Harry J. Lipkin

The Potential Model of Colored Quarks: Success for Single Hadron States, Failure for Hadron - Hadron Interactions

Abstract The success of the additive potential model of colored quarks for the masses, decay rates, and other properties of single mesons and baryons does not imply that this model can yield the observed meson-nucleon and nucleon-nucleon interactions. We give a comprehensive discussion of this issue. In agreement with previous authors, we conclude that, on the contrary, this model predicts inverse-power color-analog van der Waals potentials between separated hadrons which are in substantial contradiction with experimental data. We also discuss pathologies of non-abelian confining potentials, and show that the hamiltonian is unbounded below for an arbitrary number of quarks and antiquarks in a definite color state for all color states, except the singlet, triplet, and antitriplet.

Is observed direct CP violation in Bd→K+π− due to new physics? Check standard model prediction of equal violation in Bs→K−π+

Abstract The recently observed direct CP violation in B d → K + π − has raised suggestions of possible new physics. A robust test of the standard model vs. new physics is its prediction of equal direct CP violation in B s → K − π + decay. CPT invariance requires the observed CP violation to arise from the interference between the dominant penguin amplitude and another amplitude with a different weak phase and a different strong phase. The penguin contribution to B d → K + π − is known to be reduced by a CKM factor in B s → K − π + . Thus the two branching ratios are very different and a different CP violation is expected. But in the standard model a miracle occurs and the interfering tree diagram is enhanced by the same CKM factor that reduces the penguin to give the predicted equality. This miracle is not expected in new physics; thus a search for and measurement of the predicted CP violation in B s → K − π + decay is a sensitive test for a new physics contribution. A detailed analysis shows this prediction to be robust and insensitive to symmetry breaking effects and possible additional contributions.

A phenomenological model for pseudoscalar meson mixing

Abstract Conventional models of η-η′ mixing are extended to include radial excitations in the mass matrix. The number of free parameters is minimized by using the Quigg-Rosner logarithmic potential to obtain properties of radially excited states. The remaining parameters are fixed by fitting observed masses. The wave functions obtained by diagonalizing the mass matrix give an η similar to the conventional description, 99% ground state and mainly octet but a very different η′ with a 50% admixture of radial excitations, and the s s configuration dominant in the ground-state component. This η′ wave function modifies the bad quark-model predictions for peripheral production by introducting form factors which lead to new predictions in agreement with experiment. Additional isoscalar pseudoscalar states are predicted around 1280 and 1500 MeV. Applications to radiative vector meson decays and charmonium are also discussed.

Experimental tests and implications of the Zweig-Iizuka rule

Abstract Experimental test of relative strengths of ZI-violating and ZI-conserving transitions are proposed with the aim of obtaining a phenomenological description which can predict strengths of forbidden transitions. Models in which relative strengths are experssed in terms of parameters analogous to Cabibbo angles are discussed. Rho-omega and f-f′-A 2 interference experiments are proposed as a sensitive test of the ZI rule. Arguments that the ZI rule requires φ production in NN collisions to be stronger with kaon pairs than without are shown to be invalid and similarly for arguments requiring charmed pair production together with J particles.

A useful approximate isospin equality for charmless strange B decays.

Abstract A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a Δ I =0 transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other amplitudes are included but the direct contributions which are quadratic are neglected.

Flavor Symmetry, Emc Results and the Spin Content of the Proton

Abstract The analysis of the EMC result on the quark contribution to the spin of the proton has caused considerable confusion and is unnecessarily complicated because of the completely unjustified and incorrect use of SU(3) flavor symmetry to provide input on the proton wave function from hyperon decays. There is no reliable method for obtaining information on the proton spin structure from data on the couplings of currents to hyperons. Interesting peculiar results obtained without use of SU(3) and hyperon data show the crucial point to be the apparent contradiction between the contribution of valence u quarks to the proton spin observed in the axial vector contribution to nucleon beta decay and the failure of this contribution to appear in the conventional quark-parton interpretation of the EMC results. When input from hyperon data is not used this paradox can be resolved without requiring the quark contribution to the proton spin to be near zero, but it can be large only if it is due to the strange quarks, with the nonstrange quark contribution opposite to the spin of the proton.

Why masses and magnetic moments satisfy naive quark model predictions

Abstract Relativistic and zero point energy corrections are shown to be absorbed in renormalizing phenomenological quark mass parameters appearing in quark model descriptions of baryon and meson masses and baryon and magnetic moments and do not affect successful relations. Analysis of small differences between effective quark masses in mesons and baryons gives two new successful relations between meson and baryon masses.

A model-independent approach to multiquark bound states☆

Abstract Difficulties in extending quark models successful for hadron structure to multiquark systems are analyzed. A variational approached is developed which successfully predicts meson masses with baryon masses as input and gives nearly model-independent estimates of four-quark masses by using trial wave functions whose interaction energies are approximately given by known hadron masses; e.g. a (ccud) wave function whose dependence on the cc relative coordinate is given by the exact wave function of the J/ψ and whose dependence on the relative coordinates of the u and d relative to the center-of-mass of the cc system is given by the exact wave function of the Λ c . Four-quark states containing two identical heavy quarks are shown to have a good probability of being stable against strong decays.

Interference effects in Kη and Kη′ decay modes of heavy mesons. Clues to understanding weak transitions and CP violation

Abstract Interference between amplitudes producing η and η′ mesons via their strange and nonstrange components give relative suppression factors of an order of magnitude in certain diagrams and can be used to identify penguin contributions to B→Kη and B→Kη′ decays as well as annihilation diagram contributions to corresponding D decays. Similar suppression factors also arise in D 0 →π 0 η and D 0 →π 0 η′ decays and in charmonium decays to K + K − η and K + K − η′.

STRANGENESS ANALOG RESONANCES.

Strangeness analog resonances in hypernuclei are defined by analogy to the well-known isobaric resonances. Their relationship to the Sakata SU(3) model is discussed. Estimates are made for their energies and total widths. It is suggested that the excited states of ΛC12 and ΛN14 seen in stopped Kaon experiments are examples.