detected in LHC-b and B factories in the near future.

Effects of final state interactions in $$B^ + \to D_S^ + \bar K^0$$ decay

We investigate the effects of final state interactions (FSI) contributions in the nonleptonic two body \(B^ + \to D_S^ + \bar K^0\) decay, however the hadronic decay of \(B^ + \to D_S^ + \bar K^0\) is analyzed by using “QCD factorization” (QCDF) method and final state interaction (FSI). First, the \(B^ + \to D_S^ + \bar K^0\) decay is calculated via QCDF method and only the annihilation graphs exist in that method. Hence, the FSI must be seriously considered to solve the \(B^ + \to D_S^ + \bar K^0\) decay and the D0π+(D0*ρ+), D+π0(D+*ρ0) and D+ηc(D+*J/ψ) via the exchange of K+(*), K0(*) and Ds+(*) mesones are chosen for the intermediate states. To estimate the intermediate states amplitudes, the QCDF method is again used. These amplitudes are used in the absorptive part of the diagrams. The experimental branching ratio of \(B^ + \to D_S^ + \bar K^0\) decay is less than 8 × 10−4 and the predicted branching ratio is 0.23 × 10−9 in the absence of FSI effects and it becomes 6.74 × 10−4 when FSI contributions are taken into account.

Bs,d→ℓ+ℓ−in the Standard Model with Reduced Theoretical Uncertainty

We combine our new results for the O(αem) and O(αs2) corrections to Bs,d→ℓ+ℓ-, and present updated branching ratio predictions for these decays in the standard model. Inclusion of the new corrections removes major theoretical uncertainties of perturbative origin that have just begun to dominate over the parametric ones. For the recently observed muonic decay of the Bs meson, our calculation gives B¯(Bs→μ+μ-)=(3.65±0.23)×10-9.

A combined crossed molecular beams and ab initio investigation on the formation of vinylsulfidoboron (C₂H₃¹¹B³²S).

We exploited crossed molecular beams techniques and electronic structure calculations to provide compelling evidence that the vinylsulfidoboron molecule (C2H3(11)B(32)S) - the simplest member of hitherto elusive olefinic organo-sulfidoboron molecules (RBS) - can be formed via the gas phase reaction of boron monosulfide ((11)B(32)S) with ethylene (C2H4) under single collision conditions. The reaction mechanism follows indirect scattering dynamics via a barrierless addition of the boron monosulfide radical to the carbon-carbon double bond of ethylene. The initial reaction complex can either decompose to vinylsulfidoboron (C2H3(11)B(32)S) via the emission of a hydrogen atom from the sp(3) hybridized carbon atom, or isomerize via a 1,2-hydrogen shift prior to a hydrogen loss from the terminal carbon atom to form vinylsulfidoboron. Statistical (RRKM) calculations predict branching ratios of 8% and 92% for both pathways leading to vinylsulfidoboron, respectively. A comparison between the boron monosulfide ((11)B(32)S) plus ethylene and the boron monoxide ((11)BO) plus ethylene systems indicates that both reactions follow similar reaction mechanisms involving addition - elimination and addition - hydrogen migration - elimination pathways. Our experimental findings open up a novel pathway to access the previously poorly-characterized class of organo-sulfidoboron molecules via bimolecular gas phase reactions, which are difficult to form through 'classical' organic synthesis.

First estimates of nonleptonicBc→ATweak decays

We obtain the first estimates of branching ratios for the weak decays of ${B}_{c}$ meson decaying to 2 orbitally excited mesons namely, axial-vector meson ($A$) and tensor meson ($T$) in the final state. We calculate ${B}_{c}\ensuremath{\rightarrow}T$ transition form factors using the Isgur-Scora-Grinstein-Wise II framework and, consequently, predict branching ratios of ${B}_{c}\ensuremath{\rightarrow}AT$ decays in Cabibbo-Kobayashi-Maskawa favored and suppressed modes.

CharmlessBu,d,s→VTdecays in perturbative QCD approach

Motivated by the experimental data, we study charmless $B_{u,d,s}\to VT$ ($V$ and $T$ denote light vector and tensor mesons respectively) decays in the perturbative QCD approach. The predictions of branching ratios, polarization fractions and direct CP violations are given in detail. Specifically, within this approach we have calculated the polarization fractions and the branching ratios of $B\to \phi(K_2^{*-}, \bar K_2^{*0})$ which agree well with the observed experimental data, however the branching ratios of $B\to \omega(K_2^{*-}, \bar K_2^{*0})$ are hard to be explained, where the polarization fractions are well accommodated. The tree dominated channels with a vector meson emitted have longitudinal polarization fraction of 90%, while the penguin dominating ones have subtle polarization fractions. Fortunately, most branching ratios of $B_{u,d}$ decays are of the order $10^{-6}$, which would be straight forward for experimental observations. For the $B_s$ decays the branching ratios can reach the order of $10^{-6}$ in tree dominated decays, while in penguin dominated decays those are of order of $10^{-7}$ which require more experimental data to be observed.

Effects of Final State Interactions in Pure Annihilation Decay of $B^{0}_{s}\rightarrow\pi^{0}\pi^{0}$

We investigate the effects of final state interactions (FSI) contributions in the nonleptonic two body $B^{0}_{s} \rightarrow \pi^{0}\pi^{0}$ decay. The short distance interaction amplitude is calculated by using the annihilation diagrams and a tiny branching ratio is obtained, then the long distance amplitude is considered and calculated within FSI effects. For contributions of FSI, the ρ 0 ρ 0, π + π −(ρ + ρ −), K + K −(K +∗ K −∗) and $K^{0}\bar{K}^{0}(K^{0*}\bar{K}^{0*})$ are produced for intermediate states, in this case the π 0, π −(ρ −), K −(∗) and $\bar{K}^{0(*)}$ mesons are exchanged. The absorptive part of the diagrams is directly calculated and the dispersive part of the rescattering amplitude can be obtained from the absorptive part via the dispersion relation. The imaginary and real parts of the amplitudes are summed over all intermediate states. The predicted branching ratio of $B^{0}_{s} \rightarrow \pi^{0}\pi^{0}$ is 0.69×10−8 in the absence of FSI effects and it becomes 1.86×10−4 when FSI contributions are taken into account, while the experimental result is less than 2.1×10−4.

Higgs potential inS3invariant model for quark/lepton mass and mixing

We analyzed the S_3 invariant Higgs potential with S_3 singlet and doublet Higgs. We obtained a relation (|v_1|/|v_2|)^2=-sin2phi_2/sin2phi_1 from this S_3 invariant Higgs potential, where v_1, v_2 and phi_1, phi_2 are vacuum pectation values and phases of S_3 doublet Higgs, respectively. This relation could be satisfied exactly by the results |v_1|/ |v_2|=0.207, phi_1=-74.9deg and phi_2=0.74deg obtained from the previous our work analyzing the quark/lepton mass and mixing in S_3 invariant Yukawa interaction. Furthermore, the relation v_S ~ v_D=sqrt{|v_1|^2+|v_2|^2}=174GeV is obtained and then the coupling strength of Higgs to top quark g_{H_Stt}=m_t/v_S is altered as by a factor sqrt{2} from the standard value. Introduced the S_3 doublet Higgs, FCNC are produced in tree level. Predicted branching ratios for rare decays mu^- to e^-e^+e^-, K^0_L to mu^+\mu^- etc., induced by the FCNC are sufficiently below the present experimental upper bounds.

η′ →π0γγandη′ →ηγγ: a primer analysis

The electromagnetic rare decays η′ → π0γγ and η′ → π0γγ are analysed for the first time and their predicted branching ratios given. The vector meson exchange dominant contribution is treated using Vector Meson Dominance and the scalar component is estimated by means of the Linear Sigma Model. The agreement between our calculation and the measurement of the related process η → π0γγ is a check of the procedure. Scalar meson effects are seen to be irrelevant for η′ → π0γγ, while a significant scalar contribution due to the σ(500) resonance seems to emerge in the case of η′ → π0γγ. Future measurements coming from KLOE-2, Crystal Ball, WASA, and BES-III will elucidate if any of these processes carry an important scalar contribution or they are simply driven by the exchange of vector mesons.

Branching ratio andCPasymmetry ofBs→K0*(1430)ρ(ω,ϕ)decays in the perturbative QCD approach

In the two-quark model supposition for $K_0^{*}(1430)$, which can be viewed as either the first excited state (scenario I) or the lowest lying state (scenario II), the branching ratios and the direct CP-violating asymmetries for decays $\bar B_s^0\to K^{*0}_0(1430)\phi, K^{*0}_0(1430)\omega, K^{*0}_0(1430)\rho^0, K^{*+}_0(1430)\rho^-$ are studied by employing the perturbative QCD factorization approach. We find the following results: (a) Enhanced by the color allowed tree amplitude with large Wilson coefficients $a_1=C_2+C_1/3$, the branching ratio of $\bar B_s^0\to K^{*+}_0(1430)\rho^-$ is much larger than those of the other three decays and arrives at $(3.4^{+0.8}_{-0.7})\times 10^{-5}$ in scenario I, even $10^{-4}$ order in scenario II, and its direct CP violating asymmetry is the smallest, around 10%, so this channel might be measurable in the current LHC-b experiments, where a large number (about $10^{12}$) of $B$ mesons will be produced per year. This high statistics will make the measurement possible. (b) For the decay modes $\bar B^0_s\to K^{*0}_0(1430)\omega, K^{*0}_0(1430)\rho^0$, their direct CP-violating asymmetries are large, but it might be difficult to measure them, because their branching ratios are small and less than (or near) $10^{-6}$ in both scenarios. For example, in scenario I, these values are ${\cal B}(\bar B_s^0\to K^*_0(1430)\omega)=(8.2^{+1.8}_{-1.7})\times 10^{-7}, {\cal B}(\bar B_s^0\to K^*_0(1430)\rho^0)=(9.9^{+2.1}_{-2.0})\times 10^{-7}, \acp^{dir}(\bar B^0_s\to K^{*0}_0(1430)\omega)=-24.1^{+2.8}_{-2.5}, \acp^{dir}(\bar B^0_s\to K^{*0}_0(1430)\rho^0)=26.6^{+2.5}_{-2.5}.$ (c) For the decay $\bar B^0_s\to K^*_0(1430)\phi$, the predicted branching ratios are also small and a few times $10^{-7}$ in both scenarios; there is no tree contribution at the leading order, so its direct CP-violating asymmetry is naturally zero.

Study a0(980)-f0(980) mixing in charmonium decays

In this proceeding, we propose to directly measure the a00(980)-f0 (980) mixing in J/ψ → ϕ f0(980) → ϕa00 (980) and χc1 → π0a00(980) → π0f0(980) with the upgraded Beijing Electron Positron Collider(BEPCII) with BESIII detector. We show that a narrow peak of about 8 MeV will be produced by the a00(980)-f0 (980) mixing, and the predominant feature makes it standing out from the background contributions. The predicted branching ratios for these two reactions are both expected to be about O(10−6), which is unambiguously accessible with 109 J/ψ and 3 × 108 χc1 at BESIII.