3,504,446 research outputs found
Toward the classification of the realistic free fermionic models
The realistic free fermionic models have had remarkable success in providing
plausible explanations for various properties of the Standard Model which
include the natural appearance of three generations, the explanation of the
heavy top quark mass and the qualitative structure of the fermion mass spectrum
in general, the stability of the proton and more. These intriguing achievements
makes evident the need to understand the general space of these models. While
the number of possibilities is large, general patterns can be extracted. In
this paper I present a detailed discussion on the construction of the realistic
free fermionic models with the aim of providing some insight into the basic
structures and building blocks that enter the construction. The role of free
phases in the determination of the phenomenology of the models is discussed in
detail. I discuss the connection between the free phases and mirror symmetry in
(2,2) models and the corresponding symmetries in the case of the (2,0) models.
The importance of the free phases in determining the effective low energy
phenomenology is illustrated in several examples. The classification of the
models in terms of boundary condition selection rules, real world-sheet fermion
pairings, exotic matter states and the hidden sector is discussed.Comment: 43 pages. Standard Late
Dynamical quark loop light-by-light contribution to muon g-2 within the nonlocal chiral quark model
The hadronic corrections to the muon anomalous magnetic moment a_mu, due to
the gauge-invariant set of diagrams with dynamical quark loop light-by-light
scattering insertions, are calculated in the framework of the nonlocal chiral
quark model. These results complete calculations of all hadronic light-by-light
scattering contributions to a_mu in the leading order in the 1/Nc expansion.
The result for the quark loop contribution is
a_mu^{HLbL,Loop}=(11.0+-0.9)*10^(-10), and the total result is
a_mu^{HLbL,NxQM}=(16.8+-1.2)*10^(-10).Comment: 11 pages, 5 figures, 1 tabl
The influence of toxicity constraints in models of chemotherapeutic protocol escalation
The prospect of exploiting mathematical and computational models to gain insight into the influence of scheduling on cancer chemotherapeutic effectiveness is increasingly being considered. However, the question of whether such models are robust to the inclusion of additional tumour biology is relatively unexplored. In this paper, we consider a common strategy for improving protocol scheduling that has foundations in mathematical modelling, namely the concept of dose densification, whereby rest phases between drug administrations are reduced. To maintain a manageable scope in our studies, we focus on a single cell cycle phase-specific agent with uncomplicated pharmacokinetics, as motivated by 5-Fluorouracil-based adjuvant treatments of liver micrometastases. In particular, we explore predictions of the effectiveness of dose densification and other escalations of the protocol scheduling when the influence of toxicity constraints, cell cycle phase specificity and the evolution of drug resistance are all represented within the modelling. For our specific focus, we observe that the cell cycle and toxicity should not simply be neglected in modelling studies. Our explorations also reveal the prediction that dose densification is often, but not universally, effective. Furthermore, adjustments in the duration of drug administrations are predicted to be important, especially when dose densification in isolation does not yield improvements in protocol outcomes
Vortex line representation for flows of ideal and viscous fluids
It is shown that the Euler hydrodynamics for vortical flows of an ideal fluid
coincides with the equations of motion of a charged {\it compressible} fluid
moving due to a self-consistent electromagnetic field. Transition to the
Lagrangian description in a new hydrodynamics is equivalent for the original
Euler equations to the mixed Lagrangian-Eulerian description - the vortex line
representation (VLR). Due to compressibility of a "new" fluid the collapse of
vortex lines can happen as the result of breaking (or overturning) of vortex
lines. It is found that the Navier-Stokes equation in the vortex line
representation can be reduced to the equation of the diffusive type for the
Cauchy invariant with the diffusion tensor given by the metric of the VLR
- …