Can Lorentz invariance violation affect the sensitivity of deep underground neutrino experiment?

Sanjib Kumar Agarwalla; Mehedi Masud

doi:10.1140/epjc/s10052-020-8303-1

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2020) 80: 716
https://doi.org/10.1140/epjc/s10052-020-8303-1

Regular Article - Theoretical Physics

Can Lorentz invariance violation affect the sensitivity of deep underground neutrino experiment?

Sanjib Kumar Agarwalla¹^,2^,3^* and Mehedi Masud¹^,4

¹ Institute of Physics, Sachivalaya Marg, Sainik School Post, Bhubaneswar, 751005, India
² Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai, 400085, India
³ International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste, Italy
⁴ Astroparticle and High Energy Physics Group, Instituto de Física Corpuscular (CSIC/Universitat de València), Parc Cientific de Paterna. C/Catedratico José Beltrán, 2, 46980, Paterna, València, Spain

^* e-mail: sanjib@iopb.res.in

Received: 15 February 2020
Accepted: 30 July 2020
Published online: 9 August 2020

Abstract

We examine the impact of Lorentz Invariance Violation (LIV) in measuring the octant of $\theta _{23}$ and CP phases in the context of the Deep Underground Neutrino Experiment (DUNE). We consider the CPT-violating LIV parameters involving $e - \mu$ ( $a_{e\mu }$ ) and $e - \tau$ ( $a_{e\tau }$ ) flavors, which induce an additional interference term in neutrino and antineutrino appearance probabilities. This new interference term depends on both the standard CP phase $\delta$ and the new dynamical CP phase $\varphi _{e\mu }$ / $\varphi _{e\tau }$ , giving rise to new degeneracies among ( $\theta _{23}$ , $\delta$ , $\varphi$ ). Taking one LIV parameter at-a-time and considering a small value of $|a_{e\mu }| = |a_{e\tau }| = 5 \times 10^{-24}$ GeV, we find that the octant discovery potential of DUNE gets substantially deteriorated for unfavorable combinations of $\delta$ and $\varphi _{e\mu }$ / $\varphi _{e\tau }$ . The octant of $\theta _{23}$ can only be resolved at $3\sigma$ if the true value of $\sin ^2\theta _{23} \lesssim 0.42$ or $$ > rsim 0.62$$ for any choices of $\delta$ and $\varphi$ . Interestingly, we also observe that when both the LIV parameters $a_{e\mu }$ and $a_{e\tau }$ are present together, they cancel out the impact of each other to a significant extent, allowing DUNE to largely regain its octant resolution capability. We also reconstruct the CP phases $\delta$ and $\varphi _{e\mu }$ / $\varphi _{e\tau }$ . The typical $1\sigma$ uncertainty on $\delta$ is 10–15 $^{\circ }$ and the same on $\varphi _{e\mu }$ / $\varphi _{e\tau }$ is 25–30 $^{\circ }$ depending on the choices of their true values.