Symmetry factor

You might remember my old post, “An old joke“, where I recall a joke list provided by Joe Lykken, which outlines 10 reasons why particle physics is cooler than biology. My colleague and friend here at WSU Peter Hoffmann provided a “balanced response” to this list, providing his own “10 top reasons why biological physics is cooler than elementary particle physics.” I am a fair guy,  so here it goes:

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 10 top reasons why biological physics is cooler than elementary particle physics

1. Biological physics: can cure cancer
   Weak force: gives us cancer.

2. Biological physics makes us talk to chemists, biologists, medical researchers, materials scientists
    Elementary particle physics makes us talk to… other elementary particle physicists, so it really is a type of intellectual inbreeding.

3. Biological physics: Atoms, molecules, proteins, DNA
    Elementary particle physics: German cottage cheese (’quark’); ‘quark’ also means ‘nonsense’ in German.

4. Biological physics: 100% of life
    Elementary particle physicists: 5% of the universe, the remaining 95% they don’t even know what it is.

5. Biological physics: Understanding of genetics, cancer, how cells work and only costs a few million dollars
    Elementary particle physics: has already cost us many, many billions and now they tell us that they don’t even know what 95% of the universe is made of!

6. Darwin: Nice beard
   Wilzcek: No hair, no beard.

7. Hot topics: Biological Physics: Single molecule manipulation, DNA computers, Nanobots
    Elementary Particle Physics: confirming the Standard model for the zillionth time, non-existing pentaquarks, unsolvable theories with no predictions (string theory).

8. Biological Physics Promises: Cure cancer, Alzheimers, grow replacement organs.
    Elementary Particles: A few billion dollars to not find Higgs boson.

 9. Biological physics: Publish papers under your name for work you have really done.
     Elementary particles: Publish with 500 other people for work you had nothing to do with.

10. Biological Physics students: Set up your own equipment for experiments you designed and make interesting observations.
      Elementary Particles students: Watch a display in a big accelerator you didn’t design and  that most of the time doesn’t do anything interesting anyways.

BONUS:
11. Biological Physics theory: Gene maps, protein structure, single molecule dynamics.
      Elementary Particles: Penguin diagrams.

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I have to say that some of those are true…

Sorry, but this post is kinda technical… There is a new measurement of Lambda-b lifetime in semileptonic decays provided by DO collaboration at Fermilab (their preprint is here). This measurement gives a new number for this lifetime, t = 1.28 ± 0.12 (stat) ± 0.09 (sys) picoseconds. This is a very short time on a scale of things (it takes about the same time for light to move the distance of about a thikness of human hair). But it is also short on the scale of other lifetimes of b-flavored hadrons. In fact, according to this measurement, the ratio of Lambda_b lifetime and a neutral B-meson lifetime is 0.86 ± 0.11, if my math is right (why don’t they just provide this number in the paper!). It is consistent with D0’s previous measurement of that ratio in fully-reconstructed decays is 0.870 ± 0.102 (stat) ± 0.041 (sys).

Now, why did I want to write about that? Well, for starters, it agrees well with our predictions for this ratio,  0.86 ± 0.05. But it does not fare well with the recent CDF number, 1.037 ± 0.058 (results are here), obtained in a fully-reconstructed analysis. Over summer, some of my experimental colleagues even suggested to me to try to understand the reason why this ratio must be one. Well, I kinda like my number…

Maybe someone from CDF could explain to me if this is a statistical fluctuation on their side or there is something more to it… 

Today was an interesting day. Dava Sobel, an award-winning science writer, author of Longitude and Galileo’s Daughter, and former science reporter for the New York Times, visited our Department here at Wayne State. She apparently is on the promotion tour (WSU was her first stop!) for the paperback version of her latest book, The Planets.

So she visited our Department, listened to our short 40-min presentation of research directions (the idea was to talk about something related to astronomy/astrophysics, so five of us took turns talking about astrophysics, nuclear theory, particle theory — that was my stint, particle experiment, and … nanoscience). I guess it must have been overwhelming at times, but she said she had fun (look at the picture below taken in the room with a cool whiteboard). Moreover, the only equation in the whole presentation (which I tried to sneak into my Powerpoint slides) did not survive Windows > Mac conversion…

Then she proceeded to our Planetarium to give a short talk about her book, The Planets. I guess, our planetarium was the reason why she decided to start her book tour at WSU and not, say, Harvard - we have a “real thing,” not the digital impersonation that many Universities have. Well, really I don’t know why.

Her talk was quite entertaining. At one point she told us a story of her friend, whose boyfriend (who apparently worked for NASA) gave a bit of Moon dust, actual Moon dust brought from the Moon by one of the Apollo expeditions. “What would you do with that?” she asked the audience. I don’t know why, but I said “Eat it!” Maybe I just wanted to know how the Moon tastes - after all, “everybody knows the moon’s made of cheese”… To my surprise, that’s exactly what that lady did!!! Go figure…

It was intersting to know that she started her science-writing career in Ithaca, working with the great Carl Sagan at Cornell. It is interesting that he left a huge “imprint” on Ithaca with everyone knowing who he was. I was a postdoc at Cornell in 2000-2001, after his death, but people would still say “oh, physics department. yeah, I know Carl Sagan.” As it turned out, my landlady’s mother (or aunt) was his secretary. Hmm… It must have been great working with him…

What would you do with the Moon dust?

Update: our local University paper had an article about her visit. Check it out here.