[Triumf-seminars] TRIUMF Theory Seminar today at 13:00

[TRIUMF Seminars]

Date/Time: Tue 2013-05-28 at 13:00

Location:  Theory Room         

Speaker:   Andre' Walker-Loud (BNL)

Title:     M_n - M_p

Abstract: The formation of light nuclei in the early universe, Big Bang Nucleosynthesis, is most sensitive to the neutron-proton mass splitting as this quantity controls the initial ratio of neutrons to protons and also impacts the neutron lifetime. There are two sources of isospin violation in the Standard Model which give rise to the neutron-proton mass spitting: the masses of the up and down quarks and their electromagnetic couplings. The electromagnetic correction can be determined via contour integrals and the experimentally measured elastic and inelastic structure functions of the nucleons. The contribution from the down-quark up-quark mass splitting can only be determined with lattice QCD. I will describe in detail our understanding of these two contributions and summarize with implied constraints from primordial nucleosynthesis.



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