The Meeting

Shivalik HEPCATS meetings are intended to foster discussions and collaborations among researchers in and around the Shivalik range of the Himalayas. The meetings will take place, ideally once every six months, at various institutes located in the region.

This is the 3rd edition of this meeting series.

The webpages of the previous editions of the meetings are available here: Winter 2019 and Summer 2020.

What is HEPCATS?

HEPCATS stands for High Energy Physics, Cosmology, Astrophysics, Theory and Simulations.


The venue of Winter 2020 Meeting is virtual (over Zoom) and it is hosted by IISER Mohali. The meeting begins at 9:50AM on January 30, 2021 (Saturday) ends at 5:10PM the same day.


There is no registration for the meeting. Please join the meeting over Zoom using the invitation link and password.


The organizers of the meeting are:
Dr. Jasjeet Bagla,
Dr. Harvinder Kaur Jassal,
Dr. Anosh Joseph,
Dr. Kinjalk Lochan,
Dr. Ambresh Shivaji, and
Dr. K P Yogendran.

Local Coordinators

The local coordinators of the meeting are:

Dr. Jasjeet Bagla, Dr. Minati Biswal, Mr. Navdeep Singh Dhindsa, Dr. Harvinder Kaur Jassal, Dr. Anosh Joseph, Ms. Mandeep Kaur, Mr. Arpith Kumar, Dr. Kinjalk Lochan, Ms. Vamika Longia, Mr. Harkirat S Sahota, Dr. Ambresh Shivaji, and Dr. K P Yogendran.


We acknowledge funding from the Department of Physical Sciences, IISER Mohali.


For those of you who are on IISER Mohali campus tea/coffee/lunch will be provided in AB1 Conference Room. Kindly maintain the protocols of social distancing while you enter the conference room.


Time Speaker Affiliation Title Resources
10:00AM - 10:10AM Charanjit Singh Aulakh (IISER Mohali) Welcome Remarks -- --
Session 1 Chair: Kinjalk Lochan (IISER Mohali)
10:10AM - 10:30AM Navdeep Singh Dhindsa IISER Mohali Field Theory Matrix Models on Lattice: A Proem Slides
10:35AM - 10:55AM Rahul Sharma IISER Mohali The AstroSat observation of accreting millisecond pulsar SAX J1808.4-3658 Slides
11:00AM - 11:02AM Martyrs' Day -- Observance of Silence --
11:05AM - 11:25AM Hironori Hoshino IIT Ropar Proper Effective Temperature of Nonequilibrium Steady State Slides
11:30AM - 11:50AM Coffe/Tea Break
Session 2 Chair: Shankhadeep Chakrabortty (IIT Ropar)
11:50AM - 12:10PM Gopal Yadav IIT Roorkee Towards ChPT Lagrangian from M Theory Slides
12:15PM - 12:35PM Pramod Sharma IISER Mohali Probing Anomalous HZZ Coupling at Electron-Proton Collider Slides
12:40PM - 01:00PM Ayan Chatterjee Central University of Himachal Pradesh Supertranslations for a Dynamical Horizon Slides
01:05PM - 02:30PM Lunch Break
Session 3 Chair: Ambresh Shivaji (IISER Mohali)
02:30PM - 02:50PM NItin Joshi IIT Ropar Some Measures for Fermionic Entanglement in the Cosmological
de Sitter Spacetime
02:55PM - 03:15PM Mandeep Kaur IISER Mohali QCD Correction to H -> 4l Decay Slides
03:20PM - 03:40PM Ashish Meena IISER Mohali Gravitational Lensing of Gravitational Waves: Effect of Microlens Population Slides
03:40PM - 04:00PM Coffe/Tea Break
Session 4 Chair: Vishal Bharwaj (IISER Mohali)
04:00PM - 04:20PM Md Sabir Ali IIT Ropar Fermionic Vacuum Polarization by a Global Monopole in de Sitter Spacetime Slides
04:25PM - 04:45PM Jagbir Singh Panjab University Searching Event-by-Event CME in Heavy-Ion Collisions Slides
04:50PM - 05:10PM Minati Biswal IISER Mohali Z_3 Metastable States in PNJL Model Slides
05:15PM - 05:25PM Arpith Kumar IISER Mohali Non-lattice Complex Langevin Simulations of Supersymmetric Quantum Field Theories Slides
05:25PM - 05:30PM Harvinder Kaur Jassal (IISER Mohali) Closing Remarks --
05:30PM - 05:45PM Coffe/Tea Break


No Name Affiliation
1. Md Sabir Ali IIT Ropar
2. Charanjit Singh Aulakh IISER Mohali
3. Jasjeet Singh Bagla IISER Mohali
4. Aru Beri IISER Mohali
5. Minati Biswal IISER Mohali
6. Shankhadeep Chakrabortty IIT Ropar
7. Ayan Chatterjee Central University of Himachal Pradesh
8. Gaurav Dadwal IISER Mohali
9. Navdeep Singh Dhindsa IISER Mohali
10. Nishat Fiza IISER Mohali
11. Swati Gavas IISER Mohali
12. Bandhan Goyal Thapar Institute of Engineering And Technology, Patiala
13. Mamta Gulati Thapar Institute of Engineering And Technology, Patiala
14. Hironori Hoshino IIT Ropar
15. Harvinder Kaur Jassal IISER Mohali
16. Anosh Joseph IISER Mohali
17. Kartik Joshi IISER Mohali
18. NItin Joshi IIT Ropar
19. Roshan Kaundinya IISER Mohali
20. Mandeep Kaur IISER Mohali
21. Arpith Kumar IISER Mohali
22. Lokesh Kumar Panjab University
23. Devang Haresh Liya IISER Mohali
24. Kinjalk Lochan IISER Mohali
25. Vamika Longia IISER Mohali
26. Maguni Mahakhud IISER Mohali
27. Ashish Meena IISER Mohali
28. Aalok Misra IIT Roorkee
29. Vasudev Mittal IISER Mohali
30. Sourav Patra IISER Mohali
31. Arpan Akash Ray IISER Mohali
32. Harkirat Singh Sahota IISER Mohali
33. Bana Singh Sangtan IISER Mohali
34. Akash Singh IISER Mohali
35. Jagbir Singh Panjab University
36. Rahul Sharma IISER Mohali
37. Pramod Sharma IISER Mohali
38. Ambresh Shivaji IISER Mohali
39. Kunal Verma IISER Mohali
40. Gopal Yadav IIT Roorkee
41. K. P. Yogendran IISER Mohali

Abstracts of Talks

Time/Speaker Title/Abstract
10:10AM - 10:30AM

Navdeep Singh Dhindsa (IISER Mohali)
Title: Field Theory Matrix Models on Lattice: A Proem

Abstract: In this talk I will introduce field theory matrix models in lower dimensions with lattice framework. I will briefly touch that why these models are important. The talk will be based on IKKT, BFSS, BMN and 2d SUSY YM models. The talk will include the preliminary results of our work on these models.
10:35AM - 10:55AM

Rahul Sharma (IISER Mohali)
Title: The AstroSat Observation of Accreting Millisecond Pulsar SAX J1808.4-3658

Abstract: Accretion-powered millisecond X-ray Pulsars (AMXPs) are rapidly rotating neutron stars. These systems are transient in nature and are observed during the outburst. SAX J1808.4-3658 is one such AMXP and its latest outburst was observed in 2019.The AstroSat observed it for 125 ks. In this talk, I will present spectral and timing results from the data of SXT and LAXPC on-board AstroSat. We found the coherent pulsations at ν= 400.97521011 Hz and the orbital solutions consistent with previous studies. The pulse profile can be well fitted with two harmonically related sinusoidal components with fractional amplitude (background corrected) of 3.26(9) and 1.3(1) percent for fundamental and first harmonic, respectively. We also studied the variation of background-corrected fractional amplitude and phases with the energy. The broad-band spectrum of SAX J1808.4-3658 can be well described with thermal emission from accretion disc or neutron star and the thermal Comptonization from the hot corona.
11:05AM - 11:25AM

Hironori Hoshino (IIT Ropar)
Title: Proper Effective Temperature of Nonequilibrium Steady State

Abstract: A conventional effective temperature of nonequilibrium steady states (NESSs) is frame-dependent in relativistic systems. In this work, we define the proper effective temperature as a frame-independent (Lorentz-invariant) quantity that characterizes NESSs. We find that the proper effective temperature of NESSs is higher than the proper temperature of the heat bath in holographic models even when the conventional effective temperature is lower than the heat bath temperature.
11:50AM - 12:10PM

Gopal Yadav (IIT Roorkee)
Title: Towards ChPT Lagrangian from M Theory

Abstract: Obtaining the values of the coupling constants of the low energy effective theory corresponding to QCD, compatible with experimental data, even in the (vector) mesonic sector from (the M- theory uplift of) a UV-complete string theory dual, has thus far been missing in the literature. In this talk, I will explain how to obtain the values of the coupling constants of the O(p^4) chi-PT Lagrangian in the chiral limit involving the NGBs and rho meson (and its flavor partners) from the M-theory /type IIA dual of large-N thermal QCD-like theories, inclusive of the O(R^4) corrections and match our holographic computation results with phenomenological/experimental values of one loop renormalised low energy constants (LECs) of SU(3) chi-PT up to O(p^4) in the chiral limit.
12:15PM - 12:35PM

Pramod Sharma (IISER Mohali)
Title: Probing Anomalous HZZ Coupling at Electron-Proton Collider

Abstract: SM accurately predicts properties of elementary particles produced in high energy collision experiments. But it is not the ultimate theory as it leaves many questions like origin of neutrino mass, observed matter-antimatter asymmetry in the universe, nature of dark matter and dark energy etc. There is a need to look for deviations in the SM predictions due to the physics beyond the standard model. We use Effective Field Theory (EFT) approach, a model independent framework, to parametrize deviations from the SM. We study the effect of dimension-six operators which lead to modification in the HZZ coupling. Here we investigate sensitivity of HZZ coupling in e- p -> e- H j process at future Large Hadron electron collider. Due to momentum dependent Lorentz structures of new couplings we expect sensitivity to new physics observable like azimuthal angle distribution of final state particles. We are working to estimate constraints on parameters of new couplings by exploiting sensitivity of these observables.
12:40PM - 01:00PM

Ayan Chatterjee (Central University of Himachal Pradesh)
Title: Supertranslations for a Dynamical Horizon

Abstract: We shall discuss methods to induce supertranslations on a dynamical horizon along with examples.
02:30PM - 02:50PM

NItin Joshi (IIT Ropar)
Title: Some Measures for Fermionic Entanglement in the Cosmological de Sitter Spacetime

Abstract: We investigate two measures of quantum correlations and entanglement, namely the violation of the Bell-Mermin-Klyshko (BMK) inequalities and the quantum discord, for Dirac fermions in the cosmological de Sitter background of dimension four. The BMK violation is focused on the vacuum for two- and four-mode squeezed states and the maximum violation is demonstrated. For the quantum discord, we investigate a maximally entangled in-vacuum state. Qualitative similarities as well as differences of our results with that of different coordinations of de Sitter in the context of scalar and fermionic field theory are discussed.
02:55PM - 03:15PM

Mandeep Kaur (IISER Mohali)
Title: QCD Correction to H -> 4l Decay

Abstract: The Higgs Data provides an opportunity to look for signals of Physics Beyond the Standard Model. In this regard, the Higgs decay to four leptons, due to its nontrivial final state kinematics, is one of the most important channels to study. We aim to provide an improved prediction for this decay process by considering higher-order quantum corrections. In particular, we consider QCD corrections on top of EW corrections. The QCD corrections in this case receive contributions from two-loop Feynman diagrams. The amplitude calculation of loop diagrams is highly non-trivial.

In my talk, I will describe the steps involved in the calculation of QCD correction to H -> 4l decay. I will discuss our approach to compute two-loop amplitudes and present some results for the amplitude calculation.
03:20PM - 03:40PM

Ashish Meena (IISER Mohali)
Title: Gravitational Lensing of Gravitational Waves: Effect of Microlens Population

Abstract: In our work, we investigate the effects of microlens population in strongly lensed gravitational wave signals. We consider a wide range of strong lens magnification and the corresponding density values of the microlens population. We find that, in general, the presence of microlens population introduces amplification (de-amplification) in minima (saddle) type of images as we go from low to high gravitational wave frequencies in the LIGO frequency range. Apart from that, the effects of microlensing become increasingly significant with the increase in the strong lens magnification for both minima and saddle type of images. Hence, for notable microlensing features in the gravitational wave signals, the strong lensing magnification also needs to be substantial. It is also evident from the mismatch calculation. The mismatch between lensed and unlensed waveform remains less than 1% unless the strong lensing magnification is very high.
04:00PM - 04:20PM

Md Sabir Ali (IIT Ropar)
Title: Fermionic Vacuum Polarization by a Global Monopole in de Sitter Spacetime

Abstract: We investigate the fermionic condensate and the vacuum expectation value of the energy-momentum tensor for a massive spinor field in the geometry of a global monopole on the background of de Sitter spacetime. By using the Abel-Plana summation formula, we explicitly extract from the expectation values the contribution associated with purely de Sitter space, remaining the expectation values induced by the global monopole. The latter presents information about de Sitter gravity as well. Because the investigation of the fermionic quantum fluctuations in de Sitter space have been investigated in literature, here we are mainly interested in the global monopole-induced contributions. At large distances from the monopole source the behavior of the monopole-induced parts in the vacuum densities is damping oscillatory with the amplitude decaying as the inverse fourth power of the distance. This is in contrast to the case of flat spacetime, in which the monopole-induced vacuum densities for a massive field decay exponentially with distance from the monopole source.
04:25PM - 04:45PM

Jagbir Singh (Panjab University)
Title: Searching Event-by-Event CME in Heavy-Ion Collisions.

Abstract: The electric field induced by strong magnetic field created by the highly energetic moving spectators, causes the separation of charged particles along the systems angular momentum direction known as Chiral Magnetic Effect (CME). A new technique, the Sliding Dumbbell Method (SDM), is developed to search for back-to-back charge separation on event-by-event basis. The CME like signal is externally injected in AMPT generated events by flipping the charges (one/two) of particles perpendicular to the reaction plane in each event. Here, whole azimuthal plane is scanned by sliding the dumbbell of 90-degrees in steps of 1-degree, searching for the maximum of the sum, Db_(+/-)^(max), of the positive charge fraction on one side and the negative charge fraction on the other side of the dumbbell. The fractional dumbbell charge separation, f_(DbCS), is sliced into 10 percentile bins for each centrality to get sample of events enriched with CME like signal. Three-particle correlation will be presented for AMPT in each collision centrality along with those of the charge reshuffled background. The gamma-correlator dependence on fractional dumbbell charge separation will also be discussed.
04:50PM - 05:10PM

Minati Biswal (IISER Mohali)
Title: Z_3 Metastable States in PNJL Model

Abstract: We study the Z_3 metastable states in the Polyakov loop Nambu-Jona-Lasinio model. These states exist for temperatures above T_m ~194 MeV and can decay via bubble nucleation. We numerically solve the bounce equation to compute the nucleation rate. We speculate that, in the context of heavy-ion collisions, the likely scenario for the decay of the metastable states is via spinodal decomposition.
05:15PM - 05:25PM

Arpith Kumar (IISER Mohali)
Title: Non-lattice Complex Langevin Simulations of Supersymmetric Quantum Field Theories

Abstract: The non-perturbative study of supersymmetric theories using lattice simulations is prominent, albeit not straightforward. Lattice formalism requires eliminating SUSY breaking counterterms in order to suppress lattice artefacts. In this talk, we will briefly discuss non-lattice formalism, an extremely simple and elegant method to simulate one-dimensional supersymmetric theories. We present some preliminary non-lattice simulation results using the complex Langevin method for one-dimensional bosonic and non-gauge supersymmetric quantum mechanical models. We also compare these results with previous studies using lattice formalism.