arXiv subjects

Rohan Pramanick

Publications and source records attributed to Rohan Pramanick.

7 recordsLinked to original sources

arXiv2025

Complex Scalar Singlet Model: Electroweak Phase Transition and Gravitational Waves

The Standard Model (SM) cannot explain the observed baryon asymmetry of the Universe (BAU), thus driving the need for physics beyond the SM, which can generate electroweak baryogenesis through a strong first-order electroweak phase transition (SFOPT). We extend the SM with a complex singlet scalar (cxSM) and examine the phase transition behavior using a fully general renormalizable scalar potential that permits a complex vacuum expectation value for the singlet and coupled dynamics among multiple scalar fields. Employing the one-loop thermal effective potential with daisy resummation and appropriate counter terms, we conduct an extensive scan of the parameter space, enforcing both theoretical and experimental limits on the scalar sector. This analysis reveals viable domains yielding SFOPT. From these regions, we select representative benchmark scenarios demonstrating multi-stage transitions, producing stochastic gravitational wave signals via bubble nucleation dynamics. The resulting spectra lie within the projected sensitivity of next-generation observatories, including LISA, BBO, DECIGO, and U-DECIGO. Thus, the cxSM offers a compelling setting for electroweak baryogenesis, enriched by correlated gravitational-wave and collider phenomenology.

hep-ph↗

arXiv2024

Cogenesis of visible and dark matter in a scotogenic model

Within a scotogenic neutrino mass model we explore the cogenesis of matter from the CP violating decay of a heavy $\mathbb{Z}_2$-odd right handed neutrino that simultaneously populates the visible and a multipartite dark sector. The relic density of a sub-GeV scale freeze-in dark matter is generated by the late time decay of the next-to-lightest dark particle dynamically regulated by an interplay with the thermal scattering processes. We show that this model can simultaneously explain visible matter asymmetry and provide a cosmologically viable sub-GeV dark matter while remaining in consonance with the neutrino parameters and flavour observables.

hep-ph↗

arXiv2024

Neutrinos from captured dark matter in galactic stars

Sub-GeV neutrinos produced in a stellar core may emerge from main sequence stars, white dwarfs and brown dwarfs producing possible observable signals of dark matter capture. A distribution of these stars near the Milky Way galactic center will produce a neutrino flux that can be probed at Earth based neutrino observatories like Super-Kamiokande and Hyper-Kamiokande. We demonstrate that this can provide a handle to probe dark matter masses in the $200\,$MeV\,$-$\,$2\,$GeV mass scales that compares favourably with present day direct detection bounds.

hep-ph↗

arXiv2024

Towards a more complete description of hybrid leptogenesis

Hybrid leptogenesis framework combining type I and type II seesaw mechanism for neutrino mass necessarily include scattering topologies involving both the scalar triplet and the right handed neutrino. We demonstrate that a systematic inclusion of these mixed scatterings can significantly alter the evolution of the number densities exhibiting up to a factor ten deviation in the predicted asymmetry as demonstrated by our benchmark scenarios. We provide quantitative constraints on the degeneracy of the seesaw scales where the complete analysis becomes numerically significant, limiting the validity of leptogenesis being dominated by the lightest seesaw species only.

hep-ph↗

arXiv2022

Neutrino mass and leptogenesis in a hybrid seesaw model with a spontaneously broken CP

We introduce a novel hybrid framework combining type I and type II seesaw models for neutrino mass where a complex vacuum expectation value of a singlet scalar field breaks CP spontaneously. Using pragmatic organizing symmetries we demonstrate that such a model can simultaneously explain the neutrino oscillation data and generate observed baryon asymmetry through leptogenesis. Interestingly, natural choice of parameters leads to a mixed leptogenesis scenario driven by nearly degenerate scalar triplet and right handed singlet neutrino fields for which we present a detailed quantitative analysis.

hep-ph↗

arXiv2021

Broad toplike vector quarks at LHC and HL-LHC

Top like vector quarks arising from underlying strong sectors are expected to have large decay widths pushing them beyond the narrow width approximation. In this paper we consider a broad colored vector quark that strongly couples to an exotic pseudoscalar. We use the full 1PI resummed propagator for the exotic quark to recast the present LHC constraints ruling out masses below $\sim1.2~(1.1)$ TeV for width to mass ratio of $0.1~(0.6)$. We utilize machine learning techniques that are demonstratively more efficient than traditional cut based searches to present the reach of HL-LHC on the parameter space of this broad resonance. We find that at $3~ab^{-1}$ the HL-LHC has a discovery potential up to $1.6$ TeV dominated by the pair production channel. We study the feasibility of using machine learning techniques to analyze the broad resonance peaks expected from these exotic quarks at collider experiments like the LHC.

hep-ph↗

arXiv2020

Bargmann Invariants, Geometric Phases and Recursive Parametrization with Majorana Fermions

A generalized connection between the quantum mechanical Bargmann invariants and the geometric phases was established for the Dirac fermions. We extend that formalism for the Majorana fermions by defining proper quantum mechanical ray and Hilbert spaces. We then relate both the Dirac and Majorana type Bargmann invariants to the rephasing invariant measures of CP violation with the Majorana neutrinos, assuming that the neutrinos have lepton number violating Majorana masses. We then generalize the recursive parametrization for studying any unitary matrices to include the Majorana fermions, which could be useful for studying the neutrino mixing matrix.

hep-ph↗