کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
10722853 1033810 2011 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
A theory of extra radiation in the Universe
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم فیزیک هسته ای و انرژی بالا
پیش نمایش صفحه اول مقاله
A theory of extra radiation in the Universe
چکیده انگلیسی
Recent cosmological observations, such as the measurement of the primordial 4He abundance, CMB, and large scale structure, give preference to the existence of extra radiation component, ΔNν>0. The extra radiation may be accounted for by particles which were in thermal equilibrium and decoupled before the big bang nucleosynthesis. Broadly speaking, there are two possibilities: (1) there are about 10 particles which have very weak couplings to the standard model particles and decoupled much before the QCD phase transition; (2) there is one or a few light particles with a reasonably strong coupling to the plasma and it decouples after the QCD phase transition. Focusing on the latter case, we find that a light chiral fermion is a suitable candidate, which evades astrophysical constraints. Interestingly, our scenario predicts a new gauge symmetry at TeV scale, and therefore may be confirmed at the LHC. As a concrete example, we show that such a light fermion naturally appears in the E6-inspired GUT.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics Letters B - Volume 697, Issue 4, 14 March 2011, Pages 275-279
نویسندگان
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