Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userPseudosmooth Tribrid Inflation in $SU(5)$
60
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
A realistic tribrid model of sneutrino inflation is constructed in an $R$-symmetric $SU(5)$ grand unified theory (GUT). To avoid the monopole problem, a pseudosmooth inflationary trajectory is generated with the help of an additional $Z_5$ symmetry which is broken during and after inflation. The predictions of inflationary parameters are made at the central value of the scalar spectral index, $n_s =0.968$. The largest possible value of the tensor to scalar ratio, $rlesssim 0.0027$, is obtained with sub-Planckian field values ($lesssim m_P$). A successful realization of reheating and leptogenesis is achieved by avoiding the gravitino problem with a reheat temperature as low as $10^6$ GeV. The predicted range of the gauge symmetry breaking scale, $ 5 times 10^{16} lesssim M/text{GeV} lesssim 5 times 10^{17}$, turns out to be somewhat larger than the typical GUT scale. With additional vector-like families, a successful gauge coupling unification is achieved by avoiding the no-go theorem related to $R$-symmetric $SU(5)$ GUT.
rate research
Read More
We study the feasibility of realizing supersymmetric new inflation model, introduced by Senoguz and Shafi in [1], for $SU(5)$ and flipped $SU(5)$ models of grand unified theories (GUTs). This realization requires an additional $U(1)_R times Z_{n}$ symmetry for its successful implementation. The standard model (SM) gauge singlet scalar components of $24_H$ and $10_H$ GUT Higgs superfields are respectively employed to realize successful inflation in $SU(5)$ and flipped $SU(5)$ models. The predictions of the various inflationary observables lie within the recent Planck bounds on the scalar spectral index, $n_s$, for $n geq 5$ in $SU(5)$ model and for $n geq 6$ in flipped $SU(5)$ model. In particular, the tensor to scalar ratio $r$ and the running of spectral index $d n_s/ dln k$ are negligibly small and lie in the range, $10^{-12} lesssim r lesssim 10^{-8}$ and $10^{-9} lesssim dn_s/dln k lesssim 10^{-3}$, for realistic values of $n$. In numerical estimation of the various predictions, we fix the gauge symmetry breaking scale, $M$, around $2 times 10^{16}$ GeV. The issue of gauge coupling unification in $R$-symmetric $SU(5)$ is evaded by adding vectorlike families with mass splitting within their multiplets. The dilution of monopoles beyond the observable limit is naturally achieved in the breaking of $SU(5)$ gauge symmetry during inflation. A realistic scenario of reheating with non-thermal leptogenesis is employed for both models. The predicted range of reheat temperature within Planck bounds, $3 times 10^{7}text{ GeV }lesssim T_r lesssim 2 times 10^{9}$ GeV, is safe from the gravitino problem for the gravitino mass, $m_{3/2} gtrsim 10$ TeV. Finally, the $U(1)_R times Z_{n}$ symmetry is also observed to play a crucial role in suppressing the various fast proton decay operators.
A scheme of simplified smooth hybrid inflation is realized in the framework of supersymmetric $SU(5)$. The smooth model of hybrid inflation provides a natural solution to the monopole problem that appears in the breaking of $SU(5)$ gauge symmetry. The supergravity corrections with nonminimal Kahler potential are shown to play important role in realizing inflation with a red-tilted scalar spectral index $n_s <1$, within Plancks latest bounds. As compared to shifted model of hybrid inflation, relatively large values of the tensor-to-scalar ratio $r lesssim 0.01$ are achieved here, with nonminimal couplings $-0.05 lesssim kappa_S lesssim 0.01$ and $-1 lesssim kappa_{SS} lesssim 1$ and the gauge symmetry-breaking scale $M simeq (2.0 - 16.7) times 10^{16}$ GeV.
We present a successful realization of sneutrino tribrid inflation model based on a gauged $U(1)_{B-L}$ extension of Minimal Supersymmetric Standard Model (MSSM). A single interaction term involving the $B-L$ Higgs field and the right-handed neutrinos serves multiple purposes. These include the generation of heavy Majorana masses for the right-handed neutrinos to provide an explanation for the tiny neutrino masses via the seesaw mechanism, a realistic scenario for reheating and non-thermal leptogenesis with a reheat temperature as low as $10^6$ GeV, and a successful realization of inflation with right-handed sneutrino as the inflaton. The matter parity which helps avoid rapid proton decay survives as a $Z_{2}$ subgroup of a $U(1)$ $R$-symmetry. Depending on the choice of model parameters yields the following predicted range of the tensor to scalar ratio, $3 times 10^{-11}lesssim rlesssim 7times 10^{-4}$ ($ 6 times 10^{-7} lesssim r lesssim 0.01 $), and the running of the scalar spectral index, $-0.00022 lesssim dn_s/dln k lesssim -0.0026$ ($-0.00014 lesssim dn_s/dln k lesssim 0.005$), along with the $B-L$ breaking scale, $ 3 times 10^{14}lesssim M/ text{GeV}lesssim 5 times 10^{15}$ ($ 6 times 10^{15}lesssim M/ text{GeV}lesssim 2 times 10^{16}$), calculated at the central value of the scalar spectral index, $n_s =0.966$, reported by Planck 2018. The possibility of realizing metastable cosmic strings in a grand unified theory setup is briefly discussed. The metastable cosmic string network admits string tension values in the range $10^{-8} lesssim Gmu_s lesssim 10^{-6}$, and predicts a stochastic gravitational wave background lying within the 2-$sigma$ bounds of the recent NANOGrav 12.5-yr data.
We revisit supersymmetric hybrid inflation in the context of flipped $SU(5)$ model. With minimal superpotential and minimal Kahler potential, and soft SUSY masses of order $(1 - 100)$ TeV, compatibility with the Planck data yields a symmetry breaking scale $M$ of flipped $SU(5)$ close to $(2 - 4) times 10^{15}$ GeV. This disagrees with the lower limit $M gtrsim 7 times 10^{15}$ GeV set from proton decay searches by the Super-Kamiokande collaboration. We show how $M$ close to the unification scale $2times 10^{16}$ GeV can be reconciled with SUSY hybrid inflation by employing a non-minimal Kahler potential. Proton decays into $e^+ pi^0$ with an estimated lifetime of order $10^{36}$ years. The tensor to scalar ratio $r$ in this case can approach observable values $sim 10^{-4} - 10^{-3}$.
We propose a simple renormalizable grand unified theory based on the $SU(5)$ gauge symmetry where the neutrino masses are generated at the quantum level through the Zee mechanism. In this model the same Higgs needed to correct the mass relation between charged leptons and down-type quarks plays a crucial role to generate neutrino masses. We show that in this model one can satisfy the constrains coming from the unification of gauge couplings and the mechanism for neutrino masses is discussed in detail. The predictions for proton decay are discussed in order to understand the testability at current and future experiments such as Hyper-Kamiokande. This simple theory predicts a light colored octet which could give rise to exotic signatures at the LHC.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
