Tuesday, July 28, 2009

Easy latex on blogpsot

I had said that I wanted an easy way to use latex on blogspot. Untill now I was using an external mimetex server and using the html img tag with the url of the mimetex cg and latex code in it. The idea was to create some kind of customized tag that would write the html code. That has too good points. On one hand it makes the edition of the post easier. On the other if the mimetex cg is changed you only need the link of the cgi in the script code that is asociated to the tag.

In order to do so I have tried to study the blogspot templates structure, but I have not found too usefull information. Most that I hve found is concerning the look of the blog and I am not too interested in that kind of things. I have tried to see if I could create tags, but I have not found too much info. I have made an easy javascript function, but it was not of too much help.

Fortunately I have found someone who made the work for me. You can read how to here. As you can read there once you add a personalized javascript gadget to your blog you can insert your latex code inside two dollar symbols and it its replaced by the right latex image when you publish the entry.

The code behind the scenes is this. I have not had time to study it. If you follow the stepts indicated in the webpage I linked before that javascript is called from a remote .js file and you can't customize it. Obvioulsly one could write the whole javascript code in the customized gadget or create your own copy of the js file whereever you want and customize it.

One bad aspect of the latex, as I use it in this blog, is that the images have some annoying borders, as you can see:


I think that this problem can be advoided doing some CSS to create some tag for latex images but that is something that I'll do sometime later. Also I would like to study that javascript to use the wordpress tag for wrting latex, $latex the code goes here $ instead of the tow dolar symbols, in order to improve the crosscompatibility betwen blogspot and wordpress. But, anyway, that are minor questions, the hard problem is solved. Now it only remains that I would post about physics and write the equations, of course ;-).

Monday, July 13, 2009

Strings 2009: the slides

This year the annual conference in string theory, celebrated at Roma, has not had an internet live TV broadcast as it happened the last year.

Because of that reason I didn't do a post about the topic. I have waited until the slides where out and I could have read some of them. The slides of conferences, if they are detailed enough, are a good thing because they are addressed to non specialists in that particular field, so they can be easily read, and they condense a great amount of information from various papers.

You can get access to the lists of talks, wth the corresponding slides, here.

I have read a few ones already. The first was the one given by Howava. I was greatly interested in reading how he defended his theory against the recent papers with showed the problems of renormalizability it seems to actually has, despite of being power counting renormalizable. Well, I didn't see any mention of it. The slide talks about the "foundational" papers on the subject and explains it's relation to the M2 brane of M-theory, to the CDT (causal dynamics triangulations) result that in the short length the effective dimension of space time is near 2, and that his theory resembles that, and a few other topics. I find specially curious that one of the motivations for his theory is that string theory violates Lorentz symmetry. Well, I am not sure why he says that, but certainly said without further explanation looks weird. It is a pity that there was not live streaming, nor non-live videos, of the talks so one can't see what questions people made him.

About the F-theory GUT's there were three talks. One from Vafa. It's ppt (than not pdf) is very schematic and without some previous knowledge on the subject I am not sure how much information one can get from it. Anyway, if one reads the papers I cited in my post about F-theory for non experts maybe he could get a much better understanding. Vafa makes a decent work explaining the two foundational papers, the paper in cosmology, and the paper in LHC footprints, that I have read. It also talks about some papers I haven't read, as for example the ones in gauge mediation (although I had read some resumes of the results). The conclusions seem to be that there are two clear predictions from their models. One, in cosmology, is that the dark matter candidate is the gravitino. that rules out models on WIMPS and implies that ATIC, PAMELA and similar results that seems to indicate an anomalous ratio of positrons over electrons over certain ranks of energies would have astrophysical origins. Or not exit at all. Recent results from FERMI/GLAST seem to contradcit ATIC and PAMELA (see, for example this post by Jester, in resonances blog) would agree with this prediction.

The other prediction mentioned on the slide is that there will be some charged track on the LHC leaving the detector. It would be due to the NLSP whose lifetime, 10^1-4 secs, is long enough to allow it scape from the detector.

There are two more talks about F-theory. One by Sakura Schafer-Namek. I have read it but from all the part related to spectral covers I coudn't get any useful informrmation. I simply don't know enough form that mathemathical topic. The other paper in F-theory is the one by Jonathan Heckman. It is centred in flavor hierarchies for quarks and leptons. Well, an interesting topic for sure, but not my favourite one. Anyway the slide is good enough to get some general idea of the topic from it.

Another paper I read is the one of Strominger about the KERR/CFT correspondence. About that topic I only had read a paper dated from the last summer. Well, I am not sure if too much progress has been achieved so far neither I have clear whether the whole field is terribly significant, but possibly that is my fault.

Possibly the most awaited paper was the one from Nima-Arkani-Hamed about twistors and the S-Matrix. There are rumorology out there saying that it's not a paper in string theory but an attempt to create some kind of supersymmetric GUT diferent from string theory. I haven't still read the slide and I can't say anything about. But for sure it is a theory that many people will discuses sooner or later, possibly when the actual paper on the subject would be out.

I'll possibly read more slides later, but I am not sure if I will post about them. But everybody can try to rad the linked slides by themselves. There are good choices that anyone with a decent basic on high energy physics could get some amount of info from them.

UPDATE: In a thread in physicis forums someone, seemengly well informed, said that actually Horava recognized the problems recently found in his theory in his talk as strings 2009. Also the same physic forums poster explained that the actual problems where that one couldn't decouplee the gosths from the theory. Curiosulsly that has lead to a posible reinterpretation of that gosths as dark matter. I have not read the relevant papers but at first sight that looks very bizaree. Gosths are negative norm states tht usually appear in the quantizationo of gauge theories as intermediate states that can be shown not to appear in external legs, i.e., are no observabbles. Toclaims thatusually unwanted negative normed states can go in external lines and actually represent viable particles (in the form of dark matter) seems like one could try to do the same thing for any theory and one wouldn't need gauge theories. I suppose that there will be something special in that gosths that make them diferent from the usual ones and permits people doing such conjectures, but, as I said, looks an a priory contravied claim.

P.S. I am looking for an easier way to use LaTeX in this blog that the one I am using (writing the latex code in the url of an image generated by an external LaTeX server). If I don't find a good solution I would seriously consider the option to migrate this blog to wordpress where writing LaTeX is "natively" supported (that's the reason I make an extensive use of it in my other blog).

Thursday, July 09, 2009

Vixra, the arxiv mirror symmetric

In Kea Monad/Marni Dee Sheppeard blog there has been recently a few entries about the freedom to publish scientific results.

As a result Tomasso Dorigo suggested her a bizarre idea. s a result of comments exchange it resulted into another idea, the birth of a new archive for scientific publication. In a really fast movement a new domain was registered and the site is already available. The name for the new site is arxiv written in the opposite direction, that is vixra, which, with some minor licences can be considered as a mirror symmetric of arxiv. The actual link for the website is: vixra.org/. Note that at the date of writing this It is in a very beta status.

I leave here the manifest that justifies it's creation and it's purpose, as declared by the creator:

Why viXra?
In 1991 the electronic e-print archive, now known as arXiv.org, was founded at Los Alamos National Laboritories. In the early days of the World Wide Web it was open to submissions from all scientific researchers, but gradually a policy of moderation was employed to block articles that the administrators considered unsuitable. In 2004 this was replaced by a system of endorsements to reduce the workload and place responsibility of moderation on the endorsers. The stated intention was to permit anybody from the scientific community to continue contributing. However many of us who had successfully submitted e-prints before then found that we were no longer able to. Even those with doctorates in physics and long histories of publication in scientific journals can no longer contribute to the arXiv unless they can find an endorser in a suitable research institution.

The policies of Cornell University who now control the arXiv are so strict that even when someone succeeds in finding an endorser their e-print may still be rejected or moved to the "physics" category of the arXiv where it is likely to get less attention. Those who endorse articles that Cornell find unsuitable are under threat of losing their right to endorse or even their own ability to submit e-prints. Given the harm this might cause to their careers it is no surprise that endorsers are very conservative when considering articles from people they do not know. These policies are defended on the arXiv's endorsement help page

A few of the cases where people have been blocked from submitting to the arXiv have been detailed on the Archive Freedom website, but as time has gone by it has become clear that Cornell have no plans to bow to pressure and change their policies. Some of us now feel that the time has come to start an alternative archive which will be open to the whole scientific community. That is why viXra has been created. viXra will be open to anybody for both reading and submitting articles. We will not prevent anybody from submitting and will only reject articles in extreme cases of abuse, e.g. where the work may be vulgar, libellous, plagiarius or dangerously misleading.

It is inevitable that viXra will therefore contain e-prints that many scientists will consider clearly wrong and unscientific. However, it will also be a repository for new ideas that the scientific establishment is not currently willing to consider. Other perfectly conventional e-prints will be found here simply because the authors were not able to find a suitable endorser for the arXiv or because they prefer a more open system. It is our belief that anybody who considers themselves to have done scientific work should have the right to place it in an archive in order to communicate the idea to a wide public. They should also be allowed to stake their claim of priority in case the idea is recognised as important in the future.

Many scientists argue that if arXiv.org had such an open policy then it would be filled with unscientific papers that waste peoples time. There are problems with that argument. Firstly there are already a high number of submissions that do get into the archive which many people consider to be rubbish, but they don't agree on which ones they are. If you removed them all, the arXiv would be left with only safe papers of very limited interest. Instead of complaining about the papers they don't like, researchers need to find other ways of selecting the papers of interest to them. arXiv.org could help by providing technology to help people filter the article lists they browse.

It is also often said that the arXiv.org exclusion policies dont matter because if an amateur scientist were to make a great discovery, it would certainly be noticed and recognised. There are two reasons why this argument is wrong and unhelpful. Firstly, many amateur scientists are just trying to do ordinary science. They do not have to make the next great paradigm shift in science before their work can be useful. Secondly, the best new ideas do not follow from conventional research and it may take several years before their importance can be appreciated. If such a discovery cannot be put in a permanent archive it will be overlooked to the detriment of both the author and the scientific community.

Another argument is that anybody can submit their work to a journal where it will get an impartial review. The truth is that most journals are now more concerned with the commericial value their impact factor than with the advance of science. Papers submitted by anyone without a good affiliation to a reasearch institution find it very difficult to publish. Their work is often returned with an unhelpful note saying that it will not be passed on for review because it does not meet the criteria of the journal.

In part viXra.org is a parody of arXiv.org to highlight Cornell University's unacceptable censorship policy. It is also an experiment to see what kind of scientific work is being excluded by the arXiv. But most of all it is a serious and permanent e-print archive for scientific work. Unlike arXiv.org tt is truly open to scientists from all walks of life. You can support this project by submitting your articles now.

What do I think of this. Well, there is a famous phrase of Richard Feynman about physics (valid for science in general), and it's role as a practical discipline:

"Physics is like sex. It can have practical consequences sometimes but that is not the reason we do it".

Well, that's the idea. And publishing would be part of the fun. But seemengly to publish (as well as otherparts of a scientifi carrer) have become a game where many factors ouor of the pure siceintifc content play a role as least as important as the quality of papers. Still worst, it is not very clear what the rules of that game are. That converts publishing in a very risky busines and an error can bban one from arxiv (the papers that people actually read, peer to peer reviews have become invisible). In fact I personally think that I could find some endorser for froseable future papers. But in the actual state of the subject it is too much presure bor bboth, me and the endorser.

For that reason an alternative as arxiv is a goo option. One can publish ideas and exchange them with other people. It is important the concept of exchange. There are some kind of papers when one can have, or almost have,the secutiry that they are right. But there are other that are subjecto to many uncertainties. And, possibly, one can save only a limited amount of the difficuties he face. Possibly if one has round him people working on that field he could discusse that ideas privately. but it is not always possible (even if you are in a academic position). In that sense to publish ideas in a preliminar state of development that you are not sure you can pursue further, that maybe they could be usefull. That's the idea of scientific exchange as fr as I see. And if one is wrong, well, that's always a possibilitie. Of course one would do the usual homework to try to search as much as possible similar ideas beofre publishing rubish results. Definitively is good to publish that kind of papers in a site where if somone is wrong doesn't he (and his family, friends and cat) become banned for the rest of his life I wuold say .

Still better, as far as I see both archives wouldn't be mutually exclusives. One could publish "serious" papers in arxiv and more risked ones in vixra. Well, at least in theory. Surely someone will find good reasons to find incompatibilities among them ;-).

Wednesday, July 08, 2009

F-theory GUT for non experts

I have found a few papers that do a good job explaining the basics of F-theory in a relatively easy way. I could have posted them as un update of the previous post on the subject but I think it deserves an small separated post.

One paper is : F-theory, GUTs and Chiral Matter.

Another one, written by Hackman and Vafa is: From F-theory GUTs to the LHC

Also I think that the interested reader would try to understand more basic settings, previous to the F-theory revolution. I am talking about the intersecting branes scenarios. A short and good review is: Progress in D-brane model building.

The reason to investigate the last paper is that I find it is interesting to understand how one calculate family numbers, how chiral fermions arise and so that in more conventional D-brane models. In fact the firs paper I cite makes a good job explaining some of that aspects, but still.

Also I recommend, once again, the original paper of Ibañez, Quevedo et all in local models D-Branes at Singularities : A Bottom-Up Approach to the String Embedding of the Standard Model. I have finished to read it and I find it very clear. As a plus it also has a brief chapter about F-theory.

Certainly the last papers about D-brane model building are not required to understand the F-theory ones, but It is good to understand what existed previously to better understand the goodness of the new. In that sense the papers recommended in my entry about the prehistory of F-theory GUTS are also valuables and focuses in diferent aspects than the ones cited here.

Anyway, if someone only wants a quick, but accurate, idea of the subject the two papers cited at the start of the post make a wonderful work