WEBVTT 1 00:00:00.000 --> 00:00:06.220 Sukanya Sinha: Ritaja, who will be speaking about new sustainable alternatives for 2 00:00:06.470 --> 00:00:11.689 Sukanya Sinha: feature colitis. So your timer will start and you will hear the jingle. 3 00:00:12.110 --> 00:00:13.030 Sukanya Sinha: Go ahead. 4 00:00:13.960 --> 00:00:15.210 Rhitaja Sengupta: Hello! Can you hear me? 5 00:00:17.430 --> 00:00:17.980 Sukanya Sinha: Yes. 6 00:00:18.520 --> 00:00:44.130 Rhitaja Sengupta: Yeah, Hello, everyone. Firstly, I would like to thank the organizers for giving me this opportunity to present our work as mentioned. I'll be talking about enhancing the light and weekly coupled new physics program at future colliders with sustainable alternatives. It is mostly along the lines of how to make the most out of the existing or future collider infrastructures. 7 00:00:44.650 --> 00:00:46.081 Rhitaja Sengupta: Let me begin with 8 00:00:47.200 --> 00:01:06.689 Rhitaja Sengupta: our goals in high energy physics. So after the Higgs boson discovery, we are, we have mostly a complete picture of the standard model of particle physics, but there are still many missing pieces, and one of our main goals is to find hint any hint of physics beyond the standard model in order to tie these missing pieces together. 9 00:01:07.270 --> 00:01:28.949 Rhitaja Sengupta: In doing so, when we explore the mass and the coupling strength, parameter space of new physics. The large mass and the higher coupling strength region is relatively more explored as compared to the weakly coupled light. New physics which is going to be a focus of our talk today. 10 00:01:29.220 --> 00:01:56.400 Rhitaja Sengupta: And when we talk about weakly coupled light, new physics, the obvious benchmark that comes to our mind are long lived particles because of weak couplings. They mostly have long lifetimes, such that they do not promptly decay. In colliders. They travel some distance, and then they decay, either giving us a secondary vertex inside the detector, or they can even decay outside the detector if they are light enough 11 00:01:57.040 --> 00:01:58.150 Rhitaja Sengupta: to be boosted. 12 00:01:59.596 --> 00:02:15.529 Rhitaja Sengupta: So the reasons for long lifetimes. They exist very much in our standard model. We have many long lived particles in standard model. So you have to have a suppressed Dk width to gain lifetimes, and these are also very well motivated in many Bsm. Models. 13 00:02:16.310 --> 00:02:28.729 Rhitaja Sengupta: Moving on this slide provides a snapshot of various collider signatures of long-lived particles, from displaced vertices to muon spectrometer clusters, and 14 00:02:29.402 --> 00:02:38.199 Rhitaja Sengupta: so the interesting thing about long-lived particles is that the signatures heavily depend on where these particles decay and what it decays into. 15 00:02:39.210 --> 00:03:01.230 Rhitaja Sengupta: But now, what about the decay is happening outside the Collider detectors? And this plot here shows that for very light and long lived particles. This can happen quite often. This plot shows the distribution of the decay length in the lap frame, and after some point around 10 meters or so the main collider detectors lose sensitivity. 16 00:03:01.340 --> 00:03:12.120 Rhitaja Sengupta: So in those scenarios, dedicated detectors placed either in the forward or transverse directions away from the interactions point interactions point provide sensitivity. 17 00:03:12.390 --> 00:03:27.190 Rhitaja Sengupta: You must be familiar with many dedicated detector proposals like Mathusla Codexby, or even the Phaser detector, which is already taking data for Run 3, there are multiple dedicated detectors proposed. And 18 00:03:27.390 --> 00:03:40.969 Rhitaja Sengupta: with today's talk, I would be trying to motivate that. Why optimization of these dedicated detectors is required, so that we just have enough to gain sensitivity to new physics. 19 00:03:42.700 --> 00:03:54.099 Rhitaja Sengupta: There have already been a number of interesting talks in this workshop about sustainable future colliders, and I have just put a list out here. 20 00:03:54.330 --> 00:03:55.639 Rhitaja Sengupta: If you are interested. 21 00:03:56.339 --> 00:04:10.740 Rhitaja Sengupta: But today I'll be talking about how can we be sustainable in our efforts to probe the light and weakly coupled regine, and these are some ideas to gain sensitivity to the light and weakly coupled regime. 22 00:04:10.970 --> 00:04:16.319 Rhitaja Sengupta: The 1st one is to utilize the existing facilities to the fullest. 23 00:04:16.470 --> 00:04:45.040 Rhitaja Sengupta: to look for unusual signatures. Second, is to optimize the dedicated detectors and find out what is the minimal requirement for these dedicated detectors to improve performance over the already existing or proposed main collider detectors. And we also talk about a shared detector concept for the Fccev and fcchh, and lastly, we will also highlight 24 00:04:45.457 --> 00:04:50.099 Rhitaja Sengupta: how to use a high pileup environment to our and to our advantage. 25 00:04:50.900 --> 00:05:12.220 Rhitaja Sengupta: To illustrate all these ideas, we'll be using the long lived particles in the Higgs portal as our benchmark model, where we extend the standard model with just a light scalar particle which interacts with the Higgs boson, so the mixing is highly constrained from 26 00:05:12.220 --> 00:05:28.200 Rhitaja Sengupta: existing low energy experiments, but it can also have a trilinear coupling with the standard model Higgs boson, which is not severely constrained, and this scenario gives long lived signatures of the 5 Dk. 27 00:05:29.270 --> 00:05:44.489 Rhitaja Sengupta: So for production you can, if you have enough, if you have a considerable value of the trilinear coupling. You can produce it from Higgs. Boson decays, or you can also produce it from meson decays from the mixing term. 28 00:05:45.190 --> 00:06:09.849 Rhitaja Sengupta: Now, the 1st idea is to utilize existing facilities to the fullest, to look for unusual signatures. For example, let us look at the Cms. 0 degree calorimeters, which are located around 140 meters away from the interaction point. The IP. 5, and the good thing is, they have 2 Zdcs on either side of the interaction point, and this could be sensitive to very forward 29 00:06:09.850 --> 00:06:23.309 Rhitaja Sengupta: physics, because it's at a very high pseudo rapidity. And all the charged particles are typically deflected away by magnets before they reach the Zdc, so it's at least there is no charged particle background there. 30 00:06:23.860 --> 00:06:47.210 Rhitaja Sengupta: So what we propose in this work is, can we modify the Zdcs at the high luminosity? Lhc. To gain sensitivity for long lived particles? There could be, of course, some possible backgrounds, and we have contacted this proposal idea with Zdc members to receive their feedback. And then we just need to put trackers to enhance sensitivity. 31 00:06:47.380 --> 00:07:01.410 Rhitaja Sengupta: And just to give you an idea of its performance with respect to the Phaser for the dark scalar model that I explained, it really gives some improvement in performance with respect to the Phaser detector, because it's much closer 32 00:07:01.800 --> 00:07:08.739 Rhitaja Sengupta: to the interaction point, and the enhancement is especially for heavy Llps with low seat out. 33 00:07:10.370 --> 00:07:39.440 Rhitaja Sengupta: Now, the second point is the optimization of dedicated detectors at Lhc. Or high luminosity. Lhc. The infrastructure is already there, so mostly these dedicated detectors are placed in any empty shafts or available halls around the main detectors, which is not, which need not be optimal for the Llp. Models beyond the standard model, but with future colliders. We have this advantage that they are in their conceptual design phase now. So we can optimize their design and integrate 34 00:07:39.440 --> 00:07:52.419 Rhitaja Sengupta: these dedicated Llp detectors with the main detector design, even if the funds are not available. For now, Cern can reserve the positions based on these studies for future for integrating them in future. 35 00:07:53.550 --> 00:08:09.979 Rhitaja Sengupta: So in this regard we proposed 2 detectors, one in the transverse direction, called delight, and one in the forward direction called Fore Hunt for the Fcchh. Initially, but then we also studied their performance at the Fcc. Collider. 36 00:08:10.390 --> 00:08:19.579 Rhitaja Sengupta: and let me discuss a bit what I mean about optimization, for in respect to the delight detector here. So 37 00:08:19.630 --> 00:08:46.060 Rhitaja Sengupta: we know the. So this is the Hllhc projection for the model that we discussed the dark scalar mass in the X-axis and the lifetime in the y-axis, and we see that there is a gap here for light mass and heavy high C. Tau values which the Fccee idea detector can probe a little bit, but a gap still remains, and the question is, can a dedicated detector 38 00:08:46.120 --> 00:08:48.099 Rhitaja Sengupta: probe this region? 39 00:08:49.320 --> 00:09:13.999 Rhitaja Sengupta: So now in this direction, we optimize the delay detector. We start from a very big detector, but the idea is to slowly decrease the parameters and move it farther away from the interaction point and see what is the minimal design to have at least the same efficiency as the idea main detector. If we have, even if we place it somewhere, which doesn't gain in terms of the idea main detector. There is no point of 40 00:09:14.120 --> 00:09:17.419 Rhitaja Sengupta: having this building, this dedicated detector. 41 00:09:17.640 --> 00:09:37.729 Rhitaja Sengupta: So in. So we calculate a gain with respect to the Fccee idea detector performance. And we identify this. We show here in these plots how this gain varies, and we also identify a minimal design called the core delight in this. You can find more details in this 42 00:09:37.920 --> 00:09:42.679 Rhitaja Sengupta: work here which we also submitted for the European strategy proposal. 43 00:09:43.720 --> 00:09:57.780 Rhitaja Sengupta: The 3rd idea is to have a shared detector concept for Fcc and Fcchh. So the question is, can we use this transverse detector at both Fcc. And Fcchh? And since if we place it 44 00:09:57.780 --> 00:10:17.569 Rhitaja Sengupta: in a separate cavern, which is parallel to the experimental cavern which houses both the Fccee and Fcch detectors. Then we can actually use it for both, and this opportunity to reuse an entire detector at Fccee is really impressive. 45 00:10:17.570 --> 00:10:27.829 Rhitaja Sengupta: and it will maximize resource, utilization, and it will promote sustainability in high energy physics, because for both the experiments we can reuse this dedicated detector. 46 00:10:28.250 --> 00:10:30.099 Rhitaja Sengupta: which is already optimized. 47 00:10:30.310 --> 00:10:45.410 Rhitaja Sengupta: and these are simple detectors with Rpcs and skin tillators as its major components so use of eco-friendly Rpcs. Would be very useful here, as we also heard from a talk this morning. 48 00:10:46.410 --> 00:11:06.459 Rhitaja Sengupta: and in terms of performance. We see, if you remember these grid plots which I showed a couple of slides back. These detectors. They really enhance the performance to light, and displaced new physics, both at Fccee in the left panel, and the performance for the fcchh is shown in the right panel. 49 00:11:07.270 --> 00:11:20.010 Rhitaja Sengupta: I'll now go to the final point of using a high pileup environment to our advantage. So future Hadron colliders are high luminosity machines and high instantaneous luminosity means a high value of Pylope 50 00:11:20.060 --> 00:11:39.520 Rhitaja Sengupta: and Pylop has always been seen as a nuisance, because it adversely impacts resolutions of experimentally measured observables which are essential to distinguish Bsm signals, and this effect is even more for lightning physics, which is even indistinguishable from the pileup events because of the low energy scales. 51 00:11:40.020 --> 00:11:49.099 Rhitaja Sengupta: But what about light? New physics coming from meson decays which can be there if you have a mixing with Higgs or some model like that. 52 00:11:49.810 --> 00:12:13.540 Rhitaja Sengupta: because, as you increase the number of pile of vertex, this table shows that the number of B. Hadrons produced per bunch crossing, or even D headrons. That increases, and this increase has to be taken into account when we calculate the efficiency of these Llps, because there is a production, there is an increase in the production rate of these Lsps from the B and D, and so on. 53 00:12:13.680 --> 00:12:15.590 Rhitaja Sengupta: When my time is up, I'll 54 00:12:16.198 --> 00:12:18.651 Rhitaja Sengupta: there's only the summary slide left. 55 00:12:19.240 --> 00:12:32.060 Rhitaja Sengupta: But yeah. So the idea here is to increase the efficiency of detecting Llps in various detectors per bunch crossing, and if we carefully include this in our studies, we might discover hints of light new physics sooner than expected. 56 00:12:32.650 --> 00:12:48.530 Rhitaja Sengupta: That brings me to the summary. In our endeavors to look for hints for new physics, it is very essential to achieve sustainability without compromising our physics needs, and this workshop has been 57 00:12:48.760 --> 00:13:07.189 Rhitaja Sengupta: a great collection of many interesting talks and very detailed studies, and in this talk we discuss a few sustainable approaches for probing the light, weakly coupled Regine leading to displaced signatures, and 58 00:13:07.350 --> 00:13:11.430 Rhitaja Sengupta: I hope that these could benefit our. 59 00:13:11.550 --> 00:13:20.279 Rhitaja Sengupta: This could benefit the preliminary studies of the future circular colliders and integrating the Llp detector designs. 60 00:13:20.420 --> 00:13:22.059 Rhitaja Sengupta: Thank you for your attention. 61 00:13:23.450 --> 00:13:29.149 Sukanya Sinha: Thank you, Rita, for this really interesting talk. Do we have any questions? 62 00:13:34.400 --> 00:13:53.289 Sukanya Sinha: So? I guess, while people are still thinking, I had a question of my own for the discussion with zdc, I was just curious. If you have had any preliminary feedback from them, because I mean. This is really cool, to see. 63 00:13:53.700 --> 00:14:02.899 Rhitaja Sengupta: Yes, but we still have not received any feedback, but they have acknowledged that this could be an interesting thing at the Hllhc. 64 00:14:03.200 --> 00:14:04.160 Sukanya Sinha: People. 65 00:14:05.260 --> 00:14:16.439 Sukanya Sinha: Okay, cool. And I guess you have already put in the other detectors in the European Strategy Update, or what's the plan? From now onward. 66 00:14:16.440 --> 00:14:33.040 Rhitaja Sengupta: I mean, from now onward the plan is to actually do concrete background studies for all these proposals like for Zdz, there could be this standard model neutral, neutral Lps background. So we want to study them also for delight. For this shared detector that 67 00:14:33.200 --> 00:14:43.050 Rhitaja Sengupta: I showed it would be important to understand what the background here is. So that is our next step in this regard. 68 00:14:45.155 --> 00:14:55.020 Rhitaja Sengupta: But yes, I mean, we are waiting to hear. I mean, we are, we would be happy to hear any experimental input we would really appreciate. 69 00:14:56.480 --> 00:15:04.599 Sukanya Sinha: Perfect. Hopefully, you get more feedback in the coming months. Is there any other question, Forja? At this point? 70 00:15:05.980 --> 00:15:06.879 Sukanya Sinha: If not, I would suggest. You can post your questions later in the chat as well, and we thank her again and move forward with our next speaker, which is going to be Maria.