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Alexandrou C, Bacchio S, De Santis A, Dimopoulos P, Finkenrath J, Frezzotti R, Gagliardi G, Garofalo M, Hadjiyiannakou K, Kostrzewa B, Jansen K, Lubicz V, Petschlies M, Sanfilippo F, Simula S, Tantalo N, Urbach C, Wenger U. Probing the Energy-Smeared R Ratio Using Lattice QCD. Phys Rev Lett 2023; 130:241901. [PMID: 37390427 DOI: 10.1103/physrevlett.130.241901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/13/2023] [Accepted: 05/18/2023] [Indexed: 07/02/2023]
Abstract
We present a first-principles lattice QCD investigation of the R ratio between the e^{+}e^{-} cross section into hadrons and into muons. By using the method of Ref. [1], that allows one to extract smeared spectral densities from Euclidean correlators, we compute the R ratio convoluted with Gaussian smearing kernels of widths of about 600 MeV and central energies from 220 MeV up to 2.5 GeV. Our theoretical results are compared with the corresponding quantities obtained by smearing the KNT19 compilation [2] of R-ratio experimental measurements with the same kernels and, by centering the Gaussians in the region around the ρ-resonance peak, a tension of about 3 standard deviations is observed. From the phenomenological perspective, we have not included yet in our calculation QED and strong isospin-breaking corrections, and this might affect the observed tension. From the methodological perspective, our calculation demonstrates that it is possible to study the R ratio in Gaussian energy bins on the lattice at the level of accuracy required in order to perform precision tests of the standard model.
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Affiliation(s)
- Constantia Alexandrou
- Department of Physics, University of Cyprus, 20537 Nicosia, Cyprus
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Simone Bacchio
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Alessandro De Santis
- Dipartimento di Fisica and INFN, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
| | - Petros Dimopoulos
- Dipartimento di Scienze Matematiche, Fisiche e Informatiche, Università di Parma and INFN, Gruppo Collegato di Parma, Parco Area delle Scienze 7/a (Campus), 43124 Parma, Italy
| | - Jacob Finkenrath
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Roberto Frezzotti
- Dipartimento di Fisica and INFN, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
| | - Giuseppe Gagliardi
- Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy
| | - Marco Garofalo
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - Kyriakos Hadjiyiannakou
- Department of Physics, University of Cyprus, 20537 Nicosia, Cyprus
- Computation-based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Bartosz Kostrzewa
- High Performance Computing and Analytics Lab, Rheinische Friedrich-Wilhelms-Universität Bonn, Friedrich-Hirzebruch-Allee 8, 53115 Bonn, Germany
| | - Karl Jansen
- NIC, DESY, Platanenallee 6, D-15738 Zeuthen, Germany
| | - Vittorio Lubicz
- Dipartimento di Matematica e Fisica, Università Roma Tre and INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy
| | - Marcus Petschlies
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - Francesco Sanfilippo
- Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy
| | - Silvano Simula
- Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy
| | - Nazario Tantalo
- Dipartimento di Fisica and INFN, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy
| | - Carsten Urbach
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - Urs Wenger
- Institute for Theoretical Physics, Albert Einstein Center for Fundamental Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
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Alexandrou C, Bacchio S, Bergner G, Finkenrath J, Gasbarro A, Hadjiyiannakou K, Jansen K, Kostrzewa B, Ottnad K, Petschlies M, Pittler F, Steffens F, Urbach C, Wenger U. Quark and Gluon Momentum Fractions in the Pion from N_{f}=2+1+1 Lattice QCD. Phys Rev Lett 2021; 127:252001. [PMID: 35029455 DOI: 10.1103/physrevlett.127.252001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 11/03/2021] [Indexed: 06/14/2023]
Abstract
We perform the first full decomposition of the pion momentum into its gluon and quark contributions. We employ an ensemble generated by the Extended Twisted Mass Collaboration with N_{f}=2+1+1 Wilson twisted mass clover fermions at maximal twist tuned to reproduce the physical pion mass. We present our results in the MS[over ¯] scheme at 2 GeV. We find ⟨x⟩_{u+d}=0.601(28), ⟨x⟩_{s}=0.059(13), ⟨x⟩_{c}=0.019(05), and ⟨x⟩_{g}=0.52(11) for the separate contributions, respectively, whose sum saturates the momentum sum rule.
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Affiliation(s)
- Constantia Alexandrou
- Department of Physics, University of Cyprus, Nicosia 2109, Cyprus
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Simone Bacchio
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Georg Bergner
- Institute of Theoretical Physics, Friedrich Schiller University Jena, Jena 07743, Germany
| | - Jacob Finkenrath
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Andrew Gasbarro
- Albert Einstein Center, Institute for Theoretical Physics, University of Bern, Bern CH-3012, Switzerland
| | - Kyriakos Hadjiyiannakou
- Department of Physics, University of Cyprus, Nicosia 2109, Cyprus
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | | | - Bartosz Kostrzewa
- High Performance Computing and Analytics Lab, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn 53115, Germany
| | - Konstantin Ottnad
- PRISMA+ Cluster of Excellence and Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Mainz 55099, Germany
| | - Marcus Petschlies
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn 53115, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Bonn 53115, Germany
| | - Ferenc Pittler
- Computation-based Science and Technology Research Center, The Cyprus Institute, Nicosia 2121, Cyprus
| | - Fernanda Steffens
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn 53115, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Bonn 53115, Germany
| | - Carsten Urbach
- Helmholtz-Institut für Strahlen- und Kernphysik, University of Bonn, Bonn 53115, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Bonn 53115, Germany
| | - Urs Wenger
- Albert Einstein Center, Institute for Theoretical Physics, University of Bern, Bern CH-3012, Switzerland
- Department of Theoretical Physics, CERN, Geneva CH-1211, Switzerland
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Alexandrou C, Bacchio S, Bergner G, Constantinou M, Di Carlo M, Dimopoulos P, Finkenrath J, Fiorenza E, Frezzotti R, Garofalo M, Hadjiyiannakou K, Kostrzewa B, Koutsou G, Jansen K, Lubicz V, Mangin-Brinet M, Manigrasso F, Martinelli G, Papadiofantous E, Pittler F, Rossi G, Sanfilippo F, Simula S, Tarantino C, Todaro A, Urbach C, Wenger U. Quark masses using twisted-mass fermion gauge ensembles. Int J Clin Exp Med 2021. [DOI: 10.1103/physrevd.104.074515] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Alexandrou C, Finkenrath J, Funcke L, Jansen K, Kostrzewa B, Pittler F, Urbach C. Ruling Out the Massless Up-Quark Solution to the Strong CP Problem by Computing the Topological Mass Contribution with Lattice QCD. Phys Rev Lett 2020; 125:232001. [PMID: 33337203 DOI: 10.1103/physrevlett.125.232001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 07/20/2020] [Accepted: 09/29/2020] [Indexed: 06/12/2023]
Abstract
The infamous strong CP problem in particle physics can in principle be solved by a massless up quark. In particular, it was hypothesized that topological effects could substantially contribute to the observed nonzero up-quark mass without reintroducing CP violation. Alternatively to previous work using fits to chiral perturbation theory, in this Letter, we bound the strength of the topological mass contribution with direct lattice QCD simulations, by computing the dependence of the pion mass on the dynamical strange-quark mass. We find that the size of the topological mass contribution is inconsistent with the massless up-quark solution to the strong CP problem.
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Affiliation(s)
- Constantia Alexandrou
- Department of Physics, University of Cyprus, P.O. Box 20537, 1678 Nicosia, Cyprus
- Computation-Based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Jacob Finkenrath
- Computation-Based Science and Technology Research Center, The Cyprus Institute, 20 Konstantinou Kavafi Street, 2121 Nicosia, Cyprus
| | - Lena Funcke
- Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5, Canada
| | - Karl Jansen
- NIC, DESY Zeuthen, Platanenallee 6, 15738 Zeuthen, Germany
| | - Bartosz Kostrzewa
- Helmholtz Institut für Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Ferenc Pittler
- Helmholtz Institut für Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Carsten Urbach
- Helmholtz Institut für Strahlen- und Kernphysik, University of Bonn, Nussallee 14-16, 53115 Bonn, Germany
- Bethe Center for Theoretical Physics, University of Bonn, Nussallee 12, 53115 Bonn, Germany
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Capitani S, Dimopoulos P, Frezzotti R, Garofalo M, Kostrzewa B, Pittler F, Rossi GC, Urbach C. Dynamical Generation of Elementary Fermion Mass: First Lattice Evidence. Phys Rev Lett 2019; 123:061802. [PMID: 31491142 DOI: 10.1103/physrevlett.123.061802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/28/2019] [Indexed: 06/10/2023]
Abstract
Using lattice simulations we demonstrate from first principles the existence of a nonperturbative mechanism for elementary particle mass generation in models with gauge fields, fermions, and scalars, if an exact invariance forbids power divergent fermion masses and fermionic chiral symmetries broken at UV scale are maximally restored. We show that in the Nambu-Goldstone phase a fermion mass term, unrelated to the Yukawa operator, is dynamically generated. In models with electroweak interactions weak boson masses are also generated, opening new scenarios for beyond the standard model physics.
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Affiliation(s)
- S Capitani
- Goethe U. Frankfurt, Inst. f. Theor. Phys, Max-von-Laue-Str. 1, 60438 Frankfurt am Main, Germany
| | - P Dimopoulos
- Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, 00184 Rome, Italy
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
| | - R Frezzotti
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
- INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
| | - M Garofalo
- INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
| | - B Kostrzewa
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - F Pittler
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
| | - G C Rossi
- Centro Fermi-Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi, 00184 Rome, Italy
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
- INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
| | - C Urbach
- HISKP (Theory), Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 14-16, 53115 Bonn, Germany
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Capitani S, Divitiis GMD, Dimopoulos P, Frezzotti R, Garofalo M, Knippschild B, Kostrzewa B, Pittler F, Rossi G, Urbach C. Testing a non-perturbative mechanism for elementary fermion mass generation: lattice setup. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201817508009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this contribution we lay down a lattice setup that allows for the nonperturbative study of a field theoretical model where a SU(2) fermion doublet, subjected to non-Abelian gauge interactions, is also coupled to a complex scalar field doublet via a Yukawa and an “irrelevant” Wilson-like term. Using naive fermions in quenched approximation and based on the renormalizedWard identities induced by purely fermionic chiral transformations, lattice observables are discussed that enable: a) in theWigner phase, the determinations of the critical Yukawa coupling value where the purely fermionic chiral transformation become a symmetry up to lattice artifacts; b) in the Nambu-Goldstone phase of the resulting critical theory, a stringent test of the actual generation of a fermion mass term of non-perturbative origin. A soft twisted fermion mass term is introduced to circumvent the problem of exceptional configurations, and observables are then calculated in the limit of vanishing twisted mass.
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Finkenrath J, Alexandrou C, Bacchio S, Charalambous P, Dimopoulos P, Frezzotti R, Jansen K, Kostrzewa B, Rossi G, Urbach C. Simulation of an ensemble of Nf = 2 + 1 + 1 twisted mass cloverimproved fermions at physical quark masses. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201817502003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a general strategy aimed at generating Nf = 2+1+1 configurations with quarks at their physical mass using maximally twisted mass fermions to ensure automatic O(a) improvement, in the presence of a clover term tuned to reduce the charged to neutral pion mass difference. The target system, for the moment, is a lattice of size 643 × 128 with a lattice spacing a ~ 0:08 fm. We show preliminary results on the pion and kaon mass and decay constants.
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Helmes C, Knippschild B, Kostrzewa B, Liu L, Jost C, Ottnad K, Urbach C, Wenger U, Werner M. The η′ meson at the physical point with Nf = 2 Wilson twisted mass fermions. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201817505025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present results for the η′ meson and the topological susceptibility in Nf = 2 flavour lattice QCD. The results are obtained using Wilson twisted mass fermions at maximal twist with pion masses ranging from 340 MeV down to the physical point. A comparison to literature values is performed giving a handle on discretisation effects.
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Capitani S, De Divitiis GM, Dimopoulos P, Frezzotti R, Garofalo M, Knippschild B, Kostrzewa B, Pittler F, Rossi G, Urbach C. Testing a non-perturbative mechanism for elementary fermion
mass generation: numerical results. EPJ Web Conf 2018. [DOI: 10.1051/epjconf/201817508008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Based on a recent proposal according to which elementary particle masses could be generated by a non-perturbative dynamical phenomenon, alternative to the Higgs mechanism, we carry out lattice simulations of a model where a non-abelian strongly interacting fermion doublet is also coupled to a doublet of complex scalar fields via a Yukawa and an “irrelevant" Wilson-like term. In this pioneering study we use naive fermions and work in the quenched approximation. We present preliminary numerical results both in the Wigner and in the Nambu-Goldstone phase, focusing on the observables relevant to check the occurrence of the conjectured dynamical fermion mass generation effect in the continuum limit of the critical theory in its spontaneously broken phase.
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Minc S, Dabkowski J, Kostrzewa B. Electrokinetic phenomena at the ?-Al2 O3 mixture of polar liquids interface. J APPL ELECTROCHEM 1978. [DOI: 10.1007/bf00615386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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