Analysis of double-J/ψ production in Z decay at next-to-leading-order QCD accuracy

• DOI: 10.1007/jhep10(2023)120
• Publication Date: 2023-10-21T07:02:08Z
• Authors: Cong Li; Zhan Sun; Gui-Yuan Zhang
• Keywords: High Energy Physics - Phenomenology; High Energy Physics - Phenomenology (hep-ph); Nuclear and particle physics. Atomic energy. Radioactivity; Higher-Order Perturbative Calculations; Quarkonium; FOS: Physical sciences; QC770-798

A bstract In this article, we study in detail the double- J/ψ yield through Z decay at next-to-leading-order (NLO) QCD accuracy within nonrelativistic factorization. At tree level, pure diagrams predict a branching ratio of $$ {\mathcal{B}}_{Z\to J/\psi +J/\psi } <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>B</mml:mi> <mml:mrow> <mml:mi>Z</mml:mi> <mml:mo>→</mml:mo> <mml:mi>J</mml:mi> <mml:mo>/</mml:mo> <mml:mi>ψ</mml:mi> <mml:mo>+</mml:mo> </mml:mrow> </mml:msub> </mml:math> ~ 10 − 12 ; however, inclusion QED would augment prediction by approximately 2–3 orders magnitude. After incorporating corrections, results exhibit considerable increase, whereas undergo substantial reduction. Combining and contributions NLO α s , it is observed that = ( {1.110}_{-0.241-0.001}^{+0.334+0.054} <mml:msubsup> <mml:mn>1.110</mml:mn> <mml:mo>−</mml:mo> <mml:mn>0.241</mml:mn> <mml:mn>0.001</mml:mn> <mml:mn>0.334</mml:mn> <mml:mn>0.054</mml:mn> </mml:msubsup> ) × which displays fairly steady dependence on renormalization scale, significantly lower than upper limits released CMS.