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The infrared effective theory of adjoint QCD with one Dirac flavour is still under debate. The theory could be confining, conformal, or with a massless fermion in the infrared. The study of chiral symmetry seems to be important to answer this question. While previous investigations have considered Wilson fermions, we present here the first results for this theory based on overlap fermions to avoid explicit chiral symmetry breaking. These indicate spontaneous chiral symmetry breaking by the formation of a fermion condensate. We have also investigated the running coupling of the theory, which indicates no infrared conformality in the energy region we have explored., 8 pages, 4 figures, submitted to proceedings of the 39th International Symposium on Lattice Field Theory (LATTICE2022)

In this work we perform a perturbative study of the Noether supercurrent operator in the context of supersymmetric N=1 Yang-Mills theory on the lattice. The supercurrent mixes with several other operators, some of which are not gauge invariant, having the same quantum numbers. We determine, to one-loop order, the renormalization and all corresponding mixing coefficients by computing the relevant Green’s functions of each one of the mixing operators with external elementary fields. Our calculations are performed both in dimensional and lattice regularization. From the first regularization we obtain the MS¯-renormalized Green’s functions; comparison of the latter with the corresponding Green’s functions in the lattice regularization leads to the extraction of the lattice renormalization factors and mixing coefficients in the MS¯ scheme. The lattice calculations are performed to lowest order in the lattice spacing, using Wilson gluons and clover improved gluinos. The lattice results can be used in nonperturbative studies of supersymmetric Ward identities.

Pseudoscalar-pole diagrams are an important component of estimates of the hadronic light-by-light (HLbL) contribution to the muon $g-2$. We report on our computation of the transition form factors $\mathcal{F}_{P \rightarrow \gamma^* \gamma^*}$ for the neutral pseudoscalar mesons $P=\pi^0$ and $\eta$. The calculation is performed using twisted-mass lattice QCD with physical quark masses. On the lattice, we have access to a broad range of (space-like) photon four-momenta and therefore produce form factor data complementary to the experimentally accessible single-virtual direction, which directly leads to an estimate of the pion- and $\eta$-pole components of the muon $g-2$. For the pion, our result for the $g-2$ contribution in the continuum is comparable with previous lattice and data-driven determinations, with combined relative uncertainties below $10\%$. For the $\eta$ meson, we report on a preliminary determination from a single lattice spacing.

We present a determination of the ratio of kaon and pion leptonic decay constants in isosymmetric QCD (ISOQCD), fK/fπ, making use of the gauge ensembles produced by the Extended Twisted Mass Collaboration with Nf=2+1+1 flavors of Wilson-clover twisted-mass quarks, including configurations close to the physical point for all dynamical flavors. The simulations are carried out at three values of the lattice spacing ranging from ∼0.068 to ∼0.092 fm with linear lattice size up to L∼5.5 fm. The scale is set by the particle data group (PDG) value of the pion decay constant, fπISOQCD=130.4(2) MeV, at the ISOQCD pion point, MπISOQCD=135.0(2) MeV, obtaining for the gradient-flow scales the values w0=0.17383(63) fm, t0=0.14436(61) fm and t0/w0=0.11969(62) fm. The data are analyzed within the framework of SU(2) chiral perturbation theory without resorting to the use of renormalized quark masses. At the ISOQCD kaon point MKISOQCD=494.2(4) MeV we get (fK/fπ)ISOQCD=1.1995(44), where the error includes both statistical and systematic uncertainties. Implications for the Cabibbo-Kobayashi-Maskawa matrix element |Vus| and for the first-row Cabibbo-Kobayashi-Maskawa unitarity are discussed.

We present a preliminary study of the pion, kaon and D-meson masses and decay constants in isosymmetric QCD, as well as a preliminary result for the light-quark renormalized mass. The analysis is based on the gauge ensembles produced by ETMC with Nf = 2 + 1 + 1 flavours of Wilson-clover twisted mass quarks, spanning a range of lattice spacings from ∼ 0.10 to 0.07 fm and include configurations at the physical pion point on lattices with linear size up to L ∼ 5.6 fm.

The fundamental constituents of matter and the forces between them are splendidly described by the Standard Model of elementary particle physics. Despite its great success, it will be superseded by more comprehensive theories that are able to include phenomena, which are not covered by the Standard Model. Among the attempts in this direction are supersymmetry and Technicolor models. We report about our non-perturbative investigations of the characteristic properties of such models by numerical simulations on high-performance computers.

Supersymmetry (SUSY) has been proposed to be a central concept for the physics beyond the standard model and for a description of the strong interactions in the context of the AdS/CFT correspondence. A deeper understanding of these developments requires the knowledge of the properties of supersymmetric models at finite temperatures. We present a Monte Carlo investigation of the finite temperature phase diagram of the N=1 supersymmetric Yang-Mills theory (SYM) regularised on a space-time lattice. The model is in many aspects similar to QCD: quark confinement and fermion condensation occur in the low temperature regime of both theories. A comparison to QCD is therefore possible. The simulations show that for N=1 SYM the deconfinement temperature has a mild dependence on the fermion mass. The analysis of the chiral condensate susceptibility supports the possibility that chiral symmetry is restored near the deconfinement phase transition., 26 pages, 12 figures

In this work a lattice formulation of a supersymmetric theory is proposed and tested that preserves the complete supersymmetry on the lattice. The results of a one-dimensional nonperturbative simulation show the realization of the full supersymmetry and the correct continuum limit of the theory. It is proven that the violation of supersymmetry due to the absence of the Leibniz rule on the lattice can be amended only with a nonlocal derivative and nonlocal interaction term. The fermion doubling problem is also discussed, which leads to another important source of supersymmetry breaking on the lattice. This problem is also solved with a nonlocal realization., 31 pages, 5 figures; mass data and references corrected

We present a determination of the ratio of kaon and pion leptonic decay constants in isosymmetric QCD (ISOQCD), fK/fπ, making use of the gauge ensembles produced by the Extended Twisted Mass Collaboration with Nf = 2 + 1 + 1 flavors of Wilson-clover twisted-mass quarks, including configurations close to the physical point for all dynamical flavors. The simulations are carried out at three values of the lattice spacing ranging from ∼0.068 to ∼0.092 fm with linear lattice size up to L ∼ 5.5 fm. The scale is set by the particle data group (PDG) value of the pion decay constant, fISOQCD π = 130.4(2) MeV, at the ISOQCD pion point, MISOQCD π = 135.0(2) MeV, obtaining for the gradient-flow scales the values w0 = 0.17383(63) fm, .....t0 = 0.14436(61) fm and t0/w0 = 0.11969(62) fm. The data are analyzed within the framework of SU(2) chiral perturbation theory without resorting to the use of renormalized quark masses. At the ISOQCD kaon point MISOQCD K = 494.2(4) MeV we get (fK/fπ)ISOQCD = 1.1995(44), where the error includes both statistical and systematic uncertainties. Implications for the Cabibbo-Kobayashi-Maskawa matrix element jVusj and for the first-row Cabibbo-Kobayashi-Maskawa unitarity are discussed.

Physical review / D 104(7), 074515 (2021). doi:10.1103/PhysRevD.104.074515, We present a calculation of the up, down, strange, and charm quark masses performed within the lattice QCD framework. We use the twisted-mass fermion action and carry out simulations that include in the sea two light mass-degenerate quarks, as well as the strange and charm quarks. In the analysis, we use gauge ensembles simulated at three values of the lattice spacing and with light quarks that correspond to pion masses in the range from 350 MeV to the physical value, while the strange and charm quark masses are tuned approximately to their physical values. We use several quantities to set the scale in order to check for finite lattice spacing effects, and in the continuum limit, we get compatible results. The quark mass renormalization is carried out nonperturbatively using the (modified) Regularization Independent Momentum Subtraction (RI���-MOM) method converted into the $\overline{MS}$ scheme. For the determination of the quark masses, we use physical observables from both the meson and the baryon sectors, obtaining $m_{ud}$=3.636(66)($_{-57}^{+60}$) MeV and $m_s$=98.7(2.4)($_{-3.2}^{+4.0}$) MeV in the $\overline{MS}$(2 GeV) scheme and $m_c$=1036(17)($_{-8}^{+15}$) MeV in the $\overline{MS}$(3 GeV) scheme, where the first errors are statistical and the second ones are combinations of systematic errors. For the quark mass ratios, we get $m_s/m_{ud}$=27.17(32)($_{-38}^{+56}$) and $m_c/m_s$=11.48(12)($_{-19}^{+25}$)., Published by Inst., Melville, NY

We present a calculation of the up, down, strange and charm quark masses performed within the lattice QCD framework. We use the twisted mass fermion action and carry out simulations that include in the sea two light mass-degenerate quarks, as well as the strange and charm quarks. In the analysis we use gauge ensembles simulated at three values of the lattice spacing and with light quarks that correspond to pion masses in the range from 350 MeV to the physical value, while the strange and charm quark masses are tuned approximately to their physical values. We use several quantities to set the scale in order to check for finite lattice spacing effects and in the continuum limit we get compatible results. The quark mass renormalization is carried out non-perturbatively using the RI'-MOM method converted into the $\overline{\rm MS}$ scheme. For the determination of the quark masses we use physical observables from both the meson and the baryon sectors, obtaining $m_{ud} = 3.636(66)(^{+60}_{-57})$~MeV and $m_s = 98.7(2.4)(^{+4.0}_{-3.2})$~MeV in the $\overline{\rm MS}(2\,{\rm GeV})$ scheme and $m_c = 1036(17)(^{+15}_{-8})$~MeV in the $\overline{\rm MS}(3\,{\rm GeV})$ scheme, where the first errors are statistical and the second ones are combinations of systematic errors. For the quark mass ratios we get $m_s / m_{ud} = 27.17(32)(^{+56}_{-38})$ and $m_c / m_s = 11.48(12)(^{+25}_{-19})$., 37 pages, 23 figures, 24 tables. One reference added