REVIEW
Aharonov-Bohm effect and nucleon-nucleon phase shifts on the lattice
Nuclear Theory · Submitted 14 Feb 2004 · 18 references
Pith's verdict: A clean, cheap idea — twist the boundary conditions to scan NN phase shifts — but the L = 5 fm headline rests on an illustrative estimate whose own error term is ~25% at the advertised momentum.
T0 · AI review
Why Pith says this
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Referee report
The paper
The paper claims
A zero-field vector potential lets a small lattice box yield nucleon-nucleon phase shifts at many momenta.
The reading
What carries the argument
The carrying object is the finite-volume function $S(eta, phi) = lim sum_{|n|<N} 1/(n^2 - eta) - 4 pi N$, summed over the twisted momentum lattice, which replaces the ordinary Luescher zeta function. The twist enters only through the shifted third component of the integer vector, so the whole effect of the Aharonov-Bohm potential is captured by the allowed momenta $q_{x,y} = 2 pi n_{x,y}/L$, $q_z = 2 pi (n_z + phi/2 pi)/L$. Matching the poles of the finite-volume correlator to the effective-field-theory amplitude, which resums contact interactions with an increasing number of derivatives, gives the quantisation condition that converts a measured energy level into $k cot d$. The same change of variables that removes the potential from the quark action turns it into twisted boundary conditions on the nucleon fields, which is what makes the argument transparent in the effective theory.
Extended reading notes
Core claim
The claim is that a background gauge potential with zero field strength, combined with the standard relation between finite-volume energy shifts and scattering phase shifts, converts a lattice simulation into a tunable probe of nucleon-nucleon scattering. Concretely, the author derives the modified quantisation condition $k L cot d = (1/pi) S(k^2 L^2 / 4 pi^2, phi)$, where $S$ is a sum over momenta shifted by the twist, $n = (n_x, n_y, n_z + phi/2 pi)$, and shows that the pole structure of $S$ moves continuously with the flux. Tuning the twist near $phi = pi$ pushes the free two-nucleon ground state down to energies of a few MeV even for $L = 5$ fm, which the author illustrates for both the spin-singlet channel, using $a_s = 23.7$ fm and $r_{0s} = 2.73$ fm, and the spin-triplet channel, using $a_t = 5.425$ fm and $r_{0t} = 1.75$ fm. The payoff claimed is twofold: lattices roughly half the linear size previously thought necessary, and phase shifts at a continuum of momenta rather than at a single kinematic point per box.
Load-bearing premise
The feasibility estimate assumes that the leading contact interaction alone, evaluated with experimental scattering lengths and effective ranges, correctly predicts the finite-volume energy levels, and that higher partial waves and tensor forces stay suppressed at the twist values used.
Editorial extensions
If this is right
- Lattice collaborations could extract nucleon-nucleon phase shifts across a range of momenta from a single small box by scanning the twist parameter, instead of enlarging the box to reach new kinematic points.
- Boxes of about 5 fm become viable for the two-nucleon sector, which is close to the floor set by exponentially small finite-pion-mass corrections of order $e^{-m_pi L}$, about 0.03 at that size.
- The same trick applies to any hadronic interaction where a conserved charge can be coupled to a zero-strength potential, though positivity of the fermion determinant restricts it to flavour-neutral or baryon-number couplings unless the calculation is quenched.
- Because the method determines phase shifts rather than a potential, the output can be matched directly onto the low-energy constants of the contact effective field theory.
Reading between the lines
- If the higher-partial-wave contamination really scales as $(Q/m_pi)^3$ and the tensor-force contribution as $(Q/m_pi)^4$, the method could be pushed somewhat above $m_pi/2$; the paper does not test where those suppressions actually break down numerically.
- A practical test would be to run the same twisted-boundary simulation at two box sizes and check that the extracted $k cot d$ agrees, since a systematic error from neglected partial waves would show up as a residual volume dependence.
- Extending the twist to more than one spatial direction would give a multi-parameter tuning knob, potentially allowing several energy levels to be brought into the useful window simultaneously rather than one at a time.
Original abstract
We propose a method for the lattice QCD computation of nucleon-nucleon low-energy interactions. It consists in simulating QCD in the background of a ''electromagnetic" field whose potential is non-vanishing, but whose field strength is zero. By tuning the background field, phase-shifts at any (but small) momenta can be determined by measuring the shift of the ground state energy. Lattice sizes as small as 5 Fermi can be sufficient for the calculation of phase shifts up to momenta of order of $m_{\pi}/2$.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We propose a method for the lattice QCD computation of nucleon-nucleon low-energy interactions. It consists in simulating QCD in the background of a ''electromagnetic" field whose potential is non-vanishing, but whose field strength is zero. By tuning the background field, phase-shifts at any (but small) momenta can be determined by measuring the shift of the ground state energy. Lattice sizes as small as 5 Fermi can be sufficient for the calculation of phase shifts up to momenta of order of $m_{\pi}/2$.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We propose a method for the lattice QCD computation of nucleon-nucleon low-energy interactions. | contribution 0.99 | 0.56 | 0.24 | asserted 0.77 |
| s1 | It consists in simulating QCD in the background of a ''electromagnetic" field whose potential is non-vanishing, but whose field strength is zero. | method 0.99 | 0.34 | 0.07 | asserted 1.00 |
| s2 | By tuning the background field, phase-shifts at any (but small) momenta can be determined by measuring the shift of the ground state energy. | method 0.97 | 0.41 | 0.40 | asserted 0.83 |
| s3 | Lattice sizes as small as 5 Fermi can be sufficient for the calculation of phase shifts up to momenta of order of $m_{\pi}/2$. | result 0.89 | 0.62 | 0.21 | hedged possibility 0.89 |
What was examined, and what was not
- arXiv listing abstract v1
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
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- R cross-paper relations
References
How later papers used it
93 later papers cite it
5 later papers by other authors are listed below: 5 used its method or tool.
Uses its method or tool 5 of 50 papers with this label
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Used the so-called twisted boundary condition, which this paper has proven to be advantageous, to achieve its goal.
Scalar mesons in a finite volume (2010) · 0.93 · paraphrased: the licence does not allow quoting
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We keep the same value of $p⃗_$ on the other lattices by introducing flavour-twisted boundary conditions [ref] for the strange quark (cf. Ref. [ref] ).
Extraction of the bare form factors for the semi-leptonic $B_s$ decays (2017) · Introduction: definitions, ensembles, measurements · 1.00
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Computed the quark propagators by imposing the twisted boundary conditions of this paper to make those momenta small and remain close to the zero recoil point.
'Bs --> Ds l nu' near zero recoil in and beyond the Standard Model (2013) · 1.00 · paraphrased: the licence does not allow quoting
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Simulated near-zero momentum transfers by employing the twisted boundary condition of this paper for the valence quarks to suppress higher order contributions not known in ChPT.
Light meson electromagnetic form factors from three-flavor lattice QCD with exact chiral symmetry (2015) · 1.00 · paraphrased: the licence does not allow quoting
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Imposed non-periodic boundary conditions on valence quarks from this paper to inject arbitrary values of quark momenta and cover the full physical q^2 range.
Form factors of the $D \to \pi$ and $D \to K$ semileptonic decays with $N_f = 2$ twisted mass lattice QCD (2011) · 0.99 · paraphrased: the licence does not allow quoting
How the literature uses it
92 arXiv papers cite this in 113 sentences
Papers citing it · 47 sentences without a confident label
Uses its method or tool 50 papers
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This spectrum can be used to constrain the infinite-volume scattering amplitudes via the Lüscher method [ref] – for a recent review see Ref. [ref] .
The quark-mass dependence of elastic $\pi K$ scattering from QCD · Introduction · 0.90
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We obtain results at non zero momentum transfer with good accuracy by enforcing special boundary conditions on the quark fields, called flavor twisted [ref] , that shift by an arbitrary amount the discretized set of lattice momenta (see also [ref] ).
Quenched lattice calculation of the vector channel B --> D* l nu decay rate · Introduction · 0.91
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In order to reach small momentum transfers for the pion form factor and $q^2=0$ for the $K→π$ form factors, we use partially twisted boundary conditions [ref] , combining gauge field configurations generated with sea quarks obeying periodic boundary conditions with valence quarks with twisted boundary conditions [ref] .
Kl3 and pion form factors using partially twisted boundary conditions · The Form Factors · 0.99
Cites it as background 8 papers
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The precise relationship is encoded in the Lüscher quantization condition [ref] , which can be written as [This is valid for any two-hadron to two-hadron scattering process – significant recent steps towards a general quantization condition relevant for three-hadron channels have been made [ref] .]
Efficient solution of the multi-channel L\"uscher determinant condition through eigenvalue decomposition · Introduction · 0.83
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In traditional lattice calculations [ref] , the on shell transition factor is determined by the extrapolation of the off shell transition factors with nonzero photon virtualities, or by so-called twisted boundary conditions [ref] where an appropriate twisted angle is tuned to put the transition factor on shell directly.
Lattice study of $J/\psi \rightarrow \gamma\eta_c$ using a method without momentum extrapolation · Introduction · 0.85
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The progress made in the field is in large part due to the extensive and growing literature [ref] dedicated to deriving the relation between finite- and infinite-volume observables.
Inclusive reactions from finite Minkowski spacetime correlation functions · Introduction · 0.95
Discussion
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