No Arabic abstract
Between the years 2015 and 2019, members of the Horizon 2020-funded Innovative Training Network named AMVA4NewPhysics studied the customization and application of advanced multivariate analysis methods and statistical learning tools to high-energy physics problems, as well as developed entirely new ones. Many of those methods were successfully used to improve the sensitivity of data analyses performed by the ATLAS and CMS experiments at the CERN Large Hadron Collider; several others, still in the testing phase, promise to further improve the precision of measurements of fundamental physics parameters and the reach of searches for new phenomena. In this paper, the most relevant new tools, among those studied and developed, are presented along with the evaluation of their performances.
The Large Hadron Collider presents an unprecedented opportunity to probe the realm of new physics in the TeV region and shed light on some of the core unresolved issues of particle physics. These include the nature of electroweak symmetry breaking, the origin of mass, the possible constituent of cold dark matter, new sources of CP violation needed to explain the baryon excess in the universe, the possible existence of extra gauge groups and extra matter, and importantly the path Nature chooses to resolve the hierarchy problem - is it supersymmetry or extra dimensions. Many models of new physics beyond the standard model contain a hidden sector which can be probed at the LHC. Additionally, the LHC will be a top factory and accurate measurements of the properties of the top and its rare decays will provide a window to new physics. Further, the LHC could shed light on the origin of neutralino masses if the new physics associated with their generation lies in the TeV region. Finally, the LHC is also a laboratory to test the hypothesis of TeV scale strings and D-brane models. An overview of these possibilities is presented in the spirit that it will serve as a companion to the Technical Design Reports (TDRs) by the particle detector groups ATLAS and CMS to facilitate the test of the new theoretical ideas at the LHC. Which of these ideas stands the test of the LHC data will govern the course of particle physics in the subsequent decades.
Convincing and direct evidence for dark matter (DM) on galactic scales comes from the observation of the rotation curves of galaxies. At particle colliders, searches for DM involve the production of a pair of stable electrically neutral and weakly interacting particles with a signature of missing transverse energy ($E^{rm T}_{rm miss}$) recoiling against a SM particle. The resulting signature yields a final state denoted as X+$E^{rm T}_{rm miss}$, where the SM particle X is emitted as initial state radiation. The Higgs boson discovery at the LHC opens a new window into the searches for new physics processes beyond the SM through the h+$E^{rm T}_{rm miss}$ signature, as a direct probe of the interaction involving DM particles. Due to the small Yukawa couplings to quarks and gluons, the initial state radiation of the Higgs boson is suppressed, but it can be produced in the case of a new interaction with DM particles. Searches for DM particles produced in association with the Higgs boson are discussed. They are based on proton-proton collision data at the LHC in different final states.
The high energy programme of the HERA collider ended in March 2007. During the whole HERA programme, a combined total integrated luminosity of 1 fb$^{-1}$ was collected by the H1 and ZEUS experiments. In this context, an overview of the most recent results of both experiments concerning searches for new physics is presented. The topics covered are searches for contact interactions, leptoquarks and excited leptons, as well as studies of the isolated lepton and multi-lepton topologies, and a general signature based search.
This paper reviews the most recent results on searches for physics beyond the Standard Model at Tevatron. Both the collider experiments: CDF and DO are performing a large variety of searches such as searches for scalar top and scalar bottom particles, search for new gauge bosons, search for long-lived massive particles and general searches for new particles decaying into dijets. The results, summarized here, are a selection of what obtained recently by both the collaborations using the Run II data, collected so far.
This review focuses on the expected performance of the ATLAS and CMS detectors at the CERN Large Hadron Collider (LHC), together with some of the highlights of the global commissioning work done in 2008 with basically fully operational detectors. A selection of early physics measurements, expected to be performed with the data taken in 2009/2010 is included for completion, together with a brief reminder of the ultimate physics potential of the LHC.