IISER Pune Digital Repository

A repository of scholarly research output from the Indian Institute of Science Education and Research (IISER) Pune.

Browse publications, theses, and other research output produced by the IISER Pune community.

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OTHER RESOURCES 604
PUBLICATIONS & PATENTS 7239
THESES & PROJECT REPORTS 2998
Theses submitted to IISER Pune in partial fulfilment of the requirements of the BS-MS dual degree, MSc. and Ph.D programmes. Also, project reports submitted by the students.

Recent Submissions

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Hop-Wise Adaptive Spectral Filters for Graph Representation Learning
(Association for Computing Machinery, 2026-09) Nair, Harishankar K.; MEENAKSHISUNDAR, KSHREYA; Reena Monica P.
In recent years, learning over relational data has emerged successful with Graph Neural Networks due to its high representational capacity. Node-level representation learning on graphs faces the major challenge of performance degradation on heterophilic graphs. Standard message-passing networks aggregate neighborhoods through repeated low-pass filtering, neglecting high-frequency signals which stand vital in heterophilous graphs. Existing methods apply a single shared filter across all propagation depths which prevents the model from learning different frequency responses at different hop distances. We propose Hop-wise Adaptive Spectral Message-Passing (HASM), a framework designed to assign independent Chebyshev spectral filter to each hop distance. Each filter is parameterized by learnable polynomial coefficients and a per-channel gate, which enables the model to simultaneously learn different responses at different propagation depths. We evaluate HASM on benchmarks, namely Co-author Physics, Roman-empire, Minesweeper, etc., showcasing significant performance gains of 0.08% to 6.27% on node classification.
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Fat-jet signatures of quintuplet fermions at the LHC
(2026-09) DUBE, SOURABH; Kumar, Nilanjana; RANJAN, SHRIYANSH; Dept. of Physics
This paper explores a simplified extension of the standard model featuring a neutral fermion quintuplet and a scalar quadruplet, which together generate neutrino masses through tree and loop level mechanisms. The quintuplet fermions decay into standard model gauge bosons via the scalars, producing unique collider signatures at the LHC characterized by multilepton and multijet final states. The study focuses on the pair production of quintuplet fermions in the 700–1200 GeV mass range, where their decays produce highly boosted 𝑊 and 𝑍 bosons identifiable as fat-jets. Emphasis is placed on the production and decay of doubly charged fermions due to their higher cross section. Advanced jet substructure and kinematic techniques are applied to enhance sensitivity by reducing standard model backgrounds. A detailed analysis of signal significance is performed in the two lepton, two fat-jet (2⁢L⁢2⁢Fj) and three lepton, one fat-jet (3⁢L⁢1⁢Fj) channels for different masses of the fermion and the scalars, optimizing selection cuts to maximize signal efficiency over standard model backgrounds. The study found that both channels exhibit excellent performance, with significance exceeding 5⁢𝜎 under realistic conditions including a 50% background uncertainty at integrated luminosities up to 3000 fb−1.
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Discovery prospects of a singly charged scalar at 𝜇⁢TRISTAN
(American Physical Society, 2026-08) GEORGE, JOSEPH; Okada, Nobuchika; Sengupta, Dibyashree; Vempati, Sudhir K.; Dept. of Physics
In this article, we study the associated production of a singly charged (Δ+) scalar along with a 𝑊+ boson in the newly proposed 𝜇+⁢𝜇+ collider (also known as 𝜇⁢TRISTAN) at √𝑠 =2 TeV. Such a singly charged scalar is naturally accommodated in an extremely well-motivated neutrino mass model, namely, the Type-II seesaw model. This model, besides providing a viable explanation of neutrino mass generation, also allows for lepton flavor violating (LFV) processes. Since LFV processes are not allowed in the standard model (SM), we focus on the discovery prospect of the singly charged scalar in the Type-II seesaw model at 𝜇⁢TRISTAN through a LFV process, owing to the advantage of this process being free of any SM background. Additionally, this article also proposes a method to indicate if the underlying theory follows a normal or an inverted hierarchy depending on the distribution of lepton flavors in the final state.
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Halide Substitution Driven Symmetry Breaking in a Ferroelectric Mixed-Halide Halogenometallate for Piezoelectric Energy Harvesting
(American Chemical Society, 2026-08) GOSWAMI, ASHLESHA S.; DEKA, NILOTPAL; GADAGIN, VINAYAK B.; Zaręba, Jan K.; BOOMISHANKAR, RAMAMOORTHY; Dept. of Chemistry
Halide substitution provides a compelling yet underexplored route to engineer polar, noncentrosymmetric solids with emergent ferroelectric functionality. Herein, we report a new ammonium-based mixed-halide halogenometallate, [BTMA]2CdBr2I2, that crystallizes in the polar P21 space group and exhibits coupled ferroelectric and piezoelectric responses. The noncentrosymmetric nature of the structure is confirmed by its pronounced second harmonic generation (SHG) activity. Bulk ferroelectricity is evidenced by a well-saturated, rectangular polarization–electric field (P–E) hysteresis loop with a polarization of 4.43 μC cm–2, while piezoresponse force microscopy (PFM) directly visualizes switchable ferroelectric domains, confirming intrinsic polarization at the microscale. Beyond these fundamental properties, we further demonstrate device-level functionality by integrating [BTMA]2CdBr2I2 into flexible thermoplastic polyurethane (TPU) composites. The optimized 10 wt % composite delivers a high piezoelectric nanogenerator output voltage of 15.9 V, a power density of 10.24 μW cm–2, and an output work efficiency (OWE) of 23.7%. These results not only establish mixed halide engineering as a viable strategy to access polar molecular materials but also position halogenometallate-based hybrids as promising candidates for flexible, high-performance energy harvesting technologies.
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To Dope Mo3+ in Colloidal Nanocrystals
(Wiley, 2026-09) SARMA, MANMAYURI; MONDAL, BARNALI; Mukhuti, Kingshuk; Puttisong, Yuttapoom; NAG, ANGSHUMAN; Dept. of Chemistry
Mo3+ shows intra-configurational spin-flip (ICSF) d → d electronic transitions, emitting near-infrared-II (NIR-II) radiation. Till date, the emission has been reported from Mo3+-doped into bulk host materials, in the powder or single crystalline forms. Here we report the synthesis of Mo3+ doping in a colloidal nanocrystal (NC). Colloidal Mo3+-doped Cs2AgInCl6 double perovskite NCs are prepared using a typical hot-injection method in a non-polar medium. The challenges of poor solubility of molybdenum precursor and instability of low oxidation state of Mo3+ in the reaction medium are overcome by a rational design of the synthesis. The resulting NCs have cubic shape with edge length ∼9 nm, and oleylammonium ions as the predominant surface capping ligands. The colloidal synthesis enabled us to fabricate thin films of Mo3+-doped NCs by spin-coating technique. Both colloidal NCs and their films show the sharp Mo3+ ICSF NIR-II emission around 1105 nm. Temperature dependent (7-300 K) PL spectra and lifetime studies provide mechanistic insights about the spin- and Laporte-selection rules of the ICSF emission from [MoCl6]3− octahedral unit. This report of a colloidal NC with Mo3+ dopants, and their thin films, is expected to open up research avenues for micro-LEDs and quantum light emitters in NIR-II region.