Measurement of the differential cross section and of the polarization parameter in pp elastic scattering at 200 GeV/c

Data are given for the polarization parameter and for the differential cross section in pp elastic scattering at 200 GeV/c, in the range $\text{0.5 ??t ? 4.0}\text{GeV}{}^2$. The polarization changes sign in the dip region, as already observed at 150 GeV/c.     

Simultaneous measurement of 2 and 3 spins in proton proton elastic scattering at 6 GeVc

The elastic cross section for proton proton scattering at 6 $\text{GeV}\text{c}$ was measured using a 70% polarized beam and a 75% polarized target at the Argonne ZGS. In the range $\text{P}{}_{\mathrm{\perp }}{}^2\text{= 0.5 → 2.0(}\text{GeV}\text{c}\text{)}{}^2$ we obtained small error measurements for the ↑↑, ↓↓ and ↑↓ initial spin states perpendicular to the scattering plane. At P_⊥² = 0.5 we also measured the recoil spin and found that the 5 different cross sections were very unequal.     

Naive quark model and deep inelastic scattering

It is assumed that nucleon consists of three quarks with no admixture of gluons or strange quarks. Gluons as are seen in deep inelastic scattering, appear only as a result of bremsstrahlung by valence quarks. The model gives unique predictions for observable quantaties and imitates the scaling behavior at Q² ? 2 GeV² provided the coupling constant of strong interactions is relatively small at such values of $\text{Q}{}^2\text{(}\text{g}{}^2\text{(2}\text{GeV}{}^2\text{)}\text{4π ≈}\text{1}\text{4}\text{)}$. The predictions of the model agree with the data within (10 – 20) % accuracy and links consideration of deep inelastic scattering with the most naive quark model. The effect of charmed particles production is estimated within the model developed. It is shown that the standard four-quark model of weak interactions is inconsistent with observed anomalies in ν, $\text{ν}$-interactions.     

Evidence for a narrow peak in Ksoπ±π+π- at 2.6 gev in 12 gev/cpp interactions

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V⁰ topology of $\text{p}$p interactions at 12 GeV/c. The mass, widht and the product of cross section σ_I times the branching ratio BR into the final state (K_s^oτ±τ⁺τ^? are found to be: $\text{M}{}_{\mathrm{I}}\text{=2.60 ±}\text{0.01}\text{GeV}\text{/}\text{c}{}^2$, $\text{Γ}{}_{\mathrm{I}}\text{?}\text{0.018}\text{GeV}\text{/}\text{c}{}^2$, σ_I·BR≈20 μbarn     

Absorptive effects in the diffractive dissociation of nucleons

Absorptive effects are found to be important in diffraction dissociation. For pp→(nπ⁺)p and np→(pπ^?)p, at small excitation mass, a significant dip structure is created in the production momentum transfer distribution $\text{d}\text{σ}\text{d}\text{t}\text{d}\text{M}\text{near}\text{t = ?0.3 (}\text{GeV}\text{c}\text{)}{}^2$, in agreement with data from Fermilab and the CERN-ISR. The mass-slope correlation, seen in the data, is also reproduced. Most other distributions are affected much less by absorption.     

Differential cross sections of elastic pd scattering in the energy range 10–70 GeV

We present tables of the absolute differential cross sections of elastic pd scattering. The cross-section data have been obtained at the Serpukhov accelerator from 10 to 70 GeV in the |t|-range 0.002–0.2 GeV²/c².The elastic pd scattering amplitude was parametrised as

$\text{A(+)=}\text{d}\text{σ}\text{d}\text{+}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}_{\mathrm{<mtext>opt</mtext>}}\text{(i+α)}\text{exp}\text{1}\text{2}\text{(Bt+Ct}{}^2\text{)}$

The values $\text{α=}\text{Re}\text{A(0)}\text{Im}\text{A(0)}$,B and C are presented in these tables.     

Quark masses

In quark gluon theory with very small bare masses, -$\text{ψ}$$\text{M}$ψ, spontaneous breakdown of chiral symmetry generates sizable masses M_u, M_d, M_s, … We find ($\text{M}{}_{\mathrm{<mtext>u</mtext>}}\text{+ M}{}_{\mathrm{<mtext>d</mtext>}}\text{) /2 ≈ m}\text{p}\text{/ √6 ≈ 312}\text{MeV}\text{,}\text{and}\text{M}{}_{\mathrm{<mtext>s</mtext>}}\text{≈ 432}\text{MeV}$. Scalar densities have well determined non-zero vaccum expectations $\text{〈0|u}{}^{\mathrm{a}}\text{|0〉 ≡ 〈0|ψ(x) (λ}{}^{\mathrm{a}}\text{/2)ψ(x)/0〉 ≈ ?}{}_{\mathrm{\pi }}{}^2\text{M}{}^{\mathrm{a}}\text{,}\text{i.e}\text{〈0? u}{}^{\mathrm{o}}\text{/vb0〉 ≈ 8 × 10}{}^{\mathrm{?3}}\text{(}\text{GeV}\text{)}{}^3$ at an SU(3) breaking of the vacuum c′ ≡ 〈0|u⁸|〉/〈0|u^o|0〉 ≈ ? 16%     

Measurement of elastic scattering in antiproton-proton collisions at 52.8 GeV centre-of-mass energy

We measured the differential cross section for p?p and pp elastic scattering in the momentum-transfer range 0.01 <|t| < 1.0 GeV² at the CERN Intersecting Storage Rings with center-of-mass energy $\text{s}\text{= 52.8}\text{GeV}$. Fitting the differential cross section with an exponential [Aexp (bt)], we found $\text{b}\text{p}\text{p = 13.92 ± 0.59}\text{GeV}{}^{\mathrm{?2}}$ for |t| < 0.05 GeV², whilst for |t| > 0.09 GeV², $\text{b}\text{p}\text{p = 10.68 ± 0.26}\text{GeV}{}^{\mathrm{?2}}$. Using the optical theorem, we obtained for the total cross section $\text{σ}{}_{\mathrm{<mtext>tot</mtext>}}\text{(}\text{p}\text{p)= 44.86 ± 0.78}\text{mb}$ and, by integrating the differential cross section, we obtained for the total elastic cross section $\text{σ}{}_{\mathrm{<mtext>el</mtext>}}\text{(}\text{p}\text{p) = 7.89 ± 0.28}\text{mb}$. Calculations of σ_tot combining elastic-rate and total-rate measurements are also given. All of these measurements were also performed for pp scattering at the same energy, and the results for both reactions are compared.     

Off-diagonal generalized vector dominance and inelastic ep scattering

By also taking into account off-diagonal contributions to the virtual forward Compton amplitude, scaling in ep scattering is obtained from scaling of the total cross section for e⁺e^? annihilation into hadrons. The parameter which sets the scale for the q² dependence in ep scattering is calculated to be $\text{m}{}^2\text{? 0.61 m}{}_{\mathrm{?}}{}^2\text{? 0.36}\text{GeV}{}^2$.     

Light-cone expansions,the parton model and virtual γγ scattering

It is shown that it is sufficient to use the light-cone algebra of currents and the algebra of bilocal operators to find the asymptotic behaviour of the γγ scattering amplitude when one (or two) of the photon masses q_1,2² is large, and for an arbitrary value of the energy squared s = (q₁+q₂)². A general form of this asymptotic behaviour is obtained. The box-diagram is dominant over the wide region in $\text{s(μ}{}^2\text{« s « q}{}_1{}^2\text{q}{}_2{}^2\text{/μ}{}^2\text{,μ ～ 1}\text{GeV}\text{)}$ and so the asymptotic amplitude is known completely. It is shown that the parton model of the type of ref.[8] gives the same predictions for the asymptotic behaviour of the γγ amplitude.     

Antiproton-proton total elastic cross sections in the T and U regions (0.69−2.43 GeV/c)

Antiproton-proton total elastic cross sections at 21 incident momenta in the range 0.69 to 2.43 GeV/c have been deduced by combining p?p elastic differential cross sections over a c.m. angular range $\text{?0.95 ?}\text{cos}\text{θ}{}^1\text{? 0.93}$ with forward elastic cross sections derived from recent real-part measurements and p?p total cross sections. Two bumps are observed, at $\text{M}{}_1\text{? 2.155}$ and $\text{M}{}_2\text{? 2.345}\text{GeV}\text{/c}{}^2$, having widths of Г₁ ～ 0.135 and $\text{Г}{}_2\text{～ 0.135}\text{GeV}\text{/c}{}^2$. Corresponding structures in other p?p reaction channels are discussed.     

Radiative production of gravitinos and photinos in e+e− annihilation

We evaluate cross sections for the two processes e⁺e^? → γ-photino-antiphotino, e⁺e^? → γ-gravitino-antiphotino. In the local limit approximation they are proportional to $\text{α}{}^3\text{s}\text{m}{}^4$ (spin-0 electron) and $\text{G}{}_{\mathrm{Newton}}\text{α}{}^2\text{s}\text{m}{}^2$ (gravitino), respectively. I If spin-0 electrons have masses between 16 and $\text{40}\text{GeV}\text{c}{}^2$, the γ-photino-antiphotino production cross section would be of the order of 0.4 to 0.1 pb at $\text{s}\text{= 40}\text{GeV}$, with the cuts indicated in the text. Detecting this process is within the range of possibilities at PETRA. If no such signal is found the existence of light photinos coupled to spin-0 electrons lighter than $\text{≈40}\text{GeV}\text{c}{}^2$, or to gravitinos lighter than $\text{≈10}{}^{\mathrm{?6}}\text{eV}\text{c}{}^2$, would be excluded.     

Deuteron-deuteron scattering at 1.65, 2.00 AND 2.29 GeV: Theoretical interpretation in the Glauber model

An analysis of deuteron-deuteron scattering data at T₀= 1.65, 2.00 and 2.29 GeV is given in the framework of the Glauber NN multiple-scattering model. The model accounts qualitatively well for the larger momentum transfer data. The model cannot reproduce the observed experimental bump at small transfer in the region of missing mass $\text{2 GeV}\text{c}{}^2$, because pionic processes have not been considered. Nevertheless, it shows that the nucleon background is important.     

A Regge-pole overview of kaon-nucleon scattering

Regge-pole residues and trajectories have been extracted at fixed-t values in the range $\text{0 ? t ? ?1.0 (}\text{GeV}\text{/c)}{}^{\mathrm{<mtext>2</mtext>}}$ by simultaneously fitting CMSR and measured data on all two-body K(K)N → K(K)N processes for laboratory momenta between 1.5 GeV/c and 280 GeV/c. A good fit to all the data and CMSR is possible provided that an f′ is introduced in the vacuum quantum number exchange amplitude. This explains the possible violation of duality previously seen in this amplitude. Particular attention is paid to the problem of $\text{?-}\text{A}{}_{\mathrm{<mtext>2</mtext>}}$ exchange degeneracy and the role of their secondary trajectories, both in the CMSR and for the line-reversal breaking observed in KN charge exchange.     

The size of inelastic diffraction dissociation

It is suggested that the inelastic diffraction dissociation cross section is a constant fraction β of the unitary bound, i.e. $\text{σ}{}_{\mathrm{DIFF}}\text{(s) = β[}\text{1}\text{2}\text{σ}{}_{\mathrm{TOT}}\text{(s) ? σ}{}_{\mathrm{EL}}\text{(s)]}$. Available data from pp collisions for s ? 20 (GeV/c)² are consistent with our hypothesis with $\text{β ～}\text{1}\text{2}$. Consideration of a specific model for diffraction suggests that the value of $\text{β ～}\text{1}\text{2}$ is a consequence of there being no lower mass state than pp with its quantum numbers. Predictions for πp and Kp scattering are presented.     

Study of electron pairs below the Z0 mass produced in pp collisions at √s = 540 GeV

From an integrated luminosity of $\text{∫}\text{L}\text{d}\text{t = 116}\text{nb}{}^{-1}$, 10events are found which contain an electron pair of mass in the range $\text{12 < M}{}^{\mathrm{<mtext>ee</mtext>}}\text{< 26}\text{GeV}\text{c}{}^2$ and electron transverse momenta $\text{p}{}_{\mathrm{<mtext>T</mtext>}}{}^{\mathrm{<mtext>e</mtext>}}\text{> 5}\text{GeV}\text{c}$. THe sample are described, as well as some featruyres of the The production characteristics of this sample are described, as well as some features of the estimated to be 2.2±0.6 events. The production characteristics of this sample are described, as well as some features of the associated event topology. Comparisons are made with the expectations for such electron pair production from the Drell-Yan mechanism and from the semi-leptonic decay of heavy flavours.     

Measurement of the polarization parameter in π−p elastic scattering at 40 GeV/c

We report our first measurements of the polarization in the elastic scattering of negative pions from polarized protons at an incident pion momentum of 40 GeV/c. The momentum-transfer region covered was 0.08 < |t| < 1.3 (GeV/c)². The angular distribution of the polarization exhibits a first minimum of ～ ? 5% and the well-known zero around t ≈ ? 0.6 (GeV/c)². The energy variation of the first minimum (at around t = ? 0.2) may be expressed in a simple form, $\text{P}{}_{\mathrm{<mtext>avr</mtext>}}\text{= ?(0.48±0.06) s}{}^{\mathrm{?0.52\pm 0.05}}$.     

Observation of a direct low-mass e+e− continuum in π-p interactions at 16 GeV/c

The production of prompt electron-positron pairs in 16 GeV/c π^-p collisions has been measured using the LASS spectrometer at SLAC. An excess of events is observed above the estimated contribution of direct and Dalitz decays of known resonances in the kinematic range defined by $\text{0.1?χ?0.45, 0?p}{}_{\mathrm{T}}\text{?0.8}\text{GeV}\text{c}$ and $\text{0.2?M(e}{}^{\mathrm{+}}\text{e}{}^{\mathrm{?}}\text{)?0.7}\text{GeV}\text{c}{}^2$. The excess signal decreases slowly with increasing M, but exhibits very steep χ and p_T² dependence.     

Study of the reaction νp → μ+pπ−

We present data on the reaction $\text{ν}\text{p → μ}{}^{\mathrm{+}}\text{pπ}{}^{\mathrm{?}}$ from an exposure of the Fermilab 15 ft hydrogen bubble chamber. The channel cross section for $\text{5}\text{GeV}\text{< E}{}_{\mathrm{<mtext>\nu </mtext>}}\text{< 70}\text{GeV and}\text{M(}\text{p}\text{π}{}^{\mathrm{?}}\text{) < 1.9}\text{GeV is}\text{σ = (27 ± 5) × 10}{}^{\mathrm{?40}}\text{cm}{}^2$. This cross section is dominated by the $\text{I =}\text{1}\text{2}$ production amplitude.