Data on the production of positively charged particles emitted at an angle of 40
(in the laboratory frame) with transverse momenta of up to 2.7 GeV
in the interaction of 50-GeV
protons with carbon, ...aluminum, copper, and tungsten nuclear targets are presented. Particular attention is given to studying the production of light nuclear fragments, such as deuterons (
) and tritons (
). An analysis of data on
and
particles gives grounds to state that these fragments arise via a local mechanism of their direct knockout from nuclei. The results were obtained in the SPIN experiment at the Institute for High Energy Physics (IHEP, Protvino).
Data on the production of antiprotons at an angle of 40° in the laboratory system in collisions of 50-GeV protons with C, Al, Cu, and W nuclear targets have been obtained in the SPIN experiment ...(IHEP, Protvino, Russia). Invariant cross sections have been measured at transverse momenta up to
p
T
≈ 2.6 GeV/
c
. The an-alysis of the momentum spectra has shown that multinucleon (multiquark) configurations inside a nucleus are involved in the production of antiprotons.
The SPIN experiment is carried out with the aim of studying inclusive production of charged particles with high transverse momenta in hard proton−nucleus and nucleus−nucleus interactions. A ...single-arm narrow-aperture spectrometer is used in the study. The uniqueness of the experiment is in the high intensity of the proton (10
12
−10
13
protons/s) and ion (of the order of 5 × 10
9
ions/s) beams ejected from the U-70 accelerator, which makes it possible to measure inclusive cross sections varying by seven orders of magnitude. The SPIN setup is able to detect particles with momenta in a kinematic domain of nucleon−nucleon interactions as well as beyond its limits. The spectrometer equipment and the features of the measurement procedure are described.
A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen ...and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously.
The first data on the yield of the lightest nuclear fragments (protons
p
, deuterons
d
, and tritons
t
) with high transverse momenta
p
T
at an angle of 40° in the laboratory reference frame from ...nuclear targets bombarded by 50-GeV/
c
protons and 20A-GeV/
c
carbon nuclei obtained in the SPIN experiment (IHEP, Protvino, Russia) have been reported. It has been shown that the
pA
and C
A
data can be described within a common scaling approach, which possibly indicates that the mechanism of formation of high-
p
T
nuclear fragments is common for these reactions.
The yields of cumulative protons and π
±
mesons emitted at a laboratory angle of 40° from carbon and heavier nuclear targets irradiated by a proton beam from the U70 accelerator (Institute for High ...Energy Physics, Protvino) have been studied in the SPIN experiment. It has been found that the effect of the target nucleus on the yield of particles with large transverse momenta is weakened.
Formation of the
d
and
t
cumulative light nuclear fragments emitted from the nucleus with large transverse momenta at an angle of 35° in the laboratory frame is investigated. The data on collisions ...of 50-GeV protons with the C, Al, Cu, and W nuclei are collected using the extracted proton beam of the IHEP accelerator and the SPIN detector. The results indicate that the dominant contribution to formation of nuclear fragments comes from the local process of direct knockout from the nucleus.
Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the Hermes experiment. The asymmetries were studied as a ...function of the azimuthal angle ψ about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum PT relative to the direction of the incident beam, and the Feynman variable xF. The sinψ amplitudes are positive for π+ and K+, slightly negative for π− and consistent with zero for K−, with particular PT but weak xF dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer.
The first data on production of cumulative
K
+
,
K
–
mesons and antiprotons with high transverse momenta outgoing at the lab angle of 40 degrees in proton–nucleus interactions are presented. ...Inclusive cross sections are studied for the C, Al, Cu, and W targets at the proton beam momentum of 50 GeV/
c
. The investigated range of transverse momenta from 0.6 to 2.7 GeV/
c
is partially beyond the proton–nucleon kinematics. The
/π
–
and
K
+
/
K
–
ratios are identical for all investigated targets within the experimental errors. The data indicate a noticeable contribution of multiparton processes to production of cumulative mesons and antiprotons. The investigations have been performed in the SPIN experiment at the U-70 accelerator.