Conveners
Section C
- Antonio Vairo (TUM )
Section C
- Antonio Vairo (TUM)
Section C
- Joan Soto (Universitat de Barcelona)
Section C
- Pavel Pakhlov (Lebedev's Physical Institute)
Section C
- Pavel Pakhlov (Lebedev's Physical Institute)
Section C
- Pavel Pakhlov (Lebedev's Physical Institute)
Section C
- Antonio Vairo (TUM)
Section C
- Joan Soto (Universitat de Barcelona)
Description
Section C: Heavy Quarks
Heavy-light mesons, heavy quarkonia, heavy baryons, heavy exotics and related topics: phenomenology of spectra, decays, and production; effective theories for heavy quarks (HQET, NRQCD, pNRQCD, vNRQCD, SCET); sum rules for heavy hadrons; lattice calculations of heavy hadrons; heavy-quark masses determination; experiments.
Conveners: G. Bodwin (Argonne NL), P. Pakhlov (ITEP, Moscow), J. Soto (U. Barcelona), A. Vairo (TU Munich)
Heavy quarks (charm and beauty) are interesting probes to study the Quark-Gluon Plasma (QGP) in high-energy heavy-ion collisions, since they are produced in initial hard partonic scattering processes on a short time scale and experience the whole evolution of the medium. They are expected to traverse the QCD medium, interacting with its constituents and losing energy through radiative and...
We present results of simulations of the RQCD Collaboration on open charm states, including a scattering analysis of scalar and axialvector $D_s$ mesons near the physical pion mass, utilizing different spatial volumes. The spectra are obtained, using $N_f=2$ QCDSF and RQCD as well as $N_f=2+1$ CLS ensembles, employing non-perturbatively improved Wilson fermions. In the latter case,...
The extraction of the $B \to K^*$ transition form factors from lattice data at (close to) physical pion masses is discussed. The possible mixing of $\pi K$ and $\eta K$ states is taken into account. Applying non-relativistic effective field theory in a finite volume, the two-channel analogue of the Lellouch-Luscher formula is reproduced. Due to the resonance nature of the $K^*$ , it is shown...
We analyze long-distance QCD effects in $B_{d,s}\to\ell^+\ell^-\gamma$ decays.
Taking into account photon emission from the $b$-quark loop, weak annihilation,
and Bremsstrahlung from leptons in the final state, we give predictions
for dilepton spectrum and various asymmetries in $B_{d, s}\to \ell^+\ell^-\gamma$ decays within the Standard Model.
We present the results of our recent calculations of the hadronic form factors for semileptonic decays of B mesons and the matrix elements of local operators contributing to neutral B and Bs meson mixing. From joint fits of the lattice results and the experimental data we are able to determine the magnitude of the CKM matrix elements Vub and Vcb, and also (with Vtb as an additional input) the...
We present a lattice QCD study of coupled-channel $D\pi$, $D\eta$ and $D_{s}\bar{K}$
scattering, as well single-channel $DK$ scattering. Our methodology allows us to determine precise finite volume spectra which we use to constrain scattering amplitudes as a function of energy. We interpret our results in terms of poles in the $S$-matrix and provide a measure of the coupling of each channel...
We show that having at hand the analytic expression for the correlation functions allows one to study subtle effects related to isospin-breaking effects in the decay constants of heavy pseudoscalar and vector mesons. We obtain predictions for these effects in fD, fD, fB and fB mesons.
The aspects of mesons containing a single heavy quark are governed by the spin symmetry $SU(2)_s$ of the heavy quark and the chiral symmetry $SU(3)_L\times SU(3)_R$ of the light quarks. Incorporating both approximate symmetries in a single framework was achieved by defining the heavy meson chiral perturbation theory (HMChPT).
The masses of D and B mesons are analysed within this effective...
The mass of the bottom quark can be determined with high precision from moments of the pair-production cross section $\sigma(e^+ e^- \to b \bar{b})$ near threshold. We present the first complete NNNLO determination from non-relativistic sum rules, obtaining a bottom-quark mass of $m_b^\text{PS}(2\,\text{GeV}) = 4.532^{+0.013}_{-0.039}\,\text{GeV}$ in the potential-subtracted scheme. For the...
Although the main use of lattice QCD computation is to provide non-perturbative calculation of low-energy physical quantities, it can also be used to calculate short-distance quantities. By matching thus calculated short-distance current correlators to corresponding perturbative calculations one can obtain the parameters appearing in the perturbation theory, such as the strong coupling...
Hadrons carrying heavy quarks, i.e. charm or bottom, are important probes of the hot and dense medium created in relativistic heavy-ion collisions. Heavy quark-antiquark pairs are mainly produced in initial hard scattering processes of partons. While some of the produced pairs form bound quarkonia, the vast majority hadronize into open heavy flavor particles. RHIC experiments carry out a...
Electromagnetic E1 (and M1) multipole transitions have been studied since the early days of hadron spectroscopy because they allow to access heavy quarkonium states which are below open-flavour threshold. Moreover, they are interesting by themselves because they are an important tool to check particular regions of the hadrons' wave function and thus to determine their internal structure and...
Belle, a general-purpose detector operated at the KEKB electron-positron
B-factory at KEK, Japan, collected the world largest integrated luminosity
at the peak of the $\Upsilon(4S)$ meson as well as in a scan of the
center-of-mass energy range from 10.63 to 11.05 GeV.
We describe recent results on various bottomonium states studied -
mass and width measurements of the $\Upsilon(5S)$ and...
Numerical recovering of the spectrum and wave function of a two-body fermionic relativistic potential system.
Estimation in this framework of the widths and branching ratios of some heavy mesons radiative decays.
We use non-linear field transformations for non-relativistic fields to implement Poincare invariance in low energy effective theories for QCD. In these transformations we include all terms allowed by the explicit symmetries of the effective theory, but exploit the freedom to remove some of them through field redefinitions. By requiring the invariance of the Lagrangian under these...
We derive an analytical expression for the chromopolarizability of bottomonium states using the framework of potential nonrelativistic QCD. Next, using the QCD trace anomaly we obtain the two-pion production amplitude for the chromopolarizability operator and match the result to a chiral effective field theory for bottomonium states and pions as degrees of freedom. In this chiral effective...
The LHCb experiment is designed to study the decays and properties of heavy flavoured hadrons produced in the forward region from pp collisions at the CERN Large Hadron Collider. It has recorded the world’s largest data sample of beauty and charm hadrons, enabling precise studies into the production and decay of such particles. $\eta_c$ production has been studied in B decays and in prompt...
We analyze the first measurement of $\eta_c$
production, performed by the LHCb Collaboration, in
the nonrelativistic-QCD (NRQCD) factorization framework
at next-to-leading order (NLO) in the
strong-coupling constant $\alpha_s$ and the relative velocity v
of the bound quarks including the feeddown
from $h_c$ mesons. Converting the long-distance matrix elements (LDM
Es) extracted by...
We compute leading-power fragmentation corrections to $J/\psi$
photoproduction at DESY HERA, making use of the nonrelativistic QCD
factorization approach. Our calculations include parton production cross
sections through order $\alpha_s^3$, fragmentation functions though
order $\alpha_s^2$, and leading logarithms of the transverse momentum
divided by the charm-quark mass to all orders in...
We study higher order relativistic corrections to the electromagnetic production cross-section of a heavy quarkonium and a hard photon in the factorization framework of non-relativistic QCD (NRQCD). We obtain new matching coefficients and discuss the importance of contributions from color octet operators, that were not considered in the previous studies of this process.
References:
[1] J/Psi -pair production at large momenta: Indications for double parton scatterings and large alpha_s^5 contributions. By J.P. Lansberg, H.S. Shao. arXiv:1410.8822 [hep-ph]. Phys.Lett. B751 (2015) 479.
[2] Production of J/psi+eta(c) vs. J/psi+J/psi at the LHC: Impact of Real alpha_s^5 corrections. By J.P. Lansberg, H.-S. Shao. [arXiv:1308.0474 [hep-ph]]. Phys.Rev.Lett....
In this work, we pint out that there exists an approximate degeneracy among heavy-light systems with the same $L$.
This is supported by an experimental fact which can be seen from the observed data. This approximate symmetry explains why the GI model obtains results similar to those of the heavy-light systems which are fitted well with experimental data. This is because the GI model has this...
We determine the $1/m$ and $1/m^2$ spin-independent heavy quarkonium potentials in the unequal mass case with $\mathcal O (\alpha^3)$ and $\mathcal O (\alpha^2)$ accuracy, respectively. Furthermore, we discuss in detail different methods to obtain the potential and we provide the explicit field redefinition that relates them, thus clarifying the relation between different previous partial...
Our formalism is based on the Covariant Spectator Theory (CST), a framework based on field theory originally developed to study systems of few nucleons. The distinctive feature of this approach is that it approximates the full Bethe-Salpeter-equation by taking into account, effectively, the contributions of both ladder and crossed ladder diagrams in the kernel.
Another notable feature of...
This talk will be based on the e-print "X(3872) production and absorption in a hot hadron gas", arXiv:1604.07716.
Since the discovery of the $X(3872)$ in 2003 [1] it became evident that the naive
quark model would not be enough to describe all the baryon spectrum. This state
has properties that can not be explained in such a quark model, as its decay into
$J/\Psi \pi \pi$ through a $\rho$ meson, which is an isospin violating decay. However
this property can be easily explained in a picture in which...
Using large data samples of di-muon events, CMS has performed detailed measurements and searches for new states in the field of exotic quarkonia. We report on measurements of the charmonium X(3872), and search for its counterpart in the bottomonium sector. The investigation of the B+ to J/ψ φ K+ decay reveals two structures in the J/ψ φ mass spectrum. For the one closest to the kinematical...
The heavy-quark spin symmetry (HQSS) partners of the X(3872) molecule are investigated based on a chiral effective field theory (EFT) approach involving contact and one-pion exchange interactions. The integral equations of the Lippmann-Schwinger type are solved for a coupled-channel problem involving the $D\bar D, D\bar{D}^*$, and $D^*\bar{D}^*$ interactions to yield the scattering...
The hidden charm pentaquark state $P_c(4450)$, observed recently by the LHCb collaboration in the $\Lambda_b \rightarrow J/\psi K^- p$ decay, may be of molecular nature, as advocated by some unitary approaches that also predict pentaquark partners in the strangeness S=-1 sector. In this work we argue that a hidden-charm strange pentaquark could also be seen in the decay of the $\Lambda_b$,...
Exotic Mesons Production, All charm tetra quark, Double Parton Scattering, Color Evaporation Model.
In the last decade many states in the spectrum of charmonium and bottomonium lying above the open-flavour threshold have been observed experimentally. Most of these states reside in the vicinity of strong thresholds and cannot be described by simple quark models. Description and understanding of such exotic states is a challenge for phenomenology of strong interactions which requires building...
Hadron spectroscopy is one of the most important physics goals of BESIII. BESIII brings great opportunities to study the XYZ states of charmonium by directly producing the Y states up to 4.6 GeV. We focus on the investigation of XYZ states and the discovery of new charged charmonium-like structures. Two isospin triplets Z(3900) and Z(4020) have been discovered, decaying into J/psi pi and hc...
In the last decade new, unexpected, quarkonium states close and above open flavor thresholds have been discovered. Some of these states are candidates for quarkonium hybrids, i.e states containg a gluonic excitation. Quarkonium hybrids are characterized by a set of well separated scales, in particular, the heavy quark and gluon dynamics have very different dynamical time scales, that be...
In the framework of pNRQCD, we calculate the partial decay width of heavy hybrid states to heavy quarkonia, and the mixing potential between them. We discuss their phenomenological relevance concerning the identification of some XYZ states with heavy hybrids.
We want to discuss the Pc(4450) pentaquark-like structure observed by the LHCb Collaboration in the J/psi proton final states. We point out that it is located exactly at the chi_{c1}-proton threshold, and coincides with the leading Landau singularity of the triangle loop Lambda(1890)-chi_{c1}-proton. We also discuss the possibility of distinguishing a genuine resonance from the kinematical singularity.
Pion-exchange offers a natural explanation for Pc(4450)+ as a meson-baryon molecule, and implies a number of partner states. I discuss the properties of these partners and suggest experimental channels for their discovery. The molecular interpretation also implies that Pc(4450)+ is a mixture of isospins 1/2 and 3/2, which has characteristic signatures in production and decay. Several...
X(4260) and X(4360) mesons
The number of multiquark states and the amount of details on their properties has been growing over the years. It is very recent the discovery of two pentaquarks and the confirmation of four tetraquarks, two of which had not been observed before. We present some considerations attempting a coherent description of the so called X and Z resonances. The prominent problems plaguing theoretical...
After discussing the OZI suppression of one light meson exchange in the interaction of with isospin I = 1 , we study the contribution of the two-pion exchange to the interaction and the exchange of heavy vectors, J/ψ for diagonal transitions and D* for transitions of to J/ψ ρ. We find these latter mechanisms to be weak, but enough to barely bind the system in J = 2 with a mass around 4000 MeV,...
In this talk we report on two recent works about the $Z_c(3900)$ resonance. A coupled channel T-matrix is used in the description of the $D^*\bar{D}$ and $J/\psi\pi$ spectra in which the $Z_c(3900)$ peak has been seen. The data can be well reproduced in two different scenarios, in which the $Z_c(3900)$ is a resonance or a virtual state. We also put this coupled channel $T$-matrix in a finite...
We present a new technique to resum analytically large threshold logarithms in heavy quark decay which simplifies multi-scale problems and apply it to the B -> X_s gamma decay
$\eta_c$ production at the LHC and indications on the understanding of $J/\psi$
In this talk, we will review a number of recent ideas⋆ put forward in favour of a fixed-target programme at the LHC - AFTER@LHC. By extracting the beam with a bent crystal or by using an internal gas target, the multi-TeV LHC beams allow one to perform the most energetic fixed-target experiments ever and to study with high precision pp, pd and pA collisions at $\sqrt{s_{NN}}$=115 GeV and Pbp...
Recent $\eta_c$ hadroproduction data provided an excellent opportunity for the determination of the color-octet matrix elements for the charmonia production. This talk will present the theoretical results for the $\eta_c$ hadroproduction versus the LHCb data and its impact on the $J/\psi$ production and polarization.
