We assess the effect of QCD/QED interference effects in fixed color parton showers with tree level matrix element corrections.
Transverse Momentum Dependent (TMD) parton distribution is a very powerful concept for the description of low and high transverse momentum effects in high energy collisions. The Parton Branching (PB) method provides TMD distributions that can be used in parton shower simulations, as already implemented in CASCADE Monte Carlo event generator.
We develop a method, PS2TMD, that allows...
We present a study of intrinsic kt effects in DY production from very low DY masses up to the Z-boson mass, covering a large range of center-of-mass energies from \sqrt{s} = 40 GeV up to LHC energies.
The description of measurements from different experiments is studied with MCatNLO supplemented with Pythia8 as well as with Parton Branching TMDs.
An energy dependent intrinsic kt width is...
Particle-particle correlations, especially rapidity-rapidity correlations was already an important tool for hadron collider physics since the early 70s. Recently, we studied one-particle rapidity distributions and two-particle rapidity-rapidity correlations at hadron colliders revisiting one of the old models, the Chew-Pigniotti multiperipheral model and we were surprised to realize that the...
Double parton scattering (DPS) is the process in which one has two separate hard scatterings in an individual proton-proton collision. In recent years much progress has been made towards the proper description of this phenomenon in QCD, including a consistent description of perturbative splittings that yield the parton pair in one or both protons, and a coherent framework for combining both...
Recent measurements of the triple J/psi production performed by the CMS collaboration suggest non-negligible contribution from a triple parton scattering (TPS). The CMS results can be seen as a first experimental observation of a TPS process. Unfortunately, due to the absence of experimental fits, triple parton distribution functions (tPDFs), needed for the theoretical computation of TPS cross...
Double parton scattering (DPS) - the situation where two individual hard interactions happen during a single hadron-hadron collision - is sensitive to all sorts of correlations between two partons inside a hadron, e.g.~spin, colour, or spatial separation. Therefore DPS gives access to information about hadron structure not accessible in single parton scattering (SPS). This information is...
The production of lepton pairs at low invariant mass and finite transverse momentum resolves QCD dynamics at the boundary between the perturbative and non-perturbative domains. We investigate the impact of NNLO QCD corrections for the lepton pair transverse momentum distributions at energies corresponding to the BNL RHIC collider and to fixed-target experiments. Satisfactory perturbative...
The extraction of nonperturbative TMD physics is made challenging by prescriptions that shield the Landau pole, which entangle long- and short-distance contributions in momentum space. The use of different prescriptions then makes the comparison of fit results for underlying nonperturbative contributions meaningless on their own. We propose a model-independent method to restrict...
Fully differential measurements of the Semi-Inclusive DIS process with polarized beams provide important information on the three-dimensional structure of hadrons. In particular, azimuthal asymmetries of the fragmenting hadron probe interesting new correlations between partons in the hadronic system through novel hadronic distribution functions. In the framework of factorization for transverse...
The energy dependence of the total hadroproduction cross section for pseudoscalar quarkonia is computed via matching of the NLO Collinear-Factorisation (CF) results with Leading-Logarithmic resummation of higher-order corrections $\propto\alpha_s^{n}\ln^{n-1}(1/z)$ to the CF hard-scattering coefficient, where $z=M^2/\hat{s}$ with $\hat{s}$ being partonic center-of-mass energy squared. The...
Recent years have seen prominent progress in the first-principles calculation of transverse-momentum-dependent parton distributions (TMDs) from the so-called lattice TMDs, which are equal time correlators that include quasi-TMDs and those from the Lorentz-invariant approach. In this talk, I will show that the lattice TMDs and TMDs are related by a factorization formula which can be rigorously...
Motivated by the Kharzeev-Levin entropy formula which postulates a maximally entangled proton wave function in Deep Inelastic Scattering at low x, we investigate the proposed relation between parton number and final state hadron multiplicity. Contrary to the original formulation we propose to determine partonic entropy from the sum of gluon and quark distribution functions at low x, which we...
I present the recent studies of power corrections for the transverse momentum dependent (TMD) factorization. A particular emphasis is made on the novel method of TMD operator expansion that yields the TMD factorization theorem on the operator level. This method grants a systematic description of power corrections to TMD factorization, in particular, it naturally introduces the concept of...
We study isolated photon production in the Parton Reggeization Approach with NLO corrections originated from subprocesses of additional parton emissions. Two matching schemes are tested. The first one is based on Kt-ordering of emitted partons during Kt-depended evolution, the second one applies rapidity-ordering for factorization of real parton emissions. We compare our predictions for...
We perform explorative analyses of the 3D gluon content of the proton via a study of polarized T-odd gluon TMDs at leading twist, calculated in a spectator model for the parent nucleon. Our approach encodes a flexible parametrization for the spectator-mass density, suited to describe both moderate and small-x effects. All these prospective developments are relevant in the investigation of the...
The parton-branching solutions of QCD evolution equations have been recently
studied. From this approach, a method to construct both collinear and transverse
momentum dependent (TMD) parton densities has been formulated. In this
formalism, soft-gluon color coherence effects are taken into account by
introducing the soft-gluon resolution scale. Both analytical studies and
numerical...
In this talk, we describe the implementation of the kinematical constraint within the Langevin formulation of the JIMWLK equation following the proposal of Hatta and Iancu. We present stability and scaling tests and show first comparisons of the solutions without and with the improvement. We also comment on the rapidity evolution rate of the saturation radius.
In high-energy heavy-ion collisions, a quark-gluon plasma is produced. One way to study this exotic type of matter is to analyze the effect it has on high-energy partons traversing it. This leads to a rich phenomenology that commonly is referred to as jet quenching. High-energy partons propagating in the hot and dense medium mainly experience transverse momentum broadening which leads to...
We present a measurement of azimuthal correlations in Z+jet events measured by CMS at sqrt{s}=13 TeV. The measurements are compared to predictions at NLO using Pythia8 parton shower and hardonization as well as Parton Branching TMDs and TMD shower.
Predictions are given for the back-to-back configuration and a comparison of the prediction with measurements of multi-jets in the same kinematic...
We consider the production of $Z$ bosons associated with a heavy (charm and beauty) jet at the LHC energies using two scenarios based on the transverse momentum dependent (TMD) parton densities in the proton. First of them employs the Catani-Ciafaloni-Fiorani-Marchesini gluon evolution and is implemented into the Monte-Carlo event generator PEGASUS. The second scheme is based on the Parton...
Based on: Phys. Rev. D 104, 054039 (2021) [https://arxiv.org/abs/2105.13915]
The Leding-Logarithmic (LL) gluon Sudakov formfactor is derived from rapidity-ordered BFKL evolution with longitudinal-momentum conservation. This derivation further clarifies the relation between High-Energy and TMD-factorizations and can be extended beyond LL-approximation as well.
With the aim of targeting for clear signals of the stabilization of the high-energy resummation under higher-order corrections and energy-scale variation, we investigate the inclusive semi-hard production of two bottom-flavored hadrons, as well as a single bottom-flavored hadron accompanied by a light jet. Working within the hybrid high-energy and collinear factorization formalism, which...
We calculate single-logarithmic corrections to the small-$x$ flavor-singlet helicity evolution equations derived previously at the double-logarithmic approximation. The new single-logarithmic part of the evolution kernel sums up powers of $\alpha_s\ln(1/x)$, which are an important correction to the dominant powers of $\alpha_s\ln^2(1/x)$ summed up previously by the double-logarithmic kernel at...
We discuss Transverse Momentum Dependent (TMD) gluon distributions within high energy factorization at next-to-leading order in the strong coupling within the framework of Lipatov's high energy effective action. Unlike previous results obtained within high energy factorization, our framework allows to recover the complete anomalous dimension associated with Collins-Soper-Sterman (CSS)...
We discuss the measurement of gluon transverse momentum distribution (TMD) in dijet and heavy hadron pair (HHP) production in semi-inclusive deep inelastic scattering. The factorization of these processes in impact parameter space shows the appearance of a specific new soft factor matrix element on top of angular a complex valued anomalous dimensions. We show in detail how these features can...
We propose a novel way of studying the gluon number density (the so-called Weizsäcker-Williams gluon distribution) using the planned Electron Ion Collider. Namely, with the help of the azimuthal correlations between the total transverse momentum of the dijet system and the scattered electron, we examine an interplay between the effect of the soft gluon emissions (the Sudakov form factor) and...
Recently, jet measurements in deep-inelastic scattering (DIS) events close to Born kinematics have been proposed as a new probe to study transverse-momentum-dependent (TMD) PDFs, TMD fragmentation functions, and TMD evolution. In this talk, I will report measurements of lepton-jet momentum imbalance in high-Q2 DIS events collected with the H1 detector at HERA. These data bridge DIS...
The everyday practice of physicists is to a large extent determined by the scientific problems they are confronted with. The conceptual analysis of scientific problems and how they change, therefore, may allow for a fine-grained investigation of the development of a scientific discipline. In this talk I discuss what constitutes a scientific problem, what its elements are and how they change. I...
I will talk about track functions and TMD physics.
In the frameworks of $k_t$- and $(z, k_t)$-factorizations we discuss various TMDs (UPDFs) such as KMR, MRW, and PB which are based on the Sudakov form factor and the different angular ordering. The comparison is also made with the TMDlib and its possible extensions. The dependence of the above TMDs on input PDFs i.e. MSHT20, MMHT2014, CT14, etc are investigated. Finally, different processes...
We propose a system of evolution equations that describe in-medium time-evolution of transverse-momentumdependent quark and gluon fragmentation functions.
Furthermore, we solve this system of equations using Monte Carlo methods. We use the obtained solutions to construct observables that allow us to see
different behaviour of quark and gluon initiated final-state radiation, i.e. the...
For the first time, we study the differential cross section of the single inclusive ${e^ + }{e^ - }$ annihilation to the hadrons via $\gamma$-production, in the different ${k_{t}}$-factorization frameworks, using
the transverse momenta of the incoming partons, by apply the KMR and method to calculate the unintegrated parton fragmentation functions (UFFs) from the ordinary integrated...
We present our last work (2108.06419) on D and B-meson production in the kt-factorization approach. One of our goals is to emphasize the importance of using the same scheme for UPDFs and matrix elements. Our calculations, based on 2->2 processes computed in a general-mass variable-flavor-number scheme, are compared to ALICE and LHCb data. Finally, we discuss how the 2->1 process could be...
The extraction of TMD PDF includes PDF as input. In some recent extractions we have observed how the quality of the extraction depends on the selected PDF set. We show here how this problem, the PDF bias, is solved with a flavor dependent model for the non-perturbative TMD input.
We review the recent progress on the extraction of TMD PDFs and TMD FFs from global data of Semi-Inclusive Deep-Inelastic Scattering, Drell-Yan and Z boson production. Particular attention will be devoted to the effects of the increase in theoretical accuracy.
We investigate the TMD evolution contribution to jet production. Calculations of jet production at the LHC using the TMD merging method are presented. The predictions show very good agreement with the data over a wide kinematic range. Lower matching cone radii are preferred by jet events than Z + jets events.
We present a comparison of predictions obtained with PB TMDs (MG5-aMC+CA3(jj)NLO) with measurements in the back-to-back region.
The presentation is a result of the PB-TMD Monte Carlo school.
The speaker will be selected from the participants of the PB-TMD school.
In this talk, we will present our results on the soft gluon resummation in the dijet production processes where the total transverse momentum of the dijet is much smaller than the jet momentum.
I discuss the importance of pT resummation in fiducial cross sections at the LHC, using gluon-fusion Higgs production in the diphoton decay channel with fiducial cuts as an example. In particular, I discuss the treatment of fiducial power corrections that make the total cross section sensitive to small-pT resummation effects, and thereby enhance the N3LO correction. Integrating the resummed pT...
At the LHC, diphoton production constitutes the main background of Higgs production in the diphoton decay and of many new physics models predicting large-mass diphoton resonances. Underestimated theoretical uncertainties and large perturbative corrections have been a long-standing issue over the years with various suggestions. Especially the transverse momentum spectrum has lead to various...
Soft drop jet mass is an attractive candidate for precision measurements such as the top mass $m_t$ and the strong coupling constant $\alpha_s$, as it can be perturbatively calculable to high accuracy besides being more robust against nonperturbative and underlying event corrections. In this talk I will describe the prospects for the top mass and $\alpha_s$-determination at the LHC using soft...
We investigate the role of parton fragmentation processes for associated gauge boson (Z or W) and J/psi production at the LHC conditions. We focused on new partonic subprocesses, namely, the charmed or strange quark excitation followed by the charmed quark fragmentation c -> J/psi + c. Additionaly we take into account the effects of multiple quark and gluon radiation in the initial and final...
We present the resummed predictions for inclusive cross section for Drell-Yan (DY) production up to next-to-next-to leading logarithmic ($\rm \overline{ NNLL}$) accuracy taking into account both soft virtual (SV) and next-to SV (NSV) threshold logarithms. We restrict ourselves to resummed contributions only from quark anti-quark ($q \bar q$) initiated channels. The resummation is...
We show how to compute directly the renormalization/evolution of the
radiative jet function that appears in the factorization theorems for
$B\to \gamma\ell\nu$ and $H\to \gamma\gamma$ through a $b$-quark
loop. We point out that, in order to avoid double counting of soft
contributions, one should use in the factorization theorems a
subtracted radiative jet function, from which soft...
We perform a twist decomposition of the Balitsky-Kovchegov (BK) amplitude for the proton structure functions in the leading logarithmic limit. Assuming a single iteration of the triple pomeron vertex and using the Mellin space technique we discuss the BK corrections for the leading and subleading twist contributions.
In this talk we will describe a parallel between phenomenological and symmetry-based descriptions of the process dependence of the Time-reversal-odd phenomena in QCD, such as the Sivers effect, with the goal of defining the essential elements that lead to such process dependence in QCD. With the necessary elements clarified across these two complementary descriptions, this will then serve as a...
