STFC-RAL-CR03 R61: And over
STFC-RAL-CR03 R61: to eat them.
STFC-RAL-CR03 R61: Thanks for coming.
STFC-RAL-CR03 R61: Yeah. Good morning. Yeah. My name is Ethan Simpson.
STFC-RAL-CR03 R61: a postdoc at the University of Manchester, formerly
STFC-RAL-CR03 R61: at the University of Glasgow, where I I did this work. We realized this was the 1st in the autumn series. Happy to be kicking things up of your autumn seminars. So yeah, the title of this talk is entangled in talks.
STFC-RAL-CR03 R61: and it's the world's largest quantum information experiments. The whole veil of the stock is really the
STFC-RAL-CR03 R61: over the last. Well, certainly, of course, my Phd. Which started almost 5 years ago. Now
STFC-RAL-CR03 R61: people realize that one could do a different type, if you like, of measurement of the Nfc. And before about it in the same vein, but probing slightly different stuff. So it brings for probing nature of quantum mechanics. So what I'd like to do is kind of show you how this came about, and a little bit of the theory behind that, and then set primarily at the Atlas result controls came out almost a year ago. The 1st measurement of this phenomenon of quantum entanglement.
STFC-RAL-CR03 R61: a large hyper collider, and then I'll make a couple of comments on the Cms's subsequent measurements of the same phenomenal in a couple of different channels
STFC-RAL-CR03 R61: close by, talking about.
STFC-RAL-CR03 R61: maybe where the where this kind of new
STFC-RAL-CR03 R61: something with those subfield is doing.
STFC-RAL-CR03 R61: So yeah, it's motivated by this idea as part of business we ever think about quantum mechanics
STFC-RAL-CR03 R61: confess my ignorance on the various parts of research that goes on here around in terms of particle physics. But I think it's fair to say that
STFC-RAL-CR03 R61: when we were thinking about this, we kind of realized that despite quantum mechanics, completely underlying standard model. Really. So it's baked right in there from the start. They're set with what we do. We don't actually think about quantum mechanics.
STFC-RAL-CR03 R61: All that much. It's really a.
STFC-RAL-CR03 R61: It's quite extrapolated away quite a lot from from what we think about. So this is using
STFC-RAL-CR03 R61: machinery attitude
STFC-RAL-CR03 R61: and come back to those kind of fundamental quantum mechanical ideas.
STFC-RAL-CR03 R61: Say right at the start, what about quantum computing. That's kind of quantum mechanical, surely, and it's a lot of different and applications or possible applications of quantum computing and high energy physics. We need to improve the various techniques that we have everything from doing flavor, tagging, simulating barcode showers.
STFC-RAL-CR03 R61: doing a simulation on the lattice. So all these kind of techniques of fundamentally using quantum mechanics, using quantum computing to if you like, improve the techniques that we have in the fields. But I'm not talking about that aspect of it I'm talking more about.
STFC-RAL-CR03 R61: Let's look what quantum mechanics can do for energy physics.
STFC-RAL-CR03 R61: I'd say more.
STFC-RAL-CR03 R61: Can we use high energy physics to test quantum mechanics and specifically in a new energy system. So it's what we call quantum observables. It's a bit of a
STFC-RAL-CR03 R61: slightly controversial, salesy way of talking about it. But these are observable, so we can measure the large rapid collider to tell us something about the quantum mechanical nature of
STFC-RAL-CR03 R61: understand the model.
STFC-RAL-CR03 R61: So the point of all this like, remember, I gave this a Birmingham person up here. So they changed that for this part of the world apologies for that. And but the point here is that quantum mechanics was really developed for this kind of landscape for the atomic landscape, and then tested it there very vigorous, very rigorously.
STFC-RAL-CR03 R61: I'm in kind of
STFC-RAL-CR03 R61: fundamental research now, trying to think about how we can extend the research or the experimental research on mechanics up to macroscopic scales.
STFC-RAL-CR03 R61: things like on fluid and super conductivity, but macroscopic phenomena, quantum mechanics, and again, quantum computing at a large scale. So this is kind of pushing the quantum world to
STFC-RAL-CR03 R61: higher landscapes, larger landscapes.
STFC-RAL-CR03 R61: You can go right to the other end of that spectrum and talk about this. It from Qubit idea, said that which is
STFC-RAL-CR03 R61: thinking about how quantum mechanics, or how quantum information theory in particular, informs the actual nature of the kind of fundamental theory of the universe. Talking about the
STFC-RAL-CR03 R61: information, theoretical content of quantum field theories
STFC-RAL-CR03 R61: going to be talking about entanglement. So is something that we take for granted, like spacetime. Is that an emergent property of something more fundamental, like quantum entanglement.
STFC-RAL-CR03 R61: So the point here is that people are now thinking about quantum mechanics, not just at scale, but across the entire energy regime energy spectrum. But this is the area that we'll be focusing on today. And a couple of motivating points for that reason does quantum mechanics look different in this regime. So where we don't just have the quantum mechanics that
STFC-RAL-CR03 R61: one has learned, or maybe been lectured about, but
STFC-RAL-CR03 R61: somewhat different theory, based simply for quantum mechanics. How does the do the same phenomena exist there? How do they manifest differently at a scale?
STFC-RAL-CR03 R61: And then, maybe slightly, controversially, to say that this is, try to do something, maybe slightly
STFC-RAL-CR03 R61: out of the normal or
STFC-RAL-CR03 R61: existing Atlas measurements. So there's more to life than maybe searching for new physics. That kind of thing, making precision measurements of stand on phenomena. This is trying to sell itself as doing something
STFC-RAL-CR03 R61: slightly slightly novel within the the Atlas community.
STFC-RAL-CR03 R61: and maybe also make some remarks about this at the end. Danny's so called quantum observables actually help us in our more traditional tasks of looking for new physics.
STFC-RAL-CR03 R61: So a little bit on quantum entanglement, I should ensure you seem very well aware of this phenomenon, so I'll just go through very quickly. There's some kind of correlation between quantum numbers I like the description at the bottom here that you kind of write down the description of one particle without describing the other. So that talking about entangled spins of top quark pairs, the idea is that
STFC-RAL-CR03 R61: when we have this entangled description, we fundamentally can't just talk about one of the tops. We're talking about the ensemble of both of them. So this idea of correlations between the top parts is exactly what we're going to be talking about and formalize it in a moment.
STFC-RAL-CR03 R61: Just to say that this phenomenon of entanglement has been measured.
STFC-RAL-CR03 R61: and in many different contexts, although none of the energy scales that we're talking about here. But this is a very well known phenomenon
STFC-RAL-CR03 R61: other than
STFC-RAL-CR03 R61: they were kind of kicked. A lot of this work office. Nobel Prize was awarded for the kind of pioneering work in in time doing, using photons and establishing this quantum information as a
STFC-RAL-CR03 R61: by the field of science.
STFC-RAL-CR03 R61: And so it's actually quite
STFC-RAL-CR03 R61: a nice day to be talking about. As I say, it came out almost a year ago.
STFC-RAL-CR03 R61: But today it's actually going to be published later on. So if you're inspired by this talk, or you want to see that I was making a fair representation of the of the measurement, and 4 o'clock the paper will be published actually. And but yeah, just to say that this is a result that has gotten some interest in the in the community.
STFC-RAL-CR03 R61: Now there were a couple of measurements of the quantum entanglement in high energy physics all the way back, what's that? Nearly 20 years ago.
STFC-RAL-CR03 R61: 17 years ago as a measurement of a kind of flavor entanglement.
STFC-RAL-CR03 R61: A bell, too.
STFC-RAL-CR03 R61: and the bottom result here is actually a reinterpretation of a measurement from any of showing that actually, there's a form of polarization entanglement present in the specific decay that I show here. So this atmosphere, in
STFC-RAL-CR03 R61: looking at entanglement and energy physics. But it's if you like, the
STFC-RAL-CR03 R61: the one that's been done dedicated at the highest energy scale at the at 13 TV.
STFC-RAL-CR03 R61: And I changed the slide, because since the result of last year Cms. Have presented 2 further results of entanglement.
STFC-RAL-CR03 R61: both in pair production, and I'll mention them very briefly at the end and make some comments on the comparison between the various results.
STFC-RAL-CR03 R61: So the kind of strategy for doing this is really this
STFC-RAL-CR03 R61: serves as a structure for the talk in the next 45 min or so is really to define a quantum mechanical description of Tt. Bar production, and then condense that description down into what we call a single entanglement marker. So we take a in principle, quite a complex
STFC-RAL-CR03 R61: build, theoretical scattering, amplitude, computation, and apply the techniques from quantum information theory and say, Well.
STFC-RAL-CR03 R61: if we know what quantum entangling is.
STFC-RAL-CR03 R61: and we know what Tt Bar hair production
STFC-RAL-CR03 R61: looks like.
STFC-RAL-CR03 R61: and we condense that description down into just one thing, then we just measure that one thing. Show me.
STFC-RAL-CR03 R61: Technically, we measured some angular separation between the decay products of the the top and the antitop there, or the top and the antitop, and then extract the single entanglement marker, and then compare this against the the limit that one gets from quantum information theory, and it's really as simple as that. And then
STFC-RAL-CR03 R61: I mean, defend against claims that this is just measuring something, spinning correlations which you may or may not be aware of. I'll discuss them later on. But I'm trying to make the point here throughout that this is something a little bit more than just measuring these things of the top parts that we measured before.
STFC-RAL-CR03 R61: It's a brief interlude on the top part. So we've produced hundreds of millions of top parts at the end of C. So we're really in this era of Presidian physics with regards to top parts. And
STFC-RAL-CR03 R61: that's what I work in now at Manchester. I'm less involved in the quantum information side of things, but I still work very heavily within precision top part measurements.
STFC-RAL-CR03 R61: Now the the key idea of the top part. To say, I don't know the makeup of the audience here, but maybe you're aware of, instead of simple facts, is that
STFC-RAL-CR03 R61: the the top is a Svenheit Berbian, as I'm sure you know. So what that really means is that it's a it's a Cuban.
STFC-RAL-CR03 R61: Just quantum
STFC-RAL-CR03 R61: states quantum analog of this this classical bit states, or in a quantum information sense, you can think of the top as a qubit, and therefore Tt. Bar pair. Production is the entanglement of 2 qubit states. And that's something that's really easy to in principle, very easy to analyze. People have known how to
STFC-RAL-CR03 R61: describe entanglement in in this 2 qubit system, for you know best part of 50 years.
STFC-RAL-CR03 R61: The other point is at the top decays weekly and into case quickly.
STFC-RAL-CR03 R61: So and
STFC-RAL-CR03 R61: what? That is, yeah.
STFC-RAL-CR03 R61: yeah, maybe I'll just sort of mention that the point is.
STFC-RAL-CR03 R61: but because it's not the case through this
STFC-RAL-CR03 R61: W
STFC-RAL-CR03 R61: essentially, that that constrains the helicities of the decay products, and therefore the angle on which the pop is produced. So the point here is that because of particle, phase, weak interaction, and extremely fast before any of its quantum numbers can get washed out before it's spinning deeper. Here, then, the spin information on the top is passed through the decay chain to the decay products, and in particular their kind of spatial relation within the detector
STFC-RAL-CR03 R61: she can set
STFC-RAL-CR03 R61: you measure, if you like, where, in the where in your detector the decay products are produced, you can perfectly, in the case of let them perfectly reconstruct the spin state of your top. So that means that really a measurement of the spin entanglement of top antitop production is a measurement of the
STFC-RAL-CR03 R61: position of the angular separation, technically, of the decay products in the detector hopefully, that's clear.
STFC-RAL-CR03 R61: So this is how you write down. Tt Bar production.
STFC-RAL-CR03 R61: Really, this is, this is a cross section of a scattering amplitude actually factorizes into these what we call density matrices. That'll be important. And we're concentrating on that middle one. There. The production density matrix can actually be written in this form, which is important. We'll see this later a couple of times.
STFC-RAL-CR03 R61: These orange terms. Here are the polarizations, spinning polar polarizations, the individual top, and at the top.
STFC-RAL-CR03 R61: and this last term here the correlations of the States between top and the Antone. So what all this is saying is that we can describe.
STFC-RAL-CR03 R61: if you like, the the cross section of Tt bar production in terms of the polarizations and correlations. And that's frequently how we do these spin measurements.
STFC-RAL-CR03 R61: And there's a long history of
STFC-RAL-CR03 R61: doing this Atlas and Cms. So maybe I'll just comment on the the well. What was the latest Cms result in the diet on channel. This is from maybe 5 years ago now, where people actually measure these various polarizations and spin correlations and compare them to the standard model. And so the the values that you see here, the sea, for example, these are the correlations between the top and the antitop in various well, in that specific reference rate.
STFC-RAL-CR03 R61: So what I'm making is that, Alex. See, we have a history of being able to make very precise measurements. The spins and the spin correlations of feeding bar production.
STFC-RAL-CR03 R61: And this is what I mentioned before, just making the remark about the top decay through the W very, very fast controls the direction of the decaper. So I think I'll skip over that.
STFC-RAL-CR03 R61: So that's what we need to know about the top.
STFC-RAL-CR03 R61: Let's talk about the quantum mechanics and how we can
STFC-RAL-CR03 R61: effectively steal a definition of entanglement. So
STFC-RAL-CR03 R61: maybe in a
STFC-RAL-CR03 R61: quantum mechanics courses that he undertaken. Or maybe the lecture. You remember the
STFC-RAL-CR03 R61: you can represent all of a kind of state by some
STFC-RAL-CR03 R61: some ray in a in a Hilbert space. But that's not the most general quantum mechanical description. We actually have to move to something called a density operator, still defined in that Hilbert space which is
STFC-RAL-CR03 R61: a a mixed ensemble of various quantum states. So this is the most general quantum mechanical description that we can we can come up with.
STFC-RAL-CR03 R61: And so, yeah, I've just just described the density matrices of the
STFC-RAL-CR03 R61: Pt Bar production. So they're kind of big leap in in logic here from the theorist community 5 years ago. So it was to realize that this.
STFC-RAL-CR03 R61: this density operator. This density matrix. Here is modulus of numerical factor, exactly the same thing as this density matrix that we have for Tt Bar production.
STFC-RAL-CR03 R61: So then, to think more about the quantum information side of things.
STFC-RAL-CR03 R61: But it's what I'm thinking there's a
STFC-RAL-CR03 R61: this is the mathematics actually informing the physics. So the mathematical properties of density, matrix reveal aspects of the quantum state. So essentially, by doing linear algebra on this density matrix, you can say whether things are entangled or not.
STFC-RAL-CR03 R61: And in particular, the question is, is this density matrix factorizable?
STFC-RAL-CR03 R61: This is what entanglement means. Fundamentally so, if you could write your density matrix for Td bar production as some kind of
STFC-RAL-CR03 R61: convex combination of the product of individual density matrices.
STFC-RAL-CR03 R61: one describing the top and one describing the antitop. Then your States is separable
STFC-RAL-CR03 R61: I go. It's not in time. So it's exactly what I was saying entitlement, you know. If you can strike the constituents individually.
STFC-RAL-CR03 R61: then you're not talking about entitling. This is exactly what the expressions say.
STFC-RAL-CR03 R61: And conversely, if you can't write your density matrix in this form, then it must be in time, and in general, this is really quite difficult to do
STFC-RAL-CR03 R61: in the general case, and be hard actually to work out if some arbitrary system, if there's the matrix, is separable. But luckily we're talking about this 2 qubit state. So it's actually quite easy in principle to
STFC-RAL-CR03 R61: so want to talk about the Tt Bar production base space here and talk about a couple of tools that we borrow from quantum information theory. So the 1st is this thing called the concurrence. So this is what we call entanglement. Monitor tells you how entangled your state is. This is just a some monotonic function
STFC-RAL-CR03 R61: from one to 0,
STFC-RAL-CR03 R61: spotted up, if you like on the heat map. There's the color. So what they're telling me is, if you're 0, your state is not entangled, and if it's 1, it's maximum entangled.
STFC-RAL-CR03 R61: So what the theory community did was to compute this concurrence for Td. Bar production
STFC-RAL-CR03 R61: as a function of the
STFC-RAL-CR03 R61: like. The opening angle between the top parts and the invariant mass of the the Tt. Bar pair.
STFC-RAL-CR03 R61: And so what this is essentially saying is.
STFC-RAL-CR03 R61: you know, where is entitling? Does it exist at all in tiki bar production? The answer is, yes, in 2 regions.
STFC-RAL-CR03 R61: So the reason I'm really going to concentrate on is this highly colorful band the bottom here and say that we have a Max fully entangled, actually a spin singlet state which is produced very near the production.
STFC-RAL-CR03 R61: So this is one region of fundamental. This is
STFC-RAL-CR03 R61: some principles well, in some ways relatively easy to measure, because there's plenty of events there. The T Bar Cross section follows up by steeple as a function of Mt. Bar. So in this region, here we have high statistics.
STFC-RAL-CR03 R61: Now, there's this other region
STFC-RAL-CR03 R61: in the top right there. So
STFC-RAL-CR03 R61: in a kind of boosted regime. High values of Tt. Bar, invarian mass with a maximum time of spin triple state
STFC-RAL-CR03 R61: and Atlas hasn't looked at that at all. But Cms. Has quite recently
STFC-RAL-CR03 R61: made the 1st observation of quantum in this regime, and I'll mention that at the end. But for the purposes of the the Atlas
STFC-RAL-CR03 R61: important of this. We're going to be focusing on this threshold region here.
STFC-RAL-CR03 R61: Now, I want to talk about one other tool. The other thing that we borrow from quantum information. Theory is this thing called the Paris Horadecki criteria. So this is a Horadecki family there. Amazing family of physicists all at the University of Poland, and they're like family business, just quantum entanglement, if you like. So they're all working on this. And so this Horadecki, this Paris Horadecki criterion is a specific criterion on the density matrix.
STFC-RAL-CR03 R61: Basically, you do a bit of linear algebra
STFC-RAL-CR03 R61: compute something called the partial transpose. It's just a linear algebraic operation. And you're saying so
STFC-RAL-CR03 R61: after I do this, do I still have a density matrix
STFC-RAL-CR03 R61: or not?
STFC-RAL-CR03 R61: And so
STFC-RAL-CR03 R61: I don't even need to worry about it.
STFC-RAL-CR03 R61: Yeah. So there's a lot of linear algebra involved here. I condense it down into some kind of mean form. So basically, you have this
STFC-RAL-CR03 R61: very complex form of the density matrix. You're trying to say, you know, I take the partial transpose of this. Do all this linear algebra make some simplifications, get rid of some of these terms that we assume leading order.
STFC-RAL-CR03 R61: doing all that later on for process, you can actually write your criteria down as just this. So these things you better remember from a few feasibility and spin correlations that we can measure
STFC-RAL-CR03 R61: and have them in Td Bar production. So I've changed this slightly because this criterion
STFC-RAL-CR03 R61: differs, depending on when you're in that threshold regime or the high class regime.
STFC-RAL-CR03 R61: But in principle, the point I'm making here is that
STFC-RAL-CR03 R61: is this separable? It's very complicated statement. Actually, we only need to measure 3
STFC-RAL-CR03 R61: parameters
STFC-RAL-CR03 R61: or not even that we can actually define.
STFC-RAL-CR03 R61: Just so get an average of these 3 parameters, the key parameters.
STFC-RAL-CR03 R61: And then so all one needs to do, then is measure
STFC-RAL-CR03 R61: this the single value in data, and compare it to this entanglement condition.
STFC-RAL-CR03 R61: This is just, I think, like a rearranging all this, the slight complexity, the sign of these terms, change so
STFC-RAL-CR03 R61: threshold in this low mass region.
STFC-RAL-CR03 R61: All you need to do
STFC-RAL-CR03 R61: to say whether your density matrix is separable is measured. This value of D to be less than minus 1 3rd
STFC-RAL-CR03 R61: analogously in the high message.
STFC-RAL-CR03 R61: So the principle that's very simple.
STFC-RAL-CR03 R61: And it can actually be done even more simply because you don't need to measure these 3
STFC-RAL-CR03 R61: contributions, because there are these.
STFC-RAL-CR03 R61: take that a single differential distribution
STFC-RAL-CR03 R61: from which he can be extracted. So here this is.
STFC-RAL-CR03 R61: talk about this cost 5, which I talked about a lot. This is just the if you like, the scalar product of the 3 momenta of the laptops, the decay products of the tops, electrons boosted into their parent top frame. So that's what I was talking about, this angular separation between the tops. We just have this one angle. If you like that we need to measure, we can build this differential distribution and then extract this value of the some expectation value of that distribution.
STFC-RAL-CR03 R61: So to summarize what I've said so far, and I'm going to see if there are any questions.
STFC-RAL-CR03 R61: This Td bar production is described by his Nsd matrix.
STFC-RAL-CR03 R61: and the the idea of entanglement quantum entanglement is a non separability of the density matrix.
STFC-RAL-CR03 R61: And it turns out that it's this simple case.
STFC-RAL-CR03 R61: Yeah, 2 tops
STFC-RAL-CR03 R61: to qubits to entangle qubits. We can measure the entanglement through one angular observable to this value.
STFC-RAL-CR03 R61: So hopefully, that's
STFC-RAL-CR03 R61: it's not too complicated. I wonder if there are any questions
STFC-RAL-CR03 R61: at this point on the kind of theoretical background for that.
STFC-RAL-CR03 R61: We look at Titty Bar flight threshold as well, so always took off.
STFC-RAL-CR03 R61: Yes.
STFC-RAL-CR03 R61: why, it's not friction
STFC-RAL-CR03 R61: so
STFC-RAL-CR03 R61: not really. I mean the stats drop off by drastically, and then
STFC-RAL-CR03 R61: but maybe I can make some more remarks and come on to this. And the interesting stuff that happens just around thresholds, really. But yeah, I don't know what the
STFC-RAL-CR03 R61: dynamics of the system are in that.
STFC-RAL-CR03 R61: You know the questions that people took to send me the paper that came up. And all this, and it's kind of hard cut, 3, 40, or something like that. So
STFC-RAL-CR03 R61: I don't know what the entitlement looks like.
STFC-RAL-CR03 R61: and I think.
STFC-RAL-CR03 R61: because I you remember on that box right now, in any
STFC-RAL-CR03 R61: expanding of the bin, if you like. If you want to measure this value of d there, this will contaminate what you have there, but I don't know what the
STFC-RAL-CR03 R61: which. I don't know what the dynamics look like from a theoretical point of view below the production pressure plus communities.
STFC-RAL-CR03 R61: Any other questions. Before I go to the the measurements service.
STFC-RAL-CR03 R61: does it look like it?
STFC-RAL-CR03 R61: Okay? So yeah, I'll spend the next 50 min or so on the apps measurement. And then just briefly mention.
STFC-RAL-CR03 R61: let's see, an excellent one that worked on
STFC-RAL-CR03 R61: so very standard
STFC-RAL-CR03 R61: for
STFC-RAL-CR03 R61: kind of precision. Tt Bar measurement. This is EU channel. So one electron, one in the final state, 2 big projects essentially.
STFC-RAL-CR03 R61: But the key selection that we make on our
STFC-RAL-CR03 R61: ensemble of events is one of the invariant mass for reasons that should be obvious. So this we're trying to isolate this region of entitlement near threshold. So we applied our stringent cut on the invariant mass of the the Tt. Bar system in our city to define our signal region. So the signal region here.
STFC-RAL-CR03 R61: And so what this plot is showing you is just
STFC-RAL-CR03 R61: what this value of d.
STFC-RAL-CR03 R61: what value D takes when integrated between the production threshold and some upper bound, so that the the X axis, if you like it xordinate, is the upper bound on competing D between 340
STFC-RAL-CR03 R61: and this Africa. So
STFC-RAL-CR03 R61: if you move to something like 500
STFC-RAL-CR03 R61: TV as your signal engine
STFC-RAL-CR03 R61: see, the value of D is very close to this horizontal line. This horizontal line is what we want to stay below. This is the this is our minus on 3rd limit. I mentioned before. So kind of key experimental consideration here is
STFC-RAL-CR03 R61: having as tight an invariant mass window as possible, so that we can minimize this value of D
STFC-RAL-CR03 R61: to to make an observation.
STFC-RAL-CR03 R61: So a couple of comments about signal in the background. So
STFC-RAL-CR03 R61: models using very standard simulation tools for for the group. And I mentioned these in detail because we can discuss them later on. But the nominal methods is this, I think every part model interface to the Pta Park and shower.
STFC-RAL-CR03 R61: and we have a couple of alternatives, one where we change the the shower, which will be interesting in a few slides, time and another where we change the matrix element calculator
STFC-RAL-CR03 R61: with regards to backgrounds, all the backgrounds are estimated using simulation. I don't think it's that interesting to dwell on that, because purity on that. Just through the selections that I mentioned
STFC-RAL-CR03 R61: all the backgrounds of simulation other than this big left on
STFC-RAL-CR03 R61: background, which is scaled by some data driven factor. So those are the kind of experimental
STFC-RAL-CR03 R61: and experimental TV tips. And yeah, you can see this. This is the observable where this is the business plus 5
STFC-RAL-CR03 R61: at the
STFC-RAL-CR03 R61: a reconstruction. That was, we measure in the detector. You can see it nicely. Very good purity of Tt. Bar.
STFC-RAL-CR03 R61: So something that's pretty important in all of this.
STFC-RAL-CR03 R61: for all of these spin measurements, and the limiting factor in this measurement is reconstruction of the tops. And why is that important? Well.
STFC-RAL-CR03 R61: I said, in passing, is related. You have to boost into the you have to boost into the Tt Bar frame and then into the frames of the individual pops. So you need to know what those reference frames are
STFC-RAL-CR03 R61: before. That you need.
STFC-RAL-CR03 R61: you know, to reconstruct the kinematics of the docs.
STFC-RAL-CR03 R61: It's not all that easy to do, because in the style atomic channel. We have 2 neutrinos, obviously undetected by the Alice detector. So
STFC-RAL-CR03 R61: like this is an under constraint system, and we can't.
STFC-RAL-CR03 R61: S, we can estimate. But we've got to know exactly what the kinematics of the talks are.
STFC-RAL-CR03 R61: 7 techniques exist. Do this one we use is called the ellipse method.
STFC-RAL-CR03 R61: I don't really understand what the ellipse method is doing, but it to say in a sentence, is some kind of geometric technique where you take all these equations of constraint by assuming a mass at the top of the W. And you pose
STFC-RAL-CR03 R61: your reconstruction problem is
STFC-RAL-CR03 R61: well. The kinematics of the w defines some kind of ellipsoids in some space, and then from the intersection of these ellipses you can solve to give you the kinematics of the neutrinos.
STFC-RAL-CR03 R61: and then work out the top candidates from that. So
STFC-RAL-CR03 R61: the point is that this is a technique
STFC-RAL-CR03 R61: that
STFC-RAL-CR03 R61: is understood, and it's been around for a number of years in cases where it doesn't work, where you get complex solutions.
STFC-RAL-CR03 R61: we employ a couple of other alternative techniques. Neutrino waiter, for example, was used historically for spin measurements, and it's a numerical way of solving the same problem. So the key idea here is that we use
STFC-RAL-CR03 R61: techniques that are tried in Texas and reconstructed the kinematics.
STFC-RAL-CR03 R61: So make a
STFC-RAL-CR03 R61: comparison repo level of the data
STFC-RAL-CR03 R61: to the various one problem predictions here. And you can see that this
STFC-RAL-CR03 R61: flats that this classified distribution is slightly distorted detector effects. It's not that flat
STFC-RAL-CR03 R61: diagonal line that I was expecting it. This is something that's going to be obvious. But we're gonna have to correct for those detector effects. Well, what I want to highlight on the middle part of here is that this is the this is the value of T,
STFC-RAL-CR03 R61: which was minus 1 3.rd The the average of this distribution, and then
STFC-RAL-CR03 R61: point we want to make is that the 3 points here 3 predictions are in some level of tension, if you like, with themselves and with the data point. So this is interesting that even that
STFC-RAL-CR03 R61: detector level, if you like, what we measure before we do any correction to
STFC-RAL-CR03 R61: deconvolute those detector effects that there is some
STFC-RAL-CR03 R61: discrepancy between the data and between the 3 predictions. And that's that's something that we can import.
STFC-RAL-CR03 R61: so just mentioned that.
STFC-RAL-CR03 R61: there's distortion from the detector, so we need to undo them. And then, Principal, one would do something like unfolding. To do that you could unfold this
STFC-RAL-CR03 R61: plus by distribution
STFC-RAL-CR03 R61: to alpha level and then extract feed from that. But this turned out to be very difficult. I'm not going to with that detail other than to say that because this region of empty bar faces so narrow we couldn't do that, unfolding in an unbiased way. So instead, what we do is we effectively
STFC-RAL-CR03 R61: unfold or correct this single value of D. So this is maybe a study.
STFC-RAL-CR03 R61: maybe more old fashioned techniques, uses the calibration curve. So
STFC-RAL-CR03 R61: basically, you just
STFC-RAL-CR03 R61: generate different hypotheses of what this D value looks like at a truth level and a detective level.
STFC-RAL-CR03 R61: And then parameterize the relationship.
STFC-RAL-CR03 R61: Interpolate between the various hypotheses. Just give you some functional form which you can map back from. So it's a 0 dimensional one form.
STFC-RAL-CR03 R61: if you like.
STFC-RAL-CR03 R61: The tricky part here is that
STFC-RAL-CR03 R61: changing? The hypothesis is is challenging because this goes back to what I said right before. Entanglement is some of a baked right into the theory
STFC-RAL-CR03 R61: from the from the ground up. So it's not like.
STFC-RAL-CR03 R61: like, you know, the top mass, or something like that, where you can just change the value of the top mass in your input power to your Monte Carlo generator.
STFC-RAL-CR03 R61: It's just how do you change like the level of entanglement in in nature. That's
STFC-RAL-CR03 R61: it's not trivial. It's not something you can input your mind in parallel
STFC-RAL-CR03 R61: baked into the quantum mechanics in which the field theories built last time was built on top of that, and amplitudes are built on top of that. So
STFC-RAL-CR03 R61: this is something that is, you have to be a little bit creative about. And so the way that we did this was just some re waiting for the simulation. So you buy an event by event, re waiting some some function by some multiplicative way. This function is a function of the kinematics and some scaling ground that we can control. So here's
STFC-RAL-CR03 R61: plus 5 year proof and simulation.
STFC-RAL-CR03 R61: This is just showing that if you reweight.
STFC-RAL-CR03 R61: apply this free weighting, you can change the slope of this distribution without bringing in any kind of higher order effects. So applying this reweighting, which changes the slope, but it changes the value of D linear.
STFC-RAL-CR03 R61: So this is how we generate, instead of hypothesis, just reweight simulation, using a specific functional form, such that distribution remains linear.
STFC-RAL-CR03 R61: And then that's how we generate these alternative hypotheses, as I show with the red dots here
STFC-RAL-CR03 R61: terms of our systematics
STFC-RAL-CR03 R61: so per source of systematic. We build a independent calibration, curve
STFC-RAL-CR03 R61: your your independent calibration curve. Then you combine all the systematics to get some kind of nominal calibration curve certainty, band, English and map I measure D here I invert
STFC-RAL-CR03 R61: functional 4 numbers curve, and then I have my truth level
STFC-RAL-CR03 R61: a bit deep.
STFC-RAL-CR03 R61: And so here is the calibration curve.
STFC-RAL-CR03 R61: the red dot. Here is a prediction from simulation. You actually see that the data points the black.is lower than the prediction. So this was somewhat of a surprise sort of saying that there's a higher level of in the data that was predicted by a Syms.
STFC-RAL-CR03 R61: So then we can map this
STFC-RAL-CR03 R61: like a team
STFC-RAL-CR03 R61: measure, take the level back to truth as I just discussed.
STFC-RAL-CR03 R61: And here are the results here. So this is the the main, the money block for this particular analysis.
STFC-RAL-CR03 R61: And so I'll discuss this in a little bit of detail.
STFC-RAL-CR03 R61: maybe starting with these validations. So these were 2 other regions that we could find
STFC-RAL-CR03 R61: orthogonal to the signal region, if you like, designed to just show that the method is working and that we can report the expected behavior in this entanglement. Parameters, as I said, as you move to higher values of
STFC-RAL-CR03 R61: Mtt. Bar.
STFC-RAL-CR03 R61: they said, at the time of this weekend, ignoring the
STFC-RAL-CR03 R61: I must.
STFC-RAL-CR03 R61: It's been tripped apart here. So this is
STFC-RAL-CR03 R61: what we find is that the level of entitlement
STFC-RAL-CR03 R61: decreases, or the value of D
STFC-RAL-CR03 R61: decreases or increases, decreases in magnitude
STFC-RAL-CR03 R61: as one looks in these validation regions, such that
STFC-RAL-CR03 R61: in both
STFC-RAL-CR03 R61: is actually above the level that we constitute in tandem, in the system.
STFC-RAL-CR03 R61: And importantly, the data and the 2, the predictions here, just 2 predictions at this point, and the end of the agreement between
STFC-RAL-CR03 R61: each other and the data is fairly strong.
STFC-RAL-CR03 R61: But in the signal region
STFC-RAL-CR03 R61: well, I was immediately going to discussing the problems here. But the main point is that we did observe in Tampa with the
STFC-RAL-CR03 R61: 5 over 5 signal confidence here. So this block can
STFC-RAL-CR03 R61: data point is well below the entanglement limits here.
STFC-RAL-CR03 R61: And so this was constituted the 1st nation of them at the end scene. But yeah, I think it's more interesting to discuss
STFC-RAL-CR03 R61: kind of discrepancy between 6, just as I showed you a few slides ago at the sector level. There's some disagreement between the predictions, and there's some disagreement between them and the the data itself.
STFC-RAL-CR03 R61: So why are you saying they agree
STFC-RAL-CR03 R61: in the VR region? Disagree in the Sr. Region, given that no errors.
STFC-RAL-CR03 R61: But there's an error on the average of the predictions.
STFC-RAL-CR03 R61: I suppose there will be a an error on the
STFC-RAL-CR03 R61: okay. So I just understand what you're saying vanishingly small. What I'm saying is that the
STFC-RAL-CR03 R61: the overlap, or how close the points are together with symmetric, and says that they're very close here, you know within the
STFC-RAL-CR03 R61: uncertainty on the data point
STFC-RAL-CR03 R61: he flew. But you said it's the way you phrased, confused.
STFC-RAL-CR03 R61: got it
STFC-RAL-CR03 R61: right. But I I think the point is obvious from the club that
STFC-RAL-CR03 R61: variation perfectly. See here, some kind of discrepancy is not visible here. So something's going on with the modeling
STFC-RAL-CR03 R61: or the data in this single region that is happening happening in the validation. I think that's that's fair. You know what the error is on the simulation.
STFC-RAL-CR03 R61: but an error on the simulation is.
STFC-RAL-CR03 R61: I'm actually small project as well.
STFC-RAL-CR03 R61: So I think that this is what we present.
STFC-RAL-CR03 R61: and that is the conclusion that we're drawing
STFC-RAL-CR03 R61: point. I want to make. Here is the.
STFC-RAL-CR03 R61: There are 2, for example, lines here correspond to this
STFC-RAL-CR03 R61: and this minus 1 3rd limit, and this second, because
STFC-RAL-CR03 R61: what we did in the end is we didn't map back to partial level. You map back to article level.
STFC-RAL-CR03 R61: And this is because we found that there are very large differences between the Pythia and Harry
STFC-RAL-CR03 R61: Park and showers. This was driving an absolutely enormous
STFC-RAL-CR03 R61: you like showering inside or something.
STFC-RAL-CR03 R61: So she really killed.
STFC-RAL-CR03 R61: So instead of mapping the the data point back part of the level, we mapped it back to part of the level.
STFC-RAL-CR03 R61: and then we might have to
STFC-RAL-CR03 R61: this minus 1 3rd limit through to particle level. As well do that for the Pythia and the harrowing case. So there's actually 2 limits here, one corresponding to
STFC-RAL-CR03 R61: this minus 1 3rd
STFC-RAL-CR03 R61: partial level, using pity up and one using carriage. So that's why there are 2 horizontal banks there. So
STFC-RAL-CR03 R61: yeah, just a slight subtle view on that point. The Zoomian uncertainty bound around India
STFC-RAL-CR03 R61: prediction. Because
STFC-RAL-CR03 R61: that's for Atlas build our simulation model
STFC-RAL-CR03 R61: around for our uncertainty model around. So yeah, we don't include an uncertainty band on the Heritage
STFC-RAL-CR03 R61: git. So you know, technicality.
STFC-RAL-CR03 R61: this is just explaining why particle level, so pointless here. There's no difference between the inherent partial level, and this caused by distribution, but a large difference, a particle level, so that that large difference is driving
STFC-RAL-CR03 R61: would drive the large uncertainty, if not back to part of that.
STFC-RAL-CR03 R61: This is something that people are investigating
STFC-RAL-CR03 R61: really is to do with the the ordering parameter in the shower. So one of these is a dipole shower, the other shower. It seems that in this specific region of base space
STFC-RAL-CR03 R61: they're not
STFC-RAL-CR03 R61: in as good agreement as one would perhaps do
STFC-RAL-CR03 R61: big comment on systematics.
STFC-RAL-CR03 R61: as is true for many precision top measurements, the the modeling dominates, and in particular this pop decay is the largest
STFC-RAL-CR03 R61: systematic uncertainty. So this is the propagation of the spin information through the decay chain depending which technology which software you use to decay top parts in the simulations.
STFC-RAL-CR03 R61: So couple of common questions that we get is, you know how reliable are the simulation predictions here. They
STFC-RAL-CR03 R61: we can disagree on that. But I'm saying that there's some disagreement between simulation predictions and what we see in the data.
STFC-RAL-CR03 R61: And so
STFC-RAL-CR03 R61: what we're saying here is that there's something lacking in
STFC-RAL-CR03 R61: the simulation. I'm not trying to claim that there's a stronger level of entanglement than
STFC-RAL-CR03 R61: in nature trying to say, trying to make it play.
STFC-RAL-CR03 R61: and assuming that the level of entanglement in the simulation is less than it should be, because of
STFC-RAL-CR03 R61: lack of particular effects included in that simulation, so high order and
STFC-RAL-CR03 R61: an extra week effects that kind of thing. And yeah, I'll show it on the side. So
STFC-RAL-CR03 R61: the problem on the left is showing
STFC-RAL-CR03 R61: an increase in the Td. Bar Cross section very close to the production threshold. When you have, when you include this next leading order like 3 corrections, and these are not included in the nominal Atlas
STFC-RAL-CR03 R61: simulation.
STFC-RAL-CR03 R61: so it could be an enhancement.
STFC-RAL-CR03 R61: original aspect of the cross section that could lead to changing the levels of entitlement in including these next leading order things.
STFC-RAL-CR03 R61: But more interestingly.
STFC-RAL-CR03 R61: something that has been considered
STFC-RAL-CR03 R61: to some extent the theoretical literature, but never actually measured or well
STFC-RAL-CR03 R61: observed until this year, really is this idea of a binding state in the in the Tdr system. So some kind of
STFC-RAL-CR03 R61: the podium
STFC-RAL-CR03 R61: pseudoscalar bound state that exists very close to the empty department, exists on the antique migrations. And the the point here is that what is enhanced is this
STFC-RAL-CR03 R61: spin singlet color singlet states exactly the maximally entangled states
STFC-RAL-CR03 R61: that that we're trying to measure people. So perhaps this
STFC-RAL-CR03 R61: not having this, the pony and this bound state modeling in our simulation is
STFC-RAL-CR03 R61: the contributing factors, the under prediction of entitlement in the simulation. And I just cite this. A,
STFC-RAL-CR03 R61: you know, studies from the start of this year.
STFC-RAL-CR03 R61: You consider some kind of
STFC-RAL-CR03 R61: just the model that's pulling in. Then you can see that the value of D, which is spotted on the y-axis on the bottom, the right
STFC-RAL-CR03 R61: can actually be driven down
STFC-RAL-CR03 R61: as a function of the
STFC-RAL-CR03 R61: parameters of this model, so improving, some kind of bound state will drive down the value of D there and then we'll see how Cmsf happens in a minute.
STFC-RAL-CR03 R61: So kind of summary of the arguments here, just to come back to that again, so that the precision of this measurement sure doesn't depend strongly on the fact that there is some disagreement between the data and the simulation.
STFC-RAL-CR03 R61: and we see that the accuracy of the simulation is limited, because the park and showers seem to be doing different things. That's 1 thing, and there's also some missing effects.
STFC-RAL-CR03 R61: Probably most likely. This the podium effect in the in the simulation.
STFC-RAL-CR03 R61: So that's the the Atlas measurement.
STFC-RAL-CR03 R61: I just like to take a couple of slides to present the Cms argument, and then we'll maybe have some questions on on both.
STFC-RAL-CR03 R61: So Cns actually has 2 measurements in 10 books produced this year. 1st of all, in the dialectical channel which I'll talk about first, st which they reobserve
STFC-RAL-CR03 R61: fantastic. So now, both at the Cms. Service time in the special region.
STFC-RAL-CR03 R61: and then, more recently, Cms. Also brought out a measurement of
STFC-RAL-CR03 R61: entanglement in the electron plus jet channel, where they don't manage to achieve another observation in the threshold region. But they do in that high mass, spin Triplet region that I mentioned at the start.
STFC-RAL-CR03 R61: So the dialect on measurement can
STFC-RAL-CR03 R61: in in some sense we take it as a direct comparison between the office measurement. But I want to.
STFC-RAL-CR03 R61: I had a number of significant
STFC-RAL-CR03 R61: differences that one should be careful. We've been making to
STFC-RAL-CR03 R61: apples to apples a comparison.
STFC-RAL-CR03 R61: So the Powerpoint is that Cms only use 2016 data. So smaller data size and atlas, which uses the cool 1, 2 data set
STFC-RAL-CR03 R61: focus on the electromion channel where Cms. For specific reasons, use
STFC-RAL-CR03 R61: all the channels E and U as well.
STFC-RAL-CR03 R61: Their invariant mass window is is different. So I said that in Atlas we have this quite tiny to 380
STFC-RAL-CR03 R61: TV window
STFC-RAL-CR03 R61: Cms have a wider window up to 400 G, and presumably, if you look at the plot on the the right.
STFC-RAL-CR03 R61: The devalue is running across the X-axis in this case. So and the Sweden so something it looks stronger. It's around point 5 4.5 5. So
STFC-RAL-CR03 R61: what you immediately notice is the black lines that the black box, the data points are
STFC-RAL-CR03 R61: shifted. So it says, some level, less entanglement in this data set than there was in the Atmos data set. And I speculate that it's down to this 400 versus 382. So just
STFC-RAL-CR03 R61: including more events that are kind of washing out that
STFC-RAL-CR03 R61: spin singlet maximum entangled state.
STFC-RAL-CR03 R61: They also cut on this beta parameter just additionally to target this school and blue fusion, which is what the independent States created by.
STFC-RAL-CR03 R61: So, yeah, I think it's important to see that
STFC-RAL-CR03 R61: there's not a like. For, like completely comparison between Atlas and Cms. Here, despite them both making this 5 signal observation.
STFC-RAL-CR03 R61: and just to come back to the idea of plutonium.
STFC-RAL-CR03 R61: So once they must have done, is included some kind of landscape effects in in their simulation, so
STFC-RAL-CR03 R61: some not a a full calculation of the of this by mistake, but some kind of approximate model that's existed in the literature from some time that they've included in the modeling.
STFC-RAL-CR03 R61: And so what this is, what the 2 points are showing here, so the top is without the troponian modeling, and the bottom is with the troponian modeling.
STFC-RAL-CR03 R61: And so, again.
STFC-RAL-CR03 R61: if one can define it this way. The disagreement between the simulation and the data
STFC-RAL-CR03 R61: is lessons.
STFC-RAL-CR03 R61: Now, this one would say that it's compatible with the data
STFC-RAL-CR03 R61: when you include the podium model. So that seems to support the argument we made before that what was missing in the Atlas simulation was this bound State effect?
STFC-RAL-CR03 R61: If we move on to the single button
STFC-RAL-CR03 R61: measurement which I'm only going to mention very briefly.
STFC-RAL-CR03 R61: This is relatively new work, and it's not out in a paper yet. So it's somewhat difficult to
STFC-RAL-CR03 R61: pull out a lot of details from this, but this is instead of using a dialogue channel we're using Channel. So
STFC-RAL-CR03 R61: you don't have. You've only got one laptop, obviously. And what you're using is your down type jet. So from your other wdk, you take the down type jet, which actually has the same spin analyzing power. What that tells us is how.
STFC-RAL-CR03 R61: for for electrons mentioned this half an hour ago, there's a hundred percent correlation between the direction of your Lepton and the spin state of the top.
STFC-RAL-CR03 R61: That is also true for downtime jets. So what they're trying to do here somehow is take one electron, that's 1 spin analyzer for one top, the downpit jet from the other.
STFC-RAL-CR03 R61: Now, I mentioned how reconstruction is A is a challenge in this. In the Tt Bar
STFC-RAL-CR03 R61: case, so maybe slightly easier in the Latin plus jets case, because you have only one neutrino in the final state. But I put this up, because I think it's quite interesting to use this
STFC-RAL-CR03 R61: multivariate technique to reconstruct the top parts, which is.
STFC-RAL-CR03 R61: if one goes to the 1st kind of instance we've seen in within a
STFC-RAL-CR03 R61: thought
STFC-RAL-CR03 R61: working group or the the top sphere of using some kind of machine learning to reconstruct
STFC-RAL-CR03 R61: the top parts. And this is something that we will see a lot more. I predict over the coming months and years. So they're using this, your network technique to reconstruct talks. And then what we do is some simultaneous field likelihood to extract all the same parameters.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: the parameterizes it.
STFC-RAL-CR03 R61: Sigma Beta is the cross section, but it's also the sum seems like a strange choice of variable. But this thing at the top is the
STFC-RAL-CR03 R61: the full cross section which they expand as a function of this. This is the analogous formula, what I showed at at the start. So what we're doing is some pretty likelihood fit to Monte Carlo templates to extract these parameters. Q. Both inclusively and as a function of
STFC-RAL-CR03 R61: various kinematic security. Here, or just be clear, are the polarizations and correlations
STFC-RAL-CR03 R61: of of the tops.
STFC-RAL-CR03 R61: and they do this, as I said inclusively, and they also do this as a function of various kinematics.
STFC-RAL-CR03 R61: the entity bar of the system.
STFC-RAL-CR03 R61: and added that
STFC-RAL-CR03 R61: outside of the only angle between tops.
STFC-RAL-CR03 R61: So that's how this measurement was done. Contrast to to the Atlas one.
STFC-RAL-CR03 R61: Honest.
STFC-RAL-CR03 R61: I just wanted to highlight the the results here.
STFC-RAL-CR03 R61: So
STFC-RAL-CR03 R61: it's it's hard to say, for sure. But I, as far as I'm aware, that the precision of this measurements is dominated by the statistical uncertainty. We don't get a full breakdown of the uncertainties yet.
STFC-RAL-CR03 R61: But in the
STFC-RAL-CR03 R61: this threshold meeting they also have some systematic
STFC-RAL-CR03 R61: systematics of the leading source. I'm not sure entirely what that is, but the consequence of that is that in 11 plus yes, China, they're not able to make an observation of entanglement in this
STFC-RAL-CR03 R61: this low mass region, but they are able to make the 1st observation of retirement in this house.
STFC-RAL-CR03 R61: Yeah, so this this is good. You know, we've now seen entanglement in both areas of the phase space that was predicted.
STFC-RAL-CR03 R61: I flash this slide up. This is a bit of a controversial slide.
STFC-RAL-CR03 R61: and I'm not a fan of doing this, but I think the best explanation was to copy this later become the Cms.
STFC-RAL-CR03 R61: Lc. Seminar that we did
STFC-RAL-CR03 R61: so. The idea is that, can you? Just because
STFC-RAL-CR03 R61: if quantum entanglement made a big argument about this in my vibe, actually but quantum, this phenomenon of entanglement isn't really telling you
STFC-RAL-CR03 R61: much about the quantumness of your your system. It's what it's what we're actually always measuring. Here is separability of the desk as discussed at the start. So you can have.
STFC-RAL-CR03 R61: if you like, varying degrees of
STFC-RAL-CR03 R61: optimistic sort of various states. So you can have
STFC-RAL-CR03 R61: some level of entanglement in
STFC-RAL-CR03 R61: classical analogues. Really. So, what they're asking, here is, what is the maximum value of my entanglement, marker that can be explained by non quantum communication, by considering space like, or time, like separation of events, and they
STFC-RAL-CR03 R61: decided to find this.
STFC-RAL-CR03 R61: They have to be critical, and do some kind of template fit to that, and show
STFC-RAL-CR03 R61: are claiming that what they see
STFC-RAL-CR03 R61: is a level of observing tandem, and that cannot be explained by the classical slower than light exchange of information between these 2 particles, and this is kind of the extent of the information that is is given on this, and
STFC-RAL-CR03 R61: I think it's to to give a harvest perspective. On this. Some people are, are unsure of exactly what this is telling us, so that this is a an interpretation that makes sense because we haven't really seen the same space like time, like separation, and its application to
STFC-RAL-CR03 R61: entitlement in the in the literature.
STFC-RAL-CR03 R61: So I show this is this is a this is an additional.
STFC-RAL-CR03 R61: if you like interpretation the Cms are are making on this, but it's 1 that's not made in by the the atmosphere.
STFC-RAL-CR03 R61: So yeah, I think I'll just mention a couple of postscript ideas and then stop for questions. So the 1st is the
STFC-RAL-CR03 R61: really these measurements of
STFC-RAL-CR03 R61: created a quite diverse new subfield of of possible measurements. They had seen. People are really interested in doing things not just like measuring entanglement now, but there are a number of different analyses. I can say out there
STFC-RAL-CR03 R61: motivated by work from the female community.
STFC-RAL-CR03 R61: for example, freshly saying, You know, entanglement is not
STFC-RAL-CR03 R61: all the risk. And so you can. Actually, this would be like a hierarchy of these kind of correlation
STFC-RAL-CR03 R61: type statements. So not just measuring spin correlations. And then it's quantum entanglement. But one can measure a hierarchy of different related phenomena, and even make this.
STFC-RAL-CR03 R61: or in principle make statements on benefit tests, whether you can observe
STFC-RAL-CR03 R61: and bell test violation in Tt. Bar production and the literature, the theoretical literature. She disagrees about the precision in which you can make some statement about a bell violation in Tt. Bar production. So this is something that people are actively looking at, and particularly
STFC-RAL-CR03 R61: in the Bushland region. People will try to see if we can make some bad type tests
STFC-RAL-CR03 R61: in Tt bar production, and then we go beyond top parts, too. So wherever you can kind of get spin information out.
STFC-RAL-CR03 R61: there's many different ideas for what you can do. And so there's going to be a meeting in Oxford in a couple of weeks to discuss
STFC-RAL-CR03 R61: all the ideas that have bloomed out of this, doing the same thing with doing entanglement, bell type tests and piece of case, various different channels
STFC-RAL-CR03 R61: with with tiles also. So yeah, many of the things that people are looking at
STFC-RAL-CR03 R61: can use these quantum observables as a problem to constrain physics. So this is a simple slide to say that if you consider the standard model effective field theory. Introduce some effective operators
STFC-RAL-CR03 R61: into your model, some high dimensional ones, then you can alter the amounts of entanglement that you have.
STFC-RAL-CR03 R61: So this concurrence that I mentioned before is on the left.
STFC-RAL-CR03 R61: and you can see they're introducing some new interactions.
STFC-RAL-CR03 R61: Change the value of concurrence.
STFC-RAL-CR03 R61: This lambda to the minus, if you like, is the value of D, and you can see that it has a completely different shape to the rest of these spin observables. So the point here is that maybe
STFC-RAL-CR03 R61: if you didn't know anything about this quantum information side of things, you wouldn't use these available in your
STFC-RAL-CR03 R61: new physics fit in your eft global fit. But
STFC-RAL-CR03 R61: we're not really saying anything about the quantum nature of the
STFC-RAL-CR03 R61: standard model anymore. They were just using these as new observables to put constraints on possible new physics so kind of more traditional use, but using novel observables
STFC-RAL-CR03 R61: and finding some really exotic stuff.
STFC-RAL-CR03 R61: academics and fainting about.
STFC-RAL-CR03 R61: And when we do these traditional benefit tests or measurements between photons and electrons.
STFC-RAL-CR03 R61: those are stable particles.
STFC-RAL-CR03 R61: The top is interesting and unique because it decays in 10 to 25 seconds, so does the entanglement
STFC-RAL-CR03 R61: persist through the decay, and you measure the entanglement between a top and a W. For example. So this is something that people are thinking about. And finally.
STFC-RAL-CR03 R61: some people in the quantum information community are thinking, this is a new opportunity to try and test
STFC-RAL-CR03 R61: so-called more general
STFC-RAL-CR03 R61: theories beyond quantum mechanical theories and use. How the energy used for this in a way to test these theories at different energy regimes, from the kind of tests that are done in the standard lower energy table covers. So there's a whole slew of beyond quantum mechanics ideas out there. People are saying, maybe we can test these.
STFC-RAL-CR03 R61: So the conclusion here really is the
STFC-RAL-CR03 R61: what I presented. The main part of this talk is that 1st observation quantum entanglement at the Nhc, so this is the highest energy observation of this phenomenon of quantum entanglement ever 1st between 3 quarks.
STFC-RAL-CR03 R61: It's been
STFC-RAL-CR03 R61: framed by both apples. Cms. Now, at this point.
STFC-RAL-CR03 R61: And so
STFC-RAL-CR03 R61: yeah, couple of technical points to finish. Really, I showed you how the separability of the density matrix was what we were actually considering. Here we measure that through this D extracted that from an angular distribution
STFC-RAL-CR03 R61: it will have the Cms very standard diatonic Pt. Bar measurements. And then, finally.
STFC-RAL-CR03 R61: it's some remarks about the Stairponey and stuff that might be missing from our modeling history, including the Atlas study.
STFC-RAL-CR03 R61: And we saw the results a year ago. Clearly, there's something efficient in our modeling that will need to be included, namely, this funding contribution
STFC-RAL-CR03 R61: before we can have a better agreement between the data and the simulation. So with that I'll I'll close and attention. Welcome any questions, and report that this spooky action at a distance, as I said, called this phenomenon of quantum tandem is alive, and thank you very much.