Particle theory

Research group

Research theme

Sub department

About

Related research groups

High-frequency Gravitational Waves from Superstring Phases in the Early Universe

e-Print: 2511.16404 [hep-ph]

Authors:

Joseph P. Conlon (Oxford U., Theor. Phys.), Edmund J. Copeland (Nottingham U.), Edward Hardy (Oxford U., Theor. Phys.), Noelia Sánchez González (Oxford U., Theor. Phys.)

Abstract:

When moduli roll in the early universe, all physical scales - including string tensions - simultaneously evolve. The dynamics of cosmic string loops with time-varying tension can produce cosmic string loop trackers in which most of the energy density of the universe lies in the form of string loops. This solution can exist as an attractor until the rolling modulus reaches its minimum, when the loops ultimately decay through gravitational wave emission. We explore the spectrum of gravitational waves produced by such string loop trackers. The resulting spectrum is high-frequency and peaks in the GHz regime today. The amplitude of the signal is diluted by any subsequent matter-dominated epochs, and thus the potential observability of the signal crucially depends on the duration of the moduli-dominated epoch that follows once the moduli settle down and oscillate about their minimum.
Full PDF text
Details from ArXiV

Suppression of pair beam instabilities in a laboratory analogue of blazar pair cascades

Proceedings of the National Academy of Sciences National Academy of Sciences 122:45 (2025) e2513365122

Authors:

Charles Arrowsmith, Francesco Miniati, Pablo J Bilbao, Pascal Simon, Archie Bott, Stephane Burger, Hui Chen, Filipe D Cruz, Tristan Davenne, Anthony Dyson, Ilias Efthymiopoulos, Dustin H Froula, Alice Goillot, Jon T Gudmundsson, Dan Haberberger, Jack WD Halliday, Thomas Hodge, Brian T Huffman, Sam Iaquinta, G Marshall, Brian Reville, Subir Sarkar, Alexander Schekochihin, Luis O Silva, Raspberry Simpson, Vasiliki Stergiou, Raoul MGM Trines, Thibault Vieu, Nikolaos Charitonidis, Robert Bingham, Gianluca Gregori

Abstract:

The generation of dense electron-positron pair beams in the laboratory can enable direct tests of theoretical models of γ-ray bursts and active galactic nuclei. We have successfully achieved this using ultrarelativistic protons accelerated by the Super Proton Synchrotron at (CERN). In the first application of this experimental platform, the stability of the pair beam is studied as it propagates through a meter-length plasma, analogous to TeV γ-ray-induced pair cascades in the intergalactic medium. It has been argued that pair beam instabilities disrupt the cascade, thus accounting for the observed lack of reprocessed GeV emission from TeV blazars. If true, this would remove the need for a moderate strength intergalactic magnetic field to explain the observations. We find that the pair beam instability is suppressed if the beam is not perfectly collimated or monochromatic, hence the lower limit to the intergalactic magnetic field inferred from γ-ray observations of blazars is robust.
More details from the publisher
Details from ORA
More details

Measurement of the mean number of muons with energies above 500 GeV in air showers detected with the IceCube Neutrino Observatory

Physical Review D American Physical Society (APS) 112:8 (2025) 082004

Authors:

R Abbasi, M Ackermann, J Adams, SK Agarwalla, JA Aguilar, M Ahlers, JM Alameddine, NM Amin, K Andeen, C Argüelles, Y Ashida, S Athanasiadou, SN Axani, R Babu, X Bai, J Baines-Holmes, A Balagopal V., SW Barwick, S Bash, V Basu, R Bay, JJ Beatty, J Becker Tjus, P Behrens, J Beise, C Bellenghi, B Benkel, S BenZvi, D Berley, E Bernardini, DZ Besson, E Blaufuss, L Bloom, S Blot, I Bodo, F Bontempo, JY Book Motzkin, C Boscolo Meneguolo, S Böser, O Botner, J Böttcher, J Braun, B Brinson, Z Brisson-Tsavoussis, RT Burley, D Butterfield, MA Campana, K Carloni, J Carpio, S Chattopadhyay, N Chau, Z Chen, D Chirkin, S Choi, BA Clark, A Coleman, P Coleman, GH Collin, A Connolly, JM Conrad, R Corley, DF Cowen, C De Clercq, JJ DeLaunay, D Delgado, T Delmeulle, S Deng, P Desiati, KD de Vries, G de Wasseige, T DeYoung, JC Díaz-Vélez, S DiKerby, M Dittmer, A Domi, L Draper, L Dueser, D Durnford, K Dutta, MA DuVernois, T Ehrhardt, L Eidenschink, A Eimer, P Eller, E Ellinger, D Elsässer, R Engel, H Erpenbeck, W Esmail, S Eulig, J Evans, PA Evenson, KL Fan, K Fang, K Farrag, AR Fazely, A Fedynitch, N Feigl, C Finley, L Fischer, D Fox, A Franckowiak, S Fukami, P Fürst, J Gallagher, E Ganster, A Garcia, M Garcia, G Garg, E Genton, L Gerhardt, A Ghadimi, C Glaser, T Glüsenkamp, JG Gonzalez, S Goswami, A Granados, D Grant, SJ Gray, S Griffin, S Griswold, KM Groth, D Guevel, C Günther, P Gutjahr, C Ha, C Haack, A Hallgren, L Halve, F Halzen, L Hamacher, M Ha Minh, M Handt, K Hanson, J Hardin, AA Harnisch, P Hatch, A Haungs, J Häußler, K Helbing, J Hellrung, L Hennig, L Heuermann, R Hewett, N Heyer, S Hickford, A Hidvegi, C Hill, GC Hill, R Hmaid, KD Hoffman, D Hooper, S Hori, K Hoshina, M Hostert, W Hou, T Huber, K Hultqvist, K Hymon, A Ishihara, W Iwakiri, M Jacquart, S Jain, O Janik, M Jeong, M Jin, N Kamp, D Kang, X Kang, A Kappes, L Kardum, T Karg, M Karl, A Karle, A Katil, M Kauer, JL Kelley, M Khanal, A Khatee Zathul, A Kheirandish, H Kimku, J Kiryluk, C Klein, SR Klein, Y Kobayashi, A Kochocki, R Koirala, H Kolanoski, T Kontrimas, L Köpke, C Kopper, DJ Koskinen, P Koundal, M Kowalski, T Kozynets, N Krieger, J Krishnamoorthi, T Krishnan, K Kruiswijk, E Krupczak, A Kumar, E Kun, N Kurahashi, N Lad, C Lagunas Gualda, L Lallement Arnaud, M Lamoureux, MJ Larson, F Lauber, JP Lazar, K Leonard DeHolton, A Leszczyńska, J Liao, YT Liu, M Liubarska, C Love, L Lu, F Lucarelli, W Luszczak, Y Lyu, J Madsen, E Magnus, KBM Mahn, Y Makino, E Manao, S Mancina, A Mand, IC Mariş, S Marka, Z Marka, L Marten, I Martinez-Soler, R Maruyama, F Mayhew, F McNally, JV Mead, K Meagher, S Mechbal, A Medina, M Meier, Y Merckx, L Merten, J Mitchell, L Molchany, T Montaruli, RW Moore, Y Morii, A Mosbrugger, M Moulai, D Mousadi, T Mukherjee, R Naab, M Nakos, U Naumann, J Necker, L Neste, M Neumann, H Niederhausen, MU Nisa, K Noda, A Noell, A Novikov, A Obertacke Pollmann, V O’Dell, A Olivas, R Orsoe, J Osborn, E O’Sullivan, V Palusova, H Pandya, A Parenti, N Park, V Parrish, EN Paudel, L Paul, C Pérez de los Heros, T Pernice, J Peterson, M Plum, A Pontén, V Poojyam, Y Popovych, M Prado Rodriguez, B Pries, R Procter-Murphy, GT Przybylski, L Pyras, C Raab, J Rack-Helleis, N Rad, M Ravn, K Rawlins, Z Rechav, A Rehman, I Reistroffer, E Resconi, S Reusch, CD Rho, W Rhode, B Riedel, A Rifaie, EJ Roberts, S Robertson, M Rongen, A Rosted, C Rott, T Ruhe, L Ruohan, J Saffer, D Salazar-Gallegos, P Sampathkumar, A Sandrock, G Sanger-Johnson, M Santander, S Sarkar, J Savelberg, P Schaile, M Schaufel, H Schieler, S Schindler, L Schlickmann, B Schlüter, F Schlüter, N Schmeisser, T Schmidt, FG Schröder, L Schumacher, S Schwirn, S Sclafani, D Seckel, L Seen, M Seikh, S Seunarine, PA Sevle Myhr, R Shah, S Shefali, N Shimizu, B Skrzypek, R Snihur, J Soedingrekso, A Søgaard, D Soldin, P Soldin, G Sommani, C Spannfellner, GM Spiczak, C Spiering, J Stachurska, M Stamatikos, T Stanev, T Stezelberger, T Stürwald, T Stuttard, GW Sullivan, I Taboada, S Ter-Antonyan, A Terliuk, A Thakuri, M Thiesmeyer, WG Thompson, J Thwaites, S Tilav, K Tollefson, S Toscano, D Tosi, A Trettin, AK Upadhyay, K Upshaw, A Vaidyanathan, N Valtonen-Mattila, J Valverde, J Vandenbroucke, T Van Eeden, N van Eijndhoven, J van Santen, J Vara, F Varsi, M Venugopal, M Vereecken, S Vergara Carrasco, S Verpoest, D Veske, A Vijai, J Villarreal, C Walck, A Wang, E Warrick, C Weaver, P Weigel, A Weindl, AY Wen, C Wendt, J Werthebach, M Weyrauch, N Whitehorn, CH Wiebusch, DR Williams, L Witthaus, M Wolf, G Wrede, XW Xu, JP Yañez, Y Yao, E Yildizci, S Yoshida, R Young, F Yu, S Yu, T Yuan, A Zegarelli, S Zhang, Z Zhang, P Zhelnin, P Zilberman

Abstract:

We present a measurement of the mean number of muons with energies larger than 500 GeV in near-vertical extensive air showers initiated by cosmic rays with primary energies between 2.5 and 100 PeV. The measurement is based on events detected in coincidence between the surface and in-ice detectors of the IceCube Neutrino Observatory. Air showers are recorded on the surface by IceTop, while a bundle of high-energy muons (TeV muons) from the shower can subsequently produce a tracklike event in the IceCube in-ice array. Results are obtained assuming the hadronic interaction models Sibyll 2.1, QGSJet-II.04, and EPOS-LHC. The measured number of TeV muons is found to be in agreement with predictions from air-shower simulations. The results have also been compared to a measurement of low-energy muons by IceTop, indicating an inconsistency between the predictions for low- and high-energy muons in simulations based on the EPOS-LHC model.
More details from the publisher

HOPPET v2.0.0 release note

(2025)

Authors:

Alexander Karlberg, Paolo Nason, Gavin Salam, Giulia Zanderighi, Frà dà ric Dreyer

Supercooled confinement

Journal of High Energy Physics Springer Science and Business Media LLC 2025:10 (2025) 66

Authors:

Prateek Agrawal, Gaurang Ramakant Kane, Vazha Loladze, Mario Reig

Abstract:

<jats:title>A<jats:sc>bstract</jats:sc> </jats:title> <jats:p>We study general properties of confinement phase transitions in the early universe. An observable gravitational wave signal from such transitions requires significant supercooling. However, in almost all understood examples of confining gauge theories the degree of supercooling is too small to give interesting gravitational wave signals. We review and highlight the evidence why supercooling is not generic in confining gauge theories. The exceptions are Randall-Sundrum models which define a strongly coupled gauge theory holographically by a 5D gravitational theory. We construct a simple illustrative model of a 4D gauge theory inspired by features of the Randall-Sundrum model. It is a large-<jats:italic>N</jats:italic> gauge theory in the conformal window coupled to a weakly coupled scalar field which undergoes a supercooled phase transition that breaks the conformal symmetry and triggers confinement. We show that there are interesting features in the gravitational wave spectra that can carry the imprint of the confining gauge theory.</jats:p>
More details from the publisher
More details