Correlation of the highest-energy cosmic rays with nearby extragalactic objects.

Science 318:5852 (2007) 938-943

Authors:

Pierre Auger Collaboration, J Abraham, P Abreu, M Aglietta, C Aguirre, D Allard, I Allekotte, J Allen, P Allison, C Alvarez, J Alvarez-Muñiz, M Ambrosio, L Anchordoqui, S Andringa, A Anzalone, C Aramo, S Argirò, K Arisaka, E Armengaud, F Arneodo, F Arqueros, T Asch, H Asorey, P Assis, BS Atulugama, J Aublin, M Ave, G Avila, T Bäcker, D Badagnani, AF Barbosa, D Barnhill, SLC Barroso, P Bauleo, J Beatty, T Beau, BR Becker, KH Becker, JA Bellido, S Benzvi, C Berat, T Bergmann, P Bernardini, X Bertou, PL Biermann, P Billoir, O Blanch-Bigas, F Blanco, P Blasi, C Bleve, H Blümer, M Bohácová, C Bonifazi, R Bonino, M Boratav, J Brack, P Brogueira, WC Brown, P Buchholz, A Bueno, NG Busca, KS Caballero-Mora, B Cai, DV Camin, R Caruso, W Carvalho, A Castellina, O Catalano, G Cataldi, L Cazón-Boado, R Cester, J Chauvin, A Chiavassa, JA Chinellato, A Chou, J Chye, PDJ Clark, RW Clay, E Colombo, R Conceição, B Connolly, F Contreras, J Coppens, A Cordier, U Cotti, S Coutu, CE Covault, A Creusot, J Cronin, S Dagoret-Campagne, K Daumiller, BR Dawson, RM de Almeida, C De Donato, SJ de Jong, G De La Vega, WJM de Mello Junior, JRT de Mello Neto, I De Mitri, V de Souza, L Del Peral, O Deligny, A Della Selva, C Delle Fratte, H Dembinski, C Di Giulio, JC Diaz, C Dobrigkeit, JC D'Olivo, D Dornic, A Dorofeev, JC Dos Anjos, MT Dova, D D'Urso, MA Duvernois, R Engel, L Epele, M Erdmann, CO Escobar, A Etchegoyen, P Facal San Luis, H Falcke, G Farrar, AC Fauth, N Fazzini, A Fernández, F Ferrer, S Ferry, B Fick, A Filevich, A Filipcic, I Fleck, R Fonte, CE Fracchiolla, W Fulgione, B García, D García Gámez, D Garcia-Pinto, X Garrido, H Geenen, G Gelmini, H Gemmeke, PL Ghia, M Giller, H Glass, MS Gold, G Golup, F Gomez Albarracin, M Gómez Berisso, R Gómez Herrero, P Gonçalves, M Gonçalves do Amaral, D Gonzalez, JG Gonzalez, M González, D Góra, A Gorgi, P Gouffon, V Grassi, A Grillo, C Grunfeld, Y Guardincerri, F Guarino, GP Guedes, J Gutiérrez, JD Hague, JC Hamilton, P Hansen, D Harari, S Harmsma, JL Harton, A Haungs, T Hauschildt, MD Healy, T Hebbeker, D Heck, C Hojvat, VC Holmes, P Homola, J Hörandel, A Horneffer, M Horvat, M Hrabovsky, T Huege, M Iarlori, A Insolia, F Ionita, A Italiano, M Kaducak, KH Kampert, B Keilhauer, E Kemp, RM Kieckhafer, HO Klages, M Kleifges, J Kleinfeller, R Knapik, J Knapp, D-H Koang, A Kopmann, A Krieger, O Krömer, D Kümpel, N Kunka, A Kusenko, G La Rosa, C Lachaud, BL Lago, D Lebrun, P Lebrun, J Lee, MA Leigui de Oliveira, A Letessier-Selvon, M Leuthold, I Lhenry-Yvon, R López, A Lopez Agüera, J Lozano Bahilo, MC Maccarone, C Macolino, S Maldera, M Malek, G Mancarella, ME Manceñido, D Mandat, P Mantsch, AG Mariazzi, IC Maris, D Martello, J Martínez, O Martínez Bravo, HJ Mathes, J Matthews, JAJ Matthews, G Matthiae, D Maurizio, PO Mazur, T McCauley, M McEwen, RR McNeil, MC Medina, G Medina-Tanco, A Meli, D Melo, E Menichetti, A Menschikov, Chr Meurer, R Meyhandan, MI Micheletti, G Miele, W Miller, S Mollerach, M Monasor, D Monnier Ragaigne, F Montanet, B Morales, C Morello, E Moreno, JC Moreno, C Morris, M Mostafá, MA Muller, R Mussa, G Navarra, JL Navarro, S Navas, L Nellen, C Newman-Holmes, D Newton, T Nguyen Thi, N Nierstenhöfer, D Nitz, D Nosek, L Nozka, J Oehlschläger, T Ohnuki, A Olinto, VM Olmos-Gilbaja, M Ortiz, S Ostapchenko, L Otero, D Pakk Selmi-Dei, M Palatka, J Pallotta, G Parente, E Parizot, S Parlati, S Pastor, M Patel, T Paul, V Pavlidou, K Payet, M Pech, J Pekala, R Pelayo, IM Pepe, L Perrone, S Petrera, P Petrinca, Y Petrov, Dieppham Ngoc, Dongpham Ngoc, TN Pham Thi, A Pichel, R Piegaia, T Pierog, M Pimenta, T Pinto, V Pirronello, O Pisanti, M Platino, J Pochon, TA Porter, P Privitera, M Prouza, EJ Quel, J Rautenberg, S Reucroft, B Revenu, FAS Rezende, J Rídky, S Riggi, M Risse, C Rivière, V Rizi, M Roberts, C Robledo, G Rodriguez, D Rodríguez Frías, J Rodriguez Martino, J Rodriguez Rojo, I Rodriguez-Cabo, G Ros, J Rosado, M Roth, B Rouillé-d'Orfeuil, E Roulet, AC Rovero, F Salamida, H Salazar, G Salina, F Sánchez, M Santander, CE Santo, EM Santos, F Sarazin, S Sarkar, R Sato, V Scherini, H Schieler, F Schmidt, T Schmidt, O Scholten, P Schovánek, F Schüssler, SJ Sciutto, M Scuderi, A Segreto, D Semikoz, M Settimo, RC Shellard, I Sidelnik, BB Siffert, G Sigl, N Smetniansky De Grande, A Smialkowski, R Smída, AGK Smith, BE Smith, GR Snow, P Sokolsky, P Sommers, J Sorokin, H Spinka, R Squartini, E Strazzeri, A Stutz, F Suarez, T Suomijärvi, AD Supanitsky, MS Sutherland, J Swain, Z Szadkowski, J Takahashi, A Tamashiro, A Tamburro, O Tascau, R Tcaciuc, D Thomas, R Ticona, J Tiffenberg, C Timmermans, W Tkaczyk, CJ Todero Peixoto, B Tomé, A Tonachini, D Torresi, P Travnicek, A Tripathi, G Tristram, D Tscherniakhovski, M Tueros, V Tunnicliffe, R Ulrich, M Unger, M Urban, JF Valdés Galicia, I Valiño, L Valore, AM van den Berg, V van Elewyck, RA Vázquez, D Veberic, A Veiga, A Velarde, T Venters, V Verzi, M Videla, L Villaseñor, S Vorobiov, L Voyvodic, H Wahlberg, O Wainberg, T Waldenmaier, P Walker, D Warner, AA Watson, S Westerhoff, G Wieczorek, L Wiencke, B Wilczynska, H Wilczynski, C Wileman, MG Winnick, H Wu, B Wundheiler, J Xu, T Yamamoto, P Younk, E Zas, D Zavrtanik, M Zavrtanik, A Zech, A Zepeda, M Ziolkowski, B Kégl

Abstract:

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.

Resonant particle production in branonium

ArXiv 0711.0658 (2007)

Authors:

JG Rosa, John March-Russell

Abstract:

We study the mechanism of particle production in the world-volume of a probe anti D6-brane (or D6 with SUSY breaking) moving in the background created by a fixed stack of $D6$-branes. We show that this may occur in a regime of parametric resonance when the probe's motion is non-relativistic and it moves at large distances from the source branes in low eccentricity orbits. This leads to an exponential growth of the particle number in the probe's world-volume and constitutes an effective mechanism for producing very massive particles. We also analyze the evolution of this system in an expanding universe and how this affects the development of the parametric resonance. We discuss the effects of transverse space compactification on the probe's motion, showing that it leads to the creation of angular momentum in a similar way to the Affleck-Dine mechanism for baryogenesis. Finally, we describe possible final states of the system and their potential relevance to cosmology.

Resonant particle production in branonium

(2007)

Authors:

JG Rosa, John March-Russell

Holographic spectral functions and diffusion constants for fundamental matter

Journal of High Energy Physics 2007:11 (2007)

Authors:

RC Myers, AO Starinets, RM Thomson

Abstract:

The holographic dual of large-N c super-Yang-Mills coupled to a small number of flavours of fundamental matter, N f << N c, is described by N f probe D7-branes in the gravitational background of N c black D3-branes. This system undergoes a first order phase transition characterised by the 'melting' of the mesons. We study the high temperature phase in which the D7-branes extend through the black hole horizon. In this phase, we compute the spectral function for vector, scalar and pseudoscalar modes on the D7-brane probe. We also compute the diffusion constant for the flavour currents. © SISSA 2007.

Is the evidence for dark energy secure?

ArXiv 0710.5307 (2007)

Abstract:

Several kinds of astronomical observations, interpreted in the framework of the standard Friedmann-Robertson-Walker cosmology, have indicated that our universe is dominated by a Cosmological Constant. The dimming of distant Type Ia supernovae suggests that the expansion rate is accelerating, as if driven by vacuum energy, and this has been indirectly substantiated through studies of angular anisotropies in the cosmic microwave background (CMB) and of spatial correlations in the large-scale structure (LSS) of galaxies. However there is no compelling direct evidence yet for (the dynamical effects of) dark energy. The precision CMB data can be equally well fitted without dark energy if the spectrum of primordial density fluctuations is not quite scale-free and if the Hubble constant is lower globally than its locally measured value. The LSS data can also be satisfactorily fitted if there is a small component of hot dark matter, as would be provided by neutrinos of mass 0.5 eV. Although such an Einstein-de Sitter model cannot explain the SNe Ia Hubble diagram or the position of the `baryon acoustic oscillation' peak in the autocorrelation function of galaxies, it may be possible to do so e.g. in an inhomogeneous Lemaitre-Tolman-Bondi cosmology where we are located in a void which is expanding faster than the average. Such alternatives may seem contrived but this must be weighed against our lack of any fundamental understanding of the inferred tiny energy scale of the dark energy. It may well be an artifact of an oversimplified cosmological model, rather than having physical reality.