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Arantza Oyanguren

Publications and source records attributed to Arantza Oyanguren.

11 recordsLinked to original sources
arXiv2026

Energy efficiency of a GPU-based computing system for High Energy Physics experiments

In this paper we introduce the energy efficiency as a new metric for evaluating both hardware platforms based on Graphic Processor Units (GPU), and algorithm optimisations at High Energy Physics (HEP) experiments. We develop a method to compute the energy efficiency for the case of the first high level trigger (HLT1) of the LHCb experiment, relating the throughput with GPU specifications such as the number of cores, clock frequency, memory bandwidth and thermal design power. The model can be extended to other HEP experiments to make decisions and reach sustainable computing ecosystems.

hep-ex↗
arXiv2026

A converged architecture for processing 32 Tbps of physics data in real-time at the LHCb experiment

The LHCb detector at the Large Hadron Collider has been upgraded to acquire an unprecedented 32 Tbps of particle-collision data to provide new insights in the High Energy Physics domain. The data produced by the detector is filtered in real-time to select interesting collisions. As part of the upgrade, a pre-filtering stage has been removed leading to a factor 40 increase in data rate. To deal with the high throughput demands of LHCb real-time data processing, we present an off-the-shelf network architecture using zero-copy techniques in conjunction with an efficient, fully-GPU-based filter. Our converged architecture is able to process the full 32 Tbps of particle-collision data in real-time, the highest in any physics experiment to date. Our result extends the reach of the LHCb physics programme and sets a new standard for real-time data processing at particle physics experiments.

hep-ex↗
arXiv2026

Seeding and Matching algorithms for the first GPU-based High Level Trigger of the LHCb experiment

We describe the GPU implementation of the Seeding and Matching algorithms, developed for the first level trigger of the LHCb experiment and key to reconstruct long and very displaced tracks at 40 MHz. The algorithms have been participating in the data taking during the full Run 3 of LHCb with a very high throughput, increasing the physics reach of the experiment. The Seeding is a standalone pattern recognition algorithm aiming at finding charged particle trajectories in the most forward tracker of LHCb. These trajectories are then extrapolated backward by the Matching algorithm which combines them with stubs formed from hits in the first tracker in order to form what we call Long tracks. Hits in the second tracker are then searched for to better define the trajectory and improve the track momentum resolution. This backward approach, complementary to the approach of extrapolating the stubs in the first detector to the forward tracker through the magnetic field, improves the Long track efficiency at low transverse momenta, increasing the potential of key physics decay channels.

physics.ins-det↗
arXiv2024

LHCb potential to discover long-lived new physics particles with lifetimes above 100 ps

For years, it has been believed that the main LHC detectors can only restrictively play the role of a lifetime frontier experiment exploring the parameter space of long-lived particles (LLPs) - hypothetical particles with tiny couplings to the Standard Model. This paper demonstrates that the LHCb experiment may become a powerful lifetime frontier experiment if it uses the new Downstream algorithm reconstructing tracks that do not let hits in the LHCb vertex tracker. In particular, for many LLP scenarios, LHCb may be as sensitive as the proposed experiments beyond main LHC detectors for various LLP models, including heavy neutral leptons, dark scalars, dark photons, and axion-like particles.

hep-ph↗
arXiv2021

Review of opportunities for new long-lived particle triggers in Run 3 of the Large Hadron Collider

Long-lived particles (LLPs) are highly motivated signals of physics Beyond the Standard Model (BSM) with great discovery potential and unique experimental challenges. The LLP search programme made great advances during Run 2 of the Large Hadron Collider (LHC), but many important regions of signal space remain unexplored. Dedicated triggers are crucial to improve the potential of LLP searches, and their development and expansion is necessary for the full exploitation of the new data. The public discussion of triggers has therefore been a relevant theme in the recent LLP literature, in the meetings of the LLP@LHC Community workshop and in the respective experiments. This paper documents the ideas collected during talks and discussions at these Workshops, benefiting as well from the ideas under development by the trigger community within the experimental collaborations. We summarise the theoretical motivations of various LLP scenarios leading to highly elusive signals, reviewing concrete ideas for triggers that could greatly extend the reach of the LHC experiments. We thus expect this document to encourage further thinking for both the phenomenological and experimental communities, as a stepping stone to further develop the LLP@LHC physics programme.

hep-ex↗
arXiv2019

Tracking performance for long-lived particles at LHCb

The LHCb experiment is dedicated to the study of the $c-$ and $b-$hadron decays, including long-lived particles such as $K_s$ and strange baryons ($Λ^0$, $Ξ^-$, etc... ). These kind of particles are difficult to reconstruct by the LHCb tracking system since they escape detection in the first tracker. A new method to evaluate the performance of the different tracking algorithms for long-lived particles using real data samples has been developed. Special emphasis is laid on particles hitting only part of the tracking system of the new LHCb upgrade detector.

hep-ex↗
arXiv2019

Radiative $b$-baryon decays to measure the photon and $b$-baryon polarization

The radiative decays of $b$-baryons facilitate the direct measurement of photon helicity in $b\to sγ$ transitions thus serving as an important test of physics beyond the Standard Model. In this paper we analyze the complete angular distribution of ground state $b$-baryon ($Λ_{b}^{0}$ and $Ξ_{b}^{-}$) radiative decays to multibody final states assuming an initially polarized $b$-baryon sample. Our sensitivity study suggests that the photon polarization asymmetry can be extracted to a good accuracy along with a simultaneous measurement of the initial $b$-baryon polarization. With higher yields of $b$-baryons, achievable in subsequent runs of the Large Hadron Collider (LHC), we find that the photon polarization measurement can play a pivotal role in constraining different new physics scenarios.

hep-ph↗
arXiv2015

Measurement of the $D^0 \to π^-e^+ν$ branching fraction, form factor and implications for $V_{ub}$

In this talk results of the study of the $D^0 \to π^- e^+ ν$ decay channel, recorded by the BaBar detector at the c.m. energy close to 10.6 GeV, are reported. The branching fraction of this channel is measured relative to the $D^0 \to K^- π^+$ decay. The hadronic form factor, $f_{+,D}^π(q^2)$, function of $q^2$, the four momentum transfer squared between the $D$ and the $π$ mesons, is compared to various theoretical predictions, and the normalization $V_{cd} \times f_{+,D}^π(q^2=0)$ is extracted from a fit to data. Results are compared with Lattice QCD calculations. A new multipole model is applied which makes use of present information of resonant states contributing to the form factor. With the understanding of the $f_{+,D}^π(q^2)$ form factor, and provided the relation between the $D^0 \to π^- e^+ ν$ and $B^0 \to π^- e^+ ν$ decay widths at the same pion energy, the CKM matrix element $V_{ub}$ is determined and compared to recent measurements. This method of extracting $V_{ub}$ will become competitive with new Lattice QCD calculations of the ratio of form factors.

hep-ex↗
arXiv2014

Insight into $D/B\to π\ell ν_\ell$ decay using the pole models

After improving the knowledge about residua of the semileptonic form factor at its first two poles we show that $f_+^{Dπ}(q^2)$ is not saturated when compared with the experimental data. To fill the difference we approximate the rest of discontinuity by an effective pole and show that the data can be described very well with the position of the effective pole larger than the next excitation in the spectrum of $D^\ast$ state. The results of fits with experimental data also suggest the validity of superconvergence which in the pole models translates to a vanishing of the sum of residua of the form factor at all poles. A similar discussion in the case of $B\to π\ellν_\ell$ leads to the possibility of extracting $\vert V_{ub}\vert$, the error of which appears to be dominated by $g_{B^\ast Bπ}$, which can be nowadays computed on the lattice. In evaluating the residua of the form factors at their nearest pole we needed the vector meson decay constants $f_{D^\ast}$ and $f_{B^\ast}$, which we computed by using the numerical simulations of QCD on the lattice with $N_{\rm f}=2$ dynamical quarks. We obtain, $f_{D^\ast}/f_D=1.208(27)$ and $f_{B^\ast}/f_B=1.051(17)$.

hep-ph↗
arXiv2012

Air cooling for Vertex Detectors

The vertex detectors are crucial detectors for future linear e+e- colliders since they must give the most accurate location of any outgoing charged particles originating from the interaction point. The DEPFET collaboration is developing a new type of pixel sensors which provide very low noise and high spatial resolution. In order to precisely determine the track and vertex positions, multiple scattering in the detector has to be reduced by minimizing the material in the sensors, cooling, and support structures. A new method of cooling by blowing air over the sensors has been developed and tested. It is applied in the design and construction of the Belle-II detector and may be used in the new generation of vertex detectors for linear colliders.

physics.ins-det↗