The Hierarchy Problem and New Physics Scenarios

Guido Altarelli

The architecture of the Standard Model, the way symmetries are realized, and the way this can is described at the quantum level.

Half a century or so.

<p>The numerical values given for parameters, such as the Fermi coupling constant $G_F$.</p> Signup and view all the answers

<p>The most recent edition of the Particle Data Book (PDG).</p> Signup and view all the answers

<p>G. Altarelli</p> Signup and view all the answers

<p>University of Rome 3, Rome, Italy</p> Signup and view all the answers

<p>Electroweak sector of the Standard Model</p> Signup and view all the answers

<p>LEP electron-positron collider of CERN</p> Signup and view all the answers

<p>Mass mixing mechanism in the electroweak theory</p> Signup and view all the answers

<p>Neutrino mixing and non-vanishing neutrino masses</p> Signup and view all the answers

<p>Successful completion of the first two runs of the LHC</p> Signup and view all the answers

<p>Extreme closeness of the measured Higgs mass to the critical value required for vacuum stability</p> Signup and view all the answers

<p>Gradual disappearance of all anomalies</p> Signup and view all the answers

<p>The hierarchy problem refers to the question of why the Higgs boson mass is so much lighter than the Planck scale, leading to the fine-tuning of parameters in the Standard Model.</p> Signup and view all the answers

<p>The naturalness issue suggests that the parameters in a physical theory should not require excessive fine-tuning to explain observed phenomena.</p> Signup and view all the answers

<p>Recent updates on possible new physics scenarios in supersymmetric models can be found in Ref.</p> Signup and view all the answers

<p>Recent updates on possible new physics scenarios in non-supersymmetric models can be found in Ref.</p> Signup and view all the answers

<p>Chapter 4 is devoted to the theory of strong interactions, Quantum Chromodynamics (QCD).</p> Signup and view all the answers

<p>The experimental status of QCD has evolved from a qualitatively established theory to one that is now firmly established experimentally, although not yet tested to the same precision as the electroweak theory.</p> Signup and view all the answers

<p>The LHC is a hadron collider where every physical process necessarily involves the strong interaction, as it collides protons (or nuclei) and aims to study the Standard Model and search for new physics signals.</p> Signup and view all the answers

<p>It is now possible to understand in detail the structure of pure strong interaction events, in which jets of hadrons are produced in the final state, by looking inside these events and tracing their structure in terms of the fundamental fields of QCD— quarks and gluons.</p> Signup and view all the answers

<p>The determination of the strong coupling itself.</p> Signup and view all the answers

<p>Updated discussions can be found in the QCD review of the PDG, as well as in Ref.</p> Signup and view all the answers

<p>Future, more accurate LHC data, as well as non-perturbative calculations soon expected to become competitive.</p> Signup and view all the answers

<p>The developments have seen a full vindication of the Standard Model as a correct and accurate theory.</p> Signup and view all the answers

<p>The developments have stimulated a vast number of highly sophisticated experimental and theoretical results.</p> Signup and view all the answers

<p>Jets of hadrons are produced in the final state.</p> Signup and view all the answers

<p>Quarks and gluons.</p> Signup and view all the answers

<p>The accuracy on the determination of the strong coupling itself has not improved much.</p> Signup and view all the answers