We study the decay constants of pseudoscalar and vector $B$ meson in the framework of light-cone quark model (LCQM). We apply the variational method to the relativistic Hamiltonian with the Gaussian-type trial wave function to obtain the values of $β$ (scale parameter). Then with the help of known values of constituent quark masses, we obtain the numerical results for the decay constants $f_P$ and $f_V$, respectively. We compare our numerical results with the existing experimental data.
The contributions of one-loop diagrams with dynamical vector mesons to masses and decay constants of pseudoscalar mesons are determined. Hereby, a relativistic Lagrangian for both the pseudoscalar-meson octet and the vector-meson nonet is used. The vector mesons are given in the antisymmetric tensor representation. Both the differences between static and dynamical vector mesons and the differences between calculations with and without vector mesons are studied as functions of the light quark mass.
Sum rules are derived relating mean squared charge radii of the pseudoscalar mesons with the convergent integral of the difference of hadron photoproduction cross-sections on pseudoscalar mesons.
We investigate decay modes of B mesons emitting two pseudoscalar (P) mesons in the Quark Diagram Scheme at SU(3) level. Several relations among the decay amplitudes are obtained and various branching ratios are predicted.
A new meson mass relation for meson nonet is given after considering mixing with glueball. The mixing between pseudoscalar mesons and pseudoscalar glueball will decrease the mass of glueball by about 500 Mev. So, according to the predicted mass of the pure pseudoscalar glueball given by lattice calculation and effective Hamiltonian, the expected mass of mixed pseudoscalar glueball is about 1.7 Gev. This result is helpful for experimemtal search for the mixed Isoscalar pseudoscalar glueball.
In this paper, we investigate phenomenologically two-body weak decays of the bottom mesons emitting pseudoscalar and tensor mesons. Decay amplitudes are obtained using the factorization scheme in the improved ISGW II model. Branching ratios for the CKM-favored and CKM-suppressed decays are calculated.
Aspects of Scalar Meson Dominance in semi- and non-leptonic weak pseudoscalar meson decays are shortly discussed on the basis of the Quark-Level Linear Sigma Model.
We investigate the nonleptonic decay of charmed meson into two pseudoscalar mesons using the vector--dominance model, and compare the results with those obtained from the factorization model. In particular, we discuss the role of the annihilation diagrams in the two models.
With usage of obvious mechanisms of quark currents the amplitudes of leptonic decaies of pseudoscalar mesons are investigated. The estimation for a constant of leptonic decay of the D+ meson is obtained, f_D+ ~ 0.23 GeV.
We study Cabibbo-Kobayashi-Maskawa (CKM) favored weak decays of Bc mesons in the Isgur-Scora-Grinstein-Wise (ISGW) quark model. We present a detailed analysis of the Bc meson decaying to a pseudoscalar meson (P) and an axial-vector meson (A). We also give the form factors involving transition in the ISGW II framework and consequently, predict the branching ratios of decays.
The ongoing and planned experimental activities with direct reference to light unflavoured pseudoscalar mesons motivate a new theoretical study regarding their properties. An overview including details on new precise calculations is presented.
Two body nonleptonic weak decays of bottom mesons to a pseudoscalar meson and an axial-vector meson involving charmed states are studied using the non-relativistic quark model. We calculate the branching ratios of these decays by employing the factorization hypothesis. Obtained results are in good agreement with the existing experimental data. We also calculated the branching ratios in the light of heavy quark symmetry constraints and compared with the exiting theoretical analyses.
The strong coupling constant of doubly heavy baryons with light pseudoscalar mesons $ π$ and $ K $ are computed within the light cone sum rules. We take into account two-particle and three-particle distribution amplitudes of the said pseudoscalar mesons. We compare our result with the one existing in the literature.
Present-day experimental and phenomenological situation about pseudoscalar ($π^0$, $η$, $η'$) meson transition form factors is briefly reviewed. Necessity of more sophisticated behaviours in time-like region of these form factors is emphasized. Four-resonance unitary and analytic model of the pseudoscalar meson transition form factors is constructed, which describes well all existing experimental information.
Similarly to the electromagnetic pseudoscalar-meson transition form factors one can define also strange-quark vector current pseudoscalar-meson transition form factors, contributing only to a behaviour of the isoscalar parts of the previous ones. Their explicit form is found by constructing unitary and analytic models of the strange pseudoscalar-meson transition form factors dependent only on $ω$ and $ϕ$ coupling constant ratios as a free parameters. Numerical values of these ratios are then determined from the corresponding pseudoscalar-meson transition form factors by employing the $ω$-$ϕ$ m…
The leptonic decay constant of the pseudoscalar mesons a calculated by use of the relativistic constituent quark model constructed on the point form of Poincare-covariant quantum mechanics. We discuss the role relativistic corrections for decay constants of pseudoscalar mesons with heavy quarks. We consider the heavy mass limit of decay constant for two-particle system with equal masses.
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.
Present and planned experiments motivate new theoretical study of properties of light unflavoured pseudoscalar meson decays. An overview including details on two-loop calculation in SU(3) limit is given.
In this communication we discuss few topics related with modern experimental data on the physics of light pseudoscalar mesons. It includes the contribution of the pseudoscalar mesons to the muon anomalous magnetic moment (AMM), $g-2$, the rare decays of light pseudoscalar mesons to lepton pair, the transition form factors of pseudoscalar mesons at large momentum transfer, the pion transversity form factor. Measuring the muon anomalous magnetic moment $g-2$ and the rare decays of light pseudoscalar mesons into lepton pair $P\rightarrow l^{+}l^{-} $ serve as important test of the standard model.…
We study the effects of non-vanishing pseudoscalar masses in $τ$ decays into three mesons. The hadronic matrix elements are obtained by using the generalized structure of the chiral currents with nonvanishing pseudoscalar masses and implementing the low-lying resonances in the different channels. We demonstrate that suitable angular distributions are sensitive to the mass effects in the chiral Langrangian. Numerical results for the rele\-% vant structure functions are given for the decay modes $τ\rightarrow νπ^-π^-π^+$, $νK^-π^-π^+$ and $νK^-π^-K^+$.
The 125 GeV resonance discovered at the LHC could be a heavy quarkonium pseudoscalar meson. The diagonalization of the mass matrix of the isoscalar quarkonium states $|ζ>$ and $|ζ^{0'}>$ produces the states identified with the pseudoscalar heavy quarkonium mesons $ζ^0$ and $ζ^{0'}$. For a mixing angle $ϕ\sim 36\,^{\circ}$ the mass of the bound state pseudoscalar resonance $ζ^0$ is $m_{ζ^0}\sim 125$ GeV. The decay rates of the quarkonium $ζ^0$ meson are estimated and compared to the standard model Higgs boson predictions. The importance of determining the spin-parity of the 125 GeV resonance is…
We have systematically calculated the S-wave pseudoscalar meson and decuplet baryon scattering lengths to the third order in the small scale expansion scheme of the heavy baryon chiral perturbation theory. We hope the future study may test the framework and the present predictions.
We complete the perturbative next-to-leading order corrections to the hard scattering amplitudes of deeply virtual meson leptoproduction processes at leading twist-two level by presenting the results for the production of flavor singlet pseudoscalar mesons. The new results are given in the common momentum fraction representation and in terms of conformal moments. We also comment on the flavor singlet results for deeply virtual vector meson production.
We have systematically studied the S-wave pseudoscalar meson and heavy vector meson scattering lengths to the third order with the chiral perturbation theory, which will be helpful to reveal their strong interaction. For comparison, we have presented the numerical results of the scattering lengths (1) in the framework of the heavy meson chiral perturbation theory and (2) in the framework of the infrared regularization. The chiral expansion converges well in some channels.
The relative magnitude of the decay constants of the pseudoscalar and vector beauty mesons poses (in contrast to the case of charmed mesons) a long-standing puzzle. We revisit this problem within the framework of our recent improvements of the QCD sum-rule formalism for relating observable properties of mesons to quantum chromodynamics and are led to conclude that the decay constants of the beauty vector mesons are undoubtedly smaller than those of their pseudoscalar counterparts.
This paper presents the two body weak nonleptonic decays of B mesons emitting pseudoscalar (P) and vector (V) mesons within the framework of the diagrammatic approach at flavor SU(3) symmetry level. Using the decay amplitudes, we are able to relate the branching fractions of B PV decays induced by both b c and b u transitions, which are found to be well consistent with the measured data. We also make predictions for some decays, which can be tested in future experiments.
We analyze the decay modes $B^0 \to D^{*-} D^0 K^+$ and $B^0 \to D^{*-} D^{*0} K^+$ and, using the available experimental data, we find bounds for the constants g and h describing the strong coupling of heavy mesons to light pseudoscalar mesons. Both the decay channels are dominated by broad L=1 charm resonances; the dominance is effective also in $B^0 \to D^{-} D^0 K^+$ and $B^0 \to D^{-} D^{*0} K^+$.
It is shown that the diagonalization of the axial-vector -- pseudoscalar transitions in the effective meson Lagrangian in presence of electromagnetic interactions leads to a deviation from the vector meson dominance picture which usually arises in the Nambu - Jona-Lasinio model. The essential features of such modification of the theory are studied. Some important examples are considered in detail.
We discuss the sensitivity of nucleon properties (mass, magnetic moments and electromagnetic form factors) on the variation of the pseudoscalar meson masses in the context of the perturbative chiral quark model. The obtained results are compared to data and other theoretical predictions.
We calculate the leptonic constant for the ground pseudoscalar state of B_c meson in the framework of QCD-motivated potential model taking into account the two-loop anomalous dimension for the heavy quark current in the nonrelativistic QCD as matched with the full QCD.
We study the vacuum properties of the pseudoscalar glueball and charmed mesons by using the so-called extended Linear Sigma Model (eLSM). This model includes scalar and pseudoscalar mesons, as well as vector and axial-vector mesons. We calculate the mesonic and baryonic decays of the pseudoscalar glueball, where we fixed its mass to $2.6$ GeV, as predicted by lattice-QCD simulations, and take a closer look at the scalar-isoscalar decay channel. As a second step, we enlarge the so-called extended linear Sigma model (eLSM) by including the charm quark to a global $U(4)_r\times U(4)_l$ chiral sym…
Neutral pseudoscalar mesons in an entangled or Einstein-Podolsky-Rosen state are routinely produced in phi and B factories. Based on the peculiar properties of an entangled state, we present some general exact theorems about parameters characterizing CP and CPT violations, by using various asymmetries defined for the correlated decays of the two entangled mesons, which are rigorously calculated.
We discuss the light-front zero-mode issue in the light-front quark model prediction of the twist-3 distribution amplitude of a pseudoscalar meson from the perspective of the vacuum fluctuation consistent with the chiral symmetry of QCD.
We expand the study of the pseudoscalar glueball and its first excited state by constructing an interaction Lagrangian which produces the two- and three-body decays of the pseudoscalar glueball, $J^{PC}=0^{-+}$, into the (pseudo)scalar and the excited (pseudo)scalar mesons as well as by constructing other two different chiral Lagrangians which describe the two- and three-body decays of the first excited pseudoscalar glueball, $J^{PC}=0^{*-+}$, into the (pseudo)scalar and the excited (pseudo)scalar mesons. We compute the decay channels for the ground state of a pseudoscalar glueball with a mass…
Using a simple model in the context of the Dyson-Schwinger-Bethe-Salpeter approach, we investigate the effects of a dressed-quark-gluon vertex on pseudoscalar meson masses. In particular, we focus on the unequal-mass case and investigate heavy-light meson masses; in addition, we study the premise of the effective treatment of heavy quarks in our approach.
We discuss the two and three particle light-cone distribution amplitudes (DAs) of pseudoscalar nonsinglet mesons of twist 3 and 4. Using nonlocal operator identities and conformal expansion, we derive closed expressions for several DAs. We also include meson-mass corrections which prove to be dominant in the twist 4 DAs of K and eta mesons. Explicit parametrizations for the DAs of pi, K and eta mesons are given, with the numerical input parameters determined from QCD sum rules.
The possibility to constrain the meson distribution amplitude from the transitions of virtual photons to pseudoscalar mesons is investigated. It is shown that for a large range in the two photon virtualities the transition form factors are essentially independent of the distribution amplitudes. This in turn entails parameter-free predictions of QCD.
In the framework of a QCD relativistic potential model we evaluate the form factors describing the exclusive decays B => πl nu and B => K l+ l-. The present calculation extends a previous analysis of B meson decays into light vector mesons. We find results in agreement with the data, when available, and with the theoretical constraints imposed by the Callan-Treiman relation and the infinite heavy quark mass limit.
In this talk it is reported on an analysis of the form factors for the transitions from a photon to one of the pseudoscalar mesons pi0, eta, eta', etac within the modified perturbative approach in which quark transverse degrees of freedom are retained. The report is focused on the discussion of the surprising features the new BaBar data exhibit, namely the sharp rise of the pi-gamma form factor with the photon virtuality and the strong breaking of flavor symmetry in the sector of pseudoscalar mesons.
We study the decay of dynamically generated resonances from the interaction of two vectors into a $γ$ and a pseudoscalar meson. The dynamics requires anomalous terms involving vertices with two vectors and a pseudoscalar, which renders it special. We compare our result with data on $K^{*+}(1430)\to K^+γ$ and $K^{*0}(1430)\to K^0γ$ and find a good agreement with the data for the $K^{*+}(1430)$ case and a width considerably smaller than the upper bound measured for the $K^{*0}(1430)$ meson.
The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons with l<=2 for non-radially excited, and the l=0 radially excited mesons are presented for both charmed and beauty mesons. We also discuss the allowed decays of strange excited heavy mesons by emission of a K-meson.
The transition form factors of (D_s -> f_0 l nu), (D -> f_0 l nu) and (B_u -> f_0 l nu) decays are calculated in 3-point QCD sum rule method, assuming that "f_0" is a quark-antiquark state with a mixture of strange and light quarks. The branching ratios of these decays are calculated in terms of the mixing angle.
The $ρρ$ scattering has been studied by two groups which both claimed a dynamical generated scalar meson, most likely to be $f_0(1370)$. Here we investigate the influence of coupled-channels of pseudoscalar mesons, i.e., $ππ$ and $\bar KK$, on this dynamical generated scalar state. With the coupled channel effect included, the pole and partial decay widths are found to be more close to PDG values for $f_0(1500)$.
The temporal pseudoscalar meson correlation function in a QCD plasma is investigated in a range of temperatures exceeding $T_c$ and first time for a finite momenta which is of the experimental interest. The imaginary time formalism is employed for the finite temperature calculations. The behavior of the meson spectral function and of the temporal correlator is studied in the HTL approximation, where one replaces the free thermal quark propagators with the HTL resumed ones.
Using the description of the subprocess $γγ^*\to S(P)$ in terms of local Nambu-Jona-Lasinio model we calculate the cross sections of photoproduction of scalar and pseudoscalar mesons in high energy photon-lepton collisions processes. The dependence on the transversal momentum and the total cross sections in Weizsaecker-Williams approximation are presented.
We study three-body nonleptonic decays $B\to VVP$ by introducing two-meson distribution amplitudes for the vector-pseudoscalar pair, such that the analysis is simplified into the one for two-body decays. The twist-2 and twist-3 $ϕK$ two-meson distribution amplitudes, associated with longitudinally and transversely polarized $ϕ$ mesons, are constrained by the experimental data of the $τ\toϕKν$ and $B\toϕKγ$ branching ratios. We then predict the $B\toϕKγ$ and $B\toϕϕK$ decay spectra in the $ϕK$ invariant mass. Since the resonant contribution in the $ϕK$ channel is negligible, the above decay spe…
Masses of pseudoscalar and vector mesons, which are ground states of light or/and heavy quarks and antiquarks, have been calculated in the framework of an extended model of quasi-independent quarks with absolute uncertainties about 30 MeV. It is shown that the assumption on equidistant discrete levels for a mean field energy does not contradict to existing data and permits to reduce a number of model parameters. It is obtained, that a difference between neighbouring mean field energy levels is flavour independent. Values of spin-spin interaction between quarks and antiquarks with different fla…
The decays of a light scalar meson into a vector meson and a photon ($S\to Vγ)$ are evaluated in the tetraquark and quarkonium assignments of the scalar states. A link with the radiative decays $ϕ\to Sγ$ is established: experimental results for $S\to Vγ$ will allow to understand if the direct, quark-loop contribution to $ϕ\to Sγ$ or the kaon-loop contribution is dominant. Also strong decays $S\to PP$ -where $P$ denotes a pseudoscalar meson- are investigated: the tetraquark assignment works better than the quarkonium one. It is then also discussed why the tetraquark assignment is favoured with …
We consider the branching ratios and CP asymmetry in the B meson decays into two pseudoscalar mesons in the generalized factorization approximation. We also investigate the possible effects of the enhanced chromomagnetic interaction b --> s g on these exclusive B meson decays that was suggested as a possible solution to the semileptonic branching ratio of B mesons, the missing charm puzzle and the large B --> η^{'} + X_s. We finds that such enhanced b --> s g interaction degrades the agreement between the data and the model predictions for B meson decays into two light mesons in the generalize…
We calculate the strong coupling constants of light pseudoscalar mesons with heavy baryons within the light cone QCD sum rules method. It is shown that sextet--sextet, sextet--antitriplet and antitriplet--antitriplet transitions are described by one universal invariant function for each class. A comparison of our results on the coupling constants with the predictions existing in literature is also presented.
Effective Chiral Lagrangian is derived from QCD in the framework of Field Correlator Method. It contains the effects of both confinement and chiral symmetry breaking due to a special structure of the resulting quark mass operator. It is shown that this Lagrangian describes light pseudoscalar mesons, and Gell-Mann-Oakes-Renner relations for pions, eta and K mesons are reproduced. Spectrum of radial excitations of pions and K mesons is found and compared to experimentally known masses.
Mixing effects on the mass spectrum of light neutral pseudoscalar and vector mesons in the presence of an external uniform magnetic field $\vec B$ are studied in the framework of a two-flavor NJL-like model. The model includes isoscalar and isovector couplings both in the scalar-pseudoscalar and vector sectors, and also incorporates flavor mixing through a 't Hooft-like term. Numerical results for the $B$ dependence of meson masses are compared with present lattice QCD results. In particular, it is shown that the mixing between pseudoscalar and vector meson states leads to a significant reduct…
Matrix elements of flavor-diagonal light quark pseudoscalar densities and axial anomaly operators between vacuum and η and η' meson states have been determined. This has been done by evaluating current-current correlators of octet-octet and octet-singlet axial currents using QCD sum rules. The numerical values obtained for the matrix elements compare well with those obtained in the current literature.
The strong coupling constants of light pseudoscalar $π$, $K$ and $η$ mesons with decuplet--octet baryons are studied within light cone QCD sum rules, where $SU(3)_f$ symmetry breaking effects are taken into account. It is obtained that all coupling constants under the consideration are described by only one universal function even if $SU(3)_f$ symmetry breaking effects are switched into the game.
Some data on the ratio of vector to vector + pseudoscalar mesons, V/(V+P), and the probability of helicity zero vector states, rho_00, are now available from LEP. A possible relation between these two quantities and their interpretation in terms of polarized fragmentation functions are discussed; numerical estimates are given for the relative occupancies of K and K*, D and D*, B and B* states.
In semi-leptonic and other weak decays of mesons, the hadronic matrix elements of the operators in the weak Hamiltonian are parametrized by standard sets of independent, Lorentz invariant, form factors. For the case of pseudoscalar to vector meson transitions, it has been shown that a Quark Model description leads to relations between some of the form factors. Here, I give an alternate, and more general, proof of those relations and thus confirm that, in the Quark Model, not all the form factors for pseudoscalar to vector meson transitions are independent. As an application of this result, a Q…
Considering the fact that, a wide range of variation in masses of various states of heavy pseudoscalar and vector mesons can be seen in different models and the experimental data on masses of many of these states is not yet currently available, in this paper, we study the analytical calculation of heavy pseudoscalar and vector mesons mass spectra ( such as $η_{c}$, $B_{c}$, $η_{b}$, $J/ψ$, $B^{*}_{c}$ and $Υ$) and their corresponding wave functions in the framework of Bethe-Salpeter equation under the covariant instantaneous ansatz. The parameters of the framework were determined by a fit to t…
The strong coupling constants among members of the heavy spin--3/2 baryons containing single heavy quark with light pseudoscalar mesons are calculated in the framework of the light cone QCD sum rules. Using symmetry arguments, the structure independent relations among different correlation functions are obtained. It is shown that all possible transitions can be described in terms of one universal invariant function whose explicit expression is Lorenz structure dependent.
We employ the relativistic constituent quark model to give a unified description of the leptonic and semileptonic decays of pseudoscalar mesons (π, K, D, D_s, B, B_s). The calculated leptonic decay constants and form factors are found to be in good agreement with available experimental data and other approaches. We reproduce the results of spin-flavor symmetry in the heavy quark limit.
