Related papers: Bounds on Flavor Gauge Bosons from Precision Elect…
We report new results for a frequently discussed gauge theory with twelve fermion flavors in the fundamental representation of the SU(3) color gauge group. The model, controversial with respect to its conformality, is important in…
We consider a recent proposal by Dimopoulos and Kaplan to embed the electroweak SU(2)_L X U(1)_Y into a larger group SU(3)_W X SU(2) X U(1) at a scale above a TeV. This idea is motivated by the prediction for the weak mixing angle sin^2…
In supersymmetric theories with a strong conformal sector, soft supersymmetry breaking at the TeV scale naturally gives rise to confinement and chiral symmetry breaking at the same scale. We investigate models where such a sector…
We examine the constraints coming from incorporating the full Standard Model gauge symmetry into the effective field theory description of flavor processes, using semileptonic decays as paradigmatic examples. Depending on the dynamics…
The last years have seen a great development in our understanding of particle physics at the weak scale. Precision electroweak observables have played a key role in this process and their values are consistent, within the Standard Model…
Summary of electroweak Standard Model, including aspects of gauge summetry, symmetry breaking, and quantum radiative corrections. Implications of precise electroweak measurements for Standard Model and hypothetical non-Standard states and…
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…
Direct searches and the hints for the Higgs at ~125 GeV put increasing pressure on simple models of SUSY breaking, in particular (but not exclusively) on those that automatically solve the flavour problem, such as gauge mediation.…
We analyze various models with an extra U(1) gauge symmetry in addition to the Standard Model (SM) gauge group at low energies, and impose limits on the mass of the neutral Z' boson, M_Z', predicted in all such models, and on the Z-Z'…
The $W$ boson mass is one of the most important electroweak precision observables for testing the Standard Model or its extensions. The very recent measured $W$ boson mass at CDF shows about $7\sigma$ deviations from the SM prediction,…
The ununified standard model is an extension of the standard model that contains separate electroweak gauge groups for quarks and leptons. When it was originally proposed, data allowed the new gauge bosons to be quite light. We use recent…
Using precision electroweak data, we put limits on ``natural'' top-color assisted technicolor models. Generically the new $U(1)$ gauge bosons in these models must have masses larger than roughly 2 TeV, although in certain (seemingly…
We find that, at order alpha_s, the partial width of Z^0 to heavy flavors receives a power correction from a novel QCD mechanism, which is not suppressed by inverse powers of M_Z, but only by two unknown O(\lambdaqcd/m) constants. The…
A revised and complete list of the electroweak chiral lagrangian operators up to dimension-four is provided. The connection of these operators to the $S$, $T$ and $U$ parameters and the parameters describing the triple gauge boson vertices…
Flavor-breaking interactions due to heavy new physics can be probed at a 10 TeV muon collider in the high-energy production of quarks and leptons. The high collision energy mitigates the suppression of the new interactions, offering…
We review and update current limits on possible anomalous couplings of the top quark to gauge bosons. We consider data from top quark decay (as encoded in the $W$-boson helicity fractions) and single-top production (in the $t$-, $s$- and…
We consider the extended electroweak gauge group SU(2)_1 \times SU(2)_2 \times U(1)_Y where the first and second families of fermions couple to SU(2)_1 while the third family couples to SU(2)_2. Bounds based an precision electroweak…
We show how precision electroweak data, assuming CP conservation and flavor universality, despite being sensitive to 20 dimension 6 operators, constrain severely only 9 combinations of them. We define a set of 7 oblique parameters $\hat S,…
We present new results on chiral symmetry breaking in nearly conformal gauge theories with fermions in the fundamental representation of the SU(3) color gauge group. The number of fermion flavors is varied in an extended range below the…
We have witnessed some flavor anomalies appeared in the past years, and explanations based on extended gauge sectors are among the most popular solutions. These beyond the Standard Model (SM) theories often assume flavor changing…