F

Y~~YP+~Y~-~ 2 2 - Tx + D(x) + $ x C(x) +

x S(x). 1 Neutrino Scattering (Charged Current) : What Can Happen? Without Charm With Charm d d(x)cos20C d(x)sin2BC d d d s(x)sin2BC s(x)cos2ec S uT&+)L( qcos2tJc+ sin20Cj ‘tiHcos20c+ sin2E) = c(x) = C(x) du c 1 for v-q (or 7-T) dxdya (1 - y)2 for v-q (or v-q,. Thus daVP GF2MNE1-= dxdy in dcr* G

"NE1-= dxdy TI

symmetry limit, charge symmetry will hold to about 5% in the absence of charm. We discuss this further later in this lecture. Time Out for Data Suppose contributions due to charm could be neglected, e. g., because we are below threshold. Because the Cabibbo angle is small, we can probably neglect contributions due to strange quarks as well. This enables us to determine utd and

+d from data on neutrinos and antineutrinos. Based on the data from Gargamelle, Perkins has deduced these (Fig. 1). (See his lectures at Hawaii Summer School. ) Notice that the data are consistent with the valence quark picture for x 2 0.3 or so, i.e., U+ d = 0. (Nothing can be said about s and s because of the small Cabibbo angle. ) For x < 0.3, it would appear that u+ d # 0, but it is questionable whether these data are relevant to scaling for x,< l/

4, because neutrinos as low as 2 GeV are included (so Q2 < 1 GeV’). Given these values of u + d and u+ d, we can go further. From we know VW