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

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

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.

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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.