teractions, defined with lattice spacing a, 27702 h Rea (bag, f. I + 606- I) We define the potential energy to be h2 V (a). 4+ ma2 3 Thanks to Antony Valcntini for suggesting this was the case. (54) (55) EFTA_R1_02022339 EFTA02688813 I The action (53) then becomes S= di 2 pa (t+ 21 (a,3)2 _ v(a)_ ve+