We describe a calculation of the fully differential cross section for Higgs boson production in the gluon fusion channel through next-to-next-to-leading order (NNLO) in perturbative QCD. The decay of ...the Higgs boson into two photons is included. Technical aspects of the computation are discussed in detail. The implementation of the calculation into a numerical code, called
FEHiP, is described. The NNLO
K-factors for completely realistic photon acceptances and isolation cuts, including those employed by the ATLAS and CMS Collaborations, are computed. We study various distributions of the photons from Higgs decay through NNLO.
High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the
Z
(
ν
ν
¯
)
+
... jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by
Z
(
ℓ
+
ℓ
-
)
+
jet,
W
(
ℓ
ν
)
+
jet and
γ
+
jet production, and extrapolating to the
Z
(
ν
ν
¯
)
+
jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant
V
+
jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different
V
+
jet processes play a key role. The anticipated theoretical uncertainty in the
Z
(
ν
ν
¯
)
+
jet background is at the few percent level up to the TeV range.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
W physics at the LHC with FEWZ 2.1 Quackenbush, Seth; Gavin, Ryan; Li, Ye ...
Computer physics communications,
January 2013, 2013-1-00, Letnik:
184, Številka:
1
Journal Article
Recenzirano
We present an updated version of the FEWZ (Fully Exclusive W and Z production) code for the calculation of W± and γ∗/Z production at next-to-next-to-leading order in the strong coupling. Several new ...features and observables are introduced, and an order-of-magnitude speed improvement over the performance of FEWZ 2.0 is demonstrated. New phenomenological results for W± production and comparisons with LHC data are presented, and used to illustrate the range of physics studies possible with the features of FEWZ 2.1. We demonstrate with an example the importance of directly comparing fiducial-region measurements with theoretical predictions, rather than first extrapolating them to the full phase space.
Program title: FEWZ 2.1
Catalogue identifier: AEJP_v1_1
Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AEJP_v1_1.html
Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland
Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html
No. of lines in distributed program, including test data, etc.: 12003230
No. of bytes in distributed program, including test data, etc.: 769
Distribution format: tar.gz
Programming language: Fortran 77, C++, Python 2.4.
Computer: x86/x86-64.
Operating system: Unix/Linux, Mac OSX.
RAM: 200 Mbytes
Classification: 11.1.
External routines: CUBA (included), LHAPDF (optional)
Catalogue identifier of previous version: AEJP_v1_0
Journal reference of previous version: Comput. Phys. Comm. 182 (2011) 2388
Does the new version supersede the previous version?: Yes
Nature of problem: Calculation of hadroproduction of W bosons, with differential distributions, at next-to-next-to-leading order in the strong coupling.
Solution method: Integral reduction, sector decomposition, numerical integration
Reasons for new version: Reintroduction of W boson to FEWZ 2
Summary of revisions: Addition of W boson production, now can run in W or Z/gamma mode. LHAPDF interface added. Large speed improvements achieved through caching repeat function calls. New observables and histograms. Improved histogram binning.
Additional comments: Running with all histograms on requires approx. 1 GB of disk space to store intermediate files.
!!! The distribution file for this program is over 290 Mbytes and therefore is not delivered directly when download or e-mail is requested. Instead an html file giving details of how the program can be obtained is sent.!!!
Running time: 2 hours to achieve NNLO precision in cross section on multicore machines, up to a few days for quality kinematic distributions. Cluster running is considerably faster.
Abstract High-energy jets recoiling against missing transverse energy (MET) are powerful probes of dark matter at the LHC. Searches based on large MET signatures require a precise control of the ...$$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background in the signal region. This can be achieved by taking accurate data in control regions dominated by $$Z(\ell ^+\ell ^-)+$$ Z ( ℓ + ℓ - ) + jet, $$W(\ell \nu )+$$ W ( ℓ ν ) + jet and $$\gamma +$$ γ + jet production, and extrapolating to the $$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background by means of precise theoretical predictions. In this context, recent advances in perturbative calculations open the door to significant sensitivity improvements in dark matter searches. In this spirit, we present a combination of state-of-the-art calculations for all relevant $$V+$$ V + jets processes, including throughout NNLO QCD corrections and NLO electroweak corrections supplemented by Sudakov logarithms at two loops. Predictions at parton level are provided together with detailed recommendations for their usage in experimental analyses based on the reweighting of Monte Carlo samples. Particular attention is devoted to the estimate of theoretical uncertainties in the framework of dark matter searches, where subtle aspects such as correlations across different $$V+$$ V + jet processes play a key role. The anticipated theoretical uncertainty in the $$Z(\nu {\bar{\nu }})+$$ Z ( ν ν ¯ ) + jet background is at the few percent level up to the TeV range.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We report on a calculation of the cross-section for Higgs boson production in gluon fusion in association with a hadronic jet at next-to-next-to-leading order (NNLO) in perturbative QCD. ...The computational technique is discussed in detail. We show explicitly how to employ known soft and collinear limits of scattering amplitudes to construct subtraction terms for NNLO computations. Cancellation of singularities is demonstrated numerically for the collinearly-subtracted
gg
→
H
+
j
cross-section through NNLO and the finite
σ
gg→Hj
cross-section is computed through
as a function of the center-of-mass collision energy. We present numerical results for the gluon-fusion contribution to Higgs production in association with a jet at the LHC. The NNLO QCD corrections significantly reduce the residual scale dependence of the cross-section. The computational method that we describe in this paper is applicable to the calculation of NNLO QCD corrections to any other 2 → 2 process at a hadron collider without modification.
Abstract This report was prepared in the context of the LPCC Electroweak Precision Measurements at the LHC WG ( https://lpcc.web.cern.ch/lpcc/index.php?page=electroweak_wg ) and summarizes the ...activity of a subgroup dedicated to the systematic comparison of public Monte Carlo codes, which describe the Drell–Yan processes at hadron colliders, in particular at the CERN Large Hadron Collider (LHC). This work represents an important step towards the definition of an accurate simulation framework necessary for very high-precision measurements of electroweak (EW) observables such as the W boson mass and the weak mixing angle. All the codes considered in this report share at least next-to-leading-order (NLO) accuracy in the prediction of the total cross sections in an expansion either in the strong or in the EW coupling constant. The NLO fixed-order predictions have been scrutinized at the technical level, using exactly the same inputs, setup and perturbative accuracy, in order to quantify the level of agreement of different implementations of the same calculation. A dedicated comparison, again at the technical level, of three codes that reach next-to-next-to-leading-order (NNLO) accuracy in quantum chromodynamics (QCD) for the total cross section has also been performed. These fixed-order results are a well-defined reference that allows a classification of the impact of higher-order sets of radiative corrections. Several examples of higher-order effects due to the strong or the EW interaction are discussed in this common framework. Also the combination of QCD and EW corrections is discussed, together with the ambiguities that affect the final result, due to the choice of a specific combination recipe. All the codes considered in this report have been run by the respective authors, and the results presented here constitute a benchmark that should be always checked/reproduced before any high-precision analysis is conducted based on these codes. In order to simplify these benchmarking procedures, the codes used in this report, together with the relevant input files and running instructions, can be found in a repository at https://twiki.cern.ch/twiki/bin/view/Main/DrellYanComparison .
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This report was prepared in the context of the LPCC Electroweak Precision Measurements at the LHC WG ( https://lpcc.web.cern.ch/lpcc/index.php?page=electroweak_wg ) and summarizes the activity of a ...subgroup dedicated to the systematic comparison of public Monte Carlo codes, which describe the Drell–Yan processes at hadron colliders, in particular at the CERN Large Hadron Collider (LHC). This work represents an important step towards the definition of an accurate simulation framework necessary for very high-precision measurements of electroweak (EW) observables such as the W boson mass and the weak mixing angle. All the codes considered in this report share at least next-to-leading-order (NLO) accuracy in the prediction of the total cross sections in an expansion either in the strong or in the EW coupling constant. The NLO fixed-order predictions have been scrutinized at the technical level, using exactly the same inputs, setup and perturbative accuracy, in order to quantify the level of agreement of different implementations of the same calculation. A dedicated comparison, again at the technical level, of three codes that reach next-to-next-to-leading-order (NNLO) accuracy in quantum chromodynamics (QCD) for the total cross section has also been performed. These fixed-order results are a well-defined reference that allows a classification of the impact of higher-order sets of radiative corrections. Several examples of higher-order effects due to the strong or the EW interaction are discussed in this common framework. Also the combination of QCD and EW corrections is discussed, together with the ambiguities that affect the final result, due to the choice of a specific combination recipe. All the codes considered in this report have been run by the respective authors, and the results presented here constitute a benchmark that should be always checked/reproduced before any high-precision analysis is conducted based on these codes. In order to simplify these benchmarking procedures, the codes used in this report, together with the relevant input files and running instructions, can be found in a repository at https://twiki.cern.ch/twiki/bin/view/Main/DrellYanComparison .
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This report describes the physics case, the resulting detector requirements, and the evolving detector concepts for the experimental program at the Electron-Ion Collider (EIC). The EIC will be a ...powerful new high-luminosity facility in the United States with the capability to collide high-energy electron beams with high-energy proton and ion beams, providing access to those regions in the nucleon and nuclei where their structure is dominated by gluons. Moreover, polarized beams in the EIC will give unprecedented access to the spatial and spin structure of the proton, neutron, and light ions. The studies leading to this document were commissioned and organized by the EIC User Group with the objective of advancing the state and detail of the physics program and developing detector concepts that meet the emerging requirements in preparation for the realization of the EIC. The effort aims to provide the basis for further development of concepts for experimental equipment best suited for the science needs, including the importance of two complementary detectors and interaction regions. This report consists of three volumes. Volume I is an executive summary of our findings and developed concepts. In Volume II we describe studies of a wide range of physics measurements and the emerging requirements on detector acceptance and performance. Volume III discusses general-purpose detector concepts and the underlying technologies to meet the physics requirements. These considerations will form the basis for a world-class experimental program that aims to increase our understanding of the fundamental structure of all visible matter
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