Effect of anRRRRdimension 5 operator on proton decay in the minimal SU(5) SUGRA GUT model

Abstract

We reanalyze the proton decay in the minimal SU(5) SUGRA GUT model. Unlike previous analyses, we take into account a Higgsino dressing diagram of dimension 5 operator with right-handed matter fields (RRRR operator). It is shown that this diagram gives a dominant contribution for p → K + ν τ over that from LLLL operator, and decay rate of this mode can be comparable with that of p → K + ν µ which is dominated by the LLLL contribution. It is found that we cannot reduce both the decay rate of p → K + ν τ and that of p → K + ν µ simultaneously by adjusting relative phases between Yukawa couplings at colored Higgs interactions. Constraints on the colored Higgs mass M C and a typical squark and slepton mass mf from Super-Kamiokande limit become considerably stronger due to the Higgsino dressing diagram of the RRRR operator: M C > 6.5 × 10 16 GeV for mf < 1 TeV, and mf > 2.5 TeV for M C < 2.5 × 10 16 GeV.

Flavour Structure and Proton Decay in 6D Orbifold GUTs

“…On the experimental side, the bounds coming from the SuperKamiokande experiment have reached τ (p → e + π 0 ) ≥ 5.3 × 10 33 yrs [7] and τ (p → K +ν ) ≥ 1.9 × 10 33 yrs [8]. On the theoretical side, these bounds have motivated new detailed studies of proton decay via dimension-5 operators in supersymmetric GUTs [9]- [14]. These analyses showed that the present bounds disfavour this class of models, although the theoretical predictions strongly depend on the flavour structure assumed [12]- [14].…”

Probing the Planck scale with proton decay

“…We do include the leading contributions from chargedhiggsino dressing. In the case of charged-lepton decay modes these contributions turn out to be negligible, but [23] has shown that they can be important for the antineutrino decay modes. The bulk of the contributions come from charged-wino dressing, though the neutralwino dressing can be comparable for the antineutrino decay modes.…”

“…L,R can be found in Table 1 of [23], given in terms of the coefficients of the various four-fermion operators generated by dressing of the superpotential operators shown in Eqn. (1).…”

“…§ Eqn. (15) is written in the notation of [23]: k is a generational index, but j refers to π 0 , η 0 , K 0 , π ± or K + , and i refers to proton or neutron.…”

“…We use the standard methods for the computations, following [4] and [23]. The starting point is the higher-dimensional UV Lagrangian shown in Eqn.…”