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.
123152633
Energy and Stability in Einstein-{Gauss-Bonnet} Models
A unified energy expression for Einstein-Gauss-Bonnet gravity, valid about the model's two distinct vacua, is obtained. It reduces to the usual Einstein form about a flat background, but about an anti-de Sitter vacuum it becomes that appropriate to a ghost Einstein theory with a cosmological term. Linearisation instability about the latter and general stability about the former are deduced by energy considerations, in agreement with previous results.
116802431
Topics in field theory-higher spins, CFT, and gravity
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.
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.
14945328
High-temperature partition function of the rigid string.
We find that the high-temperature limit of the free energy per unit length for the rigid string agrees dimensionally with that of the QCD string (unlike the Nambu-Goto string). The sign, and in fact the phase, do not agree. While this may be a clue to a string theory of QCD, we note that the problem of the fourth-derivative action makes it impossible for the rigid string to be a correct description.
94329078
Chiral Phase Transition Around the Tricritical Point
18491403
Study of beauty hadron decays into pairs of charm hadrons
First observations of the decays Λb 0 → Λc +D(s) - are reported using data corresponding to an integrated luminosity of 3fb-1 collected at 7 and 8 TeV center-of-mass energies in proton-proton collisions with the LHCb detector. In addition, the most precise measurement of the branching fraction B(Bs 0→D+Ds -) is made and a search is performed for the decays B(s) 0→Λc +Λc -. The results obtained are B(Λb 0→Λc +D-)/ B(Λb 0→Λc +D s -)=0.042±0.003(stat)±0.003(syst), [B(Λb 0→Λc +D s -)/B(B0→D+D s -)]/[B(Λb 0→Λ c +π-)/B(B0→D +π-)]=0.96±0.02(stat)±0.06(syst),B(B s 0→D+Ds -)/ B(B0→D+Ds -)=0. 038±0.004(stat)±0.003(syst),B(B0→Λ c +Λc -)/B(B 0→D+Ds -)<0.0022[95%C.L.], B(Bs 0→Λc +Λ c -)/B(Bs 0→D+D s -)<0.30[95%C.L.]. Measurement of the mass of the Λb 0 baryon relative to the B0 meson gives M(Λb 0)-M(B0)=339. 72±0.24(stat)±0.18(syst)MeV/c2. This result provides the most precise measurement of the mass of the Λb 0 baryon to date.
197461694
Evidence for the decay $X(3872)\rightarrow\psi(2S)\gamma$
Evidence for the decay mode $X(3872)\rightarrow\psi(2S)\gamma$ in $B^+\rightarrow X(3872)K^+$ decays is found with a significance of 4.4 standard deviations. The analysis is based on a data sample of proton-proton collisions, corresponding to an integrated luminosity of 3fb$^{-1}$ collected with the LHCb detector, at centre-of-mass energies of 7 and 8TeV. The ratio of the branching fraction of the $X(3872)\to\psi(2S)\gamma$ decay to that of the $X(3872)\rightarrow J/\psi \gamma$ decay is measured to be $$ \frac{Br(X(3872)\rightarrow\psi(2S)\gamma)}{Br(X(3872)\rightarrow J/\psi\gamma)} = 2.46\pm0.64\pm0.29, %\pm0.06,$$ where the first uncertainty is statistical and the second is systematic. The measured value agrees with expectations for a pure charmonium interpretation of the $X(3872)$ state and a mixture of charmonium and molecular interpretations. However, it does not support a pure $D\bar{D}^{*}$ molecular interpretation of the $X(3872)$state.
54960779
Measurement of the resonant and CP components in $\overline{B}^0\to J/\psi \pi^+\pi^-$ decays
The resonant structure of the reaction $\overline{B}^0\rightarrow J/\psi \pi^+\pi^-$ is studied using data from 3 fb$^{-1}$ of integrated luminosity collected by the LHCb experiment, one-third at 7 Tev center-of-mass energy and the remainder at 8 Tev. The invariant mass of the $\pi^+\pi^-$ pair and three decay angular distributions are used to determine the fractions of the resonant and non-resonant components. Six interfering $\pi^+\pi^-$ states: $\rho(770)$, $f_0(500)$, $f_2(1270)$, $\rho(1450)$, $\omega(782)$ and $\rho(1700)$ are required to give a good description of invariant mass spectra and decay angular distributions. The positive and negative CP fractions of each of the resonant final states are determined. The $f_0(980)$ meson is not seen and the upper limit on its presence, compared with the observed $f_0(500)$ rate, is inconsistent with a model of tetraquark substructure for these scalar mesons at the eight standard deviation level. In the $q\overline{q}$ model, the absolute value of the mixing angle between the $f_0(980)$ and the $f_0(500)$ scalar mesons is limited to be less than $17^{\circ}$ at 90% confidence level.
119362042
Deconfinement phase transition in an expanding quark system in the relaxation time approximation
We investigated the effects of nonequilibrium and collision terms on the deconfinement phase transition of an expanding quark system in Friedberg-Lee model in relaxation time approximation. By calculating the effective quark potential, the critical temperature of the phase transition is dominated by the mean field, while the collisions among quarks and mesons change the time structure of the phase transition significantly.