75 research outputs found
Heavy light tetraquarks from Lattice QCD
We present preliminary results from a lattice calculation of tetraquark
states in the charm and bottom sector of the type ,
, and . These
calculations are performed on MILC ensembles with lattice
spacing of and . A relativistic
action with overlap fermions is employed for the light and charm quarks while a
non-relativistic action with non-perturbatively improved coefficients is used
in the bottom sector. Preliminary results provide a clear indication of
presence of energy levels below the relevant thresholds of different tetraquark
states. While in double charm sector we find shallow bound levels, our results
suggest deeply bound levels with double bottom tetraquarks.Comment: Corrected threshold for the tetraquark state.
Proceedings of the 35th International Symposium on Lattice Field Theory,
18-24 June 2017, Granada, Spain. TIFR preprint no : TIFR/TH/17-3
Spectroscopy of Charmed and Bottom Hadrons using Lattice QCD
We present preliminary results on the light, charmed and bottom baryon
spectra using overlap valence quarks on the background of 2+1+1 flavours HISQ
gauge configurations of the MILC collaboration. These calculations are
performed on three different gauge ensembles at three lattice spacings (a ~
0.12 fm, 0.09 fm and 0.06 fm) and for physical strange, charm and bottom quark
masses. The SU(2) heavy baryon chiral perturbation theory is used to
extrapolate baryon masses to the physical pion mass and the continuum limit
extrapolations are also performed. Our results are consistent with the well
measured charmed baryons. We predict the masses of many other states which are
yet to be discovered.Comment: 8 pages, Proceedings of the 35th International Symposium on Lattice
Field Theory (Lattice 2017
scattering in the Roper channel
We present results from our recent lattice QCD study of scattering in
the positive-parity nucleon channel, where the puzzling Roper resonance
resides in experiment. Using a variety of hadron operators, that
include -like, in -wave and in -wave, we
systematically extract the excited lattice spectrum in the nucleon channel up
to 1.65 GeV. Our lattice results indicate that N scattering in the elastic
approximation alone does not describe a low-lying Roper. Coupled channel
effects between and seem to be crucial to render a low-lying
Roper in experiment, reinforcing the notion that this state could be a
dynamically generated resonance. After giving a brief motivation for studying
the Roper channel and the relevant technical details to this study, we will
discuss the results and the conclusions based on our lattice investigation and
in comparison with other lattice calculations.Comment: 8 pages, 5 figures, presented at the 35th International Symposium on
Lattice Field Theory, 18-24 June 2017, Granada, Spai
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