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

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

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  • Probing anomalous Z γ γ γ couplings at a future muon collider
    The sensitivity to anomalous quartic gauge couplings (AQGCs) of the γγγZ interaction is studied in the μ+μ− → μ+γγμ− scattering at a future muon collider with unpolarized beams. The anomalous γγγZ vertex is described by two couplings, ζ1 and ζ2. The differential and total cross sections are calculated for the center-of-mass energies of 3 TeV, 14 TeV, and 100 TeV. For these values of the collision energy the 95% C.L. exclusion regions for AQGCs are obtained depending on the systematic error. In particular, for the 14 TeV muon collider with the integrated luminosity L = 20 ab−1 the best sensitivities are derived to be ζ1 = 3.1 × 10−5 TeV−4 and ζ2 = 6.5 ×10−5 TeV−4. These constraints are three orders of magnitude stronger than the bounds obtained for the 27 TeV HE-LHC with L = 15 ab−1. At the 100 TeV muon collider with L = 1000 ab−1 AQGCs can be probed up to 1.64 × 10−8 TeV−4 and 3.4 × 10−8 TeV−4 for ζ1 and ζ2, respectively. The partial-wave unitarity constraints on couplings ζ1, ζ2 are evaluated. It is shown that the unitarity is not violated in the region of the AQGCs examined in the present paper.

  • Flattenicity as centrality estimator in p–Pb collisions simulated with PYTHIA/Angantyr
    In this paper, a centrality estimator based on flattenicity is studied using PYTHIA 8.312 Angantyr, whose existing implementation is enough to study the particle production in p–Pb collisions in the absence of medium effects. The number of binary nucleon–nucleon collisions for different centrality estimators are compared. The studies include forward multiplicity, forward flattenicity and midrapidity multiplicity. The results using flattenicity show the smallest deviations (<8%) with respect to the results which use impact parameter for centrality classes. On the other hand, the multiplicity-based estimators exhibit huge deviations (up to a factor 2) with respect to the results using impact parameter. The particle ratios (proton-to-pion and kaon-to-pion ratios) and nuclear modification factors as a function of pT are also studied for the different centrality estimators. The studies presented here are relevant to help in the investigation of the plethora of effects, which have been reported by experiments at the Large Hadron Collider.

  • Theoretical analysis and predictions for the two-neutrino double electron capture of 124Xe
    We provide a complete theoretical description of the two-neutrino electron capture in 124Xe, improving both the nuclear and the atomic structure calculations. We improve the general formalism through the use of the Taylor expansion method, leading to higher-order terms in the decay rate of the process. The nuclear part is treated with pn-QRPA and interacting shell model (ISM) methods. The nuclear matrix elements (NMEs) are calculated with the pn-QRPA method with isospin restoration by fixing the input parameters so that the experimental decay rate is reproduced, resulting in values significantly lower than in previous calculations. The validity of the pn-QRPA NMEs is tested by showing their values to be comparable with the ones for double-beta decay with the emission of two antineutrinos of 128,130Te, which have similar pairing features. Within the ISM, we reproduce the total experimental half-life within a factor of two and predict the capture fraction to the KK channel of about 74%. We also predict the capture fractions to other decay channels and show that for the cumulative decay to the KL1–KO1 channels, a capture fraction of about 24% could be observed experimentally. On the atomic side, calculations are improved by accounting for the Pauli blocking of the decay of innermost nucleon states and by considering all s-wave electrons available for capture, expanding beyond the K and L1 orbitals considered in previous studies. We also provide improved atomic relaxation energies of the final atomic states of 124Te, which may be used as input for background modeling in liquid Xenon experiments.

  • Application of the surrogate reaction ratio method to measure the (n, xp) cross sections for nuclei with A ≈ 50–60
    We explore the applicability of the surrogate reaction (SR) ratio method for determining (n, xp) cross sections, where an incoming neutron induces the emission of at least one proton from a nuclear target with a mass range of A ≈ 50–60. These cross sections are relevant for advanced nuclear technologies. Our findings reveal that, under specific conditions, the SR ratio method can yield reliable (n, xp) cross sections, similar to its success in determining (n, f) cross sections in actinides. However, not all SR pairs meet these conditions across the entire excitation energy range, necessitating careful application of the SR ratio method for determining (n, xp) cross sections.

  • Magnetic Monopole Phenomenology at Future Hadron Colliders
    In the grand tapestry of Physics, the magnetic monopole (MM) is a holy grail. Therefore, numerous efforts are underway in search of this hypothetical particle at CMS, ATLAS, and MoEDAL experiments of Large Hadron Collider (LHC) by employing different production mechanisms. The cornerstone of our comprehension of monopoles lies in Dirac’s theory which outlines their characteristics and dynamics. Within this theoretical framework, an effective U(1) gauge field theory, derived from conventional models, delineates the interaction between spin magnetically-charged fields and ordinary photons under electric–magnetic dualization. The focus of this paper is the production of MMs through Drell–Yan (DY) and the Photon-Fusion (PF) mechanisms to generate velocity-dependent scalar, fermionic, and vector monopoles of spin angular momentum respectively at LHC. A computational study compares the monopole pair-production cross-sections for both methods at various center-of-mass energies ( ) with different magnetic dipole moments. The comparison of kinematic distributions of monopoles at Parton and reconstructed level are demonstrated for both DY and PF mechanisms. Extracted results showcase how modern machine-learning techniques can be used to study the production of MMs at the future proton-proton particle colliders at 100 TeV. We demonstrate the observability of MMs against the most relevant Standard Model background using multivariate methods such as Boosted Decision Trees, Likelihood, and Multilayer Perceptron. This study compares the performance of these classifiers with traditional cut-based and counting approaches, proving the superiority of our methods.