arXiv subjects

Suvam Maharana

Publications and source records attributed to Suvam Maharana.

8 recordsLinked to original sources

arXiv2026

Return of the CHAMPs: A clockwork portal to charged dark matter

While Dark Matter (DM) is conventionally assumed to be chargeless, the possibility of a charged massive particle (CHAMP) as the DM particle remains alive. With phenomenological constraints on the charge being very severe, such a scenario is often sought to be dismissed, citing naturalness. Moreover, the establishment of the correct relic density is often a concern. We demonstrate here that such a (mini)charged DM can yet be realized within the clockwork paradigm, without the need to invoke unnaturally small parameters. The model is examined against constraints, theoretical and experimental, and the phenomenologically admissible parameter space is delineated. Several intriguing tests, at the LHC as well as at future direct and indirect detection experiments, are pointed out.

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arXiv2026

Multipolar Dark Matter Freeze-out in an Early Matter-Dominated Universe

The relic abundance of thermal dark matter depends not only on its particle interactions but also on the expansion history of the early Universe. We study the freeze-out of fermionic dark matter interacting with the Standard Model through higher-dimensional electromagnetic operators in an early matter-dominated cosmology. In particular, we consider magnetic dipole, electric dipole, anapole, and charge-radius interactions, and compute the couplings required to reproduce the observed dark matter relic abundance in the presence of entropy injection from the decay of a long-lived heavy field. The resulting parameter space is compared with that obtained in the standard radiation-dominated freeze-out scenario and confront it with current constraints from direct-detection experiments and solar neutrino observations. We find that the entropy dilution associated with an early matter-dominated epoch significantly reduces the interaction strength required to obtain the observed relic abundance, thereby rendering viable regions of parameter space that are excluded in the conventional cosmological history. Our results demonstrate that the cosmological history prior to Big Bang nucleosynthesis can have an important impact on the phenomenology and experimental viability of electromagnetic multipole dark matter.

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arXiv2025

Axion Icebergs: Clockwork ALPs at hadron colliders

Scenarios with multiple pseudoscalars are interesting as they usually tend to provide a framework to naturally realize a light axion with a large decay constant which has rich applications in cosmology, especially in the context of inflation and light dark matter physics. On the other hand, from a particle physics perspective, this facilitates a solution to the strong CP problem with a low Peccei-Quinn symmetry breaking scale. One such realization is afforded within the framework of the clockwork mechanism where the axion can have suppressed couplings with the gluons or photons while its companion axion-like particles (ALPs) have relatively unsuppressed couplings, thereby facilitating detectability. We study a minimal clockwork model for the QCD axion invoking a KSVZ-like setup and examine the visibility of its unique multi-ALP $(a_n)$ signature at the LHC, the most sensitive channel being $p p \to a_n \, (+ \, {\rm additional \, jets})$ followed by $a_n \to γγ$. In congruence with the astrophysical and cosmological bounds for the axion, a striking feature emerges for the case of light ALPs $(m \sim \mathcal{O}(10 \, {\rm GeV}))$ wherein the mass-splittings among the former are so small that the signal profile mimics that of a single broad resonance, or an $axion$ $iceberg$. The scenario is found to be imminently testable by the end of LHC's Run 3 phase for an integrated luminosity of $\sim 300 {\rm \, fb^{-1}}$. A larger average ALP mass, on the other hand, results in multiple closely-spaced peaks with a characteristic signal profile, and would be expected to be seen at the forthcoming HL-LHC. Possible additional signals are also listed.

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arXiv2024

Clockwork Neutrinogenesis: Baryogenesis from theory space

We propose a minimal clockwork model to illustrate the possibility of baryogenesis via leptogenesis in a theory space setting. The standard lepton sector is augmented with three copies of a clockwork lattice made of SM neutral fermions. The two boundaries of these one-dimensional lattices are endowed with couplings to the SM leptons and three dark sector fermions, respectively. Small neutrino masses and a resonance enhanced Dirac leptogenesis are naturally obtained for anarchic textures of the Yukawa matrices, with $\sim \mathcal{O}(1)$ elements, provided the heavy clockwork fermions have masses $\gtrsim \mathcal{O}(10 \, \mbox{TeV})$

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arXiv2022

A closed clockwork theory: $\mathbb{Z}_2$ parity and more

We develop a new class of clockwork theories with an augmented structure of the near-neighbour interactions along a one-dimensional closed chain. Such a topology leads to new and attractive features in addition to generating light states with hierarchical couplings via the usual clockwork mechanism. For one, there emerges a $\mathbb{Z}_2$ symmetry under the exchange of fields resulting in a physical spectrum consisting of states, respectively even and odd under the exchange parity with a two-fold degeneracy at each level. The lightest odd particle, being absolutely stable, could be envisaged as a potential dark matter candidate. The theory can also be obtained as a deconstruction of a five-dimensional theory embedded in a geometry generated by a linear dilaton theory on a $S^1/\mathbb{Z}_2$ orbifold with three equidistant 3-branes. Analogous to the discrete picture, the $\mathbb{Z}_2$ symmetry in the bulk theory necessitates the existence of a KK spectrum of even and odd states, with doubly degenerate modes at each KK level when subject to certain boundary conditions.

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arXiv2022

Anomalous gauge couplings vis-$\grave{a}$-vis $(g-2)_μ$ and flavor observables

We reassess non-standard triple gauge couplings in the light of the recent $(g-2)_μ$ measurement at FNAL, the new lattice theory result of $(g-2)_μ$ and the updated measurements of several $B$-decay modes. In the framework of SMEFT, three bosonic dimension-6 operators are invoked to parametrize physics beyond the Standard Model and their contributions to such low-energy observables computed. Constraints on the corresponding Wilson coefficients are then derived from fits to the current experimental bounds on the observables and compared with the most stringent ones available from the 13 TeV LHC data in the $W^+ W^-$ and $W^\pm Z$ production channels.

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arXiv2021

Dark Matter, Muon Anomalous Magnetic Moment and the XENON1T Excess

A very economic scenario with just three extra scalar fields beyond the Standard Model is invoked to explain the muon anomalous magnetic moment, the requisite relic abundance of dark matter as well as the Xenon-1T excess through the inelastic down-scattering of the dark scalar.

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arXiv2020

A 96 GeV scalar tagged to dark matter models

Recently, the CMS Collaboration observed the hint of a resonance decaying to two photons at about 96 GeV with a local significance of $2.8σ$. While it is too early to say whether this will stand the test of time, such a resonance can easily be accommodated in many extensions of the Standard Model (SM). The more challenging part is to tune such an extension so that the required number of diphoton events is reproduced. Assuming that the new resonance is a scalar, we propose that the signal may come either from an ultraviolet complete model with vectorial quarks, or a model involving gluon-scalar and photon-scalar effective operators. We then incorporate this portal to several extensions of the SM that include one or more cold dark matter candidates, and try to investigate how the existence of such a scalar resonance affects the parameter space of such models. As expected, we find that with such a scalar, the parameter space gets more constrained and hence, more tractable. We show how significant constraints can be placed on the parameter space, not only from direct dark matter searches or LHC data but also from theoretical considerations like scattering unitarity or stability of the potential, and discuss some novel features of the allowed parameter space.

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