44 research outputs found
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Phenomenology of the left-right twin Higgs model
The twin Higgs mechanism was proposed recently to solve the little hierarchy problem. We study the implementation of the twin Higgs mechanism in left-right models. At the TeV scale, heavy quark and gauge bosonsappear, with rich collider phenomenology. In addition, there are extra Higgs bosons, some of which couple to both the standard model fermion sector and the gauge sector, while others couple to the gauge bosons only. We present the particle spectrum and study the general features of the collider phenomenology of this class of model at the Large Hadron Collider
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A Little Twin Higgs Model
We present a twin Higgs model based on left-right symmetry with a tree level quartic. This is made possible by extending the symmetry of the model to include two Z_2 parities, each of which is sufficient to protect the Higgs from getting a quadratically divergent mass squared. Although both parities are brokenexplicitly, the symmetries that protect the Higgs from getting a quadratically divergent mass are broken only collectively. The quadratic divergences of the Higgs mass are thus still protected at one loop. We find that the fine-tuning in this model is reduced substantially compared to the original left-right twin Higgs model. This mechanism can also be applied to the mirror twin Higgs model to get a significant reduction of the fine-tuning, while keeping the mirror photon massless
Phenomenology of The Left-Right Twin Higgs Model
The twin Higgs mechanism has recently been proposed to solve the little
hierarchy problem. We study the implementation of the twin Higgs mechanism in
left-right models. At TeV scale, heavy quark and gauge bosons appear, with rich
collider phenomenology. In addition, there are extra Higgses, some of which
couple to both the Standard Model fermion sector and the gauge sector, while
others couple to the gauge bosons only. We present the particle spectrum, and
study the general features of the collider phenomenology of this class of model
at the Large Hadron Collider.Comment: 41 pages, version appears in PR
Minimal SUSY SO(10) Model and Neutrino Oscillations
Many neutrino experiments in the last few years have reported their large statistic data which all converge to the conclusion that the three known neutrinos have masses and mix among themselves. The mixing angles in the quark sector are known to be
very small, whereas that for neutrinos are large. Understanding this difference between quarks and leptons is a major challenge of theoretical particle physics. This is especially acute in the
framework of Grand Unified Theories (GUT) which unifies quarks and leptons. In this thesis, we show that a very simple supersymmetric
SO(10) model predicts a large atmospheric mixing angle, as well as a large solar angle as
required to fit observations and a small but non-vanishing U_{e3} without any extra assumption. The
small neutrino masses are provided by the seesaw mechanism which is also one of the key ingredients of the model. This is the first extensive analysis that shows this model can have the correct
predictions for the two mixing angles as well as the mass differences required to explain the oscillation data. The prediction of the third angle U_{e3} can be tested in ongoing and planned experiments.
This model has a number of other predictions; in particular, we have deduced the predictions of the model for proton decay. We find the upper bounds on the partial lifetime of neutron decay modes. These results can also be used to test the model.
The specific form of the seesaw mechanism that we need to make our prediction imply constraints on the physics at the GUT scale. We find that (i) SO(10) must break to SU(5) before breaking to the standard model; (ii) B-L symmetry must break at the time of
SO(10) breaking and (iii) constraints of unification seem to require that the minimal model must have a 54 dimensional Higgs field together with the minimal set of {210,10,126,126-bar}