Ultrahigh energy neutrino scattering: An update

Abstract

We update our estimates of charged and neutral current neutrino total cross sections on isoscalar nucleons at ultrahigh energies using a global (x, Q 2 ) fit, motivated by the Froissart bound [1], to the F2 (electron-proton) structure function utilizing the most recent analysis [2] of the complete ZEUS and H1 data sets from HERA I. Using the large Q 2 , small Bjorken-x limits of the "wee" parton model, we connect the ultrahigh energy neutrino cross sections directly to the large Q 2 , small x extrapolation of our new fit, which we assume saturates the Froissart bound [1]. We compare both to our previous work [3], which utilized only the smaller ZEUS [4] data set, as well as to recent results [5] of a calculation using the ZEUS-S based global perturbative QCD parton distributions using the combined HERA I results as input. Our new results substantiate our previous conclusions [3], again predicting significantly smaller cross sections than those predicted by extrapolating pQCD calculations to neutrino energies above 10 9 GeV.

Connection of the virtualγ*pcross section ofepdeep inelastic scattering to realγ<

“…(5) and [7,8]. Those models provide good fits to the HERA data at small x and Q 2 above 1-2 GeV 2 , so we would like our extended model to be compatible with them at large Q 2 .…”

“…It has been argued in a series of papers [5][6][7][8][9] that the DIS structure function F γp 2 is basically hadronic in nature, reflecting the strong hadronic interactions initiated by the γ * , and should show the saturated Froissart bounded behavior [10][11][12][13] observed for other hadronic scattering processes [14][15][16] and real γp scattering [17,18]. The arguments are summarized in Ref.…”

“…In [7,8] we presented an accurate fit to the HERA data for Q 2 ≥ 0.85 GeV 2 , x 0.1, using the data as combined by the ZEUS and H1 groups [19] and the Froissart-bounded model proposed by Berger, Block, and Tan [6],…”

“…(5) and [6][7][8] replaced by 2mν. Absorbing powers of ln(Q 2 + µ 2 ) from the coefficient functions, we then write the argument of the energy-dependent logarithms as 2mν/(Q 2 + µ 2 ).…”

“…We take the coefficient function A(Q 2 ), B(Q 2 ), C(Q 2 ) to have the logarithmic form at large Q 2 assumed in [6][7][8] since this behavior describes the large-Q 2 HERA data well, but have modified the arguments to eliminate the divergences that appeared in [6] for Q 2 → 0, taking…”