Dark sectors — new physics neutral under Standard Model forces — can interact with ordinary matter through a few types of “portal” interaction constrained by Standard Model symmetries. This possibility has gained attention both as a paradigm for dark matter (stable dark sector particles are natural dark matter candidates, and can realize thermal freeze-out below the Lee-Weinberg bound) and as a broad framework for exploring new, weakly coupled physics. Dark sector particles are expected to have very weak couplings to ordinary matter, and motivate dedicated searches in high-intensity experiments. Simple and notable examples of dark sectors include low-mass dark matter interacting through a new force, minimal models of a scalar or vector mediator, and particles with weak long-range interactions such as millicharges.

This Topical Group will address the following areas of dark-sector physics (in parenthesis our sub-conveners):

1. Theory of dark sectors (Brian Batell, Philip Schuster)
2. Dark sectors at electron-positron colliders (Chris Hearty)
3. Dark sectors at fixed target / beam dump experiments (electron, positron, proton, and muon beams) (Gordan Krnjaic, Phil Harris, Natalia Toro)
4. Dark sectors at kaon factories (Babette Dobrich, Jure Zupan)
5. Low-mass dark sectors at energy-frontier facilities (cross-group with EF09 - BSM: More general explorations / EF10 - BSM: Dark Matter at colliders) (Phil Ilten)
6. Dark sectors at neutrino experiments (cross-group with NF03 - Neutrino physics - BSM) (Pilar Coloma)
7. Other experimental opportunities

References to recent community-driven reports on dark sectors:

• CERN PBC report
• Dark Matter New Initiatives BRN report (PRD1)
• Cosmic Visions New Ideas in Dark Matter (see, e.g., Sec. 6)
• Dark Sectors 2016:

In order for us to identify areas of interest, it would be great if you could fill out the google form at https://docs.google.com/forms/d/e/1FAIpQLSeLEgcQxYTooyS17LoR06GpZD2tXBu8QG4hQqvPTxSwTIE78w/viewform

Letters of Interest (April 1 – August 31, 2020) – https://snowmass21.org/loi
Please submit your LOI at https://www.snowmass21.org/docs/upload.php

Contributed Papers (April 1 – July 31, 2021) – https://snowmass21.org/submissions/

RF6 kickoff meeting. August 12-13 (two half days).
https://indico.fnal.gov/event/44819/

EF9/EF10/RF6/AF5 joint meeting on dark sectors. July 15-16, 8am-11am Pacific.
https://indico.fnal.gov/event/44030/overview

Rare Processes and precision kickoff meeting. July 27, 7am-3pm Pacific.
https://indico.fnal.gov/event/44121/overview

Please do not hesitate to contact us if you have questions, suggestion, or even just to express your interest, via email: Stefania Gori, Michael Williams

If you prefer, you can send an email or a message to our slack channel. We will also write to the mailing list and slack channels announcements relevant for the group.

To join our mailing list: Send an e-mail message to listserv[at]fnal.gov

Leave the subject line blank Type “SUBSCRIBE SNOWMASS-RPF-06-DARK-SECTOR FIRSTNAME LASTNAME” (without the quotation marks) in the body of your message. You'll get a Slack invitation when that subscription is approved.

To only join slack:

See the instructions on the SnowMass2021 home page for joining the snowmass2021 slack workspace. Our channel is #rpf-06-dark-sector which you can easily join once accepted to the snowmass2021 workspace, e.g., by pasting the channel name into the search bar or clicking the “+” button next to “channels” when in the snowmass2021 workspace and finding our channel, then clicking on our channel and subsequently clicking the “join” button.

Here is the list of submitted LOIs to this topic. First index before “/” corresponds to the primary frontier used for the submission.