Displaced Signals of Hidden Vectors at the Electron-Ion Collider (2307.00102v2)

Abstract: The Electron-Ion Collider (EIC) provides unique opportunities in searching for new physics through its high center of mass energy and coherent interactions of large nuclei. We examine how light weakly interacting vector bosons from a variety of models can be discovered or constrained, over significant parts of their parameter space, through clean displaced vertex signals at the EIC. Our results indicate that the searches we propose favorably compare with or surpass existing experimental projections for the models examined. The reach for the new physics that we consider can be markedly improved if "far backward" particle identification capabilities are included in the EIC detector complex.

• The paper introduces a novel approach using displaced decay vertices at the EIC to search for light, weakly interacting vector bosons.
• It employs detailed Feynman diagram analyses to evaluate production cross sections and model parameter spaces for dark photon, B–L, and leptophilic vectors.
• The study confirms that the EIC’s high luminosity and energy enhance search sensitivity, complementing other experiments in probing new physics.

Displaced Signals of Hidden Vectors at the Electron-Ion Collider

The paper, "Displaced Signals of Hidden Vectors at the Electron-Ion Collider," explores the potential of the upcoming Electron-Ion Collider (EIC) to investigate new physics beyond the Standard Model (SM), particularly focusing on the detection of light, weakly interacting vector bosons. Through a detailed analysis of various hidden vector models, the authors argue for the feasibility of such searches at the EIC, emphasizing the significance of utilizing displaced vertex signals.

Key Contributions and Analysis

The paper begins by contextualizing the need for new physics. The authors outline that recent theoretical and experimental developments suggest a pivoting interest from high-energy traditional approaches to investigating light, weakly interacting particles. Displaced decay vertices serve as a pivotal focal point due to their capacity to reveal such elusive particles in collider experiments.

The paper systematically examines three distinct vector boson paradigms: the dark photon model, a gauge boson coupled to the $B-L$ (baryon minus lepton number) gauge symmetry, and leptophilic gauge bosons. The theoretical foundation for each model is well-established, with specific attention given to their respective parameter spaces and coupling properties.

Methodology and Results

The authors utilize theoretical constructs and equation derivations to calculate the production cross-section of the vector bosons at the EIC. Employing robust Feynman diagrams, they consider the ultraperipheral production process, where the vector bosons' decay is displaced from the production vertex, resulting in an exceptionally low background signal.

Their analysis leverages the anticipated high luminosity and center-of-mass energies at the EIC. In particular, the correlation between the dark boson's lengthy lifetime and its displacement from the production vertex is computed to determine the potential search reach. These predictive calculations reveal that incorporating a "far backward" particle identification adds substantial depth to the prospective reach, further enhancing detection capabilities.

Implications

This investigation provides substantial implications for both theoretical and experimental physics areas. The EIC, through its superior energy and coherence from ion interactions, offers a strategic advantage for testing these hidden vector models.

The paper successfully maps out possible future constraints on vector boson parameter spaces, positioning the EIC's efforts as complementary to other experimental endeavors like those at SHiP, Belle II, and FASER. It crucially identifies parameter regions where EIC projections are competitive, particularly for the dark photon and $B-L$ gauge bosons, thus filling the void in intermediate mass scales and coupling strengths unexplored by current limits.

Future Directions

The paper speculates on the potential enhancements the field might witness. Incorporating muon detection could extend the capability beyond the projected limits by retrieving additional clarity on higher mass vector bosons.

Additionally, the authors hint at leveraging polarized electron beams, which could discern the chiral coupling nature of the vectors, thus distinguishing between different hypothetical bosons such as dark photons and dark Z bosons.

Conclusion

In conclusion, the paper solidifies the significance of the EIC as a powerful instrument for probing new physics domains. By elevating the discourse around hidden vector bosons and displaced decay vertices, the paper not only enriches the theoretical landscape but also grounds forthcoming experimental strategies. This research contributes robust groundwork, inviting further empirical exploration, and reinforces the EIC's role in the quest for comprehensively understanding subatomic phenomena.