Pietro Santorelli
We study the effects of final state interactions on the eta(b) => J/psi J/psi decay. In particular, we discuss the effects of the annihilation of eta(b) into two charmed meson and their rescattering into J/psi J/psi. We find that the inclusion of this contribution may enhance the short-distance branching ratio up to about 2 orders of magnitude.
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Estimates of the branching ratios for B_{d,s}->J/psi eta and B_{d,s}->eta l+l- are obtained by SU(3) relation to B_d->J/psi K and B_d->K l+l-, respectively, as functions of the eta mixing parameter, theta_P. Based on these estimates, a discussion of the prospects for HERA-B, CDF-II, and ATLAS on these processes is given. The CP violation in B_{d,s}-> J/psi eta is analyzed in depth and a method to extract the angle gamma of the unitarity triangle is discussed. Finally, a possible method to constrain the Wilson coefficient C_{10A} from measurements on semileptonic B decays such as B_d->J/psi K a…
It has been argued long ago that eta(b) could be observed through the eta(b) => J/psi(=> mu+ mu-) J/psi(=> mu+ mu-) decay chain. Recent calculations indicate that the width of eta(b) into two J/psi is almost three order of magnitude smaller than the one into the D D*. We study the effects of final state interactions due to the D D* intermediate state on the J/psi J/psi final state. We find that the inclusion of this contribution may enhance the short distance branching ratio of about two orders of magnitude.
The Bc --> J/psi pi, etac pi decays are studied with the perturbative QCD approach. It is found that form factors and branching ratios are sensitive to the parameters w, v, f_J/psi and f_etac, where w and v are the parameters of the charmonium wave functions for Coulomb potential and harmonic oscillator potential, respectively, f_J/psi and f_etac are the decay constants of the J/psi and etac mesons, respectively. The large branching ratios and the clear signals of the final states make the Bc --> J/psi pi, etac pi decays to be the prospective channels for measurements at the hadron colliders
We evaluate the form factors describing the semileptonic decays $\bar{B^0}\to J/ψ(η_c) D^+ \ell^- \bar ν_\ell$, within the framework of a QCD relativistic potential model. This decay is complementary to $\bar{B^0}\to J/ψ(η_c) D^+ π^-$ in a phase space region where a pion factors out.We estimate the branching ratio for these semileptonic and nonleptonic channels, finding $\mathcal{BR}(\bar{B^0} \to J/ψ(η_c) D^+ \ell ν_\ell) \simeq 10^{-13}$, $\mathcal{BR}(\bar{B^0} \to J/ψD^+ π^-) = 3.1 \times 10^{-8}$ and $\mathcal{BR}(\bar{B^0} \to η_c D^+ π^-) = 3.5 \times 10^{-8}$.
The inclusive and exclusive B decays into the eta' meson plus others are investigated in a model based on the QCD anomaly. The invariant mass distribution is discussed. The constraint of the effective coupling is obtained from the data of the exclusive decay modes. The branching ratio of J/psi -> eta'eta gamma is predicted to be as large as 5.4*10^{-5}, which can be tested in the forthcoming CLEO-c experiments.
We estimate the quantity |f_eta'^(c)| which is associated with the charm content of eta' meson from the experimentally known ratio R=B(psi ->eta' gamma )/B(psi ->eta_c gamma). It is shown that due to the off-shellness of the c\bar c component of eta', which has been overlooked so far, f_eta'^(c) is further suppressed. Assuming that psi ->eta' gamma decay is dominated by psi ->eta_c transition, we obtain |f_eta'^(c)| = 2.4 MeV which could imply that the (b -> c\bar cs) mechanism does not play a major role in the B -> K eta' decay mode.
Following searches for photinos and very light gravitinos in invisible decays of psi and Upsilon, we discuss new limits on Light Dark Matter and U bosons, from psi and Upsilon decays, as well as rare decays of K+ and invisible decays of pi0, eta and eta' ... . The new limits involving the vector couplings of the U to quarks turn out, not surprisingly, to be much less restrictive than existing ones on axial couplings, from an axionlike behavior of a light U boson, tested in psi --> gamma U, Upsilon --> gamma U and K+ --> pi+ U decays (or as compared to the limit from parity-violation in atomic …
We compute the O(alpha_s^2) correction to the decay rate eta_c --> gamma gamma and discuss its implications for precision quarkonium physics. We study the suitability of the ratio Gamma(J/psi --> e+e-)/Gamma(eta_c --> gamma gamma), in which the non-perturbative or soft effects cancel at O(alpha_s^{0,1}), for extracting fundamental parameters of QCD at low energies. We show that the QCD-based theory of charmonia is not capable of predicting this ratio with any degree of confidence.
The octet-singlet mixing angle $θ_P$ in the pseudoscalar meson nonet is deduced from the rich set of accurate data on $J/ψ$ decays into a vector and a pseudoscalar meson. Corrections due to non-ideal $ω$-$ϕ$ mixing have been included for the first time and turn out to be crucial to find $θ_P = -16.9 \pm 1.7$ degrees, which is appreciably less negative than previous results coming from similar analyses.
It is pointed out that the decay of the recently observed charmonium eta_c^prime resonance, eta_c^prime -> eta_c pi pi is simply related to the well studied decay psi^prime -> J/psi pi pi and can thus be used for absolute normalization of other decay modes of the eta_c^prime. The total rate of the discussed decay should be approximately three to four times the corresponding rate for the psi^prime$ resonance making the channel with charged pions the most probable exclusive decay mode of the eta_c^prime with the branching ratio in the range 5-10 %.
We present an effective field theory based extraction of the eta_c mass and width from a recent measurement by CLEO of the photon line shape in J/Psi -> eta_c gamma decay.
We present a new calculation, in the nonrelativistic QCD (NRQCD) factorization formalism, of the relativistic corrections to the double-charmonium cross section sigma[e+ e- -> J/psi+eta_c] at the energy of the Belle and BABAR experiments. In comparison with previous work, our calculation contains several refinements. These include the use of the improved results for the nonperturbative NRQCD matrix elements, the resummation of a class of relativistic corrections, the use of the vector-meson-dominance method to calculate the fragmentation contribution to the pure QED amplitude, the inclusion of…
We proceed for the first time to the evaluation of the Born cross section for J/psi+eta(c) production, namely via g+g -> J/psi+eta(c)+g, and show that it has a harder P_T spectrum than the J/psi-pair yield at Born level. If one stuck to a comparison at Born level, one would conclude that J/psi+eta(c) production would surpass that of J/psi+J/psi at large P_T. This is nonetheless not the case since J/psi-pair production, as for single J/psi, receives leading-P_T contributions at higher orders in alpha_s. We also present the first evaluation of these leading-P_T next-to-leading order contribution…
The eta(1760) may be significantly produced in J/Psi radiative decay. We deduce from experimental data that its branching ratio to two gluons is bounded, 0.4 +- 0.3 < BR(eta(1760) -> gg) < 0.9 +- 0.3, consistent with gluonic admixture. Moreover, the expectation that there should be an isoscalar analogue of the gluonic (hybrid) meson candidate pi(1800) is argued to reinforce hybrid admixture in eta(1760). Two-gluon coupling of hybrids is estimated in a spectator model to be considerably larger than that of quarkonium. In addition, the two-photon coupling of eta(1760) is estimated to be 1.4 +- 0…
We investigate the origin of the double logarithms of Q^2/m_c^2 that appear in the calculation of the cross section for e+e- -> J/psi + eta_c at next-to-leading order in alpha_s. We find that, diagram-by-diagram, the double logarithms are accounted for by Sudakov double logarithms and endpoint double logarithms. The Sudakov double logarithms cancel in the sum over all diagrams, but the endpoint double logarithms do not. We reinterpret the endpoint double logarithms in terms of a leading region of loop integration in which a spectator fermion line becomes soft. This reinterpretation may simplif…
The eta(1835) is confirmed clearly in new BESIII data for J/Psi -> gamma (eta'-pi-pi); the angular distribution of the photon is consistent with a pseudoscalar. This makes it a candidate for an s-sbar radial excitation of eta' and eta(1440) (or one or both of eta(1405) and eta(1475)). However, a conspicuous feature of the BES III data is the absence of evidence for eta(1440) -> eta'-pi-pi while it is well known that eta(1440) appears in eta-pi-pi. Can these facts be reconciled? There is in fact a simple explanation. The channel eta(1440) -> eta-pi-pi may be explained by the two-step process et…
Next-to-Leading-Order(NLO) QCD corrections to J/jpsi plus eta_c production in e+e- annihilation at sqrt{s}=10.6 GeV is calculated in this paper, and an analytic result is obtained. By choosing proper physical parameters, a K factor (ratio of NLO to LO) of about 2, which is in agreement with the result in Ref.\cite{Zhang:2005ch}, is obtained. Our results show that the Next-Next-to-Leading-Order(NNLO) corrections might be quite large. The plot of the K-factor vs the center-of-mass energy sqrt{s} shows that it is more difficult to obtain a convergent result from the perturbative QCD without resum…
Light quark masses are important fundamental parameters of the Standard Model. The decays psi'-->J/psi pi^0 (eta) were widely used in determining the light quark mass ratio m_u/m_d. However, there is a large discrepancy between the resulting value of m_u/m_d and the one determined from the light pseudoscalar meson masses. Using the technique of non-relativistic effective field theory, we show that intermediate charmed meson loops lead to a sizeable contribution to the decays and hence make the psi'-->J/psi pi^0 (eta) decays not suitable for a precise extraction of the light quark mass ratio.
Motivated by recent interest in soft $J/Ψ$ production in B decays, we investigate ${B}^0 \to J/ΨD^{(\star)}$ and $η_c D^{(\star)}$ decays in perturbative QCD. We find that, within that framework, these decays are calculable since the heavy $c\bar{c}$ pair in the final states is created by a hard gluon. The branching ratios are estimated to be around $10^{-7}\sim 10^{-8}$, too small to be consistent with the data, suggesting that other mechanism(s) contribute to the observed excess of soft $J/Ψ$ in ${B}^0 \to J/Ψ+ X$ decays. The possibility of the production of a hybrid $s{\bar d}g$ meson with …
We show that in the transitions psi' -> h_c π^0 and eta_c' -> chi_{c0} pi^0 the contributions from charmed meson loops are highly suppressed, in contrast to various other charmonium decays. We calculate the width of the psi' -> h_c pi^0, which agrees with the recent BES-III data, and predict the width of the eta_c' -> chi_{c0} pi^0, Γ(eta_c' -> chi_{c0} pi^0) = 1.5\pm0.4 keV. A confirmation of this prediction would also provide additional support for a recent analysis of psi' -> J/psi pi^0 (eta), where loops are claimed to play a prominent role.
The $η$-$η^\prime$ mixing angle is deduced from an updated phenomenological analysis of $J/ψ$ decays into a vector and a pseudoscalar meson. Corrections due to non-ideal $ω$-$ϕ$ mixing are confirmed to be crucial to find $θ_P=(-16.9\pm 1.7)^\circ$, in agreement with most recent analyses. The newly reported values of $B(J/ψ\toρπ)$ by the BABAR and BES Collaborations make more difficult a reasonable description of data.
We show results from calculations in full lattice QCD of the mass, leptonic width and radiative decay rate to eta_c of the J/psi meson. These provide few % tests of QCD. Another (1.5%) test comes from comparison of time-moments of the vector charmonium correlator with results derived from the experimental values of R(e+e- to hadrons) in the charm region.
We investigate the masses of the lowest c\bar{c} states, the J/psi and eta_c, in nuclear matter using QCD sum rules. Up to dimension four, the differences between the operator product expansions in vacuum and in medium arise from the density-dependent change in the gluon condensate and from a new contribution proportional to the nucleon expectation value of the twist-2 gluon operator. Both terms together give an attractive shift of about 5-10 MeV to the J/psi and eta_c masses in nuclear matter.
We compute the decay constants of the lowest ccbar-states with quantum numbers J(PC)=0(-+) [eta_c], 1(--) [J/psi], and 1(+-) [hc] by using lattice QCD and QCD sum rules. We consider the coupling of J/psi to both the vector and tensor currents. Lattice QCD results are obtained from the unquenched (Nf=2) simulations using twisted mass QCD at four lattice spacings, allowing us to take the continuum limit. On the QCD sum rule side we use the moment sum rules. The results are then used to discuss the rate of eta_c --> gamma gamma decay, and to comment on the factorization in B --> X K decays, with …
It is shown that difficulties in reconciling the values of the cross section e+e- -> J/psi+eta_c measured at BELLE and calculated within non-relativistic QCD (NRQCD) are caused not by some misinterpretation of the data or other exotic explanations, but by poor applicability of NRQCD to such processes. We use general theory of hard exclusive processes in QCD together with more realistic models of charmonium wave functions, and show that the BELLE result can be naturally explained.
We study eta_c and J/psi hadroproduction induced by multiple scattering off fixed centres in the target. We determine the minimum number of hard scatterings required and show that additional soft scatterings may be factorized, at the level of the production amplitude for the eta_c and of the cross section for the J/psi. The J/psi provides an interesting example of soft rescattering effects occurring inside a hard vertex. We also explain the qualitative difference between the transverse momentum broadening of the J/psi and of the Upsilon observed in collisions on nuclei. We point out that resca…
We review selected recent Belle results in quarkonium physics, that include precision measurement of the eta_b(1S) parameters, evidence for the eta_b(2S); evidence for the psi_2(1D); observation of the psi(4040) and psi(4160) transitions to J/psi eta with anomalously high rates; observation of the Upsilon(5S) transitions to Upsilon(1D)pi+pi- and Upsilon(1S,2S)eta. The low excitations of charmonium and bottomonium are in agreement with the Lattice QCD and effective theories calculations, while high excitations show unexpected properties.
The composition of the eta and eta' mesons has long been a source of discussion and is of current interest with new experimental results appearing. We investigate what can be learnt from a number of different processes: V to P gamma and P to V gamma (V and P are light vector and pseudoscalar mesons respectively), P to gamma gamma, J/psi,psi' to P gamma, J/psi,psi' to P V, and chi_{c0,2} to PP. These constrain the eta-eta' mixing angle to a consistent value, phi approx 42 degrees; we find that the c cbar components are lesssim 5% in amplitude. We also find that, while the data hint at a small g…
We reanalyze the eta-gamma and eta'-gamma transition form factors within the modified hard scattering approach on the basis of new experimental data from CLEO and L3. Our approach perfectly describes the experimental data over a wide range of the virtuality of the probing photon, 1 GeV^2 < Q^2 < 15 GeV^2. The analysis provides hints that the conventional flavor octet-singlet scheme for the eta-eta' mixing is too simple. A more general mixing scheme on the other hand, involving two mixing angles, leads to a very good description of the transition form factors and also accounts for the two-photo…
The $η$-$η^\prime$ pseudoscalar mixing angle and the gluonium content of the $η^\prime$ meson are deduced from an updated phenomenological analysis of $J/ψ$ decays into a vector and a pseudoscalar meson. The values for the mixing angle and the gluonic content of the $η^\prime$ wave function are $ϕ_P=(44.5\pm 4.3)^\circ$ and $Z^2_{η^\prime}=0.28\pm 0.21$, respectively.
The $η$-$η^\prime$ pseudoscalar mixing angle and the gluonium content of the $η^\prime$ meson are deduced from an updated phenomenological analysis of $J/ψ$ decays into a vector and a pseudoscalar meson. In absence of gluonium, the value of the mixing angle in the quark-flavour basis is found to be $ϕ_P=(40.7\pm 2.3)^\circ$. In presence of gluonium, the values for the mixing angle and the gluonic content of the $η^\prime$ wave function are $ϕ_P=(44.6\pm 4.4)^\circ$ and $Z^2_{η^\prime}=0.29^{+0.18}_{-0.26}$, respectively. The newly reported values of $B(J/ψ\toρπ)$ by the BABAR and BES Collabora…
We update the values of the eta-eta' mixing angle and of the eta' gluonium content by fitting our measurement R_phi = BR(phi to eta' gamma)/ BR(phi to eta gamma) together with several vector meson radiative decays to pseudoscalars (V to P gamma), pseudoscalar mesons radiative decays to vectors (P to V gamma) and the eta' to gamma gamma, pi^0 to gamma gamma widths. From the fit we extract a gluonium fraction of Z^2_G = 0.12 +- 0.04, the pseudoscalar mixing angle psi_P = (40.4 +- 0.6) degree and the phi-omega mixing angle psi_V = (3.32 +- 0.09) degree. Z^2_G and psi_P are fairly consistent with …
The known ratio of the branching fractions for D_s^* --> D_s pi^0 and D_s^* --> D_s gamma may be used to extract the coupling of eta mesons to strange quarks once the value of the pi^0-eta mixing angle is known. This requires that realistic models for the spectra as well as the magnetic dipole (M1) decays of the heavy-light (Q qbar) mesons are available. The coupling of eta mesons to light quarks may then be estimated using SU(3) flavor symmetry. Applied to the quark model for the baryons, an eta NN pseudovector coupling constant of f_{eta NN} = 0.35^{+0.15}_{-0.25} is obtained. If the charm q…
It has been suggested in Ref. [A. E. Bondar and V. L. Chernyak, Phys. Lett. B 612, 215 (2005)] that the disagreement between theoretical calculations and experimental observations for the rate for the process e+ e- -> J/psi + eta_c at the B factories might be resolved by using the light-cone method to take into account the relative momentum of the heavy-quark and antiquark in the quarkonia. The light-cone result for the production cross section in Ref. [A. E. Bondar and V. L. Chernyak, Phys. Lett. B 612, 215 (2005)] is almost an order of magnitude larger than existing NRQCD factorization resul…
The large rate of the $J/ψ+η_c$ production observed by the Belle collaboration has posed a serious challenge to our understanding of the quarkonium. We examine a scenario that there exists a light scalar boson around 5 GeV, with an enhanced coupling solely to the charm quark. Such a scenario would explain the Belle anomaly. It also predicts a significant increase in $J/ψ$ plus open charm pair production. An immediate test for the scalar boson is to look for a peak around 5 GeV in the recoil mass spectrum of $J/ψ$, because the scalar boson can also be produced in association with the $J/ψ$. Fin…
The relation between the ratio Gamma_{ee}(psi')/Gamma_{ee}(J/psi) and Gamma_{2gamma}(eta_{c}')/Gamma_{2gamma}(eta_{c}), expressed in terms of the configuration mixing amplitudes induced by the contact spin-spin interaction of quarks in the ground and radial excitation states, is shown to give, after the inclusion of the newly derived relativistic corrections, the radiative eta_{c}'- and η_c-width ratio in fair accord with recent experiments. The dynamical model is proposed to derive the ratio of relative probability of the ground (eta_{c}(2980))- and first radial excitation (eta_{c}'(3640))-st…
The $η$-$η^\prime$ pseudoscalar mixing angle and the gluonium content of the $η^\prime$ meson are deduced from an updated phenomenological analysis of $V\to Pγ$ and $J/ψ\to VP$ decays. In absence of gluonium, the value of the mixing angle in the quark-flavour basis is found to be $ϕ_P=(41.5\pm 1.2)^\circ$ from $V\to Pγ$ and $ϕ_P=(40.5\pm 2.4)^\circ$ from $J/ψ\to VP$. In presence of gluonium, the values for the mixing angle and the gluonic content of the $η^\prime$ wave function are $ϕ_P=(41.4\pm 1.3)^\circ$ and $Z^2_{η^\prime}=0.04\pm 0.09$ from $V\to Pγ$ and $ϕ_P=(44.5\pm 4.3)^\circ$ and $Z^2…
It is shown that the study of the ω-ρinterference pattern in the J/psi -> (rho+omega)eta -> pi+pi-eta decay provides evidence for the large (nearly 90 degrees) relative phase between the isovector one-photon and three-gluon decay amplitudes.
The two-particle decays of B_c^+ to psi pi^+(rho^+) and B_c^+ to eta_c pi^+(rho^+) are considered in a way taking into account a soft binding of quarks in the heavy quarkonia and a hard gluon exchange between the constituents at large recoil momenta of psi(eta_c). An approximate double enhancement of the amplitudes is found because of the nonspectator t-channel contribution.
We calculate the exclusive cross sections for e^+ e^- annihilation into two charmonium states through a virtual photon. Purely electromagnetic contributions are surprisingly large, changing the cross sections by as much as 21%. The predicted cross section for J/psi + eta_c is about an order of magnitude smaller than a recent measurement by the BELLE Collaboration, although part of the discrepancy can be attributed to large relativistic corrections. The cross sections for S-wave + P-wave, P-wave + P-wave, and S-wave + D-wave charmonium states are also calculated. It may be possible to discover …
We study the scattering lengths of charmonia (J/psi and eta_c) with light hadrons (pi, rho and N) by the quenched lattice QCD simulations on 24x24x24x48, 32x32x32x48 and 48x48x48x48 lattices with the lattice spacing a = 0.068 fm. The scattering length is extracted by using the Luscher's phase-shift formula together with the measurement of the energy shift Delta E of two hadrons on the lattice. We find that there exist attractive interactions in all channels, J/psi(eta_c)-pi, J/psi(eta_c)-rho and J/psi(eta_c)-N: The s-wave J/psi-pi (eta_c-pi) scattering length is determined as 0.0119+-0.0039 fm…
As a test of the color-singlet mechanism of the nonrelativistic QCD (NRQCD) factorization approach, we consider the exclusive two-quarkonium productions in electron-positron annihilation e+ e- -> eta_c + gamma and e+ e- -> J/psi + J/psi at B factories. The cross sections are computed to the next-to-leading order in alpha_s and are resummed to all orders in half the relative velocity v of the charm quark in each meson rest frame. The available theoretical prediction of the cross section for e+ e- -> J/psi + eta_c at the same level of theoretical accuracies is consistent with the available exper…
The isospin violating $J/Ψ\to ϕπ^0 η$ decay is thought to be dominated by the mixing of the $f_0(980)$ and $a_0(980)$ scalar resonances. We make a theoretical evaluation of the $J/Ψ\to ϕπ^0 η$ decay extending our own previous model for other $J/Ψ$ decays into one vector meson and two pseudoscalars using the techniques of the chiral unitary approach. The scalar resonances are dynamically generated through the final state interaction of the pseudoscalar mesons implementing unitarity from the lowest order ChPT amplitudes. Besides the direct $J/ΨϕPP$ vertex, other mechanisms like the sequential ex…
We discuss the measured partial width of the pseudoscalar charmonium state eta_c into two photons. Predictions from potential models are examined and compared with experimental values. Including radiative corrections, it is found that present measurements are compatible both with a QCD type potential and with a static Coulomb potential. The latter is then used to give an estimate on the eta_b decay into two photons. Results for eta_c are also compared with those from j/psi data through the NRQCD model.
We discuss the partial width of the pseudoscalar charmonium state eta_c and bottomonium state eta_b into two photons. Predictions from potential models are examined and compared with experimental values for the eta_c case. Through the NRQCD factorisation procedure results for eta_c are also compared with those from J/psi data, and results for eta_b to the Upsilon decay data.
Taking into account the new data on the full width of D^{\ast\pm}(2010) and the mass difference of the charged and neutral beauty mesons B^\pm, B^0,\bar B^0, the branching ratios of the decays psi(3770), Upsilon(10580) to pi^+pi^-, K bar K, rho(omega)pi, rho(omega)eta, rho(omega)eta^prime, K^ast bar K+ c.c, rho^+ rho^-, and K^ast bar K^ast are re-evaluated in the model in which the Okubo-Zweig-Iizuka rule is violated due to the real intermediate state D\bar D in case of psi(3770) and B\bar B in case of Upsilon(10580). The inclusive annihilation of psi(3770) and Upsilon(10580) into light hadron…
We propose that the radiative decay process, η_b\to J/ψγ, may serve as a clean searching mode for η_b in hadron collision facilities. By a perturbative QCD calculation, we estimate the corresponding branching ratio to be of order 10^{-7}. Though very suppressed, this radiative decay channel in fact has larger branching ratio than the hadronic decay process η_b\to J/ψJ/ψ, which was previously hoped to be a viable mode for ferreting out η_b in Tevatron Run 2. The discovery potential of η_b through this channel seems promising in the forthcoming LHC experiments and maybe even in Tevatron Run 2, t…
It is argued that the search of the J/psi --> f0(980)omega and J/psi --> a0(980)rho decays and the more precise definition of B(J/psi --> f0(980)phi) are the urgent purposes in the J/ψspectroscopy. It is shown that the study of the omega-rho0 interference pattern in the J/psi --> (ρ^0+ω)eta --> pi+pi-eta decay provides evidence for the large (nearly pi/2) relative phase between the isovector one-photon and three-gluon decay amplitudes .
In the framework of R-parity violating (\rpv) supersymmetry, we try to find a consistent explanation for both recently measured CP asymmetry in B^0 --> phi K_S decay and the large branching ratio of B^{+/-} --> eta' K^{+/-} decay, which are inconsistent with the Standard Model (SM) prediction. We also investigate other charmless hadronic B --> PP and B --> VP decay modes whose experimental data favor the SM: for instance, recently measured CP asymmetries in B^0 --> eta^{prime} K_S and B^0 --> J / Psi K_S. We find that all the observed data can be accommodated for certain values of \rpv couplin…
We calculate next to leading order QCD corrections to the direct decays b -> J/Psi + X and b -> eta_c + X. The strong renormalization scale dependence is seen to persist also in this order and in fact the rate is driven to an unphysical negative value at the M_b scale. We show that this is a consequence of the strong suppression and scale dependence in the leading order term. Large cancellations take place between terms from three different orders in alpha_s. Lacking a third order calculation we are forced to throw away the leading order term and all but one of the next to leading order terms.…
Over a large fraction of phase space a combination of an operator product and heavy quark expansions effectively turn the decay $\bar B -> D^{(*)0} e+e-$ into a ``short distance'' process, i.e., one in which the weak and electromagnetic interactions occur through single local operators. These processes have an underlying W-exchange quark diagram topology and are therefore Cabibbo allowed but suppressed by combinatoric factors and short distance QCD corrections. Our technique allows a clearer exploration of these effects. For the decay $\bar B_{d,s} -> J/psi(η_c) e+e-$ one must use a non-relati…
The branching fraction of the psi(3770) decays into charmless final states is estimated in the S- and D-wave charmonia mixing scheme. With the information of the hadronic decays of J/psi and psi(3686), it is found that a large branching fraction, up to 13% of the total psi(3770) decays may go to charmless final states. The experimental search for these decays is also discussed.
Statements concerning Extended Unitarity (EU) are clarified
We analyze B -> K H_c (where H_c = eta_c, J/psi, chi_{cJ(J=0,1)}) decays estimating nonfactorizable contributions from the light-cone sum rules (LCSR). Nonfactorizable contributions are sizable for B -> K J/psi and particularly for B -> K chi_{c1} decay. For the B decays into a (pseudo)scalar charmonia we find small nonfactorizable contributions which cannot accommodate relatively large branching ratios obtained by measurements. This specially concerns the puzzling B -> K chi_{c0} decay.
Within the standard model (SM), the time dependent CP asymmetries in B -> psi K_S, B -> eta' K_S and B -> phi K_S are expected to give the same result i.e. sin (2 beta). However recent measurements of the mixing induced CP asymmetries in B -> phi K_S and B -> eta' K_S modes give results whose central values differ from SM expectations. We explore the effects of new physics in the two Higgs doublet model (THDM), which allows tree level flavor changing neutral currents (so called Model III), and the model with extra vector like down quark (VLDQ). We find that the observed mixing induced CP asymm…
The recent measurements by CLEO Collaboration for the inclusive J/Psi and Psi(2S) production in Upsilon(1S) decay and our previous calculation are analyzed. The J/Psi momentum spectrum and the production ratio of Psi(2S) versus J/Psi favour Upsilon to J/Psi(Psi(2S)) + ccbar g as the dominant contribution. We point out that the differences between the experimental data and our previous results are mainly originated from the setting of the parameter charm quark mass. We further suggest the associate strange particle enhancement as a probe for the open charm particles in Upsilon to J/Psi (Psi(2S)…
We use the framework of a relativistic constituent quark model to study the semileptonic transitions of the Bc meson into CCbar charmonium states where CCbar = etaC (1S0), J/psi (3S1), chiC0 (3P0), chiC1 (3P1), hc (1P1), chiC2 (3P2), psi (3D2). We compute the q^2-dependence of all relevant form factors and give predictions for their semileptonic Bc decay modes including also their tau-modes. We derive a formula for the polar angle distribution of the charged lepton in the (l nu) c.m. frame and compute the partial helicity rates that multiply the angular factors in the decay distribution. For t…
Cabibbo allowed two-body hadronic weak decays of Lambda b baryons are analyzed in the factorization approximation. We use the covariant oscillator quark model to evaluate the heavy to heavy and heavy to light form factors. When applied in the heavy quark limit, our form factors satisfy all the constraints imposed by heavy quark symmetry. The decay rates and up-down asymmetries for Lambda b baryon decaying into Lambda c +P(V) are calculated. It is found that the up-down asymmetry is negative in all these decay modes. Furthermore, the prediction Br(Lambda b to Lambda+J/psi)=2.49 times 10^-4 is c…
We study the large-order asymptotic behavior of the perturbation series for short-distance coefficients in the NRQCD factorization formulas for the decays J/psi --> e^+e^- and eta_c --> gamma gamma. The short-distance coefficients of the leading matrix elements are calculated to all orders in the large-N_f limit. We find that there is a universal Borel resummable renormalon associated with the cancellation of the Coulomb singularity in the short-distance coefficients. We verify that the ambiguities in the short-distance coefficients from the first infrared renormalon are canceled by ambiguitie…
With new data sets, recently completed analyses and renewed interest, there has been significant progress in addressing existing questions about quarkonia production and decay ... but also new questions and new confrontation with theory. Some highlights include the firm establishment of the eta_c^' and of the ``missing'' psi^' decays to pseudoscalar-vector final states, improved information on the nature of the psi(3770), and the observation of a new, puzzling charmonium-like state at 3872 MeV.
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