Diboson production in the SMEFT from gluon fusion (arXiv:2306.09963v1 [hep-ph])

• Alejo Nahuel Rossia (University of Manchester)

Abstract: Precision measurements of diboson production at the LHC is an important probe of the limits of the Standard Model. The gluon-fusion channel of this process offers a connection between the Higgs and top sectors. We study in a systematic way gluon-induced diboson production in the Standard Model Effective Field Theory. We compute the amplitudes of double Higgs, double Z/W and associated ZH production at one loop and with up to one insertion of a dimension-6 operator. We study their high-energy limit and identify to which operators each channel could be most sensitive. To illustrate the relevance of these processes, we perform a phenomenological study of associated ZH production. We show that for some top operators the gluon-induced channel can offer competitive sensitivity to constraints obtained from top quark production processes.

Impact of dimension-eight SMEFT operators in the electroweak precision observables and triple gauge couplings analysis in universal SMEFT (arXiv:2304.03305v1 [hep-ph])

• Matheus Martines de Azevedo da Silva (Universidade de São Paulo)

We perform a complete study of the electroweak precision observables and electroweak gauge boson pair production in terms of the SMEFT up to ‌O(1/Λ4) under the assumption of universal, C and P conserving new physics. We show that the analysis of data from those two sectors allows us to obtain closed constraints in the relevant parameter space in this scenario. In particular we find that the Large Hadron Collider data can independently constrain the Wilson coefficients of the dimension-six and -eight operators directly contributing to the triple gauge boson vertices. Our results show that the impact of dimension-eight operators in the study of triple gauge couplings is small.

Impact of Dimension-8 SMEFT operators on Diboson Productions (arXiv:2303.10493v2 [hep-ph])

• Haolin Li (CP3/UCLouvain)

We for the first time identify all the dimension-8 (dim-8) SMEFT operators that can have an interference with the SM with E4/Λ4 enhancement in the high energy limit for the processes qq¯→WW/WZ. Our results therefore explicitly show that the non-interference observed for the dimension-six does not extend to dimension-eight. We compute the contributions of those dimension-8 operators to the cross-section at the 14 TeV Large Hadron Collider and compare the results with dimension-6 (dim-6) originated corrections at the order of dim-6-SM interference and dim-6 squared. We find one (two) dim-8 operator(s) can generate amplitudes of a similar order of magnitude compared with their dim-6 squared counterparts assuming unity dimensionless Wilson coefficients. During the study, new non-interference scenarios are found due to the selection rule of angular momentum as well as strong suppression due to the symmetric initial state for the proton-proton collider.