Benvenuti nell'Anagrafe della Ricerca d'Ateneo
La valutazione delle attività di ricerca che si svolgono nelle università ha assunto un'importanza rilevante sia per l'intero sistema universitario sia all'interno di ogni singolo ateneo. Roma Tre si è quindi dotata di idonei strumenti informativi in grado di supportare al meglio le azioni di monitoraggio e di valutazione delle attività di ricerca svolte nei propri dipartimentied ha realizzato una Anagrafe della Ricerca di Ateneo.
EnglishWe evaluate by means of lattice QCD calculations the low-energy constant ℓ7 which parametrizes strong isospin effects at next-to-leading order (NLO) in SU(2) chiral perturbation theory. Among all low-energy constants at NLO, ℓ7 is the one known less precisely, and its uncertainty is currently larger than 50%. Our strategy is based on the RM123 approach in which the lattice path-integral is expanded in powers of the isospin breaking parameter Δm=(md-mu)/2. In order to evaluate the relevant lattice correlators we make use of the recently proposed rotated twisted-mass (RTM) scheme. Within the RM123 approach, it is possible to cleanly extract the value of ℓ7 from either the pion mass splitting Mπ+-Mπ0 induced by strong isospin breaking at order O((Δm)2) (mass method), or from the coupling of the neutral pion π0 to the isoscalar operator (u¯γ5u+d¯γ5d)/2 at order O(Δm) (matrix element method). In this pilot study we limit the analysis to a single ensemble generated by the Extended Twisted Mass Collaboration (ETMC) with Nf=2+1+1 dynamical quark flavors, which corresponds to a lattice spacing a≃0.095 fm and to a pion mass Mπ≃260 MeV. We find that the matrix element method outperforms the mass method in terms of resulting statistical accuracy. Our determination, ℓ7=2.5(1.4)×10-3, is in agreement and improves previous calculations.
Frezzotti, R., Gagliardi, G., Lubicz, V., Martinelli, G., Sanfilippo, F., & Simula, S. (2021). First direct lattice calculation of the chiral perturbation theory low-energy constant ℓ7. PHYSICAL REVIEW D, 104(7) [10.1103/PhysRevD.104.074513].
| Titolo: | First direct lattice calculation of the chiral perturbation theory low-energy constant ℓ7 | |
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| Data di pubblicazione: | 2021 | |
| Rivista: | ||
| Citazione: | Frezzotti, R., Gagliardi, G., Lubicz, V., Martinelli, G., Sanfilippo, F., & Simula, S. (2021). First direct lattice calculation of the chiral perturbation theory low-energy constant ℓ7. PHYSICAL REVIEW D, 104(7) [10.1103/PhysRevD.104.074513]. | |
| Handle: | http://hdl.handle.net/11590/393340 | |
| Appare nelle tipologie: | 1.1 Articolo in rivista |
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