In the present work, we investigate the dipion transitions between $Υ(5S)$ and $Υ_J(1D)$ with $J=1, 2, 3$. Our analysis indicates that the dominant sources of the anomalously large widths of $Υ(5S)\to Υ_J(1D) π^+ π^-$ should be $Z_b^{(\prime)}$, i.e., the dipion transitions occur via the cascade decays $Υ(5S)\to Z_b^{(\prime)\pm} π^\mp \to Υ_J(1D) π^+ π^-$. With the assumption that all the short ranged dynamics could be absorbed in a single cutoff with a model parameter $α$, the present estimations indicate that in a reasonable parameter range the measured branching ratios of $Υ(5S) \to Υ_J(1D) π^+ π^-$ can be reproduced in magnitude, which further proves that the decays via $Z_b^{(\prime)}$ dominate the dipion transitions of $Υ(5S)$ to $Υ_J(1D)$. Moreover, we also predict the ratios of the branching fractions of $Z_b^{(\prime)} \to Υ_J(1D) π$, which in our calculations are largely independent of the parameter $α$ and could be tested by further experiments in Belle II.
This paper is devoted to the leading twist exclusive bottomonia decays with double charmonium in the final state. Using models of the twist-2 charmonia distribution amplitudes the widths of these decays are calculated within light cone formalism. In addition, the processes under consideration are studied within nonrelativistic QCD. In our analysis we have found that the production of some of the $P$-wave charmonia mesons with $L_z \neq 0$ is allowed already at the leading twist approximation. This means that the selection rules which predict the suppression of such decays are violated. The mec…
In the hindered magnetic dipole transitions of heavy quarkonia, the coupled-channel effects originating from the coupling of quarkonia to a pair of heavy and anti-heavy mesons can play a dominant role. Here, we study the hindered magnetic dipole transitions between two $P$-wave bottomonia, $χ_b(n P)$ and $h_b(n^\prime P)$, with $n\neq n^\prime$. In these processes the coupled-channel effects are expected to lead to partial widths much larger than the quark model predictions. We estimate these partial widths which, however, are very sensitive to unknown coupling constants related to the vertice…
In this work, we present the calculation of the production cross sections of bottomonia states using Non-Relativistic Quantum Chromodynamics (NRQCD) formalism. The direct production cross-section of a resonance can be factorised in terms of short distance Quantum Chromodynamics (QCD) cross sections and long distance matrix elements (LDMEs) under NRQCD. We use a large set of measured $Υ$(nS) production data at Tevatron and LHC energies in both central and forward rapidity regions to extract the LDMEs with better precision. The feed down contributions from the higher states including the $χ_{b}$…
The $Υ(3S)$ production and polarization at high energies is studied in the framework of $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The transverse momentum dependent (TMD, or unintegrated) gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini (CCFM) evolution equation as well as from the Kimber-Martin-Ryskin (KMR) prescription. Treating the non-perturbative color octet transitions in terms of the multipole radiation th…
The $Υ(2S)$ production and polarization at high energies is studied in the framework of $k_T$-factorization approach. Our consideration is based on the non-relativistic QCD formalism for bound states formation and off-shell production amplitudes for hard partonic subprocesses. The direct production mechanism, feed-down contributions from radiative $χ_b(3P)$ and $χ_b(2P)$ decays and contributions from $Υ(3S)$ decays are taken into account. The transverse momentum dependent gluon densities in a proton were derived from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation as well as from th…
The production of ground-state and excited bottomonia in ultrarelativistic heavy-ion collisions is investigated within a kinetic-rate equation approach including regeneration. We augment our previous calculations by an improved treatment of medium effects, with temperature-dependent binding energies and pertinent reaction rates, $B$-meson resonance states in the equilibrium limit near the hadronization temperature, and a lattice-QCD based equation of state for the bulk medium. In addition to the centrality dependence of the bottomonium yields we compute their transverse-momentum ($p_T$) spectr…
Within the color singlet model, we calculate the exclusive production of double charmonia, double bottomonia, and double $B_c$ mesons at future super $Z$ factory. The two heavy quarkonia or $B_c$'s are either two S-wave Fock states ($^1S_0, ~^3S_1$), or one S-wave and one P-wave states ($^1P_1,~^3P_J~(J=0,1,2)$). The top three $Z^0$ propagated channels in cross sections for double charmonia are $J/ψ+h_c,η_c+χ_{c2}$, and $η_c+χ_{c0}$. For double bottomonia, they are $η_b+Υ, Υ+χ_{b2}$, and $Υ+Υ$. For double $B_c$ mesons, they are $B_c^{*+}+B_c^{*-}$,$B_c^{*+}+χ_{bc2}^-$, and $η_{bc}^++B_c^{*-}$.…
We derive the three loop soft function for inclusive Higgs production in gluon fusion, and use it to perform the resummation of the Higgs cross section at N$^3$LL$^\prime$ in SCET. We improve the accuracy of the resummation by including contributions of collinear origin. We include finite top, bottom and charm mass effect where available. These results are available through the public code ResHiggs.
In the present work, we investigate the production mechanism of the $Z_b(10610)$ and $Z_b(10650)$ states from the $Υ(5S,6S)$ decays. Two types of bottom-meson loops are discussed. We show that the loop contributions with all intermediate states being the $S$-wave ground state bottom mesons are negligible, while the loops with one bottom meson being the broad $B_0^\ast$ or $B_1^\prime$ resonance could provide the dominant contributions to the $Υ(5S) \to Z_b^{(\prime)} π$. It is found that such a mechanism is not suppressed by the large width of the $B_0/B_1'$ resonance. In addition, we also est…
A gauged U$(1)$ extension of the Standard Model (SM) is a simple and anomaly free framework where three generations of Majorana type right-handed neutrinos (RHNs) are introduced to generate light neutrino mass and flavor mixings through the seesaw mechanism. We investigate such models at different hadron and lepton colliders via $Z^\prime$ induced Majorana type RHNs pair production. We derive bounds on U$(1)$ gauge coupling $(g^\prime)$ comparing the model cross sections with experimentally observed data for different $Z^\prime$ mass $(M_{Z^\prime})$ and RHNs mass $(M_N)$. Using these limits w…
We investigate the possibility to detect the scalar Higgs boson decay $H\to b\bar b$ in the associated $Z$ and $b\bar b$ production at the LHC using the $k_T$-factorization QCD approach. Our consideration is based on the off-shell (i.e. depending on the transverse momenta of initial quarks and gluons) production amplitudes of $q^* \bar q^* \to Z H \to Z q^\prime \bar q^\prime$, $q^* \bar q^* \to Z q^\prime \bar q^\prime$ and $g^* g^* \to Z q^\prime \bar q^\prime$ partonic subprocesses supplemented with the Catani-Ciafoloni-Fiorani-Marchesini (CCFM) dynamics of parton densities in a proton. We …
In this work we study the interactions of the $Z$ and $Z^{\prime}$ generated by kinetic mixing in a class of theories for physics beyond the standard model motivated by the dark matter problem, containing a spontaneously broken extra $U(1)_{d}$ gauge factor group in a hidden scenario and a Higgs sector respecting custodial symmetry. It is shown that custodial symmetry allows us to write the $Z$ and $Z^{\prime}$ couplings to standard model fermions in terms of the measured values of $α$, $G_{F}$, $M_{Z}$ and $M_{Z^{\prime}}$. Working at the loop level, we calculate the ratio $ρ_{0}=M^{2}_{W}/\h…
Recent simulation studies indicate that right-handed neutrinos may be discovered at future high luminosity LHC runs as long as a new neutral gauge boson, $Z^{\prime}$, have been discovered first. In this case, when $Z^{\prime}$ is resonantly produced at the LHC it, subsequently, decays into pair of right-handed neutrinos with mass up to TeV scale. Then the decay of these neutrinos leave as signature tri-lepton final states and/or same-sign di-muon and a boost di-boson. The prospect of discovering right-handed neutrinos through this mechanism has been developed within abelian gauge extension of…
The flavorful $Z^\prime$ model with its couplings restricted to the left-handed second generation leptons and third generation quarks can potentially resolve the observed anomalies in $R_K$ and $R_{K^*}$. After examining the current limits on this model from various low-energy processes, we probe this scenario at 14 TeV high-luminosity run of the LHC using two complementary channels: one governed by the coupling of $Z'$ to $b$-quarks and the other to muons. We also discuss the implications of the latest LHC high mass resonance searches in the dimuon channel on the model parameter space of our …
We investigate the pair production of right-handed neutrinos from the decay of an additional neutral $Z^{\prime}$ boson in the gauged $B-L$ model. Taking into account current constraints on the $Z^{\prime}$ mass and the associated gauge coupling $g_{1}^{\prime}$, we analyse the sensitivity of proposed experiments at the lifetime frontier, FASER 2, CODEX-b, MATHUSLA as well as a hypothetical version of the MAPP detector to a long lived heavy neutrino $N$ originating in the decays of the $Z^{\prime}$. We further complement this study with determining the reach of LHCb and a CMS-type detector for…
Non-resonant production of Higgs-pair via heavy intermediate states may be a distinctive signature for extended discrete symmetries when accompaied by large missing transvers energy. We discuss $T$-parity as an example of such symmetry within the Littlest Higgs Model, where a new heavy gauge boson $Z'$, the $T$-odd partner of SM $Z$-boson, predominately decays into to a Higgs boson and a dark matter candidate $χ$. In essence, $T$-parity stablises simultaneously both the Higgs mass and the dark matter. Production via $pp\rightarrow Z' Z'\rightarrow 2h 2χ$ may therefore yield important clues abo…
The heavy charged gauge bosons were proposed in the theories beyond standard model. We explore the discovery potential for $W'\to t\bar{b}$ with top quark semi-leptonic decay at the LHC. We concentrate on the new physics signal search with the deviation from the standard model prediction if the resonance peak of $W'$ can not be observed directly. The events of signal with two jets plus one charged lepton and missing energy are simulated together with the dominant standard model backgrounds. In this paper, it is found that suitable cuts on the kinematic observables can effectively suppress the …
Search for the production of dark Higgs in the framework of Mono-Z$^{\prime}$ portal at the FCC-ee simulated electron-positron collisions at $\sqrt{s} = 240$ GeV
Centre for Theoretical Physics, The British University in Egypt（埃及英国大学理论物理中心）；Istituto Nazionale di Fisica Nucleare, Sezione di Bari（意大利国家核物理研究所巴里分部）；Politecnico di Bari（巴里理工大学）
Spin identification of the mono-Z$^{\prime}$ resonance in muon-pair production at the ILC with simulated electron-positron collisions at $\sqrt{s}$ = 500 GeV
Centre for Theoretical Physics, The British University in Egypt（埃及英国大学理论物理中心）
We use the results of CMS and ATLAS searches for resonances that decay to $τν$ or $tb$ and $τ^+τ^-$ or $t\bar t$ final states to constrain the parameters of non-universal $W^\prime$ and $Z^\prime$ gauge bosons that couple preferentially to the third generation. For the former we consider production from $c\bar{b}$ annihilation and find very weak constraints on the strength of the interaction and only for the mass range between 800 and 1100 GeV from the $pp \to τ_h p_T^{\rm miss}$ channel. The constraints on the latter are much stronger and arise from both $t\bar t$ and $τ^+τ^-$ production. Tre…
Within the framework of nonrelativistic QCD, we make a detailed discussion on the doubly heavy baryon production through the $e^+ e^-$ annihilation channel, $e^{+}e^{-}\rightarrowγ/Z^0 \rightarrow Ξ_{QQ^{\prime}} +\bar{Q} +\bar{Q^{\prime}}$, at a high luminosity $e^{+}e^{-}$ collider. Here $Q^{(\prime)}$ stands for the heavy $b$ or $c$ quark. In addition to the channel through the usually considered diquark state $(QQ^{\prime})[^3S_1]_{\bf\bar{3}}$, contributions from the channels through other same important diquark states such as $(QQ^{\prime})[^1S_0]_{\bf 6}$ have also been discussed. Uncer…
There may exist seven $\bar D^{(*)} Σ_c^{(*)}$ hadronic molecular states. We construct their corresponding interpolating currents, and calculate their masses and decay constants using QCD sum rules. Based on these results, we calculate their relative production rates in $Λ_b^0$ decays through the current algebra, i.e., $\mathcal{B}(Λ_b^0 \to P_c K^-):\mathcal{B}(Λ_b^0 \to P_c^\prime K^-)$ with $P_c$ and $P_c^\prime$ two different states. We also study their decay properties through the Fierz rearrangement, and further calculate these ratios in the $J/ψp$ mass spectrum, i.e., $\mathcal{B}(Λ_b^0…
We present compact analytic results for the one-loop amplitude for the process $0 \rightarrow q \bar{q} \ell \bar\ell \ell^\prime \bar{\ell}^\prime g$, relevant for both the production of a pair of $Z$ and $W$-bosons in association with a jet. We focus on the gauge-invariant contribution mediated by a loop of quarks. We explicitly include all effects of the loop-quark mass $m$, appropriate for the production of a pair of $Z$-bosons. In the limit $m \to 0$, our results are also applicable to the production of $W$-boson pairs, mediated by a loop of massless quarks. Implemented in a numerical cod…
