120650932
Electromagnetic and Axial Form Factors of Octet and Decuplet Baryons
We report from a study of the elastic electromagnetic and axial form factors of all lowest baryon states with flavors up, down, and strange along relativistic constituent-quark models. We consider the baryons as relativistic bound states of three constituent quarks and solve the eigenvalue problem of the invariant mass operator. The corresponding eigenstates are employed to calculate manifestly covariant form factors within the point form of Poincaré-invariant quantum mechanics. The electromagnetic and axial current operators are constructed along the spectator model in point-form relativistic dynamics. We have thus obtained covariant predictions for the electroweak form factors, for momentum transfers up to Q2 ~ 4 GeV2, as well as the electric radii, magnetic moments, and axial charges. The theoretical results in general agree very well with existing phenomenological data. In cases, where no experimental information is yet available, the results are well compatible with data from lattice quantum chromodynamics.
119691200
Spectroscopy of Baryons as Relativistic Three-Quark Systems
We present results from a study of baryon spectral properties within a relativistic constituent-quark model. In particular, we demonstrate the performance of a universal quark model for all light-, strange-, and heavy-flavor baryons with regard to their spectroscopy. Thereby we produce insights into the effective interaction between constituent quarks of the various flavors up, down, strange, charm, and bottom. The relativistically invariant mass spectra are obtained by two different methods for calculating the microscopic three-quark systems: a stochastic variational method, solving the eigenvalue problem of the invariant mass operator expressed by differential equations, and a Faddeev integral-equation method, adapted to treating long-range interactions, such as the quark confinement. The corresponding results agree very well, generally within a few percents. Taking into account relativistic effects through Poincaré invariance of the mass operator, or equivalently of the Hamiltonian, turns out to be of utmost importance.
118129565
Axial properties of the nucleon and N* resonances
We report results from a theoretical study of axial charges and axial form factors of the nucleon N and its resonant states N*. By employing relativistic constituent-quark models we could produce for the first time covariant predictions for the axial-current matrix elements. The calculations are performed in the point form of Poincare-invariant quantum mechanics. The axial charge as well as the axial form factor of the nucleon are reproduced close to phenomenology. The axial charges of the N*(1535) and N*(1650) resonances – the only cases where such a comparison is possible – agree well with results from quantum chromodynamics on the lattice that have recently become available. Here, we present the axial charges of all N* excitations below ~2 GeV and two examples of N* axial form factors. These results should be interesting for comparison with other approaches, especially with regard to the issue of chiral-symmetry restoration in higher-lying hadron resonances.
118574536
Universal Constituent-Quark Model for Baryons
We present a relativistic constituent-quark model that covers all known baryons from the nucleon up to bbb. The corresponding invariant mass operator includes a linear connement and a hyperne interaction based on eective degrees of freedom. The model provides for a unied description of practically all baryon spectra in good agreement with present phenomenology and it can tentatively be employed for the relativistic treatment of all kinds of baryon reactions. Predictions of states still missing in the phenomenological data base, especially in the lesser explored heavy-avor sectors of charm and bottom baryons, should be important especially for future experiments in these areas.
125677314
Unified model for light- and heavy-flavor baryon resonances
126277985
Relativistic quark-model spectroscopy of light and heavy baryons
We report results from a study of lightand heavy-baryon spectra within a relativistic constituent quark model that relies on a universal dynamics for baryons of all flavor contents. The (linear) confinement is taken according to the string tension of quantum chromodynamics and the (flavordependent) hyperfine interaction is derived from an effective Lagrangian resulting from chiralsymmetry breaking. Here, we specifically show results for all baryons that are included in the phenomenological data base of the Particle Data Group with at least three-star status. In general, the spectra are reproduced in good agreement with experiment for both ground and excited states.
118042770
SU(3) x SU(2) x U(1) Vacua in F-Theory
The Standard Model group and matter spectrum is obtained in vacua of F-theory, without resorting to an intermediate unification group. The group SU(3) x SU(2) x U(1)_Y is the commutant to SU(5)_t \times U(1)_Y structure group of a Higgs bundle in E_8 and is geometrically realized as a deformation of I_5 singularity. Lying along the unification groups of E_n, our vacua naturally inherit their unification structure. By modding SU(5)_t out by Z_4 monodromy group, we can distinguish Higgses from lepton doublets by matter parity. Turning on universal G-flux on this part, the spectrum contains three generations of quarks and leptons, as well as vectorlike pairs of electroweak and colored Higgses. Minimal Yukawa couplings is obtained at the renormalizable level.
119159824
Non-Gaussianity and gravitational wave background in curvaton with a double well potential
We study the density perturbation by a curvaton with a double well potential and give analytical expressions for the observables such as nonlinear parameters f{sub NL}, g{sub NL} and tensor-to-scalar ratio r{sub T} with emphasizing the differences from the simple quadratic potential. We show that the level of non-Gaussianity and the tensor-to-scalar ratio depends crucially on the reheating temperature as well as the curvaton self-coupling constant for a given initial amplitude of the curvaton. We find that for a large initial field the nonlinear parameters f{sub NL} can be 10-20 and the gravitational wave background also is observable in the Planck satellite.
119200217
Towards the MSSM from F-theory
Abstract We study the MSSM in F-theory. Its group is the commutant to a structure group SU ( 5 ) × U ( 1 ) Y of a gauge bundle in E 8 . The spectrum contains three generations of quarks and leptons plus vectorlike electroweak and colored Higgses. The minimal MSSM Yukawa couplings with matter parity is obtained at the renormalizable level.
54193494
Sparticle spectrum of large volume compactification
We examine the large volume compactification of Type IIB string theory or its F theory limit and the associated supersymmetry breakdown and soft terms. It is crucial to incorporate the loop-induced moduli mixing, originating from radiative corrections to the Kähler potential. We show that in the presence of moduli mixing, soft scalar masses generically receive a D-term contribution of the order of the gravitino mass m3/2 when the visible sector cycle is stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while the moduli-mediated gaugino masses and A-parameters tend to be of the order of m3/2/8π2. It is noticed also that a too large moduli mixing can destabilize the large volume solution by making it a saddle point.
119212917
Natural inflation with multiple sub-Planckian axions
We extend the Kim-Nilles-Peloso (KNP) alignment mechanism for natural inflation to models with $N>2$ axions, which obtains a super-Planckian effective axion decay constant $f_{\textrm{eff}}\gg M_{Pl}$ through an alignment of the anomaly coefficients of multiple axions having sub-Planckian fundamental decay constants $f_0\ll M_{Pl}$. The original version of the KNP mechanism realized with two axions requires that some of the anomaly coefficients should be of the order of $f_{\textrm{eff}}/f_0$, which would be uncomfortably large if $f_{\rm eff}/f_0 \gtrsim {\cal O}(100)$ as suggested by the recent BICEP2 results. We note that the KNP mechanism can be realized with the anomaly coefficients of $\mathcal{O}(1)$ if the number of axions $N$ is large as $N\ln N\gtrsim 2\ln (f_{\textrm{eff}}/f_0)$, in which case the effective decay constant can be enhanced as $f_{\rm eff}/f_0 \sim \sqrt{N !}\,n^{N-1}$ for $n$ denoting the typical size of the integer-valued anomaly coefficients. Comparing to the other multiple axion scenario, the N-flation scenario which requires $N \sim f_{\textrm{eff}}^2/f_0^2$, the KNP mechanism has a virtue of not invoking to a too large number of axions, although it requires a specific alignment of the anomaly coefficients, which can be achieved with a probability of ${\cal O}(f_0/f_{\rm eff})$ under a random choice of the anomaly coefficients. We also present a simple model realizing a multiple axion monodromy along the inflaton direction.