Eureka Moment: New Particle Discovered At Tevatron?
By on April 7th, 2011

This is big, really big! This may be the biggest news to hit the particle physics world in the the last 50 years. Scientists, analyzing the data collected at the Tevatron, Fermilab, have detected an anomaly that could well usher in a new dawn in theoretical physics and change the Standard Model as we know it now. The observation was a bump in the data, but in the ‘wrong’ place.



Scientists are excited about a Gaussian peak that has been observed on Wednesday, 6th April, centered at about 150 GeV with a spread of 2.5 GeV, corresponding to nearly 300 events.

Data Analysis:

Physicists are generally quite skeptical about any news of big breakthroughs. This ensures that the discoveries are really authentic. Most ‘discoveries’ are just mistakes in the code being used for data-analysis, or some human error or plain background fluctuations. All of these have to be ruled out. Coding errors can be ruled out by using many orthogonal samples of data, called ‘control sets’. Background fluctuations take a bit more effort, but routine analysis can eliminate it almost completely. A peak left after background elimination cannot be discarded.

Notwithstanding the fact that physicists are extremely skeptical, almost all major discoveries in high energy physics have been accidental. The key to such a discovery is rigorous analysis of data.

Is this the Higgs Boson?

The knee-jerk reaction was to suspect the discovery of the Higgs, the bosonic particle that is believed to endow all fundamental particles with mass. The Higgs boson, however, is ruled out, because if the Higgs could be produced at 140 GeV at a non-negligible rate, then we expect to see the characteristic decay jets, which would consist, mainly, of bottom quarks. However, such jets have not been observed, ruling out this possibility.

Higgs Event at CMS

Higgs Event at CMS, LHC

Is this a new force of nature?

It is too early to comment. The discovery of a new particle – a new boson – has to be confirmed. Only further investigation can answer this question.

What could fit the fill?

A new particle, which was coincidentally proposed in a paper a few days back, could fit the bill. The particle is called the Z’ boson, as compared to the Z boson. The Z’ boson is expected to decay via semi-leptonic (i.e. a mixture of hadrons and leptons) channels. Semi-leptonic jets have been observed. So, maybe, the Z’ is the ‘new’ particle.

Decay event for the Higgs

Higgs Decay

Confidence Levels:

The result now stands with a 3-sigma confidence level. This means that the possibility of ruling out the observation as a statistical fluctuation is less than 1 percent. Physicists look for a 6-sigma confidence level, which means that the doubts should reduce to less than 0.003%. To attain this level of confidence, scientists will need more sets of data and rigorous analysis of the same.

More data is on the way. As Prof. Nima Arkani-Hamed of the Institute for Advanced Studies, Princeton, notes, LHC should come up with much more data and copious events, if this is indeed a real discovery.

An Event at the Large Hadron Collider

A Collision Event at the Large Hadron Collider

One thing is for sure: this is exciting. If this is true, this is pure gold for particle physicists.

UPDATE: Fermilab rejects new particle discovery after extensive data analysis. Read here.

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Author: Debjyoti Bardhan Google Profile for Debjyoti Bardhan
Is a science geek, currently pursuing some sort of a degree (called a PhD) in Physics at TIFR, Mumbai. An enthusiastic but useless amateur photographer, his most favourite activity is simply lazing around. He is interested in all things interesting and scientific.

Debjyoti Bardhan has written and can be contacted at
  • Yehoshua Ghitis

    Well, i believe this is an incredible discovery, a new particle wow!
    But the pictures look like a 5 year old’s scribbles and i don’t get them, sorry.

    • Debjyoti Bardhan

      The tracks are seen in cloud chambers when charged particles pass through them. This helps scientists track particles. Much information can be obtained by observing the tracks. But, true, they look like scribbles made by a 5 year old, except that they follow laws of nature.

      • Tommy

        .. then a very smart 5 year old, with excellent hand-eye coordination.

  • Christina

    Very intriguing. Thanks for posting! Could mean something truly big!

  • mtravers

    I think the most important point is the article is that “almost all major discoveries in high energy physics have been accidental.” That should tell us something about the entire process.
    As an alternative to Quantum Theory there is a new theory that describes and explains the mysteries of physical reality. While not disrespecting the value of Quantum Mechanics as a tool to explain the role of quanta in our universe. This theory states that there is also a classical explanation for the paradoxes such as EPR and the Wave-Particle Duality. The Theory is called the Theory of Super Relativity and is located at: Super Relativity website. Google it.
    This theory is a philosophical attempt to reconnect the physical universe to realism and deterministic concepts. It explains the mysterious.

  • Ujjwal Kanth

    I have to say that you have drawn my attention back to particle physics, which i left long time back.
    But as a reader i would suggest you tone it down a little. It may be too much for readers who don’t know much about the science of particles but yet are interested.
    Also i would end up saying, if you truly understand every bit of what you have written, you are my idol, i will bow down to you…

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