The contributions of qqqqqˉqqqq\bar{q} components to the axial charges of proton and its resonances

We calculate the axial charges of the proton and its resonances in the framework of the constituent quark model, which is extended to include the $qqqq\bar{q}$ components. If 20% admixtures of the $qqqq\bar{q}$ components in the proton are assumed, the theoretical value for the axial charge in our model is in good agreement with the empirical value, which can not be well reproduced in the traditional constituent quark model even though the $SU(6) \bigotimes O(3)$ symmetry breaking or relativistic effect is taken into account. We also predict an unity axial charge for $N^{*}(1440)$ with 30% $qqqq\bar{q}$ components constrained by the strong and electromagnetic decays.Comment: 4 pages, 4 table

A_4 flavour symmetry breaking scheme for understanding quark and neutrino mixing angles

We propose a spontaneous A_4 flavour symmetry breaking scheme to understand the observed pattern of quark and neutrino mixing. The fermion mass eigenvalues are arbitrary, but the mixing angles are constrained in such a way that the overall patterns are explained while also leaving sufficient freedom to fit the detailed features of the observed values, including CP violating phases. The scheme realises the proposal of Low and Volkas to generate zero quark mixing and tribimaximal neutrino mixing at tree-level, with deviations from both arising from small corrections after spontaneous A_4 breaking. In the neutrino sector, the breaking is A_4 --> Z_2, while in the quark and charged-lepton sectors it is A_4 --> Z_3 = C_3. The full theory has A_4 completely broken, but the two different unbroken subgroups in the two sectors force the dominant mixing patterns to be as stated above. Radiative effects within each sector are shown to deviate neutrino mixing from tribimaximal, while maintaining zero quark mixing. Interactions between the two sectors -- "cross-talk" -- induce nonzero quark mixing, and additional deviation from tribimaximal neutrino mixing. We discuss the vacuum alignment challenge the scenario faces, and suggest three generic ways to approach the problem. We follow up one of those ways by sketching how an explicit model realising the symmetry breaking structure may be constructed.Comment: 14 pages, no figures; v3: Section 5 rewritten to correct an error; new section added to the appendix; added references; v4: minor change to appendix C, version to be published by JHE

Robust paramagnetism in Bi2-xMxRu2O7 (M=Mn,Fe,Co,Ni,Cu) pyrochlore

We report physical property characterization of Bi2-xMxRu2O7 pyrochlores, including magnetic suseptibility, resistivity, and Seebeck coefficients. The solid solution exists up to x=0.5 for (M=Cu,Ni,Co) and up to x=0.1 for (M=Fe,Mn). None of the doped materials exhibit ferromagnetism or any localized ruthenium moment behavior. Instead we find the Ru-O and Bi-O sublattices to be essentially independent, with any magnetism resulting from the unpaired transition metal dopant spins. Cobalt substitution for bismuth results in localized Co{2+}, and low temperature spin-glass transitions in several cases. Nickel moments on the pyrochlore lattice display properties intermediate to localized and itinerant. Finally, copper doping results in only an enhancement of the Pauli metallic density of states.Comment: submitted, Phys. Rev.

Strong Gravitational Lensing in a Charged Squashed Kaluza- Klein Black hole

In this paper we investigate the strong gravitational lensing in a charged squashed Kaluza-Klein black hole. We suppose that the supermassive black hole in the galaxy center can be considered by a charged squashed Kaluza-Klein black hole and then we study the strong gravitational lensing theory and estimate the numerical values for parameters and observables of it. We explore the effects of the scale of extra dimension $\rho_0$ and the charge of black hole $\rho_q$ on these parameters and observables.Comment: 17 pages, 10 figure

Beautiful Mirrors and Precision Electroweak Data

The Standard Model (SM) with a light Higgs boson provides a very good description of the precision electroweak observable data coming from the LEP, SLD and Tevatron experiments. Most of the observables, with the notable exception of the forward-backward asymmetry of the bottom quark, point towards a Higgs mass far below its current experimental bound. The disagreement, within the SM, between the values for the weak mixing angle as obtained from the measurement of the leptonic and hadronic asymmetries at lepton colliders, may be taken to indicate new physics contributions to the precision electroweak observables. In this article we investigate the possibility that the inclusion of additional bottom-like quarks could help resolve this discrepancy. Two inequivalent assignments for these new quarks are analysed. The resultant fits to the electroweak data show a significant improvement when compared to that obtained in the SM. While in one of the examples analyzed, the exotic quarks are predicted to be light, with masses below 300 GeV, and the Higgs tends to be heavy, in the second one the Higgs is predicted to be light, with a mass below 250 GeV, while the quarks tend to be heavy, with masses of about 800 GeV. The collider signatures associated with the new exotic quarks, as well as the question of unification of couplings within these models and a possible cosmological implication of the new physical degrees of freedom at the weak scale are also discussed.Comment: 21 pages, 4 embedded postscript figures, LaTeX. Two minor corrections performe

A Supersymmetric D4 Model for mu-tau Symmetry

We construct a supersymmeterized version of the model presented by Grimus and Lavoura (GL) in [1] which predicts theta_{23} maximal and theta_{13}=0 in the lepton sector. For this purpose, we extend the flavor group, which is D4 x Z2^{(aux)} in the original model, to D4 x Z5. An additional difference is the absence of right-handed neutrinos. Despite these changes the model is the same as the GL model, since theta_{23} maximal and theta_{13}=0 arise through the same mismatch of D4 subgroups, D2 in the charged lepton and Z2 in the neutrino sector. In our setup D4 is solely broken by gauge singlets, the flavons. We show that their vacuum structure, which leads to the prediction of theta_{13} and theta_{23}, is a natural result of the scalar potential. We find that the neutrino mass matrix only allows for inverted hierarchy, if we assume a certain form of spontaneous CP violation. The quantity |m_{ee}|, measured in neutrinoless double beta decay, is nearly equal to the lightest neutrino mass m3. The Majorana phases phi1 and phi2 are restricted to a certain range for m3 < 0.06 eV. We discuss the next-to-leading order corrections which give rise to shifts in the vacuum expectation values of the flavons. These induce deviations from maximal atmospheric mixing and vanishing theta_{13}. It turns out that these deviations are smaller for theta_{23} than for theta_{13}.Comment: 19 pages, 4 figure

Exclusion Statistics of Quasiparticles in Condensed States of Composite Fermion Excitations

The exclusion statistics of quasiparticles is found at any level of the hierarchy of condensed states of composite fermion excitations (for which experimental indications have recently been found). The hierarchy of condensed states of excitations in boson Jain states is introduced and the statistics of quasiparticles is found. The quantum Hall states of charged $\alpha$-anyons ($\alpha$ -- the exclusion statistics parameter) can be described as incompressible states of $(\alpha+2p)$-anyons ($2p$ -- an even number).Comment: 4 page

'Mu-Tau' symmetry, tribimaximal mixing and four zero neutrino Yukawa textures

Within the type-I seesaw framework with three heavy right chiral neutrinos and in the basis where the latter and the charged leptons are mass diagonal, a near `mu-tau' symmetry in the neutrino sector is strongly suggested by the neutrino oscillation data. There is further evidence for a close to the tribimaximal mixing pattern which subsumes `mu-tau' symmetry. On the other hand, the assumption of a (maximally allowed) four zero texture in the Yukawa coupling matrix Y_nu in the same basis leads to a highly constrained and predictive theoretical scheme. We show that the requirement of an exact `mu-tau' symmetry, coupled with observational constraints, reduces the `seventy two' allowed textures in such a `Y_nu' to 'only four' corresponding to just two different forms of the light neutrino mass matrix `m_nu'. The effect of each of these on measurable quantities can be described, apart from an overall factor of the neutrino mass scale, in terms of two real parameters and a phase angle all of which are within very constrained ranges. The additional input of a tribimaximal mixing reduces these three parameters to `only one' with a very nearly fixed value. Implications for both flavored and unflavored leptogenesis as well as radiative lepton flavor violating decays are discussed. We also investigate the stability of these conclusions under small deviations due to renormalization group running from a high scale where the four zero texture as well as `mu-tau' symmetry or the tribimaximal mixing pattern are imposed.Comment: Typographical changes,accepted for publication in JHE

Enlargement of ribbons in zebrafish hair cells increases calcium currents, but disrupts afferent spontaneous activity and timing of stimulus onset.

In sensory hair cells of auditory and vestibular organs, the ribbon synapse is required for the precise encoding of a wide range of complex stimuli. Hair cells have a unique presynaptic structure-the synaptic ribbon-that organizes both synaptic vesicles and calcium channels at the active zone. Previous work has shown that hair-cell ribbon size is correlated with differences in postsynaptic activity. However, additional variability in postsynapse size presents a challenge to determining the specific role of ribbon size in sensory encoding. To selectively assess the impact of ribbon size on synapse function, we examined hair cells in transgenic zebrafish that have enlarged ribbons, without postsynaptic alterations. Morphologically, we found that enlarged ribbons had more associated vesicles and reduced presynaptic calcium-channel clustering. Functionally, hair cells with enlarged ribbons had larger global and ribbon-localized calcium currents. Afferent neuron recordings revealed that hair cells with enlarged ribbons resulted in reduced spontaneous spike rates. Additionally, despite larger presynaptic calcium signals, we observed fewer evoked spikes with longer latencies from stimulus onset. Taken together, our work indicates that hair-cell ribbon size influences the spontaneous spiking and the precise encoding of stimulus onset in afferent neurons.SIGNIFICANCE STATEMENTNumerous studies support that hair-cell ribbon size corresponds with functional sensitivity differences in afferent neurons and, in the case of inner hair cells of the cochlea, vulnerability to damage from noise trauma. Yet it is unclear whether ribbon size directly influences sensory encoding. Our study reveals that ribbon enlargement results in increased ribbon-localized calcium signals, yet reduces afferent spontaneous activity and disrupts the timing of stimulus onset-a distinct aspect of auditory and vestibular encoding. These observations suggest that varying ribbon size alone can influence sensory encoding, and give further insight into how hair cells transduce signals that cover a wide dynamic range of stimuli

Long-term trends in tropical cyclone tracks around Korea and Japan in late summer and early fall

This study investigates long-term trends in tropical cyclones (TCs) over the extratropical western North Pacific (WNP) over a period of 35 years (1982-2016). The area analyzed extended across 30-45 degrees N and 120-150 degrees E, including the regions of Korea and Japan that were seriously affected by TCs. The northward migration of TCs over the WNP to the mid-latitudes showed a sharp increase in early fall. In addition, the duration of TCs over the WNP that migrated northwards showed an increase, specifically in early to mid-September. Therefore, more recently, TC tracks have been observed to significantly extend into the mid-latitudes. The recent northward extension of TC tracks over the WNP in early fall was observed to be associated with changes in environmental conditions that were favorable for TC activities, including an increase in sea surface temperature (SST), decrease in vertical wind shear, expansion of subtropical highs, strong easterly steering winds, and an increase in relative vorticity. In contrast, northward migrations of TCs to Korea and Japan showed a decline in late August, because of the presence of unfavorable environmental conditions for TC activities. These changes in environmental conditions, such as SST and vertical wind shear, can be partially associated with the Pacific decadal oscillation