Origin Of Mixing Research Articles

Flavor symmetryLe−Lμ−Lτ, atmospheric neutrino mixing, andCPviolation in the lepton sector

The PMNS neutrino mixing matrix is given, in general, by the product of two unitary matrices associated with the diagonalization of the charged lepton and neutrino mass matrices. Assuming that the active flavor neutrinos possess a Majorana mass matrix which is diagonalized by a bimaximal mixing matrix, we give the allowed forms of the charged lepton mixing matrix and the corresponding implied forms of the charged lepton mass matrix. We then assume that the origin of bimaximal mixing is a weakly broken flavor symmetry corresponding to the conservation of the non–standard lepton charge L ′ = Le − Lµ − Lτ. The latter does not predict, in general, the atmospheric neutrino mixing to be maximal. We study the impact of this fact on the allowed forms of the charged lepton mixing matrix and on the neutrino mixing observables, analyzing the case of CP–violation in detail. When compared with the case of exact bimaximal mixing, the deviations from zero Ue3 and from maximal atmospheric neutrino mixing are typically  

Fast geochemical changes and rapid lava accumulation at Stromboli Island (Italy) inferred from K–Ar dating and paleomagnetic variations recorded at 60 and 40 ka

Forty-three lava flows from the Vallone di Rina (Stromboli, Aeolian Islands, Italy) have been investigated for paleomagnetic, geochemical and K–Ar analyses. K–Ar dating shows that two fast building stages occurred at 62±1 and 40±2 ka. The comparison with archeomagnetic variations for the last 2 kyr shows that the time interval covered by the Vallone di Rina section is at the most a few thousand years, most probably on the order of a few hundred years. Such high accumulation rate can be related to the Stromboli volcanic history, which is marked by five to seven successive collapses. The rapid effusion rate of these Paleo-Stromboli (PST) II lavas suggests that they have been erupted shortly after the Paleo-Stromboli I collapse in response to pressure release due to instantaneous deloading. Their age of 62±1 ka is thus interpreted here as the age of the Paleo-Stromboli I collapse event. Similarly, the age of 40±2 ka obtained for lavas from Paleo-Stromboli III can be related with another collapse event. As previously recognized, major and trace elements of these lava flows show that they are compatible with magma sources of metasomatized mantle origin and various crustal levels of melting and mixing. They display recurrent jumps from calc-alkaline to high-K calc-alkaline and shoshonitic series within a very short time span, which suggest that several magmatic systems were operating simultaneously. Finally, we have shown that the combined approach of absolute dating provided by the K–Ar Cassignol technique, together with high-resolution paleomagnetic data compared to historical variations, can constrain, for high extrusion rates, the relative lava emplacements to within a few hundred years.

What can we learn from high precision measurements of neutrino mixing angles?

Many experiments are being planned to measure the neutrino mixing angles more precisely. In this note, the theoretical significance of a high precision measurement of these parameters is discussed. It is emphasized that they can provide crucial information about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining the neutrino mass matrix. They may also be able to throw light on the question of lepton-quark unification as well as the existence of any leptonic symmetries. For instance if exact μ↔ τ symmetry in the neutrino mass matrix is assumed to be the reason for maximalv μ-vgt mixing, one gets θ13 = 0 and {ie1295-01} can provide information about the way the μ↔ τ symmetry breaking manifests in the case of normal hierarchy.

Theta-13 as a Probe of Mu-Tau symmetry for Leptons

Many experiments are being planned to measure the neutrino mixing parameter $\theta_{13}$ using reactor as well as accelerator neutrino beams. In this note, the theoretical significance of a high precision measurement of this parameter is discussed. It is emphasized that it will provide crucial information about different ways to understand the origin of large atmospheric neutrino mixing and move us closer towards determining the neutrino mass matrix. For instance if exact $\mu\leftrightarrow \tau$ symmetry in the neutrino mass matrix is assumed to be the reason for maximal $\nu_\mu-\nu_\tau$ mixing, one gets $\theta_{13}=0$. Whether $\theta_{13}\simeq \sqrt{\Delta m^2_{\odot}/\Delta m^2_A}$ or $\theta_{13}\simeq \Delta m^2_{\odot}/\Delta m^2_A$ can provide information about the way the $\mu\leftrightarrow \tau$ symmetry breaking manifests in the case of normal hierarchy. We also discuss the same question for inverted hierarchy as well as possible gauge theories with this symmetry.

On the origin of the UV-IR mixing in non-commutative matrix geometry

Scalar field theories with quartic interaction are quantized on fuzzy S 2 and fuzzy S 2× S 2 to obtain the 2- and 4-point correlation functions at one-loop. Different continuum limits of these non-commutative matrix spheres are then taken to recover the quantum non-commutative field theories on the non-commutative planes R 2 and R 4 , respectively. The canonical limit of large stereographic projection leads to the usual theory on the non-commutative plane with the well-known singular UV-IR mixing. A new planar limit of the fuzzy sphere is defined in which the non-commutativity parameter θ, beside acting as a short distance cut-off, acts also as a conventional cut-off Λ= 2 θ in the momentum space. This non-commutative theory is characterized by absence of UV-IR mixing. The new scaling is implemented through the use of an intermediate scale that demarcates the boundary between commutative and non-commutative regimes of the scalar theory. We also comment on the continuum limit of the 4-point function.

Physical origin of ion mixing induced amorphization and associated asymmetric growth in the binary metal systems

It has been clarified that the physical origin for a crystalline metal to transform into amorphous is the collapsing of the crystalline lattice while the solute atoms exceeding its critical solid solubility. In ion beam mixing, there are two major factors influencing the amorphization behavior, i.e. the critical solid solubilities and defect (or damage) creation rates of the two constituent metals and it is accordingly predicted that if there exists any difference between the two metals in achieving their respective critical solid solubilities, asymmetric growth would take place. For the Ni–Sc system, the solid solubilities are almost identical, yet the damage creation rate in Ni is about 3 times of that in Sc. Whereas for the Ni–W system, the damage creation rates are basically the same, yet the solid solubility of Ni in W lattice was much smaller than W in Ni. Carefully performed ion beam mixing experiments indeed revealed an asymmetric amorphization in the two systems with predicted preferential directions. Moreover, similar asymmetric amorphization observed in some other systems could also be well explained by the above principle.

Oxygen-18 and Deuterium Fingerprinting of Tailings Seepage at the Sullivan Mine

Stable isotopes of water, 18O and 2H, were used to fingerprint and quantify the origin and percentage of mixing between tailings pond effluent, seepage collection waters, and background waters at the Sullivan Mill Site, which is located in Kimberley, British Columbia, Canada. The old iron and siliceous ponds are covered by a layer of permeable float rock, which allows meteoric waters to directly infiltrate without undergoing evaporation. In contrast, the east gypsum pond is covered with a layer of till and vegetation, which causes meteoric waters to pond and subsequently be subjected to evaporative processes. The different evaporative environments result in distinctly different isotopic compositions for the waters collected from these sources. The difference in surface cover was used advantageously to identify particular isotopic ratios for the different tailings sources. Water collected from the east gypsum pond is relatively enriched in the heavier isotopes (δ18O and δ2H), whereas water collected from various locations in the siliceous and old iron pond are relatively depleted in δ18O and δ2H. The various seepage collection waters were observed to plot at intermediate positions, corresponding either to the old iron pond mixing line, the gypsum pond evaporation line, or somewhere between the two.

Geometric origin of large lepton mixing in a higher-dimensional spacetime

The large mixing in the lepton sector observed in the recent neutrino-oscillation experiments strongly suggests that nature of left-handed lepton doublets is very different from that of left-handed quark doublets. This means that there is a big disparity between the matter multiplets 5∗'s and 10's in the SU(5) unified theory. We show that this big difference can be explained in a six-dimensional spacetime compactified on the T2/Z3 orbifold. That is, we propose to put three families of 5∗'s on three equivalent fixed points of the orbifold and the three 10's in the two-dimensional bulk. We construct an explicit model realizing this situation and show that the democratic mass structure in the lepton sector is naturally obtained and hence the model explains the observed bi-large lepton mixing and simultaneously the required small mixing Ue3. The mass matrices and mixing in the quark sector are also briefly discussed.

Beam and experiments: summary

The discovery of neutrino oscillations marks a major milestone in the history of neutrino physics, and opens a new window to the still mysterious origin of masses and flavour mixing. Many current and forthcoming experiments will answer open questions; however, a major step forward, up to and possibly including CP violation in the neutrino-mixing matrix, requires the neutrino beams from a neutrino factory. The neutrino factory is a new concept for producing neutrino beams of unprecedented quality in terms of intensity, flavour composition, and precision of the beam parameters. Most importantly, the neutrino factory is the only known way to generate a high-intensity beam of electron neutrinos of high energy. The neutrino beam from a neutrino factory, in particular the electron–neutrino beam, enables the exploration of otherwise inaccessible domains in neutrino oscillation physics by exploiting baselines of planetary dimensions. Suitable detectors pose formidable challenges but seem within reach with only moderate extrapolations from existing technologies. Although the main physics attraction of the neutrino factory is in the area of neutrino oscillations, an interesting spectrum of further opportunities ranging from high-precision, high-rate neutrino scattering to physics with high-intensity stopped muons comes with it.

Partial Yukawa unification and a supersymmetric origin of flavor mixing

In a large class of supersymmetric SO(10) and left-right models, requiring that the effective theory below the scale of $SU(2)_R$ breaking be the MSSM implies partial Yukawa unification with $Y_u=Y_d$ and $Y_e=Y_{\nu^D}$. The same result also emerges in models with a horizontal $SU(3)_H$ symmetry. As a result, at the tree level, these models lead to vanishing quark mixing angles. We show that the correct mixing pattern can be generated in these models at the loop level from the flavor structure associated with the supersymmetry breaking terms. We generalize the constraints on supersymmetric parameters from flavor changing neutral current (FCNC) processes to include several squark mass insertions and confirm the consistency of the scheme. The expectations of this scheme for CP violating observables in the $B$ meson system are quiet different from the KM model, so it can be tested at the B factories.

The interelectronic angle in doubly excited states and the quality of approximate quantum numbers

We present complex scaling calculations of the cosine of the interelectronic angle in doubly excited states of helium below the N = 4 threshold. Since it is directly connected to one of the approximate quantum numbers commonly used to classify doubly excited states, an analysis of this expectation value will give information about the quality of this quantum number. Deviations from the predicted value already occur in the lowest manifold of resonances and are interpreted as a mixture of different basis states. This assertion is tested by a direct doubly excited symmetry basis expansion. Two types of mixing are observed; mixing of basis states to form Rydberg series and mixing of Rydberg series converging to the same threshold. As a possible origin of the basis state mixing which affects the Rydberg series as a whole, avoided crossings in the variation of the resonance energies with respect to the nuclear charge Z are discussed. Mixing between Rydberg series is due to close degeneracies in the resonance energies and connected with avoided crossings in the quantum defect. Both types can easily be distinguished by regarding real and imaginary parts of the complex expectation value.

Flavor physics — Summary and commentary (Exploring the origin of fermion masses, mixing, and CP violation)

Flavor physics has played an important historical role in unveiling Nature's intricacies and challenging our imaginations. It is expected to continue that legacy well into the future. In this conference summary, I recall some critical Standard Model developments associated with K, B, μ, τ, and ν studies and describe ongoing and anticipated efforts many of which have been reported on at this meeting.

Mixing enthalpy and phase separation in a poly(propylene oxide)–water system

Calorimetric measurements of the differential enthalpies of mixing a propylene oxide oligomer and water at two temperatures have been performed and the integral mixing enthalpies were found to be exothermic. The measurements were compared with the predictions of an extended Flory–Huggins model and a semiquantitative agreement was found. The model suggests that the origin of the exothermic mixing is a conformational change of the propylene oxide oligomer from less polar and higher-energy conformers to more polar and lower-energy conformers upon mixing with water.

The breaking of subnuclear democracy as the origin of flavour mixing

It is shown that the simplest breaking of the subnuclear democracy leads to a successful description of the mixing between the second and third family. In the lepton channel the ν μ – ν τ oscillations are expected to be described by a mixing angle of 2.65° which might be observed soon in neutrino experiments.

FLAVOR MIXING AND THE UA(1) ANOMALY

The relevance of the UA(1) anomaly is discussed in the context of models with constituent quarks. It is argued that at the mean-field level (large Nc), the inclusion of the UA(1)anomaly does not necessarily lead to flavor mixing as generally believed. Arguments are presented for the generic character of flavor dynamics at low energy and the complex origin of flavor mixing in relation to the bulk properties of the QCD vacuum.

Origin and size of hypolimnic mixing in Urnersee, the southern basin of Vierwaldstättersee (Lake Lucerne)

Urnersee and Gersauersee are two adjacent basins of Vierwaldstättersee (Lake Lucerne, Switzerland), seperated by a sill of 85 m depth, with similar topography (max. depth 195 and 213 m, respectively) but remarkably different exposure to “external forces”, such as wind and river input. Urnersee is exposed to diurnal winds and to occasional strong storms from the south (Föhn) whereas the wind over Gersauersee is moderate or weak. Two rivers, both having very large discharges during storms, replace the total water volume of Urnersee about once a year; in contrast, no large river flows directly into Gersauersee. Between March and October 1986, meteorological parameters, water temperatures and currents were measured quasi-continuously with the aim to quantify hypolimnic water exchange and mixing in Urnersee and to asses the relative importance of wind mixing versus river-induced water exchange for the renewal of the deep water layers. Three periods could be identified: (1) in April, weak stratification and strong episodic storms exchange about 50% of the deep hypolimnion (DH, defined as layer below 110 m depth) leading to a mean heat flux of 36 Wm2. Because of the large wind mixing the water of the exposed Urnersee below about 20 m depth becomes lighter than in the sheltered Gersauersee. (2) In May and June, the horizontal density gradient causes about 65% renewal of the Urnersee DH by the heavier Gersauersee intermediate water but does not affect the heart content. (3) Simultaneously with these processes are the episodic river floods adding another 20% to the DH water exchange and causing a heat flux of about 6 Wm2. During the rest of the summer, water exchange remains below 10% and is mainly due to episodic flood while wind mixing has little influence. Yet, during floods water input into the DH per unit time can still be very large and heat, fluxes reach 600 Wm2 or more. The influence of lateral density currents between the two adjacent basins on hypolimnic mixing is of great ecological significance and explains the oxygen saturation found in the deep water of Urnersee compared to Gersauersee.

Toward the Origin of Quark Masses and Mixing

Toward the Origin of Quark Masses and Mixing

Quark-based phenomenology of strong and electromagnetic particle mixing

Isoscalar quark-annihilation diagrams mediated by gluon exchanges are assumed to be the origin of particle mixing. Without specifying the detailed dynamics, the ${0}^{\ensuremath{-}}$, ${0}^{+}$, ${1}^{\ensuremath{-}}$, ${1}^{+}$, and ${2}^{+}$ meson U(3) nonets are systematically diagonalized and compared with quadratic mixing-angle and meson-decay predictions at the semistrong level. The scheme is then extended to higher U(3) nonets, to the charmed sector, and to electromagnetic quark-annihilation diagrams in conjunction with SU(2) meson mass splittings and nonphotonic ${\ensuremath{\eta}}_{3\ensuremath{\pi}}$, ${\ensuremath{\omega}}_{2\ensuremath{\pi}}$, and ${\ensuremath{\psi}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\psi}{\ensuremath{\pi}}^{0}$ meson decays. Finally, the phenomenologically deduced quark-annihilation strengths are classified in quark-model language and used to qualitatively justify the gluon-exchange QCD picture.

Gap equations, particle mixing and the U(1) problem in QCD

Abstract The gap equation for the chiral-limiting quark mass is shown to be the basis of the Goldberger-Treiman relation at the quark level, again a gap equation, for both the massless it and massive U(1) ηo states. The strength β of the isoscalar quark annihilation graphs is also demonstrated to be the origin of isoscalar qq particle mixing. Combining these three results, the perturbative second order U(1) anomaly contribution βp (2)/m2 ηo then generates a third U(1) gap equation. The latter resolves the U(1) problem in QCD because it explains why the η′ mass is significantly larger than the π,κ,η octet masses.

Optical pumping in different regions of the F centre absorption band

The origin of spin mixing in the optical pumping cycle of F centres is investigated by measuring its wavelength dependence in the F band of KCl and KBr and the K band of KJ.