25 research outputs found
General Analysis of Inflation in the Jordan frame Supergravity
We study various inflation models in the Jordan frame supergravity with a
logarithmic Kahler potential. We find that, in a class of inflation models
containing an additional singlet in the superpotential, three types of
inflation can be realized: the Higgs-type inflation, power-law inflation, and
chaotic inflation with/without a running kinetic term. The former two are
possible if the holomorphic function dominates over the non-holomorphic one in
the frame function, while the chaotic inflation occurs when both are
comparable. Interestingly, the fractional-power potential can be realized by
the running kinetic term. We also discuss the implication for the Higgs
inflation in supergravity.Comment: 16 pages, 1 figur
Evolution of suppression in Au+Au collisions from to 200 GeV
International audienceNeutral-pion, pi^0, spectra were measured at midrapidity (|y|<0.35) in Au+Au collisions at sqrt(s_NN) = 39 and 62.4 GeV and compared to earlier measurements at 200 GeV in the 1<p_T<10 GeV/c transverse-momentum (p_T) range. The high-p_T tail is well described by a power law in all cases and the powers decrease significantly with decreasing center-of-mass energy. The change of powers is very similar to that observed in the corresponding p+p-collision spectra. The nuclear-modification factors (R_AA) show significant suppression and a distinct energy dependence at moderate p_T in central collisions. At high p_T, R_AA is similar for 62.4 and 200 GeV at all centralities. Perturbative-quantum-chromodynamics calculations that describe R_AA well at 200 GeV, fail to describe the 39 GeV data, raising the possibility that the relative importance of initial-state effects and soft processes increases at lower energies. A conclusion that the region where hard processes are dominant is reached only at higher p_T, is also supported by the x_T dependence of the x_T-scaling power-law exponent
Low- direct-photon production in AuAu collisions at and 62.4 GeV
The measurement of direct photons from AuAu collisions at and 62.4 GeV in the transverse-momentum range Gev/ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon spectra for different center-of-mass energies and for different centrality selections at GeV is scaled with for . This scaling also holds true for direct-photon spectra from AuAu collisions at GeV measured earlier by PHENIX, as well as the spectra from PbPb at GeV published by ALICE. The scaling power seems to be independent of , center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to of 2 GeV/. The spectra have a local inverse slope increasing with of GeV/ in the range GeV/ and increasing to GeV/ for GeV/. The observed similarity of low- direct-photon production from to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission
Low- direct-photon production in AuAu collisions at and 62.4 GeV
The measurement of direct photons from AuAu collisions at and 62.4 GeV in the transverse-momentum range Gev/ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon spectra for different center-of-mass energies and for different centrality selections at GeV is scaled with for . This scaling also holds true for direct-photon spectra from AuAu collisions at GeV measured earlier by PHENIX, as well as the spectra from PbPb at GeV published by ALICE. The scaling power seems to be independent of , center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to of 2 GeV/. The spectra have a local inverse slope increasing with of GeV/ in the range GeV/ and increasing to GeV/ for GeV/. The observed similarity of low- direct-photon production from to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission
Low- direct-photon production in AuAu collisions at and 62.4 GeV
The measurement of direct photons from AuAu collisions at and 62.4 GeV in the transverse-momentum range Gev/ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon spectra for different center-of-mass energies and for different centrality selections at GeV is scaled with for . This scaling also holds true for direct-photon spectra from AuAu collisions at GeV measured earlier by PHENIX, as well as the spectra from PbPb at GeV published by ALICE. The scaling power seems to be independent of , center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to of 2 GeV/. The spectra have a local inverse slope increasing with of GeV/ in the range GeV/ and increasing to GeV/ for GeV/. The observed similarity of low- direct-photon production from to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission
Low- direct-photon production in AuAu collisions at and 62.4 GeV
The measurement of direct photons from AuAu collisions at and 62.4 GeV in the transverse-momentum range Gev/ is presented by the PHENIX collaboration at the Relativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon spectra for different center-of-mass energies and for different centrality selections at GeV is scaled with for . This scaling also holds true for direct-photon spectra from AuAu collisions at GeV measured earlier by PHENIX, as well as the spectra from PbPb at GeV published by ALICE. The scaling power seems to be independent of , center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to of 2 GeV/. The spectra have a local inverse slope increasing with of GeV/ in the range GeV/ and increasing to GeV/ for GeV/. The observed similarity of low- direct-photon production from to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission