Experimental High Energy Physics (HEP)
The Baylor Experimental High Energy Physics (HEP) group is engaged in an active research program on the Compact Muon Solenoid (CMS) experiment at CERN in Geneva, Switzerland. By performing cutting-edge measurements with proton collisions at the energy frontier, the group is probing the properties of the Higgs boson and other elementary particles while also seeking new physics discoveries such as the origin of dark matter.
Baylor University established a new program in experimental high energy physics (HEP) in 2003 with the hire of Prof. Jay R. Dittmann. Prof. Kenichi Hatakeyama and Prof. Andrew Brinkerhoff joined Baylor as new faculty members in this research area in 2009 and 2019, respectively. From its formation, collider physics has been the emphasis area of the Baylor experimental HEP group. In addition to our current research at CERN, the group has recently joined the CalVision Collaboration to work on detector R&D for future Higgs factories. Previously, the group also performed research at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois.
HEP Research at CERN
The Large Hadron Collider (LHC) at CERN launched a new era for particle physics on March 30, 2010, when protons collided for the first time at a record energy of 7 TeV. These collisions marked the start of a decades-long LHC research program, and the beginning of the search for discoveries by thousands of scientists around the world. In 2012, the collision energy increased to 8 TeV. Following a shutdown for improvements during 2013–2014, the LHC collided protons close to its design goal of 13 TeV and operated through Run 2 (2015–2018). Currently, we are in the third data taking period, called Run 3 (2022–2025), collecting data of proton-proton collisions at 13.6 TeV.
Since Baylor joined the CMS experiment in 2010, Baylor HEP group members have played a major role in data analysis, experimental operations, and upgrade projects. As of Fall 2024, ten current and former Baylor postdocs have worked on the CMS experiment, and seven Ph.D. graduate students (Ahmad Borzou, Ken Call, Chris Madrid, Caleb Smith, Bryan Caraway, Ankush Reddy Kanuganti, and Brooks McMaster) defended their Ph.D. theses based on their analyses of data collected at CMS.
The group's recent physics analyses include Superymmetry (SUSY) searches and analyses in the Higgs boson and top quark sectors. In the SUSY realm, we have worked on inclusive searches in the all-hadronic final state, searches for top squarks decaying hadronically, a new search for electroweak SUSY producing energetic “boosted” W, Z, and Higgs bosons, and most recently searches for stealth SUSY top squark production. The group also performed a search for new physics in ttZ and ttH events with a high-pt Z or Higgs boson decaying to bb, probed Z or Higgs pt over 450 GeV for the first time, and placed competitive constraints on new physics models parametrized using effective field theory (EFT). In the Higgs physics sectors, the group has worked on a new search for Higgs pair (HH) production with both Higgs decaying via W bosons or τ leptons to a multilepton final state and a search for Higgs decays to new light scalars a. We have integrated Baylor’s HPC into Open Science Grid, and we use it for these data analysis efforts.
Our group members also work on the operations and upgrade of the hadron calorimeter (HCAL) of the CMS experiment. The CMS detector consists of several subsystems, and the hadron calorimeter measures energies of the hadrons (pions, kaons, protons, neutrons, etc). The group played important roles for the electronics upgrade of the hadron calorimeter as well as software development and validation for the hadron calorimeter readout, and we making significant contributions to HCAL operations through Run 3. We have established a test stand at Baylor that exactly replicates the HCAL readout at CERN, allowing us to investigate HCAL operational issues in the U.S. in parallel to studies at CERN.
The group also plays an important role for the “Phase 2” upgrade endcap calorimeter, also known as the High Granularity Calorimeter (HGCAL). Our current work on HGCAL is mainly in the areas of HGCAL electronics development, testing, and HGCAL reconstruction, in particular its integration into the particle flow reconstruction. The group will be testing about 24,000 custom HGCAL components called concentrator mezzanine cards through 2024–25.
The Baylor HEP group also works on various aspects of CMS level-1 trigger (L1T). Enabling new, high-quality searches in Run 3 and Phase 2 is a key focus of our contributions to the L1T project. The Baylor team leads the L1T data monitoring effort in Run 3, organizing rapid run-by-run validation, developing automated tools, and taking operational shifts at CERN and remotely. The group also provided L1T jet energy calibrations for Run 3 using a new machine-learning-based regression algorithm.
In addition, the group has extensive experience in reconstruction software through our leadership in the CMS Particle Flow (PF) group. Baylor has led the effort to make the computationally intensive part of the PF software parallel-friendly, porting it to run on heterogeneous computational resources. Integration of detector advancements into PF reconstruction, another task performed by our group, is a critical task for upcoming high-luminosity LHC operation.
Higgs Boson Discovery
The 2013 Nobel Prize in Physics has been awarded to Francois Englert and Peter Higgs for their prediction of the Higgs Particle in 1964. Members of the Baylor High Energy Physics group are associated with the CMS experiment at CERN, one of the two teams that announced the discovery of the Higgs in July 2012.
The High Energy Physics group at Baylor was involved in the search for the Higgs boson since 2006. Over a period of years, two faculty members (Drs. Jay Dittmann and Kenichi Hatakeyama), three postdoctoral research associates, four graduate students, and one undergraduate student were directly involved with the Higgs both at Fermilab and CERN. Our contributions on the CMS experiment include improving the measurement of a variable called missing transverse energy and validating data and software associated with the hadron calorimeter.
Resources describing U.S. involvement in the Higgs Discovery:
The Discovery of the Higgs Boson: America's Role (YouTube Video)
The LPC at Fermilab and the Higgs discovery (PDF Poster)
HEP Research at Fermilab
Led by Dr. Jay Dittmann, the Baylor HEP group stayed active on the Collider Detector at Fermilab (CDF) experiment from 2003–2012. For over two decades, the CDF experiment collected data from the collisions of protons and antiprotons accelerated to nearly the speed of light by the powerful Tevatron accelerator. Although the Tevatron was decommissioned on September 30, 2011, physicists continued to complete analyses and publish new results using the proton-antiproton collision data.
Since the beginning of 2011, four Ph.D. graduate students (Sam Hewamanage, Martin Frank, Karen Bland, and Zhenbin (Ben) Wu) successfully defended theses based on their analyses of data collected at CDF. Sam focused on a study of proton-antiproton collisions in which a photon emerges directly from the collision together with ’jets’ of energetic particles. Using these data, it is possible to test the predictions of QCD and search for ’anomalous’ physics that could include the production of new, undiscovered particles. Martin and Karen worked in analysis groups that searched for the infamous Higgs boson, whose discovery was one of the most outstanding discoveries in particle physics! Martin was a key player in the analysis to discover the Higgs boson in the WH channel, and Karen actively investigated the case where a Higgs decays into two photons. Ben wrote a thesis on measurements of single top production - the single top cross section and the CKM matrix value Vtb - in the lepton plus jets final state. These measurements investigate properties of the electroweak interaction and test the possibility of physics beyond the Standard Model.
Funding for the Experimental High Energy Physics group at Baylor is provided by grants from the U.S. Department of Energy and Baylor University.
Group links: