14034697
No crisis for big bang nucleosynthesis.
Contrary to a recent claim, the inferred primordial abundances of the light elements are quite consistent with the expectations from standard big bang nucleosynthesis when attention is restricted to direct observations rather than results from chemical evolution models. The number of light neutrino (or equivalent particle) species (N�) can be as high as 4.53 if the nucleon-tophoton ratio (�) is at its lower limit of 1.65 × 10 −10 , as constrained by the upper bound on the deuterium abundance in high redshift quasar absorption systems. Alternatively, with N� = 3, � can be as high as 8.90 × 10 −10 if the deuterium abundance is bounded from below by its interstellar value.
14192961
An Absence of Neutrinos Associated with Cosmic Ray Acceleration in Gamma-Ray Bursts
Gamma-Ray Bursts R. Abbasi, Y. Abdou, T. Abu-Zayyad, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, D. Altmann, K. Andeen, J. Auffenberg, X. Bai, 38 M. Baker, S. W. Barwick, R. Bay, J. L. Bazo Alba, K. Beattie, J. J. Beatty, 20 S. Bechet, J. K. Becker, K.-H. Becker, M. Bell, M. L. Benabderrahmane, S. BenZvi, J. Berdermann, P. Berghaus, D. Berley, E. Bernardini, D. Bertrand, D. Z. Besson, D. Bindig, M. Bissok, E. Blaufuss, J. Blumenthal, D. J. Boersma, C. Bohm, D. Bose, S. Böser, O. Botner, L. Brayeur, A. M. Brown, S. Buitink, K. S. Caballero-Mora, M. Carson, M. Casier, D. Chirkin, B. Christy, F. Clevermann, S. Cohen, C. Colnard, D. F. Cowen, 43 A. H. Cruz Silva, M. V. D’Agostino, M. Danninger, J. Daughhetee, J. C. Davis, C. De Clercq, T. Degner, F. Descamps, P. Desiati, G. de Vries-Uiterweerd, T. DeYoung, J. C. D́ıaz-Vélez, M. Dierckxsens, J. Dreyer, J. P. Dumm, M. Dunkman, J. Eisch, R. W. Ellsworth, O. Engdeg̊ard, S. Euler, P. A. Evenson, O. Fadiran, A. R. Fazely, A. Fedynitch, J. Feintzeig, T. Feusels, K. Filimonov, C. Finley, T. Fischer-Wasels, S. Flis, A. Franckowiak, R. Franke, T. K. Gaisser, J. Gallagher, L. Gerhardt, 8 L. Gladstone, T. Glüsenkamp, A. Goldschmidt, J. A. Goodman, D. Góra, D. Grant, T. Griesel, A. Groß, S. Grullon, M. Gurtner, C. Ha, 8 A. Haj Ismail, A. Hallgren, F. Halzen, K. Han, K. Hanson, D. Heereman, D. Heinen, K. Helbing, R. Hellauer, S. Hickford, G. C. Hill, K. D. Hoffman, B. Hoffmann, A. Homeier, K. Hoshina, W. Huelsnitz, 31 J.-P. Hülß, P. O. Hulth, K. Hultqvist, S. Hussain, A. Ishihara, E. Jacobi, J. Jacobsen, G. S. Japaridze, H. Johansson, A. Kappes, T. Karg, A. Karle, J. Kiryluk, F. Kislat, S. R. Klein, 8 J.-H. Köhne, G. Kohnen, H. Kolanoski, L. Köpke, S. Kopper, D. J. Koskinen, M. Kowalski, T. Kowarik, M. Krasberg, G. Kroll, J. Kunnen, N. Kurahashi, T. Kuwabara, M. Labare, K. Laihem, H. Landsman, M. J. Larson, R. Lauer, J. Lünemann, J. Madsen, A. Marotta, R. Maruyama, K. Mase, H. S. Matis, K. Meagher, M. Merck, P. Mészáros, 44 T. Meures, S. Miarecki, 8 E. Middell, N. Milke, J. Miller, T. Montaruli, 6 R. Morse, S. M. Movit, R. Nahnhauer, J. W. Nam, U. Naumann, S. C. Nowicki, D. R. Nygren, S. Odrowski, A. Olivas, M. Olivo, A. O’Murchadha, S. Panknin, L. Paul, C. Pérez de los Heros, A. Piegsa, D. Pieloth, J. Posselt, P. B. Price, G. T. Przybylski, K. Rawlins, P. Redl, E. Resconi, 23 W. Rhode, M. Ribordy, M. Richman, B. Riedel, A. Rizzo, J. P. Rodrigues, F. Rothmaier, C. Rott, T. Ruhe, D. Rutledge, B. Ruzybayev, D. Ryckbosch, H.-G. Sander, M. Santander, S. Sarkar, K. Schatto, T. Schmidt, S. Schöneberg, A. Schönwald, A. Schukraft, L. Schulte, A. Schultes, O. Schulz, 23 M. Schunck, D. Seckel, B. Semburg, S. H. Seo, Y. Sestayo, S. Seunarine, A. Silvestri, M. W. E. Smith, G. M. Spiczak, C. Spiering, M. Stamatikos, 26 T. Stanev, T. Stezelberger, R. G. Stokstad, A. Stößl, E. A. Strahler, R. Ström, M. Stüer, G. W. Sullivan, H. Taavola, I. Taboada, A. Tamburro, S. Ter-Antonyan, S. Tilav, P. A. Toale, S. Toscano, D. Tosi, N. van Eijndhoven, A. Van Overloop, J. van Santen, M. Vehring, M. Voge, C. Walck, T. Waldenmaier, M. Wallraff, M. Walter, R. Wasserman, Ch. Weaver, C. Wendt, S. Westerhoff, N. Whitehorn, K. Wiebe, C. H. Wiebusch, D. R. Williams, R. Wischnewski, H. Wissing, M. Wolf, T. R. Wood, K. Woschnagg, C. Xu, D. L. Xu, X. W. Xu, J. P. Yanez, G. Yodh, S. Yoshida, P. Zarzhitsky, and M. Zoll
18427722
NEUTRINOS FROM THE BIG BANG
The standard Big Bang cosmology predicts the existence of an, as yet undetected, relic neutrino background, similar to the photons observed in the cosmic microwave background. If neutrinos have mass, then such relic neutrinos are a natural candidate for the dark matter of the universe, and indeed were the first particles to be proposed for this role. This possibility has however been increasingly constrained by cosmological considerations, particularly of large-scale structure formation, thus yielding stringent bounds on neutrino masses, which have yet to be matched by laboratory experiments. Another probe of relic neutrinos is primordial nucleosynthesis which is sensitive to the number of neutrino types (including possible sterile species) as well as to any lepton asymmetry. Combining such arguments with the experimental finding that neutrino mixing angles are large, excludes the possibility of a large asymmetry and disfavours new neutrinos beyond those now known.
118792236
The intergalactic propagation of ultrahigh energy cosmic ray nuclei
We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).
119383784
Big bang nucleosynthesis and physics beyond the standard model
The Hubble expansion of galaxies, the 2.73 K black-body radiation background and the cosmic abundances of the light elements argue for a hot, dense origin of the universe - the standard big bang cosmology - and enable its evolution to be traced back fairly reliably to the nucleosynthesis era when the temperature was of O(1) MeV corresponding to an expansion age of O(1) s. All particles, known and hypothetical, would have been created at higher temperatures in the early universe and analyses of their possible effects on the abundances of the synthesized elements enable many interesting constraints to be obtained on particle properties. These arguments have usefully complemented laboratory experiments in guiding attempts to extend physics beyond the standard model, incorporating ideas such as supersymmetry, compositeness and unification. We first present a pedagogical account of relativistic cosmology and primordial nucleosynthesis, discussing both theoretical and observational aspects, and then proceed to examine such constraints in detail, in particular those pertaining to new massless particles and massive unstable particles. Finally, in a section aimed at particle physicists, we illustrate applications of such constraints to models of new physics.
118186558
Einstein's universe: The challenge of dark energy
From an observational perspe ctive, cosmology is today in excellent shape – we can now look back to when the first galaxies formed ~ 1 Gyr after the Big Bang, and reco n struct the thermal history back to the primordial nucleosynth esis era when the universe was ~ 1 s old. However recent deep studies of the Hubble diagram of Type Ia supernovae indicate that the expa nsion rate is accelerating, requiring the dominant component of the universe to have negative pressure like vacuum e n ergy . This has been indirectly substantiated through d etailed studies of angular anisotropies in the cosmic micro-wave back ground and of spatial correlations of the large -scale structure of galaxies, which also require most of the matter component to be non -baryonic. A l-though there are plausible candidates for the constit u-ent of the dark matter in physics beyond the Standard Model (e.g. supersymmetry), the energy scale of the required ‘dark energy’ is ~10
22398034
Verifiable model of neutrino masses from large extra dimensions
We propose a new scenario of neutrino masses with a Higgs triplet (xi(++),xi(+),xi(0)) in a theory of large extra dimensions. Lepton number violation in a distant brane acts as the source of a very small trilinear coupling of xi to the standard Higgs doublet in our brane. Small realistic Majorana neutrino masses are naturally obtained with the fundamental scale M(*) approximately O(1) TeV, foretelling the possible discovery of xi (m(xi) less, similarM(*)) at future colliders. Decays of xi(++) into same-sign dileptons are fixed by the neutrino mass matrix. Observation of &mgr;-e conversion in nuclei is predicted.