118299841
Subtractions for SCET Soft Functions
We present a method to calculate the soft function in Soft-Collinear Effective Theory to NLO for N-jet events, defined with respect to arbitrarily complicated observables and algorithms, using a subtraction-based method. We show that at one loop the singularity structure of all observable/algorithm combinations can be classified as one of two types. Type I jets include jets defined with inclusive algorithms for which a jet shape is measured. Type II jets include jets found with exclusive algorithms, as well as jets for which only the direction and energy are measured. Cross sections that are inclusive over a certain region of phase space, such as the forward region at a hadron collider, are examples of Type II jets. We show that for a large class of measurements the required subtractions are already known analytically, including traditional jet shape measurements at hadron colliders. We demonstrate our method by calculating the soft functions for the case of jets defined in eta-phi space with an out-of-jet pT cut and a rapidity cut on the jets, as well as for the case of 1-jettiness.
119374134
Factorization and end point singularities in heavy-to-light decays
We prove a factorization theorem for heavy-to-light form factors. Our result differs in several important ways from previous proposals. A proper separation of scales gives hard kernels that are free of end point singularities. A general procedure is described for including soft effects usually associated with the tail of wave functions in hard exclusive processes. We give an operator formulation of these soft effects using the soft-collinear effective theory, and show that they appear at the same order in the power counting as the hard spectator contribution.
119428056
B decay shape variables and the precision determination of |V(cb)| and m(b)
We present expressions for shape variables of B decay distributions in several different mass schemes, to order $\alpha_s^2\beta_0$ and (Lambda_{QCD}/mb)^3. Such observables are sensitive to the b quark mass and matrix elements in the heavy quark effective theory, and recent measurements allow precision determinations of some of these parameters. We perform a combined fit to recent experimental results from CLEO, BABAR, and DELPHI, and discuss the theoretical uncertainties due to nonperturbative and perturbative effects. We discuss the possible discrepancy between the OPE prediction, recent BABAR results and the measured branching fraction to D and D* states. We find |Vcb| = (40.8 +- 0.9) x 10^{-3} and mb^{1S} = 4.74 +- 0.10 GeV, where the errors are dominated by experimental uncertainties.
125899154
Determining |V(ub)| from the anti-B ---> X(u) lepton anti-neutrino dilepton invariant mass spectrum
119475756
On differences between SCET and QCDf for B ---> pi pi decays
We give a detailed description of the differences between the factorization and results derived from SCET and QCDF for decays B -> M1 M2. This serves as a reply to a comment about our work "B-> M1 M2: Factorization, charming penguins, strong phases, and polarization" [1] made by the authors in [2]. We disagree with their criticisms.
34485941
Fluctuating annihilation cross sections and the generation of density perturbations
Fluctuations in the mass and decay rate of a heavy particle which for some period dominates the energy density of the Universe are known to lead to adiabatic density perturbations. We show that generically the annihilation cross section of the same particle also receives fluctuations, which leads to entropy perturbations at freeze-out. If the particle comes to dominate the energy density of the Universe and subsequently decays, this leads to an additional source of adiabatic density perturbations. On the other hand, nonadiabatic density perturbations result when the particle does not decay but contributes to the observed dark matter.
126269166
Handling of beam impurities in gamma-spectroscopy experiments at REX-ISOLDE (CERN)
The REX-ISOLDE facility at CERN delivers a great variety of radioactive ion beams with energies up to 3.0 MeV/u and therefore allows nuclear structure physics experiments far from the valley of stability. A crucial point for the experimentalist is the knowledge of beam contaminations, either from the bunching and charge-breeding procedure (residual gas ions) or directly from the ion-production process (isobaric contaminants), whose sources are discussed as well as possible ways of elimination during the postacceleration. Methods to analyse the beam composition in the relevant energy range are presented on the basis of two specific experiments using the MINIBALL detector array with an emphasis on the experimental challenges in Gamma-spectroscopy experiments and data analysis.