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Author |
Donini, A.; Hernandez, P.; Pena, C.; Romero-Lopez, F. |
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Title |
Dissecting the Delta I=1/2 rule at large N-c |
Type |
Journal Article |
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Year |
2020 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
80 |
Issue |
7 |
Pages |
638 - 12pp |
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Keywords |
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Abstract |
We study the scaling of kaon decay amplitudes with the number of colours, N-c, in a theory with four degenerate flavours, N-f = 4. In this scenario, two current-current operators, Q(+/-), mediate Delta S = 1 transitions, such as the two isospin amplitudes of non-leptonic kaon decays for K -> (pi pi)(I=0,2), A(0) and A(2.) In particular, we concentrate on the simpler K -> pi amplitudes, A(+/-), mediated by these two operators. A diagrammatic analysis of the large-N-c scaling of these observables is presented, which demonstrates the anticorrelation of the leading O(1/N-c) and O(N-f/N-c(2)) corrections in both amplitudes. Using our new N-f = 4 and previous quenched data, we confirm this expectation and show that these corrections are naturally large and may be at the origin of the Delta I = 1/2 rule. The evidence for the latter is indirect, based on the matching of the amplitudes to their prediction in Chiral Perturbation Theory, from which the LO low-energy couplings of the chiral weak Hamiltonian, g(+/-), can be determined. A NLO estimate of the K -> (pi pi)(I=0,2) isospin amplitudes can then be derived, which is in good agreement with the experimental value. |
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Address |
[Donini, Andrea; Hernandez, Pilar; Romero-Lopez, Fernando] IFIC CSIC UVEG, Edificio Inst Invest,Apt 22085, Valencia 46071, Spain, Email: fernando.romero@uv.es |
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Publisher |
Springer |
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Language |
English |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000552393200003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4480 |
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Permanent link to this record |
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Author |
Fischer, M.; Kostrzewa, B.; Liu, L.M.; Romero-Lopez, F.; Ueding, M.; Urbach, C. |
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Title |
Scattering of two and three physical pions at maximal isospin from lattice QCD Extended Twisted Mass Collaboration |
Type |
Journal Article |
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Year |
2021 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
81 |
Issue |
5 |
Pages |
436 - 19pp |
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Keywords |
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Abstract |
We present the first direct N-f = 2 lattice QCD computation of two- and three-pi(+) scattering quantities that includes an ensemble at the physical point. We study the quark mass dependence of the two-pion phase shift, and the three-particle interaction parameters. We also compare to phenomenology and chiral perturbation theory (ChPT). In the two-particle sector, we observe good agreement to the phenomenological fits in s- and d-wave, and obtain M(pi)a(0) = -0.0481(86) at the physical point from a direct computation. In the three-particle sector, we observe reasonable agreement at threshold to the leading order chiral expansion, i.e. a mildly attractive three-particle contact term. In contrast, we observe that the energy-dependent part of the three-particle quasilocal scattering quantity is not well described by leading order ChPT. |
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Address |
[Fischer, Matthias; Ueding, Martin; Urbach, Carsten] Univ Bonn, Helmholtz Inst Strahlen & Kernphys, D-53115 Bonn, Germany, Email: fernando.romero@uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
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Expedition |
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Conference |
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Notes |
WOS:000680425500003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4900 |
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Permanent link to this record |
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Author |
Albandea, D.; Hernandez, P.; Ramos, A.; Romero-Lopez, F. |
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Title |
Topological sampling through windings |
Type |
Journal Article |
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Year |
2021 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
81 |
Issue |
10 |
Pages |
873 - 12pp |
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Keywords |
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Abstract |
We propose a modification of the Hybrid Monte Carlo (HMC) algorithm that overcomes the topological freezing of a two-dimensional U(1) gauge theory with and without fermion content. This algorithm includes reversible jumps between topological sectors – winding steps – combined with standard HMC steps. The full algorithm is referred to as winding HMC (wHMC), and it shows an improved behaviour of the autocorrelation time towards the continuum limit. We find excellent agreement between the wHMC estimates of the plaquette and topological susceptibility and the analytical predictions in the U(1) pure gauge theory, which are known even at finite beta. We also study the expectation values in fixed topological sectors using both HMC and wHMC, with and without fermions. Even when topology is frozen in HMC – leading to significant deviations in topological as well as non-topological quantities – the two algorithms agree on the fixed-topology averages. Finally, we briefly compare the wHMC algorithm results to those obtained with master-field simulations of size L similar to 8 x 10(3). |
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Address |
[Albandea, David; Hernandez, Pilar; Ramos, Alberto; Romero-Lopez, Fernando] UVEG, CSIC, IFIC, Edificio Inst Invest,Apt 22085, Valencia 46071, Spain, Email: David.Albandea@uv.es; |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000703880600001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4979 |
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Permanent link to this record |
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Author |
Garofalo, M.; Romero-Lopez, F.; Rusetsky, A.; Urbach, C. |
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Title |
Testing a new method for scattering in finite volume in the phi(4) theory |
Type |
Journal Article |
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Year |
2021 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
81 |
Issue |
11 |
Pages |
1034 - 5pp |
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Keywords |
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Abstract |
We test an alternative proposal by Bruno and Hansen (J High Energy Phys 2021(6), https://doi.org/10.1007/JHEP06(2021)043, 2021) to extract the scattering length from lattice simulations in a finite volume. For this, we use a scalar phi(4) theory with two mass nondegenerate particles and explore various strategies to implement this new method. We find that the results are comparable to those obtained from the Luscher method, with somewhat smaller statistical uncertainties at larger volumes. |
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Address |
[Garofalo, Marco; Rusetsky, Akaki; Urbach, Carsten] Rheinische Friedrich Wilhelms Univ Bonn, HISKP Theory, Nussallee 14-16, D-53115 Bonn, Germany, Email: garofalo@hiskp.uni-bonn.de |
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Corporate Author |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000722881700006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5035 |
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Permanent link to this record |
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Author |
Drach, V.; Fritzsch, P.; Rago, A.; Romero-Lopez, F. |
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Title |
Singlet channel scattering in a composite Higgs model on the lattice |
Type |
Journal Article |
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Year |
2022 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
82 |
Issue |
1 |
Pages |
47 - 10pp |
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Keywords |
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Abstract |
We present the first calculation of the scattering amplitude in the singlet channel beyond QCD. The calculation is performed in SU(2) gauge theory with N-f = 2 fundamental Dirac fermions and based on a finite-volume scattering formalism. The theory exhibits a SU (4) -> Sp(4) chiral symmetry breaking pattern that is used to design minimal composite Higgs models currently tested at the LHC. Our results show that, for the range of underlying fermion mass considered, the lowest flavour singlet state is stable. |
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Address |
[Drach, Vincent; Fritzsch, Patrick; Rago, Antonio] Univ Plymouth, Ctr Math Sci, Plymouth PL4 8AA, Devon, England, Email: fernando.romero@uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Springer |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1434-6044 |
ISBN |
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Medium |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000744537400008 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
5097 |
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Permanent link to this record |