As a significant contribution to science, Assistant Professor Dr Amit Chakroborty and his Doctoral Scholar, Arindam Basu, from the Department of Physics have published a groundbreaking paper titled, Viability of boosted light dark matter in a two-component scenario in the Physics Review D (Nature Index ) Journal. The research explores a two-component dark matter model and addresses the theoretical challenges in hopes of improving our understanding and painting a complete picture of dark matter.

Abstract

We study the boosted dark matter (BDM) scenario in a two-component model. We consider a neutrinophilic two-Higgs doublet model (ν2HDM), which consists of one extra Higgs doublet and a light right-handed neutrino. This model is extended with a light (∼ 10 MeV) singlet scalar DM ϕ3, which is stabilized under an extra dark ZDM symmetry and can only effectively annihilate through the CP even scalar H. Although the presence of a light scalar H modify the oblique parameters to put tight constraints on the model, the introduction of vectorlike leptons (VLL) can potentially salvage the issue. The vectorlike doublet N and singlet χ are also stabilized through dark ZDM symmetry. The lightest vectorlike mass eigenstate (χ1 ∼ 100 GeV) is the second DM component of the model. Individual scalar and fermionic DM candidates have Higgs/Z mediated annihilation, restricting the fermion DM in a narrow mass region while a somewhat broader mass region is allowed for the scalar DM. However, when two DM sectors are coupled, the annihilation channel χ1χ1 → ϕ3ϕ3 opens up. As a result, the fermionic relic density decreases, and paves way for broader fermionic DM mass region with under-abundant relic: a region of [30 − 65] GeV compared to a narrower [40 − 50] GeV window for the single component case. On the other hand, the light DM ϕ3 acquires significant boost from the annihilation of χ1, causing a dilution in the resonant annihilation of ϕ3. This in turn increases the scalar DM relic, allowing for a smaller mass region compared to the individual case. The exact and underabundant relic is achievable in a significant parameter space of the two-component model where the total DM relic is mainly dominated by the fermionic DM contribution. The scalar DM is found to be sub-dominant or equally dominant

Practical Implementation/ Social Implications of the Research:

This research explores a new idea in the search for dark matter, the invisible substance that makes up most of the matter in our universe. Instead of assuming dark matter is made of just one kind of particle, this study investigates a two-component model, where a heavier dark matter particle can decay or interact to produce a lighter, faster one. These “boosted” light dark matter particles could leave detectable traces in experiments here on Earth. The study carefully examines how this model fits with current cosmological observations and what conditions are needed for it to work.

While the work is theoretical, it has strong practical implications: it can guide ongoing and future experiments in detecting dark matter more effectively. Understanding dark matter is one of the most important unsolved problems in physics, and progress here could lead to understanding more about the picture of the universe. In the broader sense, such deep-space research inspires innovation, sharpens technology, and fuels curiosity-driven science that ultimately benefits society.

Collaborations:

This work has been done in collaboration with Mr Arindam Basu, PhD Scholar, the Department of Physics, SRM University-AP.

Future Research Plans:

• Study of the Dark Matter Direct Detection prospects.
• Study of the Dark Matter Indirect Detection prospects.
• Searching new physics at energy frontier.

The link to the article

In the quest for next-generation organic electronic materials, researchers have drawn inspiration from nature’s intricate designs. A groundbreaking study titled “Bulk Assembly of Intrachain Folded Aromatic Polyamides Facilitating Through-Space Charge Transport Phenomenon” led by Dr Sabyasachi Mukhopadhyay, Associate Professor in the Department of Physics, introduces a novel class of polymers that mimic the secondary structures of biomolecules. Published in the high-impact Q1 journal SMALL with an Impact Factor of 13.0, this research unveils the potential of intrachain folded aromatic polyamides in facilitating efficient through-space charge transport.

Abstract :
This study presents the design and synthesis of periodically grafted aromatic Polyamides capable of intrachain folding, mimicking secondary structures seen in biomolecules. Leveraging the immiscibility between aromatic backbones and Polyethylene glycol (PEG) side chains, the polymers self-assemble into lamellar, phase-separated domains with ordered π-stacking.

The structural order is further enhanced by incorporating aromatic guest molecules, enabling efficient through-space charge transport. Structural and morphological investigations via SAXS, WAXS, AFM, and TEM confirm the formation of highly ordered π-domains. Charge transport measurements reveal vertical current densities as high as 10⁻⁴ A/cm² in annealed host–guest complexes, comparable to conventional conjugated polymers, demonstrating the potential of these materials for stable, anisotropic organic electronics.

Practical implementation :

This research provides a new strategy for designing flexible, stable, and efficient organic electronic materials without the need for traditional conjugated polymers. The ability to precisely control the orientation and spacing of conductive regions at

The nanoscale opens doors for:

• Wearable and stretchable electronics
• Flexible sensors and low-power devices
• Organic transistors and memory devices with tunable directionality
• Environmentally stable devices, useful in humid or high-temperature conditions
• These innovations can lower manufacturing costs, enhance sustainability, and enable novel applications in healthcare, IoT, and smart textiles.

This research was a collaborative effort between multiple departments and institutions including Department of Chemical Sciences, IISER Mohali, Department of Physical Sciences, IISER Mohali and Department of Physics, SRM University – AP (Ramkumar K, Dr Sabyasachi Mukhopadhyay) and was supported by Department of Science and Technology – Science and Engineering Research Board (DST-SERB)

Future research plans:

Dr Sabyasachi Mukhopadhyay is  working towards “Integrated Center for Organic Electronics” – a multidisciplinary innovation hub focused on designing the next generation of flexible, sustainable, and high-performance electronic materials and devices.

Dr Basabendu, Dr Amit Chakraborty, and Mr Arindam Basu from the Department of Physics at SRM University-AP jointly authored the study titled, “Testing leptogenesis and dark matter production during reheating with primordial gravitational waves” which was published in Physical Review D (Nature Index). The research looks into different monomial potentials and various decay processes of the inflaton field, providing important insights into fundamental cosmic events.

Abstract:

We study the generation of baryon asymmetry as well as dark matter (DM) in an extended reheating period after the end of slow-roll inflation. Within the regime of perturbative reheating, we consider different monomial potential of the inflaton field during reheating era. The inflaton condensate reheats the Universe by decaying into the Standard Model (SM) bath either via fermionic or bosonic decay modes. Assuming the leptogenesis route to baryogenesis in a canonical seesaw framework with three right handed neutrinos (RHN), we consider both the radiation bath and perturbative inflaton decay to produce such RHNs during the period of reheating when the maximum temperature of the SM bath is well above the reheating temperature. The DM, assumed to be a SM gauge singlet field, also gets produced from the bath during the reheating period via UV freeze-in. In addition to obtaining different parameter space for such nonthermal leptogenesis and DM for both bosonic and fermionic reheating modes and the type of monomial potential, we discuss the possibility of probing such scenarios via spectral shape of primordial gravitational waves.

Practical Implementations & Social Impact:

Imagine the early universe as a giant, chaotic fireball after the Big Bang. But before things settled down into the stars and galaxies we see today, the universe went through a phase called inflation—a rapid expansion driven by a field called the inflaton. Once inflation ended, the inflation’s energy had to somehow convert into all the particles that make up our universe. This process is called reheating. In this study, we explore what happens if reheating takes longer than usual, extending well beyond what’s typically assumed. We look at different ways the inflaton could decay—either into particles like fermions (similar to electrons) or bosons (like the Higgs boson)—and how this affects the formation of two big cosmic mysteries: the matter-antimatter asymmetry (baryon asymmetry) and dark matter. We analyse how different inflaton decay mechanisms and different types of inflaton energy landscapes (represented by mathematical potentials) influence these processes. Beyond just predicting what parameters could make this scenario work, we also suggest a possible way to test it: by looking at primordial gravitational waves, ripples in spacetime left over from the early universe. Their specific features might reveal hints about how reheating played out, offering a new way to probe the origins of matter and dark matter.

This study is not just about abstract physics—it’s about our origins. Understanding how matter and dark matter formed in the early universe connects directly to our existence and could shape future discoveries in physics, technology, and space exploration. Whether it’s through deep-space telescopes, gravitational wave detectors, the quest to understand the first moments of the universe is one that could transform the way we see our place in the cosmos.

Collaborations:

This work has been done in collaboration with Dr Amit Chakraborty and Mr Arindam Basu from the Department of Physics, SRM University-AP

Future Plans:

A closer look at early universe dynamics by performing more involved simulations.
Connection between particle physics models and early Universe cosmology.
Complementary searches from different experiments in unravelling new physics beyond the Standard Model. Searching for new physics at the energy and intensity frontier.

Link: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.111.055016

In the paper titled “Ternary Heteroatom-doped Carbon as a High-performance Metal-free Catalyst for Electrochemical Ammonia Synthesis.” by Prof. Ranjit Thapa and his research Scholars, a novel approach to enhance nitrogen reduction reactions (NRR) is explored. This research, published in ACS Applied Materials & Interfaces, investigates the potential of nitrogen-doped carbon materials further enhanced by the incorporation of boron and fluorine heteroatoms. The study reveals significant advancements in electrocatalytic performance, emphasising the importance of efficient and sustainable ammonia production.

Abstract :
Electrochemical nitrogen reduction reaction (NRR) has garnered much attention, but the major challenge remains with efficient electrocatalysts. Metal-free carbonaceous materials, doped with heteroatoms and structural defects, present a promising alternative to metal-based catalysts. This study introduces a novel strategic stepwise synthesis strategy of defective nitrogen-doped carbon material, further doped with secondary heteroatoms boron and fluorine (FBDG). These secondary atoms in combination create additional active sites for nitrogen adsorption, activation and suppress the hydrogen evolution reaction (HER). The synergistic effect of three heteroatoms and induced defects in the catalyst enhances electron-donor behaviour, improving π bonding within the carbon framework and facilitating the electron transfer processes during NRR, resulting in a significantly high Faradaic efficiency of 38.1 % in the case of metal-free electrocatalysts. The theoretical calculation reveals that FBDG possesses sufficient charge density to reduce nitrogen at a low overpotential following an alternating free energy pathway. The reaction intermediates are thereby identified by in situ ATR-FTIR studies. For rapid screening of ammonia, we used a rotating ring disk system (RRDE) and did a kinetic study. The high efficiency, stability, and cost-effectiveness of FBDG position it as a strong contender for sustainable ammonia production and open up the way for future advancements in NRR.

Practical implementation:
The practical implementation of your research or the social implications associated with it.The FBDG catalyst achieved a remarkable Faradaic efficiency of 38.1 %. Theoretical studies confirmed that FBDG has a low overpotential, thereby increasing its appropriateness for NRR. The incorporation of fluorine and boron through co-doping in N-doped defective material enhances the N2 absorption energy, and from the charge density difference, we showed improved electron delivery from the host surface to the intermediate, which is essential for breaking the strong triple bond in N2 molecules, enhancing NRR. This work not only introduces a novel catalyst design strategy but also provides deep insights into the synergistic effects of heteroatom doping and defect engineering, paving the way for more efficient and sustainable ammonia production.

Collaborations

Dr Ramendra Sunder Dey, Assistant Professor (Scientist-D), INSA Associates, Institute of Nano Science and Technology, Mohali

Dr Amit Chakraborty, Assistant Professor in the Department of Physics and Ms Shreecheta Chowdhury, PhD Scholar, have co-authored a research paper titled “Boosted top tagging through flavour-violating interactions at the LHC”, which has been published in the European Physical Journal C (Nature Index), Q1 Journal having an impact factor 4.2.

Their research focuses on identifying a rare process involving the top quark, one of the heaviest particles. In this rare decay, the top quark transforms into a charm quark and a Higgs boson, which then breaks down into two b quarks. The team uses the data collected at the Large Hadron Collider (LHC), the world’s largest particle smasher, and employs Machine Learning techniques to investigate the possibility of understanding these collision events and identifying signatures of physics Beyond the Standard Model.

Abstract

This paper describes a method for detecting a rare top quark decay into a charm quark and a Higgs boson (H), which decays further into b quarks, at the Large Hadron Collider (LHC), and introduces a tagging algorithm to identify boosted tops using large-R jets containing b- and c-tagged elements. We consider the associated production of the top quark with a W-boson and identify different observables to discriminate the signal from the Standard Model (SM) background events. Although our model with improved jet substructure methods outperforms existing approaches to tag such rare decay tops, the improvement in the New Physics reach in terms of t → cH branching ratio is marginal, even at the high luminosity run of LHC, compared to the existing limits from the LHC 13 TeV data. Additionally, the paper utilizes SHAP, a Game Theory-based method, to analyse the contribution of each observable to the classification of events, offering valuable insights into the classifier.

Future Research Plans

The team plans to explore Beyond Standard Model (BSM) physics through collider phenomenology. Leveraging the Higgs boson as a portal, they aim to investigate its potential role in dark matter interactions, neutrino mass generation, and possibly being part of a larger scalar sector. Additionally, Dr Chakraborty will delve into ultra-light particle searches and develop novel jet physics techniques using advanced Machine Learning (ML) algorithms for particle identification and classification. A crucial aspect of his work will be creating testable search strategies, ensuring direct comparison with experimental data from current and future colliders.

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