Considering the $B$ mesonic distribution amplitude $ϕ_{B2}$, we reinvestigated the $B$ ${\to}$ $PP$ (where $P$ $=$ $π$ and $K$) decays with the perturbative QCD (pQCD) approach based on the $k_{T}$ factorization for three scenarios. It is found that the contributions of $ϕ_{B2}$ to formfactors $F_{0}^{B{\to}P}(0)$ and branching ratios are comparable with those from the NLO corrections. The $B$ ${\to}$ $Kπ$ decays could be well explained by considering the $ϕ_{B2}$. Hence, when the nonleptonic $B$ decays are studied withe the pQCD approach, the $ϕ_{B2}$ should be taken into account seriously.
Considering the $B$ mesonic wave function $ϕ_{B2}$, the $B$ ${\to}$ $PV$ decays are restudied at the leading order for three scenarios using the perturbative QCD approach within the standard model, where $P$ $=$ $π$ and $K$, and $V$ denotes the ground $SU(3)$ vector mesons. It is found that contributions from $ϕ_{B2}$ can enhance most branching ratios, and are helpful for improving the overall consistency of branching ratios between the updated calculations and available data, although there are still several discrepancies between the experimental and theoretical results.
The complete calculation of the lowest order short-distance contributions to the $B_{s}\toγγ$ decay in the SM are presented. The amplitude and branching ratio are calculated.
The decay amplitudes for anti-B0 -> Ds+ Ds- and anti-Bs0 -> D+ D- have no factorizable contributions. We suggest that dominant contributions to the decay amplitudes arise from two chiral loop contributions and one soft gluon emission contribution. Then we determine branching ratios BR(anti-B0 -> Ds+ Ds-) ~ 7E-5 and BR(anti-Bs0 -> D+ D-) ~ 1E-3.
Order alpha^2 contribution to the orthopositronium decay rate due to one-photon virtual annihilation is found to be delta Gamma = (alpha/pi)^2 (pi^2 ln(alpha) - 0.8622(9))Gamma_LO.
The light quarks inside $B$ mesons are usually treated as spectators and do not affect the decay rates which are assumed to be purely due to b quark decays. In this paper we calculate the non-spectator contributions to inclusive charmless $B$ decays due to the spectator effects. We find that the non-spectator contributions to the branching ratio for $\bar B^0$ are small ($<2\times 10^{-4}$), but the contributions to $ΔS = 0$ and $ΔS = -1$, $B^-$ decay branching ratios can be as large as $-7.5\times 10^{-4}$ and $2\times 10^{-3}$, respectively. These contributions may play an important role in …
We show that although there is no infrared divergence in exclusive P-wave quarkonium decays, the colour octet contribution is no less important than in the inclusive decay. Results from more proper calculations with only colour singlet contribution are not sufficient to account for the measured partial decay widths and so the next higher Fock state must be included. Using the $\c_J$ decay into $N\bar N$ as an example, a scheme is devised to yield estimates of the decay widths using both contributions, the results are comparable with experimental measurements.
The rare decay b -> s s bar{d} is studied in the supersymmetric standard model by considering the contribution from the chargino box diagrams. We find that this contribution amounts to 10^{-9} in the branching ratio.
Exclusive nonleptonic decays of bottom baryons to charm baryons and pseudoscalar light mesons are analyzed within a relativistic three-quark model. We include factorizing as well as nonfactorizing contributions to the decay amplitudes. The total contribution of the nonfactorizing diagrams amount up to 30% of the factorizing contributions in amplitude. We present detailed predictions for rates and asymmetry parameters.
The order alpha_s^2 contribution to the inclusive semileptonic decay width of a b quark Γ(b -> X_u e \barν_e) is calculated analytically for zero mass u quarks.
We point out that a new contribution to B decays to three pions is relevant in explaining recent data from the CLEO and BABAR collaborations, in particular the results on quasi-two-body decays via a rho meson. We also discuss the relevance of these contribution to the measurement of CP violations.
We investigate nonfactorizable contributions to two-body hadronic decays of the charmed mesons to a pseudoscalar meson and a vector meson in Cabibbo-favored mode. Employing SU(3)-flavor symmetry for the nonfactorizable matrix elements, we obtain branching ratios of the decays in consistent agreement with experiment.
In this talk I comment on the contributions of all three types of particles (scalars, fermions and bosons) to the three--photon Z decay within the standard model (SM) and its extensions to the 2 Higgs doublet model (2 HDM) and the minimal supersymmetric extension of the standard model (MSSM). I also comment briefly on the charginos contribution to this decay rate. Finally I comment on the fermions and scalars contributions to the three--gluon Z decay.
Encouraged by recent discovery of $Ξ_{cc}^{++}$ baryon, we investigate two body non-leptonic weak decays of doubly charmed, $Ξ_{cc}$, baryons. We calculate the branching ratios for CKM-favored and suppressed modes in factorization and pole model approach. We give the first estimates of nonfactorizable W-exchange contributions using pole model. We find that W-exchange contributions to $Ξ_{cc}$ decays being sizable can not be ignored.
The importance of the color octet component in P-wave charmonia is discussed in the context of exclusive decay processes. It is vital to include this contribution already at the level of the two-body decay channels. The ππand proton-antiproton channels are used as examples.
We consider the gluon dipole penguin operator contributions to $ε'/ε$ and CP violation in hyperon decays. It has been proposed by Bertolini et al. that the contribution to $ε'/ε$ may be significant. We show that there is a cancellation in the leading order contribution and this contribution is actually suppressed by a factor of order O($m_π^2, m_K^2)/Λ^2$. We find that the same operator also contributes to CP violation in hyperon decays where it is not suppressed. The gluon dipole penguin operator can enhance CP violation in hyperon decays by as much as 25\%.
We use the new symmetries in the heavy quark limit to calculate the exclusive B-decays $B \rightarrow K^i ψ$ where $K^i$ are higher resonances of K-meson. We then estimate the long distance contributions to $B \rightarrow K^i γ$ decays via $ψ- γ$ conversion. The results point to around $30 \%$ uncertainty in the top quark mass determined by measurements of rare B-decays $B \rightarrow K^i γ$.
The nonleptonic decays of $Ξ_c^0$ and $Λ_c^+$ that are dominated by $W$-exchange are studied. In particular, we anlayse the decay modes $Ξ_c^0 \rightarrow Ξ^{*-} π^+, Σ^{*+}K^-, Ω^-K^+$ and $Λ_c^+\rightarrow Σ^0π^+, Ξ^0 K^+$, $Ξ^0_c\rightarrow Σ^+K^-$.
In this work we study the radiative leptonic decays of $B^-$, $D^-$ and $D_s^-\to γl \barν$, including both the short-distance and long-distance contributions. The short-distance contribution is calculated by using the relativistic quark model, where the bound state wave function we used is that obtained in the relativistic potential model. The long-distance contribution is estimated by using vector meson dominance model.
We study a new $K\rightarrowππ$ decay channel with gluons in intermediate state which is normally neglected within the factorization framework. Both short-distance and long-distance parts of the amplitude are calculated. The chiral Lagrangian approach is used for obtaining the long-distance contribution. The nonperturbative contribution gives an additional enhancement to $K\rightarrowππ$ decay amplitude with $ΔI=1/2$. A sizable violation of factorization in the $p^4$ order of chiral perturbation theory is found.
In this article, we calculate the nonfactorizable soft contributions in the $B \to η_c K, χ_{c0} K$ decays with the light cone QCD sum rules approach. Our results show that the nonfactorizable corrections from the soft gluon exchanges in the decay $B \to η_c K$ are of $(15-30)%$ and should not be neglected. As for the decay $B \to χ_{c0} K$, the factorizable contributions are zero and the nonfactorizable contributions from the soft hadronic matrix elements are too small to accommodate the experimental data.
We present first calculations of new long-distance contributions to $B_s \to γγ$ decay due to intermediate $D_s$ and $D_s^*$ meson states. The relevant $γ$ vertices are estimated using charge couplings and transition moment couplings. Within our uncertainties, we find that these long-distance contributions could be comparable to the known short-distance contributions. Since they have different Cabibbo-Kobayashi-Maskawa matrix-element factors, there may be an interesting possibility of observing CP violation in this decay.
Two-body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using the naive factorization while the latter is calculated by using a hard pion (or kaon) approximation in the infinite momentum frame. It is seen that the non-factorizable contribution is small but not negligible in color favored decays while it is more important in color mismatched decays.
Two body decays of B mesons are studied by decomposing their amplitude into a sum of factorizable and non-factorizable ones. The former is estimated by using a naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states and is calculated by using a hard pion (or kaon) technique in the infinite momentum frame. Possible roles of the non-factorizable contributions are discussed by comparing the result with experiments.
We investigate the contributions of neutral Higgs bosons to nonleptonic transition $b \to q \bar{s} s, q=d, s$ under the supersymmetric context. Their effects to decay width and CP violation in corresponding exclusive decays are explored. The anomalous dimension matrices of the operators which have to be incorporated to include the contributions of neutral Higgs bosons are given. We find that when tan$β$ is large (say, 50) and neutral Higgs bosons are not too heavy (say, 100 GeV), contributions of neutral Higgs penguin can dominate electroweak penguin contributions, and for some processes, the…
We analyse the long-distance contribution to $B\to X_s\ell^+\ell^-$ differential decay rate when the momentum dependence of $ψ$ and $ψ'$-$γ$ conversion strength is taken into account. The results indicate that the resonance to nonresonance interference in the dilepton invariant mass distribution is substantially reduced.
The long distance contribution to $K^+ \to π^+ ν{\bar ν} $ is calculated using chiral perturbation theory. The leading contribution comes from $O(p^4)$ tree terms. The branching ratio of the $O(p^4)$ long distance contribution is found to be of order $10_{-3}$ smaller than the short distance contributions.
We discuss the theory prediction of epsilon_K and the rare K -> pi nu nu-bar decays and review the structure and current status of higher-order contributions to these flavour changing processes in the standard model in some detail. This includes the next-to-next-to-leading order QCD calculation to the charm quark contribution to K+ -> pi+ nu nu-bar and to the charm-top quark contribution to epsilon_K. Electroweak corrections to the rare kaon decays are also discussed.
We argue that the factorizable $c\bar c$ long- and short-distance contributions to the $B\to K^*γ$ amplitude vanish, separately, if defined in a gauge-invariant way. Therefore, the $c\bar c$ states contribute to the radiative decay only through the non-factorizable soft-gluon exchanges.
It is argued that colour octet contribution in exclusive charmonium decays is very important even though the same infrared divergence found in P-wave colour singlet inclusive decay is absent. This comes about because of the suppression at the level of the wavefunction of P-wave quarkonia. Using the modified hard scattering approach of Brodsky, Lepage, Botts, Li and Sterman, we use charmonium decay into baryon-antibaryon pair as an example and show that the colour singlet contribution alone is clearly insufficient to explain the experimental decay widths.
We examine the radiative omega pi0etagamma and rho pi0etagamma decays in a phenomenological framework. We consider the VMD mechanism, chiral loops, intermediate a0-meson and rho−omega mixing. We find the values of the decay width coming from the different amplitudes and compare the results with other studies. We observe that a0-meson intermediate state is very important in the case of the rho pi0etagamma decay and small in the other case for which VMD contribution is dominant.
Pade-approximant methods are used to estimate the three-loop perturbative contributions to the inclusive semileptonic $b \to u$ decay rate. These improved estimates of the decay rate reduce the theoretical uncertainty in the extraction of the CKM matrix element $|V_{ub}|$ from the measured inclusive semileptonic branching ratio.
We present a phenomenological analysis of higher Fack state contributions to the $χ_{cJ}$ decays by using the recent BES experimental data. It is found that the higher Fock state $\mid (c\bar{c})_{8}g>$ makes an important contributions to the inclusive and exclusive processes with respect to that from the valence Fock state $\mid c\bar{c} >$ of the $χ_{cJ}$ and some constraints of these contributions are obtained for the $χ_{c0}$ and $χ_{c2}$ states in order to fit the experimental data.
In this paper the leading twist contribution to $χ_{c0,2}\toωω$ decays in the color singlet approximation is considered. It is shown, that the predictions for $\Br(χ_0\toωω)$ is in a good agreement with the experimental data, while $\Br(χ_{c2}\toωω)$ differs from the experiment significantly.
We present estimates of the charming penguin contribution to B => K pi, pi pi,K eta, K eta' decays due to intermediate charmed meson states. We find that this contribution is indeed significant for B => K pi decays, and its inclusion, together with the tree and penguin terms, produces large branching ratios in agreement with data, though the analysis is affected by large theoretical uncertainties. On the other hand, for B => pi pi, K eta, K eta' decays, the effect of the charming penguin contribution is more modest. We also compute CP asymmetries for B => K pi, pi pi decays and we obtain rathe…
We have made an ab initio three-loop quark model calculation of the $W$-exchange contribution to the nonleptonic two-body decays of the doubly charmed baryons $Ξ_{cc}^{++}$ and $Ω_{cc}^{+}$. The $W$-exchange contributions appear in addition to the factorizable tree graph contributions and are not suppressed in general. We make use of the covariant confined quark model previously developed by us to calculate the tree graph as well as the $W$-exchange contribution. We calculate helicity amplitudes and quantitatively compare the tree graph and $W$-exchange contributions. Finally, we compare the c…
We discuss how contributions to the order ${\cal O} (m α^8)$ orthopositronium decay rate can be separated into two categories, one due to relativistic momenta and calculable in terms of QED scattering amplitudes, the other due to low momenta and calculable in the simpler framework of a low-energy effective theory (NRQED). We report new results for all low-momentum contributions, and give a formula relating the remaining contributions to conventional (on-shell) QED scattering amplitudes.
The singly charged Higgs boson contribution to $0\nu2β$ is neglected on grounds of couplings involving small masses and small nuclear matrix elements. We reconsider such contributions, but now in the light of QCD corrections and renormalization group evolution. It is found that the charged Higgs contribution is generically as large as (and at times significantly larger than) the other contributions and there can be large cancellations between contributions coming from different sources. This observation will have an important impact on the phenomenology.
We investigate nonfactorizable contributions to charm meson decays in $ D \rightarrow \bar K π$/ $ \bar K ρ$ /$ \bar K ^{*} π$ / $ \bar K a_{1}$ / $ \bar K ^{*} ρ$ modes. Obtaining the contributions from spectator-quark diagrams for $ N_{c}$ = 3, we determine nonfactorizable isospin 1/2 and 3/2 amplitudes required to explain the data for these modes. We observe that ratio of these amplitudes seem to follow a universal value.
We study instanton effects on $B \rightarrow X_sγ$ decay using the heavy quark effective field theory and the operator product expansion. In the dilute gas approximation the effect is negligibly small. This is in contrast to the result of the instanton effect in inclusive semileptonic $b\rightarrow u$ decay but similar to the inclusive hadronic $τ$ decay. We discuss the similarities and differences of the $B \rightarrow X_sγ$ decay compared to inclusive hadronic $τ$ decay and semileptonic $B$ decay.
I report on a systematic analysis of the MSSM parameter space to obtain the best SUSY solution to the $R_b$ anomaly within the constraint of top quark decay. Phenomenological implications for top decay and direct stop production at the Tevatron collider are discussed.
B meson semi-leptonic rare decays are sensitive to new physics beyond standard model. We study the $B^{-}\to π^{-}μ^{+}μ^{-}$ process and investigate the Majorana neutrino contribution to its decay width. The constraints on the Majorana neutrino mass and mixing parameter are obtained from this decay channel with the latest LHCb data. Utilizing the best fit for the parameters, we study the lepton number violating decay $B^{-}\to π^{+}μ^{-}μ^{-}$, and find its branching ratio is about $6.4\times10^{-10}$, which is consistent with the LHCb data reported recently.
The decay of the Higgs boson into two photons is examined in a model-independent way within the effective Lagrangian approach. Contribution of one-loop diagrams including SU(2) x U(1) invariant dimension-six bosonic operators is evaluated explicitly. The calculation is intended to fill a gap that exists in the current literature of the subject.
Within the standard model, CP-violating asymmetries A(Λ^0_-) and A(Ξ^-_-) have been estimated in short-distance calculations to occur at the level of a few times 10^{-5}. We show here that in this model the dispersive contribution tends to give asymmetries of similar size.
We present a systematic analysis at the leading log order of the influence of combination of bilinear and trilinear R-parity violating couplings on the decay b-->s gamma. Such contributions have never been explored in the context of this decay. We show that influence of charged-slepton-Higgs mixing mediated loops can dominate the SM and MSSM contributions and hence can provide strong bounds on the combination of bilinear-trilinear R-parity violating couplings. Such contributions are also enhanced by large tan beta. With substantially extended basis of operators (28 operators), we provide illus…
We calculate all the experimentally relevant branching ratios of the Higgs bosons of the Minimal Supersymmetric Standard Model, paying particular attention to the contributions from below--threshold decays. We show that in some cases these can significantly change the pattern of branching ratios calculated without taking off--shell effects into account
With the potential for the improvements of measurement precision,the refinement of theoretical calculation on hadronic $B$ weak decays is necessary. In this paper, we study the contributions of $B$ mesonic distribution amplitude $Φ_{B2}$ within the QCD factorization approach, and find that $Φ_{B2}$ contributes to only the nonfactorizable annihilation amplitudes for the $B$ ${\to}$ $PP$ decays ($P$ denotes the ground $SU(3)$ pseudoscalar mesons). Although small, the $Φ_{B2}$ contributions might be helpful for improving the performance of the QCD factorization approach, especially for the pure a…
We study charm D - meson decays to two pseudoscalar mesons in Cabibbo favored mode employing SU(3)-flavor for the nonfactorizable matrix elements. Using $D\rightarrow \bar K π$ and $D_{s} \rightarrow \bar K K$ to fix the reduced matrix elements, we obtain a consistent fit for $ η$ and $ η'$ emitting decays of $D$ and $ D_{s}$ mesons.
Using the next-to-leading order low energy effective Hamiltonian for $|ΔB|=1$, $ΔC=ΔU=0$ transitions, the contributions of electroweak penguin operators in $ B^-(\overline {B_d^0})\rightarrow PP$ and $PV$ decays are estimated in the standard model. We find that, for some channels, the electroweak penguin effects can enhance or reduce the QCD penguin and/or tree level contributions by at least $30\%$, and can even play dominant role.
We point out that the decay mode D^0 -> K^0 \bar{K^0} has no factorizable contribution. In the chiral perturbation language, treating D^0 as heavy, the O(p) contribution is zero. We calculate the nonfactorizable chiral loop contributions of order O(p^3). Then, we use a heavy-light type chiral quark model to calculate nonfactorizable tree level terms, also of order O(p^3), proportional to the gluon condensate. We find that both the chiral loops and the gluon condensate contributions are of the same order of magnitude as the experimental amplitude.
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.
We present a detailed calculation of the contributions of charginos, scalar quarks, and charged Higgs boson to the $K^+\rightarrow π^+ν\overlineν$\ and $K^0_L\rightarrowμ^+μ^-$\ decays. We include mixings: that of charginos and that of the scalar partners of the left and right handed top quark. We find that the box contribution to the amplitudes is much smaller than the penguin contribution, which can be $\sim$10\% of the Standard Model contribution, even for relatively large SUSY masses. The charged Higgs contribution can be as large as 25\% of the SM contribution in the first decay and as mu…
New physics effects may yield a detectable mass difference in the D0-D0bar system, Delta m_D. Here we show that this has an important impact on some B --> D decays. The effect involves a new source of CP violation, which arises from the interference between the phases in the B --> D decays and those in the D0-D0bar system. This interference is naturally large. New physics may well manifest itself through Delta m_D contributions to these B decays.
The role of power corrections and higher Fock-state contributions to exclusive charmonium decays will be discussed. It will be argued that the J/Psi (Psi') decays into baryon-antibaryon pairs are dominated by the valence Fock-state contributions. P-wave charmonium decays, on the other hand, receive strong contributions from the c cbar g Fock states since the valence Fock-state contributions are suppressed in these reactions. Numerical results for J/Psi (Psi') --> B Bbar decay widths will be also presented and compared to data.
We study supersymmetric contributions to correlation coefficients that characterize the spectral shape and angular distribution for polarized muon- and beta-decays. In the minimal supersymmetric Standard Model (MSSM), one-loop box graphs containing superpartners can give rise to non-(V-A)x(V-A) four fermion operators in the presence of left-right or flavor mixing between sfermions. We analyze the present phenomenological constraints on such mixing and determine the range of allowed contributions to the weak decay correlation coefficients. We discuss the prospective implications for future muon…
Possible contributions of the bilepton to the neutrinoless double beta $(ββ)_{0ν}$ decay in the economical 3-3-1 model are discussed. We show that the $(ββ)_{0ν}$ decay in this model is due to both sources--Majorana $<M_ν>_{L}$ and Dirac $<M_ν>_{D}$ neutrino masses. If the mixing angle between charged gauge bosons, the standard model $W$ and bilepton $Y$, is in range of the ratio of neutrino masses $<M_ν>_{L}/< M_ν>_{D}$, both the Majorana and Dirac masses simultaneously give contributions dominant to the decay. As results, constraints on the bilepton mass are also given.
The neutrinoless double beta ($\znbb$) decay is analyzed within the Minimal Supersymmetric Standard Model with explicit R-parity violation (\rp MSSM). We have found new supersymmetric contributions to this process and give the complete set of relevant Feynman diagrams. Operators describing $0^+ \longrightarrow 0^+$ nuclear transitions induced by the supersymmetric interactions of the \rp MSSM are derived. These operators can be used for calculating the $\znbb$ decay rate applying any specific nuclear model wave functions.
We compute the decoupling function of the MSbar renormalized fine-structure constant up to four-loop order in perturbative QCD. The results are used in order to determine the related top-quark contributions to the Higgs-boson decay into two photons in the heavy top-quark mass limit to order alpha_s^4.
We calculate the transition form factor for the 'B_c -> B_u^* gamma' decay taking into account only the short distance contribution, in framework of QCD sum rules method. We observe that the transition form factor predicted by the QCD sum rules method is approximately two times larger compared to the result predicted by the Isgur, Scora, Grinstein and Wise model.
