Neutrino astronomy and massive long-lived particles from the big bang

We consider the neutrino flux from the decay of long-lived big-bang particles. The red-shift z_tr at which the neutrino transparency of the universe sets in is calculated as a function of neutrino energy: z_tr 1 × 10⁵ for TeV neutrinos and z_tr 3 × 10⁶ for 10 MeV neutrinos. One might expect the production of detectable neutrino flux at z z_tr, but, as demonstrated in this paper, the various upper limits, most notably due to nucleosynthesis and diffuse X- and gamma-rays, preclude this possibility. Unless the particle decay is strongly dominated by the pure neutrino channel, observable neutrino flux can be produced only at the current epoch, corresponding to red-shift z ≈ 0. For the thermal relics which annihilate through the gauge bosons of SU(3)×SU(2)×U(1) group, the neutrino flux can be marginally detectable at 0.1 < E_v < 10 TeV. As an example of non-thermal relics we consider gravitinos. If gravitinos are the lightest supersymmetric particles (LSP) they can produce the detectable neutrino flux in the form of a neutrino line with energy , where M_G is the gravitino mass. The flux strongly depends on the mechanisms of R-parity violation. It is shown that heavy gravitinos (M_G 100 GeV) can make up the dark matter in the universe.     

ON THE NEUTRINO MASS AND THE HIDDEPI MASS IN CELESTIAL BODIES

We continually use the phenomenological of the galaxy with two constituents (v+B) as in a previous paper ^[1] and uniformly handle S galaxy, E galaxy, etc. through the normalization method. At the same time, we extend this model from degenerate condition to isoentropic condition and from low temperature to high temperature. Thus, on a much more perfect foundation it is indirectly verified that the massive neutrino can account for the missing mass hidden in different celestial scales between galaxy and galactic cluster, but it can not rule out the possibiilty that there are some new massive fermions which are lighter than neutrino. Besides, in this paper we handle 21 samples of Sc galaxy yet, and obtain the average upper limit (15 eV.) of m_v. Because the spherically symmetric model is insufficient for calculation of m_v, we will progres sively research the non-spherically symmetric model, in another paper.     

ON THE NEUTRINO HALO OF GALAXIES OR GALAXIES CLUSTER AND ITS RESTRICTION ON NEUTRINO MASS

We present a simple and crude model of galaxies consisting of baryons and neutrinos with spherical symmetry. The baryon matter is rotatinq. in the central region of the galaxy as a nucleus. If the rotational curve of the heavy matter is known from the observational data, then the gravitational potential, and therefore the density distribution in this region, can also be obtained. This enables us to estimate the mass and the radius of the neutrino halo. Furthermore, the condition on the interface of the nucleus-halo will set an upper bound on neutrino mass. If the corresponding parameters duoted in Ref.[10] are adopted, then a value of ≤20eV. for the neutrino mass is obtained. By choosing m_v=15eV and a parameter in the rotational curve n=4, one can deduce that neutrino halo radius is about four times the heavy matter radius, and the total mass of neutrinos is about 14 times that of baryons. It seems, that these results are not in contradiction with the observations on the missing mass of the galaxies^[6].     

Bi-large Neutrino Mixing See-Saw Mass Matrix with Texture Zeros and Leptogenesis

We study constraints on neutrino properties for a class of bi-large mixing See-Saw mass matrices with texture zeros and with the related Dirac neutrino mass matrix to be proportional to a diagonal matrix of the form diag(ε,1,1). Texture zeros may occur in the light (class a) or in the heavy (class b) neutrino mass matrices. Each of these two classes has 5 different forms which can produce non-trivial three generation mixing with at least one texture zero. We find that two types of texture zero mass matrices in both class a and class b can be consistent with present data on neutrino masses and mixing. None of the neutrinos can have zero masses and the lightest of the light neutrinos has a mass larger than about 0.046 eV for class a and 0.0027 eV for class b. In these models although the CKM CP violating phase vanishes, the non-zero Majorana phases can exist and can play an important role in producing the observed baryon asymmetry in our universe through leptogenesis mechanism. The requirement of producing the observed baryon asymmetry can further distinguish different models and also restrict the See-Saw scale to be in the range of 10¹²～10¹⁵ GeV. We also discuss RG effects on V₁₃.     

ON THE HYDROGEN MOLECULAR CORRECTION TO THE TRITON β-SPECTRUM AND THE MEASUREMENT OF THE NEUTRINO MASS

By using a highly accurate variational wave function with 50 parameters for hydrogen molecule^[4] and the wave function of HeH⁺ used by Wolniewicz with 64 parameters^[5], the behavior of the β-spectrum of H-T→ HeH⁺+β^-+νe is discussed. The spectral shape thus obtained deviates remarkably from the β-spectrum of an atomic triton, and hence is different from the for mula used by Lyubimov et al. in determining the neutrino mass. This means that the "atomic approximation" is invalid in describing the molecular β-spectrum of valine, and the conclusion about the value of neutrino mass based upon the analysis of β -spectrum of valine also cannot be regarded as a reliable one. Therefore, in order to obtain ari accurate value of neutrino mass from the β-spectral shape, it is important to investigate the structure of the radioactive source, from which the corection has arisen.     

COMMENTS ON THE NEW NEUTRINO "BALANCE": A DISCUSSION OF THE FEASIBILITY OF USING THE ELECTRON CAPTURE PROCESS IN158Tb, 157Tb FOR NEUTRINO MASS DETERMINATION

It is found that owing to the large energy difference in K-and L-shells of the daughter atom, ¹⁵⁸Tb is not the best candidate for neutrino "balance". Instead, ^l57Tb can offer a better chance for. neutrino mass determination if the Q-value 55 far obtained is verified. If it is so,then the relevant atomic calculation with high precision is very necessary. It is shown that to include the radiative correction in the Hartree-Fock calculation is very important for such atoms as ¹⁵⁷Gd and ¹⁵⁷Tb.     

A MODEL OF NEUTRINO STELLAR SYSTEM AND THE UPPER BOUND OF NEUTRINO MASS OBTAINED FROM THE RCTATION CURVES OF SOME GALAXIES

We discuss in this paper a stellar model of degenerate massive neutrinos with a core made of heavy matter. Dimension of the core is much smaller than the scale of neutrino star. The Oppenheimer-Volkoff equation is solved for such a system. Our calculation shows that under certain conditions, this neutrino halo will resemble a pure neutrino star. We have further obtained insides the neutrino star (or halo) the rdtation curve and the gravitational red shifts. It is interesting to note that the relative rotation velocity v(r)EV(r)/V(R) (R is the radius of the neutrino star) depends only on the relative coordinate ξ=r/R in the nonrelativistic cases. Therefore, all nonrelativistically degenerate neutrino systems will have a universa1 relative rotation curve(v versus ξ). Within the accuracy of numeri calcalculation, we have also obtained a useful relation connecting the maximum velocity V_m and the corresponding coordinate R_m as V_mR_m2=0.231. By comparing this relation with the observed rotation data at large distances for some galaxies, we have obtained an upper bound for neutrino mass of about 6-9eV.     

Supersymmetry for Fermion Masses

It is proposed that supersymmetry （SUSY） may be used to understand fermion mass hierarchies. A family symmetry ZSL is introduced, which is the cyclic symmetry among the three generation SU（2） doublets. SUSY breaks at a high energy scale - 10^11 GeV. The electroweak energy scale- 100 GeV is unnaturally small No additional global symmetry, like the R-parlty, is imposed. The Yukawa couplings and R-parity violating couplings all take their natural values, which are О（10^0 -10^-2）. Under the family symmetry, only the third generation charged ferrnions get their masses. This family symmetry is broken in the soft SUSY breaking terms, which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the r mass is from the Higgs vacuum expectation value （VEV） and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both ZZL and SUSY hreaking. The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. │Ve3│, which is for Ve-Vr mixing, is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains me/ms, ms/me, md 〉 mu and so on. Other aspects of the model are discussed.     

Reconciling cold dark matter with COBE/IRAS plus solar and atmospheric neutrino data

We present a model where an unstable MeV Majorana tau neutrino can naturally reconcile the cold dark matter model (CDM) with cosmological observations of large and small scale density fluctuations and, simultaneously, with data on solar and atmospheric neutrinos. The solar neutrino deficit is explained through long wavelength, so-called just-so oscillations involving conversions of ν_e into both ν_μ and a sterile species ν_s , while atmospheric neutrino data are explained through ν_μ to ν_e conversions. Future long baseline neutrino oscillation experiments, as well as some reactor experiments will test this hypothesis. The model is based on the spontaneous violation of a global lepton number symmetry at the weak scale. This symmetry plays a key role in generating the cosmologically required decay of the ν_τ with lifetime τ_ντ ≈ 10²-10⁴ seconds, as well as the masses and oscillations of the three light neutrinos ν_e, ν_μ and ν_s required in order to account for solar and atmospheric neutrino data. It also leads to the invisibly decaying Higgs signature that can be searched at LEP and future particle colliders.     

The Mass Bounds on Exotic Particles in an SU(3)L×U(1)X Model

We study an SU(3)_L×U(1)_X electroweak model. By requiring M²_Z1-M²_W/cos²θ_W to be less than experimental value we obtain a lower bound on Z' boson mass, M_Z' >600 GeV. The relation between M_Z' and M_U (M_V) then gives a lower bound on M_U (M_V):M_U (M_V)>490 GeV. From the constraint sin² θ_W(M_Z')<0.3, the upper bounds on M_Z' and M_U (M_V) are computed to be M_Z'<5.8×10⁴ TeV and M_U (M_V)<4.6×10⁴ TeV. We estimate further the K_L-K_S mass difference due to Z' exchange and try to use the result to obtain stronger lower bounds. On cosmological grounds we find that M_N<390 eV for T_f=2.3 GeV and M_N<740 eV for T_f=300 GeV.     

Majorana neutrinos as the dark matters in the cold plus hot dark matter model

A simple model of the Majorana neutrino with the see-saw mechanism is studied, assuming that two light neutrinos are the hot dark matter each with a mass of 2.4 eV in the cold plus hot dark matter model of cosmology. We find that the heavy neutrino, which is the see-saw partner with the remaining one light neutrino, can be the cold dark matter, if the light neutrino is exactly massless. This cold dark matter neutrino is allowed to have a mass in the wide range from 5.9 × 10² eV to 2.2 × 10⁷ eV.     

The Two-Nucleon Mechanism for the Neutrinoless Double Beta Decay and the BCS Nuclear Wave Function

A method of using the Bardeen-Cooper-Schrieffer (BCS) nuclear wave function to treat the two-nucleon mechanism for neutiinoless double beta decay process 0⁺ → 0⁺ is proposed.The neutrinoless decay mode and the neutrinoless decay accompanied by a Majoron emission mode of ⁸²Se are studikd. Our cdculated results show that to reproduce the experimental value of γ^(ov) > 1.8 × 10²² yr for neutrinoless double beta decai of ⁸²Se the Majorana neutrino mass m_v < 6.2 eV and the mixing parameter of right-handed current η < 7.0 × 10^-6 In the emission with a Majoron mode the effective Majoron coupling to neutrino is deduced from the experimental value of γ^(ov,H) > 4.4 × 10²⁰ yr for ⁸²Se with the result H0> < 6.2 × 10^-4.     

Limits of neutrino stability from the γ-ray flux measured in coincidence with neutrinos from SN 1987a

Limits for the neutrino decay ν_H→ν_L+γ, where ν_H and ν_L are assumed to be massive neutrinos withm_VH>m_VL, are presented using data from the Solar Maximum Mission satellite taken in coincidence with the detected neutrino burst from SN 1987A. These limits are essentially independent of supernova models and are and τ/m_νμ,τ>3.3×10¹⁴ s/eV for a thermal spectrum at a temperature .     

Transient creep of YBa2Cu3O7−x superconductor

Rapid changes of oxygen partial pressure (P_O2) between 10³ and 2.1×10⁴ Pa have been carried out during steady-state plastic deformation of polycrystalline YBa₂Cu₃O_7−x (YBCO) at temperatures between 825 and 900°C. Transient creep was observed after such P_O2 changes. The analysis of these creep transients allowed the determination of the chemical diffusion coefficient for reequilibration, which is identical to that found from thermogravimetry and electrical conductivity experiments for oxygen vacancies.     

Study on υμ, υγ, Decays and CP Non-Invariance at Early Epoch of the Universe

We study the υ_μ and υ_γ decays in the early epoch of the universe. If m_υγ > 2m_e, there would be a CP asymmetry between υ_γ→e⁺+e^-+υ_e and υ_γ→e⁺+ e^-+ υ_e. The resultant CP non-invariance is a function of temperature and density and can reach l0^-7 for a reasonable temperature range, but it is noticed that if m_υγ > 2υ_μ～200 MeV, the CP non-invariance can be much larger.     

Ω＋Ω→（ΩΩ）Jπ=0＋＋X Cross section Calculation

The cross sections of Ω+Ω→(ΩΩ)_J^π=0⁺+X are studied by using an effective Hamiltonian method. The results are σ_{Ω+Ω→(ΩΩ)0⁺+γ}=0.03～0.16×10^-29 cm² for p_Ω=100～400 MeV, and the cross sections of η production are about 10^-28 cm² for p_Ω > 880 MeV.     

NEUTRINO MAGNETIC MOMENT IN SUPERSTRING INSPIRED MODELS

In superstring E₆ models right-handed leptonic currents can arise from the mixing between the ordinary leptons and tha exotic leptons. Contributions to the neutrino magnetic moment due to this new interaction are examined. Although the result appears to be directly proportional to the heavy exotic charged lepton mass, it is shown, however, that the mixing is proportional to the ratio of the neutrino mass and the exotic lepton mass. The combination of these two factors yields a result which is of the order of that given by the SU(2)_LxU(1)_Y model.     

快重离子辐照对MoS2热导率的影响研究

利用0.97 GeV的209Bi离子辐照二硫化钼（MoS₂）晶体,辐照注量范围为1×1010～1×1012 ions/cm2,结合原子力显微镜（AFM）观测和Raman光谱分析研究了快重离子辐照对MoS₂热导率的影响。实验结果显示,快重离子辐照在MoS₂中产生了潜径迹,较高激光功率下的Raman测试使样品局部温度升高,导致E_1/2g和A_1g峰随注量增加向低波数方向移动,且峰形展宽。引入了通过改变激光功率测量Raman光谱得到MoS₂热导率的计算方法,获得了不同辐照注量下MoS₂的热导率的定量分析结果,随注量增加,热导率不断降低,从未辐照样品的563 W/mK下降到1×1012 ions/cm2辐照时的132 W/mK。Molybdenum disulphide (MoS₂) was irradiated by 0.97 GeV 209Bi ions with the fluence of 1×1010 to 1×1012 ions/cm2. The irradiation effect on the thermal conductivity of MoS₂ was analyzed by atomic force microscope (AFM) and Raman spectroscopy. The experimental results show that hillock-like latent tracks are observed on irradiated MoS₂ by AFM. The measurement of MoS₂ by Raman spectrometer with high laser power results in the increase of local temperature of MoS₂, which cause the downshift of peaks position and broadening of E_1/2g and A_1g peak. Furthermore, according to Raman spectra measured at different laser power, thermal conductivity of MoS₂ before and after irradiation was calculated, which show that the thermal conductivity of MoS₂ decreases with increasing fluence, from 563 to 132 W/mK for pristine and 1×1012 ions/cm2 irradiated MoS₂, respectively.     

NEW AUTOIONIZING STATES NEAR THE FIRST IONIZATION LIMIT OF RARE EARTH ELEMENT Dy

This paper describes the investigation of autoionizing states near the first ionization limit of rare-earth element Dy. The 62, 51, 97 and 25 new autoionizing states resulting from the states of 4f¹⁰(⁵I₈)6s6p(³P⁰₂)³I⁰₇, 4f⁹ (⁶H⁰)5d²(³F)(⁸G⁰)6s⁹G⁰₇, 4f⁹(⁶F⁰)5d6s^{2 7}H⁰₇ and 4f⁹5d6s^{2 7}K⁰₇, respectively, were found by using a laser resonance ionization time-of-flight mass spectrometer (LRI-TOFMS), The photoionization efficiencies for different channels were compared with each other. In addition, the Shore-Fano parameters of autoionizing states were determined by a nonlinear fitting program.     

ON THE REACTION MECHANISM AND THE SELECTION RULE IN THE DOUBLE CHARGE EXCHANGE REACTION OF PIONS ON NUCLEI (DCX)-A STUDY OF THE CONNECTION BETWEEN THE 2β-DECAY AND DCX ON jP=O+ NUCLEI

It is shown that in the pion induced double charge exchange reaction on J^p=O⁺→O⁺ nuclei,there exists a possible new reaction mechanism π⁺(Δ⁰,Δ⁺⁺)π^- or π⁺(Δ^-,Δ⁺)π^- in so-called single step process,while that old speculative mechanism π⁺(N,Δ)π^- or π⁺(N,Δ)π^- is firbidden by a well-known selection rule which has been indicated in the theory of the nuclear 2β-decay.