Tau neutrino mass from semileptonic decays

The semileptonic three particle decays of the tau provide determinations of the tau neutrino mass. The shift of the maximal energy of the observable final state particles islinear in the neutrino mass. The endpoint energy of the pion and a partially integrated decay rate in τ → πωv _τ and τ → πρV _τ are sensitive to a neutrino mass smaller than 100 MeV. Thus, the present bound on \(m_{v_\tau } \) can significantly be improved.     

Measurement of the masses and lifetimes of the charmed mesonsD 0,D + andD s +

We present the final results on the measurement of the masses and lifetimes of the mesonsD ⁰,D ⁺ andD _s ⁺ in the NA32 experiment at the CERN SPS, using silicon microstrip detectors and charge-coupled devices for vertex reconstruction. We measure the following lifetimes: \(\tau _{D^0 } = 3.88 \pm _{0.21}^{0.23} \cdot 10^{ - 13} s\) using a sample of 479D°→K ^?π⁺π^?π⁺ and 162D°→K ^?π⁺ decays; \(\tau _{D^ + } = 10.5 \pm _{0.72}^{0.77} \cdot 10^{ - 13} s\) with a sample of 317D ⁺→K ^?π⁺π⁺ decays; \(\tau _{D_s^ + } = 4.69 \pm _{0.86}^{1.02} \cdot 10^{ - 13} s\) with a sample of 54D _s ⁺ →K ⁺ K ^?π⁺ decays. We measure the following masses:m _D ⁰=1864.6±0.3±1.0 MeV,m _D ⁺=1870.0±0.5±1.0 MeV and \(m_{D_s^ + } \) =1967.0±1.0±1.0 MeV.     

Cosmological General Relativity with Scale Factor and Dark Energy

In this paper the four-dimensional (4-D) space-velocity Cosmological General Relativity of Carmeli is developed by a general solution of the Einstein field equations. The Tolman metric is applied in the form 1 $$ ds^2 = g_{\mu \nu} dx^{\mu} dx^{\nu} = \tau^2 dv^2 -e^{\mu} dr^2 - R^2 \left(d{\theta}^2 + \mbox{sin}^2{\theta} d{\phi}^2 \right), $$ where g _μν is the metric tensor. We use comoving coordinates x ^α = (x ⁰, x ¹, x ², x ³) = (τv, r, θ, ?), where τ is the Hubble-Carmeli time constant, v is the universe expansion velocity and r, θ and ? are the spatial coordinates. We assume that μ and R are each functions of the coordinates τv and r. The vacuum mass density ρ _Λ is defined in terms of a cosmological constant Λ, 2 $$ \rho_{\Lambda} \equiv -\frac{ \Lambda } { \kappa \tau^2 }, $$ where the Carmeli gravitational coupling constant κ = 8πG/c ² τ ², where c is the speed of light in vacuum. This allows the definitions of the effective mass density 3 $$ \rho_{eff} \equiv \rho + \rho_{\Lambda} $$ and effective pressure 4 $$ p_{eff} \equiv p - c \tau \rho_{\Lambda}, $$ where ρ is the mass density and p is the pressure. Then the energy-momentum tensor 5 $$ T_{\mu \nu} = \tau^2 \left[ \left(\rho_{eff} + \frac{p_{eff}} {c \tau} \right) u_{\mu} u_{\nu} - \frac{p_{eff}} {c \tau} g_{\mu \nu} \right], $$ where u _μ = (1,0,0,0) is the 4-velocity. The Einstein field equations are taken in the form 6 $$ R_{\mu \nu} = \kappa \left(T_{\mu \nu} - \frac{1} {2} g_{\mu \nu} T \right), $$ where R _μν is the Ricci tensor, κ = 8πG/c ² τ ² is Carmeli’s gravitation constant, where G is Newton’s constant and the trace T = g ^αβ T _αβ . By solving the field equations (6) a space-velocity cosmology is obtained analogous to the Friedmann-Lemaître-Robertson-Walker space-time cosmology. We choose an equation of state such that 7 $$ p = w_e c \tau \rho, $$ with an evolving state parameter 8 $$ w_e \left(R_v \right) = w_0 + \left(1 - R_v \right) w_a, $$ where R _v = R _v (v) is the scale factor and w ₀ and w _a are constants. Carmeli’s 4-D space-velocity cosmology is derived as a special case.     

Dephasing in the semiclassical limit is system-dependent

Dephasing in open quantum chaotic systems has been investigated in the limit of large system sizes to the Fermi wavelength ratio, L/λ_F 〉 1. The weak localization correction g ^wl to the conductance for a quantum dot coupled to (i) an external closed dot and (ii) a dephasing voltage probe is calculated in the semiclassical approximation. In addition to the universal algebraic suppression g ^wl ∝ (1 + τ_D/τ_?)^?1 with the dwell time τ_D through the cavity and the dephasing rate τ _? ^?1 , we find an exponential suppression of weak localization by a factor of ∝ exp[? $\tilde \tau $ /τ_?], where $\tilde \tau $ is the system-dependent parameter. In the dephasing probe model, $\tilde \tau $ coincides with the Ehrenfest time, $\tilde \tau $ ∝ ln[L/λ_F], for both perfectly and partially transparent dot-lead couplings. In contrast, when dephasing occurs due to the coupling to an external dot, $\tilde \tau $ ∝ ln[L/ξ] depends on the correlation length ξ of the coupling potential instead of λ_F.     

Transverse polarization of the lepton in the decay process <Emphasis Type="Italic">B</Emphasis> → <Emphasis Type="Italic">Dlν</Emphasis><Subscript>l</Subscript> due to electromagnetic final-state interaction

The emergence of transverse polarization of the lepton in the decay processes B⁰ → D^?l⁺ν_l and \(B^ + \to \bar D^0 l + \nu _l \) for l = τ, μ is studied on the basis of the Standard Model in the leading approximation of heavy-quark effective theory. It is shown that a nonzero transverse polarization appears owing to electromagnetic final-state interactions at the one-loop level. Diagrams involving D and D* mesons in the intermediate state and making a nonzero contribution to the transverse polarization of the outgoing lepton are considered. If only these mesons are taken into account in evaluating the mean values of the τ-lepton polarization in the decays B⁰→D^?τ⁺ν_τ and \(B^ + \to \bar D^0 \tau ^ + \nu _\tau \), the results are 2.60×10^-3 and ?1.59×10^?3, respectively. The corresponding values of the transverse muon polarization averaged over the Dalitz plot are 2.97×10^?4 and-6.79×10^?4.     

Strongly positive semigroups and faithful invariant states

Let (?, τ, ω) denote aW*-algebra ?, a semigroupt>0?τ _t of linear maps of ? into ?, and a faithful τ-invariant normal state ω over ?. We assume that τ is strongly positive in the sense that $$\tau _t (A^ * A) \geqq \tau _t (A)^ * \tau _t (A)$$ for allA∈? andt>0. Therefore one can define a contraction semigroupT on ?= \(\overline {\mathcal{M}\Omega } \) by $$T_t A\Omega = \tau _t (A)\Omega ,{\rm A} \in \mathcal{M},$$ where Ω is the cyclic and separating vector associated with ω. We prove 1. the fixed points ?(τ) of τ are given by ?(τ)=?∩T′=?∩E′, whereE is the orthogonal projection onto the subspace ofT-invariant vectors, 2. the state ω has a unique decomposition into τ-ergodic states if, and only if, ?(τ) or {?υE}′ is abelian or, equivalently, if (?, τ, ω) is ?-abelian, 3. the state ω is τ-ergodic if, and only if, ?υE is irreducible or if $$\mathop {\inf }\limits_{\omega '' \in Co\omega 'o\tau } \left\| {\omega '' - \omega '} \right\| = 0$$ for all normal states ω′ where Coω′°τ denotes the convex hull of {ω′°τ _t } _t>0. Subsequently we assume that τ is 2-positive,T is normal, andT* _t ?₊Ω \( \subseteqq \overline {\mathcal{M}_ + \Omega } \) , and then prove 4. there exists a strongly positive semigroup |τ| which commutes with τ and is determined by $$\left| \tau \right|_t \left( A \right)\Omega = \left| {T_t } \right|A\Omega ,$$ 5. results similar to 1 and 2 apply to |τ| but the τ-invariant state ω is |τ|-ergodic if, and only if, $$\mathop {\lim }\limits_{t \to \infty } \left\| {\omega 'o\tau _t - \omega } \right\| = 0$$ for all normal states ω′.     

AnSO(10) model withSU(3)⊗SU(2) L ⊗SU(2) R ⊗U(1) B-L ⊗D intermediate symmetry

We construct aSO(10) model with intermediate symmetry $$SU(3) \otimes SU(2)_L \otimes SU(2)_R \otimes U(1)_{B - L} \otimes D$$ and baryon and lepton number conserved between the two highest scales. The experimental values of sin²θ _w and α _s are consistent with the lower bound on τp→e ⁺+π⁰ and with a mass value forv _τ around 1 eV.     

Vacuum condensates in supersymmetric gluodynamics

We analyse the restrictions imposed by supersymmetric Ward identities on the dimension-six condensates in supersymmetric gluodynamics. It is shown that the system of the Ward identities admits a nonzero value for the four-fermion condensate \(\left\langle {\left( {\lambda \sigma _\mu T^a \bar \lambda } \right)^2 } \right\rangle _0 \) while 〈f ^abc F _μν ^a F _νρ ^b F _ρμ ^c 〉₀ must vanish.     

Charged Higgs boson discovery potential at a 500 GeV e+e− linear collider

The discovery potential for charged Higgs bosons has been studied with full-statistics background simulations for $\sqrt s$ =500 GeV and ?=10fb^?1. For the hadronic decay channels $H^ + H^ - \to \operatorname{c} \bar s\bar cs$ , a microvertex detector is crucial for establishing a signal over the $e^ + e^ - \to t\bar t$ background. A combination with a search in the channels $H^ + H^ - \to c\bar s\tau ^ - \nu ,\tau ^ + \nu \tau ^ - \bar \nu$ allows detection sensitivity for charged Higgs bosons up to a mass of about 210GeV, independent of the charged Higgs decay modes. Sensitivity regions in them _A-tanβ parameter space of the Minimal Supersymmetric extention of the Standard Model (MSSM) are given.     

Angular correlations and the tau-neutrino mass

Effects of a nonzero mass for the tau neutrinov _τ as well as a right-handed charged-current contribution to the τ?v _τ coupling are discussed. Angular correlations of the decay products of τ⁺τ^? ine ⁺ e ^? annihilation are calculated as functions of \(m_{v_\tau } \) and the relative amount of right-handed τ?v _τ coupling.     

Some comments on heavy quark bound states,production and decay

We suggest that mixed heavy quark bound states like \(b\bar c\) may offer very good testing ground for Q.C.D. We make a prediction within ≈0.3% for the \(b\bar c\) ground state mass and discuss its possible production in weak decays. Various general features of non leptonic decays of heavey flavors and in particular the prediction of absence ofK _* ⁰ resonance inD ⁰→K ^-→⁺→⁰ arte discussed, and finally we close by commenting on the importance of associated heavy flavor production as a crucial test for the recently advanced preconfinment notion.     

M s −M u quark mass difference and the scalar form factor ofK μ3 0 reaction

We study through QCD sum rules the connection between the invariant quark mass difference \(\hat m_s - \hat m_u\) and the scalar form factor of the reactionK ⁰→π ^? μ ⁺ v _μ in the physical region. We use both theoretical information, (the value off ₊(0) and the Callan-Treiman relation, includingm _π ²/m _k ² corrections) and experimental one (the value ofλ ₀ from a linear fit) to give a lower bound for \(\hat m_s - \hat m_u\) . Taking the world most recent fitted value forλ ₀,λ ₀ = 0.025, which may be reasonably identified with the slope att=0, andf ₊ (0) ≈ 0.98, we obtain \(\hat m_s - \hat m_u\) ≥ 250 MeV for \(\Lambda _{\overline {MS} }\) = 150 MeV. The relevant hypotheses and experimental trends are discussed.     

Invariance of Jarlskog Determinant Above the GUT Scale

An asymmetry between the probabilities P(ν _μ →ν _e ) and \(P(\bar {\nu _{\mu }}\rightarrow \bar {\nu _{e}})\) would be direct indication of CP violation at the fundamental level. Planck scale effects on neutrino mixing, we have derived the mixing angles of neutrino flavour due to Planck scale effects. It has been shown that Jarlskog determinant remains nearly invariant above the GUT scale.     

The semileptonic decaysB→Mτν as a probe of hadron dynamics

We show how data on \(\bar B \to M\tau \bar v\) can be used to probe models for the hadronic form-factors which describe the \(\bar B \to M\) transition, whereM isD,D ^* etc. Extra form-factors contribute to \(\bar B \to M\tau \bar v\) , as compared to \(\bar B \to Me\bar v\) , and these may be studied by observing the polarisation of the outgoing τ. Model predictions for the decay rate and the τ polarisation are presented.     

A new determination of the capture ratior_c = \frac{{\sum ^ - p \to \sum ^0 n}}{{(\sum ^ - p \to \sum ^0 n) + (\sum ^ - p \to \Lambda ^0 n)}}, the Λ0-lifetime and the ∑−-Λ0 mass difference

The two∑ ^? reactions at rest∑ ^? p→Λ ⁰ n and∑ ^? p→Λ ⁰ n have been studied in order to determine the capture ratio $$r_c = \frac{{\sum ^ - p \to \sum ^0 n}}{{(\sum ^ - p \to \sum ^0 n) + (\sum ^ - p \to \Lambda ^0 n)}}$$ , theΛ ⁰-lifetime and the∑ ^?-Λ ⁰ mass difference. The following results were obtained: $$\begin{gathered} rc = 0.474 \pm 0.016 \hfill \\ \tau _{\Lambda ^0 } = (2.47 \pm 0.08) \times 10^{ - 10} \sec \hfill \\ M_{\sum ^ - } - M_{\sum ^0 } = 81.64 \pm 0.09{{MeV} \mathord{\left/ {\vphantom {{MeV} {c^2 }}} \right. \kern-\nulldelimiterspace} {c^2 }} \hfill \\ \end{gathered} $$ The∑ ^?-mass was determined from the range of the stopping∑ ^?-hyperons,M _∑} =1197.19±0.32 MeV/c ².     

Hadroproduction of ψ and Υ

We show that inclusive ψ hadroproduction cross sections andx _F -distributions are quantitatively consistent with calculations based on the lowest order \(q\bar q \to c\bar c\) andgg→ \(c\bar c\) QCD subprocesses using a duality ansatz. Data in the πN, KN, NN and \(\bar NN\) channels are considered. They provide determinations of the gluon distributions within the nucleon, the pion, and the kaon at the ψ mass scale. AvailableNN→ΥX data aty=0 are consistent with the same model, using gluon distributions appropriate to the Υ mass: predictions ofx _F -distributions are made.     

Powerful dynamical neutrino source with a hard spectrum

A powerful dynamical neutrino source with a hard spectrum obtained via the (n, γ) activation of ⁷Li and a subsequent β^? decay (T _1/2=0.84 s) of ⁸Li with the emission of high-energy $\tilde \nu _e$ (up to 13 MeV) is discussed. In the dynamical system, lithium is pumped over in a closed cycle through a converter near the reactor core and further to a remote $\tilde \nu _e$ detector. It is shown that, owing to a large growth of the hardness of the total $\tilde \nu _e$ spectrum, the cross section for the interaction with a deuteron can strongly increase both in the neutral ( $\tilde \nu _e + d \uparrow n + p + \tilde \nu _e$ ) and in the charged ( $\tilde \nu _e + d \uparrow n + n + e^ +$ ) channel in relation to the analogous cross sections in the reactor $\tilde \nu _e$ spectrum.     

Search for rare radiative decays ofΦ-meson at VEPP-2M

Results of the search for rare radiative decay modes of the ?-meson performed with the Neutral Detector at the VEPP-2M collider are presented. For the first time upper limits for the branching ratios of the following decay modes have been placed at 90% confidence level: $$\begin{gathered} B(\phi \to \eta '\gamma )< 4 \cdot 10^{ - 4} , \hfill \\ B(\phi \to \pi ^0 \pi ^0 \gamma )< 10^{ - 3} , \hfill \\ B(\phi \to f_0 (975)\gamma )< 2 \cdot 10^{ - 3} , \hfill \\ B(\phi \to H\gamma )< 3 \cdot 10^{ - 4} , \hfill \\ \end{gathered} $$ whereH is a scalar (Higgs) boson with a mass 600 MeV<m _H <1000 MeV, the real measurement isB(φ→H γ)·B(H→2π⁰)<0.8·10^-4, the quoted result is model dependent, as explained in the text, $$\begin{gathered} B(\phi \to a\gamma ) \cdot B(a \to e^ + e^ - )< 5 \cdot 10^{ - 5} , \hfill \\ B(\phi \to a\gamma ) \cdot B(a \to \gamma \gamma )< 2 \cdot 10^{ - 3} , \hfill \\ \end{gathered} $$ wherea is a particle with a low mass and a short lifetime, $$B(\phi \to a\gamma )< 0.7 \cdot 10^{ - 5} ,$$ wherea is a particle with a low mass not observed in the detector.