LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM

We study the phenomenology of a supersymmetric left-right model, assuming minimal supergravity boundary conditions. Both left-right and (B-L) symmetries are broken at an energy scale close to, but significantly below the GUT scale. Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for superpotential and soft parameters complete at 2-loop order. At low energies lepton flavour violation (LFV) and small, but potentially measurable mass splittings in the charged scalar lepton sector appear, due to the RGE running. Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton mass splittings, occur not only in the left- but also in the right slepton sector. Especially, ratios of LFV slepton decays, such as Br(${\tilde\tau}_R \to \mu \chi^0_1$)/Br(${\tilde\tau}_L \to \mu \chi^0_1$) are sensitive to the ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts a polarization asymmetry of the outgoing positrons in the decay $\mu^+ \to e^+ \gamma$, A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$. Observation of any of these signals allows to distinguish this model from any of the three standard, pure (mSugra) seesaw setups.Comment: 43 pages, 17 figure

Hefty MSSM-like light Higgs in extended gauge models

It is well known that in the MSSM the lightest neutral Higgs h^0 must be, at the tree level, lighter than the Z boson and that the loop corrections shift this stringent upper bound up to about 130 GeV. Extending the MSSM gauge group in a suitable way, the new Higgs sector dynamics can push the tree-level mass of h^0 well above the tree-level MSSM limit if it couples to the new gauge sector. This effect is further pronounced at the loop level and h^0 masses in the 140 GeV ballpark can be reached easily. We exemplify this for a sample setting with a low-scale U(1)_R x U(1)_B-L gauge symmetry in which neutrino masses can be implemented via the inverse seesaw mechanism.Comment: 14 pages, 3 figures; references added, typos corrected; published versio

Right-handed Sneutrino Dark Matter in Supersymmetric B-L Model

We show that the lightest right-handed sneutrino in TeV scale supersymmetric B-L model with inverse seesaw mechanism is a viable candidate for cold dark matter. We find that it accounts for the observed dark matter relic abundance in a wide range of parameter space. The spin-independent cross section of B-L right-handed sneutrino is consistent with the recent results CDMS II and XENON experiments and it is detectable in future direct detection experiments. Although the B-L right-handed sneutrinos annihilate into leptons, the PAMELA results can not be explained in this model unless a huge boost factor is considered. Also the muon flux generated by B-L right-handed sneutrino in the galactic center is smaller than Super-Kamiokande's upper bound.Comment: 16 pages, 7 figures; version accepted for publication in Journal of High Energy Physic

Heterobimetallic μ‑Oxido Complexes Containing Discrete V^V–O–M^III (M = Mn, Fe) Cores: Targeted Synthesis, Structural Characterization, and Redox Studies

Heterobimetallic compounds [L′OV^V(μ-O)­M^IIIL]_<i>n</i> (<i>n</i> = 1, M = Mn, <b>1</b>–<b>5</b>; <i>n</i> = 2, M = Fe, <b>6</b> and <b>7</b>) containing a discrete unsupported V^V–O–M^III bridge have been synthesized through a targeted synthesis route. In the V–O–Mn-type complexes, the vanadium­(V) centers have a square-pyramidal geometry, completed by a dithiocarbazate-based tridentate Schiff-base ligand (H₂L′), while the manganese­(III) centers have either a square-pyramidal (<b>1</b> and <b>3</b>) or an octahedral (<b>2</b> and <b>5</b>) geometry, made up of a Salen-type tetradentate ligand (H₂L) as established by X-ray diffraction analysis. The V–O–Mn bridge angle in these compounds varies systematically from 155.3° to 128.1° in going from <b>1</b> to <b>5</b> while the corresponding dihedral angle between the basal planes around the metal centers changes from 86.82° to 20.92°, respectively. The V–O–Fe-type complexes (<b>6</b> and <b>7</b>) are tetranuclear, in which the two dinuclear V­(μ-O)­Fe units are connected together by apical iron­(III)–aryl oxide interactions, forming a dimeric structure with a pair of Fe–O–Fe bridges. The X-ray data also confirm the VO → M canonical form to contribute predominantly on the overall V–O–M bridge structure. The molecules in solution also retain their heterobinuclear composition, as established by electrospray ionization mass spectrometry and ⁵¹V NMR spectroscopy. Electrochemically, these complexes are quite interesting; the manganese­(III) complexes (<b>1</b>–<b>5</b>) display three successive reductions (processes I–III), each with a monoelectron stoichiometry. Process I is due to a Mn^III/Mn^II reduction (<i>E</i>_1/2 ranges between −0.32 and −0.05 V), process II is a ligand-based reduction, and process III (<i>E</i>_1/2 = ∼1.80 V) owes its origin to a V^VO/V^IVO reduction; all potentials are versus Ag/AgCl. The iron­(III) compounds (<b>6</b> and <b>7</b>), on the other hand, show at least four irreversible processes, appearing at <i>E</i>_pc = −0.20, −1.0, −1.58, and −1.68 V in compound <b>6</b> (processes IV–VII), together with a reversible process (process VIII) at <i>E</i>_1/2 = −1.80 V (Δ<i>E</i>_p = 80 mV). While the first two of these are due to Fe^III/Fe^II reductions at the two iron­(III) centers of these tetranuclear cores, the reversible reduction at a more negative potential (ca. −1.80 V) is due to a V^VO/V^IVO-based electron transfer

Homo- and Heterometal Complexes of Oxido–Metal Ions with a Triangular [V(V)O–MO–V(V)O] [M = V(IV) and Re(V)] Core: Reporting Mixed-Oxidation Oxido–Vanadium(V/IV/V) Compounds with Valence Trapped Structures

A new family of trinuclear homo- and heterometal complexes with a triangular [V­(V)­O–MO–V­(V)­O] (M = V­(IV), <b>1</b> and <b>2</b>; Re­(V), <b>3</b>] all-oxido–metal core have been synthesized following a single-pot protocol using compartmental Schiff-base ligands, <i>N</i>,<i>N</i>′-bis­(3-hydroxysalicylidene)-diiminoalkanes/arene (H₄L¹–H₄L³). The upper compartment of these ligands with N₂O₂ donor combination (Salen-type) contains either a V­(IV) or a Re­(V) center, while the lower compartment with O₄ donor set accommodates two V­(V) centers, stabilized by a terminal and a couple of bridging methoxido ligands. The compounds have been characterized by single-crystal X-ray diffraction analyses, which reveal octahedral geometry for all three metal centers in <b>1</b>–<b>3</b>. Compound <b>1</b> crystallizes in a monoclinic space group <i>P</i>2₁/<i>c</i>, while both <b>2</b> and <b>3</b> have more symmetric structures with orthorhombic space group <i>Pnma</i> that renders the vanadium­(V) centers in these compounds exactly identical. In DMF solution, compound <b>1</b> displays an 8-line EPR at room temperature with ⟨<i>g</i>⟩ and ⟨<i>A</i>⟩ values of 1.972 and 86.61 × 10^–4 cm^–1, respectively. High-resolution X-ray photoelectron spectrum (XPS) of this compound shows a couple of bands at 515.14 and 522.14 eV due to vanadium 2p_3/2 and 2p_1/2 electrons in the oxidation states +5 and +4, respectively. All of these, together with bond valence sum (BVS) calculation, confirm the trapped-valence nature of mixed-oxidation in compounds <b>1</b> and <b>2</b>. Electrochemically, compound <b>1</b> undergoes two one-electron oxidations at <i>E</i> _1/2 = 0.52 and 0.83 V vs Ag/AgCl reference. While the former is due to a metal-based V­(IV/V) oxidation, the latter one at higher potential is most likely due to a ligand-based process involving one of the catecholate centers. A larger cavity size in the upper compartment of the ligand H₄L³ is spacious enough to accommodate Re­(V) with larger size to generate a rare type of all-oxido heterotrimetallic compound (<b>3</b>) as established by X-ray crystallography