Colored scalars and the neutron electric dipole moment

Abstract

We investigate new contributions to the neutron electric dipole moment induced by colored scalars. As an example, we evaluate contributions coming from the color octet, weak doublet scalar, accommodated within a modified Minimal Flavor Violating framework. These flavor non-diagonal couplings of the color octet scalar might account for the measured assymmetrytree level. The same couplings constrained by this assymmetry also induce two-loop contributions to the neutron electric dipole moment. We find that the direct CP violating asymmetry in neutral D-meson decays is more constraining on the allowed parameter space than the current experimental bound on neutron electric dipole moment. We comment also on contributions of higher dimensional operators to the neutron electric dipole moment within this framework.

Neutron Electric Dipole Moment from colored scalars

“…We have also considered the di-quark mechanism obtained from one loop diagrams for W − u → dγ and W + d → uγ, and where the W-boson is attached to left-handed u → d and d → u currents. These contributions are of same type as in [14] and of same numerical order as within the SM (For further details, see our paper [2]). …”

“…There were also contributions due to amplitudes at baryonic/mesonic level where the photon was emitted from an intermediate pion or kaon within a chiral loop. Within such mechanisms, the d n /e was estimated to be of order 10 −33 to 10 −31 cm [1,2]. It was pointed out that if the pole diagrams were interpreted at quark level it would correspond to a "diquark mechanism" [14].…”

“…There are many studies on the NEDM (for a review see [1]). Here we present a study [2] of NEDM within a model suggested by Altmannshofer et al [3] containing a c → u flavor changing colored scalar. This model was proposed to explain measurements of the apparent CP asymmetry in D → K + K − /π + π − larger than SM expectations.…”

“…This model was proposed to explain measurements of the apparent CP asymmetry in D → K + K − /π + π − larger than SM expectations. At the time we published our paper [2] the value of the world average CP asymmetry was [4][5][6]:…”

“…Many theoretical studies were performed in order to explain the apparent discrepancy between (1) and an expected SM value, see for example [8][9][10][11][12]. For a a more extensive discussion on New Physics (NP) vs SM physics, we will in this short paper refer to our more extensive paper [2] which has also further references. Some of these studies have explained the observed asymmetry by SM effects [9][10][11][12].…”