Electroweak Sphaleron with Dimension-6 Operators (1708.03061v3)

Abstract: New physics at the TeV scale can affect the dynamics of the electroweak phase transition in many ways. In this note, we evaluate its impact on the rate of baryon-number violation via sphaleron transitions. We parameterize the effect of new physics with dimension-6 operators, and we use the Newton-Kantorovich method to numerically solve the resulting equations of motion. Depending on the sign of the coefficient of the dimension-6 operators, their presence can either increase or decrease the sphaleron energy at the level of a few percent, parametrically of order $m_W^2 / \Lambda^2$ where $\Lambda$ is the scale suppressing the dimension-6 operator. The baryon-number washout condition, typically written as $v_c / T_c > 1$, is directly proportional to the sphaleron energy, and we discuss how the presence of dimension-6 operators can affect electroweak baryogenesis.