Fri·Aug 27, 2021Friday·August 27, 2021

1. 01*

   Comparing meson-meson and diquark-antidiquark creation operators for a $\bar{b}\bar{b}ud$ tetraquark

   Marc Wagner🇩🇪 · Pedro Bicudo🇵🇹 · Antje Peters🇩🇪 · Sebastian Velten🇩🇪

   We compare two frequently discussed competing structures for a stable $\bar{b}\bar{b}ud$ tetraquark with quantum numbers $I(J^P)=0(1^{+})$ by considering a meson-meson as well as a diquark-antidiquark creation operator. We treat the heavy antiquarks as static with fixed positions and find diquark-antidiquark dominance for $\bar{b}\bar{b}$ separations $r<0.2\text{fm}$, while for $r>0.5\text{fm}$ the system essentially corresponds to a pair of $B$ mesons. For the meson-meson to diquark-antidiquark ratio of the tetraquark we obtain around $58\%/42\%$.

   hep-lathep-phPoS(2022)·3 citations
2. 02*

   Minimally doubled fermions and topology in 2D

   Stephan Durr🇩🇪 · Johannes H. Weber🇩🇪

   We use the two-dimensional Schwinger model to investigate how lattice fermions perceive the global topological charge $q\in \mathbf{Z}$ of a given gauge background $U$. After a warm-up part devoted to staggered, Adams, Wilson and naive fermions, we consider Karsten-Wilczek and Borici-Creutz fermions, which are in the class of minimally doubled lattice fermion actions. We focus on the eigenvalue spectrum and the chiralities of the pertinent eigenmodes. Without modification both minimally doubled actions are found to be insensitive to topology, but in either case it is possible to define a suitable species-splitting term to make the resulting operator topology aware.

   hep-latPoS(2022)·2 citations
3. 03*

   Valence quark ratio in the proton

   Zhu-Fang Cui🇨🇳 · Fei Gao🇩🇪 · Daniele Binosi🇮🇹 · Lei Chang🇨🇳 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   Beginning with precise data on the ratio of structure functions in deep inelastic scattering (DIS) from ${}^3$He and ${}^3$H, collected on the domain $0.19\le x_B\le 0.83$, where $x_B$ is the Bjorken scaling variable, we employ a robust method for extrapolating such data to arrive at a model-independent result for the $x_B=1$ value of the ratio of neutron and proton structure functions. Combining this with information obtained in analyses of DIS from nuclei, corrected for target-structure dependence, we arrive at a prediction for the proton's valence-quark ratio: ${d_v/u_v|}_{x_B\to 1}=0.230(57)$. Requiring consistency with this result presents a challenge to many descriptions of proton structure.

   ↳ hep-phhep-exhep-latnucl-ex+1Chin.Phys.Lett.(2022)·24 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.