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Investigating Lorentz Violation with Neutrino Data from Double Chooz Experiment, placing limits on Standard Model Extension terms. The study illustrates the impact of Lorentz Violating Terms on neutrino oscillations in different frames and discusses the absence of sidereal time variations in the experimental data.
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Lorentz Violation and an Experimental Limit Ben Rybolt 12/10/2012
Goal • Test the Standard Model Extension using neutrino oscillation data from the Double Chooz Experiment [3]. • Place upper limit on possible SME terms • Neutrino Oscillations act like interferometers and over large distances may be sensitive to very small Lorentz Violating Terms
Standard Model Extension[1] • What is it? • Does not assume that the universe is Lorentz invariant. Includes terms that Violate CPT and maintain CPT symmetries • Can occur through spontaneous Lorentz symmetry breaking • Simple frame work to go beyond the standard model
Lagrangian • Standard model for leptons • Including Lorentz Violating Terms[2]
Sun Centered Frame Z • Lorentz violating terms choose a preferred direction in space • We assume the Lorentz violating field is a fixed in the Sun centered frame Y X Possible direction of Lorentz violating field
Earth Centered Frame Z-up Neutrino propagation direction Is measured in the Earth centered Frame If a Lorentz Violating Field is fixed in the Sun centered Frame then Sidereal Time Variations in the earth Centered Frame would be a clear signal for Standard Model Extension. Y-east X-south
Double Chooz Experiment • We have established that Lorentz violating terms cause Sidereal time variations in neutrino oscillations • No sidereal time variations were found in the Double Chooz data but we can place upper limits on the strength of possible Standard Model Extension Coefficients
General Oscillations • Given the standard model Extension Lagrangian • The Effective Hamiltonian for neutrino Oscillation is • The probability of oscillation then can be written
Simplifying Assumptions • Since we are looking for upper limits we can consider either the or the case separately in this work only the case will be considered • We can also neglect the mass term because it does not contribute a sidereal time dependency
Simplified Oscillation Probability . • Transforming into an Earth based frame • Grouping terms with sidereal time dependence
We have reduced the problem to three parameters that we can compare to experimental data • In Double Chooz Geometry the parameters are connected to Standard Model Extensions by [4]
Results • The Double Chooz detector measures Neutrinos created from 2 nuclear reactors ~ 1 km away • We observe ~ 40 neutrino events/day • Data set represents ~230 days of detector data • All events were placed into 24 bins per sidereal day (23.934 hours)
Results • Oscillation is Sidereal time is smaller than error bars • Data is consistent with no sidereal time oscillation • [] are constrained to <GeV
References [1]D. Colladay and A. Kostelecky, CPT Violation and the Standard Model, Phys. Rev. D 55, 6760 (1997). [2]V.A. Kostelecky and M. Mewes, Lorentz and CPT violation in the neutrino sector, Phys Rev D 70, 031902 [3]Y. Abe et al., First Test of Lorentz Violation with a Reactor-Based Antineutrino Experiment, arXiv:1209.5810[hep-ex] [4] V.A. Kostelecky and M. Mewes Phys., Lorentz Violation and Short-baseline Neutrino Experiments,Phys Rev D 70, 076002
