119663113
Ward Identity implied recursion relation at loop level
118607013
Permutation relations of generalized Yangian Invariants, unitarity cuts, and scattering amplitudes
A bstractWe find a permutation relation among the generalized Yangian Invariants — two Yangian Invariants with adjacent external lines exchanged are related by a simple kinematic factor — which is shown to be equivalent to U(1) decoupling and Bern-Carrasco-Johansson (BCJ) relation at the level of maximal helicity violating (MHV) amplitudes. We propose using unitarity cuts to study nonplanar amplitudes and to systematically reconstruct the integrands of nonplanar MHV amplitudes, up to a rational function which vanishes under all possible unitarity cuts. This is made possible with the newly found permutation relations by converting nonplanar on-shell diagrams into planar ones. As explicit examples the construction of one-loop double-trace MHV amplitudes of 4- and 5-point interactions are presented using on-shell diagrams. The kinematic factors and the resultant planar diagrams are carefully dealt with using the unitarity cut conditions. The first next-to-MHV amplitudes are addressed using generalized unitarity cuts. Their leading singularities can be identified as residues of the Grassmanian integrals. These examples also serve to demonstrate the power of the newly found relation of the generalized Yangian Invariants.
123645235
The AMS-02 electromagnetic calorimeter
Abstract The Electromagnetic Calorimeter (ECAL) of the AMS-02 experiment is a lead-scintillanting fibers sampling calorimeter characterized by high granularity that allows to image the longitudinal and lateral showers development, a key issue to provide high electron/hadron discrimination. The light collection system and the FE electronics are designed to let the calorimeter operate over a wide energy range from few GeV up to 1 TeV. A full-scale prototype of the e.m. calorimeter was tested at Cern in October 2001 using electrons and pions beams with energy ranging from 3 to 100 GeV. Effective sampling thickness, linearity and energy resolution were measured.
138378034
PERFORMANCES OF THE AMS-02 ELECTROMAGNETIC CALORIMETER
120878371
A reduced scale e.m. calorimeter prototype for the AMS-02 experiment
A reduced scale prototype of the Pb-SciFi sampling e.m. calorimeter for the AMS-02 experiment was tested at CERN SPS beam line X5 at energies from 5 to 250 GeV. The detector was equalized with minimum ionizing particles and calibrated with electron beams. Effective sampling thickness, linearity and energy resolution were measured (C) 2002 Elsevier Science B.V. All rights reserved.
97662282
Electromagnetic calorimeter for the AMS-02 experiment
The electromagnetic calorimeter (ECAL) of the AMS-02 experiment is a 3-dimensional sampling calorimeter, made of lead and scintillating fibers. The detector allows for a high granularity, with 18 samplings in the longitudinal direction, and 72 sampling in the lateral direction. The ECAL primary goal is to measure the energy of cosmic rays up to few TeV, however, thanks to the fine grained structure, it can also provide the separation of positrons from protons, in the GeV to TeV region. A direct measurement of high energy photons with accurate energy and direction determination can also be provided.
119188205
Initial Conditions with Flow from a McLerran Venugopalan model with Transverse Dynamics
Using a recursive solution of the Yang-Mills equation, we calculate analytic expressions for the gluon fields created in ultra-relativistic heavy ion collisions at small times τ. We have worked out explicit solutions for the fields and the energy momentum tensor up to 4th order in an expansion in τ. We generalize the McLerran-Venugopalan model to allow for a systematic treatment of averaged charge densities μ2 that vary as a function of transverse coordinates. This allows us to calculate radial, elliptic and directed flow of gluon fields. Our results can serve as initial conditions for hydrodynamic simulations of nuclear collisions that include initial flow.
123818688
Search for a Higgs-like boson decaying to two photons in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV
We present a search for the Standard Model (SM) Higgs boson decaying to two photons using the 9.6 fb-1 of p$$\bar{p}$$ collisions at √s = 1.96 TeV collected by the D0 detector at the Tevatron from July 2002 to September 2011. The data corresponds to the complete data-set in the RunII period of the Tevatron. This thesis employs a multivariate technique, boosted decision trees, to optimize the discrimination of signal from background. No significant excess of data above theoretical prediction is observed, so limits on the ratio of the production cross section times the branching ratio to the SM value are set at 95% confidence level as a function of hypothetical Higgs boson mass. The expected and observed limits on this ratio are 8.7 and 12.8 respectively at 125 GeV. We also interpret the data in the fermiophobic Higgs model. The result has reached a sensitivity of 114 GeV, and we set a lower limit on the fermiophobic Higgs mass of MHf > 113 GeV.
209930395
Extraction of the structure functions in tau -> 3 pi nu decay using Li model
The structure functions in the tau --> 3 pi nu decay are extracted using the model proposed by Li. The predictions of Li model are compared with KS ones and the data from OPAL experiment. It is found that predictions by the model for w(A)(Q(2)) are consistent with the data except for in the high energy region (Q(2) > 1.2 GeV2), and w(C), w(D), w(E) normalized to w(A) are in reasonable agreement with the experimental results. Correction factors to the Breit-Wigner distribution of a(1) and the Lagrangian of this decay are proposed to the model.
120081744
Study on The Property of tau Hadronic Decays
124197197
Structure functions in tau ---> 3 pi neutrino decay