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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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  • Revisiting the Dirac nature of neutrinos in the light of Δ(27) and cyclic symmetries
    Amid the uncertainty regarding the fundamental nature of neutrinos, we adhere to the Dirac description, and construct a model in the framework of Δ(27) symmetry. The model successfully accounts for the hierarchical patterns of both charged lepton and neutrino masses. The neutrino mass matrix exhibits four texture zeroes, and the associated mixing scheme aligns with the experimental data, notably controlled by a single parameter.

  • Effects of two-body currents in the one-particle one-hole electromagnetic responses within a relativistic model
    Longitudinal (RL) and transverse (RT) responses from inclusive electron scattering from 12C and 40Ca nuclei are computed within a fully relativistic model, and one- and two-body current operators leading to a final one-particle one-hole state. We find that the two-body contributions have no effect on RL but they increase RT by up to 30%, depending on the energy and momentum transfer. Inclusive cross sections have also been computed, obtaining an increase which depends on the degree of transversity of each kinematic. The comparison with carbon data is good for the responses and the cross sections. In the case of calcium, while the model compares well with the cross section data, the agreement with the responses is generally poor. However, the inconsistencies between different data sets for the separate responses in this nucleus indicate that uncertainties in the responses are largely underestimated in the data. Our calculation is fully relativistic, does not require a factorized model and includes a full quantum mechanical description of both the initial and final nucleon states. We also show that incorporating the distortion of the nucleons while making the initial and final states orthogonal is essential to reproduce the shape and magnitude of the cross section data and carbon responses. The good agreement with the electron scattering experimental data supports the use of this approach to describe the analogous neutrino-induced scattering reaction.

  • CPT-Odd effects on the electromagnetic properties of charged leptons in the standard model extension
    The impact of the CPT-Odd electroweak gauge sector of the Standard Model Extension on the electromagnetic properties of charged leptons is studied. This gauge sector is characterized by the and Lorentz violation (LV) coefficients, which have positive mass dimension because they are associated with a UY(1)-invariant and with an SUL(2)-invariant dimension-three operators, respectively. They belong to the category of relevant interactions, which can have strong effects on low-energy observables. We present a comprehensive study on the impact of this sector on the magnetic dipole moment (MDM) and the electric dipole moment (EDM) of charged leptons, up to second order in these LV coefficients, both at the tree and one-loop levels. We find that the O(ki) contributions at the tree and one-loop levels depend on energy, while ones at the tree-level do not. As for one-loop effects, there are both energy-dependent and energy-independent contributions, but we have focused only on those of the latter type. We find that the EDM only is generated at O(ki) up to one-loop level, whereas the MDM receives contributions from both O(ki) and at both tree and one-loop levels. The contributions of O(ki) to the MDM are found to be suppressed relative to the corresponding contributions to the EDM by approximately three orders of magnitude. Using a recent experimental limit on the electron EDM the bound was obtained. As far as the contributions of are concerned, we find that the tree-level contributions are suppressed with respect to the one-loop ones by at least a factor of . We find that the contribution to the electron MDM is by far the dominant one, as it can be up to four and seven orders of magnitude greater than those of the muon and tau, respectively. The Lorentz coefficient of the Carroll–Field–Jackiw’s QED is given by a linear combination of the and vectors. Assuming that and taking , which implies that and are collinear, we obtain an upper bound of . The fact that is an observer Lorentz invariant allows us to introduce a new-physics scale through , for which we obtain the upper limit ΛCPT < 2.08 × 10−5me. The physical implications derived from the fact that the LV coefficients have positive mass units are discussed.

  • Single production of singlet vector-like leptons at the ILC
    Vector-like leptons (VLLs), as one kind of interesting new particle, can produce a rich phenomenology in low- and high-energy experiments. In the framework of the singlet vector-like lepton with scalar (VLS) model, we investigate the discovery potential of the VLL via its single production at the International Linear Collider (ILC) with a center of mass energy 1 TeV and an integrated luminosity = 1 ab−1, taking into account the appropriate polarization. For the signal and standard model (SM) background analysis, we have considered two kinds of decay channels for the W boson, i.e. pure leptonic and fully hadronic decay channels. Our analytic results show that the parameter space MF ∈ [300, 675] GeV and κ ∈ [0.0294, 0.1] might be detected by the proposed ILC for a pure leptonic decay channel. For a fully hadronic decay channel, a larger detection region of the parameter space isderived as MF ∈ [300, 700] GeV and κ ∈ [0.0264, 0.0941].

  • Probe of a Randall–Sundrum-like model from muon pair production at a high-energy muon collider
    We have examined a production of a muon pair through vector boson fusion and direct μ+μ− annihilation at future high-energy muon colliders in the framework of the Randall–Sundrum-like model with a small curvature of spacetime. The collision energies of 3 TeV, 14 TeV and 100 TeV are addressed. Differential and total cross sections are both calculated, and exclusion bounds on a five-dimensional gravity scale are obtained depending on collision energy and the integrated luminosity of the muon colliders. For comparison, the effects of extra dimensions in the Arkani-Hamed–Dimopoulos–Dvali model at the muon collider are studied.