Breaking news: Click this link (direct link) to watch a D0 (Marco Verzocchi) and CDF (Tom Wright) shared talk about the new Tevatron results for ICHEP. (Real Player needed.) The talk could shed some light on the Higgs rumors. The seminar began at 11:00 pm Prague Summer Time on July 16th. CDF reported nothing interesting in a professional talk. The D0 had "results not gossips" in the title and we're promised to hear a clarification of some rumors. However, the D0 chap also says that there are (mostly combined) results that have not yet been reviewed - and won't be described today. D0 discussed many more searches for new physics - including leptonic jets and various (other) SUSY particles' decays. Nothing has been found in new physics. D0 began to discuss Higgs searches by showing Tommaso Dorigo's famous gossip post. ;-) Many channels were discussed, no significant excesses anywhere. Even the b+H production described below was denied by the data. Marco Verzocchi victoriously announced that despite the bloggers' hopes and rumors they (and others) were told, they're completely impotent in finding anything interesting, too. ;-)
The summary: Tevatron Higgs 404 error: file not found
News: Rumors denied by the Fermilab's spokesgirl
A TRF reader who may be described as an achieved physicist and whose name can be found if you study the recent comments carefully has brought us some amazing details about the Higgs rumor at the Tevatron.
I don't want to overexpose him so I will only add his name to this article if he tells me to do so. He wrote:
On a completely different issue, I've heard that there's a rumor going around Aspen that the Tevatron will be announcing discovery of gluon + b → b + Higgs, which would then require large tan(beta), which would fit the MSSM. I guess we'll find out in a couple of weeks.At 5:50 pm, this rumor was confirmed to me in a private communication with a particle physicist who is even more famous and whose name will remain secret but if you omit "a" and "the", the titles of his newest 6 papers at SPIRES begin with ULGDSL (starting from the newest one). ;-) He is skeptical about the rumor but heard it, noting that the statistics is supported by 3 bottom-quark events.
If this is true, it's much more accurate and much more juicy than Tommaso Dorigo's version of the same rumor! Your humble correspondent would also be likely to win a $10,000 bet with Jester at Resonaances (without losing $100), among other bets. But needless to say, the real value of the discovery would be priceless.
The particular process,
gluon + bottom → bottom + Higgswould be both unexpected and highly consequential. In Five faces of the God particle, I explained why the Minimal Supersymmetric Standard Model (MSSM) requires two Higgs doublets that produce five physical states. Both Higgs doublets participate in the electroweak symmetry breaking and both of them are needed to produce masses of particles.
But I haven't told you that they generally do so to different extents. The ratio of the two Higgs doublets' vacuum expectation values
tan beta := H0u / H0d- which is what they use to break the electroweak symmetry - is known as "tan(beta)", the tangent of a new angle relevant for supersymmetry.
The popular values in the supersymmetric model building go between 2 and 50 - they can be relatively small but also very high. It's been believed that the interval 2-50 is needed for the couplings to remain perturbative up to the Planck or GUT scale. However, the uplifted supersymmetry region, recently promoted by Dobrescu and Fox, can go well above 50. Note that the uplifted SUSY was also mentioned as a natural explained of the recent D0 claims about a new source of CP-violation...
When you return to high but not too high values of tan(beta), it's very natural for this quantity to be reasonably high - for several reasons. In MSSM, the up-type quarks only obtain masses from the interactions with the up-type Higgs. Similarly for bottom-type quarks. Because the top quark is near the electroweak scale and the bottom quark is about 40 times lighter, it's natural to think that the couplings are actually comparable - of order one - and the mass differences come from the difference of the Higgs vevs.
The previous rule is actually required by SO(10)-like grand unified theories (see Hall et al. 1993) to obtain the right Yukawa couplings for the third-generation heavy fermions - the top quark, the bottom quark, and the tau lepton.
Also, a large value of tan(beta), above 30 or so, is desirable to solve the soft CP-problem in sufficiently minimal models of gauge-mediated supersymmetry breaking.
The observed process
And the process that has been seen by the Tevatron according to our detailed rumor - the "associated production of SUSY Higgs and b's" - only appears is tan(beta) is large. So you not only find two Higgses but you also find that one of them is more important than the other - a feature that only becomes natural in supersymmetric models.
To see why the Higgs-bottom associated production is natural with large tan(beta), check the 2000 report of the Tevatron Higgs working group (I know two co-authors in person and know that they're at the top) where the Higgs-bottom associated production is mentioned in the last sentence of the abstract - and throughout the paper, especially on pages 29-31 (32-34 of 187 in the PDF file). A large tan(beta) is useful to enhance the cross sections - that go as tan^2(beta) - which is why the Fermilab physicists chose this process as one of their favorite places to look (because there's a bigger chance to see something).
(However, the 2000 paper above only uses the "gg" or "qq*" initial states; the mixed "gq" initial state (from the rumor) is omitted in the 2000 paper, for reasons that seemed to be a negligence to me.)
If true and relevant, the observation would be just huge. But my prominent source who is skeptical about the observation recalls an observation two years ago or so when similar four bottom-quark events were used to claim something similar, with tan(beta) above 100. At those times, related events involving tau leptons helped to strengthen a consistent picture. But the claims faded away - they were never published, in fact.
One year ago, the Tevatron published a paper (arXiv, from my birthday) about the associated production of bottom and Higgses (where Higgses decay to taus) and claimed that everything was consistent with the background hypothesis, eliminating a big portion of MSSM.
I am going to investigate (and calculate) a little bit more...
Consequences of a light Higgs
See also another related Tuesday article, What a light Higgs would mean for the future of particle physics.
Tommaso Dorigo argues that this rumor above could actually be different from his rumor, and moreover he has rumored my rumor before - one month ago.
The argument that it's a different rumor is that he claims that the bottom-Higgs associated production would be linked with a 150 GeV Higgs boson - which would have to be be the heavier one, "H", in SUSY, not the lighter one, "h", so it couldn't coincide with his "light Higgs" observation.
Clearly, your humble correspondent can't compete with Tommaso Dorigo in the number of rumors he propagates. Dorigo has already spread rumors by/from most of the janitors at CERN and Fermilab, too. :-) Many of his rumors will refer to indefensible interpretations of the observations. If one of them were right, it would still be amazing. However, I can imagine that both of the rumors described above will actually turn out to be right simultaneously.