Precision measurements of neutron decay offer complementary access to particle physics at small distance scales or high energies. In particular they allow tests of the V-A structure of the weak interaction. Among many experimental activities which are ongo

a r

X

i

v

:h e

p

-

e x /

5

4

3

4

v

1

1

8

A

p

r

2

5

Selected Aspects of Neutron Decay Stephan Paul Physik Department E18Technische Universit¨a t M¨u nchen James Frank Strasse,D-85748Garching Precision measurements of neutron decay offer complementary access to par-ticle physics at small distance scales or high energies.In particular they allow tests of the V-A structure of the weak interaction.Among many experimental activities which are ongoing around the world we present two new experiments which are planned or studied for the near future.While the neutron lifetime still bears significant experimental uncertainties and thus has to be studied with greatest precision the two-body decay (n →H ν.The

Hamiltonian for this process is written as

H =G F

2V ud ·u (1−γ5)d with G F

2=g 2

ψp f 1(q 2→0)γµ+f 2(q 2→0)σµν

m p ψn +