New Chiral Structures for Baryon Number Violating Nucleon Decays

We examine the most general nucleon decay interactions that involve three light quarks without being acted upon by a derivative. We identify four generic operator structures that correspond to the irreducible representations in the chiral group SU(3)_{L}⊗SU(3)_{R} of QCD, {8_{L}⊗1_{R},3[over ¯]_{L}⊗3_{R},6_{L}⊗3_{R},10_{L}⊗1_{R}}, plus their chirality partners under the interchange of chiralities L↔R. While half of them have been extensively discussed in the literature, the other half, 6_{L(R)}⊗3_{R(L)} and 10[over ¯]_{L(R)}⊗1_{R(L)}, are identified for the first time. We perform chiral matching for these interactions at the leading chiral order and find that each has a unique chiral realization in terms of the octet baryons and pseudoscalars. Notably, the chiral interaction in the 6_{L(R)}⊗3_{R(L)} representation appears at the same chiral order as those of the known ones, while the one in the 10_{L(R)}⊗1_{R(L)} representation appears at a higher chiral order. These new structures are prevalent in effective field theories and ultraviolet models, and they offer novel experimental avenues to search for baryon number violating nucleon decays.