The lepton number violation （LNV） process can be induced by introducing a fourth generation heavy Majorana neutrino, which is coupled to the charged leptons of the Standard Model （SM）. There have been many previou...The lepton number violation （LNV） process can be induced by introducing a fourth generation heavy Majorana neutrino, which is coupled to the charged leptons of the Standard Model （SM）. There have been many previous studies on the leptonic number violating decay processes with this mechanism. We follow the trend to study the process： D→Kllπ with the same-sign dilepton final states. We restrict ourselves to certain neutrino mass regions, in which the heavy neutrino could be on-shell and the dominant contribution to the branching fraction comes from the resonance enhanced effect. Applying the narrow width approximation （NWA）, we found that the upper limit for the branching fractions for D^0 → K^- 1＋1＋π- are generally at the order of 10-12 to 10-9, if we take the most stringent upper limit bound currently available in the literature for the mixing matrix elements. We also provide the constraints, which is competitive compared to the LNV B decays, on the mixing matrix element ｜VeN ｜^2 based on the upper limit of D^0→K^-e＋e＋π- estimated from the Monte-Carlo （MC） study at BESⅢ. Although the constraints are worse than the ones from （0vββ） decay in the literature, the future experiment at the charm factory may yield more stringent constraints.展开更多
In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, t...In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, then systematically study their strong decays to ground state charmed mesons plus pseudoscalar mesons with the3P0 decay model. Based on these studies, we assign the D＊J（2760） as the 1D5/23-state, the D＊J（3000） as the 1F5/22＋or 1F7/24＋state, the D J（3000） as the 1F7/23＋or 2P1/21＋state in the D meson family. As a byproduct, we also study the strong decays of the states 2P1/20＋, 2P3/22＋, 3S1/21-, 3S1/20-etc, which will be valuable in searching for the partners of these D mesons.展开更多
The large values and constituent-quark-number scaling of the elliptic flow of low-pT D mesons imply that charm quarks,initially produced through hard processes,might be partially thermalized through strong interaction...The large values and constituent-quark-number scaling of the elliptic flow of low-pT D mesons imply that charm quarks,initially produced through hard processes,might be partially thermalized through strong interactions with quark-gluon plasma(QGP)in high-energy heavy-ion collisions.To quantify the degree of thermalization of low-pT charm quarks,we compare the D^(0)meson spectra and elliptic flow from a hydrodynamic model to experimental data as well as transport model simulations.We use an effective charm chemical potential at the freeze-out temperature to account for the initial charm quark production from hard processes and assume that they are thermalized in the local comoving frame of the medium before freeze-out.D^(0)mesons are sampled statistically from the freeze-out hyper-surface of the expanding QGP as described by the event-by-event(3+1)D viscous hydrodynamic model CLVisc.Both the hydrodynamic and transport models can describe the elliptic flow of D^(0)mesons at pT~3 GeV/c as measured in Au+Au collisions at√SNN=200 GeV.Though the experimental data on D^(0)spectra are consistent with the hydrodynamic result at small pT~1 GeV/c,they deviate from the hydrodynamic model at high transverse momentum,pT~2 GeV/c.The diffusion and parton energy loss mechanisms in the transport model can describe the measured spectra reasonably well within the theoretical uncertainty.Our comparative study indicates that charm quarks only approach local thermal equilibrium at small pT,even though they acquire sizable elliptic flow comparable to light-quark hadrons at both small and intermediate pT.展开更多
The mass spectrum of the D wave mesons is considered in the frame work of relativistic harmonic model (RHM). The full Hamiltonian used in the investigation has the Lorentz scalar plus a vector harmonic-oscillator pote...The mass spectrum of the D wave mesons is considered in the frame work of relativistic harmonic model (RHM). The full Hamiltonian used in the investigation has the Lorentz scalar plus a vector harmonic-oscillator potential, the confined-one-gluon-exchange potential (COGEP) and the instanton-induced quark-antiquark interaction (III). A good agreement between calculated D wave meson masses with experimental D wave meson masses is obtained. The respective role of III and COGEP in the D wave meson spectrum is discussed.展开更多
The positive parity scalar D ＊ s0 （2317） and axial-vector D ＊ s1 （2460） charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and...The positive parity scalar D ＊ s0 （2317） and axial-vector D ＊ s1 （2460） charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D（D s ）-meson ground states.The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian.Chiral corrections to order Q 2 χ are calculated and found to be small.The D ＊ s0 （2317） and D ＊ s1 （2460） mesons decay either strongly into the isospin-violating π 0 D s and π 0 D ？ s channels or electromagnetically.We show that the π 0-η and （K^ 0 D ^＋-K^ ＋ D^ 0 ） mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the KD component of the states.The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q 2 χ .We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays.The radiative width are sensitive to both η D s and KD components,hence providing information complementary to the strong widths on the positive parity D s-meson structure.展开更多
基金Supported by National Natural Science Foundation of China(10935012,11125525)Major Program of National Natural Science Foundation of China(2009CB825200)China Postdoctoral Science Foundation
文摘The lepton number violation （LNV） process can be induced by introducing a fourth generation heavy Majorana neutrino, which is coupled to the charged leptons of the Standard Model （SM）. There have been many previous studies on the leptonic number violating decay processes with this mechanism. We follow the trend to study the process： D→Kllπ with the same-sign dilepton final states. We restrict ourselves to certain neutrino mass regions, in which the heavy neutrino could be on-shell and the dominant contribution to the branching fraction comes from the resonance enhanced effect. Applying the narrow width approximation （NWA）, we found that the upper limit for the branching fractions for D^0 → K^- 1＋1＋π- are generally at the order of 10-12 to 10-9, if we take the most stringent upper limit bound currently available in the literature for the mixing matrix elements. We also provide the constraints, which is competitive compared to the LNV B decays, on the mixing matrix element ｜VeN ｜^2 based on the upper limit of D^0→K^-e＋e＋π- estimated from the Monte-Carlo （MC） study at BESⅢ. Although the constraints are worse than the ones from （0vββ） decay in the literature, the future experiment at the charm factory may yield more stringent constraints.
基金Supported by National Natural Science Foundation of China(11375063)Fundamental Research Funds for the Central Universities(13QN59,2014MS165)
文摘In this work, we tentatively assign the charmed mesons D J（2580）, D＊J（2650）, D J（2740）, D＊J（2760）,D J（3000） and D＊J（3000） observed by the LHCb collaboration according to their spin, parity and masses, then systematically study their strong decays to ground state charmed mesons plus pseudoscalar mesons with the3P0 decay model. Based on these studies, we assign the D＊J（2760） as the 1D5/23-state, the D＊J（3000） as the 1F5/22＋or 1F7/24＋state, the D J（3000） as the 1F7/23＋or 2P1/21＋state in the D meson family. As a byproduct, we also study the strong decays of the states 2P1/20＋, 2P3/22＋, 3S1/21-, 3S1/20-etc, which will be valuable in searching for the partners of these D mesons.
基金Supported by the National Key Research and Development Program of China (2020YFE0202002)the National Natural Science Foundation of China (11935007,11221504, 11861131009, 12075098, 11890714)+2 种基金the Director,Office of Energy Research,Office of High Energy and Nuclear Physics,Division of Nuclear Physics,of the U.S. Department of Energy (DOE)(DE-AC02-05CH11231)the U.S. National Science Foundation (ACI-1550228) within JETSCAPE Collaboration(OAC-2004571) within the X-SCAPE Collaboration by the UCB-CCNU Collaboration Grant
文摘The large values and constituent-quark-number scaling of the elliptic flow of low-pT D mesons imply that charm quarks,initially produced through hard processes,might be partially thermalized through strong interactions with quark-gluon plasma(QGP)in high-energy heavy-ion collisions.To quantify the degree of thermalization of low-pT charm quarks,we compare the D^(0)meson spectra and elliptic flow from a hydrodynamic model to experimental data as well as transport model simulations.We use an effective charm chemical potential at the freeze-out temperature to account for the initial charm quark production from hard processes and assume that they are thermalized in the local comoving frame of the medium before freeze-out.D^(0)mesons are sampled statistically from the freeze-out hyper-surface of the expanding QGP as described by the event-by-event(3+1)D viscous hydrodynamic model CLVisc.Both the hydrodynamic and transport models can describe the elliptic flow of D^(0)mesons at pT~3 GeV/c as measured in Au+Au collisions at√SNN=200 GeV.Though the experimental data on D^(0)spectra are consistent with the hydrodynamic result at small pT~1 GeV/c,they deviate from the hydrodynamic model at high transverse momentum,pT~2 GeV/c.The diffusion and parton energy loss mechanisms in the transport model can describe the measured spectra reasonably well within the theoretical uncertainty.Our comparative study indicates that charm quarks only approach local thermal equilibrium at small pT,even though they acquire sizable elliptic flow comparable to light-quark hadrons at both small and intermediate pT.
文摘The mass spectrum of the D wave mesons is considered in the frame work of relativistic harmonic model (RHM). The full Hamiltonian used in the investigation has the Lorentz scalar plus a vector harmonic-oscillator potential, the confined-one-gluon-exchange potential (COGEP) and the instanton-induced quark-antiquark interaction (III). A good agreement between calculated D wave meson masses with experimental D wave meson masses is obtained. The respective role of III and COGEP in the D wave meson spectrum is discussed.
文摘The positive parity scalar D ＊ s0 （2317） and axial-vector D ＊ s1 （2460） charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D（D s ）-meson ground states.The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian.Chiral corrections to order Q 2 χ are calculated and found to be small.The D ＊ s0 （2317） and D ＊ s1 （2460） mesons decay either strongly into the isospin-violating π 0 D s and π 0 D ？ s channels or electromagnetically.We show that the π 0-η and （K^ 0 D ^＋-K^ ＋ D^ 0 ） mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the KD component of the states.The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q 2 χ .We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays.The radiative width are sensitive to both η D s and KD components,hence providing information complementary to the strong widths on the positive parity D s-meson structure.
