QCD corrections to jet multiplicity moments

QCD predictions of hadronic multiplicity moments in jets, including corrections of relative order $\text{α}{}_{\mathrm{s}}\text{(Q}{}^2\text{)}$, are presented. They agree with e⁺e^? annihilation data for reasonable values of α_s, but the corrections are so large that terms of yet higher order are unlikely to be negligible.     

Coupling constants for several light nuclei from a dispersion analysis of nucleon and deuteron scattering amplitudes

A forward dispersion relation cannot be applied to charged particle scattering amplitudes unless the influence of the Coulomb interaction is explicitly considered. Earlier studies have shown how Coulomb effects can be taken into account when direct (s-channel or bound-state) poles are investigated. In this paper we extend the Coulomb modification to include I = 0 exchange (u-channel) processes as well. We then apply a forward dispersion relation to empirical d + α, p + d and n + d elastic scattering amplitudes which contain both direct and exchange poles with and without Coulomb effects. We obtain detailed and model-independent information on the following vertices: ⁶Li-α-d (S- and D-state) ⁴He-d-d, ³He-d-p, ³H-d-n and d-p-n. From the coupling constants we calculate the asymptotic normalization (spectroscopic factors) C²₁ of the corresponding cluster wave functions, which become: $\text{C}{}^2{}_0\text{(}{}^6\text{Li}\text{, α}\text{d}\text{) = 4.62 ± 0.23}$, $\text{C}{}^2{}_2\text{(}{}^6\text{Li}\text{, α}\text{d}\text{) = (1 ± 6) × 10}{}^{\mathrm{?4}}$, C²₀(α, dd) < 2, $\text{C}{}^2{}_0\text{(}{}^3\text{He, dp}\text{) = 3.5 ± 0.4}$, $\text{C}{}^2{}_0\text{(}{}^3\text{H, dn}\text{) = 2.6 ± 0.3}\text{and}\text{C}{}^2{}_0\text{(}\text{d, np}\text{) = 1.66 ± 0.1}$.     

Elastoresistivity of TTF-TCNQ and related compounds

Elastoresistances of TCNQ high conducting salts have been measured at room temperature by an original strain gauge technique. The effects, on the longitudinal and transverse resistivities ?, of an elementary uniaxial strain ? applied along one of the three axes, a, b or c¹ respectively, have been estimated.For TTF-TCNQ, they are:

$\text{K}{}^{\mathrm{b}}{}_{\mathrm{a}}\text{=? ln ?}{}^{\mathrm{b}}\text{/??}{}_{\mathrm{a}}\text{= 16±3}$

;

$\text{K}{}^{\mathrm{b}}{}_{\mathrm{b}}\text{= ? ln α}{}^{\mathrm{b}}\text{/??}{}_{\mathrm{b}}\text{= 34±4}$

;

(5% risk).So, in an hydrostatic pressure experiment, the fraction of piezoresistivity attributable to transverse effects is 43± 10% of the total value χ^b (K^b_a and K^b_c effects accumulated).Low values have been found for the anisotropy (?^a/?^b) variations due to strains. So one may write:

$\text{K}{}^{\mathrm{a}}{}_{\mathrm{a}}\text{= ? ln ?}{}^{\mathrm{a}}\text{/??}{}_{\mathrm{a}}\text{≌K}{}^{\mathrm{a}}{}_{\mathrm{b}}$

;

$\text{K}{}^{\mathrm{a}}{}_{\mathrm{b}}\text{= ? ln ?}{}^{\mathrm{a}}\text{/??}{}_{\mathrm{b}}\text{≌ K}{}^{\mathrm{b}}{}_{\mathrm{b}}$

;

.The TTF-, HMTTF-, TSF-, HMTSF-TCNQ elastoresistance values are coherent with the previously measured hydrostatic pressure piezoresistivity values.All these experimental results are in good agreement with a model where the longitudinal but also the transverse elastoresistivities are essentially due to variations with strains of the longitudinal scattering time τ_ν defined by σ^b = ne²τ_ν/m¹.     

How to continue the predictions of perturbative QCD from the spacelike region where they are derived to the timelike regime where experiments are performed

The predictions of perturbative QCD are derived in the deep euclidean region, whereas the physical region for most observables is timelike. The confrontation of these predictions with experiment thus necessitates an analytic continuation. This we find introduces large higher order corrections in terms of α_s(|Q²|), the usual choice ofperturbative expansion parameter. These corrections are naturally absorbed by changing to the expansion parameter $\text{a}\text{(Q}{}^2\text{) = |α}{}_{\mathrm{<mtext>s</mtext>}}\text{(Q}{}^2\text{)|(}\text{Re}\text{α}{}_{\mathrm{<mtext>s</mtext>}}\text{(Q}{}^2\text{)/|α}{}_{\mathrm{<mtext>s</mtext>}}\text{(Q}{}^2\text{)|)}{}^{\mathrm{<mtext>(n?2)</mtext><mtext>3</mtext>}}$, where α_s(Q²)ⁿ is the leading term in the spacelike region. For the intermediate range of Q² experimentally accessible at present, where $\text{a}\text{(Q}{}^2\text{)}$ is significantly smaller than α_s(|Q²|), we find the resulting phenomenology is improved. In particular, we demonstrate how the values of $\text{Λ}{}_{\mathrm{<mtext>MS</mtext>}}$ obtained from analyses of quarkonium decays become consistent.     

Radiative corrections to neutrino-lepton scattering in the SU(2)L ⊗ U(1) theory

The radiative corrections of O(α) to the final electron spectrum and the total cross sections for the processes $\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{→ ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{,}\text{ν}{}_{\mathrm{\mu }}\text{+}\text{e}\text{→ ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}\text{, ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}\text{→ ν}\text{e}\text{+}\text{e and}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{+}\text{e}$ are studied in the framework of the SU(2)_L ? U(1) theory. The electroweak corrections to the fisrt two processes are presented in two equivalent schemes in terms of (G_μ, sin²θ_w) and $\text{(G}{}_{\mathrm{\mu }}\text{,}\text{sin}{}^2\text{θ}\text{?}{}_{\mathrm{<mtext>w</mtext>}}\text{(m}{}_{\mathrm{<mtext>w</mtext>}}\text{))}$. As a byproduct, the relationship to O(α) between the basic parameters $\text{sin}{}^2\text{θ}{}_{\mathrm{<mtext>W</mtext>}}\text{≡ 1 ? m}{}_{\mathrm{<mtext>W</mtext>}}{}^2\text{/m}{}_{\mathrm{<mtext>Z</mtext>}}{}^2\text{and sin}{}^2\text{θ}\text{?}{}_{\mathrm{<mtext>W</mtext>}}\text{(m}{}_{\mathrm{<mtext>W</mtext>}}\text{)}$ (defined by modified minimal subtraction) is explicitly given. The QED corrections are evaluated in the extreme relativistic (ER) regime of the final electron (E′_e ? m_e) for the situation in which the bremsstrahlung photons are unobserved and unrestricted. The ER approximation allows us to obtain simple analytic expressions for the differential electron spectrum and the total cross sections. The relationship to O(G_Fα) between the spin-averaged differential cross sections for the above processes in the ER regime is derived.     

Glueball spectroscopy from strong coupling expansions in hamiltonian lattice QCD

Masses of all the glueballs which are created by 6- or 7-link operators are calculated to order g^?8 in pure SU(3) hamiltonian lattice gauge theory. Several low-lying states are found with masses $\text{m(0}{}^{\mathrm{++1}}\text{)～ 1.4 m}{}_{\mathrm{<mtext>s</mtext>}}\text{, m(0}{}^{\mathrm{++7}}\text{) ～ 1.7 m}{}_{\mathrm{<mtext>s</mtext>}}$ (¹ and ⁷ stand for radial excitations and m_s is the mass of the lowest 0⁺⁺ state), . These values are obtained at the point g^?2 ? 0.8, which lies near the scaling region.     

A search for massive photinos at petra

We have searched for the supersymmetric partner of the photon, the photino, by investigating two-photon and single photon final states in e⁺e^? collisions. No significant signals were observed, which excludes the existence of the photino in the mass range 0.08–18 GeV/c² at the 95% confidence level, subject to the assumptions d=(100 GeV)² and $\text{m}{}_{\mathrm{<mtext>e</mtext><mtext>?</mtext>}}\text{=40}\text{GeV}\text{/c}{}^2$, where d is the supersymmetry breaking scale parameter and $\text{m}{}_{\mathrm{<mtext>e</mtext><mtext>?</mtext>}}$ is the scalar electron mass.     

Weak interactions of a light gravitino: A lower limit on the gravitino mass from the decay ψ→gravitino + antiphotino

The massive gravitino of spontaneously-broken locally supersymmetric theories may well be very light, leading to a mixing between weak and gravitational interactions. Particularly interesting is the photon coupling to a gravitino-antiphotino pair, with a vertex factor ($\text{κ/m}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext><mtext>\surd 6</mtext>}}\text{) γ}{}^{\mathrm{\mu }}\text{q}{}^2$: a one-photon exchange with ordinary fermions is equivalent to a local four-fermion interaction. From the upper limit on the decay ψ → gravitino + antiphotino we get a lower limit ～ 10^?8 eV/c² on the gravitino mass.     

Strong coupled-channels effects in the 9Be(α, t)10B reaction

Differential cross sections were measured for the reactions ${}^9\text{Be}\text{(α, α')}{}^9\text{Be}\text{,}{}^9\text{Be}\text{(α,}\text{t}\text{)}{}^{10}\text{B and}{}^9\text{Be}\text{(α,}{}^3\text{He}\text{)}{}^{10}\text{B at}\text{E}{}_{\mathrm{\alpha }}\text{= 65}\text{MeV}$ for angles ranging from θ_lab = 6° to 48°. Optical-model analysis was performed for elastic α-scattering from ⁹Be at E_α = 48, 65 and 104 MeV, and DWBA and CC calculations were done for the inelastic α-scattering at E_α = 65 MeV. DWBA calculations for the ⁹Be(α, ³He) reactions do not fit the transfer data so well and extracted spectroscopic factors are in disagreement with those of Cohen and Kurath and with values obtained from other reactions. Full CRC calculations assuming a band structure for the low-lying states of ¹⁰B and employing a modified set of Cohen and Kurath spectroscopic factors yield globally better fits both in shape and in absolute cross section for differential cross sections to low-lying states in ¹⁰B obtained in ⁹Be(α, t)¹⁰B at $\text{E}{}_{\mathrm{\alpha }}\text{= 65}\text{MeV and}{}^9\text{Be}\text{(}{}^3\text{He, d}\text{)}{}^{10}\text{B at}\text{E}{}_{\mathrm{<mtext>d</mtext>}}\text{= 17}\text{MeV}$. In general, strong coupled-channel effects mainly affecting the distorted waves are observed both in entrance and exit channels.     

Two-electron,one-photon transitions in nickel

The two emission lines, Kα₁α₃^h and Kα₂α₃^h resulting from the two-electron transitions $\text{1s}{}^{\mathrm{?2}}\text{→ 2s}{}^{\mathrm{?1}}\text{2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ and $\text{1s}{}^{\mathrm{?2}}\text{→ 2s}{}^{\mathrm{?1}}\text{2p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ were resolved for elemental nickel. Their measured energies agree well with calculations. Their relative intensity $\text{I(Kα}{}_1\text{α}{}_3{}^{\mathrm{h}}\text{)/I(Kα}{}_2\text{α}{}_3{}^{\mathrm{h}}\text{) ≈}\text{3}\text{4}$ and their intensity relative to that of the Kα diagram lines is about 10^?4. This is some 10⁴ times larger than both theoretical results and the results of ion-atom collision experiments.     

Theoretical analysis of the centrifugal distortion contributions to the rotational spectra of 2Π diatomics

The centrifugal distortion contributions to the rotational energies of diatomic molecules are derived from the resolution of the vibration-rotation wave equation. The unknown radial dependence of the fine structure constants is taken into account by means of a Taylor expansion around the equilibrium distance. Hence, one obtains the expressions of the centrifugal corrections associated with each fine structure constant in terms of the equilibrium values of its radial derivatives. The case of ²Π states is examined in detail. The dependence of the centrifugal distortion effects upon the choice of the coupling scheme representation is exhibited and a ²Π energy matrix containing the centrifugal constants of any order is proposed. Such a matrix is appropriate to fit the data for any value of the rotational quantum number. The theoretical expressions of the energy levels are related to the experimental data and the correlations between the spin-orbit centrifugal and spin-rotation contributions are put in evidence. It is shown that very compact formulas can be derived allowing a straightforward evaluation of the successive radial derivatives of the spin-orbit function in terms of the spectroscopic data $\text{A}{}^{\mathrm{(1)}}\text{? ?α}{}_{\mathrm{A}}\text{(}\text{w}{}_{\mathrm{e}}\text{B}{}_{\mathrm{e}}\text{)}$; $\text{A}{}^{\mathrm{(2)}}\text{? ?(1 +}\text{α}{}_{\mathrm{B}}\text{w}{}_{\mathrm{e}}\text{2B}{}_{\mathrm{e}}{}^2\text{)A}{}^{\mathrm{(1)}}$; …. Application of these results to the case of several molecules is considered and discussed.     

A remarkable duality in one-particle quantum mechanics between some confining potentials and (R+L∞ϵ) potentials

The equivalence between the bound-state problem for the spatial harmonic oscillator and for the Coulomb potential is reexamined and extended: a similar duality is displayed between large classes of confining potentials and (R+L^∞_?) potentials, i.e., potentials for which the Schrödinger operator has among other properties a discrete spectrum bounded below, in (-∞, 0). The involved confining potentials U(r) must satisfy: $\text{r}{}^{\mathrm{-\alpha }}\text{U(r)}\textcolor{red}{}\text{g>0}{}_{\mathrm{r\to +\infty }}\text{, r}{}^{\mathrm{<mtext>-2\alpha </mtext><mtext>(2+\alpha )</mtext>}}\text{U (r}{}^{\mathrm{<mtext>2</mtext><mtext>(2+\alpha )</mtext>}}\text{) ? g}\text{is R}\text{+}\text{L}{}^{\mathrm{\infty }}{}_{\mathrm{?}}$.     

QED distributions for hard photon emission in e+e− → μ+μ−γ

The hard photon emission in e⁺e^? → μ⁺μ^?γ is investigated to order α³. Formulas for a number of distributions are obtained, when neglecting terms of order (m_e/?)² and (m_μ/?)². Both charge-even and charge-odd contributions are calculated. The total contribution to the charge asymmetry parameter

$\text{? =}\text{[}\text{d}\text{σ(θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{?}\text{d}\text{Oσ(π?θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{]}\text{[}\text{d}\text{σ(θ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{+}\text{d}\text{σ(π ? σ)}\text{d}\text{O}{}_{\mathrm{\mu }}{}^{\mathrm{+}}\text{]}$

does not exceed 5% for the c.m.s. energy 2? = 3 GeV.     

Non-leading corrections to the Drell-Yan cross section at small transverse momentum

The production of Drell-Yan lepton pairs at small transverse momentum is analyzed to second order in QCD perturbation theory. By calculating exactly all terms involving powers of the large logarithm ln $\text{(}\text{Q}{}^2\text{q}{}_{\mathrm{<mtext>T</mtext>}}{}^2$), we are able to confront the predictions of “soft gluon” cross sections in which these logarithms are summed to all orders. Our results confirm the factorization properties of these cross sections, and yield new information on previously undetermined coefficients.     

Hadron masses and the sigma commutator in light of chiral perturbation theory

We analyze carefully the impact of non-analytic chiral corrections to the mass spectrum of the pseudoscalar meson octet J^P = 0^? and the baryon octet $\text{J}{}^{\mathrm{<mtext>P</mtext>}}\text{=}\text{1}\text{2}{}^{\mathrm{+}}$. We find that the quark mass ratios must lie in the range $\text{21 ≤}\text{m}{}_{\mathrm{<mtext>s</mtext>}}\text{m}\text{?}\text{≤ 32}$ and $\text{1.6 ≤}\text{m}{}_{\mathrm{<mtext>d</mtext>}}\text{m}{}_{\mathrm{<mtext>u</mtext>}}\text{≤ 2.2}$. We also calculate the analogous corrections to the pion-nucleon sigma commutator σ_πN. It turns out that the value σ_πN = 60 MeV is not compatible with the structure of the meson and baryon spectrum, unless the nucleon mass is smaller than 600 MeV in the chiral limit m_u = m_d = m_s = 0.     

Hole mass measurement in p-type InP and GaP by submillimetre cyclotron resonance in pulsed magnetic fields

The first observation of cyclotron resonance in p-type InP is reported. The holes were thermally excited at 110 K and the resonance was observed at 337μm wavelength (HCN laser) using a pulsed magnetic field of 0–350 kG. The effective masses of the light and heavy holes in the 〈111〉 direction were found to be $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.12 ± 0.01 m}{}_0$, and in the 〈100〉 direction $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.12 ± 0.01 m}{}_0$, $\text{m}{}^1{}_{\mathrm{<mtext>H</mtext>}}\text{= 0.56 ± 0.02 m}{}_0$. We obtain an estimate of the Dresselhaus parameters A = ?5.04, |B| = 3.12, C² = 6.57. We also report the effective masses for p-type GaP in the 〈111〉 direction as $\text{m}{}^1{}_{\mathrm{<mtext>L</mtext>}}\text{= 0.18 ± 0.02 m}{}_0$, $\text{m}{}^1{}_{\mathrm{<mtext>H</mtext>}}\text{= 0.56 ± 0.04 m}{}_0$.     

Level structure in 117Sb investigated in the decay of the isomeric three-quasiparticle state

The level structure of ¹¹⁷Sb was investigated in the reactions ¹¹⁵In(α, 2nγ)^117mSb, ¹¹⁷Sn(d, 2nγ)^117mSb and ¹¹⁷Sn(p, nγ)^117mSb. In order to confirm level sequences and to assign spins and parities to levels populated in the decay of the isomeric three-particle state $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ = 340 μs), prompt and delayed γ-ray spectra, lifetimes, γ-γ coincidences, γ-ray angular distributions, conversion electrons and excitation functions were measured. The spin $\text{25}\text{2}$⁺ of the isomeric state can be explained by the three-particle configuration [$\text{π(}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{); v(}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{)}{}^2\text{10}{}^{\mathrm{+}}\text{]}\text{25}\text{2}{}^{\mathrm{+}}$. This is supported by the experimentally determined g-factor of g = O.115 ± 0.006. Other levels in ¹¹⁷Sb can be interpreted as particle states coupled to anharmonic vibrations of the core. The existence of an excited $\text{9}\text{2}{}^{\mathrm{+}}\text{[404]}$ quasirotational band is experimentally proved and is supported by calculations of the equilibrium deformation.