Related papers: Light fermions in composite models
In light of null results from New Physics searches at the LHC, we look at unification of the gauge couplings as a model-building principle. As a first step, we consider extensions of the Standard Model with vector-like fermions. We present…
Beyond Standard Model theories describing the electro-weak sector must exhibit a large separation of scales (or "walking") to account for a light, 125 GeV Higgs boson and the fact that so far no other resonances have been observed. Large…
A model is proposed in which quarks, leptons and perhaps gauge bosons are composites of magnetically charged rishons T(q=1/3) and V(q=0) with magnetic charges g=(1,2,-3)g0. Structural formulas of composite particles and their interactions…
The charged fermion masses of the three generations exhibit the two strong hierarchies m_3 >> m_2 >> m_1. We assume that also neutrino masses satisfy m_{nu 3} > m_{nu 2} > m_{nu 1} and derive the consequences of the hierarchical spectra on…
We construct a model of quark and lepton compositeness based on an $SU(15)$ gauge interaction that confines chiral preons, which are also charged under the weakly-coupled $SU(4)_{\rm PS} \times SU(2)_L\times SU(2)_R$ gauge group. The…
In this work, an unquenched quark model is proposed for describing the heavy-light mesons by taking into account the coupled-channel effects induced by chiral dynamics. After including a relativistic correction term for the strong…
We present a method for implementing gauge theories of chiral fermions on the lattice.
A non-supersymmetric grand unified theory can exhibit a "radiative fermion mass hierarchy", in which the heavier quarks and leptons get mass at tree level and the lighter ones get mass from loop diagrams. Recently the first predictive model…
We present new results for light quark masses. The calculations are performed using two flavours of $O(a)$ improved Wilson fermions. We have reached lattice spacings as small as $a \sim 0.07$fm and pion masses down to $m_{\pi} \sim 340$MeV…
Leptogenesis is an appealing framework to account for the baryon asymmetry in the universe. To this end physics beyond the Standard Model is demanded. In this paper we investigate the possibility to attain successful leptogenesis with…
The magnetic polarisabilities of octet baryons are calculated close to the physical quark-mass point using the background field method in lattice QCD. This first calculation draws on the identification and elimination of exceptional…
Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate…
We consider a chiral gauge theory from which light composite Dirac neutrinos dynamically emerge, augmented by a QCD axion to solve the strong CP problem. We show that an interplay between the composite sector and the axion can also…
We propose a class of dark matter models based on a chiral $U(1)$ gauge symmetry acting on a dark sector. The chiral $U(1)$ protects the masses of the dark sector fermions, and also guarantees the stability of the dark matter particle by…
If electroweak symmetry breaking arises via strongly-coupled physics, the observed suppression of flavour-changing processes suggests that fermion masses should arise via mixing of elementary fermions with composite fermions of the strong…
Work in progress is reported on a particularly interesting gauge theory with a fermion doublet in the two-index symmetric (sextet) representation of the SU(3) color gauge group. Extending previous studies we outline our strategy as we…
We investigate a proposal for the construction of models with chiral fermions on the lattice using staggered fermions. In this approach the gauge invariance is broken by the coupling of the staggered fermions to the gauge fields. We aim at…
A unified form of mass matrix is proposed for neutrinos, charged leptons, up quarks and down quarks. Some constraints for the parameters involved are tent% atively postulated. Then, the predictions are neatly consistent with available…
We present a study of chiral behavior of light meson form factors in QCD with three flavors of overlap quarks. Gauge ensembles are generated at single lattice spacing 0.12 fm with pion masses down to 300 MeV. The pion and kaon…
In the past year domain wall fermion simulations have moved from exploratory stages to the point where systematic effects can be studied with different gauge couplings, volumes, and lengths in the fifth dimension. Results are presented here…