Wed·Jun 17, 2020Wednesday·June 17, 2020

1. 01*

   Reflections upon the Emergence of Hadronic Mass

   Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   With discovery of the Higgs boson, science has located the source for $\lesssim 2$% of the mass of visible matter. The focus of attention can now shift to the search for the origin of the remaining $\gtrsim 98$%. The instruments at work here must be capable of simultaneously generating the 1 GeV mass-scale associated with the nucleon and ensuring that this mass-scale is completely hidden in the chiral-limit pion. This hunt for an understanding of the emergence of hadronic mass (EHM) has actually been underway for many years. What is changing are the impacts of QCD-related theory, through the elucidation of clear signals for EHM in hadron observables, and the ability of modern and planned experimental facilities to access these observables. These developments are exemplified in a discussion of the evolving understanding of pion and kaon parton distributions.

   ↳ hep-phhep-exhep-latnucl-ex+1Eur.Phys.J.ST(2020)·64 citations
2. 02*

   Internal Calibration of the PandaX-II Detector with Radon Gaseous Sources

   Wenbo Ma🇨🇳 · Abdusalam Abdukerim🇨🇳 · Zihao Bo🇨🇳 · Wei Chen🇨🇳 · Xun Chen🇨🇳 · Yunhua Chen🇨🇳 · Chen Cheng🇨🇳 · Xiangyi Cui🇨🇳 · Yingjie Fan🇨🇳 · Deqing Fang🇨🇳 · Changbo Fu🇨🇳 · Mengting Fu🇨🇳 and 56 other authors

   We have developed a low-energy electron recoil (ER) calibration method with ${}^{220}$Rn for the PandaX-II detector. ${}^{220}$Rn, emanated from natural thorium compounds, was fed into the detector through the xenon purification system. From 2017 to 2019, we performed three dedicated calibration campaigns with different radon sources. We studied the detector response to $\alpha$, $\beta$, and $\gamma$ particles with focus on low energy ER events. During the runs in 2017 and 2018, the amount of radioactivity of ${}^{222}$Rn were on the order of 1\% of that of ${}^{220}$Rn and thorium particulate contamination was negligible, especially in 2018. We also measured the background contribution from ${}^{214}$Pb for the first time in PandaX-II with the help from a ${}^{222}$Rn injection. Calibration strategy with ${}^{220}$Rn and ${}^{222}$Rn will be implemented in the upcoming PandaX-4T experiment and can be useful for other xenon-based detectors as well.

   ↳ physics.ins-dethep-exnucl-exJINST(2020)·19 citations
3. 03*

   Nonrelativistic model of tetraquarks and predictions for their masses from fits to charmed and bottom meson data

   Per Lundhammar🇸🇪 · Tommy Ohlsson🇸🇪

   We investigate a nonrelativistic model of tetraquarks, which are assumed to be compact and to consist of diquark-antidiquark pairs. We fit, for the first time, basically all currently known values for the measured masses of 45 mesons, including both charmed and bottom mesons, to the model and predict masses of tetraquarks as well as diquarks. In particular, we find masses of four axial-vector diquarks, i.e., $qc$, $cc$, $qb$, and $bb$, where $q=u,d$, and 24 ground-state tetraquarks, including both heavy-light tetraquarks ($qc\overline{qc}$ and $qb\overline{qb}$) and heavy tetraquarks ($cc\overline{cc}$ and $bb\overline{bb}$). In general, our results for the masses of $qb\overline{qb}$, $cc\overline{cc}$, and $bb\overline{bb}$ are largely comparable with other reported results, whereas our results for the masses of $qc\overline{qc}$ are slightly larger than what has been found earlier. Finally, we identify some of the obtained predictions for masses of tetraquarks with masses of experimental tetraquark candidates, and especially, we find that $\psi (4660)$, $Z_b(10610)$, and $Z_b(10650)$ could be described by the model.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2020)·72 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.