14967522
A Possible Black Hole Background in c=1 Matrix Model
We propose a new space-time interpretation for c=1 matrix model with potential $V(x)=-x^{2}/2-\m^{2}/2x^{2}$. It is argued that this particular potential corresponds to a black hole background. Some related issues are discussed.
8953515
A remark on conformal anomaly and extrinsic geometry of random surfaces
Abstract In low dimensions, conformal anomaly has a profound influence on the critical behavior of random surfaces with extrinsic curvature rigidity 1/ α . We illustrate this by making a small D expansion of rigid random surfaces, where a non-trivial infrared fixed point is shown to exist. We speculate on the renormalization group flow diagram in the (α, D ) plane. We argue that the qualitative behavior of numerical simulations in D =3,4 could be understood on the basis of the phase diagram.
16052098
Three dimensional quantum chromodynamics
The subject of this talk is the study of the low energy behavior of three (2+1) dimensional Quantum Chromodynamics. We show the existence of a phase where parity is unbroken and the flavor group U(2n) is broken into a subgroup U(n)×U(n). We derive the low energy effective action for the theory and show that it has solitonic excitations with Fermi statistic, to be identified with the three dimensional ‘‘baryon’’. Finally, we study the current algebra for this effective action and we find a co‐homologically nontrivial generalization of Kac‐Moody algebras to three dimension.
122196952
A GKO Construction Based on a Path Integral Formulation of Gauged Wess-Zumino-Witten Actions
Abstract A path integral formulation of G/H conformal theories is presented, based on gauged Wess-Zumino-Witten actions. The conformal charge of the model is c = c G − c H , exactly as in the GKO construction. Ghost modes appear in the formalism as a result of gauge fixing. As a consequence, the holomorphic stress-tensor T ( z ) obtained in our construction has ghost contributions. We find T ( z )= T G − T H only for matrix elements of physical states which are also ghost free.
17778643
Asymptotic Freedom and Dirichlet String Theory
Fixed angle scattering at high energy in a string theory with boundaries satisfying Dirichlet conditions (Dirichlet strings) in D = 4 is shown to have logarithmic dependence on energy, in addition to the power-like behavior known before. High temperature free energy also depends logarithmically on temperature. Such a result could provide a matching mechanism between strings at long distance and asymptotic freedom at short distance, which is necessary for the reformulation of large-N QCD as a string theory. In order to reformulate the large-N QCD [1] as a string theory, assuming it is possible at all, we must find a string theory that contains only massive excitations (for pure QCD) and shares the characteristic features of asymptotic freedom, such as partonic behavior and logarithmic violation of scaling at high energy. The critical string theories we are mostly familiar with fail to meet theses two requirements: they contain massless gravitons and massless Yang-Mill particles, and fixed angle scattering falls off exponentially with total energy. Liouville theory [2] has been argued to be irrelevant for the problem of QCD [3], meanwhile the effective string picture advocated in [4], which without doubt is correct for long strings, has problems at short distances. Rigid strings [5] at first sight seem to give the right behavior at high energy and high temperature, but they have the wrong sign of free energy at high temperature as compared with QCD [6], and furthermore there are problems with unitarity [7]. Another simple yet non-trivial modification of short distance behavior of strings is to add world-sheet boundaries satisfying Dirichlet boundary conditions – each boundary is mapped to a single point in space-time and the position is then integrated over. Such a theory was originally proposed as an off-shell extension of closed string amplitudes [8]. Meanwhile the point-like states of the Dirichlet boundaries were proven to produce powerlike behavior of fixed angle scattering at high energy [9]. The point-like structure was then linked to partons. Developments of the Dirichlet string theory in modern language can be found in [10]. Recently Green [11] points out that at high temperature the Dirichlet boundaries produce a free energy similar to that of the large-N QCD found by Polchinski[6]. Namely, in QCD the free energy of a long string per unit length goes as μQCD(β)/L 2 ∼ − (β)N π2β4 , (1)
120535369
Massive higher spin from dimensional reduction of gauge fields
A unified treatment of symmetric and ''D-bein'' higher integer spin massive fields in arbitrary dimension is presented and illustrated with the generic cases of spins 3 and 4. The theories are uniformly generated from massless gauge systems in one higher dimension by Kaluza--Klein reduction. The origin and role of various auxiliary field formulations are thereby clarified in terms of the underlying gauge freedom. This treatment is compared with the construction of massive theories from gauge field actions in the same dimension. The general canonical formulation is also exhibited. copyright 1987 Academic Press, Inc.
94329078
Chiral Phase Transition Around the Tricritical Point
204978414
Evidence for the decay $B_c^+ \rightarrow J/\psi 3\pi^+ 2\pi^-$
Evidence is presented for the decay $B_c+\rightarrow J/\psi 3\pi^+2\pi^-$ using proton-proton collision data, corresponding to an integrated luminosity of 3fb$^{-1}$, collected with the LHCb detector. A signal yield of $32\pm8$ decays is found with a significance of 4.5 standard deviations. The ratio of the branching fraction of the $B_c^+\rightarrow J/\psi 3\pi^+ 2\pi^-$ decay to that of the $B_c^+ \rightarrow J/\psi \pi^+$ decay is measured to be $$ \frac{Br (B_c^+ \rightarrow J/\psi 3\pi^+2\pi^)}{Br (B_c^+ \rightarrow J/\psi \pi^+)} = 1.74\pm0.44\pm0.24, $$ where the first uncertainty is statistical and the second is systematic.
123017364
SPIN INTERACTION EFFECTS ON MOMENTUM CORRELATIONS FOR IDENTICAL FERMIONS EMITTED IN RELATIVISTIC HEAVY-ION COLLISIONS
The Hanbury-Brown and Twiss (HBT) effects predict a Bose–Einstein enhancement of the two-particle momentum correlations of identical bosons at small relative momentum. However, the parallel momentum correlations between identical fermions are less argued. The momentum correlations can be altered by many factors, among which the spin interaction effects are discussed in this paper. It is found that the spin interaction plays an important role on the momentum correlations of identical fermions. For spin triplet state, a full Fermi–Dirac suppression represents as expected. On the contrary, a fake Bose–Einstein enhancement shows up for spin singlet state. The measured momentum correlations of fermions could hence provide some hints of spin interactions between them if all other factors such as Coulomb interactions were removed. Spin interactions make it more complicated to extract physical information from momentum correlations between fermions.
42616
Thermal and nonthermal pion enhancements with chiral symmetry restoration
The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest order in a 1/N_c expansion is calculated as a function of temperature T and chemical potential mu. The thermal and nonthermal enhancements of pions generated by the decay before and after the freeze-out present only in the crossover region of the chiral symmetry transition. The strongest nonthermal enhancement is located in the vicinity of the endpoint of the first-order transition.
49574388
An analytic solution of hydrodynamic equations with source terms in heavy-ion collisions
The energy and baryon densities in heavy-ion collisions are estimated by analytically solving a (1+1)-dimensional hydrodynamical model with source terms. In particular, a competition between the energy and baryon sources and the expansion of the system is discussed in detail.