Phenomenological analysis of D-brane Pati-Salam vacua

In the present work we perform a phenomenological analysis of the effective low energy models with Pati-Salam (PS) gauge symmetry derived in the context of D-branes. A main issue in these models arises from the fact that the right-handed fermions and the PS-symmetry breaking Higgs field transform identically under the PS symmetry, causing unnatural matter-Higgs mixing effects. We argue that this problem could be solved in particular D-brane setups where these fields arise in different intersections. We further observe that whenever a large Higgs mass term is generated in a particular class of mass spectra, a splitting mechanism -reminiscent of the doublet triplet splitting- may protect the neutral Higgs components from a heavy mass term. We analyze the implications of each individual representation which in principle is available in these models in order to specify the minimal spectrum required to build up a consistent PS model which reconciles the low energy data. A short discussion is devoted on the effects of stringy instanton corrections, particularly those generating missing Yukawa couplings and contributing to the fermion mass textures. We discuss the correlations of the intersecting D-brane spectra with those obtained from Gepner constructions and analyze the superpotential, the resulting mass textures and the low energy implications of some examples of the latter along the lines proposed above.Comment: 50 pages, 3 figures (v2 - Minor corrections

An atypical biceps brachii and coracobrachialis muscles associated with multiple neurovascular aberrations: a case report with clinical significance

Neural and vascular variations in the axilla and upper limb area are usually paired, but coexistence of muscular aberration on top of this is uncommon. The current case report emphasizes on the unilateral coexistence of a three-headed (tricipital) biceps brachii muscle, a two-headed coracobrachialis with an accessory muscle bundle joining the superficial and deep heads of coracobrachialis muscle. On the ipsilateral side of the 72-year-old male cadaver, a connecting branch originated from the musculocutaneous nerve and joined the median nerve after surpassing the accessory muscle bundle. A large diameter subscapular trunk originated from the 2nd part of the axillary artery and after giving off the 1st lateral thoracic artery trifurcated into a common stem which gave off the 2nd and 3rd lateral thoracic arteries, the circumflex scapular artery and a common branch that gave off the 4th and 5th lateral thoracic arteries and the thoracodorsal artery, as the ultimate branch. All lateral thoracic arteries were accompanied by multiple intercostobra- chial nerves. Documentation of such muscular and neurovascular variants and their embryologic origin increases awareness of their potential impact on diagnosis and treatment of upper limb pathology. To the best of our knowledge, the currently reported cadaveric observations seem to constitute a unique finding.

SU(5) D-brane realizations, Yukawa couplings and proton stability

We discuss SU(5) Grand Unified Theories in the context of orientifold compactifications. Specifically, we investigate two and three D-brane stack realizations of the Georgi-Glashow and the flipped SU(5) model and analyze them with respect to their Yukawa couplings. As pointed out in arXiv:0909.0271 the most economical Georgi-Glashow realization based on two stacks generically suffers from a disastrous large proton decay rate. We show that allowing for an additional U(1) D-brane stack this as well as other phenomenological problems can be resolved. We exemplify with globally consistent Georgi-Glashow models based on RCFT that these D-brane quivers can be indeed embedded in a global setting. These globally consistent realizations admit rigid O(1) instantons inducing the perturbatively missing coupling 10105^H. Finally we show that flipped SU(5) D-brane realizations even with multiple U(1) D-brane stacks are plagued by severe phenomenological drawbacks which generically cannot be overcome.Comment: 34 pages v2 minor correction

Minimal Anomalous U(1)' Extension of the MSSM

We study an extension of the MSSM by an anomalous abelian vector multiplet and a St\"uckelberg multiplet. The anomalies are cancelled by the Green-Schwarz mechanism and the addition of Chern-Simons terms. The advantage of this choice over the standard one is that it allows for arbitrary values of the quantum numbers of the extra U(1). As a first step towards the study of hadron annihilations producing four leptons in the final state (a clean signal which might be studied at LHC) we then compute the decays Z'\to Z_0 \g and $Z'\to Z_0 Z_0$. We find that the largest values of the decay rate is $\sim 10^{-4}$ GeV, while the expected number of events per year at LHC is at most of the order of 10.Comment: 45 pages, 8 eps figures, feynmf. Phenomenological section expanded. 2 plots and references adde

Symplectic structure of N=1 supergravity with anomalies and Chern-Simons terms

The general actions of matter-coupled N=1 supergravity have Peccei-Quinn terms that may violate gauge and supersymmetry invariance. In addition, N=1 supergravity with vector multiplets may also contain generalized Chern-Simons terms. These have often been neglected in the literature despite their importance for gauge and supersymmetry invariance. We clarify the interplay of Peccei-Quinn terms, generalized Chern-Simons terms and quantum anomalies in the context of N=1 supergravity and exhibit conditions that have to be satisfied for their mutual consistency. This extension of the previously known N=1 matter-coupled supergravity actions follows naturally from the embedding of the gauge group into the group of symplectic duality transformations. Our results regarding this extension provide the supersymmetric framework for studies of string compactifications with axionic shift symmetries, generalized Chern-Simons terms and quantum anomalies.Comment: 27 pages; v2: typos corrected; version to be published in Class.Quantum Gra

An automated process for inclusion of package dies and circuitry within a textile yarn

The integration of small electronic components into textile fabrics, without compromising the textile qualities such as flexibility and conformability, is necessary in ensuring wider adoption of electronic textiles. A solution is to use flexible, electronic yarns that incorporate electronic components within the fibers of the yarn. The production of these novel yarns was initially a craft skill, with inclusion of electronics within each section of yarn taking 60–90 minutes. A prototype, automated production process was developed to speed up the manufacturing process to 6 minutes. This paper describes the process, using machinery and methods from both electronics and textiles applications

Gauge Threshold Corrections for Local String Models

We study gauge threshold corrections for local brane models embedded in a large compact space. A large bulk volume gives important contributions to the Konishi and super-Weyl anomalies and the effective field theory analysis implies the unification scale should be enhanced in a model-independent way from M_s to R M_s. For local D3/D3 models this result is supported by the explicit string computations. In this case the scale R M_s comes from the necessity of global cancellation of RR tadpoles sourced by the local model. We also study D3/D7 models and discuss discrepancies with the effective field theory analysis. We comment on phenomenological implications for gauge coupling unification and for the GUT scale.Comment: 30 pages; v2: references added, minor typos correcte

Yukawa couplings and masses of non-chiral states for the Standard Model on D6-branes on T6/Z6'

The perturbative leading order open string three-point couplings for the Standard Model with hidden USp(6) on fractional D6-branes on T6/Z6' from arXiv:0806.3039 [hep-th], arXiv:0910.0843 [hep-th] are computed. Physical Yukawa couplings consisting of holomorphic Wilsonian superpotential terms times a non-holomorphic prefactor involving the corresponding classical open string Kaehler metrics are given, and mass terms for all non-chiral matter states are derived. The lepton Yukawa interactions are at leading order flavour diagonal, while the quark sector displays a more intricate pattern of mixings. While N=2 supersymmetric sectors acquire masses via only two D6-brane displacements - which also provide the hierarchies between up- and down-type Yukawas within one quark or lepton generation -, the remaining vector-like states receive masses via perturbative three-point couplings to some Standard Model singlet fields with vevs along flat directions. Couplings to the hidden sector and messengers for supersymmetry breaking are briefly discussed.Comment: 52 pages (including 8p. appendix); 5 figures; 14 tables; v2: discussion in section 4.1.3 extended, footnote 5 added, typos corrected, accepted by JHE