Distribution Amplitudes of Heavy Hadrons: Theory and Applications

The physics of heavy quarks becomes a very reach area of study thanks to an excellent operation of hadron colliders and $B$-factories and exciting results from them. Experimental data obtained allows to get some information about the heavy hadron dynamics. In this case, the models for the heavy hadron wave-functions are required to do theoretical predictions for concrete processes under study. In many cases, the light-cone description is enough to obtain theoretical estimates for heavy hadron decays. A discussion of the wave-functions of the $B$-meson and heavy bottom baryons in terms of the light-cone distribution amplitudes is given in this paper. Simple models for the distribution amplitudes are presented and their scale dependence is discussed. Moments of the distribution amplitudes which are entering the branching fractions of radiative, leptonic and semileptonic $B$-mesons decays are also briefly discussed.Comment: 17 pages, 4 figures, lecture at the Helmholtz International Summer School and Dubna International Advanced School on Theoretical Physics "Quantum Field Theory at the Limits: from Strong Fields to Heavy Quarks", JINR, Dubna, Russia, July 18--30, 201

Branching Fraction of the Decay B+→π+τ+τ−B^+ \to \pi^+ \tau^+ \tau^- and Lepton Flavor Universality Test via the Ratio Rπ(τ/μ)R_\pi (\tau/\mu)

Among (semi)leptonic rare $B$-decays induced by the $b \to d$ flavor changing neutral current, the decay $B^+ \to \pi^+ \mu^+ \mu^-$ is the only one observed so far experimentally. Related decays involving the $e^+e^-$ and $\tau^+ \tau^-$ pairs are the targets for the ongoing experiments at the LHC, in particular LHCb, and Belle II. The muonic and electronic semileptonic decays have almost identical branching fractions in the Standard Model (SM). However, the tauonic decay $B^+ \to \pi^+ \tau^+ \tau^-$ differs from the other two due to the higher reaction threshold which lies slightly below the $\psi (2S)$-resonance. We present calculations of the ditauon ($\tau^+ \tau^-$) invariant-mass distribution and the branching fraction ${\rm Br} (B^+ \to \pi^+ \tau^+ \tau^-)$ in the SM based on the Effective Electroweak Hamiltonian approach, taking into account also the so-called long-distance contributions. The largest theoretical uncertainty in the short-distance part of the decay rates is due to the $B \to \pi$ form factors, which we quantify using three popular parametrizations. The long-distance contribution can be minimized by a cut on the ditauon mass $m_{\tau^+ \tau^-} > M_{\psi (2S)}$. Once available, the branching fractions in the tauonic and muonic (and electronic) modes provide stringent test of the lepton flavor universality in the $b \to d$ transitions. We illustrate this by calculating the ratio $R_\pi (\tau/\mu) \equiv {\rm Br} (B^+ \to \pi^+ \tau^+ \tau^-)/{\rm Br} (B^+ \to \pi^+ \mu^+ \mu^-)$ in the SM for the total and binned ratios of the branching fractions.Comment: 11 pages, 5 figures, 11 table

Prospects of discovering stable double-heavy tetraquarks at a Tera-ZZ factory

Motivated by a number of theoretical considerations, predicting the deeply bound double-heavy tetraquarks $T^{\{bb\}}_{[\bar u \bar d]}$, $T^{\{bb\}}_{[\bar u \bar s]}$ and $T^{\{bb\}}_{[\bar d \bar s]}$, we explore the potential of their discovery at Tera-$Z$ factories. Using the process $Z \to b \bar b b \bar b$, we calculate, employing the Monte Carlo generators MadGraph5$\_$aMC@NLO and Pythia6, the phase space configuration in which the~$b b$ pair is likely to fragment as a diquark. In a jet-cone, defined by an invariant mass interval $m_{bb} < M_{T^{\{bb\}}_{[\bar q \bar q']}} + \Delta M$, the sought-after tetraquarks $T^{\{bb\}}_{[\bar q \bar q^\prime]}$ as well as the double-bottom baryons,~$\Xi_{bb}^{0,-}$, and $\Omega_{bb}^-$, can be produced. Using the heavy quark--diquark symmetry, we estimate $\mathcal{B} (Z \to T^{\{bb\}}_{[\bar u \bar d]} + \; \bar b \bar b) = (1.4^{+1.1}_{-0.5}) \times 10^{-6}$, and about a half of this for the $T^{\{bb\}}_{[\bar{u}\bar{s}]}$ and $T^{\{bb\}}_{[\bar d \bar s]}$. We also present an estimate of their lifetimes using the heavy quark expansion, yielding $\tau(T^{\{bb\}}_{[\bar q \bar q^\prime]}) \simeq 800$~fs. Measuring the tetraquark masses would require decays, such as $T^{\{bb\} -}_{[\bar u \bar d]} \to B^- D^- \pi^+$, $T^{\{bb\} -}_{[\bar u \bar d]} \to J/\psi \overline K^0 B^-$, $T^{\{bb\} -}_{[\bar u \bar d]} \to J/\psi K^- \overline B^0$, $T^{\{bb\} -}_{[\bar u \bar s]} \to \Xi_{bc}^0 \Sigma^-$, and $T^{\{bb\} 0}_{[\bar d \bar s]} \to \Xi_{bc}^0 \bar\Sigma^0$, with subsequent decay chains in exclusive non-leptonic final states. We estimate a couple of the decay widths and find that the product branching ratios do not exceed~$10^{-5}$. Hence, a good fraction of these modes will be required for a discovery of $T^{\{bb\}}_{[\bar q \bar q']}$ at a Tera-$Z$ factory.Comment: 11 pages, 11 figures; v2: version to appear in PL

A New Look at the YY Tetraquarks and Ωc\Omega_c Baryons in the Diquark Model

We analyze the hidden charm $P$-wave tetraquarks in the diquark model, using an effective Hamiltonian incorporating the dominant spin-spin, spin-orbit and tensor interactions. We compare with other $P$-wave system such as $P$-wave charmonia and the newly discovered $\Omega_c$ baryons, analysed recently in this framework. Given the uncertain experimental situation on the $Y$ states, we allow for different spectra and discuss the related parameters in the diquark model. In addition to the presently observed ones, we expect many more states in the supermultiplet of $L=1$ diquarkonia, whose $J^{PC}$ quantum numbers and masses are worked out, using the parameters from the currently preferred $Y$-states pattern. The existence of these new resonances would be a decisive footprint of the underlying diquark dynamics.Comment: Revised and extended to accommodate referee comments. Added a table and references. Accepted for publication in the EPJ

Implication of the B→(ρ,ω)γB \to (\rho, \omega) \gamma Branching Ratios for the CKM Phenomenology

We study the implication of the recent measurement by the BELLE collaboration of the averaged branching fraction $\bar B_{exp} [B \to (\rho, \omega) \gamma] = (1.8^{+0.6}_{-0.5} \pm 0.1) \times 10^{-6}$ for the CKM phenomenology. Combined with the averaged branching fraction $\bar B_{exp} (B \to K^* \gamma) = (4.06 \pm 0.26) \times 10^{-5}$ measured earlier, this yields $\bar R_{exp} [(\rho, \omega) \gamma/K^* \gamma] = (4.2 \pm 1.3)$ for the ratio of the two branching fractions. Updating earlier theoretical analysis of these decays based on the QCD factorization framework, and constraining the CKM-Wolfenstein parameters from the unitarity fits, our results yield $\bar B_{th} [B \to (\rho, \omega) \gamma] = (1.38 \pm 0.42) \times 10^{-6}$ and $\bar R_{th} [(\rho, \omega) \gamma/K^* \gamma] = (3.3 \pm 1.0)$, in agreement with the BELLE data. Leaving instead the CKM-Wolfenstein parameters free, our analysis gives (at 68% C.L.) $0.16\leq |V_{td}/V_{ts}| \leq 0.29$, which is in agreement with but less precise than the indirect CKM-unitarity fit of the same, $0.18 \leq |V_{td}/V_{ts}| \leq 0.22$. The isospin-violating ratio in the $B \to \rho \gamma$ decays and the SU(3)-violating ratio in the $B_d^0 \to (\rho^0, \omega) \gamma$ decays are presented together with estimates of the direct and mixing-induced CP-asymmetries in the $B \to (\rho,\omega) \gamma$ decays within the SM. Their measurements will overconstrain the angle $\alpha$ of the CKM-unitarity triangle.Comment: 21 pages, 3 figures. Included a discussion of model-dependent estimates of the long-distance/rescattering contributions in radiative B-decays; added a reference. Version accepted for publication in Physics Letters

The η′g∗g∗\eta^\prime g^* g^* vertex with arbitrary gluon virtualities in the perturbative QCD hard scattering approach

We study the $\eta^\prime g^* g^*$ vertex for arbitrary gluon virtualities in the time-like and space-like regions, using the perturbative QCD hard scattering approach and an input wave-function of the $\eta^\prime$-meson consistent with the measured $\eta^\prime \gamma^* \gamma$ transition form factor. The contribution of the gluonic content of the $\eta^\prime$-meson is taken into account, enhancing the form factor over the entire virtuality considered. However, data on the electromagnetic transition form factor of the $\eta^\prime$-meson is not sufficient to quantify the gluonic enhancement. We also study the effect of the transverse momenta of the partons in the $\eta^\prime$-meson on the $\eta^\prime g^* g^*$ vertex, using the modified hard scattering approach based on Sudakov formalism. Analytic expressions for the $\eta^\prime g^* g^*$ vertex are presented in limiting kinematic regions and parametrizations are given satisfying the QCD anomaly, for real gluons, and perturbative QCD behavior for large gluon virtualities, in both the time-like and space-like regions. Our results have implications for the inclusive decay $B \to \eta^\prime X$ and exclusive decays, such as $B \to \eta^\prime (K,K^*)$, and in hadronic production processes $N + N (\bar N) \to \eta^\prime X$.Comment: 23 pages, 19 figures (requires revtex4, amssymb, epsf); several typos corrected, this version now identical to the one accepted for publication in Phys. Rev.

Lacustrine Records of Holocene Climate and Environmental Change from the Lofoten Islands, Norway

Lakes sediments from the Lofoten Islands, Norway, can be used to generate well resolved records of past climate and environmental change. This dissertation presents three lacustrine paleoenvironmental reconstructions that show evidence for Holocene climate changes associated with North Atlantic climate dynamics and relative sea-level variations driven by glacio-isostatic adjustment. This study also uses distal tephra deposits (cryptotephra) from Icelandic volcanic eruptions to improve the chronologies of these reconstructions and explores new approaches to crypto-tephrochronology. Past and present conditions at Vikjordvatnet, Fiskebølvatnet, and Heimerdalsvatnet were studied during four field seasons conducted from 2007-2010. Initially, each lake was characterized by measuring water column chemistry, logging annual temperature fluctuations, and conducting bathymetric and seismic surveys. Sediment cores were then collected and analyzed using multiple techniques, including: sediment density, magnetic susceptibility, loss-on-ignition, total carbon and nitrogen, δ13C and δ15N of organic matter, and elemental compositions acquired by scanning X-ray fluorescence. Chronologies were established using radiocarbon dating and tephrochronology. A 13.8 cal ka BP record from Vikjordvatnet provides evidence for glacial activity during the Younger Dryas cold interval and exhibits trends in Ti, Fe, and organic content during the Holocene that correlate with regional millennial-scale climate trends and provide evidence for more rapid events. A 9.7 cal ka BP record from Fiskebølvatnet shows a strong signal of sediment inwashing likely driven by local geomorphic conditions, although there is evidence that increased inwashing at the onset of the Neoglacial could have been associated with increased precipitation. Heimerdalsvatnet provides a record of relative sea-level change. A 7.8 cal ka BP sedimentary record reflects changes in salinity and water column conditions as the lake was isolated and defines sea-level regression following the Tapes transgression. Cryptotephra horizons were identified in sediments of Heimerdalsvatnet, Vikjordvatnet, and Sverigedalsvatn. They were also found in a Viking-age boathouse excavated along the shore of Inner Borgpollen. These include the GA4-85, BIP-24a, SILK-N2, Askja, 860 Layer B, Hekla 1158, Hekla 1104, Vedde Ash, and Saksunarvatn tephra. This research project also explored the use of scanning XRF to locate cryptotephra in lacustrine sediments and presents experimental results of XRF scans of tephra-spiked synthetic sediment cores

Interpretation of the Narrow J/ψpJ/\psi p Peaks in Λb→J/ψpK−\Lambda_b \to J/\psi p K^- Decay in the Compact Diquark Model

Recently, the LHCb Collaboration have updated their analysis of the resonant $J/\psi p$ mass spectrum in the decay $\Lambda_b^0 \to J/\psi p K^-$. In the combined Run~1 and Run~2 LHCb data, three peaks are observed, with the former $P_c(4450)^+$ state split into two narrow states, $P_c(4440)^+$ and $P_c(4457)^+$, having the masses $M=(4440.3\pm 1.3^{+4.1}_{-4.7})$ MeV and $M=(4457.3\pm 0.6^{+4.1}_{-1.7})$ MeV, and decay widths $\Gamma=(20.6\pm 4.9^{+8.7}_{-10.1})$ MeV and $\Gamma=(6.4\pm 2.0^{+5.7}_{-1.9})$ MeV, respectively. In addition, a third narrow peak, $P_c(4312)^+$, having the mass $M=(4311.9\pm 0.7^{+6.8}_{-0.6})$ MeV and decay width $\Gamma=(9.8\pm 2.7^{+3.7}_{-4.5})$ MeV is also observed. The LHCb analysis is not sensitive to broad $J/\psi p$ contributions like the former $P_c(4380)^+$, implying that there could be more states present in the data. Also the spin-parity, $J^P$, assignments of the states are not yet determined. We interpret these resonances in the compact diquark model as hidden-charm diquark-diquark-antiquark baryons, having the following spin and angular momentum quantum numbers: $P_c(4312)^+ =\{\bar c [cu]_{s=1} [ud]_{s=0}; L_P=0, J^P=3/2^-\}$, the $S$-wave state, and the other two as $P$-wave states, with $P_c(4440)^+ =\{\bar c [cu]_{s=1} [ud]_{s=0}; L_P=1, J^P=3/2^+\}$ and $P_c(4457)^+ = \{\bar c [cu]_{s=1} [ud]_{s=0}; L_P=1, J^P=5/2^+ \}$. The subscripts denote the spins of the diquarks and $L_P=0,1$ is the orbital angular momentum quantum number of the pentaquark. These assignments are in accord with the heavy-quark-symmetry selection rules for $\Lambda_b$-baryon decays, in which the spin $S=0$ of the light diquark $[ud]_{s=0}$ is conserved. The masses of observed states can be accommodated in this framework and the two heaviest states have the positive parities as opposed to the molecular-like interpretations