Thu·Apr 8, 2021Thursday·April 8, 2021

1. 01*

   Nuclear modification factor of light neutral-meson spectra up to high transverse momentum in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV

   ALICE Collaboration

   Neutral pion (${\pi }^0$) and $\eta$ meson production cross sections were measured up to unprecedentedly high transverse momenta ($p_{\mathrm{T}}$) in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 8.16 TeV. The mesons were reconstructed via their two-photon decay channel in the rapidity interval $-1.3<y<0.3$ in the ranges of $0.4<p_{\mathrm{T}}<200$ GeV/$c$ and $1.0<p_{\mathrm{T}}<50$ GeV/$c$, respectively. The respective nuclear modification factor ($R_{\mathrm{pPb}}$) is presented for $p_{\mathrm{T}}$ up to of 200 and 30 GeV/$c$, where the former was achieved by extending the ${\pi }^0$ measurement in pp collisions at $\sqrt{s}$ = 8 TeV using the merged cluster technique. The values of $R_{\mathrm{pPb}}$ are below unity for $p_{\mathrm{T}}<10$ GeV/$c$, while they are consistent with unity for $p_{\mathrm{T}}>10$ GeV/$c$, leaving essentially no room for final state energy loss. The new data provide strong constraints for nuclear parton distribution and fragmentation functions over a broad kinematic range and are compared to model predictions as well as previous results at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV.

   nucl-exhep-exPLB(2022)·54 citations
2. 02*

   $\text{nrCascadeSim}$ -- A simulation tool for nuclear recoil cascades resulting from neutron capture

   Anthony Villano🇺🇸 · Kitty Harris🇺🇸 · Staci Brown🇺🇸

   Neutron capture-induced nuclear recoils have emerged as an important tool for detector calibrations in direct dark matter detection and coherent elastic neutrino-nucleus scattering (CE$\nu$NS). $\text{nrCascadeSim}$ is a command-line tool for generating simulation data for energy deposits resulting from neutron capture on pure materials. Presently, silicon, germanium, neon, and argon are supported. While the software was developed for solid state detector calibration, it can be used for any application which requires simulated neutron capture-induced nuclear recoil data.

   ↳ physics.ins-dethep-exnucl-exJ.Open Source Softw.(2022)·6 citations
3. 03*

   Role of triaxiality in deformed halo nuclei

   K. Uzawa🇯🇵 · K. Hagino🇯🇵 · K. Yoshida🇯🇵

   It is known that nuclear deformation plays an important role in inducing the halo structure in neutron-rich nuclei by mixing several angular momentum components. While previous theoretical studies on this problem in the literature assume axially symmetric deformation, we here consider non-axially symmetric deformations. With triaxial deformation, the $\Omega$ quantum number is admixed in a single-particle wave function, where $\Omega$ is the projection of the single-particle angular momentum on the symmetric axis, and the halo structure may arise even when it is absent with the axially symmetric deformation. In this way, the area of halo nuclei may be extended when triaxial deformation is considered. We demonstrate this idea using a deformed Woods-Saxon potential for nuclei with neutron number N=13 and 43.

   ↳ nucl-thnucl-exPRC(2021)·9 citations
4. 04*

   Single-nucleon removal cross sections on nucleon and nuclear targets

   J.A. Tostevin🇬🇧

   The eikonal direct-reaction model, as used in spectroscopic studies of intermediate-energy nucleon-removal reactions on light target nuclei, is considered in the case of a proton target and applied to neutron removal from ${}^{29}$Ne at 240 MeV/nucleon. The computed cross sections and their sensitivities are compared using an earlier detailed analysis of carbon target data. The nuclear structure input, for the ${}^{29}$Ne ground-state and ${}^{28}$Ne final states, is that deduced from the carbon target analysis. The comparisons quantify the sensitivity of the two reactions to the angular momenta and binding energies of the active valence orbitals - showing the carbon target to be relatively more efficient for removals from weakly-bound, low-$\ell$, halo-like orbitals. Probing this sensitivity experimentally would provide useful tests of these predictions and of the model's description of the reaction mechanism.

   ↳ nucl-thnucl-ex3 citations
5. 05*

   Fermion Pair Dynamics in Open Quantum Systems

   S. M. Wang🇺🇸 · W. Nazarewicz🇺🇸

   Three-body decay is a rare decay mode observed in a handful of unbound rare isotopes. The angular and energy correlations between emitted nucleons are of particular interest, as they provide invaluable information on the interplay between structure and reaction aspects of the nuclear open quantum system. To study the mechanism of two-nucleon emission, we developed a time-dependent approach that allows us to probe emitted nucleons at long times and large distances. We successfully benchmarked the new method against the Green's function approach and applied it to low-energy two-proton and two-neutron decays. In particular, we studied the interplay between initial-state nucleon-nucleon correlations and final-state interaction. We demonstrated that the time evolution of the two-nucleon wave function is strongly impacted by the diproton/dineutron dynamics and that the correlations between emitted nucleons provide invaluable information on the dinucleon structure in the initial-state.

   ↳ nucl-thnucl-exPRL(2021)·52 citations
6. 06*

   Magnetic Field Measurement and Analysis for the Muon g-2 Experiment at Fermilab

   T. Albahri (39)🇬🇧 · A. Anastasi (11)🇮🇹 · K. Badgley (7)🇺🇸 · S. Baeßler (47 and 49)🇺🇸 · I. Bailey (19 and 50)🇬🇧 · V. A. Baranov (17)🇷🇺 · E. Barlas-Yucel (37)🇺🇸 · T. Barrett (6)🇺🇸 · F. Bedeschi (11)🇮🇹 · M. Berz (20)🇺🇸 · M. Bhattacharya (43)🇺🇸 · H. P. Binney (48)🇺🇸 and 161 other authors

   The Fermi National Accelerator Laboratory has measured the anomalous precession frequency $a_{\mu }^{}=(g_{\mu }^{}-2)/2$ of the muon to a combined precision of 0.46 parts per million with data collected during its first physics run in 2018. This paper documents the measurement of the magnetic field in the muon storage ring. The magnetic field is monitored by nuclear magnetic resonance systems and calibrated in terms of the equivalent proton spin precession frequency in a spherical water sample at 34.7${}^{\circ }$C. The measured field is weighted by the muon distribution resulting in ${\tilde{\omega }}_p^{\prime }$, the denominator in the ratio ${\omega }_a^{}$/${\tilde{\omega }}_p^{\prime }$ that together with known fundamental constants yields $a_{\mu }^{}$. The reported uncertainty on ${\tilde{\omega }}_p^{\prime }$ for the Run-1 data set is 114 ppb consisting of uncertainty contributions from frequency extraction, calibration, mapping, tracking, and averaging of 56 ppb, and contributions from fast transient fields of 99 ppb.

   ↳ hep-exnucl-exPRA(2021)·188 citations
7. 07*

   Genuine empirical pressure within the proton

   Adam Freese🇺🇸 · Gerald A. Miller🇺🇸

   A phenomenological extraction of pressure within the proton has recently been performed using JLab CLAS data (arXiv:2104.02031 [nucl-ex]). The extraction used a 3-dimensional Breit frame description in which the initial and final proton states have different momenta. Instead, we obtain the two-dimensional transverse light front pressure densities that incorporate relativistic effects arising from the boosts that cause the initial and final states to differ. The mechanical radius is then determined to be $0.518\pm 0.062_{\mathrm{fit}}\pm 0.126_{\mathrm{sys}}\mathrm{fm}$, which is smaller than the electric charge radius and larger than the light front momentum radius. The forces within the proton are shown to be predominantly repulsive at distances less than $0.43\pm 0.12\mathrm{fm}$ from the center, and predominantly attractive further out.

   ↳ hep-phnucl-exnucl-thPRD(2021)·30 citations
8. 08*

   Measurement of the anomalous precession frequency of the muon in the Fermilab Muon g-2 experiment

   T. Albahri (39)🇬🇧 · A. Anastasi (11)🇮🇹 · A. Anisenkov (4 and 49)🇷🇺 · K. Badgley (7)🇺🇸 · S. Baeßler (47 and 50)🇺🇸 · I. Bailey (19 and 51)🇬🇧 · V. A. Baranov (17)🇷🇺 · E. Barlas-Yucel (37)🇺🇸 · T. Barrett (6)🇺🇸 · A. Basti (11 and 32)🇮🇹 · F. Bedeschi (11)🇮🇹 · M. Berz (20)🇺🇸 and 166 other authors

   The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency ${\omega }_a$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment's muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of $a_{\mu }(\mathrm{FNAL})=116592040(54)\times 10^{-11}$ (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the eleven separate determinations of \omega_a, and the systematic uncertainties on the result.

   ↳ hep-exnucl-exPRD(2021)·309 citations
9. 09*

   Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

   B. Abi (44)🇬🇧 · T. Albahri (39)🇬🇧 · S. Al-Kilani (36)🇬🇧 · D. Allspach (7)🇺🇸 · L. P. Alonzi (48)🇺🇸 · A. Anastasi (11)🇮🇹 · A. Anisenkov (4 and 49)🇷🇺 · F. Azfar (44)🇬🇧 · K. Badgley (7)🇺🇸 · S. Baeßler (47 and 50)🇺🇸 · I. Bailey (19 and 51)🇬🇧 · V. A. Baranov (17)🇷🇺 and 225 other authors

   We present the first results of the Fermilab Muon g-2 Experiment for the positive muon magnetic anomaly $a_{\mu }\equiv (g_{\mu }-2)/2$. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ${\omega }_a$ between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ${\tilde{\omega }}_p^{\prime }$ in a spherical water sample at 34.7${}^{\circ }$C. The ratio ${\omega }_a/{\tilde{\omega }}_p^{\prime }$, together with known fundamental constants, determines $a_{\mu }(\mathrm{FNAL})=116592040(54)\times 10^{-11}$ (0.46\,ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both ${\mu }^{+}$ and ${\mu }^{-}$, the new experimental average of $a_{\mu }(\mathrm{Exp})=116592061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviations

   ↳ hep-exnucl-exPRL(2021)·2181 citations
10. 10*

    The Time-reversal Odd Side of a Jet

    Xiaohui Liu🇨🇳 · Hongxi Xing🇨🇳

    We re-examine the jet probes of the nucleon spin and flavor structures. We find for the first time the time-reversal odd (T-odd) component of a jet, conventionally thought to vanish, can survive due to the non-perturbative fragmentation and hadronization effects and could be testable. This additional contribution of a jet will lead to novel jet phenomena relevant for unlocking the access to several spin structures of the nucleon, which were thought to be impossible by using jets. As examples, we show how the T-odd constituent can couple to the proton transversity at the Electron Ion Collider (EIC) and can give rise to the anisotropy in the jet production in $e^{+}{e}^{-}$ annihilations. We expect the T-odd contribution of the jet to have broad applications in high energy nuclear physics.

    ↳ hep-phhep-exnucl-exnucl-thFund.Res.(2023)·19 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.