Regular Series


Vol. 38 (2007), No. 7, pp. 2229 – 2403


Measurement of \(W\) and \(Z\) Properties at the LHC

abstract

With our current knowledge limited by the absence of physics data, I review our expectations from standard processes measurements at the LHC. Focusing on charged and neutral current processes, I illustrate how their measurement will constrain our uncertainties on discovery physics, and give some arguments about our precision goal for the \(W\) mass measurement. Detailed analysis reveals that there is no reason to believe we can not measure this fundamental parameter to about 5 MeV, most uncertainties (of both experimental and theoretical source) being constrained by a detailed measurement of \(Z\) production.


Infrared Evolution Equations: Method and Applications

abstract

It is a brief review on composing and solving Infrared Evolution Equations. They can be used in order to calculate amplitudes of high-energy reactions in different kinematic regions in the double-logarithmic approximation.


LHC Event Generation with Herwig++

abstract

We report on progress with the new Monte Carlo event generator Herwig++. The chain of event simulation is briefly outlined and details on current developments, particularly in the framework of Herwig++ are given.


Higgs Amplitudes from Twistor Inspired Methods

abstract

We illustrate the use of new on-shell methods, 4-dimensional unitarity cuts combined with on-shell recursions relations by computing the \(A_4^{(1)} (\phi ,1^-,2^-,3^+,4^+)\) amplitude in the large top mass limit where the Higgs boson couples to gluons through an effective interaction.


Bearing Standard Model Benchmarks to the LHC

abstract

I discuss the importance of understanding Standard Model predictions and results at the LHC during the early running.


Towards New Monte Carlo (QCD + EW) for \(W/Z\) Production at LHC

abstract

An effort of formulating, implementing and testing new parton shower Monte Carlo for \(W\)/\(Z\) production at Large Hadron Collider (LHC) is presented. In particular, it is indicated how to construct a constrained Monte Carlo (CMC) parton shower algorithm implementing the CCFM-like evolution for a single hadron beam and how to combine two such CMCs into the single MC simulating initial state QCD radiation. Preliminary numerical results are presented.


Transverse Momentum Distributions for the Standard Model Boson Production at the LHC

abstract

In this talk we discuss selected topics concerning calculations of transverse momentum distributions for the Standard Model boson production at the LHC.


Diffractive Structure Function \(F_{\rm L}^{\rm D}\) from the Analysis with Higher Twist

abstract

We make predictions for the diffractive longitudinal structure function \(F_{\rm L}^{\rm D}\) to be measured at HERA, based on the DGLAP fits of diffractive parton distributions with an additional twist-4 term. This term describes the diffractive \(q\bar {q}\) production from longitudinal photons. The twist-4 contribution significantly changes predictions for \(F_{\rm L}^{\rm D}\) obtained in the pure DGLAP analysis.


Recursive Equations for Arbitrary Scattering Processes at Tree Order and Beyond

abstract

The usefulness of recursive equations to compute scattering matrix elements for arbitrary processes is reviewed. The importance of the recently presented reduction method at the integrand level that opens the possibility to use efficiently recursive equations for one-loop amplitude and cross sections, is also briefly discussed.


all authors

G. Balossini, G. Montagna, C.M. Carloni Calame, M. Moretti, M. Treccani, O. Nicrosini, F. Piccinini, A. Vicini

Precision Predictions and Tools for Weak Boson Production at the LHC

abstract

Precision studies of weak boson production at the LHC require that electroweak and QCD higher-order corrections are simultaneously taken into account in data analysis. After a review of the present status of higher-order calculations for single \(W\) and \(Z\) boson production at hadron colliders, we present some preliminary results on the combination of electroweak and QCD corrections to a sample of observables of the process \(p p \to W^\pm \to \mu ^\pm + X\) at the LHC. Our phenomenological analysis shows that a high-precision knowledge of QCD and a careful combination of electroweak and strong contributions is mandatory in view of the anticipated experimental accuracy.


Solving the QCD NLO Evolution Equations with a Markovian Monte Carlo

abstract

We discuss precision Monte Carlo (MC) calculations for solving the QCD evolution equations up to the next-to-leading-order (NLO) level. They employ forward Markovian Monte Carlo algorithms, which provide rigorous solutions of the above equations. These algorithms are implemented in the form of the Monte Carlo program EvolFMC. This program has been cross-checked with independent, non-MC, programs (QCDNum16 and APCheb33) and the numerical agreement at the level of \(0.1\%\) has been found.


QCD ISR Monte Carlo with \(\alpha (k_{\rm T})\)

abstract

We present a description of a Monte Carlo algorithm that solves the modified DGLAP-type evolution equation in QCD. The change with respect to normal DGLAP is in the form of the argument of the coupling constant. We consider primarily the CCFM-like form \(\alpha (k_{\rm T})\), but also a simpler choice \(\alpha (Q(1-z))\) is discussed. The evolution is performed in the rapidity space with strict rapidity ordering and no gaps in phase-space.


Matching Constrained Monte Carlo to NLO Matrix Element

abstract

We present a new method of matching the Constrained Monte Carlo (CMC) algorithm to next-to-leading order matrix elements. In such matching, one must simultaneously treat the infra-red singularities of the matrix element and double counting issues between the two contributions. In the proposed method these two issues are dealt with by a specially defined counterterm. This counterterm is analyzed in detail and the connection of the CMC algorithm and formal factorization theorems is given. This counterterm also allows many new processes to be quickly integrated into the algorithm as the application of the counterterm can be done at the matrix element generation level and all residual issues in the parton shower are universal.


QED\(\otimes \)QCD Resummation and Shower/ME Matching for LHC Physics

abstract

We present the theory of QED\(\otimes \)QCD resummation and its interplay with shower/matrix element matching in precision LHC physics scenarios. We illustrate the theory using single heavy gauge boson production at hadron colliders.


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