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arXiv · 2508.11833

LDMX -- The Light Dark Matter eXperiment

Torsten Akesson·Layan Alsaraya·Stephen Appert·Charles Bell·Elizabeth Berzin·Nikita Blinov·Léo Borrel·Cameron Bravo·Liam Brennan·Lene Kristian Bryngemark·Pierfrancesco Butti·Riccardo Catena·Anthony Chavez·Owen Colegrove·Giulia Collura·Patill Daghlian·Filippo Delzanno·E. Craig Dukes·Valentina Dutta·Bertrand Echenard·Ralf Ehrlich·Thomas Eichlersmith·Jonathan Eisch·Einar Elén·Eric Fernandez·Erich Frahm·Cooper Froemming·Andrew P. Furmanski·Gréta Gajdán·Majd Ghrear·Niramay Gogate·Victor Gomez·Matt Graham·Taylor Gray·Josh Greaves·Chiara Grieco·Craig Group·Peter György·Carsten Hast·Axel Helgstrand·Hannah Herde·Christian Herwig·David G. Hitlin·Tyler Horoho·Cameron Huse·Joseph R. Incandela·David Jang·Nathan Jay·Asahi Jige·Joseph Kaminski·Wesley Ketchum·Matthew Kilpatrick·Kai Kristiansen·Gordan Krnjaic·Susanne Kyre·Travis Lange·Juan Lazaro·Amina Li·Shirley Li·Shujin Li·Yuze Li·Ziqi Lin·Hongyin Liu·Megan Loh·Lisa Andersson Loman·Zihan Ma·Jeremiah Mans·Sanjit Masanam·Phillip Masterson·Steven Metallo·Sophie Middleton·Noah Moran·Omar Moreno·Geoffrey Mullier·Joseph Muse·Akshay Nagar·Timothy Nelson·Gavin Niendorf·Rory O'Dwyer·William Ortez·Lennart Österman·Leo Östman·James Oyang·Pritam Palit·Dhruvanshu Parmar·Jessica Pascadlo·Emrys Peets·Arnaud Pele·Ruth Pöttgen·Huilin Qu·Melissa Quinnan·Jaida Raffelsberger·Benjamin Reese·Chelsea Rodriguez·Eduardo Sanchez·Luis G. Sarmiento·Philip Schuster·Chris Sellgren·Harrison Siegel·Pradyun Solai
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Abstract

The Light Dark Matter eXperiment (LDMX) is an electron fixed-target experiment optimized to search for sub-GeV dark matter production through the missing momentum signature. LDMX is designed to operate in End Station A at SLAC, using an 8 GeV electron beam accelerated alongside the LCLS-II drive beam. The design of the apparatus is strongly motivated by the performance requirements of a high-rate missing momentum search and leverages detector technologies and designs from other experiments along with existing facilities at SLAC. LDMX will improve on previous results by up to three orders of magnitude, enabling broad sensitivity to dark sector scenarios including the dark matter interaction strengths motivated by freeze-out of MeV-GeV mass dark matter to the observed relic abundance. With hermetic forward coverage, LDMX also has sensitivity to visible signatures of dark sectors and provides a unique probe of electron-nuclear interactions important to interpreting data from accelerator-based neutrino experiments. This report encompasses the technical design of the LDMX Detector, its simulated performance, and the physics capabilities of the experiment.

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Torsten Akesson, Layan Alsaraya, Stephen Appert, Charles Bell, Elizabeth Berzin, Nikita Blinov, Léo Borrel, Cameron Bravo, Liam Brennan, Lene Kristian Bryngemark, Pierfrancesco Butti, Riccardo Catena, Anthony Chavez, Owen Colegrove, Giulia Collura, Patill Daghlian, Filippo Delzanno, E. Craig Dukes, Valentina Dutta, Bertrand Echenard, Ralf Ehrlich, Thomas Eichlersmith, Jonathan Eisch, Einar Elén, Eric Fernandez, Erich Frahm, Cooper Froemming, Andrew P. Furmanski, Gréta Gajdán, Majd Ghrear, Niramay Gogate, Victor Gomez, Matt Graham, Taylor Gray, Josh Greaves, Chiara Grieco, Craig Group, Peter György, Carsten Hast, Axel Helgstrand, Hannah Herde, Christian Herwig, David G. Hitlin, Tyler Horoho, Cameron Huse, Joseph R. Incandela, David Jang, Nathan Jay, Asahi Jige, Joseph Kaminski, Wesley Ketchum, Matthew Kilpatrick, Kai Kristiansen, Gordan Krnjaic, Susanne Kyre, Travis Lange, Juan Lazaro, Amina Li, Shirley Li, Shujin Li, Yuze Li, Ziqi Lin, Hongyin Liu, Megan Loh, Lisa Andersson Loman, Zihan Ma, Jeremiah Mans, Sanjit Masanam, Phillip Masterson, Steven Metallo, Sophie Middleton, Noah Moran, Omar Moreno, Geoffrey Mullier, Joseph Muse, Akshay Nagar, Timothy Nelson, Gavin Niendorf, Rory O'Dwyer, William Ortez, Lennart Österman, Leo Östman, James Oyang, Pritam Palit, Dhruvanshu Parmar, Jessica Pascadlo, Emrys Peets, Arnaud Pele, Ruth Pöttgen, Huilin Qu, Melissa Quinnan, Jaida Raffelsberger, Benjamin Reese, Chelsea Rodriguez, Eduardo Sanchez, Luis G. Sarmiento, Philip Schuster, Chris Sellgren, Harrison Siegel, Pradyun Solai. 2025-10-02. LDMX -- The Light Dark Matter eXperiment. https://arxiv.org/abs/2508.11833

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