Phoenix 2025

9 Jul 2025, 08:00 → 11 Jul 2025, 21:30 Asia/Kolkata

Convention Centre

Find more details at: https://sites.google.com/iith.ac.in/phoenix25iith/home

Wednesday 9 July

Inauguration

Conveners: Director (IITH), Dean Admin, Dean Faculty, HOD Physics

Plenary: Day 1, Session 1

Convener: Anjan Giri

1 Left-right symmetric models with lepton portal dark matter

I have proposed a simple model with (light) dark matters (DMs)
that interact with leptons via Yukawa couplings, with S. Okawa and S. Iguro.
The DMs can evade strong bounds from the DM direct detection experiments
and predict some specific signals at the LHC. In this talk, I review the work shortly, and
introduce a model with $SU(3)\times SU(2)_L \times SU(2)_R \times U(1)_{B-L} $ gauge symmetry and left-right (LR) symmetry, that can be interpreted as an underlying theory of the DM model.
LR symmetric models can solve the strong CP problem, but need realize DM and tiny neutrino masses. In our model, tiny neutrino masses are induced by loop corrections involving DM. We see correlation between the neutrino mass matrix and DM physics.

Speaker: Yuji Omura (Kindai University)

Omura_Phoenix25.pdf

2 Astrometric Microlensing of Primordial Black Holes with GAIA

Speaker: Vikram Rentala (Indian Institute of Technology Bombay)

AML GAIA presentation v4.pdf

3 Higher order thermal corrections to dark matter annihilations processes

We present results for higher order thermal corrections to both dark matter annihilation into fermion pairs, as well as annihilation along with photon absorption/emission. We show explicitly cancellation of soft and collinear divergences in the thermal theory and calculate the finite remainder. The corrections depend significantly on whether the dark matter particle is assumed to be Majorana or Dirac type particle.

Speaker: Indumathi D.

phoenix_2025_indumathi.pdf

11:00 Tea Break

Plenary: Day 1, Session 2

Convener: Tathagata Ghosh (HRI)

4 Blind spots in DM scenarios

Speaker: Dr Debottam Das (Institute of Physics)

dm_IITH_9.pdf

5 Mixing of the photon with axion and axion-like particles

Photons can mix with low-mass bosons in the presence of external electromagnetic fields. A known example is the hypothetical axion (spin 0) which can couple with the photon by a two-photon vertex. Other axion-like particles (ALP) have been proposed in many Beyond Standard Model (BSM) theories. In this talk we give a brief overview of the physics of axion and discuss the possibility of detecting axion and axion-like particles in different astrophysical observations and laboratory experiments. Constraints on the parameter space of axion mass and coupling are presented.

Speaker: Sourov Roy (Indian Association for the Cultivation of Science, Kolkata)

photon-axion-mixing-Phoenix-2025-IITH.pdf

6 Exploring MeV-scale U(1) Lmu-Ltau Extra Dimension through DUNE and muon beam dumps

In recent years, very weak interactions on the MeV scale, in particular the case of U(1) Lmu-Ltau, have attracted significant attention in the context of muon g-2, dark matter-mediated forces and others. This presentation will focus on how the extension of this U(1) symmetry to five dimensions can be explored in future new physics search experiments, concretely, the DUNE experiment and future muon beam dump experiments.

Speaker: Kenji Nishiwaki (Shiv Nadar Institute of Eminence)

Kenji-Phoenix2025_compressed.pdf

13:00 Lunch Break

Plenary: Day 1, Session 3

Convener: Subhendu Rakshit

7 Quark masses (in QCD-like theories)

Speaker: Tuhin Roy (Tata Institute of Fundamental Research)

QuarkMasses.pdf

8 Horizontal three Higgs-doublet model

I will present a variant of the 3HDM, referred to as the BGL-3HDM, incorporating a horizontal U(1)​×U(1)​ symmetry, which can distinguish the primary sources of mass for different fermion generations. In the version considered here, the Yukawa matrices in the down-quark and charged lepton sectors are diagonal, thereby eliminating tree-level FCNCs in these sectors. FCNC interactions mediated by neutral nonstandard Higgses are confined to the up-quark sector only. No new BSM parameters are introduced by the Yukawa sector of the model, making it as economical as the NFC versions of 3HDM with a U(1)×U(1) symmetry in terms of the number of free parameters. However, even in the down-quark and in the charged lepton sectors, flavor diagonal but nonuniversal Higgs couplings set this model apart from the NFC versions of the 3HDM.

Speaker: Dr Dipankar Das (Indian Institute of Technology, Indore)

Phoenix-DD.pdf

9 Baryogenesis from a Majorana Fermion Coupled to Quarks

In the theory with a Majorana fermion coupled to quarks via a dimension-six four-fermion vector-vector interaction, we show that the observed baryon asymmetry of the Universe can be generated in the decay and scattering processes in the expanding early Universe. In viable parts of parameter space we discuss the observability of neutrino-antineutron oscillation in upcoming experiments.

Speaker: Shrihari Gopalakrishna (Institute of Mathematical Sciences)

16:00 Tea Break

Plenary: Day 1, Session 4

Convener: Narendra Sahu (Indian Institute of Technology Hyderabad)

10 Multi-messenger astronomy with quenched superradiance

Speaker: Ujjal Kumar Dey (IISER Berhampur)

11 Confronting new physics with early universe cosmology

In this talk I shall elucidate how early universe cosmology, together with gravity, can provide a window in exploring physics beyond the Standard Model (SM). Typically, I will focus on two long-standing puzzles of particle-cosmology, namely, dark matter and matter-antimatter asymmetry. In this context I will also discuss the role of the primordial gravitational wave (GW), having different origins, in testing such scenarios at the (futuristic) GW experimental facilities.

Speaker: Basabendu Barman

phoenix_BB.pdf

12 Sifting through the Standard Model for the hints of an ALP

​Flavor experiments commissioned to provide precise measurements of the Standard Model (SM) parameters are excellent laboratories to look for hypothesised particles, especially those with masses less than a GeV. In this talk, I discuss some experiments related to semi-leptonic charged current amplitudes, which can be veritable smoking guns for axion-like particles (ALPs). I show that the bounds obtained from such an exercise are only loosely sensitive to the mass of the ALP. I discuss results from NA48/2, Belle, and BaBar and also discuss how Belle-II projected sensitivities for tau to K decays can give bounds on the Wilson-coefficient space stronger than existing ones. I also discuss sum-rules arising from the modifications to chiral perturbation theory in the presence of an ALP, a framework that we have used to derive the results.

Speaker: Triparno Bandyopadhyay (SRMIST, Chennai)

phoenix_triparno.pdf

19:30 Dinner

Thursday 10 July

Plenary: Day 2, Session 1

Convener: Shrihari Gopalakrishna

13 Collider and gravitational wave signals for electroweak phase transition

The knowledge of the Higgs potential is crucial for understanding the origin of mass and the thermal history of our Universe. We show how collider measurements and observations of stochastic gravitational wave signals can complement each other to explore the multiform scalar potential in the two Higgs doublet model. In our investigation, we analyze critical elements of the Higgs potential to understand the phase transition pattern. Specifically, we examine the formation of the barrier and the uplifting of the true vacuum state, which play crucial roles in facilitating a strong first-order phase transition. Furthermore, we explore the potential gravitational wave signals associated with this phase transition pattern and investigate the parameter space points that can be probed with LISA. Finally, we compare the impact of different approaches to describing the bubble profile on the calculation of the baryon asymmetry.

Speaker: dorival Gonçalves (Oklahoma State University)

Dorival_Phoenix_2025.pdf

14 From U (1)×U (1) Symmetry Breaking to Majoron Cosmology: Insights from NANOGrav 15-year Data

Speaker: Tathagata Ghosh (HRI)

S1.2-Tathagata.pdf

15 High Energy Astrophysical Neutrinos

Speaker: Subhendu Rakshit (IIT Indore)

S1.3-Subhendu.pdf

16 Overview of BSM Searches with boosted objects at the CMS experiment

Speaker: Swagata Mukherjee

S1.4-Swagata.pdf

11:00 Tea Break

Plenary: Day 2, Session 2

Convener: Saurabh Sandilya (Indian Institute of Technology Hyderabad)

17 Neutrino Oscillations & New Physics Effects

Speaker: Moon Moon Devi

S2.1-Moonmoon.pdf

18 ENUBET and SBN@CERN proposal

The poor knowledge of neutrino cross sections at the sub-GeV scale will represent the main systematic uncertainty for the next-generation oscillation experiments. SBN@CERN is a proposal for a short baseline neutrino beam with proper instrumentation along the beamline and in the decay tunnel, based on ENUBET and NuTag projects, which will enable flux monitoring at the percent level and provide a neutrino energy determination independent of final state particle reconstruction at the neutrino detector. As a result, it eliminates the two primary sources of systematic uncertainty in cross-section measurements: flux normalization and energy bias caused by nuclear effects. This talk will focus on the ENUBET project and how it came to be a part of SBN@CERN proposal. It will also show the physics potential of the full proposed SBN@CERN facility for the cross-section measurement.

Speaker: Budimir Klicek

S2.2-Budimir.pdf

19 Physics potential of the ESSnuSBplus setup

In this talk, I will discuss the physics potential of ESSnuSBplus setup on behalf of the ESSnuSB collaboration. ESSnuSB is an upcoming neutrino oscillation experiment to be based in Sweden. The ESSnuSBplus set up will consist of three neutrino sources i.e., the main neutrino beam from the ESS linac, low energy neutrinos from a monitored beam (LEMNB), and low energy neutrinos from a muon storage ring (LEnuSTORM). The neutrinos from the ESS linac will be detected at a distance of 360 km using a far detector (FD) to study neutrino oscillations at the second oscillation maximum. This far detector will be also used to study neutrinos from Sun, Earth’s atmosphere and future supernova explosion. The neutrinos from LEMNB will be detected at a near detector (LEMMOND) located at a distance of 50 m to measure cross-section to reduce the systematic uncertainties. Whereas the neutrinos from LEnuSTORM, will be detected both at LEMMOND and another near detector (END) located at a distance of 250 m. This beam will be used to measure cross-sections as well to study light sterile neutrinos. In this talk, I will present some of our results for this whole setup, showcasing the capability of this powerful ESSnuSBplus setup.

Speaker: Monojit Ghosh (Ruder Boskovic Institute, Zagreb)

S2.3-Monojit.pdf

20 Higgs Alignment in 3HDM: A Practical Parametrization for Phenomenology

Speaker: Ipsita Saha (IIT Madras)

S2.4-Ipsita.pdf

13:30 Lunch Break

Parallel 1: DM + GW

DM + GW

Convener: Kenji Nishiwaki (Shiv Nadar Institute of Eminence)

21 Stochastic GW and Multi-Higgs Productions at the Hadron Colliders via Dimension Six Operator

In an effective field theory approach, we have considered a minimal extension of Standard Model is extended by a non-renormalizable dimension six operator of the form respecting the symmetries of the Standard Model. Such an operator can affect the dynamics of Higgs field and the electroweak phase transition. Presence of such term modifies the triple Higgs coupling. Constraint on the scale parameter Λ is obtained from the di-Higgs data at the LHC Run II. Additionally, such dimension six terms will give rise to additional couplings which will affect tri-Higgs and four-Higgs productions at future high energy, high luminosity hadron colliders. The shape of the scalar potential also gets modified due to such higher dimensional term. It is worthwhile to study the impact of such higher-dimensional operators at suitable gravitational wave (GW) interferometry experiments to probe triple Higgs couplings as a complimentary to traditional collider search methods.

Speaker: Saurabh Niyogi (Harish-Chandra Research Institute)

P1.1-Niyogi.pdf

22 Reconciling Cosmological Tensions with Inelastic Dark Matter and Dark Radiation in a U(1)_D Framework

We propose a novel and comprehensive particle physics framework that addresses multiple cosmological tensions observed in recent measurements of the Hubble parameter, $S_8$, and Lyman-$\alpha$ forest data. Our model, termed `{SIDR+z_t}' (Self Interacting Dark Radiation with transition redshift), is based on an inelastic dark matter (IDM) scenario coupled with dark radiation, governed by a $U(1)_D$ gauge symmetry. This framework naturally incorporates cold dark matter (DM), strongly interacting dark radiation (SIDR), and the interactions between these components. The fluid-like behavior of the dark radiation component which originates from the self-quartic coupling of the $U(1)_D$ breaking scalar can suppress the free-streaming effects. Simultaneously, the interacting DM-DR system can attenuate the matter power spectrum at small scales. The inelastic nature of DM provides a distinct temperature dependence for the DM-DR interaction rate determined by the mass-splitting between the inelastic dark fermions which is crucial for resolving the Ly-$\alpha$ discrepancies. We present a cosmologically consistent analysis of the model by solving the relevant Boltzmann equations to obtain the energy density and number density evolution of different species of the model. The DR undergoes two steps of increased energy density when the heavier dark species freeze out and become non-relativistic, transferring their entropy to the dark radiation and enhancing $\Delta N_{\rm eff}$. The analysis showcases the model's potential to uphold the Big Bang Nucleosynthesis (BBN) prediction of $\Delta N_{\rm eff}$ but dominantly producing additional contributions prior to recombination, while simultaneously achieving correct relic density of DM though an hybrid of freeze-in and non-thermal production.

Speaker: SATYABRATA MAHAPATRA (Sungkyunkwan University)

P1.2-Satyabrata.pdf

23 Anatomy of singlet-doublet dark matter relic: annihilation, co-annihilation, co-scattering, and freeze-in

The singlet-doublet vector-like fermion dark matter model has been extensively studied in the literature over the past decade. An important parameter in this model is the singlet-doublet mixing angle ($\sin\theta$). All the previous studies have primarily focused on annihilation and co-annihilation processes for obtaining the correct dark matter relic density, assuming that the singlet and doublet components decouple at the same epoch. In this work, we demonstrate that this assumption holds only for larger mixing angles with a dependency on the mass of the dark matter. However, it badly fails for the mixing angle $\sin\theta<0.05$. We present a systematic study of the parameter space of the singlet-doublet dark matter relic, incorporating annihilation, co-annihilation, and, for the first time, co-scattering processes. Additionally, the freeze-in parameter space is also explored. We found that due to the inclusion of co-scattering processes, the correct relic density parameter space is shifted towards the detection sensitivity range of the LHC and MATHUSLA via displaced vertex signatures.

Speaker: Mr Partha Kumar Paul (Indian Institute of Technology Hyderabad)

P1.3-Partha.pdf

24 Singlet-doublet dark matter induced radiative neutrino mass and TeV scale leptogenesis

The singlet-doublet dark matter model is one of the most studied WIMP scenarios to realize the relic of DM in a large parameter space. In this work, we study the two-step leptogenesis in the singlet-doublet Majorana dark matter model. We extend the Standard Model (SM) by introducing three Majorana singlet fermions ($N_i$), three doublet fermions ($\Psi_i$), and a singlet scalar ($\Phi$), all of which are odd under an imposed $Z_2$ symmetry, while SM particles remain even.
The $CP$-violating out-of-decay of the heavier singlets ($N_{2,3}$) to the lighter doublets ($\Psi_i$) generates an asymmetry in the doublets. This asymmetry is then transferred to the lepton asymmetry via decays of $\Psi_i$ to leptons. Prior to the electro-weak (EW) symmetry breaking, this lepton asymmetry is converted to the baryon asymmetry by the EW spharelons. We also show that the imposed $Z_2$ symmetry prevents neutrino masses at tree level but allows them to be generated at one loop. Additionally, we analyze the dark matter relic, including the annihilation, co-annihilation, and co-scattering processes. We constrain the parameter space with the present direct, indirect, and collider searches.

Speaker: Mr Shashwat Sharma (Indian Institute of Technology Hyderabad)

P1.6-Shaswat.pdf

25 SIDM with an observable $\Delta N_{\rm eff}$ in a $U(1)_D$ framework

We propose a GeV-scale self-interacting dark matter (SIDM) candidate within a $U(1)_D$ extension of the Standard Model (SM), addressing small-scale structure anomalies in $\Lambda$CDM while predicting an observable contribution to $\Delta N_{\rm eff}$. The model introduces a fermionic DM candidate $\chi$ and a scalar $\phi$, both charged under an unbroken $U(1)_D$ gauge symmetry. The self-interactions of $\chi$ are mediated by a light vector boson $X^\mu$, whose mass is generated via the Stueckelberg mechanism. The relic abundance of $\chi$ is determined by thermal freeze-out through annihilations into $X^\mu$, supplemented by a non-thermal component from the late decay of $\phi$. Crucially, $\phi$ decays after Big Bang Nucleosynthesis (BBN) but before the Cosmic Microwave Background (CMB) epoch, producing additional $\chi$ and a dark radiation species ($\nu_S$). This late-time production compensates for the underabundance from efficient annihilation into light mediators, while remaining consistent with structure formation constraints. The accompanying dark radiation yields a detectable $\Delta N_{\rm eff}$, compatible with Planck 2018 bounds and within reach of next-generation experiments such as SPT-3G, CMB-S4, and CMB-HD.

Speaker: Vicky Singh Thounaojam (Indian Institute of Technology, Hyderabad)

P1.4-Vicky.pdf

26 Gravitational waves through inflaton decay into a pair of Rarita-Schwinger fields

The idea of cosmic inflation stands on the firm ground of observations from Big Bang nucleosynthesis and the cosmic microwave background. However, a missing piece remains—reheating—which connects inflation to the radiation-dominated universe, a crucial stage for the nucleosynthesis process. A key observable of the reheating stage is stochastic gravitational waves, generated by the decay of the inflaton into light degrees of freedom. In this work, we explore gravitational waves generated during the decay of the inflaton into a pair of Rarita-Schwinger fields.

Speaker: Sourav Saini

P1.5-SouravSaini.pdf

Parallel 2: BSM + Collider

BSM + Collider

Convener: Subhaditya Bhattacharya

27 A multi-boson door into compositeness

A multi-boson door into compositeness

Speaker: Abhishek Kumar Singh (Indian Institute Of Technology Delhi)

P2.1-Abhishek.pdf

28 Probes of Anomalous Events at LHC with Self-Organizing Maps

Self-organizing map (SOM), a special class of artificial neural network (ANN),
has found extensive application in many science branches since its discovery in 1982 by
Teuvo Kohonen. Inspired by the ability of the brain to map smells, sounds, images, etc., to
different neurons in a self-organizing way and segregate them concerning their similarity,
SOM is widely used for dimensional reduction, visualization, and clustering of higher
dimensional data. These abilities of SOM have remarkable implementations in the field of
High Energy Physics not only to identify rare decay processes from the usual Standard Model
(SM) ones but also to segregate different SM decays with differences in the decay channel.
This work considers a SM top decay process t → b W and a di-jet QCD process p p → j j in
the boosted regime (pT > 350GeV) and visualizes how these two processes can be mapped in
a two-dimensional grid (SOM grid) using their kinematic features. We map the data points to
a rectangular grid and try to identify the clusters through the SOM visualization and unified
distance matrix(u-matrix). We also tried to interpret the meaning of each boundary in the
SOM map Grid, identifying if SOM could find some anomalous cluster of data from these
datasets. The algorithm shows promising results by clustering almost 90% of SM top decay
dataset in one cluster and 91% of the di-jet QCD process dataset in another cluster.

Speaker: Shreecheta Chowdhury (SRM University-AP)

P2.2-Shreecheta.pdf

29 Hyperchargeless Scalar Triplets and the Price of Minimalism

We study the most minimal scalar extension that offers a tree-level violation of the custodial symmetry, while containing a dark matter (DM) candidate. A hypercharge-less scalar triplet that obtains a small vev breaks the custodial symmetry, which translates to the charged component $T^\pm \to Z W^\pm$ decay. Adding an inert singlet to this extension as a stable DM also opens up the fully invisible decay of the neutral triplet scalar, $T^0 \to SS$. Associated production of these charged and triplet scalars via vector boson fusion at a muon collider is studied, where the invisible decay mode aids the signal discernibility via large missing energy contribution. The parameter space reach in terms of discovery projection is presented at both the 3 TeV and 10 TeV muon colliders, with BDT-enhanced signal extraction for the former.

Speaker: Snehashis Parashar (IIT Hyderabad)

P2.3-Snehashis.pdf

30 Probing exotic Z → b¯bγ decay at HL-LHC with Machine Learning approaches

We investigate the sensitivity of high luminosity LHC for rare Z decay into b¯bγ . As a bench mark we consider a model with axion like particles where Z decays to axion
and photon and axion decays into two bottom quarks, leading to a final state with two
b-tagged jets and an isolated photon. We focus on distinguishing signal events from
background using kinematic features and spatial distributions, including transverse
momentum, angular separation (∆R ), and invariant mass. We compared different ML
models like Boosted Decision Trees (BDT), Convolutional Neural Networks (CNN), and
Graph Neural Networks (GNN), using these three variables for BDT and GNN, and
using images on the η − ϕ plane with pixel intensity as PT for CNN. Our preliminary
results show improved classification accuracy, with the aim of setting new upper boundson ALP production.

Speaker: Tejaswini Thallapalli

P2.4-Tejaswini.pdf

31 Bayesian Model Comparison: The Battle Royale of New Physics Models

Finding high-likelihood regions in BSM scenarios, particularly in high-dimensional models is a computationally expensive task and inefficient task using conventional statistical methods, due to the curse of dimensionality. In this work, we implement a generative framework, Real-valued Non-Volume Preserving(RealNVP) Normalizing Flows as our Machine Learning(ML) framework to assist Nested Sampling in likelihood calculation. This approach reaches convergence to a tolerance of approximately 0.001 within a few days. NS also computes Bayesian evidence. For similar Beyond the Standard Model (BSM) scenarios tested on the same dataset, comparing their evidences allows us to objectively assess which model is more strongly supported by the data. This method can be leveraged to calculate the evidence for different New Physics (NP) models, thereby facilitating model comparison.

Speaker: Rajneil Baruah (Bennett University)

P2.5-Rajneil.pdf

16:30 Tea Break

Parallel 3: DM+ Neutrino

Neutrino

Convener: Dr Moon Moon Devi (Tezpur University, India)

32 Neutrino interaction measurement using emulsion based detector at NINJA experiment

Neutrino oscillation measurements via long-baseline experiments rely on the accurate measurement of neutrino interactions with the nucleus and subsequent reconstruction of the neutrino energy. A signature of charged-current (CC) neutrino interaction in the detector is the lepton in the final state and further event classification of CC events in detectors is done based on the composition of the hadronic part of the final state. Charged-current quasi-elastic (CCQE) event contains one nucleon in the final state and is the dominant interaction mode at low neutrino energies (few hundred MeV range). Another mode of interaction in that energy region is called 2p2h, which has two nucleons and one lepton in the final state. In such events, detection and reconstruction of nucleons is crucial for the accurate measurement of neutrino energy. Low energy nucleons in final state pose challenge during the reconstruction process and are a major contribution towards systematic errors in the neutrino energy reconstruction. NINJA experiment employs nuclear emulsion detectors to measure neutrino-water interactions with low proton momentum threshold (∼ 200 MeV/c). Key features of nuclear emulsion detectors is their high granularity and 3-dimensions tracking capability. These characteristics allow them to reconstruction short tracks coming from neutrino interaction vertex. The NINJA detector is installed in the near detector complex of the T2K neutrino experiment and utilizes the neutrino beam from J-PARC. In this talk, I will report on theNINJA experiment and the current status of emulsion film analysis.

Speaker: Mahesh Jakkapu (Ruder Boskovic Institute, Zagreb)

P3.1-Mahesh.pdf

33 Seesaw Models and Charged Lepton Flavor Violation in Meson Decays: A Comparative Study

The observation of neutrino oscillations implies the existence of flavour violation in the charged lepton sector. The branching ratios of various charged lepton flavour-violating (CLFV) decay modes are influenced by the underlying neutrino mass model. This study investigates the correlations between radiative CLFV decays and meson CLFV decays within the framework of the three simple seesaw mechanisms for neutrino mass generation. We observe that meson CLFV decay branching ratios are negligibly small in the type-II seesaw mechanism. if the branching ratios of meson CLFV decays exceed those of radiative CLFV decays, it serves as compelling evidence that the neutrino mass generation mechanism is more intricate than the simple seesaw framework.

Speaker: Dr Jai More (INDIAN INSTITUTE OF TECHNOLOGY BOMBAY)

P3.2-Jai.pdf

34 Exploring invisible neutrino decay at P2SO experiment

The small mass of neutrinos enables the possibility of rapid neutrino decay in
beyond Standard Model scenarios. If the final state involves an active neutrino,
it is called a visible decay, whereas decay into a lighter sterile state is known
as invisible decay. This study explores the effects of the invisible decay of the
$\nu_3$ state into a sterile neutrino and a Majoron, within the framework of the
P2SO experiment. We analyze both the probability and event rates, taking into
account the decay parameter. Using the P2SO setup, we can exclude $\tau_3 /m_3 < 2.11 \times 10^{−11} s/eV$ at a 3$\sigma$ confidence level, which offers slightly better bound than the MOMENT and ESSnuSB experiments, but is not as strong as the limits
provided by DUNE and T2HK. Furthermore, we evaluate the impact of neutrino
decay on CP violation (CPV) and $\theta_{23}$ octant sensitivities as functions of $\tau_3 /m_3$, observing that decay reduces the CPV sensitivity in the P2SO experiment.

Speaker: Priya Mishra

P3.3-Priya.pdf

35 Impact of the Active-Sterile MSW Resonance on Fast Flavor Conversions in Supernovae

Sterile neutrinos, hypothetical singlet fermions, interact with ordinary matter only through mixing with active neutrinos. In core-collapse supernovae, their production via Mikheyev-Smirnov-Wolfenstein (MSW) resonances of electron neutrinos and antineutrinos can influence explosion dynamics and nucleosynthesis. We probe the effect of these kinds of MSW conversions on the fast flavor conversions (FFC’s) of neutrinos occurring deep inside the SN core. Using a 2+1 framework with two active and one sterile species, we analyze how electron neutrino depletion from MSW conversions modifies electron lepton number (ELN) crossings, a crucial factor for FFCs. We show that MSW resonance (outer resonance) can potentially modify the ELN crossings and thus affect the occurrence of FFC’s significantly. Further, we carry out a qualitative analysis considering the scenario of inner resonance with varying conversion probabilities.

Speaker: TARUN CHANDA (Indian Institute of Technology Guwahati)

P3.4-Tarun.pdf

36 Exploring neutrino oscillations in curved spacetime in long-baseline experiments

In this presentation we discuss the effect of neutrino oscillation in presence of curved spacetime. The influence of curvature on fermionic fields is described by the spin connection, which consists of two components: a universal gravitational term and a non-universal contorsion term. The contraction of contorsion with tetrad fields, which serves as a link between the internal flat space metric and the curved spacetime metric, gives rise to torsion. The presence of torsion induces a nonzero effect on neutrino oscillation appearance and disappearance probabilities, leading to modifications in all aspects of physics sensitivities related to neutrino oscillations. In this study, we explore the role of torsion in future long-baseline neutrino oscillation experiments, specifically DUNE and P2SO, and establish constraints on the torsional couplings within these experimental setups. Our findings illustrate how physics sensitivities like mass hierarchy, CP violation, and octant sensitivity are altered in the presence of nonzero torsional couplings.

Speaker: Papia Panda (University of Hyderabad)

P3.5-Papia.pdf

37 CMB pathway to constraining UV freeze-in dark matter

Prediction of spectral index from the temperature fluctuation of Cosmic Microwave Background (CMB) can play a pivotal role in predicting the reheating dynamics in the early Universe. In this work, we consider α-attractor model of inflation and investigate the reheating phenomena in conjunction with the production of dark matter from the thermal bath via a dimension five operator. The dimensionality of the interaction naturally makes the DM feebly coupled with the SM bath as the interaction is inversely proportional to a cut-off scale Λ and the production strongly depends on the reheating temperature. The dependence of the DM relic on the reheating temperature enables us to put constraints on the DM parameter space from the CMB spectral index.

Speaker: Sujit Kumar Sahoo (Indian Institute of Technology Hyderabad)

P3.6-Sujit.pdf

Parallel 4: BSM + flavour

BSM + Flavour

Convener: Yuji Omura (Kindai University)

38 Sign of the hZZ coupling and implication for new physics

The magnitudes of the couplings of the scalar resonance at 125 GeV with the SM particles are found to be consistent with those of the SM Higgs boson. However, the signs are not experimentally determined in most of the cases, a prime example being that with the $Z$-boson pair. In other words, $\kappa_Z^h$, the ratio of the couplings of the actual 125 GeV resonance with $ZZ$ and that of the SM Higgs boson with the same, is consistent with both $+1$ and $-1$, the latter being the "wrong-sign". We argue that the wrong-sign $hZZ$ coupling will necessitate the intervention of new physics below $\mathcal{O}\left(620\right)$ GeV to safeguard the underlying theory from unitarity violation. The strength of the new nonstandard couplings can be derived from the unitarity sum rules, which are comparable to the SM-Higgs couplings in magnitude. Thus the strong limits from the direct searches at the LHC can help us rule out the existence of such nonstandard particles with unusually large couplings thereby disfavoring the possibility of a wrong-sign $hZZ$ coupling.

Speaker: Agnivo Sarkar

P4.1-Agnivo.pdf

39 Reexamining the CKM Angles of the Standard Model Through Non-Leptonic Neutral B Meson Decays in the Presence of Decoherence

Quantum coherence plays a crucial role in the dynamics of neutral meson systems, aiding in the extraction of various Standard Model parameters. However, real physical systems inevitably interact with their environments, leading to decoherence effects. In the case of neutral B mesons, this decoherence is modeled using a single parameter, $\lambda$. It is important to reassess the Standard Model CKM angles $(\alpha, \beta, \gamma)$ and the mass difference $(\Delta m) $ in the presence of decoherence. In this work, we propose an alternative method to extract these angles by analyzing time-dependent asymmetry in non-leptonic neutral B meson decays. Our findings indicate that the decoherence parameter $\lambda$ influences and potentially obscures the extraction of Standard Model parameters.

Speaker: Dhiren Panda (UNIVERSITY OF HYDERABAD)

P4.2-Dhiren.pdf

40 The Fate of the scalar quartic couplings in the Inert Models

Speaker: Mr Pram Milan P Robin (IIT Hyderabad)

Pram_Milan-Talk-1.pdf

41 Democratic three Higgs-doublet models: the custodial limit and wrong-sign Yukawa

We study two novel aspects of democratic 3HDMs -- the custodial limit and the possibility of wrong-sign Yukawa couplings. In the custodial limit, the democratic 3HDMs can easily negotiate the constraints from the electroweak T-parameter. We also uncover the possibility of having wrong-sign Yukawa couplings in democratic 3HDMs, as in the case of 2HDMs. We show that a democratic 3HDM encompasses all the wrong-sign possibilities entertained by 2HDMs, and has considerably more leeway in the wrong-sign limit as compared to the 2HDM case. Our study underscores the importance of reporting analysis in the kappa-formalism without any implicit assumptions on the signs of the kappas.

Speaker: Anugrah Mathew Prasad (Indian Institute of Technology Indore)

P4.4-Anugrah.pdf

42 Axion misalignment with memory-burdened PBH

We study the possibility of producing axion dark matter (DM) via misalignment mechanisms in a non-standard cosmological era dominated by ultra-light primordial black holes (PBH). While the effect of PBH domination on the production of axion via vacuum misalignment is known assuming the PBH evaporation to proceed according to Hawking’s semi-classical (SC) approximation, we go beyond these simplest possibilities to include kinetic misalignment of axion and backreaction effect of emitted particles on the PBH themselves, referred to as the memory-burden (MB) effect. We show that, depending upon the type of misalignment mechanism and PBH evaporation regime, the axion as well as PBH parameter space consistent with the observed DM relic changes significantly having interesting implications for axion detection experiments. PBH also offer complementary detection prospects via gravitational wave due to PBH density fluctuations and excess radiation
due to emission of hot axions within reach of future cosmic microwave background experiments.

Speaker: Disha Bandyopadhyay (Indian Institute of Technology Guwahati)

P4.5-Disha.pdf

43 The clockwork paradigm and multi-axion scenarios

Speaker: Suvam Maharana (Tata Institute of Fundamental Research)

P4.6-Suvam.pdf

19:30 Conference Dinner

Friday 11 July

Plenary: Day 3, Session 1

Convener: Sourov Roy (Indian Association for the Cultivation of Science, Kolkata)

44 Anomalies in Hadronic B Meson Decays

Large SU(3) breaking has been observed in some hadronic B decays. This observation may eventually pave the way for challenging Standard Model inspired hypotheses in these decay modes. I will provide an update on these hadronic anomalies. I will include additional decay channels that may also shed light on this new puzzle.

Speaker: Prof. Bhubanjyoti Bhattacharya (Lawrence Technological University)

Anomalies in Hadronic B Decays

45 Deciphering the nature of New Physics from Flavor sector

Speaker: Dr. Rukmani Mohanta

P1.2-Rukmani.pdf

46 Preheating and Baryogenesis in Higgs-Starobinsky Inflation

In this talk, I will discuss the impact of preheating on baryogenesis in Higgs-Starobinsky inflation. I will show that if the Ricci scalar couples with the U(1) hypercharge density, it can explain the observed matter-antimatter asymmetry of the Universe.

Speaker: Tanmoy Modak

P1.3-TModak.pdf

47 Non-decoupling Heavy Higgs Bosons as a Probe of Spontaneous CP-Violation

CP-violation is essential for understanding the matter-antimatter asymmetry in the Universe and serves as a key component of physics beyond the Standard Model (SM). Extensions in the Higgs sector permit CP violations beyond the CKM phase. However, the origin of CP-violation remains unknown, as both spontaneous and explicit violations are feasible. In this talk, I present the phenomenological implications of Spontaneous CP-violation (SCPV) in the Two-Higgs Doublet Model (2HDM). There are two significant aspects in the SCPV 2HDM, i.e., non-decoupling nature of heavy Higgs bosons and flavor-violating structure of the additional Yukawa couplings. I will show that the non-decoupling nature leads to a considerable deviation and correlation in the self-coupling for the 125 GeV Higgs and its di-photon decay. I also discuss flavour-changing decays of the heavy Higgs bosons.

Speaker: Dr Tanmoy Mondal (Birla Institute of Technology & Science (BITS Pilani))

Phoenix_Tanmoy.pdf

11:00 Tea Break

Plenary: Day 3, Session 2

Convener: Prof. Asesh K. Datta (Harish-Chandra Research Institute)

48 Unveiling New Physics with Long-Lived Particles at the LHC and Beyond

Speaker: Biplob Bhattacharjee

P2.1-Biplob.pdf

49 Status and Prospects of the Minimal Universal Extra-Dimension Model and Its Extensions

Speaker: kirtiman ghosh

P2.2-Kirtiman.pdf

50 New Physics search prospects at the future colliders

New Physics, if weakly coupled to the Standard Model, is often easier to search at the electron-positron machines, than at the LHC. In this talk, I will discuss a few examples concerning dark matter, Higgs effective operators, lepton number and flavor violating interactions.

Speaker: Subhaditya Bhattacharya

P2.3-Subhaditya.pdf

13:00 Lunch Break

Plenary: Day 3, Session 3

Convener: Swagata Mukherjee

51 Collider signals for an SM-phobic gauge boson

Speaker: Santosh Kumar Rai

P3.1-Santosh.pdf

52 ML tagged boosted dark photon and portal matter phenomenology

Speaker: Sanjoy BiswasBiswas

P3.2-Sanjoy.pdf

53 Muon g − 2 and W-mass in a framework of colored scalars: an LHC perspective

A color octet isodoublet can have esoteric origins and it complies with minimal flavour violation. In this study, we take a scenario where the well known Type-X Two-Higgs doublet model is augmented with a color octet isodoublet. We shed light on how such a setup can predict the recently observed value for the W-boson mass. The two-loop Barr-Zee contributions to muon g-2 stemming from the colored scalars are evaluated. It is subsequently found that the parameter space compatible with the observed muon g-2 gets relaxed w.r.t. what it is in the pure Type-X 2HDM by virtue of the contribution from the colored scalars. The extended parameter region therefore successfully accounts for both the W-mass and muon g-2 anomalies simultaneously. Finally, a collider signature leading to a relevant final state is explored at the 14 TeV LHC using both cut-based and multivariate techniques. Such a signal can confirm the existence of both colorless as well colored scalars that are introduced by this framework.

Speaker: Indrani Chakraborty (University of Calcutta)

P3.3-Indrani.pdf

16:00 Tea Break

Plenary: Day 3, Session 4

Convener: Divya Sachdeva

54 Fermi-ball in a multicomponent dark matter framework and its gravitational wave signatures

It has been known that underabundant dark matter density of an inert doublet
can be replenished by an additional dark matter component, say, a fermion. We find that such a scenario can lead to the formation of stable Fermi-balls through
coexisting minima of the finite temperature scalar potential. More importantly, we demonstrate that the Fermi-balls contribute sizeably to the dark matter relic density.
In addition, the aforesaid coexisting minima open up the possibility of a first-order phase transition. This, in turn, triggers emission of gravitational waves that can be tested at the proposed BBO and U-DECIGO detectors. Therefore, the present study becomes a concrete setup to embed Fermi-balls in a realistic two-component dark matter model, and, to test the same using gravitational wave signatures.

Speaker: Nabarun Chakrabarty (H)

55 Isospin Violating Dark Sector: Direct Detection Prospects

"Dark matter direct detection is now standing at an interesting juncture, where the SM neutrino background and the upper bound on dark matter signal cross section are starting to overlap in a region of DM mass $\sim 10$~GeV.
The neutrino floor, which defines the extent of the neutrino background, can get modified in different BSM set up. We work in a BSM set up that is a very natural dark sector extension of the SM visible sector where isospin violation is already established. In this isopsin violating dark sector, both the dark matter and neutrino interaction have isospin violating interactions, through a newly added U(1) gauge boson ($Z^{\prime}$). In a parts of the parameter space we see the neutrino nucleus scattering (CE$\nu$NS) cross section goes down, while it goes up in some parameter space. Amount of isospin violation plays a crucial role in determining the allowed parameter space as we take into account the re-scaling of the DM experimental upper bound due to the isospin violation. We discuss different scenarios related to dark matter detection prospects. "

Speaker: Soumya Sadhukhan (Ramakrishna Mission Residential College (Autonomous), Narendrapur)

P4.2-Soumya.pdf

56 Singlet Scalar Dark Matter Model Featuring Dual High-Scale Minima

We analyze various dark matter models featuring additional scalars and fermions. The scalar quartic and Yukawa couplings play key roles in achieving the correct relic density via Freeze-out and Freeze-in mechanisms. In addition to the SM-like high-scale minimum along the Higgs direction, new minima can arise along the extended scalar direction, depending on the dark matter parameter space. We explore the full parameter space to identify regions of interest.

Speaker: Dr Najimuddin Khan (Harish-Chandra Research Institute (HRI))

P4.3-Najimuddin.pdf

Closing Session

Convener: Dr Priyotosh Bandyopadhyay (Indian Institute of Technology Hyderabad)

57 Closing Session

Speaker: Dr Priyotosh Bandyopadhyay (Indian Institute of Technology Hyderabad)

19:30 Dinner