Wednesday, January 08, 2014 ... Français/Deutsch/Español/Česky/Japanese/Related posts from blogosphere

Five HEP papers

The visitor number 10 million came to this blog around 11 am, Central European Time, today, from the whitehouse.gov domain. Congratulations (it was 5 am locally over there!). It's a coincidence because most of the recognizable visitors' domains seem to be academic and during the European morning, U.S. visits in general score less than 10% (over 50% when all times are included, however).
I will just mention five new papers on the arXiv – two hep-ph papers and three hep-th papers.

Chul Kim, Ahmad Idilbi, Thomas Mehen, and Yeo Woong Yoon discuss another interesting possible route for the supersymmetric particles to have escaped the detection at the LHC:
Light Stop Pair Production and Decays at the LHC
The top squarks may be as light as \(200-400\GeV\), long-lived, and they may form positronium-like bound state, the stoponium. These hydrogen-like particles may decay and leave footprints in the \(\gamma\gamma\) and \(ZZ\) decay channel data. They perform some sophisticated calculations and claim that while these long-lived bound-state-loving stops are invisible in the \(8\TeV\) run, they may become visible in 2015 when the \(13-14\TeV\) run begins.




Another hep-ph paper was written by Zhenyu Han, Graham D. Kribs, Adam Martin, and Arjun Menon:
Hunting Quasi-Degenerate Higgsinos
Higgsinos, the supersymmetric fermionic partners of the Higgs bosons (including the eaten Goldstone components), are more natural if they are light. Like stops, their lightness is helpful for the explanation of the lightness of the Higgs boson and the stability of the Higgs vacuum, too. If the different Higgsinos are comparably light, with the mass difference close to \(5-50\GeV\), then it turns out that it may be hard to see them and the bounds imposed by the LHC are just a little bit better than those from the LEP collider a decade ago. Using a channel involving leptons, jets, as well as missing energy, they quantify how much more visible these possible beasts are becoming at the LHC.




Now, three hep-th papers. Stephan Stieberger and Tomasz R. Taylor released an interesting preprint on mathematics of perturbative string theory:
Closed String Amplitudes as Single-Valued Open String Amplitudes
For decades, we have known about the KLT relations. The closed string's Hilbert space is approximately the tensor product of two copies of the open string's Hilbert space: one collection of degrees of freedom comes from the left-movers, another one arises from the right-movers. This "closed equals open squared" paradigm may also be used to relate the closed string amplitudes and "sort of squared" open string amplitudes. The KLT relations are particular formulae that make this concept work.

Heterotic strings hybridize a general left-moving sector with a different right-moving sector. Heterotic strings in 10 dimensions have a similar spectrum as type I string theory that includes open and closed strings. In some sense, the heterotic strings behave much like the open strings. The authors of this new paper find an interesting trick how to obtain heterotic amplitudes from the open string amplitudes by replacing all "zeta functions" in the open string tree-level amplitudes by their "single-valued" versions. After all these building blocks are "modernized" in this way, they may get the tree-level amplitude for an arbitrary number of heterotic string states.

In the second hep-th paper I picked,
Where-When-What: the general relativity of space-time-property
Robert Delbourgo and Paul D Stack discuss the idea of an extended spacetime with extra fermionic dimensions, like in the superspace of supersymmetry, but their extra dimensions transform as scalars and they have the interpretation of a "property", a word that these authors repeat 90 times in the paper. I didn't quite understand how they "fix" the violations of the spin-statistics relations (in RNS string theory, it's done by the GSO projections) but they seem to be aware of this problem, claim to have a solution (I haven't understood it yet), and their resulting theory looks like Einstein-Maxwell – similarly to the bosonic sector in the case of supersymmetry. It does look analogous to the NS-NS sector of the superstring – if their construction is correct.

Finally, there is a paper on the black hole interior,
Firewalls, smoke and mirrors.
Ram Brustein and A.J.M. Medved have decided that the violations of the equivalence principle near a black hole may be quantified by the "excessive coherence" between the Hawking quanta. They defend the claim that if the number of coherent Hawking quanta scales like \(N_{\rm coh}\sim \sqrt{S}\), the square root of the entropy, things work fine. If the number of coherent particles were smaller, a new scale in between the Planck length and the black hole radius would emerge which would be in conflict with the equivalence principle. But for the "square root" case, the black hole emits the information nicely enough. When the rate of the information emission becomes of order one in some units, the black hole becomes a perfectly reflecting mirror, we're told.

These are sort of interesting claims and conceptually new quantities and experts may want to publicize their answers to the same questions that were discussed (and perhaps answered) in this paper.



Off-topic: flights from Bremen, Germany were cancelled due to the UFO above on Monday. No one knows what the object was – it was like an airplane but louder – which is why it was an UFO. But if the UFO means an extraterrestrial alien for you, be my guest! ;-) "In Bremen" may very well be the answer to Fermi's famous question LOL.

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reader Luboš Motl said...

The free will isn't the same thing - and doesn't require - decoupling from the environment.


In fact, the free will only has a beef because the holders of the free will are *not* decoupled from the environment.


The absence of the free will would mean that the environment determines *everything* that the subject does. It's not true, and this is meant by the existence of the free will.


reader Calin said...

What from the chain of your decision taking does not belong (or belonged) to our environment (are the laws of nature considered as environment?)? Can you name one thing? Isn't our will determined by the environment? How, in what circumstances, do you think you took your first free decision? Or you think you make free decisions from your conception?


reader Enok said...

Hello,

The analysis is correct in the physical sense. Anyway there is one assumption that is not correct. The climate forcing of CO2 is not 3.7 W/m2. This figure includes the water feedback (hidden in the Myhre et at. article) and it is 50% of this value. So the right CO2 forcing is 1.75 W/m2. This means that the right climate sensitivity is about 0.525 K. Where comes from the balance value of 1.2 C?


reader Luboš Motl said...

I have already answered all these questions - and explained why your opinions are wrong. Please read the blog post, something that you have apparently not done yet.


reader lucretius said...

You now only have not read or understood Lubos' argument but also you are an ignoramus and a comically ignorant one to boot. "Free will" was discussed long before the Christian Bible and even without reference to God (e.g epicureans or Hindu philosophers) and also, of course, by Western philosophers such as David Hume who were certainly not trying to justify "bullshits from the Bible". You could try, for example, reading
http://plato.stanford.edu/entries/hume-freewill/

but unfortunately nothing will come of it since it is way above you intelligence level.


reader Calin said...

Can you enlight me how can we speak of free ("caused by our own willings, as Hume is saying") as something different than unfree ("by causes external to the agent"), as our will is determined by external causes?


reader kashyap vasavada said...

Hi Lubos:
I understand CPT and spin-statistics theorem for non SUSY particles follow from any local Lorentz invariant field theory. Does a similar theorem follow for SUSY particles?


reader Uncle Al said...

arXiv:1401.1401, Brustein and Medved
"a perfect reflecting information mirror" A perfectly reflecting mirror cannot emit where it perfectly reflects, or it violates the First Law. Wherefore Hawking radiation?

arXiv:1401.1238, Delbourgo and Stack
" we trust that one day somebody will conceive a radically new description of events that will lead to new insights with testable predictions."

"testable predictions." String/M-theory, quantum gravitation; SUSY/MSSM, proton decay, axions. CERN LHC observes no string/brane exotica, squarks, sleptons, bosinos, leptoquarks, lazy photons, WIMPs, colorons, supersymmetry exotica, extra-dimensions, magnetic monopoles, mini-black holes, Randall-Sundrum 5-D phenomena (gravitons, K-K gluons), ADS/CFT duality, fractionally charged particles.

Science must extend the preceding paragraph of fine mathematics distilled free of empirical relevance. Protect Aristotle from Galileo.


reader kashyap vasavada said...

Hi Lubos: My understanding is that CPT and spin-statistics theorem for non-SUSY particles follow from any local field theory. Is there a similar result for SUSY particles?


reader Dilaton said...

As an additional example for lack of free will in the political sense, members of stack exchange sites too strongly dominated by the SE point of view (even concerning the site topic very knowledgeable ones), behave in a mindless sheep or horde like way too, completely neglecting their good judgement, suppressing any fairness and common sense, or even acting against their natural discretion, to please the overlords and tons of random googlers.

Seeing such things emerge in real world communities would be a really scary thing, at times even some sect like traits seem to emerge with the disciples and informers blindly adhering to the word of well known SE Gurus and Celibrities etc ... ;-)

Reading on the TRF article now :-)


reader Luboš Motl said...

Dear Kashyap, the spin-statistics and CPT-theorems hold for all QFTs. That inevitably includes supersymmetric theories - theories which contains supersymmetric partners. SUSY theories are not some "deviated" constructs that could deny the laws of physics and mathematics; they are a special example of quantum field theories.


Your question is just like asking whether there is a similar result to (a+b)(a-b)=a^2-b^2 that would hold for b=365. Yes, there is. It's the same law. It still holds.


reader Vladimir Kalitvianski said...

It was not an UFO, it was unknown flying light in the darkness.


reader kashyap vasavada said...

Thanks. I see your point. Only reason I was confused was that they were trying to "fix" the spin statistics result. But if "fixed" it it is fine!!


reader Leo Vuyk said...

Dear Lubos, you wrote:

So the free will is the ability to make choices so that the
choice wouldn't be done by "someone else"

However, if the big bang is still fully symmetric and produced
CP(T) anti-symmetric bubbles of universes with instant entanglement down to
each quantum, then we live inside one of these bubbles and have to deal with
our anti-COPY me for a decision.

So democratic decision making, between two or even more distant
entangled subjects.

I think that this phenomenon already has its signal in the so
called Libet experiments.

See: Wavefunction Collapse and Human
Choice-Making Inside an Entangled Mirror Symmetrical Multiverse.

http://vixra.org/pdf/1103.0015v1.pdf


reader Claudia said...

Indeed, the paper on "Closed String Amplitudes as Single-Valued Open String Amplitudes" sounds very interesting: the authors also say, that all tree-level interactions (type I, Type II, heterotic, supergravity) are unified to all order in alpha'.


reader lucretius said...

"I usually read scientific paper."
I am sure you do Alexander. Let me guess, is it this one?


reader CentralCharge15 said...

Oh my god, 0 Centigrade?! And I start shivering here at 25 C : ) !


reader Dilaton said...

I always like such nice updates about "what is shaking" in Lumo s business :-)


reader Shannon said...

And I bet he takes part in all coloring competitions on it ;-)


reader neuromantic said...

I find it quite remarkable that the modern physicists have deviated from determinism so much, just because they are facing probabilities. Is it they truly believe that if our brains deal with uncertainty

every day, and accordingly evolution made them probabilistic, so this applies to the universe? Why should the universe be uncertain about itself?

I dont know why we're still talking about particles. As far as I remember we're having work with waves. The so called uncertainty principle is just a result from the mathematics of waves, their spectrum and the wave packet decomposition (or it's just how i see it), and from mathematical viewpoint there's no uncertainty at all in the picture, except the lack of knowledge about the exact structure of the packet - the frequencies and phases of the waves, etc. The principle talks about particle speeds and positions, but in the context of waves these concepts are meaningless.

Do we really need random generators to explain quantum mechanics? Even if we do we can certainly use quasi-random generators and "really good" can be translated as having a CPU register with enough bits to encompass the timespan of the universe (after which it will start to repeat itself). But i think a more plausible explanation will look like Conway's Game of Life. One can see how very simple set of rules can lead to complex and stable dynamical behavior. Obviously, there's no place for freedom there, except from the starting condition, and the degrees of freedom, which do not provide environment for free will. It's actually a form of quasi-random generator.

And if you lack a knowledge of the system's core even the fully deterministic behavior may look random. If the system at any moment can be described in finite number of states than sooner or later you will start to observe some patterns, following another patterns, and then not following them. So here come the probabilities -. our lack of knowledge. That's how quantum mechanics looks to me, and I remember how Gerard 't Hooft once shared the same vision - in his words there should be something beyond QM that makes hard determinism true again. I thought string theory was about removing uncertainty in quantum mechanics (besides the gravity thing), but i guess this will be in its next version.

By the way, the brain has nothing to do with the quantum level. It's much more like a classical dynamical system. Even if some neurons have a "choise" the system is made bullet proof and any queer behavior at the level of action potentials is largely ignored. Also, it's chaotic system, which makes it so interesting, and as such can be produced by the good old deterministic math rules. Chaos is hard to predict, and yet most of the brains in the world actually are very predictable. Clever people always feel like they have more free will than the not-so-clever ones, and they do, just like humans in general have more free will than the animals, but it's just more degrees of freedom. And when the grand chain of events is wandering through the labyrinth of a neural memory with a lot of competing ideas, the result looks like a free will to the self-loving egoist :) Sorry for the long comment.


reader Luboš Motl said...

Hi, physics is an empirical science. Physicists had to abandon classical determinism because experiments have proven that it doesn't hold in Nature. That's why all your extra philosophical words are redundant rubbish.


reader Eugene S said...

By coincidence yesterday I found this Smithsonian article: The Neuroscientist Who Discovered He Was a Psychopath


While studying brain scans to search for patterns that correlated with psychopathic behavior, James Fallon found that his own brain fit the profile



Of course, there’s also a third ingredient, in addition to genetics and
environment: free will. “Since finding all this out and looking into it, I’ve made an effort to try to change my behavior,” Fallon says. “I’ve more consciously been doing things that are considered ‘the right thing to do,’ and thinking more about other people’s feelings.”

I find Dr. Hossenfelder's stance on free will rather odd, almost perverse. Just because something can't be proved to exist beyond the shadow of a doubt, does not mean we are justified in proclaiming its non-existence. In matters as simple as choosing a flavor of ice cream and as profound as Dr. Fallon's choice quoted above, we experience ourselves exercising free will. And those choices, as the poet wrote, "make all the difference".



Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;


...

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I,
I took the one less traveled by,
And that has made all the difference.


---From The Road Not Taken by Robert Frost


Ultimate certainty of whether our free will was in fact free will or only an illusion, brought on by a cosmic ray striking a neuron or a change in the wind, or perhaps it was rigidly pre-determined from the beginning of time, may have to wait until after the end of our natural lifespan. But in the here and now, I see no benefits from choosing to disbelieve in free will.


reader Eugene S said...

If you think about it, though, Frost's poem does subtly investigate illusion in connection with free will. The second stanza goes:

Then took the other, as just as fair,
And having perhaps the better claim
Because it was grassy and wanted wear,
Though as for that the passing there
Had worn them really about the same,

So, it was really a toss-up which of the two to take!



And both that morning equally lay
In leaves no step had trodden black.



Yet in looking back, the narrator has settled upon a story and he's sticking to it ;)


That is the second layer of meaning hidden underneath the obvious first one.


Perhaps one should take Yogi Berra's advice:



If you come to a fork in the road, take it!


reader MoptopTheLibertarian said...

I think another part of his motivations is that "algor" means "to cool" in Latin, as in algor mortis, the cooling after death.


reader Eugene S said...

But see, you do this because you are careful about getting it right. A concept that is utterly alien to our friend Alexander. Though he probably learned from fellow climate insaniacs like this blogger. Check out the graph on that page stapling together paleo data with 120-year resolution and modern data with yearly resolution!

And for an even crazier graph, check out this concoction that Luboš linked to. It's the Guardian, but even the loyal readers are finding this too much: you can tell by the number of votes on each comment that the rats have started to abandon the sinking ship!


reader Steve Baker said...

Free will in Thailand is interesting. This is the most interesting situation for democracy to struggle with.

http://thinkingaboot.blogspot.ca/2014/01/at-last-clue-in-which-side-to-support.html


reader Werdna said...

Yep, those are pretty bad.

You know, something you learn if you actually try to analyze the climate data yourself, instead of just believing what you are told, is that the truth is usually a lot more complicated and interesting than the activist would have you believe.

For example, most of the changes look pretty benign in nature. It's not just that climate doesn't change much and therefore we can easily adjust, it's that it appears to change in mostly beneficial ways.

At least, that's the lesson of the last 30 or so years of supposedly anthropogenic warming.


reader neuromantic said...

Well, we're talking about free will here and it can hardly be described as empirical science, with or without scientific speculations. The Free Will Theorem is nothing short of a plain philosophy. If you're sticking to the physical evidence then maybe you should start with a proof of the cogency of the string theory. Have strings been observed in nature recently?

I still see no connection between the physical observations and your conclusion about the free will. Lets even assume for a moment that the electron is a pure particle. It has a probability of being somewhere in its orbital. Yes, we are uncertain about the exact location. It maybe even be purely random! But tell me, what is the probability of finding the electron outside of its orbital, cause I think it's exactly zero. Is the electron a free will particle?

Free to choose its exact location within the boundaries, maybe, but the chemistry doesn't care. Let it be wherever it wants; if you mix hydrogen and oxygen you have water. Quite deterministic if you ask me. If you put a visual signal on the retina, the visual neuron, despite its frivolous electronic behaviour will react in the same (almost, nothing is perfect) way, no matter how much experiments are made. And also, in a complex system like the brain, amongst thousands of synchronies, one little external cause can switch the behaviour of the circuit. Again, I see no place for free will. I know it sounds good, I just dont see its origin.


reader David Brown said...

"... the concept of free will."

"Free will is not a single concept, but an umbrella term." — George Musser http://www.fqxi.org/community/forum/topic/1958 FQXi'ers Debate the Deep Questions of Free Will, 2014 C.E.


reader Peter F. said...

From an effectively philosophy terminating muser' s Tolerance-Principled (and belated but impromptu) perspective:
Free Will exists (apart from some William released from jail) 'absolutely' only to the extent it means a "will" as in a want or desire or wish for, or a goal to do, ANYTHING (i.e. regardless of everything). :)
It "exists" in a relative sense in (however ephemeral) proportion to:
A. the number of needs or wishes that depending on a species' or individual's functional complexity and relevant adaptive flexibility can unconsciously emerge in brainspacetime (per lifetime or per any not too brief moment),
* multiplied by
B. the number of "'environmentally+physiologically+technologically' available to become realized" goals.
It is as simple as this! ;-)
Other than so, "free will" is an unusually sloshy or slippery talking-point and understandable only as a consequence of the Laws of Nature;"Laws" which - while underpinned by 'What Is going on quantumwise' - are known as far as we or some of us do thanks to by the knowledge-accumulating process of Science established principles that inform conclusively (and typically also as conservatively as realistically required).


reader Peter F. said...

Reading them "is one thing"; Understanding (intuitively and/or otherwise) that some of them belong in a trash can "is another thing". ;-)


reader Eugene S said...

How cold is it? It's so cold, even the polar bears are coming to town, hoping to warm up... and maybe catch a tasty snack: http://www.dailymail.co.uk/news/article-1102347/Chilling-game-hide-seek-hungry-polar-bear.html