Tag Archives: ExtraDimensions

SEARCH Workshop Panel Discussion on LHC Posted Online

The final panel discussion at the Maryland SEARCH workshop — six theoretical particle physicists talking about the 2011 experimental results from the Large Hadron Collider [LHC] and looking ahead to the 2012 data — has finally been posted online, along with the rest of the presentations at the workshop. I wrote about the workshop, which took place in mid-March, here and here.  In the latter post, I wrote:

The workshop concluded with a panel discussion — the only point during the entire workshop when theorists were formally asked to say something. The panel consisted of Michael Peskin (senior statesman [and my Ph.D. advisor] famous for many reasons, including fundamental work on the implications of highly precise measurements ), Nima Arkani-Hamed (junior statesman, and famous for helping develop several revolutionary new ways of approaching the hierarchy problem),  Riccardo Rattazzi (also famous for conceptual advances in dealing with the hierarchy problem), Gavin Salam (famous for his work advancing the applications of the theory of quarks and gluons, including revolutionary methods for dealing with jets), and myself (famous for talking too much… though come to think of it, that was true of the whole panel, except Gavin.) And Raman Sundrum, one of the organizers (and famous for his collaboration with Lisa Randall in introducing “warped” extra dimensions, and also anomaly-mediated supersymmetry breaking [which was competitive with a paper by Rattazzi and his colleagues]) informally participated too. Continue reading

LHC as Juggernaut and Behemoth

Yesterday I spent the afternoon at the Third Indian-Israeli International Meeting on String Theory,  held at the Israel Institute for Advanced Studies.  The subject of the meeting is “Holography and its Applications”.  No, this isn’t holography as in that optical trick that allows you to create a three-dimensional image on the security strip of your credit card — this is “holography” as string theorists like to discuss it, that trick of describing gravitational or string-theoretic physics  in a certain number of spatial dimensions as quantum field theory (without gravity) in a smaller number of spatial dimensions.  It’s impressive, even stunning, that sometimes you can use a precise form of the holographic principle to solve some difficult string theory problems by rewriting them as easier quantum field theory problems, and solve some difficult quantum field theory problems by rewriting them as easier string theory problems.

I worked in this research area on and off for quite a while (mainly 1999-2007) so I know most of the participants in this subfield.  In fact my most commonly cited paper happens to be on this subject.  But ironically my role at this conference was to present, as the opening talk, a review of 2011 at the Large Hadron Collider (LHC). Continue reading

Why Extra Dimensions Lead to Kaluza-Klein Particles — Part 2 (of 2)

The end of the story: if you’ve read through all the articles linked from Monday’s post — which explain why extra dimensions manifest themselves through heavier versions of known particles, called Kaluza-Klein (KK) partners — you can now read the punch-line in today’s article: why, instead of there being a KK partner for every possible mass, as Monday’s article would have naively suggested, there are KK partners only for very specific masses.  Also, you can learn why the pattern of KK partners’ masses, if any were discovered, would reveal the shape, size and number of the extra dimensions.

The next step in the extra dimensions series will be to tell you what we already know from experiments about extra dimensions, and how people are looking for them.  I’ll get to that eventually, maybe next month.

Meanwhile I’m still absorbed in some very pressing work concerning this year’s run of the Large Hadron Collider [LHC], so posts are going to be rare for a bit longer.  But over the coming week or two I do have some more things to tell you about the search for the Higgs particle, and about searches for other speculative phenomena going on at the LHC.

Why Extra Dimensions Lead to Kaluza-Klein Partner Particles – Part 1

Ok, the answer you’ve all been waiting for — the first half of it, anyway.   Even though it is not the full story yet, you’ll find it is both self-contained and instructive.

Those of you who have been following my recent series of articles on extra dimensions of space —  which include some articles on how to think about them (including some examples) and newer articles on how extra dimensions might reveal themselves to us — already know that for any type of particle that can travel in one or more extra dimensions that are unknown to us, nature will exhibit heavier versions of this particle, called Kaluza-Klein (KK) partner particles.  But I haven’t yet told you why this is the case.

Today, Step 1: why the KK partner particles exist at all, and why they are heavier than the original one.  But today’s argument is a bit too simple, and only partially correct: it gets the masses of the KK partners wrong.  In Step 2 I’ll fix this problem by adding a little bit of quantum mechanics.

The Smoking Gun for Extra Dimensions

We’re in the midst of a turning point in scientific history, with many different types of discoveries reported of planets around other stars. It certainly is starting to appear that planets around stars are the rule, not the exception.  This is an enormously important development in our understanding of our universe… so a hearty congratulations to the planet hunters!

I hope there are some good articles out there outlining the diverse array of methods being used in these discoveries; there’s a lot of good physics and astrophysics being exploited.  Since this isn’t my area of expertise I’m inclined for the moment to leave this to others… especially since I have some very urgent research going on, which is why posts have been sparse since the New Year.  (I’ll describe that research later; it’s nothing earth-shaking or exciting, but I feel it is very important for LHC operations in 2012.)  If any readers have found an article of this type, please leave a comment.

Meanwhile I’m continuing to develop the Extra Dimensions series of articles, and I’ve now followed up my examples of extra dimensions with a next installment, a first discussion of what scientists would look for in trying to identify that our world actually has one or more extra dimensions .  The new article describes one of the key clues that would indicate their presence.  But this is far from the end of the story: I owe you more articles, explaining why extra dimensions would generate this clue, outlining how we try to search for this clue experimentally, and mentioning other possible clues that might arise.  All in due course…

Another Type of Extra Dimension

I’ve updated the article on extra dimensions that I announced last week.  In the original version of the article, I gave you one example of an extra dimension; now I’ve extended it to include another example, of a very different type.   You can find all the new stuff by scanning down the article until you find a line in red that says “New additions begin here.”  If you haven’t read about extra dimensions at all, you should read some of the other introductory articles first; you can find links to them at the top of today’s article.

What will come next, perhaps in the coming week, is a discussion of the scientific techniques used to look for signs of extra dimensions.  Later I’ll add another example or two to today’s article.

A Bit More About “Extra Dimensions”

A while ago I was writing a sequence of articles — interrupted for some weeks by all the hullabaloo over Higgs particles and all the noise about neutrinos — concerning the possibility that the world has more than the three spatial dimensions that are obvious to us.  These “extra” dimensions seem to be very confusing to non-experts, so I’ve been trying to find a way to make them seem a little less strange.  We’ll see if I’ve succeeded.  Building on my articles describing some types of worlds of 1 spatial dimension and of 2 spatial dimensions, I’ve now written an article giving one type of example of an “extra” dimension.   Other articles to follow over coming weeks will provide other examples of extra dimensions, as well as an attempt to explain how scientists can potentially look for evidence of an extra dimension.