The visitor number 10 million came to this blog around 11 am, Central European Time, today, from the whitehouse.gov domain. Congratulations (it was 5 am locally over there!). It's a coincidence because most of the recognizable visitors' domains seem to be academic and during the European morning, U.S. visits in general score less than 10% (over 50% when all times are included, however).I will just mention five new papers on the arXiv – two hep-ph papers and three hep-th papers.
Chul Kim, Ahmad Idilbi, Thomas Mehen, and Yeo Woong Yoon discuss another interesting possible route for the supersymmetric particles to have escaped the detection at the LHC:
Another hep-ph paper was written by Zhenyu Han, Graham D. Kribs, Adam Martin, and Arjun Menon:
Now, three hep-th papers. Stephan Stieberger and Tomasz R. Taylor released an interesting preprint on mathematics of perturbative string theory:
KLT relations. The closed string's Hilbert space is approximately the tensor product of two copies of the open string's Hilbert space: one collection of degrees of freedom comes from the left-movers, another one arises from the right-movers. This "closed equals open squared" paradigm may also be used to relate the closed string amplitudes and "sort of squared" open string amplitudes. The KLT relations are particular formulae that make this concept work.
Heterotic strings hybridize a general left-moving sector with a different right-moving sector. Heterotic strings in 10 dimensions have a similar spectrum as type I string theory that includes open and closed strings. In some sense, the heterotic strings behave much like the open strings. The authors of this new paper find an interesting trick how to obtain heterotic amplitudes from the open string amplitudes by replacing all "zeta functions" in the open string tree-level amplitudes by their "single-valued" versions. After all these building blocks are "modernized" in this way, they may get the tree-level amplitude for an arbitrary number of heterotic string states.
In the second hep-th paper I picked,
Finally, there is a paper on the black hole interior,
These are sort of interesting claims and conceptually new quantities and experts may want to publicize their answers to the same questions that were discussed (and perhaps answered) in this paper.
Off-topic: flights from Bremen, Germany were cancelled due to the UFO above on Monday. No one knows what the object was – it was like an airplane but louder – which is why it was an UFO. But if the UFO means an extraterrestrial alien for you, be my guest! ;-) "In Bremen" may very well be the answer to Fermi's famous question LOL.