Higgs Territory Continues To Shrink

PhysicsDavid writes "Announced this morning by Fermilab, the possible territory for the Higgs boson has shrunk even further. Combined results from the CDF and DZero experiments at the Tevatron have ruled out the existence of the Higgs with a mass between 160 and 170 GeV/c^2 with 95% confidence. At 90% confidence the Higgs is ruled out between about 157 and 185 GeV/c^2. Here is Fermilab's press release. If the Higgs is to be found at the lighter end of the currently allowed range of 114 GeV/c^2 to 185 GeV/c^2, its detection will be harder than at the heavier end due to the kinds of signals that the Large Hadron Collider and the Tevatron will see. Some physicists think that a lighter Higgs will be easier to spot at the Tevatron as the background processes which obscure the faint signal are not as prevalent in those experiments."

Comments

Wow!

[Bruce Perens]

This is so cool! I get a hadron just thinking about it :-)

Not boring!

[Roger W Moore]

The fact that this is all that's left of high energy physics says a lot.

The fact that you say this shows that you do not know a lot about high energy physics. Even if the Higgs does exist somewhere in the gap shown there is a huge problem trying to explain why it has such a small mass compared to the scale where gravity is important and the Standard Model has to break down. The chances of this occuring by pure chance are about the same as you winning the UK national lottery for about 5 weeks in a row - if you did that people would not be thinking 'wow you are incredibly lucky' they would be wondering how on earth you cheated the system. Similarly we need to figure out how the universe 'cheated' and made the Higgs mass so light.

There are also several other questions we need to solve: what is all the dark matter?, what is all the dark energy?, why is there no anti-matter in the Universe?, is the neutrino its own anti-particle?, how does quantum gravity work? etc. etc. You need to remember that so far all of science has been based on the 4% of the Universe made of atoms. 96% of the Universe is made of stuff we do not understand so thinking that the Higgs is all that is left is just crazy talk!

Re:Not boring!

[Roger W Moore]

The GP would have been more accurate to say something more limited, like referring to "high-energy physics from the LHC"....It's possible that Fermilab will discover the Higgs

Not true. The Tevatron will not get to a 5 sigma discovery significance unless the LHC is delayed by several years more - the best they can hope for is 'evidence' of the Higgs, and event that is somewhat doubtful. However there are very good theoretical arguments that the LHC should be able to reach the Dark Matter scale as well as finding some evidence to explain the Higgs low mass. These are certainly not certainties but they are certainly well motivated possibilities.

There's a strong possibility that all of these questions will turn out to be ones that can't be answered by LHC-style accelerator experiments.....For instance, the LHC doesn't come anywhere near the Plank energy scale, so there's virtually no chance that it will give any insight into quantum gravity.

Sorry but you are also wrong here. There are extremely good arguments regarding thermal production of dark matter that suggest the particle cannot have more than ~1TeV mass unless it is not thermally produced. As such it is likely that we will produce it at the LHC and, if not the LHC, it could be produced in a higher energy accelerator since these recreate the conditions just after the Big Bang where the Dark Matter has to be produced (unless you believe a certain amount of Dark Matter was one of the starting conditions of the Big Bang).

Regarding the Planck scale you only think that it is unreachable because gravity is so weak. If there are extra dimensions of space then the Planck scale might only be a few TeV and then we can do quantum gravity at the LHC. Personally I find this far less likely than finding Dark Matter but it is certianly a possibility. Plus, while the neutrino questions need fixed target or underground experiments to answer these are still particle physics, and there is more to particle physics than the LHC!

The trap you seem to be falling into is that because there is no guarentee that something will be seen there is no chance of seeing it. While it is certainly true that there is no strong guarentee of seeing more than just the Higgs (or whatever else it might be) there are good theoretical motivations to expect to solve some of these other problems. You cannot say whether it is a strong or weak possibility because we do not know enough to assign any meaningful chance. All we can say is that there is a possibility and there is some good theoretical motivation for such a possibility based on reasonable assumptions. Sometimes those assumptions can of course be wrong...but not always in a 'bad' way.

Re:Easier vs. Harder

[geekoid]

"...any data is greater than the zero the LHC will have accumulated."

BURN!