2,266 research outputs found

### Theory-data comparisons for jet measurements in hadron-induced processes

Abstract We present a comprehensive overview of theory-data comparisons for inclusive jet production. Theory predictions are derived for recent parton distribution functions and compared with jet data from different hadron-induced processes at various center-ofmass energies â s. The comparisons are presented as a function of jet transverse momentum p T or, alternatively, of the scaling variable x T = 2p T / â s

### Tracking and Alignment with the Silicon Strip Tracker at the CMS Magnet Test Cosmic Challenge

Data were collected with a custom-built sub-structure of the silicon strip tracker, both during the preparation of the Magnet Test Cosmic Challenge and during the challenge itself. These data were used to evaluate performance of track reconstruction and detector alignment algorithms, both with and without magnetic field. The track reconstruction algorithm is described in detail and its performance presented, in terms of its efficiency, resolution and consistency with the results from other sub-detectors. A study of detector alignment is shown, including the use tracker construction information. The effect of alignment on track quality is discussed

### NNLO interpolation grids for jet production at the LHC

Fast interpolation-grid frameworks facilitate an efficient and flexible evaluation of higher-order predictions for any choice of parton distribution functions or value of the strong coupling $\alpha _{\mathrm {s}}$. They constitute an essential tool for the extraction of parton distribution functions and Standard Model parameters, as well as studies of the dependence of cross sections on the renormalisation and factorisation scales. The APPLfast project provides a generic interface between the parton-level Monte Carlo generator "Image missing" and both the APPLgrid and the fastNLO libraries for the grid interpolation. The extension of the project to include hadronâhadron collider processes at next-to-next-to-leading order in perturbative QCD is presented, together with an application for jet production at the LHC

### NNLO interpolation grids for jet production at the LHC

Fast interpolation-grid frameworks facilitate an efficient and flexible evaluation of higher-order predictions for any choice of parton distribution functions or value of the strong coupling Î±$_s$. They constitute an essential tool for the extraction of parton distribution functions and Standard Model parameters, as well as studies of the dependence of cross sections on the renormalisation and factorisation scales. The APPLFAST project provides a generic interface between the parton-level Monte Carlo generator NNLOJET and both the APPLGRID and the FASTNLO libraries for the grid inter- polation. The extension of the project to include hadronâ hadron collider processes at next-to-next-to-leading order in perturbative QCD is presented, together with an application for jet production at the LHC

### Calculations for deep inelastic scattering using fast interpolation grid techniques at NNLO in QCD and the extraction of Î±s from HERA data

The extension of interpolation-grid frameworks for perturbative QCD calculations at next-to-next-to-leading order (NNLO) is presented for deep inelastic scattering (DIS) processes. A fast and flexible evaluation of higher-order predictions for any a posteriori choice of parton distribution functions (PDFs) or value of the strong coupling constant is essential in iterative fitting procedures to extract PDFs and Standard Model parameters as well as for a detailed study of the scale dependence. The APPLfast project, described here, provides a generic interface between the parton-level Monte Carlo program NNLOjet and both the APPLgrid and fastNLO libraries for the production of interpolation grids at NNLO accuracy. Details of the interface for DIS processes are presented together with the required interpolation grids at NNLO, which are made available. They cover numerous inclusive jet measurements by the H1 and ZEUS experiments at HERA. An extraction of the strong coupling constant is performed as an application of the use of such grids and a best-fit value of Î±s(MZ)=0.1170(15)exp(25)th is obtained using the HERA inclusive jet cross section data

### Erratum to: Calculations for deep inelastic scattering using fast interpolation grid techniques at NNLO in QCD and the extraction of $\alpha _{\mathrm {s}}$ from HERA data

The implementation of interpolation grid techniques at NNLO and their subsequent application to the extraction of the strong coupling constant Î± s
Î±s
presented in Ref. [1] are based on the calculation in the framework [2,3,4]. An implementation error was found in this calculation [4] that altered the predicted cross sections for the DIS process at NNLO. While technical aspects and equations remain unchanged, reported numerical values and the extracted value of Î± s
Î±s
are affected. Updated figures, tables, and numbers quoted in the main text that have changed are provided. Numbering of sections and figures is as in Ref. [1]

### Simultaneous multi-frequency observation of the unknown redshift blazar PG 1553+113 in March-April 2008

The blazar PG 1553+113 is a well known TeV gamma-ray emitter. In this paper,
we determine its spectral energy distribution using simultaneous
multi-frequency data in order to study its emission processes. An extensive
campaign was carried out between March and April 2008, where optical, X-ray,
high-energy (HE) gamma-ray, and very-high-energy (VHE) gamma-ray data were
obtained with the KVA, Abastumani, REM, RossiXTE/ASM, AGILE and MAGIC
telescopes, respectively. This is the first simultaneous broad-band (i.e.,
HE+VHE) gamma-ray observation, though AGILE did not detect the source. We
combine data to derive source's spectral energy distribution and interpret its
double peaked shape within the framework of a synchrotron self compton modelComment: 5 pages, 2 figures, publishe

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