It is often said that a proton is made of three quarks: two of the same type, called up quarks, and one of a different type called a down quark. But that's not the whole story. In the space between these three stable quarks there is a boiling soup of quark–antiquark pairs. That is, a quark and an antimatter quark spontaneously come into existence, drift a while, and then recombine, destroying one another. This happens all the time— in every proton in every atom of every cell of our bodies, and in all of the matter in the universe.
When two protons collide in the LHC, most of the individual quarks miss each other. Often only one quark or antiquark from each proton collides directly. When an up quark collides with an anti-down quark, the two can combine to form a W+ boson; similarly, a down quark and an anti-up quark can combine to form a W¯ boson. In both cases, an antiquark is involved. Thus, each of the millions of W bosons produced at the LHC must come from at least one of these transient particles, caught before it had a chance to sink back into the soup.
CMS scientists recently measured the ratio of W+ to W¯ production in proton collisions at the LHC. The number of W+ bosons exceeds the number of W¯ bosons by about 40 percent, partly because each proton has two stable up-quarks for every stable down-quark. However, the exact ratio also depends on the density of the quark-antiquark soup.
My comment: This express asymmetry in favor of antimatter? Note the different quarks have different mass and hierarchy. Kea today: the remaining mystery is why the scales have the ratios that they do, namely roughly 2 and 36 for the down/lepton and up/lepton scales resp. Here with quarks we talked of protons, fermions. Has they also an hierarchy? l-adic /p-adic?
Counting W+ and W¯ bosons yields new insight into the dynamic structure of protons, which is too complicated to compute from first principles with current techniques. It also informs predictions of new physics: The rate at which hypothetical particles would be produced depends on the density of quark-antiquark pairs, for the same reason that W bosons do. It is important to know the thickness of this soup when imagining what else might spring from it.
— Jim Pivarski
http://resonaances.blogspot.com/2011/05/more-on-wjj-bump-in-cdf.html
SvaraRaderaUlla, this relates and shows the status of things where they can.
I is still a problem to me how in the use of standard ideas... even p-adic, and so on, that we can be limited by these hard found words which may not convey the higher insights.
Where the perpendicularity seems to have perpendicularity (in our more philosphic sense) it is natural to compare the anti-symmetry and the anti-matter otherview ideas and perhaps show the connection.
If, as a simple anlaogy and model here, we can determine things from the "Big Bang" as to this ratio of He and H, would it not be reasonable for some other concept of an initial beginning that the quark-antiquark ratios point to some higher level where we have to consider too that the universe in a sense has hierarchy (that nevertheless the data seems to show it too reaches some evidence of resonance).
It remains physically a question as to why this difference, and perhaps Kea's observation points this out depending on what level the math, such as p-adics, applies to what level of the otherness. 2 and 6 (thus 36) certainly have unique problems of constructable (fault lines) properties of numbers as in the dominoes in6 x 6 blocks of which no other numbers so have this property.
We deal with cubes in space which are essentially 3x3x3 but as in the report on the soma cube news there are other puzzles from such pieces that we can select coherently a different set to make a cube, even as a matter of dice probability. Nature obeys such rules even if it has the hidden bigger picture as so we do. Of course in the matters of 24 or 27 or 30 or 32 ways to organize things, 32 and 64 for example, it is clear that we should keep the numbers and geometry and dimensions straight if we are to probe the reality successfully in the down to earth effects to expect as TGD and Kea et all seems to promisingly do.
But let no one discourage you from your contemplations for you are getting there along with the rest of us mere humans who dare to think.
ThePeSla
WW-channel is just one way the proton can decay. Gluon-gluon fusion and WW/ZZ fusion are two dominant Higgs production mechanisms. It belongs to the background. H →WW*→lνlν* or lνjj- (ℓ=e or μ) Your link was about the second decay, the possible fifth force found earlier. It is rare. Also fusion of gluons are possible.
SvaraRaderahttp://arxiv.org/PS_cache/arxiv/pdf/1003/1003.4492v2.pdf
The twin Higgs mechanism is proposed as an interesting solution to the hierarchy
problem. The SM Higgs emerges as a pseudo-Goldstone boson once a global symmetry is
spontaneously broken, which is similar to what happens in the little Higgs models (Nima Arkani-hamed).
The left-right twin Higgs model predicts a light stable scalar ˆ S, which is a candidate for WIMP dark matter. We find that such an invisible decay can be sizable, which can severely suppress the conventional decay modes like h -> V V (V = W, Z) and h -> b¯b. On the other hand, compared to the SM prediction, the rates of Higgs boson productions at the LHC via gluon-gluon fusion, weak boson fusion or in association with top quark pairs are all reduced significantly, e.g., the gluon-gluon fusion channel can be suppressed by about 30%.
Higgs phenomenology, paying special attention to the decay h ->ˆ S ˆ S which is strongly correlated with the dark matter scattering on nucleon.
So dark physics is essential, at least as antimatter. Anti-symmetry is not anything iknowof, but asymmetry is shown almost certainly. A hierarchial physics with a scalar S could be replaced by p-adic interaction. But this is not standard model.
p-adics has nothing to do with the qubes you mention. They are classical. The scalar (ad hoc?) can though be chosen so it suits a p-adic hierarchy which can vary a little, depending on energy, density etc. This means the interference point is accomodating to the total situation. This is very difficult to achieve with a scalar.
Fermilab reported a distorted symmetry, too much W-, so something is not what it should according to theory.
I couldn't really grasp your comment, so please ask again if my answer went astray. Sry.
But I am far from any expert in these matters.
Interesting insofaras we are actually following each other...
SvaraRaderaThe cube thing was asserted as metaphysics really, but as an example or model we can make some sense of, yet it is after all about this question (some say is not a question) of what after all is classical and where it begins in any hierachy. Which is to say Euclidean and flat.
The fun begins if you try to make four dimensional "cubes" from such a set of possibilities and trying to decide if there are higher forms of curvatures involved.
In which case, regardless of what is a spinor or spin for that matter, the reach of some linear or more quantum like method, or the n-adic ideas, or braids even, is not a much higher reality of things than we now want to cling to.
Sorry if I did not read the decay modes in detail finding them primitive and boring and a great underestimation of our sense of space.
Perhaps you will like my biology speculation on the Dolphins in my last post.
If we are trapped in some terms and the notions behind them, well, intellectually one must consider that even the "experts" have understimated (except emotionally for or against) the new physics. And that is TGD too and to the extent it is quantum deterministic over the more general ideas- they underestimate it exactly like they tend to overestimate what we know applying physics to biology.
The PeSla
Read it as not much more of a higher reality than what we now want to cling to
SvaraRaderaor these do involve a higher reality than what we are used to
to clear what I meant up abit...
The PeSla
Now the new force seems confirmed, almost. The peak has become more pronounced! CDF does not give the precise significance, but informally the number 4.8 sigma is being quoted, say Jester. Should the new force then be called electrostrong? I guess this is exactly what the asymmetry is about.
SvaraRaderahttp://resonaances.blogspot.com/2011/05/cdf-wjj-bump-is-almost-5-sigma.html
Matti has also a post.
http://matpitka.blogspot.com/2011/05/150-gev-bump-seems-to-be-real.html
I guess we get the best possible picture of the new physics if we look at synthetic biology and artificial life. TGD is very close to whatit couldbe. But surely all that is simply speculations. It is a world of pure magic :) The candlelight can be true :)
Jester on the first link:
SvaraRaderaAnonymous said...
And some papers try to give one explanation to both ie 150GeV excess and top forward backward asymmetry. Could YOu comment on these?
30 May 2011 19:14
Jester said...
I'm not aware of a model where the connection is natural. It's always two independent couplings, one responsible for the bump, and the other for the forward-backward asymmetry.
30 May 2011 22:24
From a natural selection view life by replicating appears to have reverse causation as an explanation that the best theory is natural selection so far. (well, according to Steven Pinker and Dawkins and Cloak among others a decade and a half ago.)
SvaraRaderaMost things in nature are asymmetric, it is the symmetry and some idea like gravity up and down or defining right angles that is the exception. Cognitive theories can only explain things so far. Light does not tell us the texture of that it is reflected from and if TGD like ideas expect vague ideas of heat as the generator and a negative entropy- it is not a deep enough theory by itself.
His advice to Kea should be taken himself for they have missed each others point and the reflected wisdom does not reach do a higher view which is real science in the neutral content.
As Kea said we need to know a little more about these ideas and the theory of colour as applies to such particles.
Why should not a particle closer to the foundations or beginnings not give trouble for predictions in the simplicity and thus remain vague- one cannot improve or apply the quantum theory with its vague ideas that do not really extend to the complexity of living systems in a concrete and objective manner. The left and right brain theory is way obsolete, and if you read friends of Kea you find at the base of things a lot more depth than the simple perpendicularity we all wish we could easily identify with say dark matter or antimatter.
ThePeSla
I do not think Dawkins is totally right, there are much more to volution, because it stasted with Big Bang.
SvaraRaderaPlatonic solids are symmetric.
What is natural selection?
If TGD like ideas expect vague ideas of heat as the generator and a negative entropy- it is not a deep enough theory by itself.- I need explanations what you mean.
If you read friends of Kea - links/names.
Thanks.
http://www.science20.com/quantum_diaries_survivor/cdf_w_jj_resonance_closer_5_sigma_now-79526
SvaraRaderaHi Ulla,
SvaraRaderalinks of blogs listed on the right as in your page- hmmm you have here, did not know that.
the idea of heat, you see Pitkanen needs a better way to explain things considering Lubos replied and added that this was a bad concept- so I was thinking how he could defend it or nail it down.
There is no heat (molecular movement) in the subatomic particles but there is a relation to it at the surface of black holes as a description.
Dawkins makes more sense talking about natural selection than his anti religion lectures. I notice Matti uses the concept of memes which came from Dawkins.
Last I heard there was no good explanation for the time arrow as you pointed out as many have as good a theory as anything- and the big bang reference is ok in this respect and definitely a sort of motion or volition is involved in the evolving dynamics.
The problem is teleology, causes and effects and what direction and why. But I am at ease with effects that actually come before a cause (outside the light cone) or the illusion thereoff, but we can see things, the four terms for distance as all positive and all space only. It does not seem to matter for the final theory. (sorry, too long)
The PeSla
It's ok.
SvaraRaderaBy heat you mean dissipation? But that is very much in TGD, and dissipationless motion (which is dark also, and classic in Josephsons junctions). I simply cannot understand what you mean.
Entropy-negentropy is also about dissipation etc.
Memes is used by many. Dawkins has too much weight laid on competition, when cooporation also is very important.
Hmmm,
SvaraRaderaJosephsons junctions is a very neat idea of which I just read up on. Not sure it applies to our long dialog of comments here either.
But as some scale level the DC becomes AC at some cooling.
Surely this has some sort of biological application to our mental perceptions- that is if we think about such tunneling and resistances with cooler heads.
Some strange things happen with such force like entities, mathematical things where we wonder if the zero point is a filled vacuum.
Tension and Compression tends to reverse at some ground state. While this may be true in the usual quantum sense, say TGD applied to biology in a quantum manner, my problem with the idea of a zero point- a relative scale and a moving scale at that- at least to one Planck level- is that there is no consideration given to a Null-Point description of the energies involved.
If gravity, in hopefully what we mean as "dark" can change from attraction to repulsive as a force on the large scale- at least in the middle or life scale there is a level where this happens too- and on the micro scale it must be in some sense a deeper property of our still vague notions of the mathematics involved.
At this point we again have to consider the thermodynamic symmetries of whatever nature as a general issue to be solved before we can solve other things clearly.
In a general sense these are issues of density of some sort various bloggers here have recently discussed.
Thank you for the effort help keeping peace with the sensitive theoreticians around us :-)
The PeSla
Josephsons junctions are used in nerve impulse transmission. See http://arxiv.org/abs/1008.4279
SvaraRaderaThe null point could be exactly that - nothing. The null is only a mathematical construction? It meant a breakthrough once.
The gravity repelsion could be in the zero point. Why would it turn repelling there. This means the fields start conquer? Why? Because there happen some change. The quantization ends. No on-shell.
Antimatter is usually seen as gravitional. The handedness alone cannot change gravity.
How do we best describe thermodynamical symmetries? A ZOE is a good trial.
The theoretic toes are too sensitive. I have made comments to Kea twice, but she doesn't like them. I am not in favour. And Matti is silent. He can be SO stubborn :)
http://tgd.wippiespace.com/public_html/tgdeeg/tgdeeg.html#pulse
SvaraRaderaBose-Einstein condensates at magnetic
ux quanta in astrophysical length scales
Ulla,
SvaraRaderaGuess this was on my mind so I posted what I thought what I could say tersely but it is complex on "metaphysical thermodynamics"
It seems our boys are trying to work a lot of new physics ideas out... of course our dear Kea is there already.
Yes, as I said Theoretic Theories of Everything, TOE's are sensitive. :-)
PeSla
Ulla,
SvaraRaderaYou see, antimatter as that side of a mirror is a zeroth law thing and I am trying to talk at a deeper level which may or may not show chirality in clear space involved and yes it could be nothing at all absolutely.
But this link:
http://www.sciencedaily.com/releases/2011/03/110331104014.htm
Should warm our hearts that our emphasis and the importance of biology in the mix as well as some of the complex theories and speculations- quantum only or not- is the case. :-P~ to all the "to make he best science forum on the net" who banned me for such ideas- may your children's children ask what you did in the TOE wars as they understand the landscape and terrain of life and all the spins and matrices of which you had the credentials and power and did not consider as more and more fall by the wayside at what would really be, for our generation at least, rather simple cures.
* * *
Ye,I know. Antimatter is 'on the other side' but it should always have time-asymmetry. Still it could be an important 'motor'. This is very essential to the carbon function.
SvaraRaderaI have thought much of this. But there is so much I don't know.
B. Gohler, V. Hamelbeck, T. Z. Markus, M. Kettner, G. F. Hanne, Z. Vager, R. Naaman, H. Zacharias. Spin Selectivity in Electron Transmission Through Self-Assembled Monolayers of Double-Stranded DNA. Science, 2011; 331 (6019): 894 DOI: 10.1126/science.1199339
SvaraRaderaTransamino acids has an important signaling function too. The interesting thing is that they are about 4 % of the total.
I can see why that 4% is interesting!
SvaraRaderaHmmmm, what is the ratio of matter and dark matter-energy anyway?
http://theastronomist.fieldofscience.com/2011/01/universe-and-life-is-asymmetric.html
from these links from dave on kea's blog:
http://www.3quarksdaily.com/3quarksdaily/the-nominees-for-the-2011-3qd-prize-in-science-are-.html
Of course such asymmetry in nature has always been a sort of mirror controversy ever since those of us with such observations of spirals and such in life want to see such designs as meaningful or even magical.
But I am looking inside the helix itself rather than how they may form externally.
Of course this whole chirality issue is one of my deepest themes with a new approach I feel beyond mere quantum formalism like the idea of an antiparticle with reversed time as a description. Lately I find chirality itself not enough to explain things such as the structure of galaxy evolution.
In the paper I link to there is Carbon 84, but I already realize we can look at these things beyond the right and left and central division he makes of such geometric shapes. I do understand from Kea's view the utility of the reach of the concept of the associahedron. I wonder if Stasheff
would have been consulted by the stringers if they had known the results of this style of topology would have on their various theories?
http://focus.aps.org/story/v27/st22
SvaraRaderahttp://www.symmetrymagazine.org/breaking/2011/06/07/the-case-of-the-missing-proton-spin/
SvaraRaderaIt’s been nearly 25 years since the European Muon Collaboration made a startling discovery: only a portion of a proton’s spin comes from the quarks that make up the proton.
The revelation was a bit of a shock for physicists who had believed that the spin of a proton could be calculated simply by adding the spin states of the three constituent quarks. This is often described as the “proton spin crisis.”
“At that time people realized protons are not just a sum of three quarks stuck together like Lego-blocks,” said Jan Balewski, an MIT-based member of the Solenoidal Tracker At RHIC (STAR) experiment. “Protons are dynamic systems of interacting constituent quarks, gluons, and sea quarks.”
Gluons are massless spin 1 particles that “glue” the parts of a proton together; in this case, those parts would be two up quarks and one down quark. Sea quarks are quark-antiquark pairs that pop into existence and then annihilate each other almost immediately; their presence can contribute to the proton spin, making them a factor worth taking into consideration.
It has been postulated that the spin of the proton not only included spin from the three quarks from which it is built, but also from sea quarks and gluons. In fact, for a long time, physicists suspected that the remaining spin came from gluons. But as with the quark spin, experiments have shown that gluon spin can only account for a small fraction of the missing proton spin. The remaining proton spin should come from the orbital motion of the quarks, gluons, and sea quarks – and at the moment, the only direct measurements scientists know how to make are of the contribution from the sea quarks.
There are two kinds of W bosons. A W- boson is created when an up antiquark and a down quark from two colliding protons interact; conversely when a down antiquark and an up quark interact, a W+ boson occurs. Since the only antiquarks in a proton are sea quarks, and sea quarks always occur in quark-antiquark pairs, analyzing the W boson events can tell researchers how much of a proton’s spin comes from up and down sea quarks.
Although there are four other types of sea quarks (strange, charm, top, and bottom) which this measurement doesn’t account for, they all occur less frequently than the up and down quarks, with the strange quark being the next most common. As a result, some uncertainty about the composition of the quark spin contribution will remain. Nonetheless, what we do learn from these experiments remains valuable. Spin is central to a variety of scientific concepts and technologies, including the Magnetic Resonance Imaging machines that are used in hospitals around the world.
“The visible matter of the universe consists predominantly of proton-like particles,” Balewski said. “If the results of our experiment cause a revision of our understanding of the proton makeup this will impact how we describe visible matter in the universe.”
The question: how is it that the quarks spins’ contributions to the proton spin is only a small fraction of what was expected? To answer that, we need to learn more about where the quark spin contribution is coming from.
The three concurrent RHIC experiments may answer that question, it is the only collider in the world that will create polarized proton beams in which the spin state of the majority of the protons will be aligned with direction of the beam. This allows to study the correlation between the spin orientation of the proton and its constituents.
“The immediate access to reconstructed data has a significant psychological aspect, We can discuss how many Ws we measured last week, check if they look the same as those measured two weeks ago, and conclude that the detector is stable. We can also work immediately on improving and fine-tuning the W-finding algorithm and clean up the results while data are being taken. This accelerates analysis by many months.”
Using cloud computing provides new means to accomplish it.
What is spin?
SvaraRaderaSpin is an example of what physicists call an "intrinsic property" of particles. In other words, spin is so essential a characteristic of fundamental particles that you could no more change the spin of a particle than you could separate an electron from its charge.
Everyday objects have angular momentum when they are spinning, like the spinning wheels of your bicycle. That angular momentum is governed by a set of well-understood equations, assuring you will not fall from your bike. Although particles are not spinning, they have an intrinsic angular momentum, and that is what we call "spin." Spin is governed by a more complex set of equations similar to those that govern angular momentum, with a few key differences.
A rotating object would be rotating around an axis, which could be pointing in any direction. Likewise, spin points in a direction as though it had an axis; this is known as the particle's spin state. The similarity ends there, however. A particle with a spin of 1/2, such as a proton or quark, has only two spin states: 1/2 or -1/2. The sign indicates whether it is pointing parallel or anti-parallel with respect to the spin axis. Likewise, a particle with a spin of 1 can have three spin states: 1, 0, or -1. The 0 indicates that it is sideways, and not pointing along the spin axis. It is not possible to measure spin pointing in any other directions.
Spin 1/2 particles behave very differently from spin 1 particles. For the purposes of this article, however, the most important thing to remember is that spin 1/2 particles must follow the Pauli Exclusion Principle. This states that in a closed system, no two particles may occupy the same quantum state. In translation, that means that if you have two particles of the same type, with the same energy, they must have different spin states.
Consider the proton, a spin 1/2 particle which, with some approximation, consists of two up quarks and one down quark (each also spin 1/2). Because of the Pauli Exclusion Principle, if all three quarks have the lowest energy possible, then one of the two up quarks must have a spin of -1/2 while the other must have a spin of +1/2. The down quark is not identical to either of the up quarks, and so could have a negative or positive spin.
http://www.isgtw.org/feature/case-missing-proton-spin
http://marcofrasca.wordpress.com/2011/06/13/back-from-paris/
SvaraRaderaThis week was indeed plenty of information for people in high-energy physics due to the release by D0 of their measurements on the Wjj data, showing that the almost 5 sigma bump of CDF was not there
The second day Carl Bender gave a very beautiful talk telling us about PT invariant quantum mechanics. PT stays for Parity and Time reversal. The point to start from is the Dirac postulate about the Hamiltonian being Hermitian self-adjoint. Differently from the other postualates of quantum mechanics, this one is too much a mathematical requirement and one could ask if can be made somewhat looser. The paradigm Hamiltonian has the from H=p^2+ix^3. The answer is yes of course and we were left with the doubt that maybe this is the proper formulation of quantum mechanics rather the standard one. I suspect that this could represent a possible technique useful in quantum gravity studies.
On Wednesday there was the most shocking declaration from an experimentalist: “We do not understand the proton”. The reason for this arises from the results presented by people from CERN working at LHC. They showed a systematic deviation of their Montecarlo simulations from experimental data. This means for us, working in this area, that their modeling of low-energy QCD is bad and their possible estimation of the background unsure. There is no way currently to get an exact evaluation of the proton scattering section. I am somewhat surprise by this as so far, as I have always pointed out in this blog, at least the structure of the gluon propagator at low energies should be known exactly from the lattice. So, modeling the proton in such Montecarlo models should be a mitigated issue. This does not seem to be so and these different communities do not seem to talk each other at all.
Comment from Tony Smith:
Is that why D0 said in arxiv 11096.1457 that for multijet background calculations (particularly including the electron channel in the studies of the CDF Wjj bump) a “data-driven method” was used because “estimation of this background from Monte Carlo simulations is not reliable” ?
Could that explain at least some of the discrepancy between D0 and CDF analyses of the Wjj bump, particularly in light of the fact that the QCD Multijets background in the D0 electron channel data is centered around 105 GeV/c2 while in the CDF analysis it is centered around 75 GeV/c2 so that the D0 QCD Multijet background might be high in the relevant region of the Wjj bump (120 to 160 GEV/c2) thus obscuring a Wjj signal seen by CDF because the CDF method of calculating electron-channel QCD Multijet background may have been significantly different ?
Gordon Watts said on Back from Paris
SvaraRaderaJune 26, 2011 at 3:49 pm
In response to Tony Smith on June 14,
The reason that CDF/DZERO/ATLAS/CMS have to use data driven methods is this a combination statistics problem and detector modeling problem. First, this QCD background is for a lepton faking a jet. It happens so rarely that the amount of MC we would have to produce would be expensive and take a *very* long time. Second, this QCD background also covers various detector problems (imagine a heavy flavor jet with a lepton in it, jet measurement screws up, so it looks like a lepton on its own… ops). That is something our detector simulations are only so-so at… not enough for us to trust them for an analysis like this or one of the Higgs searches.
As to why the peak is where it is. I have no idea – and I would love to know. If you scale the results to luminosity and compare the results, you’ll see that DZERO’s lepton ID must be very different from CDF’s, so the reason could be hiding in there. [I am a member of DZERO].
http://www.physics.brown.edu/HET/PARIS2011/abstracts.pdf
SvaraRaderaIslam, Munir: “Proton Structure and Prediction of pp Elastic Scattering at LHC
at CenterofMass Energy 7 TeV "
Our phenomenological investigation of high‐energy and elastic scattering and
study of low‐energy models of nucleon structure have led us to a physical picture of
the proton; namely, proton is a ‐condensate enclosed chiral bag. Based on this
picture, we predict elastic differential cross section at LHC at c.m. energy 7 TeV.
Experimental measurement of elastic at LHC by the TOTEM
Collaboration from |t| = 0 to 10 will test our model of proton structure. We
also compare our prediction of with the predictions of the Block et al. model
and BSW (Bourrely, Soffer, Wu) model.
http://www.fnal.gov/pub/today/archive_2011/today11-07-01.html
SvaraRaderaToday’s featured CMS result is a measurement of the top quark’s mass and production rate at the LHC. Unlike any other quark, top quarks decay rapidly into a W boson and a b quark. Each of these can decay many different ways, giving scientists a choice in how to search for it. In this paper, scientists look for the following pattern: top and anti-top quarks produced in pairs, which together decay into two W bosons and two b quark jets, with both W bosons decaying into a lepton (electron e or muon μ) and a neutrino. Though the neutrino escapes undetected, it makes its presence known by shifting the balance of the other particles.
http://arxiv.org/abs/1105.5661
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.107.011804
SvaraRaderaBounds on an Anomalous Dijet Resonance in W+jets Production in pp̅ Collisions at √s=1.96 TeV
V. M. Abazov et al. (D0 Collaboration)
Phys. Rev. Lett. 107, 011804 (Published June 30, 2011)
An unexpected finding in a particle physics experiment must be reproduced to rule out the possibility that it is only a statistical fluctuation or due to something other than new physics. This is a primary reason for having more than one experiment studying the same kind of signal at a high-energy particle collider. At Fermilab, there are two such experiments: CDF and D0.
In April 2011, the CDF collaboration reported a 3.2 standard deviation excess in the number of events with a W boson and a pair of jets whose invariant mass was in the 120–160 giga-electron-volt (GeV) range (see T. Aaltonen et al., Phys. Rev. Lett. 106, 171801). One possible explanation for that excess was an unexpected new particle, with a cross section of approximately 4 picobarn (pb). Now, the D0 collaboration reports in Physical Review Letters their analysis of the same type of events. They see no evidence for such an excess, ruling out a particle with a 4 pb cross section at the 4.3 standard deviation level.
The two Fermilab experiments appear to disagree, but it’s not yet clear why. To facilitate comparison between the results, D0 made their search parallel to the CDF search to a good approximation, but there were small differences in how the two collaborations handled systematic errors, and of course the detectors are different.
It is also possible that CDF saw an upward fluctuation in the production of some new particle while D0 saw a downward fluctuation. D0 addresses this possibility, showing their p values for a range of potential signal cross sections. For example, there is only a 2% chance that a particle with a 2 pb cross section is compatible with D0’s data. Further results are needed to clarify the situation. – Robert Garisto
http://www.fnal.gov/pub/presspass/press_releases/2011/CDF-Xi-sub-b-observation-20110720.html
SvaraRaderaannounced the observation of a new particle, the neutral Xi-sub-b (Ξb0). This particle contains three quarks: a strange quark, an up quark and a bottom quark (s-u-b). While its existence was predicted by the Standard Model, the observation of the neutral Xi-sub-b is significant because it strengthens our understanding of how quarks form matter. The neutral Xi-sub-b is the latest entry in the periodic table of baryons. Baryons are particles formed of three quarks, the most common examples being the proton (two up quarks and a down quark) and the neutron (two down quarks and an up quark). The neutral Xi-sub-b belongs to the family of bottom baryons, which are about six times heavier than the proton and neutron because they all contain a heavy bottom quark. The particles are produced only in high-energy collisions, and are rare and very difficult to observe.
Fermilab’s Tevatron particle collider is not a dedicated bottom quark factory, sophisticated particle detectors and trillions of proton-antiproton collisions have made it a haven for discovering and studying almost all of the known bottom baryons. Experiments at the Tevatron discovered the Sigma-sub-b baryons (Σb and Σb*) in 2006, observed the Xi-b-minus baryon (Ξb-) in 2007, and found the Omega-sub-b (Ωb-) in 2009. The lightest bottom baryon, the Lambda-sub-b (Λb), was discovered at CERN. Measuring the properties of all these particles allows scientists to test and improve models of how quarks interact at close distances via the strong nuclear force, as explained by the theory of quantum chromodynamics (QCD).
Once produced, the neutral Xi-sub-b travels a fraction of a millimeter before it decays into lighter particles. These particles then decay again into even lighter particles. Physicists rely on the details of this series of decays to identify the initial particle. The complex decay pattern of the neutral Xi-sub-b has made the observation of this particle significantly more challenging than that of its charged sibling (Ξb-). Combing through almost 500 trillion proton-antiproton collisions produced by Fermilab's Tevatron particle collider, the CDF collaboration isolated 25 examples in which the particles emerging from a collision revealed the distinctive signature of the neutral Xi-sub-b.
The analysis established the discovery at a level of 7 sigma.
CDF also re-observed the already known charged version of the neutral Xi-sub-b in a never before observed decay,
http://blog.vixra.org/2011/07/21/susy-was-not-round-the-corner/
SvaraRaderahttp://blog.vixra.org/2011/07/21/highlights-of-eps-first-morning/
http://blog.vixra.org/2011/07/21/cdf-report-327-gev-anomaly-in-4l-channel/
http://blog.vixra.org/2011/07/31/higgs-hunting-2011/
SvaraRaderahttp://prespacetime.com/index.php/pst/issue/view/17
http://indico2.lal.in2p3.fr/indico/getFile.py/access?contribId=35&sessionId=13&resId=0&materialId=slides&confId=1507
Higgs Hunting Theory summary 30.7.
http://motls.blogspot.com/2011/08/babar-evidence-for-charged-higgs-boson.html
SvaraRaderaJust skip the comments.