Quarks and Leptons Beyond the Third Generation
TL;DR: The possibility of additional quarks and leptons beyond the three generations already established is discussed in this paper, with the possibility of exceptionally long lifetimes and decay modes being dependent on the mass spectrum and mixing angles.
About: This article is published in Physics Reports.The article was published on 2000-06-01 and is currently open access. It has received 251 citations till now. The article focuses on the topics: Quark & Fermion.
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TL;DR: HiggsBounds is a computer code that tests theoretical predictions of models with arbitrary Higgs sectors against the exclusion bounds obtained from the Higgs searches at LEP and the Tevatron, and investigates whether the considered parameter point is excluded at the 95% C.L. on topological cross sections.
803 citations
TL;DR: The physics of the SLAC and KEK B Factories are described in this paper, with a brief description of the detectors, BaBar and Belle, and data taking related issues.
Abstract: This work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C.
413 citations
TL;DR: In this article, the authors systematically study the possible signals at LHC of new vector-like quarks mainly coupled to the third generation, and show that with the combination of different channels the new quarks can be identified and their charged and neutral decays established.
Abstract: We systematically study the possible signals at LHC of new vector-like quarks mainly coupled to the third generation. We consider heavy quarks T, B, X, Y of charges 2/3, -1/3, 5/3 and -4/3, respectively, in SU(2)L isosinglets TL,R, BL,R, or isodoublets TBL,R, XTL,R or BYL,R. Analyses based on a fast detector simulation are presented for twelve different final states containing one, two, three or four charged leptons in several invariant mass regions, also considering various b quark multiplicities. It is shown that with the combination of the different channels the new quarks can be identified and their charged and neutral decays established. The comparison among final states also shows that the single lepton one offers the best discovery potential at LHC. For heavy quark masses of 500 GeV, the 5σ discovery luminosities range from 0.16 fb−1 for a XTL,R doublet to 1.9 fb−1 for a BL,R singlet.
310 citations
TL;DR: In particular, the proper generalization of null vectors towards the logarithmic case, and how these can be used to compute correlation functions, were discussed in this article, where they were complemented by some remarks on ghost systems, the Haldane-Rezayi fractional quantum Hall state, and the relation of these two to the log-mic c=-2 theory.
Abstract: These are notes of my lectures held at the first School & Workshop on Logarithmic Conformal Field Theory and its Applications, September 2001 in Tehran, Iran. These notes cover only selected parts of the by now quite extensive knowledge on logarithmic conformal field theories. In particular, I discuss the proper generalization of null vectors towards the logarithmic case, and how these can be used to compute correlation functions. My other main topic is modular invariance, where I discuss the problem of the generalization of characters in the case of indecomposable representations, a proposal for a Verlinde formula for fusion rules and identities relating the partition functions of logarithmic conformal field theories to such of well known ordinary conformal field theories. The two main topics are complemented by some remarks on ghost systems, the Haldane-Rezayi fractional quantum Hall state, and the relation of these two to the logarithmic c=-2 theory.
266 citations
TL;DR: In this article, an update of the Standard Model fit to electroweak precision data is presented, which includes new experimental results on the top-quark mass, W mass and width, and the Higgs-boson mass bounds from LEP, Tevatron and the LHC.
Abstract: We present an update of the Standard Model fit to electroweak precision data. We include newest experimental results on the top-quark mass, the W mass and width, and the Higgs-boson mass bounds from LEP, Tevatron and the LHC. We also include a new determination of the electromagnetic coupling strength at the Z pole. We find for the Higgs-boson mass $91^{+30}_{-23}~\mbox{GeV}$
and $120^{+12}_{-5}~\mbox{GeV}$
when not including and including the direct Higgs searches, respectively. From the latter fit we indirectly determine the W mass to be $(80.360^{+0.014}_{-0.013})~\mbox{GeV}$
. We exploit the data to determine experimental constraints on the oblique vacuum polarisation parameters, and confront these with predictions from the Standard Model (SM) and selected SM extensions. By fitting the oblique parameters to the electroweak data we derive allowed regions in the BSM parameter spaces. We revisit and consistently update these constraints for a fourth fermion generation, two Higgs doublet, inert Higgs and littlest Higgs models, models with large, universal or warped extra dimensions and technicolour. In most of the models studied a heavy Higgs boson can be made compatible with the electroweak precision data.
257 citations
References
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TL;DR: In this paper, the authors give an explanation of the conservation of strong interactions which includes the effects of pseudoparticles, and they find it is a natural result for any theory where at least one flavor of fermion acquires its mass through a Yukawa coupling to a scalar field which has nonvanishing vacuum expectation value.
Abstract: We give an explanation of the $\mathrm{CP}$ conservation of strong interactions which includes the effects of pseudoparticles. We find it is a natural result for any theory where at least one flavor of fermion acquires its mass through a Yukawa coupling to a scalar field which has nonvanishing vacuum expectation value.
5,545 citations
TL;DR: In this article, it was shown that no CP-violating interactions exist in the quartet scheme without introducing any other new fields, and that the strong interaction must be chiral SU ( 4) X SU( 4) invariant as precisely as the conservation of the third component of the iso-spin.
Abstract: In a framework of the renormalizable theory of weak interaction, problems of CP-violation are studied. It is concluded that no realistic models of CP-violation exist in the quartet scheme without introducing any other new fields. Some possible models of CP-violation are also discussed. When we apply the renormalizable theory of weak interaction1l to the hadron system, we have some limitations on the hadron model. It is well known that there exists, in the case of the triplet model, a difficulty of the strangeness chang ing neutral current and that the quartet model is free from this difficulty. Fur thermore, Maki and one of the present authors (T.M.) have shown2l that, in the latter case, the strong interaction must be chiral SU ( 4) X SU ( 4) invariant as precisely as the conservation of the third component of the iso-spin 13 • In addi tion to these arguments, for the theory to be realistic, CP-violating interactions should be incorporated in a gauge invariant way. This requirement will impose further limitations on the hadron model and the CP-violating interaction itself. The purpose of the present paper is to investigate this problem. In the following, it will be shown that in the case of the above-mentioned quartet model, we cannot make a CP-violating interaction without introducing any other new fields when we require the following conditions: a) The mass of the fourth member of the quartet, which we will call (, is sufficiently large, b) the model should be con sistent with our well-established knowledge of the semi-leptonic processes. After that some possible ways of bringing CP-violation into the theory will be discussed. We consider the quartet model with a charge assignment of Q, Q -1, Q -1 and Q for p, n, A. and (, respectively, and we take the same underlying gauge group SUweak (2) X SU(1) and the scalar doublet field cp as those of Weinberg's original model.1l Then, hadronic parts of the Lagrangian can be devided in the following way:
5,389 citations
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5,265 citations
TL;DR: In this paper, the weak and electromagnetic interactions of leptons are examined under the hypothesis that the weak interactions are mediated by vector bosons, and it is shown that the simplest partially-symmetric model reproducing the observed electromagnetic and weak interactions requires the existence of at least four vector-boson fields (including the photon).
4,387 citations
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TL;DR: In this article, it was pointed out that a global U(1) symmetry, introduced in order to preserve the parity and time-reversal invariance of strong interactions despite the effects of instantons, would lead to a neutral pseudoscalar boson, the "axion", with mass roughly of order 100 keV to 1 MeV.
Abstract: It is pointed out that a global U(1) symmetry, that has been introduced in order to preserve the parity and time-reversal invariance of strong interactions despite the effects of instantons, would lead to a neutral pseudoscalar boson, the "axion," with mass roughly of order 100 keV to 1 MeV. Experimental implications are discussed.
4,138 citations