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It’s Official: We’ve Found the Higgs Boson–but Which One?

The views expressed are those of the author and are not necessarily those of Scientific American.

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Potential Higgs to photon decay event as seen by the CMS experiment at the LHC

Higgs to two-photon candidate event as seen by CMS in May 2012

When last we checked in on the hunt for the Higgs, physicists weren’t yet ready to call the deal done. They were only willing to say that they had discovered a new particle—some sort of boson—and that this new boson was “Higgs-like.” Their reticence hinged on the measurement of the new particle’s spin, a fundamental quality that, for bosons, must take an integer value such as 0, 1 or 2. Both in July, when the proto-Higgs was first announced, and in November, when scientists released additional data analysis, they didn’t have enough data to definitively say that the boson had a spin of zero, which a Higgs must have.

That uncertainty has now melted away. This week, physicists gathered in Moriond, Italy announced that additional data from the Large Hadron Collider’s 2012 data run now conclusively show that the new boson has a spin of zero, and is thus a Higgs boson.

The question now becomes: just what kind of Higgs boson is it? And might it have hidden twins?

The Standard Model of particle physics—the extremely successful set of theories that physicists use to understand the universe but which most scientists believe is incomplete—predicts that the Higgs boson should behave in a particular way. Once we know its mass (which we do), the Standard Model precisely determines with what frequency the Higgs should change into other subatomic particles (a Higgs lasts for only a fraction of a second before decaying into other particles; these particles are what scientists measure at the LHC). Because scientists want to deeply probe the Standard Model to see where it fails—thus pointing the way to a new and deeper understanding of physical law—they have been closely monitoring just how the Higgs decays.

Early results indicated that the Higgs-like particle was behaving as the Standard Model predicts—with one intriguing exception. The Higgs seemed to be decaying into two photons about twice as often as it should. Could the discrepancy open a much-anticipated crack in the Standard Model?

Alas, no. New results presented at the Moriond Conference show that the apparent excess in photons was likely a statistical fluke. The Higgs appears to be a boring old Standard Model Higgs boson after all. Physicists hoping to find problems with the Standard Model will have to wait until the data from the next LHC run—which, because of a planned two-year shutdown to upgrade the machine, won’t begin before 2015.

Those who pine for strange Higgs physics now hope for a blockbuster: that the Higgs we’ve discovered isn’t the Higgs boson, but rather only the first of many. According to the decoupling theorem (PDF; see especially slide 15), if the Standard Model is not the whole story of the universe and many different Higgs bosons exist, one of them should look very much like a Standard Model Higgs boson. Therefore, the fact that we’ve seen a Standard Model Higgs boson does not mean that there aren’t additional non-Standard Model Higgs bosons out there waiting to be found.

So chin up, Higgs aficionados. Come 2015, we could be doing the Higgs dance all over again.

Image courtesy CERN/CMS

About the Author: Michael Moyer is the editor in charge of space and physics coverage at Scientific American. Follow on Twitter @mmoyr.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. jtdwyer 5:27 pm 03/15/2013

    Nice report – thanks for the links! 2015 should be interesting, at least…

    I’m just a pedestrian passerby, but since most of the universe’s stable matter is composed of quarks that were produced in the conditions of the early universe, I suspect that the Higgs field is perhaps the varying vacuum energy density at the moment of particle emission, and that mostly zero rest mass photons are produced in the prevailing conditions of the later universe as a result.

    That said, wouldn’t it have been simplest to predict the identified SM Higgs boson properties regardless of the specific details of the mechanism that imparts rest mass to fundamental particles? More directly, does the confirmation of predicted Higgs boson characteristics really confirm the rest mass allocation process (partially) described by the Higgs mechanism?

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  2. 2. jtdwyer 5:43 pm 03/15/2013

    Correction – it’s not that photons are the only particles emitted now, but more massive particles are unstable and quickly decay in the lower-confinement vacuum energy densities.

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  3. 3. Aiya-Oba 7:01 pm 03/15/2013

    Great advances indeed! Congratulations to LHC and Peter Higgs for his great insight. Beyond Relativity model of Physics there is Absolute model of Physics: eternal oneness of pairness, equator of self-contradiction, principle of included middle; the self-creation principle and singularity unit of All in all(Spacetime-Continuum).
    As in the numerical relations:

    123 + 321 = 444

    345 + 543 = 888

    (0123456789 + 9876543210)^10 = 9.99999999×10^99.
    The best of physics is yet to come.
    -Aiya-Oba,philosopher and discoverer of Nature’s Absolute Logic.

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  4. 4. dfresh 3:56 am 03/16/2013

    So many scientists – from so many countries – and so many backgrounds – have worked so diligently – for so long – to reveal the true nature of matter.

    I admire this pursuit and I respect the persistence they’ve shown in their efforts to achieve that goal. I just don’t feel all warm and fuzzy inside about this latest announcement.

    Think about it:

    Six thousand or so top scientists are given a 10 billion dollar particle accelerator to play with – for as long as it takes – to find THE particle (the Higgs boson) that would finally validate the Standard Theory once and for all.

    After colliding protons head on – at close to the speed of light – over 1,000,000,000,000 times, it doesn’t seem that remarkable to me that they have finally found a “chunk” of proton that has the exact physical characteristics they were looking for.

    I find this to be far more remarkable:

    One man – working alone and using no tools aside from his mind and a pencil – has (for the last 60 years) been quietly developing a very convincing theory describing the structure and behavior of atoms and subatomic particles. Although this theory may never be able to be proven experimentally, it is worthy of attention because it seems to resolve many of the mysteries that have baffled physicists for centuries.

    If it interests you, there is a website describing some elements of Jurjen van der Wal’s theory, which can be easily be found by searching “pyramid physics”.

    Perhaps scientists have been concentrating so hard on efforts to validate the Standard Theory that they have been neglecting to consider other possible theories.

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  5. 5. Trafalgar 7:30 pm 03/16/2013

    There are plenty of untestable theories out there which claim to resolve all the mysteries of the universe, but extraordinary claims require extraordinary proof.

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  6. 6. Dennis Fletcher 2:58 am 03/20/2013

    If the Higgs boson truly imparts the characteristic of mass to matter….then the substance of the universe and the behavior of matter as we non-scientists can observe it are all due to this marvellous little God Particle…..we should feel lucky to have it and to begin to understand its existance whether zero, one or two spins.

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  7. 7. M Tucker 2:05 pm 03/20/2013

    Well it might be ‘boring’ to particle physicists now but it wasn’t boring to Peter Higgs when he developed the idea. In fact it took quite a bit of work to get the particle physics community to take notice. The first paper he submitted on the Higgs particle was rejected because it was deemed irrelevant to physics. Higgs did not develop his theory in a vacuum and it might be nice for science writers to mention the work that went into the theory of the Higgs field and the Higgs particle. The journey from published paper to discovery of the particle is long and makes a remarkable tale. Also, the enormously expensive LHC is not unique in the history of physics. Other colliders have been built to discover just one particle and it makes perfect sense that the higher the energy requirements the more expensive and complicated the machine must be.

    For me this is the cherry on top of the icing of the cake of particle physics history. I can remember a time BEFORE the standard model. I can remember when it really was a zoo of exotic, unexpected and bewildering particles. I am glad Higgs was able to live to see the success of discovery and I do not pity the bored particle physicists…you still have much to do. You still have much to explain. We don’t know everything yet.

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  8. 8. Fretka 11:13 am 03/21/2013

    And like the little red-headed child, there sits the force of gravity, smirking!

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  9. 9. Miroslav 11:19 am 03/21/2013

    After colliding protons head on – at close to the speed of light – over 1,000,000,000,000 times, it doesn’t seem that remarkable to me that they have finally found a “chunk” of proton that has the exact physical characteristics they were looking for.

    How would they name a “chunk” created by crashing cars at such high speed? Perhaps they would have created ‘Kiggs car’ having mass roughly 130 times the car’s mass and being many times smaller than a original car.

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  10. 10. GmanMan 10:23 pm 03/21/2013

    What about the possibility of mass being caused by eddies in the Centrifugal force of the spin of sub atomic particles or collisions in their wave field creating offset to a balance based on the geometric shaped of the host atomic alignment?

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  11. 11. GmanMan 10:35 pm 03/21/2013

    Can gravity be giant sound waves that permeate through space with waves so large we could never detect in the normal fashion? Shaking all matter in the vicinity that’s influence is based on the size of it’s wave? Imagine the heavy sounds of our core and mantle rubbing together, the sounds of the nuclear furnace of a star. Maybe there is sound in space but it just takes large enough waves to carry on through the fabrics of space?

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  12. 12. GmanMan 10:40 pm 03/21/2013

    We could detect these so called large sound waves with synchronized sensors. Kind of like how we detect earthquakes now but we need to spread them out a little more and cover more of pi.

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  13. 13. GmanMan 10:44 pm 03/21/2013

    Is there a sequential pattern to pi?

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  14. 14. GmanMan 10:47 pm 03/21/2013

    Unfortunately modern Scholasticism has conformed to a political society where science is now a religion and requires canonization.

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  15. 15. gravitylover 3:44 pm 05/22/2013

    how bout those crazy theories? to me everything is crazy till’ it isn’t
    heres my theory,everything is forever falling till’ it isn’t wow that’s pretty crazy is what your thinking but if u think about it that
    is the only logical explanation to why an object weights less in top of a
    you know how everything is made of atoms right?
    well a bunch of atoms make matter,matter has weight so nothing is weightless but you say how can astronauts
    float around in space well my friend your about to find out.
    they don’t lose weight, they just lose that force that was making them
    heavier know what i’m talking about?
    that force that everyone says is a mystery, what a stupid thing to say,everything has an explanation, you know that guy and his famous apple
    he found out what gravity was but what a shame they didn’t know that
    everything was made of atoms and that atoms are made of positive and
    negative energy and neutrons and that everything small can be made into large so why
    not an atom be kept together by the same force that planets use to rotate
    around a bigger planet,gravity= electromagnetism you know different charges attract, same
    charges repel those are the laws of attraction but what if everything
    was made of small particles that have both positive charge and negative
    charge in them, hmm that would be convenient because then two atoms can
    attract and repel at the same time with equal force and never touch
    like magic wow thank god for atoms what a smart guy, well if he could make everything the same size then nothing would collide
    and explode, did he know that?
    well of course if i know he most have known it all along,
    maybe everything was created the same size to last forever never touching.
    but wait that’s not right aren’t the outer electron in an atom the
    strongest then how would humans survive if god didn’t calculate the size
    distance and force required for humans to live and move freely on earth? well he did add every atom that makes the earth and every atom
    that makes the sun and every atom that makes every star so they would be
    perfectly balanced and be able to coexist and fall freely into the vast
    nothingness of space. by the way time doesn’t move and space doesn’t contract unless there is hard prove that space is made of something.

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