Goldstino and sgoldstino in microscopic models and the constrained superfields formalism

We examine the exact relation between the superconformal symmetry breaking chiral superfield (X) and the goldstino superfield in microscopic models of an arbitrary Kahler potential (K) and in the presence of matter fields. We investigate the decoupling of the massive sgoldstino and scalar matter fields and the offshell/onshell-SUSY expressions of their superfields in terms of the fermions composites. For general K of two superfields, we study the properties of the superfield X after integrating out these scalar fields, to show that in the infrared it satisfies (offshell) the condition X³=0 and X²≠0. We then compare our results to those of the well-known method of constrained superfields discussed in the literature, based on the conjecture X²=0. Our results can be used in applications, to couple offshell the (s)goldstino fields to realistic models such as the MSSM.     

Phenomenology of TeV little string theory from holography

We study the graviton phenomenology of TeV little string theory by exploiting its holographic gravity dual five-dimensional theory. This dual corresponds to a linear dilaton background with a large bulk that constrains the standard model fields on the boundary of space. The linear dilaton geometry produces a unique Kaluza-Klein graviton spectrum that exhibits a ~TeV mass gap followed by a near continuum of narrow resonances that are separated from each other by only ~30 GeV. Resonant production of these particles at the LHC is the signature of this framework that distinguishes it from large extra dimensions, where the Kaluza-Klein states are almost a continuum with no mass gap, and warped models, where the states are separated by a TeV.     

Anomaly driven signatures of new invisible physics at the Large Hadron Collider

Many extensions of the Standard Model (SM) predict new neutral vector bosons at energies accessible by the Large Hadron Collider (LHC). We study an extension of the SM with new chiral fermions subject to non-trivial anomaly cancellations. If the new fermions have SM charges, but are too heavy to be created at LHC, and the SM fermions are not charged under the extra gauge field, one would expect that this new sector remains completely invisible at LHC. We show, however, that a non-trivial anomaly cancellation between the new heavy fermions may give rise to observable effects in the gauge boson sector that can be seen at the LHC and distinguished from backgrounds.     

On cyclic covers of the projective line

We construct configuration spaces for cyclic covers of the projective line that admit extra automorphisms and we describe the locus of curves with given automorphism group. As an application we provide examples of arbitrary high genus that are defined over their field of moduli and are not hyperelliptic.     

Brane singularities with mixtures in the bulk

By extending previous analysis of the authors, a systematic study of the singularity structure and possible asymptotic behaviors of five‐dimensional braneworld solutions is performed in the case where the bulk is a mixture of an analog of perfect fluid (with a density and pressure depending on the extra coordinate) and a massless scalar field. The two bulk components interact by exchanging energy so that the total energy is conserved. In a particular range of the interaction parameters, we find flat brane general solutions avoiding the singularity at finite distance from the brane, in the same region of the equation of state constant parameter γ = P/ρ that we found previously in the absence of the bulk scalar field (‐1 < γ < ‐1/2).     

Reactivity of di‐iodine toward thiol: Desulfuration reaction of 5‐nitro‐2‐mercapto‐benzimidazole upon reaction with di‐iodine

The reaction of 2‐mercapto‐benzoic acid (H₂MBA), 2‐mercato‐nicotinic acid (H₂MNA), and 2‐mercapto‐pyrimidine (PMTH) with a twofold molar amount of di‐iodine (I₂) results in the isolation of crystals of the neutral disulfides of formulae: {(HMBA)₂·1/2(CH₃CN)} ( 1 ), {(HMNA)₂·(H₂O)} ( 2 ), and (PMT)₂ ( 3 ), respectively, when dichloromethane/acetonitrile/methanol ( 1 ) or dichloromethane ( 2,3 ) were used as solvents. The reaction of di‐iodine with thethiol PMTH and 2‐mercapto‐benzothiazole (MBZTH) yields the disulfide (PMT)₂ ( 3 ), and the di‐iodine adduct of formula {[MBZTH‐I₂]·[MBZTH]₂} ( 4 ), respectively. The reaction of di‐iodine with 5‐nitro‐2‐mercapto‐benzimidazole (O₂N‐MBZIMH) ( 5 ) in the presence of ferric trichloride hydrate (FeCl₃·6H₂O), in a 6:3:1 (I₂:thiol:FeCl₃·6H₂O) molar ratio, results in cocrystal ( 6 ), which contain the desulfurated hydroxyl derivative O₂N‐BZIMOH ( 6a ) and unreacted O₂N‐MBZIMH ( 6b ) in a 3:1 molar ratio. The compounds were characterized by elemental analysis, FT‐IR, and ¹H NMR spectroscopy. The crystal structures of compounds 1 – 6 were also determined by X‐ray crystallography. Cyclic voltammetry measurements showed that thiols with low oxidation potentials (< 1.0 V) mainly form disulfides upon a reaction with di‐iodine, whereas those with higher oxidation potential form charge transfer (CT), resulting in desulfurated products, MBZIMH. However, in the case of O₂N‐MBZIMH a desulfurated species was isolated. The formation of the final product also requires the presence of FeCl₃. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:498–511, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21042     

Vortex lattice transitions in YNi2B2C

We have performed extensive small-angle neutron scattering (SANS) diffraction studies of the vortex lattice in single crystal YNi₂B₂C for B‖c. High-resolution SANS, combined with a field-oscillation vortex lattice preparation technique, allows us to separate Bragg scattered intensities from two orthogonal domains and accurately determine the unit cell angle, β. The data suggest that upon increasing field there is a finite transition width where both low- and high-field distorted hexagonal vortex lattice phases, mutually rotated by 45°, coexist. The smooth variation of diffracted intensity from each phase through the transition corresponds to a redistribution of populations between the two types of domains.     

Split supersymmetry in brane models

Type-I string theory in the presence of internal magnetic fields provides a concrete realization of split supersymmetry. To lowest order, gauginos are massless while squarks and sleptons are superheavy. For weak magnetic fields, the correct Standard Model spectrum guarantees gauge coupling unification with sin² ϑW=3/8 at the compactification scale of M _GUT ⋍ 2 × 10¹⁶ GeV. I discuss mechanisms for generating gaugino and higgsino masses at the TeV scale, as well as generalizations to models with split extended supersymmetry in the gauge sector.