119228671
The flavor-changing single-top quark production in the littlest Higgs model with T parity at the LHC
Abstract The littlest Higgs model with discrete symmetry named “T-parity” (LHT) is an interesting new physics model which does not suffer strong constraints from electroweak precision data. One of the important features of the LHT model is the existence of new source of FC interactions between the SM fermions and the mirror fermions. These FC interactions can make significant loop-level contributions to the couplings tcV , and furthermore enhance the cross sections of the FC single-top quark production processes. In this paper, we study some FC single-top quark production processes, p p → t c ¯ and p p → t V , at the LHC in the LHT model. We find that the cross sections of these processes strongly depend on the mirror quark masses. The processes p p → t c ¯ and p p → t g have large cross sections with heavy mirror quarks. The observation of these FC processes at the LHC is certainly the clue of new physics, and further precise measurements of the cross sections can provide useful information about the free parameters in the LHT model, specially about the mirror quark masses.
119099946
The Flavor-changing bottom and anti-strange quark production in the littlest Higgs model with T parity at the ILC
In the littlest Higgs model with T-parity (LHT) the mirror quarks induce the special flavor structures and some new flavor-changing (FC) couplings which could greatly enhance the production rates of the FC processes. We in this paper study some bottom and anti-strange production processes in the LHT model at the International Linear Collider (ILC), i.e., $e^+e^-\to b\bar{s}$ and $\gamma\gamma\to b\bar{s}$. The results show that the production rates of these processes are sizeable for the favorable values of the parameters. Therefore, it is quite possible to test the LHT model or make some constrains on the relevant parameters of the LHT through the detection of these processes at the ILC.
14268595
Phase transition of finite size quark droplets with isospin chemical potential in the Nambu–Jona-Lasinio model
Making use of the Nambu\char21{}Jona-Lasinio model and the multiple reflection expansion approximation, we study the phase transition of the finite size droplet with $u$ and $d$ quarks. We find that the dynamical masses of $u$, $d$ quarks are different, and the chiral symmetry can be restored at different critical radii for $u$, $d$ quarks. It provides a clue to understanding the effective nucleon mass splitting in nuclear matter. Meanwhile, it shows that the maximal isospin chemical potential at zero temperature is much smaller than the mass of pion in free space.
118036569
Detecting Toppion via a Flavor-Changing Single Top QuarkProduction Process*
In the framework of topcolor-assisted technicolor (TC2) theory, we study a flavor changing single top quarkproduction process pp(pp) →Ⅱ0t → tc(tc) at upgraded Tevatron and LHC. The results show that with the flavor changingcoupling of neutral toppion to top and charm quark, toppion provides a large te-channel resonance effect. The signal ofsingle top production could be detected at LHC. Otherwise, the narrow peak in the invariant mass distribution could beclearly detected both at upgraded Tevatron and LHC. Therefore, such single top production process provides a uniqueway to test TC2 model via the detection of tc-channel neutral toppion contribution.
122968394
Multiscale technicolor and top quark decay
43093269
Rare decays of the top quark in the one generation technicolor model.
The decays [ital t][r arrow][ital cV] ([ital V]=[gamma],[ital g],[ital Z]) and [ital t][r arrow][ital cP][sup 0] induced through loop processes are calculated in the Farhi-Susskind one family technicolor (TC) model. We find that these new contributions can enhance the SM branching fractions by as much as 3--4 orders of magnitude, i.e., [ital B]([ital t][r arrow][ital cg])[similar to]10[sup [minus]6], [ital B]([ital t][r arrow][ital cZ])[similar to]10[sup [minus]7], [ital B]([ital t][r arrow][ital c][gamma])[similar to]10[sup [minus]8], and [ital B]([ital t][r arrow][ital cP][sup 0])[similar to]10[sup [minus]9], for the favorable values of the parameters. It might provide a unique window to detect the virtual effects of pseudo Goldstone bosons in TC theory.
8281927
Heavy quark energy loss in a nuclear medium.
Multiple scattering, modified fragmentation functions, and radiative energy loss of a heavy-quark propagating in a nuclear medium are investigated in perturbative QCD. Because of the quark mass dependence of the gluon formation time, the medium size dependence of heavy-quark energy loss is found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss is also significantly suppressed relative to a light quark due to the suppression of collinear gluon emission by a heavy quark.
76655214
Hadron production in p+p, p+Pb, and Pb+Pb collisions with the HIJING 2.0 model at energies available at the CERN Large Hadron Collider
The Heavy-Ion Jet Interaction Generator (hijing) Monte Carlo model is updated with the latest parton distributions functions and a new set of the parameters in the two-component minijet model that controls the total p+p cross section and the central pseudorapity density. We study hadron spectra and multiplicity distributions using the hijing2.0 model and compare to recent experimental data from p+p collisions at the Large Hadron Collider (LHC) energies. We also give predictions of hadron production in p+p, p+Pb, and Pb+Pb collisions at the full LHC energy.
14560383
Charmonium production from hot hadronic matter
Abstract Charmonium production from D D annihilation in the hadron gas formed in ultra-relativistic heavy-ion collisions is studied. With initial conditions taken from the HIJING parton model, we have estimated the number of J / ψ produced from an expanding hadron gas, using the J / ψ absorption and production cross sections obtained from either an effective Lagrangian or the quark-exchange model. We find that J / ψ production is negligible in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) but may be important at the Large Hadron Collider (LHC), where more charm mesons are produced. Similar results are obtained for ψ ′ production from the hadron gas at RHIC and LHC.
124411042
Baryon Transport Dynamics: From P — P to PB — PB Collisions
Significant baryon stopping and strange hyperon production in heavy nuclear interactions has been recently observed at the CERN SPS [1,2,3,4,5]. The data is significantly under-predicted by models which use diquark-quark (qq − q) hadronic strings for their primary baryon number transport mechanism [6,7] and has thus generated much interest. We therefore study new baryon number transport mechanisms in order to differentiate non-equilibrium multi-particle production dynamics from any new sought after physics. We begin this study by reviewing two new mechanisms as implemented in the VENUS [8] and in a modified version of the dual parton model (DPM) [9] event generators. We then study a third new [10] mechanism, where the baryon number is specifically transferred via gluonic junctions. This mechanism has been implemented in the Monte Carlo event generator, HIJING/B[11], a new version of the HIJING model[12]. W e show that this gluonic mechanism can account for the observed large mid-rapidity valence baryon distribution at the SPS and predicts high baryon densities at RHIC. The highly enhanced hyperon yield and transverse momentum flow observed in PbPb collisions at the SPS can, however, only be partially reproduced by this model.
16228307
Jet and Leading Hadron Production in High-energy Heavy-ion Collisions
Jet tomography has become a powerful tool for the study of properties of dense matter in high-energy heavy-ion collisions. I will discuss recent progresses in the phenomenological study of jet quenching, including momentum, colliding energy and nuclear size dependence of single hadron suppression, modification of dihadron correlations and the soft hadron distribution associated with a quenched jet.