@article{14753,
  abstract     = {Several fixed-target experiments reported J/ψ and ϒ polarizations, as functions of Feynman x (xF) and transverse momentum (PT), in three different frames, using different combinations of beam particles, target nuclei, and collision energies. Despite the diverse and heterogeneous picture formed by these measurements, a detailed look allows us to discern qualitative physical patterns that inspire a simple empirical model. This data-driven scenario offers a good quantitative description of the J/ψ and ϒ(1S) polarizations measured in proton- and pion-nucleus collisions, in the xF 0.5 domain: more than 80 data points (not statistically independent) are well reproduced with only one free parameter. This study sets the context for future low-PT
 quarkonium polarization measurements in proton- and pion-nucleus collisions, such as those to be made by the AMBER experiment, and shows that such measurements provide significant constraints on the poorly-known parton distribution functions of the pion.},
  author       = {Faccioli, Pietro and Krätschmer, Ilse and Lourenço, Carlos},
  issn         = {1873-2445},
  journal      = {Physics Letters B},
  keywords     = {Nuclear and High Energy Physics},
  publisher    = {Elsevier},
  title        = {{Low-pT quarkonium polarization measurements: Challenges and opportunities}},
  doi          = {10.1016/j.physletb.2023.137871},
  volume       = {840},
  year         = {2023},
}

@article{6955,
  abstract     = {We study few-body bound states of charged particles subject to attractive zero-range/short-range plus repulsive Coulomb interparticle forces. The characteristic length scales of the system at zero energy are set by the Coulomb length scale D and the Coulomb-modified effective range r eff. We study shallow bound states of charged particles with D >> r eff and show that these systems obey universal scaling laws different from neutral particles. An accurate description of these states requires both the Coulomb-modified scattering length and the effective range unless the Coulomb interaction is very weak (D -> ). Our findings are relevant for bound states whose spatial extent is significantly larger than the range of the attractive potential. These states enjoy universality – their character is independent of the shape of the short-range potential.},
  author       = {Schmickler, C.H. and Hammer, H.-W. and Volosniev, Artem},
  issn         = {0370-2693},
  journal      = {Physics Letters B},
  publisher    = {Elsevier},
  title        = {{Universal physics of bound states of a few charged particles}},
  doi          = {10.1016/j.physletb.2019.135016},
  volume       = {798},
  year         = {2019},
}

@article{1453,
  abstract     = {In this Letter we exhibit a one-parameter family of new Taub-NUT instantons parameterized by a half-line. The endpoint of the half-line will be the reducible Yang-Mills instanton corresponding to the Eguchi-Hanson-Gibbons L2 harmonic 2-form, while at an inner point we recover the Pope-Yuille instanton constructed as a projection of the Levi-Civitá connection onto the positive su(2)+ ⊂ so(4) subalgebra. Our method imitates the Jackiw-Nohl-Rebbi construction originally designed for flat R4. That is we find a one-parameter family of harmonic functions on the Taub-NUT space with a point singularity, rescale the metric and project the obtained Levi-Civitá connection onto the other negative su(2)- ⊂ so(4) part. Our solutions will possess the full U(2) symmetry, and thus provide more solutions to the recently proposed U(2) symmetric ansatz of Kim and Yoon.},
  author       = {Etesi, Gábor and Hausel, Tamas},
  issn         = {0370-2693},
  journal      = {Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics},
  number       = {1-2},
  pages        = {189 -- 199},
  publisher    = {Elsevier},
  title        = {{Geometric construction of new Yang-Mills instantons over Taub-NUT space}},
  doi          = {10.1016/S0370-2693(01)00821-8},
  volume       = {514},
  year         = {2001},
}