Fifth Joint Workshop IGFAE/LIP | IGFAE's 2024 Retreat (CANCELLED!)

27 Jun 2024, 00:00 → 28 Jun 2024, 22:30 Europe/Zurich

Centro de Estudos Avanzados

UPDATE: June 21st 2024: the event has been cancelled.

 

The 5th edition of the Joint Workshop LIP/IGFAE consolidate the long tradition of scientific cooperation between researchers from the two institutes, both national and international references on High-Energy Physics. It follows the previous first, second, third and fourth editions.

The workshop will be held together with the 2024 Annual Retreat of IGFAE.

Organising Committee:

• Jaime Álvarez-Muñiz (IGFAE).
• Carlota Andrés (LIP).
• Liliana Apolinário (LIP).
• Néstor Armesto (IGFAE).
• Lorenzo Cazón (IGFAE).
• Ruben Conceição (LIP).
• Manuel Rey (IGFAE).
• Ricardo Rodríguez (IGFAE).

 

Thursday 27 June

09:00 → 09:20 Welcome

09:20 → 11:00 Astroparticle Physics: Session I

09:20 Enhancing Pierre Auger Observatory's Neutral Particle Detection Capabilities

The main goal of this work is to enhance the Pierre Auger Observatory's neutral particle detection capabilities. This will be achieved through the introduction of two distinct methods, both currently based solely on simulated data.

The first method aims to improve gamma/hadron discrimination by employing a novel variable that exploits the disparity in the spatial and temporal distribution of particle clusters between hadronic and electromagnetic/neutral showers.

The second method involves separating an event's signal into its electromagnetic and muonic components, followed by the application of simple cuts. The main objective of this procedure is to expand the Pierre Auger Observatory's field of view to include vertical electron neutrinos.

Speaker: Pedro Costa

09:40 Proton-air interactions at ultra-high energies in muon-depleted air showers with different depths

The hardness of the energy spectrum of neutral pions produced in proton-air interactions at ultra-high energies, above $10^{18}$ eV, is constrained by the steepness of the distribution of the number of muons in muon-depleted extensive air showers.

In this work, we find that this steepness, quantified by the parameter $\Lambda_{\mu}$, evolves with the depth of the shower maximum, $X_{\max}$, assuming a universal value for shallow showers and an enhanced dependence on the high-energy hadronic interaction model for deep showers. We show that $X_{\max}$ probes the so-called hadronic activity of the first interaction, thus allowing direct access to the energy spectrum of neutral pions in different regions of the kinematic phase space of the first interaction.

We verify that the unbiased measurement of $\Lambda_{\mu}$ is possible for realistic mass composition expectations. Finally, we infer that the statistical precision in $\Lambda_{\mu}$ required to distinguish between hadronic interaction models can be achieved in current extensive air shower detectors, given their resolution and exposure.

Speaker: Miguel Martins

10:00 Probing first interaction properties of ultra high energy cosmic rays by measuring the low muon number distribution tail using underground muon detectors

The Pierre Auger Observatory, the world’s largest experiment in the study of the highest energy astroparticles, is being upgraded with new detector technologies to reduce its current systematic uncertainties and accurately determine the mass composition of Ultra High Energy Cosmic Rays (HECRs). The Underground Muon Detector (UMD), a part of the recent low-energy extension of the observatory, has the ability to directly measure the muonic component of extensive air showers. UHE cosmic rays have long been seen as an unique opportunity to probe hadronic interaction physics at high energies. A recent analysis found that the shape of the lower tail of the muon number distribution is sensitive to the properties of multiparticle production in the first interaction of the air shower. Taking advantage of the detection capabilities of the UMD, E ≃ 10¹⁷eV, air-shower phenomenology studies are being developed in order to test first interaction properties for proton-air events at center-of-mass energies reached by the Large Hadron Collider for different hadronic interaction models.

Speaker: Alexandra Fernandes

10:20 Measurement of the air shower components energy spectrum using an hybrid detector station

The measurement of air shower components' energy spectra has been shown to be crucial for understanding the primary cosmic rays and the physical processes governing their interactions in the atmosphere.

This study introduces the use of a hybrid detector station for precise measurement of the energy spectrum of air shower components. The hybrid detector station integrates data from a scintillator surface detector (SSD), a water Cherenkov detector (WCD), and Resistive Plate Chambers (RPCs). This combination allows for assessment of the energy spectrum of electromagnetic particles and low-energy muons, independent of potential detector aging effects.

Speaker: Ruben Mauricio Da Silva Conceicao (Laboratory of Instrumentation and Experimental Particle Physics (PT))

10:40 Calibrations at Auger: status and challenges

The development of accurate and robust procedures for the calibration of surface-detector arrays in extensive air-shower experiments presents a formidable task. We discuss methods, challenges and ongoing work regarding the surface-detector calibration in the context of Auger and its upgrade.

Speaker: Raul Sarmento

11:00 → 11:30 Coffee break

11:30 → 12:30 Astroparticle Physics: Session II

11:30 The Potential of Water-Cherenkov Air Shower Arrays for detecting transient sources of high-energy astrophysical neutrinos

We highlight the capacity of current and forthcoming air shower arrays utilizing water-Cherenkov stations to detect neutrino events spanning energies from $10\,$GeV to $100\,$TeV. This detection approach leverages individual stations equipped with both bottom and top photosensors, making use of features of the signal time trace and machine learning techniques. Our findings demonstrate the complementary of this method to established and future neutrino-detection experiments, including IceCube and the upcoming Hyper-Kamiokande experiment.

Speaker: Borja Serrano González (LIP/IST)

11:50 P_{tail} - a high-resolution gamma/hadron and composition discriminant variable for Water Cherenkov Detector cosmic-ray observatories

The precise and efficient identification of the nature of the primary cosmic rays on an event-by-event basis stands as a fundamental aspiration for any cosmic ray observatory.
In particular, the detection and characterization of gamma ray events are challenged by their occurrence within an overwhelmingly greater flux of charged cosmic rays spanning several orders of magnitude. The intricacies of distinguishing between cosmic ray compositions and the inherent uncertainties associated with hadronic interactions present formidable challenges, which, if not properly addressed, can introduce significant sources of systematic errors.

In this presentation, we introduce a novel composition discriminant variable, $P_{\rm tail}^{\alpha}$, which quantifies the number of Water Cherenkov Detectors with a signal well above the mean signal observed in WCDs located at an equivalent distance from the shower core, in events with approximately the same energy at the ground. This new event variable is then shown to be, in the reconstructed energy range $10\,$TeV to $1.6\,$PeV, well correlated with the total number of muons that hit, in the same event, all the observatory stations located at a distance greater than $200\,{\rm m}$ from the shower core. The two variables should thus have similar efficiencies in the selection of high-purity gamma event samples and in the determination of the nature of charged cosmic ray events.

Speaker: Lucio Gibilisco (LIP)

12:10 Characteristics of atmosphere-skimming air showers relevant for high-altitude radio experiments.

Atmosphere-skimming air showers are initiated by cosmic rays with incoming directions located above the Earth’s horizon, such that the development of the cascade occurs exclusively in the atmosphere. In this work, we have performed a first characterisation of atmosphere-skimming particle cascades and their associated radio emission using the ZHAireS-RASPASS simulation program. Both the low air density and the orientation of the magnetic field in the region where the shower development takes place are shown to alter the longitudinal and lateral evolution of the particle cascade depending on its geometry. Significant differences in the radio emission appear as a consequence with respect to downward-going air showers, giving rise to unique features whose impact is discussed regarding the exposure of high-altitude detectors and the interpretation of collected data.

Speaker: Sergio Cabana Freire (IGFAE)

12:30 → 13:10 QCD: Session I

12:30 Jet evolution in a quantum computer

The quark-gluon plasma is a hot and dense soup of quarks and gluons that was present in the first microseconds of the universe. Although quark-gluon plasma can be created in the laboratory, such as in the LHC and RHIC experiments, due to its short lifetime, the use of indirect methods for studying its properties is necessary.

Jets, formed at the time of the creation of the quark-gluon plasma and having their properties modified by the interaction with the medium, are one of the most common probes to study the quark-gluon plasma. The well-understood behavior of jets in a vacuum provides a baseline for identifying medium-induced modifications. Furthermore, due to the jets’ complexity, the study of their dynamics in a medium is not a trivial task, which has led to the proposal of new techniques to simulate them in the last decades.

At the same time, quantum computing, based on inherent properties of quantum mechanics systems, has been growing, bringing new ways to deal with classical hard problems. Among many other applications and algorithms, such as Shor’s, Grover’s, and quantum phase estimation algorithms and optimization problems, following the original ideas of Feynman quantum simulation is one of the most explored applications of quantum computing.

In this context, jets, due to their quantum mechanical nature, are one of the most promising candidates to benefit from using quantum simulation algorithms to study their properties. Due to the state of the actual quantum devices, the simulation of an entire jet is still a long-term goal. Thus, to date, one is focused on simulating the dynamics of single partons in a quantum computer. Therefore, this work describes the development of a quantum routine to simulate the propagation of both single quarks and gluons within a quark-gluon plasma medium. Additionally, the results obtained from different simulation parameters are analyzed and benchmarked against analytical expectations.

Speaker: Maria Gabriela Oliveira (LIP-Minho and University of Minho)

12:50 Integrating Energy Flow Networks with Jet Substructure Observables for Enhanced Jet Quenching Studies

The phenomena of Jet Quenching, a key signature of the Quark-Gluon Plasma (QGP) formed in Heavy-Ion (HI) collisions, provides a window of insight into the properties of this primordial liquid. In this study, we rigorously evaluate the discriminating power of Energy Flow Networks (EFNs), enhanced with substructure observables, in distinguishing between jets stemming from proton-proton (pp) and jets stemming from HI collisions. This work is yet another step towards separating significantly quenched jets from relatively unmodified ones on a per-jet basis, which would enable increasingly more precise measurements of QGP properties. We have analyzed simple Energy Flow Networks (EFNs) and subsequently augmented them with global features such as N-Subjettiness observables and Energy Flow Polynomials (EFPs). Our primary objective is to gauge the power of these approaches in the context of Jet Quenching. Initial evaluations using Linear Discriminant Analysis (LDA) set a performance baseline, which is further enhanced through simple Deep Neural Networks (DNNs), capable of capturing non-linear relations in the data. Integrating EFPs and N-Subjettiness observables into EFNs results in the most performant model over this task, achieving state-of-the-art ROC AUC values of approximately 0.84, a very considerable value given that both medium response and underlying event contamination effects are taken into account.

Speaker: João A. Gonçalves (LIP - IST)

13:10 → 15:00 Lunch

15:00 → 16:40 QCD: Session II

15:00 Probing Hadronization Through Jet Substructure Analysis

Understanding the hadronization mechanism in Quantum Chromodynamics (QCD) remains a significant challenge due to its non-perturbative nature. Hadronization is typically described via phenomenological models in Monte Carlo event generators (such as PYTHIA and HERWIG), whose parameters need to be tuned to data. This work leverages jet substructure to probe underlying features of these frameworks, offering new insights into the hadronization process. While jets were originally proposed to circumvent non-perturbative effects, we show that their substructure can be a powerful tool to investigate these phenomena. Specifically, we demonstrate that the charge correlation ratio, which is sensitive to hadronization effects, can be enhanced by selections on jet substructure, particularly by analyzing the relative placement of splittings that resolve the leading charged particles within the clustering tree. Our findings reveal remarkable differences between widely used hadronization models, contributing to a better understanding of hadronization and opening new avenues for exploring non-perturbative QCD.

Speaker: Nuno Olavo Gonçalves Mendes Madureira (LIP/IST)

15:20 Exploring the time axis within medium-modified jets

The fast evolution of the QGP makes its interaction with jets an inherently time-dependent process. However, this crucial dimension is missing from current jet quenching measurements, which hence provide a mere average quantification of the medium properties. In this talk, we propose that jet substructure observables allow access to the QGP time structure. By identifying the recursive steps of a novel jet clustering algorithm (the $\tau$-algorithm) with the sequence of branchings of the parton shower, we obtain an adequate proxy for a time axis within the medium. This enables us to label jets according to their formation time and select populations with enhanced sensitivity to quenching effects. We apply this technique to $Z$+jet simulated events using the JEWEL MC generator. Our results illustrate how this method minimizes the biases stemming from $p_t$-, $\Delta R$-, or mass-based selections.

Speaker: Pablo Guerrero Rodríguez (LIP)

15:40 Deciphering QCD Parton formation time in Heavy-Ion Collisions

The extended coloured medium, the Quark-Gluon Plasma (QGP), created in heavy-ion collisions offers a unique opportunity to examine the time structure of QCD radiation. Leveraging on new jet clustering tools [1], it is possible to generate a time-ordered sequence within jets that correlates with the QCD parton formation time. The concept of QCD parton formation time, though underexplored, is emerging as a crucial parameter for understanding in-medium energy loss [2]. Early-developing jets, with formation times shorter than the medium's length, exhibit substantial suppression, while late-developing jets remain largely unaffected compared to proton-proton collisions. This differential behaviour underscores the potential of parton formation time as an indicator of jet-medium interactions. In this talk, we will discuss the next critical steps: developing a comprehensive physical model of QCD parton formation time, establishing a solid theoretical foundation for both vacuum and in-medium radiation. By using jet quenching Monte Carlo event generators, we will further illustrate how to enhance the precision characterization of the QGP.

[1] e-Print: 2012.02199
[2] e-Print: 2401.14229

Speaker: Liliana Apolinario (LIP (PT))

16:00 Jet quenching in anisotropic media

Speaker: Xoán Mayo

16:20 Quark and gluon thermalization through parton transport

Speaker: Sergio Barrera

16:40 → 17:30 Detectors

16:40 Development of a Full3D Optical Time Projection Chamber for Neutrino Interactions

An Optical Time Projection Chamber with 2 stages of amplification using THGEMs (THick Gaseous Electron Multipliers) that are operated in high-pressure Ar:CF$_4$ is being developed. Argon doped with 1% of CF$_4$ provides wavelength shifting of argon scintillation photons from the vacuum-ultraviolet (VUV) to the visible region, centred at 630nm. A Timepix camera coupled to a red light image intensifier can provide Full3D optical imaging of particle tracks with high readout rates, by obtaining the z-coordinate from time-of-arrival and x,y camera pixel number to mm conversion. Reconstruction of low-energy particles from neutrino interactions can be carried out with nanosecond time resolution and fine spatial resolution.

Speaker: Ms Raheema Hafeji (Instituto Galego de Física de Altas Enerxías (IGFAE))

17:00 LHCb: VELO upgrade and upgrade II

Speaker: Antonio Fernandez Prieto (Instituto Galego de Física de Altas Enerxías (IGFAE/USC) (ES))

17:20 CODEX-b/β: a new long-lived particles detector close to the LHCb interaction point

Speaker: Carlos Vazquez Sierra (Universidade de Santiago de Compostela (ES))

18:00 → 19:00 Conference by Almudena Martín Castro

20:00 → 21:30 Concert for the 25th anniversary of IGFAE: Open air concert

21:30 → 00:00 Conference dinner

Friday 28 June

09:00 → 10:00 Talks by directors

09:00 IGFAE

Speaker: Carlos Albert Salgado Lopez (Universidade de Santiago de Compostela (ES))

09:30 LIP

Speaker: Patrícia Gonçalves

10:00 → 11:00 Future of HEP

10:00 Discussion

11:00 → 11:30 Coffee break

11:30 → 12:15 TT: new avenues

11:30 Proton therapy at LIP

Speakers: Mário Pimenta (LIP), Patrícia Gonçalves

11:45 Proton therapy at IGFAE

Speaker: GARCIA RIVAS IRIS Not Supplied (IGFAE)

12:00 Discussion

12:15 → 12:45 IGFAE activities: Session on administrative matters

12:45 → 15:00 Lunch

15:00 → 16:50 IGFAE activities: Reports of scientific activities

15:00 Beyond the SM searches with LHCb

15:10 Hot and dense QCD in the LHC era and beyond

15:20 String theory and related fields

15:30 Extremely energetic cosmic rays and neutrinos – Large exposure experiments

15:40 Dark Matter and the nature of neutrinos

15:50 Gravitational Waves

16:00 The structure of the nuclear many-body systems and its astrophysical and cosmological implications

16:10 Exploitation of the Laser Laboratory of Acceleration and Applications (L2A2) at USC

Speaker: Aaron Alejo Alonso (Universidade de Santiago de Compostela)

16:20 Discussion

16:50 → 17:00 Closing

18:00 → 20:00 Mundo Quark: Danza Cuántica. Taller de Danza e Ciencia

https://cgac.xunta.gal/gl/actividades/mundo-quark-danza-cuantica-taller-de-danza-e-ciencia

20:00 → 21:30 Universo entre canciones