Newsfeeds

Journal of Physics G: Nuclear and Particle Physics - latest papers

Latest articles for Journal of Physics G: Nuclear and Particle Physics

IOPscience

  • The HIBEAM instrument at the European spallation source
    The European spallation source (ESS) will be the world’s brightest neutron source and will open a new intensity frontier in particle physics. The HIBEAM collaboration aims to exploit the unique potential of the ESS with a dedicated ESS instrument for particle physics which offers world-leading capability in a number of areas. The HIBEAM program includes the first search in thirty years for free neutrons converting to antineutrons and searches for sterile neutrons, ultralight axion dark matter and nonzero neutron electric charge. This paper outlines the capabilities, design, infrastructure, and scientific potential of the HIBEAM program, including its dedicated beamline, neutron optical system, magnetic shielding and control, and detectors for neutrons and antineutrons. Additionally, we discuss the long-term scientific exploitation of HIBEAM, which may include measurements of the neutron electric dipole moment and precision studies of neutron decays.

  • Impact of new particles on the ratio of electromagnetic form factors
    We consider the electromagnetic form factors ratios in the Rosenbluth and polarization methods. We explore what impact adding new particles as mediators in electron-proton scattering has on these ratios. We show that such new particles can compensate for the difference between the two methods and potentially solve this paradox. Consequently, we find some bounds on the scalar coupling as αsc ∼ 10−5 for msc ∼ 5 MeV–2 GeV and αsc ∼ 10−4 − 10−3 for msc ∼ 2–10 GeV. Meanwhile, the vector coupling is bounded as αv ∼ 10−5 for mv ∼ 5 MeV–1.1 GeV and αv ∼ 10−4 − 10−3 for mv ∼ 1.2–10 GeV. These constraints are in complete agreement with those found in other independent terrestrial experiments.

  • Neutrinoless double beta decay sensitivity of the XLZD rare event observatory
    The XLZD collaboration is developing a two-phase xenon time projection chamber with an active mass of 60–80 t capable of probing the remaining weakly interacting massive particle-nucleon interaction parameter space down to the so-called neutrino fog. In this work we show that, based on the performance of currently operating detectors using the same technology and a realistic reduction of radioactivity in detector materials, such an experiment will also be able to competitively search for neutrinoless double beta decay in 136Xe using a natural-abundance xenon target. XLZD can reach a 3σ discovery potential half-life of 5.7 × 1027 years (and a 90% CL exclusion of 1.3 × 1028 years) with 10 years of data taking, corresponding to a Majorana mass range of 7.3–31.3 meV (4.8–20.5 meV). XLZD will thus exclude the inverted neutrino mass ordering parameter space and will start to probe the normal ordering region for most of the nuclear matrix elements commonly considered by the community.

  • Theoretical tools for neutrino scattering: interplay between lattice QCD, EFTs, nuclear physics, phenomenology, and neutrino event generators
    Maximizing the discovery potential of increasingly precise neutrino experiments will require an improved theoretical understanding of neutrino-nucleus cross sections over a wide range of energies. Low-energy interactions are needed to reconstruct the energies of astrophysical neutrinos from supernovae bursts and search for new physics using increasingly precise measurement of coherent elastic neutrino scattering. Higher-energy interactions involve a variety of reaction mechanisms including quasi-elastic scattering, resonance production, and deep inelastic scattering that must all be included to reliably predict cross sections for energies relevant to DUNE and other accelerator neutrino experiments. Refined nuclear interaction models in these energy regimes will also be valuable for other applications, such as measurements of reactor, solar, and atmospheric neutrinos. This manuscript discusses the theoretical status, challenges, required resources, and path forward for achieving precise predictions of neutrino-nucleus scattering and emphasizes the need for a coordinated theoretical effort involved lattice QCD, nuclear effective theories, phenomenological models of the transition region, and event generators.

  • Physical interpretation of the 2s excitation of the nucleon
    Lattice QCD calculations of the 2s radial excitation of the nucleon place the state at an energy of approximately 1.9 GeV, raising the possibility that it is associated with the N1/2+(1880) and N1/2+(1710) resonances through mixing with two-particle meson-baryon states. The discovery of the N1/2+(1880) resonance in pion photoproduction but not in πN scattering and the small width of the N1/2+(1710) resonance suggest that a state associated with these resonances would be insensitive to the manner in which pions are permitted to dress it. To explore this possibility, we examine the spectrum of nucleon radial excitations in both 2 + 1 flavour QCD and in simulations where the coupling to meson-baryon states is significantly modified through quenching. We find the energy of the 2s radial excitation to be insensitive to this modification for quark masses close to the physical point. This invariance provides further evidence that the 2s radial excitation of the nucleon is associated with the N1/2+(1880) and N1/2+(1710) resonances.