Exploring Supersymmetric CP Violation after LHC Run 2 with Electric Dipole Moments and B Observables

A. Arbey; J. Ellis; F. Mahmoudi

doi:10.1140/epjc/s10052-020-8152-y

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2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2020) 80: 594
https://doi.org/10.1140/epjc/s10052-020-8152-y

Regular Article - Theoretical Physics

Exploring Supersymmetric CP Violation after LHC Run 2 with Electric Dipole Moments and B Observables

A. Arbey¹^,2^,5, J. Ellis²^,3^,4 and F. Mahmoudi¹^,2^,5^*

¹ Université de Lyon, Université Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique des 2 Infinis de Lyon, UMR 5822, 69622, Villeurbanne, France
² Theoretical Physics Department, CERN, 1211, Geneva 23, Switzerland
³ Theoretical Particle Physics and Cosmology Group, Department of Physics, King’s College London, London, WC2R 2LS, UK
⁴ National Institute of Chemical Physics and Biophysics, Rävala 10, 10143, Tallinn, Estonia
⁵ Institut Universitaire de France, 103 Boulevard Saint-Michel, 75005, Paris, France

^* e-mail: nazila@cern.ch

Received: 12 December 2019
Accepted: 16 June 2020
Published online: 1 July 2020

Abstract

We consider the prospects for measuring distinctive signatures of the CP-violating phases in the minimal supersymmetric extension of the Standard Model (MSSM) in light of the limits on sparticle masses from searches at the LHC. We use the CPsuperH code to evaluate model predictions and scan the parameter space using a geometric approach that maximizes CP-violating observables subject to the current upper limits on electric dipole moments (EDMs). We focus on the possible CP-violating asymmetry $A_{\mathrm{CP}}$ in $b \rightarrow s \gamma$ decay and on a possible CP-violating contribution to the $B_s - {\overline{B}}_s$ mass difference $\Delta M^{NP}_{B_s}$ , as well as future measurements of the EDMs of the proton, neutron and electron. We find that the current LHC and EDM limits are consistent with values of $A_{\mathrm{CP}}$ , $\Delta M^{NP}_{B_s}$ and the proton EDM that are measurable with the Belle-II detector, LHCb and a proposed measurement of the proton EDM using a storage ring, respectively. Measurement of a non-zero proton EDM would constrain $A_{\mathrm{CP}}$ significantly, but it and a CP-violating contribution to $\Delta M^{NP}_{B_s}$ could still be measurable, along with neutron and electron EDMs. A more accurate measurement of $A_{\mathrm{CP}}$ with the current central value would favour stop and chargino masses within reach of future LHC runs as well as a potentially measurable value of $\Delta M^{NP}_{B_s}$ .