Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Barnett effect as a new source of magnetic field in heavy-ion collisions

Dushmanta Sahu

TL;DR

The paper addresses whether rotation-induced Barnett magnetization can contribute a significant magnetic field in QCD matter created in non-central heavy-ion collisions, particularly at low $sqrt{s_{ ext{NN}}}$ where $B_{ ext{ext}}$ is weak. It uses the rotating Hadron Resonance Gas (HRG) model to compute the Barnett magnetization $M_{ m Barnett}$ and the induced field $B_{ ext{ind}}$, deriving the effective field $B_{ ext{eff}} = rac{omega}{g mu_N}$ and the relation $B_{ ext{ind}} = mu_0 M$ (with $mu_0=1$ in natural units). Findings show $M_{ m Barnett}$ grows with $T$, $mu_B$, and $omega$, and the proton-induced $B_{ ext{ind}}$ can be comparable to or exceed $B_{ ext{ext}}$ at low $sqrt{s_{ ext{NN}}}$, with a predicted species-dependent polarization pattern $P_ mbda < P_{ar{ mbda}}$ matching observations. Implications include a potentially dominant role for the Barnett magnetization in spin dynamics and anomalous transport in rotating QCD matter, with broader relevance to other extreme rotators such as neutron stars.

Abstract

The Barnett effect is a fundamental magnetomechanical phenomenon in which a ferromagnetic material becomes magnetized under rotation. Using a hadron resonance gas (HRG) model under rigid rotation, we compute the Barnett magnetization ($M_{\rm Barnett}$) and show that it produces a magnetic field ($B_{\text{ind}}$) comparable in magnitude to the well-known external field ($B_{\text{ext}}$) from spectator protons at low energy heavy-ion collisions. This finding establishes the Barnett effect as a previously overlooked but essential source of magnetization and magnetic field in the heavy-ion collisions, with profound implications for understanding spin dynamics and anomalous transport in quantum chromodynamics under extreme rotation.

Barnett effect as a new source of magnetic field in heavy-ion collisions

TL;DR

The paper addresses whether rotation-induced Barnett magnetization can contribute a significant magnetic field in QCD matter created in non-central heavy-ion collisions, particularly at low where is weak. It uses the rotating Hadron Resonance Gas (HRG) model to compute the Barnett magnetization and the induced field , deriving the effective field and the relation (with in natural units). Findings show grows with , , and , and the proton-induced can be comparable to or exceed at low , with a predicted species-dependent polarization pattern matching observations. Implications include a potentially dominant role for the Barnett magnetization in spin dynamics and anomalous transport in rotating QCD matter, with broader relevance to other extreme rotators such as neutron stars.

Abstract

The Barnett effect is a fundamental magnetomechanical phenomenon in which a ferromagnetic material becomes magnetized under rotation. Using a hadron resonance gas (HRG) model under rigid rotation, we compute the Barnett magnetization () and show that it produces a magnetic field () comparable in magnitude to the well-known external field () from spectator protons at low energy heavy-ion collisions. This finding establishes the Barnett effect as a previously overlooked but essential source of magnetization and magnetic field in the heavy-ion collisions, with profound implications for understanding spin dynamics and anomalous transport in quantum chromodynamics under extreme rotation.

Paper Structure

This paper contains 6 sections, 20 equations, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Formulation
  3. Rotation to Effective Field: Barnett Magnetization
  4. Barnett Magnetization to Induced Magnetic Field
  5. Results and Discussion
  6. Summary

Figures (3)

  • Figure 1: Barnett magnetization as a function of temperature and baryochemical potential for $\omega$ = 0.01 GeV (left panel) and 0.05 GeV (right panel).
  • Figure 2: Barnett magnetization of proton and anti-proton as a function of center of mass energies for the $\omega$ values taken from Ref. STAR:2017ckg.
  • Figure 3: Barnett-induced magnetic field as a function of center of mass energies for the $\omega$ values taken from Ref. STAR:2017ckg, compared with the external magnetic field Panda:2024ccj.