1,784 research outputs found
Testing Parity with Atomic Radiative Capture of
The next generation of "intensity frontier" facilities will bring a
significant increase in the intensity of sub-relativistic beams of . We
show that the use of these beams in combination with thin targets of
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
- 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
- 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 -- is considered. Contrarily to the abelian case, the group
structure is explicitly broken to . 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 decay
CP violation leads to a difference between the parameters and
describing the energy distributions of the charged pions produced in the and decays. We study the
difference 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 is very similar to the corresponding
one defining the parameter in the decays. This
observation allows a determination of the value of , using data on
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