Tue·Aug 15, 2023Tuesday·August 15, 2023

1. 01*

   Observation of the X17 anomaly in the decay of the Giant Dipole Resonance of ${}^8$Be

   A.J. Krasznahorkay🇭🇺 · A. Krasznahorkay · M. Csatlós🇭🇺 · L. Csige🇭🇺 · J. Timár🇭🇺 · M. Begala🇭🇺 · A. Krakó🇭🇺 · I. Rajta🇭🇺 · I. Vajda🇭🇺

   Angular correlation spectra of $e^{+}{e}^{-}$ pairs produced in the ${}^7$Li($p$,$\gamma$)${}^8$Be nuclear reaction were studied at a proton beam energy of $E_p$~=~4.0~MeV, which corresponds to the excitation energy of the Giant Dipole Resonance (GDR) in ${}^8$Be. The spectra measured show a peak like anomaly at 120${}^{\circ }$ and a broader anomaly also above 140${}^{\circ }$. Both anomalies could consistently be described by assuming that the same hypothetical X17 particle was created both in the ground-state transition and in the transition going to the broad ($\Gamma$=1.5~MeV), first excited state in ${}^8$Be. The invariant mass of the particle, which was derived to be $m_X{c}^2=16.95\pm 0.48$(stat.)~MeV, agrees well with our previously published values.

   nucl-ex15 citations
2. 02*

   Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering

   H. Atac · A. Camsonne · M. K. Jones · M. Paolone · N. Sparveris · N. Sayadat · S. Shesthra · R. Li · S. Webster · J-P. Chen · S. Covrig-Dusa · A. Deur and 28 other authors

   We propose to conduct a measurement of the Virtual Compton Scattering reaction in Hall C that will allow the precise extraction of the two scalar Generalized Polarizabilities (GPs) of the proton in the region of $Q^2=0.05(GeV/c{)}^2$ to $Q^2=0.50(GeV/c{)}^2$. The Generalized Polarizabilities are fundamental properties of the proton, that characterize the system's response to an external electromagnetic (EM) field. They describe how easily the charge and magnetization distributions inside the system are distorted by the EM field, mapping out the resulting deformation of the densities in the proton. As such, they reveal unique information regarding the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents together. Recent measurements of the proton GPs have challenged the theoretical predictions, particularly in regard to the electric polarizability. The magnetic GP, on the other hand, can provide valuable insight to the competing paramagnetic and diamagnetic contributions in the proton, but it is poorly known within the region where the interplay of these processes is very dynamic and rapidly changing.The unique capabilities of Hall C, namely the high resolution of the spectrometers combined with the ability to place the spectrometers in small angles, will allow to pin down the dynamic signature of the GPs through high precision measurements combined with a fine mapping as a function of $Q^2$. The experimental setup utilizes standard Hall C equipment, as was previously employed in the VCS-I (E12-15-001) experiment, namely the HMS and SHMS spectrometers and a 10 cm liquid hydrogen target. A total of 59 days of unpolarized 75 $\mu A$ electron beam with energy of 1100 MeV (6 days) and 2200 MeV (53 days) is requested for this experiment.

   nucl-ex7 citations
3. 03*

   Search for axion-like particles through nuclear Primakoff production using the GlueX detector

   J.R. Pybus · T. Kolar · B. Devkota · P. Sharp · B. Yu · O. Hen · E. Piasetzky · S.N. Santiesteban · A. Schmidt · A. Somov · Y. Soreq · H. Szumila-Vance and 31 other authors

   We report on the results of the first search for the production of axion-like particles (ALP) via Primakoff production on nuclear targets using the GlueX detector. This search uses an integrated luminosity of 100 pb${}^{-1}\cdot$nucleon on a ${}^{12}$C target, and explores the mass region of 200 < $m_a$ < 450 MeV via the decay $X\to \gamma \gamma$. This mass range is between the ${\pi }^0$ and $\eta$ masses, which enables the use of the measured $\eta$ production rate to obtain absolute bounds on the ALP production with reduced sensitivity to experimental luminosity and detection efficiency. We find no evidence for an ALP, consistent with previous searches in the quoted mass range, and present limits on the coupling on the scale of $O$(1 TeV). We further find that the ALP production limit we obtain is hindered by the peaking structure of the non-target-related dominant background in GlueX, which we treat by using data on ${}^4$He to estimate and subtract these backgrounds. We comment on how this search can be improved in a future higher-statistics dedicated measurement.

   ↳ hep-exhep-phnucl-exPLB(2024)·17 citations
4. 04*

   Diquarks and the production of charmed baryons

   Hyeongock Yun🇰🇷 · Sungsik Noh🇰🇷 · Sanghoon Lim🇰🇷 · Taesoo Song🇩🇪 · Juhee Hong🇰🇷 · Aaron Park🇰🇷 · Su Houng Lee🇰🇷 · Benjamin Dönigus🇩🇪

   Utilizing a quark model characterized by parameters that effectively replicate the masses of ground state hadrons, we illustrate that $(us)$ or $(ds)$ diquarks exhibit greater compactness in comparison to $(ud)$ diquarks. Concretely, the binding energy of the $(us)$ diquark - defined as the diquark's mass minus the combined masses of its individual quarks - is found to be stronger than that of the $(ud)$ diquark. This heightened attraction present in $(us)$ diquarks could lead to enhanced production of ${\Xi }_c/D$ particles in high-energy pp or ultrarelativistic heavy-ion collisions.

   ↳ hep-phnucl-exnucl-thPLB(2024)·3 citations
5. 05*

   $X(3960)$, $X_0(4140)$, and other compact $cs\bar{c}\bar{s}$ states

   Shi-Yuan Li🇨🇳 · Yan-Rui Liu🇨🇳 · Zi-Long Man🇨🇳 · Zong-Guo Si🇨🇳 · Jing Wu🇨🇳

   We study the spectrum and rearrangement decays of S-wave $cs\bar{c}\bar{s}$ tetraquark states in a simplified quark model. The masses and widths are estimated by assuming that the $X(4140)$ is the lower $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Comparing our results with experimental measurements, we find that the recently observed $X(3960)$ by LHCb can be assigned as the lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark state and the $X_0(4140)$ could be the second lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Predictions of ratios between partial widths for the involved tetraquarks are given. We call for searches for more $cs\bar{c}\bar{s}$ tetraquarks with $J^{PC}=1^{+-}$, $0^{++}$, and $2^{++}$.

   ↳ hep-phhep-exhep-latnucl-ex+1CPC(2024)·10 citations
6. 06*

   Leveraging Staggered Tessellation for Enhanced Spatial Resolution in High-Granularity Calorimeters

   Sebouh J. Paul🇺🇸 · Miguel Arratia🇺🇸

   We advance the concept of high-granularity calorimeters with staggered tessellations, underscoring the effectiveness of a design incorporating multifold staggering cycles based on hexagonal cells to enhance position resolution. Moreover, we introduce HEXPLIT, a sub-cell re-weighting algorithm tailored to harness staggered designs, resulting in additional performance improvements. By combining our proposed staggered design with HEXPLIT, we achieve an approximately twofold enhancement in position resolution for neutrons across a wide energy range, as compared to unstaggered designs. These findings hold the potential to elevate particle-flow performance across various forthcoming facilities.

   ↳ physics.ins-dethep-exnucl-exNucl.Instrum.Meth.A(2024)·7 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.