Constraining spacetime nonmetricity with neutron spin rotation in liquid 4 He

Abstract General spacetime nonmetricity coupled to neutrons is studied. In this context, it is shown that certain nonmetricity components can generate a rotation of the neutron's spin. Available data on this effect obtained from slow-neutron propagation in liquid helium are used to constrain isotropic nonmetricity components at the level of 10 − 22 GeV. These results represent the first limit on the nonmetricity ζ ( 6 ) 2 S 000 parameter as well as the first measurement of nonmetricity inside matter.