Related papers: Spin Correlations in Dark Photon Searches
Several models of dark matter suggest the existence of hidden sectors consisting of SU(3)_C x SU(2)_L x U(1)_Y singlet fields. The interaction between the ordinary and hidden sectors could be transmitted by new Abelian U'(1) gauge bosons A'…
Using the SDSS spectroscopic sample, we estimate the dark matter halo spin parameter lambda for ~53,000 disk galaxies for which MOPED star formation histories are available. We investigate the relationship between spin and total stellar…
Using the non-equilibrium quantum field theory, photon production from the coherently oscillating axion field in a flat Robertson-Walker cosmology is re-examined. First neglecting the Debye screening of the baryon plasma to photons, we find…
We discuss a formalism for the spin correlations and polarizations in two-particle systems with spins half-half, half-one and one-one, and provide the connections between the polarizations and correlations with the joint angular…
Top-antitop pairs produced at hadron colliders are largely unpolarized, but their spins are highly correlated. The structure of these correlations varies significantly over top production phase space, allowing very detailed tests of the…
A class of models of dark sectors consider new very weak interaction between the ordinary and dark matter transmitted by U'(1) gauge bosons A' (dark photons) mixing with our photons. If such A's exist, they could be searched for in a…
We study the extent to which spin assignments of new particles produced at the LHC can be deduced in the decay of a scalar or fermion C into a new stable (or quasi-stable) particle A through the chain C \to B^\pm q, B^\pm \to A W^\pm, W^\pm…
We report on a correlation between virial mass M and spin parameter lambda for dark matter halos forming at redshifts z > 10. We find that the spin parameter decreases with increasing halo mass. Interestingly, our analysis indicates that…
Positivity constraints have proved to be important for spin observables of exclusive reactions involving polarized initial and final particles. Attention is focused in this note on the photoproduction of pseudoscalar mesons from spin 1/2…
If heavy partners of the Standard Model matter fields are discovered at the LHC it will be imperative to determine their spin in order to uncover the underlying theory. In decay chains, both the spin and the mass hierarchy of all particles…
We describe the off-diagonal spin basis for observing angular correlations in top quark pair production events at the Fermilab Tevatron. For events initiated by quark-antiquark annihilation, the top and antitop quark spins are 100%…
Spin correlations of $e^{+}e^{-}$ pair productions of two colliding photons are investigated and explicit expressions for their corresponding probabilities are derived and found to be \textit{energy} (speed) dependent, for initially…
A sample of $1.69\times 10^7$ fully reconstructed $\pi^0\to\gamma e^+e^-$ decay candidates collected by the NA48/2 experiment at CERN in 2003--2004 is analysed to search for the dark photon ($A'$) production in the $\pi^0\to\gamma A'$ decay…
Dark photon ($A'$) that couples to the standard model fermions via the kinetic mixing with photons and serves as a mediator of dark matter production could be observed in the high-energy electron scattering $e^- + Z ~\rightarrow e^- + Z +…
We consider the effects in the production via gluon fusion in LHC collisions of one or two spin-zero new resonant particles $\Phi$ that decay into a top quark pair. We revisit previous analyses of the interferences between the heavy-fermion…
The diffractive $\phi$-meson photoproduction amplitude is dominated by the Pomeron exchange process and contains the terms that govern the spin-spin and spin-orbital interactions. We show that these terms are responsible for the spin-flip…
Nonrelativistic QCD provides a systematic approach for inclusive decays and productions of a quarkonium. By taking color-octet components into account, the approach can explain the $\psi'$-anomaly at Tevatron, where the measured production…
The PICASSO experiment at SNOLAB reports new results for spin-dependent WIMP interactions on $^{19}$F using the superheated droplet technique. A new generation of detectors and new features which enable background discrimination via the…
We study the production of charginos e^+ e^- -> chi^+_i chi^-_j, (i,j=1,2) with polarized beams and the subsequent decays chi^+_i -> chi^0_k ell^+ nu and chi^-_j -> chi^0_l ell^- nu, (k,l=1,...,4), including the complete spin correlations…
We investigated the spin effect on the vacuum pair production by Dirac-Heisenberg-Wigner (DHW) formalism under two-color counter-rotating electric fields. We primarily studied the combined effects of the field asymmetry, time delay, and…