Month: May 2025

Parton showers and resummation techniques play a crucial role in the physics programme of the LHC as well as that of future colliders. Indeed, they are essential tools to obtain accurate theoretical predictions for physical observables within the vast spectrum of kinematic configurations that is probed at modern colliders. The Parton Showers and Resummation School will take place between the 7th and 11th of July 2025 at CERN. The aim will be to introduce key concepts and develop an understanding of important topics in this field. It will consist on four courses:

• QCD Resummation for Collider Observables (Pier Monni)
• SCET for Collider Observables (Iain Stewart)
• Parton Showers and Logarithmic Accuracy (Alba Soto Ontoso)
• Matching and Merging (Stefan Höche)

Each course will be composed of four one-hour lectures, and one one-hour discussion session.

The school will be followed by PSR 2025, the annual conference on Parton Showers and Resummation, and a two-week workshop on related topics. More information is available at the indico pages of the conference and workshop.

INDICO page of the school: https://indico.cern.ch/event/1487726/overview

One of our students (Marco Leitão) was selected to participate in this school.

The International Doctorate Network in Particle Physics, Astrophysics and Cosmology (IDPASC) is an interdisciplinary network whose aim is to train a new generation of high-level experts in the fields of Particle Physics, Astrophysics and Cosmology.

The 14th edition of yearly IDPASC schools is organized by the “Laboratoire de Physique des 2 infinis Irène-Joliot-Curie” at the Paris-Saclay university (France). The school starts on July 15th and ends on July 25th.

This school aims at training the next generation of physicists that will investigate open questions in the PASC domains in the coming decades. The school offers a multi-disciplinary approach that will help each student, which starts to specialize in one domain, to keep a broad view on the different PASC domains. This will be a key skill to optimally use the complementarity between different approaches to shed light on the same problems with a different angle such as Dark Matter, physics beyond the Standard Model or multi-messenger physics. On top of the main courses, the school will also propose some hands-on session in specific domains such as advanced data analysis techniques or statistics. In addition, visits to experimental infrastructures are foreseen.

The school targets first year PhD students and students about to start their PhD but is also open to 2nd and 3rd year students or young postdocs.

Pre-registration deadline: 15th of May 2025. Final registration deadline: 30th of June 2025. The school will be limited to 35 students.

INDICO page: https://indico.ijclab.in2p3.fr/event/11196/

One of our students (Nuno Olavo) was selected to participate in this school.

The second “European AI for Fundamental Physics Conference” (EuCAIFCon) will take place in Cagliari from 16 to 20 June 2025. The aim of this event is to provide a platform for establishing new connections between AI activities across various branches of fundamental physics, by bringing together researchers that face similar challenges and/or use similar AI solutions. The conference will be organized “horizontally”: sessions are centered on specific AI methods and themes, while being cross-disciplinary regarding the scientific questions.

INDICO page: https://agenda.infn.it/event/43565/overview

Registration deadline: May 31st, 2025. Abstract submission deadline: February 24th, 2025.

One of our students (Fernando Souza) will present a poster. Link to contribution page: https://agenda.infn.it/event/43565/contributions/260004/

The workshop “New Opportunities in Particle and Nuclear Physics with Energy Correlators”, was held at the Central China Center for Nuclear Theory (C3NT) in Wuhan, China, between May 6th and May 17th, 2025. This event brought together leading theorists and experimentalists in high-energy particle and nuclear physics to explore the latest advancements and applications of energy correlators, fostering collaborative research and in-depth discussions on this cutting-edge topic.

The program included a dynamic mix of invited keynote talks, short presentations, and discussion sessions, fostering a vibrant environment for idea exchange and exploration of emerging trends in the field.

INDICO page: https://indico.ihep.ac.cn/event/24880/

Two members of our group delivered talks at this workshop: a researcher (Andrey Sadofyev) and a PhD student (João Silva) . Click on their names to see their respective contributions!

The upcoming era of gravitational wave (GW) cosmology, enabled by a broad range of next-generation detectors, demands a coordinated theoretical effort and a robust theory-to-data pipeline to fully exploit its discovery potential. The workshop “The Dawn of Gravitational Wave Cosmology”, held at Benasque (Spain) from April 27th to May 17th, brought together experts across diverse GW probes to develop a multi-messenger strategy, with a key focus on cross-correlations to disentangle primordial signals from astrophysical backgrounds.

The workshop featured a contribution of the LIP-Phenomenology member Marco Finetti. He presented PT2GWFinder, a Mathematica-based tool developed to streamline the analysis of first-order cosmological phase transitions and their associated gravitational wave signals within Beyond the Standard Model (BSM) scenarios.

PT2GWFinder simplifies the computation of key phase transition parameters—such as nucleation and percolation temperatures—by automating tasks like phase tracing, bounce action fitting, and gravitational wave spectrum derivation, using the polygonal bounce method via FindBounce. It also emphasizes user-friendliness and full automation while maintaining compatibility with dimensional reduction frameworks like DRalgo.

For more information, see https://benasque.org/2025gwc/

The 59th edition of the Rencontres de Moriond QCD and High-Energy Interactions conference took place in La Thuile, Italy, from March 31st to April 6th. This conference was created by Jean Tran Thanh Van in 1966 with the goal of fostering collaboration between experimentalists and theorists in a beautiful and relaxed atmosphere.

João Pires, researcher in the LIP Phenomenology group, contributed with a talk in the session dedicated to QCD. The contribution was titled “Precise Determination of the Strong Coupling Constant αₛ from Dijet Cross Sections up to the Multi-TeV Range.”

The strong coupling constant, denoted by αₛ, is one of the fundamental constants in particle physics that governs the strength of the interaction between quarks and gluons in Quantum Chromodynamics (QCD). A unique aspect of QCD is the property of asymptotic freedom, which awarded the 2004 Nobel Prize in Physics to David Gross, David Politzer, and Frank Wilczek. From this property, it can be deduced that the value of αₛ decreases at higher energies and increases at lower energies. This discovery represented a crucial advancement in our understanding of the nature of the strong force, revealing how it behaves at different energy scales.

For the research presented at Moriond, a new determination of the value of the strong coupling constant αₛ was made, based on experimental measurements from the ATLAS and CMS experiments at the LHC at center-of-mass energies of 7, 8, and 13 TeV, and its asymptotic freedom behavior was studied. The analysis was carried out using NNLO predictions for jet production in perturbative QCD, developed within the phenomenology group at LIP. From a large subset of LHC experimental data, we inferred a value of αₛ at the Z boson mass scale of αₛ(mZ) = 0.1178 ± 0.0022.

Complementing the LHC data with cross-sections measurements at the HERA collider, which operated at lower energy scales, the hypothesis of asymptotic freedom in QCD was tested in this work over three orders of magnitude in energy scale, from 7 GeV to 7 TeV. The results obtained show excellent agreement with the evolution predicted by QCD, up to the multi-TeV scale.

Since the determination of the value of αₛ can also be made through other methods, using different observables at different energy scales, the values obtained by various research groups may exhibit small variations, compatible within their respective uncertainties. The next step is to include this new determination of αₛ obtained at the LHC with a precision of 1.87%, in the global analysis of αₛ determinations conducted by the PDG (Particle Data Group) collaboration, an international collaboration responsible for establishing measurements of various physical quantities.