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Standard Model Muon Magnetic Dipole Moment
Authors:
Noah Bray-Ali
Abstract:
The most recent high-precision determination of the hadronic leading order contribution to the muon magnetic dipole moment within the Standard Model of particle physics has revealed a five standard deviation discrepancy with the previous determination with the highest precision. A systematic effect of the luminous volume created during the measurements leading to the determinations seems to be the…
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The most recent high-precision determination of the hadronic leading order contribution to the muon magnetic dipole moment within the Standard Model of particle physics has revealed a five standard deviation discrepancy with the previous determination with the highest precision. A systematic effect of the luminous volume created during the measurements leading to the determinations seems to be the source of the discrepancy. Correcting for the luminous volume effect allows a consistent determination of the Standard Model muon magnetic dipole moment with precision that is comparable to the latest world average from muon spin precession experiments.
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Submitted 5 October, 2023; v1 submitted 19 August, 2023;
originally announced August 2023.
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Spontaneous Mutations from Terahertz Proton Tunneling
Authors:
Noah Bray-Ali
Abstract:
Protons in the gap between base pairs of the double helix store the code of life by breaking the chiral symmetry that swaps the sense strand with its complementary partner. When these hydrogen bonds break during replication and transcription, pairs of protons switch sides restoring chiral symmetry and destroying genetic information. Using time-independent second-order perturbation theory, we show…
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Protons in the gap between base pairs of the double helix store the code of life by breaking the chiral symmetry that swaps the sense strand with its complementary partner. When these hydrogen bonds break during replication and transcription, pairs of protons switch sides restoring chiral symmetry and destroying genetic information. Using time-independent second-order perturbation theory, we show that the observed rate of such spontaneous mutations follows in the sudden approximation for bond breaking provided protons in bonds between bases tunnel across the gap with terahertz frequencies.
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Submitted 14 August, 2023; v1 submitted 13 April, 2023;
originally announced May 2023.
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Prospects for precise predictions of $a_μ$ in the Standard Model
Authors:
G. Colangelo,
M. Davier,
A. X. El-Khadra,
M. Hoferichter,
C. Lehner,
L. Lellouch,
T. Mibe,
B. L. Roberts,
T. Teubner,
H. Wittig,
B. Ananthanarayan,
A. Bashir,
J. Bijnens,
T. Blum,
P. Boyle,
N. Bray-Ali,
I. Caprini,
C. M. Carloni Calame,
O. Catà,
M. Cè,
J. Charles,
N. H. Christ,
F. Curciarello,
I. Danilkin,
D. Das
, et al. (57 additional authors not shown)
Abstract:
We discuss the prospects for improving the precision on the hadronic corrections to the anomalous magnetic moment of the muon, and the plans of the Muon $g-2$ Theory Initiative to update the Standard Model prediction.
We discuss the prospects for improving the precision on the hadronic corrections to the anomalous magnetic moment of the muon, and the plans of the Muon $g-2$ Theory Initiative to update the Standard Model prediction.
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Submitted 29 March, 2022;
originally announced March 2022.
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Weighing the Axion with Muon Haloscopy
Authors:
Noah Bray-Ali
Abstract:
Recent measurements of muon spin precession confirm a long-standing tension with the standard model of particle physics. We argue that axions form the dark matter in the universe and that axions from the local dark matter halo of the galaxy are responsible for the tension. The argument gives a percent level prediction for the mass of the axion that can be tested by measuring the mid-infrared elect…
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Recent measurements of muon spin precession confirm a long-standing tension with the standard model of particle physics. We argue that axions form the dark matter in the universe and that axions from the local dark matter halo of the galaxy are responsible for the tension. The argument gives a percent level prediction for the mass of the axion that can be tested by measuring the mid-infrared electrodynamic response of a wide range of polar materials. A broad resonance in the scattered visible light intensity from quartz crystal at room-temperature and ambient pressure is reported that peaks at a frequency shift of the light which is consistent with the creation of axions with the predicted mass.
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Submitted 15 March, 2024; v1 submitted 27 August, 2021;
originally announced August 2021.
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Holographic Code Rate
Authors:
Noah Bray-Ali,
David Chester,
Dugan Hammock,
Marcelo M. Amaral,
Klee Irwin,
Michael F. Rios
Abstract:
Holographic codes grown with perfect tensors on regular hyperbolic tessellations using an inflation rule protect quantum information stored in the bulk from errors on the boundary provided the code rate is less than one. Hyperbolic geometry bounds the holographic code rate and guarantees quantum error correction for codes grown with any inflation rule on all regular hyperbolic tessellations in a c…
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Holographic codes grown with perfect tensors on regular hyperbolic tessellations using an inflation rule protect quantum information stored in the bulk from errors on the boundary provided the code rate is less than one. Hyperbolic geometry bounds the holographic code rate and guarantees quantum error correction for codes grown with any inflation rule on all regular hyperbolic tessellations in a class whose size grows exponentially with the rank of the perfect tensors for rank five and higher. For the tile completion inflation rule, holographic triangle codes have code rate more than one but all others perform quantum error correction.
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Submitted 25 August, 2019;
originally announced August 2019.
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Standard Temperature and Pressure Superconductivity
Authors:
Noah Bray-Ali
Abstract:
Superconductivity at standard temperature and pressure is far from the extreme conditions where new fundamental laws of physics are expected to arise. Yet it is widely believed that the Landau-Ginzburg-Wilson-Fisher paradigm of broken symmetry and renormalization does not give a satisfactory account of the phenomenon. Almost a decade ago, we used the Bardeen-Cooper-Shrieffer wavefunction to show t…
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Superconductivity at standard temperature and pressure is far from the extreme conditions where new fundamental laws of physics are expected to arise. Yet it is widely believed that the Landau-Ginzburg-Wilson-Fisher paradigm of broken symmetry and renormalization does not give a satisfactory account of the phenomenon. Almost a decade ago, we used the Bardeen-Cooper-Shrieffer wavefunction to show that superconductors have topological order. Here we report progress using topological order to look for standard temperature and pressure superconductivity.
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Submitted 25 September, 2017;
originally announced September 2017.
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Direct observation of the Mott gap in strontium iridate with a scanning tunneling microscope
Authors:
John Nichols,
Noah Bray-Ali,
Gang Cao,
Kwok-Wai Ng
Abstract:
The single-layer Mott insulator strontium iridate Sr$_2$IrO$_4$ was studied using a scanning tunneling microscope. This measurement technique is unique due to the transport properties of this Mott insulator allowing tunneling measurements to be performed, even at cryogenic temperatures. We obtained high-resolution images of the sample surface and the differential tunneling conductance at different…
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The single-layer Mott insulator strontium iridate Sr$_2$IrO$_4$ was studied using a scanning tunneling microscope. This measurement technique is unique due to the transport properties of this Mott insulator allowing tunneling measurements to be performed, even at cryogenic temperatures. We obtained high-resolution images of the sample surface and the differential tunneling conductance at different cryogenic temperatures. The differential conductance is a direct measurement of the local electronic density of states which provided an insulating gap consistent with optical conductivity, angle resolved photoemission spectroscopy and resonant inelastic x-ray scattering (RIXS) experiments. The observed widths of these features is broader than predicted by the Slater approximation and narrower than predicted by dynamical mean field theory. Additionally, the observed density of states due to magnetic fluctuations is found in the derivative of the differential conductance and is consistent with results from Raman scattering and RIXS. At low temperatures, additional low-energy features were observed, suggesting a change in the dispersion of the collective magnetic excitations, which is consistent with the magnetic susceptibility.
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Submitted 21 February, 2013;
originally announced February 2013.
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Chern numbers hiding in time-of-flight images
Authors:
Erhai Zhao,
Noah Bray-Ali,
Carl J. Williams,
I. B. Spielman,
Indubala I. Satija
Abstract:
We present a technique for detecting topological invariants -- Chern numbers -- from time-of-flight images of ultra-cold atoms. We show that the Chern numbers of integer quantum Hall states of lattice fermions leave their fingerprints in the atoms' momentum distribution. We analytically demonstrate that the number of local maxima in the momentum distribution is equal to the Chern number in two lim…
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We present a technique for detecting topological invariants -- Chern numbers -- from time-of-flight images of ultra-cold atoms. We show that the Chern numbers of integer quantum Hall states of lattice fermions leave their fingerprints in the atoms' momentum distribution. We analytically demonstrate that the number of local maxima in the momentum distribution is equal to the Chern number in two limiting cases, for large hopping anisotropy and in the continuum limit. In addition, our numerical simulations beyond these two limits show that these local maxima persist for a range of parameters. Thus, an everyday observable in cold atom experiments can serve as a useful tool to characterize and visualize quantum states with non-trivial topology.
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Submitted 6 January, 2012; v1 submitted 16 May, 2011;
originally announced May 2011.
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Bilayer Quantum Hall Ferromagnet in a Periodic Potential
Authors:
Jianmin Sun,
Ganpathy Murthy,
H. A. Fertig,
Noah Bray-Ali
Abstract:
The bilayer quantum Hall system at a total filling of $ν_T=1$ has long resisted explanation in terms of a true counterflow superfluid, though many experimental features can be seen to be "almost" that of a superfluid. It is widely believed that quenched disorder is the root cause of this puzzle. Here we model the nonperturbative effects of disorder by investigating the $ν=1$ bilayer in a strong pe…
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The bilayer quantum Hall system at a total filling of $ν_T=1$ has long resisted explanation in terms of a true counterflow superfluid, though many experimental features can be seen to be "almost" that of a superfluid. It is widely believed that quenched disorder is the root cause of this puzzle. Here we model the nonperturbative effects of disorder by investigating the $ν=1$ bilayer in a strong periodic potential. Our model assumes that fermions are gapped and real spins are fully polarized, and concentrates on the pseudospin variable (the layer index), with the external potential coupling to the topological (Pontryagin) density of the pseudospin. We find that as the potential strength increases, there are ground state transitions in which the topological content of the pseudospin configuration changes. These transitions are generically weakly first-order, with a new quadratically dispersing mode (in addition to the linearly dispersing Goldstone mode) sometimes becoming nearly gapless near the transition. We show that this leads to strong suppressions of both the Kosterlitz-Thouless transition temperature and the interlayer tunneling strength, which we treat perturbatively. We discuss how these results might extend to the case of true disorder.
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Submitted 10 March, 2010;
originally announced March 2010.
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Fractal dimension and threshold properties in a spatially correlated percolation model
Authors:
Hongting Yang,
Wen Zhang,
Noah Bray-Ali,
Stephan Haas
Abstract:
We consider the effects of spatial correlations in a two-dimensional site percolation model. By generalizing the Newman-Ziff Monte Carlo algorithm to include spatial correlations, percolation thresholds and fractal dimensions of percolation clusters are obtained. For a wide range of spatial correlations, the percolation threshold differs little from the uncorrelated result. In contrast, the frac…
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We consider the effects of spatial correlations in a two-dimensional site percolation model. By generalizing the Newman-Ziff Monte Carlo algorithm to include spatial correlations, percolation thresholds and fractal dimensions of percolation clusters are obtained. For a wide range of spatial correlations, the percolation threshold differs little from the uncorrelated result. In contrast, the fractal dimension differs sharply from the uncorrelated result for almost all types of correlation studied. We interpret these results in the framework of long-range correlated percolation.
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Submitted 8 August, 2009; v1 submitted 1 August, 2009;
originally announced August 2009.
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Topological order in paired states of fermions in two-dimensions with breaking of parity and time-reversal symmetries
Authors:
N. Bray-Ali,
L. Ding,
S. Haas
Abstract:
We numerically evaluate the entanglement spectrum (singular value decomposition of the wavefunction) of paired states of fermions in two dimensions that break parity and time-reversal symmetries, focusing on the spin-polarized $p_x+ip_y$ case. The entanglement spectrum of the weak-pairing (BCS) phase contains a Majorana zero mode, indicating non-Abelian topological order. In contrast, for the st…
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We numerically evaluate the entanglement spectrum (singular value decomposition of the wavefunction) of paired states of fermions in two dimensions that break parity and time-reversal symmetries, focusing on the spin-polarized $p_x+ip_y$ case. The entanglement spectrum of the weak-pairing (BCS) phase contains a Majorana zero mode, indicating non-Abelian topological order. In contrast, for the strong-pairing (BEC) phase, we find no such mode, consistent with Abelian topological order.
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Submitted 19 August, 2009; v1 submitted 18 May, 2009;
originally announced May 2009.
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Conservation and persistence of spin currents and their relation to the Lieb-Schulz-Mattis twist operators
Authors:
N. Bray-Ali,
Z. Nussinov
Abstract:
Systems with spin-orbit coupling do not conserve "bare" spin current $\bf{j}$. A recent proposal for a conserved spin current $\bf{J}$ [J. Shi {\it et.al} Phys. Rev. Lett. {\bf 96}, 076604 (2006)] does not flow persistently in equilibrium. We suggest another conserved spin current $\bar{\bf{J}}$ that may flow persistently in equilibrium. We give two arguments for the instability of persistent cu…
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Systems with spin-orbit coupling do not conserve "bare" spin current $\bf{j}$. A recent proposal for a conserved spin current $\bf{J}$ [J. Shi {\it et.al} Phys. Rev. Lett. {\bf 96}, 076604 (2006)] does not flow persistently in equilibrium. We suggest another conserved spin current $\bar{\bf{J}}$ that may flow persistently in equilibrium. We give two arguments for the instability of persistent current of the form $\bf{J}$: one based on the equations of motions and another based on a variational construction using Lieb-Schulz-Mattis twist operators. In the absence of spin-orbit coupling, the three forms of spin current coincide.
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Submitted 15 May, 2009; v1 submitted 7 March, 2008;
originally announced March 2008.
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The fidelity approach to the Hubbard model
Authors:
L. Campos Venuti,
M. Cozzini,
P. Buonsante,
F. Massel,
N. Bray-Ali,
P. Zanardi
Abstract:
…the phase diagram, with particular care to the critical points. Specifically we show that close to the Mott transition, taking place at on-site repulsion U=0 and electron density n=1, the fidelity metric satisfies an hyper-scaling form which we calculate. This implies that in general, as one approaches the critical point U=0,…
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We use the fidelity approach to quantum critical points to study the zero temperature phase diagram of the one-dimensional Hubbard model. Using a variety of analytical and numerical techniques, we analyze the fidelity metric in various regions of the phase diagram, with particular care to the critical points. Specifically we show that close to the Mott transition, taking place at on-site repulsion U=0 and electron density n=1, the fidelity metric satisfies an hyper-scaling form which we calculate. This implies that in general, as one approaches the critical point U=0, n=1, the fidelity metric tends to a limit which depends on the path of approach. At half filling, the fidelity metric is expected to diverge as U^{-4} when U is sent to zero.
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Submitted 20 June, 2008; v1 submitted 16 January, 2008;
originally announced January 2008.
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Subarea law of entanglement in nodal fermionic systems
Authors:
Letian Ding,
Noah Bray-Ali,
Rong Yu,
Stephan Haas
Abstract:
We investigate the subarea law scaling properties of the block entropy in bipartite fermionic systems which do not have a finite Fermi surface. It is found that in gapped regimes the leading subarea term is a negative constant, whereas in critical regimes with point nodes the leading subarea law is a logarithmic additive term. At the phase boundary that separates the critical and non-critical re…
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We investigate the subarea law scaling properties of the block entropy in bipartite fermionic systems which do not have a finite Fermi surface. It is found that in gapped regimes the leading subarea term is a negative constant, whereas in critical regimes with point nodes the leading subarea law is a logarithmic additive term. At the phase boundary that separates the critical and non-critical regimes, the subarea scaling shows power-law behavior.
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Submitted 24 September, 2008; v1 submitted 4 January, 2008;
originally announced January 2008.
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Scaling Analysis and Application: Phase Diagram of Magnetic Nanorings and Elliptical Nanoparticles
Authors:
Wen Zhang,
Rohit Singh,
Noah Bray-Ali,
Stephan Haas
Abstract:
The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with an assumption of {\em incomplete} self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring thr…
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The magnetic properties of single-domain nanoparticles with different geometric shapes, crystalline anisotropies and lattice structures are investigated. A recently proposed scaling approach is shown to be universal and in agreement with dimensional analysis coupled with an assumption of {\em incomplete} self-similarity. It is used to obtain phase diagrams of magnetic nanoparticles featuring three competing configurations: in-plane and out-of-plane ferromagnetism and vortex formation. The influence of the vortex core on the scaling behavior and phase diagram is analyzed. Three-dimensional phase diagrams are obtained for cylindrical nanorings, depending on their height, outer and inner radius. The triple points in these phase diagrams are shown to be in linear relationship with the inner radius of the ring. Elliptically shaped magnetic nanoparticles are also studied. A new parametrization for double vortex configurations is proposed, and regions in the phase diagram are identified where the double vortex is a stable ground state.
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Submitted 29 August, 2008; v1 submitted 25 September, 2007;
originally announced September 2007.
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Ordering near the percolation threshold in models of 2D interacting bosons with quenched dilution
Authors:
N. Bray-Ali,
J. E. Moore,
T. Senthil,
A. Vishwanath
Abstract:
Randomly diluted quantum boson and spin models in two dimensions combine the physics of classical percolation with the well-known dimensionality dependence of ordering in quantum lattice models. This combination is rather subtle for models that order in two dimensions but have no true order in one dimension, as the percolation cluster near threshold is a fractal of dimension between 1 and 2: two…
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Randomly diluted quantum boson and spin models in two dimensions combine the physics of classical percolation with the well-known dimensionality dependence of ordering in quantum lattice models. This combination is rather subtle for models that order in two dimensions but have no true order in one dimension, as the percolation cluster near threshold is a fractal of dimension between 1 and 2: two experimentally relevant examples are the O(2) quantum rotor and the Heisenberg antiferromagnet. We study two analytic descriptions of the O(2) quantum rotor near the percolation threshold. First a spin-wave expansion is shown to predict long-ranged order, but there are statistically rare points on the cluster that violate the standard assumptions of spin-wave theory. A real-space renormalization group (RSRG) approach is then used to understand how these rare points modify ordering of the O(2) rotor. A new class of fixed points of the RSRG equations for disordered 1D bosons is identified and shown to support the existence of long-range order on the percolation backbone in two dimensions. These results are relevant to experiments on bosons in optical lattices and superconducting arrays, and also (qualitatively) for the diluted Heisenberg antiferromagnet.
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Submitted 25 July, 2005;
originally announced July 2005.
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Quantum destruction of stiffness in diluted antiferromagnets and superconductors
Authors:
N. Bray-Ali,
J. E. Moore
Abstract:
The reduction of 2D superconducting or antiferromagnetic order by random dilution is studied as a model for the 2D diluted Heisenberg antiferromagnet (DHAF) La$_2$Cu$_{1-p}$(Zn,Mg)$_p$O$_4$ and randomly inhomogeneous 2D suerconductors. We show in simplified models that long-range order can persist at the percolation threshold despite the presence of disordered one-dimensional segments, contrary…
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The reduction of 2D superconducting or antiferromagnetic order by random dilution is studied as a model for the 2D diluted Heisenberg antiferromagnet (DHAF) La$_2$Cu$_{1-p}$(Zn,Mg)$_p$O$_4$ and randomly inhomogeneous 2D suerconductors. We show in simplified models that long-range order can persist at the percolation threshold despite the presence of disordered one-dimensional segments, contrary to the classical case. When long-range order persists to the percolation threshold, charging effects (in the superconductor) or frustrating interactions (in the antiferromagnet) can dramatically modify the stiffness of the order. This quantum destruction of stiffness is used to model neutron scattering data on La$_2$Cu$_{1-p}$(Zn,Mg)$_p$O$_4$. In a certain simplified model, there is a sharp stiffness transition between ``stiff'' and ``floppy'' ordered phases.
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Submitted 10 October, 2003; v1 submitted 30 April, 2003;
originally announced May 2003.