In high energy physics, the ability to reconstruct particles based on their detector signatures is essential for downstream data analyses. A particle reconstruction algorithm based on learning hypergraphs (HGPflow) has previously been explored in the context of single jets. In this paper, we expand the scope to full proton–proton and electron–positron collision events and study reconstruction quality using metrics at the particle, jet, and event levels. Instead of passing entire events through HGPflow, we train it on smaller partitions for scalability and to avoid potential bias from long-range correlations related to the physics process. We demonstrate that this approach is feasible and that on most metrics, HGPflow outperforms both traditional particle flow algorithms and a machine learning-based benchmark model.

Israel

Nilotpal Kakati

Etienne Dreyer

Anna Ivina

Italy

Francesco Bello

Germany

Lukas Heinrich

Marumi Kado

Eilam Gross

HGPflow: extending hypergraph particle flow to collider event reconstruction

The task of reconstructing particles from low-level detector response data to predict the set of final state particles in collision events represents a set-to-set prediction task requiring the use of multiple features and their correlations in the input data. We deploy three separate set-to-set neural network architectures to reconstruct particles in events containing a single jet in a fully-simulated calorimeter. Performance is evaluated in terms of particle reconstruction quality, properties regression, and jet-level metrics. The results demonstrate that such a high-dimensional end-to-end approach succeeds in surpassing basic parametric approaches in disentangling individual neutral particles inside of jets and optimizing the use of complementary detector information. In particular, the performance comparison favors a novel architecture based on learning hypergraph structure, HGPflow, which benefits from a physically-interpretable approach to particle reconstruction.

Francesco Di Bello

Japan

Sanmay Ganguly

Lorenzo Santi

Jonathan Shlomi

Matteo Tusoni

Reconstructing particles in jets using set transformer and hypergraph prediction networks

Higgs-portal effective field theories are widely used as benchmarks in order to interpret collider and astroparticle searches for dark matter (DM) particles. To assess the validity of these effective models, it is important to confront them to concrete realizations that are complete in the ultraviolet regime. In this paper, we compare effective Higgs-portal models with scalar, fermionic and vector DM with a series of increasingly complex realistic models, taking into account all existing constraints from collider and astroparticle physics. These complete realizations include the inert doublet with scalar DM, the singlet-doublet model for fermionic DM and models based on spontaneously broken dark SU(2) and SU(3) gauge symmetries for vector boson DM. We also discuss the simpler scenarios in which a new scalar singlet field that mixes with the standard Higgs field is introduced with minimal couplings to isosinglet spin- $$0, \frac{1}{2}$$  <math> <mrow> <mn>0</mn> <mo>,</mo> <mfrac> <mn>1</mn> <mn>2</mn> </mfrac> </mrow> </math>   and 1 DM states. We show that in large regions of the parameter space of these models, the effective Higgs-portal approach provides a consistent limit and thus, can be safely adopted, in particular for the interpretation of searches for invisible Higgs boson decays at the LHC. The phenomenological implications of assuming or not that the DM states generate the correct cosmological relic density are also discussed.

Giorgio Arcadi

Estonia

Spain

France

Abdelhak Djouadi

The Higgs-portal for dark matter: effective field theories versus concrete realizations

In High Energy Physics experiments Particle Flow (PFlow) algorithms are designed to provide an optimal reconstruction of the nature and kinematic properties of the particles produced within the detector acceptance during collisions. At the heart of PFlow algorithms is the ability to distinguish the calorimeter energy deposits of neutral particles from those of charged particles, using the complementary measurements of charged particle tracking devices, to provide a superior measurement of the particle content and kinematics. In this paper, a computer vision approach to this fundamental aspect of PFlow algorithms, based on calorimeter images, is proposed. A comparative study of the state of the art deep learning techniques is performed. A significantly improved reconstruction of the neutral particle calorimeter energy deposits is obtained in a context of large overlaps with the deposits from charged particles. Calorimeter images with augmented finer granularity are also obtained using super-resolution techniques.

CERN

Michael Pitt

Towards a computer vision particle flow

We reanalyze the effective field theory approach for the scenario in which the particles that account for the dark matter (DM) in the universe are vector states that interact only or mainly through the Standard Model-like Higgs boson observed at the LHC. This model-independent and simple approach, with a minimal set of new input parameters, is widely used as a benchmark in DM searches and studies in astroparticle and collider physics. We show that this effective theory could be the limiting case of ultraviolet complete models, taking as an example the one based on a spontaneously broken U(1) gauge symmetry that incorporates a dark gauge boson and an additional scalar that mixes with the standard Higgs boson. Hence, despite the presence of the new degrees of freedom, measurements of the invisible decay branching ratio of the Higgs boson, as performed at colliders such as the CERN LHC, can be interpreted consistently in such an effective framework and can be made complementary to results of DM searches in direct detection experiments.

The Higgs-portal for vector dark matter and the effective field theory approach: A reappraisal

The prompt and non-prompt production cross-sections for ψ (2S) mesons are measured using 2.1 fb −1 of pp collision data at a centre-of-mass energy of 7 TeV recorded by the ATLAS experiment at the LHC. The measurement exploits the ψ (2S) → J/ψ (→ μ + μ − ) π + π − decay mode, and probes ψ (2S) mesons with transverse momenta in the range 10 ≤ p T &lt; 100 GeV and rapidity | y | &lt; 2 . 0. The results are compared to other measurements of ψ (2S) production at the LHC and to various theoretical models for prompt and non-prompt quarkonium production.

Georges Aad

United States

Brad Abbott

China

Jalal Abdallah

Samah Abdel Khalek

Azerbaijan

Ovsat Abdinov

Netherlands

Rosemarie Aben

Babak Abi

Maris Abolins

Canada

Ossama AbouZeid

Halina Abramowicz

Henso Abreu

Ricardo Abreu

Sweden

Yiming Abulaiti

United Kingdom

Bobby Samir Acharya

Poland

Leszek Adamczyk

David Adams

Jahred Adelman

Stefanie Adomeit

Tim Adye

Montenegro

Tatjana Agatonovic-Jovin

Juan Antonio Aguilar-Saavedra

Switzerland

Marco Agustoni

Steven Ahlen

Faig Ahmadov

Giulio Aielli

Henrik Akerstedt

Torsten Paul Ake Åkesson

Ginga Akimoto

Russia

Andrei Akimov

Gian Luigi Alberghi

Justin Albert

Solveig Albrand

Argentina

Maria Josefina Alconada Verzini

Martin Aleksa

Igor Aleksandrov

Romania

Calin Alexa

Gideon Alexander

Gauthier Alexandre

Greece

Theodoros Alexopoulos

Muhammad Alhroob

Gianluca Alimonti

Lion Alio

John Alison

Benedict Allbrooke

Lee John Allison

Phillip Allport

John Almond

Alberto Aloisio

Denmark

Alejandro Alonso

Francisco Alonso

Cristiano Alpigiani

Andrew David Altheimer

Barbara Alvarez Gonzalez

Mariagrazia Alviggi

Katsuya Amako

Brazil

Yara Amaral Coutinho

Christoph Amelung

Dante Amidei

Portugal

Susana Patricia Amor Dos Santos

Antonio Amorim

Simone Amoroso

Nir Amram

Glenn Amundsen

Christos Anastopoulos

Lucian Stefan Ancu

Nansi Andari

Timothy Andeen

Christoph Falk Anders

Gabriel Anders

Kelby Anderson

Attilio Andreazza

George Victor Andrei

Xabier Anduaga

Stylianos Angelidakis

Ivan Angelozzi

Philipp Anger

Aaron Angerami

Francis Anghinolfi

Alexey Anisenkov

Nuno Anjos

Alberto Annovi

Ariadni Antonaki

Mario Antonelli

Alexey Antonov

Slovakia

Jaroslav Antos

Fabio Anulli

Masato Aoki

Ludovica Aperio Bella

Rudi Apolle

Giorgi Arabidze

Ignacio Aracena

Yasuo Arai

Juan Pedro Araque

Ayana Arce

Jean-Francois Arguin

Spyridon Argyropoulos

Türkiye

Metin Arik

Aaron James Armbruster

Olivier Arnaez

Vanessa Arnal

Measurement of the production cross-section of ψ (2S) → J/ψ (→ μ + μ − ) π + π − in pp collisions at s $$ \sqrt{s} $$ = 7 TeV at ATLAS