Frederick J. Gilman

Helicity conservation in diffraction scattering

Abstract We discuss the possibility that diffraction scattering of hadrons conserves the s-channel helicities of the particles involved. Presently available experimental data is examined and shown to support conservation of s-channel helicity, and not the hypothesis of no helicity flip in the t-channel. Further tests are suggested and restrictions imposed on various models of diffraction scattering in particular, t-channel exchange models, are discussed.

The ΔI = 12 rule and violation of CP in the six-quark model☆

Abstract The consequences for K0 decay of the six-quark model with its natural possibility of incorporating a CP violating phase, δ, are investigated when a particular mechanism to give the ΔI = 1 2 rule is operative. The most important result is that the CP violation parameter ϵ′ is much larger than in previous analyses, and hence the theory has predictions for K0 → ππ decay which are experimentally distinguishable from those of the superweak model.

K0−K¯0mixing in the six-quark model

Using the leading-logarithm approximation, strong-interaction corrections to K/sup 0/-K-bar/sup 0/ mixing in the six-quark model are computed in quantum chromodynamics. The full calculation involving the mixing of eight operators at some stages is done, as well as an approximate, much simpler calculation. Numerically, the exact and approximate results agree to high accuracy and both show that the corrections to the real and imaginary parts can be large. How to obtain the free-quark limit of these and other results is shown explicitly.

Improved Bounds on Some Weak Amplitudes from the B Lifetime

Abstract We use recent information on the b lifetime to improve bounds on short-distance contributions arising from the t quark to various weak amplitudes. In particular, our previous lower bound on ϵ ′/ ϵ is substantially increased, while the upper bound on K → π ν is reduced.

Strong interaction corrections to K0-K0 mixing in the six quark model☆

Abstract Strong interaction corrections to K 0 K 0 mixing in the six quark model are computed in quantum chromodynamics using the leading logarithm approximation. The corrections to the real and imaginary parts of the off-diagonal K 0 - K 0 mass matrix elements can be large.

A lower bound on

Abstract In the Kobayashi-Maskawa (K-M) model, a lower bound on the CP violating product s 2 c 2 s 3 s δ follows from the imaginary part of the short-distance K 0 - K 0 mixing amplitude together with a conservative upper bound on the short-distance contribution to K L → μμ . This leads to a lower bound on |e′ e| in terms of a matrix element of a single (V−A)×(V+A) type operator. Familiar current alg bag model estimates for this matrix element give |e′ e| > 2×10 −3 . We also observe that the experimental upper bound on the branching ratio for the b-quark into u-quarks fixes the sign of s 2 c 2 s 3 s δ and e′ e both to be positive. Allowances for QCD corrections and long distance effects are included throughout our analysis.

CP violation in the KL→π0ℓ+ℓ− decay amplitude for large mt☆

Abstract We discuss CP violation in the amplitude for K L → π 0 l + l − when m t is large. Unlike the case of K L → ππ , CP violation in the decay amplitude itself is comparable to that which comes from the mass matrix. We study the CP violating effects, including strong interaction (QCD) corrections to the amplitudes which arise from one-loop diagrams. Short-distance contributions from diagrams that involve a W and Z or two Ws as well from those with a photon and a W are important when m t ⪆M W .

Helicity structure of nucleon resonance electroproduction and the symmetric quark model

Abstract The symmetric quark model with harmonic forces is shown to lead to a rapid change with q2 of the helicity structure for electroproduction of the second (D13) and third (F15) nucleon resonances. Preliminary results of coincidence measurements of pi-zero electroproduction in the resonance region are found to disagree with this prediction. Some further experimental tests and theoretical consequences of this failure are discussed.

Bounds on charged higgs properties from CP violation

Abstract We examine bounds from CP violation in the neutral K system on charged Higgs masses and couplings in models with two Higgs doublets. While CP violation is still due only to a non-zero phase in the Kobayashi-Maskawa matrix, there are additional short-distance contributions involving charged Higgs exchange rather than W exchange. By having CP violation in the mass matrix, but not in K → ππ decay amplitude, largely due to Higgs exchange, it is possible to obtain a small value of ϵ ′/ ϵ .

Some comments on the states between the ψ and ψ

Abstract A spin-parity assignment is made for the four even charge conjugation states now probably observed between the ψ and ψ ′. Consequences for the model of the new mesons as bound states of a new heavy quark and its corresponding antiquark are then commented upon.