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Author |
Hernandez, P.; Romero-Lopez, F. |
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Title |
The large N-c limit of QCD on the lattice |
Type |
Journal Article |
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Year |
2021 |
Publication  |
European Physical Journal A |
Abbreviated Journal |
Eur. Phys. J. A |
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Volume |
57 |
Issue |
2 |
Pages |
52 - 19pp |
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Abstract |
We review recent progress in the study of the large N-c limit of gauge theories from lattice simulations. The focus is not only the planar limit but also the size of O(N-c(-1)) corrections for values of N-c greater than or similar to 3. Some concrete examples of the topics we include are tests of large- Nc factorization, the topological susceptibility, the glueball, meson and baryon spectra, the chiral dependence of masses and decay constants, and weak matrix elements related to the Delta I = 1/2 rule in kaon decays. |
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Address |
[Romero-Lopez, Fernando] Univ Valencia, Inst Fis Corpuscular, Valencia, Spain, Email: m.pilar.hernandez@uv.es; |
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Springer |
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English |
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ISSN |
1434-6001 |
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Notes |
WOS:000617515000003 |
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no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4718 |
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Author |
Romero-Lopez, F.; Rusetsky, A.; Urbach, C. |
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Title |
Two- and three-body interactions in phi 4 theory from lattice simulations |
Type |
Journal Article |
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Year |
2018 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
78 |
Issue |
10 |
Pages |
846 - 15pp |
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Abstract |
We calculate the one-, two- and three-particle energy levels for different lattice volumes in the complex phi(4) theory on the lattice. We argue that the exponentially suppressed finite-volume corrections for the two- and three-particle energy shifts can be reduced significantly by using the single particle mass, which includes the finite-size effects. We show numerically that, for a set of bare parameters, corresponding to the weak repulsive interaction, one can reliably extract the two- and three-particle energy shifts. From those, we extract the scattering length, the effective range and the effective three-body coupling. We show that the parameters, extracted from the two- and three-particle energy shifts, are consistent. Moreover, the effective three-body coupling is significantly different from zero. |
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Address |
[Romero-Lopez, F.] Univ Valencia, CSIC, IFIC, Paterna 46980, Spain, Email: fernando.romero@uv.es |
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Springer |
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1434-6044 |
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Notes |
WOS:000448080300003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3778 |
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Author |
Hernandez, P.; Pena, C.; Romero-Lopez, F. |
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Title |
Large Nc scaling of meson masses and decay constants |
Type |
Journal Article |
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Year |
2019 |
Publication |
European Physical Journal C |
Abbreviated Journal |
Eur. Phys. J. C |
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Volume |
79 |
Issue |
10 |
Pages |
865 - 13pp |
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Abstract |
We perform an ab initio calculation of the Nc scaling of the low-energy couplings of the chiral Lagrangian of low-energy strong interactions, extracted from the mass dependence of meson masses and decay constants. We compute these observables on the lattice with four degenerate fermions, Nf=4, and varying number of colours, Nc=3-6, at a lattice spacing of a similar or equal to 0.075 fm. We find good agreement with the expected Nc scaling and measure the coefficients of the leading and subleading terms in the large Nc expansion. From the subleading Nc corrections, we can also infer the Nf dependence, that we use to extract the value of the low-energy couplings for different values of Nf. We find agreement with previous determinations at Nc=3 and Nf=2,3 and also, our results support a strong paramagnetic suppression of the chiral condensate in moving from Nf=2 to Nf=3. |
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Address |
[Hernandez, P.; Romero-Lopez, F.] IFIC CSIC UVEG, Edificio Inst Invest,Apt 22085, Valencia 46071, Spain, Email: fernando.romero@uv.es |
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Springer |
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English |
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ISSN |
1434-6044 |
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Expedition |
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Conference |
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Notes |
WOS:000492031700002 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
no |
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Call Number |
IFIC @ pastor @ |
Serial |
4186 |
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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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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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Springer |
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English |
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ISSN |
1434-6044 |
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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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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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Springer |
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English |
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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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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 |
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English |
Summary Language |
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Series Title |
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Abbreviated Series Title |
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ISSN |
1434-6044 |
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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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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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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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Springer |
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English |
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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: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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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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Springer |
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English |
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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: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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Author |
Blanton, T.D.; Romero-Lopez, F.; Sharpe, S.R. |
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Title |
Implementing the three-particle quantization condition including higher partial waves |
Type |
Journal Article |
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Year |
2019 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
03 |
Issue |
3 |
Pages |
106 - 56pp |
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Keywords |
Lattice QCD; Lattice Quantum Field Theory; Scattering Amplitudes |
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Abstract |
We present an implementation of the relativistic three-particle quantization condition including both s- and d-wave two-particle channels. For this, we develop a systematic expansion of the three-particle K matrix, K-df,K-3, about threshold, which is the generalization of the effective range expansion of the two-particle K matrix, K-2. Relativistic invariance plays an important role in this expansion. We find that d-wave two-particle channels enter first at quadratic order. We explain how to implement the resulting multichannel quantization condition, and present several examples of its application. We derive the leading dependence of the threshold three-particle state on the two-particle d-wave scattering amplitude, and use this to test our implementation. We show how strong two-particle d-wave interactions can lead to significant effects on the finite-volume three-particle spectrum, including the possibility of a generalized three-particle Efimov-like bound state. We also explore the application to the 3 pi(+) system, which is accessible to lattice QCD simulations, where we study the sensitivity of the spectrum to the components of K-df,K-3. Finally, we investigate the circumstances under which the quantization condition has unphysical solutions. |
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Address |
[Blanton, Tyler D.; Sharpe, Stephen R.] Univ Washington, Dept Phys, 3910 15th Ave NE, Seattle, WA 98195 USA, Email: blanton1@uw.edu; |
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Springer |
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English |
Summary Language |
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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 |
1029-8479 |
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:000462325900001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3953 |
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Author |
Romero-Lopez, F.; Sharpe, S.R.; Blanton, T.D.; Briceno, R.A.; Hansen, M.T. |
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Title |
Numerical exploration of three relativistic particles in a finite volume including two-particle resonances and bound states |
Type |
Journal Article |
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Year |
2019 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
007 - 43pp |
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Keywords |
Lattice QCD; Scattering Amplitudes |
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Abstract |
In this work, we use an extension of the quantization condition, given in ref. [1], to numerically explore the finite-volume spectrum of three relativistic particles, in the case that two-particle subsets are either resonant or bound. The original form of the relativistic three-particle quantization condition was derived under a technical assumption on the two-particle K matrix that required the absence of two-particle bound states or narrow two-particle resonances. Here we describe how this restriction can be lifted in a simple way using the freedom in the definition of the K-matrix-like quantity that enters the quantization condition. With this in hand, we extend previous numerical studies of the quantization condition to explore the finite-volume signature for a variety of two- and three-particle interactions. We determine the spectrum for parameters such that the system contains both dimers (two-particle bound states) and one or more trimers (in which all three particles are bound), and also for cases where the two-particle subchannel is resonant. We also show how the quantization condition provides a tool for determining infinite-volume dimer-particle scattering amplitudes for energies below the dimer breakup. We illustrate this for a series of examples, including one that parallels physical deuteron-nucleon scattering. All calculations presented here are restricted to the case of three identical scalar particles. |
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Address |
[Romero-Lopez, Fernando] Univ Valencia, CSIC, IFIC, Paterna 46980, Spain, Email: fernando.romero@uv.es; |
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Publisher |
Springer |
Place of Publication |
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Language |
English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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Edition |
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ISSN |
1029-8479 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000497979000001 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4207 |
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