characteristic for a bounded complex of hermitian G-bundles. Roughly speaking, our main results show that the Arakelov-Euler characteristic of the (logarithmic) de Rham complex of X determines certain ε-constants which are associated to the L-functions of the Artin motives obtained from X and the symplectic representations of G.Let us now describe these results in more detail. Firstly we need to say a little more about arithmetic classgroups. Let R G (resp. R s G ) be the group of virtual characters (resp. virutal symplectic characters) of G. In Section 4 we obtain a quotient. Now let S denote a finite set of primes which includes those primes where X has non-smooth reduction. Let Ω 1 X /Z log X red S / log S denote the sheaf of degree one relative logarithmic differentials of X with respect to the morphism X , X red S → (Spec (Z) , S) of schemes with log-structures.This sheaf is locally free if (as we now assume) each special fibre of X is a divisor with strictly normal crossings and the multiplicities of the irreducible components of each fibre are prime to the residue characteristic. The logarithmic de Rham complex Ω • X /Z (log X red S / log S) is defined to be the complexWe view each term of this complex as carrying the hermitian metric given by the corresponding exterior power of h D . In Theorem 7.1 we completely describe the image c s of the loga-). Here we limit ourselves to stating the result for characters of degree zero, since this result is particularly striking (see Theorem 7.1 for the result for characters of arbitrary degree):) is a rational class and for any virtual symplectic character ψ of degree zeroWhilst this result is of interest in itself, our principal concern rests with the sheaf of differentials Ω 1 X /Z . One can associate to Ω 1 X /Z and the metric h D a class Ω in the arithmetic Grothendieck group K 0 (X ), which is a λ-ring by [GS1, §7]. In [CPT2] we show d i=0 χ(λ i (Ω)) = −log|ε(X )|.