Photon emission from weakly magnetized neutral pions

Abstract

Using a hadronic framework, we derive an explicit expression for photon production from neutral pions in a weak background magnetic field. Our calculation is built on the proton triangle diagram with an effective Yukawa ${\pi }^0$-proton coupling, offering an alternative to quark-level descriptions that is advantageous when the magnetic length greatly exceeds the proton size. Corrections to the pion decay constant are computed up to second order in the magnetic-field strength, revealing that the field generally suppresses the decay rate. Quantitatively, however, the effect remains modest even for fields as strong as $|eB|\simeq m_{\pi }^2$. The differential photon emission rate exhibits anisotropy, with the strongest suppression occurring when the pion momentum is perpendicular to the magnetic field. Overall, the modification of the ${\pi }^0\to \gamma \gamma$ rate is parametrically small, scaling as $|eB{|}^2/m_P^4$, where $m_P$ is the proton mass. While the magnetic-field-induced anisotropy is conceptually interesting in principle, it is likely too small to be resolved in present heavy-ion measurements.

21 pages, 3 figures; v2: final version accepted for publication in Physical Review D, with several expanded discussions

References in corpus (30)

• Estimate of the magnetic field strength in heavy-ion collisions
• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Event-by-event generation of electromagnetic fields in heavy-ion collisions
• Quantum field theory in a magnetic field: From quantum chromodynamics to graphene and Dirac semimetals
• Electromagnetic field evolution in relativistic heavy-ion collisions
• Discovery of Very-High-Energy Gamma-Rays from the Galactic Centre Ridge
• Enhanced production of direct photons in Au+Au collisions at sqrt(s_NN)=200 GeV and implications for the initial temperature
• The production of photons in relativistic heavy-ion collisions
• Direct photon production in Pb-Pb collisions at $\sqrt{s_\rm{NN}}$ = 2.76 TeV
• Quark condensate in a magnetic field
• Azimuthally fluctuating magnetic field and its impacts on observables in heavy-ion collisions
• Chiral perturbation theory in a magnetic background - finite-temperature effects
• Multi-messenger heavy-ion collision physics
• Thermal pions in a magnetic background
• Chiral Magnetic Effects in Nuclear Collisions
• Gell-Mann - Oakes - Renner relation in a magnetic field at finite temperature
• Ellipticity of photon emission from strongly magnetized hot QCD plasma
• Spin Hydrodynamic Generation in the Charged Subatomic Swirl
• Pion decay constants in a strong magnetic field
• Production of ${\pi }^0$ and $\eta$ mesons up to high transverse momentum in pp collisions at 2.76 TeV
• Chiral Magnetic Effect in Heavy Ion Collisions: The Present and Future
• Rate and ellipticity of dilepton production in a magnetized quark-gluon plasma
• Thermal Electromagnetic Radiation in Heavy-Ion Collisions
• Anomalous low-temperature thermodynamics of QCD in strong magnetic fields
• Nonprompt direct-photon production in Au$+$Au collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV
• Chiral asymmetry in QED matter in a magnetic field
• Anomalous plasma: chiral magnetic effect and all that
• Circularly polarized photon emission from magnetized chiral plasmas
• Photon and dilepton emission anisotropy for a magnetized quark-gluon plasma
• ${\pi }^0\to 2\gamma$ decay under strong magnetic fields in the NJL model