We introduce a method based on chiral susceptibility, which enables one to draw a phase diagram in the chemical-potential–temperature plane for strongly interacting quarks whose interactions are described by any reasonable gap equation, even if the diagrammatic content of the quark-gluon vertex is unknown. We locate a critical end point at $({\mu }^E,T^E)\sim (1.0,0.9)T_c$, where $T_c$ is the critical temperature for chiral-symmetry restoration at $\mu =0$, and find that a domain of phase coexistence opens at the critical end point whose area increases as a confinement length scale grows.

The structure of ${}^{15}\mathrm{C}$, with an $s_{1/2}$ neutron weakly bound to a closed-neutron shell nucleus ${}^{14}\mathrm{C}$, makes it a prime candidate for a one-neutron halo nucleus. We have for the first time studied the cross section for the fusion-fission reaction ${}^{15}\mathrm{C}+{}^{232}\mathrm{Th}$ at energies in the vicinity of the Coulomb barrier and compared it to the yield of the neighboring ${}^{14}\mathrm{C}+{}^{232}\mathrm{Th}$ system measured in the same experiment. At sub-barrier energies, an enhancement of the fusion yield by factors of 2–5 was observed for ${}^{15}\mathrm{C}$, while the cross sections for ${}^{14}\mathrm{C}$ match the trends measured for ${}^{12,13}\mathrm{C}$.

Absolute cross sections have been determined following single neutron knockout reactions from ${}^{10}\mathrm{Be}$ and ${}^{10}\mathrm{C}$ at intermediate energy. Nucleon density distributions and bound-state wave function overlaps obtained from both variational Monte Carlo (VMC) and no core shell model (NCSM) ab initio calculations have been incorporated into the theoretical description of knockout reactions. Comparison to experimental cross sections demonstrates that the VMC approach, with the inclusion of 3-body forces, provides the best overall agreement while the NCSM and conventional shell-model calculations both overpredict the cross sections by 20% to 30% for ${}^{10}\mathrm{Be}$ and by 40% to 50% for ${}^{10}\mathrm{C}$, respectively. This study gains new insight into the importance of 3-body forces and continuum effects in light nuclei and provides a sensitive technique to assess the accuracy of ab initio calculations for describing these effects.

A possibility of the amplification of the 7.6 eV $\gamma$ radiation by the stimulated $\gamma$ emission of the ensemble of the ${}^{229m}\mathrm{Th}$ isomeric nuclei in a host dielectric crystal is proved theoretically. This amplification is a result of (1) the excitation of a large number of ${}^{229m}\mathrm{Th}$ isomers by laser radiation, (2) the creation of the inverse population of nuclear levels in a cooled sample owing to the interaction of thorium nuclei with the crystal electric field or with an external magnetic field, (3) the emission or absorption of the optical photons by thorium nuclei in the crystal without recoil, and (4) the nuclear spin relaxation through the conduction electrons of the metallic covering.

Within the AMPT Monte Carlo model, fluctuations in the initial transverse parton density are shown to lead to harmonic flows. The net back-to-back dihadron azimuthal correlation after subtraction of contributions from harmonic flows still has a double peak that is independent of the initial geometric triangularity and unique to the jet-induced Mach cone and expanding hot spots distorted by radial flow. The longitudinal structure of hot spots also leads to a nearside ridge in dihadron correlation with a large rapidity gap. By successively randomizing the azimuthal angle of the transverse momenta and positions of initial partons, one can isolate the effects of jet-induced medium excitation and expanding hot spots on the dihadron azimuthal correlation. The double peaks in the net dihadron and $\gamma$-hadron correlation are quantitatively different since the later is caused only by jet-induced Mach cone.

We investigate the medium modification of a partonic jet shower traversing in a hot quark-gluon plasma. We derive and solve a differential equation that governs the evolution of the radiated gluon distribution as the jet propagates through the medium. Energy contained inside the jet cone is lost by dissipation through elastic collisions with the medium and by scattering of shower partons to larger angles. We find that the jet energy loss at early times is dominated by medium effects on the vacuum radiation, and by medium-induced radiation effects at late times. We compare our numerical results for the nuclear modification of the dijet asymmetry with that recently reported by the ATLAS Collaboration.

High precision measurements of the differential cross sections for ${\pi }^0$ photoproduction at forward angles for two nuclei, ${}^{12}\mathrm{C}$ and ${}^{208}\mathrm{Pb}$, have been performed for incident photon energies of 4.9–5.5 GeV to extract the ${\pi }^0\to \gamma \gamma$ decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The ${\pi }^0\to \gamma \gamma$ decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is $\Gamma ({\pi }^0\to \gamma \gamma )=7.82\pm 0.14(\mathrm{stat})\pm 0.17(\mathrm{syst})\mathrm{eV}$. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current Particle Data Group average of this fundamental quantity, and it is consistent with current theoretical predictions.

A second-order supersymmetric transformation is presented, for the two-channel Schrödinger equation with equal thresholds. It adds a Breit-Wigner term to the mixing parameter, without modifying the eigenphase shifts, and modifies the potential matrix analytically. The iteration of a few such transformations allows a precise fit of realistic mixing parameters in terms of a Padé expansion of both the scattering matrix and the effective-range function. The method is applied to build an exactly solvable potential for the neutron-proton ${}^{3}S_1\mathrm{\text{−}}{}^{3}D_1$ case.

We study the sensitivity to variations in the triple-alpha and ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ reaction rates, of the yield of the neutrino-process isotopes ${}^7\mathrm{Li}$, ${}^{11}\mathrm{B}$, ${}^{19}\mathrm{F}$, ${}^{138}\mathrm{La}$, and ${}^{180}\mathrm{Ta}$ in core-collapse supernovae. Compared to solar abundances, less than 15% of ${}^7\mathrm{Li}$, about 25%–80% of ${}^{19}\mathrm{F}$, and about half of ${}^{138}\mathrm{La}$ is produced in these stars. Over a range of $\pm 2\sigma$ for each helium-burning rate, ${}^{11}\mathrm{B}$ is overproduced and the yield varies by an amount larger than the variation caused by the effects of neutrino oscillations. The total ${}^{11}\mathrm{B}$ yield, however, may eventually provide constraints on supernova neutrino spectra.

Although nuclear fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the fission-fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.

Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_E/G_M$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\overrightarrow{e},e^{\prime }\overrightarrow{p})$ reaction for three different beam energies at a $Q^2=2.5{\mathrm{GeV}}^2$, spanning a wide range of the kinematic parameter $ϵ$. The ratio $R$, which equals ${\mu }_p{G}_E/G_M$ in the Born approximation, is found to be independent of $ϵ$ at the 1.5% level. The $ϵ$ dependence of the longitudinal polarization transfer component $P_{\ell }$ shows an enhancement of $(2.3\pm 0.6)\%$ relative to the Born approximation at large $ϵ$.

The superallowed $\beta$-decay rates that provide stringent constraints on physics beyond the standard model of particle physics are affected by nuclear structure effects through isospin-breaking corrections. The self-consistent isospin- and angular-momentum-projected nuclear density functional theory is used for the first time to compute those corrections for a number of Fermi transitions in nuclei from $A=10$ to $A=74$. The resulting leading element of the Cabibbo-Kobayashi-Maskawa matrix, $|V_{\mathrm{ud}}|=0.97447(23)$, agrees well with the recent result of Towner and Hardy [Phys. Rev. C 77, 025501 (2008)].

We perform a global ${\chi }^2$ analysis of nuclear parton distribution functions using data from charged current neutrino-nucleus ($\nu A$) deep-inelastic scattering (DIS), charged-lepton–nucleus (${\ell }^{\pm }A$) DIS, and the Drell-Yan (DY) process. We show that the nuclear corrections in $\nu A$ DIS are not compatible with the predictions derived from ${\ell }^{\pm }A$ DIS and DY data. We quantify this result using a hypothesis-testing criterion based on the ${\chi }^2$ distribution which we apply to the total ${\chi }^2$ as well as to the ${\chi }^2$ of the individual data sets. We find that it is not possible to accommodate the data from $\nu A$ and ${\ell }^{\pm }A$ DIS by an acceptable combined fit. Our result has strong implications for the extraction of both nuclear and proton parton distribution functions using combined neutrino and charged-lepton data sets.

At second order in gradients, conformal relativistic hydrodynamics depends on the viscosity $\eta$ and on five additional “second-order” hydrodynamical coefficients ${\tau }_{\Pi }$, $\kappa$, ${\lambda }_1$, ${\lambda }_2$, and ${\lambda }_3$. We derive Kubo relations for these coefficients, relating them to equilibrium, fully retarded three-point correlation functions of the stress tensor. We show that the coefficient ${\lambda }_3$ can be evaluated directly by Euclidean means and does not in general vanish.

A zeptosecond multi-MeV laser pulse may either excite a “plasma” of strongly interacting nucleons or a collective mode. We derive the conditions on laser energy and photon number such that either of these scenarios is realized. We use the nuclear giant dipole resonance as a representative example, and a random-matrix description of the fine-structure states and perturbation theory as tools.

The masses of ten proton-rich nuclides, including the $N=Z+1$ nuclides ${}^{85}\mathrm{Mo}$ and ${}^{87}\mathrm{Tc}$, were measured with the Penning trap mass spectrometer SHIPTRAP. Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass surface by up to 1.6 MeV is observed causing significant abundance changes of the ashes of astrophysical x-ray bursts. Surprisingly low $\alpha$ separation energies for neutron-deficient Mo and Tc are found, making the formation of a ZrNb cycle in the $rp$ process possible. Such a cycle would impose an upper temperature limit for the synthesis of elements beyond Nb in the $rp$ process.

Mass excesses of short-lived $A=2Z-1$ nuclei ${}^{63}\mathrm{Ge}$, ${}^{65}\mathrm{As}$, ${}^{67}\mathrm{Se}$, and ${}^{71}\mathrm{Kr}$ have been directly measured to be $-46921(37)$, $-46937(85)$, $-46580(67)$, and $-46320(141)\mathrm{keV}$, respectively. The deduced proton separation energy of $-90(85)\mathrm{keV}$ for ${}^{65}\mathrm{As}$ shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of ${}^{65}\mathrm{As}$ suggest that the majority of the reaction flow passes through ${}^{64}\mathrm{Ge}$ via proton capture, indicating that ${}^{64}\mathrm{Ge}$ is not a significant $rp$-process waiting point.

The Balian-Vénéroni (BV) variational principle, which optimizes the evolution of the state according to the relevant observable, is used at the mean-field level to determine the particle-number fluctuations in fragments of many-body systems. For fermions, the numerical evaluation of such fluctuations requires the use of a time-dependent Hartree-Fock (TDHF) code. Proton, neutron, and total nucleon number fluctuations in fragments produced in collisions of two ${}^{40}\mathrm{Ca}$ are computed well above the fusion barrier. For deep-inelastic collisions, the fluctuations calculated from the BV variational principle are much larger than standard TDHF results, and closer to experimental fluctuations. Correlations between proton and neutron numbers are determined. These correlations are shown to be larger with exotic systems where charge equilibration occurs.

It was recently shown that fluctuations in the initial geometry of a heavy-ion collision generally result in a dipole asymmetry of the distribution of outgoing particles. This asymmetry, unlike the usual directed flow, is expected to be present at a wide range of rapidity—including midrapidity. The first evidence of this phenomenon can be seen in recent two-particle correlation data by the STAR Collaboration, providing the last element necessary to quantitatively describe long-range dihadron correlations. We extract differential directed flow from these data and propose a new direct measurement.

The coupling of the giant quadrupole resonance to valence-space configurations is shown to be the origin of the formation of low-lying quadrupole-collective structures in vibrational nuclei with symmetric and mixed-symmetric character with respect to the proton-neutron degree of freedom. For the first time experimental evidence for this picture is obtained from electron- and proton scattering experiments on the nucleus ${}^{92}\mathrm{Zr}$ that are sensitive to the relative phase of valence-space amplitudes by quantum interference.