PoS(EDSU2018)032. CT-PPS Physics Results and Prospects. Justin Williams. On behalf of the CMS and TOTEM Collaborations

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1 CT-PPS Physics Results and Prosects On behalf of the CMS and TOTEM Collaborations A unique search for hysics beyond the standard model in exclusive dihoton events is resented. By measuring intact rotons from the events in the forward region, we can significantly reduce the background, leading to the best sensitivity to anomalous couling behavior. Furthermore, by studying the rocess of γγ γγ we can shed light on the high mass regions of Axion-like articles, and otential dark matter candidates. 2nd World Summit: Exloring the Dark Side of the Universe June, 2018 University of Antilles, Pointe-á-Pitre, Guadeloue, France Seaker. c Coyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0). htt://os.sissa.it/

2 1. Introduction Tyically the LHC is used as a roton-roton collider; however, there is such a large amount of hotons roduced in the beam ie that we can use the LHC as a hoton-hoton collider. Events in which hotons collide are interesting to study because they may be sensitive to beyond standard model (BSM) hysics[1][2]. We roose to use the CMS Precision Proton Sectrometer (CT-PPS) to study these exciting events in a unique way by using roton tagging techniques. The tagging of outgoing rotons allows for a strong background suresion that we will see leads to a great sensitivity in the high mass region of dihoton events. The aer begins with a descrition of CT-PPS followed by an overview of the first hysics results. Then there will be a discusion of the backgrounds and motivations before the conclusion. 2. CMS Precision Proton Sectrometer What is CT-PPS? Figure 1: A schematic of one side of CT-PPS. Immediately to the right of the CMS detector are the LHC magnets. Further to the right are the Roman Pot stations where intact rotons are detected. Originally a joint roject between CMS and TOTEM[3], CT-PPS is designed to measure intact rotons on either side of CMS, about 200 m away from the interaction oint. After an interaction in CMS, rotons are ushed just outside of the beam enveloe by the LHC magnets due to the loss of momentum. These rotons are then detected further downstream where the momentum loss can be measured based on the osition where the rotons are found. The secific variable of interest to be calculated is the fractional momentum loss ξ which can be used to correlate the forward rotons with the central system within CMS. The detectors are housed within Roman Pots, which use a combination of silicon stris and ixels to measure the x and y ositions of the rotons. Fig. 1 shows one side of the CT-PPS system. A symmetric set of detectors is resent on the other side as well. 3. Physics Results From CT-PPS Joint CMS and TOTEM roject: htts://cds.cern.ch/record/ , see TheFabio s first analysis talkublished using CT-PPS was a study of hoton-induced dileton events. This was the first observation of this roccess at high mass using intact rotons. Fig. 2 shows three LHC magnets bend scattered rotons out of the beam enveloe different rocesses generating oosite sign letons by way of hoton-hoton interactions. For the sake Detect of this analysis, scattered the first rotons two rocesses a feware mm treated from as signal the whereas beam (both the thirdsides case where of CMS) both rotons dissociate, was treated as a background. First data taking in 2016: 15 fb 1 This analysis was erformed at nominal otics and ileu conditions for the LHC and yielded results that were recently ublished[4]. 1

3 l l exclusive! `+` events (the left diagram) starts only above m(`+` ) 400 GeV, where the standard model cross section is small. By selecting events with only a single tagged roton, the samle contains a mixture of lower mass exclusive and single-dissociation (! `+`, semiexclusive ) rocesses with higher cross sections. The right diagram of Fig. 1 is considered background, and contributes if a roton from the diffractive dissociation is detected, or if a article detected in CT PPS from another interaction in the same bunch crossing (ileu), or from beam-induced background is wrongly associated with the dileton system. A air of letons from a Drell Yan rocess can also mimic a signal event if detected in combination with a ileu roton. `+ `+ `+ ` ` ` Figure 1: Production of leton airs by gg fusion. The exclusive (left), single roton dissociation or semiexclusive (middle), and double roton dissociation (right) toologies are shown. The left and middle rocesses result in at least one intact final-state roton, and are considered signal in this analysis. The rightmost diagram is considered to be a background rocess. Figure 2: Feyman diagrams of events roducing two oosite sign letons in the final state. For the rocess on the far left, both rotons remain intact in the final state. For the middle rocess, only one roton remains 17 intact while the other roton dissociates. On the right is the case when both rotons dissociate. ) + ξ(l CMS+TOTEM 2016, L = 9.4 fb, CT-PPS left arm No accetance for any RP No accetance for near RP + Matching l l events + Non-matching l l events + Out of accetance l l events s = 13 TeV Red: µ + µ + Blue: e e ξ(rp) ) + ξ(l CMS+TOTEM 2016, L = 9.4 fb, CT-PPS right arm No accetance for any RP No accetance for near RP + Matching l l events + Non-matching l l events + Out of accetance l l events s = 13 TeV Red: µ + µ + Blue: e e ξ(rp) Figure 11: Correlation between the fractional values of the roton momentum loss measured in Figure 3: the Both central lots dileton show dileton system, events x(`+` that ), and were in the found RPs, with x(rp), at least for both onerps corresonding each armroton combined. measured in CT-PPS. The The 45 (left) lot andis 56 for (right) events arms with area shown. roton detected The hatched on the region left side corresonds of CMSto and the the kinematical right lot is for events with region a roton outside detected the accetance on the right of both sidethe ofnear CMS. and The fardiagonal RPs, while linethe isshaded where events (ale blue) will be region that have a erfectcorresonds matching between to the the region ξ value outside of the thecentral accetance systemofand the the near ξ RP. value For ofthe events forwardinroton(s)[4]. which a track is detected in both, the x value measured at the near RP is lotted. The horizontal error bars indicate the uncertainty of x(rp), and the vertical bars the uncertainty of x(`+` ). The Theevents events labeled that out wereofobserved accetance canarebethose seeninalong whichthe x(µ + diagonal µ ) corresonds line ontothe a signal lotsroton in Fig. 3. outside the RP accetance; in these events a background roton is detected with nonmatching Events along kinematics. the diagonal line are events which have a matching between the ξ value of the central letons and the ξ measurement of the forward rotons in CT-PPS. 12 µ + µ events and 8 e + e -1 CMS+TOTEM 2016, L = 9.4 fb, s = 13 TeV events were observed. Comared with 8 the exected background of 1.49±0.07(stat)± 0.53(syst) for µ + µ events and 2.36± 0.09(stat)±0.47(syst) 6 for e + e events, µ + µ this is an observation at the 5.1σ level. e + e 4 The success of this analysis 2indicates that the alignment, triggering, and otics are all well understood within CT-PPS and that the concet of forward roton tagging can be very succesful 0 for other analyses. ) l + y(l sector 45 sector Anomalous Quartic Gauge Coulings No accetance Accetance in 2-N/F Accetance in 2-F Double-arm accetance With the roton tagging techniques 8 in CT-PPS 2 comes 3 the ourtunity to search for anomalous 4 + m(l l ) (GeV) quartic gauge coulings (AQGC) in a unique way. Fig. 4 shows three such coulings that can be exlored Figure using 12: Exected roton tagging. accetance The regions four-hoton in the raidity anomalous vs. invariant couling mass will lane be the overlaid mainwith focus of the observed dimuon (closed circles) and dielectron (oen circles) signal candidate events. The this discussion double-arm as itaccetance is sensitiverefers to other to exclusive BSM coulings events, that! `+` will be. discussed Following the in section CMS convention, of thethese ositive events (negative) that we raidity can exlot regionfor corresonds this analysis to the are45 the (56) intact LHC sector. rotons in the final 6. The characteristics state, and the exclusive diboson roduction within CMS. The ower of this study is that we can continuously oerating a near-beam roton sectrometer at a high-luminosity hadron collider. analyse the totality of the rocess by measuring every final state article. 2

4 Figure 4: Feyman diagrams of three different anomalous quartic gauge coulings resulting from hoton fusion. From left to right, the diagrams are γγ γγ, γγ γz, γγ W + W. 5. Backgrounds Figure 5: A histogram for various tyes of backgrounds (colored lines) with resect to two signals of different couling values. The histogram is lotted as a function of the dihoton mass[6]. The signal for the rocess of interest consists of two rotons identified in the forward detectors in coincidence with two hotons in the central detector. Using the Forward Physics Monte Carlo (FPMC)[5], Fig 5 shows the significance of the tyes of backgrounds that could fake the signal[6]. While all backgrounds are considered such as double omeron exchange, H γγ, misidentification of letons and jets, ileu, Drell-Yan, etc., the only background that makes a significant contribution at high dihoton mass is that from ileu. At the LHC, ackets of rotons are collided er bunch crossing. While our intent is to detect rotons coming from the same event as the rocess that created two hotons, sometimes this is not the case. For the case of the ileu background, two hotons may be created in CMS, but rotons may be measured that actually come from an unrelated event. This overlaing of uncorrelated events creates a very significant background: for examle, in 2016, there were u to 50 ileu vertices er bunch crossing. The way we can suress this ileu background is by exloiting momentum conservation. Secifically, the mass and raidity of the centrally roduced system as measured in the central CMS aaratus and in CT-PPS are required to match. Fig. 6 shows that by requiring this matching, the signal eaks well above the background coming from ileu. 3

5 Figure 6: Dihoton to missing roton mass ratio (left) and raidity difference (right) distributions for signal considering two different couling values ( 12 and 13 GeV 4 ) and for backgrounds after requirements on hoton T, dihoton invariant mass, T ratio between the two hotons and on the angle between the two hotons. The integrated luminosity is 300 fb 1 and the average ileu is µ = 50[6]. Figure 7: A lot of the current exclusion regions for ALPs from various different exeriments. On the horizontal axis is the ALP mass and on the vertical axis is the couling strength[7]. 6. Alications An additional benefit of studying four-hoton anomalous coulings is the extra insight on BSM models of axion-like articles (ALP) and dark matter candidates. We can exlore new mass regimes of ALP roduction via hoton exchange using roton tagging in CT-PPS[7]. This search even imroves uon the standard mass reach of the LHC for ALPs. Fig. 7 shows the kinematic regimes that have already been excluded from various exeriments such as astroarticle and collider searches. The figure also shows the region that can be exlored by means of roton tagging. In a similar way, we can study the case in which a dark matter article - a olarizable dark article - is the mediator in the four-hoton loo. It is roosed to use the γγγγ couling to search for such a article as it automatically induces four hoton legs[8]. It has been shown that there is otential to discover the existence of this article at a 5σ significance at the LHC[8]. 4

6 7. Conclusion In 2016, CT-PPS showed for the first time the feasability of oerating a near-beam roton sectrometer at a high-luminosity collider on a regular basis. From the data that has been acquired, the first observation was made of the rocess γγ l + l using roton tagging. The success of the observation has aved the way for BSM searches of anomalous coulings, ALPs, dark matter, and other interesting hysics. Through 2016 and 2017, CT-PPS has taken over 55 fb 1 of data and has lans to continue this level of rogress going forward. References [1] D. d Enterria and G. G. da Silveira, Phys. Rev. Lett. 111, (2013) Erratum: [Phys. Rev. Lett. 116, no. 12, (2016)] doi:.13/physrevlett ,.13/physrevlett [arxiv: [he-h]]. [2] J. de Favereau de Jeneret et al., arxiv: [he-h]. [3] M. Gallinaro [CMS and TOTEM Collaborations], AIP Conf. Proc. 1819, no. 1, (2017) doi:.63/ [arxiv: [hysics.ins-det]]. [4] A. M. Sirunyan et al. [CMS and TOTEM Collaborations], JHEP 1807, 153 (2018) doi:.07/jhep07(2018)153 [arxiv: [he-ex]]. [5] M. Boonekam, A. Dechambre, V. Juranek, O. Keka, M. Rangel, C. Royon and R. Staszewski, arxiv: [he-h]. [6] S. Fichet, G. von Gersdorff, O. Keka, B. Lenzi, C. Royon and M. Saimert, Phys. Rev. D 89, (2014) doi:.13/physrevd [arxiv: [he-h]]. [7] C. Baldenegro, S. Fichet, G. von Gersdorff and C. Royon, JHEP 1806, 131 (2018) doi:.07/jhep06(2018)131 [arxiv: [he-h]]. [8] S. Fichet, JHEP 1704, 088 (2017) doi:.07/jhep04(2017)088 [arxiv: [he-h]]. 5