# Complexity, The Standard Model and Higgs

1. Dec 11, 2009

### inflector

I've been reading most of the threads here in particle physics forum. Recently, I noted a couple of threads started by enotstrebor which were a bit impolitic. Nevertheless, they raised some issues which are similar to those I have myself with the Standard Model as well Quantum Mechanics in general.

I am new to physics. I have no formal training in physics. Nevertheless, I am attempting to teach myself so that I can eventually have competent conversations with actual physicists. I have been studying a few hours a day for about a year and a half. I am learning the math, I am learning the basics. I don't know how long it will take to reach the level I seek but I am progressing and I understand more and more each week. I have always had an extreme aptitude for science and math so I'm not worried about having enough smarts to learn the concepts, I just have a lot of ground to cover.

Still, one thing has bothered me from the beginning, the progression of the complexity of the theory over time starting about the 1930s. In particular, as physicists dug deeper in the late 1800s and early 1900s, they found that matter as we sense it was composed of complex arrangements of simpler components; that most of what we sensed were molecules. Then they discovered atoms, which were simpler and fewer. Scientists then learned that atoms were, in turn, composed of simpler particles, the electron, the proton, and then they eventually discovered the neutron.

Now, try as they might, in the last 70 years or so since the particle accelerator was invented, scientists have been unable to separate out anything more fundamental. Sure, if they add lots of energy, then they get lots of cool particles, the particle soup, if you will, just like cosmic rays generate in our atmosphere, but none of the particles that comprise the proton or neutron (namely quarks) have been found in isolation.

The following is what seems to be the case from my limited neophyte perspective, we have a progression that goes from many complex to fewer less complex components with the complexity at the upper layers arising from emergent phenomena at the level of the interaction of the simpler components. In their most complex arrangement, we have: Animals -> Organs -> Cells -> Molecules -> Atoms -> Protons, Neutrons and Electrons. More -> Less. Complex -> Simple. A nice steady progression over decades.

Then starting in the 1930s with the advent of quantum mechanics and particle physics leading up to the Standard Model in the 1970s, we started to get the opposite, as I. I. Rabi stated after the discovery of the muon, "Who ordered this?" The theory started getting more and more complex. The number of particles started increasing and the complexity of the theories started increasing.

Which brings me back to the beginning and enostrebor's posts about the Higgs Mechanism.

My best understanding of the Higgs mechanism was it's description in Bruce Schumm's book Deep Down Things. His description is for the layman, I suspect it will be a full year or more before I'm really conversant with the math required to understand the non-layman's version of the theories, so that's what I'm stuck with of the moment. Schumm clearly believes in the Standard Model as he says it has "breathtaking beauty." Martin Perl, who won the 1995 Nobel for his discovery of the tauon, calls the book: "an ambitious and very successful non-mathematical description of the nature and significance of the world of elementary particles and forces" so I am assuming that he doesn't make any big errors in his descriptions.

When I read the description of the Higgs mechanism and the Higgs field in Deep Down Things, I said to myself, "You've got to be kidding me?" It seemed to me like a massive hack. Like there was a piece of data that didn't fit the theory so the Higgs Mechanism was bolted on in an attempt to repair it, that there was no other reason for it. That was my impression.

Now I don't know enough to have a real opinion on the matter, certainly, so I have to assume I'm missing some piece of knowledge that will cause me to think otherwise in the future. Nevertheless, when I see a discussion of the Higgs here and elsewhere, I try to follow it in the hope that the discussion will provide a clue as to what I'm missing.

But when I read the post from enotstrebor concerning Wikipedia's entry on the Higgs Mechanism, it seemed to me that he raised a valid point that I didn't see addressed here.

Namely, that we know that there is something wrong with either the Standard model or our theory of gravity. There are problems somewhere even by the admission of Paul Langacker (in his brief description of the standard model here: http://arxiv.org/pdf/0901.0241v1), he devotes 1/4 of his paper or 10 pages to discussions of what he calls: "Problems with the Standard Model." At least one source of the problems may very well be in the parts of the Standard Model that led to the requirement of the Higgs mechanism, it seems to me.

So a dogmatic statement in Wikipedia is misplaced. Instead of saying: "Although the evidence for the Higgs mechanism is overwhelming…" it seems to me that it should say: "There is considerable evidence for the Higgs mechanism, and it is widely accepted among particle physicists,…" or something like that. "Overwhelming" is a word that make a judgement, it implies a winner in a struggle. It is therefore dogmatic. I believe that dogmatic statements serve science poorly except when they relate to experimental observation. The history of science is filled with theoretical dogmatism that was subsequently overturned. A study of 19th century aether theories is one well-known example.

The choice of wording may seem trivial, but it is not. One choice admits the possibility of the theory being wrong, the other does not.

Do you have any suggestions for what to study that will help me to understand the Higgs Mechanism in another light? Am I missing something that makes "overwhelming" the best word here?

2. Dec 11, 2009

### humanino

Did it occur to you that, just maybe, the wording seems trivial to you ? It has already been indicated to enotstrebor that the "overwhelming evidence" is not in favor of the Higgs boson itself, but in favor of the Higgs mechanism. We know there are vector bosons out there, we know they effectively emerge from a gauge theory, and we know that if there was nothing to accomplish the Higgs mechanism we would obtain absurd mathematical predictions such as probabilities larger than 1. Even if the standard model is only an effective low energy theory (which is quite a common point of view), it remains that something must happen around the TeV scale to prevent probabilities to go larger than 1. We have seen those vector bosons, we know they interact between each other, so there is indeed overwhelming evidence for something to happen there. It does not need to be the single Higgs. There is not overwhelming evidence for a single Higgs. Even, whatever happens could not be visible at the LHC. But something, some mechanism has to take care of the Higgless standard model going crazy at this scale.

3. Dec 11, 2009

### Haelfix

There are models that give mass to the standard model particles that doesn't strictly speaking involve the Higgs mechanism. Otoh they are much more complicated, far more contrived and typically don't satisfy the criteria where you get out more than you put in. Hence, theoretically and aesthetically unlikely.

Most of the reason for believing in the Higgs mechanism in the first place, is the paucity of viable competitors.

4. Dec 11, 2009

### inflector

The wording doesn't seem trivial to me at all. That's why I brought it up.

Perhaps I'm dense here, but the problem I am having is that when you make statements like:

and

My naive perspectives is to think that there is another alternative. That perhaps the reason that the predictions for probabilities going greater than 1 is because the theory is in error in some respect.

This is exactly why the Higgs Mechanism seems like a hack to my uneducated naive mind. It seems to this neophyte that what is being said is:

A and B and C are not true unless D. Therefore D is true because we know A and B and C are true.

This makes logical sense if there is independent proof that A and B and C are true in and of themselves. Do we really know this about all the elements of the Standard Model outside of the Higgs Mechanism? If so then the logic makes sense. I was under a different impression.

Are we so sure there is not a C' that's really close to C but fixes things so that no Higgs Mechanism is required? i.e. are we sure that there are no potential errors in any of the other aspects of the Standard Model? Even minor ones?

5. Dec 11, 2009

### twofish-quant

It's more along the lines that D is the most elegant explanation that we can come up with right now to explain A, B, and C. Doesn't mean it's true. Doesn't mean that we can't come up with a better explanation if we try harder. It just means that what I just said.

Personally, I'd say that the Higgs mechanism is the most *likely* explanation given it's elegance and the lack of other alternatives with the same level of elegance, but ask me again next year, and I might change my mind.

No we aren't. We just haven't come up with one after a lot of trying.

6. Dec 11, 2009

### twofish-quant

There are reasons for that. If quantum mechanics is correct, there is a limit to the structure that you can get. Again, this is observation not theory. It's one of those "I don't know why the universe works this way but it does" kind of thing.

The theory got more complex because the things that we started to observe got more complex. During the 1940's, people started observing *dozens* of new particles, and the standard model was an (largely successful) effort to try to simplify things.

Curiously that's my general impression. However, looking at the alternative explanations that were suggested at the time, they ended up being *even bigger hacks*. One good thing about the Higgs mechanism is that we know that it works. The idea of the Higgs mechanism comes from condensed matter physics and you can see it at work in superconductors.

Well, the trouble is that if you take away the Higgs mechanism and you don't replace it with something else, then you really don't have any model at all. The reason you have a Higgs mechanism is to explain why things seem to have mass. If you take away that and don't replace it with something else, then nothing has mass any more.

I don't think so. I'll change the wording in the article this evening.

7. Dec 11, 2009

### twofish-quant

Just changed the wikipedia article. I don't think that there is any observational evidence at all in support of the Higgs mechanism. There are a lot of (very good) arguments based on theoretical elegance, but the universe is sometimes quite inelegant. But if theoretical elegance determined physics we wouldn't be hunting for dark matter.

Now that LHC is up, this could change tomorrow.

8. Dec 11, 2009

### inflector

Thanks for the replies. I like the new wording much better.

9. Dec 11, 2009

### kote

Lots of good philosophical questions here . The first thing that I would mention is that there is typically an assumption of http://plato.stanford.edu/entries/scientific-realism/" [Broken], that says we can't prove, in the logical and mathematical sense, any theories about the external world. We relax the rules a little bit, trust our intuitions, and say that there really are such things existing in the world as tables and chairs etc. Extrapolating this reasoning, we infer the reality of electrons and photons etc. It's acknowledged that there is no logical proof, but if you suggest that we are living in the matrix and these things don't really exist, you get banned from PF for being a crackpot etc . It's become (mostly implicitly) an accepted part of science that we don't need logical deductive proof, because we can't have it.

It goes beyond the problem of induction though. We have found out that no scientific theory can be tested in isolation, and additionally, no individual theory can ever be proven wrong by observation. See http://en.wikipedia.org/wiki/Confirmation_holism:
It turns out that things don't fall neatly into theory / observation categories, and the two are inseparable. As long as your theories are self-consistent, the only remaining criterion is aesthetics. Which theory is more elegant and more consistent with common sense and our other theories?

We don't know that C is true instead of C'. We readily acknowledge that there are deficiencies in our current understanding, or else no one would bother doing any research. It's literally a logical impossibility to have independent proof of A B and C. It is therefore just as logically (in?)valid to posit D as it is to posit anything else. And, in fact, you are justified in positing D over your other options if it results in a more aesthetically elegant set of theories.

Science doesn't work through an idealized method - we have to just do the best that we can. An assumption of scientific realism gets us from this "best science we can do" state to saying we have overwhelming or even undeniable evidence of something, even though the logic in doing so is technically invalid. But the logical problems you found in the argument for the Higgs mechanism are the exact same logical problems you will run into in arguments for the existence of tables and chairs - so how much of a problem are they really?

I also recommend checking out http://plato.stanford.edu/entries/scientific-progress/. Kuhn, Popper, and Feyerabend are good sources if you're interested in scientific methods and standards. Feyerabend's epistemological anarchism might be an interesting starting point (though I'm not advocating all of his views).

And please don't take any of this the wrong way. I meant to add modern logical realizations about science to the discussion, which seem very relevant to your confusion/questioning. I'm not supporting any sort of anti-science view whatsoever, nor am I claiming that tables and chairs don't exist.

Last edited by a moderator: May 4, 2017
10. Dec 12, 2009

### twofish-quant

I may have to rewrite the article on confirmation holism. Unfortunately with respect to the philosophy of science, I'm more or less in the same boat as the OP is to the Higgs mechanism.

I disagree that any theory can be made consistent with observations. Part of the art of theoretical physics is to intentionally create theories that *can't* be made consistent with any set of observation. In the case of the Higgs boson, if we set up LHC and we don't discover Higgs after a few years, then this will rule out a set of viable theories in the same way that the lack of proton decay rules out a number of theories.

If you've modified the theory to match the evidence, then you've come up with a new theory. This is a good thing. People try to come up with new theories that are minimally different from old theories. One way of doing that is by using free parameters. A model in which you've modified the mass of the electron is a different theory.

I'd argue differently. Unless you can show how living in the matrix makes a difference, it doesn't matter. Protons really exist. They may be artifacts of some computer simulation, but they really do exist. One of the reasons that I think this way is that there *are* things that are computer simulations that can be studied scientifically. Namely money. One of the questions that will make you go pretty batty if you think about it deeply is "what is money?" I'm not sure, but I do know that whatever money is, most of it exists within cyberspace.

But the you get the question of "what is an individual theory?" The problem is that without any context, a "theory" is just a set of meaningless statements. I'd argue that no scientific theory can be tested in isolation because no scientific theory can *exist* in isolation.

And then that gets into the question of "what is science?"

The trouble with appeals to elegance and common sense is that there is no objective and standard measure of elegance and common sense. There is part of me that things that the Higgs mechanism is just totally wrong because it's highly inelegance and just plain ugly. Now there are people that disagree with this and thing the Higgs mechanism is beautiful and elegant. The trouble here is that if we get into "yes it's beautiful" "no it's not" arguments, there is no way I can see of resolving this.

So we can agree to disagree. Except that there is part of me that thinks that the Higgs mechanism *is* beautiful and elegant. So the trouble with appeals to elegance is that I don't know what to think about this.

Common sense is even worse. There are parts of physics that just run counter to common sense. Quantum mechanics for example. You will never understand even very, very basic QM if you appeal to common sense.

But if you want to get a consensual reality out of this, this assumes an agreement as to what constitutes "elegance." Personally, I think this is a bad thing because it results in unhealthy power relationships. If you have powerful people say "this is beautiful" then everyone else will nod their heads and say "yes, this is beautiful." The nice thing about experiment is that it limits power. If the CEO of a powerful company thinks that he can jump off a 500-foot cliff and survive (for that matter that he can sell massive amounts of subprime mortgages to people that won't pay it back), then I can argue that he is totally crazy and shouldn't be CEO. If things just become a matter of "beauty" well then, his standards of beauty are going to win over mine.

This matters, because some people think string theory is a beautiful theory. Personally, I think it's an ugly, ugly, ugly theory. But the people that think string theory is beautiful have tenure and I don't.

They are a big problem. If you can't tell whether or not a big bus is heading toward is real or not, then you have a big, big problem. Most people know whether or not there really is a big bus heading toward them. But what about subprime mortgages? weapons of mass destruction in Iraq? global warming?

It's *REALLY* important to know what the basis of the evidence is. Is the valuation of this bank based on something "real" or are we just playing games with numbers that will turn out to be bogus. That $5 billion dollars that I see on my computer screen. Does is it really exist or not? Is the stated value of this credit default swap based on experimental evidence, or are we just using a theoretical model that happens to be totally wrong. This reason that you have to think pretty deeply about this sort of thing is that you really have to try to understand *why* you think something exists. For tables and chairs, it's not that hard, and the consequences for getting the answer wrong aren't huge. For that number on your ATM that says that you have$X in your checking account, it's *REALLY* hard, and the consequences for getting the answer wrong (i.e. thinking that you have $2 trillion in wealth that isn't there) are huge. The reason I reject "common sense" and "elegance" is that there are lots of people in the world that are really good at using "common sense" and "elegance" to argue that you have$X in your checking account when that may not be there. Also "common sense" is sometimes dead wrong. It's common sense that in tough economic times that people shouldn't go into massive debt. It's also totally and disastrously wrong when you apply that to national governments.

11. Dec 12, 2009

### twofish-quant

The important concepts for me are "predictivity" and "usefulness." And I tend to talk about "models" rather than in terms of "theories." One thing question that I do find interesting is "what is science?" Since I suspect that I'll give a very different answer than most string theorists.

One thing that is different about me is that my concepts of what science is come out of a Chinese Confucian tradition rather than the Greek Platonic tradition. Since a lot of philosophy comes out of the Greek Platonic tradition, I find a of the ideas that philosophers talk about to be very, very nutty. One reason I have a high tolerance for "amateur crackpots" and is that I've ended up with a high tolerance for professional ones. (Note here that I'm avoiding using the terms Eastern and Western, since there are many different and conflicting Eastern traditions and many different and conflicting Western traditions, and a lot of the Chinese Confucian tradition came from Jesuits and Protestant missionaries and is rather anti-Buddhist and anti-Taoist. Whereas Evengeical Christianity is definitely a Western tradition, but it has a *very* different cosmology and rejects a huge amount of Platoism which they see are part of the Great Apostasy.)

This is why I have very strong problems with concepts of "foundational truth" that are based on aesthetics, because aesthetics can be very culturally dependent, and I have very different aesthetics than the Platoists. The reason interesting thing is that despite being culturally dependent, that somehow I don't get into "religious wars" over physics with people that come from a very, very different and conflicting cultural background. I think the underlying reason is that the foundation is experimental data. We are looking at the same data. We might interpret in different ways, but the fact that we are looking at the same thing imposes some common constraints on people with very, very different cultural backgrounds. We can all come the the conclusion that if you jump off the Empire State Building, you are going to die, and how you come to that conclusion really doesn't matter, and the emperor really doesn't care.

If you use aesthetics rather than empirical data as the foundation of science, then I think the whole thing is going to fall apart.

12. Dec 12, 2009

### twofish-quant

One curious thing is that even sometimes simple questions become difficult. Since I was a kid, I've always wanted to be a scientist. What's interesting is that I don't know if I've succeeded or not, since I really don't know if I'm a scientist or not, since I'm no longer exactly sure what a scientist is and what a scientist does, and this is partly because I'm not sure what science is anymore.

13. Dec 12, 2009

### daschaich

Just changed it back. There is overwhelming evidence for the spontaneous breaking of electroweak symmetry, which is an equivalent (but hopefully less confusing) phrase for "Higgs mechanism". I personally try not to use the word "Higgs" unless I'm referring specifically to models of electroweak symmetry breaking that involve one or more scalar electroweak doublets, either fundamental or composite. (So I would like the "Higgs mechanism" article at Wikipedia to redirect to "Electroweak symmetry breaking", not the other way around. But since they're the same thing, I haven't pushed this.)

Electroweak symmetry and its spontaneous breaking are facts of nature, successfully tested to about a part in ten thousand, by a vast number of diverse experiments over the course of decades. For instance, the existence of the experimentally-observed W and Z bosons is a prediction of electroweak theory. This is true even though the specific mechanism responsible for electroweak symmetry breaking remains unknown. (Hell, QCD spontaneously breaks electroweak symmetry, just not strongly enough by itself.)

Some good introductions that go beyond pop physics like Deep Down Things or The Second Creation are Chris Quigg's papers
http://arxiv.org/abs/0704.2232
http://arxiv.org/abs/0905.3187
and slides from his talk on "The Coming Revolutions in Particle Physics" (if you don't mind reading slides without having the speaker's commentary to go along with them). There are lots of versions floating around, a recent one is
http://lutece.fnal.gov/Talks/NERevolutions.pdf
I've taken a stab at explaining electroweak symmetry breaking myself (to undergraduate physics majors) -- slides are at
http://physics.bu.edu/~schaich/unpub/EWSB.pdf

Edit to add another introduction I forgot, Roberto Contino's lectures at last summer's Theoretical Advanced Study Institute in Elementary Particle Physics (TASI). They're aimed at graduate students in particle physics, but videos are available online. He explains in more detail some of the more fundamental reasons for electroweak symmetry breaking, beyond just mass generation.

Last edited: Dec 12, 2009
14. Dec 14, 2009

### kote

The confirmation holism idea is very abstract and only deals with the actual logic, not practical considerations. It says that you don't have to throw out your theory and modify the mass of an electron - you can just say, "oh that's not what I meant by mass, here's what mass really is." Your theory now fits, unmodified, because you've modified the assumptions. It's always possible to modify your assumptions because there are an indefinite amount of assumptions behind any theory.

The more relevant problem is the problem of induction. It's a logical fallacy to infer general predictive theories or statements about the laws of nature from discrete historic observations. Does that mean we shouldn't use invalid logic? Absolutely not. To make any empirical predictions we have to use this method of inference, so it's our only choice. It just means that we can always be wrong and we can never have logical deductive proof.

See also Affirming the Consequent - Use of the Fallacy in Science for a very brief overview of the type of logic the OP referenced, which is related to but not quite the same as the problem of induction. Using this type of logic is no more invalid than any other mode of inference used in science. (Someone posted the link on the philosophy forum and it reminded me of this thread .)

The empirical evidence and usefulness of a theory of course play a large role in its aesthetics. But there's a lot more to consider too, like how do we choose between the infinite number of empirically equivalent theories that we could come up with to describe any given phenomena? And, once you consider the logic of the confirmation holism article, how do we decide when to throw out a theory rather than modifying any other related theories and assumptions? We can always either modify a theory or its assumptions when modification is necessary, and doing either will give the same predictions. How do we choose when they are all empirically equivalent?

I just wanted to post that link, which directly talks about the logic the OP questioned. Those other questions are just some introductory philosophy of science :tongue:.

Last edited: Dec 14, 2009
15. Dec 20, 2009

### enotstrebor

Thaanks,
It is als important as it reflects the lack of questioning (or propoderance of unquestioning physicists) given the fundamental SM problems.

Now twofish, that is a scientific statement about the Higgs mechanism. But to inflector's point, the good arguments are dependent on A,B,C. The cosmological constant problem and other fundamental problems are telling us were looking at the data wrong.

Potential evidence that A,B,C are missing something (if you are open minded);

"What has not been seen is that given the experimental and theoretical uncertainty, the measured $$W^{\pm}$$ mass of 80398 $$\pm$$ 25 MeV [PDG] is exactly $$2m_{\mathrm{p}}/m_{\mathrm{e}}$$ (3672.30534) times the mass value symmetrically between the electron and the proton ($$\sqrt{m_p~m_e} =$$ 21.89648319 MeV), i.e. 80410.57 MeV

http://www.ptep-online.com/index_files/2010/PP-20-02.PDF" [Broken]

Mathematics is not physics. Because we can mathematically do it does not make it good or even possible physics. Does a particle renormalize itself?

P.S. Do you know anyone that's good with Einstien-Cartan models?

Last edited by a moderator: May 4, 2017
16. Dec 20, 2009

### humanino

The vast majority of high energy physicists only aims at going beyond the standard model. You should realize that all precision measurements serve exactly that purpose. It can even be argued that the remaining support towards non-perturbative QCD is largely because this constitute a background to beyond the standard model signals. I can not reconcile your above statement with the activity in high energy physics.

17. Dec 21, 2009

### enotstrebor

The reason you become a high energy physicist is because you believe the SM is pretty good but needs tweaking here and there (unquestioning), rather than an alternate theoretical approach (as indicated by the fundamental problems).

As indicated by Penrose, Most quantum physicists appear to believe that no such [alternate] theory is required, having made their peace with the seeming contradictions and obscure ontology of one or other of the standard pictures (or lack of such a
picture).'' Section 29.3-p 791.).

18. Dec 21, 2009

### humanino

This is neither the reason I became physicist, nor the reason of the people I know enough in the field to know how/why they became physicists.
So, because a famous brit said so, I'm supposed to buy it ? I have a lot of respect for Penrose, but again, just look at the activity in high energy physics, and try to get support for your claim. Can you quote a recent LHC publication saying "we are going to confirm the single SM Higgs and no more" ?

Look, I'm going to do homework for you. I will list the HEP papers one can find on arxiv right now, I mean, as of this very minute. Now in this list, as I already said, please ignore non-perturbative QCD business (if you decide not to ignore them, please pay attention to the fact that those people are unhappy with the non-perturbative sector of the SM, so they certainly do not "not question" and did not "make peace" with our understanding of the SM). Once we have taken out non-perturbative issues, who in this list qualifies as "happy with the SM" and/or "not searching beyond the SM" ? Please explain or please stop repeating what you read.

1) Implications of the CDMS result on Dark Matter and LHC physics
2) Combined analysis of Z' -> t tbar and Z' -> t tbar j production for vector resonance searches at LHC
3) Quarkyonic Chiral Spirals
4) The gamma = 100 Beta-Beam revisited
5) Non-leptonic weak processes in spin-one color superconducting quark matter
6) Stopping distance for high energy jets in weakly-coupled quark-gluon plasmas
7) Azimuthal asymmetries in exclusive four-particle "Drell-Yan" events, with lepton-antilepton plus proton-antiproton detection, in proton-antiproton scattering
8) J_AW,WA functions in Passarino-Veltman reduction
9) Exact renormalization group at finite temperature
10) Dark matter detection in the BMSSM
11) Environmentally Selected WIMP Dark Matter with High-Scale Supersymmetry Breaking
12) Hierarchical Neutrino Masses and Mixing in Flipped-SU(5)
13) Transport coefficients of a massive pion gas
14) The effect of kinematic constraints on multi-tension string network evolution
15) Relic neutralinos and the two dark matter candidate events of the CDMS II experiment
16) Flavor conversion of cosmic neutrinos from hidden jets
17) On the Oscillation of Neutrinos Produced by the Annihilation of Dark Matter inside the Sun
18) Determining the mixing of $\eta-\eta'$ in terms of the semi-leptonic decay of $D$ and $D_s$
19) Thermodynamics of a field theory with infrared fixed point from gauge/gravity duality
20) Very Light Higgs Bosons in Extended Models at the LHC
21) Supernova neutrino oscillations: what do we understand?
22) Scaling laws near the conformal window of many-flavor QCD
23) Derivation of a 1/r^2 potential term for QQ-bar in a potential model
24) A Comparative Study of Contributions to $\epsilon_K$ in the RS Model
25) Connecting the Direct Detection of Dark Matter with Observation of Sparticles at the LHC
26) Neutralino Dark Matter in Gauge Mediation in Light of CDMS-II
27) Real Emission and Virtual Exchange of Gravitons and Unparticles in Pythia8
28) NLO corrections to e+e- to WWZ and e+e- to ZZZ
29) Nonperturbative and spin effects in the central exclusive production of tensor \chi_c(2^+) meson