The Proton Spin and Flavor Structure in the Chiral Quark Model

After a pedagogical review of the simple constituent quark model and deep inelastic sum rules, we describe how a quark sea as produced by the emission of internal Goldstone bosons by the valence quarks can account for the observed features of proton spin and flavor structures. Some issues concerning the strange quark content of the nucleon are also discussed.Comment: 59 pages with table of contents, Lecture delivered at the Schladming Winter School (March 1997), to be published by Springer-Verlag under the title "Computing Particle Properties" (eds. C. B. Lang and H. Gausterer

Less suppressed μ→eγ and τ→μγ loop amplitudes and extra dimension theories

AbstractWhen μeγ (or τμγ) loop involves a vector boson, the amplitude is suppressed by more than two powers of heavy particle masses. However we show that the scalar boson loop diagrams are much less damped. Particularly, the loop amplitude in which the intermediate fermion and scalar boson have comparable masses is as large as possible, as allowed by the decoupling theorem. Such a situation is realized in the “universal extra dimension theory”, and can yield a large enough rate for μeγ to be detectable in current experiments. Our investigation involves precise calculation of the scalar boson loop's dependence on the masses of the intermediate states

The effect of tourists’ technology adoption propensity on the acceptance of smart tourism apps

STA are becoming popular as tourists’ increasing relies on mobile devices in their trip to explore the destination. Therefore, the adoption of STA is crucial to the development of smart tourism. Extant literature mainly focuses on the application of different technology acceptance models. This study explores the impact of tourists’ attitude about technology on their intention to use STA. The technology adoption propensity (TAP) scale was used to measure the technology readiness of tourists in this study. A survey with a structured questionnaire was used to collect data in this study. The respondents were asked to study the introduction of a STA similar to those displayed on an App store and then complete the questionnaire. A total of 355 valid questionnaires were collected. The data were analyzed using the Partial least-squares method (PLS). Since TAP is a multi-dimensional scale, a second-order analysis was performed. From the TAP measures, tourists generally believe that technology changes and improve their daily lives, making their lives easier. However, technology is a double-edged sword, which will bring some adverse effects while improving the tourist's living standard. The result of the path analysis reveals that all the hypotheses proposed in this study are valid. The TAP of tourists has a positive influence on usage intention with trust and curiosity as two partial mediating variables. TAP has a stronger influence on the tourists' curiosity than trust, and curiosity has a stronger effect on tourists’ intentions to use STA than trust. Tourists with higher TAP will plead to increased curiosity about STA, that will prompt them to try, understand, and continue using the STA. The higher the tourists’ trust in the STA, the more willing they would choose and use STA

Heavy particle electroweak loop effects in extra-dimensional models with bulk neutrinos

One way to detect the presence of new particles in theories beyond the standard model is through their contribution to electroweak loop effects. We comment on the importance of a consistent inclusion of their mixing angles to ensure that the physical requirement of heavy particle decoupling is fulfilled. We illustrate our points by a detailed discussion of the lepton flavor changing effect mu-e-gamma, investigated recently by Kitano, in the Randall-Sundrum model. Our remarks are equally applicable to models with large compactified dimensions where bulk neutrinos are introduced to account for the observed neutrino oscillations.Comment: 13 pages; new citations added in Ref [3] and [11

Antiquark Polarization inside the Proton is Small

Quark contributions to the proton spin as deduced from polarized DIS of leptons off a nucleon target, and the octet baryon magnetic moments, can be used to deduce the antiquark polarizations $\Delta_{\overline{q}}$ inside the proton. In this way, the 1992 analysis by Karl is shown to imply $\Delta_{\overline{q}}\simeq 0.$ Such a spin structure fits nicely into the chiral quark interpretation of the proton spin and flavor puzzles.Comment: LaTex and RevTex, 7 pages, sub for pub in the Phys. Lett. B Corrected an equation number error, and revised the Author/Abstract field in the original E-preprint submission. Latex and Revtex. Sub to Phys. Lett.

Scattering of massive W bosons into gravitinos and tree unitarity in broken supergravity

The WW scattering into gravitino and gaugino is here investigated in the broken phase, by using both gauge and mass eigenstates. Differently from what is obtained for unbroken gauge symmetry, we find in the scattering amplitudes new structures, which can lead to violation of unitarity above a certain scale. This happens because, in the annihilation diagram, the longitudinal degrees of freedom in the propagator of the gauge bosons disappear from the amplitude, by virtue of the SUGRA vertex. We show that the longitudinal polarizations of the on-shell W become strongly interacting in the high energy limit, and that the inclusion of diagrams with off-shell scalars of the MSSM does not cancel the divergences.Comment: 26 pages, 17 figures. Uses JHEP3.cls, epsfig.sty and axodraw.sty. Some references, together with Ward identities in the basis of mass eigenstates, have been added. Version accepted for publication in JHE

Octet magnetic moments and the Coleman-Glashow sum rule violation in the chiral quark model

Baryon octet magnetic moments when calculated within the chiral quark model, incorporating the orbital angular momentum as well as the quark sea contribution through the Cheng-Li mechanism, not only show improvement over the non relativistic quark model results but also gives a non zero value for the right hand side of Coleman-Glashow sum rule. When effects due to spin-spin forces between constituent quarks as well as `mass adjustments' due to confinement are added, it leads to an excellent fit for the case of p, \Sigma^+, \Xi^o and violation of Coleman-Glashow sum rule, whereas in almost all the other cases the results are within 5% of the data.Comment: 5 RevTeX pages, accepted for publication in PRD(Rapid Communication

Singlet Charge 2/32/3 Quark hiding the Top: Tevatron and LEP Implications

If $c$ and $t$ quarks are strongly mixed with a weak singlet charge $2/3$ quark, $BR(t\to \ell\nu + X)$ could be suppressed via the $t\to cH^0$ mode, thereby the top quark could still hide below $M_W$, whereas the heavy quark signal observed at the Tevatron is due to the dominantly singlet quark $Q$. This may occur without affecting the small $m_c$ value. Demanding $m_Q \simeq 175$ GeV and m_t \ltap M_W, we find that $BR(t\to \ell\nu + X)$ cannot be too suppressed. The heavy quark $Q$ decays via $W,\ H$, and $Z$ bosons. The latter can lead to $b$-tagged $Z + 4$ jet events, while the strong $c$--$Q$ mixing is reflected in sizable $Q\to sW$ fraction. $Z\to t\bar c$ decay occurs at tree level and may be at the $10^{-3}$ order, leading to the signature of $Z\to \ell\nu b\bar c$, all isolated and with large $p_T$, at $10^{-5}$ order.Comment: 10 pages + 3 Figures (not included), ReVTeX, NTUTH-94-1

Spontaneous Symmetry Breaking in Presence of Electric and Magnetic Charges

Starting with the definition of quaternion gauge theory, we have undertaken the study of SU(2)_{e}\times SU(2)_{m}\times U(1)_{e}\times U(1)_{m} in terms of the simultaneous existence of electric and magnetic charges along with their Yang - Mills counterparts. As such, we have developed the gauge theory in terms of four coupling constants associated with four - gauge symmetry SU(2)_{e}\times SU(2)_{m}\times U(1)_{e}\times U(1)_{m}. Accordingly, we have made an attempt to obtain the abelian and non - Abelian gauge structures for the particles carrying simultaneously the electric and magnetic charges (namely dyons). Starting from the Lagrangian density of two SU(2)\times U(1) gauge theories responsible for the existence of electric and magnetic charges, we have discussed the consistent theory of spontaneous symmetry breaking and Higgs mechanism in order to generate the masses. From the symmetry breaking, we have generated the two electromagnetic fields, the two massive vector W^{\pm} and Z^{0} bosons fields and the Higgs scalar fields