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Production of a Z boson and two jets with one heavy-quark tag

Description: We present a next-to-leading-order calculation of the production of a Z boson with two jets, one or more of which contains a heavy quark (Q = c, b). We show that the cross section with only one heavy-quark jet is larger than that with two heavy-quark jets at both the Fermilab Tevatron and the CERN LHC. These processes are the dominant irreducible backgrounds to a Higgs boson produced in association with a Z boson, followed by h {yields} b{bar b}. Our calculation makes use of a heavy-quark distr… more
Date: October 1, 2005
Creator: Campbell, J.; /CERN; Ellis, R.K.; /Fermilab, /CERN; Maltoni, F.; U., /CERN /Louvain et al.
Partner: UNT Libraries Government Documents Department
open access

Status of SM Calculations of b to s Transitions

Description: We report recent progress in SM calculations of b {yields} s transitions. We discuss the first NNLL prediction of the {bar B} {yields} X{sub s}{gamma} branching ratio, including important additional subtleties due to non-perturbative corrections and logarithmically-enhanced cut effects, and also recent results on the inclusive mode {bar B} {yields} X{sub s}{ell}{sup +}{ell}{sup -}. Moreover, new results on the corresponding exclusive modes are reviewed. Finally, we comment on the present status… more
Date: April 4, 2007
Creator: Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

New Physics Search in Flavour Physics

Description: With the running B, kaon and neutrino physics experiments, flavour physics takes centre stage within today's particle physics. We discuss the opportunities offered by these experiments in our search for new physics beyond the SM and discuss their complementarity to collider physics. We focus on rare B and kaon decays, highlighting specific observables in an exemplary mode. We also comment on the so-called B {yields} {pi}{pi} and B {yields} K{pi} puzzles. Moreover, we briefly discuss the restric… more
Date: January 4, 2006
Creator: Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

Scattering Amplitudes: The Most Perfect Microscopic Structures in the Universe

Description: This article gives an overview of many of the recent developments in understanding the structure of relativistic scattering amplitudes in gauge theories ranging from QCD to N = 4 super-Yang-Mills theory, as well as (super)gravity. I also provide a pedagogical introduction to some of the basic tools used to organize and illuminate the color and kinematic structure of amplitudes. This article is an invited review introducing a special issue of Journal of Physics A devoted to 'Scattering Amplitude… more
Date: November 4, 2011
Creator: Dixon, Lance J. & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

C++ and data

Description: High performance computing with a large code base and C++ has proved to be a good combination. But when it comes to storing data, C++ is a problematic choice: it offers no support for serialization, type definitions are amazingly complex to parse, and the dependency analysis (what does object A need to be stored?) is incredibly difficult. Nevertheless, the LHC data consists of C++ objects that are serialized with help from ROOT's reflection database and interpreter CINT. The fact that we can do… more
Date: January 1, 2008
Creator: Naumann, Axel; /CERN; Canal, Philippe & /Fermilab
Partner: UNT Libraries Government Documents Department
open access

EMC Phenomena in HEP Detectors: Prevention and Cost Savings

Description: This paper addresses electromagnetic compatibility (EMC) studies applied to high-energy physics (HEP) detectors. They are focused on the quantification of the front-end electronic (FEE) sensitivity to conductive noise coupled through the input/output cables. Immunity tests performed on FEE prototypes of both the CMS hadron calorimeter and the CMS silicon tracker are presented. These tests characterize the sensitivity of the FEE to common and differential mode noise coupled through the power cab… more
Date: June 6, 2006
Creator: Arteche, F.; /Imperial Coll., London /CERN & Rivetta, C.
Partner: UNT Libraries Government Documents Department
open access

Distributed analysis with CRAB: The client-server architecture evolution and commissioning

Description: CRAB (CMS Remote Analysis Builder) is the tool used by CMS to enable running physics analysis in a transparent manner over data distributed across many sites. It abstracts out the interaction with the underlying batch farms, grid infrastructure and CMS workload management tools, such that it is easily usable by non-experts. CRAB can be used as a direct interface to the computing system or can delegate the user task to a server. Major efforts have been dedicated to the client-server system devel… more
Date: January 1, 2008
Creator: Codispoti, G.; /INFN, Bologna /Bologna U.; Cinquilli, M.; /INFN, Perugia; Fanfani, A.; U., /Bologna et al.
Partner: UNT Libraries Government Documents Department
open access

Preliminary Study on Emittance Growth in the LHEC Recirculating Linac

Description: In this paper, we estimate the emittance growth in the LHeC recirculating Linac, the lattice design of which is presented in another paper of IPAC10 proceedings. The possible sources for emittance growth included here are: energy spread from RF acceleration in the SRF (superconducting RF) linac together with large chromatic effects from the lattice, and synchrotron radiation (SR) fluctuations in the recirculating arcs. 6-D multi-particle tracking is launched to calculate the emittance from the … more
Date: May 20, 2011
Creator: Sun, Yi-Peng; Adolphsen, Chris; /SLAC; Zimmermann, Frank & /CERN
Partner: UNT Libraries Government Documents Department
open access

Experience with the CMS Event Data Model

Description: The re-engineered CMS EDM was presented at CHEP in 2006. Since that time we have gained a lot of operational experience with the chosen model. We will present some of our findings, and attempt to evaluate how well it is meeting its goals. We will discuss some of the new features that have been added since 2006 as well as some of the problems that have been addressed. Also discussed is the level of adoption throughout CMS, which spans the trigger farm up to the final physics analysis. Future pla… more
Date: June 1, 2009
Creator: Elmer, P.; U., /Princeton; Hegner, B.; /CERN; Sexton-Kennedy, L. & /Fermilab
Partner: UNT Libraries Government Documents Department
open access

Beam losses from ultra-peripheral nuclear collisions between 208Pb82+ ions in the Large Hadron Collider and their alleviation

Description: Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulat… more
Date: July 1, 2009
Creator: Bruce, R.; Gildardoni, S.; Jowett, J.M.; /CERN; Bocian, D. & /Fermilab
Partner: UNT Libraries Government Documents Department
open access

SCET Sum Rules for B to P and B to V Transition Form Factors

Description: We investigate sum rules for heavy-to-light transition form factors at large recoil derived from correlation functions with interpolating currents for light pseudoscalar or vector fields in soft-collinear effective theory (SCET). We consider both, factorizable and nonfactorizable contributions at leading power in the {Lambda}/m{sub b} expansion and to first order in the strong coupling constant {alpha}{sub s}, neglecting contributions from 3-particle distribution amplitudes in the B-meson. We p… more
Date: December 18, 2007
Creator: De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten; U., /Siegen; Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

Light-cone Sum Rules in Soft-Collinear Effective Theory

Description: We derive light-cone sum rules (LCSRs) for exclusive B-meson decays into light energetic hadrons from correlation functions within soft-collinear effective theory (SCET). In these sum rules the short-distance scale refers to ''hard-collinear'' interactions with virtualities of order {Lambda}{sub QCD}m{sub b}. Hard scales (related to virtualities of order m{sub b}{sup 2}) are integrated out and enter via external coefficient functions in the sum rule. Soft dynamics is encoded in light-cone distr… more
Date: June 20, 2005
Creator: De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten; U., /Siegen; Hurth, Tobias & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

The B -> pi Form Factor from Light-cone Sum Rules in Soft-collinear Effective Theory

Description: Recently, we have derived light-cone sum rules for exclusive B-meson decays into light energetic hadrons from correlation functions within soft-collinear effective theory [1]. In these sum rules the short-distance scale refers to ''hard-collinear'' interactions with virtualities of order {Lambda}{sub QCD}m{sub b}. Hard scales (related to virtualities of order m{sub b}{sup 2}) are integrated out and enter via external coefficient functions in the sum rule. Soft dynamics is encoded in light-cone … more
Date: October 17, 2005
Creator: Hurth, Tobias; /SLAC, /CERN; De Fazio, Fulvia; /INFN, Bari; Feldmann, Thorsten & U., /Siegen
Partner: UNT Libraries Government Documents Department
open access

Light-cone Sum Rules: A SCET-based Formulation

Description: We describe the construction of light-cone sum rules (LCSRs) for exclusive B-meson decays into light energetic hadrons from correlation functions within soft-collinear effective theory (SCET). As an example, we consider the SCET sum rule for the B {yields} {pi} transition form factor at large recoil, including radiative corrections from hard-collinear loop diagrams at first order in the strong coupling constant.
Date: December 14, 2005
Creator: De Fazio, F.; /INFN, Bari; Feldmann, Th.; U., /Siegen; Hurth, T. & /SLAC, /CERN
Partner: UNT Libraries Government Documents Department
open access

Multi-Bunch Simulations of the ILC for Luminosity Performance Studies

Description: To study the luminosity performance of the International Linear Collider (ILC) with different design parameters, a simulation was constructed that tracks a multi-bunch representation of the beam from the Damping Ring extraction through to the Interaction Point. The simulation code PLACET is used to simulate the LINAC, MatMerlin is used to track through the Beam Delivery System and GUINEA-PIG for the beam-beam interaction. Included in the simulation are ground motion and wakefield effects, intra… more
Date: July 11, 2005
Creator: White, G.; /SLAC /Queen Mary, U. of London; Walker, N.; /DESY; Schulte, D. & /CERN
Partner: UNT Libraries Government Documents Department
open access

Coupled optics reconstruction from TBT data using MAD-X

Description: Turn-by-turn BPM data provide immediate information on the coupled optics functions at BPM locations. In the case of small deviations from the known (design) uncoupled optics some cognizance of the sources of perturbation, BPM calibration errors and tilts can also be inferred without detailed lattice modeling. In practical situations, however, fitting the lattice model with the help of some optics code would lead to more reliable results. We present an algorithm for coupled optics reconstructio… more
Date: June 1, 2007
Creator: Alexahin, Y.; Gianfelice-Wendt, E.; /Fermilab; Kapin, V.; Inst., /Moscow Phys. Eng.; Schmidt, F. et al.
Partner: UNT Libraries Government Documents Department
open access

Search for heavy leptons and hard penetrating radiation in the neutrino beam, study of diffraction scattering of neutrinos; study of deep inelastic vu scattering in a ne bubble chamber at NAL, and test of the delta s = delta q rule at high momentum transfer using inclusive reactions

Description: We propose here an experiment designed to search for the existence of heavy leptons ({lambda}{sup +}) produced in the collisions of 400 GeV/c protons with matter in the beam dump. These charged leptons, which are assumed to decay by weak interaction will be detected by the interactions of their neutrinos ({upsilon}{sub {lambda}}, {bar {upsilon}}{sub {lambda}}) in a Ne bubble chamber. For leptons with masses of greater than 1 GeV, the {lambda} life time is expected to be too short for the lepton… more
Date: June 1, 1970
Creator: Benvenuti, A.; Camerini, U.; Fry, W.; March, R.; /Wisconsin U., Madison; Wachsmuth, H.W. et al.
Partner: UNT Libraries Government Documents Department
open access

Precise Predictions for W 4 Jet Production at the Large Hadron Collider

Description: We present the first next-to-leading order QCD results for W + 4-jet production at hadron colliders. Total cross sections, as well as distributions in the jet transverse momenta and in the total transverse energy HT, are provided for the initial LHC energy of {radical}s = 7 TeV. We use a leading-color approximation, known to be accurate to 3% for W production with fewer jets. The virtual matrix elements and the most complicated real-emission matrix elements are handled by the BlackHat library, … more
Date: September 14, 2010
Creator: Berger, C.F.; /MIT, LNS; Bern, Z.; /UCLA; Dixon, Lance J.; /SLAC, /CERN et al.
Partner: UNT Libraries Government Documents Department
open access

A Betatron tune fitting package for the Tevatron 21.4 MHz Schottky

Description: The Fermilab Tevatron is equipped with two independent Schottky monitors for measurement of betatron tunes, one operating at 21.4 MHz and the other at 1.7 GHz. A new front-end and related data acquisition for the 21.4 MHz resonator has been installed and commissioned during the FY04 Collider RunII. Sophisticated fitting strategies are required to analyze the spectra. Optimization of this fitting package allows us to report tune and chromaticity measurements at almost 1 Hz.
Date: May 1, 2005
Creator: Lebrun, Paul L. G.; Sen, Tanaji; You, Jian-Ming; Yuan, Zong-Wei; /Fermilab; Todesco, Ezio et al.
Partner: UNT Libraries Government Documents Department
open access

Electron Cloud at Low Emittance in CesrTA

Description: The Cornell Electron Storage Ring (CESR) has been reconfigured as a test accelerator (CesrTA) for a program of electron cloud (EC) research at ultra low emittance. The instrumentation in the ring has been upgraded with local diagnostics for measurement of cloud density and with improved beam diagnostics for the characterization of both the low emittance performance and the beam dynamics of high intensity bunch trains interacting with the cloud. A range of EC mitigation methods have been deploye… more
Date: July 6, 2012
Creator: Palmer, Mark; /Cornell U., CLASSE; Alexander, James; /Cornell U., CLASSE; Billing, Michael; /Cornell U., CLASSE et al.
Partner: UNT Libraries Government Documents Department
open access

New Observables In the Decay Mode \bar B_d \-->\bar K^{0*} \ell^+ \ell^-

Description: We discuss the large set of observables available from the angular distributions of the decay {bar B}{sub d} {yields} {bar K}*{sup 0}{ell}{sup +}{ell}{sup -}. We present a NLO analysis of all observables based on the QCD factorization approach in the low-dilepton mass region and an estimate of {Lambda}/m{sub b} corrections. Moreover, we discuss their sensitivity to new physics. We explore the experimental sensitivities at LHCb (10 fb{sup -1}) and SuperLHCb (100 fb{sup -1}) based on a full-angul… more
Date: August 7, 2008
Creator: Egede, U.; /Imperial Coll., London; Hurth, T.; /SLAC, /CERN; Matias, J.; Ramon, M. et al.
Partner: UNT Libraries Government Documents Department
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