In this two-parts article I wish to describe in some detail, but still at an elementary level, the characteristics of one of the most important probes of the physics of subnuclear collisions at today's particle physics experiments: jets of hadrons originated from energetic bottom quarks, or more familiarly, b-jets. By posting a dedicated article on b-jets, I hope I will be able to describe in more detail elsewhere other physics topics, such as Higgs boson decays or top quark signatures, without being hampered by having to introduce the phenomenology and detection of b-jets from scratch every time.

As silly as it may look, I am going to start this post by publishing for the third time in a row the same figure. That is because I want to keep the promise I made earlier that I would explain in terms as simple as possible (although not simpler) the details hidden behind the coloured curves and functions pictured there. I will also take this chance to come down a little from the level of technicality of the recent posts: after all, this blog is supposedly for everybody, and not just for Ph.D. students and recipients.

Yesterday I posted a short article whose main purpose was to show a figure I had received from Sven Heinemeyer, a phenomenologist who specializes in the study of Minimal Supersymmetric extensions of the Standard Model (MSSM).

Besides predicting a mirror copy of Standard Model (SM) particles, MSSM models are characterized by containing not just one, but five distinct Higgs bosons; over much of the space of possible parameters of these theories, one of the five Higgs bosons is quite similar to the one and only SM Higgs, so that one can discuss the SM Higgs and the lightest neutral scalar of the MSSM together without generating confusion.

...waiting for a piece I will post tomorrow, to stimulate your curiosity -and allow me to travel from Venice to Patras by ship, with no internet connection.

The subject is not only the Higgs mass, but the top quark mass. Which top mass ? The "pole" mass -the real part of the pole in the perturbative top-quark propagator. Have I lost you ? Ok, do not worry -definitions are for theorists. Let us just say that the top quark, being a complicated coloured object which thus cannot live free of the influence of strong interactions,
is measurable at a hadron collider like the Tevatron only within uncertainties of the order of a constant called "Lambda QCD", which is of the order of 200 MeV.