1 00:00:02,520 --> 00:00:05,340 So, an outline 2 00:00:05,340 --> 00:00:09,930 of this presentation, I will first tell you something about the Higgs boson self 3 00:00:09,930 --> 00:00:16,500 coupling, then move to rare decays and beyond standard model physics, and then if time allows a 4 00:00:16,500 --> 00:00:22,290 very brief outlook towards high-luminosity LHC. I will focus only on a selection of more recent 5 00:00:22,290 --> 00:00:27,690 results. There's many many results especially from the early LHC Run2 data 6 00:00:27,690 --> 00:00:32,460 that you can find in the public pages of ATLAS and CMS and also in the parallel 7 00:00:32,490 --> 00:00:38,040 talks. So for the self coupling, well it has been introduced already in the 8 00:00:38,040 --> 00:00:42,480 previous presentations, in the standard model in the potential we have lambda phi 9 00:00:42,480 --> 00:00:47,700 to the fourth power, and after the electroweak symmetry breaking, when we look 10 00:00:47,700 --> 00:00:54,660 at the physical Higgs, we have a term that gives us a three Higgs vertex and also a four 11 00:00:54,660 --> 00:00:59,130 Higgs vertex, but the four Higgs vertex, we will never be able to probe 12 00:00:59,130 --> 00:01:01,560 at the LHC. So, 13 00:01:03,659 --> 00:01:04,889 talking about the 14 00:01:06,180 --> 00:01:12,780 so the trilinear vertex, this we can probe in double Higgs production and the 15 00:01:12,780 --> 00:01:19,380 dominant production cross section at the LHC is gluon fusion, which has two 16 00:01:19,380 --> 00:01:24,870 contributions, as we have essentially production of a single Higgs boson that so 17 00:01:24,870 --> 00:01:30,660 goes dominantly through the top quark loop, followed by the self coupling to 18 00:01:30,660 --> 00:01:36,060 produce two Higgses, or we have contributions like the square that only 19 00:01:36,060 --> 00:01:41,460 depends on the couplings of the single Higgs boson to standard model particles. 20 00:01:43,500 --> 00:01:47,610 There is a destructive interference between the two that gives us this very 21 00:01:47,610 --> 00:01:54,060 small cross section of 31 femtobarns and causes the cross section to depend in a 22 00:01:54,060 --> 00:02:00,000 non trivial way from the self coupling. In fact, if you go to zero self coupling, the 23 00:02:00,000 --> 00:02:08,910 cross section increases instead of decreasing. So, in terms of results on double Higgs 24 00:02:08,910 --> 00:02:15,000 boson production, the state of the art is still the results based on the early LHC 25 00:02:15,000 --> 00:02:20,880 Run2 data. So it's mostly 2016 data. These, however, are fairly old results that 26 00:02:20,880 --> 00:02:25,620 have been around for a couple of years, often, so I will not describe them there, 27 00:02:25,650 --> 00:02:30,690 I just wanted to give you more or less the ballpark sensitivity. This is driven by 28 00:02:30,690 --> 00:02:36,360 three modes, the bb tau tau that has put here in green for the two experiments, bb gamma 29 00:02:36,360 --> 00:02:43,290 gamma in blue, and four b in red and the sensitivity also depends on how 30 00:02:43,290 --> 00:02:48,120 advanced the analysis was on one side or on the other side of the LHC ring. But 31 00:02:48,120 --> 00:02:55,020 combining all of them, the two experiments get to about 10 times a limit on the 32 00:02:55,020 --> 00:02:59,040 double Higgs section that is about 10 times the standard model prediction. So 33 00:02:59,040 --> 00:03:06,810 there is still a long way to go. But this was just with a partial data set. We have a 34 00:03:06,810 --> 00:03:16,170 couple of results, and in particular one from ATLAS, that goes to analyze the full 35 00:03:16,170 --> 00:03:21,180 LHC Run2 data but this is in the final state for double Higgs production to b 36 00:03:21,180 --> 00:03:28,950 bbar WW fully leptonic, which is not one of the most sensitive the three most 37 00:03:28,950 --> 00:03:34,980 sensitive modes that I was describing earlier. Still, this has, the analysis of 38 00:03:34,980 --> 00:03:41,340 this has been a lot improved compared to the earlier searches. It uses advanced 39 00:03:41,340 --> 00:03:46,080 multi class deep neural network to separate the signal. Here you can see in 40 00:03:46,080 --> 00:03:52,260 the plot in black from the two main backgrounds that are ttbar in blue and 41 00:03:52,260 --> 00:03:59,970 the Zed to ll and Zed to tau tau in different shades of orange and then 42 00:04:00,000 --> 00:04:05,910 the discriminator that is produced from this neural network is used with some selection 43 00:04:05,910 --> 00:04:10,680 cuts to define some signal regions that you see plotted here in the bottom right. 44 00:04:11,520 --> 00:04:16,620 For same flavor leptons, where you have some backgrounds from the Zed and ttbar 45 00:04:16,620 --> 00:04:22,890 and then opposite flavor leptons, so emu, that is dominated by ttbar. And you can see if 46 00:04:22,890 --> 00:04:28,620 you look carefully the green, light green outline of the signal. This is however 47 00:04:28,620 --> 00:04:35,400 scaled by a factor 20. So the sensitivity of this analysis in the end is about 30 48 00:04:35,400 --> 00:04:41,010 times the standard model. This is a large improvement compared to the first searches 49 00:04:41,010 --> 00:04:45,180 in this final state, a factor eight or three compared to the older searches by 50 00:04:45,180 --> 00:04:52,890 ATLAS and CMS. It's not yet competitive with the best modes but it shows you 51 00:04:52,890 --> 00:04:57,540 that hopefully also for those modes, we will get large improvements when we go to 52 00:04:57,960 --> 00:05:04,200 new analyses on the full data set. Then we have another search for double Higgs boson 53 00:05:04,200 --> 00:05:11,340 production, but targeting VBF. So VBF has an even smaller cross section than gluon 54 00:05:11,340 --> 00:05:18,270 fusion for double Higgs production, it's less than two femtobarns. But it is 55 00:05:18,300 --> 00:05:26,730 interesting because it has in the Standard Model three contributions. One, first, that 56 00:05:26,730 --> 00:05:32,340 is again, production of a single Higgs boson, virtual, that then through the self 57 00:05:32,340 --> 00:05:40,080 coupling gives two Higgs bosons in the final state; we have, as before, a process, 58 00:05:40,170 --> 00:05:44,910 a contribution where only the coupling between the Higgs boson and the Standard 59 00:05:44,910 --> 00:05:50,280 Model fields appears but just two times and you get two Higgs bosons with no self coupling, 60 00:05:50,700 --> 00:05:53,610 but then there is this Kappa two V 61 00:05:55,080 --> 00:05:59,970 diagram where we have a quartic vertex with two vector bosons that scatter and 62 00:06:00,000 --> 00:06:06,690 produce two Higgs bosons. As it was, so, in the Standard Model or in the 63 00:06:06,690 --> 00:06:14,340 Standard Model effective theory, the Higgs is part of an SU two doublet, and, more in 64 00:06:14,340 --> 00:06:18,780 the way it was explained in the previous talk, the symmetry is linearly realized. 65 00:06:19,410 --> 00:06:26,160 and these two diagrams are tightly connected. Here is Kappa two v, has to be 66 00:06:26,250 --> 00:06:31,290 the square of Kappa v. And this creates a cancellation. However, if you go in more 67 00:06:31,290 --> 00:06:37,200 general extensions of the Standard Model, like the electroweak chiral Lagrangian that 68 00:06:37,200 --> 00:06:42,150 was described before where the Higgs is a generic scalar, you do not have this cancellation. 69 00:06:42,780 --> 00:06:46,770 And you would have potentially a very large increase in the VBF cross section 70 00:06:46,800 --> 00:06:54,240 because you will essentially violate unitarity in the scattering. So, ATLAS has 71 00:06:54,300 --> 00:07:00,540 deployed the search to look for this, based on the entire Run 2 data set, except the 72 00:07:00,540 --> 00:07:08,490 very early, very early part of it, focusing on the four b final state to have 73 00:07:08,490 --> 00:07:14,340 a large branching ratio. And targeting this kinematic that you get when the 74 00:07:14,340 --> 00:07:19,050 Kappa 2V parameter is different from one so you don't have the cancellation. 75 00:07:19,230 --> 00:07:25,290 Here the kinematics becomes much harder compared to a normal VBF double Higgs 76 00:07:25,290 --> 00:07:31,260 production. And so the analysis can afford very tight selection criteria to select 77 00:07:31,260 --> 00:07:36,780 VBF like events with one TeV invariant mass of the two jets, and then, once you are in 78 00:07:36,780 --> 00:07:41,910 this VBF phase space, you have in the central part of the detector double Higgs to four 79 00:07:41,910 --> 00:07:49,260 b, and so, the strategy of the earlier double Higgs to four b search from ATLAS 80 00:07:49,260 --> 00:07:55,830 on the partial data set is applied here. And so signal regions are 81 00:07:55,830 --> 00:08:03,630 defined in the invariant mass of the pairs of the two bbbar pairs, and then you 82 00:08:03,690 --> 00:08:07,980 draw a ring around it as a sideband that has been used to estimate the background 83 00:08:08,130 --> 00:08:12,870 from QCD production that would contaminate, would be below your signal, and 84 00:08:12,870 --> 00:08:16,890 in addition, to make the analysis more sensitive compared to the older searches, 85 00:08:17,190 --> 00:08:23,280 a b jet energy regression is used to sharpen the resolution of the jets and so make the two 86 00:08:23,280 --> 00:08:30,690 b invariant mass have a narrower peak for the signal. And still the 87 00:08:30,690 --> 00:08:34,980 extraction of the signal is focused on this scenario as I was saying of Kappa two V 88 00:08:34,980 --> 00:08:39,120 different from one and so the other couplings, including the self coupling are 89 00:08:39,120 --> 00:08:45,240 set to unity. And in the bottom right here, you can see the sensitivity of the 90 00:08:45,240 --> 00:08:48,540 analysis. So the cross section that the analysis can exclude, 91 00:08:50,010 --> 00:08:50,520 that 92 00:08:53,340 --> 00:08:58,200 becomes much worse if you go really to the Standard Model point because the 93 00:08:58,200 --> 00:09:04,950 kinematics is less extreme but that improves as you move away in kappa 2V. 94 00:09:05,580 --> 00:09:11,070 And the opposite behavior is for the cross section that is minimal around the Standard 95 00:09:11,070 --> 00:09:16,140 Model point and then increases. So at the Standard Model with this analysis, you 96 00:09:16,140 --> 00:09:21,870 would never see anything, this limit is at 500 times the Standard Model cross section. 97 00:09:22,170 --> 00:09:28,650 But, thanks to these two features, you can instead set the first limits on this Kappa 2V 98 00:09:28,650 --> 00:09:34,950 parameter at the LHC between minus half and three apsproximately. 99 00:09:36,870 --> 00:09:43,110 So finally, the other topic about the self coupling is, as described by the previous 100 00:09:43,110 --> 00:09:48,360 speaker, we can also constrain it from single Higgs production by looking at next 101 00:09:48,360 --> 00:09:53,430 to leading order contributions where the self coupling appears. These are small 102 00:09:53,430 --> 00:09:59,250 however, the, for example, for inclusive cross sections the largest effect is for 103 00:09:59,250 --> 00:10:04,560 pT Higgs varying the self Higgs coupling by plus or minus 100%. Compared to the standard 104 00:10:04,560 --> 00:10:09,570 model, the increase in the cross section is just about three and a half percent. 105 00:10:10,590 --> 00:10:14,820 These can be enhanced a bit if you use kinematical information like it's shown 106 00:10:14,820 --> 00:10:20,400 here, but only by a factor two, factor three, not much more. So you need good 107 00:10:20,400 --> 00:10:26,070 accuracy on single Higgs boson measurements. This was tested by the two 108 00:10:26,070 --> 00:10:32,340 collaborations in their latest single Higgs combinations. And here you can see 109 00:10:32,790 --> 00:10:39,840 the plots setting limits on the self coupling divided by the Standard Model value. 110 00:10:41,160 --> 00:10:46,080 And let me draw your attention to the bottom right one from ATLAS. This is just 111 00:10:46,080 --> 00:10:50,970 the expected sensitivity but just because it's more useful to make comparisons because 112 00:10:50,970 --> 00:10:59,190 you can see in blue here the constraints that you can put from single Higgs boson 113 00:10:59,190 --> 00:11:03,030 production and in black the ones that you can put from double Higgs boson production. 114 00:11:03,660 --> 00:11:08,130 And, well, the luminosity in the two cases is different, but still you can see they 115 00:11:08,130 --> 00:11:09,000 are comparable. 116 00:11:11,160 --> 00:11:13,980 This is good. However, there is a big 117 00:11:15,540 --> 00:11:20,040 disclaimer in the sense that for the double Higgs, what we're probing is double 118 00:11:20,040 --> 00:11:25,140 Higgs, for the single Higgs these couplings, these constraints are true if 119 00:11:25,200 --> 00:11:30,720 the only thing that changes compared to Standard Model is the self coupling and 120 00:11:30,750 --> 00:11:35,340 all the other couplings are fixed to Standard Model. You can relax a little bit and 121 00:11:35,340 --> 00:11:41,310 assign one scale factor to fermions or one scale factor to vector bosons, but as soon 122 00:11:41,310 --> 00:11:46,170 as you float both you will wash out the entire sensitivity at least with the 123 00:11:46,170 --> 00:11:53,730 present analysis. So we may get to this for in a more realistic fit, but this will 124 00:11:53,730 --> 00:12:01,050 take a long while and also more work from theory predictions in order to get all 125 00:12:01,050 --> 00:12:06,180 corrections and all next to leading order predictions as function of this self coupling 126 00:12:06,180 --> 00:12:11,880 and also all the EFT operators. Still, as summarized in this slide 12, the 127 00:12:11,880 --> 00:12:16,050 constraints that we have on the self coupling and you can see that, depending 128 00:12:16,050 --> 00:12:23,610 on the inputs you use, the experiment, and so on, we are between minus three 129 00:12:23,610 --> 00:12:32,340 minus five times Standard Model to a bit more than plus ten. And, so, not yet so 130 00:12:32,340 --> 00:12:40,140 close to it. This was for the self coupling. Let me now skip to the next topic that are 131 00:12:40,230 --> 00:12:45,510 rare and forbidden and beyond Standard Model decays. I've made the list of new 132 00:12:45,510 --> 00:12:52,650 results from 2020. There is one however, the Higgs to invisible, that is motivated by 133 00:12:52,650 --> 00:12:57,720 dark matter and so, I will skip entirely from this presentation and you will see it 134 00:12:57,720 --> 00:13:02,010 in the plenary session in the talk by Katherine in the session about dark 135 00:13:02,010 --> 00:13:09,750 matter. However, before jumping to these decays I want to say very quickly 136 00:13:09,750 --> 00:13:16,020 something about second generation fermion couplings. Luca has shown you that third 137 00:13:16,020 --> 00:13:20,310 generation fermion couplings are all observant and well measured. Second 138 00:13:20,310 --> 00:13:25,560 generation couplings are smaller, and so they are harder to probe. There are no new 139 00:13:25,560 --> 00:13:32,220 results compared to late last summer. And in the case of the muons, the state of 140 00:13:32,220 --> 00:13:37,050 the art was the ATLAS analysis from summer of last year based on the full data set. 141 00:13:37,470 --> 00:13:42,120 Here experimentally this is a simple analysis, but the branching ratio is so 142 00:13:42,120 --> 00:13:48,240 small that the off-shell tail of the Z above the signal is a factor of 1000 bigger than 143 00:13:48,240 --> 00:13:56,220 the Higgs to mumu signal. One can try to improve this by using smart categorization 144 00:13:56,220 --> 00:14:04,440 to select VBF like events but it remains a quite challenging analysis. And 145 00:14:04,440 --> 00:14:11,430 the result from ATLAS here you can see in the data minus background panel, that 146 00:14:11,490 --> 00:14:18,390 perhaps there is a very little tiny start of an excess. This is less than one sigma 147 00:14:18,690 --> 00:14:23,160 in terms of statistical significance. Also, because the signal strength measured 148 00:14:23,190 --> 00:14:28,710 is a half standard model with an uncertain go plus or minus 0.7, it's up to you to 149 00:14:28,710 --> 00:14:36,270 choose if it's a full half or empty half. Now, for cc bar similarly, we don't 150 00:14:36,300 --> 00:14:42,840 have new results to see from this year, the state of the art was the search from 151 00:14:42,990 --> 00:14:48,240 CMS on a partial dataset that was released again in the summer. Here the 152 00:14:48,240 --> 00:14:52,770 branching ratio is not so small, but it's still a factor 20 smaller than Higgs to 153 00:14:52,770 --> 00:14:57,450 b bbar that wasn't an easy search to begin with. And so this is much harder 154 00:14:57,450 --> 00:15:03,360 than that. CMS deployed a quite advanced analysis targeting vector boson 155 00:15:03,360 --> 00:15:08,100 associated production in all the three final states, Z to ll, W to l nu and Z 156 00:15:08,100 --> 00:15:13,080 to two neutrinos. And even with the combination of a resolved analysis that is 157 00:15:13,080 --> 00:15:18,780 like the Higgs to b bbar with the Higgs decaying in two jets, with a boosted 158 00:15:18,780 --> 00:15:24,420 analysis similar to what Luca described for boosted Higgs to b bbar just recently, 159 00:15:25,860 --> 00:15:32,850 and despite all this, the sensitivity that CMS can get is only around 40 times the 160 00:15:32,850 --> 00:15:39,090 Standard Model with them setting an upper limit at about 70 times the Standard Model. So for the muons, 161 00:15:39,090 --> 00:15:44,040 we'll probably get there fairly often, like in Run 3, for Higgs to c cbar 162 00:15:44,040 --> 00:15:45,210 it's gonna be more a long, 163 00:15:46,650 --> 00:15:47,430 a long way. 164 00:15:48,750 --> 00:15:55,410 Now jumping to new results, instead, there is one from, that was just shown for the 165 00:15:55,410 --> 00:16:00,600 first time in this conference, from CMS, trying to look, probe couplings 166 00:16:00,630 --> 00:16:04,710 To even lighter quarks than the charm. Of course, in the Standard Model, these 167 00:16:04,710 --> 00:16:10,230 are vanishingly small. However, in extensions of the Standard Model motivated 168 00:16:10,230 --> 00:16:15,030 probably by flavour, these can be largely enhanced. And so you could have in this case 169 00:16:15,030 --> 00:16:23,700 production of a Zed boson plus a rho or a phi meson, so to the light q qbar states, 170 00:16:23,700 --> 00:16:29,370 through diagrams of this form that could be largely enhanced. And this search uses clean 171 00:16:29,370 --> 00:16:35,580 final states of rho going to pi pi or phi going to K K and so you have these two 172 00:16:35,580 --> 00:16:41,760 tracks that have to be isolated, close by and at least one of the tracks have to be of 173 00:16:41,760 --> 00:16:46,860 high momentum so that you reject the otherwise overwhelming background of Z plus 174 00:16:46,860 --> 00:16:52,470 jets. And once you do this, since everything is very well measured in the 175 00:16:52,470 --> 00:17:00,630 detector, you can build a resonant mass of the signal at 125 GeV and the background can 176 00:17:00,630 --> 00:17:06,870 be parameterized with some analytic functions. And this allows to set limits 177 00:17:06,900 --> 00:17:14,370 on this kind of decays. And for this search they are between point two and sorry 178 00:17:14,370 --> 00:17:18,570 point three and 2% depending on the resonance, and also the polarization that 179 00:17:18,570 --> 00:17:23,610 you assume that gives you different acceptance. These are the first limits in 180 00:17:23,610 --> 00:17:27,570 this final state, but they still correspond to about 1000 times the 181 00:17:27,570 --> 00:17:34,650 Standard Model. Now moving to another example of something that has a small 182 00:17:34,650 --> 00:17:38,640 branching ratio in the Standard Model, I want to discuss Higgs to Zed gamma that was 183 00:17:38,640 --> 00:17:43,800 released by ATLAS and presented at a CERN seminar just a couple of weeks ago. 184 00:17:45,240 --> 00:17:49,950 This is the only diboson decay of the Higgs that we haven't observed then, in 185 00:17:49,950 --> 00:17:55,170 fact, all the others have been seen since quite a long while. But the problem is 186 00:17:55,170 --> 00:18:00,780 that this has a small branching ratio, comparable to Higgs to four leptons, but, once 187 00:18:00,780 --> 00:18:06,270 you take a look at leptonic Z's, but a larger background from Standard Model Zed plus 188 00:18:06,270 --> 00:18:11,700 gamma. However it's quite important to try to probe this because if you go in 189 00:18:12,930 --> 00:18:20,220 extensions of the Standard Model typically symmetries tie together these four 190 00:18:20,340 --> 00:18:26,700 vertices Higgs to WW, Higgs to ZZ Higgs to gamma, gamma and Higgs to Zed gamma. So, new physics 191 00:18:26,700 --> 00:18:32,340 should give you a correlated deviation across these if it respects this symmetries. 192 00:18:32,640 --> 00:18:36,330 So, for example, in the in the Standard model effective field theory you should 193 00:18:36,330 --> 00:18:40,530 see a correlated deviations again in these, if you measure only three you cannot 194 00:18:40,620 --> 00:18:46,080 resolve it but if you measure all four you could. And this is again a quite hallenging 195 00:18:46,080 --> 00:18:52,050 search, similarly to Higgs to mu mu you have to try to get your signal peak as narrow as possible 196 00:18:52,050 --> 00:18:55,740 and your signal to background as good as possible. For example, selecting VBF 197 00:18:55,740 --> 00:18:56,370 events. 198 00:18:58,890 --> 00:19:01,860 And I have put here a plot 199 00:19:01,860 --> 00:19:03,210 [you have five minutes left] 200 00:19:03,270 --> 00:19:08,670 Yes, with all the categories and in the background subtracted window you can start 201 00:19:08,670 --> 00:19:13,470 to see a bit larger excess compared to Higgs to mu mu. Now that was two 202 00:19:13,470 --> 00:19:21,210 sigma sorry one sigma, this is two sigma. So, not yet evidence, and this in part is 203 00:19:21,210 --> 00:19:25,650 helped by the fact that a positive fluctuation is seen, so the signal strength is 204 00:19:25,680 --> 00:19:32,310 two plus or minus one, but still we may be seeing hints of the first Higgs to Zed gamma signal. Now, let 205 00:19:32,310 --> 00:19:38,730 me move instead to BSM physics and searches for light pseudoscalars 206 00:19:39,330 --> 00:19:46,530 from extensions of say the MSSM and starting again with a new paper from ATLAS on 207 00:19:47,670 --> 00:19:54,150 production of this light pseudoscalar in association with the Zed for light masses 208 00:19:54,150 --> 00:19:57,900 of this particle. So we look for something that is less than four GeV and decays 209 00:19:57,960 --> 00:20:03,270 hadronically, this can only be seen, this can only be reconstructed as a jet because if 210 00:20:03,270 --> 00:20:08,580 you go for an inclusive thing there is not much more than you can do. But you can use 211 00:20:08,640 --> 00:20:14,160 a multilayer perceptron, so essentially a neural network, to try to regress what is the 212 00:20:14,160 --> 00:20:18,900 mass of the particle that gives origin to the jet and you can see that from this plot 213 00:20:18,900 --> 00:20:24,210 that for light particles like half a GeV you can really separate them from heavier 214 00:20:24,210 --> 00:20:28,560 particles and from the continuum background. And you can also use the same 215 00:20:28,560 --> 00:20:33,300 strategy to produce a discriminator that selects signal and rejects the background 216 00:20:33,330 --> 00:20:40,950 from Z plus jets. With that, you can enhance your purity and then try to reconstruct a 217 00:20:40,950 --> 00:20:45,930 signal peak in the lepton lepton jet mass and build your signal region. 218 00:20:47,520 --> 00:20:52,800 Unfortunately, a very good data to Monte Carlo agreement is seen not just in control 219 00:20:52,800 --> 00:20:58,350 regions, but also in the signal region. And so there is no evidence for these new 220 00:20:58,350 --> 00:21:02,580 particles. Limits can be set depending on the decay modes that you assume, for 221 00:21:02,580 --> 00:21:07,890 example, here it is for a going to a pair of gluons. And for light particles 222 00:21:07,890 --> 00:21:12,450 where the sensitivity is better, you can set, ATLAS can set branching ratio limits 223 00:21:12,450 --> 00:21:19,650 that go as low as about 30%. Still for light particles there is a new paper also 224 00:21:19,680 --> 00:21:26,790 submitted a couple of days ago from CMS for now for pair production of particles in a 225 00:21:27,330 --> 00:21:31,920 exclusive final state now, one a going to a pair of muons and one a going into a 226 00:21:31,920 --> 00:21:36,240 pair of taus. Again, we're looking at light particles. And so there is a 227 00:21:36,240 --> 00:21:41,310 challenge that the decay products of the two taus will start to overlap. So CMS 228 00:21:41,340 --> 00:21:46,650 deployed dedicated reconstruction, tagging first a muon, removing it and then 229 00:21:46,650 --> 00:21:50,160 trying to reconstruct, a muon from a decay of a tau of course, and then 230 00:21:50,160 --> 00:21:55,050 trying to reconstruct the hadronically decaying tau from the from the remaining 231 00:21:55,050 --> 00:22:01,680 decay products and this allow to boost the efficiency by 50% for masses of say 232 00:22:01,680 --> 00:22:08,460 five to ten GeV. And then you, one can use the fact that the dimuon mass is 233 00:22:08,460 --> 00:22:12,900 measured very precisely and the signal should be resonant there and then also 234 00:22:12,900 --> 00:22:18,210 fitted simultaneously in two dimensions not fit with the invariant mass of the 235 00:22:18,210 --> 00:22:22,980 whole system that should resonate at the Higgs mass. And this allows to set quite 236 00:22:22,980 --> 00:22:30,390 stringent limits on this final state, between point .02 and .08%. That's 237 00:22:30,390 --> 00:22:34,710 a function of the mass with a little bit worse sensitivity around the Upsilon 238 00:22:34,710 --> 00:22:41,250 peak of course. There is another search for pair produced light scalars but 239 00:22:41,250 --> 00:22:46,170 instead on hadronically decays, hadronic decays, submitted by Atlas 240 00:22:46,200 --> 00:22:54,210 yesterday. Now, if you look for Higgs to a a to to four b's, and especially at low mass, 241 00:22:54,240 --> 00:22:58,860 you could not, you cannot trigger these events at the LHC at the moment. So the 242 00:22:58,860 --> 00:23:03,660 search is done requiring a Zed associated production with the Zed going leptonically 243 00:23:03,690 --> 00:23:09,870 to select the events. And then in order to catch both cases where the b bbar give 244 00:23:09,870 --> 00:23:15,510 rise to two jets or the b bbar are captured by a single jet when using 245 00:23:15,510 --> 00:23:21,270 standard reconstruction, a wider cone is used to re cluster the standard jets in 246 00:23:21,270 --> 00:23:25,320 order to make sure to catch one of the, each of the a bosons into a single jet. 247 00:23:25,710 --> 00:23:31,860 And then a fancy substructure and flavor tagger can be used to discriminate between 248 00:23:32,070 --> 00:23:37,440 this process compared to just a jet that contains a single b quark. In addition, 249 00:23:37,440 --> 00:23:43,470 one can set kinematic constraints that the two a bosons have have the same mass 250 00:23:43,500 --> 00:23:46,800 and that the a pair has to have the mass of the Higgs. 251 00:23:49,320 --> 00:23:53,250 Signal regions and control regions can be made depending on the number of loose and 252 00:23:53,280 --> 00:24:01,530 tight tags of the two a legs and and then this allows to set limits in the mass 253 00:24:01,530 --> 00:24:08,160 range between 15 and 30 GeV at high mass at some point the standard Higgs to aa 254 00:24:08,160 --> 00:24:14,340 to four b analysis takes over. So let me get to the last search. [So Giovanni 255 00:24:14,340 --> 00:24:16,200 your time is is actually up]. 256 00:24:17,400 --> 00:24:25,080 Now, okay, I'll be extremely quick on this. It's just a search for Zed Zed to.. 257 00:24:25,740 --> 00:24:33,840 Zed dark Zed dark or Zed Zed dark to four leptons. And for the Zed plus Zed dark 258 00:24:33,840 --> 00:24:38,580 you can find the Zed requiring four leptons to be on the Higgs peak and then scan the 259 00:24:38,580 --> 00:24:45,660 mass of the light there and set limits down to 10 to the minus four. And for 260 00:24:45,660 --> 00:24:52,230 Zed dark Zed dark is a similar strategy but you want to find two light like mass 261 00:24:52,260 --> 00:24:57,930 pairs and so you scan a box around the diagonal of the masses of two leptons. And 262 00:24:57,930 --> 00:25:02,070 since there is very little events there you can set extremely tight limits about 263 00:25:02,100 --> 00:25:09,990 10 to the minus six for this branching ratio. This search on MSSM A to tau tau I think, 264 00:25:10,230 --> 00:25:16,860 at this moment I will just skip then, it's a very classical search for MSSM Higgs to tau tau that has 265 00:25:16,860 --> 00:25:22,350 been done in the past, it's just updated to the full luminosity. So it has better 266 00:25:22,350 --> 00:25:29,880 sensitivity than what was done up to now and one can get limits on tangent beta 267 00:25:29,880 --> 00:25:39,390 as low as eight for even one TeV tau tau masses. For the high luminosity LHC 268 00:25:39,390 --> 00:25:44,160 we don't have really new new results since European strategy updates. So back then we 269 00:25:44,160 --> 00:25:48,870 had shown that we can set single Higgs boson observables we can probe them to 270 00:25:49,320 --> 00:25:55,020 better than 2 few% level: cross sections, branching ratios, couplings and 271 00:25:55,020 --> 00:26:00,450 differential distributions, and we could we predict to be able to observe when 272 00:26:00,450 --> 00:26:05,040 combining ATLAS and CMS double Higgs production or at least get close to it 273 00:26:05,040 --> 00:26:09,570 with four sigma and measure the self coupling to plus or minus 50%. 274 00:26:11,130 --> 00:26:15,390 So, concluding, for the Higgs boson self coupling we have 275 00:26:16,680 --> 00:26:21,030 new developments, we're improving analysis, we're starting to probe VBF double Higgs 276 00:26:21,030 --> 00:26:25,650 production to test new couplings. We expect to have much stronger results when 277 00:26:25,650 --> 00:26:29,730 the LHC full Run 2 data set will be analyzed in the channels that have higher 278 00:26:29,730 --> 00:26:35,550 sensitivity like bb gamma gamma or bb tau tau that hasn't happened yet. And then we have quite many 279 00:26:35,550 --> 00:26:41,700 searches that probe into the unknown: rare decays, or decays into BSM particles. 280 00:26:42,840 --> 00:26:48,000 There are no big excesses or evidences for signals yet, but there is many more 281 00:26:48,000 --> 00:26:52,770 searches to try and many searches to extend to the full Run 2 data set and 282 00:26:52,770 --> 00:26:56,490 beyond towards the high luminosity LHC. Thank you. 283 00:26:58,950 --> 00:27:01,260 Great, thanks a lot, Giovanni. 284 00:27:03,540 --> 00:27:07,050 Please, if you have any questions, go ahead and raise your hands. 285 00:27:12,929 --> 00:27:18,089 All right, I don't see any hands. I had a curiosity. It was back. When you were 286 00:27:18,089 --> 00:27:20,489 talking about the background for the 287 00:27:21,840 --> 00:27:24,960 the Higgs to phi I thing. 288 00:27:26,460 --> 00:27:29,430 When you were showing this it looked like you said that there was a simple 289 00:27:29,430 --> 00:27:34,020 polynomial fit. It looked like the background shape was somewhat complex. I 290 00:27:34,020 --> 00:27:37,260 was curious if you could say a little bit about the background fit. So 291 00:27:39,450 --> 00:27:44,340 now it's the shape is an analytic function. Now I don't remember exactly 292 00:27:44,370 --> 00:27:50,220 what analytic function. It has a turn on. That's why we ended up with not having a 293 00:27:50,220 --> 00:27:54,660 lot of sideband on the left in order to not have to model this, this turn on. In this 294 00:27:54,660 --> 00:27:59,910 region here it's described by fairly smooth analytic functions. 295 00:28:01,709 --> 00:28:03,299 If this is the. 296 00:28:03,329 --> 00:28:07,829 Yeah, I was just curious how you validated it because it looks like as you're saying 297 00:28:07,829 --> 00:28:11,099 you're you're avoiding a turn on but it also looks like the shape changes somewhat 298 00:28:11,099 --> 00:28:12,989 during the range. I was just curious what 299 00:28:14,490 --> 00:28:19,740 that is. The usual procedures that are done for like gamma gamma, I mean like bias 300 00:28:19,740 --> 00:28:24,600 studies to test different shapes that still are able to fit the data and see 301 00:28:24,600 --> 00:28:27,150 whether they would produce a spurious signal or not. 302 00:28:28,890 --> 00:28:31,920 Okay, thanks. Any other questions? 303 00:28:38,580 --> 00:28:42,510 All right, if I don't see any more, then Christophe, if you want to 304 00:28:42,510 --> 00:28:46,890 go ahead and wrap up. I wanted to thank the four speaker that did a complete 305 00:28:46,890 --> 00:28:54,630 overview, and also all the attendees. And as I said in the chat, I mean, at 306 00:28:54,630 --> 00:29:01,320 least Maggie and Luca are waiting for you in the Zoom room. You can connect if you 307 00:29:01,320 --> 00:29:02,970 want to discuss more with them.