A foray into creative writing

by Andrea Giammanco

Tommaso encouraged me some time ago to advertise here my own blog, although it is not written in English, and so I do:

Particelle stabili cariche e massice (i.e. Heavy stable charged particles; sub-title: Quindi non era un problema di calibrazione?, i.e. Are you saying it was not a calibration issue?)

It is a sci-fi story based at CERN, which unfolds (not in that sense) between 2019 and 2022, although the narrator is writing in 2042 and assumes therefore that his contemporary readers are aware of many facts that the protagonists cannot know yet.

My goal is

Lost in unfolded space – last episode: “Thou shalt not unfold”

by Andrea Giammanco

This is the end of my unfolding series, whose previous episodes can be found here, here, and here.

This post discusses when we should apply unfolding to our data, and when not.

There is an interesting thing about the unfolding community: when you ask an expert for practical advice, the expert typically starts by asking why you think you need unfolding, and will in general discourage you from doing it.

Some time ago, a mini-workshop on unfolding techniques was organized by a group inside CMS. I was quite interested

Lost in unfolded space – part III: “Let a hundred flowers bloom, let a hundred schools of thought contend” (Mao Tse-Tung)

by Andrea Giammanco

In the first episode of this series of posts I tried to convey the simplicity of the unfolding problem; in the second I warned against the dire consequences of treating it a bit too simply.

This third post is about a few of the methods that are most popular in experimental HEP (although usually originated outside of HEP) to address the problem.

First of all, a reminder of the problem that we are trying to solve

Lost in unfolded space – part II: “and then I accidentally divided by zero…”

by Andrea Giammanco

In my previous post I drove you from the safe land of The Truth to the so called “smeared space” (i.e., what is actually observable), where things are murky and brown, and then back to the “unfolded space”, which resembles your point of departure, but with some noise due to the amount of information that was lost in the process.

I started with a two-bin measurement that only demands to invert a 2×2 matrix. The most advanced mathematics

Lost in unfolded space – part I

by Andrea Giammanco

This series of posts is about an ill-posed mathematical problem, and will marginally touch particle physics and management decisions in HEP analysis groups.

The ill-posed problem is the so called “unfolding” problem. Saying ill-posed is not a judgment about the value of the problem but it has to be intended in the mathematical meaning. (Although many colleagues