Probing Non-Perturbative QCD with CERN’s North Area Secondary Beams

by Dipanwita Banerjee (CERN)

Wednesday 28 Oct 2026, 14:00 → 16:00 Europe/Zurich

500/1-001 - Main Auditorium (CERN)

Abstract:

Many open questions in particle and astroparticle physics are limited by strong-interaction quantities that cannot yet be calculated from first principles. At low momentum transfer perturbative QCD no longer applies, and predictions rely either on phenomenological models tuned to data or on lattice QCD, which can so far compute only a limited set of observables. These quantities therefore have to be measured. This lecture discusses three experiments that do this with secondary beams in CERN’s North Area: NA61/SHINE, AMBER and MUonE.

Space-borne experiments such as AMS-02 now measure cosmic-ray fluxes at the percent level, and interpreting these data is limited by poorly known nuclear cross sections. At the H2 beamline, NA61/SHINE measures hadron production relevant to air showers, central to the cosmic-ray muon puzzle, and the nuclear fragmentation cross sections needed to infer how cosmic rays propagate through the Galaxy. At the M2 beamline, AMBER has measured antiproton production in proton–proton and proton–helium collisions at 60–250 GeV/c, aiming at few-percent precision. These reactions produce most of the secondary cosmic-ray antiprotons, the main background in dark-matter searches with cosmic antiprotons.

 

Another fundamental QCD question is the origin of hadron mass. The Higgs-generated masses account for only about 1% of the proton’s mass; the rest emerges from QCD dynamics. The pion, by contrast, is a Nambu–Goldstone boson and would be massless without the Higgs. Yet meson structure is known mainly from Drell–Yan data of the 1980s, with only about 700 kaon-induced Drell–Yan events worldwide. Using the only high-intensity, high-energy pion and kaon beam in the world, AMBER will collect the largest meson-induced Drell–Yan and charmonium samples of this decade, giving access to the valence, sea and gluon content of the pion and a much-improved picture of kaon structure.

 

With the M2 muon beam, AMBER will also measure the proton charge radius in elastic muon–proton scattering, an independent test of the proton-radius puzzle. MUonE will extract the leading hadronic vacuum-polarisation contribution to the muon g−2 from μe elastic scattering, a third route alongside the data-driven and lattice determinations that currently disagree

 

Finally, the programme through LS3 into Run 4 will be placed in the context of the Non-Collider Physics Roadmap (2027–2046).

 

Bio: 

Dipanwita Banerjee is a beam physicist in the Experimental Areas group of CERN’s Beams Department (BE-EA). She received her PhD in physics from ETH Zurich in 2017 during which she designed and built Resistive Multiplexed Micromegas tracking detectors for the NA64 and GBAR experiments at CERN. She is currently responsible for the operation of the M2 beamline in the North Area, which serves AMBER, NA64μ and MUonE, and of the T9 beamline in the East Area. She chairs the Conventional Beams EHN2 Working Group, which coordinates studies and technical solutions for the experiments in EHN2, and the Experimental Areas Technical Meeting, which follows accelerator-wide activities that affect the Experimental Areas. Her work covers beam-optics design, Monte Carlo simulation of beamlines and backgrounds for the experiments as well as machine-learning methods for beamline tuning. She also brings her experiment, beamline and operation knowledge currently working as the project lead of BRUTUS, the future control system for CERN’s secondary beamlines. 

 

QCD_AcademicTraining_v3.pdf

QCD_AcademicTraining_v3.pptx

Recording