1,183,424 research outputs found
On the Higgs cross section at NLO+NLL and its uncertainty
We consider the inclusive production of a Higgs boson in gluon-fusion and we
study the impact of threshold resummation at next-to-next-to-next-to-leading
logarithmic accuracy (NLL) on the recently computed fixed-order prediction
at next-to-next-to-next-to-leading order (NLO). We propose a conservative,
yet robust way of estimating the perturbative uncertainty from missing higher
(fixed- or logarithmic-) orders. We compare our results with two other
different methods of estimating the uncertainty from missing higher orders: the
Cacciari-Houdeau Bayesian approach to theory errors, and the use of algorithms
to accelerate the convergence of the perturbative series. We confirm that the
best convergence happens at , and we conclude that a
reliable estimate of the uncertainty from missing higher orders on the Higgs
cross section at 13 TeV is approximately %.Comment: 27 pages, 6 figures. Version to be published in JHE
Strange Quark PDFs and Implications for Drell-Yan Boson Production at the LHC
Global analyses of Parton Distribution Functions (PDFs) have provided
incisive constraints on the up and down quark components of the proton, but
constraining the other flavor degrees of freedom is more challenging.
Higher-order theory predictions and new data sets have contributed to recent
improvements. Despite these efforts, the strange quark PDF has a sizable
uncertainty, particularly in the small x region. We examine the constraints
from experiment and theory, and investigate the impact of this uncertainty on
LHC observables. In particular, we study W/Z production to see how the s-quark
uncertainty propagates to these observables, and examine the extent to which
precise measurements at the LHC can provide additional information on the
proton flavor structure.Comment: 14 pages, 11 figures, added reference
Precise Prediction for M_W in the MSSM
We present the currently most accurate evaluation of the W boson mass, M_W,
in the Minimal Supersymmetric Standard Model (MSSM). The full complex phase
dependence at the one-loop level, all available MSSM two-loop corrections as
well as the full Standard Model result have been included. We analyse the
impact of the different sectors of the MSSM at the one-loop level with a
particular emphasis on the effect of the complex phases. We discuss the
prediction for M_W based on all known higher-order contributions in
representative MSSM scenarios. Furthermore we obtain an estimate of the
remaining theoretical uncertainty from unknown higher-order corrections.Comment: 38 pages, 25 figures. Minor corrections, additional reference
Supersymmetric top and bottom squark production at hadron colliders
The scalar partners of top and bottom quarks are expected to be the lightest
squarks in supersymmetric theories, with potentially large cross sections at
hadron colliders. We present predictions for the production of top and bottom
squarks at the Tevatron and the LHC, including next-to-leading order
corrections in supersymmetric QCD and the resummation of soft gluon emission at
next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order
corrections on total cross sections and transverse-momentum distributions, and
provide an estimate of the theoretical uncertainty due to scale variation and
the parton distribution functions.Comment: 29 pages, 6 figure
How useful are historical data for forecasting the long-run equity return distribution?
We provide an approach to forecasting the long-run (unconditional) distribution of equity returns making optimal use of historical data in the presence of structural breaks. Our focus is on learning about breaks in real time and assessing their impact on out-of-sample density forecasts. Forecasts use a probability-weighted average of submodels, each of which is estimated over a different history of data. The paper illustrates the importance of uncertainty about structural breaks and the value of modeling higher-order moments of excess returns when forecasting the return distribution and its moments. The shape of the long-run distribution and the dynamics of the higher-order moments are quite different from those generated by forecasts which cannot capture structural breaks. The empirical results strongly reject ignoring structural change in favor of our forecasts which weight historical data to accommodate uncertainty about structural breaks. We also strongly reject the common practice of using a fixed-length moving window. These differences in long-run forecasts have implications for many financial decisions, particularly for risk management and long-run investment decisions.density forecasts, structural change, model risk, parameter uncertainty, Bayesian learning, market returns
How useful are historical data for forecasting the long-run equity return distribution?
We provide an approach to forecasting the long-run (unconditional) distribution of equity returns making optimal use of historical data in the presence of structural breaks. Our focus is on learning about breaks in real time and assessing their impact on out-of-sample density forecasts. Forecasts use a probability-weighted average of submodels, each of which is estimated over a different historyof data. The paper illustrates the importance of uncertainty about structural breaks and the value of modeling higher-order moments of excess returns when forecasting the return distribution and its moments. The shape of the long-run distribution and the dynamics of the higher-order moments are quite different from those generated by forecasts which cannot capture structural breaks. The empirical results strongly reject ignoring structural change in favor of our forecasts which weight historical data to accommodate uncertainty about structural breaks. We also strongly reject the common practice of using a fixed-length moving window. These differences in long-run forecasts have implications for many financial decisions, particularly for risk management and long-run investment decisions.density forecasts, structural change, model risk, parameter uncertainty, Bayesian learning, market returns
Higher-order QED corrections to W-boson mass determination at hadron colliders
The impact of higher-order final-state photonic corrections on the precise
determination of the W-boson mass at the Tevatron and LHC colliders is
evaluated. In the presence of realistic selection criteria, the shift in the W
mass from a fit to the transverse mass distribution is found to be about 10 MeV
in the channel and almost negligible in the
channel. The calculation, which is implemented in a Monte Carlo event generator
for data analysis, can contribute to reduce the uncertainty associated to the W
mass measurement at future hadron collider experiments.Comment: 9 pages, 2 figures, 1 table, RevTe
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Permanent trading impacts and bond yields
We analyze four years of transaction data for euro-area sovereign bonds traded on the MTS electronic platforms. In order to measure the informational content of trading activity, we estimate the permanent price response to trades. We find not only strong evidence of information asymmetry in sovereign bond markets, but we also show the relevance of information asymmetry in explaining the cross-sectional variations of bond yields across a wide range of bond maturities and countries. Our results confirm that trades of more recently issued bonds and longer maturity bonds have a greater permanent effect on prices. We compare the price impact of trades for bonds across different maturity categories and find that trades of French and German bonds have the highest long-term price impact in the short maturity class whereas trades of German bonds have the highest permanent price impacts in the long maturity class. More importantly, we study the cross-section of bond yields and find that after controlling for conventional factors, investors demand higher yields for bonds with larger permanent trading impact. Interestingly, when investors face increased market uncertainty, they require even higher compensation for information asymmetry
On the Higgs cross section at N3LO+N3LL and its uncertainty
open4noWe consider the inclusive production of a Higgs boson in gluon-fusion and we study the impact of threshold resummation at next-to-next-to-next-to-leading logarithmic accuracy (N3LL) on the recently computed fixed-order prediction at next-to-next-to-next-to-leading order (N3LO). We propose a conservative, yet robust way of estimating the perturbative uncertainty from missing higher (fixed- or logarithmic-) orders. We compare our results with two other different methods of estimating the uncertainty from missing higher orders: the Cacciari-Houdeau Bayesian approach to theory errors, and the use of algorithms to accelerate the convergence of the perturbative series, as suggested by David and Passarino. We confirm that the best convergence happens at μR = μF = mH/2, and we conclude that a reliable estimate of the uncertainty from missing higher orders on the Higgs cross section at 13 TeV is approximately ±4%.openMarco Bonvini; Marzani S; Claudio Muselli; Luca RottoliMarco, Bonvini; Marzani, Simone; Claudio, Muselli; Luca, Rottol
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