Showing papers on "Elementary particle published in 1988"
TL;DR: A formalism which is adapted to study the evolution of a photon (axion, graviton) beam in the presence of external fields is developed, and the possibility of detecting axions by a measurement of the magnetically induced birefringence of the vacuum is discussed.
Abstract: Photons can mix with low-mass bosons in the presence of external electromagnetic fields if these particles---not necessarily of spin 1---couple by a two-photon vertex. Important examples are the hypothetical axion (spin 0) and graviton (spin 2). We develop a formalism which is adapted to study the evolution of a photon (axion, graviton) beam in the presence of external fields. We apply our results to discuss the possibility of detecting axions by a measurement of the magnetically induced birefringence of the vacuum. We also discuss photon-axion (graviton) transitions in pulsar magnetic fields. The QED-induced nonlinearity of Maxwell's equations causes magnetic birefringence effects which are much stronger than the axion-induced effects in the range of axion parameters allowed by astrophysical constraints. Also, this QED effect induces an index of refraction for photons in vacuum which is so large near pulsars that photon-axion (graviton) transitions are strongly suppressed. However, this QED effect can be canceled by plasma refractive effects, leading to degeneracy between photons and axions so that resonant transitions can occur in analogy with the Mikheyev-Smirnov-Wolfenstein effect. The adiabatic condition can be met only in spatially extended systems, possibly in the magnetosphere of magnetic white dwarfs. Our conclusions differ substantially from several recent discussions of various aspects of these mixing phenomena.
772 citations
TL;DR: The observation of a neutrino pulse from the supernova SN1987A constrains the production of light exotic particles in the proto neutron star and derives a new bound on the axion decay constant, f/sub a/approx.
Abstract: The observation of a neutrino pulse from the supernova SN 1987A constrains the production of light exotic particles in the protoneutron star. A new bound on the axion decay constant is derived, f(a) of greater than about 10 to the 10th GeV. If right-handed (RH) neutrinos exist, 'RH Fermi constant' is G(RH) of less than about 10 exp-4 G(F), two orders of magnitude below laboratory bounds. The Dirac mass of hv sub m can be constrained below laboratory limits. The Dirac mass of the mu-neutrino can be constrained below laboratory limits.
377 citations
TL;DR: In this article, the decay of a standard model Higgs boson into a tau pair was considered as a possible signature at the SSC or LHC for a Higgs particle of mass between 110 and 160 GeV.
312 citations
TL;DR: In this paper, the SU(2) Higgs sector with spontaneously broken O(4) symmetry and perturbative gauge coupling becomes a trivial field theory at infinite cutoff, and a low-energy effective theory is found with non-trivial couplings and mass generation from spontaneous symmetry breaking.
Abstract: The electroweak model with one Higgs doublet is investigated when the mass of the Higgs particle is larger than the weak-interaction scale. It is shown that the SU(2) Higgs sector with spontaneously broken O(4) symmetry and perturbative gauge coupling becomes a trivial field theory at infinite cutoff. Around the trivial Gaussian fixed point, for finite cutoff, a low-energy effective theory is found with non-trivial couplings and mass generation from spontaneous symmetry breaking. We find an upper bound of ${M}_{H}\ensuremath{\approx}640$ GeV on the mass of the Higgs particle with a lattice momentum cutoff $2\ensuremath{\pi}$ times larger than the Higgs-boson mass.
168 citations
TL;DR: A quantum field theory for electroweak interaction and gravitational interaction with local scale invariance and local SU(2) x U(1) gauge invariance is proposed, leading to the existence of Weyl's vector meson which eats up the Higgs particle remaining in the Weinberg-Salam model.
Abstract: A quantum field theory for electroweak interaction and gravitational interaction with local scale invariance and local SU(2) \ensuremath{\bigotimes} U(1) gauge invariance is proposed. The requirement of local scale invariance leads to the existence of Weyl's vector meson which absorbs the Higgs particle remaining in the Weinberg-Salam model.
140 citations
119 citations
01 Jan 1988
TL;DR: In this article, the authors present a collection of papers on electroweak and strong interactions, general relativity, and quantum theory, including Hamiltonian formulations of QCD and aspects of confinement and Mass spectrum of Higgs bosons at the Fermi scale.
Abstract: This book contains papers on electroweak and strong interactions, general relativity, and quantum theory. Topics covered include: Hamiltonian formulations of QCD and aspects of confinement and Mass spectrum of Higgs bosons at the Fermi scale.
115 citations
CERN1
TL;DR: In this paper, the authors present new predictions for the detection of supersymmetric dark matter via its annihilation in the Sun and elastic scattering off heavy nuclei in the laboratory, which include many effects found in realistic models such as non-degenerate left-and right-squark masses, unequal super-ymmetric Higgs v.v.s.
114 citations
TL;DR: In this paper, the role of the top quark as a parton is examined by a detailed study of the cancellation between the straight parton model contribution and a subtraction term required by QCD corrections.
102 citations
TL;DR: The cross section of the chiral-SU(2) symmetry reaction is calculated for both on-shell and off-shell photons, as both cases can both be studied at e/sup +/e/sup -/ storage rings.
Abstract: Two-photon production of a neutral-pion pair is uniquely predicted near threshold by the theory of chiral symmetry. The prediction vanishes at the tree level and is nonzero only at one-loop order, yielding a finite result without any unknown counterterms. In this paper we calculate the cross section for both on-shell and off-shell photons, as both cases can both be studied at e/sup +/e/sup -/ storage rings. This reaction is the most accessible process which directly probes the loop structure of chiral-SU(2) symmetry.
98 citations
TL;DR: The low-energy nuclear and atomic experimental evidence against the existence of a light scalar boson is reanalyzed, and the bounds to those originally derived with the expectation that the nucleon consists mainly of the up and down quarks are compared.
Abstract: The chiral-symmetry-breaking sigma term as extracted from the pion-nucleon phase-shift and dispersion analysis implies that the Higgs boson coupling to the nucleon is dominated by the strange quarks. For sigma/sub ..pi..//sub N/approx. =60 MeV the strange-quark contribution is an order of magnitude larger than that of any other flavor. This significantly increases the Higgs-boson--nucleon coupling from its chiral-symmetric value. Some of the phenomenological consequences are briefly discussed. In particular I reanalyze the low-energy nuclear and atomic experimental evidence against the existence of a light scalar boson, and compare the bounds to those originally derived with the expectation that the nucleon consists mainly of the up and down quarks. A summary review of the various issues concerning a large ..pi..N sigma term is also provided.
TL;DR: In this article, the effect of a nonrelativistic particle X, which decays out of equilibrium, on primordial nucleosynthesis is investigated, including both the energy density of the X particle and the electromagnetic entropy production from its decay.
Abstract: The effect of a nonrelativistic particle X, which decays out of equilibrium, on primordial nucleosynthesis is investigated, including both the energy density of the X particle and the electromagnetic entropy production from its decay. The results are parametrized in terms of the X particle lifetime and the density parameter rm(X), where m(X) is the X particle mass and r is the ratio of X number density to photon number density prior to nucleosynthesis. The results rule out particle lifetimes greater than 1-10 s for large values of rm(X). The question of a decaying particle which produces no electromagnetic entropy in the course of its decay is addressed, and particles which produce both entropy and an inert component in their decay are discussed.
TL;DR: In this article, a detailed discussion of the electroweak radiative corrections to the partial decay widths of the Z boson into lepton and quark pairs (q≠t) and to the total width for 5 flavors are presented.
Abstract: We present a detailed discussion of the electroweak radiative corrections to the partial decay widths of theZ boson into lepton and quark pairs (q≠t) and to the total width for 5 flavors. The results are only very weakly dependent on the Higgs mass. The top mass dependence leads to sizable variations ofΓ
z
which have to be taken into account for precision experiments at thee
+
e
− colliders LEP and SLC.
TL;DR: The two-body decay into the lightest Higgs boson is almost always present, and enhances the heavy-quark component of the final state, and the two- body-decay branching ratios into a W or Z can be large for the heaviest charginos and neutralinos.
Abstract: We give explicit formulas for the two-body decays of the neutralinos and charginos of the minimal model of supersymmetry. There are two possible classes of two-body final states: (i) neutralino or chargino plus a W, Z, or Higgs boson; and (ii) channels involving squarks or sleptons. The important features of these decays are illustrated and their phenomenological implications discussed. The two-body decay into the lightest Higgs boson is almost always present, and enhances the heavy-quark component of the final state. In addition, two-body-decay branching ratios into a W or Z can be large for the heaviest charginos and neutralinos.
TL;DR: In this article, the authors examined the rate for B-meson decay to a hard photon and strange hadronic final states (i.e., rmB→γ X s, X s = K ∗, etc) in extension of the standard model with two Higgs doublets and no tree-level flavor-changing neutral Higgs-boson couplings.
TL;DR: An updated survey of mostly experimental spectroscopy work in Seattle on an individual closely-confined isolated atomic or elementary particle is presented in this paper, where the classical notion of an atomic particle at rest in free space is discussed, and shown to be approximable by zero-point confinement of the particle in a laboratory trap.
Abstract: An updated survey of mostly experimental spectroscopy work in Seattle on an individual closely-confined isolated atomic or elementary particle is presented. The classical notion of an atomic particle at rest in free space is discussed, and shown to be approximable by zero-point confinement of the particle in a laboratory trap. An important tool for cooling the particle, and in the case of an electron, for obtaining directly the difference of spin and cyclotron frequencies vs, vc, is side band excitation. The quantum numbers of the geonium "atom", an electron in a Penning trap, have been continuously monitored in a non-destructive way by the new "continuous" Stern-Gerlach effect. In this way the g-factors of electron and positron have been determined to unprecedented precision, ½g ≡ vs/vc ≡ 1.001 159 652 188(4), providing the most severe tests of QED and of the CPT symmetry theorem, for charged elementary particles. From the close agreement of experimental and theoretical g-values a new, 104 × smaller, value for the electron radius, Rg < 10-20 cm, may be extracted. Other important results are: confinement of the individual positron, Priscilla, for 3 months, a tenfold suppression of the natural width of the cyclotron resonance, detection of an isomeric (cyclotron-excited) state via mass-spectroscopy, isolation and continuous detection of an individual proton, confinement of ≈ 100 antiprotons slowed to ≈ 3000 eV, confinement of a Ba+ ion to 13 ≈ 100 nm, and the demonstration of quantum jumps in geonium and in an isolated, individual regular atomic particle, Ba+. Some new experiments are proposed.
TL;DR: In this paper, a generalized formalism of the hidden local symmetry was proposed, in which any nonlinear sigma model based on the manifold C/H is gauge equivalent to a model possessing GglobalX Goeal symmetry.
Abstract: We present a generalized formalism of the hidden local symmetry in which any nonlinear sigma model based on the manifold C/H is gauge equivalent to a model possessing GglobalX Goeal symmetry, which is a natural extension of the well-known gauge equivalence between a C/H nonlinear sigma model and a CglObal X H'oea' "linear" model. As an application of this formalism, we reexamine a possibility that the Al mesons as well as the p mesons and their U(3) partners are dynamical gauge bosons of the hidden local symmetry, [U(3)L x U(3)RJ.oeal, in the U(3h x U(3)R/U(3)v nonlinear sigma model.
TL;DR: In this paper, the authors reexamine the bounds on a very light Higgs boson (φ) coming from limits on the decays K→ π + φ and B→ φ + X.
TL;DR: It is shown thatgluon fusion is just as important as quark-antiquark annihilation for photon pairs of invariant mass less than 200 GeV, and that the gluon-fusion cross section is twice as large for a light top quarks as for a heavy top quark.
Abstract: We study the production of photon pairs at future hadron colliders from quark-antiquark annihilation and gluon fusion via quark loops. We show that gluon fusion is just as important as quark-antiquark annihilation for photon pairs of invariant mass less than 200 GeV, and that the gluon-fusion cross section is twice as large for a light top quark as for a heavy top quark. Photon pairs are an irreducible background to the two-photon decay mode of the Higgs boson, which is important if the Higgs boson is of intermediate mass (m/sub H/<2M/sub W/) and m/sub H/<2m/sub t/, i.e., if its decay to top quarks is kinematically forbidden. If that is the case, we show that the top-quark contribution to the gluon-fusion process is small and, if m/sub H/approx. =2m/sub t/, is even destructive. We also show that a judicious choice of cuts can improve the signal-to-background ratio.
TL;DR: In this article, various massive Yang-Mills theories not based on the Higgs mechanism are investigated and they are subject to conflicting demands in the twin requirements of unitarity and perturbative renormalizability.
Abstract: Various massive Yang-Mills theories not based on the Higgs mechanism are investigated. They are subject to conflicting demands in the twin requirements of unitarity and perturbative renormalizability. Either one or other of these requirements is violated. Unitarity is considered in some detail.
TL;DR: Using the Schwinger-Dyson equations the behavior of quark and gluon propagators is studied in the Landau gauge for momenta from the deep Euclidean to the confinement regime to highlight the usefulness of this continuum approach to nonperturbative QCD as a method of investigating the mechanics of confinement.
Abstract: Using the Schwinger-Dyson equations the behavior of quark and gluon propagators is studied in the Landau gauge for momenta from the deep Euclidean to the confinement regime. We find that while at short distances quarks and gluons propagate like free particles, over longer distances, of the order of a fermi, the gluon propagator is greatly enhanced as are the triple-gluon and quark-gluon couplings. These in turn suppress the propagation of massless quarks over long distances to such an extent that they have no physical particle pole, exactly as expected of a confining theory. We study the way the world changes as the number of massless flavors of quark is increased from zero. Even one generation of light fermions has a sizable deconfining effect on the one-gluon-exchange part of the interquark potential, greater than suggested by naive perturbative counting. These results highlight the usefulness of this continuum approach to nonperturbative QCD as a method of investigating the mechanics of confinement.
TL;DR: The mass of a doubly strange dibaryon called the H particle is calculated in lattice QCD on a 16/sup 3/x 48 lattice with a renormalization-group--improved gauge action and Wilson's quark action.
Abstract: The mass of a doubly strange dibaryon called the H particle is calculated in lattice QCD on a 16/sup 3/ x 48 lattice with a renormalization-group--improved gauge action and Wilson's quark action. We find that the H is below the ..lambda lambda.. threshold for strong decay. Furthermore the case where the H is slightly below the NN threshold for weak decay is consistent with our numerical results and is not in conflict with the stability of the nuclei.
TL;DR: In the search at the Stanford Linear Collider and the CERN collider LEP for a Higgs scalar produced in association with a real or virtual Z boson, it is important not to cut out events with significant missing energy recoiling against the Z.
Abstract: We point out that the dominant decay of the light scalar Higgs boson in a supersymmetric model may be into a pair of the lightest neutralinos (assumed to be the lightest supersymmetric particles), which would result in an invisible final state. Thus, in the search at the Stanford Linear Collider and the CERN collider LEP for a Higgs scalar produced in association with a real or virtual Z boson, it is important not to cut out events with significant missing energy recoiling against the Z.
TL;DR: In this article, Fermion mixing is analyzed in (E6) extensions of the standard model and cross sections and signatures for the production in present and future e+e− colliders are discussed in detail.
TL;DR: N numerically study the regularization dependence of the upper bound on the Higgs-particle mass M/sub H/(phys) by varying the lattice type and interaction by computing f/sub ..pi../ and lambda/sub r/ where the scalar mass is approx. 1.1.
Abstract: We numerically study the regularization dependence of the upper bound on the Higgs-particle mass M/sub H/(phys) by varying the lattice type and interaction. Computing f/sub ..pi../ and lambda/sub r/ where the scalar mass is approx.1, we find the bound M/sub H/(phys)<620 GeV. However, there is a small but systematic increase in the bound as the coordination number of the lattice increases. Hence, it is not meaningful to quote error estimates on such bounds.
TL;DR: This work analyzes the existence of charged Higgs bosons which can be important in rare meson decays, such as K..--> pi nu..nu-bar, with the constraint placed on the charged-Higgs-boson mass, the t-quark mass, and the ratio of the vacuum expectation values of the two doublets by B/ sub d//sup 0/-B-bar/sub d//Sup 0/ mixing.
Abstract: Extensions of the standard model containing two Higgs-boson doublets leads to the existence of charged Higgs bosons which can be important in rare meson decays, such as K--> pi nunu-bar, B/sub d/-->X/sub s/nunu-bar, and B/sub d/-->X/sub s/gamma We analyze these in the minimal two Higgs-boson doublets with the constraint placed on the charged-Higgs-boson mass, the t-quark mass, and the ratio of the vacuum expectation values of the two doublets by B/sub d//sup 0/-B-bar/sub d//sup 0/ mixing An enhancement factor of approx15 over the prediction of the standard model is obtained for the branching ratio of K--> pi nunu-bar
TL;DR: This work considers the transverse-momentum distribution of Higgs-boson production in gluon-gluon fusion and uses resummation techniques to obtain a result valid at all transverse momenta.
Abstract: We consider the transverse-momentum distribution of Higgs-boson production in gluon-gluon fusion. Using resummation techniques we obtain a result valid at all transverse momenta. The resulting distributions are compared with those from the WW fusion mechanism and with those produced by event generators.
TL;DR: The lifetimes of low-mass population I helium-burning stars as derived from the number of ''clump'' giants in the open cluster M67 and in the old galactic disk population agree very well with calculations.
Abstract: The lifetimes of low-mass population I helium-burning stars as derived from the number of ''clump'' giants in the open cluster M67 and in the old galactic disk population agree very well with calculations. This provides an observational basis for previous speculative bounds on axions, Majorons, supersymmetric particles, and exotic scalar and vector bosons. We find a slightly improved bound on the neutrino magnetic dipole moment of ..mu../sub ..nu../<3 x 10/sup -11/..mu../sub B/. The possibility of detecting axionlike particles in the laboratory is severely constrained.
01 Aug 1988
TL;DR: In this article, the process of e/sup +/e/sup -/ annihilation to a pair of quarks for which the semiweak decay channels Q..-->..Wq are open is discussed.
Abstract: The process of e/sup +/e/sup -/ annihilation to a pair of quarks for which the semiweak decay channels Q..-->..Wq are open is discussed. The total cross section of e/sup +/e/sup -/ annihilation to a pair of such quarks near threshold is obtained. This cross section is a calculable function of the quark mass and width and the coupling constant ..cap alpha../sub s/.