Institute of Physics, Bhubaneswar

About: Institute of Physics, Bhubaneswar is a facility organization based out in Bhubaneswar, Orissa, India. It is known for research contribution in the topics: Large Hadron Collider & Hadron. The organization has 566 authors who have published 1768 publications receiving 64889 citations.

Photoinduced entanglement in a magnonic Floquet topological insulator

Abstract: When irradiated via high-frequency circularly polarized light, the stroboscopic dynamics in a Heisenberg spin system on a honeycomb lattice develops a next-nearest-neighbor (NNN) Dzyaloshinskii-Moriya (DM) type term, making it a magnonic Floquet topological insulator. We investigate the entanglement generation and its evolution on such systems, particularly an irradiated ferromagnetic XXZ spin-$\frac{1}{2}$ model in a honeycomb lattice as the system parameters are optically tuned. In the high-frequency limit, we compute the lowest quasienergy state entanglement in terms of the concurrence between nearest-neighbor (NN) and NNN pair of spins and witness the entanglement transitions occurring there. For the easy-axis scenario, the unirradiated system forms a product state but entanglement grows between the NNN spin pairs beyond some cutoff DM strength. Contrarily in the easy-planar case, NN and NNN spins remain already entangled in the unirradiated limit. It then goes through an entanglement transition which causes decrease (increase) of the NN (NNN) concurrences down to zero (up to some higher value) at some critical finite DM interaction strength. For a high frequency of irradiation and a suitably chosen anisotropy parameter, we can vary the field strength to witness sudden death and revival of entanglement in the Floquet system. Both exact diagonalization and modified Lanczos techniques are used to obtain the results up to 24 site lattice. We also calculate the thermal entanglement and obtain estimates for the threshold temperatures below which nonzero concurrence can be expected in the system.

Boundaries and Unphysical Fixed Points in Dynamical Quantum Phase Transitions

Abstract: We show that dynamic quantum phase transitions (DQPT) in many situations involve renormalization group (RG) fixed points that are unphysical in the context of thermal phase transitions. In such cases, boundary conditions are shown to become relevant to the extent of even completely suppressing the bulk transitions. We establish these by performing an exact RG analysis of the quantum Ising model on scale-invariant lattices of different dimensions, and by analyzing the zeros of the Loschmidt amplitude. Further corroboration of boundaries affecting the bulk transition comes from the three-state quantum Potts chain, for which we also show that the DQPT corresponds to a pair of period-2 fixed points.

Exploring flavor-dependent long-range forces in long-baseline neutrino oscillation experiments

Abstract: The Standard Model gauge group can be extended with minimal matter content by introducing anomaly free U(1) symmetry, such as L e − L μ or L e − L τ . If the neutral gauge boson corresponding to this abelian symmetry is ultra-light, then it will give rise to flavor-dependent long-range leptonic force, which can have significant impact on neutrino oscillations. For an instance, the electrons inside the Sun can generate a flavor-dependent long-range potential at the Earth surface, which can suppress the ν μ → ν e appearance probability in terrestrial experiments. The sign of this potential is opposite for anti-neutrinos, and affects the oscillations of (anti-)neutrinos in different fashion. This feature invokes fake CP-asymmetry like the SM matter effect and can severely affect the leptonic CP-violation searches in long-baseline experiments. In this paper, we study in detail the possible impacts of these long-range flavor-diagonal neutral current interactions due to L e − L μ symmetry, when (anti-)neutrinos travel from Fermilab to Homestake (1300 km) and CERN to Pyhasalmi (2290 km) in the context of future high-precision superbeam facilities, DUNE and LBNO respectively. If there is no signal of long-range force, DUNE (LBNO) can place stringent constraint on the effective gauge coupling α eμ < 1.9 × 10−53 (7.8 × 10−54) at 90% C.L., which is almost 30 (70) times better than the existing bound from the Super-Kamiokande experiment. We also observe that if α eμ ≥ 2 × 10−52, the CP-violation discovery reach of these future facilities vanishes completely. The mass hierarchy measurement remains robust in DUNE (LBNO) if α eμ < 5 × 10−52 (10−52).

Conformal Structure of Massless Scalar Amplitudes Beyond Tree level

Abstract: We show that the one-loop on-shell four-point scattering amplitude of massless $\phi^4$ scalar field theory in 4D Minkowski space time, when Mellin transformed to the Celestial sphere at infinity, transforms covariantly under the global conformal group ($SL(2,C)$) on the sphere. The unitarity of the four-point scalar amplitudes is recast into this Mellin basis. We show that the same conformal structure also appears for the two-loop Mellin amplitude. Finally we comment on some universal structure for all loop four-point Mellin amplitudes specific to this theory.

A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (ν) and μ-DAR (ν¯)

Abstract: Neutrino mass hierarchy, CP-violation, and octant of θ23 are the fundamental unknowns in neutrino oscillations. In order to address all these three unknowns, we study the physics reach of a setup, ...