18,399 research outputs found
The Lorentzian distance formula in noncommutative geometry
For almost twenty years, a search for a Lorentzian version of the well-known
Connes' distance formula has been undertaken. Several authors have contributed
to this search, providing important milestones, and the time has now come to
put those elements together in order to get a valid and functional formula.
This paper presents a historical review of the construction and the proof of a
Lorentzian distance formula suitable for noncommutative geometry.Comment: 16 pages, final form, few references adde
Spin-Orbit Coupling Fluctuations as a Mechanism of Spin Decoherence
We discuss a general framework to address spin decoherence resulting from
fluctuations in a spin Hamiltonian. We performed a systematic study on spin
decoherence in the compound K[VAsO(DO)]
8DO, using high-field Electron Spin Resonance (ESR). By analyzing the
anisotropy of resonance linewidths as a function of orientation, temperature
and field, we find that the spin-orbit term is a major decoherence source. The
demonstrated mechanism can alter the lifetime of any spin qubit and we discuss
how to mitigate it by sample design and field orientation.Comment: submitte
Deep structure of the Tyrrhenian basin from 2-D joint refraction and reflection travel-time tomography of wide angle seismic data
D-brane Instantons as Gauge Instantons in Orientifolds of Chiral Quiver Theories
Systems of D3-branes at orientifold singularities can receive
non-perturbative D-brane instanton corrections, inducing field theory operators
in the 4d effective theory. In certain non-chiral examples, these systems have
been realized as the infrared endpoint of a Seiberg duality cascade, in which
the D-brane instanton effects arise from strong gauge theory dynamics. We
present the first UV duality cascade completion of chiral D3-brane theories, in
which the D-brane instantons arise from gauge theory dynamics. Chiral examples
are interesting because the instanton fermion zero mode sector is topologically
protected, and therefore lead to more robust setups. As an application of our
results, we provide a UV completion of certain D-brane orientifold systems
recently claimed to produce conformal field theories with conformal invariance
broken only by D-brane instantons.Comment: 50 pages, 32 figures. v2: version published in JHEP with references
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