Detecting the neutrino magnetic moment at hadron colliders

Abstract

We consider the model based on the $SU(2{)}_{R}\ifmmode\times\else\texttimes\fi{}SU(2{)}_{L}\ifmmode\times\else\texttimes\fi{}U(1{)}_{B\ensuremath{-}L}$ gauge group with Majorana neutrinos. In this model the transit dipole magnetic moment $({\ensuremath{\mu}}^{\ensuremath{\nu}N}{)}_{if}$ which is associated with the ${N}_{i}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{f}\ensuremath{\gamma}$ transition may be as large as a $\text{few}\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}8}{\ensuremath{\mu}}_{B}$. The possible manifestations of the $({\ensuremath{\mu}}^{\ensuremath{\nu}N}{)}_{if}$ at hadron colliders are investigated. In doing so, we assume that one of the three heavy right-handed neutrinos ${N}_{eR}$ is on the electroweak scale. The process of ${N}_{eR}$ production $p+p\ensuremath{\rightarrow}{W}_{R}^{\ensuremath{-}}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}{N}_{eR}$, with the subsequent ${N}_{eR}$ decay through the channel ${N}_{eR}\ensuremath{\rightarrow}{\ensuremath{\nu}}_{eL}+\ensuremath{\gamma}$, is investigated. Problems caused by selecting the signal from background is examined. It is shown that the process in question is the most perspective one for detecting the $({\ensuremath{\mu}}^{\ensuremath{\nu}N}{)}_{if}$, provided the condition ${m}_{{W}_{R}}<6\text{ }\text{ }\mathrm{TeV}$ is realized. The cross section of ${N}_{\ensuremath{\mu}R}$ production under the collision of a high-energy light neutrino beam with the proton target ${\ensuremath{\nu}}_{\ensuremath{\mu}L}+p\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\rightarrow}{N}_{\ensuremath{\mu}R}+p+X$ is investigated. The produced ${N}_{\ensuremath{\mu}R}$ neutrino is identified through the decay channel ${N}_{\ensuremath{\mu}R}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ifmmode\pm\else\textpm\fi{}}+2j$. Detection of both the positive and negative charged muons will point to the Majorana nature of the neutrino. On the other hand, detection of the right-handed polarized muons will be unambiguously indicative of a nonzero value of $({\ensuremath{\mu}}^{\ensuremath{\nu}N}{)}_{if}$.