Tests of the standard model and search for new physics using flavor
CERN1
TL;DR: In this article, the status of the search for new physics with flavor-related observables is discussed, including the status and performance of the unitarity triangle analysis beyond the standard model, and the perspectives of the next generation of flavor-physics experiments, the precision they can reach and their phenomenological impact.
About: This article is published in Progress in Particle and Nuclear Physics.The article was published on 2009-01-01. It has received 8 citations till now. The article focuses on the topics: Physics beyond the Standard Model & CP violation.
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TL;DR: In this paper, the authors proposed an alternative mechanism to suppress squark contributions to flavor changing neutral currents: the alignment of quark with squark mass matrices, which arises naturally in the framework of Abelian horizontal symmetries.
Abstract: For generic squark masses, box diagrams with squarks and gluinos give unacceptably large contributions to neutral meson ($K$, $B$ and $D$) mixing. The standard solution to this problem is to assume that squarks are degenerate to a very good approximation. We suggest an alternative mechanism to suppress squark contributions to flavor changing neutral currents: the alignment of quark with squark mass matrices. This mechanism arises naturally in the framework of Abelian horizontal symmetries.
212 citations
TL;DR: The status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider (LHC) is discussed in this paper, where a compact summary of the logic and structure of the theory precedes an examination of what experimental tests have established so far.
Abstract: This article is devoted to the status of the electroweak theory on the eve of experimentation at CERN's Large Hadron Collider (LHC). A compact summary of the logic and structure of the electroweak theory precedes an examination of what experimental tests have established so far. The outstanding unconfirmed prediction is the existence of the Higgs boson, a weakly interacting spin-zero agent of electroweak symmetry breaking and the giver of mass to the weak gauge bosons, the quarks, and the leptons. General arguments imply that the Higgs boson or other new physics is required on the 1-TeV energy scale. Even if a “standard” Higgs boson is found, new physics will be implicated by many questions about the physical world that the Standard Model cannot answer. Some puzzles and possible resolutions are recalled. The LHC moves experiments squarely into the 1-TeV scale, where answers to important outstanding questions will be found.
73 citations
01 Mar 2004
TL;DR: In this article, the difference between the decay rates of the two neutral-B mass eigenstates and on CP, T, and CPT violation in B{sup 0} and B{bar B} mixing was investigated.
Abstract: Using events in which one of two neutral-B mesons from the decay of an {Upsilon}(4S) resonance is fully reconstructed, we set limits on the difference between the decay rates of the two neutral-B mass eigenstates and on CP, T, and CPT violation in B{sup 0}{bar B}{sup 0} mixing. The reconstructed decays, comprising both CP and flavor eigenstates, are obtained from 88 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We determine six independent parameters governing oscillations ({Delta}m, {Delta}{Lambda}/{Lambda}), CPT and CP violation (Re z, Im z), and CP and T violation (Im {lambda}{sub CP}, |q/p|), where {lambda}{sub cp} characterizes B{sup 0} and {bar B}{sup 0} decays to states of charmonium plus K{sub S}{sup 0} or K{sub L}{sup 0}. The results are sgn(Re {lambda}{sub CP}){Delta}{Lambda}/{Lambda} = .0.008 {+-} 0.037(stat.) {+-} 0.018(syst.) [-0.084, 0.068], |q/p| = 1.029 {+-} 0.013(stat.) {+-} 0.011(syst.) [1.001, 1.057], (Re {lambda}{sub CP}/|{lambda}{sub CP}|)Re z = 0.014 {+-} 0.035(stat.) {+-} 0.034(syst.) [-0.072, 0.101], Imz = 0.038 {+-} 0.029(stat.) {+-} 0.025(syst.) [-0.028, 0.104]. The values inside square brackets indicate the 90% confidence-level intervals. The values of Im {lambda}{sub CP} and {Delta}m are consistent with previous analyses and are usedmore » as cross-checks. These measurements are in agreement with Standard Model expectations.« less
13 citations
Dissertation•
01 Jan 2009
TL;DR: In this article, the authors present l'etude de deux effets parasites, la gigue et la diaphonie, conduite sur le calorimetre electromagnetique d'ATLAS lors de its installation finale.
Abstract: Le collisionneur LHC du CERN permettra de sonder la matiere a des energies inedites en laboratoire. Le Modele Standard et ses extensions potentielles seront testes a l'echelle d'energie du TeV. L'experience ATLAS est pour cela installee a l'un des quatre points d'interaction du LHC. Le quark top y sera produit en grande quantite. Des resultats competitifs sur ses mecanismes de production et de decroissance seront rapidement obtenus. Contrairement aux autres quarks, celui-ci ne s'hadronise pas : les effets de spin sont observables. Il se desintegre en un boson W et un quark beau, qui sont polarises par la violation de la symetrie de parite de l'interaction faible. Cette these presente l'etude prospective de la polarisation des bosons W produits dans la decroissance, en un lepton charge et un ensemble de jets, des paires de quarks top. Cette mesure est realisee par la prediction de la distribution angulaire experimentale du lepton charge, pour chaque etat d'helicite du boson W. Elle permet de contraindre le vertex d'interaction entre le quark top, le boson W et le quark beau. La sensibilite de l'experience ATLAS aux differents couplages anormaux du vertex d'interaction est estimee dans une approche generique. La validation des resultats d'ATLAS necessitera une bonne connaissance des detecteurs. Son calorimetre electromagnetique est notamment caracterise par etalonnage electronique. Cette these presente l'etude de deux effets parasites, la gigue et la diaphonie, conduite sur le calorimetre electromagnetique d'ATLAS lors de son installation finale. L'interet des analyses de diaphonie pour la caracterisation des voies defectueuses du calorimetre est egalement degage.
8 citations
Cites background from "Tests of the standard model and sea..."
...Cette phase est responsable de tous les phénomènes de brisure de la symétrie CP par l'interaction faible du modèle standard [15]....
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Journal Article•
TL;DR: In this paper, the authors presented a method to solve the problem of the PDE problem in PhysRevD by using the Web of Science Record created on 2010-11-05, modified on 2017-05-12.
Abstract: Reference EPFL-ARTICLE-154557doi:10.1103/PhysRevD.73.112009View record in Web of Science Record created on 2010-11-05, modified on 2017-05-12
5 citations
References
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TL;DR: In this paper, the weak scale is generated from the Planck scale through an exponential hierarchy, but this exponential arises not from gauge interactions but from the background metric, which is a slice of spacetime.
Abstract: We propose a new higher-dimensional mechanism for solving the hierarchy problem. The weak scale is generated from the Planck scale through an exponential hierarchy. However, this exponential arises not from gauge interactions but from the background metric (which is a slice of ${\mathrm{AdS}}_{5}$ spacetime). We demonstrate a simple explicit example of this mechanism with two 3-branes, one of which contains the standard model fields. The phenomenology of these models is new and dramatic. None of the current constraints on theories with very large extra dimensions apply.
9,088 citations
TL;DR: In this paper, a single 3-brane embedded in five dimensions was shown to reproduce four-dimensional Newtonian and general relativistic gravity to more than adequate precision, even without a gap in the Kaluza-Klein spectrum.
Abstract: Conventional wisdom states that Newton's force law implies only four noncompact dimensions. We demonstrate that this is not necessarily true in the presence of a nonfactorizable background geometry. The specific example we study is a single 3-brane embedded in five dimensions. We show that even without a gap in the Kaluza-Klein spectrum, four-dimensional Newtonian and general relativistic gravity is reproduced to more than adequate precision.
6,936 citations
TL;DR: In this paper, the authors propose a new framework for solving the hierarchy problem which does not rely on either supersymmetry or technicolor, and they take as the only fundamental short distance scale in nature.
6,013 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
CERN1
TL;DR: In this article, an analysis of leptonic decays based on unitary symmetry for strong interactions and the V-A theory for weak interactions is presented, and an explanation for the observed predominance of the LAMBDA yields + e/sup -/ + nu decay over the lamBDA /sup −/ yields n + e /sup + n decay.
Abstract: An analysis of leptonic decays based on unitary symmetry for strong interactions (eightfold way) and the V-A theory for weak interactions is presented. An explanation for the observed predominance of the LAMBDA yields + e/sup -/ + nu decay over the LAMBDA /sup -/ yields n + e/sup -/ + nu decay is obtained. Branching ratios predicted for electron modes with DELTA S, 1 are presented; the ratios for the above decays agree well with experimental results. (D.C.W.)
3,957 citations