March 24, 2005

March 24

Bj in Helsinki

Every now and then we get outstanding visitors coming to Helsinki in winter time. Today we had James Bjorken, giving a talk on The Classification of the Universes that was of great interest to many of us.
I took some pictures in bj's seminar.

March 18, 2005

March 18

The most interesting paper in some time is in my opinion (ok, this is very subjective as you see below) Quantized tension: Stringy amplitudes with Regge poles and parton behavior, by Oleg Andreev and Warren Siegel.

For now being out of town, I only comment the first and last paragraph. The first paragraph refers to the nostalgic time of the late sixties and early seventies, when I did some modest phenomenology in all the four regions of phase space. The last paragraph contains an idea "...that gravity would disappear at short distances ..." that came to my mind in August 2004 (hep-ph/0210446 v5 16 Aug 2004, still under low priority debug and upgrade) - and perhaps in raw form two years earlier. Whether the idea is correct ... who knows.

The real content of Quantized tension is, of course, in the paragraphs between and requires some more reading, and it is most likely subject to (rapid?) further development.

March 10, 2005

March 10

At Aspen in February, Mirjam Cvetic gave a talk on particle physics
based on Intersecting D-branes. She claims progress being made. But they can't get "the devil from details": Higgs, chiral exotics.
More discussion on Higgs is given by Jesse Thaler and Itay Yavin.

March 09, 2005

March 9


E. Witten has brought some long ago developed mathematics (by Roger Penrose) on the arena of the string theory, the twistors. This has stimulated many authors for further work. There has been Twistor Strings Workshop in Oxford in January 2005. Among the speakers were both Penrose and Witten. My view is that Sir Roger does not mind computing graviton and gluon scattering using twistors, but he is worried of problems on even more fundamental level. He has a new book The Road to Reality, which has been criticized by Frank Wilczek and, more favorably, by Peter Woit.


V. Braun, Y-H He, B. Ovrut and T. Pantev make a step toward string phenomenology in A Heterotic Standard Model.

Year 2004

Andrei Linde and coauthors have found the landscape's beauty attratctive. They state that "... some of the surprising properties of our world might arise not through pure chance or miraculous cancellations, but through a natural selection mechanism during dynamical evolution."

P. Brax, C. van de Bruck and A.-C. Davis have written a very readable (" ... get a feeling of the physics ... " ) review (cover page only on this site) of Brane World Cosmology (total 57 pages, 6 figures), and start your own "brane wars".

A. Ashtekar and J. Lewandowski have prepared a pedagogical status report titled Background Independent Quantum Gravity: A Status Report (125 pages, 5 figures).

Elias Kiritsis has written an interesting rewiew D-branes in Standard Model building, Gravity and Cosmology (132 pages, 7 figures).

A quick look at some late summer papers:

C. Burgess, Inflatable String Theory? This review consists of 15 well written pages.

T. Banks, W. Fischler, L. Manelli, Microscopic Quantum Mechanics of the p=rho Universe. This paper has to be read carefully, or be set aside for future measures.

More of strings, branes and tachyons:

A. Sen, Tachyon Dynamics in Open String Theory.

D. Klemm, Black Holes and Singularities in String Theory .

C. Kokorelis, Standard Model Building from Intersecting D-Branes .

H. Nilles, Five Golden Rules for Superstring Phenomenology .

After the above papers on theory and model building it's interesting to read M. Dine who writes that a large group of people have found "... at the very least, .. a very large elephant in the closet".

T. Banks is skeptical about the Landscape.

R. Bousso discusses the deeper questions of string Cosmology and the S-matrix.

Year 2003

See my web site.