Review of physics results from the Tevatron: Searches for new particles and interactions

Abstract

We present a summary of results for searches for new particles and interactions at the Fermilab Tevatron collider by the CDF and the D0 experiments. These include results from Run I as well as Run II for the time period up to July 2014. We focus on searches for supersymmetry, as well as other models of new physics such as new fermions and bosons, various models of excited fermions, leptoquarks, technicolor, hidden-valley model particles, long-lived particles, extra dimensions, dark matter particles, and signaturebased searches. a Note that for simplicity, when we say we are looking for a model, like SUSY, we are looking for evidence of new particles and/or interactions. September 18, 2014 0:22 NP˙review˙v3 4 D. Toback, L.Živkovićissues, like production mechanisms, decay products, final states and relevant models parameters are discussed in sections 4 and 5. SupersymmetryThe motivations for SUSY are well known and documented 4-7 and include its ability to potentially solve hierarchy problem for the Higgs boson mass, provide a dark matter candidate, and satisfy consistency requirements of modern models of string theory. Inherent in the theory is that for every fermion observed in the SM there is a supersymmetric boson partner that has not yet been observed; the same is true for the known bosons, including the observed Higgs boson, and the hypothetical graviton (the particle mediator of gravity). The non-observation of low-mass sparticles with equal masses to their SM counterparts has focused efforts on SUSY models with broken symmetry.Since there are many new particles to be searched for, and a 128 free parameters in the most general models, other "clues" and possible tie-ins have been used by model builders to focus on weak-scale SUSY. 8 The hallmark of these SUSY models is their ability to provide a dark matter candidate, and not contradict other observations. 9 Since experimental results from the proton and electron lifetime measurements imply conservation of baryon number and lepton number, it is not unreasonable that SUSY has an additional symmetry, known as R-parity b . If R-parity is conserved this has the consequence that the lightest SUSY particle (LSP) must be stable, potentially making it a dark matter candidate. We note for now that for many SUSY models the LSP couple to normal matter with a tiny strength and when produced in a collision, it would leave the detector without a trace, yielding significant missing transverse energy, E T , giving a signature for SUSY that is searched for in many models.With this in mind we quickly mention the models focused on at the Fermilab Tevatron collider which are typically selected for simplicity and general features. These include: (i) gravity-mediated SUSY breaking (minimal SuperGravity or mSUGRA) type models, where the lightest neutralino is the LSP, has a mass at the electroweak scale and becomes a natural cold-dark matter candidate (discussed in section 4.1), (ii) gauge-mediated SUSY breaking models (GMSB) which have a ∼keV mass gravitino as the LSP, and often h...

Fermionic extensions of the Standard Model in light of the Higgs couplings

“…When the Large Hadron Collider (LHC) began its data taking, possible extensions of the Standard Model (SM) at the TeV scale were already severely constrained: electroweak (EW) precision measurements accurately confirmed the structure of the gauge sector [1][2][3], a number of flavour violating observables showed no significant deviation from the SM predictions [4,5], all direct searches of non-standard particles at LEP and Tevatron gave null results [2,6,7]. After the first run of the LHC, the lower bounds on the masses of new particles increased substantially [8,9].…”

The Quest for Dark Matter with Neutrino Telescopes

“…However, the lack of evidence so far for supersymmetry from direct searches, first at LEP [10], then at the Tevatron [11] and more recently at the LHC [12], has restricted the allowed phase space of the theory and raised the supersymmetric particle mass scale to the O(TeV) region. There are other flavours of supersymmetry, like the phenomenological MSSM (pMSSM) [13] or the Next-to-Minimal Supersymmetric Standard Model (NMSSM) [14] which can still accommodate WIMPs down to the few GeV region.…”