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New zoom in on the Higgs mass from Summer 2008 Tevatron results! July 31, 2008

Posted by dorigo in news, physics, science.
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Many thanks to Sven Heinemeyer, who provided me this morning with a fresh update of the traditional plot summarizing the status of Standard Model measurements of top quark and W boson masses, their consistency with SM and SUSY, and their impact on the Higgs boson mass. Have a look at it below (a better version, in .eps format, is here):

As you can see, the consistency between direct determinations at the Tevatron (blue ellipse) and the LEP II(black lines) and LEP I/SLD results (hatched purple lines) is still quite good.

One detail worth mentioning: when plotting a 68% CL ellipse atop a 68% interval, the interval will look more restrictive in the variable which is measured (in the case of blue and black lines, the W boson mass, which is in the Y axis), because of the need of the ellipse to extend way past the 1-sigma limits to accommodate a total area of 68%.

The Tevatron results on the W mass are no worse than the LEP II ones by now – and they are based on only one experiment -CDF- analyzing a twentieth of the currently available data! The W mass reach of CDF is estimated at 15 MeV, a result three times better than the current one.

So, there is still a lot to squeeze from Tevatron data, despite the update you are looking at now “only” includes an improved measurement of the top quark mass, which now sits at 172.4 +-1.2 GeV – a 0.7% accuracy on this important parameter of the Standard Model.

It remains me to congratulate with my colleagues in CDF and D0 for their continuing effort. Well done, folks!

UPDATE: a commenter asks for the 95% CL ellipse in the plot above. I advise him and whomever else wants much more information to visit Sven’s site.

Also, two other blogs have posted today discussing this result: Lubos Motl and Marco Frasca. NB: Lubos advertises his blog in the comment section below, and he says he did a much better job than me in discussing the new results… I believe him: I wrote mine with my kids running around, asking me to finally leave for a hike on the mountains. I believe Lubos has no kids so… Enjoy!


1. Big Vlad - July 31, 2008

can I see the 95% confidence limit ellipse?

2. cecil kirksey - July 31, 2008

Nice chart, but could you now provide your best estimate for the Higgs mass? I look at the cahrt and say there is a problem with the current range of Higgs mass and the 68% Top mass ellipse.

3. hktelemacher - July 31, 2008

Wow, I sure wish I understood any of that. I really do.

4. Sven - July 31, 2008

The effects of the new top quark mass measurements on the Higgs mass fits have been presented in a talk by Peter Renton at the ICHEP 2008 conference. You can find the talk here: http://www.hep.upenn.edu/ichep08/talks/misc/schedule

The new fit value for MH is 84+34-26 GeV with an upper limit of 154 GeV at the 95% C.L.
A corresponding update of the fit for the lightest CMSSM Higgs boson mass has not yet been performed.

5. Higgsy - July 31, 2008

Just curious if you can provide any info on the ZZ production that was announced this morning?

6. Luboš Motl - July 31, 2008

Thanks for your report. I wonder why you don’t mention to your readers what the result is and what does it mean for the Fermilab ellipse to sit inside the MSSM strip. 😉

A somewhat superior report with a working link to Renton’s talk is here:


7. Quasar9 - July 31, 2008

Hi Tomasso, been a little busy with building work at the villa (and little or no time for the internet or blogging in July)

A sort of working holiday – lol!

But I hope to have time to catch up and keep abreast of my favourite blogs in August.

Good to see you are still keeping a close eye on the ever elusive higgs

8. Big Vlad - July 31, 2008

which values of the MSSM parameter space are varied to get the green band in the plot? is it just tan(beta) and M_A ? do the soft breaking terms make a difference to the plot?

really interesting work by the way 🙂

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10. dorigo - July 31, 2008

Hi Higgsy,

I plan to do some review of ZZ searches at the Tevatron tomorrow, if I find the time.

Vlad, please see my update in the post above.

hktelemaker, this blog offers you the chance to do so. Please visit the “physics made easy” section. You will find some plots describing in easier terms and more detail the plot you are looking at above.

Hi Lubos, thank you for your post too.

Hello Quasar9, welcome back! Please visit often and let me know if there’s anything in particular I could offer to review here, among new Tevatron results. I also have little time this summer (you can sort of notice it from my reduced throughput here) but I’ll see what I can do…

Vlad, Sven’s plot is best described in his web page. But I would also advise you to read his latest preprints, which discuss how one can fit together electroweak observables and cosmological constraints, together with b-physics observables, in the context of some constrained SUSY scenarios. Check, for instance:



11. John Baez - August 1, 2008

hktelemacher wrote:

Wow, I sure wish I understood any of that. I really do.

It would help if the vertical axis of the graph were labelled. From the remarks above the graph, a naive reader might guess it stands for the Higgs mass (since the horizontal axis is the top quark mass). By cheating and peeking at the “better version in eps”, I discovered it’s the W mass.

12. Sven - August 1, 2008

Vlad, the green band has been obtained by varying all relevant parameters of the MSSM (about 20) independently. Therefore the green band really represents the general prediction of the MSSM (well, ok, we left out points with a very large mass splittings between stops and sbottoms, which result in W masses that are even larger (and experimentally excluded)). If you want to know more details, check p38 in http://arxiv.org/abs/0710.2972 .

13. Absalom - August 1, 2008

Tommaso, I’m surprised that you consider Motl’s report superior. You don’t really think that he actually *understands* this stuff, surely?
Anyway, thanks for your superfluous-rhetoric-free version.

14. dorigo - August 1, 2008

John, instead than cheating, next time read the post 😉 it’s in plain sight: “The Y axis is the W mass”.

Absalom, maybe irony is not my forte, but I thought it transpired. Thank you for visiting.


15. Luboš Motl - August 1, 2008

Dear Tommaso, your criticism that John should learn how to read is fair but if you look at my article, you will see that his criticism couldn’t apply to my picture!

But don’t try to be as perfect as me because otherwise kilotons of stupid people will hate you! 😉

16. John Baez - August 2, 2008

So, the label of the graph’s axis is tucked away down there in a parenthetical remark a paragraph down… sneaky! Usually people put it on the graph,so lazy people like me can see what’s going on.

17. Myke - August 2, 2008

Tomasso, I was asked today how your coloured squares on the right are allocated to your correspondents. I don’t know, so could you please explain, thanks…


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I love your blog…really. Did you already hear about water on mars? 🙂

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