1) Is the Higgs like candidate ATLAS/CMS observe a SM Higgs? The Higgs particle is important since it is (like neutrinos) a portal or gate into New Physics. New particles couple naturally to fundamental scalars, so SM deviations can be … Continue reading

# Category Archives: SM

What is the SM? What it does?What is not the SM? What it does not? 1) A local relativistic quantum field theory describing matter-energy and the electroweak and strong interactions up to a distance . It is a “correct”, “effective” … Continue reading

The weak scale and the weak angle The Fermi constant is defined through a beautiful and simple mathematical formula: This formula for the Fermi constant was very important in the long path towards the EW unification since knowing the Fermi … Continue reading

The above picture is a cool mind map by the cosmologist and particle physicist Sean Carroll. It summaries somehow the phenomenological charges of the Standard Model plus the gravitational sector we do not know at quantum level. Physical Higgs sector … Continue reading

The total SM lagrangian can be written now, with some subtle notational changes, from the previous posts. It is really a monster “thing”: From what you have learned in previous log-entries, can you identify the meaning of every lagrangian piece … Continue reading

Gauge theories require that we select “a gauge” in order to calculate physical observables. That is, you have to fix the gauge to eliminate field configurations that are physically equivalent ( they can not be distintinguished, as field configurations). The … Continue reading

We have seen that the SM, under general considerations such as gauge invariance and renormalizability, does NOT initially allow EXPLICIT mass terms in the lagrangian framework for the gauge bosons AND/OR the chiral fermions. Note that every SM fermions is … Continue reading

The above picture is the EW lagrangian! Is it simple? Is it beautiful? It depends on your taste! It is called the GSW (Glashow-Salam-Weinberg) lagrangian. The electroweak (EW) part/theory is based on the gauge symmetry group. Before spontaneous symmetry breaking, … Continue reading

QCD or Quantum ChromoDynamics acts on quarks and hadrons (both baryons and mesons, “colored” particles). There are lots of baryons and mesons, and I have listed some of them in the two tables above as “an apetizer”. Please, remeber that … Continue reading

What is the Standard Model? We are going to study this theory in a long series of blog posts. I don’t pretend to be completely exhaustive but a starting point even for the layman. I do want to review what … Continue reading