Dark matter and electroweak symmetry breaking in models with warped extra dimensions

Self Cite

176

230

We analyze the corrections to the precision EW observables in minimal composite Higgs models by using a general effective parametrization that also includes the lightest fermionic resonances. A new, possibly large, logarithmically divergent contribution to S is identified, which comes purely from the strong dynamics. It can be interpreted as a running of S induced by the non-renormalizable Higgs interactions due to the nonlinear σ-model structure. As expected, the corrections to the T parameter coming from fermion loops are finite and dominated by the contributions of the lightest composite states. The fit of the oblique parameters suggests a rather stringent lower bound on the σ-model scale f 750 GeV. The corrections to the Zb L b L vertex coming from the lowest-order operators in the effective Lagrangian are finite and somewhat correlated to the corrections to T . Large additional contributions are generated by contact interactions with 4 composite fermions. In this case a logarithmic divergence can be generated and the correlation with T is removed. We also analyze the tree-level corrections to the top couplings, which are expected to be large due to the sizable degree of compositeness of the third generation quarks. We find that for a moderate amount of tuning the deviation in V tb can be of order 5% while the distortion of the Zt L t L vertex can be 10%.

Section: Jhep10(2013)160mentioning

confidence: 99%

Light top partners and precision physics

Grojean

Matsedonskyi

Panico

2013

Self Cite

176

230

“…The introduction of more sets of fermionic composites is inspired by the five-dimensional model presented in [37], which does not seem to suffer from such severe constraints. In [31], it was shown that a four-dimensional composite Higgs model with two multiplets of fermionic resonances is compatible with EWPT in large regions of parameter space.…”

Section: The Fermionic Sectormentioning

confidence: 99%

Gluon-fusion Higgs production at NNLO for a non-standard Higgs sector

Furlan¹

2011

Abstract:We consider an extension of the Standard Model with an arbitrary number of heavy quarks having general couplings to the Higgs boson. We construct an effective Lagrangian integrating out quarks that are heavier than half the mass of the Higgs boson and compute the Wilson coefficient for the effective gluon-Higgs vertex through NNLO. We apply our result to a composite Higgs model with vector-like quarks coupling to the third generation quarks. In the heavy quark-mass approximation, we show that the suppression of the leading-order cross section with respect to the Standard Model does not depend on the number of vector-like multiplets introduced. We analyse the effects of QCD and electroweak corrections through three loops, as well as bottom-quark contributions through two loops.

“…It also features a very strong potential for the discovery or exclusion of new physics/particles, thus opening the possibility of investigating both strongly and weakly coupled extensions of the Standard Model. New vector-like (VL) fermions are often present in many of the extensions of the SM, especially in relation with the top sector (top partners, as for example in composite Higgs models [1][2][3][4], extradimensional models [5][6][7][8][9][10][11], little Higgs models [12][13][14], gauge-Higgs models [15,16], gauge coupling unification [17,18] and models with an extended custodial symmetry [19,20]). Both CMS [21] and ATLAS [22] have recently devoted a considerable effort in the analyses apt to setting bounds on this type of new particles.…”

Section: Introductionmentioning

confidence: 99%

Interplay of vector-like top partner multiplets in a realistic mixing set-up

Cacciapaglia

Deandrea

Gaur

et al. 2015

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 available, these experimental collaborations will start to investigate more realistic cases. The presence of more than one extra vector-like multiplet is indeed a common situation in many extensions of the standard model. The interplay of these vector-like multiplet between precision electroweak bounds, flavour and collider phenomenology is a important question in view of establishing bounds or for the discovery of physics beyond the standard model. In this work we study the phenomenological consequences of the presence of two vector-like multiplets. We analyse the constraints on such scenarios from tree-level data and oblique corrections for the case of mixing to each of the SM generations. In the present work, we limit to scenarios with two top-like partners and no mixing in the down-sector.