The study of identified particle production as a function of the proton-proton (pp) collision energy and multiplicity is a key tool for understanding similarities and differences between small and large interacting systems. We report on new measurements of the production of unidentified charged hadrons as well as of pions, kaons, protons, K$^{0}_{\rm S}$, $\Lambda$, $\Xi$, $\Omega$, K$^{*0}$...
The measurements of dilepton and diphoton production in photon-photon fusion with the CMS-TOTEM Precision Proton Spectrometer (CT-PPS) are presented. For the first time, exclusive dilepton production at high masses have been observed in the CMS detector while one or two outgoing protons are measured in CT-PPS using around 10~${\rm fb}^{-1}$ of data accumulated in 2016 during high-luminosity...
The forward acceptance of LHCb, 2.0 < y < 5.0, provides a complementary reach to the general purpose detectors on LHC. LHCb measurements of the inelastic cross-section and related results will be presented, as well as a comparison to Run 1 results.
The cross-section for central exclusive production of J/psi and Psi(2S) mesons at 13 TeV is measured using the LHCb detector. Proton dissociative...
Low energy phenomena have been studied in detail at the LHC, providing important input for improving models of non-perturbative QCD effects. The ATLAS collaboration has performed several new measurements in this sector:
We present charged-particle distributions sensitive to the underlying event, measured by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV. ...
We present recent results of diffractive and exclusive measurements with the CMS experiment.
The photoproduction of isolated photons has been measured using diffractive events recorded by the ZEUS detector at HERA. Cross sections are evaluated in the photon transverse-energy and pseudorapidity ranges 5 < $E_T^\gamma$ < 15 GeV and
−0.7 < $\eta^\gamma$ < 0.9, inclusively and also with a jet with transverse-energy and pseudorapidity in the ranges 4 < $E_T^{jet}$ < 35 GeV and −1.5 <...
Quarkonia are mesons formed of either a charm and anti-charm quark pair ($\rm{J}/\psi$, $\psi(2S)$), or a beauty and anti-beauty quark pair ($\Upsilon$(1S), (2S) and (3S)). In high-energy hadronic collisions such as those delivered by the LHC between 2010 and 2016, quarkonium production results from the hard scattering of two gluons in a process which occurs very early in the collision...
Produced in a hard scattering an energetic parton will lead to a parton shower which will be fragmenting into a hadronic spray of particles called jet. The mass of the jet is sensitive to the initial virtuality of the parton at the origin of the shower. The jet fragmentation functions and their moments, describe the momentum distribution of hadrons inside a reconstructed jet. Their measurement...
Measurements of charmed-hadron production in pp collisions are important to test predictions from perturbative QCD and provide an essential baseline for the studies in A--A collisions. Measurements in p--A collisions also allow studies of possible modifications of the charmed-hadron yields due to cold nuclear matter effects. The study of charm production as a function of the multiplicity of...
We present precise measurements of decay properties of hadrons containing a b quark performed on the data collected by the CMS experiment at LHC. The lifetime is among the fundamental properties of particles and in heavy hadrons it is one of the important observables that allows to test the theoretical tools describing their physics. Some of the reported measurements are at the precision level...
Heavy flavour production measurements in proton-proton collisions are important tests of QCD.
We report on updated production cross-section measurement of quarkonia, open-charm, and open-beauty states. Other aspects related to the quarkonium production mechanisms, such as the associative production of quarkonium and jets, will be discussed.
We report on the first observation of excited hadronic states in both the charm and beauty sector with special emphasis on the observation of five excited Omega_c states.
Similar techniques are used to analyse LHCb data for short-lived intermediate bound-states formed during the multi-body decay of b-hadrons.
The latest results from ATLAS on heavy flavour and quarkonium production, including exotic states, are presented. This talk includes the measurement of B-hadron pair production, presented as a function of a variety kinematic variables between the two B-hadrons, providing important inputs to modelling of production via gluon splitting. Additional Insight into QCD models of quarkonium...
The production of electroweak gauge bosons in association with a jet, V+jet, constitutes an important class of standard-candle processes at the LHC. The requirement of an additional hadronic jet in the final state introduces a direct sensitivity to the strong coupling constant and the gluon PDF, while still retaining a large event rate. As such, V+jet production provides an ideal testing...
The production of jets in association with vector bosons is an important process to study perturbative QCD in a multi-scale environment. The ATLAS collaboration has performed new measurements of vector boson + jets cross sections, differential in several kinematic variables, in proton-proton collision data taken at center-of-mass energies of 8 TeV and 13 TeV. The measurements are compared to...
The most recent results on the production of single W and Z bosons with two jets at high invariant mass at centre-of-mass energies of 7, 8 and 13 TeV are presented. Integrated and differential cross sections are measured in different phase space regions with varying degree of sensitivity to the electroweak production in vector boson fusion. The cross section for the electroweak W boson...
The study of the associated production of vector bosons and jets constitutes an excellent testbench to check numerous QCD predictions. Total and differential cross sections of vector bosons produced in association with jets has been studied at both 8 and 13 TeV center-of-mass energies. Differential distributions as function of a broad range of kinematical observables are measured and compared...
The associated production of vector bosons, W or Z, and jets originating from heavy-flavour quarks is a large background source in measurements of several standard model processes, Higgs boson studies, and many searches for physics beyond the SM. The study of events with one or two well-identified and isolated leptons accompanied by heavy-flavour jets is crucial to refine the theoretical...
Precision tests of the Standard Model can be successfully performed at the LHC
only if QCD and EW radiative corrections are under control.
In this presentation I will discuss the non trivial interplay between the two sets of corrections, using several observables which can be measured in the Drell-Yan processes to illustrate the conceptual and technical problems that arise in the...
In this talk, we describe the computation of higher-order QED effects relevant in hadronic collisions. In particular, we discuss the calculation of mixed QCD-QED one-loop contributions to the Altarelli-Parisi splittings functions, as well as the pure two-loop QED corrections. We explain how to extend the DGLAP equations to deal with new parton distributions, emphasizing the consequences of the...
Isolated photons with high transverse energy components have been studied in $ep$
scattering with the ZEUS detector at HERA, using 326 pb$^−1$ integrated luminosity. The kinematic region includes photon virtualities 10 < $Q^2$ < 350 GeV$^2$. Photons with transverse energy 4 < $E_T^\gamma$ < 15 GeV and pseudorapidity −0.7 < $\eta^\gamma$ < 0.9 were measured with accompanying jets having...
The production of prompt isolated photons at hadron colliders provides a stringent test of perturbative QCD and can be used to probe the proton structure. The ATLAS collaboration has performed precise measurements of the inclusive production of isolated prompt photons at a center-of-mass energy of 13 TeV, differential in both rapidity and the photon transverse momentum. In addition, the...
Photon production, also in association with jets, is an important
probe of the quark gluon plasma. For many decades, theoretical
predictions of prompt photon production have been based on next-
to-leading order (NLO) calculations. We present a recalculation
of this process at NLO and combine it with parton showers (PS) in
the POWHEG framework. This allows for the first time full...
LHCb, while purpose built for b-physics, also functions as a general purpose forward detector, covering the pseudo-rapidity range 2.0 to 5.0. We present the latest measurements of W and Z boson production. These benchmark measurements are used to constrain the parton distribution functions that describe the inner structure of the proton, and to test the modelling of Standard Model processes....
We present the xFitter project (former HERAFitter) which provides a unique open-source software framework for the determination of the proton's PDFs and for the interpretation of the physics analyses in the context of Quantum Chromodynamics.
We highlight the new xFitter software release which includes state-of-the-art
theoretical developments. We present a novel determination of the photon...
I will review recent progress in the calculation of higher-order QCD corrections and their impact for precision measurements and new physics searches at the LHC.
A precision measurement of jet cross sections in neutral current deep-inelastic scattering for photon virtualities $5.5 < Q^2 < 80$ GeV$^2$ and inelasticities $0.2 < y < 0.6$ is presented, using data taken with the H1 detector at HERA, corresponding to an integrated luminosity of 290 pb$^{−1}$. Double-differential inclusive jet, dijet and trijet cross sections are measured simultaneously and...
We present measurements of multi-differential Jet cross sections over a wide range in transverse momenta from inclusive jets to multi-jet final states. We present studies on the impact these measurements have on the determination of the strong coupling alphas as well as on parton density functions. We also show angular correlations in multi-jet events at highest center-of-mass energies and...
The production of jets at hadron colliders provides a stringent test of perturbative QCD at the highest energies. The process can also be used to probe the gluon density function of the proton. Specific topologies can be used to extract the strong coupling constant.
The ATLAS collaboration has recently measured the inclusive jet production cross section in data collected at a center-of-mass...
We present results on measurements of characteristics of events with jets, from jet-charge over investigations of shapes to jet mass distributions. The measurements are compared to theoretical prediction including those matched to parton shower and hadronization.
We compute cross section for the production of three jets in electron-positron annihilation at next-to-next-to-leading order (NNLO) accuracy. We use a general subtraction scheme developed for computing QCD jet cross sections in perturbation theory. This method is implemented in the Monte Carlo for the CoLoRFulNNLO Subtraction Method (MCCSM) program that provides a general framework for...
High Energy Factorisation was applied so far almost exclusively to Deep Inelastic Scattering process, as computing gauge invariant matrix elements with off shell external legs is a highly non trivial task. In recent years, this problem has been completely solved in a variety of ways, both analytically and numerically. The times are mature to produce the first phenomenological predictions.
We...
In this presentation, we review the general features of integrand-reduction techniques with a particular focus on their generalization beyond one loop. We briefly summarize the ongoing efforts in the field, whose ultimate goal is the development of efficient alternative computational techniques for the evaluation of Feynman integrals beyond one loop. Finally, we describe some recent...
In this talk I will present a new result for the beta function in QCD, valid for a general gauge group. I will briefly summarise the methods which were used to obtain this result and explain its impact on low energy strong coupling extractions and precision observables at NNNNLO in perturbative QCD, such as the Higgs decay width and the total cross section for e+ e- to Hadrons.
The product of the gluon dressing function and the square of the ghost dressing function in the Landau gauge can be regarded to represent, apart from the inverse power corrections $1/Q^{2n}$, a nonperturbative generalization $A(Q^2)$ of the perturbative QCD running coupling $a(Q^2)$ ($\equiv \alpha_s(Q^2)/\pi$). Recent large volume lattice calculations for these dressing functions strongly...
Starting from low energy hadronic input from the particle data book,
we perform a non-perturbative lattice computation of running couplings
up to scales of around 100GeV. The continuum limit is controlled in all
stages. These non-perturbative computations are performed in the
three-flavor theory, yielding $\Lambda^{(3)}$ with around $4\%$ precision.
Matching accross flavor thresholds with...
Combined HERA data on charm production in deep-inelastic scattering
have previously been used to determine the charm-quark running mass
$m_c(m_c)$ in the MSbar renormalisation scheme.
Here, the same data are used as a function of the photon virtuality $Q^2$
to evaluate the charm-quark running mass at different scales to one-loop
order, in the context of a next-to-leading order QCD...
We determine the charm quark mass $m_c(m_c)$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD. Only experimental data for the charm resonances below the continuum threshold are needed in our approach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the zeroth moment....
Multijet processes have always been hard to model precisely in hadron collisions, and reliance of experimental studies and searches on Monte Carlo simulations has been problematic, at times resulting in controversies and retractions. Nowadays matrix-element-based tools can accurately predict the general features of energetic collisions producing several hadronic jets, yet often the huge...
The study of Higgs boson properties form an important part of the LHC program. These studies are not only important for a better understanding of electroweak symmetry breaking mechanism but also for BSM searches. For example, most recently a strategy has been proposed to use LHC measurements of the Higgs transverse momentum distribution to constrain the Yukawa couplings of light-generation...
The KLOE experiment has collected 2.5 fb-1 at the e+e- collider DAPHNE. The upgraded detector KLOE-2 has already collected 3.5 fb-1 with a new beam crossing scheme, allowing for a reduced beam size and increased luminosity. Analysis of KLOE data is still in progress, providing new important results in the light meson sector. VPgamma* transitions have been studied using the phi -> eta e+ e-,...
The COMPASS experiment at CERN has performed a rich programme in inclusive and semi-inclusive deep inelastic scattering of longitudinally polarised muons off longitudinally, transversely polarised and unpolarised nucleons. The main topic is the investigation of the spin structure of the nucleon in terms of quark and gluons, both through accessing the spin dependent collinear parton...
In 2015 the COMPASS collaboration at CERN studied the Drell-Yan process with a 190 GeV/c π− beam on a transversely polarized ammonia target. From single-spin asymmetries COMPASS was able to determine amplitudes related to the proton Sivers, transversity and pretzelosity transverse momentum dependent (TMD) distributions. The most notable of these TMDs is the Sivers function which has...
The Relativistic Heavy Ion Collider (RHIC) is a versatile machine that has provided collision between a wide range of heavy ions, from d to Au, as well as p-p and p-nucleus collisions, over a range of collision energies. Polarized proton program at RHIC provides unique testing ground for the fundamental study of the proton's spin structure. I will present the latest highlights from the PHENIX...
The precision measurement of the anomalous magnetic moment of the muon presently exhibits a 3.5σ discrepancy with the Standard Model (SM) prediction. In the next few years this measurement will reach an even higher precision at Fermilab and
J-PARC. While the QED and electroweak contributions to the muon g-2 can be determined very precisely, the leading hadronic (HLO) correction is affected by...
Overview of recent developments in the PDF field (new PDF sets, new directions), focusing on the most urgent challenges in the PDF fits and the PDF needs
from a point of view of an experimental physicists, for both precision observables and new physics searches.
Parton distribution functions (PDFs) are crucial ingredients for measurements at hadron colliders, since they describe the initial states and therefore critically impact the precision of cross section predictions for observables. This talk will review recent precision analyses, where the PDFs play an important role and discuss the impact of several new ATLAS cross-section measurements on PDFs...
The sensitivity of CMS measurements to Parton Distribution Functions, strong coupling constant and treatment of heavy flavours in QCD analyses is presented. CMS data collected at various center-of-mass energies and their impact on the PDFs are presented. Measurements of cross sections of jet and top-quark pair production are in particular sensitive to the gluon distribution in the proton and...
A phenomenological study of the final combined HERA data on inclusive deep inelastic scattering (DIS) has been performed. The data are presented and investigated for a kinematic range extending from values of the four-momentum transfer, $Q^2$, above 10$^4$ GeV$^2$ down to the lowest values observable at HERA of $Q^2$ = 0.045 GeV$^2$ and Bjorken x, $x_{Bj}$ = 6 x 10−7. The data are well...
We present the updates of CTEQ-TEA parton distribution functions (CT17 PDFs). Previous LHC 7 TeV and HERA 1 data, included in the CT14 PDF analysis, are superseded by HERA 1+2 and new LHC data, especially on W boson, Z boson, inclusive jet, and top quark differential distributions. We also discuss the possibility of a (sizable) non-perturbative contribution to charm parton distribution...
Recently released ATLAS and CMS measurements of the Z transverse momentum distribution in vector boson hadroproduction have the potential to significantly constrain the gluon and light quark PDFs in a range of Bjorken-x that is relevant for Higgs production.
In this talk I will review the most recent data and discuss their inclusion in a PDF determination based on the NNPDF methodology. In...
Recent results on the double parton scattering studies and
measurement of the underlying event activity, performed using
proton-proton collisions data collected using the CMS detector
are presented. Comparisons to previous results at different
center of mass energies are also reported. Latest tests of
double parton scattering, underlying event tunes, minimum bias,
and diffraction are made by...
Recent results on study of exclusive processes of $e^+e^-$ annihilation into hadrons below 2 GeV obtained at the SND detector are presented. The analyses are based on data collected at the VEPP-2M and VEPP-2000 colliders. In particular, we present the precise measurements of the $e^+e^-\to \pi^0\gamma$ and $e^+e^-\to K^+K^-$ cross sections, and the first measurments of the $e^+e^-\to...
The CMD-3 detector is taking data at the VEPP-2000 e+e
collider (BINP, Novosibirsk, Russia). The CMD-3
is the general purpose particle magnetic (1.3 T) detector, equipped with
the tracking system, two crystal (CSI and BGO) calorimeters, liquid Xe
calorimeter, TOF and muon systems. The main goal of experiments with CMD-3
is the measurement of the cross-sections and dynamics of the...
The unambiguous identification and systematic study of bound states beyond the constituent quark degrees of freedom, e.g., multiquark states or states with gluonic degrees of freedom (hybrids, glueballs) would provide validation of and valuable input to the quantitative understanding of QCD. Hadron spectroscopy is one of the most important physics goals of BESIII. Since 2009, BESIII has...
We report some of the most recent results in studying different aspects of QCD with about 500 fb$^-1$ of data collected by the BaBar experiment at the e+e- $B$-factory PEP-II.
In particular, we present Dalitz plot analyses of the hadronic three-body $J/\psi$ decays to $\pi^+\pi^-\pi^0$, $K^+K^-\pi^0$, and $K_S K^{\pm}\pi^{\mp}$ using an isobar model and a Veneziano model. We then show the...
In this talk we present results of our study of the next-to-leading order corrections to deeply virtual pion and kaon production in neutrino experiments. We estimate these corrections in the kinematics of the Minerva experiment at FERMILAB, and find that they are sizable and increase the leading order cross-section by up to a factor of two. Also, we estimate the cross-sections of the...
The presentation will be based on our paper in preparation [1].
We discuss production of pairs of $J/\psi$ in pp collisions in the context
of recent results obatained at the LHC at large transverse momenta.
The leading-order $O(\alpha_s^4)$ contribution
is calculated in both collinear and the $k_t$-factorization approach
with the KMR UGDF.
We include also two-gluon exchange contribution ...
I will discuss spectroscopic properties of heavy quarkonium hybrids
derived in the last year in the systematic framework of nonrelativistic effective field theories. Results will be compared with data and lattice determinations.
Measurements of open charm production are presented in diffractive deep inelastic scattering (5<Q2<100 GeV2), based on 287 pb−1 of H1 HERA-II data recorded at the center of mass energy sqrt(s)=319 GeV. The event topology is given by ep→eXY , where the system X, containing at least one D⋆(2010) meson, is separated from a leading low-mass proton dissociative system Y by a large rapidity gap. The...
A search for a narrow baryonic state in the $pK_S^0$ and $\bar{p}K_S^0$ system has been performed in $ep$ collisions at HERA with the ZEUS detector using an integrated luminosity of 358 pb$^{−1}$ taken in 2003-2007. The search was performed with deep inelastic scattering (DIS) events at an $ep$ centre-of-mass energy of 318 GeV for exchanged photon virtuality, $Q^2$, between 20 and 100 GeV$^2$....
We use the full Run II dataset consisting of $10.4\ \rm fb^{−1}$ of $p\bar p$ collisions recorded by the D0 detector at the Fermilab Tevatron collider at $\sqrt s=1.96\ $TeV to search for new exotic multiquark states. We report the evidence of a new state X(5568) decaying to $B^0_s\pi$ seen in the $B^0_s \to J/\psi\phi$ decay channel and its independent confirmation in the semi-leptonic...
After the unambiguous confirmation of the resonant behaviour of the Zc(4430) charmonium-like state and the observation of two pentaquark states, it is a main goal for the heavy flavour experiments to complete the picture with searches for the many partners the quark model predicts. We report on several studies of b-hadron decay modes potentially involving exotic intermediate states, including...
Theoretical results on heavy meson exotic spectroscopy will be presented mainly concentrating on hybrid heavy charmonia and bottomonia states. Theoretical results
for heavy hybrids states, c-antic-gluons systems, will be compared with experimental data. Finally the emerging differences for exotic mesons when described as compact tetraquarks, hybrid mesons, molecules or core mesons plus higher...
We show that the correlation functions involving exotic tetra- and penta-quark currents in QCD have fundamentally different properties compared with the correlation functions of the bilinear quark current, the interpolating currents for the normal hadrons. Taking into account the fact, that the exotic currents of different structures may be used as the interpolating currents for one and the...
