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The [ital P]-odd and [ital CP]-odd nucleon potential for different models of [ital CP] violation in the one-meson exchange approximation is studied. It is shown that the main contribution is due to the [pi]-meson exhcange which leads to a simple one-parameter [ital CP]-odd nucleon potential.

In this paper we study the strange quark contribution to the neutron electric dipole moment and compare with other contributions in multi-Higgs doublet models. We find that the strange quark contribution is significant because the strange quark color dipole moment is larger than that of the down (up) quark by a factor >NU>m s m s ( m s m u ) . In the case of neutral Higgs it can be the dominant contribution to the neutron electric dipole moment.

We study two-body baryonic decays of pseudoscalar {ital B} mesons to charmed-baryon--antibaryon pairs, where baryons (or antibaryons) are orbital ground states in spin doublets or quartets. The four-fermion interaction theory forbids {ital F}-wave decays for spin-quartet--quartet final-state configurations. SU(6) symmetry requires that all decay amplitudes are expressed by no more than eight parameters: three for {ital S} wave, four for {ital P} wave, and one for {ital D} wave. Both {Lambda}{sub {ital c}} inclusive and some exclusive branching ratios are studied based on the assumption of two-body dominance in baryonic decays of {ital B} mesons. Results are listed in tables.

We show by examples that multichannel mixing can affect both the parameters extracted from neutrino oscillation experiments, and that more general conclusions derived by fitting the experimental data under the assumption that only two channels are involved in the mixing. Implications for MiniBooNE are noted and an example based on maximal CP violation displays profound implications for the two data sets (muon-neutrino and muon-antineutrino) of that experiment., 5 pages 4 figures

Arkani-Hamed and Schmaltz (AS) have shown that proton stability need not originate from symmetries in a high energy theory. Instead the proton decay rate is suppressed if quarks and leptons are spatially separated in a compact extra dimension. This separation may be achieved by coupling five dimensional fermions to a bulk scalar field with a non-trivial vacuum profile and requires relationships between the associated quark and lepton Yukawa couplings. We hypothesise that these relationships are the manifestation of an underlying symmetry. We further show that the AS proposal may suggest that proton stability \emph{is} the result of an underlying symmetry, though not necessarily the traditional baryon number symmetry., Comment: 4 pages, references added to match published version

We propose that there coexist two scalar mesons of different structures (a conventional meson and a four-quark meson) in the recently observed broad bumps just below the large peak of the tensor meson in the D-pi mass distribution. We base this proposal on the interpretation of the charm-strange scalar meson of mass 2317 MeV as a four-quark meson. The strange counterparts of these scalar mesons are also studied., 4 pages, 0 figures, Revtex

If the sterile neutrino mass matrix in an otherwise conventional seesaw model has a rank less than the number of flavors, it is possible to produce pseudo-Dirac neutrinos. In a two-flavor, sterile rank 1 case, we demonstrate analytic conditions for large active mixing induced by the existence of (and coupling to) the sterile neutrino components. For the three-flavor, rank 1 case, ``3+2'' scenarios with large mixing also devolve naturally as we show by numerical examples. We observe that, in this approach, small mass differences can develop naturally without any requirement that masses themselves are small. Additionally, we show that significant three channel mixing and limited experimental resolution can combine to produce extracted two channel mixing parameters at variance with the actual values., Comment: 26pp., 3 figs., revtex4; extension of hep-ph/0307245

Recent proposals to study the mass of the "electron" neutrino at a sensitivity of 0.3 eV can be used to place limits on the right handed and scalar charged currents at a level which improves on the present experimental limits. Indeed the neglect of the possibility of such interactions can lead to the inference of an incorrect value for the mass, as we illustrate., 12 pages and 3 figures. Contributed to the XX International Symposium on Lepton and Photon Interactions at High Energies, Rome, July 2001, and to the International Europhysics Conference on High Energy Physics, Budapest, July 2001. Preprint numbers added, misprints corrected

The interference of charge-changing interactions, weaker than the V-A Standard Model (SM) interaction and having a different Lorentz structure, with that SM interaction, can, in principle, produce effects near the end point of the Tritium beta decay spectrum which are of a different character from those produced by the purely kinematic effect of neutrino mass expected in the simplest extension of the SM. We show that the existence of more than one mass eigenstate can lead to interference effects at the end point that are stronger than those occurring over the entire spectrum. We discuss these effects both for the special case of Dirac neutrinos and the more general case of Majorana neutrinos and show that, for the present precision of the experiments, one formula should suffice to express the interference effects in all cases. Implications for "sterile" neutrinos are noted., 32 pages, LaTeX, 6 figures, PostScript; full discussion and changes in notation from Phys. Lett. B440 (1998) 89, nucl-th/9807057; submitted to Phys. Rev. D

The O(v(2)) relativistic correction for inelastic J/psi photoproduction, in which heavy quark pairs are in the dominant Fock state of the quarkonium, is studied in the framework of NRQCD factorization. An assessment of its significance, particularly in comparison to the color octet contributions, is made, it is found that the impact on the energy distribution is negative in certain regions of phase space. The predictions are compared with photoproduction data from DESY HERA.

We note that off the quark mass shell the operators $(p_i+p_f)_\mu\gamma_5$ and $i\sigma_{\mu\nu}(p_i -p_f)^\nu\gamma_5$, both of which reduce to $-\vec{\sigma}\cdot\vec{E}$ in the non-relativistic limit, are no longer identical. In this paper we explore the effects of this difference in the contribution of these quark electric moments to hadronic electric moments., Comment: 21 pages, 1 figure, Revtex, uses psfig

We use improved lattice actions for glue, light quarks and heavy quarks for which we use lattice NRQCD to compute hadron masses. Our results are in good agreement with experiment, except for charmed hadrons. It seems that charmed quar ks are not well approximated as heavy quarks nor as light quarks., 14 pages +6 pages figures, plain-tex file

The electric and magnetic dipole moments of the rho meson are calculated using the propagators and vertices derived from the QCD Dyson-Schwinger equations. Results obtained from using the Bethe-Salpeter amplitude studied by Chappell, Mitchell and Tandy, and Pichowsky and Lee, are compared. The rho meson EDM is generated through the inclusion of a quark electric dipole moment, which is left as a free variable. These results are compared to the perturbative results to obtain a measure of the effects of quark interactions and confinement. The two dipole moments are also calculated using the phenomenological MIT bag model to provide a further basis for comparison., 31 pages, RevTeX, 2 figures, uses psfig. Replacement of results using amplitude/propagator from paper by Mitchell et.al. with those from more recent paper by Mitchell and Tandy. Minor modification of tables 1 and 2. Explanation of proof of current conservation added. Expanded discussion of quark propagators and confinement. To be published in Phys. Rev. C

It has been shown that CP violating electron-nucleon and nucleon-nucleon interactions can induce atomic electric dipole moments and are therefore constrained from experimental data. We show that using the experimental upper bounds on neutron and electron electric dipole moments, one can also obtain constraints, in some cases better ones, on these interactions. In addition stringent constraints can also be obtained for muon-quark and tauon-quark four-fermion CP violating interactions, which cannot be constrained from atomic electric dipole moment experiments., Comment: ps-file, 12pages

A general result for the eigenenergies of the one-dimensional Dirac equation for an arbitrary array of delta-function potentials of either Lorentz scalar or vector type is developed. This result is then used to discuss a finite one-dimensional model of the nucleus from which the energy bands of the constituent quarks may be obtained. The resulting energy eigenvalues are compared with those obtained previously via a similar model based on a Klein-Gordon equation. In contrast to this alternative treatment a system consisting of massless quarks confined to a regular periodic one-dimensional nucleus is found to be unbound. In the near ultra-relativistic limit binding to first order in the mass is found, thus conforming unexpectedly with the nonrelativistic limit. The possible surface states are examined and it is found that the so-called Dirac surface states are not expected for potentials of either Lorentz character. The existence and effect of quark surface states is also discussed in terms of our nuclear model. Finally the scattering coefficients for a relativistic particle in an arbitrary array of delta-function potentials are determined and their implications with regard to quark tunneling in nuclei are discussed.

The standard resul ts of the quark model rely on nonrelativistic descriptions of the wavefunctions of the quarks in the hadron. However, simple uncertainty principle considerations show that the momenta of the quarks are comparable to their (constituent) masses, so that relativistic dynamics must be used in the description of the hadronic structure. In this paper I describe a number of new and old results which illustrate relativistic effects on the quark structure of hardons, and which employ the method of light cone quantisation to handle relativity.

The spectator model of charmed-particle decays has failed to reproduce the two-body decay data. Soft-pion/kaon arguments have led to the belief that it is equally condemned to fail for three-body decays. However, avoiding soft-pion/kaon analyses we are led to a pole model of three-body decay which is in good agreement with the branching-ratio data, and the observed $\frac{\ensuremath{\tau}({D}^{+})}{\ensuremath{\tau}({D}^{0})}$ ratio.

The status of three-body forces in nuclear physics within the context of the trinucleon system is reviewed. The theoretical approaches of the Hannover. Brazilian, Tuscon-Melbourne, and Urbana-argonne groups to modeling the three-nucleon force are outlined and compared. Results of numerical calculations based upon contemporaryNN forces alone plus those utilizing these three-body interactions are summarized for various bound-state observables and the Fourier transform of the charge density (the charge form factor in the impulse approximation) as well as selected continuum observables. Uncertainties in our experimental knowledge of theNN force, which significantly affect conclusions about the size of nuclear three-body force effects. are discussed.

We compute the electric dipole moment of the neutron in the standard KM model, including the meson-baryon intermediate states which dominate the result in the SU(3) × SU(3) chiral limit, and find 1.4×10−31 e cm⩾|Dn|⩾9.9×10−33 e cm.

A phenomenological analysis of recent experiments on parity non-conservation in the low energy nucleon-nucleon system suggests that the Δ S = 0 non-leptonic weak interaction contains a large isotensor component. Further experiments to clarify the situation are suggested.

We have calculated the ratio of the rate for nonmesonic decay of the $\ensuremath{\Lambda}$ in nuclear matter to that of the free $\ensuremath{\Lambda}$ decay rate using a pion and rho meson exchange model. Including tensor force effects and a final-state correlation function generated from the Reid-soft-core potential, we estimate $\frac{{\ensuremath{\Gamma}}_{\mathrm{nm}}}{{\ensuremath{\Gamma}}_{\mathrm{free}}}$ to be of order 1. A discrepancy with respect to the prior estimate of Adams is resolved.

The dependence of the invariant amplitudes for electroproduction of off-mass-shell pions on the pion Born term is investigated when current-algebra Ward identities and PCAC (partial conservation of axial-vector current) are used to determine pion electroproduction invariant amplitudes. We show that an amplitude satisfying the Ward identities can be constructed starting from the usual Born terms which do not satisfy them and that this same amplitude will be obtained for a large class of input Born terms.

The current algebra program of the ππ exchange three-body force (TBF) is extended to include ϱ- and π-meson exchange. A qualitative discussion is given of the origin of the potentials which are constrained by the low-energy theorems of Thirring, Beg, and Kroll and Ruderman and supplemented by Δ-isobar contributions. The leading local parts of the ϱϱ and ϱπ TBF's are presented and used to estimate the binding energy of nuclear matter. The contributions are ππ TBF ∼- −4 MeV , ϱπ TBF ∼- +2 MeV , ϱϱ TBF ∼- − 1 4 MeV . The relative contributions from model-independent low-energy theorems and from the Δ-isobar to the ϱπ and ρρ potentials are discussed. In contrast to the ππ exchange TBF which is dominated by the model-independent part, the ϱπ and pp potentials have substantial contributions from an explicit Δ-isobar. The convergence of the nuclear matter estimates with respect to exchanged meson mass indicates that future calculations should not be concerned with heavier meson exchanges. The form factors used in the estimates with these potentials are collected in an appendix.

We derive the complete three-nucleon potential of the two-pion-exchange type, suitable for nuclear structure calculations, by extending away from the forward direction the subthreshold off-pion-mass-shell πN scattering amplitude of Coon, Scadron and Barrett. The off-mass-shell extrapolation, subject to current algebra and PCAC constraints, yields approximately model independent amplitudes (in that they depend primarily on πN data) in the complete potential. The subtraction of the forward propagating nucleon term from the amplitudes is done in greater generality than before. The contribution of this three-nucleon potential to the binding energy of symmetric nuclear matter is estimated using the perturbative formalism of McKellar and Rajaraman. In our treatment of correlations in nuclear matter, the dominant three-nucleon potential has strong components from both s-wave and p-wave πN scattering. A three-body potential based on the p-wave Δ isobar can be considered a special case of the derived potential. Therefore, we are able to trace most of the discrepancies in previously reported binding energy contributions back to the assumed energy denominator in second order. We find the contribution of the three nucleon potential to the energy of symmetric nuclear matter to be − 1.90 ± 0.2 MeV.

The one-pion-exchange contributions to the Lobashov experiment are carefully calculated and are shown to be relativistic corrections. Their contribution to the circular polarization, P γ , is 1.1 × 10 −9 A , where A measures the strength of the parity violating NNπ coupling. For A = 1 this is approximately 10% of the usual nonrelativistic result arising from heavy meson exchange.

We have calculated the parity violating observables in p-p and n-p scattering using a number of strong nucleon-nucleon potentials for a large class of weak parity violating potentials.

There are currently two major QCD-inspired quark models for hadrons. Nonrelativistic potential models and ultrarelativistic bag models have both had their successes. In this paper we present the case for an alternative quark picture, emphasizing the nonperturbative dynamical breaking of chiral symmetry in QCD. The relativistic constituent quark model which emerges recovers the main results of the other approaches, and also holds better prospects for the calculation of relativistic phenomena, and for the eventual understanding of the interrelations between chiral-symmetry breaking, hadron structure and confinement.

Caprini and Micu recently introduced a one particle nucleon-nucleus pnc potential generated by one loop corrections to nuclear field theory. I show how to obtain the conventional nucleon-nucleus pnc potential as a tree graph in nuclear field theory, and demonstrate that the one loop corrections introduced by Caprini and Micu are small corrections to the conventional pnc potential.

We show that nucleon pole terms contribute significantly to proton decay, increasing the branching ratio for e+π0 and νRπ+ modes. The total lifetime is decreased to the point where keeping the SU(5) value of the lifetime below the experimental upper bound forces us to the choice of QCD scale parameter and proton radius parameter which are near the edge of the allowed region.

We construct supersymmetric theories in which the number of generations of quarks and leptons is related by gauge anomaly cancellation to the spectrum of Higgs fields. Models yielding at least three generations with the minimal Higgs spectrum assumed are discussed in detail. This mechanism requires an extension of the standard model gauge group such that an ordinary quark-lepton generation is not anomaly-free. We discuss models of SU (3) weak isospin, separate isospin groups for quarks and leptons, and chiral colour.

We have extended the dispersion relation calculation of the π NN vertex function to include off-shell terms in the π N scattering matrix. These off-shell terms are constrained by the current algebra and PCAC results, and contribute to the N N → ππ s-wave. As such, they add to the kinematic off-shell effects which Durso, Jackson and VerWest found in the p-terms. The off-shell terms increase the calculated Goldberger-Treiman discrepancy from 0.02 to 0.03, bringing it into agreement with the field theory value of Jones and Scadron (0.035). The calculated discrepancy remains smaller than the experimental value of 0.06±0.01.

We investigate the contribution of three-body forces to the binding energy of nuclear matter, including the effects of two- and three-body correlations induced by the two-nucleon forces, and find that it may by approximated using plane-wave three-nucleon states cut off when any interparticle distance is less than about 0.9 fm. Existing calculations can then be used to estimate that three-body forces contribute about 1 MeV to the binding energy.

A new method is developed for the study of deuteron stripping reactions. The aim is to circumvent a difficulty associated with the usual DWBA approach. This is that the approximation of assuming zero internal deuteron distortion is made in a matrix element which receives its contributions from that region of configuration space within or near the initial nucleus. As this is the same region in which deuteron polarization is likely to be most important, it may be that the DWBA approach is inherently incapable of yielding accurate determinations of spectroscopic factors. In the present method the cross section is expressed in terms of a matrix element which differs in form from that usually employed, while an explicit function S (1 − S) 2 of the spectroscopic factor S emerges as a multiplying factor. It appears that this form for the cross section has the following advantages: (a) in the matrix element involved, the deuteron elastic scattering wavefunction contributes primarily in the asymptotic region of configuration space for which there is no internal deuteron distortion, while effects arising from the neutron and proton influenced differently by the core nucleus appear in terms of neutron and proton optical wavefunctions only; (b) a large part of the structure, or S , dependence of a specific reaction has been extracted in the factor S (1 − S) 2 so that the matrix element itself is less sensitive to specific structure details than the usual DWBA matrix element; (c) an evaluation of the differential cross section depends primarily on a knowledge of neutron and proton optical wavefunctions, and the results are not significantly dependent on any particular choice of optical model parameters provided these are consistent with nucleon scattering data. Differential cross sections have been calculated for six ground-state reactions covering a wide range of mass numbers; comparisons with experimental results are highly encouraging.

At least one massive neutrino, with mass greater than 1 MeV, can provide an explanation of the residual Goldberger-Treiman discrepancy (1938). Agreement with the π → eν branching ratio requires either one massive neutrino with mass between 34 and 139 MeV, or a number of massive neutrinos with appropriately chosen masses and mixing angles.

We show that, when nucleon-nucleon correlations are taken into account using correlation functions derived. from the Reid soft core potential, the contribution of three body forces to the binding energy of nuclear matter is enhanced. The two pion exchange three body forces contributes 6 MeV attraction.

In a recent letter, Nardulli et al. have derived a low energy potential representing the parity violating nucleon-nucleon interaction induced by parity non-conservation in the nucleon wavefunction. I point out that this potential is in conflict with the data on parity non-conservation in s-d shell nuclei.

The calculation of short-distance gluon exchange corrections to the ΔS = 0 weak interaction at the quark level is described. Results are given for the coefficients of the 36 independent four-quark operators involving u, d, and s quarks explicitly, and for the 16 independent operators, which remain when s quarks are eliminated and only u and d quarks explicitly occur in the operators.

The parity-nonconserving nucleon-nucleon potential is calculated from the Oakes theory of weak interactions on the assumption that $\ensuremath{\pi}$ and $\ensuremath{\rho}$ exchange terms dominate. It is found that this theory predicts a circular polarization of \ifmmode\pm\else\textpm\fi{}(1.8\ifmmode\pm\else\textpm\fi{}0.9)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$ for 482-keV $\ensuremath{\gamma}$ ray from $^{181}\mathrm{Ta}$. The observed polarization is -(0.06\ifmmode\pm\else\textpm\fi{}0.01)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$.

A calculation is made of the parity-violating contributions of hypothetical excited quarks and leptons to two examples of low-energy phenomena. In particular, the contributions to polarized-electron--deuteron scattering and the parity-violating nuclear potential are studied. The parity-violating contributions are induced by the magnetic coupling of photons or gluons with virtual excited fermions and left-handed ordinary fermions. It is concluded that the mass of an excited quark, if it exists, must be larger than approx.3 TeV. The restriction on the mass of an excited lepton is less stringent.

Publisher Summary This chapter describes the three nucleon potential in nuclear matter. It presents a calculation of the two-pion exchange three nucleon potential for use in nuclear matter calculations. The new potential is based on a scattering amplitude, which was constructed to satisfy the constraints imposed by current algebra and the most scattering data. There is a significant s wave πN amplitude, although the well-known cancellation at the Adler point was imposed. A potential in nuclear matter where one will eventually average over the spins and isospins of the nucleons in computing the energy was constructed. The chapter presents the resulting amplitude in the rest frame of the incident nucleon. The background term F -(+) is required to satisfy the current algebra constraints when one pion is soft and the other is on the mass shell and when both pions are soft. This enables the determination of the coefficients in the expansion.

Publisher Summary This chapter discusses the different aspects of three-body forces in nuclei. There is a clear discrepancy of about 1 MeV between the calculated and observed binding energy of the triton. It seems impossible to move the binding energy curve of nuclear matter or finite nuclei away from the Coester Line. Almost as soon as the meson theory of nuclear forces was proposed, attempts were made to calculate three nucleon potentials arising from multiple pion exchange. There is a possible empirical need for many-body forces of weaker strength exchanged pions. As the three-body force does not open any new channels, the introduction of additional Lovelace type amplitudes is an unnecessary complication. The equation is a well-defined integral equation for three-body matrix, which can serve as the basis of a systematic perturbation expansion.

The difficulties in computing the parity violating nucleon‐nucleon interaction from an underlying weak interaction theory are reviewed, and the extent to which the parameters of the interaction can be determined by the available data is discussed. A possible experiment in 21Ne which can provide useful constraints on the parameters is outlined.

Large-basis meson wave functions, built from static cavity quarks and gluons, are used in conjunction with a simple plane-wave projection prescription to calculate meson charge radii with /ital O/(/ital g//sup 2/) corrections. After fitting to the light-meson mass spectrum the pion charge radius is used to constrain the remaining degree of freedom of the model parameters. The resulting large-basis model is found to give the following mass predictions in the light-quark sector: /ital K//sup */(892)=904.4/plus minus/0.1 MeV, /phi/(1020)=1040.6/plus minus/0.1 MeV. For the kaon charge radius we obtain /l angle//ital r//sup 2//r angle//sub K/=0.35/plus minus/0.040 fm/sup 2/ (/l angle//ital r//sup 2//r angle//sub K//sup expt/=0.34/plus minus/0.05 fm/sup 2/).

The weak parity — violating nucleon — nucleon potential may be regarded as a meson exchange potential arising from the reactions $${\rm{N\bar N}}\,\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{{\rm{P}}{\rm{.v}}{\rm{.}}}^{{\rm{weak}}}} \,{\rm{mesons}}\,\left( {\pi ,\rho ,2\pi ,{\rm{etc}}.} \right)\,\buildrel {{\rm{strong}}} \over \longrightarrow \,{\rm{N\bar N}}$$ The main problem in calculating the single meson exchange terms is in the calculation of the weak meson — nucleon vertex. For 2π exchange the strong amplitude is no longer trivial, introducing additional complications. I now wish to discuss the π, ρ, and 2π potentials in turn.

The one pion exchange contribution to the weak parity violating nucleon-nucleon potential is calculated by relating the weak NNπ vertex to the nonleptonic hyperon decays by the Suzuki-Sugarawa method. It is also shown that the G parity odd part of the weak Hamiltonian cannot contribute to the potential.

Recent hints in experimental data of a fJ.1T resonance at 429 MeV have led us to speculate about the possibility of meson-lepton and dilepton resonances. We show that the proposed fJ.7T resonance at 429 MeV is not in conflict with the muon g-2 measurements, and that it could be interpreted as a partner of the excited charged leptons possibly seen at CERN. Moreover, a composite model by Fritzsch and Mandelbaum predicts not only a flavour octet of meson-muon resonances of which this could be one, but also dilepton resonances which were suggested by Ramm as an explanation of the lobe structure in the fJ.7T data. The observed widths and branching ratios of the resonances can be interpreted to suggest that the colour-octet states are considerably smaller than the colour singlets.

We show that nuclear physics provides evidence against the existence of hadronic Van der Waals forces between nucleons.

Large-basis O(g) static cavity wavefunctions, containing bremsstrahlung and quark-sea states, previously fitted to the light quark meson sector, are applied to the ground-state meson spectrum in general. The only parameters of the model in the heavy quark sector are the quark masses me and mb which we fit to D and B states. Predictions for the meson mass spectrum are given and are found to be a significant improvement over the predictions of the original. MIT model.

We utilise the light-front dynamical formalism to compute the magnetic moments of baryons in a relativistic constituent quark model, investigating the dependence of the results on the mass of the constituent quarks and on the size of the hadron.