Tue·Aug 31, 2021Tuesday·August 31, 2021

1. 01*

   A Direct Detection Search for Hidden Sector New Particles in the 3-60 MeV Mass Range

   A. Ahmidouch (1) · S. Davis (1) · A. Gasparian (1) · T. J. Hague (1) · S. Mtingwa (1) · R. Pedroni (1) · C. Ayerbe-Gayoso (2) · H. Bhatt (2) · B. Devkota (2) · J. Dunne (2) · D. Dutta (2) · L. El Fassi (2) and 49 other authors

   In our quest to understand the nature of dark matter and discover its non-gravitational interactions with ordinary matter, we propose an experiment using a \pbo ~calorimeter to search for or set new limits on the production rate of i) hidden sector particles in the $3-60$ MeV mass range via their $e^{+}{e}^{-}$ decay (or $\gamma \gamma$ decay with limited tracking), and ii) the hypothetical X17 particle, claimed in multiple recent experiments. The search for these particles is motivated by new hidden sector models and dark matter candidates introduced to account for a variety of experimental and observational puzzles: the small-scale structure puzzle in cosmological simulations, anomalies such as the 4.2$\sigma$ disagreement between experiments and the standard model prediction for the muon anomalous magnetic moment, and the excess of $e^{+}{e}^{-}$ pairs from the ${}^8$Be M1 and ${}^4$He nuclear transitions to their ground states observed by the ATOMKI group. In these models, the $1-100$ MeV mass range is particularly well-motivated and the lower part of this range still remains unexplored. Our proposed direct detection experiment will use a magnetic-spectrometer-free setup (the PRad apparatus) to detect all three final state particles in the visible decay of a hidden sector particle allowing for an effective control of the background and will cover the proposed mass range in a single setting. The use of the well-demonstrated PRad setup allows for an essentially ready-to-run and uniquely cost-effective search for hidden sector particles in the $3-60$ MeV mass range with a sensitivity of 8.9$\times$10${}^{-8}$ - 5.8$\times$10${}^{-9}$ to ${ϵ}^2$, the square of the kinetic mixing interaction constant between hidden and visible sectors. This updated proposal includes our response to the PAC49 comments.

   nucl-exphysics.ins-det6 citations
2. 02*

   Measurement of the $\gamma n\to K^0{\Sigma }^0$ differential cross section over the $K^{\ast }$ threshold

   K. Kohl · T.C. Jude · S. Alef · R. Beck · A. Braghieri · P. Cole · R. D. Salvo · A. Fantini · O. Freyermuth · F. Frommberger · F. Ghio · A. Gridnev and 21 other authors

   The differential cross section for the quasi-free photoproduction reaction $\gamma n\to K^0{\Sigma }^0$ was measured at BGOOD at ELSA from threshold to a centre-of-mass energy of 2400 MeV. Close to threshold the results are consistent with existing data and are in agreement with partial wave analysis solutions over the full measured energy range, with a large coupling to the $\Delta$(1900)1/2- evident. This is the first dataset covering the K* threshold region, where there are model predictions of dynamically generated vector meson-baryon resonance contributions.

   nucl-exEPJA(2023)·19 citations
3. 03*

   'Phase Transition' in the 'Thorium-Isomer Story'

   P.G. Thirolf🇩🇪 · B. Seiferle · L. v.d. Wense · I. Amersdorffer · D. Moritz🇩🇪 · J. Weitenberg🇩🇪

   Given the drastic progress achieved during recent years in our knowledge on the decay and nuclear properties of the thorium isomer 229mTh, the focus of research on this potential nuclear clock transition will turn in the near future from the nuclear physics driven `search and characterization phase' towards a laser physics driven `consolidation and realization phase'. This prepares the path towards the ultimate goal of the realization of a nuclear frequency standard, the `Nuclear Clock'. This article briefly summarizes our present knowledge, focusing on recent achievements, and points to the next steps envisaged on the way towards the Nuclear Clock.

   nucl-exphysics.ins-detActa Phys.Polon.B(2020)·1 citation
4. 04*

   Lightweight self-conjugate nucleus ${}^{80}$Zr

   A. Hamaker (1,2,3)🇺🇸 · E. Leistenschneider (1,2,6)🇺🇸 · R. Jain (1,2,3)🇺🇸 · G. Bollen (1,2,3)🇺🇸 · S.A. Giuliani (1,4,5)🇺🇸 · K. Lund (1,2)🇺🇸 · W. Nazarewicz (1,3)🇺🇸 · L. Neufcourt (1)🇺🇸 · C. Nicoloff (1,2,3)🇺🇸 · D. Puentes (1,2,3)🇺🇸 · R. Ringle (1,2)🇺🇸 · C.S. Sumithrarachchi (1,2)🇺🇸 · I.T. Yandow (1,2,3) ((1) Facility for Rare Isotope Beams, Michigan State University, East Lansing, Michigan, USA, (2) National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan, USA, (3) Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, USA, (4) European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT*-FBK), Trento, Italy, (5) Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey, United Kingdom, (6) CERN, Geneva, Switzerland)🇺🇸

   Protons and neutrons in the atomic nucleus move in shells analogous to the electronic shell structures of atoms. Nuclear shell structure varies across the nuclear landscape due to changes of the nuclear mean field with the number of neutrons $N$ and protons $Z$. These variations can be probed with mass differences. The $N=Z=40$ self-conjugate nucleus ${}^{80}$Zr is of particular interest as its proton and neutron shell structures are expected to be very similar, and its ground state is highly deformed. In this work, we provide evidence for the existence of a deformed double shell closure in ${}^{80}$Zr through high precision Penning trap mass measurements of ${}^{80-83}$Zr. Our new mass values show that ${}^{80}$Zr is significantly lighter, and thus more bound than previously determined. This can be attributed to the deformed shell closure at $N=Z=40$ and the large Wigner energy. Our statistical Bayesian model mixing analysis employing several global nuclear mass models demonstrates difficulties with reproducing the observed mass anomaly using current theory.

   nucl-exnucl-thNat.Phys.(2021)·38 citations
5. 05*

   Mass Spectra of One or Two Heavy Quark Mesons and Diquarks within a Nonrelativistic Potential Model

   L.X. Gutiérrez-Guerrero🇲🇽 · A. Alfaro🇲🇽 · A. Raya🇲🇽

   In this article, the mass spectra of mesons with one or two heavy quarks and their diquarks partners are estimated within a non-relativistic framework by solving Schrödinger equation with an effective potential inspired by a symmetry preserving Poincaré covariant vector-vector contact interaction model of quantum chromodynamics. Matrix Numerov method is implemented for this purpose. In our survey of mesons with heavy quarks, we fix the model parameter to the masses of ground-states and then extend our calculations for radial excitations and diquarks. The potential model used in this work gives results which are in good agreement with experimental data and other theoretical calculations.

   ↳ hep-phnucl-exnucl-thInt.J.Mod.Phys.A(2021)·12 citations
6. 06*

   Splitting of elliptic flow in non-central relativistic heavy-ion collisions

   Zhengyu Chen🇨🇳 · Zeyan Wang🇨🇳 · Carsten Greiner🇩🇪 · Zhe Xu🇨🇳

   We predict a new effect due to the presence of the global vorticity in non-central relativistic heavy-ion collisions, namely a splitting of the elliptic flow parameter $v_2$ at non-zero rapidity. The size of the splitting is proposed as a new observable that can be used to constrain the initial vortical configuration of the produced QCD matter in experiments. The new findings are demonstrated by numerical calculations employing the parton cascade model, Boltzmann Approach of MultiParton Scatterings (BAMPS), for non-central Au + Au collisions at $\sqrt{s_{NN}}=200GeV$.

   ↳ hep-phhep-exnucl-exnucl-th7 citations
7. 07*

   Ambiguities from nuclear interactions in the ${}^{12}$C($p,2p$)${}^{11}$B reaction

   Nguyen Tri Toan Phuc🇻🇳 · Kazuyuki Ogata🇯🇵 · Nguyen Hoang Phuc🇻🇳 · Bui Duy Linh🇻🇳 · Vo Hong Hai · Le Xuan Chung

   We investigate the impact of ambiguities coming from the choice of optical potentials and nucleon-nucleon scattering cross sections on the spectroscopic factors extracted from the ${}^{12}$C($p,2p$)${}^{11}$B reaction. These ambiguities are evaluated by analyzing the cross sections of the ${}^{12}$C($p,2p$)${}^{11}$B reaction at 100 and 200 MeV within the framework of the distorted-wave impulse approximation with realistic choices of nuclear inputs. The results show that the studied ambiguities are considerably large in this energy region and careful choices of nuclear inputs used in the reaction calculations are required to extract reliable structure information.

   ↳ nucl-thnucl-exCommun.in Phys.(2022)·0 citations
8. 08*

   Sensitivity of quasi-free reactions on details of the bound-state overlap functions

   C.A. Bertulani🇺🇸 · A. Idini🇸🇪 · C. Barbieri🇮🇹

   It is often stated that heavy-ion nucleon knockout reactions are mostly sensitive to the tails of the bound-state wavefunctions. In contrast, (p,2p) and (p,pn) reactions are known to access information on the full overlap functions within the nucleus. We analyze the oxygen isotopic chain and explore the differences between single-particle wave functions generated with potential models, used in the experimental analysis of knockout reactions, and ab initio computations from self-consistent Green's function theory. Contrary to the common belief, we find that not only the tail of the overlap functions, but also their internal part are assessed in both reaction mechanisms, which are crucial to yield accurately determined spectroscopic information.

   ↳ nucl-thnucl-exPRC(2021)·13 citations
9. 09*

   Measurement of the nuclear modification factor and prompt charged particle production in $p\mathrm{Pb}$ and $pp$ collisions at $\sqrt{s_{\mathrm{NN}}}=5\mathrm{TeV}$

   LHCb collaboration: R. Aaij · C. Abellán Beteta · T. Ackernley · B. Adeva · M. Adinolfi · H. Afsharnia · C.A. Aidala · S. Aiola · Z. Ajaltouni · S. Akar · J. Albrecht · F. Alessio and 961 other authors

   The production of prompt charged particles in proton-lead collisions and in proton-proton collisions at the nucleon-nucleon centre-of-mass energy $\sqrt{s_{\mathrm{NN}}}=5\mathrm{TeV}$ is studied at LHCb as a function of pseudorapidity ($\eta$) and transverse momentum ($p_{\mathrm{T}}$) with respect to the proton beam direction. The nuclear modification factor for charged particles is determined as a function of $\eta$ between $-4.8<\eta <-2.5$ (backward region) and $2.0<\eta <4.8$ (forward region), and $p_{\mathrm{T}}$ between $0.2<p_{\mathrm{T}}<8.0\mathrm{GeV}/c$. The results show a suppression of charged particle production in proton-lead collisions relative to proton-proton collisions in the forward region and an enhancement in the backward region for $p_{\mathrm{T}}$ larger than $1.5\mathrm{GeV}/c$. This measurement constrains nuclear PDFs and saturation models at previously unexplored values of the parton momentum fraction down to $10^{-6}$.

   ↳ hep-exnucl-exPRL(2022)·60 citations
10. 10*

    Fast & rigorous predictions for $A=6$ nuclei with Bayesian posterior sampling

    T. Djärv🇸🇪 · A. Ekström🇸🇪 · C. Forssén🇸🇪 · H. T. Johansson🇸🇪

    We make ab initio predictions for the A = 6 nuclear level scheme based on two- and three-nucleon interactions up to next-to-next-to-leading order in chiral effective field theory ($\chi$EFT). We utilize eigenvector continuation and Bayesian methods to quantify uncertainties stemming from the many-body method, the $\chi$EFT truncation, and the low-energy constants of the nuclear interaction. The construction and validation of emulators is made possible via the development of JupiterNCSM -- a new M-scheme no-core shell model code that uses on-the-fly Hamiltonian matrix construction for efficient, single-node computations up to $N_{\max }=10$ for ${}^6\mathrm{Li}$. We find a slight underbinding of ${}^6\mathrm{He}$ and ${}^6\mathrm{Li}$, although consistent with experimental data given our theoretical error bars. As a result of incorporating a correlated $\chi$EFT-truncation errors we find more precise predictions (smaller error bars) for separation energies: $S_d({}^6\mathrm{Li})=0.89\pm 0.44$ MeV, $S_{2n}({}^6\mathrm{He})=0.20\pm 0.60$ MeV, and for the beta decay Q-value: $Q_{{\beta }^{-}}({}^6\mathrm{He})=3.71\pm 0.65$ MeV. We conclude that our error bars can potentially be reduced further by extending the model space used by JupiterNCSM.

    ↳ nucl-thnucl-exphysics.data-anPRC(2022)·31 citations
11. 11*

    A new approach to semi-inclusive deep-inelastic scattering with QED and QCD factorization

    Tianbo Liu🇨🇳 · W. Melnitchouk🇺🇸 · Jian-Wei Qiu🇺🇸 · N. Sato🇺🇸

    We present the details of a new factorized approach to semi-inclusive deep-inelastic scattering which treats QED and QCD radiation on equal footing, and provides a systematically improvable approximation to the extraction of transverse momentum dependent parton distributions. We demonstrate how the QED contributions can be well approximated by collinear factorization, and illustrate the application of the factorized approach to QED radiation in inclusive scattering. For semi-inclusive processes, we show how radiation effects prevent a well-defined "photon-nucleon" frame, forcing one to use a two-step process to account for the radiation. We illustrate the utility of the new method by explicit application to the spin-dependent Sivers and Collins asymmetries.

    ↳ hep-phhep-exnucl-exnucl-thJHEP(2021)·30 citations
12. 12*

    Ratios of jet and hadron spectra at LHC energies: measuring high-$p_T$ suppression without a $pp$ reference

    Jasmine Brewer🇨🇭 · Alexander Huss🇨🇭 · Aleksas Mazeliauskas🇨🇭 · Wilke van der Schee🇨🇭

    We analyze the reliability of several techniques for computing jet and hadron spectra at different collision energies. This is relevant for discovering energy loss in the upcoming oxygen-oxygen (OO) run at the LHC, for which a reference pp run is currently not planned. For hadrons and jets we compute the ratio of spectra between different pp collision energies in perturbative QCD, which can be used to construct a reference spectrum. Alternatively, it can be interpolated from measured spectra at nearby energies. We estimate the precision of both strategies for the spectra ratio relevant to the oxygen run, and conclude that the central values agree to 4% accuracy for hadrons and 2% accuracy for jets. Finally we propose taking the ratio of OO and pp spectra at different collision energies, which cleanly separates the experimental measurement and theoretical computation.

    ↳ hep-phnucl-exnucl-thPRD(2022)·16 citations
13. 13*

    Machine Learning Application for $\mathbf{\Lambda }$ Hyperon Reconstruction in CBM at FAIR

    Shahid Khan🇩🇪 · Viktor Klochkov🇩🇪 · Olha Lavoryk🇺🇦 · Oleksii Lubynets🇩🇪 · Ali Imdad Khan🇩🇪 · Andrea Dubla🇩🇪 · Ilya Selyuzhenkov🇷🇺

    The Compressed Baryonic Matter experiment at FAIR will investigate the QCD phase diagram in the region of high net-baryon densities. Enhanced production of strange baryons, such as the most abundantly produced $\Lambda$ hyperons, can signal transition to a new phase of the QCD matter. In this work, the CBM performance for reconstruction of the $\Lambda$ hyperon via its decay to proton and ${\pi }^{-}$ is presented. Decay topology reconstruction is implemented in the Particle-Finder Simple (PFSimple) package with Machine Learning algorithms providing efficient selection of the decays and high signal to background ratio.

    ↳ physics.ins-detnucl-exEPJ Web Conf.(2022)·4 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.