Nuclear Theory·nucl-th

Monday·March 13, 2017

10 papers—6 primary·4 cross-listed

07
A Subleading Operator Basis and Matching for $g g \to H$
Ian Moult🇺🇸 · Iain W. Stewart🇺🇸 · Gherardo Vita🇺🇸
The Soft Collinear Effective Theory (SCET) is a powerful framework for studying factorization of amplitudes and cross sections in QCD. While factorization at leading power has been well studied, much less is known at subleading powers in the $λ ≪ 1$ expansion. In SCET subleading soft and collinear corrections to a hard scattering process are described by power suppressed operators, which must be fixed case by case, and by well established power suppressed Lagrangians, which correct the leading power dynamics of soft and collinear radiation. Here we present a complete basis of power suppressed operators for $g g \to H$ , classifying all operators which contribute to the cross section at $O (λ^{2})$ , and showing how helicity selection rules significantly simplify the construction of the operator basis. We perform matching calculations to determine the tree level Wilson coefficients of our operators. These results are useful for studies of power corrections in both resummed and fixed order perturbation theory, and for understanding the factorization properties of gauge theory amplitudes and cross sections at subleading power. As one example, our basis of operators can be used to analytically compute power corrections for $N$ -jettiness subtractions for $g g$ induced color singlet production at the LHC.
↳ hep-phnucl-thJHEP(2017)·77 citations
08
A Complete Basis of Helicity Operators for Subleading Factorization
Ilya Feige🇺🇸 · Daniel W. Kolodrubetz🇺🇸 · Ian Moult🇺🇸 · Iain W. Stewart🇺🇸
Factorization theorems underly our ability to make predictions for many processes involving the strong interaction. Although typically formulated at leading power, the study of factorization at subleading power is of interest both for improving the precision of calculations, as well as for understanding the all orders structure of QCD. We use the SCET helicity operator formalism to construct a complete power suppressed basis of hard scattering operators for $e^{+} e^{-} \to$ dijets, $e^{-} p \to e^{-}$ jet, and constrained Drell-Yan, including the first two subleading orders in the amplitude level power expansion. We analyze the form of the hard, jet, and soft function contributions to the power suppressed cross section for $e^{+} e^{-} \to$ dijet event shapes, and give results for the lowest order matching to the contributing operators. These results will be useful for studies of power corrections both in fixed order and resummed perturbation theory.
↳ hep-phnucl-thJHEP(2017)·91 citations
09
Pseudomagnetic lens as a valley and chirality splitter in Dirac and Weyl materials
E. V. Gorbar🇺🇦 · V. A. Miransky🇨🇦 · I. A. Shovkovy🇺🇸 · P. O. Sukhachov🇨🇦
It is proposed that strain-induced pseudomagnetic fields in Dirac and Weyl materials could be used as valley and chirality sensitive lenses for beams of Weyl quasiparticles. The study of the (pseudo-)magnetic lenses is performed by using the eikonal approximation for describing the Weyl quasiparticles propagation in magnetic and strain-induced pseudomagnetic fields. Analytical expressions for the locations of the principal foci and the focal lengths are obtained in the paraxial approximation in the models with uniform as well as nonuniform effective magnetic fields inside the lens. The results show that the left- and right-handed quasiparticles can be focused at different spatial locations when both magnetic and pseudomagnetic fields are applied. It is suggested that the use of magnetic and pseudomagnetic lenses could open new ways of producing and manipulating beams of chiral Weyl quasiparticles.
↳ cond-mat.mes-hallhep-phnucl-thPRB(2017)·17 citations
10
Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production
B. Trzeciak🇳🇱 · C. Da Silva🇺🇸 · E.G. Ferreiro🇪🇸 · C. Hadjidakis🇫🇷 · D. Kikola🇵🇱 · J.P. Lansberg🇫🇷 · L. Massacrier🇫🇷 · J. Seixas🇵🇹 · A. Uras🇫🇷 · Z. Yang🇨🇳
We outline the case for heavy-ion-physics studies using the multi-TeV lead LHC beams in the fixed-target mode. After a brief contextual reminder, we detail the possible contributions of AFTER@LHC to heavy-ion physics with a specific emphasis on quarkonia. We then present performance simulations for a selection of observables. These show that $Υ (n S)$ , $J / ψ$ and $ψ (2 S)$ production in heavy-ion collisions can be studied in new energy and rapidity domains with the LHCb and ALICE detectors. We also discuss the relevance to analyse the Drell-Yan pair production in asymmetric nucleus-nucleus collisions to study the factorisation of the nuclear modification of partonic densities and of further quarkonia to restore their status of golden probes of the quark-gluon plasma formation.
↳ nucl-exhep-exhep-phnucl-thFew Body Syst.(2017)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE

A Subleading Operator Basis and Matching for gg→H

A Complete Basis of Helicity Operators for Subleading Factorization

Pseudomagnetic lens as a valley and chirality splitter in Dirac and Weyl materials

Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production

Affiliations

A Subleading Operator Basis and Matching for $g g \to H$