Nuclear Theory·nucl-th

Friday·January 27, 2017

7 papers—3 primary·4 cross-listed

04
[Submitted on 27 Dec 2016] (cross-list from hep-ph)
Subtracting IR Renormalons from Wilson Coefficients: Uniqueness and power dependences on $Λ_{QCD}$
Go Mishima🇩🇪 · Yukinari Sumino🇯🇵 · Hiromasa Takaura🇯🇵
In the context of OPE and using the large- $β_{0}$ approximation, we propose a method to define Wilson coefficients free from uncertainties due to IR renormalons. We first introduce a general observable $X (Q^{2})$ with an explicit IR cutoff, and then we extract a genuine UV contribution $X_{UV}$ as a cutoff-independent part. $X_{UV}$ includes power corrections $\sim (Λ_{QCD}^{2} / Q^{2})^{n}$ which are independent of renormalons. Using the integration-by-regions method, we observe that $X_{UV}$ coincides with the leading Wilson coefficient in OPE and also clarify that the power corrections originate from UV region. We examine scheme dependence of $X_{UV}$ and single out a specific scheme favorable in terms of analytical properties. Our method would be optimal with respect to systematicity, analyticity and stability. We test our formulation with the examples of the Adler function, QCD force between $Q Q ˉ$ , and $R$ -ratio in $e^{+} e^{-}$ collision.
Comments:
55 pages, 11 figures, 1 table. v3: version published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1612.08711 [pdf]
PRD(2017)·11 citations
05
[Submitted on 25 Jan 2017] (cross-list from hep-lat)
Relating the finite-volume spectrum and the two-and-three-particle $S$ matrix for relativistic systems of identical scalar particles
Raúl A. Briceño🇺🇸 · Maxwell T. Hansen🇩🇪 · Stephen R. Sharpe🇺🇸
Working in relativistic quantum field theory, we derive the quantization condition satisfied by coupled two- and three-particle systems of identical scalar particles confined to a cubic spatial volume with periodicity $L$ . This gives the relation between the finite-volume spectrum and the infinite-volume $2 \to 2$ , $2 \to 3$ and $3 \to 3$ scattering amplitudes for such theories. The result holds for relativistic systems composed of scalar particles with nonzero mass $m$ , whose center of mass energy lies below the four-particle threshold, and for which the two-particle $K$ matrix has no singularities below the three-particle threshold. The quantization condition is exact up to corrections of the order $O (e^{- m L})$ and holds for any choice of total momenta satisfying the boundary conditions.
Comments:
47 pages, 19 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1701.07465 [pdf]
PRD(2017)·209 citations
06
[Submitted on 26 Jan 2017] (cross-list from hep-lat)
Möbius domain-wall fermions on gradient-flowed dynamical HISQ ensembles
Evan Berkowitz🇩🇪 · Chris Bouchard🇬🇧 · Chia Cheng Chang🇺🇸 · M. A. Clark🇺🇸 · Balint Joo🇺🇸 · Thorsten Kurth🇺🇸 · Christopher Monahan🇺🇸 · Amy Nicholson🇺🇸 · Kostas Orginos🇺🇸 · Enrico Rinaldi🇺🇸 · Pavlos Vranas🇺🇸 · Andre Walker-Loud🇺🇸
We report on salient features of a mixed lattice QCD action using valence Möbius domain-wall fermions solved on the dynamical $N_{f} = 2 + 1 + 1$ HISQ ensembles generated by the MILC Collaboration. The approximate chiral symmetry properties of the valence fermions are shown to be significantly improved by utilizing the gradient-flow scheme to first smear the HISQ configurations. The greater numerical cost of the Möbius domain-wall inversions is mitigated by the highly efficient QUDA library optimized for NVIDIA GPU accelerated compute nodes. We have created an interface to this optimized QUDA solver in Chroma. We provide tuned parameters of the action and performance of QUDA using ensembles with the lattice spacings $a ≃ {0.15, 0.12, 0.09}$ fm and pion masses $m_{π} ≃ {310, 220, 130}$ MeV. We have additionally generated two new ensembles with $a \sim 0.12$ fm and $m_{π} \sim {400, 350}$ MeV. With a fixed flow-time of $t_{g f} = 1$ in lattice units, the residual chiral symmetry breaking of the valence fermions is kept below 10\% of the light quark mass on all ensembles, $m_{r es} ≲ 0.1 \times m_{l}$ , with moderate values of the fifth dimension $L_{5}$ and a domain-wall height $M_{5} \leq 1.3$ . As a benchmark calculation, we perform a continuum, infinite volume, physical pion and kaon mass extrapolation of $F_{K^{\pm}} / F_{π^{\pm}}$ and demonstrate our results are independent of flow-time, and consistent with the FLAG determination of this quantity at the level of less than one standard deviation.
Comments:
14 pages + refs, 5 figures; v3 is version accepter for publication; v2 includes continuum chiral extrapolation analysis of FK/Fpi and details of two new HISQ ensembles generated
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1701.07559 [pdf]
PRD(2017)·33 citations
07
[Submitted on 26 Jan 2017] (cross-list from hep-lat)
On Lattice Calculation of Electric Dipole Moments and Form Factors of the Nucleon
M. Abramczyk🇺🇸 · S. Aoki🇯🇵 · T. Blum🇺🇸 · T. Izubuchi🇺🇸 · H. Ohki🇺🇸 · S. Syritsyn🇺🇸
We analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF) $F_{3}$ and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor $F_{2}$ due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the CP-violating quark chromo-EDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using background electric field that respects time translation invariance and boundary conditions, and find that it decidedly agrees with the new formula but not the old formula for $F_{3}$ . Finally, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM.
Comments:
27 pages, 25 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1701.07792 [pdf]
PRD(2017)·102 citations

Affiliations

first authorsco-authorsvia INSPIRE

Subtracting IR Renormalons from Wilson Coefficients: Uniqueness and power dependences on ΛQCD​

Relating the finite-volume spectrum and the two-and-three-particle S matrix for relativistic systems of identical scalar particles

Möbius domain-wall fermions on gradient-flowed dynamical HISQ ensembles

On Lattice Calculation of Electric Dipole Moments and Form Factors of the Nucleon

Affiliations

Subtracting IR Renormalons from Wilson Coefficients: Uniqueness and power dependences on $Λ_{QCD}$

Relating the finite-volume spectrum and the two-and-three-particle $S$ matrix for relativistic systems of identical scalar particles