Within the framework of transverse-momentum-dependent factorization, we investigate for the first time the impact of a flavor-dependent intrinsic transverse momentum of quarks on the production of W bosons in hadronic collisions. We study the transverse-mass, lepton transverse momentum, and missing transverse momentum distributions of the W−decay products by means of a template-fit technique...
HCb provides unique opportunities to study W and Z boson production at forward rapidities at the LHC.
It has recently be suggested that a new measurement of the W boson mass by LHCb would complement measurements by ATLAS and CMS.
All measurements of the W mass at the LHC are susceptible to PDF uncertainties, but there would be a partial cancellation of the overall PDF uncertainty when the LHCb...
The electroweak sector of the Standard Model can be tested via precision measurements of fundamental observables. Measurements of the Drell-Yan production of Z bosons at the LHC provide a benchmark of our understanding of perturbative QCD and electroweak processes. The ATLAS collaboration has recently used such measurements to evaluate the effective leptonic weak mixing angle using data...
I would like to report on a calculation of inclusive Z boson production in proton-lead col-lisions at the LHC taking into account the transverse momenta of the initialpartons. We use the framework of kT-factorization combining transverse momentum dependent parton distributions (TMDs) with off-shell matrix elements.In order to do it we need to construct appropriate TMDs for...
Diboson measurements at the LHC require precision that can be reached only by state-of-the-art perturbative computations. In this talk, I will review the most important higher-order corrections to diboson processes and their consistent combination. This involves NNLO QCD corrections, NLO EW corrections and NLO QCD corrections to the loop-induced gg contribution, all of which are necessary to...
In this talk, we present a number of recent measurements of inclusive ZZ and Z𝛾 production in proton-proton collisions at √s=13 TeV at ATLAS. The unfolded differential cross section for ZZ->4l as a function of the four-lepton invariant mass is presented and compared to state-of-the-art Standard Model calculations. If available, an additional measurement of ZZ production will be presented for...
Measurements of electroweak boson pair production at the LHC constitute a stringent test of the electroweak sector and provide a model-independent means to search for new physics at the TeV scale. In this talk, we present recent results for inclusive WW and WZ production in proton-proton collisions at √s=13 TeV, including polarisation studies in the WZ final state. The precision measurements...
Measurements of multi-boson production at the LHC constitute precision tests of the Standard Model and unique probes of new physics through anomalous gauge couplings. These processes are also important backgrounds to Higgs measurements and searches for new particles. Relevant measurements from CMS are presented.
A search for the production of three massive vector bosons in WWW, WWZ and WZZ final states is presented, using proton-proton collision data collected by the ATLAS experiment at √s=13 TeV. The analysis utilises multiple search channels. WWW production is probed using a fully-leptonic decay channel, with three-charged leptons and missing transverse momentum, and a semi-leptonic decay channel...
The scattering of electroweak bosons tests the gauge structure of the Standard Model and is sensitive to anomalous quartic gauge couplings. In this talk, we present recent results on vector-boson scattering from the ATLAS experiment using proton-proton collisions at √s=13 TeV. This includes the observation of WZ and same-sign-WW production via vector-boson scattering along with a measurement...
In this talk we investigate how new physics effects can be
systematically included in the family of vector boson processes (VBF,
VBS, diboson), by means of the Standard Model Effective Field Theory
(SMEFT) parametrisation. We discuss which effects can be searched for in
LHC Run-2 and HL-LHC, and how this set of processes involving
electroweak vertices and very energetic jets can be used...
So far light-by-light scattering ($\gamma\gamma\to\gamma\gamma$) was not accessible for experiments because the corresponding cross section is rather low. Measurements of diphotons in ultra-peripheral collisions (UPCs) of lead-lead have been reported recently by the ATLAS [1] and CMS Collaborations [2]. Our theoretical results based on equivalent photon approximation in the impact parameter...
The production of vector bosons in association with jets is a stringent test of perturbative QCD and is a background process in searches for new physics. Total and differential cross-section measurements of vector bosons produced in association with jets in proton-proton collisions performed by the CMS collaboration at the LHC are presented. The measurements are compared to the predictions of...
Semi-inclusive deep inelastic scattering will be a crucial channel to extract transverse momentum dependent distributions at future colliders. In this context, we recently developed a framework that uses jets (instead of single hadrons) to achieve reduced sensitivity to final-state non-perturbative effects. Moreover, a suitable non-standard jet definition allows us to apply the factorization...
We study the ratio of the cross sections for t\bar{t}\gamma and t\bar{t} production at the LHC. We argue that, due to correlations between the theoretical uncertainties in the numerator and in the denominator, a very precise determination of this observable can be achieved at NLO QCD accuracy, with an uncertainty comparable to that of typical NNLO QCD computations. Thus, the ratio has an...
High Energy Jets (HEJ) provides all-order summation of the perturbative terms dominating the production of well-separated multiple jets at hadron colliders to leading log accuracy. We will present the first calculation of all the real next-to-leading high energy logarithms to the processes of pure jet and W-boson production in association with at least two jets. I will discuss the impact of...
We present measurements of differential jet cross sections over a wide range in transverse momenta from inclusive jets to multi-jet final states. Studies on the impact that these measurements have on the determination of the strong coupling alpha_s as well as on parton density functions are reported.
Most of the interesting physics at the LHC involves final states with hadronic jets. We present new Monte Carlo event generator configurations used by the ATLAS experiment to model multi-jet processes in pp collisions at 13 TeV. The different generators are compared to each other and to 13 TeV ATLAS measurements in kinematic distributions sensitive both to the kinematic of hard process and...
I present the longitudinal and transverse momentum distributions, two particle eta-phi correlations and azimuthal anisotropy (v2) of pions in jets of high mass, obtained in a newly developed fragmentation model [1-4]. In this model, the jet mass is used as the fragmentation scale, and the scale evolution is calculated in the phi^3 theory. The initial form of the fragmentation function at...
The production of jets at hadron colliders provides stringent tests of perturbative QCD. We present a measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations, using the quantity RΔϕ. This quantity specifies the fraction of the inclusive dijet events in which the azimuthal opening angle of the two jets with the highest transverse momenta is less than a...
We discuss the jet shape variable pull and in particular, we present a first-principle prediction for the pull angle, which can help to probe the colour flow between jets.
While the pull angle is not infra-red and collinear safe, it is Sudakov safe and therefore it can be calculated using all-order techniques, which share similarities to standard $Q_T$ resummation. We compare our result with...
Theoretical calculations for jet substructure observables with accuracy beyond leading-logarithm have recently become available. Such observables are significant not only for probing a new regime of QCD at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many searches for physics beyond the Standard Model. In this talk, we discuss a...
The production of hadronic jets in deep-inelastic lepton-proton scattering (DIS) is sensitive both
to the strong and electroweak sectors of the Standard Model and constitutes one of the most precise
probes to study the inner structure of the proton. It further provides crucial constraints on the
flavour composition of the proton and thus in the extraction of parton distribution functions.
I...
KaTie is a parton level event generator that can deal with space-like initial-state partons, which occur in factorization prescriptions for hadron scattering that involve non-vanishing momentum components transverse to scattering hadrons. Since recently, it is possible to perform calculations with KaTie for deep inelastic scattering, including the possibility for a space-like initial-state...
I present a new local, analytic scheme for the subtraction of infrared singularities at next-to-next-to-leading order (NNLO) in QCD, which aims at reducing the complexity of the problem and features remarkable aspects. It works for any infrared-safe observable, it benefits from the partition of the radiative phase-space into sectors, the subtraction counterterms are local and can be...
I will present recent development of a new kind of parton shower algorithm at the amplitude level. An application of such an algorithm to the flexible resummation of non-global observables beyond leading-N is discussed, and prospects to a full parton shower implementation are presented, as well.
We present a parton shower based on Transverse Momentum Dependent (TMD)
parton distributions obtained with the Parton Branching method. We investigate
how well the TMD parton shower reproduces the TMD parton distributions.
Applications of the TMD parton shower to LHC processes will be presented.
In this talk we review the project aiming and computing transverse-mementum-dependent splitting functions featuring correct collinear and high-energy limit that we started in refs. [arXiv:1711.04587, arXiv:1607.01507, arXiv:1511.08439]. At the moment we have obtained the real-emission parts of all the kernels (Pgg, Pgq, Pqg and Pqq) at LO. After introducing the methods used for defining and...
I would like to present application of Improved Transversal Momentum
Dependent factorization to description of measurement of dijets
production in forward rapidity region in p-p and p-Pb collisions.
Furthermore recent results on constructing Transversal Momentum
Dependent parton densities needed for calculation of 3 and for 4 jet
final states will be presented.
Recent observations at RHIC and the LHC of two- and multi-particle correlations in high multiplicity relativistic proton-proton and proton-ion collisions and similarity of the results to those observed in central heavy-ion collisions are often interpreted as an evidence for collective particle production in small collision systems. These results motivate a study in even smaller systems, such...
New CMS PYTHIA 8 event tunes are presented. The new tunes are obtained using minimum bias and underlying event observables exploiting Monte Carlo configurations with consistent parton distribution functions and strong coupling constant values in the matrix element and the parton shower, at leading order (LO), next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). Validation and...
$K\rightarrow \pi \nu \bar{\nu}$ is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the $K^{+}\rightarrow \pi^{+} \nu \bar{\nu}$ decay with 10\% precision. NA62 took data in 2015-2018; the analysis of a partial data set allows to reach the...
Final results of recent NA48/2 measurements are presented.
The charged kaon semileptonic form factors have been precisely measured from 4.4 million Ke3 and 2.3 million Kmu3 events collected in 2004.
In addition, the first observation of the K+- -> pi+- pi0 e+ e- decay is reported, with a sample of about 4900 candidates and less than 5% background.
The measured branching ratio in the full...
Gluon splitting to b-quark pairs is a unique probe of the properties of gluon fragmentation, as the identified b-tagged jets provide a proxy for the quark daughters of the initial gluon. We present a measurement of key differential distributions related to g→b bbar using data collected with the ATLAS detector at √s=13 TeV. Track jets are used to probe angular scales below the standard R=0.4...
