Optimized QCD Corrections at 50 Fb⁻¹ Enhance Prospects for Exclusive Double Production at B Factories

The challenging task of precisely predicting particle production at high-energy collisions receives a significant boost from new calculations concerning exclusive double production, a process crucial for testing fundamental theories of particle physics. Wen-Long Sang from Southwest University, Feng Feng, and colleagues demonstrate a refined method for calculating this process to an unprecedented level of accuracy, reaching next-to-next-to-leading order. This achievement involves an improved theoretical framework that carefully separates and calculates different contributions to the process, resulting in remarkably stable and convergent predictions. The team’s work suggests that upcoming experiments, specifically the projected 50 dataset at Belle 2, stand a very good chance of successfully observing this exclusive double production, opening new avenues for precision tests of the Standard Model.

The team calculates the process of creating two J/ψ particles from electron-positron collisions at a center-of-mass energy of 10 GeV, achieving next-to-next-to-leading order (NNLO) precision. They employed an improved non-relativistic quantum chromodynamics (NRQCD) factorization approach, separating the process into components arising from photon exchange and other interactions. The contribution from photon exchange utilized a precisely measured property of the J/ψ particle, while the remaining components were calculated to NNLO in αs, a measure of the strong force, and to leading order in velocity. This refined scheme yields positive and well-behaved corrections at both first and second order in αs, demonstrating a robust and reliable theoretical framework. The team found that a component representing interactions beyond simple photon exchange contributes negligibly to the overall process, simplifying the calculations.

NNLO Corrections to Double J/ψ Production

Scientists have determined the rate of double J/ψ production with unprecedented precision, calculating corrections up to next-to-next-leading order (NNLO) in quantum chromodynamics (QCD). This calculation is crucial for understanding the strong force and for testing the predictions of QCD. The team employed a sophisticated theoretical framework, relying on perturbative QCD and advanced computational tools. These calculations involved finding and evaluating complex integrals, a computationally demanding task accomplished using a recent tool designed for multi-loop calculations. The NNLO corrections significantly improve the accuracy of the theoretical prediction for this process, allowing for more stringent tests of QCD and comparisons with experimental data. The precise prediction is particularly valuable for experiments at B-factories, and will be essential for interpreting data from future experiments, such as those planned at the Belle II experiment. This work represents a significant advancement in high-energy physics, pushing the boundaries of our ability to calculate predictions from the Standard Model of particle physics.

Double J/ψ Production at Next-to-Next-Leading Order

Scientists have achieved a precise determination of the double J/ψ production process at next-to-next-leading order (NNLO) accuracy, utilizing a center-of-mass energy of 10. 58 GeV. The research team employed an improved non-relativistic quantum chromodynamics (NRQCD) factorization approach, carefully separating the process into components representing photon exchange and other interactions. The contribution from photon exchange was determined using the measured decay constant of the J/ψ particle, while the remaining components were calculated to NNLO in αs, a measure of the strong force, and to leading order in velocity.

This optimized scheme demonstrates positive and well-converging corrections at both first and second order in αs, indicating a robust theoretical framework. Notably, a component representing interactions beyond simple photon exchange was found to be numerically insignificant, simplifying the overall calculation. The team decomposed the differential cross section into components representing photon exchange, interference effects, and other interactions, allowing for a detailed analysis of each contribution. Measurements confirm that the contribution from photon exchange decreases predictably with increasing energy, while the interference component exhibits a different energy dependence. The results demonstrate that with a projected dataset of 50 inverse femtobarns at the Belle 2 experiment, the prospects for observing exclusive double J/ψ production are very promising, paving the way for future experimental verification of these theoretical predictions. The team’s calculations provide a crucial foundation for guiding experimental searches and interpreting future data from Belle 2.

Charmonium Production at Next-to-Next-Leading Order

This research presents a significantly refined calculation of the production of two charmonium particles, specifically the J/ψ and ψ(2S), in electron-positron collisions. Scientists achieved this by employing an improved theoretical approach, building upon a framework known as Non-Relativistic Quantum Chromodynamics (NRQCD). The team decomposed the process into components representing photon exchange and other interactions, allowing for a more accurate prediction of the production rate. Crucially, they calculated corrections up to next-to-next-leading order, representing a substantial advancement in precision.

The results demonstrate that these higher-order corrections are positive and well-behaved, indicating a reliable and converging theoretical framework. The calculated production rate for double charmonium production at an energy of 10. 58 GeV is 2. 13 femtobarns, a value considered more dependable than previous estimates. This improved prediction is particularly important because it enhances the prospects for observing this rare process at the Belle 2 experiment.

The authors anticipate that with a projected dataset of 50 inverse femtobarns, Belle 2 can realistically detect exclusive double charmonium production, offering a valuable test of quantum chromodynamics in a challenging environment. The study acknowledges that a component representing interactions beyond simple photon exchange contributes negligibly to the overall process, simplifying the analysis. This work lays a solid foundation for future experimental investigations at Belle 2 and provides a valuable benchmark for theoretical studies of heavy quarkonium production.