The prompt atmospheric neutrino flux in the light of LHCb

Abstract

Abstract:The recent observation of very high energy cosmic neutrinos by IceCube heralds the beginning of neutrino astronomy. At these energies, the dominant background to the astrophysical signal is the flux of 'prompt' neutrinos, arising from the decay of charmed mesons produced by cosmic ray collisions in the atmosphere. In this work we provide predictions for the prompt atmospheric neutrino flux in the framework of perturbative QCD, using state-of-the-art Monte Carlo event generators. Our calculation includes the constraints set by charm production measurements from the LHCb experiment at 7 TeV, recently validated with the corresponding 13 TeV data. Our result for the prompt flux is a factor of about 2 below the previous benchmark calculation, in general agreement with other recent estimates, but with an improved estimate of the uncertainty. This alleviates the existing tension between the theoretical prediction and IceCube limits, and suggests that a direct detection of the prompt flux is imminent.

Observation and Characterization of a Cosmic Muon Neutrino Flux From the Northern Hemisphere Using Six Years of Icecube Data

“…The shaded area shows the uncertainty band corresponding to the prediction in Gauld et al (2016). Besides the ERS (H3p) predicition this is the closest band to the prompt flux constraint.…”

“…Several more recent calculations of the prompt flux have been published: GMS (H3p) (Garzelli et al 2015), BERSS (H3p) (Bhattacharya et al 2015) and GRRST (H3p) (Gauld et al 2016). Figure 21 shows multiple predictions for the prompt flux as well as the upper limit calculated here using the prediction from Enberg et al (2008) and taking into account a more realistic cosmic-ray model (Gaisser 2012).…”

“…For the first time, it is possible to constrain such a flux in this range of theoretical predictions. However, recent perturbative QCD calculations from Garzelli et al (2015), Bhattacharya et al (2015) and (Gauld et al 2016) predict lower prompt neutrino fluxes which are not yet constrained by the upper limit.…”

“…We acknowledge the support from the following agencies: U.S. National Science Foundation-Office of Polar Programs, U.S. National Science Foundation-Physics Division, University of Wisconsin Alumni Research Foundation, the Grid Laboratory Of Wisconsin (GLOW) grid infrastructure at the University of Wisconsin-Madison, the Open Science Grid (OSG) grid infrastructure; U.S. Department of Energy, and (Enberg et al 2008;Bhattacharya et al 2015;Garzelli et al 2015;Gauld et al 2016) in comparison to the constraint on the prompt flux given by this analysis. The shaded area shows the uncertainty band corresponding to the prediction in Gauld et al (2016).…”

“…All flux predictions are based on the cosmic-ray model from Gaisser (2012). Note. The limits for GMS (H3p) (Garzelli et al 2015), BERSS (H3p) (Bhattacharya et al 2015) and GRRST (H3p) (Gauld et al 2016) are determined by rescaling the ERS (H3p) limit with the corresponding flux ratio at 30 TeV which is well within the sensitive energy range. All flux predictions are based on the cosmic ray model from Gaisser (2012).…”