All posts by donoghue

Getting up to date

Wow, this has gotten way out of date!

Some developments, in no particular order.

On Aug 2, Barry, Gene and I submitted the revised edition of “Dynamics of the Standard Model” to Cambridge. This is the updated version of our book. It is a relief to get this finished.

I went to the workshop on Jets and Field Theory in Vienna http://www.univie.ac.at/esijet/index.html . My interest was in Regge within SCET. Interesting conference.

I also had a European tour (Louvain, Mainz and Trieste) in March to discuss the seemingly conflicting views of gravity from effective field theory and from Asymptotic Safety – and also talked on this at Perimeter in May. There is potential for some new insights to come out of this. Mohamed and I are working on it.

Ufuk has taken a new postdoc in Upsalla and will start there in September.

We are looking forward to the arrival of many new folks this September. Michael Ramsey-Musolf will be arriving, as well as postdocs Grigory Ovaneysan, Peter Winslow and Wei Chao.

Congratulations again to Ufuk

Ufuk Aydemir successfully defended his thesis today – I was his research advisor. His thesis contained three topics on physics beyond the standard model. He wrote about the tests of general covariance that was done with me and Mohamed Anber, on work with Lorenzo Sorbo on dynamical four-form fields, and also recent work on self-healing and new physics in effective field theories. His publications are here, and there are still more in the works. Congratulations Ufuk – the new Dr. Aydemir!

Field Theory and Gravitation

I recently returned from giving some lectures at the 6th School on Field Theory and Gravitation in Petropolis, Brazil. The link is here. It had some good people at it and of course had an interesting topic. I also got to visit my former student Gustavo Burdman, who is doing very well at the University of Sao Paulo. It was good to see him after many years.

Congratulations, Ufuk

My student Ufuk Aydemir has just been offered (and will accept) a nice postdoctoral position at Virginia Tech. This is great news, and the group at VT should be a good match for Ufuk’s skills. We are looking forward to great things.

Unitarity violation

Ufuk Aydemir, Mohamed Anber and I have just put out a paper that shows that the traditional signal for new physics – the violation of unitarity at tree level – is actually unconnected to the onset of the new degrees of freedom. Moreover, in the chiral theory it is even very far from being an upper bound, because tree-unitarity violation happens almost an order of magnitude before the QCD degrees of freedom are manifest. We also have a very interesting gravitational example.

Running gravitational coupling

This post is a bit late. Mohamed Anber and I have written a paper that provides counter-examples to the idea that there is a running gravitational coupling. Here is the link. We feel that this is a crucial rebuttal to the idea of a running gravitational coupling in the perturbative region. If this problem extends past the Planck scale, then it would seem that there would be problems for the idea of Asymptotic Safety.

Neutrinos faster than light?

Mohamed and I were ahead of our time. Our paper back in the spring, The emergence of a universal limiting velocity,, about particles having different limiting velocities is now pretty relevant given the new OPERA result. However, not too many folks were paying attention to such a topic back then, so it was not noticed. We describe something that is overlooked in most of the discussion – the limiting velocities are scale-dependent quantities that “run” with the energy.

In our paper we stated that the largest deviation would come with the particles that are the weakest coupled- and pointed to gravitons as the weakest. We missed an opportunity to note that neutrinos are the second weakest! In light of the OPERA results, Mohamed and I have written a new paper where we directly address the neutrino situation – Limiting velocities as running and superluminal neutrinos. Hopefully people are paying more attention now. However, this running does not solve all problems with the OPERA result. It could be part of the solution should the OPERA result hold up.

Seminar in auditorium A

I am visiting the Niels Bohr Institute this month and had the pleasure of giving a seminar in the historic Auditorium A. You can find many pictures of Bohr and famous physicists in this room – an example is above. The room has been kept in almost the same condition as back in Bohr’s day, with the same benches, lights etc. Most of the time, European science departments have moved out of the historic buildings to modern ones, so we have lost the sense of place for our history. NBI is different – the original buildings are still in use, as is Bohr’s office, the room where Heisenberg first came up with the uncertainty principle, and the seminar rooms. I enjoy this connection. Moreover, the folks here successfully keep up Bohr’s spirit of informality and relaxed discussion.

Last Thursday, Andy Jackson gave an interesting talk on the travels of an earlier famous Danish physicist, Hans Christian Ørsted, who discovered that electricity and magnetism were part of the same force. Andy and his wife have spent many years editing Ørsted’s letters and have many great stories to tell. The previous week I also had a chance to visit the island associated with yet an earlier Danish scientist – Tycho Brahe. Tycho was given an island (Hven) in the Øresund for his observatory. He hired many craftmen and assistants – it was the first big science laboratory. You can still see his instruments (above) although the associated castle is gone. That is me below helping Tycho scan the sky. Overall – interesting science tourism!