arXiv subjects

Dhruv Pasari

Publications and source records attributed to Dhruv Pasari.

4 recordsLinked to original sources

arXiv2026

The Dark Dimension and Majorana Neutrinos

Recent developments in the Swampland program motivate the existence of a mesoscopic Dark Dimension of size $0.1-10~μ$m with bulk Majorana fermions in the $1-10$ keV range. Motivated by this, we derive terrestrial constraints on Majorana bulk neutrinos as a function of the compactification radius. After determining the mass spectrum and mixing structure, we confront the model with Daya Bay neutrino-oscillation data, the KATRIN beta-decay bound, and the KamLAND-Zen neutrinoless double beta decay limit. For the latter, we obtain a closed-form expression for the effective Majorana mass and show that the Kaluza-Klein tower efficiently screens neutrinoless double beta decay when the nuclear momentum exceeds the compactification and Majorana scales. In the Dark-Dimension window, beta decay provides the strongest constraint, pushing the allowed Yukawa couplings down to $\mathcal{O}(10^{-3})$. Oscillation and neutrinoless double beta decay searches remain complementary, probing smaller and larger Majorana masses, respectively. For completeness, outside the Dark-Dimension assumptions, we investigate how hierarchical Majorana masses can weaken the constraints.

hep-ph↗

arXiv2026

Do neutrinos dream in 5D? Towards a comprehensive extra-dimensional neutrino phenomenology

This paper provides a comprehensive overview of neutrino masses and mixing in Large Extra Dimension scenarios, focusing on the phenomenological impact of a five-dimensional (5D) bulk fermion. In a flat extra dimension compactified on an $S^1/\mathbb{Z}_2$ orbifold, this fermion manifests as a Kaluza-Klein tower of right-handed neutrinos in the 4D effective theory. We systematically investigate four distinct scenarios for mass generation, considering both Dirac and Majorana mass terms originating from either the bulk or the 3-brane. For each case, we analyse the consequences for neutrino oscillations in a vacuum and in matter, deriving the resulting mass spectra and mixing patterns. By comparing these theoretical predictions with experimental data, we explore the constraints on the large extra dimensions' parameters.

hep-ph↗

arXiv2026

ULYSSES the Third: An Odyssey Towards a Unified Python Toolkit for Leptogenesis

We present the third release of $\texttt{ULYSSES}$, a Python package for the numerical evaluation of the baryon asymmetry generated through leptogenesis. This version includes code implementing state-of-the-art density matrix equations for low-scale leptogenesis with three quasi-degenerate right-handed neutrinos. We extend the validity of the code in this scenario beyond the 100 GeV right-handed neutrino mass scale, into the regime of resonant leptogenesis, by including neutrino production rates valid in both the relativistic and non-relativistic regimes. In addition, in the high-scale vanilla scenario, we provide routines for computing $ΔL = 1$ scattering processes, enabling full phase-space evolution of the right-handed neutrino and lepton asymmetry. A new $\texttt{--extended}$ parameter interface allows users to pass model-specific inputs beyond the standard leptogenesis runcard without modifying the core infrastructure and demonstrate its use with a toy module that simultaneously solves the vanilla leptogenesis equations and the freeze-in production of dark matter. On top of these improvements, we introduce an alternative parametrisation of the Casas-Ibarra matrix, update the default neutrino oscillation parameters and report cross-checks of the new low-scale leptogenesis module against published benchmarks and independent codes. $\texttt{ULYSSES}$ is publicly available on $\href{https://github.com/earlyuniverse/ulysses}{\texttt{GitHub}}$ and pip-installable from PyPI.

hep-ph↗

arXiv2026

nuSTORM as a Precision Probe of the Standard Model and New Physics

The Neutrinos from Stored Muons (nuSTORM) facility will generate neutrino beams from both muon and meson decays in a storage ring, providing a neutrino flux known to the percent level. This unprecedented precision enables a rich physics programme, including high-precision tests of the Standard Model and searches for new phenomena. In this paper we demonstrate nuSTORM's sensitivity to key Standard Model processes such as, measurements of the weak mixing angle at low $Q^2$ and the rare process of neutrino trident production. We also show its powerful reach for a diverse range of beyond-the-Standard-Model scenarios, including eV-scale sterile neutrinos, Kaluza-Klein excitations from large extra dimensions and lepton flavour violation. Furthermore, nuSTORM can place significant constraints on heavy QCD axions and other axion-like particles produced in rare kaon decays. These capabilities establish nuSTORM as a powerful and complementary probe to long baseline experiments and collider searches.

hep-ph↗