Far-forward neutrinos at the Large Hadron Collider

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Springer

Received: February 18, Revised: May 5, Accepted: May 11, Published: June 3,

2020 2020 2020 2020

Far-forward neutrinos at the Large Hadron Collider

a

Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, U.S.A. b Brookhaven National Laboratory, Upton, NY 11973-5000, U.S.A. c Universit` a degli Studi di Firenze, Dipartimento di Fisica e Astronomia & INFN, Firenze, Italy d Theoretical Physics Department, CERN, 1211 Geneva 23, Switzerland

E-mail: [email protected], [email protected], [email protected], [email protected], [email protected] Abstract: 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-kT effects are approximated by a simple phenomenological model introducing a Gaussian kT -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 DsĀ± production are compared with LHCb data on double-differential cross-sections in transverse momentum and rapidity. The uncertainties 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. Keywords: Beyond Standard Model, Heavy Quark Physics, Neutrino Physics ArXiv ePrint: 2002.03012

c The Authors. Open Access, Article funded by SCOAP3 .

https://doi.org/10.1007/JHEP06(2020)032

JHEP06(2020)032

Weidong Bai,a Milind Diwan,b Maria Vittoria Garzelli,c Yu Seon Jeongd and Mary Hall Renoa

Contents 1 Introduction

1

2 Overview of forward neutrino detection geometry

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3 Forward heavy-flavor production and decay at the LHC

5 12 12 18

5 New physics

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6 Conclusions

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A Decay distributions

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1

Introduction

Since the discovery of oscillation properties of neutrinos, their fundamental roles in shaping the universe ha