Seminars IFIC

A Standard Model explanation for the excess of electron-like events in MiniBooNE

por Prof. Ara Ioanissyan (Yerevan Physics Institute, Armenia)

Europe/Madrid
4-4-4426 - Seminari Física Teòrica (Campus Burjassot)

4-4-4426 - Seminari Física Teòrica

Campus Burjassot

20
Descripción
We study the dependence of neutral current (NC) neutrino-induced 
π0/photon production (νμ+A→νμ+1π0/γ+X) on the atomic number of the 
target nucleus, A, at 4-momentum transfers relevant to the MiniBooNE 
experiment: Δ resonance mass region. Our conclusion is based on 
experimental data for photon-nucleus interactions from the 
A2 collaboration at the Mainz MAMI accelerator. We work in the 
approximation that decays of Δ resonance unaffected by its production 
channel, via photon or Z boson. 1π0+X production scales as A2/3, 
the surface area of the nucleus. Meanwhile the photons created in Δ 
decays will leave the nucleus, and that cross section will be 
proportional to the atomic number of the nucleus. Thus the ratio of 
photon production to π0 production is proportional to A1/3. For carbon
12C this factor is ≈2.3. MiniBooNE normalizes the rate of photon 
production to the measured π0 production rate. The reduced neutral 
pion production rate would yield at least twice as many photons as 
previously expected, thus significantly lowering the number of 
unexplained electron-like events.