9th Forward Physics Facility Meeting

Session

Parallel Session: Dark Sectors

5 Mar 2026, 14:30

6/R-012 - conference room (CERN)

1. Right handed neutrino production from $Z^\prime$ interactions in forward search experiments

Arindam Das (Hokkaido University)

05/03/2026, 14:30

We study two general $U(1)$ extensions of the Standard Model (SM) those generate tiny neutrino masses via the seesaw mechanism after general $U(1)$ breaking. These models predict a new neutral gauge boson ($Z'$) and right-handed neutrinos (RHNs), the latter introduced for anomaly cancellation and neutrino mass generation. In both scenarios, left- and right-handed fermions couple differently...

12. Long-lived particle searches Beyond B meson

Wei Su (Sun Yat-sen University)

05/03/2026, 14:50

In this talk I will show our recent study about the LLP searches af FASER. There are two kinds of modes, with the production from the usual mesons, and from the PP collision directly.

For the meson production mode, we study the prospect of detecting light CP-even and CP-odd scalars. We develop the general formalism for the scalar production and decay from mesons at LHC, given modified...

2. Single Photon Signature of Light Long-Lived Particles

Herbi Dreiner

05/03/2026, 15:10

We have investigated single photon signatures of a light long-lived neutralino in supersymmetric models with broken R-parity. We consider the sensitivities at the detectors: ANUBIS, CODEXb, FACET, FASER, MAPP, MATHUSLA.

8. Exploring Neutrino Compositeness: Emerging and Invisible Jets at Neutrino and Charged Lepton Beams

Matteo Borrello (University of Florence, INFN of Florence)

05/03/2026, 15:30

The origin of neutrino masses suggests the existence of a sterile neutrino sector, which may be either too heavy or too weakly coupled to the Standard Model (SM) to be detected in the near future. The inverse seesaw mechanism provides a testable framework where the coupling between the sterile sector and the SM is large enough to allow direct experimental probes. In this context, it is crucial...

30. Characterizing Heavy Neutral Leptons: Measuring Parameters, Discriminating Majorana versus Dirac, and Using FASER2 as a Trigger for ATLAS

Daniel La Rocco

05/03/2026, 16:00

Heavy Neutral Leptons (HNLs) are a well-motivated extension of the Standard Model which may provide explanations for observed neutrino masses, dark matter, and baryogengesis via leptogenesis. In the event that a HNL signal is actually detected, much work will be dedicated to identifying the underlying nature of the observed signal excess. In this talk, we will use Monte-Carlo simulations of...

11. Spin Correlations in Dark Photon Searches

Misa Toman

05/03/2026, 16:20

We investigate the spin correlations between production and decay in the process where dark photons $A'$ are produced in pseudoscalar meson decays, for example, $\pi^0, \eta \to \gamma A'$, and then decay to fermion pairs, $A' \to f \bar{f}$. This process is the focus of many experimental searches, but spin correlations are typically ignored. We derive analytic results that allow us to...

13. Millicharged Particles with FORMOSA via Forward Neutron-Induced Showers at the LHC

Peiran Li (University of Minnesota)

05/03/2026, 16:40

We study the sensitivity of the FORMOSA experiment at the LHC Forward Physics Facility to millicharged particles (mCPs), focusing on a previously unexplored production mechanism associated with the forward neutron flux. Existing studies mainly consider mCP production from forward mesons directly produced in pp collisions.
We point out that pp collisions also generate an intense flux of...

3. Cosmic Millicharged Background, Reheating, and Arithmetica Electrōrum

Yu-Dai Tsai (University of California, Irvine)

05/03/2026, 17:00

We demonstrate that the searches for dark sector particles can provide probes of reheating scenarios, focusing on the cosmic millicharge background produced in the early universe. We discuss two types of millicharge particles (mCPs): either with, or without, an accompanying dark photon. These two types of mCPs have distinct theoretical motivations and cosmological signatures. We discuss...