Is Dark Matter Lurking in Neutron Decays?

by Tommaso Dorigo

A paper by B. Fornal and B. Grinstein published last week in Physical Review Letters is drawing a lot of interest to one of the most well-known pieces of subnuclear physics since the days of Enrico Fermi: beta decay.

The mechanism by means of which a neutron transmutes into a proton has been studied for decades before the neutron was officially discovered (by Chadwick, in 1932). That is because beta decay is at the heart of radioactive processes: nuclei of elements rich with neutrons can turn into others by turning one of their neutrons into a proton, with the emission of an electron and an antineutrino. The details of that reaction were understood thanks to Fermi and a handful of other

Deliverable 4.2 Is Out

by Tommaso Dorigo

I am happy to report that an important new product of the AMVA4NewPhysics ITN is now public. This is generically titled “Report on a Statistical Learning Method for Model-Independent Searches for New Physics“, and labeled D4.2 as per the grant agreement we signed with the European Union. The document is available at the following link:

http://www.pd.infn.it/%7Edorigo/D4.2.pdf

What is this document about ? It is a description of the studies for the development of a software package aiming at automating the searches for new physics in LHC data, by evidencing anomalous clusterings of events that are hard to explain with known physics processes. I am sure that Fabricio and Grzegorz, the two main developers of the software (Deliverable 4.3, available on github at https://github.com/Grzes91/PenalizedAD) and its documentation (D4.2) will be happy to post in this blog a more complete description of the new package and its possible uses in particle physics research.

Things that Decay into Boson Pairs

by Tommaso Dorigo

Writing a serious review of research in particle physics is a refreshing job – all the things that you already knew on that specific topic once sat on a fuzzy cloud somewhere in your brain, and now find their place in a tidily organized space, with clear interdependence among them. That’s what I am experiencing as I progress with a 60-pageish thing on hadron collider searches for diboson resonances, which will appear sometime next year in a very high impact factor journal.

One of the things that the review must cover is a theoretical overview of the models that the searches for these physics processes address. So I thought I would say a few words on this topic here – but bear in

How I Learned to Stop Worrying and Love the Higgs

by Seng-Pei Liew

Recently we have witnessed the birth of gravitational-wave astronomy, as gravitational waves were directly observed for the first time. Subsequently, gravitational waves due to binary neutron star merger were detected along with associated electromagnetic events, opening a new era of multi-messenger astronomy.

Summer activities at LIP-Lisbon

by Giles Strong

So, it’s been a while since my last post, apologies for that, but the summer has been both busy and eventful, so let me summarise what’s been happening.

The Physics of Vector Boson Pairs

by Tommaso Dorigo

At 10:00 AM this morning, my smartphone alerted me that in two months I will have to deliver a thorough review on the physics of boson pairs – a 50 page thing which does not yet even exist in the world of ideas. So I have better start planning carefully my time in the next 60 days, to find at least two clean weeks where I may cram in the required concentration. That will be the hard part!

Because of that, rather than an article about things that I know about boson pairs, this is a post about things I do not know well enough now, but on which my knowledge will see a rapid expansion in the near future. Don’t get me wrong: I know the matter, from the history of research in this interesting sub-field

Recasting new physics searches at the LHC

by Seng-Pei Liew

The AMVA4NewPhysics work package I am involved in is related to developing tools for recasting new physics searches, with a particular focus on multivariate analyses. I would like to explain a little more about it in this article.

Let me begin by describing the motivation to look for new physics at the Large Hadron Collider (LHC). Despite the fact that the Standard Model (SM) of particle physics is very successful at describing most properties of elementary particles, there are many reasons to believe that nature is much more complicated and there is new physics, or physics beyond the Standard Model (BSM). Firstly, there is the hierarchy problem that asks why the electroweak scale or the Higgs mass, 125 GeV can be so light compared to the cutoff scale of the SM, the Planck scale if there is no BSM physics, which is 17 orders of magnitude larger than the electroweak scale. The Higgs mass is unprotected by any symmetry in the SM, and the quantum corrections to its mass are proportional to the cutoff scale. One requires an extreme fine tuning to keep the Higgs boson light while renormalizing the quantum effects, which seems to be totally unnatural. Secondly, as explained previously, there exists dark matter, which is thought by many to be a new type of elementary particle. For these and many other motivations, people are excited at the prospects of discovering BSM physics at the LHC.

Dark Matter Hunting at the LHC

by Seng Pei Liew

Hello there! My name is Seng Pei Liew, and I am the “Marie Sklodowska-Curie Actions” Innovative Training Network (AMVA4NewPhysics) early-stage researcher based at the Technische Universitat Munich (TUM). I am tasked in the network to look for new physics at the Large Hadron Collider (LHC) using advanced statistical tools. In my very first article here, I would like to talk

W Mass: Closing In

by Tommaso Dorigo

After a lot of agonizing work on tiny systematic uncertainties, the ATLAS collaboration released in time for the Moriond conference their latest measurement of the W boson mass (in fact the only one so far). The result is in close match with previous determinations, and has a slightly larger error bar than those. So why bother discussing it here ?

There is a reason. The W boson is one of the most important subatomic particles