1096657
Modelling light-cone distribution amplitudes from non-relativistic bound states
We calculate light-cone distribution amplitudes for non-relativistic bound states, including radiative corrections from relativistic gluon exchange to first order in the strong coupling constant. We distinguish between bound states of quarks with equal (or similar) mass, m1 ~ m2, and between bound states where the quark masses are hierarchical, m1 >> m2. For both cases we calculate the distribution amplitudes at the non-relativistic scale and discuss the renormalization-group evolution for the leading-twist and 2-particle distributions. Our results apply to hard exclusive reactions with non-relativistic bound states in the QCD factorization approach like, for instance, Bc → ηclν or e+e− → J/ψηc. They also serve as a toy model for light-cone distribution amplitudes of light mesons or heavy B and D mesons, for which certain model-independent properties can be derived. In particular, we calculate the anomalous dimension for the B meson distribution amplitude B−(ω) in the Wandzura-Wilczek approximation and derive the according solution of the evolution equation at leading logarithmic accuracy.
56450914
NNLO corrections to semileptonic and hadronic B decays
We review recent progress in the perturbative calculations for semileptonic and hadronic B meson decays with an emphasis on the phenomenological implications of the next-to-next-to-leading order (NNLO) corrections. Specifically, we consider CP-averaged branching ratios of tree-dominated B -> pi pi/pi rho/rho rho decays and the inclusive determination of |V_ub| from B -> X_u l nu.
118509342
Master integrals for the two-loop penguin contribution in non-leptonic B-decays
A bstractWe compute the master integrals that arise in the calculation of the leading penguin amplitudes in non-leptonic B-decays at two-loop order. The application of differential equations in a canonical basis enables us to give analytic results for all master integrals in terms of iterated integrals with rational weight functions. It is the first application of this method to the case of two different internal masses.
14116539
NNLO corrections to inclusive semileptonic B decays in the shape-function region
Abstract We compute 2-loop QCD corrections to the hard coefficient functions which arise in the factorization formula for B → X u l ν decays in the shape-function region. Our calculation provides the last missing piece required for a NNLO analysis of inclusive semileptonic B decays, which may significantly reduce the theoretical uncertainty in the extraction of the CKM matrix element | V u b | . Among the technical aspects, we find that the 2-loop hard coefficient functions are free of infrared singularities as predicted by the factorization framework. We perform a brief numerical analysis of the NNLO corrections and include a discussion on charm mass effects.
119143806
Higher order QCD corrections in exclusive charmless B decays
We discuss exclusive charmless B decays within the Standard Model of particle physics. In particular we compute part of the NNLO corrections for hadronic two-body decays in the framework of QCD Factorization. We also present a conceptual analysis of heavy-to-light form factors at large recoil.
43936826
The transverse-momentum spectrum of Higgs bosons near threshold at NNLO
A bstractWe give next-to-next-to-leading order (NNLO) predictions for the Higgs production cross section at large transverse momentum in the threshold limit. Near the partonic threshold, all radiation is either soft or collinear to the final state jet which recoils against the Higgs boson. We find that the real emission corrections are of moderate size, but that the virtual corrections are large. We discuss the origin of these corrections and give numerical predictions for the transverse-momentum spectrum. The threshold result is matched to the known NLO result and implemented in the public code PeTeR.
119910077
FISSION AND THE SYNTHESIS OF HEAVY NUCLEI BY RAPID NEUTRON CAPTURE.
124991742
COUPLING MODULATOR SIMULATIONS INTO AN FEL AMPLIFIER FOR COHERENT ELECTRON COOLING
Next-generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques [1]. Particle-in-cell (PIC) simulations of a CeC modulator with the parallel VORPAL framework generate macro-particle distributions with subtle but important phase space correlations. To couple these macro-particles into a 3D simulation code for the free-electron laser (FEL) amplifier, while retaining all details of the 6D phase space coordinates, we implemented an alternative approach based on particle-clone pairs [2]. Our approach allows for selfconsistent treatment of shot noise and spontaneous radiation, with no need for quiet-start initialization of the FEL macro-particles’ ponderomotive phase. We present results of comparing fully 3D amplifier modeling based on the particle-clone approach vs GENESIS [3] simulations where distribution of bunching parameter was used as input.
55740595
Present Status of Coherent Electron Cooling Proof-of-Principle Experiment
The status of FEL-based Coherent Electron Cooling Proof-of-principle Experiment at BNL is presented. The experimental set-up is comprised of a 2 MeV CW SRF electron gun and 20 MeV CW SRF linac and 8-m long helical FEL amplifier. The status of the accelerator commissioning, and progress in the construction of the helical undulator at Budker INP, is also reported.
29202817
Electron cooling in the presence of undulator fields
The design of the higher-energy cooler for Relativistic Heavy Ion Collider (RHIC) recently adopted a non-magnetized approach which requires a low temperature electron beam [1]. However, to avoid significant loss of heavy ions due to recombination with electrons in the cooling section, the temperature of the electron beam should be high. These two contradictory requirements are satisfied in the design of the RHIC cooler with the help of the undulator fields. The model of the friction force in the presence of an undulator field was benchmarked vs direct numerical simulations with an excellent agreement. Here, we discuss cooling dynamics simulations with a helical undulator, including recombination suppression and resulting luminosities.
53999449
Advances in Coherent Electron Cooling
Cooling techniques are required for improving the quality of hadron beams and increasing the luminosity in hadron- and electron-hadron-colliders. In contrast to light leptons that have very strong radiation damping via synchrotron radiation, the hadrons radiate very little (even in a 7-TeV LHC) and require an additional cooling mechanism to control the growth or reduce their emittances. In this paper, we focus on the advances in, and challenges of Coherent Electron Cooling (CeC) that promises to be an effective method of cooling of high-energy hadron beams, and potentially even ultra-relativistic muon beams. Specifically, we describe the underlying physics principles, and the advances in this revolutionary, but yet untested, technique: viz., CeC. While we described physics principles in an earlier paper [1], our comprehensive studies revealed several other important factors affecting the CeC’s performance [2-5]. In this paper, we summarize our main findings as well as presenting current advances and novel CeC schemes. We also briefly describe the CeC demonstration experiment under preparation at Brookhaven National Laboratory; its detailed description is part of these proceedings [6].