arXiv subjects

Swagatam Tah

Publications and source records attributed to Swagatam Tah.

3 recordsLinked to original sources

arXiv2026

Probing QCD instantons using jet correlation observables in proton-proton collisions at the LHC

Discovery of instantons in colliders will provide experimental evidence for the topological properties of the QCD vacuum. In this work, we propose jet correlation observables that can unambiguously discriminate between instanton-induced processes and perturbative hard scattering events in $pp$ collisions at the LHC for a specific range of center-of-mass energies of the produced hadrons. By calculating the instanton sizes and their separations in 2+1 flavor QCD with physical quark masses, we provide a qualitative understanding of why the semiclassical methods reliably predict the cross-section of instanton-induced processes at the particular center-of-mass energies we are focusing on. Our proposal is directly applicable to future $ep$ measurements at the Electron-Ion Collider, offering a cleaner environment to probe instanton-induced processes.

hep-ph↗

arXiv2026

Lattice study of spin interactions between heavy quarks in the quark-gluon plasma

We calculate the spin-dependent potential, which is the $\mathcal{O}(1/M^2)$ correction term to the thermal potential between a static quark-antiquark pair within non-relativistic QCD. At leading order in hard thermal loop perturbation theory, we show that this spin-dependent potential has an imaginary part which is different in magnitude for pseudoscalar and vector quarkonium states. For the first time, we extract the imaginary part non-perturbatively using lattice techniques, in the deconfined phase of quenched QCD at $T\sim 470$ MeV, after performing a continuum estimation and subsequent renormalization. We have found that the spin-dependent potential in the quark-gluon plasma phase is complex, and its imaginary part has a remarkably significant contribution over the thermal static potential for charmonium states. Consequences of this thermal spin-dependent potential on the quarkonium spectral functions are also discussed.

hep-lat↗

arXiv2025

The spatial string tension and its effects on screening correlators in a thermal QCD plasma

We calculate the spatial Wilson line correlator for 2+1 flavor QCD using highly improved staggered quark discretization for fermions and in quenched QCD for a wide range of temperatures, from the chiral crossover temperature $\mathrm{T_{pc}\simeq 156}$ MeV or the deconfinement temperature $\simeq 300$ MeV respectively, up to $2$ GeV. Extracting the spatial string tension for different lattice cut-offs and by performing a continuum extrapolation of this observable, we show that the soft (magnetic) gluons interact non-perturbatively even at temperatures $\gtrsim 1$ GeV. We provide incriminating evidences to demonstrate that dimensionally reduced effective theories can describe these soft quark and gluon quasi-particles for both quenched and $2+1$ flavor QCD, at temperatures $\mathrm{T\gtrsim 5T_{pc}}$. We also show for the first time the imprints of the non-perturbative pseudo-potential in the properties of mesonic screening masses for temperatures ranging from $0.8$-$164$ GeV in the quark-gluon plasma.

hep-lat↗