Krzysztof Mękała, Jürgen Reuter, Aleksander Filip Żarnecki
Neutrinos are the most elusive particles known. Heavier sterile neutrinos mixing with the standard neutrinos might solve the mystery of the baryon asymmetry of the universe. In this letter, we show that among all future energy frontier accelerators, muon colliders will provide the farthest search reach for such neutrinos for mass ranges above the $Z$ pole into the multi-TeV regime. We compare the performance of muon with electron colliders of the same machine energy and briefly discuss the complementarity in flavor space between the two types of accelerators.
Krzysztof Mękała, Daniel Jeans, Junping Tian, Jürgen Reuter, Aleksander Filip Żarnecki
Electroweak Precision Measurements are stringent tests of the Standard Model and sensitive probes to New Physics. Accurate studies of the Z-boson couplings to the first-generation quarks could reveal potential discrepancies between the fundamental theory and experimental data. Future lepton colliders offering high statistics of Z bosons would be an excellent tool to perform such a measurement based on comparison of radiative and non-radiative hadronic decays of the Z boson. Due to the difference in quark charge, the relative contribution of the events with final-state radiation (FSR) directly reflects the ratio of up- and down-type quark decays. Such an analysis requires a proper distinction between photons coming from different sources, including initial-state radiation (ISR), FSR, parton showers and hadronisation. In our talk, we will show how to extract the values of the Z couplings to quarks and present preliminary results of the analysis for ILC.
Krzysztof Mękała, Jürgen Reuter, Aleksander Filip Żarnecki
In this paper we investigate how well the nature of heavy neutral leptons can be determined at a future lepton collider, after its potential discovery. Considered in a simplified model are prompt decays of the neutrino in the mass range from 100 GeV to 10 TeV. We study event selection and application of multivariate analyses to determine whether such a newly discovered particle is of the Dirac or Majorana nature. Combining lepton charge and kinematic event variables, we find that the nature of a heavy neutrino, whether it is a Dirac or a Majorana particle, can be determined at 95% C.L. almost in the whole discovery range. We will briefly speculate about other than the studied channels and the robustness of this statement in more general models of heavy neutral leptons, particularly on the complementarity of high-energy electron-positron vs. muon colliders on resolving the flavor structure of heavy neutrinos.
Krzysztof Mękała, Jürgen Reuter, Aleksander Filip Żarnecki
Neutrinos are among the most mysterious particles in nature. Their mass hierarchy and oscillations, as well as their antiparticle properties, are being intensively studied in experiments around the world. Moreover, in many models of physics beyond the Standard Model, the baryon asymmetry or the dark matter density in the Universe are explained by introducing new species of neutrinos. Among others, heavy neutrinos of Dirac or Majorana nature were proposed to solve open questions in High Energy Physics. Such neutrinos with masses above the EW scale could be produced at future linear e$^+$e$^-$ colliders, like the Compact LInear Collider (CLIC) or the International Linear Collider (ILC). We studied the possibility of observing decays of heavy Dirac and Majorana neutrinos in the $qq\ell$ final state with ILC running at 500 GeV and 1 TeV, and CLIC at 3 TeV. The analysis is based on the Whizard event generation and fast simulation of detector response with Delphes. Neutrinos with masses from 200 GeV to 3.2 TeV were considered. We estimated the limits on the production cross sections, interpreted them in terms of the neutrino-lepton coupling parameter $V_{\ell N}^{2}$ (effectively the neutrino mixing angle) and compared them with current limits coming from the LHC running at 13 TeV, as well as the expected limits from future hadron colliders. The limits for the future lepton colliders, extending down to the coupling values of $10^{-7} - 10^{-6}$, are stricter than any other limit estimates published so far.
Kateryna Korshynska, Maximilian Löschner, Mariia Marinichenko, Krzysztof Mękała, Jürgen Reuter
We study the discrimination power of future multi-TeV muon colliders for a large set of models with extended gauge symmetries and additional neutral gauge bosons ("$Z'$-models"). Our study is carried out using a $χ^2$-analysis of leptonic observables of s-channel scattering in effective $Z'$-models. We make use of angular and chiral asymmetries induced in such models to find the discovery reach of a given muon collider setup in terms of the $Z'$ mass and to discriminate between the different scenarios. In this context, we discuss how polarized beams - should they become available at muon colliders - or polarization measurements can help in the discrimination. Our results show that typical muon collider setups which are currently under consideration can give a significantly higher reach compared to existing bounds and projections for high-luminosity LHC.
Tulika Bose, Antonio Boveia, Caterina Doglioni, Simone Pagan Griso, James Hirschauer, Elliot Lipeles, Zhen Liu, Nausheen R. Shah, Lian-Tao Wang, Kaustubh Agashe, Juliette Alimena, Sebastian Baum, Mohamed Berkat, Kevin Black, Gwen Gardner, Tony Gherghetta, Josh Greaves, Maxx Haehn, Phil C. Harris, Robert Harris, Julie Hogan, Suneth Jayawardana, Abraham Kahn, Jan Kalinowski, Simon Knapen, Ian M. Lewis, Meenakshi Narain, Katherine Pachal, Matthew Reece, Laura Reina, Tania Robens, Alessandro Tricoli, Carlos E. M. Wagner, Riley Xu, Felix Yu, Filip Zarnecki, Amin Aboubrahim, Andreas Albert, Michael Albrow, Wolfgang Altmannshofer, Gerard Andonian, Artur Apresyan, Kétévi Adikle Assamagan, Patrizia Azzi, Howard Baer, Michael J. Baker, Avik Banerjee, Vernon Barger, Brian Batell, Martin Bauer, Hugues Beauchesne, Samuel Bein, Alexander Belyaev, Ankit Beniwal, Mikael Berggren, Prudhvi N. Bhattiprolu, Nikita Blinov, Alain Blondel, Oleg Brandt, Giacomo Cacciapaglia, Rodolfo Capdevilla, Marcela Carena, Cesare Cazzaniga, Francesco Giovanni Celiberto, Cari Cesarotti, Sergei V. Chekanov, Hsin-Chia Cheng, Thomas Y. Chen, Yuze Chen, R. Sekhar Chivukula, Matthew Citron, James Cline, Tim Cohen, Jack H. Collins, Eric Corrigan, Nathaniel Craig, Daniel Craik, Andreas Crivellin, David Curtin, Smita Darmora, Arindam Das, Sridhara Dasu, Annapaola de Cosa, Aldo Deandrea, Antonio Delgado, Zeynep Demiragli, David d'Enterria, Frank F. Deppisch, Radovan Dermisek, Nishita Desai, Abhay Deshpande, Jordy de Vries, Jennet Dickinson, Keith R. Dienes, Karri Folan Di Petrillo, Matthew J. Dolan, Peter Dong, Patrick Draper, Marco Drewes, Etienne Dreyer, Peizhi Du, Florian Eble, Majid Ekhterachian, Motoi Endo, Rouven Essig, Jesse N. Farr, Farida Fassi, Jonathan L. Feng, Gabriele Ferretti, Daniele Filipetto, Thomas Flacke, Karri Folan Di Petrillo, Roberto Franceschini, Diogo Buarque Franzosi, Keisuke Fujii, Benjamin Fuks, Sri Aditya Gadam, Boyu Gao, Aran Garcia-Bellido, Isabel Garcia Garcia, Maria Vittoria Garzelli, Stephen Gedney, Marie-Hélène Genest, Tathagata Ghosh, Mark Golkowski, Giovanni Grilli di Cortona, Emine Gurpinar Guler, Yalcin Guler, C. Guo, Nate Graf, Ulrich Haisch, Jan Hajer, Koichi Hamaguchi, Tao Han, Philip Harris, Sven Heinemeyer, Christopher S. Hill, Joshua Hiltbrand, Tova Ray Holmes, Samuel Homiller, Sungwoo Hong, Walter Hopkins, Shih-Chieh Hsu, Phil Ilten, Wasikul Islam, Sho Iwamoto, Daniel Jeans, Laura Jeanty, Haoyi Jia, Sergo Jindariani, Daniel Johnson, Felix Kahlhoefer, Yonatan Kahn, Paul Karchin, Thomas Katsouleas, Shin-ichi Kawada, Junichiro Kawamura, Chris Kelso, Elham E Khoda, Valery Khoze, Doojin Kim, Teppei Kitahara, Juraj Klaric, Michael Klasen, Kyoungchul Kong, Wojciech Kotlarski, Ashutosh V. Kotwal, Jonathan Kozaczuk, Richard Kriske, Suchita Kulkarni, Jason Kumar, Manuel Kunkel, Greg Landsberg, Kenneth Lane, Clemens Lange, Lawrence Lee, Jiajun Liao, Benjamin Lillard, Lingfeng Li, Shuailong Li, Shu Li, Jenny List, Tong Li, Hongkai Liu, Jia Liu, Jonathan D Long, Enrico Lunghi, Kun-Feng Lyu, Danny Marfatia, Dakotah Martinez, Stephen P. Martin, Navin McGinnis, Karrick McGinty, Krzysztof Mękała, Federico Meloni, Oleksii Mikulenko, Ming Huang, Rashmish K. Mishra, Manimala Mitra, Vasiliki A. Mitsou, Chang-Seong Moon, Alexander Moreno, Takeo Moroi, Gerard Mourou, Malte Mrowietz, Patric Muggli, Jurina Nakajima, Pran Nath, J. Nelson, Matthias Neubert, Laura Nosler, Maria Teresa Núñez Pardo de Vera, Nobuchika Okada, Satomi Okada, Vitalii A. Okorokov, Yasar Onel, Tong Ou, Maksym Ovchynnikov, Rojalin Padhan, Priscilla Pani, Luca Panizzi, Andreas Papaefstathiou, Kevin Pedro, Cristián Peña, Federica Piazza, James Pinfold, Deborah Pinna, Werner Porod, Chris Potter, Markus Tobias Prim, Stefano Profumo, James Proudfoot, Mudit Rai, Filip Rajec, Reese Ramos, Michael J. Ramsey-Musolf, Javier Resta-Lopez, Jürgen Reuter, Andreas Ringwald, Chiara Rizzi, Thomas G. Rizzo, Giancarlo Rossi, Richard Ruiz, L. Rygaard, Aakash A. Sahai, Shadman Salam, Pearl Sandick, Deepak Sathyan, Christiane Scherb, Pedro Schwaller, Leonard Schwarze, Pat Scott, Sezen Sekmen, Dibyashree Sengupta, S. Sen, Anna Sfyrla, Eric Shackelford, T. Sharma, Varun Sharma, Jessie Shelton, William Shepherd, Seodong Shin, Elizabeth H. Simmons, Zoie Sloneker, Carlos Vázquez Sierra, Torbjörn Sjöstrand, Scott Snyder, Huayang Song, Giordon Stark, Patrick Stengel, Joachim Stohr, Daniel Stolarski, Matt Strassler, Nadja Strobbe, Julia Gonski, Rebeca Gonzalez Suarez, Taikan Suehara, Shufang Su, Wei Su, Raza M. Syed, Tim M. P. Tait, Toshiki Tajima, Andy Tang, Xerxes Tata, Teodor Tchalokov, Andrea Thamm, Brooks Thomas, Natalia Toro, Nhan V. Tran, Loan Truong, Yu-Dai Tsai, Eva Tuecke, Nikhilesh Venkatasubramanian, Chris B. Verhaaren, Carl Vuosalo, Xiao-Ping Wang, Xing Wang, Yikun Wang, Zhen Wang, Christian Weber, Glen White, Martin White, Anthony G. Williams, Brady Williams, Mike Williams, Stephane Willocq, Alex Woodcock, Yongcheng Wu, Ke-Pan Xie, Keping Xie, Si Xie, C. -H. Yeh, Ryo Yonamine, David Yu, S. -S. Yu, Mohamed Zaazoua, Aleksander Filip Żarnecki, Kamil Zembaczynski, Danyi Zhang, Jinlong Zhang, Frank Zimmermann, Jose Zurita
Jan-Hendrik Arling, Alexander Burgman, Christina Dimitriadi, Ulrich Einhaus, Axel Gallén, Abdelhamid Haddad, Laura Huhta, Armin Ilg, Jan Klamka, Elizabeth Long, Thomas Madlener, Arnau Morancho Tardà, Emanuela Musumeci, Krzysztof Mękała, Elena Pompa Pacchi, Marvin Pfaff, Daniel Reichelt, Leonhard Reichenbach, Birgit Stapf, Francesco P. Ucci, Erik Wallin, Harriet Watson, Sagar Vidya Addepalli, Bruno Alves, Robert Mihai Amarinei, Ricardo Barrué, Lydia Brenner, Giacomo Da Molin, Arturo de Giorgi, Bohdan Dudar, Francesco Giuli, Andrea Gurgone, César Jesús-Valls, Antoine Laudrain, Martin J. Losekamm, Rafał Masełek, Wrishik Naskar, Miquel Nebot-Guinot, Marko Pesut, Thomas Pöschl, Efrain P. Segarra, Rebecca Taylor, Pavel Vana, Hannah Wakeling, Aidan R. Wiederhold
This document, written by early career researchers (ECRs) in particle physics, aims to represent the perspectives of the European ECR community and serves as input for the 2025--2026 update of the European Strategy for Particle Physics. With input from a community-wide survey, it highlights key challenges faced by ECRs -- career stability, funding access and long-term research opportunities -- while proposing policy recommendations and targeted initiatives. It underscores the importance of practices fostering diverse, equitable, inclusive and healthy workplaces, as well as of stronger ECR communities, and highlights how effective communication and interdisciplinary collaborations reinforce the societal relevance of particle physics and promote continued support for large-scale and long-term projects. Finally, the future of both collider and beyond-collider experiments is addressed, emphasising the critical role of ECRs in shaping future projects. The ECR contribution is formed of two parts: the ten-page executive summary submitted as input to the European Strategy for Particle Physics Update and, as backup document, this extended white paper providing additional context.
Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime', Avni Aksoy, Gian Luigi Alberghi, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto, Fabio Anulli, Ludovica Aperio Bella, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae, E. J. Bahng, Lorenzo Balconi, Fabrice Balli, Laura Bandiera, Laura Bandiera, Carmelo Barbagallo, Daniele Barducci, Roger Barlow, Camilla Bartoli, Nazar Bartosik, Emanuela Barzi, Fabian Batsch, Matteo Bauce, Michael Begel, J. Scott Berg, Andrea Bersani, Alessandro Bertarelli, Francesco Bertinelli, Alessandro Bertolin, Pushpalatha Bhat, Clarissa Bianchi, Michele Bianco, William Bishop, Kevin Black, Fulvio Boattini, Alex Bogacz, Maurizio Bonesini, Bernardo Bordini, Patricia Borges de Sousa, Salvatore Bottaro, Luca Bottura, Steven Boyd, Johannes Braathen, Marco Breschi, Francesco Broggi, Matteo Brunoldi, Xavier Buffat, Laura Buonincontri, Marco Buonsante, Philip Nicholas Burrows, Graeme Campbell Burt, Dario Buttazzo, Barbara Caiffi, Sergio Calatroni, Marco Calviani, Simone Calzaferri, Daniele Calzolari, Vieri Candelise, Claudio Cantone, Rodolfo Capdevilla, Christian Carli, Carlo Carrelli, Fausto Casaburo, Massimo Casarsa, Luca Castelli, Maria Gabriella Catanesi, Lorenzo Cavallucci, Gianluca Cavoto, Francesco Giovanni Celiberto, Luigi Celona, Alessia Cemmi, Sergio Ceravolo, Alessandro Cerri, Francesco Cerutti, Gianmario Cesarini, Cari Cesarotti, Antoine Chancé, Nikolaos Charitonidis, mauro chiesa, Paolo Chiggiato, Vittoria Ludovica Ciccarella, Pietro Cioli Puviani, Anna Colaleo, Francesco Colao, Francesco Collamati, Marco Costa, Nathaniel Craig, David Curtin, Laura D'Angelo, Giacomo Da Molin, Heiko Damerau, Sridhara Dasu, Jorge de Blas, Stefania De Curtis, Herbert De Gersem, Andre de Gouvea, Tommaso Del Moro, Jean-Pierre Delahaye, Dmitri Denisov, Haluk Denizli, Radovan Dermisek, Radovan Dermisek, Paula Desiré Valdor, Charlotte Desponds, Luca Di Luzio, Elisa Di Meco, Karri Folan Di Petrillo, Ilaria Di Sarcina, Eleonora Diociaiuti, Tommaso Dorigo, Karlis Dreimanis, Tristan du Pree, Hatice Duran Yildiz, Juhi Dutta, Thomas Edgecock, Mamad Eshraqi, Siara Fabbri, Marco Fabbrichesi, Stefania Farinon, Davide Fazioli, Guillaume Ferrand, Samuel Ferraro, Jose Antonio Ferreira Somoza, Marco Ferrero, Max Fieg, Frank Filthaut, Patrick Fox, Roberto Franceschini, Rui Franqueira Ximenes, Frank Gaede, Simone Galletto, Michele Gallinaro, Maurice Garcia-Sciveres, Luis Garcia-Tabares, Rocky Bala Garg, Ruben Gargiulo, Cedric Garion, Maria Vittoria Garzelli, Marco Gast, Lisa Generoso, Cecilia E. Gerber, Luca Giambastiani, Alessio Gianelle, Eliana Gianfelice-Wendt, Stephen Gibson, Simone Gilardoni, Dario Augusto Giove, Valentina Giovinco, Carlo Giraldin, Alfredo Glioti, Arkadiusz Gorzawski, Mario Greco, Christophe Grojean, Alexej Grudiev, Edda Gschwendtner, Emanuele Gueli, Nicolas Guilhaudin, Tao Han, Chengcheng Han, John Michael Hauptman, Matthew Herndon, Adrian D Hillier, Micah Hillman, Gabriela Hoff, Tova Ray Holmes, Samuel Homiller, Walter Hopkins, Lennart Huth, Sudip Jana, Laura Jeanty, Sergo Jindariani, Sofia Johannesson, Benjamin Johnson, Owain Rhodri Jones, Paul-Bogdan Jurj, Yonatan Kahn, Rohan Kamath, Anna Kario, Ivan Karpov, David Kelliher, Wolfgang Kilian, Ryuichiro Kitano, Felix Kling, Antti Kolehmainen, K. C. Kong, Jaap Kosse, Jakub Kremer, Georgios Krintiras, Karol Krizka, Nilanjana Kumar, Erik Kvikne, Robert Kyle, Stephan Lachnit, Emanuele Laface, Kenneth Lane, Andrea Latina, Anton Lechner, Lawrence Lee, Junghyun Lee, Seh Wook Lee, Thibaut Lefevre, Emanuele Leonardi, Giuseppe Lerner, Gabriele Levati, Filippo Levi, Peiran Li, Qiang Li, Tong Li, Wei Li, Roberto Li Voti, Giulia Liberalato, Mats Lindroos, Ronald Lipton, Da Liu, Zhen Liu, Miaoyuan Liu, Alessandra Lombardi, Shivani Lomte, Kenneth Long, Luigi Longo, José Lorenzo, Roberto Losito, Ian Low, Xianguo Lu, Donatella Lucchesi, Tianhuan Luo, Anna Lupato, Yang Ma, Yang Ma, Shinji Machida, Edward MacTavish, Thomas Madlener, Lorenzo Magaletti, Marcello Maggi, Tommaso Maiello, Helene Mainaud Durand, Abhishikth Mallampalli, Fabio Maltoni, Jerzy Mikolaj Manczak, Marco Mandurrino, Claude Marchand, Francesco Mariani, Stefano Marin, Samuele Mariotto, Simon Marsh, Stewart Martin-Haugh, David Marzocca, Maria Rosaria Masullo, Giorgio Sebastiano Mauro, Anna Mazzacane, Andrea Mazzolari, Patrick Meade, Barbara Mele, Federico Meloni, Xiangwei Meng, Matthias Mentink, Rebecca Miceli, Natalia Milas, Abdollah Mohammadi, Dominik Moll, Francesco Montagno Bozzone, Alessandro Montella, Manuel Morales-Alvarado, Mauro Morandin, Marco Morrone, Tim Mulder, Riccardo Musenich, Toni Mäkelä, Elias Métral, Krzysztof Mękała, Emilio Nanni, Marco Nardecchia, Federico Nardi, Felice Nenna, David Neuffer, David Newbold, Daniel Novelli, Maja Olvegård, Yasar Onel, Domizia Orestano, Inaki Ortega Ruiz, John Osborne, Simon Otten, Yohan Mauricio Oviedo Torres, Daniele Paesani, Simone Pagan Griso, Davide Pagani, Kincso Pal, Mark Palmer, Leonardo Palombini, Alessandra Pampaloni, Paolo Panci, Priscilla Pani, Yannis Papaphilippou, Rocco Paparella, Paride Paradisi, Antonio Passeri, Jaroslaw Pasternak, Nadia Pastrone, Kevin Pedro, Antonello Pellecchia, Fulvio Piccinini, Henryk Piekarz, Tatiana Pieloni, Juliette Plouin, Alfredo Portone, Karolos Potamianos, Joséphine Potdevin, Soren Prestemon, Teresa Puig, Ji Qiang, Lionel Quettier, Tanjona Radonirina Rabemananjara, Emilio Radicioni, Raffaella Radogna, Ilaria Carmela Rago, Angira Rastogi, Andris Ratkus, Elodie Resseguie, Juergen Reuter, Pier Luigi Ribani, Cristina Riccardi, Stefania Ricciardi, Tania Robens, Youri Robert, Chris Rogers, Juan Rojo, Marco Romagnoni, Kevin Ronald, Benjamin Rosser, Carlo Rossi, Lucio Rossi, Leo Rozanov, Maximilian Ruhdorfer, Richard Ruiz, Farinaldo S. Queiroz, Saurabh Saini, Filippo Sala, Claudia Salierno, Tiina Salmi, Paola Salvini, Ennio Salvioni, Nicholas Sammut, Carlo Santini, Alessandro Saputi, Ivano Sarra, Giuseppe Scarantino, Hans Schneider-Muntau, Daniel Schulte, Jessica Scifo, Sally Seidel, Claudia Seitz, Tanaji Sen, Carmine Senatore, Abdulkadir Senol, Daniele Sertore, Lorenzo Sestini, Vladimir Shiltsev, Ricardo César Silva Rêgo, Federica Maria Simone, Kyriacos Skoufaris, Elise Sledge, Valentina Sola, Gino Sorbello, Massimo Sorbi, Stefano Sorti, Lisa Soubirou, Simon Spannagel, David Spataro, Anna Stamerra, Marcel Stanitzki, Steinar Stapnes, Giordon Stark, Marco Statera, Bernd Stechauner, Shufang Su, Wei Su, Ben Suitters, Xiaohu Sun, Alexei Sytov, Yoxara Sánchez Villamizar, Jingyu Tang, JINGYU TANG, Jian Tang, Rebecca Taylor, Herman Ten Kate, Pietro Testoni, Leonard Sebastian Thiele, Rogelio Tomas Garcia, Max Topp-Mugglestone, Toms Torims, Toms Torims, Riccardo Torre, Luca Tortora, Ludovico Tortora, Luca Tricarico, Sokratis Trifinopoulos, Donato Troiano, Alexander Naip Tuna, Sosoho-Abasi Udongwo, Ilaria Vai, Riccardo Umberto Valente, Giorgio Vallone, Ursula van Rienen, Rob Van Weelderen, Marion Vanwelde, Gueorgui Velev, Rosamaria Venditti, Adam Vendrasco, Adriano Verna, Gianluca Vernassa, Arjan Verweij, Piet Verwilligen, Ludovico Vittorio, Paolo Vitulo, Isabella Vojskovic, Biao Wang, Dayong Wang, Lian-Tao Wang, Xing Wang, Xing Wang, Manfred Wendt, Robert Stephen White, Markus Widorski, Mariusz Wozniak, Juliet Wright, Yongcheng Wu, Andrea Wulzer, Keping Xie, Yifeng Yang, Yee Chinn Yap, Katsuya Yonehara, Hwi Dong Yoo, Zhengyun You, Zaib Un Nisa, Marco Zanetti, Angela Zaza, Jinlong Zhang, Liang Zhang, Ruihu Zhu, Alexander Zlobin, Davide Zuliani, José Francisco Zurita
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
Jan Kalinowski, Wojciech Kotlarski, Krzysztof Mekala, Kamil Zembaczynski, Aleksander Filip Zarnecki
High energy e$^+$e$^-$ colliders offer unique possibility for the most general dark matter search based on the mono-photon signature. Analysis of the energy spectrum and angular distributions of photons from the initial state radiation can be used to search for hard processes with invisible final state production. Most studies in the past focused on scenarios assuming heavy mediator exchange. We notice however, that scenarios with light mediator exchange are still not excluded by existing experimental data, if the mediator coupling to Standard Model particles is very small. We proposed a novel approach, where the experimental sensitivity to light mediator production is defined in terms of both the mediator mass and mediator width. This approach is more model independent than the approach assuming given mediator coupling values to SM and DM particles. Summarised in this contribution are published results of our studies concerning simulation of mono-photon events with WHIZARD and the expected sensitivity of the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments to dark matter production.
Jürgen Reuter, Pia Bredt, Marius Höfer, Wolfgang Kilian, Nils Kreher, Maximilian Löschner, Krzysztof Mękała, Thorsten Ohl, Tobias Striegl, Aleksander Filip Żarnecki
We give a status report on new developments within the Whizard event generator. Important new features comprise NLO electroweak automation (incl. extension to BSM processes like SMEFT), loop-induced processes and new developments in the UFO interface. We highlight work in progress and further plans, such as the implementation of electroweak PDFs, photon radiation, the exclusive top threshold and features for exotic new physics searches.
Rebecca Taylor, Antoine Chancé, Dario Augusto Giove, Natalia Milas, Roberto Losito, Donatella Lucchesi, Chris Rogers, Lucio Rossi, Daniel Schulte, Carlotta Accettura, Simon Adrian, Rohit Agarwal, Claudia Ahdida, Chiara Aime, Avni Aksoy, Gian Luigi Alberghi, Simon Albright, Siobhan Alden, Luca Alfonso, Muhammad Ali, Anna Rita Altamura, Nicola Amapane, Kathleen Amm, David Amorim, Paolo Andreetto, Fabio Anulli, Ludovica Aperio Bella, Rob Appleby, Artur Apresyan, Pouya Asadi, Mohammed Attia Mahmoud, Bernhard Auchmann, John Back, Anthony Badea, Kyu Jung Bae, E. J. Bahng, Lorenzo Balconi, Fabrice Balli, Laura Bandiera, Carmelo Barbagallo, Daniele Barducci, Roger Barlow, Camilla Bartoli, Nazar Bartosik, Emanuela Barzi, Fabian Batsch, Matteo Bauce, Michael Begel, J. Scott Berg, Andrea Bersani, Alessandro Bertarelli, Francesco Bertinelli, Alessandro Bertolin, Pushpalatha Bhat, Clarissa Bianchi, Michele Bianco, William Bishop, Kevin Black, Fulvio Boattini, Alex Bogacz, Maurizio Bonesini, Bernardo Bordini, Patricia Borges de Sousa, Salvatore Bottaro, Luca Bottura, Steven Boyd, Johannes Braathen, Marco Breschi, Francesco Broggi, Matteo Brunoldi, Xavier Buffat, Laura Buonincontri, Marco Buonsante, Philip Nicholas Burrows, Graeme Campbell Burt, Dario Buttazzo, Barbara Caiffi, Ilkay Turk Cakir, Orhan Cakir, Rama Calaga, Sergio Calatroni, Marco Calviani, Simone Calzaferri, Daniele Calzolari, Kyle Capobianco-Hogan, Vieri Candelise, Silvio Candido, Ali Can Canbay, Claudio Cantone, Rodolfo Capdevilla, Christian Carli, Carlo Carrelli, Fausto Casaburo, Massimo Casarsa, Luca Castelli, Maria Gabriella Catanesi, Lorenzo Cavallucci, Gianluca Cavoto, Francesco Giovanni Celiberto, Luigi Celona, Alessia Cemmi, Sergio Ceravolo, Alessandro Cerri, Francesco Cerutti, Gianmario Cesarini, Cari Cesarotti, Nikolaos Charitonidis, mauro chiesa, Paolo Chiggiato, Vittoria Ludovica Ciccarella, Pietro Cioli Puviani, Anna Colaleo, Francesco Colao, Francesco Collamati, Marco Costa, Nathaniel Craig, David Curtin, Laura D'Angelo, Giacomo Da Molin, Heiko Damerau, Sridhara Dasu, Jorge de Blas, Stefania De Curtis, Herbert De Gersem, Andre de Gouvea, Tommaso Del Moro, Jean-Pierre Delahaye, Dmitri Denisov, Haluk Denizli, Radovan Dermisek, Paula Desiré Valdor, Charlotte Desponds, Luca Di Luzio, Elisa Di Meco, Karri Folan Di Petrillo, Ilaria Di Sarcina, Eleonora Diociaiuti, Tommaso Dorigo, Karlis Dreimanis, Tristan du Pree, Hatice Duran Yildiz, Juhi Dutta, Thomas Edgecock, Mamad Eshraqi, Siara Fabbri, Marco Fabbrichesi, Stefania Farinon, Davide Fazioli, Javier Fernandez Roncal, Guillaume Ferrand, Samuel Ferraro, Jose Antonio Ferreira Somoza, Marco Ferrero, Max Fieg, Frank Filthaut, Patrick Fox, Roberto Franceschini, Rui Franqueira Ximenes, Frank Gaede, Simone Galletto, Michele Gallinaro, Maurice Garcia-Sciveres, Luis Garcia-Tabares, Rocky Bala Garg, Ruben Gargiulo, Cedric Garion, Maria Vittoria Garzelli, Marco Gast, Lisa Generoso, Cecilia E. Gerber, Luca Giambastiani, Alessio Gianelle, Eliana Gianfelice-Wendt, Stephen Gibson, Simone Gilardoni, Valentina Giovinco, Carlo Giraldin, Alfredo Glioti, Arkadiusz Gorzawski, Mario Greco, Christophe Grojean, Alexej Grudiev, Edda Gschwendtner, Emanuele Gueli, Nicolas Guilhaudin, Tao Han, Chengcheng Han, John Michael Hauptman, Matthew Herndon, Adrian D Hillier, Micah Hillman, Gabriela Hoff, Tova Ray Holmes, Samuel Homiller, Walter Hopkins, Lennart Huth, Sudip Jana, Laura Jeanty, Sergo Jindariani, Sofia Johannesson, Benjamin Johnson, Owain Rhodri Jones, Paul-Bogdan Jurj, Yonatan Kahn, Rohan Kamath, Anna Kario, Ivan Karpov, David Kelliher, Wolfgang Kilian, Ryuichiro Kitano, Felix Kling, Antti Kolehmainen, K. C. Kong, Jaap Kosse, Jakub Kremer, Georgios Krintiras, Karol Krizka, Nilanjana Kumar, Erik Kvikne, Robert Kyle, Stephan Lachnit, Emanuele Laface, Elleanor Lamb, Kenneth Lane, Andrea Latina, Anton Lechner, Lawrence Lee, Junghyun Lee, Seh Wook Lee, Thibaut Lefevre, Emanuele Leonardi, Giuseppe Lerner, Gabriele Levati, Filippo Levi, Peiran Li, Qiang Li, Tong Li, Wei Li, Roberto Li Voti, Giulia Liberalato, Mats Lindroos, Ronald Lipton, Da Liu, Zhen Liu, Miaoyuan Liu, Alessandra Lombardi, Shivani Lomte, Kenneth Long, Luigi Longo, José Lorenzo, Ian Low, Xianguo Lu, Tianhuan Luo, Anna Lupato, Yang Ma, Shinji Machida, Edward MacTavish, Thomas Madlener, Lorenzo Magaletti, Marcello Maggi, Tommaso Maiello, Helene Mainaud Durand, Abhishikth Mallampalli, Fabio Maltoni, Jerzy Mikolaj Manczak, Marco Mandurrino, Claude Marchand, Francesco Mariani, Stefano Marin, Samuele Mariotto, Simon Marsh, Stewart Martin-Haugh, David Marzocca, Maria Rosaria Masullo, Giorgio Sebastiano Mauro, Anna Mazzacane, Andrea Mazzolari, Patrick Meade, Barbara Mele, Federico Meloni, Xiangwei Meng, Matthias Mentink, Rebecca Miceli, Abdollah Mohammadi, Dominik Moll, Francesco Montagno Bozzone, Alessandro Montella, Manuel Morales-Alvarado, Mauro Morandin, Marco Morrone, Tim Mulder, Riccardo Musenich, Toni Mäkelä, Elias Métral, Krzysztof Mękała, Emilio Nanni, Marco Nardecchia, Federico Nardi, Felice Nenna, David Neuffer, David Newbold, Daniel Novelli, Maja Olvegård, Yasar Onel, Domizia Orestano, Inaki Ortega Ruiz, John Osborne, Simon Otten, Yohan Mauricio Oviedo Torres, Daniele Paesani, Simone Pagan Griso, Davide Pagani, Kincso Pal, Mark Palmer, Leonardo Palombini, Alessandra Pampaloni, Paolo Panci, Priscilla Pani, Yannis Papaphilippou, Rocco Paparella, Paride Paradisi, Antonio Passeri, Jaroslaw Pasternak, Nadia Pastrone, Kevin Pedro, Antonello Pellecchia, Fulvio Piccinini, Henryk Piekarz, Tatiana Pieloni, Juliette Plouin, Alfredo Portone, Karolos Potamianos, Joséphine Potdevin, Soren Prestemon, Teresa Puig, Ji Qiang, Lionel Quettier, Tanjona Radonirina Rabemananjara, Emilio Radicioni, Raffaella Radogna, Ilaria Carmela Rago, Angira Rastogi, Andris Ratkus, Elodie Resseguie, Juergen Reuter, Pier Luigi Ribani, Cristina Riccardi, Stefania Ricciardi, Caroline Riggall, Tania Robens, Youri Robert, Juan Rojo, Marco Romagnoni, Kevin Ronald, Benjamin Rosser, Carlo Rossi, Leo Rozanov, Maximilian Ruhdorfer, Richard Ruiz, Farinaldo S. Queiroz, Saurabh Saini, Filippo Sala, Claudia Salierno, Tiina Salmi, Paola Salvini, Ennio Salvioni, Nicholas Sammut, Carlo Santini, Alessandro Saputi, Ivano Sarra, Giuseppe Scarantino, Hans Schneider-Muntau, Jessica Scifo, Sally Seidel, Claudia Seitz, Tanaji Sen, Carmine Senatore, Abdulkadir Senol, Daniele Sertore, Lorenzo Sestini, Vladimir Shiltsev, Ricardo César Silva Rêgo, Federica Maria Simone, Kyriacos Skoufaris, Elise Sledge, Valentina Sola, Gino Sorbello, Massimo Sorbi, Stefano Sorti, Lisa Soubirou, Simon Spannagel, David Spataro, Anna Stamerra, Marcel Stanitzki, Steinar Stapnes, Giordon Stark, Marco Statera, Bernd Stechauner, Shufang Su, Wei Su, Ben Suitters, Xiaohu Sun, Alexei Sytov, Yoxara Sánchez Villamizar, Jingyu Tang, Jian Tang, Herman Ten Kate, Pietro Testoni, Leonard Sebastian Thiele, Rogelio Tomas Garcia, Max Topp-Mugglestone, Toms Torims, Riccardo Torre, Luca Tortora, Ludovico Tortora, Luca Tricarico, Sokratis Trifinopoulos, Donato Troiano, Alexander Naip Tuna, Sosoho-Abasi Udongwo, Ilaria Vai, Riccardo Umberto Valente, Giorgio Vallone, Ursula van Rienen, Rob Van Weelderen, Marion Vanwelde, Gueorgui Velev, Rosamaria Venditti, Adam Vendrasco, Adriano Verna, Gianluca Vernassa, Arjan Verweij, Piet Verwilligen, Ludovico Vittorio, Paolo Vitulo, Isabella Vojskovic, Biao Wang, Dayong Wang, Lian-Tao Wang, Xing Wang, Manfred Wendt, Robert Stephen White, Markus Widorski, Mariusz Wozniak, Juliet Wright, Yongcheng Wu, Andrea Wulzer, Keping Xie, Yifeng Yang, Yee Chinn Yap, Katsuya Yonehara, Hwi Dong Yoo, Zhengyun You, Zaib Un Nisa, Marco Zanetti, Angela Zaza, Jinlong Zhang, Liang Zhang, Ruihu Zhu, Alexander Zlobin, Davide Zuliani, José Francisco Zurita
Bohdan Grzadkowski, Michal Iglicki, Krzysztof Mekala, Aleksander Filip Zarnecki
We discuss possibility to detect spin 0, 1 and 1/2 dark matter (DM) at future $e^{+} e^{-}$ colliders. The models considered here are simple, consistent and renormalizable field theories, that provide correct DM abundance and satisfy direct detection, indirect detection and collider constraints. The intention of this paper was to verify to what extend it might be possible to disentangle models of different DM spins by measurement of the cross section for $e^{+} e^{-} \to Z + \ldots\,$ at future $e^{+} e^{-}$ colliders. We specialize to the case of the ILC operating at $\sqrt{s} = 250~\text{GeV}$, however our results apply as well for the FCC-ee and the CEPC colliders. For each model the cross section maximized with respect to parameters was calculated and compared to the expected 95% CL cross-section limits estimated for the ILC. It turned out that near $2 m_{\text{DM}}\simeq m_{1,2}$ resonances, where $m_{1}$ and $m_{2}$ are the SM Higgs boson and a non-standard Higgs boson masses, respectively, there exist substantial regions where the models are testable. A special attention has been payed to calculation of the cross section in the region where $m_{1}\simeq m_{2}$.
Jan Kalinowski, Wojciech Kotlarski, Krzysztof Mekala, Pawel Sopicki, Aleksander Filip Zarnecki
As any $e^+e^-$ scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy $e^+e^-$ colliders offer a unique possibility for the most general search of dark matter (DM) based on the mono-photon signature. We consider production of DM particles at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments via a light mediator exchange. Detector effects are taken into account within the DELPHES fast simulation framework. Limits on the light DM production in a simplified model are set as a function of the mediator mass and width based on the expected two-dimensional distributions of the reconstructed mono-photon events. The experimental sensitivity is extracted in terms of the DM production cross section. Limits on the mediator couplings are then presented for a wide range of mediator masses and widths. For light mediators, for masses up to the centre-of-mass energy of the collider, coupling limits derived from the mono-photon analysis are more stringent than those expected from direct resonance searches in decay channels to SM particles.
Jan Kalinowski, Wojciech Kotlarski, Krzysztof Mekala, Pawel Sopicki, Aleksander Filip Zarnecki
As any e$^+$e$^-$ scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy e$^+$e$^-$ colliders offer a unique possibility for the most general search of Dark matter based on the mono-photon signature. We consider production of DM particles via a mediator at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments taking into account detector effects within the DELPHES fast simulation framework. Limits on the light DM production in a generic model are set for a wide range of mediator masses and widths. For mediator masses up to the centre-of-mass energy of the collider, results from the mono-photon analysis are more stringent than the limits expected from direct resonance searches in Standard Model decay channels.
Jürgen Reuter, Pia Bredt, Wolfgang Kilian, Maximilian Löschner, Krzysztof Mękała, Thorsten Ohl, Tobias Striegl, Aleksander Filip Żarnecki
We give a status report on new developments in the WHIZARD event generator, including NLO electroweak automation for $e^+e^-$ colliders, loop-induced processes, POWHEG matching, new features in the UFO interface and the current development for matching between exclusive photon radiation and fixed-order LO/NLO electroweak (EW) corrections. We report on several bug fixes relevant for certain aspects of the ILC250 Monte Carlo (MC) mass production, especially on the normalization of matching EPA samples with full-matrix element samples. Finally, we mention some ongoing work on efficiency improvements regarding parallelization of matrix elements and phase space sampling, as well as plans to revive the top threshold simulation.
Krzysztof Mękała, Daniel Jeans, Jürgen Reuter, Junping Tian, Aleksander Filip Żarnecki
Electroweak Precision Measurements are stringent tests of the Standard Model and sensitive probes to New Physics. Accurate studies of the $Z$-boson couplings to the first-generation quarks, which are currently constrained from LEP data to a few percent, could reveal potential discrepancies from the theory predictions. Future $e^+e^-$ colliders running at the $Z$-pole would be an excellent tool for an analysis based on a comparison of radiative and non-radiative $Z$ boson decays. In this paper, we present a method to extract the values of the $Z$ couplings to light quarks and discuss the uncertainty of the measurement, including contributions from various systematic effects. We show that systematic uncertainty in the heavy-flavour tagging performance is the key factor in the analysis and reducing it to a sub-permille level might be crucial to fully profit from the high luminosity of future $e^+e^-$ machines. The measurement could improve the LEP results by at least an order of magnitude.
Felix Kling, Yang Ma, Krzysztof Mękała, Jürgen Reuter, Zahra Tabrizi
In addition to their broad physics reach enabled by their high energies and precision, future multi-TeV muon colliders will also be the world's most intense sources of neutrinos. This offers the opportunity to search for new non-standard neutrino interactions, possible by installing a dedicated forward neutrino detector in the straight sections of the collision ring, which is then used to measure reactions initiated by neutrinos from the decaying beam muons. In this paper, we show that these searches can exceed current and upcoming bounds on non-standard neutrino interactions from low-energy precision experiments and the LHC. This is achieved by the large flux of high-energetic neutrinos, the precise knowledge of the neutrino flavor composition on each side of the interaction point and the chirality of the neutrinos. We further discuss the technical requirements of the proposed forward neutrino detector, \FASERmuC, to maximally exploit this physics potential.
Krzysztof Mekala, Aleksander Filip Zarnecki, Bohdan Grzadkowski, Michal Iglicki
We studied the possibility of measuring invisible Higgs boson decays at CLIC running at 380 GeV and 1.5 TeV. The analysis is based on the WHIZARD event generation and fast simulation of the CLIC detector response with DELPHES. We considered $e^+e^-$ background processes but also relevant $γγ$ and $γe^\pm$ interactions. The approach consisting of a two step analysis was used to optimize separation between signal and background processes. First, a set of preselection cuts was applied; then, multivariate analysis methods were employed to optimise the significance of observations. We estimated the expected limits on the invisible decays of the 125 GeV Higgs boson, as well as the cross section limits for production of an additional neutral Higgs-like scalar, assuming its invisible decays, as a function of its mass. Extracted model-independent branching ratio and cross section limits were then interpreted in the framework of the vector-fermion dark matter model to set limits on the mixing angle between the SM-like Higss boson and the new scalar of the "dark sector".
Krzysztof Mekala, Aleksander Filip Zarnecki, Bohdan Grzadkowski, Michal Iglicki
The Compact Linear Collider (CLIC) is a proposed TeV-scale high-luminosity electron-positron collider at CERN. The first CLIC running stage, at 380\,GeV, will focus on precision Higgs boson and top quark studies while the main aim of the subsequent high-energy stages, at 1.5 TeV and 3 TeV, is to extend the sensitivity of CLIC to different Beyond the Standard Model (BSM) scenarios. We studied the prospects for measuring invisible Higgs boson and additional heavy scalar decays using CLIC data at 380 GeV and 1.5 TeV. The analysis is based on the WHIZARD event generator, with fast simulation of the CLIC detector response parametrised by the DELPHES package. We present the expected limits for the invisible decays of the 125 GeV Higgs boson, the cross section limits for production of an additional neutral Higgs scalar, assuming its invisible decays, and limits on the mixing angle between the SM-like Higgs boson and the new scalar of the "dark sector" in the framework of the vector-fermion dark matter model.