18431189
Nuclear Effects on Charmonium Production
$J/\psi$ and $\psi'$ production cross sections in fixed-target experiment is calculated, considering the contributions from both color-singlet and color-octet mechanisms.The results are applied to the investigations of the $J/\psi$ suppression and the $\psi'/\psi$ ratio problems in p-A collisions. The results agree with the experimental data as the $(c \bar c)-$nucleon absorption cross sections $\sigma_{abs}^8\simeq 10mb $ for $(c \bar c)_8$ and $\sigma_{abs}^1\simeq 0mb $ for $(c \bar c)_1$. The model is further used to investigate A-A collisions when comover absorption mechanism is also considered. It is found that the observed experiment data of $J/\psi$ and $\psi'/\psi$ ratio in S-U collisions and Pb-Pb collisions can not be explained consistently within this model. The possibility of QGP formation in S-U and Pb-Pb collisions is also discussed.
6699997
THERMAL RELAXATION TIME IN CHEMICALLY NON-EQUILIBRATED QUARK-GLUON PLASMA
The definition of thermal relaxation time is extended to chemically non-equilibrated quark-gluon plasma and the chemical non-equilibrated thermal relaxation times for partons are calculated using the non-equilibrium Debye mass as the infrared regulator. The dependence of the thermal relaxation time on the fugacity is given and the influence of the chemical non-equilibration is discussed. We find that there are threshold fugacities lambda(g)* and lambda(q)* for gluons and quarks. for lambda(g) lambda(g)*(lambda(q) > lambda(q)*), ratios are almost 1. It is shown that there is also the two-stage equilibration in a chemically non-equilibrated plasma. We also discussed the effect of using the non-equilibrium Debye mass as the infrared cutoff. (C) 1998 Published by Elsevier Science B.V.
123725926
Quark propagator with a quark mass term in the color-superconducting phase
118203227
Meson effects on the chiral symmetry breaking and restoration
Based on the self-consistent chiral symmetric scheme of the SU(2) Nambu-Jona-Lasinio model, the meson effects have been investigated on the chiral symmetry breaking vacuum and chiral symmetry restoration by exactly calculating the next-to-leading (NLO) order Feynman diagrams in the 1/Nc expansion.
14601338
The mesonic fluctuations and corrections in the chiral symmetry breaking vacuum
Abstract The mesonic quantum fluctuations and their corrections on the chiral condensate and pion polarization function are investigated in the self-consistent scheme of SU(2) Nambu–Jona-Lasinio model by exactly calculating the next-to-leading order (NLO) Feynman diagrams in 1/ N c expansion. While the fluctuations and corrections depend strongly on the meson's three-momentum cut-off Λ M , no chiral symmetry restoration is found since the cancellation between the NLO and the one-quark-loop diagram with quark mass deviated from the mean-field value.
103821996
The effects of gluon shadowing and nuclear absorption on J / psi suppression in h A and A A collisions
118448034
Neutrino Masses, Dark Matter and B-L Symmetry at the LHC
We establish a hybrid seesaw mechanism to explain small neutrino masses and predict cold dark matter candidate in the context of the B − L gauge symmetry extension of the Standard Model. In this model a new scalar doublet and two new fermion singlets are introduced at loop-level beyond the minimal Type I seesaw. The lightest particle inside the loop can be dark matter candidate. We study in detail the constraints from neutrino oscillation data, lepton flavor violating processes and cosmological observation. We also explore the predictions of the decays of the new charged scalars in each spectrum of neutrino masses and show the most optimistic scenarios to distinguish the spectra. We consider the pair production of the stable fermion associated with two observable SM charged leptons at �
124312353
The Hierarchy Problem and Lifshitz Type Quantum Field Theory
We study the Lifshitz type extension of the standard model (SM) at UV, with dynamical critical exponent z=3. One loop radiative corrections to the Higgs mass in such a model is calculated. Our result shows that, the Hierarchy problem, which has initiated many excellent extension of the minimal SM, can be weakened in the z=3 Lifshitz type quantum field theory.
2474648
Neutrino masses and lepton-flavor-violating τ decays in the supersymmetric left-right model
In the supersymmetric left-right model, the light neutrino masses are given by the Type-II seesaw mechanism. A duality property of this mechanism indicates that there exist eight possible Higgs triplet Yukawa couplings which result in the same neutrino mass matrix. In this paper, we work out the one-loop renormalization group equations for the effective neutrino mass matrix in the supersymmetric left-right model. The stability of the Type-II seesaw scenario is briefly discussed. We also study the lepton-flavor-violating processes (tau -> mu gamma and tau -> e gamma) by using the reconstructed Higgs triplet Yukawa couplings.
118352553
The Muon Magnetic Moment in the TeV Scale Seesaw Models
The reported discrepancy of the muon abnormal magnetic moment $a_\mu^{}$ has impacts on the low energy phenomenology. In this paper we calculate the corrections to $a_\mu$ in the standard model extended by the TeV scale seesaw models. We show that the correction induced by the type-I seesaw model is negative and of the order ${\cal O} (10^{-11})$, which can be neglected compared with $a_\mu^{\rm SM}$. The correction induced by the type-II seesaw model, which depends on the mass of the Higgs triplet $m_\Delta$ and the Yukawa coupling $Y_\Delta$, can be of the order ${\cal O}(10^{-10})$ and compensate for the discrepancy between $a_\mu^{\rm SM}$ and $a_{\mu}^{\rm exp}$. The correction induced by the type-III seesaw model is also negative and can be of the order ${\cal O}(10^{-10})$.
119230665
TeV-scale Type-II Seesaw Models and Possible Collider Signatures
A natural extension of the standard model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a 6×6 neutrino mass matrix. We show that three light Majorana neutrinos (i.e., the mass eigenstates of νe, νμ and ντ) are exactly massless, if and only if $M_{L} = M_{\rm D}M^{-1}_{\rm R}M^{T}_{\rm D}$ exactly holds in this seesaw model. We propose three simple Type-II seesaw scenarios with broken A4 × U(1)x flavor symmetry to interpret the observed neutrino mass spectrum and neutrino mixing pattern. Such a TeV-scale neutrino model can be tested in two complementary ways: (1) searching for possible collider signatures of lepton number violation induced by the right-handed Majorana neutrinos and doubly-charged Higgs particles; and (2) searching for possible consequences of unitarity violation of the 3 × 3 neutrino mixing matrix in the future long-baseline neutrino oscillation experiments.