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Register a new userScalar correlators near the 3-flavor thermal critical point
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We investigate screening masses at both sides of the first order finite temperature transition with 3 quark flavors using the nonperturbatively improved clover fermion action and the Iwasaki gauge action. We have developed the method of hierarchical truncations with stochastic probing to accelerate the noise estimator for evaluating quark loops at every spatial lattice slices. At parameter values we study, the flavor singlet scalar meson has a screening mass about half of the pion screening mass. It becomes lighter as the system approaches the critical endpoint.
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We investigate the critical endline of the finite temperature phase transition of QCD around the SU(3)-flavor symmetric point at zero chemical potential. We employ the renormalization-group improved Iwasaki gauge action and non-perturbatively $O(a)$-improved Wilson-clover fermion action. The critical endline is determined by using the intersection point of kurtosis, employing the multi-parameter, multi-ensemble reweighting method to calculate observables off the SU(3)-symmetric point, at the temporal size $N_{rm T}$=6 and lattice spacing as low as $a approx 0.19$ fm. We confirm that the slope of the critical endline takes the value of $-2$, and find that the second derivative is positive, at the SU(3)-flavor symmetric point on the Columbia plot parametrized with the strange quark mass $m_s$ and degenerated up-down quark mass $m_{rm l}$.
We present an update on our results of nucleon form factors measured on a large-volume lattice $(8.1rm{fm})^4$ at almost the physical point in 2+1 flavor QCD. The configurations are generated with the stout-smeared $mathcal{O}(a)$ improved Wilson quark action and Iwasaki gauge action at $beta = 1.82$, which corresponds to the lattice spacing of 0.085 fm. The pion mass at the simulation point is about 145 MeV. We determine the iso- vector electric radius and magnetic moment from nucleon electric ($G_E$) and magnetic ($G_M$) form factors. We also report on preliminary results of the axial-vector ($F_A$), induced pseudo-scalar ($F_P$) and pseudo-scalar ($G_P$) form factors in order to verify the axial Ward- Takahashi identity in terms of the nucleon matrix elements, which may be called as the generalized Goldberger-Treiman relation.
We investigate the QCD phase diagram and the location of the critical end point (CEP) in the SU(2) Polyakov$-$Nambu$-$Jona-Lasinio model with entanglement interaction giving special attention to the $pi$ and $sigma$-mesons properties, namely the decay widths $sigmarightarrowpipi$, for several conditions around the CEP: we focus on the possible $sigmarightarrowpipi$ decay along the isentropic trajectories close to the CEP since the hydrodynamical expansion of a heavy-ion collision fireball nearly follows trajectories of constant entropy. It is expected that the type of transition the dense medium goes through as it expands after the thermalization determines the behavior of this decay. It is shown that no pions are produced from the sigma decay in the chirally symmetric phase if the isentropic lines approach the first order line from chemical potentials above it. Near the CEP or above the $sigmarightarrowpipi$ decay is possible with a high decay width.
Heavy-heavy-light-light (HHLL) correlators of pairwise identical scalars in CFTs with a large central charge in any number of dimensions admit a double scaling limit where the ratio of the heavy conformal dimension to the central charge becomes large as the separation between the light operators becomes null. In this limit the stress tensor sector of a generic HHLL correlator receives contributions from the multi stress tensor operators with any number of stress tensors, as long as their twist is not increased by index contractions. We show how one can compute this leading twist stress tensor sector when the conformal dimension of the light operators is large and the stress tensor sector approximates the thermal CFT correlator. In this regime the value of the correlator is related to the length of the spacelike geodesic which approaches the boundary of the dual asymptotically AdS spacetime at the points of light operator insertions. We provide a detailed description of the infinite volume limit. In two spacetime dimensions the HHLL Virasoro vacuum block is reproduced, while in four spacetime dimensions the result is written in terms of elliptic integrals.
We present the first calculation within lattice QCD of excited light meson resonances with $J^{PC} = 1^{--}$, $2^{--}$ and $3^{--}$. Working with an exact SU(3) flavor symmetry, for the singlet representation of pseudoscalar-vector scattering, we find two $1^{--}$ resonances, a lighter broad state and a heavier narrow state, a broad $2^{--}$ resonance decaying in both $P$- and $F$-waves, and a narrow $3^{--}$ state. We present connections to experimental $omega^star_J, phi^star_J$ resonances decaying into $pi rho$, $Kbar{K}^*$, $eta omega$ and other final states.
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