118565086
Stringy origin of Tevatron Wjj anomaly
Abstract The invariant mass distribution of dijets produced in association with W bosons, recently observed by the CDF Collaboration at Tevatron, reveals an excess in the dijet mass range 120 – 160 GeV / c 2 , 3σ beyond Standard Model expectations. We show that such an excess is a generic feature of low mass string theory, due to the production and decay of a leptophobic Z ′ , a singlet partner of SU ( 3 ) gluons coupled primarily to the U ( 1 ) baryon number. In this framework, U ( 1 ) and SU ( 3 ) appear as subgroups of U ( 3 ) associated with open strings ending on a stack of 3 D-branes. In addition, a minimal model contains two other stacks to accommodate the electro-weak SU ( 2 ) ⊂ U ( 2 ) and the hypercharge U ( 1 ) . Of the three U ( 1 ) gauge bosons, the two heavy Z ′ and Z ″ receive masses through the Green–Schwarz mechanism. For a given Z ′ mass, the model is quite constrained. Fine tuning three of its free parameters is just sufficient to simultaneously ensure: a small Z – Z ′ mixing in accord with the stringent LEP data on the Z mass; very small (less than 1%) branching ratio into leptons; and a large hierarchy between Z ″ and Z ′ masses. The heavier neutral gauge boson Z ″ is within the reach of LHC.
119056773
THE MYSTERIOUS ULTRAHIGH ENERGY COSMIC RAY CLUSTERING
We examine the correlation between compact radio quasars (redshifts in the range z=0.3–2.2) and the arrival direction of ultrahigh energy cosmic rays forming clusters. Our Monte Carlo simulation reveals a statistically significant correlation on the AGASA sample: the chance probability of this effect being less than 1%. The implications of this result on the origin of ultrahigh energy cosmic rays are discussed.
121355086
Estimates for the probability of detecting neutral heavy leptons in hadron-initiated interactions
A consideration of two mechanisms for the production of neutral heavy leptons (${L}^{0}$'s) in hadron-initiated interactions lead to an estimate of ${10}^{\ensuremath{-}39}$ ${\mathrm{cm}}^{2}$ for the cross section per nucleon for observing the trimuons associated with the production of $\ensuremath{\mu}$-coupled ${L}^{0}$'s. This is well below the estimated background due to the production of a pair of ${\ensuremath{\rho}}^{0}$'s which decay into $\ensuremath{\mu}$ pairs.
120429995
PREDICTIONS FOR INCLUSIVE REACTIONS BASED ON A PARTON STRUCTURE OF HADRONS.
Abstract It is proposed that the asymptotic single-particle distributions f ( x )= x (d σ /d x ) in inclusive reactions should reflect the limiting longitudinal momentum distribution, ∼ νW 2 ( x ), of the hypothetical partons constituting a hadron. It is further argued that f ( x ) becomes, proportional to νW 2 ( x ) as x → 1. Predictions are then made for a large class of inclusive reactions based on our knowledge of νW 2 ( x ) from electroproduction data. For some of these (such as pp → π ± X), in which the predictions differ markedly from the Regge ones, present experiments distinctly favor ours.
10475979
Primordial Fluctuations from Gaugino Condensation
I present a model for inflation based on the gaugino-dilaton dynamics of supersymmetry breaking. The inflaton is the dimension–1 scalar field φ related to the gaugino condensate via λT λ = φ. Recent work in this area is used to obtain two significant results: (1) Scalar density fluctuations at second horizon crossing are generated on scale λ with amplitude
13042203
Extensive air showers with TeV scale quantum gravity
One of the possible consequences of the existence of extra degrees of freedom beyond the electroweak scale is the increase of neutrino-nucleon cross sections ({sigma}{sub {nu}N}) beyond standard model predictions. At ultrahigh energies this may allow the existence of neutrino-initiated extensive air showers. In this paper, we examine the most relevant observables of such showers. Our analysis indicates that the future Pierre Auger Observatory could be potentially powerful in probing models with large compact dimensions.
121567945
An optical model consistency condition between the regeneration phase and the real parts of the KON forward scattering amplitudes
Abstract Using just the magnitude of the regeneration amplitude we show that both the regeneration phase, ϕ r , and the sum of the ratios of the real to imaginary parts of the K O N forward scattering amplitudes, γ pn , can be determined for nuclei with zero or moderate neutron excess. We find: ϕ r = (43.5 ± 2.5) o ; γ pn = −0.73 ± 0.1 + 1.7 γ pn 〈 2.7 GeV /c 〉 = −0.65 ± 0.07 + 1.6 γ pn 〈 4.5 GeV /c 〉 , where γ pn is corresponding quantity for K O N scattering. Applications to regeneration in hydrogen and the ϕ-meson are discussed.
118297532
A Study of hadronic final states produced in association with high pT jets and high - mass dimuons