arXiv subjects

India Bhalla-Ladd

Publications and source records attributed to India Bhalla-Ladd.

3 recordsLinked to original sources

arXiv2026

Ceci n'est pas un gluon

We discuss and then resolve a tension between how physicists treat gauge bosons and the celebrated "Wu-Yang dictionary", which identifies particle physics terminology with that of principal bundles and principal connections. We show how this tension leads to an interpretative choice that is not widely discussed in the physics literature. We then show how the same considerations present a dilemma for a recent "particle-first" approach to Yang-Mills theory due to Henrique Gomes. Either the particle-first approach has surplus structure as compared to principal-bundle-based approaches, or gauge bosons are not sections of vector bundles.

physics.hist-ph↗

arXiv2025

Leptogenesis During an Era of Early SU(2) Confinement

We explore leptogenesis during a cosmological epoch during which the electroweak $SU(2)_L$ force is confined. During weak confinement, there is only one conserved non-anomalous global charge, $r$, which is a linear combination of lepton-number, baryon-number, and hypercharge. The inclusion of heavy Majorana neutrinos leads to an $r$-charge and $CP$-violating interaction, allowing for the generation of an $r$-charge asymmetry, which translates into a baryon asymmetry post $SU(2)_L$ deconfinement. Determining the resulting baryon asymmetry as a function of the model parameters, we find that the predicted baryon-asymmetry can match observations for a wide swath of parameter space. While leptogenesis under the assumption of a standard cosmology relies on the complex phase of the neutrino Yukawa couplings, the asymmetry generated in this novel background cosmology primarily depends on a strong phase from $SU(2)_L$ confinement and favors negligible $CP$-violation in the right-handed neutrino decays.

hep-ph↗

arXiv2019

Introducing the Search for Intermediate-mass Black-hole In Nearby Galaxy (SIBLING) Survey

Intermediate mass black holes (IMBHs) have masses between the $10^2\!-\!10^6$ M$_\odot$ and are key to our understanding of the formation of massive black holes. The known population of IMBH remains small, with a few hundred candidates and only a handful of them confirmed as bona-fide IMBHs. Until now, the most widely used selection method is based on spectral analysis. Here we present a methodology to select IMBH candidates via optical variability analysis of the nuclear region of local galaxies ($z \leqslant 0.35$). Active IMBH accreting at low rates show small amplitude variability with time scales of hours, as it is seen in one of the known IMBH NGC4395. We found a sample of $\sim \!500$ galaxies evidencing fast and small amplitude variation in their weekly based light curves. We estimate an average occupancy fraction of 4\% and a surface density of $\sim \!3$ deg$^{-2}$, which represent an increase by a factor of $\sim\!40$ compared to previous searches. A large fraction ($78\%$) of the candidates are in spiral galaxies. We preliminary confirm the AGN nature of 22 sources via BPT diagrams using SDSS legacy spectra. Further confirmation of these candidates will require multiwavelength observations, especially in X-ray and radio bands.

astro-ph.GA↗