相关论文: Weak-Singlet Fermions: Models and Constraints
We provide a set of theoretical constraints on models in which the Standard Model field content is extended by vector-like fermions and in some cases also by a real scalar singlet. Our approach is based on the study of electroweak vacuum…
If the electroweak symmetry is broken by some unspecified strong dynamics, composite fermions may exist with definite transformation properties under SU(2)_L x SU(2)_R/SU(2)_{L+R} and may play a role in giving masses by mixing to all the…
There has been renewed interest in the possibility of additional fermion generations. At the same time there have been significant changes in the relevant electroweak precision constraints, in particular, in the interpretation of several of…
We investigate the mixing of an extra ${Z^0}^\prime$ with the standard $Z^0$ and mixings of exotic fermions with their standard counterparts through some precisely measured electroweak observables. These observables are geared to search for…
We calculate the oblique electroweak corrections and confront with the experiments in an extension of the Standard Model. The new fields added are a vector-like weak doublet and a singlet fermion. After electroweak symmetry breaking there…
The ATLAS and CMS collaborations at the LHC have performed analyses on the existing data sets, studying the case of one vector-like fermion or multiplet coupling to the standard model Yukawa sector. In the near future, with more data…
Many models of Beyond the Standard Model physics involve heavy colored fermions. We study models where the new fermions have vector interactions and examine the connection between electroweak precision measurements and Higgs production. In…
The S,T, and U formalism for studying electroweak precision data has recently been updated to include the effects of new light physics and within this analysis the latest LEP and SLC data tightly constrain models of physics beyond the…
The constraints on the mixing angles of the standard fermions with new heavy particles that can appear in many extensions of the electroweak theory are reviewed. Some emphasis is put in distinguishing the effects of a mixing with new states…
Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of…
In a variety of supersymmetric extensions of the Standard Model, the scalar partners of the quarks and leptons are predicted to be very heavy and beyond the reach of next-generation colliders. For instance, the realization of electroweak…
The successful description of current data provided by the Standard Model includes fundamental fermions that are color-singlets and electroweak-nonsinglets, but no fermions that are electroweak-singlets and color-nonsinglets. In an effort…
Electroweak precision tests of the Standard Model of the fundamental interactions are reviewed ranging from the lowest to the highest energy experiments. Results from global fits are presented with particular emphasis on the extraction of…
We calculate the oblique electroweak corrections and confront them with the experiments in a composite Higgs version of the standard model. A vector-like weak doublet and a singlet fermion are added to the standard model without elementary…
We study symmetry breaking in a left-right symmetric extension of the Standard Model with mirror fermions, one for each Standard-Model fermion. The new particles assist a top-quark condensate in breaking electro-weak symmetry. Half of the…
We study extensions of the Standard Model with general new vector bosons. The full Standard Model gauge symmetry is used to classify the extra vectors and constrain their couplings. We derive the corresponding effective Lagrangian, valid at…
In light of recent data from direct detection experiments and the Large Hadron Collider, we explore models of dark matter in which an SU(2) doublet is mixed with a Standard Model singlet. We impose a thermal history. If the new particles…
While a chiral fourth generation of quarks is almost ruled out from the data on Higgs boson production and decay at the Large Hadron Collider, vector-like quarks are still a feasible option to extend the fermionic sector of the Standard…
We consider fermionic and scalar dark matter (DM) candidates that couple predominantly to third-generation Standard Model fermions, describing their interactions within an effective field theory framework. We show that current…
As the Higgs boson properties settle, the constraints on the Standard Model extensions tighten. We consider all possible new fermions that can couple to the Higgs, inspecting sets of up to four chiral multiplets. We confront them with…