arXiv subjects

V. N. Senoguz

Publications and source records attributed to V. N. Senoguz.

11 recordsLinked to original sources

arXiv2007

Supersymmetric And Smooth Hybrid Inflation In The Light Of WMAP3

In their minimal form both supersymmetric and smooth hybrid inflation yield a scalar spectral index n_s close to 0.98, to be contrasted with the result n_s=0.951+0.015-0.019 from WMAP3. To realize better agreement, following hep-ph/0604198, we extend the parameter space of these models by employing a non-minimal Kaehler potential. We also discuss non-thermal leptogenesis by inflaton decay and obtain new bounds in these models on the reheat temperature to explain the observed baryon asymmetry.

hep-ph↗

arXiv2007

From New to Large Field Inflation: Comparison with WMAP3

We briefly summarize and update a class of inflationary models from the early eighties based on a quartic (Coleman-Weinberg) potential for a gauge singlet scalar (inflaton) field. For vacuum energy scales comparable to the grand unification scale, the scalar spectral index n_s=0.94-0.97, in very good agreement with the WMAP three year results. The tensor to scalar ratio r<~0.14 while alpha=dn_s/d ln k=~-10^-3. For vacuum energy scales >~10^16 GeV, the inflationary scenario switches from `new' to `large-field' (V\proptoϕ^2) inflation. An SO(10) version naturally explains the observed baryon asymmetry via non-thermal leptogenesis.

astro-ph↗

arXiv2006

Non-Canonical MSSM, Unification, And New Particles At The LHC

We consider non-canonical embeddings of the MSSM in high-dimensional orbifold GUTs based on the gauge symmetry SU(N), N=5,6,7,8. The hypercharge normalization factor k_Y can either have unique non-canonical values, such as 23/21 in a six-dimensional SU(7) model, or may lie in a (continuous) interval. Gauge coupling unification and gauge-Yukawa unification can be realized in these models by introducing new particles with masses in the TeV range which may be found at the LHC. In one such example there exist color singlet fractionally charged states.

hep-ph↗

arXiv2006

Higgs Boson Mass from Orbifold GUTs with Split Supersymmetry

We consider orbifold GUTs with N=1 supersymmetry in which the Standard Model (SM) gauge couplings are unified at M_GUT =~ 2 x 10^16 GeV with one of the third family (charged) Yukawa couplings. With split supersymmetry the SM Higgs mass is estimated to be 131 +/- 10 GeV for gauge-top quark Yukawa unification, which increases to 146 +/- 8 GeV for gauge-bottom quark (or gauge-tau lepton) Yukawa unification.

hep-ph↗

arXiv2006

Coleman-Weinberg Potential In Good Agreement With WMAP

We briefly summarize and update a class of inflationary models from the early eighties based on a quartic (Coleman-Weinberg) potential for a gauge singlet scalar (inflaton) field. For vacuum energy scales comparable to the grand unification scale, the scalar spectral index n_s=0.94-0.97, in very good agreement with the WMAP three year results. The tensor to scalar ratio r<~0.14, while alpha=dn/dlnk is =~-10^-3. An SO(10) version naturally explains the observed baryon asymmetry via non-thermal leptogenesis.

astro-ph↗

arXiv2005

U(1)_B-L: Neutrino Physics and Inflation

A gauged U(1)_B-L symmetry predicts three right handed handed neutrinos and its spontaneous breaking automatically yields the seesaw mechanism. In a supersymmetric setting this breaking can be nicely linked with inflation to yield deltaT/ T proportional to (M_B-L / M_P)^2, where M_B-L (M_P) denote the B-L breaking (Planck) scale. Thus M_B-L is estimated to be of order 10^16 GeV, and the heaviest right handed neutrino mass is less than or of order 10^14 GeV. A second right handed neutrino turns out to have a mass of order 10-10^2 T_r, where T_r (<~10^9 GeV) denotes the reheat temperature. A U(1) R symmetry plays an essential role in implementing inflation and leptogenesis, resolving the MSSM mu problem and eliminating dimension five nucleon decay. An unbroken Z_2 subgroup plays the role of matter parity. The scalar spectral index n_s=0.99+-0.01 for the simplest models, while in smooth hybrid inflation n_s>=0.97. The tensor to scalar ratio r is negligible, and dn_s/dlnk<~10^-3.

hep-ph↗

arXiv2005

Reheat temperature in supersymmetric hybrid inflation models

The allowed range of parameters for supersymmetric hybrid inflation and its extensions are investigated. The lower bound on the reheat temperature T_r in these models with hierarchical right handed neutrinos is found to be 3*10^7 GeV. (T_r as low as 100 GeV is possible for quasi degenerate right handed neutrinos.) We also present revised estimates for the scalar spectral index and the symmetry breaking scale associated with inflation.

hep-ph↗

arXiv2004

New inflation, preinflation, and leptogenesis

We present a new inflation model in which the inflationary scenario including subsequent reheating is determined in part by a U(1)_R\times Z_n symmetry. A preinflation epoch can be introduced to yield, among other things, a running spectral index indicated by the WMAP analysis. The inflaton decay into right handed neutrinos, whose masses can be hierarchical because of the Z_n symmetry, leads to a reheat temperature >~10^8 GeV (~10^4-10^6 GeV in some cases), followed by non-thermal leptogenesis.

hep-ph↗

arXiv2004

TeV Scale Leptogenesis With Heavy Neutrinos

Following a baryogenesis scenario proposed by Lazarides, Panagiotakopoulos and Shafi, we show how the observed baryon asymmetry can be explained via resonant leptogenesis in a class of supersymmetric models with an intermediate mass scale M_I<~10^9 GeV. It involves the out of equilibrium decay of heavy (<~M_I) right handed neutrinos at a temperature close to the TeV supersymmetry breaking scale. Such models can also resolve the MSSM mu problem.

hep-ph↗

arXiv2003

GUT Scale Inflation, Non-Thermal Leptogenesis, and Atmospheric Neutrino Oscillations

Leptogenesis scenarios in supersymmetric hybrid inflation models are considered. Sufficient lepton asymmetry leading to successful baryogenesis can be obtained if the reheat temperature T_r>10^6 GeV and the superpotential coupling parameter kappa is in the range 10^-6<kappa<10^-2. For this range of kappa the scalar spectral index n_s=0.99+-0.01. Constraints from neutrino mixing further restrict the range of kappa that is allowed. We analyze in detail the case where the inflaton predominantly decays into the next-to-lightest right handed Majorana neutrino taking into account especially the constraints from atmospheric neutrino oscillations.

hep-ph↗

arXiv2003

Testing Supersymmetric Grand Unified Models of Inflation

We reconsider a class of well motivated supersymmetric models in which inflation is associated with the breaking of a gauge symmetry G to H, with the symmetry breaking scale M~10^16 GeV. Starting with a renormalizable superpotential, we include both radiative and supergravity corrections to derive the inflationary potential. The scalar spectral index n_s can exceed unity in some cases, and it cannot be smaller than 0.98 if the number of e-foldings corresponding to the present horizon scale is around 60. Two distinct variations of this scenario are discussed in which non-renormalizable terms allowed by the symmetries are included in the superpotential, and one finds n_s>=0.97. The models discussed feature a tensor to scalar ratio r<~10^-4, while dn_s/dlnk<~10^-3. If G corresponds to SO(10) or one of its rank five subgroups, the observed baryon asymmetry is naturally explained via leptogenesis.

hep-ph↗