Search for large extra dimensions via single photon plus missing energy final states at sqrt s = 1.96 TeV.
We report on a search for large extra dimensions in a data sample of approximately 1 fb(-1) of pp[over] collisions at sqrt s=1.96 TeV. We investigate Kaluza-Klein graviton production with a photon and missing transverse energy in the final state. At the 95% C.L. we set limits on the fundamental mass scale M(D) from 884 to 778 GeV for two to eight extra dimensions.

title: Jet energy scale determination in the D0 experiment
abstract: The calibration of jet energy measured in the DO detector is presented, based on p (p) over bar collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider, jet energies are measured using a sampling calorimeter composed of uranium and liquid argon as the passive and active media, respectively. This paper describes the energy calibration of jets performed with gamma+jet, Z+jet and dilet events, with jet transverse momentum p(T) > 6 GeV and pseudorapidity range vertical bar eta vertical bar < 3.6, The corrections are measured separately for data and simulation, achieving a precision of 1.4-1.8% for jets in the central part of the calorimeter ancl up to 3.5% for the jets with pseudorapidity vertical bar eta vertical bar = 3.0. Specific corrections are extracted to enhance the description of jet energy in simulation and in particular of the effects due to the flavor of the parton originating the jet, correcting biases up to 3-4% in jets with low PT originating from gluons and up to 6-8% in jets from b quarks.

title: Precision measurement of the top quark mass in lepton + jets final States.
abstract: We measure the mass of the top quark in lepton+jets final states using the full sample of pp collision data collected by the D0 experiment in Run II of the Fermilab Tevatron Collider at sqrt[s] = 1.96 TeV, corresponding to 9.7 fb(-1) of integrated luminosity. We use a matrix element technique that calculates the probabilities for each event to result from tt production or background. The overall jet energy scale is constrained in situ by the mass of the W boson. We measure m(t) = 174.98 ± 0.76 GeV. This constitutes the most precise single measurement of the top-quark mass.

title: Measurement of angular correlations of jets at s=1.96 TeV and determination of the strong coupling at high momentum transfers
abstract: We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance Delta-R in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of Delta-R and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in pp-bar collisions at sqrt(s)=1.96 The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50-400 GeV.

title: Search for long-lived particles decaying into electron or photon pairs with the D0 detector.
abstract: In this Letter we report on a search for long-lived particles that decay into final states with two electrons or photons. Such long-lived particles arise in a variety of theoretical models, such as hidden valleys and supersymmetry with gauge-mediated breaking. By precisely reconstructing the direction of the electromagnetic shower we are able to probe much longer lifetimes than previously explored. We see no evidence of the existence of such long-lived particles and interpret this search as a quasi model-independent limit on their production cross section, as well as a limit on a long-lived fourth generation quark.

title: Observation and properties of the orbitally excited B_(s2)(*) meson.
abstract: We report the direct observation of the excited L=1 state B_(s2)(*) in fully reconstructed decays to B+K-. The mass of the B_(s2)(*) meson is measured to be 5839.6+/-1.1(stat)+/-0.7(syst) MeV/c(2), and its production rate relative to the B+ meson is measured to be [1.15+/-0.23(stat)+/-0.13(syst)]%.

title: Double quiver gauge theory and nearly Kähler flux compactifications
abstract: A bstractWe consider G-equivariant dimensional reduction of Yang-Mills theory with torsion on manifolds of the form M × G/H where M is a smooth manifold, and G/H is a compact six-dimensional homogeneous space provided with a never integrable almost complex structure and a family of SU(3)-structures which includes a nearly Kähler structure. We establish an equivalence between G-equivariant pseudo-holomorphic vector bundles on M × G/H and new quiver bundles on M associated to the double of a quiver Q, determined by the SU(3)-structure, with relations ensuring the absence of oriented cycles in Q. When M = $ {{\mathbb{R}}^{{2}}} $, we describe an equivalence between G-invariant solutions of Spin(7)-instanton equations on M × G/H and solutions of new quiver vortex equations on M . It is shown that generic invariant Spin(7)-instanton configurations correspond to quivers Q that contain non-trivial oriented cycles.

title: Hyperbolic strings, bosonized ghosts, and fermions

title: Torsion-induced gauge field doubling in Kaluza-Klein theory
abstract: Torsion in Kaluza-Klein theory is considered. It is shown that a part of the components of the torsion tensor can be identified with the components of gauge fields different from the gauge fields of the Kaluza-Klein theory, while the other part can be identified with the field strength tensor of these gauge fields. The gauge fields introduced this way acquire a geometrically induced mass. It is shown that the torsion in the internal space allows to generate any a priori given mass in Kaluza-Klein theory.

title: Sigma models with N=8 supersymmetries in 2+1 and 1+1 dimensions
abstract: We introduce an N = 8 supersymmetric extension of the Bogomolny-type model for Yang–Mills–Higgs fields in 2 + 1 dimensions related with twistor string theory. It is shown that this model is equivalent to an N = 8 supersymmetric U ( n ) chiral model in 2 + 1 dimensions with a Wess–Zumino–Witten-type term. Further reduction to 1 + 1 dimensions yields N = ( 8 , 8 ) supersymmetric extensions of the standard U ( n ) chiral model and Grassmannian sigma models.

title: On spontaneous compactification of superstrings with torsion
abstract: We consider the spontaneous compactification of the field-theory limit of superstrings with a nonvanishing antisymmetric tensor H/sub M//sub N//sub P/. The existence of a class of solutions with internal spaces of constant negative curvature and vanishing cosmological constant is proved. Compactification to Ricci-flat spaces (in particular, to Calabi--Yau manifolds) is realized in the limit H/sub M//sub N//sub P/..-->..0.