a 5th force ?

"Recently a 6.8σ anomaly has been reported in the opening angle and invariant mass distributions of e+e− pairs produced in 8Be nuclear transitions. The data are explained by a 17 MeV vector gauge boson X that is produced in the decay of an excited state to the ground state, 8Be∗→8BeX, and then decays through X→e+e−. The X boson mediates a fifth force with a characteristic range of 12fm and has milli-charged couplings to up and down quarks and electrons, and a proton coupling that is suppressed relative to neutrons. The protophobic X boson may also alleviate the current 3.6σ discrepancy between the predicted and measured values of the muon's anomalous magnetic moment."
arXiv

This would be quite a surprising step beyond the standard model, but why did nobody else notice this 17 Mev boson before?


added later: There are now some doubts about the experiment.

added much later: A pretty good explanation of the experiment, relevant theories and also some other anomalies which may or may not be related.

How (not) to translate Tolstoy

"I read you had trouble with the editing of the British Penguin edition of Anna Karenina."
"They hated what we did."
"It was quite something. For example, Kitty meets Levin at the skating rink. She asks him, "Did you come recently?" And the copy editor wrote a comment which said, I'm not sure if you're aware of it, but this word has now acquired different meanings. And there is a better example! Kitty is discussing the upcoming ball. Seventeen-year-old, completely innocent Kitty says, "I do like balls." Again the copy editor wrote, I'm not sure if you're aware . . . Then the editor had this other problem. I had written that Anna "got into the carriage." And the editor said, This is the American usage of the word got. We can't do this in a British edition. You should say Anna went into the carriage. I wrote back, I'm not sure if you're aware of it, but this word has now acquired different meanings..."

I think unfogged is still one of the best blogs out there ...

Sean and The Big Picture

Sean Carroll has just published his book about The Big Picture, which seems to be the kind of book accomplished physicists used to write after they got older.
I have not read it and I have no plans to do so. But he has given us a good idea about its content on his blog, so I can tell you what I find a bit weird about it.

We know that Sean is a believer of the many worlds interpretation (*) and it would make sense to discuss what it suggests for "the meaning of life, the universe and everything" if all possible worlds are equally real in some sense. Others have already discussed this in some parts, but it would have been interesting to get "the big picture" from one of the true believers.

But Sean told us that "The discussion of the basics of quantum mechanics itself is quite brief, and I mention the Many-Worlds formulation only to emphasize that there’s nothing about QM that implies we need to be idealist, anti-realist, or non-determinist".
Later he tells us e.g. this "poetic naturalist" story: "The universe is not a miracle. It simply is, unguided and unsustained, manifesting the patterns of nature with scrupulous regularity. Over billions of years it has evolved naturally, from a state of low entropy toward increasing complexity, and it will eventually wind down to a featureless equilibrium condition."
This is obviously along the conventional one-world interpretation most people are familiar with (*).

Either Sean is not really serious about many worlds, or he did not think it through yet, or he left it all for his next book.

(*) As far as I know, his derivation of "the arrow of time" also involves a cosmological multiverse, which is independent of the many worlds interpretation, but surprisingly also mostly missing from his book as far as I can tell. If you find this disappointing, Don Page discussed a much bigger picture in this preprint.

dominoes and chess

I am posting this puzzle for two reasons: It is one of my favorites and I would like to check if Lee, who likes such a challenge, is still reading this blog ...
But of course everybody is invited to post an answer.

We consider a chessboard (8x8 squares) and 32 dominoes. The dominoes are of such size that they cover exactly two squares on the chess board.
But now assume that we cut off two squares at diagonally opposite corners of the chess board and take away one of the dominoes.
Is it possible to put the remaining 31 dominoes on the board so that all of the remaining 62 squares are covered and if yes how?