Hadron exotique

Résumé

vignette|Exemple de pentaquark : quatre quarks, un antiquark (en jaune) et des gluons (ligne ondulées). Les hadrons exotiques sont des particules subatomiques constituées de quarks (et probablement de gluons), mais qui ne s'insèrent pas dans le schéma habituel des hadrons. Bien que sensibles à l'interaction forte, ils ne sont pas prévus par le . Les hadrons exotiques n'ont en effet pas le même contenu en quarks que les hadrons ordinaires : les baryons exotiques ont plus de quarks que les trois qui constituent les baryons ordinaires, et les mésons exotiques n'ont pas un quark et un antiquark comme les mésons ordinaires. Des indices expérimentaux de l'existence d'hadrons exotiques ont été observés en 2003, mais restent un sujet de controverse en physique des particules. Types de hadrons exotiques

Les "baryons exotiques" sont théoriquement formés d'un nombre impair de quarks et d'antiquarks. Les plus connus sont les pentaquarks qui sont formés de quatre quarks et d'un antiq

Source officielle

https://fr.wikipedia.org/wiki/Hadron_exotique

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Presentation of the electroweak and strong interaction theories that constitute the Standard Model of particle physics. The course also discusses the new theories proposed to solve the problems of the Standard Model.

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Hunting for tetraquarks in ultraperipheral heavy ion collisions

Angelo Esposito, Claudio Andrea Manzari

Ultraperipheral heavy ion collisions constitute an ideal setup to look for exotic hadrons because of their low event multiplicity and the possibility of an efficient background rejection. We propose to look for fourquark states produced by photon-photon fusion in these collisions at the center-of-mass energy per nucleon pair root s(NN) = 5.5 TeV. In particular, we focus on those states that would represent a definite smoking gun for the compact tetraquark model. We show that the X(6900), a likely cc (c) over bar(c) over bar compact state, is a perfect candidate for this search, and estimate a production cross section ranging from around 250 nb to 1150 nb, depending on its quantum numbers. Furthermore, we discuss the importance of ultraperipheral collisions to the search for the scalar and tensor partners of the X(3872) predicted by the diquarkonium model, and not yet observed. The completion of such a flavor-spin multiplet would speak strongly in favor of the compact tetraquark model.

AMER PHYSICAL SOC2021

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Effective Field Theories for New and Old Physics

Alfredo Glioti

Effective Field Theories have changed our understanding of Quantum Field Theories. This thesis shows several applications of this powerful tool in the context of the Standard Model and for searches of New Physics.The thesis starts with a review of the Standard Model and its open questions and is followed by an updated and systematic study of models of flavor in the context of Partial Compositeness in Composite Higgs theories. Following that, the question on how to measure the Wilson coefficients of the Standard Model effective operators at present and future experiments is addressed: first by using modern Machine Learning techniques by studying angular distributions for diboson production, followed then by a study on ElectroWeak radiation at a future Muon Collider and how to use it to better probe the new physics parameter space.The fourth chapter deals instead with applying Non-Relativistic Effective Theories to the study of exotic mesons in the Standard Model. The two competing interpretations, a molecule formed of two mesons or a compact tetraquark state, and their consequences are studied. In particular this study is done on the X(3872) exotic charmonium and the consequences of the two accidental tunings of this system are discussed.The last chapter addresses the problem of baryogenesis from the ElectroWeak phase transition. A new scalar sector is introduced that decouples the physics responsible for the generation of the baryon asymmetry from the weak scale. This helps solving the main problems that ElectroWeak baryogenesis models face, namely the large modifications to the Higgs physics and the need of large CP violating new effects.

EPFL2022

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Minimal matter at the large hadron collider

Roberto Franceschini, Duccio Pappadopulo

We classify all possible new U(1)(Y) circle times SU(2)(L) circle times SU(3)(c) multiplets that can couple to pairs of SM particles. Assuming that production of such new particles is dominated by their gauge interactions we study their signals at LHC, finding the following five main classes: (i) lepto-quark 2l2q signals; (ii) di-lepton 4l signals; (iii) di-quarks 4j signals, (iv) heavy-lepton 2l2V signals and (v) heavy quarks 2j2V signals, where V denotes heavy SM vectors (with W being associated to exotic fermions). In each case we outline the most promising final states, the SM backgrounds and propose the needed searches. (C) 2009 Elsevier B.V. All rights reserved.

2010

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