Can one test technicolour?

We estimate the couplings to ordinary particles of the lightest bound states in technicolour theories and discuss the resulting phenomenology. We compute their couplings to light gauge bosons through axial anomalies and also estimate their non-anomalous couplings at low energies. We estimate their couplings to fermions under the general simplifying assumption that each fermion acquires its mass from a unique technifermion condensate (“monophagy”), in which case they are naturally flavour conserving and relatively well-defined. We find that the classic Higgs search experiments (ttoponium → H⁰ + γ, e⁺e^? → H⁺H^?, e⁺e^? → Z⁰ + H⁰) enable one to make a decisive discrimination between elementary and composite models of spontaneous symmetry breaking. We also emphasize the interest of improving experimental limits on K_L⁰ → μe in the context of dynamical symmetry breaking models.     

On pseudo-Goldstone boson masses from broken gauge interactions

We investigate the effects of extended technicolour interactions on the masses of pseudo-Goldstone bosons in one-technifamily models. We find that the P⁰ and P³ cannot acquire any masses from ETC, while the P^± only acquire contributions of order g_Wg_ETC (?5 GeV). This removes a major source of uncertainty in the masses of these particles.     

Challenges for extended technicolour theories

We develop the dialectic between extended technicolour theories and phenomenological constraints on rare processes. The natural suppression of flavour-changing neutral currents and CP-violating processes which can occur in models with elementary scalars is not a general feature of naïve extended technicolour (ETC) models. We study the extent to which naïve ETC estimates must in fact be suppressed in order to be compatible with the phenomenology of such rare processes. We emphasize the potential significance of the exchanges of neutral flavour-changing bosons and find that the strongest constraints arise from considering the combination of the D₁⁰-D₂⁰ and K₁⁰-K₂⁰ systems. CP-violating effects in ETC models must be severely suppressed if they are to be compatible with the observational facts. We point to several rare processes whose further experimental study is of particular concern to ETC theories.     

Spontaneous CP violation in extended technicolor models with horizontal U(2)L ⊗ U(2)R flavor symmetries (I)

The Eichten, Lane, Preskill mechanism for CP violation in extended technicolor (ETC) models is examined in models with “horizontal” U(2)_L ? U(2)_R flavor symmetries. We identify a class of chiral perturbations which generate spontaneous CP violation when the vacuum alignment is determined by Dashen's theorem, and show that, in general, a discrete symmetry must be invoked to avoid strong CP non-conservation. CP-violating phases appearing in the electroweak and broken ETC interactions may be naturally suppressed by ratios of ETC vector boson masses.     

The glueball mass spectrum in QCD: First results of a lattice Monte Carlo calculation

We perform a variational calculation of the masses of glueballs of various spins and parities in SU(2) gauge theory. The quantum vacuum we use is generated by the lattice Monte Carlo technique. Our first results, obtained on medium sized lattices give m(0⁺) = (3.6 ± 0.35) Λ_mom, m(0^? = (6.0 ± 1.0)Λ_mom, m(2⁺) = (6.5^+1.8_?1.1)Λ_mom, various mass upper bounds and information on glueball wave functions.     

On the radiative corrections to the electroweak parameters and precision tests of the electroweak theory

The radiative corrections to the electroweak parameters are reconsidered with an emphasis on analysing prospects for future tests of the as yet untested parts of the electroweak theory, in particular the “new physics” of vector-boson self-interactions and the Higgs scalar. The vacuum polarization due to the light fermions is treated in the leading-long approximation, while the top-quark is taken into account exactly. A detailed analysis of the errors involved in our approximations and a comparison with the results of complete one-loop calculations shows that vacuum polarization due to bosons is negligible, ifm _H =100 GeV, while it may become visible in precision tests ine ⁺ e ^? annihilation, ifm _H ?1 TeV. We also give detailed results (as a function of the top-quark mass) on the radiatively correceted parameters used in model-independent fits to neutrino-scattering and in the interpretation of atomic-parity violation experiments. Technically, we diagonalize the γ-Z propagator for anyq ², and we show, when treating the top-quark vacuum polarization exactly, that the intuitively appealing notion of running coupling constants can be used beyond the leading-log approximation.     

小变形原子核中的相干效应

本文考察了在转动的小变形核力场中运动的核子-核子对、核子-空穴对中的相干效应。计算了O¹⁸最低的偶宇称态0⁺,2⁺,4⁺和O¹⁶最低的奇宇称态0^-,1^-,2^-,3^-波函数;和壳模型经典方法计算出的结果作了比较,二者相当一致。得出的初步结论如下:核力主要是P₂力再加上一定成分具有相干性质的力。前者与转动的变形场等效。不但对于0⁺,2⁺,4⁺,3^-态,而且对于1^-,2^-态,附加的相干成分都很重要;它们的内部态混合组态是比较多的,粒子-粒子之间、或粒子-空穴之间的关联都比较显著。只有0^-态的内部态是纯组态。     

Search for light technimesons

The light neutral colour-singlet spin-zero bosons P⁰ and P³ expected in contemporary extended technicolour theories have some small induced flavour-changing couplings, even in monophagic theories where their couplings are mainly flavour-diagonal. Their non-observation in K⁺ decay means that $\text{m}{}_{\mathrm{<mtext>P</mtext>}}\text{0,3 ? 350}\text{MeV}$, leading one to expect direct quark-lepton transitions mediating K_L0 → μe decay close to the present experimental upper limit. In the absence of some as yet unknown suppression mechanisms, eitherP⁰ and P³ should be observed in bottom decays with a branching ratio approaching 100% (which may already be experimentally excluded) and/or they should be observed in charm decays with branching ratios ? 1% and/or the decay K⁰_L → μe should be detected within an order of magnitude of the present upper limit.     

Phosphorus cluster production by laser ablation

Neutral and charged phosphorus clusters of a wide size range have been produced by pulsed laser ablation (PLA) in vacuum at 532, 337, and 193 nm ablating wavelengths and investigated by time-of-flight mass spectrometry. The neutral P_n clusters are even-numbered with local abundance maxima at n=10 and 14, while the cationic and anionic clusters are preferentially odd-numbered with P₇⁺, P₂₁⁺, and P₁₇^- being the most abundant ions. The dominance of the magic clusters is more pronounced at 337-nm ablation that is explained by efficient direct ejection of their building blocks under these conditions. Nanocrystalline phosphorus films have been produced by PLA in ambient helium gas. PACS 52.38.MF; 61.46.+w; 79.20.Ds; 81.07.B; 81.16.Mk     

AN SU(6) GRAND UNIFIED MODEL

A model of grand unified theory based on SU(6) gauge group is proposed. It can accommodate two generations of ordinary fermions with V－A weak coupling and two generations of anomalous fermions with V+A weak coupling. In this model a new discrete symmetry is introduced which insures existence of fermions with lower masses when SU(6) gauge symmetry is spontaneously broken. We choose simple Higgs fields with appropriate vacuum expectation values so that the masses of anomalous fermions are heavier than those of ordinary fermions. This model also gives the same value of Weinberg angle, sin²θw=3/8, as in the usual SU(5) grand unified model at the grand unified scale.     

High-resolution mass spectra of the residual gas in a metallic vacuum system

The mass spectra of the residual gas in a metallic vacuum chamber of capacity 3 l are studied with an MI-9303 high-resolution magnetic resonance mass spectrometer in the mass range 1–140 u. The experiments are carried out under four evacuation conditions in the pressure range P = 10⁻⁸–10⁻¹⁰ Torr, and almost all the mass peaks forming multiplets are resolved. It is shown that the multiplets with mass numbers M≤80 have, as a rule, a multicomponent structure and hydrogen is the basic component responsible for the total pressure in the chamber irrespective of evacuation conditions. Next in order of intensity in the mass spectra are, CH ₄ ⁺ , H²O⁺, CO⁺, and CO ₂ ⁺ peaks. Other lines in the residual gas spectra are largely due to various C-, H-, N-, and O-based compounds. In addition, the background mass spectrum involves Cl-and F-based compounds and noble gas isotopes. The multiplets with M > 80 often degenerate into a single hydrocarbon line.     

Low-energy neutral current phenomenology and grand unified theories

We derive necessary and sufficient conditions to be satisfied by any expanded electroweak gauge model in order to reproduce the standard model low-energy neutral current predictions. These conditions imply several constraints on the neutral gauge boson masses and quantum number assignments for the ordinary fermions. Using these conditions, we prove that the popular grand unified theories based on the gauge groups SO(10) and E₆ can only accomodate trivial extensions of the standard model. As a consequences, if any of these grand unified models works at some energy scale, present low-energy neutral current phenomenology implies that the Z-boson must be produced with the expected mass and couplings to the ordinary fermions. Any additional neutral gauge boson (with the possible exception of very heavy ones) could only be produced in hadronic collisions and it would not decay in e⁺e^?.     

Family unification within SO(15)

We present a model for the unification of fermion families based on the gauge symmetry SO(15). It is a minimal SO(n) model which can accommodate the known fermions within a single irreducible representation. The model predicts four ordinary fermion families and four families of mirror fermions. The latter have V + A weak interactions, and their mass scale is predicted to be 10² GeV/c². We argue that radiative corrections to the fermion masses can cause non-negligible mixing between ordinary and mirror fermions. The implications of these mixings for the weak interaction phenomenology and solar neutrinos are discussed.     

Observation of the c3Πu-X1Σg+ intersystem transition in the absorption spectrum of P2

The observation of the c³Π_u-X¹Σ_g⁺ intersystem transition of P₂ is reported. The 6-0 band of the system was identified on high resolution absorption plates teken on the NRC 10-m vacuum spectrograph at Ottawa. A rotational analysis of the band is given together with that of the adjacent 5-0 band of the C¹Σ_u⁺-X¹Σ_g⁺ system, the upper level of which is involved in a mutual perturbation with the c³Π_u, v = 6 level. The interaction parameters for the perturbation are derived. It is proposed that the appearance of the 6-0 band of the c³Π_u-X¹Σ_g⁺ transition is due to intensity borrowing from the strong, allowed C¹Σ_u⁺-X¹Σ_g⁺ system. Accurate values for the energies of the c³Π_u, b³Π_g, and a³Σ_u⁺ states relative to the ground state are given. The analysis of two other bands, 2-0 and 7-0, of the C¹Σ_u⁺-X¹Σ_g⁺ system whose upper levels likewise interact strongly with the c³Π_u state are also given.     

Study of the π+π+π-π- system centrally 0 produced by incident π+ andp beams at 85 GeV/c

The reactions π⁺ p→π⁺(π⁺π⁺π^-π^-)p andpp→p(π⁺π⁺π^-π^-)p, where the (π⁺ π⁺ π^- π^-) system is centrally produced have been studied at 85 GeV/c. The π⁺π⁺π^-π^- mass spectrum shows evidence for thef ₁ (1285) meson with a mass of 1278±2 MeV and width 41±12 MeV which decays mainly through ρ⁰(770)π⁺π^-. Thef ₁(1285) is also observed in the ηπ⁺π^- channel. There is no significant evidence for ηππ or 4π decay modes of thef ₁(1420). The ρ⁰ρ⁰ production is found to be small. A Dalitz plot analysis of the 3π system shows evidence fora ₂ (1320) production and for a large contribution of theJ ^PC=1⁺⁺ ρπ wave.     

有挠量子引力和无鬼de Sitter引力(Ⅱ)——SO(3,2)de Sitter引力的无鬼性

本文利用文献的结果审查了de Sitter引力的粒子内容,发现SO(3,2)de Sitter引力既不含鬼粒子,又不含快子。而SO(4,1)应被排除。SO(3,2)de Sitter理论的粒子内容为m=0,J^P=2⁺,1⁺两种正度规粒子,以及m=2^1/2L^-1(L为de Sitter伪球半径)、J^P=0⁺的正度规粒子。本文还在树图近似下研究了宇宙项所造成的Minkowski真空自发破缺。 关键词：     

New fermions at e+e− colliders II. Signals and backgrounds

We discuss the production, at high-energye ⁺ e ^– linear colliders, of new heavy fermions predicted by extensions of the Standard Model. We analyze in great details the various signals and the corresponding backgrounds for both pair production and single production in association with ordinary fermions. Concentrating on new leptons, we use a model detector fore ⁺ e ^– collisions at a center of mass energy of 500 GeV, to illustrate the discovery potential of the next linear colliders.     

Consequences of flavor as a dynamical quantum number

Phenomenological consequences of composite leptons and quarks are studied in the class of models in which the fermions of the first generation (i.e. e, ν_e, u and d) are the ground states of (unspecified) composite systems and each new generation is a radial excitation level. We find that the standard QED results remain practically unaffected in such a scheme. The excited quarks/leptons having mass larger than 5 GeV could be produced in e⁺e^- experiments and would increase the value of R by several per cent as compared with the case of the pointlike quarks and leptons. An argument is given for the smallness of the anomalous magnetic moments of composite leptons.     

Signals of universality violation in e<Superscript>+</Superscript>e<Superscript>-</Superscript> collisions

We examine distributions of leptons produced in e⁺e^- collisions, by a family nonuniversal extra gauge boson Z^′, suggested by the model, and by other neutral gauge bosons occurring in left–right symmetric models and in superstring-inspired E₆ models. We discuss how to distinguish the models by examining the couplings to fermions of the extra Z-boson through its leptonic production cross sections and asymmetries. We show how the universality violation inherent in the model enhances the discovery potential of Z^′ at future planned and proposed e⁺e^- colliders.