A light leptophobic Z' in polarized hadronic collisions

Abstract

Theoretical and phenomenological arguments are in favor of an elusive new neutral vector boson Z' with a relatively low mass, chiral couplings to ordinary quarks and whose couplings to ordinary leptons are suppressed (leptophobia). We point out that this new particle could induce some parity violating spin asymmetries which could be measured soon at the Brookhaven Relativistic Heavy Ion Collider (RHIC), running part of the time as a polarized hadronic collider.Comment: Latex file, 13 pages and 3 ps fig. included in tex file with psfig.st

Constraints on leptophobic gauge bosons with polarized neutrons and protons at RHIC

“…The result of our calculation for these models in the case of p p collisions has been already displayed in ref. [8]. Concerning the standard asymmetry, one can notice that, in spite of the smaller center of mass energy the A L ( nn) is larger than the one calculated for p p collisions in ref.…”

“…One has also to add the very tiny Electroweak-Z interference which will not yield an observable effect. As it was already pointed out in reference [8], 95% of the effect due to the new boson comes from Z -gluon interference terms involving the scattering of identical quarks in the t, u-channels. In the case of nn collisions it corresponds essentially to the scattering of d quarks.…”

“…At first, the machine will run with E p = 250 GeV , it is the reason why we have taken a center mass energy √ s = 500 GeV for p p collisions [8]. A 3 He nuclei, being accelerated, will get the total energy of its two protons.…”

“…Hence, we have E3 He = 600 GeV and E n = 200 GeV , n n (or nn) collisions reaching an energy √ s = 400 GeV in the center of mass, value that we take in the following. Concerning the integrated luminosities, we have taken the same values as in [8], namely L 1 = 800 pb −1 and L 2 = 3.2 f b −1 for practical comparison with the p p results, even if these values are certainly a little bit optimistic. However, if we take seriously the possibility of some luminosity upgrades at RHIC in the future [23], these numbers become perfectly realistic.…”

“…We refer the reader to ref. [8] and to the original literature for more details on the theoretical motivations and on the underlying structures of each model.…”