The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An Energy Recovery Linac in racetrack configuration will provide 60 GeV electrons to collide with the HL-LHC ion beams and, eventually, with those from the HE-LHC and the FCC-hh. Such configurations will yield electron-nucleus collisions with per nucleon centre-of-mass energies 0.8-2.2 TeV and luminosities...
The understanding of the Higgs coupling to fermions is among the main goals of the Run2 at the LHC. This talk will present the most recent results from LHC on this topic. Prospects for the full Run2 analyses and for CP measurements of the Hff vertex will be also discussed.
A comprehensive collection of results on longitudinal double-spin asymmetries is presented for charged pions and kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons on the proton and deuteron, based on the full HERMES data set. The dependence of the asymmetries on hadron transverse momentum and azimuthal angle extends the sensitivity to the flavor structure of...
NNLO predictions for jet production in Deep Inelastic Scattering have recently become available. These are used to extend the QCD HERAPDF2.0Jets fits, that were made to extract PDFs from inclusive HERA data and HERA jet data, from NLO to NNLO. In addition new jet data sets have become available since the publication of HERAPDF2.0 and these are also considered.
This talk reviews the current theory status of top-quark production at the LHC.
The production of top-quarks, the heaviest elementary particle known, is studied in great
detail by the experiments ATLAS and CMS. It provides unique possibilities to extend our
knowledge about the Standard Model and beyond. To make most of the precise data
available, precise theory predictions for...
The production of $W$ bosons in longitudinally polarized proton-proton collisions at the Relativistic Heavy Ion Collider (RHIC) provides an ideal tool to study the spin-flavor structure of the proton, through the measurement of the parity-violating single-spin asymmetry, $A_L$. STAR has measured $A_L$ for $W$ boson production from datasets taken in 2011 and 2012 which provided significant...
Deep Inelastic Scattering (DIS) is the cleanest tool available to probe the content of a fast proton or nucleus. In the regime of low Bjorken x, one enters in the nonlinear regime of gluon saturation where the gluons are better described within the framework of Color Glass Condensate (CGC) and the dipole factorization. This framework allows to resum coherent multiple scattering on the target,...
We discuss the updates to the MMHT2014 PDFs. These are due to inclusion of ever-increasing amounts of LHC data, and simultaneously the treatment of more cross sections fully at NNLO. We also present the final results of our inclusion of QED effects in parton distributions.
The measurement of Higgs boson production in association with a ttbar pair is essential to understand the top-quark couplings to the Higgs boson. This talks presents the analyses using Higgs boson decays to bbbar pairs, to two Z bosons, to other multi-lepton final states, and to a pair of photons, using pp collision data collected at 13 TeV.
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...
The contribution of the gluon helicity to the spin of the proton is being studied through the use of the unique capability of the Relativistic Heavy Ion Collider (RHIC) to collide polarized protons at $\sqrt{s}=200\,$GeV and $\sqrt{s}=510\,$GeV. The kinematic coverage of the Solenoidal Tracker At RHIC (STAR) allows access to gluons through quark-gluon and gluon-gluon scattering processes which...
Latest results on inclusive top quark pair production cross sections are presented using proton-proton collision data collected at the LHC. The inclusive measurements reach high precision and are compared to the best available theoretical calculations. Differential measurements of the kinematic properties of the top quark production are also discussed. These measurements, including results...
Pomeron was introduced in the framework of the phenomenological Regge theory.
It governs the high-energy asymptotics of various hadronic processes and the small-$x$ behavior of $F_1$ in particular.
The best-known contribution to the QCD Pomeron comes from the BFKL equation which
sums Leading Logarithmic (LL) contributions i.e. the
single-logarithmic (SL) contributions $\sim (\alpha_s \ln...
We present the new CTEQ-TEA global analysis of Quantum Chromodynamics (QCD). In this analysis, parton distribution functions (PDFs) of the nucleon are determined within the Hessian method at the next-to-next-to-leading order (NNLO) in perturbative QCD, based on the most recent measurements from the Large Hadron Collider (LHC) and a variety of world experimental collider data. Next-to-leading...
The accumulation of a large amount of new experimental data at an impressive rate at present and future collider experiments has led to important questions concerning data storage and organization, their public access and usability, as well as their effective and efficient usage in order to discriminate between different theories. For the last thirty years, the HEPData database has been the...
The production of a Higgs boson in association with a pair of top quarks (ttH) is presented. In particular the final states with multileptons targeting the WW, ZZ and tautau decays of the Higgs boson, are reported. The data set analyzed corresponds 41.4 fb$^{-1}$ of pp collisions recorded by the CMS experiment in 2017. Machine learning and matrix element techniques are used to enhance the...
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 NLO Balitsky-Kovchegov (BK) equation describing the high-energy evolution of the scattering between a dilute projectile and a dense target suffers from instabilities unless it is supplemented by a proper resummation of large (anti-)collinear logarithms. Earlier studies showed that if one expresses the evolution in terms of the rapidity of the dilute projectile, the dominant anti-collinear...
A significant limitation in current PDF determinations is that the impact of theoretical uncertainties is not systematically accounted for. I will present a framework for the inclusion of additional sources of theoretical uncertainty in PDF fits, and present the first study of the effects of Missing Higher Order Uncertainties, which are estimated using scale variations, on PDFs in the context...
The CLAS12 detector at Jefferson Laboratory (JLab) started data taking with a polarized 10.6 GeV electron beam, interacting with an unpolarized liquid hydrogen target in February 2018. One of the first quantities which could be extracted from the new data is the moment $A_{LU}^{sin(\phi)}$ corresponding to the polarized electron beam spin asymmetry in semi-inclusive deep inelastic scattering....
A comprehensive set of measurements of top quark pair and single top quark production in association with EWK bosons (W, Z or ɣ) is presented. The results are compared to theory predictions and re-interpreted as searches for new physics inducing deviations from the standard model predictions using an effective field theory approach. The status of the search for four top quark production, to...
Testing the couplings of the Higgs boson to fermions is an important part to understand the origin of fermion masses. The talk presents cross section measurements in Higgs boson decays to two tau leptons, as well as a search for Higgs boson decays to two muons. Both analyses are based on pp collision data collected at 13 TeV.
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...
In the Color Glass Condensate framework the profile of the target is modelled by the saturation scale, $Q_s(\vec b)$. In the literature it is commonly assumed that the length scale of the fluctuations of the saturation scale, $l_{fluc.}$, is large. One implication of this approximation is that the gluon dipole cannot couple to gradients of the saturation scale. Using the McLerran-Venugopalan...
We report an update of the NNLO ABMP16 PDFs aimed to include recent
data on the Drell-Yan process, single- and pair-production of the top
quarks at the LHC, and the heavy-quark semi-inclusive DIS production with a
main focus on the small-x PDFs. The parameters of QCD Lagrangian,
strong coupling constants and the heavy quark masses, are determined
simultaneously with the PDFs and interplay...
Since the first measurements by the EMC that triggered the so-called “proton spin crisis”, many experimental programs have been carried out to understand the spin of the nucleon in terms of its partonic degrees of freedom. It is still today an active research area in QCD phenomenology, with ongoing programs at COMPASS, RHIC and Jefferson Lab measuring spin observables to be analyzed within a...
A new fit of diffractive parton distribution functions (DPDFs) to the HERA inclusive and jet data in diffractive deep-inelastic scattering (DDIS) at next-to-next-to-leading order accuracy (NNLO) is presented. The inclusion of the most comprehensive dijet cross section data, together with their NNLO predictions, provide enhanced constraints to the gluon component of the DPDF, which is of...
In 2016 and 2017, together with DVCS data, the COMPASS Collaboration has collected a considerable amount of Deep Inelastic Scattering events scattering a 160 GeV/c muon beam off a liquid hydrogen target. A first analysis of a small
subsample of these data has allowed to extract preliminary results on the amplitudes of three azimuthal modulations, $A^{\cos \phi_h}_{UU}$, $A^{\cos...
In Run2 precise measurements of the Higgs production and its properties have been carried out using the Higgs decays to bosons. Recent results from the LHC will be discussed, including measurements of different Higgs production modes and differential cross section measurements.
I give an overview talk on recent theoretical studies of top quark properties. Starting from basic quantities such as the top quark mass and spin correlations, I discuss more sophisticated quantities related to the electroweak interactions and dipole moments. These couplings can be probed at the LHC in a multitude of different ways. I will present some of the most recent ideas and proposals.
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...
A fixed-target experiment using the LHC beams with an (un)polarized target would offer a unique opportunity to study the 3-dimensional (3D) and spin structure of the nucleon. Recent studies have shown that a number of spin and azimuthal asymmetries are large enough to be precisely measured, allowing to constrain several non-perturbative functions which encode the internal structure of the...
The multiplicities of charged hadrons produced in the deep inelastic scattering (DIS) of muons off a proton target as a function of the hadron transverse momentum $P_{hT}$ are being measured by COMPASS using the data collected in 2016 and 2017 with a $160~\mathrm{GeV}/c$ muon beam and a liquid hydrogen target. Preliminary results of this analysis using a fraction of the full collected sample...
We present a first determination of the nuclear parton distribution functions (nPDF) based on the NNPDF methodology: nNNPDF1.0. This nPDF analysis is based on neutral-current deep-inelastic structure function data, and is performed using NNLO QCD calculations with heavy quark mass effects. For the first time in the NNPDF fits, the $\chi^2$ minimisation is carried out using stochastic gradient...
Inclusive single diffractive dissociation (pp->pX) is studied using data collected by the ATLAS experiment at the LHC. The intact proton is reconstructed and measured in the ALFA forward spectrometer, while charged particles from the dissociative system (X) are reconstructed and measured using the ATLAS inner tracking detector and calorimeters. Differential cross sections are presented as a...
The most precise measurements of Higgs boson cross sections, using the framework of simplified template cross sections, are obtained from a combination of the measurements performed in the different Higgs boson decay channels. This talk presents the combined measurements, as well as their interpretation.
The LHCSpin project aims to bring both unpolarized and polarized physics at the LHC through the installation of a gaseous fixed target at the upstream end of the LHCb detector. The forward geometry of the LHCb spectrometer is perfectly suited for the reconstruction of particles produced in fixed-target collisions. The fixed-target configuration, with center-of-mass energies ranging from √s=115...
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...
With the upgrade of JLab 12 GeV, a new era for the exploration of partonic degress of freedom in hadronic physics has started. In particular SIDIS is a key reaction to understand partonic structure of hadrons and the physics of hadronizaion provided a solid understanding and consistency of QCD factorization theorems to describe the data. In this talk I will review a recent progress to...
Measurements of top quark properties using data collected by the LHC are presented. Among them, latest results on top mass, ttbar spin correlations and charge asymmetries will be discussed.
Parton distribution functions (PDFs) are important quantities that characterize the structure of hadrons at high energy. Calculating them from first principles have been a long standing challenge in hadron physics and particle physics. In the past few years, rapid progress has been made in directly computing PDFs from lattice QCD. In this talk, I will summarize the current status of lattice...
Merged abtsract
In this contribution we briefly discuss an ongoing phenomenological programme on quarkonium production in unpolarised and polarised proton-proton collisions in a fixed target setup at LHCb, the LHCSpin project.
Within a TMD approach, we will consider in particular: the relative role of the NRQCD color-singlet and color-octet production mechanisms, both for unpolarised and polarised quarkonium...
The Higgs decay width can be constrained by exploiting interference effects of the $pp \to H \to \gamma\gamma$ signal with the $pp \to \gamma\gamma$ continuum background, which leads to a width-dependent shift of the Higgs mass peak. I review a study in which my collaborators and I investigate the reach of an analysis that determines the reference mass by measuring the di-photon final state at...
The extraction of unpolarized transverse momentum dependent functions (TMDs) has received a lot of attention in recent years. A succesful extraction of these funtions require careful consideration of the interplay between perturbative and non-perturbative components in the definitions of the TMDs. In this talk, I will discuss how our knowledge of the unpolarized TMDs may be improved in light...
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...
The TOTEM experiment at the LHC has measured proton-proton elastic scattering in dedicated runs at √s = 2.76, 7, 8 and 13 TeV centre-of-mass
LHC energies. The proton-proton total cross-section has been derived for each energy using a luminosity independent method. TOTEM has
excluded a purely exponential differential cross-section for elastic proton-proton scattering with significance greater...
We present a PDF interpretation of events containing a vector boson produced in association with jets at a proton-proton collider, performed using ATLAS data from 2012 at a centre-of-mass energy of 8 TeV, together with ATLAS data on inclusive vector boson production at 7 TeV. The results are given relative to the ATLASepWZ16 PDF set, with consequences for the strangeness content of the sea....
We describe two recent ideas to probe gluon TMDs in electron-proton collisions using quarkonium production. In the first one, we study the semi-inclusive production of a j/psi or upsilon meson in deep-inelastic scattering off a (un)polarized proton. In the regime where the small transverse momentum of the quarkonium is much smaller than the virtuality of the process, the cross section is...
Describing qT-dependent SIDIS distributions requires consideration of two different regimes which involve two different factorization schemes. In both cases, the necessary ingredients include parton distribution and fragmentation functions (PDFs and FF), which are traditionally extracted in statistical analyses with collinear observables. In this talk I will present examples of how the errors...
Latest results on inclusive and differential single top quark production cross sections are presented using proton-proton collision data collected by the LHC. The single top quark analyses investigate separately the production of top quarks via t-channel exchange, in association with a W boson (tW) or via the s-channel. Final states with at least one charged lepton and one b-jet are explored...
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...
This talk will discuss the most recent results for the search of double Higgs non-resonant production at the LHC.
The sensitivity reached, which is still one order of magnitude above than the SM prediction, allows excluding already significant regions of the BSM phase space. Interpretation of searches results with a dedicated EFT approach will be showed. A particular focus will be also given...
Global QCD analyses of PDFs and fragmentation functions (FFs) have traditionally been performed in completely independent studies. The JAM Collaboration, in contrast, has embarked on a systematic program to simultaneously extract PDFs and FFs from a wide range of processes using Monte Carlo methods. In this talk I will report new results on spin-averaged and spin-dependent PDFs and FFs from a...
Recent results of the TOTEM collaboration [1] suggest that the odderon exchange can be responsible for a disagreement of theoretical calculations and the TOTEM data [2] for elastic $pp$ scattering. It is premature to draw conclusions. Here we present our recent studies for three different processes in $pp$ collisions where the odderon may show up. We apply recently proposed tensor-pomeron and...
A future EIC with forward detectors would enable measurements of DIS on
the deuteron with detection of a forward proton/neutron (spectator tagging) over a wide kinematic range. Spectator tagging controls the nuclear configuration during the DIS process and permits an accurate differential treatment of nuclear effects. When combined with deuteron polarization, the method enables next-generation...
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.
At the LHC the dominant production channel for the Higgs-boson with two
jets is through gluon fusion, which is therefore also the dominant background for measuring the Higgs-boson production through weak boson fusion. To reduce the gluon fusion component WBF cuts require a large invariant mass of the dijet system. Thus the predictions become sensitive to a high energy logarithm. We present new...
Recently COMPASS has reported unexpected results concerning K− over K+ multiplicity ratio for kaons produced in DIS with a large fraction of the virtual-photon energy, PLB 786 (2018) 390. The obtained ratio is significantly below the lower limit given by NLO pQCD.
In order to provide more information about the observed phenomenon we will show for the first time results concerning pbar over p...
We consider impact of the large-log resummation emerging at the large momentum transfer $Q$ in the variable-flavour-number (VFN) scheme description when it is applied to analysis of the semi-inclusive DIS production of the charm and bottom quarks. Matching of the VFN scheme with the fixed-flavour-number (FFN) one at small $Q$ is also discussed and phenomenological relevance of these two...
Beauty production in events containing two muons in the final state has been measured with the ZEUS detector at HERA II. A low transverse-momentum threshold for muon identification, in combination with the large rapidity coverage of the ZEUS muon system and the upgraded ZEUS tracker, gives access to almost the full phase space for beauty production. The total cross section for beauty...
We discuss Dyson-Schwinger hierarchy of the equations for the correlators of reggeized gluon fields in the framework of Lipatov's
high energy QCD effective action formalism.
The non-linear corrections to the two-field correlators are presented and correspondence between the correlators of reggeized gluon fields and Wilson line
operators of longitudinal gluon fields is established,
the...
The new planned QCD facility at the M2 beam line of the CERN
SPS, will be a successor of COMPASS, and will have a broad
experimental programme addressing fundamental issues
leading to significant improvements in our understanding
of strong interactions. After a brief summary of the planned
research in hadron partonic structure and hadron spectroscopy,
the presentation will focus on two...
We present preliminary COMPASS results on pion and kaon multiplicities produced in semi-inclusive deep inelastic scattering of 160 GeV muons off a pure proton (LH$_2$) target. The results constitute a large data set of more than 600 points for pions and 600 for kaons, covering a large $x$, $Q^2$ and $z$ domain in a fine binning. The results from the sum of the z-integrated multiplicities...
The new planned QCD facility at the M2 beam line of the CERN SPS will have a broad experimental programme addressing fundamental issues leading to significant improvements in our understanding of strong interactions. The presentation will be focused on the Drell-Yan programme, which aims to make a major step forward in the determination of the nearly unknown pion and kaon parton distribution...
We show how theoretical uncertainties due to nuclear effects may be
incorporated into global fits of proton parton distribution functions (PDFs)
that include deep-inelastic scattering and Drell-Yan data on
nuclear targets. We specifically consider the CHORUS, NuTeV and E605 data
included in the NNPDF3.1 fit, which used Pb, Fe and Cu targets, respectively.
We show that the additional...
The gauge-invariant EFT for Multi-Regge processes in QCD [1,2] has bee introduced to facilitate the computation of NLO corrections in the BFKL approach. The main difficulty in this approach is the appearance of rapidity divergences (RDs) in loop integrals, which are not regularized by dimensional regularization and require separate regularization, see Ref. [3] for more details. We will discuss...
Several direct searches for exotic Higgs decays, which will be a clear sign of BSM physics, are performed at the LHC (lepton flavour violation, long-lived particles, low-mass scalars, semi-invisible...). This talk will discuss the most recent searches performed at the LHC, the interpretation of the results and prospects for the full LHC Run2 analyses.
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 spectroscopy of excited hadronic states in the beauty sector, double heavy hadrons and quarkonia provides a rich proofing ground for effective theories of the strong interaction. The decays of these states also provide a source of exotic hadrons, especially in the charmonium mass region. The unique data samples collected during Run I and II of the LHC open new possibilities for precision...
We investigate the high energy proton-proton scattering in the framework of holographic QCD, which is an effective approach to QCD constructed based on the AdS/CFT correspondence. In our model setup, the involved nonperturbative partonic dynamics is described by the Pomeron exchange, which is realized applying the Reggeized spin 2 particle propagator together with the proton gravitational form...
We present an investigation of the theoretical uncertainties in parton distribution functions (PDFs) due to missing higher-order corrections in the perturbative predictions used in the fit, and their relationship to the uncertainties in subsequent predictions made using the PDFs. We consider in particular the standard approach of factorization and renormalization scale variation, and derive...
The searches for light pseudoscalar Higgs bosons pair produced from the decay of the 125 GeV Higgs boson and resulting in various final states (4mu, 4tau, 2mu2tau, 2b2tau) according to the mass of the light boson and searches for low mass scalar bosons below 125 GeV in decays to photon pairs will be summarised. The analyses are performed using data collected with the CMS experiment at the LHC...
The description of the polarized quark hadronization process is one of the most challenging problems in strong interactions. The various single hadron and dihadron fragmentation functions, that quantify this process, are determined by analyzing the inclusive production of hadrons in electron-positron annihilation process. These, in turn, are used to extract the transverse momentum dependent...
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...
We present new quantitative predictions for the distribution of the total invariant mass produced diffractively in dipole-nucleus scattering at large relative rapidity. We show that the shape of this distribution is intimately related to the properties of the fluctuations in the small-x partonic evolution. This observable can potentially be measured at a future electron-ion collider.
*Based on...
The proton radius can be determined by measuring the slope of the electric form factor at small squared four-momentum transfer $Q^2$. Numerous elastic-scattering and laser-spectroscopy measurements of the proton radius have been performed with contradicting results, the so-called proton radius puzzle. We propose to measure the proton radius in high-energy elastic muon-proton scattering at the...
We study the threshold corrections for inclusive deep-inelastic scattering and resummation to N4LL accuracy. Using the form factor at four loops in the large-nc limit we are able to derive the soft-virtual coefficients at the four loops in large-nc approximation. We have presented the expression for resummation coefficients B4q coefficient for quarks which enters first time in the resummed...
We connect at the operator level the inclusive gauge-invariant quark propagator and the quark to single hadron fragmentation correlator in QCD. Exploiting a new spectral decomposition for the quark propagator, we then derive a complete set of momentum sum rules for the quark fragmentation functions into a single unpolarized hadron up to twist-three. Known results are recovered, and new sum...
The largest data sample accumulated by the Belle experiment at KEKB asymmetric energy e+e- collider provides an opportunity to perform studies of hadron spectroscopy. We present new measurements on charmed baryons
such as Xi_c^0, Lambda_c, as well as other charmed mesons and strange baryons.
In this presentation, we also cover recent results on hadron spectroscopy from Babar and BES III.
Recent results on searches for Dark Matter are reported, including H->inv.
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...
We present results for the diffractive dijet production cross section in e+p collisions within the color glass condensate framework to leading logarithmic accuracy. The framework includes a spatially dependent McLerran-Venugopalan initial configuration at relatively large $x$, combined with explicit numerical solution of the JIMWLK equations. We focus in particular on the dependence of the...
E-906/SeaQuest is a fixed-target experiment at Fermilab designed to measure the flavor dependence of the light-quark sea in nucleons at high Bjorken-x. Previous experiments have shown a surprising drop of the $\bar{d}/\bar{u}$ ratio at high Bjorken-x and SeaQuest was designed to extend the measurement to higher Bjorken-x with a 120 GeV proton beam. The Drell-Yan process is used as a probe of...
Dihadron production in Semi-Inclusive Deep Inelastic Scattering (SIDIS) represents a novel probe for
nucleon structure, as well as for spin-orbit correlations in hadronization. Measurements of the beam
spin asymmetry from dihadron production provide access to the twist-3 PDF $e(x)$, which can be related to
the transverse polarization dependence of the transverse force experienced by a struck...
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton and ion beams to achieve per nucleon centre-of-mass energies 1.3-3.5 (0.8-2.2) TeV and luminosities $\sim 10^{34(33)}$ cm$^{-2}$s$^{-1}$. Such a machine offers the opportunity to build a state-of-the-art HEP detector to be...
The presence of a non-baryonic dark matter component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model it would be produced at the LHC, escaping the detector and leaving a large missing transverse momentum as their signature. The ATLAS detector has developed a broad and systematic search program for dark...
The forward Drell-Yan (DY) lepton pair production together with a backward jet is proposed as a new way to study the BFKL effects due to a large rapidity gap between the two systems. Predictions for quantities to be measured are computed using the leading order DY impact factors and the BFKL kernel with a consistency condition which takes into account an important part of the next-to-leading...
We present our work on the inclusion of spin effects in the hadronization part of the PYTHIA 8 event generator. These effects are restricted to the emission of pseudoscalar mesons and are obtained from the propagation of the quark polarization along the fragmentation chain according to the rules of the ${}^3P_0$ model.
The interface between PYTHIA 8 and the ${}^3P_0$ model and the results on...
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...
In this contribution I will present the latest developments concerning the APFEL++ program. APFEL++ is a C++ rewriting of the Fortran 77 evolution code APFEL, it is based on a completely new code design and guarantees a better performance along with an optimal memory management. This makes APFEL++ suitable for a wide range of tasks: from the solution of the DGLAP evolution equations to the...
The spectroscopy of charm baryons provides a rich proving ground for effective theories of the strong interaction. This talk will present recent measurements of charmed baryons at LHCb, BESIII, and Belle. Discoveries of previously unobserved states in recent years will be discussed, along with precise determinations of the properties of known states.
A brief review of developments for APPLgrid to allow PDF fits other than to the proton, or other non standard proton fits is presented. These include changes to allow fitting of the photon density within the proton, and changes to facilitate the use of distinct PDF sets for each of the incoming hadrons in hadron-hadron interactions.
The inclusive photoproduction of two heavy quark–antiquark pairs, separated by a large rapidity interval, is proposed as a new channel for the manifestation of the Balitsky–Fadin–Kuraev–Lipatov (BFKL) dynamics. The extension to the hadroproduction case will also be discussed.
Evidence for the light-by-light scattering process, γγ → γγ, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV is reported. The analysis is conducted using a data sample corresponding to an integrated luminosity of 390 μb −1 recorded by the CMS experiment at the LHC. Light-by-light scattering processes are selected in events with two photons exclusively...
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...
We present recent results from the xFitter project--an open-source
software framework for the determination of PDFs and the analysis of
QCD physics. xFitter has been used for a variety of LHC studies
including the measurement of the strange PDF, which we briefly
summarize. Additionally, charged current DIS charm production
provides a complementary perspective on s(x). We make use of...
Recent years tremendous progress has gained in the study of the exotic states (so called XYZ) in both experiment and theory。 In this talk, we will review the experimental results of the XYZ study.
After an introduction to the EIC (parameters, physics goals, and status)
and a quick overview of the various detector concepts being developed for the EIC,
I will introduce the TOPSiDE detector concept. TOPSiDE aims a the detection and
identification of all particles created in electron-proton/ion collisions at the EIC
while achieving the best possible momentum/energy resolution....
Unequal rapidity correlations can be studied within the stochastic Langevin picture of JIMWLK evolution in the Colour Glass Condensate effective field theory. By evolving the classical field in the direct and complex conjugate amplitudes, the Langevin formalism can be used to study two-particle production at large rapidity separations. The evolution between the rapidities of the two produced...
We present a novel framework to carry out global analyses of the Standard Model Effective Field Theory (SMEFT) at dimension-six: SMEFiT. The SMEFiT approach is based on the Monte Carlo replica method to derive a faithful estimate of the experimental and theoretical uncertainties and enables one to construct the probability distribution in the space of the SMEFT degrees of freedom.
As a proof...
The sheer volume of the LHC experimental data sensitive to the hadronic structure presents a formidable challenge for the global QCD analysis. In the CT18 global analysis, we implemented new approaches to streamline identification of the LHC experiments that have the greatest promise for constraining parton distributions in the nucleon at the next-to-next-to-leading order accuracy. Toward this...
Transverse single-spin asymmetries (TSSAs) of proton-proton collisions have a history of revealing the richness of QCD. Large TSSAs were originally discovered in fixed target experiments in the mid 1970s. However they have been found to persist in collisions up to $ \sqrt{s} = 510 $ GeV and transverse momenta up to about $7$ GeV/c, well into the perturbative regime of QCD, and yet their...
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...
Initial simulations investigating using the RHIC-EIC proton beam as the drive beam in a plasma wakefield acceleration experiment are presented. The proton beam enters the plasma and undergoes self-modulation, forming a series of microbunches. These microbunches resonantly drive electron density perturbations within the plasma, exciting a longitudinal electric field with accelerating gradients...
The PHENIX experiment at RHIC studied the $A$-dependence of transverse,
single-spin asymmetries in production of charged hadrons in collisons
of polarized protons with aluminum and gold nuclei, as well as with
protons. The measurements covered forward rapidities, between 1.4 and
2.4, over the transverse-momentum range of 1.8 to 7 GeV$/c$. We report
on the observation of a significant asymmetry...
Fast interpolation grid technology provides a fast and flexible way to reproduce the results of perturbative QCD cross section calculations with any input PDF, choice of scales, or strong coupling. Recent developments in the APPLfast interface between the NNLOJET QCD calculation with both APPLgid and fastNLO are reported including the release of development versions of grids for QCD cross...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+e^-$collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory. The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor. From February to July of this year, the machine...
Top quark production can probe physics beyond the SM in different ways. Some processes, and especially certain angular correlations, are sensitive to the existence of anomalous top quark couplings. In the SM, flavour-changing neutral currents (FCNC) are forbidden at tree level and are strongly suppressed in loop corrections. Several extensions of the SM incorporate significantly enhanced FCNC...
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...
We discuss the $k_{T}$-factorization approach for $c \bar c$ production in the context of the color evaporation model for $J/\psi$ meson production. We use a new approach to color evaporation model (CEM) for quarkonium production. The production of $c\bar c$ pairs is performed within $k_T$-factorization approach using different unintegrated gluon distribution functions (UGDF) from the...
We present an efficient numerical solution of the DGLAP equations for single and double parton distribution functions (PDFs and DPDs), based on the Chebyshev interpolation of these functions.
For PDF evolution, our method allows for a higher numerical accuracy using a considerably smaller number of grid points compared to other methods. The DPD evolution is realized using an affordable...
Many extensions to the Standard Model predicts new particles decaying into two bosons (W, Z, photon, or Higgs bosons) making these important signatures in the search for new physics. Searches for such resonant diboson resonances (including HH) have been performed in final states with different numbers of leptons, photons, jets and b-jets where new jet substructure techniques to disentangle the...
We review theoretical approaches to heavy flavor and quarkonium production mechanisms in hadron colliders. We discuss the application of the factorization theorem to heavy flavor production, and introduce implementations of the formalism in phenomenological calculations. For heavy quarkonium production, we give an overview of various production mechanisms, including phenomenological models and...
In this contribution I will provide an overview of the physics possibilities in the future DIS machines: EIC, LHeC and FCC-eh.
The exploration of the transverse spin structure of the nucleon by measuring spin (in)dependent azimuthal asymmetries in semi-inclusive DIS and in Drell-Yan processes is one of the main objectives of the COMPASS experiment at CERN (SPS, M2 beamline). During the first phase of the experiment (2002-2011) a series of SIDIS measurements were performed, using a longitudinally polarized muon beam...
Over the past several years, parton distribution functions (PDFs) have become more precise. However there are still kinematic regions where more data are needed to help constrain global PDF extractions, such as the ratio of the sea quark distributions $\bar{d}$/$\bar{u}$ near the valence region. Furthermore, current measurements appear to suggest different high-$x$ behaviors of this ratio. The...
We study the differential cross section in the unpolarized $\pi^- N$ Drell-Yan process, using transverse momentum dependent factorization up to next-to-logarithmic order of QCD and extract the nonperturbative Sudakov form factor for the pion in the evolution formalism of the unpolarized TMD distribution function, by fitting the experimental data collected by the E615 Collaboration at Fermilab....
Exclusive photoproduction of $\rho(770)$ vector mesons is studied using the H1 detector at HERA. A sample of about 700000 decays $\rho\to\pi^{+}\pi^{-}$ was collected in the years 2006-2007, using the H1 fast track trigger. It corresponds to an integrated luminosity of $1.3$ pb$^{−1}$. The sample is used to study cross-sections as a function of the invariant mass $m_{\pi\pi}$ of the decay...
Many theories beyond the Standard Model predict new particles, including new gauge bosons or heavy Majorana or Dirac neutrinos, which decay to well isolated leptons. Searches for new physics models with these signatures, are performed using the ATLAS experiment at the LHC.
Understanding the properties of nuclear matter and its emergence through the underlying partonic structure and dynamics of quarks and gluons requires a new experimental facility in hadronic physics known as the Electron-Ion Collider (EIC). A US-based facility capable of colliding high-energy polarized electron and ion beams at high luminosity has been envisaged for a long time and articulated...
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...
COMPASS is a fixed-target experiment in operation at the CERN North Area (SPS, M2 beam-line) since 2002. An important part of its broad physics programme is dedicated to the exploration of the transverse spin-structure of the nucleon studying target spin-(in)dependent azimuthal asymmetries arising in the Semi-Inclusive DIS (SIDIS) and Drell-Yan (DY) cross-sections. Recently, COMPASS has also...
The LHCb experiment allows to measure the production and polarisation of charm and beauty hadrons including quarkonia in various collision systems in collider and fixed-target mode. The forward rapidity acceptance in the laboratory frame and the covered Q^2 range test perturbative QCD calculations with their factorisation assumptions and put constraints on parton densities in unique kinematic...
We consider a new parametrisation for the parton distribution functions (PDFs) that is more flexible in the small-$x$ region. We implement it in the $\texttt{xFitter}$ open-source PDF fitting tool, and compare it to the default xFitter parametrization, widely used for many PDF studies, and notably for the HERAPDF determination. We find that we can describe the combined inclusive HERA I+II data...
The exclusive photoproduction reaction $\gamma p \to \psi(2S) p$ has been studied with the ZEUS detector in $ep$ collisions at HERA using an integrated luminosity of 350 pb$^{-1}$, in the kinematic range $30 < W < 180$ GeV, $Q^2 < 1$ GeV$^2$, $|t| < 5$ GeV$^2$, where $W$ is the photon-proton centre-of-mass energy, $Q^2$ - the photon virtuality and $t$ – four-momentum transfer at the proton...
The sensitivity of beam dump experiments to heavy neutral leptons depends on the relative strength of their couplings to individual lepton flavours in the Standard Model. We study the impact of present neutrino oscillation data on these couplings in the minimal type I seesaw model and find that it significantly constrains the allowed heavy neutrino flavour mixing patterns. We estimate the...
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An Energy Recovery Linac in racetrack configuration will provide 60 GeV electrons to collide with the HL-LHC proton and ion beams and, eventually, with those from the HE-LHC and the FCC-hh. Such configurations will yield electron-proton (nucleus) collisions with per nucleon centre-of-mass energies 1.3-3.5...
Measuring lepton angular distributions of Drell-Yan process provides a powerful tool to explore the reaction mechanisms and related parton distributions. For example, the Lam-Tung relation has been proposed as a benchmark of the pQCD effect in Drell-Yan process. Nevertheless, the violation of Lam-Tung relation was observed in the measurements of fixed-target experiments. Precision data 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.
Fracture functions are parton distributions of a hadron in the presence of an almost collinear particle observed in the final state. They are important ingredients in QCD factorization for processes where a particle is produced diffractively. Different kinds of fracture functions are used for a process in different kinematic regions depending on the scale of the momentum transfer. We take the...
A significant sample of $p^{\uparrow}p\to p\pi^{0} X$ events have been observed at STAR in $\sqrt{s}=200$ GeV
transversely polarized $pp$ collisions, where an isolated $\pi^0$ is detected in the forward
pseudorapidity range $2.65<\eta<3.9$ along with the forward-going proton $p$, which scatters with a
near-beam forward pseudorapidity into Roman Pot detectors. The sum of the $\pi^{0}$ and the...
We discuss production of Drell-Yan lepton pairs at hadron colliders
in the framework of the Parton Reggeization Approach, which includes
off-shell initial state effects in a gauge-invariant way. Other
possible prescriptions to restore gauge-invariance of
hard-scattering coefficient with off-shell initial-state partons are
also investigated and significant differences for the...
Recently, an Electron-Ion Collider was proposed in China based on the High-Intensity Heavy Ion Accelerator Facility (HIAF) which is currently under construction. The first phase of EicC will be an e-p/e-A collider with center-of-mass energy around 10-20 GeV for e-p. Both electron and proton (light nucleus) beams will be polarized with a luminosity of 1-5x10$^{33}$ cm$^{−2}$s$^{−1}$. EicC will...
Many theories beyond the Standard Model predict new phenomena which decay to light or heavy quarks. Such final states are of particular interest at the LHC since new phenomena produced in parton collisions are likely to produce final states with (at least) two partons. Various strategies are employed to probe high and low resonance masses. This talk will present the latest searches performed...
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...
Ultra-peripheral nucleus-nucleus collisions (UPC) are mediated by strong
electromagnetic fields, offering the opportunity to study photon-nucleus pro-
cesses at RHIC. Coherent J/ψ photoproduction is of particular interest for its
sensitivity to nuclear gluon distribution. The J/ψ mesons are heavy enough to
be described by perturbative Quantum Chromodynamics (pQCD), where coher-
ent cross...
In perturbative QCD, the masses of the hadrons involved in high energy reactions can usually be neglected. However, in the case of production of Kaons in electron-proton collisions at low (and not so low) beam energies this may not be a good approximation. In particular, a recent proposal to include hadron masses in theoretical calculations shows how these Hadron Mass Corrections can explain a...
The dilepton angular distribution in vector particle decays can be described through a set of five SO(3) rotational-invariant observables. These observables are derived as invariants of the spacial part of the hadronic tensor (density matrix) expressed in terms of angular coefficients. The restrictions on the invariants following from the positivity of the hadronic tensor are obtained....
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...
We present state-of-the-art predictions for the ultra-high energy (UHE) neutrino-nucleus cross-sections in charged- and neutral-current scattering. The calculation is performed in the framework of collinear factorisation at NNLO, extended to include the resummation of small-x BFKL effects. Further improvements are made by accounting for the free-nucleon PDF constraints provided by D-meson data...
We discuss the QCD predictions for the radiative decay $B\to \gamma \ell \nu_\ell$ with an energetic photon in the final state by taking into account the $1/E_\gamma, 1/m_b$ power-suppressed hard-collinear and soft corrections from higher-twist $B$-meson light-cone distribution amplitudes (LCDAs). The soft contribution is estimated through a dispersion relation and light-cone QCD sum rules....
The strong electromagnetic fields of Pb nuclei, accelerated at the LHC, can be used to measure photon-induced interactions in a new kinematic regime. Photon-induced processes are usually studied in ultra-peripheral Pb-Pb collisions where hadronic interactions are strongly suppressed. Coherent charmonium photoproduction is of particular interest since it is sensitive to poorly known gluon...
The talk will present the most recent results on inclusive searches for supersymmetric squarks (including direct stop and sbottom pair production) and gluinos at the LHC, possibly including R-parity violating scenarios and the description of special reconstruction techniques needed in these searches.
The Sivers function is benchmark for spin physics. The systematic calculation of this observable in QCD has been object of many studies. We discuss here a methodology for calculation which is allows to rederive systematically the NLO calculation and that can be used for all other twist-3 TMDs.
The forward acceptance of LHCb, 2.0 < y < 5.0, provides complementary reach to the general purpose detectors at the LHC for the study of Soft QCD processes. In addition, the installation of a series of scintillating pad detectors (Herschel), bracketing the LHCb detector along the beamline, for Run 2 of the LHC, with dedicated triggers, has significantly enhanced LHCb's sensitivity to central...
In this talk, we present results from a detailed assessment of the ultimate constraining power of LHC data on the PDFs that can be expected from the complete dataset, in particular after the High-Luminosity (HL) phase. To achieve this, HL-LHC pseudo-data for different projections of the experimental uncertainties are generated, and the resulting constraints on the PDF4LHC15 set are quantified...
Supersymmetry (SUSY) is a theoretical favored extension of the standard model (SM) since it provides explanations for several issues. Models with general gauge mediation (GGM), have the additional benefit of naturally suppressing flavor violations in the SUSY sector. Many of those models predict the production of events with photons and significant missing transverse momentum. The results of a...
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 explore the complete cross-section for the production of unpolarized hadrons in semi-inclusive deep-inelastic scattering up to power-suppressed $\mathcal{O}(1/Q^2)$ terms in the Wandzura–Wilczek-type approximation, which consists in systematically assuming that $\bar{q}gq$-correlators are much smaller than $\bar{q}q$-correlators. Under the applicability of Wandzura–Wilczek-type...
Measurements with hadrons containing heavy quarks are indispensable when studying the properties of the medium created in high-energy nuclear collisions. High-statistics data collected by experiments at RHIC and LHC allow to perform comprehensive studies of the hot and dense QCD matter using heavy quarks as probes and put under scrutiny models describing various aspects of production of...
The SHiP Collaboration has proposed a general-purpose experimental facility operating in beam dump mode at the CERN SPS accelerator. The SHiP experiment incorporates a muon shield based on magnetic sweeping and two complementary apparatuses. The detector immediately downstream of the muon shield is optimised both for recoil signatures of light dark matter scattering and for physics with...
The talk presents results from searches for gaugino and slepton pair production at the LHC, possibly including R-Parity violating scenarios, and from searches for long-lived particles (excluding the ones from exotics Higgs decays), which can be detected through abnormal specific energy loss, appearing or disappearing tracks, displaced vertices, long time-of-flight or late calorimetric energy deposits.
Within the so-called color gauge invariant generalized parton model (CGI-GPM), which includes initial (ISI) and final state (FSI) interactions in a transverse momentum dependent formalism, we present a phenomenological analysis of available data on single spin asymmetries for pion and $D$-meson production in $pp$ collisions at RHIC. This allows us, for the first time, to put preliminary...
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...
The publicly available PDFSense analysis package provides a variety
of tools for quantifying the potential impact of experimental data on
the extraction of PDFs. Our approach relies crucially on the Hessian
correlation between theory-data residuals and the PDFs themselves, as
well as on a newly defined quantity — the sensitivity — which
represents an extension of the correlation and reflects...
We argue that ultraperipheral collisions at the LHC allow to study effects color fluctuations (CF) of the strength of interaction of photon in large and small size configurations. We make predictions for the distribution over the number of wounded nucleons ν in the inelastic photon-nucleus scattering and in events with charm production. We show that CFs lead to a dramatic enhancement of this...
Quarkonium states are powerful tools to study the properties of thequark-gluon plasma (QGP), since their production is strongly affected by the dense and hot medium created in heavy-ion collisions.
In nucleus-nucleus interactions at LHC energies, charmonia reveal a smaller suppression with respect to the one measured at lower energies, as at RHIC and SPS. This observation points to the...
We show that heavy ion collisions at the LHC provide a promising environment to search for signatures with displaced vertices in well-motivated New Physics scenarios. The lower instantaneous luminosity in heavy ion collisions allows to operate the LHC experiments with very loose triggers. For scenarios in which long-lived particles are produced in the decay of light particles, this can...
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 Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities $\sim 10^{34}$ cm$^{-2}$s$^{-1}$. These three configurations will extend the kinematic plane by more than one order of magnitude towards smaller $x$ and...
The presently published Boer-Mulders (BM) function, for a given quark flavour, was extracted from data on semi-inclusive deep inelastic scattering (SIDIS) using the simplifying assumption that it is proportional to the Sivers function for that flavour. We argued that such an assumption is theoretically unacceptable and replaced it with an analogous, theoretically acceptable, relation for the...
A major recent breakthrough in global fits of the quark and gluon structure of the proton has been the inclusion of a significant amount of precision LHC measurements. While these data sets provide important constraints, especially on the poorly-known gluon and antiquark PDFs, it is crucial to avoid any contamination from potential beyond the Standard Model (BSM) effects that could be present...
We present recent developments in the theoretical description of
processes leading to the production of heavy flavours, which, together
with the most recent experimental data, are of interest for further
constraining present fits of Parton Distribution Functions. We compare
different approaches, and, for selected cases, we show the impact of
using the MSbar scheme as an alternative to the...
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...
One of the most striking phenomena arising from the extension of collinear factorization (inspired in Bjorken's parton model) to Transverse Momentum Dependent (TMD) factorization is the appearance of azimuthal modulation induced by the polarization of partons with nonzero transverse momentum even inside unpolarized hadrons. Linearly polarized gluons inside unpolarized hadrons is one of these...
A high-energy high-luminosity polarized electron-ion collider (EIC) is the Nuclear Science Advisory Committee's highest priority for new facility construction. A dedicated $e+A$ Monte Carlo event generator is especially crucial during the process of identifying observables and the experimental needs they would pose to detector designs. The JETSCAPE collaboration recently released version 1.0...
Merged abstract
We present a fit to determine parton distribution functions (PDFs) using inclusive W± and Z/γ∗ boson and top-antitop production measurements from ATLAS in combination with deep-inelastic scattering data from HERA. The ATLAS W and Z boson data exhibit sensitivity to the valence quark distributions and the light quark sea composition, whereas the top-quark pair production data have sensitivity...
I present the theory of high energy hadron-lepton interactions in presence of a background which breaks Lorentz invariance (this parameterization of Lorentz violation is known in the literature as the Standard Model Extension). I apply this theory to the calculation of Lorentz violating effects in DIS and present the expected bounds that can be obtained by sidereal time analyses of existing...
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...
We report on our recent study on the extraction of the gluon Transverse Mo-
mentum Dependent distributions (TMDs) inside unpolarised protons, using vector
quarkonium pair production at the LHC. In this work, we show how J/ψ pair pro-
duction is an ideal process to pin down the gluon TMDs and generate large azimuthal
asymmetries ; we also present a first fit of the average kT parameter for a...
Photon-photon fusion is a rare process at hadron and ion colliders. It is particularly interesting as a remarkably clean interaction with little (if any) remnant activity from the interacting particles. In this talk we present the status of photon-photon fusion measurements at the ATLAS detector, focussing on two types of analyses. In the first type of analysis, the ATLAS inner tracking...
Detailed studies have been carried out on the impact of top pair production data from the LHC on the gluon PDF, in the context of the CTEQ-TEA global PDF fit. The data includes single differential distributions from ATLAS at and double differential distributions from CMS, both at 8 TeV. The relative impact of different physical observables related to top quark production was considered. All...
Leptoquarks are predicted by many new physics theories to describe the similarities between the lepton and quark sectors of the Standard Model and offer an attractive potential explanation for the lepton flavour anomalies observed at flavour factories. The ATLAS experiment has a broad program of direct searches for leptoquarks, coupling to the first-, second- or third-generation particles....
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...
A technique has been recently proposed to achieve a control of the neutrino targets and fluxes comparable to electron scattering experiments. In particular, it allows precise measurements of high statistics samples of (anti)neutrino-hydrogen interactions and of various nuclear targets. The planned high intensity LBNF/DUNE beams give access to a broad mixture of measurements of electroweak...
We analyze in detail the LHC prospects for charged electroweakino searches, decaying to leptons, in compressed supersymmetry scenarios, via exclusive photon-initiated pair production. This provides a potentially increased sensitivity in comparison to inclusive channels, where the background is often overwhelming. We pay particular attention to the challenges that such searches would face in...
Differential measurements of top quark pair (tt) and single top quark (t-channel) production cross sections are presented using data collected by CMS. The cross sections are measured as a function of various kinematic observables of the top quarks and the jets and leptons of the event final state. The results are confronted with precise theory calculations. For the first time,...
Studying light-cone (standard) parton distribution functions (PDFs) through Euclidean correlators in lattice QCD is currently a very active field of research. In particular, the quasi-distributions (quasi-PDFs) suggested by Ji have attracted a lot of attention. Quasi-PDFs converge to their respective standard distributions if the hadron momentum goes to infinity. We explore the...
High-precision HERA data corresponding to a luminosity of around
1 fb$^{-1}$ have been used in the framework of $eeqq$ contact
interactions (CI) to set limits on possible high-energy contributions
beyond the Standard Model to electron--quark scattering. Measurements
of the inclusive deep inelastic cross sections in neutral and charged
current $ep$ scattering were considered. The analysis of...
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.
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities $\sim 10^{34}$ cm$^{-2}$s$^{-1}$. These large luminosities and the corresponding cross sections provide huge possibilities for precision measurements of...
We discuss the production of $W^+ W^-$ pairs and $t \bar t$ quark-antiquark pairs in proton-proton collisions induced by two-photon fusion including, for a first time, transverse momenta of incoming photons. The unintegrated inelastic fluxes (related to proton dissociation) of photons are calculated based on modern parametrizations of deep inelastic structure functions in a broad range of $x$...
Recent experimental measurements hint for possible new physics effects in B-meson decays, the so-called B-anomalies. New physics explanations of the anomalies generically imply large effects also in other observables, both at low-energies and at high-pT. I will review new physics scenarios able to address these anomalies and discuss their smoking-gun signatures. The possible connection of...
We present a first calculation of the heavy flavour contribution to the longitudinally polarized DIS structure function $g_1^Q$, differential in the transverse momentum or the rapidity of the observed heavy antiquark $\overline Q$. The results are obtained at next-to-leading order accuracy with a newly developed parton-level Monte Carlo generator that also allows one to study observables...
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.
The APPLgrid and fastNLO projects provide a fast and flexible way to reproduce the results of perturbative QCD cross section calculations with any input PDF, renormalisation or factorisation scale, and different values for the strong coupling constant. Recent developments in the generation of fast interpolation grids using the DIS process with the NNLOJET generator through the standardised...
The basis light front quantization (BLFQ) approach has been developed for solving many-body bound state problems in quantum field theories. We investigate several aspects of the nucleon properties such as electromagnetic form factors, generalized parton distributions (GPDs) etc. using the framework of BLFQ. We consider the light front wavefunctions obtained by diagonalizing the effective...
Charm production in charged current deep inelastic scattering has been measured for the first time in $e^\pm p$ collisions, using data collected with the ZEUS detector at HERA, corresponding to an integrated luminosity of 358 pb$^{−1}$. Results are presented separately for $e^+ p$ and $e^− p$ scattering at a centre-of-mass energy of $\sqrt{s} = 318$ GeV within a kinematic phase-space region of...
The concept of lepton universality, where the muon and tau particles are simply heavier copies of the electron, is a key prediction in the Standard Model (SM). In models beyond the SM, lepton universality can be naturally violated with new physics particles that couple preferentially to the second and third generation leptons. Over the last few years, several hints of lepton universality...
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...
We study the single longitudinal-spin asymmetry of dihadron production in semi-inclusive deep inelastic scattering process in which the transverse momentum of the final-state hadron pairs is integrated out. In Particular, we investigate origins of the $\sin \phi_R$ azimuthal asymmetry for which we take into account the coupling of the twist-3 distributions $h_L$ and the dihadron framgentation...
Jet measurements play an essential role in PDF fits and the available measurements will be briefly summarized. The primary experimental uncertainties in these measurements are the knowledge of the jet energy scale and resolution. The analyses used to evaluate these uncertainties will be described and how they are combined to form the set of uncertainties that dominate these measurements. How...
The production of a hard dijet with small transverse momentum imbalance in semi-inclusive DIS probes the conventional and linearly polarized Weizsäcker-Williams (WW) transverse momentum dependent (TMD) gluon distributions. The latter, in particular, gives rise to an azimuthal dependence of the dijet cross section. In this talk I will discuss the feasibility of a measurement of these TMDs...
The Belle II experiment at the SuperKEKB energy-asymmetric $e^+ e^-$ collider is a substantial upgrade of the B factory facility at the Japanese KEK laboratory.
The design luminosity of the machine is $8\times 10^{35}$ cm$^{-2}$s$^{-1}$ and the Belle II experiment aims to record 50 ab$^{-1}$ of data, a factor of 50 more than its predecessor.
With this data set, Belle II will be able to...
We investigate the transverse single-spin asymmetry with a $\sin\phi_{S_h}$ modulation for the transversely polarized proton and lambda production in semi-inclusive inelastic scattering process, where $\phi_{S_h}$ is the azimuthal angle of the transverse spin of the final hadron. Theoretically, the spin asymmetry can be interpreted by the convolution of the twist-3 transverse momentum...
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.
The production of prompt isolated photons at hadron colliders provides stringent tests of perturbative QCD and can be used to evaluate probability density functions of partons in the proton. In this talk, we present the measurements of the isolated-photon plus two jets and the inclusive isolated-photons cross sections, both measured using proton-proton collision data collected by the ATLAS...
Most of the progress in high-energy Quantum Chromodynamics has been obtained within the eikonal approximation and infinite Wilson-line operators. Evolution equations of Wilson lines with respect to the rapidity parameter encode the dynamics of the hadronic processes at high energy. However, even at high energy many interesting aspects of hadron dynamics are not accessible within the eikonal...
One of the challenges of hadronic physics is to fully understand the structure of the proton. In particular, there is nowadays a great interest in the decomposition of its total angular momentum into orbital angular momentum (OAM) and intrinsic
spin, as well as identifying contributions from valence quarks, sea quarks and gluons.
The most common decompositions of OAM are the Jaffe-Manohar...
Precision measurements of CP violating observables in the decays of b and c hadrons are powerful probes to search for physics beyond the Standard Model.
The most recent results on CP violation in the decay, mixing and interference of both b and c hadrons obtained by the LHCb Collaboration with Run I and years 2015-2016 of Run II are reviewed. In particular world best constraints and world...
Precision measurements of the production cross sections of W and Z bosons in proton-proton collisions provide stringent tests of perturbative QCD and yield important information about the parton distribution functions (PDFs) for quarks within the proton. We report measurements of fiducial integrated and differential cross sections for inclusive W+, W− and Z boson production, analysed in the...
Double parton scattering is the process in which one has two hard scatterings in an individual proton-proton collision. It can compete in rate with single scattering in certain kinematic regions and/or for certain processes, reveals new information on proton structure, and becomes more important as collider energy grows. I review recent progress in the theoretical description of double parton...
In the last years the LHCb experiment established itself as an important contributor to heavy ion physics by exploiting some of its specific features.
Production of particles, notably heavy flavour states, can be studied in p-p, p-Pb and Pb-Pb collisions at LHC energies in the forward rapidity region (pseudorapidity between 2 and 5), providing measurements which are highly complementary to...
I will present two complementary analyses of nearly all existing Deeply Virtual Compton Scattering (DVCS) data allowing to explore the proton structure within the framework of Generalised Parton Distributions (GPDs). The first analysis is based on a classic approach, where parameterisations of DVCS amplitudes are constructed in a model-dependent way to fulfil the basic properties of GPDs. The...
Part of the COMPASS-II program is dedicated to the investigation of Generalized Parton Distributions (GPDs) via lepton-induced hard exclusive reactions, in particular Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production. Data have been taken in 2016 -17 using a high intensity muon beam of 160 GeV and a 2.5 m-long liquid hydrogen target surrounded by a barrel-shaped...
In this talk, a new QCD analysis for nuclear parton distribution functions (nPDFs) at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) will be presented. The framework of the analysis, including the form of the parametrisation as well as the included DIS datasets, will be discussed. The results of this QCD analysis will be compared to the existing nPDF sets and to the...
In the context of the Standard Model (SM) of particle physics, the relationship between the mass of top quark and its width has been precisely calculated. However, the uncertainty from current direct measurements of the width is nearly 50%. A new approach for directly measuring the top quark width is presented, using events away from the resonance peak.
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities $\sim 10^{34}$ cm$^{-2}$s$^{-1}$. These large luminosities and the corresponding CC and NC cross sections for Higgs production make the LHeC a Higgs...
Measurements of multiple parton scattering in proton-proton collisions provide insight into the structure and long-range low-momentum scale interactions of the proton. In this talk we present two recent measurements using proton-proton collision data collected by the ATLAS experiment. The first measurement determines the double-parton scattering contribution to four-lepton events at √s=8 TeV....
Generalized Parton Distributions (GPDs) provide the opportunity to obtain a 3-dimensional description of a nucleon in terms of its constituent partons. Moreover, GPDs are related, via QCD-based sum rules, to total angular momentum, mass and pressure distributions inside the nucleon. GPDs are experimentally accessible via the deeply virtual Compton scattering (DVCS), i.e. the absorption of a...
We quantify the impact of LHCb D-meson measurements at $\sqrt{s}=5\,{\rm TeV}$ on the EPPS16 and nCTEQ15 nuclear PDFs. In our study, the theoretical description of D-meson production is based on the recently developed SACOT-$m_{\rm T}$ variant of the general-mass variable-flavour-number formalism, and the impact on PDFs is estimated via profiling methods. We pay a special attention on the...
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. An ERL will provide electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams to achieve centre-of-mass energies 1.3-3.5 TeV and luminosities $\sim 10^{34}$ cm$^{-2}$s$^{-1}$. These large luminosities provide most interesting possibilities for BSM studies. In this talk we present the latest...
We calculate the cross section for the production of $D$ mesons and $\Lambda_{c}$ baryons in pp collisions at the LHC. The cross section for production of $c\bar c$ pairs is calculated within the $k_{T}$-factorization approach. We show that our approach well describes the $D^0$, $D^+$, and $D_s$ experimental data. We try to understand recent ALICE and LHCb data for $\Lambda_{c}$ production...
The form factors of the energy-momentum tensor can be accessed
via studies of GPDs in hard exclusive reactions. In this talk
we present recent results on the EMT densities in the bag model.
The simplicity and lucidity of this quark model allow us to
investigate many general concepts which have recently attracted
interest, including shear, pressure, radial and tangential forces.
We also present...
I will review how associated-quarkonium production can help us study double parton scatterings.
The CJ (CTEQ-Jefferson Lab) collaboration provides a global fit of parton distribution functions with a special emphasis on the large $x$ region. The latest CJ15 global analysis implemented deuteron nuclear corrections at the parton level, and included data that were sensitive specifically to the neutron. These nuclear corrections allow for a calculation of the $F_2$ structure functions of the...
The electromagnetic probe has proven to be a very efficient way to access the three-dimensional
structure of the nucleon, particularly thanks to the exclusive Compton processes. We explore the hard photoproduction of a large invariant mass diphoton in the kinematical regime where the diphoton is nearly forward and its invariant mass is the hard scale enabling to factorize the scattering...
We explore how the positivity of the $P_T$-integrated $\eta_c$-hadroproduction cross section computed at NLO in $\alpha_s$ can set up constraints on the $x$ dependence of both gluon PDFs and TMDs at low scales. We also discuss the phenomenological implications on other quarkonium-production cross sections computed at NLO in both collinear and TMD factorisations.
Since a few years the LHC experiments started to give a special focus on searches for unusual signatures, namely long lived particles that would traverse the experiments our decay in the detectors. Several of these searches are conducted now in the ATLAS, CMS, LHCb and MoEDAL experiments. New experiments for the LHC are presently being proposed to extend substantially the phase space for these...
Extraction of the strange quark PDF is a long standing puzzle. We use
nCTEQ nPDFs with uncertainties to examine W/Z production at the LHC
and try to study both the nuclear corrections and the flavor
differentiation. This complements the information from neutrino-DIS
data. Additionally, we look ahead to future facilities such as EIC,
LHeC, and LHC upgrades and use a new tool, PDFSense, to...
The transverse momentum parton distribution $f_{1T}^\perp$, known as Sivers function, is odd under the naive time-reversal transformation and gives rise to a transverse single spin asymmetry (tSSA) in semi-inclusive DIS (SIDIS). An intuitive picture to understand the origin of this asymmetry is to relate the average Sivers transverse momentum to the impact parameter parton distribution E,...
Theory uncertainty from missing higher orders is usually estimated using scale variation. While scale variation is certainly a good tool to guess the size of the next perturbative order, it lacks of a statistical (probabilistic) interpretation and it often underestimates the actual uncertainty. Having a statistical definition of theory uncertainties is not only need for a fair comparison with...
Since 2005, measurements of the SIDIS process off transversely polarised protons performed by the HERMES and COMPASS Collaboration have shown that the Collins and the Sivers asymmetries are clearly different from zero, a milestone in the knowledge of the nucleon structure.
Only few data were collected in the early phase of the COMPASS experiment on a deuteron (6LiD) target and more recently at...
Due to the large masses of the charm and bottom quarks, their production cross sections are calculable within the perturbative QCD. This makes the heavy-quark mesons important observables in high-energy collisions of protons and nuclei. However, the available calculations for heavy-flavored-meson hadroproduction have been somewhat problematic in reliably describing the cross sections across...
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...
The prospects of the proposed Large Hadron electron Collider (LHeC) in the
search for heavy neutral scalar particles are discussed.
A minimal model is considered with one additional complex scalar singlet that interacts with the Standard Model (SM) via mixing with the Higgs doublet, giving rise to a SM-like Higgs boson h1 and a heavy scalar particle h2.
Both scalar particles are produced via...
The tensor-pomeron model is applied to low-x deep-inelastic lepton-nucleon scattering and photoproduction. We consider c. m. energies in the range 6 - 318 GeV and $Q^2 < 50$ GeV$^2$. In addition to the soft tensor pomeron, which has proven quite successful for the description of soft hadronic high-energy reactions, we include a hard tensor pomeron. We also include $f_2$-reggeon exchange which...
Semi-hard processes serve as a special testing ground for calculations of high-energy scatterings in perturbative QCD. In this kinematic limit, the enhanced effect of energy logarithms calls for an all-order resummation procedure. The most natural language to resum these large logarithms, both in the leading and the next-to-leading approximation, is elegantly embodied by the BFKL approach....
The knowledge of the proton parton densities for large $x$ is very important in the search for new physics signals at the LHC. For Bjorken-$x$ larger than 0.6 they are however poorly constrained by the data used in extracting the proton parton density functions (PDFs) and different pdf sets have large uncertainties, and differ considerably, in this regime. We compare the pdf sets most widely...
The Large Hadron Collider (LHC) has been successfully delivering proton-proton collision data at the unprecedented center of mass energy of 13 TeV. An upgrade is planned to increase the instantaneous luminosity delivered by LHC in what is called HL-LHC, aiming to deliver a total of about 3000/fb of data to the ATLAS detector. To cope with the expected data-taking conditions ATLAS is planning...
The recent intriguing hints for new physics in semi-leptonic B decays point towards lepton flavor universality (LFU) violating extensions of the SM. Prime candidates for such new particles are leptoquarks which can provide the desired effects. After a review of the current experimental and theoretical situation, the phenomenology of the vector leptoquark SU(1) singlet, which was proposed...
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...
Using the formalism of the light-cone wave function in perturbative QCD together with the hybrid factorization, we compute the cross-section for three (and two) particle production at forward rapidities in proton-nucleus collisions. We focus on the quark channel, in which the three produced partons -- a quark accompanied by a gluon pair, or two quarks plus one antiquark -- are all generated...
We present a new determination of Transverse Momentum Dependent (TMD)
parton distributions applying the Parton Branching method. The PB TMDs are
obtained from fits to precision DIS data using DGLAP splitting functions at
leading and higher order. In addition the CCFM splitting function will be applied
to include small x effects.
Applications of these new TMD distributions will be discussed.
The SoLID (Solenoidal Large Intensity Detector) program is proposed at JLab to be capable of running experiments with both high luminosity (10$^{37}$ − 10$^{39}$cm$^{−2}$s$^{−1}$) and large acceptance, exploiting the full potential of the 12 GeV energy upgrade at JLab. The spectrometer is designed with a capability of reconfiguration to optimize for either Parity-Violating Deep Inelastic...
The type II seesaw mechanism is an attractive way to generate the observed light neutrino masses. It postulates a SU(2)$_\mathrm{L}$-triplet scalar field, which develops an induced vacuum expectation value after electroweak symmetry breaking, giving masses to the neutrinos via its couplings to the lepton SU(2)$_\mathrm{L}$-doublets. When the components of the triplet field have masses around...
$K\rightarrow \pi \nu \bar{\nu}$ 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...
We consider the non-eikonal corrections to particle production in the Color Glass Condensate originating from relaxing the shockwave approximation for the target which takes into account its finite longitudinal thickness. We derive a modified expression of the Lipatov vertex that accounts for these corrections. This expression is employed to compute single, double and triple gluon production...
We study the effects of angular ordering constraint on collinear and transverse momentum dependent (TMD) parton distributions functions (PDFs) obtained within the Parton Branching (PB) method. We compare it with virtuality and pt ordering definitions. We study the effect of ordering choice on predictions for Z boson pt spectrum, especially at low pt and we demonstrate the advantage of the...
Polarized proton-proton and proton-nucleus collisions at Relativistic Heavy Ion Collider (RHIC) presents a unique opportunity to study the partonic and spin structure of the nucleon and nuclei. The STAR experiment at RHIC has measured at mid-pseudorapidity ($-1<\eta<2$) spin asymmetries in production cross section of pions, jets, as well as W and Z bosons, providing important experimental...
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...
Measurements of the forward-backward asymmetry in neutral-current Drell-Yan di-lepton production have primarily been used for determinations of the weak mixing angle $\theta_W$.
We investigate the possibility of using the reconstructed forward-backward asymmetry to place constraints on the determination of the parton distribution functions (PDFs). We perform this study using the open-source...
This talk will discuss opportunities to measure spin effects at a high-energy Electron-Ion Collider (EIC). Various types of spin distributions (PDFs, TMDs, GTMDs) will be considered and promising observables will be discussed, in particular those with heavy quark final states.
The concept of lepton universality, where the muon and tau particles are simply heavier copies of the electron, is a key prediction in the Standard Model (SM). In models beyond the SM, lepton universality can be naturally violated with new physics particles that couple preferentially to the second and third generation leptons. Over the last few years, several hints of lepton universality...
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.
The production of a light charged Higgs boson at the future Large Hadron electron Collider (LHeC) and Future Circular Collider in the mode hadron-electron (FCC-he) is studied, the main process e^− p \to \nu_e H^− q is considered, taking in account the decay channels H^− \to b \bar{c} and H^− \to \tau \nu_{\tau} in the final state. We analyze these processes in the framework of the 2-Higgs...
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...
Heavy quarks (charm and beauty) are unique probes for studies of the properties of the Quark-Gluon Plasma (QGP) formed in high-energy Pb--Pb collisions, since they are almost exclusively produced in hard scattering processes in the initial stages of the collision and thus experience the full evolution of the QGP.
In order to distinguish the effects of the QGP from possible Cold Nuclear Matter...
