EF03 Report Discussion
>> Okay, now, so turning to the discussion of the report. So we thought we just put up a very, very, rough draft. This is a rough draft of what we are working on, and some of the points were already made on Monday to highlight this talk, but let's see, Reinhard will share with us. 
REINHARD: I've shared them, do you see the slides? 
>> There they are. Is there  there are so many screens here. Just, okay. Yes, so, so we are in the process of cross-organising all the wonderful work that has been done, and before, of course, this Snowmass, and doing this Snowmass process. In the very beginning, we had started with some questions that we phrased, what we would like to address in this study, and then of course now we can go back and do a reality check and see what we are able to do, so of course the first thing living in an era of a top-quark factory, that is something we really would like to emphasise in this report that we're now in the lucky situation, 27 years after the discovery of the top-quark, we have a factory where they can do extremely high-precision studies of all aspects of top-quark s. That is something that hopefully we will be able to get across in this report by emphasising what is done now, and at the HL-LHC, and on the ... side. As with everybody, that will be the starting point to discuss what is the future for top quarks, and also other heavy flavours. How with the full explores of the heaviest known element particle help elucidate the Higgs sector and inform about possible physics beyond the SM. We know that the top-quark is intertwined with the Higgs sector so that is the overarching topic. And then, of course, what is the optimal way to guarantee that we take full advantage of the physics potential of top-quark studies at different colliders running different scenarios, and so on? I won't read all of this. But we had some questions, and hopefully we will be able to address them. So, in one, we start in the report with the properties. And of course, the important one, top-quark mass. We discussed this on Monday. What is the top-quark mass? You measure different observables, and how is it defined and what are the uncertainties from the theory point of view? And we were agreed to help with this section, Andre Hoang agreed to help us in this section. From the theory side, we have understood a lot but there is still a lot of work to be done to take full advantage of precise measurement, and what is the ultimate precision we can aim for from the theory side. And then of course the experimental aspect will be that we go over the HL-LHC projections, so all the different collider scenarios, and, of course, they are also severe limitations there that we need to point out and see what is needed to get to that precision. So we were thinking of having tables, of course, right, so that in after all this discussion of the details, please don't look at the details of the table yet. But, of course, we would love the comparison tables of top-quark measurements and only uncertainties, and then maybe a summary table, but I think - we think it is also important to point out the different origins of the uncertainties where we can expect improvements, where should they come from, theory on the experimental side, and so on. So we will have several tables on that and maybe an overview table, is the main message. And then, we discussed doing Snowmass, and, of course, in Snowmass, there are many new ideas about how to do top mass measurements. We have referred to them here in the parallel session. We've heard examples in the plenary sessions from booster tops, so there are many ideas that we would also like to highlight. Okay. Of course, the contributed papers will also be highlighted, so we won't go over this here, and then after the top top mass, we will discuss the widths in terms of e+e- colliders mainly because the line shape fits, combined fits of top mass widths, and coupling, and so on. Reinhard, would you go to the next topic? These are these other tables. Then we go into this whole rich world of top-quark production processes. You just have seen many of them in the table that Víctor showed us that are input to the EFT studies but also of interest on their own. So measuring electro weak couplings on the top, in TTV, TW and looking at single-top production and hopefully having projections what we expect for - what kind of work needs to be done to take full advantage of the HL-LHC and what are the projections for the future, because for the top-quark, right, we have to wait until we get back to top-quark as a going above the production threshold, so we have to really make sure that we take full advantage what we are going to have as the HL-LHC and see how can you improve on this in the future. One place is of course for top production. That one example of a rare process where there is a discovery in waiting, so we will maybe have a discovery. And then what can we learn from in in the context of top operators, and there has been new studies about the sensitivity on those operators which we will highlight in the different collider option, and then we have on here, a study again tables, comparing the different collider options, how well we can do in terms of CCT, the top operator, so we would like to have these kinds of examples, when it is not covered in EF04 concentrating on the global fit, the EF fit which we highlighted this year. Okay, maybe in this context also discuss the connection to Higgs compositeness and - we presented this as one of the highlights on Monday. So we will go here too. Then we go to - we have a collaboration going on with the EF06 so we have to discuss with them how much we say here in terms of how top-quark observers can help us to re strain - we will have them in the audience here, how we divide this up, which information goes where but it has to be prominently covered somewhere, and we will discuss where. And then top quark electrocouplings, we talked about this, not just in terms of E - talking about the couplings of the top to the Z and so on. What can we do with the different options ? Looking at boosted top s capabilities here, so we had examples today in our session, how we can use as an angle correlations to a sensitive ... for new physics becomes for instance. We should also point out we are not include any direct new physics signatures here, so we will make sure that nothing gets lost, but those things are covered in the topics. Then of course we didn't have any specific work on flavour-changing neutron ... but that is something we would like to highlight too. Study have been done about different collider scenarios to both those, and they include an overview there too. And then we had a number of studies, and you heard already today how for instance bottom-quark production plus and minus can help in constraining some of the EFT operators, so they had studies on charm quark production, so those will go here in our report. This is the non-top contribution that we will cover. So I think are we at the end? Is this what we have right now? Yes, okay. So these are the topics we would like to cover, and now we would like to open for discussion suggestions, offers to help. Yes? Yes? Sarah, please go ahead. 
>> There is a [inaudible]. Yes, of course, I'm sorry. Sorry, I meant the outside the reports from the collaboration. But you're completely right, Sarah, yes. So that is actually what we rely on, right, so just highlight be those sections in the other report as results of course. Thank you. There was another comment, Alessandro? 
>> Thank you, on the definition of a top mass, in the yellow report, High Lumi LHC for electroweak and top, wrote two pages in agreement with the several people, it was longly debated how to write it, what is the definition of a top mass, and the very definitions, so maybe we can start from that. 
>> We're not reinventing the wheel. 
>> There was lots of discussion with people with different agreements, and we distilled the agreement to put down in word. 
>> I'm sure Andre got to the section as well. 
>> He was involved, I think. 
>> I would make our statement a little controversial. It's great that people are talking and this is an active field of discussion, exactly what the - it exactly what the differences is between the different definitions. I think Andre has a slightly different approach than Paolo, so it is good that we have Andre giving his two pages for our report and not Paolo. 
>> Which we will share publicly of course for feedback, and then ... 
>> As Alessandro pointed out, they discussed this in multiple forums multiple times, so there are not very big differences. 
>> Yes, but I think we still want to cover it in our report, right? It is such an important topic. Just don't want to just point to the yellow report. I'm sorry? 
>> A question on Zoom from Chip. 
>> Shall we do that first? Let's do the question from Chip first. 
>> This is kind of a general comment, but I think it figures into the discussion of the document, in some circular way. I'm pretty convinced that in 2013, we were conservative in our estimates what the prospects would be for luminosity, we went to 3,000, as I recall, and you're talking on Monday about the top-quark mass status just hit me beside the head on that subject because in many ways, we've already reached the limits that we thought were going to be high-luminosity limits. We've reached them now. And I wonder just for the Snowmass brand, because we tend to do this conservatively anyway, if it might be worthwhile maybe even interesting, and like I say, useful for the brand, that we compare where we are now after Run 2, especially with the LHC, to what we predicted we would be doing in 2013. I believe in almost every case, we will find that we were over ly conservative, which is our nature, but I think it's useful to point that out, maybe even in some innumerated way, or somewhere in actually each country frontier document that points out, here's what we said we would do, here's what we said we would do, and here's what we did, and now here's what we say we're going to do the next chunk because it adds legitimacy to the way that we do these processes. 
>> That's an excellent point. I think, Reinhard, did you put the point in when you go back to our questions? Wasn't it the last point you put? 
>> I think.
>> Let's go there. Yes. Is it the possible to receive - yes. The last point? 
>> Exactly. Exactly. So, when I saw it initially, because it's on page 2, you see it is the last bullet on this page, which is exactly that. How realistic are we and we can make an argument from being realistic based on where we are today compared to the original Snowmass 2013 prediction. 
>> I think that would be useful in the Snowmass report, especially on the energy frontier, to the degree that we're not wild-eyed when we do these projections in our field. 
>> Excellent point, yes. Yes. And we're lucky the situation is the top that we can do this. We can look back and see how well did we do. Okay. Very good point. Any other questions on Zoom before we continue here? Not yet? 
>> Now, no other questions. 
>> Then, please go ahead. 
>> Just would like to continue the discussion of the top-quark mass. Of course, if you look back ten years, so, by now, we understand what top mass is in theory much better, right? For example, when we talk about very precise measurements, we have to compare top mass measurement in e+e- versus the hidden measurements in there, and the definitions, but also the inputs from QCD that go into these measurements would be very different. I think it would be useful to show what we know by now, a one- or two-page summary precisely on the issue of the top mass how to understand the concepts and where to make the progress compared to ten years ago. The other question that comment, on  is considering this dependence on the PDFs that you mentioned, within the EF06 group, we are looking for a wish list of various measurements that may be sensitive to the PDF uncertainty, into the PDFs and obviously you mentioned that while, several of these measurements in the top physics are clearly very important, and so what would be very valuable for us is to have some kind of, again, list of requests, so, for example, now, what I have in mind is that when we talk about the PDF dependence, we often would refer to the ... from the Higgs working group which show the accuracy of the measurements of various Higgs couplings, depending on the optimistic and pessimistic projection for PDFs, or other uncertainties. We want to have more like this, and so actually could help you with providing let's say two scenarios for PDFs that could be folded into this, well, projections, for example, for the measurements of the couplings, et cetera. So, again, this is a request to your group and also to other groups, if you can think about this kind of presentation where we could provide two models for the PDFs, and you could play with them and see what kind of projections you get, clearly, we would have people in our group who would be interested to help you out with those. 
>> Just in practice, for instance on the example of the top mass measurement, the HL-LHC, there is an assumption in the PDF answer there? So that is one point, right? So where £introduce an uncertainty, and we can presume pessimistic and optimistic. But then we also had the session, an intense session, on using top observables in your input in PDF fits and how much do they contain, for instance, the gluon PDF. That part, does it go in your report? 
>> It could go in your report, but for us it's important to emphasise what the studies of £that we do the affect the projection in other groups, like, for example, ... 
>> That's why we thought where it applies always to highlight the difference sources of uncertainty, and among them is a PDF, right? So, that should be always clearly stated. 
>> Right, we just had that this morning, right? We can use the top pair production plus jet to measure the top mass very precisely but the largest uncertainty in that distribution is the PDF uncertainty so we could turn around and use top pair plus jet production to restrain PDFs further. I would say optimistically depending on which variable you look at both  each process goes in both directions. 
>> You can - do the analysis in a different way and you - it is difficult for you to do in EF03 but we have some tools to help you out with that as well. 
>> So let's keep this in mind when we get to the writing that we do this the right way. Thank you. 
>> There is a follow-up on Zoom presumably by Maria? 
>> Thank you for citing this. I mean, actually, we were also thinking, pointing this live, because we were also thinking this is a quicker process, sensitive to PDF large X but in the analysis that one should think about an analysis where you correlate, I mean, at the same time, you extract the top mass in PDF but because there is a correlation between the two. And so this is an important point. 
>> Yes, Maria. 
>> You have to take into account [inaudible] have to be stuck all together. 
>> Hmm-hmm. Yes. There are studies where people have done the simultaneous fits on all three. 
>> I know this becomes more complicated, but let's say the future, I am thinking to the future at instruction of the top core mass at my - try also the PDF the end, and the - but especially PDF because we saw it very - there is a region of this distribution that is very sensitive, yes. Thanks. 
>> Thank you very much  thank you, Maria. Good point. Okay. Any other questions or suggestions? Okay. We should emphasise in our report, is there at least anything on Zoom? 
>> So far no, but maybe I shall repeat the discussion you and I had because we separated, with well, I was in favour of separating the bottom quark, the heavy flavour and have that appear in a separate section. As we just heard from Víctor, this is all part of a global fit so maybe it should all be described in the same section where that would make more sense. 
>> Yes, we can discuss this ... 
>> Yes. 
>> Pavel? 
>> Well, again, depending what you wish to do, because clearly there are in physics aspects in the channel production which are not the same in tt bar, right? And, well, there is some overlap but there will be issues that will require several pages of independent text. 
>> Because we're not just thinking in these processes of global EFT fits, so, I think they deserve separate attention. 
>> They deserve separate attention because it's complicated measurements. Also, what did I hear this morning? Multiple LO theory prediction s in differential distributions. 
>> Yes. Patrick? Over there? 
>> Interpretations through - in terms of what you learn about new physics, are you going to include anything other than like a zilch parameterisation for composite Higgs? Maybe this is a crossover? 
>> That is something we need to discuss with TPSM, how much we want to go into this in our, so do we just use an example to highlight the interpretation of these measurements where we can learn from it? Or do we do a full land scape so that we discussed the full landscape of possibilities? We have to see, right? 
>> This is something that we also have to think about for EF02 as well. At least the default for European strategy was just to say zilch even if it is not a model and wash your hands, but especially in the top sector when you try to build models, there are lots of different classes of how ... 
>> You can take this opportunity to be more inclusive here in that sense. It is important to highlight all these interesting physics that you can do with the top. The top, I don't know, Higgs gets a lot of attention but we can do top now! So, thank you for mentioning this, so we should talk and get all the interesting physics and models that can be studied in there. 
>> I mean, there was a lot of correlation, when you break off top, then you think about implicit favour assumption in terms of how this compositeness shows up, and things like that. 
>> We should have you there! Doing this right, if it is not covered anywhere else. Right. 
>> Just to add to that, I think for us, the attractiveness of compositeness in particular came up because that's something where top quarks become relevant in a muon collider, but you will have noticed nowhere in our table so far have we listed the muon collider because it is not useful to measure the top-quark mass to high precision. The composite at highest energies, that's something where the muon collider can really contribute, and that's why we wanted to have it is part of our write-up so we get a chance to write about muons. 
>> Any other questions or suggestions? On Zoom? 
>> I don't see any hands raised on Zoom. 
>> Well, it's a process, right, so we will share as soon as we have something more presentable there. And take note of the feedback we get here, and will get, and hopefully it will be an exciting report about top physics. 
>> Different people already asked me that question. We did not put this on the Indico yet because we don't think it's ready yet for public consumption. We want to show it here. You can see the Latex didn't compile quite right but we are hoping to share this and make it more organic. We are also asking other people to contribute to this so we will share the link with those people who will contribute, and then we can all work on this together and hopefully upload it to some Indico when we're ready for people to send comments. 
>> I wanted to ask you. Then you will share the overleaf, someone who is interested to comment or contribute will get in touch with you? 
>> Yes, they have to get in touch with us. We have control of the document, right? And so that - yes. Definitely. 
>> Like Wikipedia type, everyone can edit. 
>> We will continue to have meetings where we can make these things that have been brought up a topic, a dedicated topic where we hash out the details. Thank you. 
>> Chip is asking about an outline. We can probably produce that and put it on our wiki, for example. 
>> Yes, that we can do. Okay. Okay? Then we can close the session.
Thank you very much. Thank you very much for contributing, and we keep in touch. Of course. Thank you. [Applause]. 
>> Thank you, Reinhard. 
>> Thank you, Víctor for the talk. 
VÍCTOR MIRALLES: Thank you. Ciao. 
>> Bye-bye.