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Measuring short-range correlations and quasi-elastic cross sections in A(e,e') at x>1 and modest Q$^2$

Y. P. Zhang, Z. H. Ye, D. Nguyen, P. Aguilera, Z. Ahmed, H. Albataineh, K. Allada, B. Anderson, D. Anez, K. Aniol, J. Annand, J. Arrington, T. Averett, H. Baghdasaryan, X. Bai, A. Beck, S. Beck, V. Bellini, F. Benmokhtar, A. Camsonne, C. Chen, J. -P. Chen, K. Chirapatpimol, E. Cisbani, S. Covrig Dusa, M. M. Dalton, D. Day, W. Deconinck, M. Defurne, D. Flay, N. Fomin, M. Friend, E. Fuchey, F. Garibaldi, D. Gaskell, S. Gilad, R. Gilman, S. Glamazdin, C. Gu, P. Gu`eye, C. Hanretty, J. -O. Hansen, M. Hashemi Shabestari, D. W. Higinbotham, M. Huang, S. Iqbal, G. Jin, N. Kalantarians, H. Kang, A. Kelleher, I. Korover, J. LeRose, J. Leckey, S. Li, R. Lindgren, E. Long, J. Mammei, P. Markowitz, D. Meekins, R. Michaels, M. Mihovilovic, N. Muangma, C. Munoz Camacho, B. E. Norum, Nuruzzaman, K. Pan, S. Phillips, E. Piasetzky, I. Pomerantz, M. Posik, V. Punjabi, X. Qian, Y. Qiang, X. Qiu, P. E. Reimer, A. Rakhman, S. Riordan, G. Ron, O. Rondon-Aramayo, L. Selvy, A. Shahinyan, R. Shneor, S. S, K. Slifer, N. Sparveris, R. Subedi, V. Sulkosky, D. Wang, J. W. Watson, L. B. Weinstein, B. Wojtsekhowski, S. A. Wood, I. Yaron, J. Zhang, Y. W. Zhang, B. Zhao, X. Zheng, P. Zhu, R. Zielinski

TL;DR

The paper investigates short-range correlations (SRCs) in nuclei through inclusive quasi-elastic electron scattering across a range of targets, focusing on isolating 2N-SRCs with $A/{}^2$H cross-section plateaus and probing potential 3N-SRCs via $A/{}^3$He ratios. Using the JLab E08-014 setup, it employs a yield-ratio method against radiatively corrected Monte Carlo simulations to extract absolute cross sections and SRC-related ratios, with careful treatment of detector acceptance, target boiling, and model dependencies. The study confirms a robust $2N$-SRC plateau and provides the first $a_2$ extractions for $^{40}$Ca and $^{48}$Ca, indicating similar SRC probabilities for light and heavier nuclei while highlighting an isospin effect in calcium isotopes. For 3N-SRCs, the data do not reveal a plateau when analyzed versus $x$, but when expressed in terms of the struck nucleon’s light-cone momentum $ obreak\alpha_{3N}$ and at higher $Q^2$, they trend toward the predicted plateau, suggesting that future higher-energy measurements could definitively identify 3N-SRCs. Overall, the work strengthens the evidence for universal 2N-SRC behavior and charts a path toward isolating 3N-SRCs with next-generation kinematics.

Abstract

We present results from the Jefferson Lab E08-014 experiment, investigating short-range correlations (SRC) through measurements of inclusive quasi-elastic scattering from $^2$H, $^3$He, $^4$He, $^{12}$C, $^{40}$Ca, and $^{48}$Ca. The kinematics were selected to isolate scattering from SRCs, yielding a plateau in the A/$^2$H cross-section ratios due to the universal two-body structure of the 2N-SRCs in light and heavy nuclei. We observe approximate plateaus in the A/$^2$H ratios and provide the first extractions of the A/$^2$H ratio for $^{40}$Ca and $^{48}$Ca. We also examine the A/$^3$He ratio, aiming to identify three-nucleon SRCs (3N-SRCs). Following the approach for isolating 2N-SRCs, searching for 3N-SRC dominance involved measuring the A/$^3$He cross section ratio at modest-to-large $Q^2$ values and looking for a plateau ratios for $x \gtorder 2.5$. This was not observed in the data, and in fact increasing $Q^2$ values moved the data \textit{further away} from the predicted plateau. We show here that, when analyzed in terms of the struck nucleon's light-cone momentum, the data exhibited the expected trend, progressively approaching the predicted 3N-SRC plateau. These observations suggest that future measurements at higher energies may facilitate a definitive isolation and identification of 3N-SRCs.

Measuring short-range correlations and quasi-elastic cross sections in A(e,e') at x>1 and modest Q$^2$

TL;DR

The paper investigates short-range correlations (SRCs) in nuclei through inclusive quasi-elastic electron scattering across a range of targets, focusing on isolating 2N-SRCs with H cross-section plateaus and probing potential 3N-SRCs via He ratios. Using the JLab E08-014 setup, it employs a yield-ratio method against radiatively corrected Monte Carlo simulations to extract absolute cross sections and SRC-related ratios, with careful treatment of detector acceptance, target boiling, and model dependencies. The study confirms a robust -SRC plateau and provides the first extractions for Ca and Ca, indicating similar SRC probabilities for light and heavier nuclei while highlighting an isospin effect in calcium isotopes. For 3N-SRCs, the data do not reveal a plateau when analyzed versus , but when expressed in terms of the struck nucleon’s light-cone momentum and at higher , they trend toward the predicted plateau, suggesting that future higher-energy measurements could definitively identify 3N-SRCs. Overall, the work strengthens the evidence for universal 2N-SRC behavior and charts a path toward isolating 3N-SRCs with next-generation kinematics.

Abstract

We present results from the Jefferson Lab E08-014 experiment, investigating short-range correlations (SRC) through measurements of inclusive quasi-elastic scattering from H, He, He, C, Ca, and Ca. The kinematics were selected to isolate scattering from SRCs, yielding a plateau in the A/H cross-section ratios due to the universal two-body structure of the 2N-SRCs in light and heavy nuclei. We observe approximate plateaus in the A/H ratios and provide the first extractions of the A/H ratio for Ca and Ca. We also examine the A/He ratio, aiming to identify three-nucleon SRCs (3N-SRCs). Following the approach for isolating 2N-SRCs, searching for 3N-SRC dominance involved measuring the A/He cross section ratio at modest-to-large values and looking for a plateau ratios for . This was not observed in the data, and in fact increasing values moved the data \textit{further away} from the predicted plateau. We show here that, when analyzed in terms of the struck nucleon's light-cone momentum, the data exhibited the expected trend, progressively approaching the predicted 3N-SRC plateau. These observations suggest that future measurements at higher energies may facilitate a definitive isolation and identification of 3N-SRCs.

Paper Structure

This paper contains 9 sections, 4 equations, 5 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Experimental Overview and Data Analysis
  3. Electron Reconstruction and Selection
  4. Cross Section Extraction
  5. Results
  6. Absolute Cross Sections
  7. A/2H Cross-Section Ratios
  8. A/3He Cross-Section Ratios
  9. Conclusion

Figures (5)

  • Figure 1: Differential cross sections for all nuclear targets for different scattering angles. Scale uncertainties are not shown.
  • Figure 2: The A/$^2$H ratio of the cross section per nucleon as a function of $x$ (top axis label) and $\alpha_{2N}$ (bottom) for the 25$^\circ$ data. Scale uncertainties are not shown. The points for $^{12}$C ($^{40}$Ca) are shifted slightly to the right (left) so they can be more easily distinguished.
  • Figure 3: $a_2$ vs. A where new results (red stars) are from Table \ref{['table_a2_fitting']}, and the $a_2$ values from the previous experiments Fomin:2011ngFrankfurt:1993spCLAS:2019vsb are taken from the updated values in Ref. Arrington:2022sov. Different $a_2$ values for the same $A$ were shifted slightly for better visualization. For the solid targets (A$\ge$12), there is an additional 1.5% uncertainty (not shown) that affects all three of these targets together, associated with the model dependence in extracting $a_2$ when the data do not yield a perfect plateau (see text above). A table of $a_2$ values from all experiments is included in the supplemental material supplemental.
  • Figure 4: The $^4$He/$^3$He ratio of the cross section per nucleon as a function of $x$ (top) $\alpha_{3N}$ (bottom) for all data sets from this work and from the lowest $Q^2$ data set of Ref. Fomin:2011ng. Scale uncertainties are not shown. Lines are the ratios of cross sections calculated using the XEMC model, included to allow for comparison of the $Q^2$ dependence of the $y$-scaling model.
  • Figure 5: The $^{12}C$/$^3$He ratio of the cross section per nucleon as a function of $x$ (top) $\alpha_{3N}$ (bottom) for all angles. Data are from this work and Ref. Fomin:2011ng. Scale uncertainties are not shown. Lines are the ratios of cross sections calculated using the XEMC model.