# HP2.6 High Precision for Hard Processes 6

Europe/Zurich
ICAS-UNSAM, Buenos Aires, Argentina

#### ICAS-UNSAM, Buenos Aires, Argentina

Buenos Aires, Argentina
Description

The 6th Workshop on "High Precision for Hard Processes" (HP2) will be held from September 6 (Tuesday) to September 9 (Friday), 2016 at ICAS-UNSAM, a research and conference center recently created in Buenos Aires, Argentina.

This is the sixth workshop of this series, which is devoted to high-precision studies of hard-scattering processes at hadron colliders. The main themes of these workshops are recent developments and new results on theory and phenomenology of hard-scattering processes within the Standard Model and its extensions.

Topics covered at HP2.6 include

• Phenomenological results on hard-scattering cross sections at high perturbative orders
• Automated methods to compute multi-leg amplitudes at tree and loop level
• Matching Monte Carlo event generators with fixed order calculations
• Status reports and implications of current LHC results
• Precision in Beyond the Standard Model physics phenomenology and other related subjects.

A fee of 200 Euro will be charged, covering lunches, coffee breaks and a great "asado".

Please find nome news and local information here

Participants
• Achillefs Lazopoulos
• Alejandro Szynkman
• Alexey Yushkov
• Andrea Pelloni
• Andres Daniel Perez
• Ben Page
• Ben Ruijl
• Carlos García Canal
• Caterina Specchia
• Chris Wever
• Cintia Willemyns
• Daniel E. LOPEZ-Fogliani
• Daniel Enrique de Florian
• Davide Pagani
• Dieter Zeppenfeld
• Eleni Vryonidou
• Epele Manuel
• Ernesto Arganda
• Ezequiel Alvarez
• Fabio Maltoni
• Fulvio Piccinini
• Gabriel Abelof
• Gavin Salam
• German Rodrigo
• German Sborlini
• Gino Marceca
• Giuseppe Bevilacqua
• Gonzalo Lucero
• Gustavo Otero Y Garzon
• Hayk Sargsyan
• Ignacio Fabre
• Jan Niehues
• Javier Mazzitelli
• Jonas Lindert
• Jonathan Bossio
• Jonathan Gaunt
• Leandro Cieri
• Leandro Da Rold
• Lily Asquith
• Lorenzo Magnea
• Manuel Der
• Marco Zaro
• Maria Florencia Daneri
• Maria Roberta Devesa
• Mariel Estevez
• Marius Wiesemann
• Massimiliano Grazzini
• Matias Perlin
• Max Zoller
• Nerina Fidanza
• Nicolás Mileo
• Ricardo Piegaia
• Roberto Morales
• Rodolfo Sassot
• Roger Hernandez-Pinto
• Salinas Ibañez Monica
• Simone Lionetti
• Tiziano Camporesi
• Yamila Rotstein Habarnau
• Tuesday, 6 September
• 10:00 12:00
Registration 2h

Registration at Building Labocluster

• 12:00 13:15
Lunch 1h 15m
• 13:15 13:35
Introduction 20m
• 13:35 14:05
Recent developments in VBFNLO 30m
Speaker: Dieter Zeppenfeld
• 14:05 14:35
Probing anomalous Higgs self couplings via single Higgs production at the LHC 30m

The Higgs self-coupling is still a missing piece in the Standard Model puzzle. Although its theoretical value can be extracted from its relation to the mass of the Higgs and the Fermi constant, its measurement via double Higgs production is particularly challenging. We explore the possibility of probing an anomalous trilinear coupling indirectly, through the production and decay of a single Higgs boson. Indeed, although these processes do not depend on this coupling at tree level, they are sensitive to the Higgs self-coupling at NLO. This gives us the opportunity to derive current and possible future constraints on the trilinear coupling from precise measurements of various observables of the different single-Higgs production channels.

Speaker: Davide Pagani
• 14:35 15:05
Vacuum stability in the SM: Towards a four-loop precision analysis 30m

During the last years the question of the stability of the vacuum state in the Standard Model extended up to high scales has become an exciting topic for precision physics since for the currently measured Higgs and top mass values the electroweak vacuum seems to be located close to the border between stability and metastability.

The effective Higgs potential, which characterizes all possible vacuum states, is closely connected to the evolution of the couplings and field strengths in the theory. This evolution is described by beta functions and anomalous dimensions. The state of the art discussion of vacuum stability in the SM involves the full set of three-loop beta functions in the MSbar-scheme and the matching of experimentally measured quantities to MSbar parameters at two-loop accuracy.
Now the leading contributions to the beta function for the strong coupling [JHEP 1602 (2016) 095], the top-Yukawa coupling and the Higgs self-coupling [paper in preparation] are available at four-loop level which constitutes a first step towards a full calculation of the gauge coupling beta functions at this precision.

In this talk we briefly review the vacuum stability problem in the SM and present the latest four-loop results for the most important beta functions connected to this problem as well as their impact on the stability of the electroweak vacuum state. Furthermore, a comparison of the most important sources of uncertainty will be given.
Finally, a few technical issues will be discussed such as the treatment of gamma_5 matrices in dimensional regularization which is the main limitation towards a full four-loop beta-functions and three-loop on-shell to MSbar matching discussion of this problem.

Speaker: Max Zoller (UZH)
• 15:05 15:35
Coffee Break 30m
• 15:35 16:05
Higgs Pair Production 30m
Speaker: Javier Mazzitelli (Universidad de Buenos Aires (AR))
• 16:05 16:35
Tackling differential distributions for Higgs production at higher orders 30m
Speaker: Simone Lionetti (ETHZ - ETH Zurich)
• 21:30 23:30
Social Event Suggested 2h

We suggest dinner, tango lesson and tango practice+show at La Catedral (Sarmiento 4006, upstairs).

• Wednesday, 7 September
• 09:00 09:30
Measurements of the production of prompt photons, jets and vector bosons+jets in pp collisions with the ATLAS detector 30m
Speaker: Lily Asquith (University of Sussex (UK))
• 09:30 10:00
Recent highlights of inclusive single boson and multiboson measurements with the ATLAS detector 30m
Speaker: Gustavo Otero Y Garzon (Universidad de Buenos Aires (AR))
• 10:00 10:30
The Pentabox Master Integrals with the Simplified Differential Equations approach 30m

We present the calculation of massless two-loop Master Integrals relevant
to five-point amplitudes with one off-shell external leg and derive the
complete set of planar Master Integrals with five on-mass-shell legs,
that contribute to many $2\to 3$ amplitudes of interest at the LHC,
as for instance three jet production, $\gamma, V, H +2$ jets etc.,
based on the Simplified Differential Equations approach.

Speaker: Chris Wever (Karlsruhe Institute of Technology)
• 10:30 11:00
Coffee Break 30m
• 11:00 11:30
One loop more: 4 and 5 loop physics 30m

For many processes at the LHC, there is an ever growing need for precision predictions. To this end, we created Forcer, a program that computes 4-loop massless propagator diagrams. Forcer solves IBP identities parametrically, which allows us to calculate processes beyond the reach of Laporta methods. We will show some recent results for 4-loop splitting functions. Finally, we will show a method to extend our program to include certain 5-loop calculations.

Speaker: Ben Ruijl (Nikhef)
• 11:30 12:00
Unsubtraction in the IR 30m

Recent developments of the loop-tree duality method.

Speaker: German Rodrigo (CSIC)
• 12:00 12:30
Aspects of the Unitarity Approach for loop amplitudes in QCD 30m
Speaker: Benjamin Page (University of Freiburg)
• 12:30 13:45
Lunch 1h 15m
• 13:45 14:15
Higher-order EWK corrections for W mass determination at hadron colliders 30m

One of the precision physics goals at the LHC is the direct determination
of the W mass through single W production, with a total uncertainty competitive
with the one obtained at Tevatron.
To this aim EWK corrections are an important source of theoretical systematics.
We present very recent developments on the calculation of higher order EWK, including
mixed EWK and QCD, corrections and their implementation in the POWHEG-BOX event generator
for Drell-Yan processes.

Speaker: Fulvio Piccinini (INFN Pavia)
• 14:15 14:45
NP in the ttbb final state at the LHC 30m
Speaker: Mariel Estevez
• 14:45 15:15
Probing the pseudoscalar top-Higgs coupling through CP-odd observables 30m
Speaker: Nicolas Ismael Mileo (Universidad Nacional de La Plata (AR))
• 15:15 15:45
Coffee Break 30m
• 15:45 16:15
Accurate predictions for charged Higgs boson production at the LHC 30m

A deep understanding of the Higgs sector is one of the paramount aims of the LHC, and in particular of the Run II. The evidence of extra, possibly charged, Higgs bosons would be a clear sign of physics beyond the Standard Model. In this talk, I will review the recent progresses in simulating charged Higgs boson production at the LHC, focusing on the cases of an intermediate-mass and a heavy charged Higgs boson in the two-Higgs-doublet-model. I will discuss the computation of NLO corrections to the total cross-section for the former, and how to perform a reliable fully-differential simulation for the latter.

Speaker: Marco Zaro (LPTHE Jussieu, Paris)
• 16:15 16:45
LHC phenomenology of a composite Higgs 30m
Speaker: Leandro Da Rold (C)
• 21:30 23:30
Social Event Suggested 2h

We suggest dinner, tango lesson and tango practice+show at La Viruta (Armenia 1366).

• Thursday, 8 September
• 09:00 10:00
Results from CMS 1h
Speaker: Tiziano Camporesi (CERN)
• 10:00 10:30
Top-antitop + jet production with off-shell effects at NLO QCD 30m

We present results for the NLO QCD corrections to the process $pp \to t\bar{t} j \to W^+W^-b\bar{b} j \to e^+ \nu_e \mu^- \bar{\nu}_\mu b \bar{b} j + X$, including complete off-shell effects for top quarks and W bosons: double-, single- and non-resonant contributions at the order (\alpha_{s}^4 \alpha^4). We discuss results of total and differential cross sections of interest for the LHC Run I and II.

Speaker: Dr Giuseppe Bevilacqua (MTA-DE Particle Physics Research Group, University of Debrecen)
• 10:30 11:00
Coffee Break 30m
• 11:00 11:30
An NLO+PS generator for top-pair and Wt production and decay including non-resonant and interference effects 30m

see Summary

Speaker: Jonas Lindert
• 11:30 12:00
Precision in EFT studies for top-quark physics 30m

In this talk I review recent progress in the computation of processes involving top quarks in the framework of Standard Model Effective Theory (SMEFT) at NLO in QCD. In particular I will discuss the impact of QCD corrections on top pair production, single top production, and top pair production in association with a photon, a Z boson and a Higgs in the presence of higher-dimensional operators. Results are obtained within MadGraph5_aMC@NLO.

Speaker: Eleni Vryonidou (Universite catholique de Louvain)
• 12:00 12:30
Speaker: Lorenzo Magnea (Universita e INFN (IT))
• 12:30 13:45
Lunch 1h 15m
• 13:45 14:15
NNLL soft and Coulomb threshold resummation for squark and gluino production at the LHC​ 30m

In this talk I will present improved predictions for the production cross sections of squark and gluino pairs at the LHC at 13 and 14 TeV. Our results incorporate a combined resummation of soft logarithms and Coulomb singularities at NNLL order, including bound-state corrections and also annihilation contributions that were first reported on in arXiv:1312.6279 for top pair production, and extended in our work to squark and gluino production. The corrections dominate the threshold region of the partonic cross section and are resummed directly in momentum space using an effective-theory framework based on SCET and pNRQCD. The combined resummation of soft and Coulomb corrections lead to enhancements of up to 80% compared to the fixed-order NLO result at 13/14 TeV for gluino-gluino production, and 10-40% for squark-antisquark, squark-squark and squark-gluino production. The theoretical uncertainty of the cross sections is typically reduced to about \pm 5-10% for all four processes. The finite widths of the squarks and gluinos have a small, negligible effect on the soft and Coulomb corrections of the total SUSY production cross section.

Speaker: Chris Wever (Karlsruhe Institute of Technology)
• 14:15 14:45
Transverse momentum resummation for diphotons at LHC 30m

After briefly introducing the b-space transverse momentum (qT) resummation formalism in the context of hadron collisions, I will show the latest predictions (at improved NNLO) for the qT spectrum, and other spectra, of diphoton pairs at the LHC and compare them to the experimental results. Besides restoring the predictivity of the perturbative QCD prediction at low qT, resummation improves the overall agreement of the theoretical prediction with the data. I will highlight some of the useful features of the employed formalism, such as its flexibility and universality.

Speaker: Francesco Coradeschi (INFN - National Institute for Nuclear Physics)
• 14:45 15:15
Transverse-momentum resummation for heavy-quark production at hadron colliders 30m

I discuss the all-order transverse momentum resummation structure for the hadroproduction of heavy-quark pairs. I present some numerical results for the resummed qT spectrum of heavy-quark pairs at next-to-leading logarithmic (NLL) order. I also discuss the azimuthal correlations produced by soft parton radiation, which are entangled with those that are produced by initial-state collinear radiation. The knowledge of the small-qT limit of the transverse-momentum cross section enables us to perform a fully exclusive fixed-order calculation up to NNLO in the framework of qT-subtraction method. I present the results of our first calculation which is accurate up to NLO in QCD perturbation theory and it includes all the flavour off-diagonal partonic channels at NNLO.

Speaker: Hayk Sargsyan (University of Zurich)
• 15:15 15:45
Coffee Break 30m
• 15:45 16:15
Mixed QCD-QED corrections to the AP splitting functions 30m

In this talk, we review recent results on the computation
of electroweak (EW) corrections to the Altarelli-Parisi (AP) kernels. In
particular, we consider QED effects, and we obtain the O($\alpha \, \alpha_{\rm S}$) and O($\alpha^2$) corrections to the double collinear splitting
functions. For this purpose, we analyse mixed QCD-QED
effects in the DGLAP evolution equations and their implications in the
evolution of PDFs. The results presented here are a crucial ingredient to
perform a full NLO QCD-QED analysis of PDF, as well as to compute hadronic
cross-sections with a full NNLO QCD-QED precision.

Speaker: German Sborlini (IFIC (UV-CSIC))
• 16:15 16:45
A precise determination of the photon PDF 30m

The talk will present the contents of https://arxiv.org/abs/1607.04266

Speaker: Gavin Salam (CERN)
• 20:30 22:30
Social event suggested 2h

We suggest pizza dinner at Guerrin (Av. Corrientes 1368)

• Friday, 9 September
• 09:00 09:30
Fully differential NNLO(+NNLL) computations with MATRIX 30m

We present a general framework for the fully differential computation
of NNLO corrections as well as the analytical transverse momentum
resummation through NNLL for the production of colorless particles.
Employing the p_T-subtraction and resummation methods in an automated
form, MATRIX provides the first NNLO(+NNLL) process library and includes
a number of single- and di-boson production processes. Recent physics
applications such as WW and WZ production at NNLO are discussed in detail.

Speaker: Marius Wiesemann (Universitaet Zuerich (CH))
• 09:30 10:00
Diphoton production at the LHC 30m

We review selected theoretical results for diphoton production at the LHC concerning Standard Model studies and new physics searches, at the light of the recent 750 GeV excess.

Speaker: Leandro Cieri (University of Zürich (UZH))
• 10:00 10:30
N-jettiness subtractions for NNLO QCD calculations 30m
Speaker: Jonathan Gaunt (DESY)
• 10:30 11:00
Coffee Break 30m
• 11:00 11:30
Single-inclusive jet production in electron-nucleon collisions at NNLO 30m

I will discuss the O(α^2*αs^2) perturbative corrections to inclusive jet production in electron-nucleon collisions. This process is of particular interest to the physics program of a future Electron Ion Collider (EIC). Our calculation uses the N-jettiness subtraction scheme for performing higher-order computations, and allows for a completely differential description of the deep-inelastic scattering process. I will describe the application of this method to inclusive jet production in detail, and present phenomenological results for the proposed EIC.

Speaker: Dr Gabriel Abelof (Argonne National Laboratory)
• 11:30 12:00
NNLO dijet production in DIS with the antenna subtraction method 30m

NNLO dijet calculation in DIS with the antenna subtraction method.

Speaker: Jan Niehues (University of Zurich)
• 12:00 12:30
Status and future of precise predictions with MC 30m
Speaker: Fabio Maltoni (Universite Catholique de Louvain (UCL) (BE))
• 12:30 15:00