Seminar Organizer: Kumar Abhinav
Previous Series Lists [Series 1, Series 2, Series 3, Series 4, Series 5, Series 6, Series 7]
Series 8
Upcoming:
On 17th of March 2025 at 14:00 hrs ICT
Title: A Multi-field Inflatory Scenario in Loop Quantum Cosmology-II
Abstract: Loop Quantum Gravity (LQG) – a non-perturbative and background independent canonical quantization of GR formulated in the Yang–Mills phase space, stands as a compelling quantum gravity candidate. Loop Quantum Cosmology (LQC), obtained by applying LQG techniques to symmetry-reduced cosmological spacetimes generically replaces “Big Bang” with a non-singular quantum bounce purely due to quantum geometric effects.
While single scalar field sourced LQC models are extensively studied in the literature, this thesis advances the study of early universe dynamics by constructing a multi-field LQC model with a non-trivial field space metric. We systematically investigate two representative multi-field inflationary models — a hybrid inflation potential and an interacting two-field potential model — within the holonomy corrected dynamics of LQC. Starting from the Hamiltonian formulation in Ashtekar variables and implementing the ¯μ-scheme polymerization, we derive and numerically evolve the modified multi-field Friedmann and Klein–Gordon equations initializing with a kinetic energy dominated (KED) quantum bounce to study the early universe regimes.
In this talk, after briefly reviewing these foundational aspects, I will present our analysis confirming the robustness and universality of the post-bounce sequence in the multi-field driven LQC setup in the following order:
- A quantum-gravity driven superinflationary phase characterized by H>0,
- A transition phase,
- a finite slow-roll phase.
We find that inflationary outcomes depend sensitively on pre-inflationary initial conditions. A systematic scan of the initial phase space has been performed to identify regions of initial conditions that yield observationally viable ∼ 60 e-folds of inflation. In addition, a qualitative dynamical system analysis reveals distinct phase-space structures and the interplay among multi-field components and gravitational sectors for the two models with corresponding linear stability analysis highlighting the asymptotic behavior of the dynamical flow.
As a natural future extension, the higher-order stability analysis can be performed to further probe the highly non-linear phase space structure.
The canonical formulation presented in the thesis is generically constructed to elegantly accommodate, diverse multi-field scenarios with nontrivial spacetime, thus laying the groundwork for both qualitative and quantitative analyses to test robustness and phenomenological viability of polymerized spacetime dynamics.
Speaker: Divya Gupta, NAS-MUNA
| Sl. No | Date & Time | Title | Speaker & Afiliation |
| 1 | 1st Sep 2025 @ 14:00-15:30 ICT | Spin Structure of Proton at High Energy | Yossathorn Tawabutr, Chulalongkorn University |
| 2 | 9th Sep. 2025 @ 11:00-12:30 ICT | Testing the standard model of cosmology | Roy Maartens, University of Western Cape, South Africa |
| 3 | 16th Sep. 2025 @ 14:00-15:30 ICT | Symmetry arguments solving the problems of Dark Matter and Dark Energy | Ivan Arraut, University of St. Joseph, Macau |
| 4 | 14th Oct. 2025 @ 11:00-13:00 ICT | On the fundamental forces | Naresh Dadhich, IUCAA Pune, India |
| 5 | 2nd Dec. 2025 @14:00-15:30 ICT | Kinesis movement of animals with energy concern | Thiti Sirithanakorn, NAS-MUNA |
| 6 | 9th Dec. 2025 @ 14:00-15:30 ICT | Cosmology of non-minimally coupled scalar field under exponential potential with holographic vacuum: slow-roll, phase portraits, and late-time trajectories. (NWTP 691 Seminar Course Talk) |
Pakkapon Phaitha, NAS-MUNA |
| 7 | 22th Dec. 2025 @ 14:30-16:30 ICT | Gravitational collapse to regular black holes | Daniele Malafarina, Nazarbayev University |
| 8 | 30th Dec. 2025 @ 14:00-15:30 ICT | Multi-field scenario in Loop Quantum Gravity (Assessment of Student’s Progress and Research Performance for Thesis) | Divya Gupta, NAS-MUNA |
| 9 | 13th Jan. 2026 @ 14:00-15:30 ICT | Quantum Gravity is far from Quantum Cosmology – A top-down approach on the backdrop of discrete quantum gravity | Manabendra Sharma, NAS-MUNA |
| 10 | 27th Jan. 2026 @ 14:00-15:30 ICT | Operator approach of solving Quantum Mechanics | Kumar Abhinav, NAS-MUNA |
| 11 |
10th Feb. 2026 @ 14:00-15:30 ICT | From Arrays to Layers: Utilizing Multiplex Networks for Chemical Recognition | Pradeep Bhadola, NAS-MUNA |
| 12 | 17th Feb. 2026 @ 14:00-15:30 ICT | Uncovering Common Oncogenic Signatures Between Renal Cell carcinoma and Prostate Cancer: A Network-Based Approach | Vishal Cahudhary, NAS-MUNA |
| 13 | 23rd Feb. 2026 @ 14:00-16:00 ICT | Logarithmic corrections to near-extremal entropy of de Sitter black holes | Debangshu Mukherjee, POSTECH, Korea |
| 14 | 17th Mar. 2026 @ 14:00-16:00 ICT | A Multi-field Inflatory Scenario in Loop Quantum Cosmology-II (Ph.D. Pre-submission seminar) | Divya Gupta, NAS-MUNA |
| 15 | 31st Mar. 2026 @ 14:00-16:00 ICT | TBA | Arpita Mitra, NAS-MUNA |