Ekaterina Kriukova

A bstract: We study the production of hypothetical vector portal mediators, dark photons γ ^′ , with masses in the range 0.4–3.5 GeV in the negatively charged pion-proton collisions π ⁻ p → γ ^′ X via inelastic pion bremsstrahlung and QCD Drell-Yan-like process. In both cases we estimate the value of total dark photon production cross section and obtain the energy distribution for dark photons that could be produced in the NA64h experiment. We also present the mean energies of dark photons produced in the same way by the secondary pions with momenta typical for T2K, DUNE and SHiP experiments.

We study the production of vector portal mediators, dark photons, with masses in the range 0.4–1.8 GeV in proton-proton collisions via the process of inelastic proton bremsstrahlung. In contrast to previous studies, we take into account the contribution of Pauli electromagnetic form factor to differential cross section and introduce two new splitting functions of the proton. We show that their contributions can become leading in the mass region 0.9–1.8 GeV and present the updated estimate for the sensitivity of the future SHiP experiment to visible decays of dark photons.

We study the production of hypothetical vector particles, dark photons γ′, with masses in the range 0.4–1.8 GeV via inelastic proton bremsstrahlung. We further develop the approach of refs. [1–3], where for the first time we considered the contributions to the cross section that are associated with the Pauli form factor in ppγ′ vertex and obtained new splitting functions. We demonstrate numerically the importance of these corrections to full inelastic proton bremsstrahlung cross section and refine the sensitivity of the ongoing and future fixed-target experiments T2K, DUNE and SHiP to the parameters of dark photon model. A dedicated experiment on measurements of the proton electromagnetic form factors in the time-like region below the proton-antiproton threshold, like those suggested in PANDA at FAIR, would help to obtain the robust predictions for the dark photon production by a proton beam at fixed target.

We study the production of vector portal mediators, dark photons, with masses in the range 0.4--1.8\,GeV in proton-proton collisions via the process of inelastic proton bremsstrahlung. In contrast to previous studies, we take into account the contribution of Pauli electromagnetic form factor to differential cross section and introduce two new splitting functions of the proton. We show that their contributions can become leading in the mass region 0.9--1.8\,GeV and present the updated estimate for the sensitivity of the future SHiP experiment to visible decays of dark photons.

We study the production of dark photons with masses in range 0.4-1.5\,GeV in elastic proton bremsstrahlung. In contrast to the known approaches to calculating the bremsstrahlung cross section, we consider the non-zero momentum transfer between protons. The numerical estimates show that the refined result agrees well with the generalized Weizsacker-Williams approximation, although it significantly differs from the result obtained by Blumlein and Brunner \cite{Blumlein:2013cua} which is widely used in proton beam-dump phenomenology.

We study the production of dark photons with masses in range 0.4-1.5\,GeV in elastic proton bremsstrahlung. In contrast to the known approaches to calculating the bremsstrahlung cross section, we consider the non-zero momentum transfer between protons. The numerical estimates show that the refined result agrees well with the generalized Weizsacker-Williams approximation, although it significantly differs from the result obtained by Blumlein and Brunner which is widely used in proton beam-dump phenomenology.

We explore hypothetical vector particles, dark photons γ′, which mix with the Standard Model photons and thus mediate interactions with charged particles into the hidden sector. We study the elastic proton bremsstrahlung of dark photons with masses 0.4–1.8 GeV, relevant for direct searches with proton accelerators. A key feature of our calculation is that it explicitly considers the non-zero momentum transfer between protons in the process pp → ppγ′. We compare the obtained differential and full bremsstrahlung cross sections with the results of other authors. Our calculation agrees well (up to 3–9% corrections) with the Weizsacker-Williams approximation that confirms its applicability for proton beams. Then we refine predictions for the dark photon production with proton beams of energy 30 GeV, 70 GeV, 120 GeV and 400 GeV relevant for past, present and future experiments considered in literature.

The contribution of light sgoldstinos with masses about 100 GeV to the effective potential at a finite temperature is considered in the model with