Reparameterization Invariant Collinear Operators

In constructing collinear operators, which describe the production of energetic jets or energetic hadrons, important constraints are provided by reparameterization invariance (RPI). RPI encodes Lorentz invariance in a power expansion about a collinear direction, and connects the Wilson coefficients of operators at different orders in this expansion to all orders in alphas. We construct reparameterization invariant collinear objects. The expansion of operators built from these objects provides an efficient way of deriving RPI relations and finding a minimal basis of operators, particularly when one has an observable with multiple collinear directions and/or soft particles. Complete basis of operators are constructed for pure glue currents at twist-4, and for operators involving multiple collinear directions, including those appearing in e+e- -> 3 jets, and for pp-> 2 jets initiated via gluon-fusion.Comment: 45 pages, Journal Version, Ref. adde

Carbon Pricing in Climate Policy: Seven Reasons, Complementary Instruments, and Political Economy Considerations

Carbon pricing is a recurrent theme in debates on climate policy. Discarded at the 2009 COP in Copenhagen, it remained part of deliberations for a climate agreement in subsequent years. As there is still much misunderstanding about the many reasons to implement a global carbon price, ideological resistance against it prospers. Here, we present the main arguments for carbon pricing, to stimulate a fair and well-informed discussion about it. These include considerations that have received little attention so far. We stress that a main reason to use carbon pricing is environmental effectiveness at a relatively low cost, which in turn contributes to enhance social and political acceptability of climate policy. This includes the property that corrected prices stimulate rapid environmental innovations. These arguments are underappreciated in the public debate, where pricing is frequently downplayed and the erroneous view that innovation policies are sufficient is widespread. Carbon pricing and technology policies are, though, largely complementary and thus are both needed for effective climate policy. We also comment on the complementarity of other instruments to carbon pricing. We further discuss distributional consequences of carbon pricing and present suggestions on how to address these. Other political economy issues that receive attention are lobbying, co-benefits, international policy coordination, motivational crowding in/out, and long-term commitment. The overview ends with reflections on implementing a global carbon price, whether through a carbon tax or emissions trading. The discussion goes beyond traditional arguments from environmental economics by including relevant insights from energy research and innovation studies as well

Jet Shapes and Jet Algorithms in SCET

Jet shapes are weighted sums over the four-momenta of the constituents of a jet and reveal details of its internal structure, potentially allowing discrimination of its partonic origin. In this work we make predictions for quark and gluon jet shape distributions in N-jet final states in e+e- collisions, defined with a cone or recombination algorithm, where we measure some jet shape observable on a subset of these jets. Using the framework of Soft-Collinear Effective Theory, we prove a factorization theorem for jet shape distributions and demonstrate the consistent renormalization-group running of the functions in the factorization theorem for any number of measured and unmeasured jets, any number of quark and gluon jets, and any angular size R of the jets, as long as R is much smaller than the angular separation between jets. We calculate the jet and soft functions for angularity jet shapes \tau_a to one-loop order (O(alpha_s)) and resum a subset of the large logarithms of \tau_a needed for next-to-leading logarithmic (NLL) accuracy for both cone and kT-type jets. We compare our predictions for the resummed \tau_a distribution of a quark or a gluon jet produced in a 3-jet final state in e+e- annihilation to the output of a Monte Carlo event generator and find that the dependence on a and R is very similar.Comment: 62 pages plus 21 pages of Appendices, 13 figures, uses JHEP3.cls. v2: corrections to finite parts of NLO jet functions, minor changes to plots, clarified discussion of power corrections. v3: Journal version. Introductory sections significantly reorganized for clarity, classification of logarithmic accuracy clarified, results for non-Mercedes-Benz configurations adde

Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented

Tracker Operation and Performance at the Magnet Test and Cosmic Challenge

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented

Performance studies of the CMS strip tracker before installation

Peer reviewe

Installation entries and exits in the EU ETS industrial sector

Focusing on the industrial sector of the EU ETS, this study identifies and analyses the entries and the exits of installations into and from the system over the period 2005-2013. The overall number of exits was notable relative to the number of installations, and significantly greater than that of the entries. Further, we estimate a hazard model for the risk of an installation exiting the EU ETS, which identifies a number of different factors referring to the installation, the firm, and the economy, explaining the occurrence of this event. In addition to these, an “end-of-phase effect” is found, whereby the chances of exit were significantly higher in the final years of the EU ETS Phases I and II. This effect, related to the rules concerning the closure of an installation and the withdrawal of the relative allowances, is detrimental to the allocative efficiency of the system and, therefore, to its cost-effectiveness in emissions abatement. The evidence provided by the study and some of its methodological aspects may be useful for future attempts to identify investment leakage in the EU ETS

Free allowance allocation in the EU ETS

In the EU ETS, free allowance allocation is used to safeguard the competitiveness of the regulated industries and to avoid carbon leakage. In Phase I and II, most allowances were given for free. With Phase III, auctioning became the default method for allocation of allowances. However, industrial sectors receive free allowances according to emission efficiency benchmarks and depending on the sectoral risk of carbon leakage. Sectors at risk of carbon leakage are identified based on carbon and trade intensity. • We analysed the empirical research on the EU ETS relevant to free allocation. First, no strong evidence has been found that the EU ETS affected the competitiveness of the regulated industries. Second, an overly conservative criterion for identifying the sectors at risk of carbon leakage meant that free allowances were given to installations which most likely were in fact not at risk. Third, evidence of pass-through of carbon costs was found not only for the electricity sector, but also for industrial sectors. • The reform for Phase IV proposed by the European Commission introduces some changes relevant to free allocation. Notably, it devises a more efficient criterion for identifying the sectors at risk of carbon leakage and it sets a rule for updating the benchmark values