Blast from the past: Constraints on the dark sector from the BEBC WA66 beam dump experiment

SciPost Physics SciPost 10 (2021) 043

Authors:

Giacomo Marocco, Subir Sarkar

Abstract:

We derive limits on millicharged dark states, as well as particles with electric or magnetic dipole moments, from the number of observed forward electron scattering events at the Big European Bubble Chamber in the 1982 CERN-WA-066 beam dump experiment. The dark states are produced by the 400 GeV proton beam primarily through the decays of mesons produced in the beam dump, and the lack of excess events places bounds extending up to GeV masses. These improve on bounds from all other experiments, in particular CHARM II.

C-parameter hadronisation in the symmetric 3-jet limit and impact on αs fits

European Physical Journal C Springer 81:2 (2021) 158

Authors:

Gionata Luisoni, Gavin Salam, Pier Monni

Abstract:

Hadronisation corrections are crucial in extractions of the strong coupling constant (αs) from event-shape distributions at lepton colliders. Although their dynamics cannot be understood rigorously using perturbative methods, their dominant effect on physical observables can be estimated in singular configurations sensitive to the emission of soft radiation. The differential distributions of some event-shape variables, notably the C parameter, feature two such singular points. We analytically compute the leading non-perturbative correction in the symmetric three-jet limit for the C parameter, and find that it differs by more than a factor of two from the known result in the two-jet limit. We estimate the impact of this result on strong coupling extractions, considering a range of functions to interpolate the hadronisation correction in the region between the 2 and 3-jet limits. Fitting data from ALEPH and JADE, we find that most interpolation choices increase the extracted αs, with effects of up to 4% relative to standard fits. This brings a new perspective on the long-standing discrepancy between certain event-shape αs fits and the world average.

Machine learning Calabi-Yau four-folds

Physics Letters B Elsevier 815 (2021) 136139

Authors:

Yang-Hui He, Andre Lukas

Abstract:

Hodge numbers of Calabi-Yau manifolds depend non-trivially on the underlying manifold data and they present an interesting challenge for machine learning. In this letter we consider the data set of complete intersection Calabi-Yau four-folds, a set of about 900,000 topological types, and study supervised learning of the Hodge numbers h1,1 and h3,1 for these manifolds. We find that h1,1 can be successfully learned (to 96% precision) by fully connected classifier and regressor networks. While both types of networks fail for h3,1, we show that a more complicated two-branch network, combined with feature enhancement, can act as an efficient regressor (to 98% precision) for h3,1, at least for a subset of the data. This hints at the existence of an, as yet unknown, formula for Hodge numbers.

Axion Quasiparticles for Axion Dark Matter Detection

(2021)

Authors:

Jan Schütte-Engel, David JE Marsh, Alexander J Millar, Akihiko Sekine, Francesca Chadha-Day, Sebastian Hoof, Mazhar Ali, Kin-Chung Fong, Edward Hardy, Libor Šmejkal

Measurements of the Time-Dependent Cosmic-Ray Sun Shadow with Seven Years of IceCube Data -- Comparison with the Solar Cycle and Magnetic Field Models

Physical Review D: Particles, Fields, Gravitation and Cosmology American Physical Society 103:4 (2021) 042005

Authors:

MG Aartsen, R Abbasi, M Ackermann, J Adams, JA Aguilar, M Ahlers, M Ahrens, C Alispach, NM Amin, K Andeen, T Anderson, I Ansseau, G Anton, C Argüelles, J Auffenberg, S Axani, H Bagherpour, X Bai, A Balagopal V, A Barbano, SW Barwick, B Bastian, V Basu, V Baum, S Baur, R Bay, JJ Beatty, K-H Becker, J Becker Tjus, S BenZvi, D Berley, E Bernardini, DZ Besson, G Binder, D Bindig, E Blaufuss, S Blot, C Bohm, S Böser, O Botner, J Böttcher, E Bourbeau, J Bourbeau, F Bradascio, J Braun, S Bron, J Brostean-Kaiser, A Burgman, J Buscher, RS Busse, T Carver, C Chen, E Cheung, D Chirkin, S Choi, BA Clark, K Clark, L Classen, A Coleman, GH Collin, JM Conrad, P Coppin, P Correa, DF Cowen, R Cross, P Dave, C De Clercq, JJ DeLaunay, H Dembinski, K Deoskar, S De Ridder, A Desai, P Desiati, KD de Vries, G de Wasseige, M de With, T DeYoung, S Dharani, A Diaz, JC Díaz-Vélez, H Dujmovic, M Dunkman, MA DuVernois, E Dvorak, T Ehrhardt, P Eller, R Engel, PA Evenson, S Fahey, AR Fazely, J Felde, H Fichtner, AT Fienberg, K Filimonov, C Finley, D Fox, A Franckowiak, E Friedman, A Fritz, TK Gaisser, J Gallagher, E Ganster, S Garrappa, L Gerhardt, A Ghadimi, T Glauch, T Glüsenkamp, A Goldschmidt, JG Gonzalez, S Goswami, D Grant, T Grégoire, Z Griffith, S Griswold, M Günder, M Gündüz, C Haack, A Hallgren, R Halliday, L Halve, F Halzen, K Hanson, J Hardin, A Haungs, S Hauser, D Hebecker, D Heereman, P Heix, K Helbing, R Hellauer, F Henningsen, S Hickford, J Hignight, C Hill, GC Hill, KD Hoffman, R Hoffmann, T Hoinka, B Hokanson-Fasig, K Hoshina, F Huang, M Huber, T Huber, K Hultqvist, M Hünnefeld, R Hussain, S In, N Iovine, A Ishihara, M Jansson, GS Japaridze, M Jeong, BJP Jones, F Jonske, R Joppe, D Kang, W Kang, A Kappes, D Kappesser, T Karg, M Karl, A Karle, U Katz, M Kauer, M Kellermann, JL Kelley, A Kheirandish, J Kim, K Kin, T Kintscher, J Kiryluk, T Kittler, J Kleimann, SR Klein, R Koirala, H Kolanoski, L Köpke, C Kopper, S Kopper, DJ Koskinen, P Koundal, M Kowalski, K Krings, G Krückl, N Kulacz, N Kurahashi, A Kyriacou, JL Lanfranchi, MJ Larson, F Lauber, JP Lazar, K Leonard, A Leszczyńska, Y Li, QR Liu, E Lohfink, CJ Lozano Mariscal, L Lu, F Lucarelli, A Ludwig, J Lünemann, W Luszczak, Y Lyu, WY Ma, J Madsen, G Maggi, KBM Mahn, Y Makino, P Mallik, S Mancina, IC Mariş, R Maruyama, K Mase, R Maunu, F McNally, K Meagher, M Medici, A Medina, M Meier, S Meighen-Berger, J Merz, T Meures, J Micallef, D Mockler, G Momenté, T Montaruli, RW Moore, R Morse, M Moulai, P Muth, R Nagai, U Naumann, G Neer, LV Nguyen, H Niederhausen, MU Nisa, SC Nowicki, DR Nygren, A Obertacke Pollmann, M Oehler, A Olivas, A O'Murchadha, E O'Sullivan, H Pandya, DV Pankova, N Park, GK Parker, EN Paudel, P Peiffer, C Pérez de los Heros, S Philippen, D Pieloth, S Pieper, E Pinat, A Pizzuto, M Plum, Y Popovych, A Porcelli, M Prado Rodriguez, PB Price, GT Przybylski, C Raab, A Raissi, M Rameez, L Rauch, K Rawlins, IC Rea, A Rehman, R Reimann, B Relethford, M Renschler, G Renzi, E Resconi, W Rhode, M Richman, B Riedel, S Robertson, G Roellinghoff, M Rongen, C Rott, T Ruhe, D Ryckbosch, D Rysewyk Cantu, I Safa, SE Sanchez Herrera, A Sandrock, J Sandroos, M Santander, S Sarkar, S Sarkar, K Satalecka, M Scharf, M Schaufel, H Schieler, P Schlunder, T Schmidt, A Schneider, J Schneider, FG Schröder, L Schumacher, S Sclafani, D Seckel, S Seunarine, S Shefali, M Silva, B Smithers, R Snihur, J Soedingrekso, D Soldin, M Song, GM Spiczak, C Spiering, J Stachurska, M Stamatikos, T Stanev, R Stein, J Stettner, A Steuer, T Stezelberger, RG Stokstad, NL Strotjohann, T Stürwald, T Stuttard, GW Sullivan, I Taboada, F Tenholt, S Ter-Antonyan, A Terliuk, S Tilav, K Tollefson, L Tomankova, C Tönnis, S Toscano, D Tosi, A Trettin, M Tselengidou, CF Tung, A Turcati, R Turcotte, CF Turley, B Ty, E Unger, MA Unland Elorrieta, M Usner, J Vandenbroucke, W Van Driessche, D van Eijk, N van Eijndhoven, D Vannerom, J van Santen, S Verpoest, M Vraeghe, C Walck, A Wallace, M Wallraff, TB Watson, C Weaver, A Weindl, MJ Weiss, J Weldert, C Wendt, J Werthebach, BJ Whelan, N Whitehorn, K Wiebe, CH Wiebusch, DR Williams, L Wills, M Wolf, TR Wood, K Woschnagg, G Wrede, J Wulff, XW Xu, Y Xu, JP Yanez, S Yoshida, T Yuan, Z Zhang, M Zöcklein

Abstract:

Observations of the time-dependent cosmic-ray Sun shadow have been proven as a valuable diagnostic for the assessment of solar magnetic field models. In this paper, seven years of IceCube data are compared to solar activity and solar magnetic field models. A quantitative comparison of solar magnetic field models with IceCube data on the event rate level is performed for the first time. Additionally, a first energy-dependent analysis is presented and compared to recent predictions. We use seven years of IceCube data for the Moon and the Sun and compare them to simulations on data rate level. The simulations are performed for the geometrical shadow hypothesis for the Moon and the Sun and for a cosmic-ray propagation model governed by the solar magnetic field for the case of the Sun. We find that a linearly decreasing relationship between Sun shadow strength and solar activity is preferred over a constant relationship at the 6.4sigma level. We test two commonly used models of the coronal magnetic field, both combined with a Parker spiral, by modeling cosmic-ray propagation in the solar magnetic field. Both models predict a weakening of the shadow in times of high solar activity as it is also visible in the data. We find tensions with the data on the order of $3\sigma$ for both models, assuming only statistical uncertainties. The magnetic field model CSSS fits the data slightly better than the PFSS model. This is generally consistent with what is found previously by the Tibet AS-gamma Experiment, a deviation of the data from the two models is, however, not significant at this point. Regarding the energy dependence of the Sun shadow, we find indications that the shadowing effect increases with energy during times of high solar activity, in agreement with theoretical predictions.