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Simultaneous measurements of -subjettiness observables in light-flavour quark and gluon jets, and in hadronic decays of boosted W bosons and top quarks
No full textA simultaneous measurement of twenty-five jet substructure observables is presented using large-radius jets with high transverse momentum from proton-proton collisions at TeV. The measurement is carried out on QCD dijet events and events enriched in boosted, hadronic decays of W bosons and top quarks. The three data samples consist of jets with one, two, and three prongs from the showering and hadronisation of a light quark or gluon, two quarks and three quarks, respectively. The data correspond to an integrated luminosity of 138 fb, recorded by the CMS experiment between 2016--2018. A detailed characterisation of the jet substructure is provided using a 6-body basis of -subjettiness observables that over-constrains the phase space of the resolved emissions in the jet. The measurements are unfolded to the level of stable particles, and an estimate of the particle-level correlations between observables is provided, ensuring that the results can be used to systematically assess and refine the modelling of radiation in jets
The SN 1987A Cooling Bound on Dark Matter Absorption in Electron Targets
No full textWe present new supernova (SN 1987A) cooling bounds on sub-MeV fermionic dark matter with effective couplings to electrons. These bounds probe the parameter space relevant for direct detection experiments in which dark matter can be absorbed by the target material, showing strong complementarity with indirect searches and constraints from dark matter overproduction. Crucially, our limits exclude the projected sensitivity regions of current and upcoming direct detection experiments. Since these conclusions are a priori not valid for light mediators, we extend our analysis to this case. We show that sub-GeV mediators can be produced resonantly both in supernova cores and in the early Universe, altering the SN 1987A analysis for effective couplings. Still, a combination of supernova cooling constraints and limits from dark matter overproduction excludes the entire parameter space relevant for direct detection in this case
Dark matter searches at ATLAS
No full textThis talk will present the latest ATLAS searches for Dark Matter to ICNFP2025
Delivery of third US-AUP magnet for HL-LHC
No full textThe third cryo-assembly (named LQXFA04) from the United States Accelerator Upgrade Program (US-AUP) has been delivered to CERN. It arrived on 6th August 2025, after a long journey from Fermilab in Batavia, Illinois
Student Sessions 2025
No full textJinkyu is an undergraduate physics student at Hanyang University in Seoul, South Korea. He has been working as a research intern with the KCMS Elementary Particle Physics group at his university.
This summer, he has been involved in Data Quality and Monitoring for the LBD group in LHCb, focusing on a project analyzing the 4-Cell Problem in the LHCb electromagnetic calorimeter. This issue, which has been recurring throughout the past year, often goes unnoticed, leaving potentially affected data included in the ntuples used for research. His work has centered on identifying the impact of this problem, understanding its behavior, and assessing whether the data can still be used for specific types of analyses. In this presentation, he will share the details of his investigation, as well as his contributions and insights for future occurrences
Student Sessions 2025
No full textHello! My name is Brad Brown and I’m a senior undergraduate physics student at the University of Texas at Arlington. This summer, I worked with the LHCb Simulation team on restoring and modernizing the Machine-Induced Background (MIB) generator — a simulation tool originally developed during Run 1 of the LHC but unused since. MIB arises from beam losses around the accelerator and can impact detector performance. New studies are needed to evaluate MIB conditions for High-Luminosity LHC, Heavy Ion Collisions, and even for future colliders like the FCC. My project involved understanding the relevant accelerator physics, reviving the legacy tool, and porting it into the modern Gauss-on-Gaussino framework. With the generator now operational again, LHCb is equipped to carry out these new studies
University of Michigan Research Abroad Student Program, Summer 2025
No full textUniversity of Michigan students participating in the Homer Neal undergraduate research program at CERN, Summer 2025
First exclusive reconstruction of the , , and mesons and precise measurement of their masses
No full textUsing proton-proton collision data collected by the CMS experiment at 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb, the first full reconstruction of the three vector meson states, , , and , is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be 45.277 0.039 0.027 MeV, 45.471 0.056 0.028 MeV, and 49.407 0.132 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.Using proton-proton collision data collected by the CMS experiment at = 13 TeV in 20162018, corresponding to an integrated luminosity of 140 fb, the first full reconstruction of the three vector B meson states, B, B, and B, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be = 45.277 0.039 0.027 MeV, = 45.471 0.056 0.028 MeV, and = 49.407 0.132 0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude
Student Sessions 2025
No full text**DFX4ML: enable Dynamic Function eXchange for Machine Learning**
In resource-constrained edge computing applications like satellites, autonomous vehicles, and wearable devices, power efficiency and hardware limitations are critical. FPGAs offer reconfigurability, but large ML models often exceed their capacity. This project tackles the issue by enabling dynamic Function eXecution (DFX), allowing efficient use of FPGA resources.
I’m a master’s student at Chulalongkorn University, currently interning at edgespAIce@CERN. My thesis project, KATHRYN, is a hybrid hardware design and simulation framework that aligns closely with my CERN work, both aiming to generate flexible and efficient hardware