Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session X15: Hadron ResonancesLive
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Sponsoring Units: GHP Chair: Garth Huber, University of Regina |
Tuesday, April 20, 2021 10:45AM - 10:57AM Live |
X15.00001: Excited $J^{--}$ meson resonances at the $SU(3)$ flavor point from lattice QCD Christopher Johnson While the lightest vector mesons, the $\rho$, $\omega$ and $\phi$ are well understood and the inspiration for phenomenological statements like the OZI rule, their excited states remain poorly known. In the first lattice QCD study of its kind, the spectrum of excited $J^{PC}=1^{- -}$ resonances is determined, finding two vector states, one lighter and broad, and the second heavier and narrow. The $2^{- -}$ and $3^{- -}$ partner states are also extracted in this calculation. \[\] based upon material appearing in \[\] arXiv:2012.00518 \[\] C.T. Johnson and J.J. Dudek \[\] for the Hadron Spectrum Collaboration [Preview Abstract] |
Tuesday, April 20, 2021 10:57AM - 11:09AM Live |
X15.00002: Decays of an exotic $1^{-+}$ hybrid meson resonance in QCD Jozef Dudek For the first time using lattice QCD we determine an exotic $1^{-+}$ hybrid meson appearing as a resonance in coupled-channel scattering. The calculation, performed with an exact SU(3) flavor symmetry, suggests that the hybrid has a large coupling to at least one axial-vector -- pseudoscalar channel. A simple extrapolation to the physical light quark mass suggests a broad $\pi_1$ decaying dominantly through the $b_1 \pi$ mode. Based upon material presented in arXiv:2009.10034 by A.J. Woss, J.J. Dudek, R.G. Edwards, C.E. Thomas and D.J. Wilson for the Hadron Spectrum Collaboration [Preview Abstract] |
Tuesday, April 20, 2021 11:09AM - 11:21AM Live |
X15.00003: Longitudinal Spin Transfer to $\Lambda^0$ Hyperons in CLAS12 Matthew McEneaney Using the self analyzing decay of the $\Lambda^0$, the longitudinal spin transfer $D_{LL}$ from a polarized electron beam scattering an unpolarized proton target to the hyperon can be measured. For $\Lambda$'s produced in the current fragmentation region, this quantity is proportional to the helicity dependent fragmentation function $G_1^\Lambda$ and can provide insight into the spin structure of the $\Lambda^0$. Currently, experimental data on $D_{LL}$ is limited and is not able to discriminate between different models of the $\Lambda^0$ spin structure. This contribution will report the status of the ongoing analysis of the longitudinal spin transfer using data taken by the CLAS12 experiment at Jefferson Lab, a large acceptance spectrometer using a 10.6 GeV electron beam. [Preview Abstract] |
Tuesday, April 20, 2021 11:21AM - 11:33AM Live |
X15.00004: Analysis of $\pi^+\pi^-$ mass spectrum in $\chi_{c1}(3872)\to\pi^+\pi^- J/\psi$ decays Baasansuren Batsukh The $\pi^+\pi^-$ mass spectrum in $\chi_{c1}(3872)\to\pi^+\pi^- J/\psi$ decays is analyzed to probe for its resonant content. This can shed light at the nature of this exotic hadron candidate. The data sample of $B^{\pm}\to K^{\pm}\chi_{c1}(3872)$ events is selected for a good control of the backgrounds and for the optimal mass resolution. The data were obtained with the LHCb detector, and corresponds to 9 fb$^{-1}$ of the integrated luminosity in $pp$ collisions at the LHC. [Preview Abstract] |
Tuesday, April 20, 2021 11:33AM - 11:45AM Live |
X15.00005: Amplitude analysis of $B^0\to J/\psi K^+\pi^-$ and of $B^0\to\psi(2S) K^+\pi^-$ decays Andrew Beiter Amplitude analysis of $B^0\to J/\psi K^+\pi^-$ and of $B^0\to \psi(2S) K^+\pi^-$ decays is performed to probe for exotic hadron contributions, like the previously reported $Z_c(4430)^-\to\psi(2S)\pi^-$ and $Z_c(4200)^-\to J/\psi \pi^-$. The data were obtained with the LHCb detector, and corresponds to 9 fb$^{-1}$ of the integrated luminosity in $pp$ collisions at the LHC. [Preview Abstract] |
Tuesday, April 20, 2021 11:45AM - 11:57AM Live |
X15.00006: Spectroscopy at LHCB Ivan Polyakov Spectroscopy of hadron states, in particular those formed of heavy quarks, is a crucial source of knowledge for qcd and during last 15 years its importance was reinforced by many observations of new exotic hadron states. Thankfully to high luminosity of LHC, high b/c-hadron production cross-section and unique capabilities of LHCB detector in reconstructing b/c-hadron decays LHCB experiment has unprecedented opportunities for related spectroscopy studies. In the talk the latest results on spectroscopy of b/c-hadron states, including exotic ones, will be reported along with prospects for run3. [Preview Abstract] |
Tuesday, April 20, 2021 11:57AM - 12:09PM Live |
X15.00007: Masses of doubly heavy tetraquarks with error bars Abhishek Mohapatra, Eric Braaten, Liping He In the heavy-quark limit, the two heavy quarks in a doubly heavy baryon or a doubly heavy tetraquark are bound by their color-Coulomb potential into a compact diquark. The doubly heavy hadrons are related by the approximate heavy-quark--diquark symmetry of QCD to the heavy hadrons obtained by replacing the heavy diquark by a heavy antiquark. Effective field theories can be used to expand the masses of singly heavy hadrons and doubly heavy hadrons in inverse powers of the heavy quark masses. The coefficients in the expansions for doubly heavy tetraquarks can be determined from those for heavy mesons, heavy baryons, and doubly heavy baryons using heavy-quark--diquark symmetry. We predict the masses of the ground-state doubly heavy tetraquarks with error bars using as inputs the masses of heavy mesons and heavy baryons measured in experiments and the masses of doubly heavy baryons calculated using lattice QCD. The only doubly heavy tetraquarks predicted to be stable with respect to strong decays are $bb$ tetraquarks with light flavor $\bar u \bar d$, $\bar s \bar u$ and $\bar s \bar d$. [Preview Abstract] |
Tuesday, April 20, 2021 12:09PM - 12:21PM Live |
X15.00008: Search for excited $\Xi^{*}$ states and preliminary cross section for $\Xi^-(1530)$ Brandon Sumner Constituent quark models (CQMs) and lattice calculations often predict many more states than have been observed, the so-called “missing resonance” problem. For example, the Particle Data Group (PDG) tables indicate evidence for ten states for the cascade baryon, five of which presently have only fair or poor ratings; yet, relativized quark model calculations predict 45 states with masses in the same range as those in the PDG. Thus, providing additional evidence for the known $\Xi$ resonances and discovering new excited states will help greatly improve models, as well as identifying the most salient features necessary for predicting baryon resonances. Experimentally, using $\Xi$ in the hunt for missing resonances has the advantage that those final states are expected to have much narrower widths compared to N* and $\Delta$* resonances, facilitating identification. To better elucidate the cascade resonance spectrum, the GlueX experiment continues to obtain data for reconstructing $\Xi$ resonances. Utilizing GlueX data, invariant mass distributions for the $\Xi^{-} $$\pi^{0}$ system will be shown, along with preliminary cross section measurements for $\gamma$ p $\rightarrow$ $ K^{+} $$K^{+} $$\Xi^-(1530)$. [Preview Abstract] |
Tuesday, April 20, 2021 12:21PM - 12:33PM Live |
X15.00009: Inclusive electroproduction in the resonance region Astrid Hiller Blin, Wally Melnitchouk, Victor Mokeev We study the resonant contributions into the proton inclusive structure functions in the resonance region. The results on longitudinal/transverse virtual photon cross sections and the structure functions have been updated based on the JLab Hall C results on the longitudinal over transverse cross section ratio. The resonant contributions are evaluated from the JLab CLAS Collaboration results on the nucleon resonance electroexcitation amplitudes, accounting for the interference between all resonances. Our studies have demonstrated that the resonance contribution into inclusive electron scattering remains substantial at all photon virtualities where data are available so far, up to $Q^2$ of 4.0 GeV$^2$. Furthermore, the $Q^2$-evolution of the resonant contributions within the first, second and third resonance regions demonstrates pronounced differences, emphasizing the need for the exploration of the electroexcitation amplitudes for all prominent resonances. These studies are essential for new insights into the nucleon ground-state PDFs in the resonance region, which allow us for the first time to compare the experimental structure functions obtained in the resonance region with those computed from the PDF fit to the data in the DIS region. [Preview Abstract] |
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