Tommaso Dorigo, Pietro Vischia, Shahzaib Abbas, Tosin Adewumi, Lama Alkhaled, Lorenzo Arsini, Muhammad Awais, Maxim Borisyak, András Bóta, Florian Bury, Sascha Caron, James Carzon, Long Chen, Prakash C. Chhipa, Paul Christakopoulos, Jacopo De Piccoli, Andrea De Vita, Zlatan Dimitrov, Michele Doro, Luigi Favaro, Francesco Ferranti, Santiago Folgueras, Rihab Gargouri, Nicolas R. Gauger, Andrea Giammanco, Christian Glaser, Tobias Golling, João A. Gonçalves, Hui Han, Hamza Hanif, Lukas Heinrich, Yan Chai Hum, Florent Imbert, Andreas Ipp, Michael Kagan, Noor Kainat Syeda, Rukshak Kapoor, Aparup Khatua, Eduard J. Kerkhoven, Jan Kieseler, Tobias Kortus, Ashish Kumar Singh, Marius S. Köppel, Daniel Lanchares, Ann Lee, Pelayo Leguina, Christos Leonidopoulos, Giuseppe Levi, Boying Li, Chang Liu, Marcus Liwicki, Karl Lowenmark, Enrico Lupi, Carlo Mancini-Terracciano, Dominik Maršík, Leonidas Matsakas, Hamam Mokayed, Federico Nardi, Amirhossein Nayebiastaneh, Xuan T. Nguyen, Aitor Orio, Jingjing Pan, Jigar Patel, Carmelo Pellegrino, María Pereira Martínez, Karolos Potamianos, Shah Rukh Qasim, Martin Ravn, Luis Recabarren Vergara, Humberto Reyes-González, Hipolito A. Riveros Guevara, Ippocratis D. Saltas, Rajkumar Saini, Fredrik Sandin, Alexander Schilling, Kylian Schmidt, Nicola Serra, Saqib Shahzad, Foteini Simistira Liwicki, Giles C. Strong, Kristian Tchiorniy, Mia Tosi, Andrey Ustyuzhanin, Xabier Cid Vidal, Kinga A. Wozniak, Mengqing Wu, Zahraa Zaher
The optimization of large experiments in fundamental science, such as detectors for subnuclear physics at particle colliders, shares with the optimization of complex systems for industrial or societal applications the common issue of addressing the inter-relation between parameters describing the hardware used in data production and parameters used to analyse those data. While in many cases this coupling can be ignored -- when the problem can be successfully factored into simpler sub-tasks and the latter addressed serially -- there are situations in which that approach fails to converge to the absolute maximum of expected performance, as it results in a mis-alignment of the optimized hardware and software solutions. In this work we consider a few use cases of interest in fundamental science collected primarily from particle physics and related areas, and a pot-pourri of industrial and societal applications where the matter is similarly of relevance. We discuss the emergence of strong hardware-software coupling in some of those systems, as well as co-design procedures that may be deployed to identify the global maximum of their relevant utility functions. We observe how numerous opportunities exist to advance methods and tools for hardware-software co-design optimization, bridging fundamental science and industry through application- and challenge-driven projects, and shaping the future of scientific experiments and industrial systems.
Diogo Buarque Franzosi, Giacomo Cacciapaglia, Xabier Cid Vidal, Gabriele Ferretti, Thomas Flacke, Carlos Vázquez Sierra
We study the possibility of observing a light pseudo-scalar $a$ at LHCb. We target the mass region $1 \lesssim m_a \lesssim 60$ GeV and various decay channels, some of which have never been considered before: muon pairs, tau pairs, $D$ meson pairs, and di-photon. We interpret the results in the context of models of 4D Composite Higgs and Partial Compositeness in particular.
Xabier Cid Vidal, Miguel Fernández Gómez, Matthew Low, Alejandro Novo Cal, Yuhsin Tsai, Carlos Vázquez Sierra
Quirks are heavy particles connected by a flux tube from a hidden confining force that remain weakly constrained in large regions of their parameter space. This flux tube acts as a string that, at short enough distance, stretches as the quirk pair separates, then pulls the pair back together leading to interesting dynamics. We propose a novel search using the LHCb Vertex Locator (VELO), whose forward geometry and software-based trigger are uniquely suited to detecting the characteristic back-to-back, planar hit patterns produced by quirk pairs with little transverse recoil. Using detailed simulations of the VELO geometry, together with simple geometric selections, we present different sensitivity projections, demonstrating that LHCb can probe parameter regions inaccessible to existing ATLAS and CMS searches and offering a powerful, complementary path toward discovering quirks.
Giulio Aielli, Juliette Alimena, Saul Balcarcel-Salazar, Eli Ben Haim, András Barnabás Burucs, Roberto Cardarelli, Matthew J. Charles, Xabier Cid Vidal, Albert De Roeck, Biplab Dey, Silviu Dobrescu, Ozgur Durmus, Mohamed Elashri, Vladimir V. Gligorov, Rebeca Gonzalez Suarez, Zarria Gray, Conor Henderson, Louis Henry, Philip Ilten, Daniel Johnson, Jacob Kautz, Simon Knapen, Bingxuan Liu, Yang Liu, Saul López Soliño, Pablo Eduardo Menéndez-Valdés Pérez, Titus Mombächer, Benjamin Nachman, David T. Northacker, Gabriel M. Nowak, Michele Papucci, Gabriella Pásztor, María Pereira Martínez, Michael Peters, Jake Pfaller, Luca Pizzimento, Máximo Pló Casasús, Gian Andrea Rassati, Dean J. Robinson, Emilio Xosé Rodríguez Fernández, Debashis Sahoo, Sinem Simsek, Michael D. Sokoloff, Joeal Subash, James Swanson, Abhinaba Upadhyay, Riccardo Vari, Carlos Vázquez Sierra, Gábor Veres, Nigel Watson, Michael K. Wilkinson, Michael Williams, Eleanor Winkler
This document is written as a contribution to the European Strategy of Particle Physics (ESPP) update. We offer a detailed overview of current developments and future directions for the CODEX-b detector, which aims to detect long-lived particles beyond the Standard Model. We summarize the scientific motivation for this detector, advances in our suite of simulation and detector optimization frameworks, and examine expected challenges, costs, and timelines in realizing the full detector. Additionally, we describe the technical specifications for the smaller-scale demonstrator detector (CODEX-$β$) we have installed in the LHCb experimental cavern.
Xabier Cid Vidal, Alberto Mariotti, Diego Redigolo, Filippo Sala, Kohsaku Tobioka
We assess the impact of searches at flavor factories for new neutral resonances that couple to both photons and gluons. These are well motivated by "heavy axion" solutions of the strong CP problem and by frameworks addressing both Dark Matter and the Higgs hierarchy problem. We use LHCb public diphoton data around the Bs mass to derive the current best limit on these resonances for masses between 4.9 and 6.3 GeV. We estimate that a future LHCb dedicated search would test an axion decay constant of O(TeV) for axion masses in the few-to-tens of GeV, being fully complementary to the low mass ATLAS and CMS searches. We also derive the impact of BABAR searches based on Upsilon decays and the future Belle-II reach.
Alexandre Brea Rodríguez, Veronika Chobanova, Xabier Cid Vidal, Saúl López Soliño, Diego Martínez Santos, Titus Mombächer, Claire Prouvé, Emilio Xosé Rodríguez Fernández, Carlos Vázquez Sierra
A model that can simultaneously explain Dark Matter relic density and the apparent matter anti-matter imbalance of the universe has been recently proposed. The model requires $b$-hadron branching fractions to Dark Matter at the per mille level. The $b$-hadrons decay to a dark sector baryon, $ψ_{\rm{DS}}$, which has a mass in the region $940$ MeV/c$^{2} \leq m(ψ_{\rm{DS}}) \leq 4430$ MeV/c$^{2}$. In this paper, we discuss the sensitivity of the LHCb experiment to search for this dark baryon, covering different types of topology and giving prospects for Runs 3 and 4 of the LHC, as well as for the proposed Phase-II Upgrade. We show that the LHCb experiment can cover the entire mass range of the hypothetical dark baryon.
Martino Borsato, Xabier Cid Vidal, Yuhsin Tsai, Carlos Vázquez Sierra, José Zurita, Gonzalo Alonso-Álvarez, Alexey Boyarsky, Alexandre Brea Rodríguez, Diogo Buarque Franzosi, Giacomo Cacciapaglia, Adrián Casais Vidal, Mingxuan Du, Gilly Elor, Miguel Escudero, Gabriele Ferretti, Thomas Flacke, Patrick Foldenauer, Jan Hajer, Louis Henry, Philip Ilten, Jernej Kamenik, Brij Kishor Jashal, Simon Knapen, Federico Leo Redi, Matthew Low, Zuowei Liu, Arantza Oyanguren Campos, Erica Polycarpo, Maria Ramos, Miguel Ramos Pernas, Ennio Salvioni, Murilo Santana Rangel, Ruth Schäfer, Lorenzo Sestini, Yotam Soreq, Van Que Tran, Inar Timiryasov, Maarten van Veghel, Susanne Westhoff, Michael Williams, Jure Zupan
In this paper, we describe the potential of the LHCb experiment to detect Stealth physics. This refers to dynamics beyond the Standard Model that would elude searches that focus on energetic objects or precision measurements of known processes. Stealth signatures include long-lived particles and light resonances that are produced very rarely or together with overwhelming backgrounds. We will discuss why LHCb is equipped to discover this kind of physics at the Large Hadron Collider and provide examples of well-motivated theoretical models that can be probed with great detail at the experiment.
Xabier Cid Vidal, Lorena Dieste Maroñas, Álvaro Dósil Suárez
The popularity of Machine Learning (ML) has been increasing in the last decades in almost every area, being the commercial and scientific fields the most notorious ones. Concerning particle physics, ML has been proved as a useful resource to make the most of projects such as the Large Hadron Collider (LHC). The main advantage provided by ML is reducing the time and effort put into the measurements done by experiments, while improving the performance. With this work we aim to encourage scientists at particle colliders to use ML and to try the different alternatives we have available nowadays, focusing in the separation between signal and background. We assess some of the most used libraries in the field, like Toolkit for Multivariate Data Analysis with ROOT, and also newer and more sophisticated options like PyTorch and Keras. We also check how optimal are some of the most common algorithms for signal-background discrimination, such as Boosted Decision Trees, and propose the use of others, namely Neural Networks. We compare the overall performance of different algorithms and libraries in simulated LHC data and produce some guidelines to help analysts deal with different situations. Examples are the use of low or high-level features from particle detectors or the amount of statistics available for training the algorithms.
Xabier Cid Vidal, Yuhsin Tsai, Jose Zurita
The LHCb detector provides accurate vertex reconstruction and hadronic particle identification, which make the experiment an ideal place to look for light long-lived particles (LLP) decaying into Standard Model (SM) hadrons. In contrast with the typical search strategy relying on energetic jets and a high multiplicity of tracks from the LLP decay, LHCb can identify LLPs in exclusive, specific hadronic final states. To illustrate the idea, we study the sensitivity of LHCb to an exotic Higgs decay $h\to SS$, followed by the displaced decay of GeV-scale scalars into charged kaons $S\to K^+K^-$. We show that the reconstruction of kaon vertices in narrow invariant mass windows can efficiently eliminate the combinatorial backgrounds from $B$-meson decays. While the same signal is extremely difficult to probe in the existing displaced jet searches at ATLAS/CMS, the LHCb search we propose can probe the branching ratio BR$(h\to SS)$ down to $0.1\%$ ($0.02\%$) level with $15$ ($300$) fb$^{-1}$ of data. We also apply this projected bound to two scenarios with Higgs portal couplings, where the scalar mediator $S$ either couples to a) the SM quarks only, or b) to both quarks and leptons in the minimal flavor violation paradigm. In both scenarios we compare the reach of our proposed search with the expected constraints from ATLAS and CMS on the invisible Higgs width and with the constraints from rare B-decays studies at LHCb. We find that for 1 GeV $< m_S < $ 2 GeV and $0.5~{\rm mm} \lesssim c τ\lesssim 10$ mm our proposed search will be competitive with the ATLAS and CMS projections, while at the same time providing crucial information of the hadronic interactions of $S$, which can not be obtained from the {\it indirect} measurement of the Higgs invisible width.
Sean Benson, Adrián Casais Vidal, Xabier Cid Vidal, Albert Puig Navarro
ALP-mediated decays and other as-yet unobserved $B$ decays to di-photon final states are a challenge to select in hadron collider environments due to the large backgrounds that come directly from the $pp$ collision. We present the strategy implemented by the LHCb experiment in 2018 to efficiently select such photon pairs. A fast neural network topology, implemented in the LHCb real-time selection framework achieves high efficiency across a mass range of $4-20$ GeV$/c^{2}$. We discuss implications and future prospects for the LHCb experiment.
ECFA Early-Career Researcher Panel, :, Anamika Aggarwal, Chiara Amendola, Liliana Apolinario, Jan-Hendrik Arling, Adi Ashkenazi, Kamil Augsten, Julien Baglio, Evelin Bakos, Liron Barak, Diogo Bastos, Bugra Bilin, Silvia Biondi, Neven Blaskovic Kraljevic, Lydia Brenner, Francesco Brizioli, Antoine Camper, Alessandra Camplani, Xabier Cid Vidal, Hüseyin Dag, Flavia de Almeida Dias, Eleonora Diociaiuti, Lennart van Doremalen, Katherine Dunne, Filip Erhardt, Pedro Fernández Manteca, Andrei Alexandru Geanta, Stefan Alexandru Ghinescu, Loukas Gouskos, Andrej Herzan, Viktoria Hinger, Bojan Hiti, Armin Ilg, Gianluca Inguglia, Adrián Irles, Hendrik Jansen, Kateřina Jarkovská, Lucia Keszeghova, Henning Kirschenmann, Sotiroulla Konstantinou, Magdalena Kuich, Neelam Kumari, Katarína Křížková Gajdošová, Aleksandra Lelek, Jeanette Lorenz, Ana Luisa Carvalho, Jakub Malczewski, Giada Mancini, Alexander Mann, Laura Martikainen, Émilie Maurice, Seán Mee, Predrag Milenovic, Vukasin Milosevic, Zuzana Moravcova, Laura Moreno Valero, Louis Moureaux, Heikki Mäntysaari, Nikiforos Nikiforou, Younes Otarid, Alex Pearce, Michael Pitt, Vlad-Mihai Placinta, Giulia Ripellino, Bryn Roberts, Luka Šantelj, Steven Schramm, Mariana Shopova, Kirill Skovpen, Aleks Smolkovič, Gamze Sokmen, Paweł Sznajder, Abigail Victoria Waldron, Sarah Williams, Valentina Zaccolo, Manuel Zeyen
The European Committee for Future Accelerators (ECFA) Early-Career Researchers (ECR) Panel was invited by the ECFA Detector R&D Roadmap conveners to collect feedback from the European ECR community. A working group within the ECFA ECR panel held a Townhall Meeting to get first input, and then designed and broadly circulated a detailed survey to gather feedback from the larger ECR community. A total of 473 responses to this survey were received, providing a useful overview of the experiences of ECRs in instrumentation training and related topics. This report summarises the feedback received, and is intended to serve as an input to the ECFA Detector R&D Roadmap process.
X. Cid Vidal
These proceedings present the LHCb results on Majorana neutrino searches and direct production of exotic particles using the data collected during Run I of LHC. For the former, Majorana neutrinos are searched for both on-shell and off-shell in $B$ and $D$ decays to final states with two same-sign muons. For the latter, different types of new particles are studied profiting the unique coverage of LHCb with respect to other detectors.
X. Cid Vidal
A short summary of the LHCb muon identification procedure is given in this article. First, the muon system of LHCb is presented, together with some examples of physics measurements of the experiment where the muon identification is crucial. Then, the muon identification algorithm is introduced in three single steps. With this, the efficiency vs. misidentification rate is shown for MC simulated data. The way this method will be calibrated with real data is also seen. Finally, some preliminary muon identification results with proton-proton collisions at sqrt(s) = 900 GeV are presented.
X. Cid Vidal
LHCb, while purpose built for $b-$physics, also functions as a general purpose forward detector, covering the pseudo-rapidity range 2.0 to 5.0. LHCb has performed several measurements including jets, which concern, e.g., QCD, top and Higgs physics. A selection of LHCb results in this area will be presented, focusing on the most recent ones.
LHCb collaboration, R. Aaij, C. Abellan Beteta, A. Adametz, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, Z. Ajaltouni, J. Albrecht, F. Alessio, M. Alexander, S. Ali, G. Alkhazov, P. Alvarez Cartelle, A. A. Alves, S. Amato, Y. Amhis, L. Anderlini, J. Anderson, R. B. Appleby, O. Aquines Gutierrez, F. Archilli, A. Artamonov, M. Artuso, E. Aslanides, G. Auriemma, S. Bachmann, J. J. Back, C. Baesso, W. Baldini, R. J. Barlow, C. Barschel, S. Barsuk, W. Barter, A. Bates, Th. Bauer, A. Bay, J. Beddow, I. Bediaga, S. Belogurov, K. Belous, I. Belyaev, E. Ben-Haim, M. Benayoun, G. Bencivenni, S. Benson, J. Benton, A. Berezhnoy, R. Bernet, M. -O. Bettler, M. van Beuzekom, A. Bien, S. Bifani, T. Bird, A. Bizzeti, P. M. Bjørnstad, T. Blake, F. Blanc, C. Blanks, J. Blouw, S. Blusk, A. Bobrov, V. Bocci, A. Bondar, N. Bondar, W. Bonivento, S. Borghi, A. Borgia, T. J. V. Bowcock, C. Bozzi, T. Brambach, J. van den Brand, J. Bressieux, D. Brett, M. Britsch, T. Britton, N. H. Brook, H. Brown, A. Büchler-Germann, I. Burducea, A. Bursche, J. Buytaert, S. Cadeddu, O. Callot, M. Calvi, M. Calvo Gomez, A. Camboni, P. Campana, A. Carbone, G. Carboni, R. Cardinale, A. Cardini, L. Carson, K. Carvalho Akiba, G. Casse, M. Cattaneo, Ch. Cauet, M. Charles, Ph. Charpentier, P. Chen, N. Chiapolini, M. Chrzaszcz, K. Ciba, X. Cid Vidal, G. Ciezarek, P. E. L. Clarke, M. Clemencic, H. V. Cliff, J. Closier, C. Coca, V. Coco, J. Cogan, E. Cogneras, P. Collins, A. Comerma-Montells, A. Contu, A. Cook, M. Coombes, G. Corti, B. Couturier, G. A. Cowan, D. Craik, S. Cunliffe, R. Currie, C. D'Ambrosio, P. David, P. N. Y. David, I. De Bonis, K. De Bruyn, S. De Capua, M. De Cian, J. M. De Miranda, L. De Paula, P. De Simone, D. Decamp, M. Deckenhoff, H. Degaudenzi, L. Del Buono, C. Deplano, D. Derkach, O. Deschamps, F. Dettori, A. Di Canto, J. Dickens, H. Dijkstra, P. Diniz Batista, F. Domingo Bonal, S. Donleavy, F. Dordei, A. Dosil Suárez, D. Dossett, A. Dovbnya, F. Dupertuis, R. Dzhelyadin, A. Dziurda, A. Dzyuba, S. Easo, U. Egede, V. Egorychev, S. Eidelman, D. van Eijk, S. Eisenhardt, R. Ekelhof, L. Eklund, I. El Rifai, Ch. Elsasser, D. Elsby, D. Esperante Pereira, A. Falabella, C. Färber, G. Fardell, C. Farinelli, S. Farry, V. Fave, V. Fernandez Albor, F. Ferreira Rodrigues, M. Ferro-Luzzi, S. Filippov, C. Fitzpatrick, M. Fontana, F. Fontanelli, R. Forty, O. Francisco, M. Frank, C. Frei, M. Frosini, S. Furcas, A. Gallas Torreira, D. Galli, M. Gandelman, P. Gandini, Y. Gao, J-C. Garnier, J. Garofoli, J. Garra Tico, L. Garrido, C. Gaspar, R. Gauld, E. Gersabeck, M. Gersabeck, T. Gershon, Ph. Ghez, V. Gibson, V. V. Gligorov, C. Göbel, D. Golubkov, A. Golutvin, A. Gomes, H. Gordon, M. Grabalosa Gándara, R. Graciani Diaz, L. A. Granado Cardoso, E. Graugés, G. Graziani, A. Grecu, E. Greening, S. Gregson, O. Grünberg, B. Gui, E. Gushchin, Yu. Guz, T. Gys, C. Hadjivasiliou, G. Haefeli, C. Haen, S. C. Haines, S. Hall, T. Hampson, S. Hansmann-Menzemer, N. Harnew, S. T. Harnew, J. Harrison, P. F. Harrison, T. Hartmann, J. He, V. Heijne, K. Hennessy, P. Henrard, J. A. Hernando Morata, E. van Herwijnen, E. Hicks, D. Hill, M. Hoballah, P. Hopchev, W. Hulsbergen, P. Hunt, T. Huse, N. Hussain, R. S. Huston, D. Hutchcroft, D. Hynds, V. Iakovenko, P. Ilten, J. Imong, R. Jacobsson, A. Jaeger, M. Jahjah Hussein, E. Jans, F. Jansen, P. Jaton, B. Jean-Marie, F. Jing, M. John, D. Johnson, C. R. Jones, B. Jost, M. Kaballo, S. Kandybei, M. Karacson, T. M. Karbach, J. Keaveney, I. R. Kenyon, U. Kerzel, T. Ketel, A. Keune, B. Khanji, Y. M. Kim, O. Kochebina, V. Komarov, R. F. Koopman, P. Koppenburg, M. Korolev, A. Kozlinskiy, L. Kravchuk, K. Kreplin, M. Kreps, G. Krocker, P. Krokovny, F. Kruse, M. Kucharczyk, V. Kudryavtsev, T. Kvaratskheliya, V. N. La Thi, D. Lacarrere, G. Lafferty, A. Lai, D. Lambert, R. W. Lambert, E. Lanciotti, G. Lanfranchi, C. Langenbruch, T. Latham, C. Lazzeroni, R. Le Gac, J. van Leerdam, J. -P. Lees, R. Lefèvre, A. Leflat, J. Lefrançois, O. Leroy, T. Lesiak, Y. Li, L. Li Gioi, M. Liles, R. Lindner, C. Linn, B. Liu, G. Liu, J. von Loeben, J. H. Lopes, E. Lopez Asamar, N. Lopez-March, H. Lu, J. Luisier, A. Mac Raighne, F. Machefert, I. V. Machikhiliyan, F. Maciuc, O. Maev, J. Magnin, M. Maino, S. Malde, G. Manca, G. Mancinelli, N. Mangiafave, U. Marconi, R. Märki, J. Marks, G. Martellotti, A. Martens, L. Martin, A. Martín Sánchez, M. Martinelli, D. Martinez Santos, A. Massafferri, Z. Mathe, C. Matteuzzi, M. Matveev, E. Maurice, A. Mazurov, J. McCarthy, G. McGregor, R. McNulty, M. Meissner, M. Merk, J. Merkel, D. A. Milanes, M. -N. Minard, J. Molina Rodriguez, S. Monteil, D. Moran, P. Morawski, R. Mountain, I. Mous, F. Muheim, K. Müller, R. Muresan, B. Muryn, B. Muster, J. Mylroie-Smith, P. Naik, T. Nakada, R. Nandakumar, I. Nasteva, M. Needham, N. Neufeld, A. D. Nguyen, C. Nguyen-Mau, M. Nicol, V. Niess, N. Nikitin, T. Nikodem, A. Nomerotski, A. Novoselov, A. Oblakowska-Mucha, V. Obraztsov, S. Oggero, S. Ogilvy, O. Okhrimenko, R. Oldeman, M. Orlandea, J. M. Otalora Goicochea, P. Owen, B. K. Pal, A. Palano, M. Palutan, J. Panman, A. Papanestis, M. Pappagallo, C. Parkes, C. J. Parkinson, G. Passaleva, G. D. Patel, M. Patel, G. N. Patrick, C. Patrignani, C. Pavel-Nicorescu, A. Pazos Alvarez, A. Pellegrino, G. Penso, M. Pepe Altarelli, S. Perazzini, D. L. Perego, E. Perez Trigo, A. Pérez-Calero Yzquierdo, P. Perret, M. Perrin-Terrin, G. Pessina, K. Petridis, A. Petrolini, A. Phan, E. Picatoste Olloqui, B. Pie Valls, B. Pietrzyk, T. Pilař, D. Pinci, S. Playfer, M. Plo Casasus, F. Polci, G. Polok, A. Poluektov, E. Polycarpo, D. Popov, B. Popovici, C. Potterat, A. Powell, J. Prisciandaro, V. Pugatch, A. Puig Navarro, W. Qian, J. H. Rademacker, B. Rakotomiaramanana, M. S. Rangel, I. Raniuk, N. Rauschmayr, G. Raven, S. Redford, M. M. Reid, A. C. dos Reis, S. Ricciardi, A. Richards, K. Rinnert, V. Rives Molina, D. A. Roa Romero, P. Robbe, E. Rodrigues, P. Rodriguez Perez, G. J. Rogers, S. Roiser, V. Romanovsky, A. Romero Vidal, J. Rouvinet, T. Ruf, H. Ruiz, G. Sabatino, J. J. Saborido Silva, N. Sagidova, P. Sail, B. Saitta, C. Salzmann, B. Sanmartin Sedes, M. Sannino, R. Santacesaria, C. Santamarina Rios, R. Santinelli, E. Santovetti, M. Sapunov, A. Sarti, C. Satriano, A. Satta, M. Savrie, P. Schaack, M. Schiller, H. Schindler, S. Schleich, M. Schlupp, M. Schmelling, B. Schmidt, O. Schneider, A. Schopper, M. -H. Schune, R. Schwemmer, B. Sciascia, A. Sciubba, M. Seco, A. Semennikov, K. Senderowska, I. Sepp, N. Serra, J. Serrano, P. Seyfert, M. Shapkin, I. Shapoval, P. Shatalov, Y. Shcheglov, T. Shears, L. Shekhtman, O. Shevchenko, V. Shevchenko, A. Shires, R. Silva Coutinho, T. Skwarnicki, N. A. Smith, E. Smith, M. Smith, K. Sobczak, F. J. P. Soler, A. Solomin, F. Soomro, D. Souza, B. Souza De Paula, B. Spaan, A. Sparkes, P. Spradlin, F. Stagni, S. Stahl, O. Steinkamp, S. Stoica, S. Stone, B. Storaci, M. Straticiuc, U. Straumann, V. K. Subbiah, S. Swientek, M. Szczekowski, P. Szczypka, T. Szumlak, S. T'Jampens, M. Teklishyn, E. Teodorescu, F. Teubert, C. Thomas, E. Thomas, J. van Tilburg, V. Tisserand, M. Tobin, S. Tolk, S. Topp-Joergensen, N. Torr, E. Tournefier, S. Tourneur, M. T. Tran, A. Tsaregorodtsev, N. Tuning, M. Ubeda Garcia, A. Ukleja, D. Urner, U. Uwer, V. Vagnoni, G. Valenti, R. Vazquez Gomez, P. Vazquez Regueiro, S. Vecchi, J. J. Velthuis, M. Veltri, G. Veneziano, M. Vesterinen, B. Viaud, I. Videau, D. Vieira, X. Vilasis-Cardona, J. Visniakov, A. Vollhardt, D. Volyanskyy, D. Voong, A. Vorobyev, V. Vorobyev, H. Voss, C. Voß, R. Waldi, R. Wallace, S. Wandernoth, J. Wang, D. R. Ward, N. K. Watson, A. D. Webber, D. Websdale, M. Whitehead, J. Wicht, D. Wiedner, L. Wiggers, G. Wilkinson, M. P. Williams, M. Williams, F. F. Wilson, J. Wishahi, M. Witek, W. Witzeling, S. A. Wotton, S. Wright, S. Wu, K. Wyllie, Y. Xie, F. Xing, Z. Xing, Z. Yang, R. Young, X. Yuan, O. Yushchenko, M. Zangoli, M. Zavertyaev, F. Zhang, L. Zhang, W. C. Zhang, Y. Zhang, A. Zhelezov, L. Zhong, A. Zvyagin
Xabier Cid Vidal, Titus Mombächer, Maria Ramos, Emilio Xosé Rodríguez Fernández
This paper reports a study of the experimental signatures of hierarchical sectors beyond the Standard Model characterized by a flavor-violating heavy vector and a set of light pseudo-Goldstone bosons $a_{1,2}$, spanning a large range of lifetimes. The non-minimal scalar spectrum triggers novel $B$ decays into multiple leptons that would have escaped the reach of current searches. Novel displaced vertex analyses at LHCb are therefore discussed to probe the hierarchical new physics, extending the scope of the tracking system of the detector. Additionally, the reach of the proposed CODEX-b experiment is studied as well. By exploiting the use of tracks only reconstructed in subsystems of the detector at the high-level LHCb trigger, ${\mathcal{B}(B_s^0\to a_1 a_2) < 10^{-8}}$ and ${\mathcal{B}(B^+\to K^+ a_1 a_2) < 10^{-9}}$ could be reached in the muon channel across seven orders of magnitude in the lifetime of the Goldstone bosons. Correspondingly, heavy-light particle couplings of order $\lesssim 1$ could be tested, potentially ruling out composite Higgs scenarios where the heavy and light sectors couple strongly.
Kazu Akiba, Martin van Beuzekom, Henk Boterenbrood, Emma Buchanan, Jan Buytaert, Wiktor Byczynski, Xabier Cid Vidal, Paula Collins, Elena Dall'Occo, Alvaro Dosil Suarez, Raphael Dumps, Tim Evans, Vinicius Franco Lima, Abraham Gallas Torreira, Julian Garcia Pardinas, Bas van der Heijden, Christoph Hombach, Malcolm John, Szymon Kulis, Xavi Llopart Cudie, Franciole Marinho, Eugenia Price, Sophie Richards, Pablo Rodriguez Perez, Daniel Saunders, Asmund Schiager Folkestad, Heinrich Schindler, Frans Schreuder, Hella Snoek, Panagiotis Tsopelas, Jaap Velthuis, Maria Vieites Diaz, Mark R. J. Williams
The LHCb VELO Timepix3 telescope is a silicon pixel tracking system constructed initially to evaluate the performance of LHCb VELO Upgrade prototypes. The telesope consists of eight hybrid pixel silicon sensor planes equipped with the Timepix3 ASIC. The planes provide excellent charge measurement, timestamping and spatial resolution and the system can function at high track rates. This paper describes the construction of the telescope and its data acquisition system and offline reconstruction software. A timing resolution of 350~ps was obtained for reconstructed tracks. A pointing resolution of better than 2~\mum was determined for the 180~GeV/c %\gevc mixed hadron beam at the CERN SPS. The telescope has been shown to operate at a rate of 5 million particles~\unit{s^{-1}\cdot cm^{-2}} without a loss in efficiency.
Giulio Aielli, Eli Ben-Haim, Roberto Cardarelli, Matthew John Charles, Xabier Cid Vidal, Victor Coco, Biplab Dey, Raphael Dumps, Jared A. Evans, George Gibbons, Olivier Le Dortz, Vladimir V. Gligorov, Philip Ilten, Simon Knapen, Jongho Lee, Saul López Soliño, Benjamin Nachman, Michele Papucci, Francesco Polci, Robin Quessard, Harikrishnan Ramani, Dean J. Robinson, Heinrich Schindler, Michael D. Sokoloff, Paul Swallow, Riccardo Vari, Nigel Watson, Mike Williams
This document presents the physics case and ancillary studies for the proposed CODEX-b long-lived particle (LLP) detector, as well as for a smaller proof-of-concept demonstrator detector, CODEX-$β$, to be operated during Run 3 of the LHC. Our development of the CODEX-b physics case synthesizes `top-down' and `bottom-up' theoretical approaches, providing a detailed survey of both minimal and complete models featuring LLPs. Several of these models have not been studied previously, and for some others we amend studies from previous literature: In particular, for gluon and fermion-coupled axion-like particles. We moreover present updated simulations of expected backgrounds in CODEX-b's actively shielded environment, including the effects of shielding propagation uncertainties, high-energy tails and variation in the shielding design. Initial results are also included from a background measurement and calibration campaign. A design overview is presented for the CODEX-$β$ demonstrator detector, which will enable background calibration and detector design studies. Finally, we lay out brief studies of various design drivers of the CODEX-b experiment and potential extensions of the baseline design, including the physics case for a calorimeter element, precision timing, event tagging within LHCb, and precision low-momentum tracking.
Pablo Baladrón Rodríguez, Veronika Chobanova, Xabier Cid Vidal, Vladimir Gligorov, Miriam Lucio Martínez, Jovan Markov, Diego Martínez Santos, Máximo Pló Casasús
A method for calibrating the momentum scale in a particle physics detector is described. The method relies on the determination of the masses of the final state particles in two-body decays of neutral particles, which can then be used to obtain corrections in the momentum scale. A modified version of the Armenteros-Podolanski plot and the $K_S^0 \to π^+ π^-$ decay is used as a proof of principle for this method.
ECFA Early-Career Researcher Panel, :, Andrei Alexandru Geanta, Chiara Amendola, Liliana Apolinario, Jan-Hendrik Arling, Adi Ashkenazi, Kamil Augsten, Emanuele Bagnaschi, Evelin Bakos, Liron Barak, Diogo Bastos, Giovanni Benato, Bugra Bilin, Neven Blaskovic Kraljevic, Lydia Brenner, Francesco Brizioli, Antoine Camper, Alessandra Camplani, Xabier Cid Vidal, Hüseyin Dag, Flavia de Almeida Dias, Jordy Degens, Eleonora Diociaiuti, Laurent Dufour, Katherine Dunne, Filip Erhardt, Stefan-Alexandru Ghinescu, Loukas Gouskos, Andrej Herzan, Viktoria Hinger, Bojan Hiti, Armin Ilg, Adrián Irles, Kateřina Jarkovská, Jelena Jovicevic, Lucia Keszeghova, Henning Kirschenmann, Suzanne Klaver, Sotiroulla Konstantinou, Magdalena Kuich, Neelam Kumari, Katarína Křížková Gajdošová, Aleksandra Lelek, Jeanette Lorenz, Ana Luisa Carvalho, Péter Major, Jakub Malczewski, Giada Mancini, Laura Martikainen, Émilie Maurice, Seán Mee, Vukasin Milosevic, Zuzana Moravcova, Laura Moreno Valero, Louis Moureaux, Heikki Mäntysaari, Nikiforos Nikiforou, Younes Otarid, Michael Pitt, Vlad-Mihai Placinta, Géraldine Räuber, Giulia Ripellino, Bryn Roberts, Luka Šantelj, Steven Schramm, Mariana Shopova, Kirill Skovpen, Aleks Smolkovič, Gamze Sokmen, Paweł Sznajder, Lourdes Urda Gomez, Abigail Victoria Waldron, Sarah Williams, Valentina Zaccolo, Nima Zardoshti, Manuel Zeyen
The European Committee for Future Accelerators (ECFA) Early Career Researcher's (ECR) panel, which represents the interests of the ECR community to ECFA, officially began its activities in January 2021. In the first two years, the panel has defined its own internal structure, responded to ECFA requests for feedback, and launched its own initiatives to better understand and support the diverse interests of early career researchers. This report summarises the panel composition and structure, as well as the different activities the panel has been involved with during the first two years of its existence.