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.

General Searches and Black Swans at the LHC

by Fabricio Jiménez

Hi again! So, this time I’m going to tell you about two ideas which are fairly new to me but nonetheless interesting (and, I think, closely related): General searches for new phenomena at the Large Hadron Collider (LHC) and Black Swan events.

What Will Happen Next

(By Tommaso Dorigo)

The excitement over the 750 GeV would-be resonance could not be higher these days, with 1) accelerator scientists at the LHC producing collisions in the core of the CMS and ATLAS detectors, 2) theorists producing more and more interpretations of the physics scenarios about to open up, and 3) experimentalists getting ready to jump at the data.

The evidence of #1 is of public domain. As a proof of #2 above, below please find a graph

What if it is real ?

While the flurry of theoretical speculations on the 750 GeV bump spotted by ATLAS and CMS in their 13-TeV diphoton data continues (over 300 papers written to interpret it, in little more than 3 months), the question on whether it is a fluctuation or something else remains on the table, and keeps all of us wondering.

Introdution to SUSY in 5 minutes!

Last week I attended an interesting course about Supersymmetry theory (SUSY) at CP3. The course was meant to be an introduction to SUSY, but in fact it treated this theory in deep detail from a mathematical point of view. It developed all the (endless!) calculations from which the supersymmetric lagrangian can be inferred.

Theories Compared by Number of Papers

Alexander Belyaev gave an inspiring talk at the HEP2016 conference in Valparaiso today. His talk was titled “Interplay of the LHC and DM search in unravelling natural SUSY”. I cannot report his talk here, but I wish to steal a very interesting graph from his presentation.