Thu·Nov 15, 2007Thursday·November 15, 2007

1. 01*

   Euclidean lattice simulation for the dynamical supersymmetry breaking

   Issaku Kanamori🇯🇵 · Fumihiko Sugino🇯🇵 · Hiroshi Suzuki🇯🇵

   The global supersymmetry is spontaneously broken if and only if the ground-state energy is strictly positive. We propose to use this fact to observe the spontaneous supersymmetry breaking in euclidean lattice simulations. For lattice formulations that possess a manifest fermionic symmetry, there exists a natural choice of a hamiltonian operator that is consistent with a topological property of the Witten index. We confirm validity of our idea in models of the supersymmetric quantum mechanics. We then examine a possibility of a dynamical supersymmetry breaking in the two-dimensional $\mathcal{N}=(2,2)$ super Yang-Mills theory with the gauge group $\text{SU}(2)$, for which the Witten index is unknown. Differently from a recent conjectural claim, our numerical result tempts us to conclude that supersymmetry is not spontaneously broken in this system.

   hep-lathep-thPRD(2008)·51 citations
2. 02*

   Dirac b quark on the lattice

   TWQCD Collaboration: Ting-Wai Chiu🇹🇼 · Tung-Han Hsieh🇹🇼 · Chao-Hsi Huang🇹🇼 · Kenji Ogawa🇹🇼

   We perform the first study of treating b, c, and s quarks as Dirac fermions in lattice QCD with exact chiral symmetry. On a 32^3 60 lattice with 1/a ~ 7.68 GeV, we compute point-to-point quark propagators, and measure the time-correlation functions for mesons with quark contents b_bbar, c_bbar, s_bbar, and c_cbar. The lowest-lying meson mass spectra, the pseudoscalar decay constants, and the b and c quark masses are determined.

   hep-lathep-exhep-phPoS(2007)·1 citation
3. 03*

   Observing dynamical supersymmetry breaking with euclidean lattice simulations

   Issaku Kanamori🇯🇵 · Fumihiko Sugino🇯🇵 · Hiroshi Suzuki🇯🇵

   A strict positivity of the ground-state energy is a necessary and sufficient condition for spontaneous supersymmetry breaking. This ground-state energy may be directly determined from the expectation value of the Hamiltonian in the functional integral, defined with an \emph{antiperiodic} temporal boundary condition for all fermionic variables. We propose to use this fact to observe the dynamical spontaneous supersymmetry breaking in Euclidean lattice simulations. If a lattice formulation possesses a manifestly preserved fermionic symmetry, there exists a natural choice of a Hamiltonian operator that is consistent with a topological nature of the Witten index. We numerically confirm the validity of our idea in models of supersymmetric quantum mechanics. We further examine the possibility of dynamical supersymmetry breaking in the two-dimensional $\mathcal{N}=(2,2)$ super Yang-Mills theory with the gauge group SU(2), for which the Witten index is unknown. Although statistical errors are still large, we do not observe positive ground-state energy, at least within one standard deviation. This prompts us to draw a different conclusion from a recent conjectural claim that supersymmetry is dynamically broken in this system.

   hep-lathep-thProg.Theor.Phys.(2008)·63 citations
4. 04*

   Hadron interactions from lattice QCD

   Sinya Aoki🇯🇵

   Studies on hadron interactions from lattice QCD are reviewed. The $S$-wave $\pi \pi$ scattering lengths of the I=0 and I=2 channels are extracted from various lattice determinations of low energy constants in $N_f=2$ chiral perturbation theory. The results agree with each other and agree also with other non-lattice estimates. Recently the $P$-wave $\pi \pi$ scattering phase shift for the I=1 channel has been calculated. A preliminary estimate of the $\rho$ meson decay width from the phase shift is consistent with the experimental value. Two approaches to potentials between hadrons are discussed. One is a method using static quarks to define the distance between two hadrons. The other is a method to define a potential from a wave function of two hadrons. An application of the latter to the nucleon-nucleon ($NN$) potential turns out to reproduce qualitative features of the phenomenological $NN$ potential such as attraction at long distance and repulsion at short distance. Theoretical issues of this approach are also discussed.

   hep-latnucl-thPoS(2007)·16 citations
5. 05*

   Distribution Amplitudes of Vector Mesons

   V.M. Braun🇩🇪 · D. Brömmel🇩🇪 · M. Göckeler🇩🇪 · R. Horsley🇬🇧 · Y. Nakamura🇩🇪 · H. Perlt🇩🇪 · D. Pleiter🇩🇪 · P.E.L. Rakow🇬🇧 · A. Schäfer🇩🇪 · G. Schierholz🇩🇪 · A. Schiller🇩🇪 · W. Schroers🇩🇪 and 3 other authors

   Results are presented for the lowest moment of the distribution amplitude for the K-star vector meson. Both longitudinal and transverse moments are investigated. We use two flavours of O(a) improved Wilson fermions, together with a non-perturbative renormalisation of the matrix element.

   hep-latPoS(2007)·12 citations
6. 06*

   Renormalized Polyakov loops in many representations

   Sourendu Gupta🇮🇳 · Kay Hubner🇺🇸 · Olaf Kaczmarek🇩🇪

   We present a renormalization procedure for Polyakov loops which explicitly implements the fact that the renormalization constant depends only on the ultraviolet cutoff. Using this we study the renormalized Polyakov loops in all representations upto the {\bf 27} of the gauge group SU(3). We find good evidence for Casimir scaling of the Polyakov loops and for approximate large-N factorization. By studying many loops together, we are able to show that there is a matrix model with a single coupling which can describe the high temperature phase of QCD, although it is hard to construct explicitly. We present the first results for the non-vanishing renormalized octet loop in the thermodynamic limit below the SU(3) phase transition, and estimate the associated string breaking distance and the gluelump binding energy. By studying the connection of the direct renormalization procedure with a generalization of an earlier suggestion which goes by the name of the $Q\bar{Q}$ renormalization procedure, we find that they are functionally equivalent.

   hep-lathep-phPRD(2008)·159 citations
7. 07*

   Nucleon Structure from Lattice QCD

   David Richards🇺🇸

   Recent advances in lattice field theory, in computer technology and in chiral perturbation theory have enabled lattice QCD to emerge as a powerful quantitative tool in understanding hadron structure. I describe recent progress in the computation of the nucleon form factors and moments of parton distribution functions, before proceeding to describe lattice studies of the Generalized Parton Distributions (GPDs). In particular, I show how lattice studies of GPDs contribute to building a three-dimensional picture of the proton. I conclude by describing the prospects for studying the structure of resonances from lattice QCD.

   ↳ nucl-thhep-lat7 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.