The quark mass dependences of light element binding energies and nuclear scattering lengths are derived using chiral perturbation theory in combination with non–perturbative methods .
In particular , we present new , improved values for the quark mass dependence of meson resonances that enter the nuclear force .
A detailed analysis of the theoretical uncertainties arising in this determination is presented .
As an application we derive from a comparison of observed and calculated primordial deuterium and helium abundances a stringent limit on the variation of the light quark mass , \delta m _ { q } / m _ { q } = 0.02 \pm 0.04 .
Inclusion of the neutron lifetime modification under the assumption of a variation of the Higgs vacuum expectation value that translates into changing quark , electron , and weak gauge boson masses , leads to a stronger limit , | \delta m _ { q } / m _ { q } | < 0.009 .