High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF’s physics potential.

Secret interactions of neutrinos with light new gauge bosons, Z ′ , can lead to a rich phenomenology in a supernova explosion as well as in the early Universe. This interaction can also lead to new decay modes for charged mesons, π + (K + ) → e + νZ ′ , and subsequently to Z ′ → νν. After demonstrating that such an interaction can be accommodated within viable electroweak symmetric models, we study how the near detector (ND) of DUNE can probe this scenario. We also discuss how the DUNE ND can make it possible to reconstruct the flavor structure of the Z ′ coupling to neutrinos. * pouya bakhti@ipm.ir † yasaman@theory.ipm.ac.ir ‡ meshkat.rajaee@ipm.ir

No abstract

Various alleged indirect dark matter search signals, such as the 511 keV line from galaxy center or the PAMELA/AMS02 signal, are often challenged by the absence of corresponding signal from dwarf galaxies and/or by the absence of an impact on CMB through delayed recombination. We propose a novel scenario that can avoid these bounds based on the decay of dark matter, X, to a pair of intermediate particles C andC with a lifetime much greater than the age of universe. The annihilation of these intermediate particles eventually leads to a dark matter signal. The bounds from CMB can be easily avoided by the fact that at the time of recombination, not enough C particles had been accumulated. In order to keep C particles from leaving the galaxy, we assume the particles have a small electric charge so in the galactic disk, the magnetic field keeps the C particles in the vicinity of their production. However, they can escape the dwarf galaxies and the dark matter halo where the magnetic field is weak, leading to null signal from these regions. The small charge can have interesting consequences including a signal in direct dark matter search experiments.

The positron excess observed by PAMELA and then confirmed by AMS-02 has intrigued the particle physics community since 2008. Various dark matter decay and annihilation models have been built to explain the excess. However, the bounds from isotropic gamma ray disfavor the canonical dark matter decay scenario. We propose a solution to this excess based on the decay of dark matter particles into intermediate millicharged particles which can be trapped by the galactic magnetic field. The subsequent decay of the millicharged particles to electron positron in our vicinity can explain the excess. Since these particles diffuse out of the halo before decay, their contribution to the isotropic gamma ray background is expected to be much smaller than that in the canonic dark matter decay scenarios. We show that the model is testable by direct dark matter search experiments. * yasaman@theory.ipm.ac.ir