Showing papers on "Elementary particle published in 1998"
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TL;DR: The standard model of particle physics is valid to distances as small as 10−16 cm, and there is some evidence (such as that obtained by extrapolating the strengths of the four forces to determine the distance scale at which they might become indistinguishable) that the next level of structure will be detected only at a distance scale of roughly 10−32 cm as discussed by the authors.
Abstract: Particle physicists have spent much of this century grappling with one basic question in various forms: what are the fundamental degrees of freedom needed to describe nature, and what are the laws that govern their dynamics? First molecules, then atoms, then “elementary particles” such as protons and neutrons all have been revealed to be composite objects whose constituents could be studied as more fundamental degrees of freedom. The current “standard model” of particle physics—which is nearly 25 years old, has much experimental evidence in its favor and is comprised of six quarks, six leptons, four forces, and the as yet unobserved Higgs boson—contains internal indications that it, too, may be just another step along the path toward uncovering the truly fundamental degrees of freedom. The standard model is valid to distances as small as 10−16 cm, and there is some evidence (such as that obtained by extrapolating the strengths of the four forces to determine the distance scale at which they might become indistinguishable) that the next level of structure will be detected only at a distance scale of roughly 10−32 cm, far beyond our abilities to measure in the laboratory.
The study of motion and gravity also has undergone several revisions during this century. Reconciling the Newtonian theory of motion with the experimentally observed constancy of the speed of light required the introduction of special relativity, which quite remarkably insists that space and time are intimately related, much as different faces of the same …
2,812 citations
University of Turin1, University of Milan2, Darmstadt University of Applied Sciences3, Stanford University4, University of Hamburg5, University of Vienna6, CERN7, Lorentz Institute8, RWTH Aachen University9, Moscow State University10, Weizmann Institute of Science11, University of Glasgow12, University of Florence13, Northeastern University14, Istituto Nazionale di Fisica Nucleare15, Paul Scherrer Institute16, Centre national de la recherche scientifique17, University of Cambridge18, University of Montpellier19, Rutherford Appleton Laboratory20, University of Paris21, Leipzig University22, University of Geneva23, Indian Institute of Science24, Aristotle University of Thessaloniki25, Karlsruhe Institute of Technology26, Helsinki Institute of Physics27, Heidelberg University28, Silesian University29, University of Warsaw30, Max Planck Society31, Ludwig Maximilian University of Munich32, Autonomous University of Barcelona33, Sapienza University of Rome34, University College London35, University of Barcelona36, University of Bergen37, University of Trieste38, Rutgers University39, University of Valencia40, University of Würzburg41, Lund University42, Durham University43
TL;DR: The physics potential of linear linear colliders has been discussed in this paper, where the authors describe the potential for the discovery of particles in supersymmetric extensions of the Standard Model, the spectrum of Higgs particles, the super-ymmetric partners of the electroweak gauge and Higgs bosons.
250 citations
TL;DR: In this article, a diagrammatic calculation of the leading two-loop QCD corrections to the masses of the neutral Higgs bosons in the minimal supersymmetric standard model (MSSM) is performed.
Abstract: We perform a diagrammatic calculation of the leading two-loop QCD corrections to the masses of the neutral $\mathrm{CP}$-even Higgs bosons in the minimal supersymmetric standard model (MSSM). The results are valid for arbitrary values of the parameters of the Higgs boson and scalar top sector of the MSSM. The two-loop corrections are found to reduce the mass of the lightest Higgs boson considerably compared to its one-loop value. The numerical results are analyzed in the grand unified theory favored regions of small and large $\mathrm{tan}\ensuremath{\beta}.$ Their impact on a precise prediction for the mass of the lightest Higgs boson is briefly discussed.
232 citations
Journal Article•
TL;DR: In this article, the basic physics of intensity interferometry, and its current applications in high energy nuclear physics, as well as recent applications in condensed matter and atomic physics, are discussed.
Abstract: In the 1950's Hanbury Brown and Twiss showed that one could measure the angular sizes of astronomical radio sources and stars from correlations of signal intensities, rather than amplitudes, in independent detectors. Their subsequent correlation experiments demonstrating quantum bunching of photons in incoherent light beams were seminal in the development of quantum optics. Since that time the technique of "intensity interferometry" has become a valuable probe of high energy nuclear and particle collisions, providing information on the space-time geometry of the collision. The effect is one of the few measurements in elementary particle detection that depends on the wave mechanics of the produced particles. Here we discuss the basic physics of intensity interferometry, and its current applications in high energy nuclear physics, as well as recent applications in condensed matter and atomic physics.
131 citations
Posted Content•
TL;DR: In this article, the basic physics of intensity interferometry, and its current applications in high energy nuclear physics, as well as recent applications in condensed matter and atomic physics, are discussed.
Abstract: In the 1950's Hanbury Brown and Twiss showed that one could measure the angular sizes of astronomical radio sources and stars from correlations of signal intensities, rather than amplitudes, in independent detectors. Their subsequent correlation experiments demonstrating quantum bunching of photons in incoherent light beams were seminal in the development of quantum optics. Since that time the technique of "intensity interferometry" has become a valuable probe of high energy nuclear and particle collisions, providing information on the space-time geometry of the collision. The effect is one of the few measurements in elementary particle detection that depends on the wave mechanics of the produced particles. Here we discuss the basic physics of intensity interferometry, and its current applications in high energy nuclear physics, as well as recent applications in condensed matter and atomic physics.
127 citations
TL;DR: In this article, the coupling of CP-even and CP-odd Higgs bosons to a photon and a Z boson in extensions, of the Standard Model was analyzed, and the contribution of SUSY particle loops in the minimal supersymmetric extension of the standard model was discussed.
Abstract: We analyze the coupling of CP-even and CP-odd Higgs bosons to a photon and a Z boson in extensions, of the Standard Model. In particular, we study in detail the effect of charged Higgs bosons in two-Higgs doublet models;. and the contribution of SUSY particle loops in the minimal supersymmetric extension of the Standard Model: The Higgs-γZ coupling can be measured in the decayZ → γ+Higgs ate
+
e
− colliders running on theZ resonance, or in the reverse process Higgs →Zγ with the Higgs boson produced at LHC. We show that a measurement of this coupling with a precision at the percent level, which could be the case at futuree
+
e
− colliders, would allow to distinguish between the lightest SUSY and standard Higgs bosons in large areas of the parameter space.
92 citations
TL;DR: In this article, a scalar sector of the 3 3 1 model with three Higgs triplets is considered, and the mass spectrum, eigenstates and interactions of the Higgs and the SM gauge bosons are derived.
Abstract: A scalar sector of the 3 3 1 model with three Higgs triplets is considered in detail. The mass spectrum, eigenstates and interactions of the Higgs and the SM gauge bosons are derived. We show that one of the neutral scalars can be identified with the standard model Higgs boson, and in the considered potential, there is no mixing between scalars having vev and those without vev.
60 citations
CERN1
TL;DR: In this paper, the trilinear couplings between charged and neutral CP -even Higgs bosons, H + H − H 0 and H+ H −H 0, can be measured.
59 citations
TL;DR: In this paper, the differences between the on-shell mass and width of the Higgs boson and their pole counterparts are evaluated in leading order, and they are found to be sensitive functions of the gauge parameter and become numerically large over a class of gauges that includes the unitary gauge.
Abstract: The differences between the on-shell mass and width of the Higgs boson and their pole counterparts are evaluated in leading order. For a heavy Higgs boson, they are found to be sensitive functions of the gauge parameter and become numerically large over a class of gauges that includes the unitary gauge. For a light Higgs boson, the differences remain small in all gauges. The pinch-technique mass and width are found to be close to their pole counterparts over a large range of Higgs boson masses.
40 citations
TL;DR: In this paper, the authors investigated the production of Higgs particles in association with the supersymmetric scalar partners of the top quark at proton colliders, and showed that the cross sections for the lightest neutral Higgs boson production can be rather large, substantially exceeding the rate for the associated production with top quarks.
Abstract: We investigate the production of Higgs particles in association with the supersymmetric scalar partners of the top quark at proton colliders. In the minimal supersymmetric extension of the standard model, the cross sections for the lightest neutral Higgs boson production can be rather large, substantially exceeding the rate for the associated production with top quarks. If the lightest top squark is not much heavier than the top quark, this process will enhance the potential of the CERN Large Hadron Collider to discover the lightest neutral Higgs boson, and will open a window to the study of the Higgs-stop coupling, the potentially largest electroweak coupling in the supersymmetric theory.
34 citations
Journal Article•
TL;DR: In this article, it was shown that inflation is almost inevitable consequence of the great difference between Planck mass and the mass of the heaviest massive particle. But the shape of inflationary solutions strongly depends on the underlying gauge model of the elementary particles physics.
Abstract: In the very early Universe the matter may be described by the free radiation, that is by the set of massless fields with negligible interactions between them. Then the dom- inating quantum effect is the trace anomaly which comes from the renormalization of the conformal invariant part of the vacuum action. The anomaly-induced effective action can be found with accuracy to an arbitrary conformal functional which vanishes for the special case of the conformally flat metric. This gives the solid basis for the study of the conformally-flat cosmological solutions, first of which was discovered by Mamaev and Mostepanenko and by Starobinski in 1980. Treating the anomaly-induced action as quantum correction to the Einstein-Hilbert term we explore the possibility to have inflationary solutions, investigate their dependence on the initial data and discuss the restrictions in considering the density perturbations. The shape of inflationary solutions strongly depends on the underlying gauge model of the elementary particles physics. Two special cases are considered: Minimal Stan- dard Model and the matter sector of N = 8, D = 4 supergravity. It turns out that inflation is almost inevitable consequence of the great difference between Planck mass and the mass of the heaviest massive particle.
TL;DR: In this paper, the three-dimensional U(1) + Higgs theory (Ginzburg-Landau model) was studied as an effective theory for finite-temperature phase transitions from the 1 K scale of superconductivity to the relativistic scales of scalar electrodynamics.
TL;DR: In this paper, generalized quantal distribution functions are investigated concerning systems of noninteracting bosons and fermions and applications to the Chandrasekhar limit of white dwarfs stars and to the Bose-Einstein condensation are commented.
Abstract: The generalized quantal distribution functions are investigated concerning systems of non-interacting bosons and fermions. The formulae for the number of particles and energy are presented and applications to the Chandrasekhar limit of white dwarfs stars and to the Bose–Einstein condensation are commented.
Book•
08 Sep 1998
TL;DR: In this article, the standard model of the Electroweak interaction is used to describe the interactions between particles and their interactions in the electromagnetic field, and the Standard Model of Electroweak Interaction is described.
Abstract: 1 Particles and Interactions: An Overview.- 2 Boson Fields.- 3 Fermion Fields.- 4 Collisions and Decays.- 5 Discrete Symmetries.- 6 Hadrons and Isospin.- 7 Quarks and SU(3) Symmetry.- 8 Gauge Field Theories.- 9 The Standard Model of the Electroweak Interaction.- 10 Electron-Nucleon Scattering.- 11 Neutral K Mesons and CP Violation.- 12 The Neutrinos.- 13 Muon and Tau Lepton Decays.- 14 One-Loop QCD Corrections.- 15 Asymptotic Freedom in QCD.- 16 Heavy Flavors.- 17 Status and Perspectives of the Standard Model.- Selected Solutions.- Appendix: Useful Formulas.- A.1 Relativistic Quantum Mechanics.- A.2 Cross-Sections and Decay Rates.- A.3 Phase Space and Loop Integrals.- A.4 Feynman Rules.- A.5 Parameters of the Standard Model.
TL;DR: In this paper, a relativistic covariant one boson exchange model was extended to study η production in NN collisions, where the transition amplitudes for the elementary BN → ηN processes with B being the meson exchanged (B = π, σ, η, ϱ, ω and δ) were taken to be the sum of four terms corresponding to s and u-channels with a nucleon or nucleon isobar N ∗ (1535 MeV) in the intermediate states.
Journal Article•
TL;DR: A search for the Standard Model Higgs boson was carried out on data collected by the L3 detector at a center-of-mass energy of $189 \mathrm{\ Ge\kern -0.1em V} as mentioned in this paper.
CERN1
TL;DR: In this article, it was shown that in the minimal supersymmetric extension of the Standard Model with a large trilinear coupling both the fundamental Higgs boson and a bound state of squarks (formed via strong scalar interaction) can have a non-zero VEV.
Book•
28 Oct 1998
TL;DR: In this paper, the authors introduce the concepts of Wave and Particle-Wave Propagation, Bound States, Obstacles, Tunneling, and Unbound States, and Statistical Mechanics.
Abstract: 1. Special Relativity. 2. Waves and Particles I: Electromagnetic Radiation Behaving as Particles. 3. Waves and Particles II: Matter Behaving as Waves. 4. Bound States: Simple Cases. 5. Unbound States: Obstacles, Tunneling, and Particle-Wave Propagation. 6. Quantum Mechanics in Three Dimensions and the Hydrogen Atom. 7. Spin and Atomic Physics. 8. Statistical Mechanics. 9. Bonding: Molecules and Solids. 10. Nuclear Physics. 11. Fundamental Particles and Interactions. Appendices.
TL;DR: In this paper, it was shown that these indirect constraints are much weaker in simple extensions of the MSSM Higgs sector involving the introduction of an extra U (1) gauge group or an extra SU (2)× U ( 1) Y Higgs singlet field; in the latter case charged Higgs bosons can even be pair produced at LEP.
Posted Content•
TL;DR: In this paper, the authors discuss a scenario of ''the path to physics at the Planck scale'' where todays theory of the interactions of elementary particles, the so called Standard Model (SM), emerges as a low energy effective theory describing the long distance properties of a sub-observable medium existing at the planck scale, which they call ''ether''.
Abstract: We discuss a scenario of ``the path to physics at the Planck scale'' where todays theory of the interactions of elementary particles, the so called Standard Model (SM), emerges as a low energy effective theory describing the long distance properties of a sub--observable medium existing at the Planck scale, which we call ``ether''. Properties of the ether can only be observable to the extent that they are relevant to characterize the universality class of the totality of systems which exhibit identical low energy behavior. In such a picture the SM must be embedded into a ``Gaussian extended SM'' (GESM), a quantum field theory (QFT) which includes the SM but is extended in such a way that it exhibits a quasi infrared (IR) stable fixed point in all its couplings. Some phenomenological consequences of such a scenario are discussed.
01 Jan 1998
TL;DR: In this article, a Feynman Checkerboard physics model was constructed that allows computation of force strength constants and constituent mass ratios of elementary particles, with a Lagrangian structure.
Abstract: From sets and simple operations on sets, a Feynman Checkerboard physics model is constructed that allows computation of force strength constants and constituent mass ratios of elementary particles, with a Lagrangian structure that gives a Higgs scalar particle mass of about 146 GeV and a Higgs scalar eld vacuum expectation value of about 252 GeV, giving a tree level constituent Truth Quark (top quark) mass
TL;DR: In this article, the unification of general relativity and standard model for strong and electro-weak interactions is considered on the basic of the conformal symmetry principle, where the Penrose-Chernikov-Tagirov Lagrangian is used to describe the Higgs scalar field modulus and gravitation.
TL;DR: In this paper, the effect of hard gluon kinks on a string is applied to study the strange particle production in Proton-Nucleus and nucleus-nucleus collisions, and it is found that the effective string tension increases with the increase of centrality and mass of the colliding system.
Abstract: The idea that effective string tension increases as a result of the hard gluon kinks on a string is applied to study the strange particle production in proton-nucleus and nucleus-nucleus collisions. It is found that the effective string tension increases with the increase of centrality and mass of the colliding system as a consequence of the minijet (gluon) production stemming from the collective string-string interaction. This mechanism leads to strangeness enhancement in pA and AA collisions through the enhanced production of the strange quark pairs from the color field of strings. We discuss different roles played by this mechanism and rescattering of the final state hadrons in the production of strange particles and compare our results with experimental data.
Book•
01 Jan 1998
TL;DR: In this article, Wolfenstein pointed out that there is also a new interaction in addition to the usual four, called the superweak interaction, which is responsible for the asymmetry.
Abstract: CP violation is one of the most subtle effects in the Standard Model of particle physics and may be the first clue to the physics that lies beyond. Charge conjugation, C, and parity, P, are symmetries of particle interactions. C corresponds to the operation of replacing a particle by its antiparticle, while P is the operation of mirror reflection. Before 1956, it was believed that these were also symmetries of the interactions of elementary particles. In 1956, C S Wu found evidence for P violation in the weak interaction. Theorists proposed that the combination of CP would be a symmetry of the weak interaction. In 1964, Christenson, Cronin, Fitch and Turlay found the first evidence for the violation of CP symmetry in the decays of kaons.Although Kobayashi and Maskawa then showed how the Standard Model can accommodate the observed CP violation, Wolfenstein pointed out that it is also possible that there is a new interaction in addition to the usual four, called the superweak interaction, which is responsible for the asymmetry. To test this idea, the observation of a different type of asymmetry, called direct CP violation, is required; in the kaon sector, very precise measurements of the ratio of kaon decay rates are necessary. In B decay modes where a second order weak process whimisically named "penguin" interferes with another suppressed, first order "tree" amplitude, it may also be possible to observe these direct CP-violating effects.B physics and CP violation is now one of the major growth areas in high energy physics. Nearly every major high energy physics laboratory now has a project underway to observe the large CP asymmetries expected in the B sector and to test the consistency of the Standard Model. The unitarity of the Kobayashi-Maskawa mixing matrix in the Standard Model implies the existence of three phases, called alpha, beta and gamma, which can be determined by the measurements of CP asymmetries in B decays. About 200 participants gathered in Hawaii in March 1997 to discuss the progress in the field, and this important book constitutes the proceedings of that conference.
TL;DR: In this paper, the authors studied the Georgi-Machacek two triplet, one doublet model in the context of LEP2, and showed that cascade decays of Higgs bosons to lighter Higgs Bosons and a virtual vector boson may play a major role.
TL;DR: In this paper, a measurement of the mass of the W boson is presented which is based on a sample of 5982 W → eνv decays observed in pp collisions at √s=1.8 TeV with the D∅ detector during the 1992-1993 run.
Abstract: A measurement of the mass of the W boson is presented which is based on a sample of 5982 W → eνv decays observed in pp collisions at √s=1.8 TeV with the D∅ detector during the 1992-1993 run. From a fit to the transverse mass spectrum, combined with measurements of the Z boson mass, the W boson mass is measured to be MW=80.350±0.140(stat)±0.165(syst)±0.160(scale) GeV/c 2 . Detailed discussions of the determination of the absolute energy scale, the measured efficiencies, and all systematic uncertainties are presented.
TL;DR: A nonstandard approach to the construction of quantum field theory inspired by Markov's idea of the finiteness of the elementary-particle mass spectrum is discussed in this paper, where a non-standard approach is used to construct quantum field theories.
Abstract: A nonstandard approach to the construction of quantum field theory inspired by Markov’s idea of the finiteness of the elementary-particle mass spectrum is discussed.
Posted Content•
TL;DR: In this article, the author's recollections of the turbulent days preceding the establishment of the Standard Model as an accurate description of all known elementary particles and forces are described and discussed.
Abstract: This is an account of the author's recollections of the turbulent days preceding the establishment of the Standard Model as an accurate description of all known elementary particles and forces.