Search results for "Transverse plane"
showing 10 items of 285 documents
Inclusive electron scattering off 4He
2007
Inclusive electron scattering off 4He is investigated for low and medium energy and momentum transfers. The final state interaction, given by the simple semirealistic Malfliet-Tjon potential, is treated rigorously applying the Lorentz Integral Transform (LIT) method. Besides the nonrelativistic one-body current a consistent meson exchange current is constructed and implemented. Results are presented for both longitudinal and transverse response functions at various momentum transfers. Good agreement with experimental data is found for the longitudinal response function, while some strength is missing in the transverse response function on the low-energy side of the quasi-elastic peak.
Normal and transverse single tau polarization at the Z-peak
1994
Abstract We study normal (to the collision plane) and transverse (within the collision plane) single-τ polarization in τ pairs produced in e + e − unpolarized collisions at the Z -resonance. The transverse polarization component is sensitive to the anomalous weak-magnetic moment, whereas the normal polarization component is sensitive to a CP-violating weak-electric dipole moment. We show how these components of the single τ polarization are accessible from the angular distribution of its decay products. We define a CP violating asymmetry of the τ decay products which, with 10 7 Z ′s produced, provides a sensitivity of 2.3 × 10 −18 e ·cm for the weak-electric dipole moment.
Transverse Spectra of Hadrons in Central $AA$ Collisions at RHIC and LHC from pQCD+Saturation+Hydrodynamics and from pQCD+Energy Losses
2005
We study the transverse spectra of hadrons in nearly central $AA$ collisions at RHIC and LHC in a broad transverse momentum range Low-$p_T$ spectra are calculated by using boost-invariant hydrodynamics with initial energy and net-baryon densities from the EKRT pQCD+saturation model. High-$p_T$ spectra are obtained from pQCD jet calculation including the energy loss of the parton in the matter prior to its fragmentation to final hadrons.
Search for squarks and gluinos in events with jets and missing transverse energy in pp¯ collisions at s=1.96 TeV
2006
Abstract The results of a search for squarks and gluinos using data from p p ¯ collisions recorded at a center-of-mass energy of 1.96 TeV by the DO detector at the Fermilab Tevatron Collider are reported. The topologies analyzed consist of acoplanar-jet and multijet events with large missing transverse energy. No evidence for the production of squarks or gluinos was found in a data sample of 310 pb−1. Lower limits of 325 and 241 GeV were derived at the 95% C.L. on the squark and gluino masses, respectively, within the framework of minimal supergravity with tan β = 3 , A 0 = 0 , and μ 0 .
Non-zero chemical potential and the shape of the pT-distribution of hadrons in heavy-ion collisions
1990
Abstract The pT-spectra of negative particles from 200 GeV/nucleon O + Au and S + S collisions, measured at CERN by the NA35 collaboration, are fitted by a thermal distribution of massive pions which are strongly out of chemcial equilibrium. Both sets of data are consistent with the same values of temperature and chemical potential, T ≈ 165 MeV and μ ≈ 120 MeV. The low pT behaviour of the measured spectra seems to indicate that the transverse flow in these collisions is not strong.
Many-body approach to the inclusive (e,e ') reaction from the quasielastic to the Delta excitation region
1997
We have performed a many body calculation of the inclusive (e,e') cross section which runs over the three traditional regions at intermediate energies: the quasielastic peak, the dip region and the delta region. The longitudinal and transverse response functions in the quasielastic peak have also been evaluated. Traditional effects like polarization, meson exchange currents, final state interaction and delta renormalization in the nuclear medium have been included. Meson exchange currents are generated from a model of pion electroproduction on the nucleon which reproduces accurately the experimental data. The inclusive cross section accounts for 1N,2N,3N mechanisms of virtual photon absorpt…
Transverse momentum of j/$\psi$ produced in oxygen-uranium collisions at 200 GeV per nucleon
1990
Abstract The study of the J ψ transverse momentum distribution in oxygen-uranium reactions at 200 GeV/nucleon shows that 〈PT〉 and 〈PT2〉 increase with the transverse energy of the reaction. Muon pairs in the mass continuum do not exhibit the same behaviour. The comparison of the J ψ production rates in central and peripheral collisions shows a significant diminution for low PT central events.
Hydrodynamic simulation of elliptic flow
1999
We use a hydrodynamic model to study the space-time evolution transverse to the beam direction in ultrarelativistic heavy-ion collisions with nonzero impact parameters. We focus on the influence of early pressure on the development of radial and elliptic flow. We show that at high energies elliptic flow is generated only during the initial stages of the expansion while radial flow continues to grow until freeze-out. Quantitative comparisons with SPS data from semiperipheral Pb+Pb collisions suggest the applicability of hydrodynamical concepts already $\approx$ 1 fm/c after impact.
From quark-gluon plasma to hadron spectra
2001
Results on initial transverse energy production based on NLO perturbative QCD calculation with final state saturation of produced minijets are used to fix the initial energy density of produced matter. Assuming rapid thermalization, this provides the initial conditions for a hydrodynamic description of the expansion of final matter. Given a prescription of the the decoupling of particles from the thermal system to free particles, final transverse spectra of hadrons and integrated quantities like multiplicity and transverse energy can be calculated in the central rapidity region. Results are reported and compared with measurements.
Effects of partial thermalization on HBT interferometry
2009
Hydrodynamical models have generally failed to describe interferometry radii measured at RHIC. In order to investigate this ``HBT puzzle'', we carry out a systematic study of HBT radii in ultrarelativistic heavy-ion collisions within a two-dimensional transport model. We compute the transverse radii $R_o$ and $R_s$ as functions of $p_t$ for various values of the Knudsen number, which measures the degree of thermalization in the system. For realistic values of the Knudsen number estimated from $v_2$ data, we obtain $R_o/R_s \simeq 1.2$, much closer to data than standard hydrodynamical results. Femtoscopic observables vary little with the degree of thermalization. Azimuthal oscillations of th…