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J. G. Korner

Publications and source records attributed to J. G. Korner.

32 records · Page 2Linked to original sources
arXiv1998

Charm and Bottom Baryon Decays in the Bethe-Salpeter Approach: Heavy to Heavy Semileptonic Transitions

Charm and bottom baryons and mesons are studied within the framework of a relativistically covariant 3D reduction of the Bethe-Salpeter equation. We carry out an analysis of semileptonic decays of heavy hadrons within this framework using explicit oscillator-type wave functions where we calculate Isgur-Wise functions, decay rates and asymmetry parameters. Within this model we also study the effect of interactions between the light quarks inside the heavy baryon and how they affect the values of the computed heavy baryon observables. We also elaborate on the role of relativistic effects in the calculation of the heavy baryon Isgur-Wise function.

hep-ph↗
arXiv1998

One-Pion Charm Baryon Transitions in a Relativistic Three-Quark Model

We study one-pion transitions between charm baryon states in the framework of a relativistic three-quark model. We calculate the charm baryon-pion coupling factors that govern the S-wave, P-wave and D-wave one-pion transitions from the s-wave and the lowest lying p-wave charm baryon states down to the s-wave charm baryon states. For these we obtain: g_{Σ_cΛ_cπ}=8.88 GeV^{-1}, f_{Λ_{c1}Σ_cπ}=0.52 and f_{Λ_{c1}^*Σ_cπ}=21.5 GeV^{-2}. We compare our rate predictions for the one-pion transitions with experimental results.

hep-ph↗
arXiv1998

Exclusive nonleptonic bottom to charm baryon decays including nonfactorizable contributions

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.

hep-ph↗
arXiv1998

Exclusive Nonleptonic Decays of Bottom and Charm Baryons in a Relativistic Three-Quark Model: Evaluation of Nonfactorizing Diagrams

Exclusive nonleptonic decays of bottom and charm baryons are studied within a relativistic three-quark model with a Gaussian shape for the momentum dependence of the baryon-three-quark vertex. We include factorizing as well as nonfactorizing contributions to the decay amplitudes. For heavy-to-light transitions Q -> q u d the total contribution of the nonfactorizing diagrams amount up to approximately 60% of the factorizing contributions in amplitude, and up to approximately 30% for b -> c u d transitions. We calculate the rates and the polarization asymmetry parameters for various nonleptonic decays and compare them to existing data and to the results of other model calculations.

hep-ph↗
arXiv1997

Weak Decays of Heavy Baryons in the Covariant Quasipotential Approach

Bethe-Salpeter approach has been applied to the study of b --> c transitions both for heavy mesons and heavy baryons. Meson and baryon IW functions are calculated on the equal footing. A reasonable agreement with the experimental data for heavy to heavy semileptonic transitions has been obtained.

hep-ph↗
arXiv1996

Heavy Baryon Transitions in a Relativistic Three-Quark Model

Exclusive semileptonic decays of bottom and charm baryons are considered within a relativistic three-quark model with a Gaussian shape for the baryon-three-quark vertex and standard quark propagators. We calculate the baryonic Isgur-Wise functions, decay rates and asymmetry parameters.

hep-ph↗
arXiv1994

On the 1/m^2 corrections to the form-factors in /\_b -> /\_c semileptonic decays

Model-independent bounds are presented for the form-factors describing the semileptonic decay $Λ_b\toΛ_ce\barν_e$ at the end-point of the lepton energy spectrum. For the axial-vector form-factor $f_1^A(1)$ we obtain $f_1^A(1)\leq 0.960÷0.935$, where the uncertainty arises from the value of $μ_π^2$, the average kinetic energy of the $b$ quark inside of the $Λ_b$ baryon. A bound is given on the forward matrix element of the axial current in a $Λ_b$ baryon which is relevant for the inclusive semileptonic decays of the polarized $Λ_b$ decays.

hep-ph↗
arXiv1993

Inclusive Semileptonic Decays in QCD Including Lepton Mass Effects

Starting from an Operator Product Expansion in the Heavy Quark Effective Theory up to order 1/m_b^2 we calculate the inclusive semileptonic decays of unpolarized bottom hadrons including lepton mass effects. We calculate the differential decay spectra dΓ/(dE_τ), and the total decay rate for B meson decays to final states containing a τlepton.

hep-ph↗
arXiv1993

Two Heavy Quark Effective Theories

We point out that there exist two different formulations of the Heavy Quark Effective Theory (HQET). One formulation of HQET was mostly developed at Harvard and involves the use of the equation of motion to eliminate the small components of the heavy quark field. The second formulation, developed in Mainz, involves a series of Foldy-Wouthuysen-type field transformations which diagonalizes the heavy quark Lagrangian. Starting at O($1/m_Q^2$) the two formulations are different in that their effective Lagrangians, their effective currents, and their fields differ. However, when these three differences are properly taken into account, the two alternative formulations lead to identical S-matrix elements. This is demonstrated in an explicit example at O($1/m_Q^2$). We point to an essential difficulty of the Harvard HQET in that the Harvard effective fields are not properly normalized starting at order $O(1/m_Q^2)$.

hep-ph↗
arXiv1993

On the Determination of the $b \rightarrow c$ Handedness Using Nonleptonic $Λ_c$-Decays

We consider possibilities to determine the handedness of $b \ra c$ current transitions using semileptonic baryonic $Λ_{b} \rightarrow Λ_{c}$ transitions. We propose to analyze the longitudinal polarization of the daughter baryon $Λ_c$ by using momentum-spin correlation measurements in the form of forward-backward (FB) asymmetry measures involving its nonleptonic decay products. We use an explicit form factor model to determine the longitudinal polarization of the $Λ_c$ in the semileptonic decay $Λ_b \ra Λ_c + l^- + \bar ν_l$. The mean longitudinal polarization of the $Λ_c$ is negative (positive) for left-chiral (right-chiral) $b \ra c$ current transitions. The frame dependent longitudinal polarization of the $Λ_c$ is large ($\cong 80\%$) in the $Λ_b$ rest frame and somewhat smaller (30\% - 40\%) in the lab frame when the $Λ_b$'s are produced on the $Z_0$ peak. We suggest to use nonleptonic decay modes of the $Λ_c$ to analyze its polarization and thereby to determine the chirality of the $b \ra c$ transition. Since the $Λ_b$'s produced on the $Z_0$ are expected to be polarized we discuss issues of the polarization transfer in $Λ_b \ra Λ_c$ transitions. We also investigate the $p_\perp$- and $p$-cut sensitivity of our predictions for the polarization of the $Λ_c$.

hep-ph↗
arXiv1993

Heavy Quark Effective Theory at Large Orders in $1/m$

The existing derivations of a heavy quark effective theory (HQET) are analyzed beyond the next-to-leading order in $1/m$. With one exception they are found to be incorrect. The problem is a wrong normalization of the heavy quark field in the effective theory. We argue that the correct effective theory should be given by a Foldy--Wouthuysen type field transformation to all orders in $1/m$. The renormalization of the resulting Lagrangian to order $1/m^2$ is performed allowing for inclusion of effects arising through vacuum polarization. Our results for the anomalous dimensions disagree with the existing ones. Some applications are considered.

hep-ph↗
arXiv1992

Spectral Functions for Heavy-Light Currents and Form Factor Relations in Hqet

We derive relations among form factors describing the current-induced transitions: (vacuum) $\rightarrow B,B^{*}, B π, B^{*} π, B ρ$ and $B^{*} ρ$ using heavy quark symmetry. The results are compared to corresponding form factor relations following from identities between scalar and axial vector, and pseudoscalar and vector spectral functions in the heavy quark limit.

hep-ph↗