Impact of a complex scalar spectator field on baryon asymmetry within spontaneous baryogenesis
Dubbini M. Luongo O. Muccino M.
February 2026Elsevier B.V.
Physics of the Dark Universe
2026#51
We extend the framework of spontaneous baryogenesis by investigating the generation of baryon asymmetry when the inflaton, θ , is minimally coupled with a complex spectator scalar field ϕ , as θ 2| ϕ |2. We also consider ϕ non-minimally coupled with the Ricci scalar curvature R , since in previous works a Yukawa-like interaction with gravity has already been shown to provide a significant contribution to the production of baryon asymmetry. We do not consider further interactions of the spectator field with the fermions of the Standard Model, considering it de facto as a dark scalar field. In evaluating the violation of the baryon-number conservation during the reheating epoch, in a perfectly homogeneous and isotropic universe, we follow a semiclassical approach, where θ, ϕ and gravity are considered as classical fields, whereas the fermions are quantized. We solve the equations of motion for the inflaton and spectator fields, respectively at first and zero-order in perturbation theory, neglecting at first stage the expansion of the universe. Afterwards, we quantify how the spectator field modifies the inflationary dynamics and thus find the baryon asymmetry produced via the inflaton decays into fermion-antifermion pairs by computing the corresponding decay amplitudes. In particular, the coupling term θ 2| ϕ |2 acts as an additional contribution to the square effective mass of the inflaton, increasing its decay amplitudes into fermion-antifermion pairs. Consequently, we expect this to affect the production of the net baryon asymmetry. We therefore obtain small first order correction to standard spontaneous baryogenesis and finally discuss the mass-mixing between fermions. Accordingly, the effects of considering the universe expansion are accounted, showing when the coupling between ϕ and R becomes noticeable in altering the overall baryon asymmetry. Copyright
Baryogenesis , Baryon asymmetry , Spectator fields
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Universit‘a di Camerino, Via Madonna delle Carceri, Camerino, 62032, Italy
Department of Nanoscale Science and Engineering, University at Albany-SUNY, Albany, 12222, NY, United States
Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Brera, Milano, 20121, Italy
Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Perugia, Perugia, 06123, Italy
Al-Farabi, Kazakh National University, Al-Farabi av. 71, Almaty, 050040, Kazakhstan
ICRANet, Piazza della Repubblica 10, Pescara, 65122, Italy
Universit‘a di Camerino
Department of Nanoscale Science and Engineering
Istituto Nazionale di Astrofisica (INAF)
Istituto Nazionale di Fisica Nucleare (INFN)
Al-Farabi
ICRANet
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026