Showing papers on "Elementary particle published in 1984"
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01 Dec 1984
TL;DR: In a recent review as mentioned in this paper, the authors reflect some of the shifts of emphasis that are occurring among the fields of astrophysics, nuclear physics, and elementary particle physics and discuss the role of rotational degrees of freedom in heavy-ion collisions at low and moderate energies.
Abstract: The contents of this review reflect some of the shifts of emphasis that are occurring among the fields of astrophysics, nuclear physics, and elementary particle physics. Particle physics has made great advances in the unification of the fundamental forces of nature. Discussions and planning for a next big step in accelerator-colliders are presented. The technology of superconducting magnet systems as well as the fundamental physical principles of particle accelerators are discussed. Also presented are: high-resolution electronic particle detectors; nuclear physics changes such as pion interactions within nuclei; discussion of future relativistic heavy-ion colliders; the role of rotational degrees of freedom in heavy-ion collisions at low and moderate energies; hyperon beta decays; and the analysis of materials via nuclear reaction techniques. Neutrinos, their interactions and possible masses, have an important bearing on cosmology and the matter density of the universe in addition to their inherent interest in the microscopic world and this is also examined.
676 citations
TL;DR: In this article, the authors examine the algebraic and geometric properties of the interacting boson model-1 and review the interaction model-2, and discuss analytic solutions, transitional classes, extensions of the models, coherent states, transition classes and shape phase transitions, energy levels, electromagnetic transition rates, other properties, a microscopic description of interacting bosons, generalized seniority, the single j-shell, several jshells, and the Ginocchio model.
Abstract: This chapter examines the algebraic and geometric properties of the interacting boson model-1, and reviews the interacting boson model-2. Explains that the model was originally introduced with only one kind of collective boson variable with angular momentum J=O and J=2 (the interacting boson model-1), and subsequently, a more elaborate version was introduced with two kinds of collective variables, proton bosons and neutron bosons (the interacting boson model-2). Discusses analytic solutions, transitional classes, extensions of the models, coherent states, transitional classes and shape-phase transitions, energy levels, electromagnetic transition rates, other properties, a microscopic description of interacting bosons, generalized seniority, the single j-shell, several j-shells, and the Ginocchio model. Excludes odd-even nuclei and the corresponding interacting boson-fermion models 1 and 2 from the review.
577 citations
TL;DR: In an interesting class of composite Higgs models, the composite mass can be calculated to be mH ≅ 1.7 MW as mentioned in this paper where the confining ultracolor group which binds the Higgs is SU(N), N ⩾ 3.
240 citations
TL;DR: The associated production of a heavy Higgs boson (mH > 100 GeV) with top quarks at Juratron energies is studied in this paper, where it is assumed that the mass value of the top-quarks is in the interval mt ≈ 30-80 GeV.
171 citations
TL;DR: In this article, the CPT, CP, and C properties of Majorana neutrinos with opposite CP parity were derived and examined for neutrinoless double-beta-decay.
Abstract: In neutrinoless double-..beta.. decay, the contributions of two virtual Majorana neutrinos with opposite CP parity will interfere destructively. This makes it evident that the amplitudes for reactions involving Majorana particles contain significant new phase factors, reflecting the special discrete-symmetry properties of these particles. To study this phenomenon, we derive and examine the CPT, CP, and C properties of Majorana particles. We then apply these properties, especially to the study of neutrinoless double-..beta.. decay, and to the neutral weak and electromagnetic interactions of Majorana particles. We show how the new phase factors in the Feynman amplitudes for Majorana-particle processes arise, and see that their precise form and location within these amplitudes depends on one's choice of formalism.
166 citations
TL;DR: In this paper, the authors derived an exact large-$N$ equation identical to the so-called bootstrap condition of static strong-coupling theory, which determines the group structure of the baryon multiplets at $N\ensuremath{\rightarrow}\ensureMath{\infty}$.
Abstract: Starting from the large-$N$ power counting which suggests that the baryons are QCD solitons, the authors derive an exact large-$N$ equation identical to the so-called bootstrap condition of static strong-coupling theory. This equation determines the group structure of the baryon multiplets at $N\ensuremath{\rightarrow}\ensuremath{\infty}$. One solution is the standard nonrelativistic quark model.
130 citations
01 Jan 1984
94 citations
TL;DR: For a wide range of top-quark masses, the Higgs mass in the canonical realization of the Salam-Weinberg theory must be < or approx. =125 GeV as discussed by the authors.
Abstract: It is shown that, for a wide range of top-quark masses, the Higgs mass in the canonical realization of the Salam-Weinberg theory must be < or approx. =125 GeV. The considerations are predicated on the premise that the pure lambdaphi/sup 4/ theory is a free-field theory. The bound emerges as a necessary condition, albeit within a specific scenario, to avoid the trap of a trivial Higgs sector.
88 citations
TL;DR: In this article, the O2N Higgs-Goldstone model was shown to be a good indicator of the behavior of the standard SU2 ⊗ U1 electroweak model in the non-perturbative limit of a strongly interacting Higgs sector.
68 citations
TL;DR: In this article, the authors studied the six-quark system in a nonrelativistic quark model which incorporates some of the features expected from chromodynamics using a large basis space which includes color, spin, and orbital excitations.
Abstract: We have studied the six-quark system in a nonrelativistic quark model which incorporates some of the features expected from chromodynamics Using a large basis space which includes color, spin, and orbital excitations, and a Hamiltonian completely determined by previous studies of baryon structure, we derive a number of the features of low-energy nuclear physics Among our findings are (1) a strong dynamical clustering of the $3u\ensuremath{-}3d$ system into a neutron-proton configuration and (2) an effective nucleon-nucleon potential with a strong repulsive core and an intermediate-range attraction similar to those of semiphenomenological potentials When supplemented with a reasonable model for one-pion exchange, this effective potential gives a good account of the properties of the deuteron
66 citations
TL;DR: In this article, the mass relations between ordinary Higgs particles were derived and the most crucial relation gave an upper bound of 93 GeV on the mass of the lightest Higgs scalar.
TL;DR: In this paper, the authors performed a QCD calculation of semi-inclusive Higgs-boson production in conjunction with a heavy-quark pair in pp-bar collisions.
Abstract: We have performed a QCD calculation of semi-inclusive Higgs-boson production in conjunction with a heavy-quark pair in pp-bar collisions. Numerical results are obtained through a Monte Carlo integration. Several differential cross sections relevant to experiment are given.
TL;DR: In this article, the possibility that the lowest energy state for certain quantum numbers involves a Higgs field polarized into a skyrmion-type configuration was discussed, and a new type of vacuum instability arises.
Abstract: The possibility is discussed that the lowest-energy state for certain quantum numbers involves a Higgs field polarized into a skyrmion-type configuration. In some models a new type of vacuum instability arises. Phenomenological consequences are indicated schematically.
01 Jan 1984
TL;DR: In this article, it was shown that effects which are preasymptotic in the mass of the heavy quark in nonleptonic weak decays of charmed particles lead to the experimentally observed hierarchy of lifetimes tau(.. lambda../sub c//sup +/).. us in the case of.. lambda../sup +//sub c/ decay.
Abstract: It is shown that effects which are preasymptotic in the mass of the heavy quark in nonleptonic weak decays of charmed particles lead to the experimentally observed hierarchy of lifetimes tau(..lambda../sub c//sup +/).. us in the case of ..lambda../sup +//sub c/ decay.
TL;DR: In this article, the authors proposed a therrnalization mechanism of vacuum energy due to Higgs particles produced by the temporal change of the background classical Higgs field which subsequently decay into other particles.
Abstract: Entropy production mechanism during the vacuum energy dominated stage of the inflationary universe is considered. We propose a therrnalization mechanism of vacuum energy due to Higgs particles produced by the temporal change. of the background classical Higgs field which subsequently decay into other particles. Then the dissipation coefficient associated with the classical Higgs field is evaluated for an specific decay process and implications of the result are discussed.
TL;DR: In this article, the electroweak $\ensuremath{rho}$ parameter is examined in a general class of supersymmetric models, including scalar quarks and leptons, and an extra doublet of Higgs scalars.
Abstract: The electroweak $\ensuremath{\rho}$ parameter is examined in a general class of supersymmetric models. Formulas are given for one-loop contributions to $\ensuremath{\Delta}\ensuremath{\rho}$ from scalar quarks and leptons, gauge and Higgs fermions, and an extra doublet of Higgs scalars. Mass differences between members of isodoublet scalar quarks and leptons are constrained to be less than about 200 GeV.
TL;DR: In this article, the authors explore some properties of dense matter in Skyrme's chiral soliton model and show that at high densities the energy density varies as ${n}^{\frac{4}{3}}, where $n$ is the baryon density.
Abstract: We explore some properties of dense matter in Skyrme's chiral soliton model and show that at high densities the energy density varies as ${n}^{\frac{4}{3}}$, where $n$ is the baryon density. This is quite different from the behavior of conventional nuclear models, but is very similar to that of quark matter. The maximum mass of neutron stars constructed of such matter is significantly lower than that for most other versions of dense matter and may account for the absence of neutron stars in many extended supernova remnants. The phase transition to quark matter is expected to be softened considerably by such a nuclear-matter model.
TL;DR: In this article, the mass limits for new quarks at CM energies between 39.8 and 45.2 GeV and a search was made for new heavy quarks and no evidence was found for the existence of a narrow state in this mass range.
TL;DR: In this paper, tree unitarity is shown to be valid for partial-wave scattering amplitudes provided three quartic couplings from the Higgs potential are small, provided that at least one neutral scalar must have a mass $Ml1$ TeV.
Abstract: The abundance of new Higgs bosons in many extensions of the electroweak theory motivate an investigation of their effect on partial-wave scattering amplitudes. For SU(2)\ifmmode\times\else\texttimes\fi{}U(1), tree unitarity is shown to be valid for $W$ and $Z$ amplitudes provided three quartic couplings from the Higgs potential are small ($|f|l16\ensuremath{\pi}$). The mass spectrum of the Higgs boson is almost unconstrained but for the simple requirement that at least one neutral scalar must have a mass $Ml1$ TeV. Similar results are obtained in a general broken guage theory for the scattering of arbitrary combinations of scalar and vector bosons.
TL;DR: The leading two-loop correction to the masses of the vector bosons was calculated in the limit of large Higgs mass as mentioned in this paper, and the result is equal and of the same sign as the one-loop result for a higgs mass of about fifty-five times the vector Boson mass.
TL;DR: In this article, the authors examined dynamical gauge-symmetry breaking and left-right asymmetry in higher-dimensional theories by taking non-Abelian gauge theory on a manifold M/sup 2/ x S/Sup 2/, where Msup 2 / and S/sup / are a two-dimensional Minkowski space and a twosphere, respectively.
Abstract: We examine dynamical gauge-symmetry breaking and left-right asymmetry in higher-dimensional theories by taking non-Abelian gauge theory on a manifold M/sup 2/ x S/sup 2/, where M/sup 2/ and S/sup 2/ are a two-dimensional Minkowski space and a two-sphere, respectively. It is shown that a shift in fermion zero-point energies due to the compactness of the extra-dimensional space S/sup 2/ induces dynamical gauge-symmetry breaking, provided that there exist many heavy fermions. With additional Weyl fermions incorporated in M/sup 2/ x S/sup 2/ we obtain left-right--asymmetric massless fermions in M/sup 2/. The effective Lagrangian in M/sup 2/ is given. A relationship between four-dimensional and two-dimensional anomalies is also established.
TL;DR: In this article, a simple method is presented for evaluating transition amplitudes between massive states with spin = 1 2, 1 and definite polarization, and applications to testing the decay and production of vector bosons are considered.
TL;DR: In this paper, the possibility of isolating single electroweak structure functions in deep inelastic lepton-nucleon scattering at Q 2 around M 2 1 /2 2 /
Abstract: The possibility is studied of isolating single electroweak structure functions in deep inelastic lepton-nucleon scattering atQ
2 aroundM
2
. Utilizing the cross-section dependence on the lepton charge and longitudinal polarization λ it is shown that the most-conclusive results follow from measurements of σ+(−λ)±σ−(+λ). Considerable simplifications of the problem are possible if λ can be tuned to sin2 θ dependent values of about 0.2. New quark-parton model relations are derived.
TL;DR: In this paper, an exact solution to the evolution equation is found, and a momentum-degradation length of 4.9 fm is inferred from the data, based on Hwa's model.
Abstract: Inclusive cross sections for the reactions $p+A\ensuremath{\rightarrow}p+X$ at 100 GeV are discussed in the framework of the evolution model proposed by Hwa. An exact solution to the evolution equation is found. A momentum-degradation length of 4.9 fm is inferred from the data.
TL;DR: Using the QCD sum-rule approach, this article studied the two-body decays into ordinary mesons of J/sup P/C = 1/sup +/ quark-antiquark-gluon hybrid mesons containing u and d quarks.
Abstract: Using the QCD sum-rule approach, we study the two-body decays into ordinary mesons of J/sup P/C = 1/sup - +/ quark-antiquark-gluon hybrid mesons containing u and d quarks. It is found that the I = 0 state is stable for these decays while the I = 1 states decay predominantly into ..pi..rho with a characteristic width of 10 to 100 MeV.
TL;DR: In this article, the authors investigated the possible influence of the chromomagnetic vacuum fields on high energy hadron-hadron reactions and suggested that high energy quarks traversing these fields will produce soft gluon and photon radiation analogous to synchrotron radiation from electrons and positrons in a storage ring.
Abstract: Standard ideas on the structure of the vacuum in QCD suggest it to be full of fluctuating color fields. We investigate the possible influence of the chromomagnetic vacuum fields on high energy hadron-hadron reactions. We suggest that high energy quarks traversing these fields will produce soft gluon and photon radiation analogous to synchrotron radiation from electrons and positrons in a storage ring. We argue that this radiation will lead to polarization phenomena for quarks in spin- and colorspace which in turn can explain theK-factor in the Drell-Yan reaction. We point out that jet production offers another way to study these polarization phenomena. We present then a calculation of the number of “synchrotron” photons which should be emitted inp−p collisions at high energies. Thus, we predict a sizable signal of prompt photons of nnergy less than a few hundred MeV with a characteristic frequency distribution. Observation of such photons would give strong support to our naive picture. Finally we point out a number of other phenomena like charmed particle decays where our “synchrotron” effect may be of importance.
TL;DR: For a top quark mass of 30 (40) GeV, the upper bound on the light Higgs is given by 11 (24) and 14 (15) GeVs respectively.
01 Nov 1984
TL;DR: In this article, it is shown that two photon studies can refute the difficult-to-refute hypothesis that xi(2220) or zeta(8320) are Higgs bosons.
Abstract: A quantity called stickiness is introduced which should be largest for J not equal to 0 glueballs and can be measured in two photon scattering and radiative J/psi decay. An argument is reviewed suggesting that light J = 0 glueballs may have large couplings to two photons. The analysis of radiative decays of eta and eta' is reviewed and a plea made to desist from false claims that they are related to GAMMA(..pi../sup 0/ ..-->.. ..gamma gamma..) by SU(3) symmetry. It is shown that two photon studies can refute the difficult-to-refute hypothesis that xi(2220) or zeta(8320) are Higgs bosons. A gallery of rogue resonances and resonance candidates is presented which would usefully be studied in ..gamma gamma.. scattering, including especially the low mass dipion. 34 references.
TL;DR: In this paper, the results of the prompt-neutrino experiment at Fermilab were analyzed to set limits on the masses and decays of supersymmetric particles by means of three measurements; (1) the..nu../sub e//..nu../ sub..mu../ ratio, (2) the rate of events consisting of electromagnetic showers only, and (3) the event rate at large transverse momentum.
Abstract: Muonless events from the prompt-neutrino experiment at Fermilab have been analyzed to set limits on the masses and decays of supersymmetric particles by means of three measurements; (1) the ..nu../sub e//..nu../sub ..mu../ ratio, (2) the rate of events consisting of electromagnetic showers only, and (3) the event rate at large transverse momentum. These limits are based upon the absence of events above our visible energy cutoff of 20 GeV which could be attributed to supersymmetry. Several hypotheses concerning supersymmetric particle decays are considered.