Wed·Aug 30, 2023Wednesday·August 30, 2023

1. 01*

   Quasiprojectile breakup and isospin equilibration at Fermi energies: an indication of longer projectile-target contact times?

   C. Ciampi🇫🇷 · S. Piantelli🇮🇹 · G. Casini🇮🇹 · A. Ono🇯🇵 · J. D. Frankland🇫🇷 · L. Baldesi🇮🇹 · S. Barlini🇮🇹 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · A. Camaiani🇮🇹 · A. Chbihi🇫🇷 · J. A. Dueñas🇪🇸 and 29 other authors

   An investigation of the quasiprojectile breakup channel in semiperipheral and peripheral collisions of ${}^{58,64}$Ni+${}^{58,64}$Ni at 32 and 52 MeV/nucleon is presented. Data have been acquired in the first experimental campaign of the INDRA-FAZIA apparatus in GANIL. The effect of isospin diffusion between projectile and target in the two asymmetric reactions has been highlighted by means of the isospin transport ratio technique, exploiting the neutron-to-proton ratio of the quasiprojectile reconstructed from the two breakup fragments. We found evidence that, for the same reaction centrality, a higher degree of relaxation of the initial isospin imbalance is achieved in the breakup channel with respect to the more populated binary output, possibly indicating the indirect selection of specific dynamical features. We have proposed an interpretation based on different average projectile-target contact times related to the two exit channels under investigation, with a longer interaction for the breakup channel. The time information has been extracted from AMD simulations of the studied systems coupled to GEMINI++: the model calculations support the hypothesis hereby presented.

   nucl-exPRC(2023)·15 citations
2. 02*

   Helicity dependent cross sections for the photoproduction of ${\pi }^0{\pi }^{\pm }$ pairs from quasi-free nucleons

   A2 Collaboration: D. Ghosal🇨🇭 · V. Sokhoyan🇩🇪 · A. Fix🇷🇺 · S. Lutterer🇨🇭 · S. Abt🇨🇭 · P. Achenbach🇩🇪 · F. Afzal🇩🇪 · Z. Ahmed🇨🇦 · J.R.M. Annand🇬🇧 · M. Bashkanov🇬🇧 · R. Beck🇩🇪 · M. Biroth🇩🇪 and 61 other authors

   Photoproduction of ${\pi }^0{\pi }^{\pm }$-pairs from quasifree nucleons bound in the deuteron has been investigated to study the helicity dependence of this reaction. Measurements with a liquid deuterium target were used to extract the unpolarized cross sections for reactions on protons and neutrons. A deuterated, longitudinally polarized solid-butanol target, together with a circularly polarized photon beam, determined the double polarization observable $E$. From these results the spin-dependent cross sections ${\sigma }_{1/2}$ and ${\sigma }_{3/2}$, corresponding to the anti-parallel and parallel spin configurations of the beam photon and target nucleon, have been derived. The measurements were performed at the Mainz MAMI accelerator with tagged, circularly-polarized photon beams produced via bremsstrahlung from longitudinally polarized electron beams. The reaction products were detected with an almost $4\pi$ solid-angle covering calorimeter composed of the Crystal Ball and TAPS detectors, supplemented by plastic scintillation detectors for charged particle identification. The results are sensitive to sequential decays of nucleon resonances via intermediate states and also to the decay of nucleon resonances by emission of charged $\rho$ mesons, and are compared to recent model results.

   nucl-exPLB(2023)·3 citations
3. 03*

   High-precision Penning-trap mass measurements of Cd and In isotopes at JYFLTRAP remove the fluctuations in the two-neutron separation energies

   A. Jaries🇫🇮 · M. Stryjczyk🇫🇮 · A. Kankainen🇫🇮 · L. Al Ayoubi🇫🇮 · O. Beliuskina🇫🇮 · P. Delahaye🇫🇷 · T. Eronen🇫🇮 · M. Flayol🇫🇷 · Z. Ge🇩🇪 · W. Gins🇫🇮 · M. Hukkanen🇫🇮 · D. Kahl🇷🇴 and 14 other authors

   We report on the first direct mass measurements of the ${}^{118,119}$Cd and ${}^{117-119}$In isotopes performed at the Ion Guide Isotope Separator On-Line facility using the JYFLTRAP double Penning trap mass spectrometer. The masses of ${}^{117}$In and ${}^{118}$Cd isotopes are in agreement with the literature, while ${}^{118,119}$In and ${}^{119}$Cd differ from literature by 49, 13 and 85 keV (6.1, 1.9 and 2.1 standard deviations), respectively. The excitation energy of the ${}^{118}$In first isomeric state, $E_x=40.3(25)$ keV, was determined for the first time. The updated mass values removed the fluctuations observed in the two-neutron separation energies and lead to a smoother linear decrease of both isotopic chains. The $\log (ft)$ value for the ${}^{118}$Cd decay is also found to increase from 3.93(6) to 4.089(8). The reported results indicate an absence of significant structural changes around $N=70$.

   nucl-exPRC(2023)·10 citations
4. 04*

   First simultaneous global QCD analysis of dihadron fragmentation functions and transversity parton distribution functions

   C. Cocuzza🇺🇸 · A. Metz🇺🇸 · D. Pitonyak🇺🇸 · A. Prokudin🇺🇸 · N. Sato🇺🇸 · R. Seidl🇺🇸

   We perform a comprehensive study within quantum chromodynamics (QCD) of dihadron observables in electron-positron annihilation, semi-inclusive deep-inelastic scattering, and proton-proton collisions, including recent cross section data from Belle and azimuthal asymmetries from STAR. We extract simultaneously for the first time ${\pi }^{+}{\pi }^{-}$ dihadron fragmentation functions (DiFFs) and the nucleon transversity distributions for up and down quarks as well as antiquarks. For the transversity distributions we impose their small-$x$ asymptotic behavior and the Soffer bound. In addition, we utilize a new definition of DiFFs that has a number density interpretation to then calculate expectation values for the dihadron invariant mass and momentum fraction. Furthermore, we investigate the compatibility of our transversity results with those from single-hadron fragmentation (from a transverse momentum dependent/collinear twist-3 framework) and the nucleon tensor charges computed in lattice QCD. We find a universal nature to all of this available information. Future measurements of dihadron production can significantly further this research, especially, as we show, those that are sensitive to the region of large parton momentum fractions.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2024)·60 citations
5. 05*

   Pinning down electron correlations in RaF via spectroscopy of excited states and high-accuracy relativistic quantum chemistry

   M. Athanasakis-Kaklamanakis🇨🇭 · S. G. Wilkins🇺🇸 · L. V. Skripnikov · A. Koszorús🇨🇭 · A. A. Breier🇩🇪 · O. Ahmad🇧🇪 · M. Au🇨🇭 · S. W. Bai🇨🇳 · I. Belošević🇨🇦 · J. Berbalk🇧🇪 · R. Berger🇩🇪 · C. Bernerd🇨🇭 and 44 other authors

   We report the spectroscopy of the 14 lowest excited electronic states in the radioactive molecule radium monofluoride (RaF). The observed excitation energies are compared with fully relativistic state-of-the-art Fock-space coupled cluster (FS-RCC) calculations, which achieve an agreement of >=99.64% (within ~12 meV) with experiment for all states. Guided by theory, a firm assignment of the angular momentum and term symbol is made for 10 states and a tentative assignment for 4 states. The role of high-order electron correlation and quantum electrodynamics effects in the excitation energy of excited states is studied, found to be important for all states. Establishing the simultaneous accuracy and precision of calculations is an important step for research at the intersection of particle, nuclear, and chemical physics, including searches of physics beyond the Standard Model, for which RaF is a promising probe.

   ↳ physics.atom-phnucl-exphysics.chem-phNature Commun.(2025)·19 citations
6. 06*

   Note on the electromagnetic radius of proton

   M. Ridwan🇮🇩 · T. Mart🇮🇩

   We have analyzed the proton form factor data by using a number of phenomenological parameterizations (models) and extracting the proton electric and magnetic radii. To this end we performed a global fit to all available form factor data, with the virtual photon momentum squared $Q^2$ from $0.0002$ to nearly 10 GeV${}^2$ for electric form factor and from $0.015$ to 31 GeV${}^2$ for magnetic one. Special attention was given to the small structure shown by the form factor data near $Q^2=0.2$ GeV${}^2$. It was found that different models yield different structures with different numbers of minimum at this kinematics. Since the slope of form factor in the limit of $Q^2\to 0$ is influenced by this structure, the extracted proton radii are consequently different for different models. Our finding recommends that future experiments should focus on this kinematics instead of low $Q^2$. Experimental data with accuracies comparable to those of the latest data at low $Q^2$ would clearly help to clarify the effect of this structure on the proton charge radius. Interestingly, most of the extracted proton charge radii were found to be closer to the value obtained from the muonic hydrogen atom spectroscopy.

   ↳ hep-phnucl-exnucl-thphysics.pop-phMod.Phys.Lett.A(2023)·4 citations
7. 07*

   $J/\psi$ and $\psi$(2S) polarization in proton-proton collisions at energies available at the CERN Large Hadron Collider using PYTHIA8

   Bhagyarathi Sahoo🇮🇳 · Dushmanta Sahu🇮🇳 · Suman Deb🇫🇷 · Captain R. Singh🇮🇳 · Raghunath Sahoo🇮🇳

   The production mechanisms of charmonium states in both hadronic and heavy-ion collisions hold great significance for investigating the hot and dense QCD matter. Studying charmonium polarization in ultra-relativistic collisions can also provide insights into the underlying production mechanisms. With this motivation, we explore the $J/\psi$ and $\psi$(2S) polarization in proton+proton collisions at $\sqrt{s}$ = 7, 8, and 13 TeV using a pQCD-inspired Monte-Carlo event generator called PYTHIA8. This work considers reconstructed quarkonia through their dimuons decay channel in the ALICE forward rapidity acceptance range of $2.5<y_{\mu \mu }<4$. Further, we calculate the polarization parameters ${\lambda }_{\theta }$, ${\lambda }_{\varphi }$, ${\lambda }_{\theta \varphi }$ from the polar and azimuthal angular distributions of the dimuons in helicity and Collins-Soper frames. This study presents a comprehensive measurement of the polarization parameters as a function of transverse momentum, charged-particle multiplicity, and rapidity at the LHC energies. Our findings of charmonium polarization are in qualitative agreement with the corresponding experimental data.

   ↳ hep-phhep-exnucl-exnucl-thPRC(2024)·16 citations
8. 08*

   Measurements of the $Z^0/{\gamma }^{\ast }$ cross section and transverse single spin asymmetry in 510 GeV $p$$+$$p$ collisions

   STAR Collaboration

   The differential cross section for $Z^0$ production, measured as a function of the boson's transverse momentum ($p_{\mathrm{T}}$), provides important constraints on the evolution of the transverse momentum dependent parton distribution functions (TMDs). The transverse single spin asymmetry (TSSA) of the $Z^0$ is sensitive to one of the polarized TMDs, the Sivers function, which is predicted to have the opposite sign in $p+p$ $\to W/Z+X$ from that which enters in semi-inclusive deep inelastic scattering. In this Letter, the STAR Collaboration reports the first measurement of the $Z^0/{\gamma }^{\ast }$ differential cross section as a function of its $p_{\mathrm{T}}$ in $p$$+$$p$ collisions at a center-of-mass energy of 510 GeV, together with the $Z^0/{\gamma }^{\ast }$ total cross section. We also report the measurement of $Z^0/{\gamma }^{\ast }$ TSSA in transversely polarized $p$$+$$p$ collisions at 510 GeV.

   ↳ hep-exnucl-exPLB(2024)·19 citations
9. 09*

   Ripples of the QCD Critical Point

   Wei-jie Fu🇨🇳 · Xiaofeng Luo🇨🇳 · Jan M. Pawlowski🇩🇪 · Fabian Rennecke🇩🇪 · Shi Yin🇨🇳

   We investigate the impact of a critical end point (CEP) on the experimentally accessible baryon number fluctuations of different orders. By now, its potential location has been constrained fairly accurately within first principles functional QCD, together with the location of the chiral crossover line and further thermodynamic observables. This information is incorporated in an advanced QCD-assisted low energy effective theory which is used for the computation of baryon number fluctuations at the chemical freeze-out. This computation also takes care of global baryon number conservation at larger density, where the system changes from grand-canonical to canonical statistics. We observe a prominent peak structure, whose amplitude depends on the location of the CEP, while its position is more sensitive to the location of the freeze-out curve. Our results provide guidance for future low energy heavy-ion experiments.

   ↳ hep-phnucl-exnucl-thPRD(2025)·55 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.