ELFT HÍRADÓ

[Asbóth János Károly <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

Dec. 2. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Kapás Kornél (BME Elm. Fiz. Tanszék):
Numerical obstacles in Monte Carlo simulations: The overlap and sign problem

A major breakthrough in the study of the strong interaction at low energies 
was achieved in 1974, when the foundations of lattice formalism were laid. 
This led to a very efficient, systematically correct and, most importantly, 
non-perturbative method. With the help of appropriate mathematical tools, the 
original theory can be reduced to a finite dimensional, finite volume 
statistical physical system in which the desired observables can be computed 
via Monte Carlo simulations. The limitations are typically the numerical 
difficulties, for which the obvious antidote would be to infinitely increase 
the computation time. This means that the algorithms should in principle be 
able to produce the exact results, but with finite machine time, very severe 
obstacles can arise, e.g. the notorious overlap and sign problem [1-3]. In my 
presentation I give a detailed insight into these numerical difficulties and 
show how they can be alleviated.

[1] M. Giordano, K. Kapás, S. D. Katz, D. Nógrádi and A. Pásztor. “Effect of 
stout smearing on the phase diagram from multiparameter reweighting in 
lattice QCD”. Physical Review D 102.3 (2020).
[2] M. Giordano, K. Kapás, S. D. Katz, D. Nógrádi és A. Pásztor. “New 
approach to lattice QCD at finite density; results for the critical end point 
on coarse lattices”. JHEP 05 (2020)
[3] M. Giordano, K. Kapás, S. D. Katz, A. Pásztor és Z. Tulipánt. 
“Exponential reduction of the sign problem at finite density in the 2+1D XY 
model via contour deformations”. Phys. Rev. D 106 (2022)

Minden érdeklődőt szeretettel várunk.
Asbóth János,
 szemináriumi koordinátor