Quenched QCD

Indian Lattice Gauge Theory Initiative,
Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005, India


Lattice 2017 will be held in Granada, Spain on 19--24 June, 2017. A complete list of meetings held in TIFR is available.

Gauge configurations

Some gauge configurations are available for use on request (see a list). Please request gauge configurations from ilgti at theory fullstop tifr dot res period in.

The Temperature Scale

Using the scaling formula and the existing data on plaquettes, the relation between T and β plotted here is obtained. The error bars on the Nt=8 data come from measurement errors in the plaquette values. As can be seen, the difference between the data for Nt=4 and Nt=8 is not significant if one takes measurement errors into account.

Additional unpublished material

Compilation of critical couplings

Nt Vs bc shift Vs Ps Pt Ref.
31235.55(1)   [4]
4835.6875(?) 0.54932(8)0.5500(1)[1]
41235.6875(?) 0.5482(2)0.5486(2)[1]
41635.6908(2)   [5]
4Infinite5.69247(23)-0.053(26)Nt3  [2]
4Infinite5.6925(2)(as above)  [5]
63235.8938(11)   [5]
6Infinite5.89405(51)-0.072(77)Nt3  [2]
6Infinite5.8941(5)(as above)  [5]
81636.001(25)   [3]
83236.0609(9)   [5]
8Infinite6.0625(?)(as in Nt=6)  [5]
101636.160(7)   [3]
121636.268(12)   [4]
123236.3331(13)   [5]
12Infinite6.3384(?)(as in Nt=6)  [5]
141636.383(10)   [4]
162436.45(5)   [4]

Citation list for the compilation

  1. M. Fukugita et al, Nucl. Phys. B 337 (1990) 181. (Nt=4)
  2. Y. Iwasaki et al, Phys. Rev. Lett. 67 (1991) 3343. (Nt=4,6)
  3. N.H. Christ and H.-Q. Ding, Phys. Rev. Lett. 60 (1988) 1367. (Nt=6,8,10)
  4. Quoted in J. Fingberg et al, Nucl. Phys. B 392 (1993) 493.
  5. G. Boyd et al, Nucl. Phys. B 469 (1996) 419. (Nt=4,6,8,12)

Screening in the plasma

We measured the screening masses for two kinds of operators made of gluon fields. The one called the A1++ is made of two gluons or more. The one called the A2-- is made of three gluons or more. If there are (almost) free gluons in the plasma, then the ratio of the screening masses should be (close to) 3/2. The picture shows that the ratio nears this value for T>1.25Tc, but closer to the QCD phase transition there are strong devations from this picture. The degrees of freedom near the transition are not gluons.

The Wroblewski parameter

The Wroblewski parameter, λs, as inferred from experiments measures the relative yield of strange and light quarks. It has been measured on the lattice as the ratio of quark number susceptibilities for strange and light quarks. The continuum limit in quenched QCD has been found (brackets are estimates of unquenching errors) and it agrees well with data.