EF03 Contributions
Doreen Wackeroth
DOREEN: Thank you very much. Yes. Okay. So, it's my pleasure to give a quick presentation on the activities of the top and heavy quark topical group. And this is, of course, put together with my coconvener, Reinhard Schwienhorst.
Okay. So, here is just an overview of all the topics we have discussed over the whole process. Of course, the main focus here is the top quark. Exploring the top quark, its properties. And it has many connections to other topical groups. Of course, today I will mostly talk about the mass of the top quark and electroweak top couplings. The role of rare processes and the potential and projection for studying those several collider options. And then there are other precision measurements we can do and explorations of the properties, spin correlation, we can look at new kinematic regime from the top. And as I mentioned, we have a lot of connections to other topical groups. One that is clear is, of course, the top mass in global fit. That is EF04. And also the top couplings in the EFT states that are going to be performed. And of course the role of top in PDF fits and also PDF uncertainties in the top quark mass. That is a study together with EF06. And we are not just concerned about the top quark, but other heavy quarks, button, cork and strange. And we had nice talks on colliders about charm and strange, and also running Bquark mass. Does last but not least, we are concerned about the status of predictions and prospects for theory improvements which are very important everywhere, of course, in this Snowmass process.
But also in the top quark because we will have beautiful, precise measurements. Many, many measurements we have from the LHC. And we will get more at the HLLHC. So, this is like what we just heard about the Higgs. The top is something we can explore with our collider options right now to very high precision. And that will be the starting point and, of course, what we want to discuss in the future.
So, today we decided not to present the contributed papers. I will mention them on these slides because they will all be presented in our parallel session. So, please tune in, in our parallel session if you would like to hear about the very nice studies that have been done in our group. What I will be what we decided to pick today to present to you are just some nice examples from the collaborations, ATLAS, CMS, ILC, CLC, muon collider. FCC reports, we picked a few examples of the precision potential for top quark physics from those reports.
And then, of course, here is the list of contributed papers and the different studies. A big focus was on topquark mass, as you can imagine. That's, of course, an important topic in our group. But also modeling uncertainties in rare processes. Heavy flavor PDFs. It's really a very rich spectrum that we are discussing in our group. So, all these talks are presented all these topics are presented in our parallel session. There are a few more papers in the making. They are coming up soon. So, some of them will present also here at the workshop.
And there was a other a recent talk so, just if you want to see more. Because this is really just a small snapshot of what we discussed over the past years. So, the highlight talk we gave at the Restart Workshop gives you even more information.
So, let me start with the topquark mass. As we all know, that is a parameter in the Standard Model you want to know as precisely as possible. The community is also working very hard both on the experimental and the theory side to understand what is it that we're measuring at the collider right now. And then how can we make a connection to the renormalized topquark mass in the seem. And here is a overview of all the many measurements that have been done so far at the LHC. We know about the top mass, at the Monte Carlo mass, at the uncertainty of 480 MeV right now. And we will have to discuss, and this will be extensively discussed in our report how to relate this Monte Carlo mass to the mass in the rare defined normalization scheme. And there are uncertainties attached that have to be carefully estimated just to get an idea what will be our capabilities to pin down the topquark mass, and when we say topquark mass what we are talking about.
There are studies. People are creative. And at the collider, to get the most out of it measuring the topquark mass. We will discuss that. And we will discuss measuring the topquark mass and what we measure in the uncertainties there.
Given the uncertainties involved in the definition of the Monte Carlo pass, there are also measurements now on the pole mass by comparing with high order calculations, the ttbar and other measures with higher order calculations and selects the pole mass and the welldefined scheme. And again here there are uncertainties involved which all have to be carefully disentangled and understood. And these are just examples from recent studies. I'm not claiming this is a full overview. This is a long story and we will try to disentangle all of this and show what we are able to do now and in the future. And again, there are contributed papers that will be presented here.
And then projections have been made for the HLLHC. So, again when you talk about the topquark mass, we have to talk about what has we are talking about, which measurements are we talking about? Here you can see examples to measure the Monte Carlo mass with a very high precision. So, statistically, 20 MeV, and then statistical uncertainty, and 170 MeV. And then pole mass less precise because of the attachment to want pole mass. And again, for measuring pole mass in ttbar, you need to look at the mass. There's an interesting result for Kidonakis, how higherorder corrections are at high energies. That shows we have to do the studies to look. I invite you to his parallel session to see what he found.
And then the important measurements, like at the plus and minus collider, the top mass from the ttbar production. This could be a beautiful measurement as you know. So, we can extract the welldefined threshold mass and also the top width and combined fit also in the coupling. So, this is there is a lot of potential here. And here are examples from the reports. How well we anticipate to be able to measure the topquark mass there and what are the uncertainties?
And again, there are theory uncertainties and you're going to relate the different masses you can measure, the top mass, the threshold mass, the pole mass, MSbar mass, jet mass, there are many names for the topquark mass and that has been has been studied what are the uncertainties there. And there is a new study on optimizing the scan at CLIC that will be reported in our parallel session.
And also the FCCee report gives a projection for the measurement of the topquark mass. Also, of course, from the special scan of what are the capabilities there. And there is, of course, information on the report submitted to the Snowmass process.
So far for the topquark mass, this will be a focus of our report. But then, of course, also the top electroweak couplings are important to pin down. And this is a close collaboration with EF04. We are not doing the fits. The EFT fits. But our group hopes to provide the information and projections for the topquark measurements that go into the fits. So, that's the relationship between the two groups. That will be a top that will highlight projections for top measurements. So, like, for instance, ttbar Z or tt, these are the measurements and how well they can pin down the measurements in the EFT interpretation.
Part of this is also again then the uncertainties with gauge bosons. And did Bevilacqua will have a talk in our parallel session also.
Then in terms of rare processes, we, again, one of the rare processes that will allow us to pin down the neutral couplings, electroweak couplings in the top. ttZ, for instance. That's new study in the HLLHC report on how well we can pin down the topquark operators. And just to give an example of the ranges of what we can do with the HL and LHC for one of those topquark operators in the HLLHC.
And for e+e colliders, here is just one example how well we will be able to do this PSEC left and righthand couplings of the z boson to the topquark. Taken from an earlier paper to highlight the capabilities. Here you see in blue the ILC capability to pin down these couplings compared to the FCCee and compared to the HLLHC and then the pink dots are just some models that give large deviations from the Standard Model.
These are, of course, electroweak couplings which will be a big part of our report to the show capabilities of the different collider options to pin down these couplings. But also what are the projections for the measurements that go into especially in the EFT fits. And you have seen this already for the Higgs sector.
I mean, this is, of course, something that just gives us a feeling for what can we learn from these future measurements in an EFT interpretation? So, we received this throughout I guess the Snowmass report. Also for the top you have the specific toprelated coefficiency and comparisons of ILC and HLLHC, how well they can pin down these couplings. As I was saying, in our group, concentrating on the input in these fits to present and be able to measure these crosssection differential distributions. A new study that was also done in our group is spin correlation as an input into the EFT fits. And then figuring out how well they help us to reduce the uncertainties here.
Thank you. So, this is a new study that was highlighted in the HLLHC report. It was spin correlation. Again, it's a property we want to understand well. And here is an example of projections from the HLLHC report. How well they can do to measuring the spin correlation fraction compared to what we already know at the LHC. And we have a new study. And also polarization of the topquark is studied in our will be studied in our report and there's a new study that will be in the top jet structure that will be presented in a parallel session.
Again, in terms of rare processes, that was also highlighted in the HLLHC report. Projection for measuring the four top cross sections. Making a discovery here for the top production and how well we can measure the cross sections. Here we can see the projection on the righthand side for the uncertainties. With different systemic uncertainty. The red curve gives you, for instance, and, of course, the dependence of the integrated luminosity that you can have 15 to 20% measurement uncertainty here for this after this discovery at the HLLHC. So, that will be also highlighted four top production as a place. And we can look at top contact interactions.
So, and that can be phrased in EFT coupling also in terms of compositeness of the top. So, this is a projection from HLLHC how well these EFT contact interaction operators can be pinned down. And then there has been also new studies for the muon collider. So, in the report that was submitted to the Snowmass process, topquark physics is interesting. Also, in the context of probing compositeness of the top. And here we gain just from having more energy available. As you can see, the last one of the possible ways, how we can have sensitivity on these operators connected to the top is the one that is connected to compositeness. And it increases this energy.
And you can see that there's also an interesting process, vector boson fusion, where after producing the Higgs ttbar, cross section is very large for high energy muon collider where they can be studied. I will say these studies are still in the beginning. So, what is the potential for topquark physics? There's a lot of room for more study as well.
And here I was saying top compositeness is an interesting property that we want to explore if it exists. And here you can see different projections for the ILC click muon collider. On the righthand side, you see, for instance, the red contribution is then going to include topquark compositeness as the additional signature at the muon collider. This is the red. And you see the exclusion limit in the plane parameter space. And then the different projections that have been studied in a recent paper by Banelli et al. And you can see the other 87 curve is a new study by CLIC. That belongs to the constrain on the scale divided by the square root of the CTT operator larger than 7.7 TeV. Here, again, energy helps to extend the reach.
So what about it brings me already to my last slide. That was giving a overview of the most recent result. There's much, much more that's been done in earlier studies that we will discuss on Wednesday afternoon when we discuss our report. We have a similar outline ready to show you that just showed us for the Higgs report. And then we would invite everybody to come and give input what we that we don't forget any important topic, of course. We have all contributed papers are invited to, of course, present a most important result. We already have commitments from several groups to do this in the report.
We invited experts to take charge. One of the dedicated sessions like the one on the topquark mass, the theory issues. There. Andre Hoang will help there is, Manfred Kraus will help with ttV production. We set up the people who have already contributed and also will help to get across the most important message for topquark physics and heavy quark physics. Thank you very much.
[ Applause ]
>> Okay. So, should we start again from Zoom? If there are questions?
ALESSANDRO: Yes. Thank you for the nice presentation. We have in fact a question from Dmitri to start.
>> Thank you for the nice presentation, Doreen. It might be more of a comment about what we discussed about Higgs action. What many of us are looking for for the Snowmass is to provide benchmark for the study of the topquark various properties. And understand how HLLHC will contribute. So, combinations between ATLAS and Snowmass, and various parameters for progress and production will be very, very useful. Updates in comparison with the European Strategy. Because that sort of sets the threshold for other proposals to mention. hopefully did much better.
DOREEN: Thank you. Yes, that's a good comment. And, of course, we are working on this Reinhard being the coconvener, as you can imagine, he's very well aware of what's going on in CMS and ATLAS. Thank you.
>> Do we have questions or comments from the audience? Go first. Run up there.
>> Just maybe a quick question, I think it was 12, 11, 13. Something like no. Here. And so, here is an example you went through where a set of what is showed is I think linear collider and FCCee seems to have a qualitative difference in terms of relative strength in the two axis in terms of constraining. So, I don't want to get too detailed there. There's probably plenty of room in the parallel session. But is this like a genuine difference that is understood? Something that would be looked at?
DOREEN: So, this is discussed in the paper by that is cited here. I don't remember from the top of my head
>> Don't worry. I was curious.
DOREEN: This is just an example because I tried to find something more recent. This was the recent one I could find that was cited in the report that was submitted here. But it is definitely something we want to solicit input from the authors so that we present as clearly as possible. Yes. Thank you.
>> Just to give another answer to this question. The comparison of ILC and FCCee is a little it's a little complicated. Because FCCee doesn't ignores the experimental systemics. Whereas ours includes an estimate of experimental systemics. So, you really have to go into detail. But basically, it's the same sensitivity. Except for the fact that with FCCee you see a strong correlation between the two quantities you want to measure. And breaking that correlation is beam polarization. If you have beam polarization, as you see, you can eliminate that correlation and you just have the intrinsic ability to measure each coupling.
DOREEN: Thank you, Michael.
ALESSANDRO: We have a question from Patrick in Zoom.
>> Yes.
>> Finally I managed to unmute myself. Since my name is on the slide, I can maybe bring a more accurate than the one that was just brought.
The observables at the FCCee and the Hadron collider are totally different from this plot. The linear collider makes use of the initial state polarization. While the FCCee makes use of the final state polarization of the tops. Which makes the analysis completely different. Also the FCCee analysis is limited here to just the lepton observability in one of the top. Nothing about the quarks. So, there is a lot of room for improvement there. Which will reduce the reduce the collaboration mentioned by Michael. So, I wouldn't say it's due to the polarization. The initial set polarization of the final set polarization that we have this correlation. It's due to the limited number of observable that we use. And finally, to answer the question of systemics, this this analysis is actually not dominated by systemics because it's only the momentum and the angular distribution of the leptons which is fully simulated here and there was no systemics that would that would reserve the statistical uncertainty.
>> Just a quick followup, then. I wonder in presenting these type of results, does it really make sense to write the FCCee and LHC, or try to label those as different techniques and explain them in the test that to reference the proper studies from the correct collaboration to give credit?
>> I think there is a difference here. A qualitative difference. The fact that there is no initial state polarization at the FCCee makes the use of the final state polarization much more efficient.
So, it's intrinsic. If the linear collider wanted to have this kind of performance, it would have to give up on the initial state polarization.
>> Okay. Thank you.
DOREEN: Thank you, Patrick. And it's great that you connected. So, you will definitely be contacted by us for this part.
>> Even if I were not connected, I can be contacted.
>> Do we have more comments or questions from people here? Michael?
>> So, I wanted to ask a different question. Which is the treatment of top partners and ttbar resonances. So, this is one of the big opportunities, obviously, for HLLHC to extend their reach in these states which appear more or less generically in composite models of the Higgs Boson and the topquark. Is that being covered by you? Or is that being covered by someone in this group? And it's obviously connected because, for example, ttbar resonances basically provide the Schannel structure of these composite operators.
DOREEN: Yes.
>> That you're interested in. How are you treating that?
DOREEN: Our understanding is that we initially in the beginning talks about ttbar resonances and moved on to BSM topical groups. But, of course, we have to make sure that all the topics that are covered in several groups that they're presented somewhere.
So, for that part, I'm glad that you mentioned that, we will have to talk to the topical group conveners and say what are you planning to cover there? And that's this workshop, what I'm hoping to hear and discuss. Shall it be in our section or the BSM section? For the moment, we're assuming it's in the BSM section. But that has to be checked. It has to be covered somewhere. That's for sure. Thank you.
>> Yeah. And along the same lines of talking and coordinating, you were mentioning, you know, the EFT studies that you have shown. That you're also probably looking at models and seeing how they project or different operators. And this talk's a little bit to the inverse problems. That Caterina was talking about. So, pick models, and the two of you some of the models are also the ones coming up in your discussion.
DOREEN: Yes. We need to do that. We haven't done this yet. But again, here, it's great.
>> Alessandro, do you have more questions on Zoom?
ALESSANDRO: No, we have no more there's one that just came up now. You have a question, Yuan?
>> Yes. No, in fact since Michael was asking about the the new physics. And in this top group we worked out a study related to the booster talk. So, with that in mind, if there's a new resonance state in the ttbar production, then here is a new kind of the experimental observable that can help to pull of these new resonant states. For example with the coupling of this new resonant state to this ttbar system. And that will affect in principle affect the top. In a boost system. So, then we construct and the new experimental observable which was now known before. As much as we know about it. As an angle correlation. And again, the goal of that is to use that to help probing these new resonant state in the ttbar production and also discriminate with the different kind of the new particles in the different in various new physics models.
>> Thank you. So, if I don't see more questions from the audience, Alessandro, I think we can move to the next speaker unless you have something else on Zoom.
ALESSANDRO: No. Thank you Doreen, again.
[ Applause ]