The top quark electro-weak couplings after LHC Run 2

Víctor Miralles, Marcos Miralles López, María Moreno Llácer, Ana Peñuelas, Martín Perelló, Marcel Vos

Recent measurements at the Large Hadron Collider allow for a robust and precise characterisation of the electro-weak interactions of the top quark. We present the results of a global analysis at next-to-leading order precision including LHC, LEP/SLD and Tevatron data in the framework of the Standard Model Effective Field Theory. We include a careful analysis of the impact of correlations among measurements, as well as of the uncertainties in the Effective Field Theory setup itself. We find remarkably robust global fit results, with central values in good agreement with the Standard Model prediction, and 95% probability bounds on Wilson coefficients that range from $\pm$ 0.35 to $\pm$ 8 TeV$^{-2}$. This result represents a considerable improvement over previous studies, thanks to the addition of differential cross-section measurements in associated production processes of top quarks and neutral gauge bosons.

Commissioning of the ATLAS reconstruction software with first data

Maria Moreno Llacer

Looking towards first LHC collisions, the ATLAS detector is being commissioned using the physics data available: cosmic rays and data taken during the LHC single beam operations at 450 GeV. During the installation of the ATLAS detector in the cavern, cosmic rays were collected with the different parts of the detector that were available. Combined cosmic runs taken with the full installed detector with and without magnetic field as well as a few single beam events recently recorded are being used to commission the full system prior to the first proton collisions.

ASFAP summary report: Particles and their Applications

María Moreno Llácer

The Second Biennal African Conference on Fundamental and Applied Physics (ACP) took place in March 2022. The scientific program included three summary reports on the African Strategy for Fundamental and Applied Physics (ASFAP). Here, the summary report of "Particle Physics and related applications" groups (Particle Physics, Nuclear Physics, Medical Physics, Astrophysics and Cosmology, Fluid and Plasma, and Complex Systems; and the cross-cutting fields: Accelerators, Instrumentation and Detectors, Computing, and Nuclear Energy) is presented. The scope of each of the groups, the events organised so far and their upcoming activities are summarised.

$t\bar{t}+V$ production in ATLAS

María Moreno Llácer

The latest ATLAS results for processes with a top quark pair and an associated vector boson are presented here. The measurement of the production cross sections for these processes is important for the direct determination of the top quark couplings to gauge bosons and for constraints on new physics models, in particular for models which go beyond the Standard Model regarding the mechanism for the mass generation.

Measurements of inclusive and differential fiducial cross-sections of $t\bar{t}γ$ production in leptonic final states at $\sqrt{s}$ = 13 TeV

María Moreno Llácer

The latest results of the ATLAS experiment for the production of a top-quark pair in association with a photon using proton-proton collision data from the LHC at a centre-of-mass energy of 13 TeV are summarised here. This includes inclusive and differential cross-sections measurements performed in single-lepton and dilepton final states in a fiducial volume corresponding to the experimental acceptance.

Search for the Standard Model Higgs boson production in association with top quarks in pp collisions at 8 TeV with the ATLAS detector

Maria Moreno Llacer

The search for the production of the Higgs boson associated with a pair of top quarks in the ATLAS experiment is presented. It focuses on Higgs bosons decaying to $b\bar{b}$ and events containing two leptons (electrons and/or muons). It uses 20.3 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}$ = 8 TeV collected with the ATLAS detector at the LHC in 2012. No significant excess of events is found and the 95% CL observed (expected) limit is 7.0xSM (4.3xSM). After combining with the single lepton final state an observed (expected) limit of 4.1xSM (2.6xSM) with a best fit of $μ=1.7\pm1.4$ is obtained.

Activity Report of the Second African Conference on Fundamental and Applied Physics, ACP2021

Kétévi A. Assamagan, Obinna Abah, Amare Abebe, Stephen Avery, Diallo Boye, Arame Boye-Faye, Kenneth Cecire, Mohamed Chabab, Samuel Chigome, Simon Connell, Marie Chantal Cyulinyana, Mark Macrae Dalton, Christine Darve, Lalla Btissam Drissi, Farida Fassi, Ulrich Goelach, Mohamed Gouighri, Paul Gueye, Sonia Haddad, Bjorn von der Heyden, Oumar Ka, Gihan Kamel, Stéphane Kenmoe, Diouma Kobor, Tjaart Krüger, Mounia Laassiri, Lerothodi Leeuw, Maria Moreno Llacer, Benard Mulilo, Robinson Musembi, Chilufya Mwewa, Clara Nellist, Lawrence Norris, Marie Clémentine Nibamureke, Mirjana Pović, Horst Severini, Marco Silari, Bertrand Tchanche Fankam, Iyabo Usman, Esmeralda Yitamben, Jaehoon Yu

The African School of Fundamental Physics and Applications, also known as the African School of Physics (ASP), was initiated in 2010, as a three-week biennial event, to offer additional training in fundamental and applied physics to African students with a minimum of three-year university education. Since its inception, ASP has grown to be much more than a school. ASP has become a series of activities and events with directed ethos towards physics as an engine for development in Africa. One such activity of ASP is the African Conference on Fundamental and Applied Physics (ACP). The first edition of ACP took place during the 2018 edition of ASP at the University of Namibia in Windhoek. In this paper, we report on the second edition of ACP, organized on March 7--11, 2022, as a virtual event.

Snowmass White Paper: prospects for the measurement of top-quark couplings

Gauthier Durieux, Abel Gutiérrez Camacho, Luca Mantani, Víctor Miralles, Marcos Miralles López, María Moreno Llácer, René Poncelet, Eleni Vryonidou, Marcel Vos

In this contribution to the 2021 Snowmass community planning exercise that informs the American strategy for particle physics, we present the prospects for measurements of the top-quark couplings at future colliders. Projections are presented for the high luminosity phase of the Large Hadron Collider and a future Higgs/electroweak/top factory electron-positron collider. Results are presented for the expected bounds on Wilson coefficients of the relevant SMEFT operators from a global fit to the top physics sector.

Report of the Topical Group on Top quark physics and heavy flavor production for Snowmass 2021

Reinhard Schwienhorst, Doreen Wackeroth, Kaustubh Agashe, Simone Alioli, Javier Aparisi, Giuseppe Bevilacqua, Huan-Yu Bi, Raymond Brock, Abel Gutierrez Camacho, Fernando Febres Cordero, Jorge de Blas, Regina Demina, Yong Du, Gauthier Durieux, Jarrett Fein, Roberto Franceschini, Juan Fuster, Maria Vittoria Garzelli, Alessandro Gavardi, Jason Gombas, Christoph Grojean, Jiale Gu, Marco Guzzi, Heribertus Bayu Hartanto, Andre Hoang, Jack Holguin, Adrian Irles, Nikolaos Kidonakis, Dojin Kim, Manfred Kraus, Christopher Lepenik, Tony M. Liss, Luca Mantani, Sonny Mantry, Vicent Mateu, Davide Melini, J. Michel, Victor Miralles, Marcos Miralles Lopez, Maria Moreno Llacer, Sven-Olaf Moch, Pavel Nadolsky, Tobias Neumann, Meenakshi Narain, Jasmina Nasufi, Kacper Nowak, Aditya Pathak, Michael Peskin, Rene Poncelet, Massimiliano Procura, Laura Reina, G. Rodrigo, Deepak Sathyan, Sara Sawford, Frank Simon, Michael Spira, Ian Stewart, Seidai Tairafune, Junping Tian, Alessandro Tricoli, Peter Uwer, Eleni Vryonidou, Katharina Voss, Marcel Vos, Malgorzata Worek, Keping Xie, Hitoshi Yamamoto, Ryo Yunamine, Zhite Yu, C. -P. Yuan, Aleksander Filip Zarnecki

This report summarizes the work of the Energy Frontier Topical Group on EW Physics: Heavy flavor and top quark physics (EF03) of the 2021 Community Summer Study (Snowmass). It aims to highlight the physics potential of top-quark studies and heavy-flavor production processes (bottom and charm) at the HL-LHC and possible future hadron and lepton colliders and running scenarios.

Universal Anomaly Detection at the LHC: Transforming Optimal Classifiers and the DDD Method

Sascha Caron, José Enrique García Navarro, María Moreno Llácer, Polina Moskvitina, Mats Rovers, Adrián Rubio Jímenez, Roberto Ruiz de Austri, Zhongyi Zhang

In this work, we present a novel approach to transform supervised classifiers into effective unsupervised anomaly detectors. The method we have developed, termed Discriminatory Detection of Distortions (DDD), enhances anomaly detection by training a discriminator model on both original and artificially modified datasets. We conducted a comprehensive evaluation of our models on the Dark Machines Anomaly Score Challenge channels and a search for 4-top quark events, demonstrating the effectiveness of our approach across various final states and beyond the Standard Model scenarios. We compare the performance of the DDD method with the Deep Robust One-Class Classification method (DROCC), which incorporates signals in the training process, and the Deep Support Vector Data Description (DeepSVDD) method, a well-established and well-performing method for anomaly detection. Results show that the effectiveness of each model varies by signal and channel, with DDD proving to be a very effective anomaly detector. We recommend the combined use of DeepSVDD and DDD for purely unsupervised applications, with the addition of flow models for improved performance when resources allow. Findings suggest that network architectures that excel in supervised contexts, such as the particle transformer with standard model interactions, also perform well as unsupervised anomaly detectors. We also show that with these methods, it is likely possible to recognize 4-top quark production as an anomaly without prior knowledge of the process. We argue that the Large Hadron Collider community can transform supervised classifiers into anomaly detectors to uncover potential new physical phenomena in each search.

The International Linear Collider: Report to Snowmass 2021

Alexander Aryshev, Ties Behnke, Mikael Berggren, James Brau, Nathaniel Craig, Ayres Freitas, Frank Gaede, Spencer Gessner, Stefania Gori, Christophe Grojean, Sven Heinemeyer, Daniel Jeans, Katja Kruger, Benno List, Jenny List, Zhen Liu, Shinichiro Michizono, David W. Miller, Ian Moult, Hitoshi Murayama, Tatsuya Nakada, Emilio Nanni, Mihoko Nojiri, Hasan Padamsee, Maxim Perelstein, Michael E. Peskin, Roman Poeschl, Sam Posen, Aidan Robson, Jan Strube, Taikan Suehara, Junping Tian, Maxim Titov, Marcel Vos, Andrew White, Graham Wilson, Kaoru Yokoya, Aleksander Filip Zarnecki, Ichiro Adachi, Kaustubh Agashe, Tatjana Agatonovic Jovin, Hiroaki Aihara, Wolfgang Altmannshofer, Daniele Alves, Justin Anguiano, Ken-Ichi Aoki, Masato Aoki, Toshihiro Aoki, Yumi Aoki, Yasuo Arai, Hayato Araki, Haruka Asada, Kento Asai, Shoji Asai, David Attie, Howard Baer, Jonathan Bagger, Yang Bai, Ian Bailey, Ricardo Barrue, Rainer Bartoldus, Emanuela Barzi, Matthew Basso, Lothar Bauerdick, Sebastian Baum, Alain Bellerive, Sergey Belomestnykh, Jorge Berenguer Antequera, Jakob Beyer, Pushpalatha Bhat, Burak Bilki, Kevin Black, Kenneth Bloom, Geoffrey Bodwin, Veronique Boisvert, Fatma Boran, Vincent Boudry, Radja Boughezal, Antonio Boveia, Ivanka Bozovic-Jelisavcic, Jean-Claude Brient, Stanley Brodsky, Laurent Brunetti, Karsten Buesser, Eugene Bulyak, Philip N. Burrows, Graeme C. Burt, Yunhai Cai, Valentina Cairo, Anadi Canepa, Francesco Giovanni Celiberto, Enrico Cenni, Zackaria Chacko, Iryna Chaikovska, Mattia Checchin, Lisong Chen, Thomas Y. Chen, Hsin Chia Cheng, Gi-Chol Cho, Brajesh Choudhary, Jim Clarke, James Cline, Raymond Co, Timothy Cohen, Paul Colas, Chris Damerell, Arindam Das, Sridhara Dasu, Sally Dawson, Jorge de Blas, Carlos Henrique de Lima, Aldo Deandrea, Klaus Dehmelt, Jean Delayen, Carlos Henrique de Lima, Marcel Demarteau, Dmitri Denisov, Radovan Dermisek, Angel Dieguez, Takeshi Dohmae, Jens Dopke, Katharina Dort, Yong Du, Bohdan Dudar, Bhaskar Dutta, Juhi Dutta, Ulrich Einhaus, Eckhard Elsen, Motoi Endo, Grigory Eremeev, Engin Eren, Jens Erler, Eric Esarey, Lisa Everett, Angeles Faus Golfe, Marcos Fernandez Garcia, Brian Foster, Nicolas Fourches, Mary-Cruz Fouz, Keisuke Fujii, Junpei Fujimoto, Esteban Fullan Torregrosa, Kazuro Furukawa, Takahiro Fusayasu, Juan Fuster, Serguei Ganjour, Yuanning Gao, Naveen Gaur, Rongli Geng, Howard Georgi, Tony Gherghetta, Joel Goldstein, Dorival Goncalves, Julia Gonski, Tomas Gonzalo, Takeyoshi Goto, Toru Goto, Norman Graf, Joseph Grames, Paul Grannis, Lindsey Gray, Alexander Grohsjean, Jiayin Gu, Yalcin Guler, Phillip Gutierrez, Junji Haba, Howard Haber, John Hallford, Koichi Hamaguchi, Tao Han, Kazuhiko Hara, Daisuke Harada, Koji Hashimoto, Katsuya Hashino, Masahito Hayashi, Gudrun Heinrich, Keisho Hidaka, Takeo Higuchi, Fujio Hinode, Zenro Hioki, Minoru Hirose, Nagisa Hiroshima, Junji Hisano, Wolfgang Hollik, Samuel Homiller, Sungwoo Hong, Anson Hook, Yasuyuki Horii, Hiroki Hoshina, Ivana Hristova, Katri Huitu, Yoshifumi Hyakutake, Toru Iijima, Katsumasa Ikematsu, Anton Ilderton, Kenji Inami, Adrian Irles, Akimasa Ishikawa, Koji Ishiwata, Hayato Ito, Igor Ivanov, Sho Iwamoto, Toshiyuki Iwamoto, Masako Iwasaki, Yoshihisa Iwashita, Haoyi Jia, Fabricio Jimenez Morales, Prakash Joshi, Sunghoon Jung, Goran Kacarevic, Michael Kagan, Mitsuru Kakizaki, Jan Kalinowski, Jochen Kaminski, Kazuyuki Kanaya, Shinya Kanemura, Hayato Kanno, Yuya Kano, Shigeru Kashiwagi, Yukihiro Kato, Nanami Kawada, Shin-ichi Kawada, Kiyotomo Kawagoe, Valery Khoze, Hiromichi Kichimi, Doojin Kim, Teppei Kitahara, Ryuichiro Kitano, Jan Klamka, Sachio Komamiya, K. C. Kong, Taro Konomi, Katsushige Kotera, Emi Kou, Ilya Kravchenko, Kiyoshi Kubo, Takayuki Kubo, Takuya Kumaoka, Ashish Kumar, Nilanjana Kumar, Jonas Kunath, Saumyen Kundu, Hiroshi Kunitomo, Masakazu Kurata, Masao Kuriki, Alexander Kusenko, Theodota Lagouri, Andrew J. Lankford, Gordana Lastovicka-Medin, Francois Le Diberder, Claire Lee, Matthias Liepe, Jacob Linacre, Zachary Liptak, Shivani Lomte, Ian Low, Yang Ma, Hani Maalouf, David MacFarlane, Brendon Madison, Thomas Madlener, Tomohito Maeda, Paul Malek, Sanjoy Mandal, Thomas Markiewicz, John Marshall, Aurelien Martens, Victoria Martin, Martina Martinello, Celso Martinez Rivero, Nobuhito Maru, John Matheson, Shigeki Matsumoto, Hiroyuki Matsunaga, Yutaka Matsuo, Kentarou Mawatari, Johnpaul Mbagwu, Peter McIntosh, Peter McKeown, Patrick Meade, Krzysztof Mekala, Petra Merkel, Satoshi Mihara, Víctor Miralles, Marcos Miralles Lopez, Go Mishima, Satoshi Mishima, Bernhard Mistlberger, Alexander Mitov, Kenkichi Miyabayashi, Akiya Miyamoto, Gagan Mohanty, Laura Monaco, Myriam Mondragon, Hugh E. Montgomery, Gudrid Moortgat-Pick, Nicolas Morange, María Moreno Llacer, Stefano Moretti, Toshinori Mori, Toshiyuki Morii, Takeo Moroi, David Morrissey, Benjamin Nachman, Kunihiro Nagano, Jurina Nakajima, Eiji Nakamura, Shinya Narita, Pran Nath, Timothy Nelson, David Newbold, Atsuya Niki, Yasuhiro Nishimura, Eisaku Nishiyama, Yasunori Nomura, Kacper Nowak, Mitsuaki Nozaki, María Teresa Nunez Pardo de Vera, Ines Ochoa, Masahito Ogata, Satoru Ohashi, Hikaru Ohta, Shigemi Ohta, Norihito Ohuchi, Hideyuki Oide, Nobuchika Okada, Yasuhiro Okada, Shohei Okawa, Yuichi Okayasu, Yuichi Okugawa, Toshiyuki Okugi, Takemichi Okui, Yoshitaka Okuyama, Mathieu Omet, Tsunehiko Omori, Hiroaki Ono, Tomoki Onoe, Wataru Ootani, Hidetoshi Otono, Shuhei Ozawa, Simone Pagan Griso, Alessandro Papa, Rocco Paparella, Eun-Kyung Park, Gilad Perez, Abdel Perez-Lorenzana, Yvonne Peters, Frank Petriello, Jonatan Piedra, Werner Porod, Christopher Potter, Alan Price, Yasser Radkhorrami, Laura Reina, Juergen Reuter, Francois Richard, Sabine Riemann, Robert Rimmer, Thomas Rizzo, Tania Robens, Roger Ruber, Alberto Ruiz Jimeno, Takayuki Saeki, Ipsita Saha, Tomoyuki Saito, Makoto Sakaguchi, Tadakatsu Sakai, Yasuhito Sakaki, Kodai Sakurai, Riccardo Salvatico, Fabrizio Salvatore, Yik Chuen San, Pearl Sandick, Tomoyuki Sanuki, Kollassery Swathi Sasikumar, Oliver Schaefer, Ruth Schaefer, Uwe Schneekloth, Thomas Schoerner-Sadenius, Carl Schroeder, Philip Schuster, Ariel Schwartzman, Reinhard Schwienhorst, Felix Sefkow, Yoshihiro Seiya, Motoo Sekiguchi, Kazuyuki Sekizawa, Katsumi Senyo, Hale Sert, Danielev Sertore, Ronald Settles, Qaisar Shafi, Tetsuo Shahdara, Barmak Shams Es Haghi, Ashish Sharma, Jessie Shelton, Claire Shepherd-Themistocleous, Hiroto Shibuya, Tetsuo Shidara, Takashi Shimomura, Tetsuo Shindou, Yutaro Shoji, Jing Shu, Ian Sievers, Frank Simon, Rajeev Singh, Yotam Soreq, Marcel Stanitzki, Steinar Stapnes, Amanda Steinhebel, John Stupak, Shufang Su, Fumihiko Suekane, Akio Sugamoto, Yuji Sugawara, Satoru Sugimoto, Yasuhiro Sugimoto, Hiroaki Sugiyama, Yukinari Sumino, Raman Sundrum, Atsuto Suzuki, Shin Suzuki, Maximilian Swiatlowski, Tim M. P. Tait, Shota Takahashi, Tohru Takahashi, Tohru Takeshita, Michihisa Takeuchi, Yosuke Takubo, Tomohiko Tanabe, Philip Tanedo, Morimitsu Tanimoto, Shuichiro Tao, Xerxes Tata, Toshiaki Tauchi, Geoffrey Taylor, Takahiro Terada, Nobuhiro Terunuma, Jesse Thaler, Alessandro Thea, Finn Tillinger, Jan Timmermans, Kohsaku Tobioka, Kouichi Toda, Atsushi Tokiyasu, Takashi Toma, Julie Torndal, Mehmet Tosun, Yu-Dai Tsai, Shih-Yen Tseng, Koji Tsumura, Douglas Tuckler, Yoshiki Uchida, Yusuke Uchiyama, Daiki Ueda, Fumihiko Ukegawa, Kensei Umemori, Junji Urakawa, Claude Vallee, Roberto Vega, Liliana Velasco, Silvia Verdu-Andres, Caterina Vernieri, Anna Vila, Ivan Vila Alvarez, Joost Vossebeld, Raghava Vsrms, Natasa Vukasinovic, Doreen Wackeroth, Moe Wakida, Liantao Wang, Masakazu Washio, Takashi Watanabe, Nigel Watson, Gordon Watts, Georg Weiglein, James D. Wells, Marc Wenskat, Susanne Westhoff, Glen White, Ciaran Williams, Stephane Willocq, Matthew Wing, Alasdair Winter, Marc Winter, Yongcheng Wu, Keping Xie, Tao Xu, Vyacheslav Yakovlev, Shuei Yamada, Akira Yamamoto, Hitoshi Yamamoto, Kei Yamamoto, Yasuchika Yamamoto, Masato Yamanaka, Satoru Yamashita, Masahiro Yamatani, Naoki Yamatsu, Shigehiro Yasui, Takuya Yoda, Ryo Yonamine, Keisuke Yoshihara, Masakazu Yoshioka, Tamaki Yoshioka, Fukuko Yuasa, Keita Yumino, Dirk Zerwas, Ya-Juan Zheng, Jia Zhou, Hua Xing Zhu, Mikhail Zobov, Fabian Zomer

Future collider constraints on top-quark operators

Fernando Cornet-Gomez, Víctor Miralles, Marcos Miralles López, María Moreno Llácer, Marcel Vos

In this paper we present updated constraints on the top-quark sector of the Standard Model Effective Field Theory using data available from Tevatron, LEP and the LHC. Bounds are obtained for the Wilson coefficients from a global fit including the relevant two-fermion operators, four-quark operators and two-quark two-lepton operators. We compare the current bounds with the prospects for the high luminosity phase of the Large Hadron Collider and future lepton colliders.

Simplified Template Cross Sections -- Stage 1.1 and 1.2

Nicolas Berger, Claudia Bertella, Matteo Bonanomi, Nihal Brahimi, Thomas P. Calvet, Milene Calvetti, Valerio Dao, Marco Delmastro, Michael Duehrssen-Debling, Paolo Francavilla, Yacine Haddad, Sarah Heim, Jelena Jovicevic, Oleh Kivernyk, Maria Moreno Llacer, Jonathon M. Langford, Changqiao Li, Giovanni Marchiori, Josh A. McFayden, Johannes K. L. Michel, Predrag Milenovic, Carlo E. Pandini, Edward Scott, Frank J. Tackmann, Kerstin Tackmann, Lorenzo Viliani, Meng Xiao, Hongtao Yang

Simplified Template Cross Sections (STXS) have been adopted by the LHC experiments as a common framework for Higgs measurements. Their purpose is to reduce the theoretical uncertainties that are directly folded into the measurements as much as possible, while at the same time allowing for the combination of the measurements between different decay channels as well as between experiments. We report the complete, revised definition of the STXS kinematic bins (stage 1.1 and stage 1.2), which have been used for the measurements by the ATLAS and CMS experiments using the full LHC Run 2 datasets. The main focus is on the four dominant Higgs production processes, namely gluon-fusion, vector-boson fusion, production in association with a vector boson and in association with a $t\bar t$ pair. We also comment briefly on the treatment of other production modes.

t-channel dark matter at the LHC -- a whitepaper

Chiara Arina, Benjamin Fuks, Luca Panizzi, Michael J. Baker, Alan S. Cornell, Jan Heisig, Benedikt Maier, Rute Pedro, Dominique Trischuk, Diyar Agin, Alexandre Arbey, Giorgio Arcadi, Emanuele Bagnaschi, Kehang Bai, Disha Bhatia, Mathias Becker, Alexander Belyaev, Ferdinand Benoit, Monika Blanke, Jackson Burzynski, Jonathan M. Butterworth, Antimo Cagnotta, Lorenzo Calibbi, Linda M. Carpenter, Xabier Cid Vidal, Emanuele Copello, Louie Corpe, Francesco D'Eramo, Aldo Deandrea, Aman Desai, Caterina Doglioni, Sunil M. Dogra, Mathias Garny, Mark D. Goodsell, Sohaib Hassan, Philip Coleman Harris, Julia Harz, Alejandro Ibarra, Alberto Orso Maria Iorio, Felix Kahlhoefer, Deepak Kar, Shaaban Khalil, Valery Khoze, Pyungwon Ko, Sabine Kraml, Greg Landsberg, Andre Lessa, Laura Lopez-Honorez, Alberto Mariotti, Vasiliki A. Mitsou, Kirtimaan Mohan, Chang-Seong Moon, Alexander Moreno Briceño, María Moreno Llácer, Léandre Munoz-Aillaud, Taylor Murphy, Anele M. Ncube, Wandile Nzuza, Clarisse Prat, Lena Rathmann, Thobani Sangweni, Dipan Sengupta, William Shepherd, Sukanya Sinha, Tim M. P. Tait, Andrea Thamm, Michel H. G. Tytgat, Zirui Wang, David Yu, Shin-Shan Yu

This report, summarising work achieved in the context of the LHC Dark Matter Working Group, investigates the phenomenology of $t$-channel dark matter models, spanning minimal setups with a single dark matter candidate and mediator to more complex constructions closer to UV-complete models. For each considered class of models, we examine collider, cosmological and astrophysical implications. In addition, we explore scenarios with either promptly decaying or long-lived particles, as well as featuring diverse dark matter production mechanisms in the early universe. By providing a unified analysis framework, numerical tools and guidelines, this work aims to support future experimental and theoretical efforts in exploring $t$-channel dark matter models at colliders and in cosmology.

Radiation effects on the entanglement of fermion pairs at colliders

Rafael Aoude, José Manuel Camacho, Valentin Durupt, Guillermo García-Mir, Fabio Maltoni, María Moreno Llácer, Leonardo Satrioni, Marcel Vos

We study the impact of radiation on quantum systems defined by the spins of elementary fermion-antifermion pairs produced at colliders. We present predictions for several processes, showing that energetic final-state radiation can induce decoherence and significantly reduce the entanglement of quantum systems formed by elementary fermion pairs. We investigate the feasibility of observing this effect experimentally in exclusive samples with energetic radiation. A statistically significant signal can be obtained with current data in associated $pp \rightarrow t\bar{t}(g)$ production at the LHC and in $e^+e^- \rightarrow τ^{+}τ^{-}(γ)$ production at Belle 2. Future electron-positron colliders operated at the $Z$ pole or well above the $t\bar{t}$ production threshold will extend these prospects further.