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Published:
, doi: 10.1088/1674-1137/43/3/031001
Abstract:
Studies of $ e^+e^- \to D^+_s \overline{D}{}^{(*)0}K^- $ and the $ P $ -wave charmed-strange mesons are performed based on an $ e^+e^- $ collision data sample corresponding to an integrated luminosity of 567 pb−1 collected with the BESIII detector at $ \sqrt{s}= 4.600 $ GeV. The processes of $ e^+e^-\to D^+_s \overline{D}{}^{*0} K^- $ and $ D^+_s \overline{D}{}^{0} K^- $ are observed for the first time and are found to be dominated by the modes $ D_s^+ D_{s1}(2536)^- $ and $ D_s^+ D^*_{s2}(2573)^- $ , respectively. The Born cross sections are measured to be $ \sigma^{B}(e^+e^-\to D^+_s \overline{D}{}^{*0} K^-) = (10.1\pm2.3\pm0.8)$ pb and $ \sigma^{B}(e^+e^-\to D^+_s \overline{D}{}^{0} K^-) = (19.4\pm2.3\pm1.6)$ pb, and the products of Born cross section and the decay branching fraction are measured to be $ \sigma^{B}(e^+e^-\to D^+_s D_{s1}(2536)^- + c.c.)\cdot$ $ {\cal{B}}( D_{s1}(2536)^- \to \overline{D}{}^{*0} K^-) = (7.5 \pm 1.8 \pm 0.7)$ pb and $\sigma^{B}(e^+e^-\to D^+_s D^*_{s2}(2573)^- + c.c.)\cdot {\cal{B}}( D^*_{s2}(2573)^- \to \overline{D}{}^{0} K^-) =$ $ (19.7 \pm 2.9 \pm 2.0)$ pb. For the $ D_{s1}(2536)^- $ and $ D^*_{s2}(2573)^- $ mesons, the masses and widths are measured to be $ M( D_{s1}(2536)^- ) = (2537.7 \pm 0.5 \pm 3.1)\; {\rm{MeV}}/c^2 $ , $ \Gamma( D_{s1}(2536)^- ) = (1.7\pm 1.2 \pm 0.6) $ MeV, and $M( D^*_{s2}(2573)^- ) = $ $ (2570.7\pm 2.0 \pm 1.7)\; {\rm{MeV}}/c^2, $ $ \Gamma( D^*_{s2}(2573)^- ) = (17.2 \pm 3.6 \pm 1.1)$ MeV. The spin-parity of the $ D^*_{s2}(2573)^- $ meson is determined to be $ J^P=2^{+} $ . In addition, the processes $ e^+e^-\to D^+_s \overline{D}{}^{(*)0} K^- $ are searched for using the data samples taken at four (two) center-of-mass energies between 4.416 (4.527) and 4.575 GeV, and upper limits at the 90% confidence level on the cross sections are determined.
Studies of
Published:
, doi: 10.1088/1674-1137/43/3/034106
Abstract:
We present the masses of N baryons upto 3300 MeV. The radial and orbital excited states are determined using hypercentral constituent quark model with the first-order correction. The obtained masses are compared with the experimental results and other theoretical predictions. The Regge trajectories are also determined in (n, $M^2$ ) and (J, $M^2$ ) planes. Moreover, the magnetic moments with $J^{P}= \displaystyle\frac{1}{2}^{+}, \displaystyle\frac{1}{2}^{-}$ are calculated. We also calculates the $N\pi$ decay width of excited nucleons.
We present the masses of N baryons upto 3300 MeV. The radial and orbital excited states are determined using hypercentral constituent quark model with the first-order correction. The obtained masses are compared with the experimental results and other theoretical predictions. The Regge trajectories are also determined in (n,
Published:
, doi: 10.1088/1674-1137/43/2/024105
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The in-medium $ NN\rightarrow N\Delta $ cross sections and its differential cross sections in isospin asymmetric nuclear medium are investigated in the framework of the one-boson exchange model by including isovector mesons, i.e., $ \delta $ and $ \rho $ mesons. Our results show that the in-medium $ NN\rightarrow N\Delta $ cross sections are suppressed when the density increases, and the differential cross sections become isotropic with an increase in the density around the $ \Delta $ threshold energy. The isospin splitting on the medium correction factor, $ R=\sigma_{ NN\rightarrow N\Delta}^*/\sigma_{NN\rightarrow N\Delta}^{\rm{free}} $ is observed for different channels of $ NN\to N\Delta $ , especially around the threshold energy for all the effective Lagrangian parameters. By analyzing the selected effective Lagrangian parameters, our results show that the larger effective mass is, the weaker medium correction $ R $ is.
The in-medium
Published:
, doi: 10.1088/1674-1137/43/2/023106
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Using the covariant light-front approach with conventional vertex functions, we estimate the production rates of D -wave charmed/charmed-strange mesons via the $B_{(s)}$ semileptonic decays. As the calculated production rates are significant, it seems possible to experimentally search for D -wave charmed/charmed-strange mesons via semileptonic decays, which may provide an additional approach for exploring D -wave charmed/charmed-strange mesons.
Using the covariant light-front approach with conventional vertex functions, we estimate the production rates of D -wave charmed/charmed-strange mesons via the
Published:
, doi: 10.1088/1674-1137/43/2/023104
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Whether an additional light scalar exists is an interesting topic in particle physics beyond the Standard Model (SM), as we do not know as yet the nature of physics beyond the SM in the low mass region in view of the inconsistent results of the ATLAS and CMS collaborations in their search for light resonances around 95 GeV in the diphoton channel. We study a light scalar in the Minimal Dilaton Model (MDM). Under the theoretical and the latest experimental constraints, we sort the selected data samples into two scenarios according to the diphoton rate of the light scalar: the large-diphoton scenario (with $\sigma_{\gamma\gamma}/{\rm SM}\gtrsim0.2$ ) and the small-diphoton scenario (with $\sigma_{\gamma\gamma}/{\rm SM}\lesssim0.2$ ), which are favored by the CMS and ATLAS results, respectively. We compare the two scenarios, test the characteristics of the model parameters, the scalar couplings, production and decay, and consider how they could be further discerned at colliders. We draw the following conclusions for the two scenarios: (i) The large-diphoton scenario has in general a small Higgs-dilaton mixing angle ( $|\sin\theta_S|\lesssim0.2$ ) and a small dilaton vacuum expectation value (VEV) $f$ ( $0.5\lesssim\eta\equiv v/f\lesssim1$ ), and the small-diphoton scenario has large mixing ( $|\sin\theta_S|\gtrsim0.4$ ) or large VEV ( $\eta\equiv v/f\lesssim0.3$ ). (ii) The large-diphoton scenario in general predicts small $s\gamma\gamma$ coupling ( $|C_{s\gamma\gamma}/{\rm SM}|\lesssim0.3$ ) and large $sgg$ coupling ( $0.6\lesssim|C_{sgg}/{\rm SM}|\lesssim1.2$ ), while the small-diphoton scenario predicts small $sgg$ coupling ( $|C_{sgg}/{\rm SM}|\lesssim0.5$ ). (iii) The large-diphoton scenario can interpret the small diphoton excess seen by CMS at its central value, when $m_s\simeq95$ GeV, $\eta\simeq0.6$ and $|\sin\theta_S|\simeq0$ . (iv) The large-diphoton scenario in general predicts a negative correlation between the Higgs couplings $|C_{h\gamma\gamma}/{\rm SM}|$ and $|C_{hgg}/{\rm SM}|$ , while the small-diphoton scenario predicts that both couplings are smaller than 1, or $|C_{h\gamma\gamma}/{\rm SM}|\lesssim0.9 \lesssim|C_{hgg}/{\rm SM}|$ .
Whether an additional light scalar exists is an interesting topic in particle physics beyond the Standard Model (SM), as we do not know as yet the nature of physics beyond the SM in the low mass region in view of the inconsistent results of the ATLAS and CMS collaborations in their search for light resonances around 95 GeV in the diphoton channel. We study a light scalar in the Minimal Dilaton Model (MDM). Under the theoretical and the latest experimental constraints, we sort the selected data samples into two scenarios according to the diphoton rate of the light scalar: the large-diphoton scenario (with
Published:
, doi: 10.1088/1674-1137/43/2/023105
Abstract:
The thermodynamics of strongly interacting matter near the critical end point are investigated in a holographic QCD model, which can describe the QCD phase diagram in $ T-\mu $ plane qualitatively. Critical exponents along different axes ( $ \alpha,\beta,\gamma,\delta $ ) are extracted numerically. It is given that $ \alpha\approx 0$ , $\beta\approx 0.54 $ , $\gamma \approx 1.04$ , and $\delta \approx 2.97$ , which is similar to the three-dimensional Ising mean-field approximation and previous holographic QCD model calculations. We also discuss the possibilities to go beyond the mean field approximation by including the full back-reaction of the chiral dynamics in the holographic framework.
The thermodynamics of strongly interacting matter near the critical end point are investigated in a holographic QCD model, which can describe the QCD phase diagram in
Published:
, doi: 10.1088/1674-1137/43/2/024104
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Based on the neutron and proton degrees of freedom, low-lying energy levels, $ E2 $ , $ M1 $ , and $ E0 $ transition strengths of nucleus 124Te have been calculated by the neutron-proton interacting boson model. The calculated results are reasonably consistent with the experimental data. By comparing the key observables of the states at the critical point of $ {\rm U}_{\pi \nu}(5) $ - $ {\rm O}_{\pi \nu}(6) $ transition with the experimental data and calculated results, we show that the 124Te is a possible nucleus at the critical point of the second-order phase transition from vibration to unstable rotation, and such a critical point exhibits slight triaxial rotation. The 0 $_2^ + $ state of 124Te can be interpreted as the lowest state of the first-excited family of the intrinsic levels in the critical point symmetry.
Based on the neutron and proton degrees of freedom, low-lying energy levels,
Published:
, doi: 10.1088/1674-1137/43/2/025102
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We investigate the power spectra of the CMB temperature and matter density in the running vacuum model (RVM) with the time-dependent cosmological constant of $ \Lambda = 3 \nu H^2 + \Lambda_0 $ , where $ H $ is the Hubble parameter. In this model, dark energy decreases in time and decays to both matter and radiation. By using the Markov chain Monte Carlo method, we constrain the model parameter $ \nu $ as well as the cosmological observables. Explicitly, we obtain $ \nu \leqslant 1.54 \times 10^{-4} $ (68% confidence level) in the RVM with the best-fit $\chi^2_{\mathrm{RVM}} = 13968.8$ , which is slightly smaller than $\chi^2_{\Lambda \mathrm{CDM}} = 13969.8$ in the $\Lambda{\rm{CDM}}$ model of $ \nu=0 $ .
We investigate the power spectra of the CMB temperature and matter density in the running vacuum model (RVM) with the time-dependent cosmological constant of
Published:
, doi: 10.1088/1674-1137/43/2/024102
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With quark-antiquark annihilation and creation in the first Born approximation, we study the reactions: $K \bar {K} \to K \bar {K}^\ast$ , $K \bar{K} \to K^* \bar{K}$ , $\pi K \to \pi K^\ast$ , $\pi K \to \rho K$ , $\pi \pi \to K \bar{K}^\ast$ , $\pi \pi \to K^\ast \bar{K}$ , $\pi \pi \to K^\ast \bar{K}^\ast$ , $\pi \rho \to K \bar{K}$ , $\pi \rho \to K^\ast \bar{K}^\ast$ , $\rho \rho \to K^\ast \bar{K}^\ast$ , $K \bar{K}^\ast \to \rho \rho$ , and $K^* \bar{K} \to \rho \rho$ . Unpolarized cross sections for the reactions are obtained from transition amplitudes that are composed of mesonic quark-antiquark relative-motion wave functions and the transition potential for quark-antiquark annihilation and creation. Using a quark-antiquark potential that is equivalent to the transition potential, we prove that the total spin of the two final mesons may not be equal to the total spin of the two initial mesons. Based on flavor matrix elements, cross sections for some isospin channels of reactions can be obtained from other isospin channels of the reactions. Remarkable temperature dependence of the cross sections was observed.
With quark-antiquark annihilation and creation in the first Born approximation, we study the reactions:
Published:
, doi: 10.1088/1674-1137/43/2/023103
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BESIII data show a particular angular distribution for the decay of $ J/\psi $ and $ \psi(2S) $ mesons into $ \Lambda \overline \Lambda $ and $ \Sigma^0 {\overline \Sigma}{}^0 $ hyperons: the angular distribution of the decay $ {{\psi(2S)}} \to {\Sigma^0\overline{\Sigma}{}^0} $ exhibits an opposite trend with respect to the other three channels: $ J/\psi \to \Lambda \overline \Lambda $ , $ J/\psi \to \Sigma^0 {\overline \Sigma}{}^0 $ and $ \psi(2S) \to \Lambda \overline \Lambda $ . We define a model to explain the origin of this phenomenon.
BESIII data show a particular angular distribution for the decay of
Published:
, doi: 10.1088/1674-1137/43/2/023102
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We confront the perturbativity problem in the real scalar quintuplet minimal dark matter model. In the original model, the quintuplet quartic self-coupling inevitably hits a Landau pole at a scale ~1014 GeV, far below the Planck scale. In order to push up this Landau pole scale, we extend the model with a fermionic quintuplet and three fermionic singlets which couple to the scalar quintuplet via Yukawa interactions. Involving such Yukawa interactions at a scale ~1010 GeV can not only keep all couplings perturbative up to the Planck scale, but can also explain the smallness of neutrino masses via the type-I seesaw mechanism. Furthermore, we identify the parameter regions favored by the condition that perturbativity and vacuum stability are both maintained up to the Planck scale.
We confront the perturbativity problem in the real scalar quintuplet minimal dark matter model. In the original model, the quintuplet quartic self-coupling inevitably hits a Landau pole at a scale ~1014 GeV, far below the Planck scale. In order to push up this Landau pole scale, we extend the model with a fermionic quintuplet and three fermionic singlets which couple to the scalar quintuplet via Yukawa interactions. Involving such Yukawa interactions at a scale ~1010 GeV can not only keep all couplings perturbative up to the Planck scale, but can also explain the smallness of neutrino masses via the type-I seesaw mechanism. Furthermore, we identify the parameter regions favored by the condition that perturbativity and vacuum stability are both maintained up to the Planck scale.
Published:
, doi: 10.1088/1674-1137/43/2/025101
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We study a spherically symmetric spacetime made of an anisotropic fluid whose radial equation-of-state is given by $ p_1 = -\rho $ . This case allows analytic solutions and is a good example for studying the static configuration of a black hole plus matter. For a given equation-of-state parameter $ w_2 = p_2/\rho $ for angular directions, we find the exact solutions of the Einstein equation described by two parameters. We classify the solutions into six types based on the behavior of the metric function. Depending on the parameters, the solutions can have event and cosmological horizons. One of the solution types corresponds to a generalization of the Reissner-Nordström black hole, the thermodynamic properties for which are obtained in a simple form. The solutions are stable under radial perturbations.
We study a spherically symmetric spacetime made of an anisotropic fluid whose radial equation-of-state is given by
Published:
, doi: 10.1088/1674-1137/43/2/023001
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As a Higgs factory, the CEPC (Circular Electron-Positron Collider) project aims at precision measurements of the Higgs boson properties. A baseline detector concept, APODIS (A PFA Oriented Detector for the HIggS factory), has been proposed for the CEPC CDR (Conceptual Design Report) study. We explore the Higgs signatures for this baseline design with $\nu\bar{\nu}$ Higgs events. The detector performance for reconstructing charged particles, photons and jets is quantified with $H \to \mu\mu, \gamma\gamma$ and jet final states, respectively. The resolutions of reconstructed Higgs boson mass are comparable for the different decay modes with jets in the final states. We also analyze the $H \to WW$ * and ZZ* decay modes, where a clear separation between different decay cascades is observed.
As a Higgs factory, the CEPC (Circular Electron-Positron Collider) project aims at precision measurements of the Higgs boson properties. A baseline detector concept, APODIS (A PFA Oriented Detector for the HIggS factory), has been proposed for the CEPC CDR (Conceptual Design Report) study. We explore the Higgs signatures for this baseline design with
Published:
, doi: 10.1088/1674-1137/43/2/024103
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We propose a dynamical description of the 136Xe + p spallation at 1000 MeV/nucleon with the aim of probing the mechanism which rules the production of intermediate-mass fragments (IMF). The isospin-dependent quantum molecular dynamics (IQMD) model is used to describe the dynamical process of spallation until hot fragments with excitation energy less than a certain value Estop are formed. The statistical code GEMINI is applied to simulate the light-particle evaporation from hot fragments. It is found that IMF production is well described by the model when Estop = 2 MeV/nucleon is used. Comparison of the calculated mean neutron-to-proton ratio and the experimental data indicates that Estop should be 3 MeV/nucleon.
We propose a dynamical description of the 136Xe + p spallation at 1000 MeV/nucleon with the aim of probing the mechanism which rules the production of intermediate-mass fragments (IMF). The isospin-dependent quantum molecular dynamics (IQMD) model is used to describe the dynamical process of spallation until hot fragments with excitation energy less than a certain value Estop are formed. The statistical code GEMINI is applied to simulate the light-particle evaporation from hot fragments. It is found that IMF production is well described by the model when Estop = 2 MeV/nucleon is used. Comparison of the calculated mean neutron-to-proton ratio and the experimental data indicates that Estop should be 3 MeV/nucleon.
Published:
, doi: 10.1088/1674-1137/43/2/024101
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We systematically study different production sources of light nuclei in ultra-relativistic heavy-ion collisions with a new method, an exclusive quark combination model + an inclusive hadron recombination model. We take deuterons and 3He produced in Pb-Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV as examples to show the contribution of different production sources by studying their rapidity densities ${\rm d}N/{\rm d}y$ , yield ratios and transverse momentum ( $p_T$ ) spectra just after hadronization and at the final kinetic freeze-out. We find that about a half of $d$ and a fourth of 3He created just after hadronization can survive after the hadronic evolution process. Nucleons from $\Delta$ resonance decays make a much larger contribution to the regeneration of light nuclei at the hadronic phase stage, and this contribution is about 77% and 90% for $d$ and 3He, respectively, calculated at the final kinetic freeze-out. In addition, we give an explanation for the constant behaviors of yield ratios $d/p$ and 3He $/p$ as a function of the averaged charged multiplicity in Pb-Pb collisions and also provide a possible explanation for the observation that $d/p$ in Pb-Pb collisions is larger by a factor of about two than in pp collisions at LHC energies.
We systematically study different production sources of light nuclei in ultra-relativistic heavy-ion collisions with a new method, an exclusive quark combination model + an inclusive hadron recombination model. We take deuterons and 3He produced in Pb-Pb collisions at
Published:
, doi: 10.1088/1674-1137/43/2/023101
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Lepton number violation processes can be induced by the Majorana neutrino exchange, which provide evidence for the Majorana nature of neutrinos. In addition to the natural explanation of the small neutrino masses, Type-I seesaw mechanism predicts the existence of Majorana neutrinos. The aim of this work is to study the B meson rare decays $B^{+} \to K^{(*)+}\mu^+\mu^-$ in the Standard Model and its extensions, and then to investigate the same-sign decay process $B^{+}\to K^{(*)-}\mu^{+}\mu^+$ . The corresponding dilepton invariant mass distributions are calculated. It is found that the dilepton angular distributions could shed light on the properties of new interactions induced by Majorana neutrinos.
Lepton number violation processes can be induced by the Majorana neutrino exchange, which provide evidence for the Majorana nature of neutrinos. In addition to the natural explanation of the small neutrino masses, Type-I seesaw mechanism predicts the existence of Majorana neutrinos. The aim of this work is to study the B meson rare decays
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We investigate the bipartite entanglement for the boundary states in a simple type of spin networks with dangling edges, in which the two complementary parts are linked by two or more edges. Firstly, the spin entanglement is considered in the absence of the intertwiner entanglement. By virtue of numerical simulations, we find that the entanglement entropy usually depends on the group elements. More importantly, when the intertwiner entanglement is taken into account, we find that it is in general impossible to separate the total entanglement entropy into the contribution from spins on edges and the contribution from intertwiners at vertices. These situations are in contrast to the case when the two vertices are linked by a single edge.
We investigate the bipartite entanglement for the boundary states in a simple type of spin networks with dangling edges, in which the two complementary parts are linked by two or more edges. Firstly, the spin entanglement is considered in the absence of the intertwiner entanglement. By virtue of numerical simulations, we find that the entanglement entropy usually depends on the group elements. More importantly, when the intertwiner entanglement is taken into account, we find that it is in general impossible to separate the total entanglement entropy into the contribution from spins on edges and the contribution from intertwiners at vertices. These situations are in contrast to the case when the two vertices are linked by a single edge.
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Vacuum polarization is a part of the initial-state radiative correction for the cross-section of $e^+e^-$ annihilation processes. In the energy region in the vicinity of narrow resonances $J/\psi$ and $\psi(3686)$, the vacuum polarization contribution from the resonant component has a significant effect on the line-shape of the lepton pair production cross-section. This paper discusses some basic concepts and describes an analytical calculation of the cross-section of $e^+e^-\to\gamma^\ast/\psi\to\mu^+\mu^-$ considering the single and double vacuum polarization effect of the virtual photon propagator. Moreover, it presents some numerical comparisons with the traditional treatments.
Vacuum polarization is a part of the initial-state radiative correction for the cross-section of $e^+e^-$ annihilation processes. In the energy region in the vicinity of narrow resonances $J/\psi$ and $\psi(3686)$, the vacuum polarization contribution from the resonant component has a significant effect on the line-shape of the lepton pair production cross-section. This paper discusses some basic concepts and describes an analytical calculation of the cross-section of $e^+e^-\to\gamma^\ast/\psi\to\mu^+\mu^-$ considering the single and double vacuum polarization effect of the virtual photon propagator. Moreover, it presents some numerical comparisons with the traditional treatments.
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We study the four-body decays of neutral flavored mesons, including $\bar K^0$, $D^0$, $\bar B^0$, and $\bar B_s^0$. These processes, which could be induced by a hypothetical doubly-charged scalar particle, do not conserve the lepton number. Assuming, as an example, that the mass of the doubly-charged particle is 1000 GeV, and using the upper bounds of the couplings, we calculate the branching ratios of different channels. For $\bar K^0\rightarrow h_1^+h_2^+e^-e^-$, $D^0\rightarrow h_1^-h_2^-e^+e^+$, and $\bar B_{d,s}^0\rightarrow h_1^+h_2^+e^-e^-$, it is of the order of $10^{-30}$, $10^{-32}$--$10^{-29}$, and $10^{-33}$--$10^{-28}$, respectively. Based on the experimental results for the $D^0\rightarrow h_1^-h_2^-l_1^+l_2^+$ channels, we also find the upper limit for the quantity $\frac{s_\Delta h_{ij}}{M_\Delta^2}$.
We study the four-body decays of neutral flavored mesons, including $\bar K^0$, $D^0$, $\bar B^0$, and $\bar B_s^0$. These processes, which could be induced by a hypothetical doubly-charged scalar particle, do not conserve the lepton number. Assuming, as an example, that the mass of the doubly-charged particle is 1000 GeV, and using the upper bounds of the couplings, we calculate the branching ratios of different channels. For $\bar K^0\rightarrow h_1^+h_2^+e^-e^-$, $D^0\rightarrow h_1^-h_2^-e^+e^+$, and $\bar B_{d,s}^0\rightarrow h_1^+h_2^+e^-e^-$, it is of the order of $10^{-30}$, $10^{-32}$--$10^{-29}$, and $10^{-33}$--$10^{-28}$, respectively. Based on the experimental results for the $D^0\rightarrow h_1^-h_2^-l_1^+l_2^+$ channels, we also find the upper limit for the quantity $\frac{s_\Delta h_{ij}}{M_\Delta^2}$.
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We study the prospects of probing the anomalous $tHq$~($q= u, c$) couplings via SS2L or 3L signatures at the High Luminosity (HL-LHC) run of the 14 TeV CERN collider. We focus on signals of the $tH$ associated production followed by the decay modes $t\to b\ell^{+}\nu_{\ell}$ and $H\to WW^{\ast}$, and $t\bar{t}$ production followed by the decay modes $t\to b\ell^{+}\nu_{\ell}$ and $\bar{t}\to H(\to WW^{\ast})\bar{q}$, where $\ell=e, \mu$. Based on two types of $H\to WW^{\ast}$ decay topologies, one assuming the semileptonic decay mode $H\to WW^{\ast}\to \ell^{+}\nu jj $ and the other the fully leptonic decay mode $H\to WW^{\ast}\to \ell^{+}\nu \ell^{-}\bar{\nu}$, we perform a full simulation for signals and backgrounds. It is shown that, at the future HL-LHC, the branching ratio $Br(t\to uh)~(Br(t\to ch))$ can be probed to $1.17~(1.56)\times 10^{-3}$ for the same-sign di-lepton channel, and to $7.1~\times 10^{-4}~(1.39~\times 10^{-3})$ for the 3L channel at $3\sigma$ sensitivity.
We study the prospects of probing the anomalous $tHq$~($q= u, c$) couplings via SS2L or 3L signatures at the High Luminosity (HL-LHC) run of the 14 TeV CERN collider. We focus on signals of the $tH$ associated production followed by the decay modes $t\to b\ell^{+}\nu_{\ell}$ and $H\to WW^{\ast}$, and $t\bar{t}$ production followed by the decay modes $t\to b\ell^{+}\nu_{\ell}$ and $\bar{t}\to H(\to WW^{\ast})\bar{q}$, where $\ell=e, \mu$. Based on two types of $H\to WW^{\ast}$ decay topologies, one assuming the semileptonic decay mode $H\to WW^{\ast}\to \ell^{+}\nu jj $ and the other the fully leptonic decay mode $H\to WW^{\ast}\to \ell^{+}\nu \ell^{-}\bar{\nu}$, we perform a full simulation for signals and backgrounds. It is shown that, at the future HL-LHC, the branching ratio $Br(t\to uh)~(Br(t\to ch))$ can be probed to $1.17~(1.56)\times 10^{-3}$ for the same-sign di-lepton channel, and to $7.1~\times 10^{-4}~(1.39~\times 10^{-3})$ for the 3L channel at $3\sigma$ sensitivity.
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This work deals with the behavior of fermions in the background of kinklike structures in the two-dimensional spacetime. The kinklike structures appear from bosonic scalar field models that engender distinct profiles and interact with the fermion fields via the standard Yukawa coupling. We first consider two models that engender parity symmetry, one leading to the exclusion of fermion bound states, and the other to the inclusion of bound states, when the parameter that controls the bosonic structure varies from zero to unity. We then investigate a third model where the kinklike solution explicitly breaks parity symmetry, leading to fermion bound states that are spatially asymmetric.
This work deals with the behavior of fermions in the background of kinklike structures in the two-dimensional spacetime. The kinklike structures appear from bosonic scalar field models that engender distinct profiles and interact with the fermion fields via the standard Yukawa coupling. We first consider two models that engender parity symmetry, one leading to the exclusion of fermion bound states, and the other to the inclusion of bound states, when the parameter that controls the bosonic structure varies from zero to unity. We then investigate a third model where the kinklike solution explicitly breaks parity symmetry, leading to fermion bound states that are spatially asymmetric.
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We use a non-relativistic model to study the spectroscopy of a tetraquark composed of $[cc][\bar{c}\bar{c}]$ in a diquark-antidiquark configuration. By numerically solving the Schr\"{o}dinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c\bar{c}$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the diquark-antidiquark system, despite the heavy diquark mass, and also that the diquark has a finite size if treated in the same way as the $c\bar{c}$ systems. We find that the lowest $S$-wave $T_{4c}$ tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs, while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds. Finally, we repeat the alculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks. This might be relevant to the study of exotic charmonium in the quark-gluon plasma. The $T4c$ states could be investigated in the forthcoming experiments at the LHC and Belle II.
We use a non-relativistic model to study the spectroscopy of a tetraquark composed of $[cc][\bar{c}\bar{c}]$ in a diquark-antidiquark configuration. By numerically solving the Schr\"{o}dinger equation with a Cornell-inspired potential, we separate the four-body problem into three two-body problems. Spin-dependent terms (spin-spin, spin-orbit and tensor) are used to describe the splitting structure of the $c\bar{c}$ spectrum and are also extended to the interaction between diquarks. Recent experimental data on charmonium states are used to fix the parameters of the model and a satisfactory description of the spectrum is obtained. We find that the spin-dependent interaction is sizable in the diquark-antidiquark system, despite the heavy diquark mass, and also that the diquark has a finite size if treated in the same way as the $c\bar{c}$ systems. We find that the lowest $S$-wave $T_{4c}$ tetraquarks might be below their thresholds of spontaneous dissociation into low-lying charmonium pairs, while orbital and radial excitations would be mostly above the corresponding charmonium pair thresholds. Finally, we repeat the alculations without the confining part of the potential and obtain bound diquarks and bound tetraquarks. This might be relevant to the study of exotic charmonium in the quark-gluon plasma. The $T4c$ states could be investigated in the forthcoming experiments at the LHC and Belle II.
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Abstract:
The associated production of Higgs boson with a muon pair, $e^+e^-\to \mu^+\mu^- H$, is one of the golden channels to pin down the properties of the Higgs boson in the prospective Higgs factories exemplified by {CEPC}. The projected accuracy of the corresponding cross section measurement is about per cent level at CEPC. In this work, we investigate both ${\mathcal O}(\alpha)$ weak correction and the ${\mathcal O}(\alpha\alpha_s)$ mixed electroweak-QCD corrections for this channel, appropriately taking into account the effect of finite $Z^0$ width. The $\mu^+\mu^-$ invariant mass spectrum is also predicted. The mixed electroweak-QCD correction turns out to reach 1.5\% of the Born-order result, and thereby must be included in future confrontation with the data. We also observe that, after including higher-order corrections, the simplified prediction for the integrated cross section employing the narrow-width-approximation may deviate from our full result by a few per cents.
The associated production of Higgs boson with a muon pair, $e^+e^-\to \mu^+\mu^- H$, is one of the golden channels to pin down the properties of the Higgs boson in the prospective Higgs factories exemplified by {CEPC}. The projected accuracy of the corresponding cross section measurement is about per cent level at CEPC. In this work, we investigate both ${\mathcal O}(\alpha)$ weak correction and the ${\mathcal O}(\alpha\alpha_s)$ mixed electroweak-QCD corrections for this channel, appropriately taking into account the effect of finite $Z^0$ width. The $\mu^+\mu^-$ invariant mass spectrum is also predicted. The mixed electroweak-QCD correction turns out to reach 1.5\% of the Born-order result, and thereby must be included in future confrontation with the data. We also observe that, after including higher-order corrections, the simplified prediction for the integrated cross section employing the narrow-width-approximation may deviate from our full result by a few per cents.
Published:
Abstract:
Analysis of various mass formulas related to neutron-proton correlations in atomic nuclei is carried out. Using the example of the $N = Z$ chain it is shown that for self-adjoint nuclei various formulas proposed in literature for estimating the $ np $ pairing energy lead to similar results. Significant differences between the calculation methods arise when nuclei with $N \ne Z$ are considered, which allows to reveal the complexity of neutron-proton correlations in different types of atomic nuclei and to make assumptions on the correspondence of the mass relation to the real effect of $ np $ pairing. The Shell Model parametrization of the binding energy makes it possible to draw additional conclusions on the structure of mass formulas and their relationship.
Analysis of various mass formulas related to neutron-proton correlations in atomic nuclei is carried out. Using the example of the $N = Z$ chain it is shown that for self-adjoint nuclei various formulas proposed in literature for estimating the $ np $ pairing energy lead to similar results. Significant differences between the calculation methods arise when nuclei with $N \ne Z$ are considered, which allows to reveal the complexity of neutron-proton correlations in different types of atomic nuclei and to make assumptions on the correspondence of the mass relation to the real effect of $ np $ pairing. The Shell Model parametrization of the binding energy makes it possible to draw additional conclusions on the structure of mass formulas and their relationship.
Published:
Abstract:
We propose alternative methods for measurement of the global polarization of $\Lambda$ hyperons. These methods involve event averages of proton and $\Lambda$ momenta in the laboratory frame. We carry out simulations using these methods and show that all of them work equally well in obtaining the global polarization of $\Lambda$ hyperons.
We propose alternative methods for measurement of the global polarization of $\Lambda$ hyperons. These methods involve event averages of proton and $\Lambda$ momenta in the laboratory frame. We carry out simulations using these methods and show that all of them work equally well in obtaining the global polarization of $\Lambda$ hyperons.
Published:
Abstract:
A simple approach is proposed to describe the experimental data for the widths of the fission-fragment mass yields in $^{197}$Au and $^{209}$Bi at low and intermediate energies. The approach is based on the expressions for the temperature dependence of the width of the fission-fragment mass yield and the mass of the most probable fragment. The expression for the width of the fission-fragment mass yield depends on the mass of the most probable fragment, the surface terms of the energy level density parameter, the temperature and the stiffness parameter of the potential related to mass-asymmetric degree of freedom. It is shown that the contribution of the surface term of the energy level density parameter is important for describing the experimental data in a wide range of energies.
A simple approach is proposed to describe the experimental data for the widths of the fission-fragment mass yields in $^{197}$Au and $^{209}$Bi at low and intermediate energies. The approach is based on the expressions for the temperature dependence of the width of the fission-fragment mass yield and the mass of the most probable fragment. The expression for the width of the fission-fragment mass yield depends on the mass of the most probable fragment, the surface terms of the energy level density parameter, the temperature and the stiffness parameter of the potential related to mass-asymmetric degree of freedom. It is shown that the contribution of the surface term of the energy level density parameter is important for describing the experimental data in a wide range of energies.
Published:
Abstract:
The number of exotic candidates that are beyond the conventional quark model has increased dramatically over recent decades. Some of these can be viewed as analogues of the deuteron. Similarly, the existence of the triton indicates that bound states formed by three hadrons could also exist. To illustrate this possibility, we study the $DD^*K$ and $BB^*\bar{K}$ systems using the Born-Oppenheimer approximation. To leading order, only one-pion exchange potentials are considered. This means that the three constituents share one virtual pion. This is similar to the role of the delocalized {\it $\pi$ bond} for the formation of benzene in chemistry. After solving the Schr\"odinger equation, we find two three-body $DD^*K$ and $BB^*\bar{K}$ bound states with masses $4317.92_{-4.32}^{+3.66}~\mathrm{MeV}$ and $11013.65_{-8.84}^{+8.49}~\mathrm{MeV}$, respectively. The masses of their $D\bar{D}^*K$ and $B\bar{B}^*\bar{K}$ analogues are $4317.92_{-6.55}^{+6.13}~\mathrm{MeV}$ and $11013.65_{-9.02}^{+8.68}~\mathrm{MeV}$, respectively. From the experimental side, the $D\bar{D}^*K$ bound state could be found by analyzing the current world data on the $B\to J/\psi\pi\pi K$ process, by focusing on the $J/\psi \pi K$ channel.
The number of exotic candidates that are beyond the conventional quark model has increased dramatically over recent decades. Some of these can be viewed as analogues of the deuteron. Similarly, the existence of the triton indicates that bound states formed by three hadrons could also exist. To illustrate this possibility, we study the $DD^*K$ and $BB^*\bar{K}$ systems using the Born-Oppenheimer approximation. To leading order, only one-pion exchange potentials are considered. This means that the three constituents share one virtual pion. This is similar to the role of the delocalized {\it $\pi$ bond} for the formation of benzene in chemistry. After solving the Schr\"odinger equation, we find two three-body $DD^*K$ and $BB^*\bar{K}$ bound states with masses $4317.92_{-4.32}^{+3.66}~\mathrm{MeV}$ and $11013.65_{-8.84}^{+8.49}~\mathrm{MeV}$, respectively. The masses of their $D\bar{D}^*K$ and $B\bar{B}^*\bar{K}$ analogues are $4317.92_{-6.55}^{+6.13}~\mathrm{MeV}$ and $11013.65_{-9.02}^{+8.68}~\mathrm{MeV}$, respectively. From the experimental side, the $D\bar{D}^*K$ bound state could be found by analyzing the current world data on the $B\to J/\psi\pi\pi K$ process, by focusing on the $J/\psi \pi K$ channel.
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