The Hunt for New Physics at the Large Hadron Collider

Abstract

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.Comment: Summary document for international workshop "Beyond the Standard Model at the LHC" (Pre-SUSY09), Northeastern University, Boston, June 2-4, 200

LHC bounds on lepton number violation mediated by doubly and singly-charged scalars

“…Thus, although in the see-saw of type II neutrino masses are proportional to the corresponding doubly-charged scalar decays [52,53,80,81], in general they are not closely related and more elaborated models can accommodate both independently of their specific values. At any rate, along this paper our approach to LHC searches will be mainly phenomenological and hence largely model independent.…”

Maximal electric dipole moments of nuclei with enhanced Schiff moments

“…in terms of the isoscalarḡ (0) πN N , isovectorḡ (1) πN N , and isotensorḡ (2) πN N T-violating pionnucleon couplings. The Schiff moment is linear in the CP-odd πN N couplingsḡ (i) πN N , and may be written as [19] …”

“…The contribution of the four-fermion interactions to the isoscalar couplingḡ (0) πN N is ignored and the isotensor couplingḡ (2) πN N , which changes the isospin by two units, is neglected in this work (as in ref. [28]), since it can be generated only at the expense of an additional m u − m d suppression.…”

“…Electric dipole moments (EDMs) are among the most promising potential signatures for CP-violating physics beyond the Standard Model (SM), and one of the most promising options for extending the SM is provided by supersymmetry (SUSY) (for recent reviews, see [1,2]). The minimal SUSY extension of the SM (the MSSM) already contains many possible CP-violating phases, even in its minimally flavour-violating (MFV) version.…”

LHC top partner searches beyond the 2 TeV mass region

“…Many available methods for boosted top tagging exist in the literature (see for instance refs. [15,16,18,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] and references therein). In addition, several interesting proposals for boosted W tagging appeared recetly in refs.…”