122736538
Dark matter, LFV and neutrino magnetic moment in the radiative seesaw model with fermion triplet
In this paper we work in the framework of a radiative seesaw model with triplet fermion Σ. Due to the Z2 discrete flavor symmetry, the lightest neutral component of Σ is stable and thus can be a dark matter candidate. Its mass can be solely determined by the dark matter relic abundance, which is bout 2.594 TeV. It can still constitute 30% of the dark matter when considering constraints from dark matter indirect detection experiments. The model also predict a dark matter-nucleus scattering cross-section that would be accessible with future dark matter direct detection searches. We further investigate constraints on the parameter space of the model from the lepton-flavor-violating processes and neutrino transition magnetic moments, induced by the Yukawa interaction of the Σ with the left-handed lepton doublets.
119236167
Correlative signatures of heavy Majorana neutrinos and doubly-charged Higgs bosons at the Large Hadron Collider
Abstract We explore an intriguing possibility to test the type-II seesaw mechanism of neutrino mass generation at the Large Hadron Collider (LHC). We show that the lepton-number-violating signatures of heavy Majorana neutrinos N i (for i = 1 , 2 , 3 ) and doubly-charged Higgs bosons H ± ± can be closely correlated with each other in a class of TeV-scale type-II seesaw models. Taking the minimal version of such models for example, we calculate the cross sections of p p → l α ± l β ± X processes mediated separately by N 1 and H ± ± , and illustrate their nontrivial correlation at the LHC.
118662547
Compromise between neutrino masses and collider signatures in the type-II seesaw model
A natural extension of the standard $\mathrm{SU}(2{)}_{\mathrm{L}}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1{)}_{\mathrm{Y}}$ gauge model to accommodate massive neutrinos is to introduce one Higgs triplet and three right-handed Majorana neutrinos, leading to a $6\ifmmode\times\else\texttimes\fi{}6$ neutrino mass matrix which contains three $3\ifmmode\times\else\texttimes\fi{}3$ submatrices, ${M}_{\mathrm{L}}$, ${M}_{\mathrm{D}}$ and ${M}_{\mathrm{R}}$. We show that three light Majorana neutrinos (i.e., the mass eigenstates of ${\ensuremath{\nu}}_{e}$, ${\ensuremath{\nu}}_{\ensuremath{\mu}}$, and ${\ensuremath{\nu}}_{\ensuremath{\tau}}$) are exactly massless in this model, if and only if ${M}_{\mathrm{L}}={M}_{\mathrm{D}}{M}_{\mathrm{R}}^{\ensuremath{-}1}{M}_{\mathrm{D}}^{T}$ exactly holds. This no-go theorem implies that small but nonvanishing neutrino masses may result from a significant but incomplete cancellation between ${M}_{\mathrm{L}}$ and ${M}_{\mathrm{D}}{M}_{\mathrm{R}}^{\ensuremath{-}1}{M}_{\mathrm{D}}^{T}$ terms in the Type-II seesaw formula, provided three right-handed Majorana neutrinos are of $\mathcal{O}(1)\text{ }\text{ }\mathrm{TeV}$ and experimentally detectable at the LHC. We propose three simple Type-II seesaw scenarios with the ${A}_{4}\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1{)}_{\mathrm{X}}$ flavor symmetry and its explicit breaking 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 $3\ifmmode\times\else\texttimes\fi{}3$ neutrino mixing matrix in the future long-baseline neutrino oscillation experiments.
6575970
Higgs Vacuum Stability, Neutrino Mass, and Dark Matter
Recent results from ATLAS and CMS point to a narrow range for the Higgs mass: M_H∈(124,126)  GeV. Given this range, a case may be made for new physics beyond the Standard Model (SM) because of the resultant vacuum stability problem, i.e., the SM Higgs quartic coupling may run to negative values at a scale below the Planck scale. We study representative minimal extensions of the SM that can keep the SM Higgs vacuum stable to the Planck scale by introducing new scalar or fermion interactions at the TeV scale while solving other phenomenological problems. In particular, we consider the type-II seesaw model, which is introduced to explain the nonzero Majorana masses of the active neutrinos. Similarly, we observe that if the stability of the SM Higgs vacuum is ensured by the running of the gauge sector couplings, then one may require a series of new electroweak multiplets, the neutral component of which can be a cold dark matter candidate. Stability may also point to a new U(1) gauge symmetry, in which the SM Higgs carries a nonzero charge.
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.
118481043
The D0 Dimuon Charge Asymmetry and Baryon Asymmetry of the Universe
The D0 collaboration has reported a 3.2 \sigma deviation from the Standard Model (SM) prediction in the like-sign dimuon charge asymmetry. New physics beyond the SM in B_s - \bar B_s mixing is needed to explain the data. In this paper, we investigate the possible extension of the SM with one generation color-triplet charged scalar as well as three generation Majorana fermions. We study the implications of the model on the D0's dimuon charge asymmetry as well as matter anti-matter asymmetry of the Universe.
119437903
Charge neutrality effects on two-flavor color superconductivity
Four different phases of the two-flavor quark system, i.e., the normal quark matter and color superconducting phases with and without the charge neutrality condition, are investigated in the framework of the SU(2) Nambu-Jona-Lasinio model. It is found that the color superconducting phase without charge neutrality has the lowest thermodynamic potential, and the charge neutral systems have higher thermodynamic potentials. However, the BCS pairing always lowers the system's thermodynamic potential, i.e., for both the charged and charge neutral systems, the superconducting phases always have lower thermodynamic potentials. Compared with the BCS gap Delta(0) for the color superconducting phase without charge neutrality, the BCS gap Delta in the charge neutral color superconducting phase has been largely reduced. When the thermodynamic potential for the charge neutral color superconducting phase equals that in the neutral normal quark matter, the diquark condensate disappears.
123931554
THE EFFECT OF SECONDARY COLLISIONS IN THE RAPIDITY DISTRIBUTION IN RELATIVISTIC HEAVY-ION COLLISIONS
Based on the participant model the effect of secondary collisions in relativistic heavy ion collisions is analyzed by introducing additional contributions in fragmentation regions. The rapidity distributions of n of NA35 and WA80 groups are well reproduced. Special improvement is shown in the target fragmentation region.
124347725
THE RELATION BETWEEN K+/PI+ RATIO AND SECONDARY COLLISIONS IN ULTRA-RELATIVISTIC HEAVY-ION COLLISIONS
Based on the concept of the formation time, the contribution of secondary collisions to the change of the K+/π+ ratio in ultra-relativistic heavy ion collisions is calculated. The result shows that the effect of secondary collisions in the target nucleus is not enough to explain the observed change of the K+/π+ ratio.
18902857
$\pi - \pi$ Scattering Lengths and Chiral Condensate in NJL Model
Within the general framework of SU(2) Nambu-Jona-Lasinio model beyond mean-field approximation, the S-wave $\pi - \pi$ scattering lengths $a_0^0$ and $a_0^2$ are calculated. The numerical results are in agreement with that analyzed from recent experiment $\pi N \to \pi \pi N$ data by using Chew-Low-Goebel technique, and the corresponding chiral condensate $ $ is around $-(250 {\rm MeV})^3$, which is close to the ones obtained from lattice and sum rules.
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.