118830218
Prospects for the measurement of the unitarity triangle angle gamma from B-0 -> DK+pi(-) decays
The potential for a precise measurement of the unitarity triangle angle gamma in future experiments from the decay B-0 -> DK*0 is well known. It has recently been suggested that the sensitivity can be significantly enhanced by analyzing the B-0 -> DK+pi(-) Dalitz plot to extract amplitudes relative to those of the flavor-specific decay B-0 -> D2*-K+. An extension to this method which includes the case where the neutral D meson is reconstructed in suppressed final states is presented. The sensitivity to gamma is estimated using this method and compared to that obtained using the B-0 -> DK*0 decay alone. Experimental effects, such as background contamination, are also considered. This approach appears to be a highly attractive addition to the family of methods that can be used to determine gamma.
121580852
New results in ω photoproduction using high-statistics data obtained from CLAS at Jefferson Lab
High-statistics differential cross sections and spin density matrix elements for the reaction γ p → p ω have been measured using the CLAS at Jefferson Lab for center-of-mass energies, W , from threshold up to 2.84 GeV. An event-based partial wave analysis (PWA) has also been performed on the data. This analysis benefits from access to the world's first high precision spin density matrix element measurements, available to the event-based PWA through the decay distribution of ω → π + π − π 0 . Strong evidence has been found for nucleon resonance contributions.
56334536
uBoost: a boosting method for producing uniform selection efficiencies from multivariate classifiers
The use of multivariate classifiers, especially neural networks and decision trees, has become commonplace in particle physics. Typically, a series of classifiers is trained rather than just one to enhance the performance; this is known as boosting. This paper presents a novel method of boosting that produces a uniform selection efficiency in a selected multivariate space. Such a technique is well suited for amplitude analyses or other situations where optimizing a single integrated figure of merit is not what is desired.
106656211
User analysis of LHCb data with Ganga
GANGA (http://cern.ch/ganga) is a job-management tool that offers a simple, efficient and consistent user analysis tool in a variety of heterogeneous environments: from local clusters to global Grid systems. Experiment specific plug-ins allow GANGA to be customised for each experiment. For LHCb users GANGA is the officially supported and advertised tool for job submission to the Grid. The LHCb specific plug-ins allow support for end-to-end analysis helping the user to perform his complete analysis with the help of GANGA. This starts with the support for data selection, where a user can select data sets from the LHCb Bookkeeping system. Next comes the set up for large analysis jobs: with tailored plug-ins for the LHCb core software, jobs can be managed by the splitting of these analysis jobs with the subsequent merging of the resulting files. Furthermore, GANGA offers support for Toy Monte-Carlos to help the user tune their analysis. In addition to describing the GANGA architecture, typical usage patterns within LHCb and experience with the updated LHCb DIRAC workload management system are presented.
119112453
How good are your fits? Unbinned multivariate goodness-of-fit tests in high energy physics
Multivariate analyses play an important role in high energy physics. Such analyses often involve performing an unbinned maximum likelihood fit of a probability density function (p.d.f.) to the data. This paper explores a variety of unbinned methods for determining the goodness of fit of the p.d.f. to the data. The application and performance of each method is discussed in the context of a real-life high energy physics analysis (a Dalitz-plot analysis). Several of the methods presented in this paper can also be used for the non-parametric determination of whether two samples originate from the same parent p.d.f. This can be used, e.g., to determine the quality of a detector Monte Carlo simulation without the need for a parametric expression of the efficiency.
18677949
Separating Signals from Non-Interfering Backgrounds using Probabilistic Event Weightings
A common situation in experimental physics is to have a signal which can not be separated from a non-interfering background through the use of any cut. In this paper, we describe a procedure for determining, on an event-by-event basis, a quality factor (Q-factor) that a given event originated from the signal distribution. This Q-factor can then be used as an event weight in subsequent analysis procedures, allowing one to more directly access the true spectrum of the signal.
3581209
EFT beyond the horizon: stochastic inflation and how primordial quantum fluctuations go classical
A bstractWe identify the effective field theory describing the physics of super-Hubble scales and show it to be a special case of a class of effective field theories appropriate to open systems. Open systems are those that allow information to be exchanged between the degrees of freedom of interest and those that are integrated out, such as would be appropriate for particles moving through a fluid. Strictly speaking they cannot in general be described by an effective lagrangian; rather the appropriate ‘low-energy’ limit is instead a Lindblad equation describing the time-evolution of the density matrix of the slow degrees of freedom. We derive the equation relevant to super-Hubble modes of quantum fields in de Sitter (and near-de Sitter) spacetimes and derive two of its implications. We show that the evolution of the diagonal density-matrix elements quickly approach the Fokker-Planck equation of Starobinsky’s stochastic inflationary picture. This allows us both to identify the leading corrections and provide an alternative first-principles derivation of this picture’s stochastic noise and drift. (As applications we show that the noise for massless fields is independent of the details of the window function used, and also compute how the noise changes for systems with a sub-luminal speed of sound, cs< 1.) We then argue that the presence of interactions drive the off-diagonal density-matrix elements to zero in the field
118294173
A measurement of the inclusive branching ratio for $b o sgamma$ with the ALEPH detector at LEP
117248378
Accidental Supersymmetry and the Naturalness of Codimension-2 Branes
This thesis addresses two separate naturalness issues which generically come to bear on physical theories with large extra dimensions, and so a gravity scale much lower than the Planck scale. The first is related to the observed stability of the proton, wherein we determine the relevant constraints on an additional gauge boson which conserves baryon number. Although several such proposals have been previously considered, our analysis is distinctive in its interest in lighter gauge boson masses (which naturally arise in such models), and in its focus on the dependence of constraints due to kinetic mixing effects. The second is related to the main purpose of large extra dimensions—namely, to address the smallness of the observed vacuum energy—wherein we compute the leading-order quantum corrections to the four-dimensional (4D) vacuum energy resulting from loops of extradimensional fields. We compute the contributions from bulk scalars (spin 0), fermions (spin 12 ), and gauge fields (spin 1) in a flux-stabilized, spheroidal extra-dimensional geometry whose rugbyball shape is due to two codimension-2 branes—one at each pole. (We also obtain the corresponding beta functions for both bulk and brane operators.) These results are then combined to obtain the net contribution from various multiplets in the context of a particular supersymmetric extra-dimensional model that has been shown to give a vanishing result for the 4D vacuum energy at the classical level. Surprisingly, we find that supersymmetry can be preserved dynamically at one loop in the case of identical branes, without arranging any particular relationship between the brane parameters. Perturbing away from the case of identical branes is shown to give a positive 1-loop contribution to the 4D vacuum energy whose size is set by the radius of the extra dimensions.
110521797
Ganga: User-friendly Grid job submission and management tool for LHC and beyond
Ganga has been widely used for several years in ATLAS, LHCb and a handful of other communities. Ganga provides a simple yet powerful interface for submitting and managing jobs to a variety of computing backends. The tool helps users configuring applications and keeping track of their work. With the major release of version 5 in summer 2008, Ganga's main user-friendly features have been strengthened. Examples include a new configuration interface, enhanced support for job collections, bulk operations and easier access to subjobs. In addition to the traditional batch and Grid backends such as Condor, LSF, PBS, gLite/EDG a point-to-point job execution via ssh on remote machines is now supported. Ganga is used as an interactive job submission interface for end-users, and also as a job submission component for higher-level tools. For example GangaRobot is used to perform automated, end-to-end testing of distributed data analysis. Ganga comes with an extensive test suite covering more than 350 test cases. The development model involves all active developers in the release management shifts which is an important and novel approach for the distributed software collaborations. Ganga 5 is a mature, stable and widely-used tool with long-term support from the HEP community.
119159946
Inflating with Large Effective Fields
We re-examine large scalar fields within effective field theory, in particular focussing on the issues raised by their use in inflationary models (as suggested by BICEP2 to obtain primordial tensor modes). We argue that when the large-field and low-energy regimes coincide the scalar dynamics is most effectively described in terms of an asymptotic large-field expansion whose form can be dictated by approximate symmetries, which also help control the size of quantum corrections. We discuss several possible symmetries that can achieve this, including pseudo-Goldstone inflatons characterized by a coset G/H (based on abelian and non-abelian, compact and non-compact symmetries), as well as symmetries that are intrinsically higher dimensional. Besides the usual trigonometric potentials of Natural Inflation we also find in this way simple large-field power laws (like V ∝ φ{sup 2}) and exponential potentials, V(φ) = ∑{sub k}V{sub x}e{sup −kφ/M}. Both of these can describe the data well and give slow-roll inflation for large fields without the need for a precise balancing of terms in the potential. The exponential potentials achieve large r through the limit |η| || e and so predict r ≅ (8/3)(1-n{sub s}); consequently n{sub s} ≅ 0.96 gives r ≅ 0.11 but not much larger (and so could be ruled out as measurements on r and n{sub s} improve).more » We examine the naturalness issues for these models and give simple examples where symmetries protect these forms, using both pseudo-Goldstone inflatons (with non-abelian non-compact shift symmetries following familiar techniques from chiral perturbation theory) and extra-dimensional models.« less