Far-forward neutrinos at the Large Hadron Collider

• Published in: The journal of high energy physics Vol. 2020; no. 6; pp. 1 - 38
• Main Authors: Bai, Weidong, Diwan, Milind, Garzelli, Maria Vittoria, Jeong, Yu Seon, Reno, Mary Hall
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2020; Springer Nature B.V; SpringerOpen
• Subjects: Antineutrinos; Beyond Standard Model; Charm (particle physics); Classical and Quantum Gravitation; Cross-sections; Decay; Distribution functions; Elementary Particles; Energy distribution; Flavor (particle physics); Fluxes; Galling; Gluons; Hadrons; Heavy Quark Physics; High energy physics; Large Hadron Collider; Neutrino Physics; Neutrinos; Parameter uncertainty; Partons; Physics; Physics and Astronomy; Quantum chromodynamics; Quantum Field Theories; Quantum Field Theory; Quantum Physics; Regular Article - Theoretical Physics; Relativity Theory; String Theory; Transverse momentum; Neutrino Physics; Heavy Quark Physics; Beyond Standard Model
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP06(2020)032

A bstract We present a new calculation of the energy distribution of high-energy neutrinos from the decay of charm and bottom hadrons produced at the Large Hadron Collider (LHC). In the kinematical region of very forward rapidities, heavy-flavor production and decay is a source of tau neutrinos that leads to thousands of charged-current tau neutrino events in a 1 m long, 1 m radius lead neutrino detector at a distance of 480 m from the interaction region. In our computation, next-to-leading order QCD radiative corrections are accounted for in the production cross-sections. Non-perturbative intrinsic- k T effects are approximated by a simple phenomenological model introducing a Gaussian k T -smearing of the parton distribution functions, which might also mimic perturbative effects due to multiple initial-state soft-gluon emissions. The transition from partonic to hadronic states is described by phenomenological fragmentation functions. To study the effect of various input parameters, theoretical predictions for D s ± production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertain- ties related to the choice of the input parameter values, ultimately affecting the predictions of the tau neutrino event distributions, are discussed. We consider a 3+1 neutrino mixing scenario to illustrate the potential for a neutrino experiment to constrain the 3+1 parameter space using tau neutrinos and antineutrinos. We find large theoretical uncertainties in the predictions of the neutrino fluxes in the far-forward region. Untangling the effects of tau neutrino oscillations into sterile neutrinos and distinguishing a 3+1 scenario from the standard scenario with three active neutrino flavours, will be challenging due to the large theoretical uncertainties from QCD.