# The Modern Physics of Compact Stars and Relativistic Gravity 2017

18-22 September 2017
Yerevan, Armenia
Etc/GMT+4 timezone

## Modification of Compact Star Observables due to Quantum Fluctuations

20 Sep 2017, 11:20
40m
Yerevan, Armenia

#### Yerevan, Armenia

Department of Physics, Alex Manoogian str. 1, Yerevan, Armenia

### Speaker

Dr Gergely Gabor Barnafoldi (Wigner RCP Hungarian Academy of Sciences (HU))

### Description

We present the application of our technique to obtain equation of state (EoS) by the Functional Renormalization Group (FRG) method presented earlier. Using the expansion of the effective potential in a base of harmonic functions at finite chemical potential we can provide a general framework for the calculation of the EoS. Within this theoretical framework we determined the equation of state and the phase diagram of a simple model -- as a proof-of-concept. To illustrate this we used the simplest, non-trivial case, where massless fermions coupled to scalars through Yukawa-coupling at the zero-temperature limit.

We compared our results to the 1-loop and the mean field approximation of the same model and other high-density nuclear matter equation of states. We found a $10-20\%$ difference between these approximations. As an application, we used our FRG-based equation of states to test the effect of the quantum fluctuations in superdense nuclear matter of a compact astrophysical object. To illustrate the magnitude of this effect, we calculated the mass-radius relation for a compact star using the Tolmann-Oppenheimer-Volkov equation and observed a 5% effect in compact star observables due to quantum fluctuations.

Type of contribution Talk

### Primary authors

Dr Gergely Gabor Barnafoldi (Wigner RCP Hungarian Academy of Sciences (HU)) Péter Pósfay (Wigner Research Centre for Physics) Antal Jakovac (Eotvos University Budapest)