119237953
Non-perturbative renormalization of overlap quark bilinears on domain wall fermion configurations
We present renormalization constants of overlap quark bilinear operators on 2+1-flavor domain wall fermion configurations. Both overlap and domain wall fermions have chiral symmetry on the lattice. The scale independent renormalization constant for the local axial vector current is computed using a Ward Identity. The renormalization constants for the scalar, pseudoscalar and vector current are calculated in the RI-MOM scheme. Results in the MS scheme are obtained by using perturbative conversion ratios. The analysis uses in total six ensembles with lattice sizes 243×64 and 323×64.
118596020
Light baryon masses with dynamical twisted mass fermions
We present results on the mass of the nucleon and the $\ensuremath{\Delta}$ using two dynamical degenerate twisted mass quarks and the tree-level Symanzik improved gauge action. The evaluation is performed at four quark masses corresponding to a pion mass in the range of about 300\char21{}600 MeV on lattices of 2.1\char21{}2.7 fm at three lattice spacings less than 0.1 fm. We check for cutoff effects by evaluating these baryon masses on lattices of spatial size 2.1 fm at $\ensuremath{\beta}=3.9$ and $\ensuremath{\beta}=4.05$ and on a lattice of 2.4 fm at $\ensuremath{\beta}=3.8$. The values we find are compatible within our statistical errors. Lattice results are extrapolated to the physical limit using continuum chiral perturbation theory. Performing a combined fit to our lattice data at $\ensuremath{\beta}=3.9$ and $\ensuremath{\beta}=4.05$ we find a nucleon mass of $963\ifmmode\pm\else\textpm\fi{}12(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}8(\mathrm{syst})\text{ }\text{ }\mathrm{MeV}$ where we used the lattice spacings determined from the pion decay constant to convert to physical units. The systematic error due to the chiral extrapolation is estimated by comparing results obtained at $\mathcal{O}({p}^{3})$ and $\mathcal{O}({p}^{4})$ heavy baryon chiral perturbation theory. The nucleon mass at the physical point provides an independent determination of the lattice spacing. Using heavy baryon chiral perturbation theory at $\mathcal{O}({p}^{3})$ we find ${a}_{\ensuremath{\beta}=3.9}=0.0889\ifmmode\pm\else\textpm\fi{}0.0012(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0014(\mathrm{syst})\text{ }\text{ }\mathrm{fm}$, and ${a}_{\ensuremath{\beta}=4.05}=0.0691\ifmmode\pm\else\textpm\fi{}0.0010(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0010(\mathrm{syst})\text{ }\text{ }\mathrm{fm}$, in good agreement with the values determined from the pion decay constant. Using results from our two smaller lattices spacings at constant ${r}_{0}{m}_{\ensuremath{\pi}}$ we estimate the continuum limit and check consistency with results from the coarser lattice. Results at the continuum limit are chirally extrapolated to the physical point. Isospin violating lattice artifacts in the $\ensuremath{\Delta}$-system are found to be compatible with zero for the values of the lattice spacings used in this work. Performing a combined fit to our lattice data at $\ensuremath{\beta}=3.9$ and $\ensuremath{\beta}=4.05$ we find for the masses of the ${\ensuremath{\Delta}}^{++,\ensuremath{-}}$ and ${\ensuremath{\Delta}}^{+,0}$ $1315\ifmmode\pm\else\textpm\fi{}24(\mathrm{stat})\text{ }\text{ }\mathrm{MeV}$ and $1329\ifmmode\pm\else\textpm\fi{}30(\mathrm{stat})\text{ }\text{ }\mathrm{MeV}$, respectively. We confirm that in the continuum limit they are also degenerate.
118355581
Diquark effects in light baryon correlators from lattice QCD
We study the role of diquarks in light baryons through point-to-point baryon correlators. We contrast results from quenched simulations with ones with two flavors of dynamical overlap fermions. The scalar, pseudoscalar, and axial vector diquarks are combined with light quarks to form color singlets. The quenched simulation shows large zero-mode effects in correlators containing the scalar and pseudoscalar diquark. The two scalar diquarks created by {gamma}{sub 5} and {gamma}{sub 0}{gamma}{sub 5} lead to different behavior in baryon correlators, showing that the interaction of diquarks with the third light quark matters: we do not see an isolated diquark. In our quark mass range, the scalar diquark created by {gamma}{sub 5} seems to play a greater role than the others.
17813649
Baryon correlators containing different diquarks from lattice simulations
Point to point vacuum correlators containing diquarks in the color anti-triplet representation are computed both in the quenched approximation and dynamical overlap simulations with two flavors. The scalar, pseudoscalar and axial vector diquarks are combined with light quarks to form color singlets. The scalar (“good") diquark channel shows a stronger attraction than the axial vector (“bad") channel in the quenched data set. The pseudoscalar diquark channel shows a finite volume zero mode artifact: the correlator becomes negative at large distance when the quark mass is small. By separating configurations without zero modes from those with zero modes, we found that the zero modes have an important contribution in both the attraction in the scalar channel and the repulsion in the pseudoscalar channel. In the axial vector diquark channel, we did not find apparent zero mode effects.
118437820
Meson Mass Decomposition
Center for High Energy Physics, Peking University, Beijing 100871, ChinaHadron masses can be decomposed as a sum of components which are deﬁned through hadronicmatrix elements of QCD operators. The components consist of the quark mass term, the quarkenergy term, the glue energy term and the trace anomaly term. We calculate these components ofmesons with lattice QCD for the ﬁrst time. The calculation is carried out with overlap fermionon 2+1 ﬂavor domain-wall fermion gauge conﬁgurations. We conﬁrm that ˘50% of the lightpion mass comes from the quark mass and ˘10% comes from the quark energy, whereas, thecontributions are found to be the other way around for the r mass. The combined glue compo-nents contribute ˘40 50% for both mesons. It is interesting to observe that the quark masscontribution to the mass of the vector meson is almost linear in quark mass over a large quarkmass region below the charm quark mass. For heavy mesons, the quark mass term dominates themasses, while the contribution from the glue components is about 400 ˘500 MeV for the heavypseudoscalar and vector mesons. The charmonium hyperﬁne splitting is found to be dominatedby the quark energy term which is consistent with the quark potential model.32st International Symposium on Lattice Field Theory - LATTICE 2014June 22 - June 29, 2014Columbia UniversityNew York, USA
118450238
Oscillatory behavior of the domain wall fermions revisited
In the generic domain wall fermion formulation of chiral fermions on the lattice, the zero modes of the four-dimensional Wilson fermion operator with the negative mass parameter -M-5 introduce unphysical massive modes propagating in the four-dimensional spacetime. In the free fermion case, the pole mass of this kind of unphysical modes is given by (E) over bar = ln(1-M-5), which acquires an imaginary part, i pi, when M-5 > 1 and results in an oscillatory behavior of the domain wall fermion propagator in time. The existence of the unphysical modes in the presence of gauge fields is investigated in the mean field approximation, and their physical consequences are discussed. In addition, we also give a semiquantitative criterion for tuning M-5 in the realistic numerical study.
54185957
Colored resonant signals at the LHC: largest rate and simplest topology
We study the colored resonance production at the LHC in a most general approach. We classify the possible colored resonances based on group theory decomposition, and construct their effective interactions with light partons. The production cross section from annihilation of valence quarks or gluons may be on the order of 400–1000 pb at LHC energies for a mass of 1 TeV with nominal couplings, leading to the largest production rates for new physics at the TeV scale, and simplest event topology with dijet final states. We apply the new dijet data from the LHC experiments to put bounds on various possible colored resonant states. The current bounds range from 0.9 to 2.7 TeV. The formulation is readily applicable for future searches including other decay modes.
121457351
Boson-Fermion Duality in A2 Toda Field Theory
In this paper, we consider a two-dimensional integrable and conformal invariant field theory with two Dirac spinors and two scalar fields. This model has chiral symmetry and CP-like symmetry. Moreover, this model also has a Neother current depending only on the matter field. At last, we bosonize the spinor fields.
118506962
Chiral perturbation theory and the $\bar B \bar B$ strong interaction
We have calculated the potentials of the heavy (charmed or bottomed) pseudoscalar mesons up to $O(\epsilon^2)$ with the heavy meson chiral perturbation theory. We take into account the contributions from the football, triangle, box, and crossed diagrams with the 2$\phi$ exchange and one-loop corrections to the contact terms. We notice that the total 2$\phi$-exchange potential alone is attractive in the small momentum region in the channel ${\bar B \bar B}^{I=1}$, ${\bar B_s \bar B_s}^{I=0}$, or ${\bar B \bar B_s}^{I=1/2}$, while repulsive in the channel ${\bar B \bar B}^{I=0}$. Hopefully the analytical chiral structures of the potentials may be useful in the extrapolation of the heavy meson interaction from lattice QCD simulation.
67819117
Pseudoscalar Mesons Scattering off D*-mesons with Chiral Perturbation Theory
We have systematically calculated the s-wave pseudoscalar mesons and D*- mesons scattering lengths to the third order with chiral perturbation theory, which will be helpful to reveal their strong interaction. We present the scattering lengths (1) in the framework of the heavy meson chiral perturbation theory and (2) in the framework of the infrared regularization.
124427740
ALICE Technical Design Report on Forward Detectors : FMD, T0 and V0