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Abstract
We discuss the observability of neutrino-induced sphaleron transitions in the IceCube detector, encouraged by a recent paper by Tye and Wong (TW), which argued on the basis of a Bloch wave function in the periodic sphaleron potential that such transitions should be enhanced compared to most previous calculations. We calculate the dependence on neutrino energy of the sphaleron transition rate, comparing it to that for conventional neutrino interactions, and we discuss the observability of tau and multi-muon production in sphaleron-induced transitions. We use IceCube 4-year data to constrain the sphaleron rate, finding that it is comparable to the upper limit inferred previously from a recast of an ATLAS search for microscopic black holes at the LHC with ∼ 3/fb of collisions at 13 TeV. The IceCube constraint is stronger for a sphaleron barrier height E Sph ≳ 9 TeV, and would be comparable with the prospective LHC sensitivity with 300/fb of data at 14 TeV if E Sph ∼ 11 TeV.
Highlights
Neutrino-nucleon cross-section calculationsThe analysis of [9] is based on the idea that sphaleron transitions changing the ChernSimons number n can be modelled by considering a Bloch wave function for an effective one-dimensional Schrodinger equation
JHEP05(2016)085 observability of sphaleron-induced transitions at the LHC and possible future higher-energy pp colliders, and recast a recent ATLAS search for microscopic black holes using ∼ 3/fb of data at 13 TeV in the centre-of-mass as a search for sphalerons [19]
We discuss the observability of neutrino-induced sphaleron transitions in the IceCube detector, encouraged by a recent paper by Tye and Wong (TW), which argued on the basis of a Bloch wave function in the periodic sphaleron potential that such transitions should be enhanced compared to most previous calculations
Summary
The analysis of [9] is based on the idea that sphaleron transitions changing the ChernSimons number n can be modelled by considering a Bloch wave function for an effective one-dimensional Schrodinger equation. In figure 2 we show the sphaleron-induced and conventional IceCube event rate as functions of Eνthres again assuming c = 2 and p = 1 and using (dot-dashed) (dashed) red lines for ESph = 9(8)(10) TeV and a black dashed line for sum of the conventional charged- and neutral-current neutrino cross sections. In the right panel we show the corre√sponding distributions in the reduced neutrino-quark subprocess centre-of-mass energies s, which are sharply peaked at the sphaleron energy ESph, taken here to have its nominal value of 9 TeV This peaking implies that our results would not be affected strongly by a possible energy dependence in the overall factor p, but depend essentially only on the value of p at the sphaleron threshold energy
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