Flavour independent searchesfor hadronically decaying neutral Higgs bosons

Abdallah, J.; Abreu, P.; Adam, W.; Adžić, P.; Albrecht, Thomas; Alderweireld, T.; Alemany–Fernández, R.; Allmendinger, T.; Allport, P. P.; Amaldi, U.; Amapane, N.; Amato, S.; Anashkin, E.; Andreazza, A.; Andringa, S.; Anjos, N.; Antilogus, P.; Apel, W. D.; Arnoud, Y.; Ask, S.; Åsman, B.; Augustin, E.; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D. Y.; Barker, J.; Baroncelli, A.; Battaglia, M.; Baubillier, M.; Becks, K. H.; Begalli, M.; Behrmann, A.; Ben-Haim, E.; Benekos, N.; Benvenuti, A. C.; Bérat, C.; Berggren, M.; Berntzon, L.; Bertrand, Daniel; Besançon, M.; Besson, N.; Blöch, D.; Blom, M.; Bluj, M.; Bonesini, M.; Boonekamp, M.; Booth, Laurence; Borisov, G.; Botner, O.; Bouquet, B.; Bowcock, T. J. V.; Boyko, I. R.; Bračko, M.; Brenner, R.; Brodet, E.; Brückman, P.; Brunet, Michel; Bugge, L.; Buschmann, P.; Calvi, M.; Camporesi, T.; Canale, V.; Carena, F.; Castro, N. F.; Cavallo, F. R.; Chapkin, M.; Charpentier, Ph.; Checchia, P.; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, U.; Cieślik, K.; Collins, P.; Contri, R.; Cosme, G.; Cossutti, F.; Costa, J. Goncalves Pinto Firmino Da; Crennell, D.; Cuevas, J.; D’Hondt, J.; Dalmau, J.; Silva, T. da; Silva, W. Da; Ricca, G. Della; Angelis, A. De; Boer, W. De; Clercq, C. De; Lotto, B. De; Maria, N. De; Min, A. De; Paula, L. De; Ciaccio, L. Di; Simone, A. Di; Doroba, K.; Drees, J.; Dris, M.; Eigen, G.; Ekelöf, T.; Ellert, M.; Elsing, M.; Santo, C. E.; Fanourakis, G.; Fassouliotis, D.; Feindt, M.; Fernández, J. P.; Ferrer, A.; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, M.; García, C.; Gavillet, Ph.; Gazis, E. N.; Gokieli, R.; Golob, B.; Gómez-Ceballos, G.; Gonçalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, K.; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, V.; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S. O.; Holt, J. M.; Houlden, A.; Hultqvist, K.; Jackson, Neil; Jarlskog, G.; Jarry, P.; Jeans, D.; Johansson, K. E.; Johansson, D.; Jönsson, P.; Joram, C.; Jungermann, L.; Kapusta, F.; Katsanevas, S.; Katsoufis, E.; Kernel, G.; Kerševan, B. P.; Kerzel, U.; Kiiskinen, A.; King, T.L.; Kjaer, J.; Kluit, P.; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lämsä, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, J.; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, Helena J. Nussenzveig; Lopez, M.; Loukas, D.; Lutz, P.; Lyons, L.; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Maréchal, B.; Margoni, M.; Marin, J. C.; Mariotti, C.; Μάρκου, Α.; Martínez-Rivero, C.; Mašík, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Nulty, R. Mc; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Mönig, K.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S. Carrillo; Morettini, P.; Muêller, U.; Muenich, K.; Mulders, M.; Mundim, L.; Murray, W. J.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F. L.; Nawrocki, K.; Nicolaidou, R.; Nikolenko, M.; Obłąkowska-Mucha, A.; Obraztsov, V.; Olshevski, A. G.; Onofre, A.; Orava, R.; Österberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, Paloma de; Pałka, H.; Papadopoulou, D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, A.; Petrolini, A.; Piedra, J.; Pieri, L.; Pierre, F.; Pimenta, M.; Piotto, E.; Podobnik, T.; Poireau, V.; Pol, E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Rameš, J.; Read, A. L.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, P.; Richard, F.; Řídký, J.; Rivero, M.; Rodriguez, D. Rodriguez; Romero, A.; Ronchese, P.; Roudeau, P.; Rovelli, T.; Ruhlmann-Kleider, V.; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Segar, A. M.; Sekulin, R.; Siebel, M.; Sisakian, A. N.; Smadja, G.; Smirnova, O.; Sokolov, A.; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M. M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli, T.; Taffard, C.; Tegenfeldt, F.; Timmermans, J.; Tkatchev, L. G.; Tobin, M.; Todorovova, S.; Tomé, B.; Tonazzo, A.; Tortosa, P.; Trávničék, P.; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, C.; Turluer, M. L.; Tyapkin, A.A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, G.; Dam, P. Van; Eldik, J. Van; Lysebetten, A. Van; Remortel, N. Van; Vulpen, I. van; Vegni, G.; Veloso, F.; Vénus, W.; Verdier, P.; Verzi, V.; Vilanova, D.; Vitale, L.; Vrba, V.; Wahlen, H.; Washbrook, J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, D.; Zhuravlov, V.; Zimin, I.; Zintchenko, A.; Župan, M.

doi:10.1140/epjc/s2005-02353-3

Cited by 9 publications

(4 citation statements)

References 27 publications

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“…The set of LHC (and LEP) searches that we consider is listed in table 2, where the mass range and the luminosity of a given search is mentioned. Concerning the LEP constraints, we employ the search looking for Higgs-like state decaying into bb final state [60] and into hadrons [61], which provide bounds on the C 2 φZZ coupling times the relevant branching ratio. We will choose the strongest of the two constraints for every point of our parameter space and we will show only one common line for the LEP bounds.…”

Section: Gauge-philic Dilaton Modelmentioning

confidence: 99%

A light dilaton at the LHC

Ahmed

Mariotti

Najjari

2020

J. High Energ. Phys.

137

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In this paper, we explore the possibility that a light dilaton can be the first sign of new physics at the LHC. The dilaton could emerge in approximate scale invariant UV completions of the SM as the Goldstone boson associated with the spontaneous breaking of the scale invariance. We study in detail the phenomenology of the dilaton at the LHC in the mass range of [10-300] GeV including the case where the dilaton can mix with the SM Higgs boson, leading to an interesting interplay between direct and indirect constraints. A possibility that the dilaton acts as a portal to a dark sector is also considered. As a minimal realization, the dark sector includes a dark photon lighter than the dilaton implying sizeable missing energy signatures. Several simplified benchmark models that can encode different UV completions are discussed, for which we scrutinize the current and future LHC reach.

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Section: Gauge-philic Dilaton Modelmentioning

confidence: 99%

A light dilaton at the LHC

Ahmed

Mariotti

Najjari

2020

J. High Energ. Phys.

137

View full text Add to dashboard Cite

show abstract

“…2. Concerning the LEP constraints, we employ the search looking for Higgs-like state decaying into b b final state [58] and into hadrons [59], which provide bounds on the C 2 φZZ coupling times the relevant branching ratio. We will choose the strongest of the two constraints for every point of our parameter space and we will show only one common line for the LEP bounds.…”

Section: Details On Implementation Of Collider Boundsmentioning

confidence: 99%

A light dilaton at the LHC

Ahmed,

Mariotti,

Najjari

2019

Preprint

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In this paper, we explore the possibility that a light dilaton can be the first sign of new physics at the LHC. The dilaton could emerge in approximate scale invariant UV completions of the SM as the Goldstone boson associated with the spontaneous breaking of the scale invariance. We study in detail the phenomenology of the dilaton at the LHC in the mass range of [10−300] GeV including the case where the dilaton can mix with the SM Higgs boson, leading to an interesting interplay between direct and indirect constraints. A possibility that the dilaton act as a portal to a dark sector is also considered. As a minimal realization, the dark sector includes a dark photon lighter than the dilaton implying sizeable missing energy signatures. Several simplified benchmark models that can encode different UV completions are discussed, for which we scrutinize the current and future LHC reach.

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“…Of the four experiments, only DELPHI [51] conducts a flavor-independent hZ search down to m h ∼ 30 GeV at LEP2, relevant for our Region A. Their analysis requires the thrust to satisfy 0.70 < T < 0.92; this cut will eliminate most of the events in Region A. Additionally, they cluster the events into three jets, which may complicate comparison with our masses M 1 and M 2 .…”

Section: B Relation To Previous Studiesmentioning

confidence: 99%

“…Flavor-independent searches for hA of possible relevance here were also done by DELPHI [51], L3 [52], and OPAL [53]. L3 uses a neural net to reduce their QCD background; this likely eliminates the vast majority of events in Region A.…”

Section: B Relation To Previous Studiesmentioning

confidence: 99%

Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

Kile

Wimmersperg-Toeller

2018

J. High Energ. Phys.

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We investigate an excess observed in hadronic events in the archived LEP2 ALEPH data. This excess was observed at preselection level during data-MC comparisons of four-jet events when no search was being performed. The events are clustered into four jets and paired such that the mass difference between the two dijet systems is minimized. The excess occurs in the region M 1 + M 2 ∼ 110 GeV; about half of the excess is concentrated in the region M 1 ∼ 80 GeV, M 2 ∼ 25 GeV, with a local significance between 4.7σ and 5.5σ, depending on assumptions about hadronization uncertainties. The other half of the events are in a broad excess near M 1 ∼ M 2 ∼ 55 GeV; these display a local significance of 4.1 − 4.5σ. We investigate the effects of changing the SM QCD Monte Carlo sample, the jet-clustering algorithm, and the jet rescaling method. We find that the excess is remarkably robust under these changes, and we find no source of systematic uncertainty that can explain the excess. No analogue of the excess is seen at LEP1. than either of the masses measured separately; such a plot also displays a nice separation of QCD and W + W − events, useful for data-MC comparisons.Unlike what was typical during the LEP era, we plotted M 1 + M 2 using the entire ALEPH LEP2 data sample (∼ 735pb −1 ) simultaneously; with our very loose cuts, this amounts to O(17, 000) events. In doing so, we noticed an excess of about 200 events (∼ 3σ) in the dijet mass sum in the region M 1 + M 2 ∼ 110 GeV. Interestingly, this is the same region in which ALEPH observed an excess in the search for hA final states [2] with a much smaller dataset (5.7pb −1 ) and after analysis cuts; the excess was later dismissed as a statistical fluctuation [3] 3 . This excess brought with it a set of unusual challenges. The first of these is that we had no model on which to base selection cuts for an analysis. Second, as this excess was found during data-MC comparisons at preselection level when no search was being conducted, we had to develop the machinery of the analysis after knowing of the excess; the analysis is unavoidably unblind.Were the experiment still running, a simple solution to these challenges would be to explore the features of the excess region, design a set of cuts which efficiently selects the excess, and then see if such cuts also yield an excess in future data. Unfortunately, this is not possible in our case. However, there are three additional LEP data sets which could potentially be used to confirm or refute our findings. With this in mind, we follow the philosophy of Ref.[2] and set about cataloging the features in the excess region to develop analyses which can be used by the three other LEP experiments. In this paper, we will concentrate on establishing the location of the excess, its significance, and its dependence upon MC samples, jet-clustering algorithm, etc. We will reserve further details, including distributions of many observables in the excess region, for future work.At the time that we initially noticed the excess near M 1 + M 2 ∼ 110 G...

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Flavour independent searchesfor hadronically decaying neutral Higgs bosons

Cited by 9 publications

References 27 publications

A light dilaton at the LHC

A light dilaton at the LHC

A light dilaton at the LHC

Localized 4σ and 5σ dijet mass excesses in ALEPH LEP2 four-jet events

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