Testing Parity with Atomic Radiative Capture of μ−\mu^-

The next generation of "intensity frontier" facilities will bring a significant increase in the intensity of sub-relativistic beams of $\mu^-$. We show that the use of these beams in combination with thin targets of $Z\sim 30$ elements opens up the possibility of testing parity-violating interactions of muons with nuclei via direct radiative capture of muons into atomic 2S orbitals. Since atomic capture preserves longitudinal muon polarization, the measurement of the gamma ray angular asymmetry in the single photon $2S_{1/2}$-$1S_{1/2}$ transition will offer a direct test of parity. We calculate the probability of atomic radiative capture taking into account the finite size of the nucleus to show that this process can dominate over the usual muonic atom cascade, and that the as yet unobserved single photon $2S_{1/2}$-$1S_{1/2}$ transition in muonic atoms can be detected in this way using current muon facilities.Comment: To appear in PR

Neutrino statistics and big bang nucleosynthesis

Neutrinos may possibly violate the spin-statistics theorem, and hence obey Bose statistics or mixed statistics despite having spin half. We find the generalized equilibrium distribution function of neutrinos which depends on a single fermi-bose parameter, \kappa, and interpolates continuously between the bosonic and fermionic distributions when \kappa changes from -1 to +1. We consider modification of the Big Bang Nucleosynthesis (BBN) in the presence of bosonic or partly bosonic neutrinos. For pure bosonic neutrinos the abundances change (in comparison with the usual Fermi-Dirac case) by -3.2% for 4He (which is equivalent to a decrease of the effective number of neutrinos by \Delta N_\nu = - 0.6), +2.6% for 2H and -7% for 7Li. These changes provide a better fit to the BBN data. Future BBN studies will be able to constrain the fermi-bose parameter to \kappa > 0.5, if no deviation from fermionic nature of neutrinos is found. We also evaluate the sensitivity of future CMB and LSS observations to the fermi-bose parameter.Comment: 11 pages, 3 figures, matches version in JCAP, discussion and references extended slightl

Baryon vector and axial content up to the 7Q component

We have used the light-cone formulation of Chiral-Quark Soliton Model to investigate the vector and axial content of octet, decuplet and the hypothetical antidecuplet in the flavor SU(3) symmetry limit. We have extended previous works by computing the 7Q contribution to vector and axial charges for the octet and antidecuplet but stayed at the 5Q sector for the decuplet where the full computation needs much more time. As expected the 7Q component has a weaker impact on the quantities but still changes them by a few percent. We give also a detailed decomposition of those charges into flavor, valence quark, sea quark and antiquark contributions. Many of them are of course not (yet) measured or estimated and constitute then a theoretical estimation. Among the different interesting observations made in this work are the explicit quadrupole deformation of decuplet baryons due to the pion field and the sum of quark spins larger than the pentaquark one.Comment: 34 pages, 7 figures and 17 tables, revised and more explicit versio

Neutrino wave function and oscillation suppression

We consider a thought experiment, in which a neutrino is produced by an electron on a nucleus in a crystal. The wave function of the oscillating neutrino is calculated assuming that the electron is described by a wave packet. If the electron is relativistic and the spatial size of its wave packet is much larger than the size of the crystal cell, then the wave packet of the produced neutrino has essentially the same size as the wave packet of the electron. We investigate the suppression of neutrino oscillations at large distances caused by two mechanisms: 1) spatial separation of wave packets corresponding to different neutrino masses; 2) neutrino energy dispersion for given neutrino mass eigenstates. We resolve contributions of these two mechanisms.Comment: 7 page

The decay eta_c^prime -> eta_c pi pi

It is pointed out that the decay of the recently observed charmonium eta_c^prime resonance, eta_c^prime -> eta_c pi pi is simply related to the well studied decay psi^prime -> J/psi pi pi and can thus be used for absolute normalization of other decay modes of the eta_c^prime. The total rate of the discussed decay should be approximately three to four times the corresponding rate for the psi^prime$ resonance making the channel with charged pions the most probable exclusive decay mode of the eta_c^prime with the branching ratio in the range 5-10 %.Comment: 5 pages, references adde

Interplay of gravitation and linear superposition of different mass eigenstates

The interplay of gravitation and the quantum-mechanical principle of linear superposition induces a new set of neutrino oscillation phases. These ensure that the flavor-oscillation clocks, inherent in the phenomenon of neutrino oscillations, redshift precisely as required by Einstein's theory of gravitation. The physical observability of these phases in the context of the solar neutrino anomaly, type-II supernovae, and certain atomic systems is briefly discussed

SU(2) Kinetic Mixing Terms and Spontaneous Symmetry Breaking

The non-abelian generalization of the Holdom model --{\it i.e.} a theory with two gauge fields coupled to the kinetic mixing term $g {tr}(F_{\mu \nu} (A) F_{\mu \nu} (B))$-- is considered. Contrarily to the abelian case, the group structure $G\times G$ is explicitly broken to $G$. For SU(2) this fact implies that the residual gauge symmetry as well as the Lorentz symmetry is spontaneusly broken. We show that this mechanism provides of masses for the involved particles. Also, the model presents instanton solutions with a redefined coupling constant.Comment: 9pp. typos and clarifications are adde

CP violation in K±→π0π0π±K^{\pm}\to\pi^0\pi^0\pi^{\pm} decay

CP violation leads to a difference between the parameters $g^+$ and $g^-$ describing the energy distributions of the charged pions produced in the $K^+ \to\pi^0 \pi^0 \pi^+$ and $K^- \to \pi^0\pi^0 \pi^-$ decays. We study the difference $(g^+ - g^-)$ as a function of the relative contributions from the QCD-penguin and the electroweak-penguin diagrams. We find that the combination of these contributions in $(g^+ - g^-)$ is very similar to the corresponding one defining the parameter $\epsilon'$ in the $K_L \to 2\pi$ decays. This observation allows a determination of the value of $(g^+ - g^-)$, using data on $\epsilon'$