16862018
Corrections to chiral dynamics of heavy hadrons: SU(3) symmetry breaking.
In previous publications we have analyzed the strong and electromagnetic decays of heavy mesons and heavy baryons in a formalism which incorporates heavy-quark and chiral symmetries. There are two possible symmetry-breaking effects on the chiral dynamics of heavy hadrons: the finite-mass effects from light quarks and the 1/[ital m][sub [ital Q]] corrections from heavy quarks. In the present paper, chiral-symmetry-breaking effects are studied and applications to various strong and radiative decays of heavy hadrons are illustrated. SU(3) violations induced by chiral loops in the radiative decays of charmed mesons and charmed baryons are compared with those predicted by the constituent quark model. In particular, available data for [ital D][sup *] decays favor values of the parameters in chiral perturbation theory which give predictions for [ital D][sup *] decays close to the quark model results except for the [ital D][sub [ital s]][sup *+]. Implications are discussed.
34810684
Restudy of the open-superstring tree amplitudes by looking at their field-theoretical limits.
We carry out complete computations of some open- and closed-superstring tree amplitudes by using the bosonized covariant vertices. Some open-superstring amplitudes so obtained are shown to be different from those obtained in the light-cone gauge approach by some numerical factors. The low-energy limits of our five open-superstring amplitudes are then shown to match the five super Yang-Mills field amplitudes while the five light-cone gauge open-superstring amplitudes fail to do so.
13594754
Heavy-flavor-conserving nonleptonic weak decays of heavy baryons.
The heavy-flavor-conserving nonleptonic weak decays of heavy baryons are studied in a formalism that incorporates both heavy-quark symmetry and chiral symmetry. The phenomenological {Delta}{ital S}=1 nonleptonic weak chiral Lagrangian for these transitions contains two independent coupling constants that describe the transitions between two flavor-SU(3) antitriplet heavy baryons, and the transitions between two flavor-SU(3) sextet heavy baryons. In the MIT bag model and the diquark model, only transitions between antitriplets are allowed. The coupling constants for these transitions are calculated in both models. The result is applied to specific nonleptonic decays such as {Xi}{sub {ital c}}{r arrow}{Lambda}{sub {ital c}}{pi}, and the branching ratios are found to be of the order of 10{sup {minus}4}. An example of a nonleptonic decay due to symmetry breaking is provided by {Omega}{sub {ital c}}{r arrow}{Xi}{sub {ital c}}{sup {prime}}{pi}, which is estimated to have a smaller branching ratio, of the order of 10{sup {minus}5}.
120093276
CONSISTENT FACTORIZATION AND TWIST-3 CONTRIBUTIONS TO THE POLARIZED NUCLEON STRUCTURE FUNCTION g2(x,Q2)
Quark mass effects are clarified in the parton model approach to the transversely polarized nucleon structure function. The special propagator technique is employed to obtain manifestly gauge invariant results and extract the buried short-distance contributions inside the soft part after momentum factorization in the collinear expansion approach. A generalized massive special propagator for a massive quark is constructed. We identify the corresponding matrix elements of the transversely polarized structure function in deep inelastic scattering by the massive special propagator technique.
10063732
Effective Lagrangian approach to weak radiative decays of heavy hadrons.
Motivated by the observation of the decay B\ifmmode\bar\else\textasciimacron\fi{}\ensuremath{\rightarrow}K${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{\mathrm{*}}$\ensuremath{\gamma} by the CLEO Collaboration, we have systematically analyzed the two-body weak radiative decays of bottom and charmed hadrons. There exist two types of weak radiative decays: One proceeds through the short-distance b\ensuremath{\rightarrow}s\ensuremath{\gamma} transition and the other occurs through W exchange accompanied by a photon emission. Effective Lagrangians are derived for the W-exchange bremsstrahlung processes at the quark level and then applied to various weak electromagnetic decays of heavy hadrons. Predictions for the branching ratios of B${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}0}$\ensuremath{\gamma}, ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{b}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Sigma}}}_{\mathit{c}}^{0}$\ensuremath{\gamma}, ${\mathrm{\ensuremath{\Xi}}}_{\mathit{b}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{0}$\ensuremath{\gamma}, and ${\mathrm{\ensuremath{\Xi}}}_{\mathit{b}}^{0}$\ensuremath{\rightarrow}\ensuremath{\Xi}${\mathcal{'}}_{\mathit{b}}^{0}$\ensuremath{\gamma} are given. In particular, we find scrB(B${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{0}$\ensuremath{\rightarrow}${\mathit{D}}^{\mathrm{*}0}$\ensuremath{\gamma})\ensuremath{\approxeq}0.9\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}6}$. Order of magnitude estimates for the weak radiative decays of charmed hadrons, ${\mathit{D}}^{0}$\ensuremath{\rightarrow}K${\mathrm{\ifmmode\bar\else\textasciimacron\fi{}}}^{\mathrm{*}0}$\ensuremath{\gamma}, ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{c}}^{+}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Sigma}}}^{+}$\ensuremath{\gamma}, and ${\mathrm{\ensuremath{\Xi}}}_{\mathit{c}}^{0}$\ensuremath{\rightarrow}${\mathrm{\ensuremath{\Xi}}}^{0}$\ensuremath{\gamma}, are also presented. Within this approach, the decay asymmetry for antitriplet to antitriplet heavy baryon weak radiative transitions is uniquely predicted by heavy quark symmetry. The electromagnetic penguin contribution to ${\mathrm{\ensuremath{\Lambda}}}_{\mathit{b}}^{0}$\ensuremath{\rightarrow}\ensuremath{\Lambda}\ensuremath{\gamma} is estimated by two different methods and its branching ratio is found to be of the order of 1\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}5}$. We conclude that weak radiative decays of bottom hadrons are dominated by the short-distance b\ensuremath{\rightarrow}s\ensuremath{\gamma} mechanism.
36067168
Dimensional regularization and perturbative solution of the chiral Schwinger model.
The anomalous chiral Schwinger model is regulated by the method of dimensional regularization and is solved by diagrammatic perturbative expansion. It is shown that there is a regulation ambiguity in the solution. The result disagrees with Das's assertion and agrees with that of Jackiw, Rajaraman, and others.
45380547
Glueball components of the meson f2(1270).
It is shown that in order to explain the ratios {ital x} and {ital y} of the helicity amplitudes for the process {ital J}/{psi}{r arrow}{gamma}+{ital f}{sub 2}(1270) and the experimental datum {ital R}={ital B}({psi}{prime}({bold 3685}){r arrow}{gamma}+{bold f}{sub {bold 2}}({bold 1270}))/{ital B}({ital J}/{psi}{r arrow}{gamma}+{ital f}{sub {bold 2}}({bold 1270})) =(9{plus minus}3)% in terms of the mixture between the meson {ital f}{sub 2}(1270) and a 2{sup ++} glueball, two {ital D}-wave components have to be considered in addition to the {ital S}-wave component of the 2{sup ++} glueball.