We present fits to determine parton distribution functions (PDFs) using a diverse set of measurements from the ATLAS experiment at the LHC, including inclusive W and Z boson production, ttbar production, W+jets and Z+jets production, inclusive jet production and direct photon production. These ATLAS measurements are used in combination with deep-inelastic scattering data from HERA. Particular...
I will review recent results on the inclusion of small-x resummation in PDF fits, with emphasis on where we are and where we can/shall go in future, especially in the light of future higher energy colliders and improved theoretical accuracy.
I will present some recent developments in the understanding of
theoretical and experimental uncertainties in PDFs, with special
emphasis on the features of NNPDF 4.0, the regularisation of
experimental covariance matrices and the propagation of matched scale
uncertainties.
Transverse momentum dependent (TMD) parton distributions in a proton
are important in high energy physics from both theoretical and phenomenological
points of view. Using the latest LHC data on the inclusive soft hadron production at small
transverse momenta, we determine the parameters of the initial TMD gluon density,
derived within the soft QCD model at the low scale $\mu_0 \sim 1 -...
Precise theoretical predictions of QCD scattering and radiation
processes are fundamental building blocks for the LHC precision
program. Fixed-order computations must be supplemented by all-order
resummations where logarithmically-enhanced contributions become
large. Among those, small-$x$ logarithms are enhanced when the ratio,
$x=\frac{Q^2}{S}$ between the typical energy scale of a...
The predictions for the atmospheric neutrino flux at high energies strongly depend on the contribution of prompt neutrinos, which are determined by the production of charmed mesons in the atmosphere at extremely high energies and very forward rapidities. Study of charm production in the far-forward directions requires to deal with a very asymmetric kinematics configuration with extremelly...
o calculate the PDFs from first principles in Lattice gauge theories it is convenient to considerthe Ioffe-time distribution defined through gauge-invariant bi-local operators with spacelike separa-tion. Lattice calculations provide values for a limited range of the distance separating the bi-localoperators. In order to perform the Fourier transform and obtain the pseudo- and the quasi-PDFs,it...
In this talk I’ll explain how new physical results in 4D (N=2) supersymmetric matter gauge theories can be found by connecting them to 2D quantum integrable models. In particular, we set up an identification between the basic mathematical and physical objects of the two kind of theories (the Q, Y and T functions of integrability and the periods and masses of the gauge theories) and from this a...
The double differential cross sections of the Drell--Yan lepton pair ($\ell^+\ell^-$, dielectron or dimuon) production, as functions the invariant mass $m_{\ell\ell}$, transverse momentum $p_\mathrm{T}(\ell\ell)$, and
$\varphi^*$, are measured. The $\varphi^*$ observable is highly correlated with
$p_\mathrm{T}(\ell\ell)$ and is used to probe the low-$p_\mathrm{T}(\ell\ell)$
region in a...
On behalf of the ZEUS Collaboration.
Submitted to JHEP.
The exclusive photoproduction reactions gamm p -> J/psi(1S) p and gamma p -> psi(2S) p have been measured at an ep centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb-1. The measurement was made in the kinematic range 30 < W < 180 GeV, Q^2 < 1 GeV^2 and |t| < 1 GeV^2, where W is the...
Correlations between charged particles provide important insight about hadronization process. The analysis of the momentum difference between charged hadrons in pp, p-lead, and lead-lead collisions of various energies is performed in order to study the dynamics of hadron formation. The spectra of correlated hadron chains are explored and compared to the predictions based on the quantized...
We present a phenomenological analysis of events with two high transverse momentum jets separated by a large (pseudo-)rapidity interval void of particle activity, also known as jet-gap-jet events. In the limit where the collision energy is much larger than any other momentum scale, the jet-gap-jet process is described in terms of perturbative pomeron exchange between partons within the...
On behalf of the H1 and ZEUS Collaborations.
Eur. Phys. J. C82 (2022) 243
The HERAPDF2.0 ensemble of parton distribution functions (PDFs) was introduced in2015. The final stage is presented, a next-to-next-to-leading-order (NNLO) analysis of theHERA data on inclusive deep inelasticepscattering together with jet data as published bythe H1 and ZEUS collaborations. A perturbative QCD fit,...
The LHCb detector is able to probe kinematic coverage at low Bjorken-x down to 1e-5 or lower due to its forward rapidity coverage. In this talk, studies of vector boson and hadron production in proton-proton and proton-lead collisions are presented. The Z boson events are used to probe the proton structure while a relatively unknown low-x region is studied with charged and neutral hadron...
On behalf of the ZEUS Collaboration.
A new measurement of inclusive jet cross sections in neutral current deep inelastic scattering using the ZEUS detector at the HERA collider is obtained. The data were taken at HERA2 at a center of mass energy of 318 GeV and correspond to an integrated luminosity of 347 pb-1. Massless jets, reconstructed using the k_T-algorithm in the Breit reference...
Single, double and central diffractive dissociation of protons is studied at high energies in a Regge-pole model. The main premises are: 1) Regge factorization, 2) inelastic vertices identified with DIS SFs, 3) Duality relation between high- and low missing masses, 4) Non-linear, complex Regge trajectories, updated.
The new results concern: 1) the dip-bump structure in the differential...
We review the computation of anomalous dimensions in planar N=4 super Yang-Mills theory from an integrable system, i.e. AdS_5/CFT_4 ''integrability''. We then introduce the hexagon operator originally designed by Basso, Komatsu, and Vieira for three-point functions. It is argued that four- and higher-point functions can be studied using hexagon tessellations. A ''gluing prescription'' for the...
I present prediction for cross section of Mueller-Tang jets (jet-gap-jet) processes at LHC, obtained by using the BFKL approach, where both impact factors and gluon Green functions are calculated in the next-to-leading logarithmic approximation (NLLA). I discuss also the issue of the validity of the standard BFKL factorization for such processes, and show that the actual violation is small,...
