8 Search Results

We provide a self-contained discussion of how reparameterization invariance connects a rotationally-invariant heavy particle effective theory with a single heavy fermion to a Lorentz-invariant theory. Furthermore, using Hilbert-series methods, a Lorentz- invariant operator basis is tabulated, up to and including operators of order $1/M^4$, when the fermion couples to an external U(1) or SU(3) gauge interaction.

An operator basis of an effective theory with a heavy particle, subject to external gauge fields, is spanned by a particular kind of neutral scalar primary of the non-relativistic conformal group. We calculate the characters that can be used for generating the operators in a non-relativistic effective field theory, which accounts for redundancies from the equations of motion and integration by parts.

We perform such a calculation in quantum field theory, where we include simultaneously the source, detector, and neutrino fields in the Hamiltonian. Within the appropriate limits associated with current neutrino oscillation experiments, we recover the standard oscillation formula. On the other hand, we find that the dominant contributions to the amplitude are associated with different neutrino mass eigenstates being emitted at different times, such that they arrive at the detector at the same time. This is contrary to the neutrino wave packet picture, where they are emitted simultaneously and separate as they travel to the detector. This has direct consequencesmore » regarding the mechanisms that lead to a damping of neutrino oscillations for very long baselines. Our analysis also provides a pedagogical example of a measurement process in quantum mechanics.« less

Not provided.

We fit the unfolded data of $$-\atop{B}$$⁰→D^*+ℓ$$-\atop{v}$$ from the Belle experiment, where ℓ ≡ e,μ, using a method independent of heavy quark symmetry to extrapolate to zero-recoil and extract the value of |V_cb|. This results in |V_cb| (41.9$$+2.0\atop{-1.9}$$) × 10^-3, which is robust to changes in the theoretical inputs and very consistent with the value extracted from inclusive semileptonic B decays.

In this study, we prove that for a given operator in the Standard Model (SM) with baryon number ΔB and lepton number ΔL, that the operator's dimension is even (odd) if (ΔB - ΔL)/2 is even (odd). Consequently, this establishes the veracity of statements that were long observed or expected to be true, but not proven, e.g., operators with ΔB - ΔL = 0 are of even dimension, ΔB - ΔL must be an even number, etc. These results remain true even if the SM is augmented by any number of right-handed neutrinos with ΔL = 1.

If one day the technology for muon storage rings permits sensitivity to precession at the order of 10^-8Hz, the local gravitational field of Earth can be a dominant contribution to the precession of the muon, which, if ignored, can fake the signal for a nonzero muon electric dipole moment (EDM). Specifically, the effects of Earth’s gravity on the motion of a muon’s spin is indistinguishable from it having a nonzero EDM of magnitude d_μ~10^-29e cm in a storage ring with vertical magnetic field of -1T, which is significantly larger than the expected upper limit in the Standard Model, d_μ ≲10^-36emore » cm. As a corollary, measurements of Earth’s local gravitational field using stored muons would be a unique test to distinguish classical gravity from general relativity with a bonafide quantum mechanical entity, i.e., an elementary particle’s spin.« less