Search

In a modified chromomagnetic interaction model, assuming $X(4140)$ to be the lowest $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark and treating it as the reference state, we systematically investigated the masses of the triply-heavy tetraquark states $QQ\bar{Q}\bar{q}$ ($Q=c,b;q=u,d,s$). Because of their higher masses, no stable tetraquarks were found. Using a simple scheme, we also estimated the partial widths of the rearrangement decay channels and relevant ratios. A compact triply heavy tetraquark candidate would be favored if its observed mass and partial width ratios were comparable with our predictions. We hope that the present work will be helpful for further studies., Comment: 18 pages, 1 figure, 12 tables

Within the framework of non-relativistic quantum chromodynamics (NRQCD), we study the production of doubly charmed tetraquark $T_{cc}$ via photon-photon fusion at electron-positron colliders. Two diquark configurations of $(cc)[^3S_1]_{\bar{3}}$ and $(cc)[^1S_0]_{6}$ are considered, and the $(cc)[^3S_1]_{\bar{3}}$ state dominates the produciotn of $T_{cc}$. We discuss two hadronization models of $(cc)[^3S_1]_{\bar{3}}$ intermediate state into the tetraquark $T_{cc}$. At the Circular Electron Positron Collider (CEPC) with center-of-mass energy $\sqrt{s} = 240$ GeV and the luminosity of $10^{34}\ {\rm cm}^{-2}{\rm s}^{-1}$, it is promising to observe the tetraquark $T_{cc}$ via photon-photon fusion process. We find that the cross sections are sensitive to charm quark mass. And the cross sections at CEPC also have strong dependence on the hadronization models, as well as the photon spectrum functions for initial photons., Comment: 19 pages, 6 figures

The inclusive production of pseudoscalar heavy quarkoniua ($\eta_c,~\eta_b$ and $B_c$) via photon-photon fusion in heavy ion ultraperipheral collision (UPC) are calculated to QCD next-to-leading order in the framework of non-relativistic QCD (NRQCD). The total cross section of $\eta_c$ produced in Pb-Pb UPC is 194 $\mathrm{nb}$ and 1275 $\mathrm{nb}$ at nucleon-nucleon c.m. energies $\sqrt{S_{\mathrm{NN}}}=$ 5.52 TeV and 39.4 TeV, respectively. The cross sections for $\eta_b$ and $B_c$ mesons are more than two to three orders of magnitude smaller. We make a detailed phenomenological analysis on the $\eta_c$ production; the uncertainties caused by the renormalization scale and the charm quark mass, the cross sections in other ultraperipheral nucleon-nucleon colliding systems, and the transverse momentum distribution are discussed. At the coming HL-LHC and future FCC, the heavy ion UPC opens another door of the study on the production of heavy quarkonium., Comment: 17 pages, 1 figures, 4 tables

The finite mass of the heavy quark suppresses the collimated radiations, which is generally referred to as the dead cone effect. In this paper, we study the distribution of hadron multiplicity over the hadron opening angle with respect to the jet axis in various flavors of jets. The corresponding measurement can be the most straightforward and simplest to explore the dynamical evolution of the radiations in the corresponding jet, which can expose the mass effect. We also propose the transverse energy-weighted angular distribution which sheds light on the interplay between perturbative and nonperturbative effects in the radiation. With Monte-Carlo simulations, our calculation shows that the dead cone effect can be clearly seen by taking the ratio between the b jet and the light-quark (inclusive) jet, promising to be measured at the LHC in the future., Comment: 7 pages, 4 figures; published version in CPC

Treating the $X(4140)$ as a compact $J^{PC}=1^{++}$ $cs\bar{c}\bar{s}$ state and using its mass as a reference scale, we systematically estimate the masses of doubly heavy tetraquark states $QQ\bar{q}\bar{q}$ where $Q=c,b$ and $q=u,d,s$. Their decay properties are studied with a simple rearrangement scheme. Based on our results, the lowest $I(J^P)=0(1^+)$ $bb\bar{n}\bar{n}$ state is a stable tetraquark about 20 MeV below the $\bar{B}^*\bar{B}$ threshold. The mass and width of the low-mass $0(1^+)$ $cc\bar{n}\bar{n}$ ($n=u,d$) tetraquark are compatible with the $T_{cc}(3875)^+$ observed by the LHCb Collaboration. The location of the lowest $0(0^+)$ and $0(1^+)$ $bc\bar{n}\bar{n}$ states are found to be close to the $\bar{B}D$ and $\bar{B}^*D$ thresholds, respectively. We hope that the predicted ratios between partial widths of different channels may be helpful to identify compact tetraquark states from future measurements., Comment: 18 pages,3 figures,11 tables

We study the spectrum and rearrangement decays of S-wave $cs\bar{c}\bar{s}$ tetraquark states in a simplified quark model. The masses and widths are estimated by assuming that the $X(4140)$ is the lower $1^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Comparing our results with experimental measurements, we find that the recently observed $X(3960)$ by LHCb can be assigned as the lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark state and the $X_0(4140)$ could be the second lowest $0^{++}$ $cs\bar{c}\bar{s}$ tetraquark. Predictions of ratios between partial widths for the involved tetraquarks are given. We call for searches for more $cs\bar{c}\bar{s}$ tetraquarks with $J^{PC}=1^{+-}$, $0^{++}$, and $2^{++}$., Comment: 1 figure

Assuming that the $P_c(4312)^+$ is a $I(J^P)=\frac12(\frac32^-)$ compact pentaquark, we study the mass spectrum of its S-wave hidden-charm partner states in a color-magnetic interaction model. Combining the information from their decays obtained in a simple rearrangement scheme, one finds that the quantum numbers of $P_c(4457)^+$, $ P_c(4440)^+$, and $P_c(4337)^+$ can be assigned to be $I(J^P)=\frac12(\frac32^-)$, $\frac12(\frac12^-)$, and $\frac12(\frac12^-)$, respectively, while both $P_{cs}(4338)^0$ and $P_{cs}(4459)^0$ can be interpreted as $I(J^P)=0(\frac12^-)$ $udsc\bar{c}$ compact states. Based on the numerical results, we also find narrow pentaquarks in $ssnc\bar{c}$ ($n=u,d$) and $sssc\bar{c}$ systems. The decay properties of the studied pentaquarks and the searching channels for them can be tested in future experiments., Comment: 17 pages, 14 tables, 4 figures

Decay amplitude of $H \to \gamma Z$ process via one $W$ loop in the unitary gauge is presented. The divergent integrals including those of high divergence orders typical of unitary gauge are arranged to cancel to get the electromagnetic $U(1)$ gauge invariant finite result, hence no contribution to the renormalization constant of $Z\gamma$ mixing in this 1-loop subprocess. For the calculation of the Feynman diagrams employing the Feynman rules, all the integrations of the propagator momenta and all the delta-functions representing the 4-momentum conservation of every vertex are retained in the beginning. Therefore, the ambiguity of setting independent loop momentum for divergences worse than logarithmic does not exist, and shift of integrated variable in such divergent integrals is eschewed. The calculation are done in 4-dimension Minkowski momentum space without the aid of any regularization. The correct treatment on the surface terms for the quadratic and logarithmic tensor integral is one of the key points. This part I is devoted to the calculation details and the indications from the key surface terms. Comparing with other gauge(s) and complete results for $H \to \gamma Z$ are left for part II., Comment: 29 pages, 3 figures. This paper is mainly for calculation details as ref. arXiv admin note: text overlap with arXiv:1705.04941

We study the relations between low-energy constants (LECs) in the chiral Lagrangians with $\Delta(1232)$ and those in the quark-level description model up to the third chiral order. Ten structure correspondences are involved in getting the relations. This situation is more complicated than the spin-1/2 baryon case. The obtained results may help to further investigations involving the $\Delta(1232)$ baryons., Comment: Version accepted by Eur. Phys. J. C. 10 pages, 2 figures, 4 tables

The quark model symmetry can be adopted to establish relations between the low-energy constants (LECs) in the baryon chiral perturbation theory ($\chi PT$) if one assumes that a baryon-baryon-meson coupling is described equivalently by a quark-quark-meson coupling at the quark level. Through the correspondence between the $SU(2)$ description and the $SU(3)$ description for the same coupling vertex at the quark level, we find some relations between the LECs in $SU(2)_{\chi PT}$ and $SU(3)_{\chi PT}$ up to the third chiral order. The $SU(3)_{\chi PT}$ LEC relations at the same order are also obtained. The numerical analysis roughly supports these relations. In the situation that the available experimental data are not enough, one may employ such constraints to reduce the number of LECs., Comment: Version to appear in PRD. 16 pages, 2 figures, 7 tables

In high energy scattering, multiproduction process is unique in its relevance to the total cross section and in its global property such as rapidity and other kinematic distributions. If there is hard interaction, the jet rate and structure is a good arena of perturbative chromodynamics. However, once any hadron is specified, its property and structure must make sense while the global and/or perturbative chromodynamics mechanism still can put important constrains. The relation of the hadron property and structure with its production cross section, distribution etc. can be much more complex than its decay width. In one hand there are many difficulties and challenges in calculation; on the other hand, production process provides unique way to study the details of property and structure of the hadron, which is beyond the approach of its decay process. Here I review our works on such topic in recent years, mainly on the multiquark state production in multiproduction process and the Bethe-Salpeter wave function in exclusive process. For the former, I emphasize on the unitarity of hadronization process and relevant models, so that Almost No multiquark state is observed in multiproduction process; I also address how to calculate hadron molecule production in multiproduction process; the most recent observed $T^+_{cc}$ is also stated with its relevance to colour and baryon number fluctuation of the preconfinement clusters. For the latter, I emphasize the Dirac structure of the hadron-quark coupling vertex., Comment: Proceedings of 50th International Symposium on Multiparticle Dynamics (ISMD2021), three pages of contents. New version, modified according to the journal requirement, new grammarical modification acr. to Editor

The loop momenta of a single Feynman diagram in momentum space can be assigned unambiguously within the 'Dyson scheme' without referring to the other Feynman diagrams in the complete set to some order of coupling constant for the certain process. This fact and the scheme which were provided in Dyson's original paper are applied to a typical relevant problem, i.e., the triangle diagrams of the 'axial vector current anomaly'. The calculation is done in four-dimension Minkowski space-time straightforwardly without the aid of any regularization. The linearly divergent terms are canceled sans incertitude. The logarithmically divergent symmetric integration (tensor integration) is investigated for obtaining the consistent and gauge invariant result., Comment: 16 pages, 2 Feynman diagrams, several discussions and one ref. added

We suggest to study the production mechanism and some details of the production properties to probe the structure of the DDpi resonance T_cc^+ recently observed by the LHCb Collaboration. If the resonance is produced as a four-quark state, one can find the corresponding finger prints via measurements on some production properties that are the same as those of Xi_cc. The reason is that a special colour connection on the interface between the perturbative and non perturbative QCD is required for these doubly-charm hadron production. On the other hand, if T_cc^+ is produced as a hadron molecule, the measurement on the momentum correlation of DD^* can be a smoking gun to make the judgement. The present data favour a compact four-quark state production via the cc diquark fragmentation., Comment: 20 papges, 6 figs

In the framework of the perturbative Quantum Chromodynamics factorization, the cross section of the heavy meson production via the combination of a heavy quark with a light one can be factorized to be the convolution of the combination matrix element, the light quark distribution function, and the hard partonic sub-cross section of the heavy quark production. The partonic distribution and the combination matrix element are functions of a scaling variable, respectively, which is the momentum fraction of the corresponding quark with respect to the heavy meson. We studied the $D^{*\pm}$ production in jet via combination in pp collision at the LHC. Our calculation can be summed with the fragmentation contribution, and the total result is comparable with the experimental data. The combination matrix elements can be further studied in various hadron production processes., Comment: 15 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:hep-ph/0501290

We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak. At the second order of QCD coupling, we consider the exact calculation of flavour-singlet contributions where the Higgs boson couples to the internal top and bottom quark. Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process. High precision production for $h\to c\bar{c}$ within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark. As an example, we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions., Comment: 18 pages, 7 figures

We calculate the masses of the $QQ\bar{q}\bar{q}$ ($Q=c,b$; $q=u,d,s$) tetraquark states with the aid of heavy diquark-antiquark symmetry (HDAS) and the chromomagnetic interaction (CMI) model. The masses of the highest-spin ($J=2$) tetraquarks that have only the $(QQ)_{\bar{3}_c}(\bar{q}\bar{q})_{3_c}$ color structure are related with those of conventional hadrons using HDAS. Thereafter, the masses of their partner states are determined with the mass splittings in the CMI model. Our numerical results reveal that: (i) the lightest $cc\bar{n}\bar{n}$ ($n=u,d$) is an $I(J^P)=0(1^+)$ state around 3929 MeV (53 MeV above the $DD^*$ threshold) and none of the double-charm tetraquarks are stable; (ii) the stable double-bottom tetraquarks are the lowest $0(1^+)$ $bb\bar{n}\bar{n}$ around 10488 MeV ($\approx116$ MeV below the $BB^*$ threshold) and the lowest $1/2(1^+)$ $bb\bar{n}\bar{s}$ around 10671 MeV ($\approx20$ MeV below the $BB_s^*/B_sB^*$ threshold); and (iii) the two lowest $bc\bar{n}\bar{n}$ tetraquarks, namely the lowest $0(0^+)$ around 7167 MeV and the lowest $0(1^+)$ around 7223 MeV, are near-threshold states. Moreover, we discuss the constraints on the masses of double-heavy hadrons. Specifically, for the lowest nonstrange tetraquarks, we obtain $T_{cc}<3965$ MeV, $T_{bb}<10627$ MeV, and $T_{bc}<7199$ MeV., Comment: 19 pages, 4 figures, and 11 tables

Upsilon (1S) decay to Xi_cc +anything is studied. It is shown that the branching ratio can be as significant as that of Upsilon (1S) decay to J/Psi +anything. The non-relativistic heavy quark effective theory framework is employed for the calculation on the decay width. Measurements on the production of Xi_cc and likely production characteristic of the partonic state with four charm quarks at BELLE2 are suggested., Comment: 13 pages, 6 figs, language updated in the 2nd version

We have systematically investigated the mass spectrum and rearrangement decay properties of the exotic tetraquark states with four different flavors using a color-magnetic interaction model. Their masses are estimated by assuming that the $X(4140)$ is a $cs\bar{c}\bar{s}$ tetraquark state and their decay widths are obtained by assuming that the Hamiltonian for decay is a constant. According to the adopted method, we find that the most stable states are probably the isoscalar $bs\bar{u}\bar{d}$ and $cs\bar{u}\bar{d}$ with $J^P=0^+$ and $1^+$. The width for most unstable tetraquarks is about tens of MeVs, but that for unstable $cu\bar{s}\bar{d}$ and $cs\bar{u}\bar{d}$ can be around 100 MeV. For the $X(5568)$, our method cannot give consistent mass and width if it is a $bu\bar{s}\bar{d}$ tetraquark state. For the $I(J^P)=0(0^+),0(1^+)$ double-heavy $T_{bc}=bc\bar{u}\bar{d}$ states, their widths can be several MeVs., Comment: Version published in PRD. 18 pages, 1 figure, 9 tables

Dark sector may couple to the Standard Model via one or more mediator particles. We discuss two types of mediators: the dark photon $A^{\prime}$ and the dark scalar mediator $\phi$. The total cross-sections and various differential distributions of the processes $e^{+} e^{-} \rightarrow q \bar{q} A^{\prime}$ and $e^{+} e^{-} \rightarrow q \bar{q} \phi$ ($q=u,~d,~c,~s$ and $b$ quarks) are discussed. We focus on the study of the invisible $A^{\prime}$ due to the cleaner background at future $e^{+} e^{-}$ colliders. It is found that the kinematic distributions of the two-jet system could be used to identify (or exclude) the dark photon and the dark scalar mediator, as well as to distinguish between them. We further study the possibility of a search for dark photons at a future CEPC experiment with $\sqrt{s}=$ 91.2 GeV and 240 GeV. With CEPC running at $\sqrt{s}=$ 91.2 GeV, it would be possible to perform a decisive measurement of the dark photon (20 GeV $< m_{A^{\prime}} <$ 60 GeV) in less than one operating year. The lower limits of the integrated luminosity for the significance $S/\sqrt{B}=$ 2$\sigma$, 3$\sigma$ and 5$\sigma$ are presented., Comment: 17 pages, 10 figures, to be published in Chinese Physics C

A completely relativistic quark model in the Bethe-Salpter framework is employed to calculate the exclusive production ratio of the neutral over charged Kaon pair in $e^+e^-$ annihilation continuum region for center of mass energies smaller than the $J/\Psi$ mass. The valence quark charge plays the key r\^{o}le. The cancellation of the diagrams for the same charge case (in $K_S + K_L$) and the non-cancellation of the diagrams for the different charge case (in $K^-+K^+$) lead to the ratio as $(m_s-m_d)^2/M_{Kaon}^2 \sim 1/10$., Comment: 6 papges, 4 figures. This paper is dedicated to M. Gell-Mann In v2 several refs. added

The heavy singlet Majorana neutrinos are introduced to generate the neutrino mass in the so-called phenomenological type-I seesaw mechanism. The phenomena induced by the heavy Majorana neutrinos are important to search for new physics. In this paper, we explore the heavy Majorana neutrino production and decay at future $e^{-}p$ colliders. The corresponding cross sections via $W$ and photon fusion are predicted for different collider energies. Combined with the results of the heavy Majorana neutrino production via single $W$ exchange, this work can provide helpful information to search for heavy Majorana neutrinos at future $e^{-}p$ colliders., Comment: 15 pages, 16 figures

The direct observation of the Yukawa interaction related to Standard Model Higgs and the bottom quark is obtained from the $h\to b\bar{b}$ process recently. The b-tagging becomes an important tool to search for new heavy resonance production at LHC. We use the b-tagging method to investigate the neutral Higgs production in association with a bottom quark pair, and perform the detector simulation for the signal process with the Higgs decaying into $b\bar{b}$ or $\tau^+\tau^-$ together with the dominant backgrounds. Our results show that $b\bar{b}b\bar{b}$ and $b\bar{b}\tau^+\tau^-$ processes will play an important role to search for the exotic heavy Higgs production at LHC and future hadron colliders., Comment: 21 pages, 12 figures

We discuss the mass splittings for the $S$-wave triply heavy pentaquark states with the $QQQq\bar{q}$ $(Q=b,c;q=u,d,s)$ configuration which is a mirror structure of $Q\bar{Q}qqq$. The latter configuration is related with the nature of $P_c(4380)$ observed by the LHCb Collaboration. The considered pentaquark masses are roughly estimated with a simple method. One finds that such states are probably not narrow even if they do exist. This leaves room for molecule interpretation for a state around the low-lying threshold of a doubly heavy baryon and a heavy-light meson, e.g. $\Xi_{cc}D$, if it were observed. As a by product, we conjecture that upper limits for the masses of the conventional triply heavy baryons can be determined by the masses of the conventional doubly heavy baryons., Comment: 19 pages, 1 figure, 10 tables; Version accepted by Eur. Phys. J. C

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 standard model backgrounds, so that it is possible to search for $W'$ signal at the LHC with its mass less than 6.6 TeV., Comment: 20 pages, 14 figures

We study one possible production mechanism for hidden charm pentaquark in e+e- collision, where it is produced via a color-octet c \bar c pair fragmentation. The pentaquark production at B factory energy is dominated by e+e- to c \bar c g to Pc + X. At Z^0 pole, for the pentaquark production, there are several partonic processes playing significant role. Our results show that it is possible to search for the direct pentaquark production signal at e+e- colliders, which is important to understand the properties of pentaquark., Comment: 8 pages, 4 figures, 2 tables

Following the thread of R. Gastmans, S. L. Wu and T. T. Wu, the calculation in the unitary gauge for the $H \to \gamma \gamma$ process via one W loop is repeated, but without the specific choice of the independent loop momentum for the Feynman diagrams. This is based on the original 'Dyson scheme' provided in Dyson's classical paper. I.e., the original integrations on all propagator momenta are kept, not expressed by the specified independent loop momentum. Correspondingly, the 4-dimension $\delta$ function at each vertex in which the 4-momentum conservation is embedded, is retained. Together with the Ward identity of the W-W-photon vertex, the 4-momentum conservation of each vertex guarantee the cancellation of all divergent integrals worse than logarithmic without any uncertainty or ambiguity, with any shift of integrated momentum eschewed. The calculation is in 4-dimension Minkowski phase space and without any help of regularization. The resulting integrals are to the most logarithmically divergent, hence is invariant for various setting of the independent loop momentum and any of its shift. At last the logarithmically divergent symmetric (tensor) integration is determined by the boundary condition at infinity in momentum space inherent of the free Feynman propagator, and the gauge (both $SU(2)\times U_Y(1)$ and $U_{em}(1)$) invariant finite result can be obtained without the introduction of the 'Dyson subtraction'. The physical boundary conditions at infinity of phase space can make sense in many problems., Comment: 1 figure, 31 pages (updated). The surface terms are clarified, so that the gauge (both $SU(2)\times U_Y(1)$ and $U_{em}(1)$) invariant finite result is obtianed. This observation is used in calculating axial vector anomaly in 2109.14835, and in calculating H to gamma Z (to be submitted). Physical implication of the surface term is discussed

The non-relativistic wave function framework is applied to study the production and decay of the exotic hadrons which can be effectively described as bound states of other hadrons. Employing the factorized formulation, we investigate the production of exotic hadrons in the multiproduction processes at high energy hadronic colliders with the help of event generators. This study provides crucial information for the measurements of the relevant exotic hadrons., Comment: This paper also serves partially as the long write-up for the paper arXiv:1603.03250, to be published in Chinese Physics C

The production rate of the X(5568) observed by D0 collabotation is quite large and can not be understood by various general hadronization mechanism. We propose an inclusive resonance production formulation to calculate the cross section and extract the value of the effective wave function at origin. Based on these results we suspect X($D_s \pi^{\pm}$) can be copiously produced and observable at high enenrgy scatterings (the relative production ratio to D_s is larger than 10 %). In the updated version the discussions on cluster model and FI are added. Both cases can not give large rate. Then we show that pion in X(5568) decay can only gain a very small momentum. In the pseudo-rapidity region [2,5], large part of the signal pions will be dismissed by the detector since the transverse mometum is too small and/or total momentum too small. If further requirement on pion tranverse mometum larger than 1GeV/c added, almost all signal pions are rejected. But for the charm partner, this problem does not exist since the charm partner can give a larger boost factor. A 3D distribution of signal pions are added, Comment: 10 pages, 2 figures

Wave propagation in nonlinear theories of the electromagnetism described by Lagrangian densities dependent upon its two local invariants L(F, G) is revisited. On the light of the recent findings in metamaterials, it is here shown that trirefringence is also a possible phenomenon to occur in the realm of such nonlinear theories. A specific model exhibiting this effect is investigated both in terms of phase and group velocities. It is claimed that wave propagation in some well known nonlinear models for spin-one fields, like QED and QCD in certain regimes, may exhibit trirefringence., Comment: 7 pages, 2 figures

The doubly charmed hadron production at B factories is of special importance for the study of the hadron structure and the color connections before hadronization. To suppress the combination background fluctuations of the reconstructed hadron mass spectra, we suggest a three-jet event shape trigger. After these three jets are identified by their energy and angular distributions, it is found that: 1) The background process $e^+ e^- \to c\bar {c} \to h's$ in consideration of the final hadron system $\Lambda_c^+K^-\pi^+ +X$ are significantly suppressed. 2) For the selected events, about half of the particles, $\Lambda_c^+$, $K^-$, $\pi^+$, which obviously can not belong to the decay products of doubly charmed hadron, can be vetoed. The relevant hadronization is investigated., Comment: 14 pages, 8 figures. arXiv admin note: text overlap with arXiv:1309.5849

The hadronization effects induced by various colour connections of the four quark system in $e^{+}e^{-}$ annihilation are briefly reviewed. A special colour connection of four heavy quark system without colour-separation favours the production of doubly heavy baryons. For the related three-jet case, the corresponding hadronization has not been considered. We argue that it can be effectively described as two string fragmentation besides the leading heavy diquark fragmentation. The production rate and the properties of final state hadron systems are discussed. Emphasis is on the string effect as a finger print of this hadronization procedure., Comment: 17 pages, 8 figures

We investigate the possibility to discover the charged Higgs via $pp\to W^{\pm}H^{\mp}\to l+\met+b\bar{b}jj$ process at LHC, which suffers from large QCD backgrounds. We optimize the kinematic cuts to suppress the backgrounds, so that the reconstruction of the charged Higgs through hadronic decay is possible. The angular distribution of the b-jet from $H^{\pm}$ decay is investigated as a way to identify the charged scalar from vector bosons.

First we call the attention that velocity defined by ratio between some intervals of space and time respectively is sometimes ambiguous, in the framework of quantum theory. Velocity in general is not possible to be well defined as some generator of certain space-time symmetry operation. Then in section 3 by analyzing the OPERA experiment we show that the OPERA Collaboration may have measured the phase speed of the neutrino wave function. Employing a very (maybe too) simple model which is just a reproduction from Brillouin's classical book, we demonstrate the phase velocity and group velocity. These are just a qualitative illustration rather than aiming to quantitively explain the OPERA data. However, how to rigorously define the phase containing the particle production ordering information as a space-time distribution observable in QFT needs more investigations. Due to the finite life time of the pions (w.r.t. its flying time in the 1 km long tunnel) which decay to the muon neutrinos, the wave form for neutrinos recorded by OPERA is deformed from that of the proton. Such an effect is estimated to lead to an advanced time displacement of the order of 100ns, which coincides with the measured. Such an effect can only be significant when measuring phase speed and the recorded neutrino events per extraction of proton smaller than one, as the OPERA case., Comment: 12 pages for 12pt

We presented a general classification scheme for the tripartite $L\times N\times N$ entangled system under stochastic local operation and classical communication. The whole classification procedure consists of two correlated parts: the simultaneous similarity transformation of a commuting matrix pair into a canonical form and the study of internal symmetry of parameters in the canonical form. Based on this scheme, a concrete example of entanglement classification for a $3\times N\times N$ system is given., Comment: 21 pages; published in Phys. Rev. A

Entropy change in exclusive quark combination models is not an isolated problem. Contrary to adding and tuning some parameters to the relevant model(s) to fix the entropy, we show that it relates to the most general principles. Unitarity of the combination model is demonstrated to play the central r\^{o}le that guarantees the non-decrease of the entropy in the exclusive combination process., Comment: 4 pages in revtex, 1 figure, a ref. added

We have employed the framework of Bethe-Salpeter equation under covariant instantaneous ansatz to calculate leptonic decay constants of unequal mass pseudoscalar mesons like pi, K, D, Ds and B and radiative decay constants of neutral pseudoscalar mesons like pi and etac in two photon decays of these mesons. In the Dirac structure of hadronic BS wave function, the covariants are incorporated from their complete set in accordance with a recently proposed power counting rule, order-by-order in powers of inverse of meson mass. The decay constants are calculated with the incorporation of both Leading order (LO) and the Next-to-leading order (NLO) Dirac covariants. The contribution of both LO as well as NLO Dirac covariants are studied in detail in this paper. The results are found to improve dramatically and hence validating the power counting rule which also provides a practical means of incorporating Dirac covariants in the BS wave function for a hadron., Comment: article and four figures

The philosophy on production of exotic hadrons (multi-quark states) in the framework of quark combination model is investigated, taking $f_0(980)$ as an example. The production rate and $p_T$ spectra of $f_0(980)$ considered as $(s\bar s)$ or $(s\bar q\bar s q)$ respectively, are calculated and compared in Au+Au collisions at $\sqrt{s_{NN}}=200GeV$. The unitarity of various combination models, when open for exotic hadron production, is addressed., Comment: 5 pages, 1 figure, new version with minor corrections and one ref. added

This is a version submitted to proceedings of sqm09. The space time of hard interaction induced radiation (collinear, double log) and jet-QGM-interaction-induced radiation (bremsstrahlung + pionization) is more clarified. A hand-drawing picture is attached for interested reader. To measure y=1.2 to 2.2 more suppressed (than y=0) open charm pT spectrum is predicted and suggested as a good test., Comment: revtex4 (V5)

We employ the framework of Bethe-Salpeter equation under Covariant Instantaneous Ansatz to study the leptonic decays of pseudoscalar mesons. The Dirac structure of hadron-quark vertex function $\Gamma $ is generalized to include various Dirac covariants besides $\gamma_5 $ from their complete set. The covariants are incorporated in accordance with a power counting rule, order by order in powers of the inverse of the meson mass. The decay constants are calculated with the incorporation of leading order covariants. Most of the results are dramatically improved., Comment: new version of the paper

The recent measurements by CLEO Collaboration for the inclusive J/Psi and Psi(2S) production in Upsilon(1S) decay and our previous calculation are analyzed. The J/Psi momentum spectrum and the production ratio of Psi(2S) versus J/Psi favour Upsilon to J/Psi(Psi(2S)) + ccbar g as the dominant contribution. We point out that the differences between the experimental data and our previous results are mainly originated from the setting of the parameter charm quark mass. We further suggest the associate strange particle enhancement as a probe for the open charm particles in Upsilon to J/Psi (Psi(2S)) + ccbar g., Comment: minor corrections during proof-reading

The hadronization effects induced by different colour connections of $c\bar{c}q\bar{q}$ system in $e^+e^-$ annihilation are investigated by a toy model where diquark fragmentation is employed based on Pythia. It is found that the correlations between the charm baryons and charm antibaryons produced via diquark pair fragmentation are much stronger, and their momentum spectra are harder than those from the standard colour connection in Pythia., Comment: 10 pages, 7 figures and 1 table in latex with axodraw.sty, version to appear in PLB

We employ the framework of Bethe-Salpeter equation under Covariant Instantaneous Ansatz (CIA) to study the leptonic decays of vector mesons. The structure of hadron-quark vertex function Gamma is generalized to include various Dirac covariants (other than i gamma dot epsilon) from their complete set. They are incorporated in accordance with a naive power counting rule order by order in powers of the inverse of the meson mass. The decay constants for rho omega and phi mesons are calculated with the incorporation of leading order covariants., Comment: 18 pages, 1 table and 1 figure in pdf file; Version to appear in JPG

In relativistic heavy ion collisions, the cross section of heavy hadron production via the combination of a heavy quark with a light one from the quark-gluon matter can be factorized. It is the convolution of twist-4 combination matrix elements, the parameters corresponding to the parton distributions of the quark-gluon matter, as well as the hard partonic cross section of heavy quark production calculable in PQCD. These parton distributions and combination matrix elements are functions of a scaling variable which is the momentum fraction of the heavy quark w.r.t. the heavy hadron. In the same factorization framework, the combination matrix elements appear in other `simpler' processes and can be extracted. Taking them as inputs, comparing with data from RHIC and (future) LHC, we can get the parton distributions of the quark-gluon matter just as the similar way we get those of nucleon, pion, or photon, etc.., Comment: 17 pages in A4 preprint form and 12pt, 2 figures

We replace in the event generator JETSET the color singlet chain connection with the color separate state one as the interface between the hard and soft sectors of hadronic processes. The modified generator is applied to produce the hadronic events in $e^+ e^-$ annihilation. It describes the experimental data at the same level as the original JETSET with default parameters. This should be understood as a demonstration that color singlet chain is not the unique color connection. We also search for the difference in special sets of three-jet events arising from different color connections, which could subject to further experimental test., Comment: 23 pages, 8 figures, 4 tables, Revtex4

Hadronic events in $e^+ e^- \to Z^0$ are generated by a Monte-Carlo model including the production of colour separate states. These events are compared with those produced by the JETSET with default set of parameters where the colour connections are colour singlet chains. By selecting two-jet-like events and a sensitive observable, we find that these two kinds of colour connections lead to significant differences in the hadronic states., Comment: 9 figs, 4 pps in revtex