Tue·Apr 26, 2022Tuesday·April 26, 2022

1. 01*

   On the randomness and correlation in the trajectories of alpha particle emitted from ${}^{241}$Am: Statistical inference based on information entropy

   M. El Ghazaly🇪🇬 · Elsayed k. Elmaghraby🇪🇬 · A. Al-Sayed🇪🇬 · Amal Mohamed🇪🇬 · Mahmoud S. Dawood🇪🇬

   Most particle detectors are based on the hypothesis that particles are emitted randomly upon nuclear decay. In the present work, we tested the hypothesis of the existence of correlation in the random trajectories of alpha particles emitted from ${}^{241}$Am source and the null hypothesis of random trajectories. The trajectories were clued through the registration of track in a solid-state nuclear track detector. The experimental parameters were optimized to identify the possible sources of correlation in the track registration and the detector conditions upon exposure and etching to avoid misleading results. The optimization included authentication of linearity in registration efficiency with exposure time to prevent coalescence of registered tracks. The statistical inference processes were based upon adaptive quadrates analysis of the spatial data, and entropy and divergence analysis of the quadrate data together with the null hypothesis of Poisson distribution of random trajectories. The clustering and dispersion analysis were performed with central deviation tendency, empirical K-function, radial distribution analysis, and proximity Analysis. Results showed a pattern of gained information within the registered tracks that may be attributed to the alteration in the alpha particles' trajectories induced by the strong electric field due to atoms in the source compound and encapsulation film.

   nucl-exhep-phSci.Rep.(2022)·0 citations
2. 02*

   Two-particle correlations on transverse rapidity in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV at STAR

   STAR Collaboration: M. S. Abdallah · B. E. Aboona · J. Adam · L. Adamczyk · J. R. Adams · J. K. Adkins · G. Agakishiev · I. Aggarwal · M. M. Aggarwal · Z. Ahammed · A. Aitbaev · I. Alekseev and 382 other authors

   Two-particle correlation measurements projected onto two-dimensional, transverse rapidity coordinates ($y_{T1},y_{T2}$), allow access to dynamical properties of the QCD medium produced in relativistic heavy-ion collisions that angular correlation measurements are not sensitive to. We report non-identified charged-particle correlations for Au + Au minimum-bias collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV taken by the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). Correlations are presented as 2D functions of transverse rapidity for like-sign, unlike-sign and all charged-particle pairs, as well as for particle pairs whose relative azimuthal angles lie on the near-side, the away-side, or at all relative azimuth. The correlations are constructed using charged particles with transverse momentum $p_T\ge 0.15$ GeV/$c$, pseudorapidity from $-$1 to 1, and azimuthal angles from $-\pi$ to $\pi$. The significant correlation structures that are observed evolve smoothly with collision centrality. The major correlation features include a saddle shape plus a broad peak with maximum near $y_T\approx 3$, corresponding to $p_T\approx$ 1.5 GeV/$c$. The broad peak is observed in both like- and unlike-sign charge combinations and in near- and away-side relative azimuthal angles. The all-charge, all-azimuth correlation measurements are compared with the theoretical predictions of {\sc hijing} and {\sc epos}. The results indicate that the correlations for peripheral to mid-central collisions can be approximately described as a superposition of nucleon + nucleon collisions with minimal effects from the QCD medium. Strong medium effects are indicated in mid- to most-central collisions.

   nucl-exPRC(2022)·3 citations
3. 03*

   Total absorption $\gamma$-ray spectroscopy of the $\beta$ decays of ${}^{96\text{gs,m}}$Y

   V. Guadilla🇫🇷 · L. Le Meur🇫🇷 · M. Fallot🇫🇷 · J. A. Briz🇫🇷 · M. Estienne🇫🇷 · L. Giot🇫🇷 · A. Porta🇫🇷 · A. Cucoanes🇫🇷 · T. Shiba🇫🇷 · A. -A. Zakari-Issoufou🇫🇷 · A. Algora🇪🇸 · J. L. Tain🇪🇸 and 33 other authors

   The $\beta$ decays of the ground state (gs) and isomeric state (m) of ${}^{96}$Y have been studied with the total absorption $\gamma$-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility. The separation of the 8${}^{+}$ isomeric state from the 0${}^{-}$ ground state was achieved thanks to the purification capabilities of the JYFLTRAP double Penning trap system. The $\beta$-intensity distributions of both decays have been independently determined. In the analyses the de-excitation of the 1581.6 keV level in ${}^{96}$Zr, in which conversion electron emission competes with pair production, has been carefully considered and found to have significant impact on the $\beta$-detector efficiency, influencing the $\beta$-intensity distribution obtained. Our results for ${}^{96\text{gs}}$Y (0${}^{+}$) confirm the large ground state to ground state $\beta$-intensity probability, although a slightly larger value than reported in previous studies was obtained, amounting to $96.6_{-2.1}^{+0.3}\%$ of the total $\beta$ intensity. Given that the decay of ${}^{96\text{gs}}$Y is the second most important contributor to the reactor antineutrino spectrum between 5 and 7 MeV, the impact of the present results on reactor antineutrino summation calculations has been evaluated. In the decay of ${}^{96\text{m}}$Y (8${}^{+}$), previously undetected $\beta$ intensity in transitions to states above 6 MeV has been observed. This shows the importance of total absorption $\gamma$-ray spectroscopy measurements of $\beta$ decays with highly fragmented de-excitation patterns. ${}^{96\text{m}}$Y (8${}^{+}$) is a major contributor to reactor decay heat in uranium-plutonium and thorium-uranium fuels around 10 s after fission pulses, and the newly measured average $\beta$ and $\gamma$ energies differ significantly from the previous values in evaluated databases (...)

   nucl-exPRC(2022)·15 citations
4. 04*

   Gamma-ray emission in proton-induced nuclear reactions on natC and Mylar targets over the incident energy range of Ep = 30-200 MeV. Astrophysical implications

   Y.Rahma🇩🇿 · S. Ouichaoui🇩🇿 · J. Kiener🇫🇷 · E. A. Lawrie🇿🇦 · J. J. Lawrie🇿🇦 · V. Tatischeff🇫🇷 · A. Belhout🇩🇿 · D. Moussa🇩🇿 · W. Yahia-Cherif🇩🇿 · H. Benhabiles-Mezhoud🇩🇿 · T. D. Bucher🇿🇦 · T.R.S. Dinoko🇿🇦 and 28 other authors

   We have measured the gamma-ray line production cross sections in proton-induced nuclear reactions on various target nuclei abundant in astrophysical sites over the incident energy range of Ep = 30 - 200 MeV. We carried out experimental campaigns in joint collaboration at the K = 200 cyclotron of iThemba LABS using a high-energy resolution, high-efficiency detection array composed of 8 Compton-suppressed clover detectors comprising 32 HP-Ge crystals for recording the gamma-ray spectra. In the current paper, we focus on de-excitation lines produced in proton irradiations of natC and Mylar targets. In particular, on the prominent 4.439 and 6.129 MeV lines of ${}^{12}$C and ${}^{16}$O which are among the strongest lines emitted in solar flares and in interactions of low-energy cosmic rays with the gas and dust of the inner galaxy. We report new gamma-ray production experimental cross section data for ten nuclear lines that we compare to previous low-energy data sets from the literature, to the predictions of the TALYS code of modern nuclear reactions and to a semi-empirical compilation. In first approach, performing calculations with default input parameters of TALYS we observed substantial deviations between the predicted cross sections and experimental data. Then, using modified optical model potential and nuclear level deformation parameters as input data we generated theoretical excitation functions for the above two main lines fully consistent with experimental data. In contrast, the experimental data sets for the other eight analyzed lines from the two proton-irradiated targets exhibit significant deviations with the predicted cross section values. We also report line-shape experimental data for the line complex observed at $E_g$ = 4.44 MeV in irradiations of the two targets. Finally, we emphasize the astrophysical implications of our results.

   nucl-exNPA(2023)·4 citations
5. 05*

   Dielectron production at midrapidity at low transverse momentum in peripheral and semi-peripheral Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV

   Alice Collaboration

   The first measurement of the ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ pair production at low lepton pair transverse momentum ($p_{\mathrm{T},\mathrm{ee}}$) and low invariant mass ($m_{\mathrm{ee}}$) in non-central Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV at the LHC is presented. The dielectron production is studied with the ALICE detector at midrapidity ($|{\eta }_{\mathrm{e}}|<0.8$) as a function of invariant mass ($0.4\le m_{\mathrm{ee}}<2.7$ GeV/$c^2$) in the 50$-$70% and 70$-$90% centrality classes for $p_{\mathrm{T},\mathrm{ee}}<0.1$ GeV/$c$, and as a function of $p_{\mathrm{T},\mathrm{ee}}$ in three $m_{\mathrm{ee}}$ intervals in the most peripheral Pb$-$Pb collisions. Below a $p_{\mathrm{T},\mathrm{ee}}$ of 0.1 GeV/$c$, a clear excess of ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ pairs is found compared to the expectations from known hadronic sources and predictions of thermal radiation from the medium. The $m_{\mathrm{ee}}$ excess spectra are reproduced, within uncertainties, by different predictions of the photon$-$photon production of dielectrons, where the photons originate from the extremely strong electromagnetic fields generated by the highly Lorentz-contracted Pb nuclei. Lowest-order quantum electrodynamic (QED) calculations, as well as a model that takes into account the impact-parameter dependence of the average transverse momentum of the photons, also provide a good description of the $p_{\mathrm{T},\mathrm{ee}}$ spectra. The measured $\sqrt{⟨p_{\mathrm{T},\mathrm{ee}}^2⟩}$ of the excess $p_{\mathrm{T},\mathrm{ee}}$ spectrum in peripheral Pb$-$Pb collisions is found to be comparable to the values observed previously at RHIC in a similar phase-space region.

   nucl-exhep-exJHEP(2023)·21 citations
6. 06*

   Glueball-meson molecules

   Alexey A Petrov🇺🇸

   Experimental searches for pure glueball states have proven challenging and so far yielded no results. This is believed to occur because glueballs mix with the ordinary $q\bar{q}$ states with the same quantum numbers. We will discuss an alternative mechanism, the formation of the glueball-meson molecular states. We will argue that the wave functions of already observed excited meson states may contain a significant part due to such molecular states. We discuss the phenomenology of glueball-meson molecules and comment on a possible charmless component of the $XYZ$ states.

   ↳ hep-phhep-exnucl-exPLB(2023)·11 citations
7. 07*

   Quark Nuclear Physics with Heavy Quarks

   Nora Brambilla🇩🇪

   Heavy quarks have been instrumental for progress in our exploration of strong interactions. Quarkonium in particular, a heavy quark-antiquark nonrelativistic bound state, has been at the root of several revolutions. Quarkonium is endowed with a pattern of separated energy scales qualifying it as special probe of complex environments. Its multiscale nature has made a description in Quantum Field Theory particularly difficult up to the advent of Nonrelativistic Effective Field Theories. We will focus on systems made by two or more heavy quarks. After considering some historical approaches based on the potential models and the Wilson loop approach, we will introduce the contemporary nonrelativistic effective field theory descriptions, in particular potential Nonrelativistic QCD which entails the Schoedinger equation as zero order problem, define the potentials as matching coefficients and allows systematic calculations of the physical properties. The effective field theory allows us to explore quarkonium properties in the realm of QCD. In particular it allows us to make calculations with unprecedented precision when high order perturbative calculations are possible and to systematically factorize short from long range contributions where observables are sensitive to the nonperturbative dynamics of QCD. Such effective field theory treatment can be extended at finite temperature and in presence of gluonic and light quark excitations. We will show that in this novel theoretical framework, quarkonium can play a crucial role for a number of problems at the frontier of our research, from the investigation of the confinement dynamics in strong interactions to the study of deconfinement and the phase diagram of nuclear matter, to the precise determination of Standard Model parameters up to the emergence of exotics X Y Z states of an unprecedented nature.

   ↳ hep-phhep-exhep-latnucl-ex+13 citations
8. 08*

   Theory of QED radiative corrections to neutrino scattering at accelerator energies

   Oleksandr Tomalak🇺🇸 · Qing Chen🇺🇸 · Richard J Hill🇺🇸 · Kevin S McFarland🇺🇸 · Clarence Wret🇺🇸

   Control over quantum electrodynamics (QED) radiative corrections is critical for precise determination of neutrino oscillation probabilities from observed (anti)neutrino detection rates. It is particularly important to understand any difference between such corrections for different flavors of (anti)neutrinos in charged-current interactions. We provide theoretical foundations for calculating these corrections. Using effective field theory, the corrections are shown to factorize into soft, collinear, and hard functions. The soft and collinear functions contain large logarithms in perturbation theory but are computable from QED. The hard function parametrizes hadronic structure but is free from large logarithms. Using a simple model for the hard function, we investigate the numerical impact of QED corrections in charged-current (anti)neutrino-nucleon elastic cross sections and cross-section ratios at GeV energies. We consider the implications of mass singularity theorems that govern the lepton-mass dependence of cross sections for sufficiently inclusive observables and demonstrate the cancellation of leading hadronic and nuclear corrections in phenomenologically relevant observables.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2022)·41 citations
9. 09*

   Upgrade of ASACUSA's Antihydrogen Detector

   V. Kraxberger🇦🇹 · C. Amsler🇦🇹 · H. Breuker🇯🇵 · S. Chesnevskaya🇦🇹 · G. Costantini🇮🇹 · R. Ferragut🇮🇹 · M. Giammarchi🇮🇹 · A. Gligorova🇦🇹 · G. Gosta🇮🇹 · H. Higaki🇯🇵 · E. D. Hunter🇦🇹 · C. Killian🇦🇹 and 26 other authors

   The goal of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) CUSP experiment at CERN's Antiproton Decelerator is to measure the ground state hyperfine splitting of antihydrogen in order to test whether CPT invariance is broken. The ASACUSA hodoscope is a detector consisting of two layers of 32 plastic scintillator bars individually read out by two serially connected silicon photo multipliers (SiPMs) on each end. Two additional layers for position resolution along the beam axis were scintillator fibres, which will now be replaced by scintillating tiles placed onto the existing bars and also read out by SiPMs. If the antiproton of antihydrogen annihilates in the center of the hodoscope, particles (mostly pions) are produced and travel through the various layers of the detector and produce signals. The hodoscope was successfully used during the last data taking period at CERN. The necessary time resolution to discriminate between particles travelling through the detector from outside and particles produced in the center of the detector was achieved by the use of waveform digitisers and software constant fraction discrimination. The disadvantage of this readout scheme was the slow readout speed, which was improved by two orders of magnitude. This was done by omitting the digitisers and replacing them with TDCs reading out the digital time-over-threshold (ToT) signal using leading edge discrimination.

   ↳ physics.ins-detnucl-exNucl.Instrum.Meth.A(2023)·6 citations
10. 10*

    Pairing enhancement in a two-neutron transfer process through the continuum

    Gagandeep Singh🇪🇸 · Lorenzo Fortunato🇮🇹 · Andrea Vitturi🇮🇹

    Enhancement, due to constructive interference through the many possible reaction channels, occurs in two-neutron transfer reactions from a bound system $A$ to a weakly-bound system ($A$+2), whenever the intermediate system is unbound and consists of a continuum with a resonant state. We elucidate this phenomenon in the case of ${}^6$He, modeled as two neutrons in the orbitals of an intermediate ${}^5$He nucleus, comparing the realistic case of an unbound ($A$+1) system with an artificially bound case. A properly modeled continuum in these calculations is found to be crucial and leads to significant enhancement due to pairing correlations.

    ↳ nucl-thnucl-exPLB(2022)·8 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.