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

[TRIUMF Seminars]

Date/Time: Tue 2014-05-13 at 13:00

Location:  Theory Room         

Speaker:   Michael Buchoff (INT)

Title:     Neutron-antineutron transitions and the lattice

Abstract: In the everyday exploration of our matter filled universe, one scenario that rarely crosses our mind is the possibility of matter suddenly transitioning to antimatter.  While this idea seems somewhat far-fetched, there is ample collider evidence that this occurs in mesonic physics such as kaon-mixing and B-mixing; both instances indicative of the weak interaction.   One intriguing instance that hits closer to the low-energy world we see everyday is the possibility that a neutron can transition to an antineutron via some beyond-the-Standard-Model (BSM) interaction that changes baryon number by two units.  Obviously, this transition cannot occur too frequently (none of us would exist), but any indication of this process would not only imply new physics, but address the monumental question of what early universe process enabled the baryon-antibaryon asymmetry that we see today.   Even if a signal is not observed, very tight constraints can be put on large classes of theoretical models by bounding the transition rate.  However, to make a reliable prediction/interpretation of this transition rate, the dimension-six neutron-antineutron matrix elements must be calculated from first principles via lattice QCD.  In this colloquium, I will review the promising experimental prospects along with the potential theoretical implications, and I will present preliminary results of the lattice QCD calculations that are necessary to understand these implications.



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