Enhancing sensitivity to leptonic CP violation using complementarity among DUNE, T2HK, and T2HKK

Sanjib Kumar Agarwalla; Sudipta Das; Alessio Giarnetti; Davide Meloni; Masoom Singh

doi:10.1140/epjc/s10052-023-11863-7

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2023) 83: 694
https://doi.org/10.1140/epjc/s10052-023-11863-7

Regular Article - Theoretical Physics

Enhancing sensitivity to leptonic CP violation using complementarity among DUNE, T2HK, and T2HKK

Sanjib Kumar Agarwalla¹^,2^,3^,4^a, Sudipta Das¹^,2, Alessio Giarnetti⁵, Davide Meloni⁵ and Masoom Singh¹^,6

¹ Institute of Physics, Sachivalaya Marg, Sainik School Post, 751005, Bhubaneswar, India
² Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, 400094, Mumbai, India
³ International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy
⁴ Department of Physics and Wisconsin IceCube Particle Astrophysics Center, University of Wisconsin, 53706, Madison, WI, USA
⁵ Dipartimento di Matematica e Fisica, Università di Roma Tre, Via della Vasca Navale 84, 00146, Rome, Italy
⁶ Department of Physics, Utkal University, Vani Vihar, 751004, Bhubaneswar, India

^a sanjib@iopb.res.in

Received: 23 April 2023
Accepted: 25 July 2023
Published online: 5 August 2023

Abstract

After the landmark discovery of non-zero $θ_{13}$ $\theta _{13}$ by the modern reactor experiments, unprecedented precision on neutrino mass-mixing parameters has been achieved over the past decade. This has set the stage for the discovery of leptonic CP violation (LCPV) at high confidence level in the next-generation long-baseline neutrino oscillation experiments. In this work, we explore in detail the possible complementarity among the on-axis DUNE and off-axis T2HK experiments to enhance the sensitivity to LCPV suppressing the $θ_{23} - δ_{CP}$ $\theta _{23}-\delta _{\textrm{CP}}$ degeneracy. We find that none of these experiments individually can achieve the milestone of 3 $σ$ $\sigma$ LCPV for at least 75% choices of $δ_{CP}$ $\delta _{\textrm{CP}}$ in its entire range of $[- 180^{\circ}, 180^{\circ}]$ $[-180^{\circ }, 180^{\circ }]$ , with their nominal exposures and systematic uncertainties. However, their combination can attain the same for all values of $θ_{23}$ $\theta _{23}$ with only half of their nominal exposures. We observe that the proposed T2HKK setup in combination with DUNE can further increase the CP coverage to more than 80% with only half of their nominal exposures. We study in detail how the coverage in $δ_{CP}$ $\delta _{\textrm{CP}}$ for $\geq$ $\ge$ 3 $σ$ $\sigma$ LCPV depends on the choice of $θ_{23}$ $\theta _{23}$ , exposure, optimal runtime in neutrino and antineutrino modes, and systematic uncertainties in these experiments in isolation and combination. We find that with an improved systematic uncertainty of 2.7% in appearance mode, the standalone T2HK setup can provide a CP coverage of around 75% for all values of $θ_{23}$ $\theta _{23}$ . We also discuss the pivotal role of intrinsic, extrinsic, and total CP asymmetries in the appearance channel and extrinsic CP asymmetries in the disappearance channel while analyzing our results.

© The Author(s) 2023

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