Conveners
QCD and Hadronic Physics
- Marek Schoenherr (University of Durham)
- Mikko Voutilainen (Helsinki Institute of Physics (FI))
- Gabor Veres (Eotvos Lorand University (HU))
- Bogdan Malaescu (Centre National de la Recherche Scientifique (FR) & CERN)
QCD and Hadronic Physics
- Mikko Voutilainen (Helsinki Institute of Physics (FI))
- Gabor Veres (Eotvos Lorand University (HU))
- Bogdan Malaescu (Centre National de la Recherche Scientifique (FR) & CERN)
- Marek Schoenherr (University of Durham)
QCD and Hadronic Physics
- Mikko Voutilainen (Helsinki Institute of Physics (FI))
- Bogdan Malaescu (Centre National de la Recherche Scientifique (FR) & CERN)
- Marek Schoenherr (University of Durham)
- Gabor Veres (Eotvos Lorand University (HU))
QCD and Hadronic Physics
- Bogdan Malaescu (Centre National de la Recherche Scientifique (FR) & CERN)
- Marek Schoenherr (University of Durham)
- Gabor Veres (Eotvos Lorand University (HU))
- Mikko Voutilainen (Helsinki Institute of Physics (FI))
We discuss the parton branching (PB) evolution equation for transverse momentum dependent (TMD) parton distribution functions (PDFs), especially we concentrate on the angular ordering constrain and its effect on the TMD distributions.
We discuss application of the PB TMDs to precise prediction of Drell-Yan transverse momentum spectrum at LHC, especially we stress the role of angular ordering...
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 2018, the machine has...
We present the chiral corrections to the pseudoscalar current transition form factors of the delta in relativistic baryon chiral perturbation theory up to third chiral order using the complex-mass renormalization scheme (CMS) to generate a systematic power counting. We analyze the form factors $\tilde{g}(q^2)$ and $\tilde{h}(q^2)$ which are relevant to address the $\pi \Delta \Delta$ coupling...
We discuss $\gamma^* \gamma^* \to \eta_c(1S)\, , \,\eta_c(2S)$ transition form factor for both virtual photons. The general formula is given. We use different models for the $c \bar c$ wave function obtained from the solution of the Schr\"odinger equation for different $c \bar c$ potentials: harmonic oscillator, Cornell, logarithmic, power-law, Coulomb and Buchm\"uller-Tye. We compare our...
We study manifestations of the Melosh spin rotation effects in diffractive electroproduction of heavy quarkonia off a nucleon target.
The quarkonia wave functions are determined within the Schroedinger equation based formalism using realistic potentials, which describe the interaction between heavy quark and antiquark.
The large importance of the Melosh spin transformation is analysed within...
We study color allowed $\Lambda_b\to \Lambda^{(*,**)}_c M^-$, $\Xi_b\to\Xi_c^{(**)} M^-$ and $\Omega_b\to\Omega^{(*,**)}_c M^-$ decays with $M=\pi, K, D, D_s, \rho, K^*, D^*, D^*_s, a_1$ and $s$-wave and $p$-wave charmed baryons, including $\Lambda^{(*,**)}_c=\Lambda_c, \Lambda_c(2595), \Lambda_c(2625), \Lambda_c(2765), \Lambda_c(2940)$,$\Xi_c^{(**)}=\Xi_c, \Xi_c(2815), \Xi_c(2790)$ and...
The future circular collider (FCC) study released a conceptual design report (CDR) in January 2019. An electron machine is considered as a first step (FCC-ee) with up to four detectors. FCC-ee is capable of very high luminosities in a wide center-of-mass (ECM) spectrum from 90 to 365 GeV. FCC-ee provides a clean experimental environment, produces high luminosity for precision measurements of...
The Large Hadron-electron Collider (LHeC) is a proposed upgrade of the LHC at CERN. It consists of an ERL providing electrons to collide with the HL-LHC, HE-LHC and the FCC-hh proton beams. These ep configurations will achieve centre-of-mass energies 1.3-3.5 TeV and luminosities $\sim 10^{34}$ cm$^{โ2}$ s$^{-1}$ which extends the HERA kinematic coverage by more than one order of magnitude...
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...
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 โs=8 TeV....
We present fits to determine parton distribution functions (PDFs) using top-antitop, inclusive W/Z-boson, as well as W+ and Wโ boson production measurements in association with jets 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...
Non-perturbative QCD effects from Parton Distribution Functions (PDF) at hadron colliders may be constrained by using high statistics Large Hadron Collider (LHC) data. Drell-Yan (DY) measurements in the Charged Current (CC) case provide one of the primary channels to do this, in the form of the lepton charge asymmetry. We investigate here the impact of measurements in Neutral Current (NC) DY...
Isolated photons with high transverse energy have been studied in deep inelastic $ep$ scattering with the ZEUS detector at HERA, using an integrated luminosity of $326\, \mathrm{pb}^{-1}$ in the range of exchanged-photon virtuality $10 - 350 \,\, \mathrm{GeV}^2$. Outgoing isolated photons with transverse energy $4 < E_T^\gamma < 15$ GeV and pseudorapidity $-0.7 < \eta^\gamma < 0.9$ were...
We present a study for the generation of events from a physical process with generative deep learning. To simulate physical processes it is not only important to produce physical events, but also to produce the events with the right frequency of occurrence (density). We investigate the feasibility to learn the event generation and the frequency of occurrence with Generative Adversarial...
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...
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 gโb bbar using data collected with the ATLAS detector at โs=13 TeV. Track jets are used to probe angular scales below the standard R=0.4...
New results on jet fragmentation measurements at LHCb are presented. LHCb has probed the fragmentation of light and heavy flavour jets, with results showing significant discrepancies with theoretical predictions found using standard Monte Carlo event simulation. These are the first measurements of jet hadronisation and fragmentation at forward rapidities at the LHC. Results from LHCb of J/Psi...
As the experimental precision at the LHC keeps improving, next-to-next-to leading order (NNLO) corrections for scattering processes have become crucial for providing theoretical predictions of comparable accuracy. The scattering amplitudes are a fundamental ingredient of these theoretical predictions, and the perturbative analytic calculations are extremely valuable. While NNLO calculations...
I will present a framework to compute two-loop five-point amplitudes that combines
integrand reduction, integration-by-part identities and finite-field reconstruction techniques. Analytic results for two-loop five parton amplitudes obtained using the framework will also be discussed.
The CMS Open Data project offers new opportunities to measure Standard Model (SM) Production Cross Sections which have not been probed so far. In this work, we evaluate the challenges and the opportunities of the CMS Open Data
project in the view of cross-section measurements. In
particular we reevaluate SM cross-sections of the production of W-bosons, Z-bosons, top-quark pairs and WZ...
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...
We suggest that generalized parton distributions can be probed in charged current meson production process, like $ep\to e\pi^{โ}p$ and $ep\to e\rho^{โ}p$. In contrast to pion photoproduction, this process is sensitive to the unpolarized GPDs $H, E$, and for this reason has a very small contamination by higher twist and Bethe-Heitler type contributions. We prove that the simultaneous study of...
Transverse Momentum Dependent parton distribution functions allow to take into account apart from the proton momentum fraction also transverse momenta of initial partons in the description of hadronic cross-section. They are therefore a promising tool to obtain a more precise description of kinematics of hadronic observables. In this talk we present our most recent results in the ...
The PPS (Precision Proton Spectrometer) detector system consists of silicon tracking stations as well as timing detectors to measure both the position and direction of protons and their time-of-flight with high precision. They are located at around 200 m from the interaction point in the very forward region on both sides of the CMS experiment. PPS is built to study Central Exclusive Production...
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 LHCb detector at the LHC offers unique coverage of forward rapidities. This enables complementary measurements of soft QCD phenomena to those at the other LHC detectors. Measurements of the inelastic cross-section and of particle production will be presented. Measurements of Central Exclusive Production (CEP) at LHCb will also be presented. These measurements probe QCD, allowing...
We analyze in detail the LHC prospects at the center-of-mass enery of 14 TeV 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...
We present recent results on study of exclusive processes of $e^+e^-$ annihilation into hadrons with the SND detector. Data were collected at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range from 0.3 to 2 GeV. In particular, we have measured the cross sections for $e^+e^-\to \pi^+\pi^-$ and $n\bar{n}$, studied the radiative decays of excited light vector mesons to...
The KLOE-2 experiment completed its data-taking at the e+e- DAPHNE collider in Frascati, achieving the integrated luminosity goal of more than 5 fb-1 at the phi peak. KLOE-2 represents the continuation of KLOE with an upgraded detector and an extended physics program, which includes the study of light meson properties and decay dynamics with unprecedented statistics. The new data sample,...
The CMD-3 experiment at the VEPP-2000 collider in Novosibirsk carries out a comprehensive study of the exclusive cross-sections of $e^+e^- \to hadrons$ in the center-of-mass energy range from the threshold to $\sqrt{s}<2$ GeV. The energy scan of the whole energy range was performed in 2011-2013 and, after detector and collider upgrade and increase in luminosity by factor 2-3, in 2017-2019. The...
We present measurements of absolute branching fractions of the two-body decays of $B$ mesons ${\cal{B}}(B \to K + X)$, where $X$ is a charmonium state, by using a data set corresponding to about 470 fb$^{-1}$ collected by the $BABAR$ detector at the PEP-II $e^+e^-$ collider. For events in which one $B$ is fully reconstructed, the charmonium spectrum can be observed in an unbiased way by...
The evaluation of the hadronic vacuum polarisation contribution to the muon magnetic anomaly is reappraised using the latest e+e- โ hadrons cross-section data. A fit incorporating constraints from analyticity and unitarity of the dominant two-pion form factor allows to significantly reduce the uncertainty in the evaluation at low energy where the measurements are scarce and less precise. The...
I will present a number of calculations relevant for hadronic
contributions to the muon $g-2$. These include issues relevant for the
Light-by-light part, i.e. proper constraints on the short-distnace part [1]
and understanding a number of aspects of pion-exchange, here with
regards to the cancellation between connected and disconnected parts
in lattice QCD, and the two-pion contribution [2]....
We determine the strong coupling, $\alpha_s$, using finite-energy sum
rules and a new compilation of the hadronic $R$-ratio from available
data for $e^+e^- \to {\rm hadrons}$ below the charm threshold. Quoting our
final results at the tau mass to facilitate comparison to the results
of analyses of hadronic tau decay data, we find
$\alpha_s(m_\tau^2) = 0.298 \pm 0.017$ in fixed-order...
We discuss the status of determinations of the strong coupling with special attention to using event shape observables based on data collected at the Large Electron Positron collider and theoretical predictions at highest accuracy available at present. We argue that such extractions can be competitive with lattice determinations if the observables are selected carefully such that both higher...
The strong coupling constant $\alpha_s$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of $\alpha_s(m_Z)$ at the Z-boson mass $m_Z$ are studied as a function of the...
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...
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 will include a review of inclusive jet measurements performed by the CMS collaboration.
Production of jets, top quarks and electroweak bosons in proton-proton collisions at the LHC probes the fundamental parameters of the Standard Model as quark masses or the strong coupling constant. Furthermore, the constraints on the parton distribution functions of the proton can be probed by including the measurements of these processes in a QCD analysis. New insights into the proton...
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 Rฮฯ. 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...
New results on heavy-flavor production in proton-proton collisions will be presented. The measurements are performed using data collected during 2015-2018 at a centre-of-mass energy of 13 TeV in the forward region. Results from different charmonia states and b-hadrons will be covered in the talk.
Recent results on beauty and charm production with the CMS experiment, based on data collected in Run 1 and Run 2 of the LHC, are presented. Measurements of open charm production cross sections, a study of Upsilon(1S) production versus charged-particle multiplicity, and a study of jet fragmentation in J/psi mesons are presented.
Heavy quarks (charm and beauty) are effective probes of the Quark-Gluon Plasma (QGP) formed in high-energy nuclear collisions. They are produced in the initial hard partonic scatterings of the collisions, propagate through the medium, and interact with its constituents, thus probing the entire evolution of the system.
Heavy-flavour measurements in pp and p--Pb collisions not only provide the...
Heavy quarks are particularly useful probes to investigate the properties of the Quark-Gluon Plasma produced in heavy-ion collisions at the LHC, since they are produced on a shorter timescale than that of the hot fireball. To single out the signals that are characteristic of the QGP, it is nevertheless crucial to understand the primordial heavy-quark production in vacuum, i.e. in inelastic...
Measurements of open charm and beauty production cross sections in deep inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections are obtained in the kinematic range of negative four-momentum transfer squared of the photon $2.5$ GeV${}^2\le Q^{2} \le 2000$ GeV${}^2$ and Bjorken scaling variable $3\cdot 10^{โ5}\le x_{Bj}\le 5\cdot 10^{โ2}$ . The...
The large data sample accumulated by the Belle experiment at KEKB asymmetric energy e^+ e^- collider provides a unique opportunity to perform studies of charmed strange baryons. In this presentation, we report a measurement of the absolute branching fraction of Xi_c^0 and Xi_c^+. We present observation of Xi(1620)^0 and evidence for Xi(1690)^0 found in the decay Xi_c^+ -> Xi^0 pi^+ pi^-, and...
The LHCb detector is an excellent tool for studying b-hadron decays to charmonium, benefiting from a large b-hadron sample, an efficient trigger and good mass resolution. Such decays provide insight into properties of both conventional and exotic charmonium, and can also probe the factorization approach. Recent results in this area are presented.
A salient feature shared by all tetraquark candidates observed in experiment is the absence of flavor-exotic states of the type $\bar ab \bar cd$, with four different quark flavors.This phenomenon may be understood from the properties of large-Nc QCD: On the one hand, previous work shows that consistency conditions for flavor-exotic Green functions, potentially containing these tetraquark...
Coherence leads to $p_T$ broadening of partons in high-multiplicity events, which is a manifestation of the effect of parton saturation. Appearance of the saturation scale generates via DGLAP evolution an enhancement of low-x gluons. Mutual enhancement of low-x gluons in both colliding hadrons (pp, AA) results in an even stronger boost of the saturation scales. This explains the observed steep...
ALICE has performed several measurements aimed at understanding the heavy-ion-like patterns observed in small collision systems. New approaches can be helpful to clarify particle production mechanisms in pp collisions, as well as the similarities observed among the systems created in pp, p-A and A-A collisions.
In this talk we report on charged-particle transverse momentum distributions as a...
The matrix elements for $g^* g^* \to \chi_c(J_i) \chi_c(J_j)$
for off-shell gluons were derived [1].
The matrix elements are used then in the $k_t$-factorization
approach for the $p p \to \chi_c(J_i) \chi_c(J_j)$ reaction.
Different combination of the $chi_c$ mesons are considered.
We use the Kimber-Martin-Ryskin (KMR) unintegrated gluon distributions
to evaluate cross sections. We...
Measurements of the production of short-lived hadronic resonances are used to probe the properties of the late hadronic phase in ultra-relativistic heavy-ion collisions. Since these resonances have lifetimes comparable to that of the produced fireball, they are sensitive to the competing effects of particle re-scattering and regeneration in the hadronic gas, which modify the observed particle...
We present a model with which we predict the cross sections for exclusive and dissociativeย photo andย electroproduction of light and heavy vector mesonsย off protons; the model describes correctlyย available experimental data. The model is based on the color-dipole approach and incorporates geometric fluctuations of the target-proton partonic structure. The fluctuations are generated as randomly...
The studies on the propagation of the color charge and hadron formation in nuclear medium allow to explore mechanisms intimately related to confinement and asymptotic freedom. This fundamental topic has been of interest to multiple communities: Drell-Yan, heavy-ion collisions and Semi-Inclusive DIS, all of which contribute different but complimentary information. A unique feature of SIDIS is...