Papers by Konstantinos Pallis
Proceedings of Corfu Summer Institute 2022 "School and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2022)
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Proceedings of Corfu Summer Institute 2021 "School and Workshops on Elementary Particle Physics and Gravity" — PoS(CORFU2021), Nov 23, 2022
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Journal of Physics: Conference Series, 2021
We present a realization of Higgs inflation within Supergravity which is largely tied to the exis... more We present a realization of Higgs inflation within Supergravity which is largely tied to the existence of a pole of order two in the kinetic term of the inflaton field. This pole arises due to the selected Kaehler potential which parameterizes the SU(2,1)/(SU(2) × U(1)) manifold with scalar curvature R 21 = − 6 / N . The associated superpotential includes, in addition to the Higgs superfields, a stabilizer superfield, respects a B − L gauge and an R symmetries and contains the first allowed nonrenormalizable term. If the coefficient of this term is almost equal to that of the others within about 10−5 and N = 2, the inflationary observables can be done compatible with the present data. The tuning can be eluded if we modify the Kaehler potential associated with the manifold above. In this case, inflation can be realized with just renormalizable superpotential terms and results to higher tensor-to-scalar ratios as N approaches its maximum at N ≃80.
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World Academy of Science, Engineering and Technology, International Journal of Physical and Mathematical Sciences, 2015
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Physical Review D, 2003
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F-term hybrid inflation (FHI) of the hilltop type can generate a scalar spectral index, ns, in ag... more F-term hybrid inflation (FHI) of the hilltop type can generate a scalar spectral index, ns, in agreement with the fitting of the seven-year Wilkinson microwave anisotropy probe data by the standard power-law cosmological model with cold dark matter and a cosmological constant, LambdaCDM. We investigate the realization of this type of FHI by using quasi-canonical Kahler potentials with or without the inclusion of extra hidden-sector fields. In the first case, acceptable results can be obtained by constraining the coefficients of the quadratic and/or quartic supergravity correction to the inflationary potential and therefore a mild tuning of the relevant term of the Kahler potential is unavoidable. Possible reduction of ns without generating maxima and minima of the potential on the inflationary path is also possible in a limited region of the available parameter space. The tuning of the terms of the Kahler potential can be avoided with the adoption of a simple class of string-inspire...
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The cosmological relic density of a Bino-like Lightest Supersymmetric Particle is calculated in t... more The cosmological relic density of a Bino-like Lightest Supersymmetric Particle is calculated in the framework of the Minimal Supersymmetric Standard Model. We include annihilation and coannihilation effects of the Bino with the lightest stau and with the other sleptons, which happen to have comparable masses with it. Coannihilation turns out to be crucial for reducing the Bino relic density to an acceptable level. Phenomenological constraints, also, results from the inclusion of the supersymmetric corrections to the CP-even Higgs boson and b-quark masses and the branching ratio of b -->s gamma. We impose these constraints on two versions of the Minimal Supersymmetric Standard Model, employing radiative electroweak breaking with universal boundary conditions and gauge coupling unification. In the first version of the model we assume Yukawa coupling unification and boundary conditions from gravity-mediated supersymmetry breaking. In the second version of the model we assume boundar...
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Physics Letters B, 2011
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Physical Review D, 2012
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Nuclear Physics B, 2002
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Nuclear Physics B, 2004
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Journal of Physics: Conference Series, 2012
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Journal of Cosmology and Astroparticle Physics, 2011
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Journal of Cosmology and Astroparticle Physics, 2011
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Journal of Cosmology and Astroparticle Physics, 2014
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Arxiv preprint hep-ph/0303098, 2003
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Arxiv preprint hep-ph/0303094, 2003
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International Journal of Modern Physics A, 2013
The construction of specific supersymmetric grand unified models based on the Pati–Salam gauge gr... more The construction of specific supersymmetric grand unified models based on the Pati–Salam gauge group and leading to a set of Yukawa quasi-unification conditions which can allow an acceptable b-quark mass within the constrained minimal supersymmetric standard model with μ > 0 is briefly reviewed. Imposing constraints from the cold dark matter abundance in the universe, B physics, and the mass mh of the lighter neutral CP-even Higgs boson, we find that there is an allowed parameter space with, approximately, 44 ≤ tan β ≤ 52, -3 ≤ A0/M1/2 ≤ 0.1, 122 ≤ mh/ GeV ≤ 127, and mass of the lightest sparticle in the range (0.75–1.43) TeV. Such heavy lightest sparticle masses can become consistent with the cold dark matter requirements on the lightest sparticle relic density thanks to neutralino–stau coannihilations which are enhanced due to stau–antistau coannihilation to down type fermions via a direct-channel exchange of the heavier neutral CP-even Higgs boson. Restrictions on the model pa...
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Physical Review D, 2013
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Proceedings of 18th International Conference From the Planck Scale to the Electroweak Scale — PoS(PLANCK 2015), Mar 18, 2016
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Papers by Konstantinos Pallis