2553762
Boost-Invariant (2+1)-Dimensional Anisotropic Hydrodynamics
We present results of the application of the anisotropic hydrodynamics (aHydro) framework to (2+1)-dimensional boost-invariant systems. The necessary aHydro dynamical equations are derived by taking moments of the Boltzmann equation using a momentum-space anisotropic one-particle distribution function. We present a derivation of the necessary equations and then proceed to numerical solutions of the resulting partial differential equations using both realistic smooth Glauber initial conditions and fluctuating Monte Carlo Glauber initial conditions. For this purpose we have developed two numerical implementations: one that is based on straightforward integration of the resulting partial differential equations supplemented by a two-dimensional weighted Lax-Friedrichs smoothing in the case of fluctuating initial conditions and another that is based on the application of the Kurganov-Tadmor central scheme. For our final results we compute the collective flow of the matter via the laboratory-frame energy-momentum tensor eccentricity as a function of the assumed shear viscosity-to-entropy ratio, proper time, and impact parameter.
36601565
Next-to-eikonal corrections in the CGC: gluon production and spin asymmetries in pA collisions
A bstractWe present a new method to systematically include corrections to the eikonal approximation in the background field formalism. Specifically, we calculate the subleading, power-suppressed corrections due to the finite width of the target or the finite energy of the projectile. Such power-suppressed corrections involve Wilson lines decorated by gradients of the background field — thus related to the density - of the target. The method is of generic applicability. As a first example, we study single inclusive gluon production in pA collisions, and various related spin asymmetries, beyond the eikonal accuracy.
13868349
Dilepton production as a measure of QGP thermalization time
We discuss dilepton production from a quark–gluon plasma which has a time-dependent anisotropy in momentum space. A phenomenological model for the hard momentum scale, phard(τ) and the plasma anisotropy parameter, ξ(τ), is presented. The model interpolates between early-time 1 + 1 free streaming behavior (τ τiso) and late-time ideal 1 + 1 hydrodynamical behavior (τ τiso). Using this model, we find that the dilepton rate arising from electromagnetic annihilations of quarks in the kinematic range 3 <pT< 8 GeV is sensitive to the assumed isotropization time of the system, τiso. Therefore high-energy dilepton production can be used to probe the degree of momentum-space isotropy of a quark–gluon plasma produced in relativistic heavy-ion collisions and the time of onset of hydrodynamic expansion of the QGP.
121540832
A very forward luminosity monitor for the ALEPH detector at LEP
Abstract The design of a very small angle luminosity monitor for the ALEPH detector at LEP is described. The detector consists of four calorimeter modules made of alternating layers of tungsten and scintillators plus one layer of silicon strips for shower localization. Tests of the performance of the calorimeter and initial results obtained in LEP are also described.
111282417
The front-end system of the silicon drift detectors of ALICE
The ALICE experiment at CERN will have an inner tracker made of six barrels of semiconductor detectors. The two intermediate layers of the system will employ Silicon Drift Detectors (SDD) technology. The front-end electronics of the SDDs, which required the development of two full-custom integrated circuits, is reviewed in this paper. The design of the front-end hybrid is discussed and results obtained with full-size prototypes are presented.
11938821
Search for new phenomena in events with a monojet and large missing transverse momentum at the LHC using the ATLAS detector
We report preliminary results on a search for new phenomena in an event sample with monojets and large missing transverse momentum in the final state. The analysis uses 1.00 fb−1 of data collected in 2011 with the ATLAS detector [1]. Good agreement is observed between the number of events in data and the Standard Model predictions. The results are translated into improved limits on a model with Large Extra Dimensions.
122254977
Inclusive Search for Squark and Gluino Production at CDF
We present preliminary results on the search for squark and gluino production in proton-antiproton collisions at s = 1.96 TeV using 1.1 fb −1 of CDF Run II data. Events with multiple jets of hadrons and large missing transverse energy in the final state are studied within mSUGRA framework and assuming R-parity conservation. No excess with respect to Standard Model predictions is observed. In a mSUGRA scenario with A 0 = 0 , μ 0 and tan β = 5 , we exclude masses up to about 380 GeV / c 2 at 95% C.L. in the region where gluino and squark masses are similar.
119515666
Study of jet properties at the Tevatron
The Run II at the Tevatron will define a new level of precision for QCD studies in hadron collisions. Both collider experiments, CDF and D0, expect to collect up to 8 fb{sup -1} of data in this new run period. The increase in instantaneous luminosity, center-of-mass energy (from 1.8 TeV to 2 TeV) and the improved acceptance of the detectors will allow stringent tests of the Standard Model (SM) predictions in extended regions of jet transverse momentum, P{sub T}{sup jet}, and jet rapidity, Y{sup jet}. The hadronic final states in hadron-hadron collisions are characterized by the presence of soft contributions (the so-called underlying event) from initial-state gluon radiation and multiple parton interactions between remnants, in addition to the jets of hadrons originated by the hard interaction. A proper comparison with pQCD predictions at the parton level requires an adequate modeling of these soft contributions which become important at low P{sub T}{sup jet}. In this letter, a review of some of the most important QCD results from Run II is presented.