Mon·Nov 6, 2023Monday·November 6, 2023

1. 01*

   Nuclear density dependence of polarization transfer in quasi-elastic $\mathrm{A}(\vec{e},e^{\prime }\vec{p})$ reactions

   T. Kolar🇮🇱 · W. Cosyn🇺🇸 · C. Giusti🇮🇹 · P. Achenbach🇩🇪 · A. Ashkenazi🇮🇱 · R. Böhm🇩🇪 · D. Bosnar🇭🇷 · T. Brecelj🇸🇮 · M. Christmann🇩🇪 · E. O. Cohen🇮🇱 · M. O. Distler🇩🇪 · L. Doria🇩🇪 and 43 other authors

   The ratio of the transverse and longitudinal component of polarization transfer to protons in the quasi-elastic $(\vec{e},e^{\prime }\vec{p})$ reaction, $P_x^{\prime }/P_z^{\prime }$, is sensitive to the proton's electromagnetic form factor ratio, $G_E/G_M$. To explore density-dependent in-medium modifications, a comparison of polarization transfer ratios involving protons from distinct nuclear shells, each with different local nuclear densities, has been proposed. In this study, we present such comparisons between four shells, $1s_{1/2}$, $1p_{3/2}$ in ${}^{12}\mathrm{C}$ and $1d_{3/2}$, $2s_{1/2}$ in ${}^{40}\mathrm{Ca}$. In an effort to account for other many-body effects that may differ between shells, we use a state-of-the-art relativistic distorted-wave impulse-approximation (RDWIA) calculation and present the double ratios, $(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{Data}}/(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{RDWIA}}$ as well as the super ratios, ${\left[(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{A}}/(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{B}}\right]}_{\mathrm{Data}}/{\left[(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{A}}/(P_x^{\prime }/P_z^{\prime }{)}_{\mathrm{B}}\right]}_{\mathrm{RDWIA}}$, for chosen shells A and B, as a function of effective local nuclear densities. We find that double ratios for individual shells show a dependence on the probed effective nuclear densities. Studying the ratios, we observed a systematic variation between pairs of higher- and lower-density shells.

   nucl-exnucl-thPRC(2024)·3 citations
2. 02*

   Fraction of ${\chi }_c$ decays in prompt $J/\psi$ production measured in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV

   LHCb collaboration: R. Aaij · A.S.W. Abdelmotteleb · C. Abellan Beteta · F. Abudinén · T. Ackernley · B. Adeva · M. Adinolfi · P. Adlarson · C. Agapopoulou · C.A. Aidala · Z. Ajaltouni · S. Akar and 1090 other authors

   The fraction of ${\chi }_{c1}$ and ${\chi }_{c2}$ decays in the prompt $J/\psi$ yield, $F_{\chi c}={\sigma }_{{\chi }_c\to J/\psi }/{\sigma }_{J/\psi }$, is measured by the LHCb detector in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV. The study covers the forward ($1.5<y^{\ast }<4.0$) and backward ($-5.0<y^{\ast }<-2.5$) rapidity regions, where $y^{\ast }$ is the $J/\psi$ rapidity in the nucleon-nucleon center-of-mass system. Forward and backward rapidity samples correspond to integrated luminosities of 13.6 $\pm$ 0.3 nb${}^{-1}$ and 20.8 $\pm$ 0.5 nb${}^{-1}$, respectively. The result is presented as a function of the $J/\psi$ transverse momentum $p_{T,J/\psi }$ in the range 1$<p_{T,J/\psi }<20$ GeV/$c$. The $F_{\chi c}$ fraction at forward rapidity is compatible with the LHCb measurement performed in $pp$ collisions at $\sqrt{s}=7$ TeV, whereas the result at backward rapidity is 2.4 $\sigma$ larger than in the forward region for $1<p_{T,J/\psi }<3$ GeV/$c$. The increase of $F_{\chi c}$ at low $p_{T,J/\psi }$ at backward rapidity is compatible with the suppression of the $\psi$(2S) contribution to the prompt $J/\psi$ yield. The lack of in-medium dissociation of ${\chi }_c$ states observed in this study sets an upper limit of 180 MeV on the free energy available in these pPb collisions to dissociate or inhibit charmonium state formation.

   ↳ hep-exnucl-exPRL(2024)·18 citations
3. 03*

   Developing predictions for pion fragmentation functions

   H.-Y. Xing🇨🇳 · Z.-Q. Yao🇮🇹 · B.-L. Li🇨🇳 · D. Binosi🇮🇹 · Z.-F. Cui🇨🇳 · C. D. Roberts🇨🇳

   Exploiting crossing symmetry, the hadron scale pion valence quark distribution function is used to predict the kindred elementary valence quark fragmentation function (FF). This function defines the kernel of a quark jet fragmentation equation, which is solved to obtain the full pion FFs. After evolution to a scale typical of FF fits to data, the results for quark FFs are seen to compare favourably with such fits. However, the gluon FF is markedly different. Notably, although FF evolution equations do not themselves guarantee momentum conservation, inclusion of a gluon FF which, for four quark flavours, distributes roughly 11% of the total light-front momentum fraction, is sufficient to restore momentum conservation under evolution. Overall, significant uncertainty is attached to FFs determined via fits to data; hence, the features of the predictions described herein could potentially provide useful guidance for future such studies.

   ↳ hep-phhep-exhep-latnucl-ex+1EPJC(2024)·18 citations
4. 04*

   Production of the $\Xi N$ dibaryon as a weakly bound system in $pp$ collisions

   Tian-Chen Wu🇨🇳 · Atsushi Hosaka🇯🇵 · Li-Sheng Geng🇨🇳

   The $\Xi N$ interaction plays an important role in our understanding on the long-anticipated $H$-dibaryon. Recent lattice QCD calculations verified the attractive nature of the $\Xi N$ interaction. On the other hand, whether it is strong enough to generate a bound state remains inconclusive.In this work, assuming that it can generate a weakly bound state, we study the yields of the $\Xi N$ dibaryon for different binding energies in $pp$ collisions at 7 TeV using the coalescence model and the transport model PACIAE. The yields are estimated first numerically and then analytically adopting a Yukawa-type wave function. In particular, we find that in the weak binding limit, there exists a universal relation between the yield and the binding energy, valid for $pp$ collisions.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2024)·0 citations
5. 05*

   Precision three-dimensional imaging of nuclei using recoil-free jets

   Shen Fang🇨🇳 · Weiyao Ke🇨🇳 · Ding Yu Shao🇨🇳 · John Terry🇺🇸

   In this study, we explore the azimuthal angle decorrelation of lepton-jet pairs in e-p and e-A collisions as a means for precision measurements of the three-dimensional structure of bound and free nucleons. Utilizing soft-collinear effective theory, we perform the first-ever resummation of this process in e-p collisions at NNLL accuracy using a recoil-free jet axis. Our results are validated against Pythia simulations. In e-A collisions, we address the complex interplay between three characteristic length scales: the medium length $L$, the mean free path of the energetic parton in the medium $\lambda$, and the hadronization length $L_h$. We demonstrate that in the thin-dilute limit, where $L\ll L_h$ and $L\sim \lambda$, this process can serve as a robust probe of the three-dimensional structure for bound nucleons. We conclude by offering predictions for future experiments at the Electron-Ion Collider within this limit.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2024)·12 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.