Z' Coupling Information From LHeC Page: 4 of 16
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
labels everywhere in the expressions above. Furthermore, one finds that the bzj, with i, j being a
helicity labels, are given by
= (2)
bz = 9i (n)g(n) 9Q2 + M2 ,(2)
with n labeling the masses and couplings of the the various gauge bosons exchanged in the
t-channel, i.e., n = r, Z, Z', and g7 (n) are the relevant chiral couplings of the electron and
quarks to these gauge bosons in units of proton charge e. Note that since no resonances appear in
this channel it is safe to neglect the finite widths of the Z and Z' in the present analysis. Obvi-
ously for the case of Mz' > 1 TeV as considered here, very large Q2 will be necessary to show any
statistically significant non-SM behavior. From these expressions it is clear that the shifts in the
cross sections due to a Z' of a known fixed mass will depend upon the eight products of unknown
couplings, g R(Z')gLR(Z'); here we have assumed that these couplings are generation-independent
as in many, but not all, models that predict the existence of a Z'. It is just these specific coupling
combinations that we would hope to be able to constrain by fits to this deep inelastic scattering
data. Certainly, the individual Z' couplings themselves cannot be determined from these measure-
ments alone but one can then combine them with the more familiar ones obtained from the LHC
in the Drell-Yan (and possibly other) channel(s). Note that if the gauge group, G, which contains
the generator to which the Z' under discussion couples, commutes with the SU(2)L of the SM then
gZ(Z') = gJ(Z') and we have only six combinations of independent couplings to determine. This
is a rather common feature of many Z' models[1].
One could now go ahead and calculate the four differential quantities d-(eLRP) and compare
the predictions of various models with Z' exchanges included to those of the SM and to each other.
There are three reasons not to follow this direct approach. First, as is well-known, overall cross
section measurements suffer from luminosity uncertainties. Though we might expect these to be
rather small in this channel, - 0(5%), we are at the same time looking to examine small deviations
in these cross sections so it is best to avoid this problem if possible even though it is only an overall3
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Rizzo, Thomas G. Z' Coupling Information From LHeC, article, April 4, 2008; [Menlo Park, California]. (https://digital.library.unt.edu/ark:/67531/metadc900916/m1/4/: accessed April 23, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.