Purely leptonic bound states provide precision probes of QED. Positronium $(e^+e^-)$ and muonium $(\mu^+e^-)$ have long been observed, whereas dimuonium $(\mu^+\mu^-)$ and tauonium $(\tau^+\tau^-)$ remain undiscovered. We study exclusive vector-leptonium electroproduction in $ep$ collisions within nonrelativistic QED. We include the Bethe--Heitler and double deeply virtual Compton scattering contributions and their interference, and calculate the NLO QCD hard-scattering kernels entering the dominant Compton form factor $\Hcal$ within collinear GPD factorization. The NLO QCD correction to the DDVCS contribution changes from a strong suppression at low photon virtuality to a sizable enhancement as the lower virtuality cut is raised, with the gluon channel providing the dominant contribution. Bethe--Heitler production dominates the exclusive rate, supporting dedicated dimuonium searches at the EIC and JLab, with larger samples expected at higher-energy electron--proton colliders. The much larger positronium samples provide a high-statistics environment for precision QED studies, whereas tauonium production remains strongly suppressed.
We assess the prospects for inclusive heavy-quark-pair electroproduction in electron-proton ($ep$) and electron-nucleus ($e$A) collisions, alongside double-charm-pair ($D^0 \bar{D}^0$ and $D^0D^0$) electroproduction in $ep$ collisions, during the early operational phase of the Electron-Ion Collider (EIC). Based on the...
In the framework of non-relativistic quantum chromodynamics (NRQCD), we systematically investigate the inclusive and exclusive production processes of spin-singlet \(^1S_0\) and spin-triplet \(^3S_1\) toponium at future muon colliders and in Pb--Pb ultraperipheral collisions (Pb--Pb UPC). Using the Coulomb-plus-linear...
Heavy quarks (charm and beauty) are predominantly produced in hard partonic scatterings, making their cross sections in proton--proton (pp) collisions calculable in perturbative quantum chromodynamics (pQCD) and thus providing stringent tests of pQCD. Furthermore, the associated production of two charm hadrons in a sin...
Deependra Sharma· Journal of Subatomic Particl...· 0 citations
The strange quark and antiquark contents of the proton remain weakly constrained compared to the other light quarks, particularly the asymmetry between the two. Production of a $W^\mp$ boson in association with a charmed meson $D^{(*)\pm}$ could provide additional constraints in future fits of parton distribution funct...
Ville Alanko, I. Helenius, H. Paukkunen· 0 citations
The electron-positron Future Circular Collider will provide an unprecedented opportunity for precision studies at the $Z$ pole. In addition to improving the electroweak measurements pioneered at LEP, Tera-$Z$ statistics and modern jet flavor reconstruction could make rare, flavor-resolved final states accessible as pre...
We study the structure of leading hadronization effects and the contributions of massive electroweak gauge boson exchange in the $\tau_1$ and $\tau_{1a}$ 1-Jettiness global event shapes for deep inelastic scattering (DIS). The leading hadronization effects in $\tau_1$ acquire a non-trivial dependence on the hard scatte...
R. Boughezal, Hao-Tian Cao, Z. Kang et al.· 1 citation
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