118422616
Hadron properties from lattice QCD simulations with exact chiral symmetry
16381056
Lattice QCD calculation of form factors describing the rare decays $B \to K^* \ell^+ \ell^-$ and $B_s \to \phi \ell^+ \ell^-$
The rare decays $B^0 \to K^{*0} \mu^+ \mu^-$ and $B_s \to \phi \mu^+ \mu^-$ are now being observed with enough precision to test Standard Model predictions. A full understanding of these decays requires accurate determinations of the corresponding hadronic form factors. Here we present results of lattice QCD calculations of the $B \to K^*$ and $B_s \to \phi$ form factors; we also determine the form factors relevant for the tree-level decays $B_s \to K^* \ell \nu$. We use full-QCD configurations including 2+1 flavors of sea quarks using an improved staggered action, and we employ lattice non-relativistic QCD to describe the bottom quark.
118634793
Lattice study on $\eta_{c2}$ and X(3872)
Properties of 2(-+) charmonium eta(c2) are investigated in quenched lattice QCD. The mass of eta(c2) is determined to be 3.80(3) GeV, which is close to the mass of D-wave charmonium psi(3770) and in agreement with quark model predictions. The transition width of eta(c2) -> gamma J/psi is also obtained with a value of Gamma = 3.8(9) keV. Since the possible 2(-+) assignment to X(3872) has not been ruled out by experiments, our results help to clarify the nature of X(3872). DOI: 10.1103/PhysRevD.87.014501
18642908
Moments of meson distribution functions with dynamical twisted mass fermions
We present our preliminary results on the lowest moment hxi of quark distribution functions of the pion using two flavor dynamical simulations with Wilson twisted mass fermions at maximal twist. The calculation is done in a range of pion masses from 300 to 500 MeV. A stochastic source method is used to reduce inversions in calculating propagators. Finite volume effects at the lowest quark mass are examined by using two different lattice volumes. Our results show that we achieve statistical errors of only a few percent. We plan to compute renormalization constants non-perturbatively and extend the calculation to two more lattice spacings and to the nucleons.
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.
37916668
Renormalization of bilinear quark operators for overlap fermions
We present nonperturbative renormalization constants of fermionic bilinears on the lattice in the quenched approximation at {beta}=6.1 using an overlap [H. Neuberger, Phys. Lett. B 417, 141 (1998)] fermion action with hypercubic (HYP)-blocked links. We consider the effects of the exact zero modes of the Dirac operator and find they are important in calculating the renormalization constants of the scalar and pseudoscalar density. The results are given in the RI' and MS schemes and compared to perturbative calculations.
116857589
Inclusive $\pi^0$ and $K^0_{S}$ production in two photon collisions at LEP
The reactions e + e − →e + e − π 0 X and e + e − →e + e − K S 0 X are studied using data collected at LEP with the L3 detector at centre-of-mass energies between 189 and 202 GeV. Inclusive differential cross sections are measured as a function of the particle transverse momentum p t and the pseudo-rapidity. For p t ⩽1.5 GeV, the π 0 and K S 0 differential cross sections are described by an exponential, typical of soft hadronic processes. For p t ⩾1.5 GeV, the cross sections show the presence of perturbative QCD processes, described by a power-law. The data are compared to Monte Carlo predictions and to NLO QCD calculations.
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.
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.
59333781
The Case for a Muon Collider Higgs Factory
Author(s): Alexahin, Y; Ankenbrandt, CM; Cline, DB; Conway, A; Cummings, MA; Benedetto, VD; Eichten, E; Delahaye, J-P; Gatto, C; Grinstein, B; Gunion, J; Han, T; Hanson, G; Hill, CT; Ignatov, F; Johnson, RP; Lebedev, V; Lederman, LM; Lipton, R; Liu, Z; Markiewicz, T; Mazzacane, A; Mokhov, N; Nagaitsev, S; Neuffer, D; Palmer, M; Purohit, MV; Raja, R; Rubbia, C; Striganov, S; Summers, D; Terentiev, N; Wenzel, H | Abstract: We propose the construction of a compact Muon Collider Higgs Factory. Such a machine can produce up to \sim 14,000 at 8\times 10^{31} cm^-2 sec^-1 clean Higgs events per year, enabling the most precise possible measurement of the mass, width and Higgs-Yukawa coupling constants.
119107633
Neutrino dark matter candidate in fourth generation scenarios
Abstract We overview the constraints on the 4th-generation neutrino dark matter candidate and investigate a possible way to make it a viable dark matter candidate. Given the LEP constraints tell us that the 4th-generation neutrino has to be rather heavy ( > M Z / 2 ) , in sharp contrast to the other three neutrinos, the underlying nature of the 4th-generation neutrino is expected to be different. We suggest that an additional gauge symmetry B − 4 L 4 distinguishes it from the standard modelʼs three lighter neutrinos and this also facilitates promotion of the 4th-generation predominantly right-handed neutrino to a good cold dark matter candidate. It provides distinguishable predictions for the dark matter direct detection and the Large Hadron Collider experiments.