Cosmic Origins and the Search for New Physics

19 Jan 2026, 05:15 → 23 Jan 2026, 20:00 Asia/Kolkata

Saha and Sarabhai Auditoriums (Indian Institute of Technology Madras, Research Park)

This Conference will focus on the physics related to the early universe. With the detection of gravitational waves by the LIGO-VIRGO collaboration and the hint of a stochastic gravitational wave background by the pulsar timing arrays, there has arisen a tremendous scope for constraining the primordial correlations over small scales. In the coming decades, primordial gravitational waves are expected to be constrained over a wide range of frequencies.  It has been recognized that these observations will perfectly complement those involving anisotropies and spectral distortions in the cosmic microwave background, distribution of the large scale structure, and observations of neutral hydrogen, over larger scales. There has been significant theoretical and observational developments in these directions over the last few years,   leading to a substantial gain in our understanding of the physics operating in the early universe. In particular, the observations have led to certain cosmic anomalies, which may require new physics to resolve. This Conference is aimed at bringing together experts on the origins of the primordial perturbations and their evolution through the history of the universe to examine if recent observations point to new physics. Broadly, the following topics will be covered:

• Origin and evolution of primordial perturbations
• Sources of primordial gravitational waves and their detection
• Primordial magnetic fields and their signatures
• Nature and origin of dark matter
• Masses of neutrinos and implications for cosmology
• Anomalies and tensions in cosmology

 

Scientific organizing committee

Fabio Finelli (INAF OAS, Bologna)
Dhiraj Hazra (IMSc, Chennai)
Raghuveer Garani (IITM, Chennai)
Laura Lopez-Honorez (ULB, Brussels)
L. Sriramkumar (IITM, Chennai)
Vincent Vennin (LPENS, Paris)

Monday 19 January

09:30 → 09:45 Welcome

09:45 → 10:30 Loop corrections to inflationary power spectra: Matteo Braglia

10:30 → 11:00 Coffee Break

11:00 → 11:45 Testing cosmic inflation with gravitational wave experiments: Gianmassimo Tasinato

madras_26_GT.pdf

11:45 → 12:15 Gravitational Reheating: Debaprasad Maity

Our present understanding of the reheating phase is incomplete due to a
lack of observations. Apart from its cosmological implications, the reheating should
play a vital role in particle physics and inflation model building. Conventionally
reheating dynamics are modeled by invoking arbitrary coupling among the inflaton
and daughter fields. Such an approach lacks robust cosmological predictions due
to its arbitrary couplings and is difficult to verify through observation. In this talk, we
discuss reheating scenario where the inflaton is coupled with all the daughter fields
only gravitationally. Besides being successful in reheating the Universe, the
scenario offers a strong cosmological prediction of the primordial gravitational
wave spectrum and rich dark matter phenomenology.

Debu-Chennai--2026-jan.pdf

12:15 → 12:35 Route to Accurate Inference of Dark Energy using Gravitational Waves: Samsuzzaman Afroz

DE_IITMadras.pdf

12:35 → 14:00 Lunch

14:00 → 14:30 21-cm cosmology - the global signal perspective: Mayuri Rao

COSNP.pdf

COSNP.pptx

Mayuri_COSNP_21cm.pdf

14:30 → 15:00 Primordial gravitational waves: Debika Chowdhury

Primordial Gravitational Waves (PGWs) provide us with an important
observable for studying a variety of early-universe phenomena. In this talk, I shall
discuss the properties of GW spectra generated in both standard as well as
non-standard cosmological scenarios. I shall discuss about possible synergies
between GW detectors, with the aim of a multi-band detection of a cosmological
stochastic GW background. Additionally, I shall talk about the effects of kinematic
anisotropies on the GW signal, and their detection prospects with the upcoming
Einstein Telescope.

debika-cosnp-2026-slides.pdf

15:00 → 15:20 Production of Gravitational Waves from Preheating and Tachyonic Instabilities: Khursid Alam

We analyze GW production during preheating for an $\alpha$-attractor
potential terminating in the positive-curvature regime, with energy transfer via
$\phi\chi^{2}$. Linear Floquet analysis and nonlinear simulations show that $\phi$
fluctuations grow by parametric resonance, while $\chi$ undergoes tachyonic
bursts. The GW spectrum features two peaks: a dominant low-frequency peak
from the parametric channel and a subdominant high-frequency peak from the
tachyonic channel. Redshifted to today, the peak reaches $h^{2}\Omega_{\rm GW}^{(0)} \sim 10^{-11}$ at $f_{p} \sim 10^{7}$ Hz. This multi-peak structure is a
characteristic imprint of trilinear preheating in $\alpha$-attractors.

Slide_for_IIT_Madraj.pdf

15:20 → 16:00 Coffee Break

16:00 → 16:20 Primordial magnetism in the light of cosmic dawn and post-EoR observables: Arko Bhaumik

During the pre-reionization epoch, a primordial magnetic field (PMF) is
expected to influence 21-cm physics via two distinct physical pathways, namely
magnetic heating of the intergalactic medium through ambipolar diffusion and
decaying turbulence, and modification of the star formation rate through
small-scale enhancement of matter power. In this talk, I shall discuss a recent work
of ours where both effects have been integrated within a common analytic
framework, which has subsequently been used to provide upper bounds on the
PMF parameter space in the light of the global 21-cm signal reported by EDGES.
This leads to a typical upper limit of 10 pG on a nearly scale-invariant PMF, which
is strongly competitive with bounds obtained from other cosmological datasets
available at present. Our forecast analysis for the upcoming SKA-Low facility
sheds light on the prospect of further constraining the PMF window that is
consistent with the EDGES observation, projecting $1\sigma$ errors
$\lesssim10\%$ on the relevant PMF parameters and an associated
signal-to-noise ratio (SNR) $\gtrsim10$. During the post-reionization epoch, on the
other hand, the PMF-enhanced matter power on small scales is expected to
strongly affect the Lyman-$\alpha$ power spectrum and cross-correlations
between Lyman-$\alpha$ and 21-cm fluctuations, which may thus serve as
important probes of the PMF sector at late times. I shall conclude by briefly
discussing our ongoing work in this direction in the light of upcoming 21-cm and
large scale survey missions.

arko_bhaumik_cosnp.pdf

16:20 → 16:40 Gravitational Wave Signature and the Nature of Neutrino Masses: Majorana, Dirac, or Pseudo-Dirac?: Sudip Manna

In this talk, I will explore how gravitational-wave (GW) signatures can
reveal the nature of neutrino masses—Dirac, Majorana, or pseudo-Dirac. Within
the minimal $B-L$ gauge extension of the Standard Model, I will show that
Majorana neutrinos with high-scale breaking produce flat GW spectra from cosmic
strings, Dirac neutrinos with low-scale breaking generate peaked spectra from
first-order phase transitions, and pseudo-Dirac scenarios lead to kink-like features
from domain wall annihilation.

sudip_manna_iitm_slides.pdf

16:40 → 17:00 Role of Next Generation Cosmological Surveys in Identifying Primordial Features: Debabrata Chandra

Primordial features are specific model-dependent corrections on top of
the standard power-law inflationary power spectrum, where different functional
forms come from different inflationary scenarios. Signature of any significant
departure from the feature-less power spectrum will enable us to decipher the
intricacies of the inflationary Universe. Here, we delve into three major yet distinct
features, namely, Bump feature, Sharp feature signal, and Resonance feature
signal. To analyse the features, we adopt a specific template for each feature
model. We estimate the possible constraints on the feature parameters by
employing Fisher matrix forecast analysis for the upcoming CMB missions such as
CMB-S4, CORE-M5, LiteBIRD, PICO conjointly with DESI, and EUCLID galaxy
surveys and upcoming SKA surveys (wherein we explore SKA-Cosmic Shear and
SKA-Intensity Mapping surveys). Furthermore, the significance of combining
EUCLID-Galaxy surveys with the SKA-Intensity Mapping survey is also explored. A
comparative analysis of all three features has been done to estimate relative
capabilities of these upcoming observations in shedding light on this crucial aspect
of precision cosmology. This analysis will help us to understand quantitatively the
competence of forthcoming cosmological surveys in detecting primordial features
in the primordial power spectrum.

Debabrata_Chandra.pdf

19:00 → 20:00 Dinner

Tuesday 20 January

09:30 → 10:15 Entanglement and correlations between local observables in de Sitter spacetime: Ivan Agullo

de Sitter curvature enhances two-point correlations at super-Hubble
distances. Likewise, the von Neumann entropy of local patches is enhanced by
curvature, implying stronger entanglement between any compact region and its
complement. This talk will present a series of recent calculations of correlations
and entanglement between local observables (i.e. compactly supported) in bosonic
field theories in the cosmological patch of de Sitter space. We conclude that, when
restricting to local observables, curvature degrades entanglement. I will argue that
this result is compatible with previous studies based on entropy and correlation
measures, when properly interpreted. Our results reveal interesting features of how
entanglement in the de Sitter–invariant vacuum is spatially distributed. These
findings have implications for entanglement between observables generated
during cosmic inflation.

AgulloChennai.pdf

10:15 → 11:00 The High-redshift Universe in the Era of JWST and 21 cm Cosmology: Tirthankar Roy Choudhury

The Epoch of Reionization and Cosmic Dawn, eras marked by the
emergence of the first galaxies, represent the final frontiers of observational
cosmology. This talk examines the immense potential of unifying a variety of
observational probes to reconstruct the evolutionary history of the early Universe. It
highlights the powerful synergy between the Cosmic Microwave Background,
quasar absorption spectra, the unprecedented high-redshift galaxy populations
revealed by JWST, and the anticipated 21 cm signal. Particular emphasis is placed
on the need for consistent modelling of galaxies and the intergalactic medium to
robustly interpret these multi-messenger datasets. The talk also explores the
critical role of advanced statistical frameworks, including machine-learning-driven
inference techniques, in breaking long-standing parameter degeneracies. Finally, it
discusses how these combined probes can not only constrain astrophysical
mechanisms but also provide sensitive tests of the standard Lambda-CDM
paradigm and potential new physics at high redshift.

TRC-IITM.pdf

11:00 → 11:30 Coffee Break

11:30 → 12:00 Charting the unobservable -- The early-universe as an open quantum system: Suddhasattwa Brahma

IITM_COSNP_2026.pdf

12:00 → 12:30 Scalaron dark matter dynamics in f(R) gravity: Koushik Dutta

Koushik_Dutta_IIT_Chennai_2026.pdf

12:30 → 14:00 Lunch

14:00 → 14:45 Exotic energy injection during cosmic dawn

Speaker: Dr Sergio Palomares Ruiz

Chennai_COSNP_2026_PalomaresRuiz.pdf

14:45 → 15:15 Gravitational wave background from primordial magnetic field

Speaker: Dr Ramkishor Sharma

cosnp_madras_ramkishor.pdf

15:15 → 15:35 Probing Extended Mass Distributions of Primordial Black Holes in NANOGrav and LVK

Speaker: Dr Nilanjandev Bhaumik

QCD_PBH_iitm_2026_nilanjandev_bhaumik.pdf

15:35 → 16:00 Coffee Break

16:00 → 16:20 Dark matters are completely dark, or WIMPy, or FIMPy : An Inflationary gravitational particle production

Speaker: Mr AYAN CHAKRABORTY

COSNP IITM Ayan Chakraborty.pdf

16:20 → 16:40 Implications of self-interactions of ultralight dark matter at galactic scales

Speaker: Dr Bihag Dave

Bihag_COSNP_talk.pdf

16:40 → 17:00 Loops in Cosmological Correlators

Speaker: Ms Supritha Bhowmick

COSNP (1).pdf

19:00 → 20:00 Dinner

Wednesday 21 January

09:30 → 10:15 Warm and Noisy Cosmological Fields

Speaker: Mustafa Amin

10:15 → 11:00 Isocurvature bounds on PBHs and non-Gaussianity

Speaker: Jinn-Ouk Gong

11:00 → 11:30 Coffee Break

11:30 → 12:00 Understanding the Universe with the cosmic microwave background

Speaker: Rishi Khatri

IITM2026.pdf

12:00 → 12:30 Using the early universe as a quantum laboratory

Speaker: Patrick Peter

Chennai2026.pdf

12:30 → 14:00 Lunch

14:00 → 14:20 Reconstructing primordial features on large scales using machine learning

Speaker: Alipriyo Hoory

14:20 → 14:40 Primordial Magnetogenesis as a Unified Origin of PBHs, Dark Matter, and Gravitational Waves

Speaker: SUBHASIS Maiti

14:40 → 15:00 Asymmetries from Primordial Black Holes

Speaker: Koushik Loho

15:00 → 15:20 Capturing the 21-cm signal in radio interferometers

Speaker: Asif Elahi

15:20 → 16:30 Coffee Break

Move to department of Physics for Chandrasekhar lecture by Joseph Silk

16:30 → 18:00 Chandrasekhar Lecture: Current and Future Prospects for the CMB-- Joseph Silk

The cosmic microwave background provides a unique view of the beginning of the Universe, some 380,000 years after the Big Bang. I will review the successive improvements in studies of the tiny fluctuations that trace the seeds of structure, and how they have led to the emergent field of precision cosmology. The next decades are likely to lead to a transformative period in our pursuit of the frontiers of cosmology and the CMB will play a key role in this challenging future.

19:00 → 20:00 Dinner

Thursday 22 January

09:30 → 10:15 Cosmic Hum of Gravitational Waves from the Early Universe

Speaker: Suvodip Mukherjee

10:15 → 11:00 Looking for new physics via CMB and Gravitational Waves

Speaker: Nicola Bartolo

11:00 → 11:30 Coffee Break

11:30 → 12:00 Warm Inflation 2.0--The resurgence story

Speaker: Mayukh Gangopadhyay

12:00 → 12:30 From Poles to Branch Cuts--Analytic Structure of Cosmological Correlators

Speaker: Diptimoy Ghosh

12:30 → 14:00 Lunch

14:00 → 14:30 Effects of dissipation during the accelerating epochs

Speaker: Suratna Das

WI-dissipation.pdf

14:30 → 15:00 Cosmological Dynamics of Scalar Fields in String-Motivated Models

Speaker: Ivonne Zavala

15:00 → 15:20 Primordial Magnetogenesis with Dark Photons

Speaker: Debottam Nandi

15:20 → 16:00 Coffee Break

16:00 → 16:20 Power Suppression and Lensing Anomaly - A phenomenological investigation

Speaker: Roshana K

16:20 → 16:40 Constraining the early universe with NANOGrav 15-year data

Speaker: Suvashis Maity

16:40 → 17:00 Anomalies and tensions in cosmology

Speaker: Purba Mukherjee

19:00 → 20:00 Dinner

Friday 23 January

09:30 → 10:15 Gauge fields and parity violation in the early universe

Speaker: Rajeev Kumar Jain

10:15 → 11:00 Primary gravitational waves at high frequencies--Origin of suppression in the power spectrum

Speaker: Jerome Martin

11:00 → 11:30 Coffee Break

11:30 → 11:50 Bayesian optimisation for efficient cosmological model selection

Speaker: Ameek Malhotra

11:50 → 12:10 The importance of being warm in the Early Universe

Speaker: Dibya Chakraborty

12:10 → 12:30 AI/ML Techniques for Model-Independent Cosmological Analysis

Speaker: Rahul Shah

12:30 → 14:00 Lunch

14:00 → 14:30 Anchoring The Universe at Characteristic Redshifts and Measurement of the Hubble Parameter

Speaker: Anjan Ananda Sen

14:30 → 14:50 Validity of separate-universe approach in transient ultraslow-roll inflation

Speaker: Rathul Nath Raveendran

14:50 → 15:10 Non-minimal coupling of scalar fields in the dark sector and generalization of the top-hat collapse

Speaker: Priyanka Saha

15:10 → 15:30 Inflationary trispectrum of gauge fields from scalar and tensor exchanges

Speaker: Jishnu Sai

15:30 → 15:50 Emergence of the exponential cut-off in the spectrum of PGWs at small scales

Speaker: Arnab Paul

15:50 → 16:00 Closing remarks

16:00 → 16:30 Coffee Break

19:00 → 20:00 Dinner