The high-spin states of ${}^{150}\mathrm{Ho}$ have been studied by the ${}^{141}\mathrm{Pr}$(${}^{16}\mathrm{O}$,$7n$)${}^{150}\mathrm{Ho}$ reaction at a beam energy of 165 MeV using techniques of in-beam γ-ray spectroscopy. Measurements of $\gamma \text{−}\gamma \text{−}t$ coincidences were performed. Based on the coincidence relations of γ rays, a level scheme was constructed up to 11.25 MeV. The excitation energy of high-spin isomer was determined to be 8.412 MeV with a half-life of 787 ± 36 ns. The experimental results were compared with deformed independent particle model (DIPM) calculations. The excitation energy of the state with the possible configuration of the high-spin isomer in ${}^{150}\mathrm{Ho}$ was discussed.

Positive-energy one-particle levels for neutrons in $Y_{20}$ deformed Woods-Saxon potentials are examined using the eigenphase representation. Taking the example of ${\Omega }^{\pi }=1/2^{+}$ levels, not only one-particle resonant levels but also all solutions in the eigenphase representation within a model space are studied. It is shown that a particular eigenphase solution among an infinite number of eigenphase solutions at a given energy plays a crucial role in producing low-lying one-particle resonance, whereas for the excitation energy lower than a few MeV the eigenphase sum is almost equal to the particular eigenphase when the sum is expressed by the value $\mathit{mod}n\pi$. Some one-particle resonant levels defined in terms of eigenphase, which have no correspondence to any bound one-particle levels, are found and discussed. It is shown that the relative probability of the $s_{1/2}$ component estimated using the probabilities inside the Woods-Saxon potentials is a decisive factor for obtaining one-particle resonant levels as a continuation of weakly bound ${\Omega }^{\pi }=1/2^{+}$ levels.

Excited states in the deformed nucleus ${}^{168}\mathrm{Er}$ have been studied with high-energy resolution, in the ($p,t$) reaction, with the Munich Q3D spectrograph. A number of 25 excited $0{}^{+}$ states (four tentative) and $632^{+}$ states have been assigned up to 4.0 MeV excitation energy. This unusually rich characterization of the $0{}^{+}$ and $2{}^{+}$ states in a deformed nucleus, close to a complete level scheme, offers a unique opportunity to check, in detail, models of nuclear structure that incorporate many excitation modes. A comparison of the experimental data is made with two such models: the quasiparticle-phonon model (QPM), and the projected shell model (PSM). The PSM wave functions appear to contain fewer correlations than those of the QPM and than required by the data.

Excitation functions were measured for the reactions ${}^{196}\mathrm{Hg}$($n$, $2n)$${}^{195}\mathrm{Hg}$${}^{m,g},$${}^{198}\mathrm{Hg}$($n$, $2n)$${}^{197}\mathrm{Hg}$${}^{m,g},$${}^{204}\mathrm{Hg}$($n$, $2n)$${}^{203}\mathrm{Hg}$,${}^{198}\mathrm{Hg}$($n,p)$${}^{198}\mathrm{Au}$${}^g$, and ${}^{199}\mathrm{Hg}$($n,p)$${}^{199}\mathrm{Au}$ over the neutron energy range of 7.6–12.5 MeV. Quasimonoenergetic neutrons were produced via the ${}^2\mathrm{H}$($d,n)$${}^3\mathrm{He}$ reaction using a deuterium gas target at the Jülich variable energy compact cyclotron CV 28. Use was made of the activation technique in combination with high-resolution, high-purity Ge detector $\gamma$-ray spectroscopy. All the data were measured for the first time over the investigated energy range. The transition from the present low-energy data to the literature data around 14 MeV is generally good. Nuclear model calculations using the codes STAPRE and EMPIRE-2.19, which employ the statistical and precompound model formalisms, were undertaken to describe the formation of both the isomeric and ground states of the products. The total reaction cross section of a particular channel is reproduced fairly well by the model calculations, with STAPRE giving slightly better results. Regarding the isomeric cross sections, the agreement between the experiment and theory is only in approximate terms. A description of the isomeric cross-section ratio by the model was possible only with a very low value of η, i.e., the ${\Theta }_{\text{eff}}$/${\Theta }_{\text{rig}}$ ratio.

We relate the fragmentation functions of partons into mesons and baryons in the framework of recombination of shower partons. The results are in reasonable agreement with the data. The implication is that the meson and baryon fragmentation functions are not independent when hadronization of the shower partons is taken into account. The conclusion therefore closes a conceptual gap in the system of fragmentation functions, whose $Q^2$ evolution has been more extensively studied than the interrelationship among various species of hadrons produced.

The jet shape modification due to partonic energy loss in the dense QCD matter is investigated with the help of the special transverse energy-energy correlator in the vicinity of maximum energy deposition of every event. In the accepted scenario with scattering of jet hard partons off comoving medium constituents this correlator is independent of the pseudorapidity position of a jet axis and becomes considerably broader (symmetrically over the pseudorapidity and the azimuthal angle) in comparison with $\mathit{pp}$-collisions. At scattering off “slow” medium constituents the broadening of correlation functions is dependent on the pseudorapidity position of a jet axis and increases noticeably in comparison with the previous scenario for jets with large enough pseudorapidities. These two considered scenarios result also in the different dependence of jet quenching on the pseudorapidity.

Properties of bottomonia ($\Upsilon ,{\chi }_b$, and ${\Upsilon }^{\text{'}}$) in the quark-gluon plasma (QGP) are investigated by assessing inelastic reaction rates and their interplay with open-bottom states ($b$ quarks or $B$ mesons) and color screening. The latter leads to vanishing quarkonium-binding energies at sufficiently high temperatures (close to the dissolution point), which, in particular, renders standard gluo-dissociation, $g+\Upsilon \to b+\overline{b}$, inefficient because of a substantial reduction in final-state phase space. This problem is overcome by invoking a “quasifree” destruction mechanism, $g,q,\overline{q}+\Upsilon \to g,q,\overline{q}+b+\overline{b}$, as previously introduced for charmonia. The pertinent reaction rates are implemented into a kinetic theory framework to evaluate the time evolution of bottomonia in heavy-ion reactions at the Relativistic Heavy Ion Collider and the CERN Large Hadron Collider within an expanding fireball model. Although bottom quarks are assumed to be exclusively produced in primordial nucleon-nucleon collisions, their thermal relaxation times in the QGP, which importantly figure into $\Upsilon$-formation rates, are estimated according to a recent Fokker-Planck treatment. Predictions for the centrality dependence of $\Upsilon$ production are given for upcoming experiments at RHIC and LHC. At both energies, $\Upsilon$ suppression turns out to be the prevalent effect.

Measurements of two-particle correlations on angular difference variables ${\eta }_1-{\eta }_2$ (pseudorapidity) and ${\varphi }_1-{\varphi }_2$ (azimuth) are presented for all primary charged hadrons with transverse momentum $0.15\le p_t\le 2$ GeV/$c$ and $\left|\eta \right|\le 1.3$ from Au-Au collisions at $\sqrt{s_{\mathit{NN}}}=130$ GeV. Large-amplitude correlations are observed over a broad range in relative angles where distinct structures appear on the same-side and away-side (i.e., relative azimuth less than $\pi /2$ or greater than $\pi /2$). The principal correlation structures include that associated with elliptic flow plus a strong, same-side peak. It is hypothesized that the latter results from correlated hadrons associated with semi-hard parton scattering in the early stage of the heavy-ion collision which produces a jet-like correlation peak at small relative angles. The width of the jet-like peak on ${\eta }_1-{\eta }_2$ increases by a factor 2.3 from peripheral to central collisions, suggesting strong coupling of semi-hard scattered partons to a longitudinally-expanding medium. The new methods of jet analysis introduced here provide access to scattered partons at low transverse momentum well below the kinematic range where perturbative quantum chromodynamics and standard fragmentation models are applicable.

We present a systematic study of the energy of vanishing flow by considering symmetric colliding nuclei (between ${}^{12}\mathrm{C}$ and ${}^{238}\mathrm{U}$) at normalized impact parameters using variety of equations of state (with and without momentum dependent interactions) as well as different nucleon-nucleon cross sections. A perfect power law mass dependence is obtained in all the cases which passes through calculated points nicely. Further, the choice of impact parameter affects the energy of vanishing flow drastically, demanding a very accurate measurement of the impact parameter. However, the energy of vanishing flow is less sensitive towards the equation of state as well as its momentum dependence.

The delayed x-ray detection technique was used to measure complete and incomplete fusion cross sections for the ${}^9\mathrm{Be}+{}^{144}\mathrm{Sm}$ reaction at sub- and near-barrier energies. Elastic and inelastic scattering for this system were also measured. Reaction cross sections were derived and the transfer cross sections of one neutron were calculated. The suppression of complete fusion above the barrier, of the order of 10%, is attributed to ${}^9\mathrm{Be}$ breakup and is considerably smaller than the value of 30% found for the ${}^9\mathrm{Be}+{}^{208}\mathrm{Pb}$ system.

The energy dependence of photofission cross section for heavy nuclei has recently been well described in terms of a Monte Carlo calculation at energies from the pion photoproduction threshold up to 1 GeV [see, for instance, A. Deppman et al., Phys. Rev. Lett. 87 (2001) 182701]. Recent experimental data from CLAS (CEBAF Large Angle Spectrometer) collaboration have extended the measured photofission cross section up to 3.5 GeV for actinide and preactinide nuclei. In this work we address the calculation of photoabsorption and photofission cross sections for actinide and preactinide nuclei above 1 GeV, a region where the shadowing effect plays an important role in the nuclear photoabsorption process.

Previously defined spin-dependent quark densities that are matrix elements of specific density operators in proton states of definite spin-polarization generally have an infinite variety of nonspherical shapes. The present application is concerned with both charge and matter densities. We show that the Gross and Agbakpe model nucleon harbors an interesting variety of nonspherical shapes.

We have developed a model to describe the interactions of neutrinos with nucleons and nuclei, focusing on the region of the quasielastic and $\Delta (1232)$ peaks. We describe neutrino-nucleon collisions with a fully relativistic formalism that incorporates state-of-the-art parametrizations of the form factors for both the nucleon and the $N-\Delta$ transition. The model has then been extended to finite nuclei, taking into account nuclear effects such as Fermi motion, Pauli blocking (both within the local density approximation), nuclear binding and final-state interactions. The in-medium modification of the Δ resonance because of Pauli blocking and collisional broadening have also been included. Final-state interactions are implemented by means of the Boltzmann-Uehling-Uhlenbeck (BUU) coupled-channel transport model. Results for charged current inclusive cross sections and exclusive channels as pion production and nucleon knockout are presented and discussed.

The recoil proton polarization was measured in the ${}^2\mathrm{H}$$(\overrightarrow{e},e^{\prime }\overrightarrow{p})n$ reaction in Hall A of the Thomas Jefferson National Accelerator Facility. The electron kinematics were centered on the quasielastic peak ($x_{\mathit{Bj}}\approx 1$) and included three values of the squared four-momentum transfer, $Q^2=0.43,1.00$ and 1.61 (GeV/$c){}^2$. For $Q^2=0.43$ and 1.61 (GeV/$c){}^2$, the missing momentum, $p_m$, was centered at zero, whereas for $Q^2=1.00(\mathrm{GeV}/c){}^2$ two values of $p_m$ were chosen: 0 and $174\mathrm{MeV}/c$. At low $p_m$, the $Q^2$ dependence of the longitudinal polarization, $P_z^{\prime }$, is not well described by a state-of-the-art calculation. Further, at higher $p_m$, a 3.5σ discrepancy was observed in the transverse polarization, $P_x^{\prime }$. Understanding the origin of these discrepancies is important to confidently extract the neutron electric form factor from the analogous ${}^2\mathrm{H}$$(\overrightarrow{e},e^{\prime }\overrightarrow{n})p$ experiment.

Recent discussions of RHIC data emphasized the exciting possibility that the matter produced in nucleus-nucleus collisions shows properties of a near-perfect fluid. Here, we aim at delineating the applicability of fluid dynamics, which is needed to quantify the size of corresponding dissipative effects. We start from the equations for dissipative fluid dynamics, which we derive from kinetic theory up to second order (Israel-Stewart theory) in a systematic gradient expansion. In model studies, we then establish that for too early initialization of the hydrodynamic evolution (${\tau }_0\lesssim 1\mathrm{fm}/c$) or for too high transverse momentum ($p_T\lesssim 1$ GeV) in the final state, the expected dissipative corrections are too large for a fluid description to be reliable. Moreover, viscosity-induced modifications of hadronic transverse momentum spectra can be accommodated to a significant degree in an ideal fluid description by modifications of the decoupling stage. We argue that these conclusions, drawn from model studies, can also be expected to arise in significantly more complex, realistic fluid dynamics simulations of heavy ion collisions.

We present a new and efficient method to obtain a Gamow shell-model basis and matrix elements generated by realistic nucleon-nucleon interactions. We derive a self-consistent Hartree-Fock potential from the renormalized N${}^3\mathrm{LO}$ interaction model. The corresponding Gamow one-body eigenstates are generated in a plane wave basis in order to build a Gamow shell-model set of basis states for the closed shell nuclei ${}^4\mathrm{He}$ and ${}^{16}\mathrm{O}$. We address also the problem of representing a realistic nucleon-nucleon interaction in a two-particle Berggren basis in the laboratory frame. To achieve this, an expansion of matrix elements of the residual nucleon-nucleon interaction in a finite set of harmonic oscillator wave functions is used. We show that all loosely bound and narrow resonant states converge surprisingly fast. Even broad resonances in these two-particle valence systems converge within a reasonable number of harmonic oscillator functions. Examples of ${}^6\mathrm{He}$ and ${}^{18}\mathrm{O}$ Gamow shell-model calculations using ${}^4\mathrm{He}$ and ${}^{16}\mathrm{O}$ as closed shell cores are presented. This procedure allows Gamow shell-model calculations to be performed with all realistic nucleon-nucleon interactions and with either momentum or position space representations for the Gamow basis. Perspectives for nuclear structure calculations of dripline nuclei are outlined.

Effects of the choice of the freeze-out hypersurface and resonance decays on the Hanbury-Brown–Twiss (HBT) interferometry in relativistic heavy-ion collisions are studied in detail within a class of models with single freeze-out. The Monte-Carlo method, as implemented in THERMINATOR, is used to generate hadronic events describing production of particles from a thermalized and expanding source. All well-established hadronic resonances are included in the analysis as their role is crucial at large freeze-out temperatures. We find that presence of the the short-lived resonances increase the pionic HBT radii by about 1 fm. We use the two-particle method to extract the correlation functions, which allows us to study the Coulomb effects. We find that the pion HBT data from the Relativistic Heavy Ion Collider are fully compatible with the single freeze-out scenario, pointing at the shape of the freeze-out hypersurface where the transverse radius is decreasing with time. Results for the single-particle spectra for this situation are also presented. Finally, we present predictions for the kaon femtoscopy.

We calculate at two-loop order in chiral perturbation theory the electromagnetic corrections to the dominant two-pion exchange nucleon-nucleon interaction that is generated by the isoscalar $\pi N$ contact-vertex proportional to the large low-energy constant $c_3$. We find that the respective $2\pi \gamma$-exchange potential contains sizable isospin-breaking components which amount to about $-1\%$ of the strongly attractive isoscalar central $2\pi$-exchange potential. The typical value of these novel charge-independence and charge-symmetry breaking central potentials is 0.3 MeV at a nucleon distance of $r=m_{\pi }^{-1}=1.4$ fm. Our analytical result for this dominant $2\pi \gamma$-exchange interaction is in a form such that it can be easily implemented into phase-shift analyses and few-body calculations.

We investigate the helicity properties of the ejectile in quasielastic neutrino-induced nucleon-knockout reactions and consider the ${}^{12}\mathrm{C}$ target as a test case. A formalism based on a relativistic mean-field model is adopted. The influence of final-state interactions is evaluated within a relativistic multiple-scattering Glauber approximation model. Our calculations reveal that the nucleon helicity asymmetries $A_l$ in quasielastic $A(\nu ,N)$ and $A(\overline{\nu },N)$ reactions are hardly affected by medium corrections, as final-state interactions and off-shell ambiguities in the electroweak current operators. On the contrary, the values of $A_l$ in $A(\overline{\nu },N)$ processes are extremely sensitive to strange-quark contributions to the weak vector form factors.

The coefficients of different combinations of terms of the liquid drop model have been determined by a least square fitting procedure to the experimental atomic masses. The nuclear masses can also be reproduced using a Coulomb radius taking into account the increase of the ratio $R_0/A^{1/3}$ with increasing mass, the fitted surface energy coefficient remaining around 18 MeV.