Department of Physics & Astronomy

Robert Clare

Robert Clare

Robert Clare


Physics 3021

Telephone: 951-827-5335
Email: robert.clare@ucr.edu
Fax: 951-827-3345

Research Interests:

  • Experimental High Energy Physics


Ph.D. 1982, Massachusetts Institute of Technology

Current Research:

Professor Clare has been a leader in the studies of electroweak physics for many years. He chaired the LEP Electroweak Working Group from 1996-2001, which was responsible for combining the results of the 4 LEP experiments to obtain the best possible constraints on the Standard Model. The data led to predictions of the top quark mass before it was discovered at the Tevatron. With the latest measurements of the top quark mass at the Tevatron and W boson mass at both LEP and the Tevatron, the data have been used to predict the Higgs boson to be lighter than about 300 GeV. This was well within the discovery potential of the experiments at CERN's Large Hadron Collider (LHC), and, indeed, in 2012 both the Compact Muon Solenoid (CMS) and ATLAS announced the observation of the Higgs Boson at about 125 GeV.

Professor Clare and his team have been involved in the commissioning of CMS, the data taking and subsequent analysis of CMS. Currently, the LHC is in the middle of a two year shutdown, after which the machine energy will go up from 8 TeV to 13 TeV. While the accelerator is being improved, so too is CMS. Prof Clare's group is heavily involved in the upgrades to the end-cap muon system. An additional 72 muon chambers have been constructed, tested and are now installed in CMS. The group is also involved in the detector control system for the end-cap muon detector.

The physics that his group is involved in revolves around the Higgs boson. One activity will be the measurement of the Higgs into a pair of muons. In the Standard Model, the coupling of particles to the Higgs is proportional to the square of the mass of the particle. Since muons are relatively light, the branching ratio of the Higgs to muons is very small. Nevertheless, it is an important measurement to make as any deviations could be indications of new physics. Another topic is the search for additional Higgs bosons which are predicted by some theories, including supersymmetric models.

The computing resources necessary to analyze the CMS data will be enormous, as approximately one Petabyte of data will be recorded per year. UCR is involved in establishing US-based computing facilities to allow physicists to participate in the analysis from their home institutes. This requires hardware and software to work in a distributed grid of world-wide resources. Currently available at UCR is a cluster consisting of 240 cores and about 100 TB of disk storage. The cluster is a Tier-3 center, part of the CMS world wide computing system. Professor Clare helps organize the Tier 3 computing for all of the US institutions in CMS.

Selected Publications:

  1. Observation of a new boson with mass near 125 GeV in pp collisions at √s = 7 and 8 TeV, CMS Collaboration, JHEP 1306 (2013) 081.
  2. Measurement of the tt Production Cross Section in Collisions at √s = 7 TeV using the Kinematic Properties of Events with Leptons and Jets”, CMS Collaboration, Eur. Phys. J. C71, 1721 (2011).
  3. Performance of CMS Muon Reconstruction in Cosmic-Ray Events, CMS Collaboration, JINST 5, T03022 (2010).
  4. Performance of CMS Cathode Strip Chambers with Cosmic Rays”, CMS Collaboration, JINST 5, T03018, (2010).
  5. The CMS experiment at the CERN LHC, The CMS Collaboration, JINST 3, S08004 (2008).
  6. Precision Electroweak Measurements on the Z Resonance, The ALEPH, DELPHI, L3, OPAL and SLD Collaborations, Physics Reports 427, 257 (2006) [arXiv:hep-ex/0509008].
  7. Measurement of the mass and the width of the W boson at LEP, The L3 Collaboration, Eur. Phys. J. C 45, 569 (2006) [arXiv:hep-ex/0511049].
  8. The CMS high level trigger, The CMS Collaboration, Eur. Phys. J. C 46, 605 (2006) [arXiv:hep-ex/0512077].
  9. Measurement of the cross section of W-boson pair production at LEP, The L3 Collaboration, Phys. Lett. B 600, 22 (2004)
  10. Present and future electroweak precision measurements and the indirect determination of the mass of the Higgs boson, U. Baur, et al., [arXiv:hep-ph/0202001].
  11. Measurement of the W-pair Production Cross Section and W-Decay Branching Fractions in e+e- Interactions at √s = 189 GeV, The L3 Collaboration, Phys. Lett. B 496, 19 (2000).
  12. Measurements of Cross Sections and Forward-Backward Asymmetries at the Z Resonance and Determination of Electroweak Parameters, The L3 Collaboration, Eur. Phys. Jour. C 16, 1 (2000).
  13. Measurement of the Properties of the η' and Search for Other Resonances in γ γ -> η π0 π0, The Crystal Ball Collaboration, Phys. Rev. D 36, 2633 (1987).

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