Since two NN analyses of the 2006 dataset did not see Single-T,
I would be interested to see application of the 2009 NN analysis to the 2006 dataset.

If the 2009 NN analysis were to see Single-T in the 2006 dataset,
then
I would be interested to see exactly the differences in the NN code between the two 2006 NN and the 2009 NN
that enabled the 2009 NN to see what the 2006 NN did not see in the same dataset.

Also, it might be interesting to apply the 2006 NN to the 2009 dataset.

Such comparisons might give more physical intuition into how NN code works.

Tony Smith

the current searches for single top have not established fully a signal yet. In CDF, for instance, the global significance is so far of just 3.7 standard deviations. These 3.7 sigmas are the result of a combination of several different analyses, and the effort of dozens of people, as you well know. Therefore, I think the 2.2 standard deviations that this single analysis adds to the lot are significant.

If you ask me whether this analysis by itself would suffice to establish single top production, of course I have to say it doesn’t, but with ten times more data it probably would.

I could marry your point of view and agree that hadronic searches are not really advancing our understanding at the forefront, but they do fill a lot of gaps in the back lines…

Cheers,
T.

sorry for the late answer. This analysis is considering a totally orthogonal dataset to the one of 2006, so the two observations are also orthogonal. As you may imagine, given that the data is different, and the fact that the final state objects are also different (no leptons in the latter case), the mass reconstruction cannot be compared in the two cases. In particular, I am not sure to understand what plot are you referring to, since this new analysis does not fully reconstruct the top mass.

Cheers,
T.

first of all, sorry for the belated answer -your comment went unnoticed along with the others in this thread, because I’ve been flooded with comments on the Gaza war these days.

The CDF detector allows particles with large component of longitudinal momentum escape through holes next to the beam pipe. This is done on purpose for two reasons: one, because the physics connected with those particles is not terribly interesting (although diffractive-physics aficionados do object), and two, because these particles have high energy and intensity is very high too, resulting in problems with radiation hardness. There is then a third problem, connected with the fact that high-energy particle hitting detectors located very close to the beam would create sprays of secondary hadrons which would mess up the measurements done in the central region.

That said, your question can be put in perspective. We cannot account for more than a few percents of the total energy released in the collisions, because most of it escapes along the beampipes. Even restricting to the inelastic collisions, that remains true. But if you were to ask “What fraction of the energy do you detect from particles emitted at an angle larger than 20 degrees from the beam?”, the answer would be 95 to 99%, because there the detector is quite hermetic. In fact, once the traceable losses from punch-through are accounted for, what is left is a few muons and neutrinos which escape undetected, and very few “blue sky” events which happen when the interaction point is displaced from the center of the detector by some amount (but I am not even sure this still holds in Run II -it was an issue from Run 1 I think).

Cheers,
T.

The middle figure of the second row plots
Events/10.20 v. Inv. Mass of 3 Leading Jets
and seems to me to show two data peaks,
one at about 150 and another at about 180.

The first (left-hand) figure of the fourth (last) row plots
Events/10.17 v. Inv. Mass of MET, Jet 1 & Jet 2
and seems to me to show a two-peak structure,
one at about 160 and another at about 180.

The first (left-hand) figure of the third row plots
Events/10.40 v. Inv. Mass of MET and Jet 2
and seems to me to show a data excess around 135.

As you might expect, I would like to interpret the two-peak structures as two states of a multi-state T-quark,
and
the excess around 135 as related to a low-mass T-quark state,
but
I expect that you would see them as statistically insignificant.

The public web page says “… we use a likelihood profile of this discriminant to measure the production cross section of single top events … We consider the uncertainty associated with the variation of the top mass. We consider top masses of 170 & 180 GeV as 2 standard deviation variations. This uncertainty is applied to all top processes. …”.

How does this analysis compare with
the CDF Likelihood Function (LF) Method
and
the CDF 1-dim and 2-dim Neural Network searches
that in 2006 did not find single-T events ?

In particular,
did the new analysis use less rigid assumption of Mt than the negative-result analyses of 2006,
thus allowing contributions from low-mass states of the T-quark?

Tony Smith

With regards to (what I understand as the root of) your question, it’s not that most interactions are non-understandable; most are boring. That’s why we have trigger systems to select interesting events and throw away the rest. At CMS, we aim to reduce the ~40M collisions per second (which can have up to ~15 proton-proton interactions each at high luminosity) to about 150 per second stored for analysis.

Summing up the energy in subdetectors over time is a useful tool, used for some calibration studies (as you know that energy deposition will have certain rotational symmetries), but it is the symmetry that is meaningful, not the absolute value.

That is, say, you have beams with X protons (anti-protons) in them. You have some percentage of actual interactions vs beam luminosity so say it is Y. So given a specific machine and a specific timeframe (so you have a standard energy per particle) you have some function Energy_in_interactions of X and Y for a given accelerator. What percentage of that can we account for by (*) actually looking at it with instruments and saying ok, e_1 energy in elastic collisions we see with ?, e_2 energy in mesons from interaction y_2, which we see with instrument ?? and so on.

(*) not all at once, but adding up the results of different detectors over time – once looking at this, then that.

I am asking because I am trying to understand if you are picking out specific cases with most of the interactions non-understandable, or are you filling in the nooks of things and we could look at almost all the interactions, so we are down to the hard cases of really rare interactions.

Thinking about it, what I am asking is what percentage of total beam luminosity could you UNDERSTAND if you looked for it and how much could you not even if you could see charged particles coming out? Say they hit twice and messed things up so it just couldn’t be figured out.

How much has this been getting better? That is, hpw much more efficient are we than 5, 10, 15 years ago

MRK