Nuclear Transparency with the gamma + n -> pi- + p Process in 4He

Color transparency is studied for the $K^+$ meson produced due to large four-momentum transfer in the $(e,e^\prime)$ reaction on nuclei. The variation of the $K^+$ meson color transparency ($K^+$CT) with the photon virtuality, and kaon momentum is investigated. The calculated results for $K^+$CT are compared with the data reported from Jefferson Laboratory.

This dissertation explores two main topics: 1) Color Transparency and quasi-elastic knockout reactions involving pions and $\rho$ mesons; and 2) determination of the $J/\psi$-nucleon scattering amplitude and scattering length via $J/\psi$ electroproduction on the deuteron. It is shown that at the energies available at the COMPASS experiment at CERN, Color Transparency should be detectable in the reaction $\pi+A\to \pi+p+(A-1)^*$ (proton knockout). It is also shown that Color ...

The quasielastic (e,e$^\prime$p) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer $Q^2$ of 8.1 (GeV/c)$^2$. A nuclear transparency was determined by comparing the data to calculations in the Plane-Wave Impulse Approximation. The dependence of the nuclear transparency on $Q^2$ and the mass number $A$ was investigated in a search for the onset of the Color Transparency phenomenon. We find no evidence for the onset of Color Transp...

It is argued that color transparency in quasi elastic scattering of electrons and hadrons on nuclei is possible only due to Fermi-motion. We found a strong dependence of nuclear transparency on Bjorken x in (e,e'p), it is close to the Glauber model expectations at $x>1$, but increases and even exceeds one at $x<1$. It is argued that color transparency is accompanied by large longitudinal momentum transfer to nuclear matter during the passage of the small size wave packet. \vs...

Exclusive coherent and incoherent electroproduction of the $\rho^0$ meson from $^1$H and $^{14}$N targets has been studied at the HERMES experiment as a function of coherence length ($l_c$), corresponding to the lifetime of hadronic fluctuations of the virtual photon, and squared four-momentum of the virtual photon ($-Q^2$). The ratio of $^{14}$N to $^1$H cross sections per nucleon, known as nuclear transparency, was found to increase (decrease) with increasing coherence leng...

We review the theoretical formalism for hard exclusive processes in a nuclear medium. Theory suggests that these processes will show the very interesting phenomena of color transparency and nuclear filtering. The survival probability in nuclear media has also been predicted to show a scaling behavior at large momentum and large nuclear number. We show that all of these effects may have already been seen experimentally.

Using the experimental data on total {\it S}=1 transition cross-sections \, for $^4$He$(\gamma,p)$$^3$H and $^4$He$(\gamma,n)$$^3$He reactions as the base, the paper describes the possibility of measuring the probability of {\it P}-states in the $^4$He nucleus. The {\it S}=1 transitions may originate from $^3P_0$ states of the nucleus, or be the result of the spin-flip of the final-state particle system from $^1S_0$, or $^5D_0$ states of the $^4$He nucleus, and also as a resu...

Quasi-elastic scattering on $^{12}$C$(e,e'p)$ was measured in Hall C at Jefferson Lab for space-like 4-momentum transfer squared $Q^2$ in the range of 8--14.2\,(GeV/$c$)$^2$ with proton momenta up to 8.3\,GeV/$c$. The experiment was carried out in the upgraded Hall C at Jefferson Lab. It used the existing high momentum spectrometer and the new super high momentum spectrometer to detect the scattered electrons and protons in coincidence. The nuclear transparency was extracted ...

We calculate quasi-exclusive scattering of a virtual photon and a proton or pion in nuclear targets. This is the first complete calculation of ``color transparency" and "nuclear filtering " in perturbative QCD. The calculation includes full integrations over hard interaction kernels and distribution amplitudes in Feynman -x fractions and transverse spatial separation space $b$. Sudakov effects depending on $b$ and the momentum transfer $Q^2$ are included. Attenuation of the h...

We make detailed comparisons between the measured $Q^2$ dependency of nuclear transparency in quasifree electron scattering and theoretical predictions based on Glauber theory. We also describe a theory-free method to extract $T$ from data.