arXiv subjects

Chandan Hati

Publications and source records attributed to Chandan Hati.

40 records · Page 3Linked to original sources

arXiv2015

Moduli induced cogenesis of baryon asymmetry and dark matter

We study a cogenesis mechanism in which the observed baryon asymmetry of the universe and the dark matter abundance can be produced simultaneously at low reheating temperature without violating baryon number in the fundamental vertex. In particular, we consider a model which could be realized in the context of type IIB large volume string compactifications. The matter superfields in this model include additional pairs of color triplet and singlet superfields in addition to the Minimal Supersymmetric Standard Model (MSSM) superfields. Assuming that the mass of the additional singlet fermions is O(GeV) and color triplet fermions is O(TeV), we show that the modulus dominantly decays into the additional color triplet superfields. After soft supersymmetry (SUSY) breaking, the lightest eigenstate of scalar component of color triplet superfield further decays into fermionic component of singlet superfield and quarks without violating baryon number. Assuming R-parity conservation, it follows that the singlet superfield will not further decay into the SM particles and therefore it can be considered as a stable asymmetric dark matter (ADM) component. We find that the decay of the lightest eigenstate of scalar component of color triplet superfield gives the observed baryon asymmetry in the visible sector, an asymmetric dark matter component with the right abundance and naturally explains cosmic coincidence.

hep-ph↗

arXiv2015

Explaining the CMS excesses, baryogenesis and neutrino masses in $E_{6}$ motivated $U(1)_{N}$ model

We study the superstring inspired $E_{6}$ model motivated $U(1)_{N}$ extension of the supersymmetric standard model to explore the possibility of explaining the recent excess CMS events and the baryon asymmetry of the universe in eight possible variants of the model. In light of the hints from short-baseline neutrino experiments at the existence of one or more light sterile neutrinos, we also study the neutrino mass matrices dictated by the field assignments and the discrete symmetries in these variants. We find that all the variants can explain the excess CMS events via the exotic slepton decay, while for a standard choice of the discrete symmetry four of the variants have the feature of allowing high scale baryogenesis (leptogenesis). For one other variant three body decay induced soft baryogenesis mechanism is possible which can induce baryon number violating neutron-antineutron oscillation. We also point out a new discrete symmetry which has the feature of ensuring proton stability and forbidding tree level flavor changing neutral current processes while allowing for the possibility of high scale leptogenesis for two of the variants. On the other hand, neutrino mass matrix of the $U(1)_{N}$ model variants naturally accommodates three active and two sterile neutrinos which acquire masses through their mixing with extra neutral fermions giving rise to interesting textures for neutrino masses.

hep-ph↗

arXiv2015

The $eejj$ Excess Signal at the LHC and Constraints on Leptogenesis

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy $E_6$-based models to investigate if they can explain both the recently detected excess $eejj$ signal at CMS and leptogenesis. The $eejj$ excess can be explained from the decay of the right-handed gauge bosons ($W_R$) with mass $\sim \rm{TeV}$ in certain variants of the LRSM (with $g_{L}\neq g_{R}$). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the $W_{R}$ mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However this may not be feasible due to washout of the lepton asymmetry by certain processes. Therefore we consider three effective low energy subgroups of the superstring inspired $E_{6}$ model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of $E_6$ too cannot explain both the $eejj$ excess signal and leptogenesis simultaneously.

hep-ph↗

arXiv2015

Explaining the CMS $eejj$ and $e\ \rm{missing}\ p_T \ jj$ excess and leptogenesis in superstring inspired $E_6$ models

We show that superstring inspired $E_6$ models can explain both the recently detected excess $eejj$ and $e\ \rm{missing}\ p_T \ jj$ signals at CMS, and also allow for leptogenesis. Working in a R-parity conserving low energy supersymmetric effective model, we show that the excess CMS events can be produced via the decay of exotic sleptons in Alternative Left-Right Symmetric Model of $E_6$, which can also accommodate leptogenesis at a high scale. On the other hand, either the $eejj$ excess or the $e\ \rm{missing}\ p_T \ jj$ excess can be produced via the decays of right handed gauge bosons, but some of these scenarios may not accommodate letptogenesis as there will be strong $B-L$ violation at low energy, which, along with the anomalous fast electroweak $B+L$ violation, will wash out all baryon asymmetry. Baryogenesis below the electroweak scale may then need to be implemented in these models.

hep-ph↗