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Neutron Valence Structure from Nuclear Deep Inelastic Scattering
E P Segarra1, A Schmidt1,2, T Kutz1,2
1Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review Letters
|March 24, 2020
Summary
This study extracts the neutron structure function from deep inelastic scattering data, revealing a constant neutron-to-proton ratio at high momentum transfer. This finding challenges scalar diquark models in quantum chromodynamics (QCD).
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Chromodynamics (QCD)
Background:
- Spin-flavor SU(6) symmetry breaking in QCD is not fully understood.
- The EMC effect describes modifications to nucleon structure functions within nuclei.
- Short-range correlated (SRC) pairs are hypothesized to universally modify nucleons.
Purpose of the Study:
- To extract the free neutron structure function.
- To investigate spin-flavor symmetry breaking mechanisms.
- To analyze the EMC effect using SRC pair framework.
Main Methods:
- Global analysis of deep inelastic scattering (DIS) data on protons and various nuclei (A=2 to 208).
- Consistent accounting for the EMC effect via universal nucleon modification in SRC pairs.
- Extraction of the neutron-to-proton structure function ratio, F_{2}^{n}/F_{2}^{p}.
Main Results:
- The ratio F_{2}^{n}/F_{2}^{p} approaches a constant value of 0.47±0.04 as x_{B}→1.
- This result aligns with perturbative QCD and Dyson-Schwinger equation predictions.
- The findings contradict predictions from the scalar diquark dominance model.
Conclusions:
- The study provides crucial insights into spin-flavor symmetry breaking in QCD.
- The results support the SRC pair model for explaining nuclear modifications of nucleon structure functions.
- Predictions are made for the MARATHON Collaboration's measurement of F_{2}^{3He}/F_{2}^{3H}.
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