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Register a new userThe Electroweak Model based on the Nonlinearly realized Gauge Group. Theoretical Foundations and Phenomenological Prospects
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A consistent strategy for the subtraction of the divergences in the nonlinearly realized Electroweak Model in the loop expansion is presented. No Higgs field enters into the perturbative spectrum. The local functional equation (LFE), encoding the invariance of the SU(2) Haar measure under local left SU(2) transformations, the Slavnov-Taylor identity, required in order to fulfill physical unitarity, and the Landau gauge equation hold in the nonlinearly realized theory. The quantization is performed in the Landau gauge for the sake of simplicity and elegance. The constraints on the admissible interactions arising from the Weak Power-Counting (WPC) are discussed. The same symmetric pattern of the couplings as in the Standard Model is shown to arise, as a consequence of the defining functional identities and the WPC. However, two independent mass invariants in the vector meson sector are possible, i.e. no tree-level Weinberg relation holds between the Z and W mass. Majorana neutrino masses can be implemented in the nonlinearly realized Electroweak Model in a way compatible with the WPC and all the symmetries of the theory.
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We consider a minimal nonlinearly realized electroweak theory where mass generation happens `a la Stueckelberg. Deformation of the nonlinearly realized gauge symmetry is controlled by functional methods. The Weak Power Counting allows to select uniquely the Hopf algebra of the theory and gives definite predictions on the Beyond-the-Standard Model (BSM) sector of the theory: the latter includes one CP-odd and two charged physical scalars (in addition to the Higgs-like CP-even resonance). The model interpolates between a purely Stueckelberg and a Higgs scenario. It can be used in order to check whether the presence of a Stueckelberg mass component can already be excluded on the basis of the existing LHC7-8 data.
In this paper we evaluate the self-energy of the vector mesons at one loop in our recently proposed subtraction scheme for massive nonlinearly realized SU(2) Yang-Mills theory. We check the fulfillment of physical unitarity. The resulting self-mass can be compared with the value obtained in the massive Yang-Mills theory based on the Higgs mechanism, consisting in extra terms due to the presence of the Higgs boson (tadpoles included). Moreover we evaluate all the one-loop counterterms necessary for the next order calculations. By construction they satisfy all the equations of the model (Slavnov-Taylor, local functional equation and Landau gauge equation). They are sufficient to make all the one-loop amplitudes finite through the hierarchy encoded in the local functional equation.
This paper includes two main parts. In the first part, we present generalized gauge models based on SU(3)_C x SU(4)_L x U(1)_X (3-4-1) gauge group with arbitrary electric charge of leptons. The mixing matrix of neutral gauge bosons is analysed, the eigenmasses and eigenstates are obtained. The anomaly free as well as matching conditions are discussed precisely. In the second part, we present new development of the original 3-4-1 model [1,2]. In difference from previous works, in this paper the neutrinos, with the help of the decuplet H, get the Dirac masses at the tree level. The VEV of the Higgs field in the decuplet H acquiring VEV responsible for neutrino Dirac mass leads to mixing in separated pairs of singly charged gauge bosons, namely the SM W boson and K - new gauge boson acting in right-handed lepton sector, and the singly charged bileptons X and Y. Due to the mixing, there occurs a right-handed current carried by the SM W bosons. From the expression of the electromagnetic coupling constant, ones get the limit of square sinus of the Weinberg angle: sin^2 theta_W < 0.25 and a constraint on electric charges of extra leptons. In the limit of lepton number conservation, the Higgs sector contains all massless Goldstone bosons for massive gauge bosons and the SM-like Higgs. Some phenomenology are pointed out.
We review the history of jets in high energy physics, and describe in more detail the developments of the past ten years, discussing new algorithms for jet finding and their main characteristics, and summarising the status of perturbative calculations for jet cross sections in hadroproduction. We also describe the emergence of jet grooming and tagging techniques and their application to boosted jets analyses.
A wide array of deep-inelastic-scattering and hadron collider experiments have tested the predictions of the electroweak theory and measured its parameters, while also searching for new particles and processes. We summarise recent measurements and searches that probe the Standard Model to unprecedented precision.
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