Article
Extra vectorlike matter and the lightest Higgs scalar boson mass in lowenergy supersymmetry
Physical review D: Particles and fields 01/2010; 81(3):035004035004. DOI: 10.1103/PHYSREVD.81.035004
Source: arXiv

Article: LHC signatures of vectorlike quarks
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ABSTRACT: This work provides an overview on the current status of phenomenology and searches for heavy vectorlike quarks, which are predicted in many models of new physics beyond the Standard Model. Searches at Tevatron and at the LHC, here listed and shortly described, have not found any evidence for new heavy fermionic states (either chiral or vectorlike), and have therefore posed strong bounds on their masses: depending on specific assumptions on the interactions and on the observed final state, vectorlike quarks with masses up to roughly 400600 GeV have been excluded by all experiments. In order to be as simple and modelindependent as possible, the chosen framework for the phenomenological analysis is an effective model with the addition of a vectorlike quark representation (singlet, doublet or triplet under SU(2)) which couples through Yukawa interactions with all SM families. The relevance of different observables for the determination of bounds on mixing parameters is then discussed and a complete overview of possible twobody final states for every vectorlike quark is provided, including their subsequent decay into SM particles. A list and short description of phenomenological analyses present in literature is also provided for reference purposes.Advances in High Energy Physics 07/2012; 2013. · 3.50 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: In the framework of gauged flavour symmetries, new fermions in parity symmetric representations of the standard model are generically needed for the compensation of mixed anomalies. The key point is that their masses are also protected by flavour symmetries and some of them are expected to lie way below the flavour symmetry breaking scale(s), which has to occur many orders of magnitude above the electroweak scale to be compatible with the available data from flavour changing neutral currents and CP violation experiments. We argue that, actually, some of these fermions would plausibly get masses within the LHC range. If they are taken to be heavy quarks and leptons, in (bi)fundamental representations of the standard model symmetries, their mixings with the light ones are strongly constrained to be very small by electroweak precision data. The alternative chosen here is to exactly forbid such mixings by breaking of flavour symmetries into an exact discrete symmetry, the socalled protonhexality, primarily suggested to avoid proton decay. As a consequence of the large value needed for the flavour breaking scale, those heavy particles are longlived and rather appropriate for the current and future searches at the LHC for quasistable hadrons and leptons. In fact, the LHC experiments have already started to look for them.Journal of High Energy Physics 12/2011; 2012(2). · 5.62 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We establish that the light Higgs boson mass in the context of the NoScale Flipped SU(5) GUT with TeV scale vectorlike matter multiplets (flippons) is consistent with m_h = 125.5+0.5 GeV in the region of the best supersymmetry (SUSY) spectrum fit to low statistics data excesses observed by ATLAS in multijet and light stop 5/fb SUSY searches at the LHC7. Simultaneous satisfaction of these disparate goals is achieved by employing a minor decrease in the SU(5) partial unification scale M_{32} to lower the flippon mass, inducing a larger Higgs boson mass shift from the flippon loops. The reduction in M_{32}, which is facilitated by a phenomenologically favorable reduction of the lowenergy strong coupling constant, moreover suggests an imminently observable (emu)^+ pi^0 proton decay with a central value time scale of 1.7x10^34 years. At the same point in the model space, we find a lightest neutralino mass of m_{\chi} = 145 GeV, which is suitable for the production of 130 GeV monochromatic gammarays through annihilations yielding associated Zbosons; a signal with this energy signature has been identified within observations of the galactic center by the FERMILAT Space Telescope. In conjunction with direct correlations to the fate of the ATLAS multijet and light stop production channels presently being tested at the LHC8, we suggest that the reality of a 125.5 GeV Higgs boson affords a particularly rich company of specific and imminently testable associated observables.European Physical Journal C 08/2012; 72(12). · 5.25 Impact Factor
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