arXiv subjects

Jian-Xiong Wang

Publications and source records attributed to Jian-Xiong Wang.

At least 55 records · Page 3Linked to original sources

arXiv2009

Discovery Potential of New Boson $W_1^{\pm}$ in the Minimal Higgsless Model at LHC

In this paper, we demonstrate the LHC discovery potential of new charged vector boson $W_1^{\pm}$ predicted by the Minimal Higgsless model in the process $pp\to W_1^{\pm}qq^{\prime}\to W^{\pm}Z^0qq^\prime\to \ell^{\pm}\ell^+\ell^-νqq^{\prime}(\ell=e,μ)$ by analyzing the generator level events of the signal and backgrounds. The generator for the signal $pp \to {W_1}^{\pm}qq^\prime\to W^{\pm}Z^0qq^\prime$ at tree level is developed with the Minimal Higgsless model and then interfaced with PYTHIA for the parton showers and hadronization. The backgrounds are produced with PYTHIA and ACERMC. We give integrated luminosities required to discover 5$σ$ signal as a function of $W_1^{\pm}$ mass.

hep-ex↗

arXiv2009

QED contribution to the production of J/ψ+c\bar{c}+X at the Tevatron and LHC

We calculate α^{2}α_{s}^{2} order QED contribution to J/ψproduction in pp(\bar{p})\to J/ψ+c\bar{c} color-singlet process at the Tevatron and LHC in the framework of non-relativistic QCD. The contribution of the interference between the α^{2}α_{s}^{2} QED and α_{s}^{4} QCD is also taken into account. The J/ψproduction associated with a charm quark pair could be a measurable signal at hadron collider experiment. Our calculations show that by including the QED contribution, the p_{t} distribution is enhanced by a factor of 1.5 (1.9) at the Tevatron (LHC) at p_{t}=50 (100) GeV. In addition, the polarization of J/ψturns from unpolarized in all region to increasingly transverse when p_{t} becomes larger.

hep-ph↗

arXiv2009

Next-to-Leading-Order QCD Corrections to e^ + e^- -> J/ψ+gg at the B Factories

We calculate the next-to-leading-order (NLO) QCD corrections to $e^+e^-\to J/ψg g$ via color singlet $J/ψ(^3{-0.8mm}S_1)$ at the B factories. The result shows that the cross section is enhanced to $0.373\pb$ by a K factor (NLO/LO) of about 1.21. By considering its dependence on the charm quark mass and renormalization scale, the NLO cross section can range from 0.294 to $0.409\pb$. Further including the $ψ^\prime$ feed-down, $σ(e^+e^-\to \jpsi X(\mathrm{non} c\bar{c}))$ is enhanced by another factor of about 1.29 and reaches $0.482\pb$. In addition, the momentum distributions of $J/ψ$ production and polarization are presented. Recent measurements from Belle agree well with our prediction for the cross section and momentum distribution. It is expected that this process can serve as a very good channel to clarify the $J/ψ$ polarization puzzle by performing further experimental measurements.

hep-ph↗

arXiv2009

J/ψProduction Via Photon Fragmentation at Hadron Colliders

The transverse momentum ($p_t$) distributions of production and polarization for $J/ψ$ measured by CDF Collaboration are still challenging our understanding of the heavy quarkonium production mechanism even with recent significant theoretical progresses on the next-to-leading-order (NLO) QCD calculation. We suggest a new mechanism for $J/ψ$ production at hadron collider, $pp(\bar p)\to γ^{\ast}(J/ψ)+X$ with $J/ψ$ from a virtual photon $γ^{\ast}$ fragmentation. Our calculations show it's $p_t$ distribution at NLO will be larger than that of the conventional $J/ψ$ production from the color-singlet mechanism at NLO when $p_{t}>26$ (35) GeV at the Tevatron (LHC) and reach about 6 (10) times of the conventional one when $p_t=50$ (100) GeV at the Tevatron (LHC), in spite of a suppression factor $(α/α_s)^2$ that is associated with the QED and QCD coupling constants. In addition, it also has large impact on the $p_{t}$ distribution of $J/ψ$ polarization in large $p_{t}$ region. Therefore, it is a important mechanism for $J/ψ$ production at large $p_t$ region especially for the LHC.

hep-ph↗

arXiv2009

Next-to-Leading-Order QCD corrections to J/ψ(Υ)+γproduction at the LHC

In this work, we calculate the next-to-leading-order (NLO) QCD corrections to the process $p+p \to J/ψ+ γ$ via the color-singlet mechanism at the LHC. The results show that the partial cross section ($p_t^{J/ψ}>$3GeV and $|y^{J/ψ,γ}|<$3) is enhanced by a factor of about 2.0, and the differential cross section can be enhanced by two orders of magnitude in the large transverse momentum region of $J/ψ$. Furthermore, the polarization of $J/ψ$ changes from transverse polarization at leading-order to longitudinal polarization at NLO. For the inclusive $J/ψ$ hadroproduction, it is known that the color-octet contributions are one order of magnitude larger than the color-singlet contribution, and the polarization distribution is dominated by the color-octet behavior at NLO. In contrast, for $J/ψ+γ$ production the color-singlet contribution is of the same order as the color-octet contribution, and the polarization distribution arises from both the color-singlet and color-octet. Therefore, measurements of $J/ψ$ production associated with a direct photon at the hadron collider could be an important supplement to testify the theoretical framework treating with the heavy quarkonium. In addition, an NLO QCD correction to $Υ+γ$ production at the LHC is also presented in this paper.

hep-ph↗

arXiv2008

Exclusive $eta_b$ decay to double $J/ψ$ at next-to-leading order in $alpha_s$

Within the nonrelativistic QCD (NRQCD) factorization framework, we calculate the exclusive decay process η_b \to J/ψJ/ψto next-to-leading order in the strong coupling constant, while at leading order in charm quark relative velocity. It is found that this new contribution to the amplitude is comparable in magnitude with the previously calculated relativistic correction piece, but differs by a phase about 90^\circ. Including this new contribution will increase the previous prediction to B(η_b \to J/ψJ/ψ) substantially, thus brightening the discovery potential of this clean hadronic decay channel of η_b in the forthcoming LHC experiment.

hep-ph↗

arXiv2008

QCD corrections to polarization of J/ψand Υat Fermilab Tevatron and CERN LHC

In this work, we present more detail of the calculation on the NLO QCD corrections to polarization of direct J/psi production via color singlet at Tevatron and LHC, as well as the results for Upsilon for the first time. Our results show that the J/psi polarization status drastically changes from transverse polarization dominant at LO into longitudinal polarization dominant in the whole range of the transverse momentum $p_t$ of J/psi when the NLO corrections are counted. For Upsilon production, the p_t distribution of the polarization status behaves almost the same as that for J/psi except that the NLO result is transverse polarization at small p_t range. Although the theoretical evaluation predicts a larger longitudinal polarization than the measured value at Tevatron, it may provide a solution towards the previous large discrepancy for J/psi and Upsilon polarization between theoretical predication and experimental measurement, and suggests that the next important step is to calculate the NLO corrections to hadronproduction of color octet state J/psi^(8) and Upsilon^(8). Our calculations are performed in two ways, namely we do and do not analytically sum over the polarizations, and then check them with each other.

hep-ph↗

arXiv2008

QCD corrections to double J/ψproduction in e+e- annihilation at \sqrt{s}=10.6 GeV

Next-to-Leading-Order(NLO) QCD corrections to double J/psi production in e^+e^- annihilation at sqrt{s}=10.6 GeV are calculated. We find that they greatly decrease the cross section, with a K factor (NLO/LO) ranging from -0.31 to 0.25 depending on the renormalization scale. Although the renormalization scale dependence indicates a large uncertainty, when combined with the NLO QCD corrections to J/psi + eta_c production, it can explain why the double J/psi$ production could not be found at B factories while the J/psi + eta_c production could, despite the fact that cross section of the former is larger than that of the latter at LO by a factor of 1.8.

hep-ph↗

arXiv2008

QCD corrections to J/psi plus eta_c production in e+e- annihilation at sqrt{s}=10.6 GeV

Next-to-Leading-Order(NLO) QCD corrections to J/jpsi plus eta_c production in e+e- annihilation at sqrt{s}=10.6 GeV is calculated in this paper, and an analytic result is obtained. By choosing proper physical parameters, a K factor (ratio of NLO to LO) of about 2, which is in agreement with the result in Ref.\cite{Zhang:2005ch}, is obtained. Our results show that the Next-Next-to-Leading-Order(NNLO) corrections might be quite large. The plot of the K-factor vs the center-of-mass energy sqrt{s} shows that it is more difficult to obtain a convergent result from the perturbative QCD without resummation of ln(s/m_c) terms as the sqrt{s} becomes larger.

hep-ph↗

arXiv2008

QCD corrections to J/psi polarization of hadronproduction at Tevatron and LHC

The next to leading order (NLO) QCD corrections to J/psi polarization of hadronproduction at Tevatron and LHC are calculated. The results show that the J/psi polarization is extremely changed from more transversal polarization at leading order (LO) into more longitudinal polarization at NLO. Although it gives more longitudinal polarization than the recent experimental result on the J/psi polarization at Tevatron. It sheds light on the solution to the large discrepancy of J/psi polarization between theoretical predication and experimental measurement, and suggests that the next important step is to calculate the NLO correction for color octet state J/psi^{(8)} hadronproduction. Our calculations are performed in two ways where the polarizations are summed analytically or not, and they are checked with each other. It also gives a K factor for total cross section (ratio of NLO to LO) of about 2 and shows that the NLO corrections boost the J/psi production for about 2 order of magnitude in high transverse momentum p_t region of J/psi, which confirms the calculation by Campbell, Maltoni and Tramontano.

hep-ph↗

arXiv2007

Production of $B_c$ or $\bar{B}_c$ meson and its excited states via $\bar{t}$-quark or $t$-quark decays

The production of $(b\bar{c})$-quarkonium ($\bar{B}_c$ meson and its excited states) or $(c\bar{b})$-quarkonium ($B_c$ meson and its excited states) via top quark $t$ or top anti-quark $\bar{t}$ decays, $t\to (b\bar{c})+c+W^+$ or $\bar{t}\to (c\bar{b})+\bar{c}+W^-$, respectively is studied within the framework of NRQCD. In addition to the production of the two color-singlet $S$-wave states $|(b\bar{c})(^1S_0)_{\bf 1}>$ or $|(c\bar{b})(^1S_0)_{\bf 1}>$ and $|(b\bar{c})(^3S_1)_{\bf 1}>$ or $|(c\bar{b})(^3S_1)_{\bf 1}>$, the production of the $P$-wave excited $(b\bar{c})$ or $(c\bar{b})$ states, i.e. the four color-singlet $P$-wave states $|(b\bar{c})(^1P_1)_{\bf 1}>$ or $|(c\bar{b})(^1P_1)_{\bf 1}>$, and $(b\bar{c})(^3P_J)_{\bf 1}>$ or $(c\bar{b})(^3P_J)_{\bf 1}>$ (with $J=(1,2,3)$), is also studied. According to the velocity scaling rule of NRQCD, for the production of $P$-wave excited states the contributions from the two color-octet components $|(b\bar{c})(^1S_0)_{\bf 8}>$ or $|(c\bar{b})(^1S_0)_{\bf 8}>$ and $|(b\bar{c})(^3S_1)_{\bf 8}>$ or $|(c\bar{b})(^3S_1)_{\bf 8}>$ are also taken into account. We quantitatively discuss the possibility and the advantages in experimental studies of $B_c$ or $\bar{B}_c$ meson and its excited states via the indirect production at LHC in high luminosity runs and at LHC possible upgraded versions such as SLHC, DLHC, TLHC etc. in future.

hep-ph↗

arXiv2007

GENXICC: A Generator for Hadronic Production of the Double Heavy Baryons $Ξ_{cc}$, $Ξ_{bc}$ and $Ξ_{bb}$

We write down a generator program for the hadronic production of the double-heavy baryons $Ξ_{cc}$, $Ξ_{bc}$ and $Ξ_{bb}$ according to relevant publications. We name it as GENXICC and we test it by comparing its numerical results with those in references. It is written in a PYTHIA-compatible format and it can be easily implemented into PYTHIA. GENXICC is also written in modularization manner, with {\bf make}, a GNU C compiler, one may apply the generator to various situations or experimental environments very conveniently.

hep-ph↗

arXiv2006

FDCSUSYDecay: A MSSM Decay package

FDCSUSYDecay is a FORTRAN program package generated by FDC (Feynman Diagram Calculation) system fully automatically. It is dedicated to calculate at tree-level all the possible 2-body decays of SUSY and Higgs particles in the Minimal Supersymmetric extension of the Standard Model (MSSM). The format of its output files complies with SUSY Les Houches Accord and can be easily imported by other packages.

hep-ph↗

arXiv2006

Detecting the ambient neutralino dark matter particles at accelerator

In this work, we present a new strategy to investigate the possibility of direct detection of the ambient neutralino matter at accelerator. We calculate the cross sections for both elastic and inelastic scattering processes of the dark matter particles with the beam particles at $e^+e^-$ and hadron colliders.

hep-ph↗

arXiv2006

An Upgraded Version of the Generator BCVEGPY2.0 for Hadronic Production of $B_c$ Meson and Its Excited States

An upgraded version of the package [BCVEGPY2.0: Chao-Hsi Chang, Jian-Xiong Wang and Xing-Gang Wu, Comput. Phys. Commun. {\bf 174} (2006) 241-251] is presented, which works under LINUX system and is named as BCVEGPY2.1. Using this version with a GNU C compiler, users may simulate the $B_c$-events in various experimental environments very conveniently. It has been rearranged for better modularity and code reusability (less dependency among various modules) than BCVEGPY2.0 has. Furthermore, in the upgraded version a special and convenient executable-file {\bf run} as default is available according to one's wish, i.e., the file is obtained in the way that the GNU command {\bf make} compiles the codes requested by precise purpose with the help of a master {\bf makefile} in the main code directory. Finally, this paper may also be considered as an erratum of the original BCVEGPY2.0, i.e., here the errors (typo mainly) in BCVEGPY2.0 have been corrected.

hep-ph↗

arXiv2006

Estimate of the Hadronic Production of the Doubly Charmed Baryon $Ξ_{cc}$ under GM-VFN Scheme

Hadronic production of the doubly charmed baryon $Ξ_{cc}$ ($Ξ^{++}_{cc}$ and $Ξ^{+}_{cc}$) is investigated under the general-mass variable-flavor-number (GM-VFN) scheme. The gluon-gluon fusion mechanism and the intrinsic charm mechanisms, i.e. via the sub-processes $g+g\to(cc)[^3S_1]_{\bar 3}+\bar{c}+\bar{c}$, $g+g\to(cc)[^1S_0]_6+\bar{c}+\bar{c}$; $g+c\to (cc)[^3S_1]_{\bar 3}+\bar{c}$, $g+c\to (cc)[^1S_0]_6+\bar{c}$ and $c+c\to (cc)[^3S_1]_{\bar 3}+g$, $c+c\to (cc)[^1S_0]_6+g$, are taken into account in the investigation, where $(cc)[^3S_1]_{\bar 3}$ (in color {\bf $\bar 3$}) and $(cc)[^1S_0]_6$ (in color {\bf 6}) are two possible $S$-wave configurations of the doubly charmed diquark pair $(cc)$ inside the baryon $Ξ_{cc}$. Numerical results for the production at hadornic colliders LHC and TEVATRON show that both the contributions from the doubly charmed diquark pairs $(cc)[^1S_0]_6$ and $(cc)[^3S_1]_{\bar 3}$ are sizable with the assumption that the two NRQCD matrix elements are equal, and the total contributions from the `intrinsic' charm mechanisms are bigger than those of the gluon-gluon fusion mechanism. For the production in the region of small transverse-momentum $p_t$, the intrinsic mechanisms are dominant over the gluon-gluon fusion mechanism and they can raise the theoretical prediction of the $Ξ_{cc}$ by almost one order.

hep-ph↗

arXiv2005

Hadronic Production of $B_c(B^*_c)$ Meson Induced by the Heavy Quarks inside the Collision Hadrons

In general-mass variable-flavor-number (GM-VFN) scheme, the `heavy quark mechanisms' of $B_c(B_c^*)$ meson hadroproduction via the sub-processes $g+c\to B_c(B_c^*)+...$ and $g+\bar{b}\to B_c(B_c^*)+...$ are investigated. In the scheme, possible double counting from these mechanisms and the `light mechanisms' (the gluon-gluon fusion and quark-antiquark annihilation mechanisms) is subtracted properly. The numerical results show that the transverse momentum, $p_t$, distribution of the produced $B_c(B_c^*)$ from the `intrinsic heavy quark mechanisms' (i.e. the heavy quark mechanisms in which the double counting components have been subtracted accordingly) declines faster with the increment of the $p_t$ than that from the `light mechanisms', and only in small $p_t$ region ($p_t\lesssim 7.0$ GeV) the `intrinsic heavy quark mechanisms' themselves may make remarkable contributions. The combined contributions from the `intrinsic heavy quark mechanisms' and the `light mechanisms' to the production are compared with that obtained by the most calculations in literature, which in some sense are within the fixed flavor number (FFN) scheme at leading order, and we find that the production by virtue of the GM-VFN scheme is more or less the same as the one in literature, except in the small $p_t$ region.

hep-ph↗

arXiv2005

BCVEGPY2.0: A upgrade version of the generator BCVEGPY with an addendum about hadroproduction of the $P$-wave $B_c$ states

The generator BCVEGPY is upgraded by adding the hadroproduction of the $P$-wave excited $B_c$ states (denoted by $B_{cJ,L=1}^*$ or by $h_{B_c}$ and $χ_{B_c}$) and by improving some features of the original one as well. We denote it as BCVEGPY2.0. The $P$-wave production is also calculated by taking only the dominant gluon-gluon fusion mechanism (with the subprocess $gg\to B_{cJ,L=1}^*+\bar{c}+b$ being dominated) into account as that for $S$-wave. In order to make the addendum piece of the upgraded generator as compact as possible so as to increase its efficiency, we manipulate the amplitude as compact as possible with FDC (a software for generating Feynman diagrams and the algebra amplitudes, and for manipulating algebra formulae analytically etc) and certain simplification techniques. The correctness of the program is tested by checking the gauge invariance of the amplitude and by comparing the numerical results with the existent ones in the literature carefully.

hep-ph↗