Research output: Contribution to journal › Article › peer-review
Millicharged fermion vacuum polarization in a cosmic magnetic field and generation of CMB elliptic polarization. / Ejlli, Damian.
In: Physical Review D, Vol. 96, No. 2, 023540, 31.07.2017.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Millicharged fermion vacuum polarization in a cosmic magnetic field and generation of CMB elliptic polarization
AU - Ejlli, Damian
PY - 2017/7/31
Y1 - 2017/7/31
N2 - The contribution of one-loop millicharged fermion vacuum polarization in a cosmic magnetic field to the cosmic microwave background (CMB) polarization is considered. Exact and perturbative solutions of the density matrix equations of motion in terms of the Stokes parameters are presented. For linearly polarized CMB at the decoupling time, it is shown that the propagation of CMB photons in a cosmic magnetic field would generate elliptic polarization (circular and linear) of the CMB due to millicharged fermion vacuum polarization. Analytic expressions for the degree of circular polarization and rotation angle of the polarization plane of the CMB are presented. Depending on the ratio of millicharged fermion relative charge to mass, ϵ/mϵ, magnetic field amplitude, and CMB observation frequency, it is shown that the acquired CMB degree of circular polarization could be of the order of magnitude PC(T0)∼10-10-10-6 in the best scenario for a canonical value of magnetic field amplitude of the order of ∼nG and ϵ/mϵ∼10-4-few×10-3. The mechanism considered in this work generates CMB polarization even in the case when the CMB is initially in thermal equilibrium. Limits on the magnetic field amplitude due to prior-decoupling CMB polarization are presented.
AB - The contribution of one-loop millicharged fermion vacuum polarization in a cosmic magnetic field to the cosmic microwave background (CMB) polarization is considered. Exact and perturbative solutions of the density matrix equations of motion in terms of the Stokes parameters are presented. For linearly polarized CMB at the decoupling time, it is shown that the propagation of CMB photons in a cosmic magnetic field would generate elliptic polarization (circular and linear) of the CMB due to millicharged fermion vacuum polarization. Analytic expressions for the degree of circular polarization and rotation angle of the polarization plane of the CMB are presented. Depending on the ratio of millicharged fermion relative charge to mass, ϵ/mϵ, magnetic field amplitude, and CMB observation frequency, it is shown that the acquired CMB degree of circular polarization could be of the order of magnitude PC(T0)∼10-10-10-6 in the best scenario for a canonical value of magnetic field amplitude of the order of ∼nG and ϵ/mϵ∼10-4-few×10-3. The mechanism considered in this work generates CMB polarization even in the case when the CMB is initially in thermal equilibrium. Limits on the magnetic field amplitude due to prior-decoupling CMB polarization are presented.
KW - ELECTRIC-CHARGE QUANTIZATION
KW - PARITY-VIOLATION
KW - PARTICLES
KW - PROPAGATION
KW - HYDROGEN
KW - UNIVERSE
UR - http://www.scopus.com/inward/record.url?scp=85026996484&partnerID=8YFLogxK
U2 - 10.1103/PhysRevD.96.023540
DO - 10.1103/PhysRevD.96.023540
M3 - Article
AN - SCOPUS:85026996484
VL - 96
JO - Physical Review D
JF - Physical Review D
SN - 2470-0010
IS - 2
M1 - 023540
ER -
ID: 9966264