We have studied the three quark system in a relativized version of the quark potential model with chromodynamics. With parameters consistent with those of an analogous study of meson spectroscopy we obtain a successful description of the spectrum of baryons. The model naturally explains the apparent absence of spin‐orbit interactions in baryons.

Baryons in a relativized quark model with chromodynamics

This article reports world averages of measurements of b-hadron, c-hadron, and tau-lepton properties obtained by the Heavy Flavor Averaging Group (HFAG) using results available through the end of 2011. In some cases results available in the early part of 2012 are included. For the averaging, common input parameters used in the various analyses are adjusted (rescaled) to common values, and known correlations are taken into account. The averages include branching fractions, lifetimes, neutral meson mixing parameters, CP violation parameters, parameters of semileptonic decays and CKM matrix elements.

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Averages of b-hadron, c-hadron, and tau-lepton properties as of early 2012

http://cds.cern.ch/record/257993/files/9401310.pdf

QCD phenomenology based on a chiral effective Lagrangian

We update the profile of the CKM matrix. The apex (rhobar,etabar) of the Unitarity Triangle is given by means of a global fit. We propose to include therein sin2alpha from the CP-violating asymmetries in B0->rho+rho-, using isospin to discriminate the penguin contribution. The constraint from epsilon'/epsilon is briefly discussed. We study the impact from the measurement of the rare decay K+->pi+nunu-bar, and from a future observation of KL->pi0nunubar. The B system is investigated in detail, beginning with 2beta+gamma and gamma from B0->D(*)+-pi-+ and B+->D(*)0K+. A significant part of this paper is dedicated to B decays into pipi, Kpi, rhopi and rhorho. Various phenomenological and theoretical approaches are studied. Within QCD Factorization we find a remarkable agreement of the pipi and Kpi data with the other UT constraints. A fit of QCD FA to all pipi and Kpi data leads to precise predictions of the related observables. We analyze separately the B->Kpi decays, and in particular the impact of electroweak penguins in response to recent phenomenological discussions. We do not observe any unambiguous sign of New Physics, whereas there is some evidence for potentially large rescattering effects. Finally we use a model-independent description of a large class of New Physics effects in both BBbar mixing and B decays, namely in the b->d and b->s gluonic penguin amplitudes, to perform a new numerical analysis. Significant non-standard corrections cannot be excluded yet, however standard solutions are favored in most cases.

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CP Violation and the CKM Matrix : Assessing the Impact of the Asymmetric B Factories

QCD factorization for exclusive non-leptonic B-meson decays: General arguments and the case of heavy-light final states

We argue that the large energy effective theory (LEET), originally proposed by Dugan and Grinstein, is applicable to exclusive semileptonic, radiative, and rare heavy-to-light transitions in the region where the energy release E is large compared to the strong interaction scale and to the mass of the final hadron, i.e., for ${q}^{2}$ not close to the zero-recoil point. We derive the effective Lagrangian from the QCD one, and show that in the limit of heavy mass M for the initial hadron and large energy E for the final one, the heavy and light quark fields behave as two-component spinors. Neglecting QCD short-distance corrections, this implies that there are only three form factors describing all the pseudoscalar to pseudoscalar or vector weak current matrix elements. We argue that the dependence of these form factors with respect to M and E should be factorizable, the M dependence $(\sqrt{M})$ being derived from the usual heavy quark expansion while the E dependence is controlled by the behavior of the light-cone distribution amplitude near the end point $u\ensuremath{\sim}1.$ The usual expectation of the $\ensuremath{\sim}(1\ensuremath{-}u)$ behavior leads to a ${1/E}^{2}$ scaling law, that is a dipole form in ${q}^{2}.$ We also show explicitly that in the appropriate limit the light-cone sum rule method satisfies our general relations as well as the scaling laws in M and E of the form factors, and obtain very compact and simple expressions for the latter. Finally we note that this formalism gives theoretical support to the quark model-inspired methods existing in the literature.

Heavy-to-light form factors in the final hadron large energy limit of QCD

We make an extensive comparison of the naive quark-pair-creation model of strong-interaction vertices for $\ensuremath{\pi}N\ensuremath{\rightarrow}{N}^{*}\ensuremath{\rightarrow}\ensuremath{\Delta}\ensuremath{\pi}$,$\ensuremath{\rho}N$,$\ensuremath{\sigma}N\ensuremath{\rightarrow}\ensuremath{\pi}\ensuremath{\pi}N$ with recent experimental results. The model describes any vertex in terms of a quark-pair creation in the $^{3}P_{0}$ state and a rearrangement leading to final states. The hadron states are given by SU(6) harmonic-oscillator wave functions. We show that the model correctly describes, without any additional assumption, the centrifugal barrier effect and also the "anti-${\mathrm{SU}(6)}_{W}$" coupling signs, features that are present in most reactions (with the important exception of $F{P}_{15}\ensuremath{\rightarrow}\ensuremath{\Delta}\ensuremath{\pi}$ for the second feature) and are included phenomenologically in the works of Rosner et al. Both facts are related to the presence, in the limit of elementary meson emission, of recoil terms depending on internal quark momenta. Contrary to other works, the model predicts the relative coupling signs for all the two-body baryonic decays leading to $\ensuremath{\pi}\ensuremath{\pi}N$. Concerning $\ensuremath{\Delta}\ensuremath{\pi}$ and $\ensuremath{\rho}N$ channels, among 18 predictions, 15 agree with experiment, comparing our results to the last report of the Particle Data Group, and three disagree. One of these three is the very serious failure $F{P}_{15}\ensuremath{\rightarrow}\ensuremath{\Delta}\ensuremath{\pi}$, which is among the best determined experimental coupling signs. We compare our predictions with parallel works. Unlike the model of Feynman, Kislinger, and Ravndal, in the limit of elementary $\ensuremath{\rho}$ emission, our model presents a recoil term in the spin part of the interaction, $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\sigma}}(i)\ifmmode\cdot\else\textperiodcentered\fi{}[({\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}}_{\ensuremath{\rho}}\ensuremath{-}{\stackrel{\ensuremath{\rightarrow}}{\mathrm{k}}}_{i})\ifmmode\times\else\texttimes\fi{}{\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\epsilon}}}_{\ensuremath{\rho}}]$. Thus, for $F{P}_{35}\ensuremath{\rightarrow}N{\ensuremath{\rho}}_{3}$, our model predicts an "anti-${\mathrm{SU}(6)}_{W}$" sign, in agreement with experiment and contrary to the prediction of Moorhouse and Parsons. For the controversial $\ensuremath{\sigma}$ production, the model is contradicted by experiment; we show, however, that the model could be compatible with experiment if the $I=0$, ${J}^{P}={0}^{+}$ dipion observed is not really a resonance.

Resonant Partial Wave Amplitudes in pi + n --> pi + pi + n According to the Naive Quark Pair Creation Model

Using the Bogoliubov-Valatin variational method, we show that the chiral-invariant vacuum is unstable for a color, fourth-component vector powerlike potential rsup..cap alpha.. (0 ..0, but breaks down for ..cap alpha..> or =3 (number of spatial dimensions) due to severe infrared singularities. If the confining potential possesses a spin-spin piece, there are critical values of its strength, depending on the power ..cap alpha.., beyond which the stability of the chiral-invariant vacuum is restored. In the case of the harmonic oscillator ..cap alpha.. = 2, the gap equation reduces to a nonlinear second-order differential equation. We find (besides the usual chiral degeneracy) an infinite number of solutions breaking chiral symmetry, higher in energy as the number of their nodes increases. We compute the expectation value of psi-barpsi and the mass gapmore » for the new vacuum, the lowest solution in energy. The infrared singularity of the massless fermion self-energy is removed for the stable broken solution.« less

Spontaneous Breaking of Chiral Symmetry for Confining Potentials

We study the hadronic decay of q$\bar q$g hybrid mesons. To that aim we establish the connection between the diatomic-molecule like wave functions and the standard q$\bar q$g wave functions. We show that inSU(6) approximation TE hybrids cannot decay intoPP, PV, VV channels while TM hybrids are weakly coupled to ψγ. Hence only TE-TM mixed hybrids are easy to see in ψ → γX. We show that hydrids are weakly mixed with quarkonia. We discuss the possible nature of the ξ(2.2) resonance and the ways of detecting exotic 1−+ q$\bar q$g bound states.

q $$\bar q$$ g Hybrid mesons in ψ → γ+hadrons

Once chosen the dynamics in one frame, the rest frame in this paper, the Bakamjian-Thomas method allows one to define relativistic quark models in any frame. These models have been shown to provide, in the infinite quark mass limit, fully covariant current form factors as matrix elements of the quark current operator. In this paper we use the rest frame dynamics fitted from the meson spectrum by various authors, already shown to provide a reasonable value for ${\ensuremath{\rho}}^{2}.$ From the general formulas for the scaling invariant form factors ${\ensuremath{\xi}}^{(n)}(w),$ ${\ensuremath{\tau}}_{1/2}^{(n)}(w),$ and ${\ensuremath{\tau}}_{3/2}^{(n)}(w),$ we predict quantitavely the $B$ semileptonic branching ratios to the ground state and orbitally excited charmed mesons $D,$ ${D}^{*},$ and ${D}^{**}.$ We check Bjorken's sum rule and discuss the respective contributions to it. We find $\ensuremath{\xi}(w)\ensuremath{\simeq}[2/(1+w){]}^{2},$ resulting from the fact that the ground state wave function is Coulomb-like. We also find ${\ensuremath{\tau}}_{3/2}\ensuremath{\simeq}0.5[2/(1+w){]}^{3}$ and ${\ensuremath{\tau}}_{1/2}(w)\ensuremath{\ll}{\ensuremath{\tau}}_{3/2}(w).$ Very small branching ratios into $j=1/2$ orbitally excited $D$'s results. The overall agreement with experiment is rather good within the present accuracy which is poor for the orbitally excited charmed mesons. We predict a ratio $B(B\ensuremath{\rightarrow}{D}_{2}^{*}l\ensuremath{\nu})/B(B\ensuremath{\rightarrow}{D}_{1}l\ensuremath{\nu})=1.55\ifmmode\pm\else\textpm\fi{}0.15$ as a mere consequence of the heavy quark symmetry. If some faint experimental indications that $B(B\ensuremath{\rightarrow}{D}_{1}l\ensuremath{\nu})\ensuremath{\simeq}B(B\ensuremath{\rightarrow}{D}_{2}^{*}l\ensuremath{\nu})$ were confirmed, it would indicate a sizable ${O(1/m}_{c})$ correction.

Quantitative predictions for B semileptonic decays into D , D * , and the orbitally excited D * * in quark models in the manner of Bakamjian and Thomas

J.-C. Raynal

Papers

Heavy-to-light form factors in the final hadron large energy limit of QCD

Resonant Partial Wave Amplitudes in pi + n --> pi + pi + n According to the Naive Quark Pair Creation Model

Spontaneous Breaking of Chiral Symmetry for Confining Potentials

q $$\bar q$$ g Hybrid mesons in ψ → γ+hadrons

Quantitative predictions for B semileptonic decays into D , D * , and the orbitally excited D * * in quark models in the manner of Bakamjian and Thomas