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Register a new userThe Size of the Weak Bosons
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Authors
Harald Fritzsch
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We study the hypothesis that weak bosons are composite systems, which have a size of the order of 10^{-17} cm. The electromagnetic selfenergies of the weak bosons lead to specific departures from the standard electroweak model, in agreement with observation. Above the energy of 1 TeV the standard electroweak model breaks down completely.
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In a composite model of the weak bosons the p-wave bosons are studied. The state with the lowest mass is identified with the boson, which has been observed at the LHC. Specific properties of the excited bosons are studied, in particular their decays into weak bosons and photons. Such decays might have been observed recently with the ATLAS detector at the Large Hadron Collider.
The weak bosons, leptons and quarks are considered as composite particles. The interaction of the constituents is a confining gauge interaction. The standard electroweak model is a low energy approximation. The mixing of the neutral weak boson with the photon is a dynamical mechanism, similar to the mixing between the photon and the rho-meson in QCD. This mixing provides information about the energy scale of the confining gauge force. It must be less than 1 TeV. At and above this energy many narrow resonances should exist, which decay into weak bosons and into lepton and quark pairs. Above 1 TeV excited leptons should exist, which decay into leptons under emission of a weak boson or a photon. These new states can be observed with the detectors at the Large Hadron Collider in CERN.
We present accurate QCD predictions for the transverse momentum pT spectrum of electroweak gauge bosons at the LHC for 13 TeV collisions, based on a consistent combination of a NNLO calculation at large pT and N3LL resummation in the small pT limit. The inclusion of higher order corrections leads to substantial changes in the shape of the differential distributions, and the residual perturbative uncertainties are reduced to the few percent level across the whole transverse momentum spectrum. We examine the ratio of pT distributions in charged- and neutral-current Drell-Yan production, and study different prescriptions for the estimate of perturbative uncertainties that rely on different degrees of correlation between these processes. We observe an excellent stability of the ratios with respect to the perturbative order, indicating a strong correlation between the corresponding QCD corrections.
In this study we consider an effective model by introducing two hypothetical real scalars, $H$ and $chi$ - a dark matter candidate, where the masses of these scalars are $2 m_h < m_H < 2 m_t$ and $m_chi approx m_h/2$ with $m_h$ and $m_t$ being the Standard Model Higgs boson and top quark masses respectively. A distortion in the transverse momentum distributions of $h$ in the intermediate region of the spectrum through the processes $p p to H to hchichi$ could be observed in this model. An additional scalar, $S$, has been postulated to explain large $H to hchichi$ branching ratios, assuming $m_h lesssim m_S lesssim m_H-m_h$ and $m_S > 2 m_chi$. Furthermore, a scenario of a two Higgs doublet model (2HDM) is introduced and a detailed proposal at the present energies of the Large Hadron Collider to study the extra CP-even ($h, H$), CP-odd ($A$) and charged ($H^pm$) scalars has been pursued. With possible phenomenological implications, all possible spectra and decay modes for these scalars are discussed. Based on the mass spectrum of $H, A$ and $H^pm$, the production of multi-leptons and $Z$+jets+missing-energy events are predicted. A specific, Type-II 2HDM model is discussed in detail.
Simple symmetry arguments applied to the third generation lead to a prediction: there exist new sequential Higgs doublets with masses of order $lesssim 5 $ TeV, with approximately universal Higgs-Yukawa coupling constants, $gsim 1$. This is calibrated by the known Higgs boson mass, the top quark Higgs-Yukawa coupling, and the $b$-quark mass. A new massive weak-isodoublet, $H_b$, coupled to the $b$-quark with $gsim 1$ is predicted, and may be accessible to the LHC at $13$ TeV, and definitively at the energy upgraded LHC of $26$ TeV. The extension to leptons generates a new $H_tau$ and a possible $H_{ u_tau}$ doublet. The accessibility of the latter depends upon whether the mass of the $tau$-neutrino is Dirac or Majorana.
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