Searches for Beyond the Standard Model Physics with Hadronic Topologies
Lead Research Organisation:
University College London
Department Name: Physics and Astronomy
Abstract
Physicists want to determine the most fundamental building blocks of the Universe and how they interact. Currently, our best theory is called the Standard Model (SM). It explains how magnetic fields and electrical currents are related to radioactive nuclei decay and the force that holds a proton together. However, many open questions exist within and beyond the SM. Neither ~95% of the known universe nor gravity is described by the SM, for instance.
The SM deals only with the visible Universe, while the majority of matter does not emit or absorb light: aptly named dark matter (DM). By looking at gravitational effects on stars in galaxies and clusters of galaxies, we suspect DM comprises ~84% of the Universe's mass. DM has not yet been observed on Earth because it may interact very weakly with visible matter. Some attempts to explain DM are simple and only include one new particle and mediator - the bridge between the dark and visible worlds. Others, such as Supersymmetry, a very popular SM extension, predict many new particles, one of which could be DM.
Gravity is very weak. A kitchen magnet holds a paper clip against the gravitational pull of the entire Earth. One explanation is that the Universe contains more than four dimensions, and we only feel a fraction of the full gravitational potential in our four.
As scientists, we develop possible answers to unexplained phenomena, such as those mentioned above, and devise experiments to test our ideas; sometimes we find the completely unexpected. The Large Hadron Collider (LHC) was built for this purpose. The LHC smashes together protons at very high energies to create all the SM particles and hopefully a few never seen before! DM particles themselves or the DM mediator can be created in proton-proton collisions. The higher dimensional theories focusing on gravity predict the creation of black holes at LHC energies. These and a host of other theories tackling the big physics questions, if true, predict new particles will be produced by the LHC and decay into jets - highly energetic collimated sprays of SM particles. An excess in the number of such decays would signify that we have found new physics and revolutionize our understanding of the Universe!
With every discovery, the new physics gives insight to the most fundamental workings of the Universe. It changes our understanding of the Universe and the way we live in it. The discovery of the electron allowed us to harness the power of electricity and magnets, understanding the rules of the atom yielded nuclear energy to power our cities, and Einstein's theory of relativity enabled Global Positioning Systems to find our way across this beautiful planet. Technologies developed by physicists have amazing potential for progress, and the World Wide Web for example was created at CERN. Physicists trained in the rigors of the scientific method on tremendous datasets are employed by governments, businesses, financial institutions, and even sports teams to analyze data and solve complicated problems. Nevertheless, for me, the reason to understand nature at a fundamental level is best encapsulated by the Nobel laureate Steven Weinberg when he wrote, "The effort to understand the Universe is one of the very few things which lifts human life a little above the level of farce and gives it some of the grace of tragedy."
The SM deals only with the visible Universe, while the majority of matter does not emit or absorb light: aptly named dark matter (DM). By looking at gravitational effects on stars in galaxies and clusters of galaxies, we suspect DM comprises ~84% of the Universe's mass. DM has not yet been observed on Earth because it may interact very weakly with visible matter. Some attempts to explain DM are simple and only include one new particle and mediator - the bridge between the dark and visible worlds. Others, such as Supersymmetry, a very popular SM extension, predict many new particles, one of which could be DM.
Gravity is very weak. A kitchen magnet holds a paper clip against the gravitational pull of the entire Earth. One explanation is that the Universe contains more than four dimensions, and we only feel a fraction of the full gravitational potential in our four.
As scientists, we develop possible answers to unexplained phenomena, such as those mentioned above, and devise experiments to test our ideas; sometimes we find the completely unexpected. The Large Hadron Collider (LHC) was built for this purpose. The LHC smashes together protons at very high energies to create all the SM particles and hopefully a few never seen before! DM particles themselves or the DM mediator can be created in proton-proton collisions. The higher dimensional theories focusing on gravity predict the creation of black holes at LHC energies. These and a host of other theories tackling the big physics questions, if true, predict new particles will be produced by the LHC and decay into jets - highly energetic collimated sprays of SM particles. An excess in the number of such decays would signify that we have found new physics and revolutionize our understanding of the Universe!
With every discovery, the new physics gives insight to the most fundamental workings of the Universe. It changes our understanding of the Universe and the way we live in it. The discovery of the electron allowed us to harness the power of electricity and magnets, understanding the rules of the atom yielded nuclear energy to power our cities, and Einstein's theory of relativity enabled Global Positioning Systems to find our way across this beautiful planet. Technologies developed by physicists have amazing potential for progress, and the World Wide Web for example was created at CERN. Physicists trained in the rigors of the scientific method on tremendous datasets are employed by governments, businesses, financial institutions, and even sports teams to analyze data and solve complicated problems. Nevertheless, for me, the reason to understand nature at a fundamental level is best encapsulated by the Nobel laureate Steven Weinberg when he wrote, "The effort to understand the Universe is one of the very few things which lifts human life a little above the level of farce and gives it some of the grace of tragedy."
People |
ORCID iD |
| Gabriel Facini (Principal Investigator / Fellow) |
Publications
Aaboud M
(2017)
Search for new phenomena in dijet events using 37 fb - 1 of p p collision data collected at s = 13 TeV with the ATLAS detector
in Physical Review D
Aaboud M
(2017)
Performance of the ATLAS track reconstruction algorithms in dense environments in LHC Run 2.
in The European physical journal. C, Particles and fields
Aad G
(2022)
Constraints on Higgs boson production with large transverse momentum using H ? b b ¯ decays in the ATLAS detector
in Physical Review D
Facini G
(2019)
On the model dependence of fiducial cross-section measurements
in Modern Physics Letters A
| Description | With this award, several key searches with large momentum (high pT) jets were performed for the first time and published. These searches looked for evidence for physics beyond the standard model using high pT jets that are expected to be formed from a b-hadron decay. The two main results are those which have been published from the first time: - a search for a heavy resonance decaying to b-quarks - a search for a high pT Higgs boson decaying to a pair of b-quarks These types of searches are limited by the charged particle reconstruction and algorithmic efficiency to identify b-hadron decays at high pT. I have contributed to improving the charged particle efficiency and introducing a new tool to identify b-hadrons based on Graph Neural Networks. These both will improve the physics program as many analyses improve due to the developments. I have been awarded two high-level leadership roles that speak to my work's impact. One was the convener of the 600-person Exotics group as the youngest person to hold the position until then. This group focuses on searches beyond the standard model physics. I am currently the convener of the Tracking group, which focuses on charge particle reconstruction. In between these two appointments, I was the convener of the tracking sub-group that focuses on track reconstruction in jets. (I co-founded this group a few years back). |
| Exploitation Route | I am carrying this work forward with my group as a Lecturer in Data Intensive Science in the Centre of Data Intensive Science and Industry in the Astronomy and Physics Department of University College London. I work in close collaboration with Prof. Tim Scanlon at UCL. The ATLAS collaboration has other members who contribute to these efforts, but we are the leading contributors. |
| Sectors | Education,Other |