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Higgs boson mass measurement in H→ZZ∗→4ℓ
Get PDFThe projection of the measurement of the Higgs boson mass in the H → ZZ∗ → 4l (l = e, μ) using the CMS experiment at High-Luminosity LHC in proton-proton collisions at √s = 14 TeV using an integrated luminosity of 3000 fb−1 is presented here. The projection will be compared with the last published result by CMS. In addition to the increased luminosity, the analysis benefits from major upgrades in the CMS detectors as well as from enhanced analysis strategies
Spectroscopy of hadrons with heavy quarks from lattice QCD
Get PDFLattice QCD results on hadrons with heavy quarks are briefly reviewed. The focus is on the spectrum of conventional and exotic hadrons. Structure of certain conventional hadrons is addressed as well
Non-strange light-meson spectroscopy at COMPASS
Get PDFLattice QCD predicts the exotic meson π1(1600) to dominantly decay to b1π. The b1π decay channel is accessible via the ωπ−π0 final state. COMPASS recorded the so far largest data set of this final state. A partial-wave analysis allows
to determine the resonant content in this final state including possible contributions from π1(1600). Decomposing the measured intensity into amplitudes of partial waves
gives a first qualitative insight into contributing intermediate states. We observe signals in agreement with well-established states like the π(1800) and a4(1970).
Smaller resonance-like signals are visible in the JP C sectors 3++ and 6++, where possible states were claimed but none are established. For JP C = 1−+ a signal at 1.65 GeV/c2 in b1(1235)π partial waves is consistent with the expected π1(1600)
Light-meson spectroscopy with GlueX and beyond
Get PDFThe GlueX experiment at Jefferson Lab was specifically designed for precision studies of the light-meson spectrum. For this purpose, a photon beam with energies up to 12 GeV is directed onto a liquid hydrogen target contained within a
hermetic detector with near-complete neutral and charged particle coverage. Linear polarization of the photon beam with a maximum around 9 GeV provides additional information about the production process. In 2018, the experiment completed its first phase, recording data with a total integrated luminosity above 400 pb−1. We highlight a selection of results from this world-leading data set with emphasis on the search for light hybrid mesons. In the mean time, the detector underwent significant upgrades and is currently recording data with an even higher luminosity. The future plans of the GlueX experiment to explore the meson spectrum with unprecedented precision are summarized
Latest results on B+c at ATLAS and CMS
Get PDFThe present report summarizes recent results on the B+c meson from the CMS and ATLAS experiments at the LHC: aspects such as the B+c production, its decay mechanisms and the observation of excited states are investigated
Glueballs from Dyson-Schwinger and Bethe-Salpeter equations
Get PDFThe quenched spectrum of glueballs with positive charge parity is calculated from two-body bound state equations. As input, a self-contained solution for the primitively divergent correlation functions from Dyson-Schwinger equations is used. It only has one parameter to be set which is the physical scale. An important feature of this setup is the consistent construction of the bound state kernels along
the same lines as the equations from which the input was obtained. Keeping only the one-particle exchanges, already good agreement with lattice results is obtained. For the tensor glueball, we present first results including two-loop contributions, elevating its calculation to the same level of truncation as for the spin zero glueballs for which such calculations have been done previously
Tcc states of D∗D∗ and D∗sD∗ molecular nature
Get PDFThe newly observed Tcc state can be explained as a molecular state of D∗D in the chiral unitary approach. An extension to D∗D∗ and D∗ sD∗ systems in the JP = 1+ will be discussed in the present work. We make predictions that the D∗D∗ system leads to a bound state with a binding of the order of MeV and
similar width, while the D∗ sD∗ system develops a strong cusp around threshold
Progress in the partial-wave analysis methods at COMPASS
Get PDFWe study the excitation spectrum of light and strange mesons in diffractive scattering. We identify different hadron resonances through partial-wave analysis, which inherently relies on analysis models. Besides statistical uncertainties, the model dependence of the analysis introduces dominant systematic uncertainties. We discuss several of their sources for the π−π−π+ and K0 SK− final states and present methods to reduce them. We have developed a new approach exploiting a priori knowledge of signal continuity over adjacent final-state–mass bins to stably
fit a large pool of partial waves to our data, allowing a clean identification of very small signals in our large data sets. For two-body final states of scalar particles,
such as K0 SK−, mathematical ambiguities in the partial-wave decomposition lead to the same intensity distribution for different combinations of amplitude values. We will discuss these ambiguities and present solutions to resolve or at least reduce the number of possible solutions. Resolving these issues will allow for a complementary analysis of the aJ -like resonance sector in these two final states
Probing hadron formation through the study of strange particles in different collision systems and energies with ALICE at the LHC
Get PDFStrange hadrons constitute a unique tool for studying hadronization. While their production yield was first proposed as a clean signature of quark-gluon plasma (Rafelski J., Eur. Phys. J. ST, 229 (2020) 1) formation in heavy-ion collisions, at present the role of strangeness production in large and small collision systems is pivotal in understanding how a colored system evolves into the observed gas of mesons and baryons. This process started to be explored in more detail after the ALICE Collaboration made the groundbreaking observation that strange-hadron
yields increase with charged-particle multiplicity density, regardless of the collision system or the center-of-mass energy (ALICE Collaboration, Nat. Phys., 13 (2017) 535). The data also shows that transverse momentum spectra in elementary interactions are affected by partonic collectivity even when only few particles are produced at midrapidity (Kalweit A., Nucl. Phys. A, 982 (2019) 1). In this proceedings, a complete overview of the latest findings in the study of strangehadron production at the LHC will be presented, with special emphasis on the discussion of present and future prospects of this field in view of the LHC Run 3 data taking campaign
Chiral symmetry restoration in nuclear medium observed in pionic atoms
Get PDFWe interpret the spectral information of the pionic 1s and 2p states in the 121Sn nucleus observed with unprecedented precision and resolution with respect to the in-medium pion-nucleus interaction to deduce partial restoration of the chiral symmetry in the high density of the nuclear matter. Most recent theoretical and experimental results are integrated to obtain the precision information on the partial restoration of the chiral symmetry. We find reduction of the chiral condensate in the Sn nucleus by a factor of 77 ± 2% at the nucleon density of 0.098 fm−3. The
result is compared with the chiral theories showing fairly good agreement