1,232 research outputs found
Static quark-antiquark pair free energy and screening masses: continuum results at the QCD physical point
We study the correlators of Polyakov loops, and the corresponding gauge
invariant free energy of a static quark-antiquark pair in 2+1 flavor QCD at
finite temperature. Our simulations were carried out on = 6, 8, 10, 12,
16 lattices using a Symanzik improved gauge action and a stout improved
staggered action with physical quark masses. The free energies calculated from
the Polyakov loop correlators are extrapolated to the continuum limit. For the
free energies we use a two step renormalization procedure that only uses data
at finite temperature. We also measure correlators with definite Euclidean time
reversal and charge conjugation symmetry to extract two different screening
masses, one in the magnetic, and one in the electric sector, to distinguish two
different correlation lengths in the full Polyakov loop correlator. This
conference contribution is based on the paper: JHEP 1504 (2015) 138Comment: 7 pages, 4 figures. Talk presented at the 33rd International
Symposium on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe
International Conference Center, Kobe, Japa
Charmonium spectral functions from 2+1 flavour lattice QCD
Finite temperature charmonium spectral functions in the pseudoscalar and
vector channels are studied in lattice QCD with 2+1 flavours of dynamical
Wilson quarks, on fine isotropic lattices (with a lattice spacing of 0.057 fm),
with a non-physical pion mass of 545 MeV. The highest
temperature studied is approximately . Up to this temperature no
significant variation of the spectral function is seen in the pseudoscalar
channel. The vector channel shows some temperature dependence, which seems to
be consistent with a temperature dependent low frequency peak related to heavy
quark transport, plus a temperature independent term at \omega>0. These results
are in accord with previous calculations using the quenched approximation.Comment: 17 pages, 9 figures, 2 table
Equation of state of a hot-and-dense quark gluon plasma: lattice simulations at real vs. extrapolations
The equation of state of the quark gluon plasma is a key ingredient of heavy
ion phenomenology. In addition to the traditional Taylor method, several novel
approximation schemes have been proposed with the aim of calculating it at
finite baryon density. In order to gain a pragmatic understanding of the limits
of these schemes, we compare them to direct results at , using
reweighting techniques free from an overlap problem. We use 2stout improved
staggered fermions with 8 time-slices and cover the entire RHIC BES range in
the baryochemical potential, up to .Comment: 7 pages, 3 figure
Lattice simulations of the QCD chiral transition at real ÎŒB
Most lattice studies of hot and dense QCD matter rely on extrapolation from
zero or imaginary chemical potentials. The ill-posedness of numerical analytic
continuation puts severe limitations on the reliability of such methods. We
studied the QCD chiral transition at finite real baryon density with the more
direct sign reweighting approach. We simulate up to a baryochemical
potential-temperature ratio of , covering the RHIC Beam Energy
Scan range, and penetrating the region where methods based on analytic
continuation are unpredictive.This opens up a new window to study QCD matter at
finite from first principles.Comment: 10 pages, 3 figures; Contribution to the XXXIII International
(ONLINE) Workshop on High Energy Physics "Hard Problems of Hadron Physics:
Non-Perturbative QCD & Related Quests"; Based on 2108.09213 [hep-lat]. arXiv
admin note: substantial text overlap with arXiv:2112.0213
Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV
A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe
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