Exploring CP violation in the MSSM

Alexandre Arbey; John Ellis; Rohini M. Godbole; Farvah Mahmoudi

doi:10.1140/epjc/s10052-015-3294-z

2024 Impact factor 4.8

Particles and Fields

Open Access

Eur. Phys. J. C (2015) 75: 85
https://doi.org/10.1140/epjc/s10052-015-3294-z

Regular Article - Theoretical Physics

Exploring CP violation in the MSSM

Alexandre Arbey¹^,2^,3, John Ellis³^,4, Rohini M. Godbole⁵ and Farvah Mahmoudi¹^,2^,3^,6^*

¹ Université de Lyon, Université Lyon 1, Centre de Recherche Astrophysique de Lyon, CNRS, UMR 5574, 69561, Saint-Genis Laval Cedex, France
² Ecole Normale Supérieure de Lyon, Lyon, France
³ Theory Division, CERN, 1211, Geneva 23, Switzerland
⁴ Theoretical Particle Physics and Cosmology Group, Department of Physics, King’s College London, London, WC2R 2LS, UK
⁵ Centre for High Energy Physics, Indian Institute of Science, Bangalore, 560012, India
⁶ Institut Universitaire de France, 103 boulevard Saint-Michel, 75005, Paris, France

^* e-mail: mahmoudi@in2p3.fr

Received: 23 October 2014
Accepted: 28 January 2015
Published online: 21 February 2015

Abstract

We explore the prospects for observing CP violation in the minimal supersymmetric extension of the Standard Model (MSSM) with six CP-violating parameters, three gaugino mass phases and three phases in trilinear soft supersymmetry-breaking parameters, using the CPsuperH code combined with a geometric approach to maximise CP-violating observables subject to the experimental upper bounds on electric dipole moments. We also implement CP-conserving constraints from Higgs physics, flavour physics and the upper limits on the cosmological dark matter density and spin-independent scattering. We study possible values of observables within the constrained MSSM (CMSSM), the non-universal Higgs model (NUHM), the CPX scenario and a variant of the phenomenological MSSM (pMSSM). We find values of the CP-violating asymmetry $A_\mathrm{CP}$ in $b \rightarrow s \gamma$ decay that may be as large as 3 %, so future measurements of $A_\mathrm{CP}$ may provide independent information about CP violation in the MSSM. We find that CP-violating MSSM contributions to the $$B_s$$ meson mass mixing term $\Delta M_{B_s}$ are in general below the present upper limit, which is dominated by theoretical uncertainties. If these could be reduced, $\Delta M_{B_s}$ could also provide an interesting and complementary constraint on the six CP-violating MSSM phases, enabling them all to be determined experimentally, in principle. We also find that CP violation in the $h_{2,3} \tau ^+ \tau ^-$ and $h_{2,3} {\bar{t}} t$ couplings can be quite large, and so may offer interesting prospects for future $$pp$$ , $$e^+ e^-$$ , $\mu ^+ \mu ^-$ and $\gamma \gamma$ colliders.