119309124
Ramond-Ramond cohomology and O(D, D) T-duality
A bstractIn the name of supersymmetric double field theory, superstring effective actions can be reformulated into simple forms. They feature a pair of vielbeins corresponding to the same spacetime metric, and hence enjoy double local Lorentz symmetries. In a manifestly covariant manner — with regard to O(D, D) T-duality, diffeomorphism, B-field gauge symmetry and the pair of local Lorentz symmetries — we incorporate R-R potentials into double field theory. We take them as a single object which is in a bi-fundamental spinorial representation of the double Lorentz groups. We identify cohomological structure relevant to the field strength. A priori, the R-R sector as well as all the fermions are O(D, D) singlet. Yet, gauge fixing the two vielbeins equal to each other modifies the O(D, D) transformation rule to call for a compensating local Lorentz rotation, such that the R-R potential may turn into an O(D, D) spinor and T-duality can flip the chirality exchanging type IIA and IIB supergravities.
15885764
Three-algebra for supermembrane and two-algebra for superstring
While string or Yang-Mills theories are based on Lie algebra or two-algebra structure, recent studies indicate that -theory may require a one higher, three-algebra structure. Here we construct a covariant action for a supermembrane in eleven dimensions, which is invariant under global supersymmetry, local fermionic symmetry and worldvolume diffeomorphism. Our action is classically on-shell equivalent to the celebrated Bergshoeff-Sezgin-Townsend action. However, the novelty is that we spell the action genuinely in terms of Nambu three-brackets: All the derivatives appear through Nambu brackets and hence it manifests the three-algebra structure. Further the double dimensional reduction of our action gives straightforwardly to a type IIA string action featuring two-algebra. Applying the same method, we also construct a covariant action for type IIB superstring, leading directly to the IKKT matrix model.
15319887
Singlet fermionic dark matter as a natural higgs portal model
We propose a renormalizable model of a fermionic dark matter by introducing a gauge singlet Dirac fermion and a real singlet scalar. The bridges between the singlet sector and the standard model sector are only the singlet scalar interaction terms with the standard model Higgs field. The singlet fermion couples to the standard model particles through the mixing between the standard model Higgs and singlet scalar and is naturally a weakly interacting massive particle (WIMP). The measured relic abundance can be explained by the singlet fermionic dark matter as the WIMP within this model. Collider implication of the singlet fermionic dark matter is also discussed. Predicted is the elastic scattering cross section of the singlet fermion into target nuclei for a direct detection of the dark matter. Search of the direct detection of the dark matter provides severe constraints on the parameters of our model.
118339519
5-dim superconformal index with enhanced En global symmetry
A bstractThe five-dimensional $ \mathcal{N}=1 $ supersymmetric gauge theory with Sp(N) gauge group and SO(2Nf) flavor symmetry describes the physics on N D4-branes with Nf D8-branes on top of a single O8 orientifold plane in Type I′ theory. This theory is known to be superconformal at the strong coupling limit with the enhanced global symmetry $ {E_{{N_f +1}}} $ for Nf ≤ 7. In this work we calculate the superconformal index on S1 × S4 for the Sp(1) gauge theory by the localization method and confirm such enhancement of the global symmetry at the superconformal limit for Nf ≤ 5 to a few leading orders in the chemical potential. Both perturbative and (anti)instanton contributions are present in this calculation. For Nf = 6, 7 cases some issues related the pole structure of the instanton calculation could not be resolved and here we could provide only some suggestive answer for the leading contributions to the index. For the Sp(N) case, similar issues related to the pole structure appear.
118491865
The CDF dijet excess and Z'cs coupled to the second generation quarks
Recently the CDF collaboration has reported the excess in the dijet invariant-mass distribution of the Wjj events, corresponding to a significance of 3.2 standard deviations. Considering the lack of similar excesses in the $\gamma jj$ and $Z jj$ events yet, we propose a new Z' model: Z' couples only to the second generation quarks. Single production of $\zsc$ as well as associated production with $W,\gamma, Z$ are mainly from the sea quarks. Only $W Z'$ production has additional contribution from one valence quark and one sea quark, which is allowed by CKM mixing. We found that if the new gauge coupling is large enough, marginally permitted by perturbativity, this new model can explain the observed CDF $Wjj$ anomaly as well as the lack of $\gm jj$ and $Z jj$ anomalies. Vanishing coupling of Z'-b-b protects this model from the constraint of p pbar ->WH -> l\nu b \bar{b}.
14742265
APPROXIMATE FLAVOR SYMMETRIES AND SEESAW MECHANISM
We study the approximate flavor symmetries imposed on the lepton sector assuming seesaw mechanism as the neutrino mass structure. We apply the symmetry to various neutrino phenomenologies and obtain constraints on neutrino masses and mixings.
15160462
SU(2) calorons and magnetic monopoles
We investigate the self-dual Yang-Mills gauge configurations on R{sup 3}{times}S{sup 1} when the gauge symmetry SU(2) is broken to U(1) by the Wilson loop. We construct the explicit field configuration for a single instanton by the Nahm method and show that an instanton is composed of two self-dual monopoles of opposite magnetic charge. We normalize the moduli space metric of an instanton and study various limits of the field configuration and its moduli space metric. {copyright} {ital 1998} {ital The American Physical Society}