15136419
Going chiral: Overlap versus twisted mass fermions
We compare the behavior of overlap fermions, which are chirally invariant, and of Wilson twisted mass fermions at full twist in the approach to the chiral limit. Our quenched simulations reveal that with both formulations of lattice fermions pion masses of (250 MeV) can be reached in practical applications. Our comparison is done at a fixed value of the lattice spacing a 0.123 fm. A number of quantities are measured such as hadron masses, pseudoscalar decay constants and quark masses obtained from Ward identities. We also determine the axial vector renormalization constants in the case of overlap fermions.
26599771
Sea quark effects on quarkonia
We study the effects of two dynamical sea quarks on the spectrum of heavy quarkonia. Within the non-relativistic approach to Lattice QCD we found sizeable changes to the hyperfine splitting, but we could not observe any changes for the fine structure. We also investigated the scaling behaviour of our results for several different lattice spacings.
73624755
Many flavor QCD as exploration of the walking behavior with the approximate IR fixed point
Computing Research Center, High Energy Accelerator Research Organization (KEK), Tsukuba,305-0801, JapanWe present the ﬁrst report of the LatKMI collaboration on the the lattice QCD simulation per-formed at the KMI computer, “ϕ”, for the cases of 4 ﬂavors and 8 ﬂavors, the latter being ex-pected to be a candidate for the walking technicolor having an approximate scale invariance nearthe infrared ﬁxed point. The simulation was carried out base d on the highly improved staggeredquark (HISQ) action. In this proceedings,we report preliminaryresults on the spectrum, analyzedthrough the chiral perturbation theory and the ﬁnite-size hyperscaling. We observe qualitativelydifferent behavior of the 8-ﬂavor case in contrast to the 4-ﬂavor case which shows clear indicationof the hadronic phase as in the usual QCD.The XXIX International Symposium on Lattice Field Theory - Lattice 2011July 10-16, 2011Squaw Valley, Lake Tahoe, California
125708608
Walking signals in $N_f=8$ QCD on the lattice
5379081
Scaling test of fermion actions in the Schwinger model
Abstract We discuss the scaling behaviour of different fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We have chosen Wilson, hypercube, twisted mass and overlap fermion actions. As physical observables, the pion mass and the scalar condensate are computed for the above mentioned actions at a number of coupling values and fermion masses. We also discuss possibilities to simulate overlap fermions dynamically avoiding problems with low-lying eigenvalues of the overlap kernel.
59353007
Investigation of the phase structure of a chirally-invariant Higgs-Yukawa model
a CERN, Physics Department, 1211 Geneva 23, Switzerland b Institut fur Physik, Humboldt-Universitat zu Berlin, D-12489 Berlin, Germany c NIC, DESY, Platanenallee 6, Zeuthen D-15738, Germany d Department of Physics, National Taiwan University, Roosevelt Road, Taipei 10617, Taiwan e Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan f Kobayashi-Maskawa Institute, Nagoya University, Nagoya, Aichi 464-8602, Japan g Department of Physics, Chung-Yuan Christian University, Chung-Li 32023, Taiwan h Division of Physics, National Centre for Theoretical Sciences, Hsinchu 300, Taiwan
14502654
Beam test of novel n-in-p strip sensors for high radiation environment
Abstract Highly radiation tolerant n-in-p strip sensors have been developed for the high-luminosity LHC (HL-LHC). This paper reports the results of measurements with 392 MeV kinetic energy proton beam at RCNP in December 2011. The data was taken with a new DAQ system consisting of an universal read-out board ‘SEABAS’ and beam tracking telescopes whose spacial resolution is better than 5 μ m . The aim of this beam test is to evaluate the new 1 cm×1 cm n-in-p miniature sensors before and after 10 15  n eq  cm −2 irradiation. The median charge of un-irradiated sensor is 6.2 fC at full depletion voltage, while the median charge after 10 15  n eq  cm −2 irradiation of the sensor is 4.2 fC. The novel Punch-Through-Protection (PTP) has been implemented in these sensors. The length of active region of the sensor around PTP is observed to be decreased by 12 μ m in the irradiated sensors at 10 15  n eq  cm −2 .