Takumi Iritani
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Takumi Iritani has a total of 67 co-authors. Here are the top co-authors by number of shared publications:
- Hideo Suganuma
Department of Physics Graduate School of Science Kyoto University Kitashirakawa-oiwake 606-8502 Sakyo Kyoto Japan
14 shared publications Shinya Gongyo
9 shared publications- Sinya Aoki
TRIP Headquarters, RIKEN
8 shared publications Takashi Inoue
8 shared publicationsKenji Sasaki
7 shared publicationsNoriyoshi Ishii
7 shared publications
Latest Publications
- Open Access
- 29 May 2019
- Published by Sissa Medialab Srl
- Vol. 334, 090
HAL QCD method and Nucleon-Omega interaction with physical quark masses
In lattice QCD, both direct method and HAL QCD method are used to investigate the two-baryon systems. We show that due to the contamination of the scattering excited states, it is challenging to measure the eigenenergy from the temporal correlation in the direct method, while the HAL QCD method can extract the information of the interaction from both scattering states and ground state by using the spatial correlation. We examine the systematic uncertainty of the derivative expansion in the HAL QCD method, which is found to be well under control at the low energies. By using the time-dependent HAL QCD method, we study the nucleon($N$)-Omega($\Omega$) system in the $^5$S$_2$ channel with almost physical quark masses at $m_\pi \simeq 146$ MeV. We find the interaction is attractive at all distances, which produces a quasi-bound state with the binding energy 1.54(0.30)($^{+0.04}_{-0.10}$) MeV. We also consider the extra Coulomb interaction in the $p\Omega^{-}$($^5$S$_2$) system, whose binding energy becomes 2.46(0.34)($^{+0.04}_{-0.01}$) MeV. $N\Omega$($^5$S$_2$) dibaryon could be searched through two-particle correlations in the heavy ion collision experiments.- 29 May 2019
- Published by Sissa Medialab Srl
- Vol. 334, 090
Open AccessHAL QCD method and Nucleon-Omega interaction with physical quark masses
In lattice QCD, both direct method and HAL QCD method are used to investigate the two-baryon systems. We show that due to the contamination of the scattering excited states, it is challenging to measure the eigenenergy from the temporal correlation in the direct method, while the HAL QCD method can extract the information of the interaction from both scattering states and ground state by using the spatial correlation. We examine the systematic uncertainty of the derivative expansion in the HAL QCD method, which is found to be well under control at the low energies. By using the time-dependent HAL QCD method, we study the nucleon($N$)-Omega($\Omega$) system in the $^5$S$_2$ channel with almost physical quark masses at $m_\pi \simeq 146$ MeV. We find the interaction is attractive at all distances, which produces a quasi-bound state with the binding energy 1.54(0.30)($^{+0.04}_{-0.10}$) MeV. We also consider the extra Coulomb interaction in the $p\Omega^{-}$($^5$S$_2$) system, whose binding energy becomes 2.46(0.34)($^{+0.04}_{-0.01}$) MeV. $N\Omega$($^5$S$_2$) dibaryon could be searched through two-particle correlations in the heavy ion collision experiments. - Open Access
- 1 May 2019
- Published by Elsevier in Physics Letters B
- Vol. 792, 284-289
NΩ dibaryon from lattice QCD near the physical point
- 1 May 2019
- Published by Elsevier in Physics Letters B
- Vol. 792, 284-289
Open AccessNΩ dibaryon from lattice QCD near the physical point
- Open Access
$NΩ$ dibaryon from lattice QCD near the physical point
The nucleon($N$)-Omega($\Omega$) system in the S-wave and spin-2 channel ($^5$S$_2$) is studied from the (2+1)-flavor lattice QCD with nearly physical quark masses ($m_\pi \simeq 146$~MeV and $m_K \simeq 525$~MeV). The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon correlation function to the baryon-baryon potential and eventually to the scattering observables. The $N\Omega$($^5$S$_2$) potential, obtained under the assumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce a quasi-bound state near unitarity: In this channel, the scattering length, the effective range and the binding energy from QCD alone read $a_0= 5.30(0.44)(^{+0.16}_{-0.01})$~fm, $r_{\rm eff} = 1.26(0.01)(^{+0.02}_{-0.01})$~fm, $B = 1.54(0.30)(^{+0.04}_{-0.10})$~MeV, respectively. Including the extra Coulomb attraction, the binding energy of $p\Omega^-$($^5$S$_2$) becomes $B_{p\Omega^-} = 2.46(0.34)(^{+0.04}_{-0.11})$~MeV. Such a spin-2 $p\Omega^-$ state could be searched through two-particle correlations in $p$-$p$, $p$-nucleus and nucleus-nucleus collisions.Open Access$NΩ$ dibaryon from lattice QCD near the physical point
The nucleon($N$)-Omega($\Omega$) system in the S-wave and spin-2 channel ($^5$S$_2$) is studied from the (2+1)-flavor lattice QCD with nearly physical quark masses ($m_\pi \simeq 146$~MeV and $m_K \simeq 525$~MeV). The time-dependent HAL QCD method is employed to convert the lattice QCD data of the two-baryon correlation function to the baryon-baryon potential and eventually to the scattering observables. The $N\Omega$($^5$S$_2$) potential, obtained under the assumption that its couplings to the D-wave octet-baryon pairs are small, is found to be attractive in all distances and to produce a quasi-bound state near unitarity: In this channel, the scattering length, the effective range and the binding energy from QCD alone read $a_0= 5.30(0.44)(^{+0.16}_{-0.01})$~fm, $r_{\rm eff} = 1.26(0.01)(^{+0.02}_{-0.01})$~fm, $B = 1.54(0.30)(^{+0.04}_{-0.10})$~MeV, respectively. Including the extra Coulomb attraction, the binding energy of $p\Omega^-$($^5$S$_2$) becomes $B_{p\Omega^-} = 2.46(0.34)(^{+0.04}_{-0.11})$~MeV. Such a spin-2 $p\Omega^-$ state could be searched through two-particle correlations in $p$-$p$, $p$-nucleus and nucleus-nucleus collisions. - Open Access
Consistency between Lüscher's finite volume method and HAL QCD method for two-baryon systems in lattice QCD
There exist two methods to study two-baryon systems in lattice QCD: the direct method which extracts eigenenergies from the plateaux of the temporal correlator and the HAL QCD method which extracts observables from the non-local potential associated with the tempo-spatial correlator. Although the two methods should give the same results theoretically, qualitatively different results have been reported. Recently, we pointed out that the separation of the ground state from the excited states is crucial to obtain sensible results in the former, while both states provide useful signals in the latter. In this paper, we identify the contribution of each state in the direct method by decomposing the two-baryon correlators into the finite-volume eigenmodes obtained from the HAL QCD method. We consider the $\Xi\Xi$ system in the $^1$S$_0$ channel at $m_\pi = 0.51$ GeV in 2+1 flavor lattice QCD using the wall and smeared quark sources. We demonstrate that the "pseudo-plateau" at early time slices (t = 1~2 fm) from the smeared source in the direct method indeed originates from the contamination of the excited states, and the true plateau with the ground state saturation is realized only at t > 5~15 fm corresponding to the inverse of the lowest excitation energy. We also demonstrate that the two-baryon operator can be optimized by utilizing the finite-volume eigenmodes, so that (i) the finite-volume energy spectra from the HAL QCD method agree with those from the optimized temporal correlator and (ii) the correct spectra would be accessed in the direct method only if highly optimized operators are employed. Thus we conclude that the long-standing issue on the consistency between the L\"uscher's finite volume method and the HAL QCD method for two baryons is now resolved: They are consistent with each other quantitatively only if the excited contamination is properly removed in the former.Open AccessConsistency between Lüscher's finite volume method and HAL QCD method for two-baryon systems in lattice QCD
There exist two methods to study two-baryon systems in lattice QCD: the direct method which extracts eigenenergies from the plateaux of the temporal correlator and the HAL QCD method which extracts observables from the non-local potential associated with the tempo-spatial correlator. Although the two methods should give the same results theoretically, qualitatively different results have been reported. Recently, we pointed out that the separation of the ground state from the excited states is crucial to obtain sensible results in the former, while both states provide useful signals in the latter. In this paper, we identify the contribution of each state in the direct method by decomposing the two-baryon correlators into the finite-volume eigenmodes obtained from the HAL QCD method. We consider the $\Xi\Xi$ system in the $^1$S$_0$ channel at $m_\pi = 0.51$ GeV in 2+1 flavor lattice QCD using the wall and smeared quark sources. We demonstrate that the "pseudo-plateau" at early time slices (t = 1~2 fm) from the smeared source in the direct method indeed originates from the contamination of the excited states, and the true plateau with the ground state saturation is realized only at t > 5~15 fm corresponding to the inverse of the lowest excitation energy. We also demonstrate that the two-baryon operator can be optimized by utilizing the finite-volume eigenmodes, so that (i) the finite-volume energy spectra from the HAL QCD method agree with those from the optimized temporal correlator and (ii) the correct spectra would be accessed in the direct method only if highly optimized operators are employed. Thus we conclude that the long-standing issue on the consistency between the L\"uscher's finite volume method and the HAL QCD method for two baryons is now resolved: They are consistent with each other quantitatively only if the excited contamination is properly removed in the former. - Open Access
- 4 March 2019
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2019 (3) , 7
Consistency between Lüscher’s finite volume method and HAL QCD method for two-baryon systems in lattice QCD
There exist two methods to study two-baryon systems in lattice QCD: the direct method which extracts eigenenergies from the plateaux of the temporal correlation function and the HAL QCD method which extracts observables from the non-local potential associated with the tempo-spatial correlation function. Although the two methods should give the same results theoretically, there have been reported qualitative difference for observables from lattice QCD simulations. Recently, we pointed out in [1, 2] that the separation of the ground state from the excited states is crucial to obtain sensible results in the former, while both states provide useful signals for observables in the latter. In this paper, we identify the contribution of each state in the direct method by decomposing the two-baryon correlation functions into the finite-volume eigenmodes obtained from the HAL QCD method. As in our previous studies, we consider the ΞΞ system in the 1S0 channel at m π = 0.51 GeV in (2+1)-flavor lattice QCD using the wall and smeared quark sources with spatial extents, La = 3.6, 4.3, 5.8 fm. We demonstrate that the “pseudo-plateau” at early time slices (t = 1 ∼ 2 fm) from the smeared source in the direct method indeed originates from the contamination of the excited states, and the plateau with the ground state saturation is realized only at t > 5 ∼ 15 fm corresponding to the inverse of the lowest excitation energy. We also demonstrate that the two-baryon operator can be optimized by utilizing the finite-volume eigenmodes, so that (i) the finite-volume energy spectra from the HAL QCD method agree with those from the temporal correlation function with the optimized operators and (ii) the correct finite-volume spectra would be accessed in the direct method only if highly optimized operators are employed. Thus we conclude that the long-standing issue on the consistency between Lüscher’s finite volume method and the HAL QCD method for two baryons is now resolved at least for this particular system considered here: they are consistent with each other quantitatively only if the excited contamination is properly removed in the former.
- 4 March 2019
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2019 (3) , 7
Open AccessConsistency between Lüscher’s finite volume method and HAL QCD method for two-baryon systems in lattice QCD
There exist two methods to study two-baryon systems in lattice QCD: the direct method which extracts eigenenergies from the plateaux of the temporal correlation function and the HAL QCD method which extracts observables from the non-local potential associated with the tempo-spatial correlation function. Although the two methods should give the same results theoretically, there have been reported qualitative difference for observables from lattice QCD simulations. Recently, we pointed out in [1, 2] that the separation of the ground state from the excited states is crucial to obtain sensible results in the former, while both states provide useful signals for observables in the latter. In this paper, we identify the contribution of each state in the direct method by decomposing the two-baryon correlation functions into the finite-volume eigenmodes obtained from the HAL QCD method. As in our previous studies, we consider the ΞΞ system in the 1S0 channel at m π = 0.51 GeV in (2+1)-flavor lattice QCD using the wall and smeared quark sources with spatial extents, La = 3.6, 4.3, 5.8 fm. We demonstrate that the “pseudo-plateau” at early time slices (t = 1 ∼ 2 fm) from the smeared source in the direct method indeed originates from the contamination of the excited states, and the plateau with the ground state saturation is realized only at t > 5 ∼ 15 fm corresponding to the inverse of the lowest excitation energy. We also demonstrate that the two-baryon operator can be optimized by utilizing the finite-volume eigenmodes, so that (i) the finite-volume energy spectra from the HAL QCD method agree with those from the temporal correlation function with the optimized operators and (ii) the correct finite-volume spectra would be accessed in the direct method only if highly optimized operators are employed. Thus we conclude that the long-standing issue on the consistency between Lüscher’s finite volume method and the HAL QCD method for two baryons is now resolved at least for this particular system considered here: they are consistent with each other quantitatively only if the excited contamination is properly removed in the former.
- Open Access
HAL QCD method and Nucleon-Omega interaction with physical quark masses
In lattice QCD, both direct method and HAL QCD method are used to investigate the two-baryon systems. We show that due to the contamination of the scattering excited states, it is challenging to measure the eigenenergy from the temporal correlation in the direct method, while the HAL QCD method can extract the information of the interaction from both scattering states and ground state by using the spatial correlation. We examine the systematic uncertainty of the derivative expansion in the HAL QCD method, which is found to be well under control at the low energies. By using the time-dependent HAL QCD method, we study the nucleon($N$)-Omega($\Omega$) system in the $^5$S$_2$ channel with almost physical quark masses at $m_\pi \simeq 146$ MeV. We find the interaction is attractive at all distances, which produces a quasi-bound state with the binding energy 1.54(0.30)($^{+0.04}_{-0.10}$) MeV. We also consider the extra Coulomb interaction in the $p\Omega^{-}$($^5$S$_2$) system, whose binding energy becomes 2.46(0.34)($^{+0.04}_{-0.01}$) MeV. $N\Omega$($^5$S$_2$) dibaryon could be searched through two-particle correlations in the heavy ion collision experiments.Open AccessHAL QCD method and Nucleon-Omega interaction with physical quark masses
In lattice QCD, both direct method and HAL QCD method are used to investigate the two-baryon systems. We show that due to the contamination of the scattering excited states, it is challenging to measure the eigenenergy from the temporal correlation in the direct method, while the HAL QCD method can extract the information of the interaction from both scattering states and ground state by using the spatial correlation. We examine the systematic uncertainty of the derivative expansion in the HAL QCD method, which is found to be well under control at the low energies. By using the time-dependent HAL QCD method, we study the nucleon($N$)-Omega($\Omega$) system in the $^5$S$_2$ channel with almost physical quark masses at $m_\pi \simeq 146$ MeV. We find the interaction is attractive at all distances, which produces a quasi-bound state with the binding energy 1.54(0.30)($^{+0.04}_{-0.10}$) MeV. We also consider the extra Coulomb interaction in the $p\Omega^{-}$($^5$S$_2$) system, whose binding energy becomes 2.46(0.34)($^{+0.04}_{-0.01}$) MeV. $N\Omega$($^5$S$_2$) dibaryon could be searched through two-particle correlations in the heavy ion collision experiments. - Open Access
- 23 May 2018
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 120 (21) , 212001
Most Strange Dibaryon from Lattice QCD
The system in the channel (the most strange dibaryon) is studied on the basis of the ()-flavor lattice QCD simulations with a large volume and nearly physical pion mass at a lattice spacing of . We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length , the effective range , and the binding energy . These results indicate that the system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions.- 23 May 2018
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 120 (21) , 212001
Open AccessMost Strange Dibaryon from Lattice QCD
The system in the channel (the most strange dibaryon) is studied on the basis of the ()-flavor lattice QCD simulations with a large volume and nearly physical pion mass at a lattice spacing of . We show that lattice QCD data analysis by the HAL QCD method leads to the scattering length , the effective range , and the binding energy . These results indicate that the system has an overall attraction and is located near the unitary regime. Such a system can be best searched experimentally by the pair-momentum correlation in relativistic heavy-ion collisions. - Open Access
- 1 April 2018
- Published by Oxford University Press (OUP) in Progress of Theoretical and Experimental Physics
- Vol. 2018 (4)
I = 2 ππ scattering phase shift from the HAL QCD method with the LapH smearing
Physical observables, such as the scattering phase shifts and binding energy, calculated from the non-local HAL QCD potential do not depend on the sink operators used to define the potential. In practical applications, the derivative expansion of the non-local potential is employed, so that physical observables may receive some scheme dependence at a given order of the expansion. In this paper, we compare the $$I=2$$ $$\pi\pi$$ scattering phase shifts obtained in the point-sink scheme (the standard scheme in the HAL QCD method) and the smeared-sink scheme (the LapH smearing newly introduced in the HAL QCD method). Although potentials in different schemes have different forms as expected, we find that, for reasonably small smearing size, the resultant scattering phase shifts agree with each other if the next-to-leading-order (NLO) term is taken into account. We also find that the HAL QCD potential in the point-sink scheme has a negligible NLO term for a wide range of energies, which implies good convergence of the derivative expansion, while the potential in the smeared-sink scheme has a non-negligible NLO contribution. The implications of this observation for future studies of resonance channels (such as the $$I=0$$ and $$1$$ $$\pi\pi$$ scatterings) with smeared all-to-all propagators are briefly discussed.- 1 April 2018
- Published by Oxford University Press (OUP) in Progress of Theoretical and Experimental Physics
- Vol. 2018 (4)
Open AccessI = 2 ππ scattering phase shift from the HAL QCD method with the LapH smearing
Physical observables, such as the scattering phase shifts and binding energy, calculated from the non-local HAL QCD potential do not depend on the sink operators used to define the potential. In practical applications, the derivative expansion of the non-local potential is employed, so that physical observables may receive some scheme dependence at a given order of the expansion. In this paper, we compare the $$I=2$$ $$\pi\pi$$ scattering phase shifts obtained in the point-sink scheme (the standard scheme in the HAL QCD method) and the smeared-sink scheme (the LapH smearing newly introduced in the HAL QCD method). Although potentials in different schemes have different forms as expected, we find that, for reasonably small smearing size, the resultant scattering phase shifts agree with each other if the next-to-leading-order (NLO) term is taken into account. We also find that the HAL QCD potential in the point-sink scheme has a negligible NLO term for a wide range of energies, which implies good convergence of the derivative expansion, while the potential in the smeared-sink scheme has a non-negligible NLO contribution. The implications of this observation for future studies of resonance channels (such as the $$I=0$$ and $$1$$ $$\pi\pi$$ scatterings) with smeared all-to-all propagators are briefly discussed. - Open Access
- 26 March 2018
- Published by EDP Sciences in EPJ Web of Conferences
- Vol. 175, 05008
Two-baryon systems from HAL QCD method and the mirage in the temporal correlation of the direct method
Both direct and HAL QCD methods are currently used to study the hadron interactions in lattice QCD. In the direct method, the eigen-energy of two-particle is measured from the temporal correlation. Due to the contamination of excited states, however, the direct method suffers from the fake eigen-energy problem, which we call the “mirage problem,” while the HAL QCD method can extract information from all elastic states by using the spatial correlation. In this work, we further investigate systematic uncertainties of the HAL QCD method such as the quark source operator dependence, the convergence of the derivative expansion of the non-local interaction kernel, and the single baryon saturation, which are found to be well controlled. We also confirm the consistency between the HAL QCD method and the Lüscher’s finite volume formula. Based on the HAL QCD potential, we quantitatively confirm that the mirage plateau in the direct method is indeed caused by the contamination of excited states.
- 26 March 2018
- Published by EDP Sciences in EPJ Web of Conferences
- Vol. 175, 05008
Open AccessTwo-baryon systems from HAL QCD method and the mirage in the temporal correlation of the direct method
Both direct and HAL QCD methods are currently used to study the hadron interactions in lattice QCD. In the direct method, the eigen-energy of two-particle is measured from the temporal correlation. Due to the contamination of excited states, however, the direct method suffers from the fake eigen-energy problem, which we call the “mirage problem,” while the HAL QCD method can extract information from all elastic states by using the spatial correlation. In this work, we further investigate systematic uncertainties of the HAL QCD method such as the quark source operator dependence, the convergence of the derivative expansion of the non-local interaction kernel, and the single baryon saturation, which are found to be well controlled. We also confirm the consistency between the HAL QCD method and the Lüscher’s finite volume formula. Based on the HAL QCD potential, we quantitatively confirm that the mirage plateau in the direct method is indeed caused by the contamination of excited states.
- Open Access
- 26 March 2018
- Published by EDP Sciences in EPJ Web of Conferences
- Vol. 175, 05006
Sanity check for NN bound states in lattice QCD with Lüscher’s finite volume formula – Disclosing Symptoms of Fake Plateaux –
The sanity check is to rule out certain classes of obviously false results, not to catch every possible error. After reviewing such a sanity check for NN bound states with the Lüscher’s finite volume formula [1–3], we give further evidences for the operator dependence of plateaux, a symptom of the fake plateau problem, against the claim [4]. We then present our critical comments on [5] by NPLQCD: (i) Operator dependences of plateaux in NPL2013 [6, 7] exist with the P value of 4–5%. (ii) The volume independence of plateaux in NPL2013 does not prove their correctness. (iii) Effective range expansions (EREs) in NPL2013 violate the physical pole condition. (iv) Their comment is partly based on new data and analysis different from the original ones. (v) Their new ERE does not satisfy the Lüscher’s finite volume formula.
- 26 March 2018
- Published by EDP Sciences in EPJ Web of Conferences
- Vol. 175, 05006
Open AccessSanity check for NN bound states in lattice QCD with Lüscher’s finite volume formula – Disclosing Symptoms of Fake Plateaux –
The sanity check is to rule out certain classes of obviously false results, not to catch every possible error. After reviewing such a sanity check for NN bound states with the Lüscher’s finite volume formula [1–3], we give further evidences for the operator dependence of plateaux, a symptom of the fake plateau problem, against the claim [4]. We then present our critical comments on [5] by NPLQCD: (i) Operator dependences of plateaux in NPL2013 [6, 7] exist with the P value of 4–5%. (ii) The volume independence of plateaux in NPL2013 does not prove their correctness. (iii) Effective range expansions (EREs) in NPL2013 violate the physical pole condition. (iv) Their comment is partly based on new data and analysis different from the original ones. (v) Their new ERE does not satisfy the Lüscher’s finite volume formula.