General COHERENT constraints on neutrino nonstandard interactions

We present the results of a systematic study of the constraints on neutrino neutral-current nonstandard interactions (NSIs) that can be obtained from the analysis of the COHERENT spectral and temporal data. First, we consider the general case in which all ten relevant neutral-current NSI parameters are considered as free. We show that they are very weakly constrained by the COHERENT data because of possible cancellations between the up and down quark contributions. However, the up-down average parameters are relatively well constrained, and the strongest constraints are obtained for an appropriate linear combination of up and down NSI parameters. We also consider the case in which there are only NSIs with either up or down quarks, and we show that the LMA-Dark fit of solar neutrino data is excluded at 5.6 sigma and 7.2 sigma, respectively, for NSIs with up and down quarks. We finally present the tight constraints that can be obtained on each NSI parameter if it is the dominant one, assuming that the effects of the others are negligible.