118538593
Weak coupling large-N transitions at finite baryon density
A bstractWe study thermodynamics of free SU(N) gauge theory with a large number of colours and flavours on a three-sphere, in the presence of a baryon number chemical potential. Reducing the system to a holomorphic large-N matrix integral, paying specific attention to theories with scalar flavours (squarks), we identify novel third-order deconfining phase transitions as a function of the chemical potential. These transitions in the complex large-N saddle point configurations are interpreted as “melting” of baryons into (s)quarks. They are triggered by the exponentially large (~eN) degeneracy of light baryon-like states, which include ordinary baryons, adjoint-baryons and baryons made from different spherical harmonics of flavour fields on the three-sphere. The phase diagram of theories with scalar flavours terminates at a phase boundary where baryon number diverges, representing the onset of Bose condensation of squarks.
18863456
Out of Equilibrium Fields in Inflationary Dynamics. Density Fluctuations
The energy and time scales during the inflationary stage of the universe calls for an out of equilibrium quantum field treatment. Moreover, the high energy densities involved (∼1/g ∼ 1012) make necessary the use of non-perturbative approaches as the large N and Hartree methods. We start these lectures by introducing the such non-perturbative out of equilibrium methods in cosmological universes. We discuss the renormalization procedure and the choice of initial conditions. We then study with these methods the non-linear dynamics of quantum fields in matter and radiation dominated FRW and de Sitter universes. For a variety of initial conditions, we compute the evolution of the inflaton, its quantum fluctuations and the equation of state. We investigate the phenomenon of explosive particle production due to spinodal instabilities and parametric amplification in FRW and de Sitter universes with and without symmetry breaking. We find that the particle production is somewhat sensitive to the expansion of the universe. In the large N limit for symmetry breaking scenarios, we determine generic late time fields behavior for any flat FRW and de Sitter cosmology. We find that quantum fluctuations damp in FRW as the square of the scale factor while the order parameter approaches a minimum of the potential at the same rate. We present a complete and numerically accessible renormalization scheme for the equation of motion and the energy momentum tensor in flat cosmologies. In this scheme the renormalization constants are independent of time and of the initial conditions. Furthermore, we consider an O(N) inflaton model coupled self-consistently to gravity in the semiclassical approximation, where the field is subject to ‘new inflation’ type initial conditions. We study the dynamics self-consistently and non-perturbatively with non-equilibrium field theory methods in the large N limit. We find that spinodal instabilities drive the growth of non-perturbatively large quantum fluctuations which shut off the inflationary growth of the scale factor. We find that a very specific combination of these large fluctuations plus the inflaton zero mode assemble into a new effective field. This new field behaves classically and it is the object which actually rolls down. We show how this reinterpretation qualitatively saves the standard picture of how metric perturbations are generated during inflation and that the spinodal growth of fluctuations dominates the time dependence of the Bardeen variable for superhorizon modes during inflation. We compute the amplitude and index for the spectrum of scalar density and tensor perturbations and argue that in all models of this type the spinodal instabilities are responsible for a ‘red’ spectrum of primordial scalar density perturbations. The decoherence aspects and the quantum to classical transition through inflation are studied in detail by following the full evolution of the density matrix.
17544914
Precision test of AdS/CFT in Lunin-Maldacena background
We obtain the solutions and explicitly calculate the energy for a class of two-spin semiclassical string states in the Lunin-Maldacena background. These configurations are the β-deformed versions of the folded string solutions in AdS5 × S5 background. They correspond to certain single trace operators in the = 1 superconformal β deformation of = 4 Yang-Mills. We calculate the one loop anomalous dimension for the dual single trace operators from the associated twisted spin chain with a general two-cut distribution of Bethe roots. Our results show a striking match between the two calculations. We demonstrate the natural identification of parameters on the two sides of the analysis, and explain the significance of the Virasoro constraint associated with the winding motion of semiclassical strings from the perspective of the spin chain solution.
59440238
Vacuum structure and flavor symmetry breaking in supersymmetric SO(nc) gauge theories
We determine the vacuum structure and phases of N=1 theories obtained via a 
mass \mu for the adjoint chiral superfield in N=2, SO(n_c) SQCD. For large 
number of flavors these theories have two groups of vacua. The first exhibits 
dynamical breaking of flavor symmetry \USp(2n_f) \to U(n_f) and arises as a 
relevant deformation of a non-trivial superconformal theory. These are in the 
confined phase. The second group, in an IR-free phase with unbroken flavor 
symmetry, is produced from a Coulomb branch singularity with Seiberg's dual 
gauge symmetry. In the large-\mu regime both groups of vacua are well-described 
by dual quarks and mesons, and dynamical symmetry breaking in the first group 
occurs via meson condensation. We follow the description of these vacua from 
weak to strong coupling and demonstrate a nontrivial agreement between the 
phases and the number of vacua in the two regimes. We construct the 
semiclassical monopole flavor multiplets and argue that their multiplicity is 
consistent with the number of N=1 vacua.
15505916
Exact Superpotentials from Matrix Models
Dijkgraaf and Vafa (DV) have conjectured that the exact superpotential for a large class of = 1 SUSY gauge theories can be extracted from the planar limit of a certain holomorphic matrix integral. We test their proposal against existing knowledge for a family of deformations of = 4 SUSY Yang-Mills theory involving an arbitrary polynomial superpotential for one of the three adjoint chiral superfields. Specifically, we compare the DV prediction for these models with earlier results based on the connection between SUSY gauge theories and integrable systems. We find complete agreement between the two approaches. In particular we show how the DV proposal allows the extraction of the exact eigenvalues of the adjoint scalar in the confining vacuum and hence computes all related condensates of the finite-N gauge theory. We extend these results to include Leigh-Strassler deformations of the = 4 theory.
5243610
Non-Abelian Vortices at Weak and Strong Coupling in Mass Deformed ABJM Theory
We find half-BPS vortex solitons, at both weak and strong coupling, in the = 6 supersymmetric mass deformation of ABJM theory with U(N) × U(N) gauge symmetry and Chern-Simons level k. The strong coupling gravity dual is obtained by performing a k quotient of the = 8 supersymmetric eleven dimensional supergravity background of Lin, Lunin and Maldacena corresponding to the mass deformed M2-brane theory. At weak coupling, the BPS vortices preserving six supersymmetries are found in the Higgs vacuum of the theory where the gauge symmetry is broken to U(1) × U(1). The classical vortex solitons break a colour-flavour locked global symmetry resulting in non-Abelian internal orientational moduli and a CP1 moduli space of solutions. At strong coupling and large k, upon reduction to type IIA strings, the vortex moduli space and its action are computed by a probe D0-brane in the dual geometry. The mass of the D0-brane matches the classical vortex mass. However, the gravity picture exhibits a six dimensional moduli space of solutions, a section of which can be identified as the CP1 we find classically, along with a Dirac monopole connection of strength k. It is likely that the extra four dimensions in the moduli space are an artifact of the strong coupling limit and of the supergravity approximation.
118517206
Boson stars in a theory of complex scalar fields coupled to the U(1) gauge field and gravity
We study boson shells and boson stars in a theory of a complex scalar field coupled to the gauge field and Einstein gravity with the potential . This could be considered either as a theory of a massive complex scalar field coupled to an electromagnetic field and gravity in a conical potential, or as a theory in the presence of a potential that is an overlap of a parabolic and conical potential. Our theory has a positive cosmological constant . Boson stars are found to come in two types, having either ball-like or shell-like charge density. We studied the properties of these solutions and also determined their domains of existence for some specific values of the parameters of the theory. Similar solutions have also been obtained by Kleihaus, Kunz, Laemmerzahl and List, in a V-shaped scalar potential.
118403162
αdecay chains study for the recently observed superheavy elementZ=117within the isospin cluster model
The recently observed $\alpha$-decay chains $^{293-294}117$ were produced by the fusion reactions with target $^{249}Bk$ and projectile $^{48}Ca$ at Dubna in Russia. The reported cross-sections for the mentioned reaction are $\sigma=0.5(+1.1,-0.4)$pb and $\sigma$=1.3(+1.5,-0.6)$pb$ at $E^{*}=35MeV$ and $E^{*}=39MeV$, respectively. The Q-values of $\alpha$-decay and the half-lives $Log_{10}T^{\alpha}_{1/2}$(s) are calculated for the $\alpha$-decay chains of $^{293-294}117$ nuclei, within the framework of Isospin Cluster Model (ICM). In the ICM model the proximity energy is improved by using the isospin dependent radius of parent, daughter and alpha particle. The binding energy $B(A_{i}, Z_{i})$ (i=1,2) of any nucleus of mass number A and atomic number Z was obtained from a phenomenological and more genaralized BW formula given by \cite{samanta02}. The calculated results in ICM are compared with the experimental results and other theoretical Macro-Microscopic(M-M), RMF(with NL3 and SFU Gold forces parameter) model calculations. The estimated values of $\alpha$-decay half-lives are in good agreement with the recent data. The ICM calculation is in favor of the persence of magic number at N=172.
116623275
Experimental study of nuclei in the vicinity of the 'island of inversion' through the fusion-evaporation reaction
We report the observation of high-spin states in nuclei in the vicinity of the 'island of inversion', populated via the {sup 18}O+{sup 18}O fusion reaction at an incident beam energy of 34 MeV. The fusion reaction mechanism circumvents the limitations of other reactions used so far to populate excited states in these nuclei. The level structures of {sup 33,34}P and {sup 33}S have been investigated and their level schemes were substantially extended. The intensities and branching ratios of the {gamma} transitions were measured. The observed {gamma} coincidence intensity anisotropy and polarization asymmetry were analyzed for a consistent assignment of the spins and parities of the nuclear levels. The 1876-keV transition in {sup 34}P that had an ambiguous multipolarity assignment has been confirmed to be a mixed transition. Truncated (1p-1h) shell model calculations within the 'sdpf' valence space were performed. These calculations reproduce the experimental excitation energies of {sup 34}P but fail to explain the observed mixing ratio for the 1876-keV transition.
73552991
Pb-Radioactivity in superheavy elements
A study on exotic natural radioactivity of emitting nuclei heavier than α-particle, known as cluster radioactivity. Theoretically, it was predicted in 1980 by Săndulescu, Poenaru and Greiner [1]. Later it was confirmed experimentally by Rose and Jones in 1984 [2] via the 14 C decay from 223 Ra nucleus. Since then many other 14 C-decays from other radioactive nuclei ( 221 Fr, 221,222,224,226 Ra, 223,225 Ac) and some other neutron rich clusters, such as 20 O, 23 F, 22,24-
120097279
Thirring fermions at high temperature
A Green's-function method is used to study the thermodynamic properties of self-interacting massless dimension and one time dimension. It is shown that the exact expression can be obtained for the thermodynamic one-particle Green's function for the case where the dimensionless chemical potential $mu$ = 0, which is identical with the corresponding field-theoretic Green's function. The number density is obtained as an infinite sum. It exhibits a peculiar peaked behavior as a function of momentum. The energy, however, is a continuous function of temperature. (AIP)