Håkan Snellman

Neutrino oscillations with three flavors in matter: Applications to neutrinos traversing the Earth

Analytic formulas are presented for three flavor neutrino oscillations in matter in the plane wave approximation. We calculate in particular the time evolution operator in both mass and flavor base ...

Three flavor neutrino oscillations in matter

We derive analytic expressions for three flavor neutrino oscillations in the presence of matter in the plane wave approximation using the Cayley–Hamilton formalism. Especially, we calculate the time evolution operator in both flavor and mass bases. Furthermore, we find the transition probabilities, matter mass squared differences, and matter mixing angles all expressed in terms of the vacuum mass squared differences, the vacuum mixing angles, and the matter density. The conditions for resonance in the presence of matter are also studied in some examples.

Perturbative QCD effects in the non-perturbative low energy region

Abstract We show that a large body of phenomena in p p annihilation into hyperons, or into three mesons containing a pair of strange quarks, as well as K-P scattering with production of a strange quark pair (like K−p→ΦΛ), can be understood as a simple consequence of perturbative QCD dynamics. We give detailed predictions for ratios of cross section, poolarizations and some selection rules. When measured the predictions are well satisfied. LEAR experiments are indicated.

Octet baryon magnetic moments in the chiral quark model with configuration mixing

The Coleman{endash}Glashow sum-rule for magnetic moments is always fulfilled in the chiral quark model, independently of SU(3) symmetry breaking. This is due to the structure of the wave functions, coming from the non-relativistic quark model. Experimentally, the Coleman{endash}Glashow sum-rule is violated by about ten standard deviations. To overcome this problem, two models of wave functions with configuration mixing are studied. One of these models violates the Coleman{endash}Glashow sum-rule to the right degree and also reproduces the octet baryon magnetic moments rather accurately. {copyright} {ital 1997} {ital The American Physical Society}

Decuplet baryon magnetic moments in the chiral quark model

We present calculations of the decuplet baryon magnetic moments in the chiral quark model. As input we use parameters obtained in qualitatively accurate fits to the octet baryon magnetic moments st ...

On the decay of θ mesons in charmonium models

Abstract We derive a new formula for the decay rate of the ψ mesons by properly treating the dependence of lowest order electromagnetic annihilation on the quark-antiquark bound state wave function. Results are presented for currently used non-relativistic potentials models for charmonium. In all cases substantial corrections to previous estimates from commonly used formulas occur. Our results are of relevance also for hadronic decay via gluons in QCD and weak decay of pseudoscalar mesons.

Neutrino oscillations with three flavors in matter of varying density

Abstract. In this paper, we discuss the evolution operator and the transition probabilities expressed as functions of the vacuum mass squared differences, the vacuum mixing angles, and the matter density parameter for three flavor neutrino oscillations in matter of varying density in the plane wave approximation. The applications of this to neutrino oscillations in a model of the earths matter density profile, step function matter density profiles, constant matter density profiles, linear matter density profiles, and finally in a model of the suns matter density profile are discussed. We show that for matter density profiles which do not fluctuate too much, the total evolution operator consisting of n operators can be replaced by one single evolution operator in the semi-classical approximation.

Day-night effect in solar neutrino oscillations with three flavors

We investigate the effects of a nonzero leptonic mixing angle theta(13) on the solar neutrino day-night asymmetry. Using a constant matter density profile for the Earth and well-motivated approxima ...

Relativistic calculation of the two photon coupling of scalar and tensor mesons

The decay rates of scalar and tensor mesons into two photons are calculated in the Bethe-Salpeter bound state formalism. The suppression of the non-relativistic estimates due to relativistic kinematics is found to be substantial. Production crosssections in colliding beam experiments are estimated to be in the picobarn range. Also in the relativistic case the helicity 0 production cross-section of tensor mesons is found to be negligible.

Gluonic corrections to the decay rate of heavy quarkonium states into lepton pairs

We calculate one-gluon corrections to the decay rate of heavy quarkonium states into lepton pairs. We find that the correction due to one-gluon exchange is not very significant for charmonium, and for practical purposes only the relativistic kinematical effects need to be taken into account. For theY family the gluonic corrections are, relatively, of greater importance.