A New Particle Detected at Fermilab? Maybe. Maybe Not.

The physics blogosphere has been abuzz1,2,3,4,5,6,7,8 for the last few days about an arXiv.org preprint9 from the Tevatron CDF Collaboration at Fermilab, and the New York Times has picked up on the story.10 Keep in mind that it is only a 3.2-sigma bump in the data that has generated the excitement, barely discernible from background noise. The Tevatron will be shutting down later this year, so it will be up to the Large Hadron Collider at CERN, the only other accelerator powerful enough to reach the energy ranges in question, to either confirm or refute the findings, but the LHC only has about 1/fb of data to go on so far. Also, this analysis is based upon 4.3/fb of collision data. By the end of the Tevatron’s run, the CDF team will have 10/fb of collision data to go through. No word from the D0 team at Fermilab as to whether their data shows a corresponding effect.

The apparent ~150 GeV resonance does not seem consistent with a Standard Model Higgs boson (the tiny bump is actually about 300 times too large for that), or any other expected particle. It could be an entirely new and unexpected type of Higgs boson, a different particle altogether, or the result of experimental or analytical error. It is not at all uncommon for 3-sigma results to turn out to be statistical flukes. (If further data should bump this up to a 5-sigma result, then things get really interesting.) Of course, this uncertainty hasn’t prevented other researchers from scrambling to see if these results fit with their own pet models.11,12




A long overdue update (November 13, 2011):

The D0 team at FermiLab has poured over their data, and have found no corresponding bump. See here, here, and here.

1. Flip Tanedo, “A hint of something new in “W+dijets” at CDF”, US/LHC Blogs.
2. Sean Carrol, “Anomalies at Fermilab”, Cosmic Variance Blog.
3. Marco Frasca, “A new particle at Fermilab”, The Gauge Connection.
4. Adam Falkowki, “Another 3 sigma from CDF”, Resonaances Blog.
5. Peter Woit, “Suspicious Bump”, Not Even Wrong.
6. Tommaso Dorigo, “Is That A New Massive Particle? Is That Some Kind Of Higgs?”, A Quantum Diaries Survivor.
7. Tommaso Dorigo, “More Thoughts On The New CDF Signal”, A Quantum Diaries Survivor.
8. Tommaso Dorigo, “The Jet Energy Scale As An Explanation Of The CDF Signal”, A Quantum Diaries Survivor.
9. CDF Collaboration, T. Aaltonen, et al. “Invariant Mass Distribution of Jet Pairs Produced in Association with a W boson in ppbar Collisions at sqrt(s) = 1.96 TeV”, submitted to Phys. Rev. Lett. arXiv:1104.0699v1 [hep-ex]
10. D. Overbye, “At Particle Lab, a Tantalizing Glimpse Has Physicists Holding Their Breaths”, New York Times, April 5, 2011.
11. Eichten et al. “Technicolor at the Tevatron”, arXiv:1104.0976v1 [hep-ph]
12. Buckley et al. “Light Z’ Bosons at the Tevatron”, arXiv:1103.6035v2 [hep-ph]

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About Glen Mark Martin

MCSE-Messaging. Exchange Administrator at the University of Texas at Austin. Unrepentant armchair physicist.
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