Seeking massless dark photons in the decays of charmed hadrons

Abstract

A massless dark photon could affect standard-model particles only via higher-dimensional operators and would therefore have eluded recent searches for its massive counterpart, which were based on the assumption that the latter had renormalizable interactions with known fermions due to gauge kinetic mixing. In this study we entertain the possibility that the massless dark photon has nonnegligible flavor-changing dipole-type couplings with the $u$ and $c$ quarks, giving rise to the decays of charmed hadrons into a lighter hadron plus missing energy carried away by the dark photon. We propose to investigate decays of this kind, especially those in which the parents are the charmed pseudoscalar-mesons $D^{+}$, $D^0$, and $D_s^{+}$ and singly charmed baryons ${\Lambda }_c^{+}$, ${\Xi }_c^{+}$, and ${\Xi }_c^0$. Employing a simplified new-physics model satisfying the relevant constraints, we find that the branching fractions of these processes could be as large as several times $10^{-5}$. This suggests that one or more of them might in the near future fall within reach of the ongoing Belle II and BESIII experiments. Since the same underlying operators are responsible for all of these transitions, detecting one of them automatically implies particular predictions for the others, allowing for additional experimental checks on the massless-dark-photon scenario.

15 pages, no figure, minor errors corrected, matches publication

References in corpus (13)

• Secluded U(1) below the weak scale
• Observation of the doubly charmed baryon ${\Xi }_{cc}^{++}$
• Dark Matter and Dark Radiation
• $B_{(s)},D_{(s)}\to \pi ,K,\eta ,\rho ,K^{\ast },\omega ,\varphi$ Transition Form Factors and Decay Rates with Extraction of the CKM parameters $|V_{ub}|$, $|V_{cs}|$, $|V_{cd}|$
• Rare baryon decays Lambda_b -> Lambda l+ l- (l=e, mu, tau) and Lambda_b -> Lambda gamma : Differential and total rates, lepton- and hadron-side forward-backward asymmetries
• Search for production of an invisible dark photon in ${\pi }^0$ decays
• Photon polarization from helicity suppression in radiative decays of polarized Lambda_b to spin-3/2 baryons
• A comprehensive analysis of weak transition form factors for doubly heavy baryons in the light front approach
• FCNC decays of SM fermions into a dark photon
• Probing a dark photon using rare leptonic kaon and pion decays
• Search for $D^0$ decays to invisible final states at Belle
• Searching for dark photons in hyperon decays
• Kaon decays shedding light on massless dark photons

Cited by in corpus (7)

• The Dark Photon
• Search for a massless dark photon in ${\Lambda }_c^{+}\to p{\gamma }^{\prime }$ decay
• Exploring charm decays with missing energy in leptoquark models
• Flavor phenomenology of light dark sectors
• FCNC charmed-hadron decays with invisible singlet particles in light of recent data
• Search for the massless dark photon with $D^0\to \omega {\gamma }^{\prime }$ and $D^0\to \gamma {\gamma }^{\prime }$
• Probing invisible particles with charm