Scalar boson

A scalar boson is a boson whose spin equals zero. A boson is a particle whose wave function is symmetric under particle exchange and therefore follows Bose–Einstein statistics. The spin–statistics theorem implies that all bosons have an integer-valued spin. Scalar bosons are the subset of bosons with zero-valued spin. The name scalar boson arises from quantum field theory, which demands that fields of spin-zero particles transform like a scalar under Lorentz transformation (i.e. are Lorentz invariant). A pseudoscalar boson is a scalar boson that has odd parity, whereas "regular" scalar bosons have even parity. Examples Scalar

The only fundamental scalar boson in the Standard Model of particle physics is the Higgs boson, the existence of which was confirmed on 14 March 2013 at the Large Hadron Collider by CMS and ATLAS. As a result of this confirmation, the 2013 Nobel Prize in physics was awarded to Peter Higgs and François Englert.
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PHYS-416: Particle physics II

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.

PHYS-415: Particle physics I

Presentation of particle properties, their symmetries and interactions. Introduction to quantum electrodynamics and to the Feynman rules.

The S-matrix Bootstrap Reloaded

Aditya Hebbar

Quantum field theories (QFTs) are the backbone upon which the edifice of modern physics is built. In this thesis we explore the S-matrix bootstrap which is a non-perturbative method that constrains the vast space of QFTs by using consistency conditions that they must satisfy. The thesis is divided into two parts.In part I of the thesis we study the S-matrix bootstrap for particles with spin in 4 spacetime dimensions and apply the formalism to scattering of identical Majorana fermions to estimate bounds on their quartic couplings and their cubic (Yukawa) coupling to scalar particles. In part II of the thesis, we consider the scattering of massless (Goldstone) excitations on a long flux tube. We use the S-matrix bootstrap to constrain Wilson coefficients of higher dimension operators in the low energy flux tube effective field theory. These constraints naturally translate to bounds on the ground state and excited state energy levels of long flux tubes. The techniques used in this thesis should be extendable to many other systems, both massive and massless. We conclude by discussing some of these possibilities.

EPFL2021

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Electric dipole moment constraints on CP-violating heavy-quark Yukawas at next-to-leading order

Emmanuel Stamou

Electric dipole moments are sensitive probes of new phases in the Higgs Yukawa couplings. We calculate the complete two-loop QCD anomalous dimension matrix for the mixing of CP-odd scalar and tensor operators and apply our results for a phenomenological study of CP violation in the bottom and charm Yukawa couplings. We find large shifts of the induced Wilson coefficients at next-to-leading-logarithmic order. Using the experimental bound on the electric dipole moments of the neutron and mercury, we update the constraints on CP-violating phases in the bottom and charm quark Yukawas.

SPRINGER2021

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Electrical conductivity of hot Abelian plasma with scalar charge carriers

Oleksandr Sobol

We study the electrical conductivity of hot Abelian plasma containing scalar charge carriers in the leading logarithmic order in coupling constant alpha using the Boltzmann kinetic equation. The leading contribution to the collision integral is due to the Moller and Bhabha scattering of scalar particles with a singular cross section in the region of small momentum transfer. Regularizing this singularity by taking into account the hard thermal loop corrections to the propagators of intermediate particles, we derive the second order differential equation which determines the kinetic function. We solve this equation numerically and also use a variational approach in order to find a simple analytical formula for the conductivity. It has the standard parametric dependence on the coupling constant sigma approximate to 2.38T/(alpha log alpha(-1)) with the prefactor taking a somewhat lower value compared to the fermionic case. Finally, we consider the general case of hot Abelian plasma with an arbitrary number of scalar and fermionic particle species and derive the simple analytical formula for its conductivity.

2019

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Modèle standard de la physique des particules

vignette|upright=2.0|Modèle standard des particules élémentaires avec les trois générations de fermions (trois premières colonnes), les bosons de jauge (quatrième colonne) et le boson de Higgs (cinqui

Boson de Higgs

thumb|De gauche à droite : Kibble, Guralnik, Hagen, Englert et Brout, en 2010. Le boson de Higgs ou boson BEH, est une particule élémentaire dont l'existence, postulée indépendamment en juin 1964 par

Méson

Un méson est, en physique des particules, une particule composite (c’est-à-dire non élémentaire) composée d'un nombre pair de quarks et d'antiquarks. Le terme « méson » vient du grec , meson, qui s