1 00:00:01,260 --> 00:00:02,610 By Fady Bishara. 2 00:00:04,290 --> 00:00:09,240 So please, Fady, you I you you share the screen so you can start now. 3 00:00:10,290 --> 00:00:14,130 Okay, sounds sounds very good. So, um, so I'll talk about um 4 00:00:15,540 --> 00:00:20,670 some theoretical aspect and aspects in dark matter direct um I will talk about direct 5 00:00:20,670 --> 00:00:27,630 detection, but I will explain why um this is relevant for LHC searches. And um uh I have 6 00:00:27,630 --> 00:00:33,000 15 minutes, so I'll do my best then. Try not to have too many details. So if there are 7 00:00:33,000 --> 00:00:37,230 something, there's some things that you want to know um that I didn't cover, please 8 00:00:37,230 --> 00:00:44,070 ask me. Okay, so, uh, well, since it's the beginning, I can I can do a motivation, 9 00:00:44,070 --> 00:00:48,510 even though Oh, I think it is really needed. There's overwhelming observational 10 00:00:48,510 --> 00:00:53,430 evidence for dark matter. We know it exists. But all of these observe all of 11 00:00:53,430 --> 00:00:59,760 these probes are based on gravitational interactions. But we know that there's 12 00:01:00,000 --> 00:01:05,550 particle physics beyond the Standard Model, this is something we know that we 13 00:01:05,550 --> 00:01:09,480 know that it has to be something and we know that it has to be a particle, we can 14 00:01:09,480 --> 00:01:15,240 discuss to which direction you know which which puzzle we need to solve that can, 15 00:01:15,540 --> 00:01:20,520 has to be solved by a particle in which not. But um this can also include particle 16 00:01:20,520 --> 00:01:26,670 dark matter. So, it's a it's a reasonable uh uh it's a reasonable hypothesis that dark 17 00:01:26,670 --> 00:01:31,470 matter is a particle in nature. And this has motivated many many searches for dark 18 00:01:31,470 --> 00:01:37,320 matter at the LHC direct detection in direct detection and all kinds of new 19 00:01:37,320 --> 00:01:42,870 probes are being thought of in a theoretical and experimental communities. 20 00:01:43,380 --> 00:01:47,400 And if dark matter is a particle, then there is a variety of searches that we can uh 21 00:01:48,120 --> 00:01:51,900 have we have that we can look for it. So there are three main pillars sort of 22 00:01:51,930 --> 00:02:00,690 direct, indirect, and Collider. And uh in order for for one for us to build uh uh uh uh coherent 23 00:02:00,720 --> 00:02:06,390 sort of big picture model of the dark, oh oh big picture of the Dark Matter model that's 24 00:02:06,390 --> 00:02:09,840 behind these these signatures hopefully we'll start seeing signatures. We haven't 25 00:02:09,840 --> 00:02:16,170 seen any smoking guns for particle nature of dark matter yet. But hopefully we start uh 26 00:02:16,560 --> 00:02:20,880 seeing them and in order to know disentangle the nature of the sector, or 27 00:02:20,880 --> 00:02:25,860 this particle or the mediators that come with this particle, we need to connect all 28 00:02:25,860 --> 00:02:32,070 these different experimental searches. So there are really a couple of questions uh that that that 29 00:02:32,280 --> 00:02:35,730 we want to address. One, how can we compare the results in different search 30 00:02:35,730 --> 00:02:41,430 strategies. So at the moment, everybody's sort of doing their thing. And uh for direct 31 00:02:41,430 --> 00:02:45,480 detection, are all the relevant defects accounted for because this is actually 32 00:02:45,540 --> 00:02:51,270 quite quite important and and it ties into sort of historical precedents of of looking 33 00:02:51,270 --> 00:02:55,890 for certain for new interactions, and not having to write not having to correct 34 00:02:55,890 --> 00:03:01,230 effects and and taking care of you might have seen something much earlier than you 35 00:03:01,230 --> 00:03:04,860 expected or not see something things like this. And both of these questions are can 36 00:03:04,860 --> 00:03:09,840 be answered in in the complex of dark matter effective field theories, which is what I'll 37 00:03:09,840 --> 00:03:18,900 I'll just describe for you uh in in the coming slides. So first, uh let's look at the LHC 38 00:03:18,900 --> 00:03:22,020 versus direct directions so the super, super simplified picture of of what's going 39 00:03:22,020 --> 00:03:26,220 on there many many searches at the LHC and there many searches there are many direct detection 40 00:03:26,220 --> 00:03:32,940 probes, but just for just a simple naive picture, let me show that uh so at at at the at 41 00:03:32,940 --> 00:03:40,920 the LHC either you can produce uh dark matter particles directly. Which Can you 42 00:03:40,920 --> 00:03:41,700 see my cursor? 43 00:03:44,820 --> 00:03:46,260 Yes, yes, yes. 44 00:03:47,880 --> 00:03:52,740 Good, I will not point all over the place. So here you can see the top at the LHC 45 00:03:52,740 --> 00:03:57,270 panel on the right here you produce two dark matter particles by a mediator. For 46 00:03:57,270 --> 00:04:02,250 example, if the mediator is not too heavy, Meaning if it's accessible within the LHC 47 00:04:02,250 --> 00:04:06,630 energies, you will produce the mediator. And if it decays only, I mean clearly it 48 00:04:06,630 --> 00:04:09,210 cannot only decay to dark matter because it couples to the standard model. 49 00:04:09,210 --> 00:04:14,640 But there are many, a lot of theoretical model building goes in this direction. 50 00:04:15,420 --> 00:04:19,170 But, uh so either you observe it directly for the decay back to standard model like dijets or 51 00:04:19,170 --> 00:04:22,620 things like this, or it's missing E T signature and then the other side, there's 52 00:04:22,620 --> 00:04:25,890 some other standard model particle that's produced, let's call it x. So there are 53 00:04:25,890 --> 00:04:31,560 two different uh broadly speaking, uh signatures at the LHC. Of course, you'll hear more 54 00:04:31,560 --> 00:04:37,890 about that in the in the coming uh uh specific searches at Atlas and CMS and, and and one such 55 00:04:37,890 --> 00:04:43,740 signature with Higgs. Uh and for the direct detection, what you have is, again, your 56 00:04:43,740 --> 00:04:47,910 coupling, still the Standard Model, to the Dark Sector with some mediator, it's 57 00:04:48,360 --> 00:04:52,620 probably the same mediator, but now it's happening at a much different scale. And 58 00:04:52,620 --> 00:04:57,780 I'll talk about scales in the next slide. And so this nucleus gets elastically 59 00:04:57,870 --> 00:05:04,380 probed and it just uh gets excited and and radiates a photon, etc, etc. If you zoom in on 60 00:05:04,380 --> 00:05:09,780 this interaction, you see that again, uh it's something similar to what we have here. 61 00:05:09,780 --> 00:05:14,910 But I just took the proton and I just integrated out the mediator. And proton can 62 00:05:14,910 --> 00:05:20,280 be proton or neutron. And if you zoom in even further on this interaction, you see that uh 63 00:05:20,670 --> 00:05:24,900 Well, you have to couple the dark matter to the quarks and then the quarks have to 64 00:05:24,900 --> 00:05:30,240 interact have to, well, the quarks, you know, make up the hadrons make up the 65 00:05:30,240 --> 00:05:36,720 pions and the nucleons. But in order for uh for you to compute this rate, uh you need to uh 66 00:05:36,780 --> 00:05:42,060 compute some uh non perturbative objects, and I'll talk about this a little bit next. 67 00:05:42,060 --> 00:05:47,370 So the idea is that uh this what happened here at the LHC is what's happening here, 68 00:05:47,370 --> 00:05:50,550 it's just happening at a very different scale and the physics is different. And 69 00:05:50,550 --> 00:05:56,340 what we want is we want to say, Ah, you know, Atlas CMS, they saw this, uh you know, 70 00:05:56,340 --> 00:06:00,960 this dijets signature that that looks like in this mass range and direct detection we saw 71 00:06:00,990 --> 00:06:05,550 we saw, you know, dark matter in this range, etc etc. And you know, put these 72 00:06:05,550 --> 00:06:10,980 two together we want to know we want to be able someday to say this dark sector has 73 00:06:11,400 --> 00:06:15,300 this kind of mediator couples to dark matter couples to to quarks, it doesn't 74 00:06:15,300 --> 00:06:20,790 couple to leptons. And in order to do this we need to we need some framework in order 75 00:06:20,790 --> 00:06:27,120 to combine all these researches. And um uh before I I tell you about the effective 76 00:06:27,120 --> 00:06:31,020 field theories that are involved here, uh let's let's talk about scales because that's a 77 00:06:31,020 --> 00:06:36,330 very important aspect of what's going on here. So scales. What's happening at 78 00:06:36,330 --> 00:06:40,470 the LHC. I'll start from the right and then go to the left. What's happening at 79 00:06:40,470 --> 00:06:46,470 the LHC at collider searches uh is you produce standard model uh Standard Model 80 00:06:46,470 --> 00:06:51,090 particles collide with the quarks, gluons, blah, blah, they collide, they make uh either 81 00:06:51,090 --> 00:06:56,550 a mediator uh which which decays into standard dark matter or or just a mediator something 82 00:06:56,550 --> 00:07:02,790 like this. Okay? This uh energy scale is set by the by the partonic center of mass energy at the 83 00:07:02,790 --> 00:07:09,870 LHC, which is roughly of a quarter TeV. For indirect detection, what's happening is 84 00:07:09,870 --> 00:07:13,560 that uh you turn this diagram. I mean, you've seen this pictures with people putting 85 00:07:13,560 --> 00:07:17,310 arrows all over the place during one diagram. But here I draw the diagrams for 86 00:07:17,310 --> 00:07:22,770 you. So uh uh from the left to the right, you have uh dark matter dark matter going into standard 87 00:07:22,770 --> 00:07:27,480 model standard model, and since dark matter is nonrelativistic, uh in our Halo, 88 00:07:28,050 --> 00:07:36,510 thinking broadly about some GeV to TeV particle and uh and of course, that that's just a subset 89 00:07:36,510 --> 00:07:45,810 of models, but Okay, uh just to to to to think about something concrete, uh that's set by the the 90 00:07:45,810 --> 00:07:52,470 twice the mass roughly of the dark matter, which is around 100 GeV or so. For direct 91 00:07:52,470 --> 00:07:56,310 detection, the relevant scale is the momentum transferred to the nucleus and the 92 00:07:56,310 --> 00:08:03,240 momentum transferred to the nucleus is roughly uh 200 MeV, at the moment maximal, 93 00:08:03,240 --> 00:08:07,890 let's say 200 MeV max is this momentum of transfer, there's yet another scaling 94 00:08:08,010 --> 00:08:10,470 problem. And that's the scale of the mediator. So here, I didn't draw the 95 00:08:10,470 --> 00:08:15,480 mediator, but of course at the LHC, uh you're, you know, if if the mediator is not 96 00:08:15,480 --> 00:08:19,560 too heavy, you're most likely to see to see that first at the LHC. So that's 97 00:08:19,560 --> 00:08:23,970 another scale in this in this problem. So, there are many, many scales and when you 98 00:08:23,970 --> 00:08:29,370 have many, many scales, the first thing that comes to mind or the go to solution, 99 00:08:29,370 --> 00:08:35,760 when you have separate scales, like this is effective field theories. And, uh and I 100 00:08:35,760 --> 00:08:39,090 see a tower of effective field theories, because really, these are very different 101 00:08:39,090 --> 00:08:41,220 effective field theories that that that you 102 00:08:42,569 --> 00:08:47,639 that that you have to construct. So starting with a very high scale. So let's say, at 103 00:08:47,669 --> 00:08:51,509 or below the scale of the mediators. Uh You can have some effective field theory that 104 00:08:51,509 --> 00:08:54,269 couples dark matter to. So below the scales of mediators, you can just 105 00:08:54,269 --> 00:08:57,989 integrate it out. And you can just have the dark matter directly interacting with 106 00:08:57,989 --> 00:09:01,199 a standard model, but also you can have a simplified model, which is something 107 00:09:01,199 --> 00:09:06,569 that, you know is useful at the LHC, which combine some effective operators plus 108 00:09:06,599 --> 00:09:11,759 a few extra light states if you want, light meaning of order the dark matter mass or 109 00:09:11,759 --> 00:09:15,269 below some uh cutoff to integrate some stuff out of the Dark Sector, but not 110 00:09:15,269 --> 00:09:21,839 everything. Uh If the dark matter is roughly of the electroweak scale, for the sake of 111 00:09:21,839 --> 00:09:26,219 argument, let's say that below that you have to integrate out all the heavy 112 00:09:26,219 --> 00:09:34,139 states. So the heavy states in this case is the Higgs, the top, the uh uh uh the W and the 113 00:09:34,139 --> 00:09:39,089 Z and also the dark matter mass itself. If if it's heavy, you have to use a heavy 114 00:09:39,239 --> 00:09:43,049 Dark matter effective field theory. So now we have heavy dark matter effective field 115 00:09:43,049 --> 00:09:47,609 theory plus five flavor QCD. Now we're out of essentially out of the realm of, of 116 00:09:47,609 --> 00:09:52,709 LHC, LHC was above now we are below, okay, but uh we need to keep going below because we 117 00:09:52,709 --> 00:09:58,319 need to get from the LHC energies, okay, above M Z all the way down to the nuclear 118 00:09:58,319 --> 00:10:03,059 scale. So now we're here Go down below the bottom threshold integrate at the bottom 119 00:10:03,509 --> 00:10:09,689 for flavor QCD plus heavy dark matter, etc etc until you get to one GeV or two GeV. When you 120 00:10:09,689 --> 00:10:14,399 get to this scale you can no longer talk about quarks uh interacting with dark matter 121 00:10:14,399 --> 00:10:18,419 you have to talk about dark matter interacting with pions and nucleons with 122 00:10:18,419 --> 00:10:24,839 hadrons. So, what you have to do is you have to match from above this three GeV one GeV 123 00:10:24,839 --> 00:10:30,389 scale to below it. And when you do this, you have you go to uh non perturbative if if you 124 00:10:30,389 --> 00:10:35,969 want this non perturbative matching in in a sense to uh uh uh effective field theory with with 125 00:10:35,969 --> 00:10:39,989 nonrelativistic nucleon physics heavy baryons in effective field theory of external probes 126 00:10:39,989 --> 00:10:44,999 that are the dark matter. one step further is now you have to match on to this 127 00:10:45,029 --> 00:10:48,659 nonrelativistic effective field theory which the nuclear theorists use in order 128 00:10:48,659 --> 00:10:55,709 to compute these response functions of uh uh the the response of the nucleus to the dark matter 129 00:10:55,709 --> 00:11:00,779 external probe. And so there are some references below. Lots of work in this 130 00:11:00,779 --> 00:11:06,059 direction for many years, there's a bunch of papers I was involved in, there's more 131 00:11:06,329 --> 00:11:09,509 and more things. So just some references. I'm not going to talk in details about any 132 00:11:09,509 --> 00:11:16,979 of these things, because I I only have three minutes left. Uh So uh uh it's such as the nature, 133 00:11:17,009 --> 00:11:23,339 but what what you need to compute I mentioned earlier is these nonrelativistic sorry, 134 00:11:23,369 --> 00:11:28,619 these non perturbative matrix elements, all you know is that you can organize 135 00:11:28,619 --> 00:11:33,299 these matrix elements. So what you want What you want is is I have a 136 00:11:33,299 --> 00:11:36,089 dark matter talking with a quark current, I want to know what the dark matter 137 00:11:36,089 --> 00:11:40,769 interaction with the nucleus with the nucleons in the nucleus is and what I can 138 00:11:40,769 --> 00:11:45,749 do is I can just write it by by uh Lorentz invariance, I can write whatever 139 00:11:45,749 --> 00:11:51,209 everything that can appear by parity Lorentz etc. and uh stick in front of these 140 00:11:51,239 --> 00:11:57,119 these these Lorentz structures, some form factor, which is non perturbative. You can 141 00:11:57,119 --> 00:12:02,639 compute this systematically with uh with Using chiral expansion, I'm not going to 142 00:12:02,639 --> 00:12:06,839 talk about this. Uh Once once you do this, then you can match up to this 143 00:12:06,839 --> 00:12:13,649 nonrelativistic effective field theory. And uh in this nonrelativistic physics, effective 144 00:12:13,649 --> 00:12:18,749 field theory is Galilean invariant At leading order in in in the momentum expansion there are 145 00:12:18,749 --> 00:12:25,589 these sort of 14 operators. If you restrict it, if you impose certain 146 00:12:25,589 --> 00:12:30,149 restrictions, if you don't, they're more and maybe I put your attention to a couple 147 00:12:30,149 --> 00:12:35,999 of them, which you're familiar with O one n is the uh uh uh spin independent uh 148 00:12:36,869 --> 00:12:40,589 interaction. And O four is the spin-dependent. If you see there's a spin dots spin 149 00:12:40,589 --> 00:12:44,189 here, and here, there's the number operator on dark matter side, on the 150 00:12:44,189 --> 00:12:50,669 nucleus side. So we want to match onto this. There's some form factors. uh I only 151 00:12:50,669 --> 00:12:53,309 have two minutes so we'll just go to an example and then you can ask me 152 00:12:53,309 --> 00:12:59,909 whatever you want back back on top of this. I have a few minutes. Three minutes for you. Sorry, you have three minutes. I I 153 00:13:00,839 --> 00:13:06,329 Yeah, yeah. Oh, maybe your clock is that one minutes ahead of me but all I want to 154 00:13:06,449 --> 00:13:10,229 All I want to show is one example uh which is uh uh 155 00:13:11,700 --> 00:13:17,400 you know connecting. This is really maybe maybe more for the for the those who do 156 00:13:17,460 --> 00:13:21,420 direct detection of of dark matter. But if those who are doing direct detection of 157 00:13:21,420 --> 00:13:26,850 dark matter want to correlate their experimental searches with things that are 158 00:13:26,850 --> 00:13:32,460 seeing at the LHC what's best to do is to put bounds on the operators 159 00:13:32,460 --> 00:13:37,230 between dark matter and quarks and not on these nonrelativistic coefficient. This is 160 00:13:37,230 --> 00:13:45,150 an example of just a simple uh uh electric dipole interaction uh uh with with the with 161 00:13:45,150 --> 00:13:49,440 dark matter, uh uh tensor current, and you see there are many operators in the 162 00:13:49,440 --> 00:13:53,820 nonrelativistic theory that enter. uh Some of them dominate in different regimes 163 00:13:53,850 --> 00:14:00,420 different experiments, fluorine versus Xenon, etc, etc. So the the point of of this Here 164 00:14:00,420 --> 00:14:06,120 this this this lowest uh uh black curve is what you would expect as a bound from the dark 165 00:14:06,120 --> 00:14:10,950 detection experiment. Forget about the y axis, it doesn't really matter. And uh all 166 00:14:10,950 --> 00:14:15,480 these other individual contributions of the different operators, these operators 167 00:14:15,480 --> 00:14:20,490 interfere with each other. So for example, for fluorine, you see that the some curve 168 00:14:20,490 --> 00:14:24,960 is actually higher than one of these lower curves because they interfere somewhat, 169 00:14:24,960 --> 00:14:32,790 the interferences are negative. So, uh so, uh all this is summarized in a in a public code, 170 00:14:32,790 --> 00:14:39,930 that's Mathematica. And Python, if uh uh you want to do either translate a direct 171 00:14:39,930 --> 00:14:47,190 detection result up to uh LHC result or the other way around. Ideally, what I 172 00:14:47,190 --> 00:14:51,510 would really just like to to get across from hopefully to get across from what I said 173 00:14:51,510 --> 00:14:56,700 is that we want to correlate these these search the search strategies with each 174 00:14:56,700 --> 00:15:00,990 other. We want to be able to build a coherent picture and uh For this, it's best 175 00:15:00,990 --> 00:15:07,290 to try to put things on the same plane. And and this, this tool or tools like it allow 176 00:15:07,290 --> 00:15:14,160 you to direct detection or LHC, put bounds on certain uh coefficients, either simplified 177 00:15:14,160 --> 00:15:19,470 model parameters, etc, something like this and talk about the same quantities, not 178 00:15:19,470 --> 00:15:24,390 different quantities. And that's what we want. We want to do this consistent. So I 179 00:15:24,390 --> 00:15:27,900 will close with just a quick summary of what I said, there's overwhelming evidence 180 00:15:27,900 --> 00:15:31,890 for the existence of dark matter, it's reasonable to posit that it is a particle 181 00:15:32,160 --> 00:15:35,820 in nature. At least we don't have any evidence to the contrary of this at the 182 00:15:35,820 --> 00:15:40,020 moment. Uh So we want to discover and if that's the case, we want them to discover 183 00:15:40,020 --> 00:15:44,070 the model and disentangle the structure of the dark sector. And and and you've probably heard 184 00:15:44,070 --> 00:15:49,080 this 1000 times. But let me also emphasize that there's most likely a Dark Sector not 185 00:15:49,080 --> 00:15:52,620 a dark matter particle, it's probably not going to come by itself. I mean, we know 186 00:15:52,620 --> 00:15:55,080 it's not going to come by itself, because we already know there has to be a 187 00:15:55,080 --> 00:16:01,140 mediator, but it could be even more complicated than this. Uh uh to To this end, you 188 00:16:01,140 --> 00:16:04,890 know, we need we need different we have different probes at different scales. And this is a 189 00:16:04,890 --> 00:16:07,590 classic setup for effective field theories, we should be using something 190 00:16:07,590 --> 00:16:11,490 like this in order to correlate these signatures. The public code exists. And I 191 00:16:11,490 --> 00:16:18,630 should tell you that if you want a a much broader overview of dark matter, uh uh progress 192 00:16:18,630 --> 00:16:23,010 and model building, etc, things like this. There's uh the dark matter at LHC next week, 193 00:16:23,010 --> 00:16:27,390 and there's the indico link for for your convenience. Thank you. 194 00:16:28,290 --> 00:16:31,140 Thank you very much, Fady. This was very interesting. um 195 00:16:33,360 --> 00:16:38,310 So now it's time for questions or comments. So to remind you, you can raise 196 00:16:38,310 --> 00:16:42,960 your hand with the button at the uh the bottom of your zoom window. 197 00:16:44,640 --> 00:16:45,570 Any questions? 198 00:16:54,060 --> 00:16:56,700 I don't see any Julien? 199 00:16:57,990 --> 00:16:59,670 I wanted to ask you 200 00:17:00,780 --> 00:17:06,750 On the practical side, so for for an experimentalist at the LHC. So, what what 201 00:17:07,260 --> 00:17:10,470 can you be more specific how to use your code 202 00:17:11,700 --> 00:17:13,740 for an experimental setup okay uh 203 00:17:17,129 --> 00:17:19,589 yes I mean one okay. 204 00:17:21,150 --> 00:17:27,630 I mean one one thing is so there there are for example, simplified models at at the LHC 205 00:17:27,690 --> 00:17:30,120 which uh you guys are already using. uh 206 00:17:31,890 --> 00:17:33,570 The question is the question is uh 207 00:17:34,920 --> 00:17:42,570 is uh for you maybe you already putting bounds on on a simplified model with a few 208 00:17:42,570 --> 00:17:50,430 parameters. The idea mainly is for the for the direct detection experiments to use 209 00:17:50,430 --> 00:17:56,520 the same simplified model with the same parameters matching onto the effective 210 00:17:56,520 --> 00:18:02,280 field theory and running down to their scale and then Compare the bounds, which 211 00:18:02,700 --> 00:18:06,900 already has been done. Actually, it's not i'm not saying anything super new. I mean, um 212 00:18:07,320 --> 00:18:10,620 some people are doing this, but it's certainly not adopted by the experiments 213 00:18:10,650 --> 00:18:17,220 on a wide scale. I think. I think, I don't know if there are any direct detection 214 00:18:17,220 --> 00:18:20,730 experimentalists in the audience. But that's really the where the push needs to 215 00:18:20,730 --> 00:18:25,140 happen. I think there's been a slow trickle of direct detection experience 216 00:18:25,140 --> 00:18:29,190 putting pounds on these nonrelativistic operators. And I think that's preventing 217 00:18:29,790 --> 00:18:35,850 the ease of comparison with LHC results. So there's nothing you need to do per se, 218 00:18:35,940 --> 00:18:42,480 even though you could if you want to take this, put in uh the bounds from a recent 219 00:18:42,480 --> 00:18:46,110 search on some simplified model, match it onto the effective field theory, the 220 00:18:46,110 --> 00:18:51,360 matching could be done at tree level, depending on the model. And just uh and if 221 00:18:51,360 --> 00:18:56,580 you need Of course, if you need help doing that, we're also happy happy to do to do 222 00:18:56,580 --> 00:19:00,600 this if it's a in some paper already, and then you can compare ATLAS Results 223 00:19:00,600 --> 00:19:05,970 directly with LHC rather than I mean, I should Atlas or CMS, but rather than I 224 00:19:05,970 --> 00:19:13,440 should mention uh uh the attempt of of plotting Atlas or CMS results, maybe I should have 225 00:19:13,440 --> 00:19:14,610 said this first, sorry. 226 00:19:16,170 --> 00:19:18,930 Plotting Atlas or CMS result as a single uh uh uh 227 00:19:20,370 --> 00:19:25,110 cross section per per nucleon. At zero momentum transfer. I think that's maybe, uh 228 00:19:26,190 --> 00:19:29,790 maybe that's the message. No, you don't need to do that. And I think there's been 229 00:19:29,850 --> 00:19:33,870 already a push away from this in recent years. I don't think this is being done 230 00:19:33,870 --> 00:19:40,200 actively anymore. But there were lots of Atlas and CMS trying to put bounds on on 231 00:19:40,230 --> 00:19:44,100 dark matter in that same plane of direct detection, and that's simply not the right 232 00:19:44,100 --> 00:19:45,090 thing to do. But 233 00:19:45,900 --> 00:19:46,410 I see. 234 00:19:48,690 --> 00:19:52,590 Not the best thing to do I should say, I understand. So yeah, this is this is good 235 00:19:52,590 --> 00:19:58,980 yeah. Indara, you you raised your hand, but I don't see it anymore, raise it. I 236 00:19:58,980 --> 00:20:02,430 hope it's fine. Don't we have another? Oh yeah. 237 00:20:07,080 --> 00:20:11,790 Hi. Yeah, I guess I'm still a little confused. So do we as LHC 238 00:20:11,790 --> 00:20:16,980 experimentalists benefit from this tool? Like will we get what would be if we are 239 00:20:16,980 --> 00:20:22,680 already doing interpretations ah In simplify models, ah, what would we get 240 00:20:22,770 --> 00:20:23,910 out of this tool? 241 00:20:24,659 --> 00:20:27,569 That's not clear to me still, right? 242 00:20:28,830 --> 00:20:33,000 Okay. If you're doing if you if you have a simplified model and the model is not 243 00:20:33,000 --> 00:20:39,450 sick, for which there has been also work on on on on making sure that models are are are S U 244 00:20:39,450 --> 00:20:44,010 Two gauge invariant, etc, etc, then you're doing the right thing you don't need to 245 00:20:44,010 --> 00:20:49,680 worry okay. But if you want to compare, which as I mentioned was done before 246 00:20:49,680 --> 00:20:54,060 compare on the same plot with direct detection, then you need to use this 247 00:20:54,060 --> 00:20:59,160 because you need to put in your, your model you match your model to effective 248 00:20:59,160 --> 00:21:03,930 field theory. And then from this extract the the direct detection cross section and 249 00:21:03,930 --> 00:21:13,080 rather than converting results into uh cross section, cross cross section for single 250 00:21:13,080 --> 00:21:18,240 nucleon at zero momentum transfer, which works for only some interactions, but 251 00:21:18,420 --> 00:21:22,860 mostly, if you start going to spin dependent stuff, it becomes very awkward 252 00:21:23,100 --> 00:21:27,900 to do, then that that's it. No, I mean, that's only for comparing between if 253 00:21:27,900 --> 00:21:31,260 you're if you're using simplified models and you're putting bounds on a few 254 00:21:31,260 --> 00:21:34,110 parameters, the mass, the mass of the mediator, the mass of dark matter or the 255 00:21:34,110 --> 00:21:37,710 coupling, then everything is okay as long as the model is not sick because 256 00:21:37,710 --> 00:21:42,150 simplified models can also be sick, sick, meaning they could have unitarity 257 00:21:42,180 --> 00:21:46,710 violation problems, or they could have gauged invariance problems above the 258 00:21:46,710 --> 00:21:50,220 electroweak scale. So this but this has been addressed also in the literature. 259 00:21:50,700 --> 00:21:56,400 Does this answer your question? I'm sorry, if I'm not being very precise, I can reach 260 00:21:56,400 --> 00:22:00,420 out to you offline. I guess I'm just curious about what the output of This 261 00:22:00,420 --> 00:22:06,840 would be okay, please, I would be happy to to please send me an email and we can go by 262 00:22:06,840 --> 00:22:09,600 email or chat if you wish. It would be very happy to do it. 263 00:22:11,490 --> 00:22:12,750 Thank you. Yeah. 264 00:22:14,370 --> 00:22:27,300 I see two questions in the chat. Uh uh One question uh is is the EFT is this EFT to include 265 00:22:27,300 --> 00:22:28,740 gravity somehow? 266 00:22:34,830 --> 00:22:41,550 Okay, we're we're working around the electroweak scale. So this is not EFT for 267 00:22:41,550 --> 00:22:46,260 gravitational interactions. It's just for Yeah. Not sure if I'm answering the 268 00:22:46,260 --> 00:22:53,760 question in the way it was meant to be asked But yeah no, this doesn't include 269 00:22:53,760 --> 00:22:56,250 gravity. Let me say it this way. 270 00:22:57,000 --> 00:23:02,490 Then there is there is another question. I don't know Yong Du, Do you want to raise 271 00:23:02,490 --> 00:23:10,860 your hand rather than chatting in the window? So that we Yeah. 272 00:23:18,119 --> 00:23:24,899 Uh huh. Can you hear me. Yes, yes. My question is so in the nuclear nuclear 273 00:23:24,899 --> 00:23:30,359 Matrix element you include, for the form factors, you include contributions from the second 274 00:23:30,359 --> 00:23:35,339 class currents and I want to know how large those contributions and and do 275 00:23:35,369 --> 00:23:40,829 We really need to include those at this moment Can you can you explain 276 00:23:40,829 --> 00:23:42,479 what you mean by second class currents. Uh 277 00:23:43,020 --> 00:23:43,980 So basically 278 00:23:46,530 --> 00:23:55,920 those are ah the ones that are suppressed by the by the mass of the nucleons the second term in your in your 279 00:23:56,010 --> 00:23:57,540 the second term in your 280 00:24:00,000 --> 00:24:04,800 higher terms in the in the heavy baryon expansion? 281 00:24:05,340 --> 00:24:05,850 Yes. 282 00:24:07,350 --> 00:24:07,860 I mean, 283 00:24:11,610 --> 00:24:15,300 yeah, these effective field theories are very complicated because there are many 284 00:24:15,300 --> 00:24:18,810 parameters. As you mentioned this already one, one thing, there's one over. I mean, 285 00:24:19,620 --> 00:24:23,910 you're used to you, people are used to writing uh uh a Wilson coefficient over lambda 286 00:24:23,910 --> 00:24:27,960 squared, for example, like you do in SMEFT, or something like this. But here, 287 00:24:28,020 --> 00:24:30,960 lambda squared is actually many, many parameters. There's the dark matter 288 00:24:30,960 --> 00:24:36,690 masses, there is the baryon masses, as you mentioned, there's the Q squared. Uh There's a q squared 289 00:24:36,690 --> 00:24:41,370 expansion q squared over lambda chi expansion. Uh We're interested in the leading 290 00:24:41,370 --> 00:24:44,460 effects because there are many uncertainties. So if there was a reason 291 00:24:44,460 --> 00:24:48,360 that the leading order contribution is is is we think the leading order one so if the 292 00:24:48,360 --> 00:24:49,590 leading order one is not that uh 293 00:24:50,880 --> 00:24:53,760 one over m to the zero then you take the one over m. 294 00:24:55,620 --> 00:25:02,580 Yeah, but higher order corrections are not included at the moment. I see Thank you, 295 00:25:02,790 --> 00:25:07,440 but they and let me let me let me let me follow up on this question because it's a 296 00:25:07,440 --> 00:25:12,000 very nice question. Why do you use EFT you use EFT is because first you can do the 297 00:25:12,000 --> 00:25:14,880 leading order thing. And you know what it is, it's very well defined, you have power 298 00:25:14,880 --> 00:25:18,990 counting everywhere. And if you want once we discovered dark matter and you want 299 00:25:18,990 --> 00:25:23,280 more precision for some reason, there's some area where you need better precision, 300 00:25:23,460 --> 00:25:29,190 you know how to improve you can go to the next order in one over m um um m nuclear, 301 00:25:29,220 --> 00:25:34,290 nucleon and you can go higher order in q squared over Lambda Chi for example, and 302 00:25:34,290 --> 00:25:40,290 we do all a lot of this, these things so you can you can improve easily and in this in a 303 00:25:41,640 --> 00:25:42,570 controlled way.