Showing papers on "Elementary particle published in 1980"
TL;DR: In this article, it was shown that in all theories with a Lorentz-covariant energy-momentum tensor, such as all known renormalizable quantum field theories, composite as well as elementary massless particles with j > 1 are forbidden.
562 citations
TL;DR: In this article, the sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed, and the effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs boson mass divided by the W mass.
Abstract: The sensitivity of present-energy weak interactions to a strongly interacting heavy-Higgs-boson sector is discussed. The gauged nonlinear sigma model, which is the limit of the linear model as the Higgs-boson mass goes to infinity, is used to organize and catalogue all possible heavy-Higgs-boson effects. As long as the SU(2)/sub L/ x SU(2)/sub R/ symmetry of the Higgs sector is preserved, these effects are found to be small, of the order of the square of the gauge coupling times logarithms (but not powers) of the Higgs-boson mass divided by the W mass. We work in the context of a simplified model with gauge group SU(2)/sub L/; the extension to SU(2)/sub L/ x U(1) is briefly discussed.
346 citations
TL;DR: An Introduction to Quarks and Partons by F.E. Close as discussed by the authors is a good starting point for a discussion of the relationship between quarks and partons in the context of physics.
Abstract: An Introduction to Quarks and Partons. By F.E. Close. Pp.481. (Academic: London, New York and San Francisco, 1979.) £26.40; $54.50.
261 citations
TL;DR: The SU(3) \ifmmode\times\else\texttimes\fi{} U(1) gauge symmetries are used to analyze the properties of various possible baryon and lepton-nonconserving effective interactions among ordinary particles as discussed by the authors.
Abstract: The SU(3) \ifmmode\times\else\texttimes\fi{} SU(2) \ifmmode\times\else\texttimes\fi{} U(1) gauge symmetries are used to analyze the properties of various possible baryon- and lepton-nonconserving effective interactions among ordinary particles. A multiplicative quantum number is introduced as an aid in this analysis. Estimates are given of the masses of the exotic particles that could produce these effective interactions at observable levels. Cosmological and other considerations suggest that the effective interactions of exotic particles of any mass below ${10}^{14}$ GeV should conserve some linear combination $B+aL$ of baryon and lepton number.
236 citations
TL;DR: Weinberg's Nobel lecture is reprinted in this paper, where the author emphasizes the importance of symmetry breaking and quantum field theory renormalization techniques, and the author concludes that symmetry breaking is essential for quantum field theories.
Abstract: Weinberg's Nobel lecture is reprinted. The author emphasizes the importance of symmetry breaking and quantum field theory renormalization techniques. (AIP)
137 citations
TL;DR: In this article, a potential model based on quantum-chromodynamics (QCD) considerations is developed, which attempts to overcome the relativistic limitations associated with earlier models by introducing an effective size for quarks.
Abstract: A potential model based on quantum-chromodynamics (QCD) considerations is developed. The model attempts to overcome the relativistic limitations associated with earlier models by introducing an effective size for quarks. Application of the model Hamiltonian to both light and heavy mesons yields an accurate description of the mass spectrum, radiative transitions, and annihilation widths for a large number of known mesons. Spin-dependent interactions are treated nonperturbatively using standard diagonalization procedures with an oscillator basis set and relativistic kinematics are adopted throughout. The scaling of the potential parameters is found to be similar to simple QCD predictions. Much of the anomalous behavior for pseudoscalar mesons appears to be resolved both for light and heavy mesons.
110 citations
TL;DR: In this article, the propagation of particles in simple models of the first two types of bubble units, CP2, S2 × S2 and K3, is investigated. But the results suggest that there is no inconsistency between the spacetime foam picture and everyday observations from which spacetime appears nearly flat, because all the elementary particles have spin 1 2 or greater.
104 citations
TL;DR: In this article, the dynamics of classical spinning particles are studied from the point of view of gauge supersymmetry, which is accomplished by describing the spin degrees of freedom by means of odd Grassman algebra elements and relying on Dirac's theory of constrained Hamiltonian systems.
Abstract: The dynamics of classical spinning particles is studied from the point of view of gauge supersymmetry. The central idea is that the natural way of introducing intrinsic spin degrees of freedom into a physical system is to take the square root of the Hamiltonian generators of the system without spin, which is equivalent to rendering the system gauge supersymmetric. This is accomplished by describing the spin degrees of freedom by means of ’’anticommuting c‐numbers’’ (odd Grassman algebra elements) and relying on Dirac’s theory of constrained Hamiltonian systems. The requirement of gauge supersymmetry fixes completely the action principle and leaves neither room nor need for a d h o c subsidiary conditions on the relative direction of the spin and the velocity as in the more traditional treatments. Both massive and massless particles free and in interaction with electromagnetic and gravitational fields are discussed. It is found that there exists a supergauge in which the spin tensor of a massive particle in a gravitational field is transported in parallel but the particle does not follow a geodesic. Massless particles on the other hand have the property of possessing a supergauge where their helicity is conserved and in which at the same time the worldline is a geodesic. Special attention is paid to the meaning and properties of the supergauge transformations. The main aspects of that discussion are applicable to more complicated systems such as supergravity. In particular phenomena such as necessity of invoking the equations of motion to close the gauge are analyzed.
103 citations
TL;DR: In this paper, the authors derived constraints on charged-Higgs-boson couplings in gauge theories of the weak and electromagnetic interactions using the experimental value of the KL-KS mass difference.
Abstract: Using the experimental value of the KL-KS mass difference, the authors derive constraints on charged-Higgs-boson couplings in gauge theories of the weak and electromagnetic interactions. These bounds severely restrict the possible magnitude of charged-Higgs-boson effects in K and D meson decays. The results are based on the observation that charged-Higgs-boson-exchange contributions to K0-K0 mixing are of order 1/MH^2 whereas the corresponding W-boson contribution is only of order mc^2/MW^4.
101 citations
TL;DR: In this paper, the spinor-subquark model of leptons and quarks is discussed in detail and the possibility that gauge bosons and Higgs scalars are also made of a subquark-antisubquark pair is discussed.
Abstract: Various subquark models so far proposed are briefly reviewed. Classifications of leptons and quarks in the models are discussed and compared. Our spinor-subquark model of leptons and quarks in which leptons and quarks are made of three subquarks of spin \textonehalf{} is discussed in detail. The possibility that gauge bosons and Higgs scalars are also made of a subquark-antisubquark pair is discussed. Exotic states of subquarks such as leptons and quarks of spin $\frac{3}{2}$, exotic fermions, and exotic bosons are predicted in our model. Subquark currents and their algebra are proposed. Two unified subquark models of strong and electroweak interactions are discussed. The one is a gauge model and the other is a model of the Nambu-Jona-Lasinio type. A subquark model of gravity and its supergrand unification is proposed. Finally, a speculation is made on "color-space correspondence."
TL;DR: Using the operator-product expansion, it was shown that perturbative quantum-chromodynamic corrections to the hadronic decay width of the Higgs boson can be calculated without encountering mass singularities as mentioned in this paper.
Abstract: Using the operator-product expansion it is shown that perturbative quantum-chromodynamic corrections to the hadronic decay width of the Higgs boson can be calculated without encountering mass singularities. The result is given in terms of the "running quark mass" of the renormalization group and calculable corrections in powers of $\frac{1}{\mathrm{ln}(\frac{{M}^{2}}{{\ensuremath{\Lambda}}^{2}})}$. The next-to-leading-order correction amounts to about 35% for the Higgs-boson mass $M=50$ GeV.
TL;DR: In this paper, the decays of Higgs-boson and t-quark masses were examined and the branching ratio for 2 gluons and qq-barg decay was shown to be sizable.
Abstract: We examine the decays of H ..-->.. 2 gluons, H ..-->.. qq-barg, and H ..-->.. ff-bar ( f=some fermion) over an extended range of Higgs-boson and t-quark masses. In particular, we show that the branching ratio for H ..-->.. 2 gluons may be sizable ( approx. 10%) without requiring the existence of superheavy quarks. We calculate the differential spherocity and thrust distributions as well as the values of and for the H ..-->.. qq-barg decay.
Book•
01 Jan 1980
TL;DR: In this paper, Meson interactions with nucleons, mesons and deuterons: three-body systems, Mesons and nuclei: multiple scattering theory, Meson scattering by nuclei, applications of multiple scattering theories; Field theory and coupled channel methods; Absorption and production of mesons; Meson interaction and nuclear structure.
Abstract: This book covers the following topics: Meson interactions with nucleons; Mesons and deuterons: three-body systems; Mesons and nuclei: multiple scattering theory; Meson scattering by nuclei: applications of multiple scattering theory; Field theory and coupled channel methods; Absorption and production of mesons; Meson interactions and nuclear structure.
TL;DR: In this article, it was shown that the nonrelativistic approximation for the lighter hadrons with the conventional one-gluon exchnage potential breaks down due to the Coulomb and the short-range hyperfine interactions.
Abstract: This Letter demonstrates that the nonrelativistic approximation breaks down for the lighter hadrons with the conventional $\mathrm{qq}$ one-gluon exchnage potential. This is mainly due to the Coulomb and the short-range hyperfine interactions. To overcome this difficulty, some phenomenological interactions with a long-range spin dependence are proposed. The validity of treating the spin-dependent term as a perturbation is examined.
TL;DR: In this paper, the Weinberg-Salam Higgs boson mass m/sub H/> or approx. = 9 GeV is assumed to have a symmetry-breaking phase transition only after extreme supercooling, resulting in too high a ratio of entropy to baryon number.
Abstract: Cosmological considerations imply that the Weinberg-Salam Higgs boson mass m/sub H/> or approx. =9 GeV. If this bound were violated, the symmetry-breaking phase transition would occur only after extreme supercooling, resulting in too high a ratio of entropy to baryon number.
TL;DR: Hadronic coupling constants of the vertices including charmonium mesons are calculated in a nonrelativistic quark model as discussed by the authors, which takes into account the SU4 breakings through different masses of quarks and different wave functions in the overlap integrals.
TL;DR: In this article, the standard electroweak gauge model was generalized to SU(2) \ifmmode\times\else\texttimes\fi{} U(1), which has twice the number of gauge bosons of the standard model.
Abstract: We show how the standard electroweak gauge model can be naturally generalized to SU(2) \ifmmode\times\else\texttimes\fi{} U(1) \ifmmode\times\else\texttimes\fi{} SU(2)', which has twice the number of gauge bosons of the standard model. All known fermions transform with respect to SU(2) \ifmmode\times\else\texttimes\fi{} U(1); spontaneous symmetry breaking is achieved with a scalar quartet which links SU(2) and SU(2)' and the usual scalar doublet. The interaction Hamiltonian at low energy reproduces the low-energy phenomenology of the standard model. The high-energy predictions of the model are explored. One $W$ and one $Z$ are less massive than the corresponding bosons of the standard model. These light bosons are relatively narrow, with total widths typically 50 MeV. Cross sections for light $Z$ and $W$ production in ${e}^{+}{e}^{\ensuremath{-}}$ collisions and hadron collisions are given. A $Z$ mass as low as 32 GeV is compatible with existing measurements; the most stringent present limit is set by the ${e}^{+}{e}^{\ensuremath{-}}$ annihilation cross section.
TL;DR: In this article, the topological charge spectrum of quark condensation with (n 2 − 1) small-mass bosons has been studied and general conditions for non-integer ν and hence two vacua at θ = π (mod 2π) were derived for quantization in rational units.
TL;DR: The decay of a neutral heavy Higgs bosonH to a weak vector bosonV+lepton pair is discussed and found to be relevant in this paper, where it is shown that the width is strongly growing with increasing H and frommH≈200 GeV it exceeds ≈10 MeV.
Abstract: The decay of a neutral heavy Higgs bosonH to a weak vector bosonV+lepton pair is discussed and found to be relevant. Its width is strongly growing with increasingm
H and fromm
H≈200 GeV it exceeds ≈10 MeV.
TL;DR: In this article, it was shown that neutrino and antineutrino currents parallel to the rotation axis vanishes in the lowest order of perturbation theory in a rotating equilibrium system with parity-violating weak interactions.
Abstract: It has recently been shown that in a rotating equilibrium system there exist neutrino and antineutrino currents parallel to the rotation axis. This suggests that particles other than neutrinos can also develop equilibrium currents if parity-violating weak interactions are taken into account. This possibility is examined using quantum field theory at finite temperature, density, and angular velocity. Regularization and renormalization of such a theory are discussed. The result obtained is negative. It is found that in the model considered the equilibrium current vanishes in the lowest order of perturbation theory. This is a surprising result, since the existence of a nonzero current is not forbidden by the symmetries of the Lagrangian. The question naturally arising from this result is whether a nonzero current appears in higher orders of perturbation theory or in different models or there is some deep physical reason which makes the equilibrium current equal to zero for all particles except neutrinos.
TL;DR: In this article, the angular correlation of Lyman cap alpha with inelastically scattered electrons at 54.1s-2p excitation in hydrogen has been studied by observing angular correlation.
Abstract: 1s-2p excitation in hydrogen has been studied by observing the angular correlation of Lyman ..cap alpha.. photons detected in coincidence with inelastically scattered electrons at 54.4 eV incident energy. The electron scattering angles ranged from 10/sup 0/ to 133/sup 0/; the results at scattering angles larger than 20/sup 0/ cannot be explained by currently available theories.
TL;DR: In this paper, total and annihilation cross sections for p-barp and p-bard have been measured over the momentum range 355-1066 MeV/c at closely spaced momenta and with good energy resolution.
Abstract: Total and annihilation cross sections for p-barp and p-bard have been measured over the momentum range 355--1066 MeV/c at closely spaced momenta and with good energy resolution. No evidence is seen for the narrow structure reported by other experiments in the vicinity of 500 MeV/c. The present measurements indicate a broader enhancement in this region, which, if interpreted as a resonance, would have a height of approx. 3 mb and a width of approx. 20 MeV. This structure appears only in the p-barp data.
TL;DR: The general effective radial potentials for a spin-1/2 particle interacting with scalar, electric, and magnetic potentials are given in this paper, where it is shown that the magnetic potential provides a well deep enough to confine the massless particle.
Abstract: The general effective radial potentials for a spin‐ 1/2 particle interacting with scalar, electric, and magnetic potentials are given. In the m=0 limit, it is shown that the magnetic potential provides a well deep enough to confine the massless particle. In particular, there are exact zero‐energy solutions in which two of the four components of the massless particle are confined; only two can leak out into the asymptotic region. The scattering amplitude is analytic in the entire j plane, hence consists only of Regge poles.
TL;DR: In this article, the effects of finite gyroradius ρ and particle drifts (including magnetic trapping) were investigated in a canonical framework, in which both the criterion for onset of stochasticity and the diffusion tensor scale with fieldparticle coupling coefficients were used.
Abstract: The quasi‐linear theory of collisionless test particle diffusion in stochastic magnetic fields is extended to include the effects of finite gyroradius ρ and particle drifts (including magnetic trapping). A canonical framework is used, in which both the criterion for onset of stochasticity and the diffusion tensor scale with field‐particle coupling coefficients gl. The gl contain all the information about the unperturbed orbit of a given particle and the perturbation fields with which the particle interacts. The modification of transport due to finite ρ and drifts is thus found by comparison of the gl including these effects to their driftless, ρ→0 limit. It is found that runaway electron confinement is substantially improved over earlier, driftless estimates, and that trapped particles in microturbulence ought not be stochastic. The perturbations from proposed ripple injection schemes are large enough to induce stochasticity for certain classes of particles.
TL;DR: In this article, small contributions to baryon magnetic moments are discussed, which provide corrections to the simplest nonrelativistic-quark-model estimates, and the remaining discrepancies are similar in size to those encountered in nuclear physics.
Abstract: We discuss small contributions to baryon magnetic moments which provide corrections to the simplest nonrelativistic-quark-model estimates. In particular, we consider configuration mixing of $^{2}S_{M}$ states into the ground states $^{2}S_{S}$, relativistic corrections to the additivity of quark moments, and isospin-violating effects. Although the "corrected" baryon magnetic moments are in better agreement with measurement, the agreement is not perfect; the remaining discrepancies are similar in size to those encountered in nuclear physics.
TL;DR: In this paper, a set of constraints on the masses of particles in the Weinberg-Salam model is obtained and it is shown that in the absence of superheavy fermions (m F ≲ 100 GeV) the Higgs meson mass should exceed the Coleman-Weinberg value ≈9.2 GeV for sin 2 φW ≈ 0.23.
TL;DR: In this paper, the standard SU(2) \ensuremath{\bigotimes} U(1) model is extended to include two $W$ and two $Z$ bosons without changing the structure of its low-energy phenomenology.
Abstract: The standard SU(2) \ensuremath{\bigotimes} U(1) model is extended to include two $W$ and two $Z$ bosons without changing the structure of its low-energy phenomenology. The experimental implications of this model regarding the existence of a light $W$ and a light $Z$ are discussed.
TL;DR: In this article, the use of extensive air shower interactions to study elementary particles is discussed, among the topics treated are energy dependence of cross sections, emulsion chamber techniques, and new particle production.
Abstract: The use of extensive air shower interactions to study elementary particles is discussed. Among the topics treated are energy dependence of cross sections, emulsion chamber techniques, and new particle production. (AIP)
TL;DR: In this paper, the most general expression for the WZH vertex which is the most relevant for the production of charged Higgs particles was derived for SU(2) electroweak gauge models with standard fermion assignments.
Abstract: In the framework of SU(2)\ifmmode\times\else\texttimes\fi{}U(1) electroweak gauge models with standard fermion assignments we derive the most general expression for the $\mathrm{WZH}$ vertex which is the most relevant for the production of charged Higgs particles. We show that the vertex only exists with an appreciable strength in models with a rather complicated Higgs sector. Experimental detection of charged Higgs particles seems therefore very difficult.