124365920
A statistical model analysis of the rapidity distribution of hadrons
45880759
Strange matter lumps in the early Universe.
We study the stability of hot strange matter lumps formed in the early Universe. As the Universe cools below the hadronization temperature, these lumps normally become unstable against boiling. They can stabilize themselves against this process if their mass is sufficiently large to hold a hadronic crust by gravitational attraction. Our analysis improves on previous studies of the internal structure of such stable hot quark matter lumps with hadronic crust by correctly treating the constraints from chemical equilibrium of baryonic and electric charge between crust and core. Since the expansion rate of the early Universe is much faster than the cooling rate of the strange matter lumps, their internal structure is characterized by constant entropy per baryon. Our improved analysis confirms the earlier finding that such stable quark matter lumps require a mass well above the total mass inside the horizon.
121511469
The ϱ-peak in the dimuon spectrum as a clock for fireball lifetimes in relativistic nuclear collisions
Abstract We discuss the modification of the dipleton yield from vector mesons inside a nuclear fireball. We argue that the relative magnitude of the ϱ peak in the dilepton spectrum determines the lifetime of the hadron gas phase in nuclear collisions with an accuracy of about 1 fm/ c . We also find that the φ (ω + ϱ) ratio measured in the dimuon channel in 200 A GeV O + U and S + U collisions points towards a rather short-lived hadronic phase in these collisions.
46431416
Energy spectra of strange particles hadronizing from a quark-gluon plasma.
Using a schematic hydrodynamic description of relativistic heavy-ion collisions in the regime of complete nuclear stopping, we study the freeze-out and strange particle energy spectra from a hadronized quark-gluon plasma. We argue that characteristic changes in the slopes of the ${\mathrm{K}}^{+}$ and ${\mathrm{K}}^{\mathrm{\ensuremath{-}}}$ meson energy spectra are a signature for the quark-gluon plasma phase transition.
118425306
Two freeze-out model for the hadrons produced in the Relativistic Heavy-Ion Collisions
An expanding fireball model with two freeze-outs, which assumes that the chemical freeze-out occurs earlier at higher temperature and the thermal freeze-out occurs later at lower temperature, is developed and successfully applied to fit simultaneously the hadron ratios, transverse momentum spectra of measured hadrons and rapidity distribution of charged hadrons measured in Au+Au collision at 200 A·GeV by STAR, PHENIX and PHOBOS collaborations. The quality of all the fittings is very good and the resulting parameters are in agreement with published values.
119332767
Analysis of Low-Energy Pion Spectra
The transverse mass spectra and the rapidity distributions of $\pi^+$ and $\pi^-$ in Au-Au collisions at 2, 4, 6, and 8 GeV$\cdot$A by E895 collaboration are fitted using an elliptically expanding fireball model with the contribution from the resonance decays and the final state Coulomb interaction. The ratio of the total number of produced $\pi^-$ and $\pi^+$ is used to fit the data. The resulting freeze-out temperature is rather low($T_f < 60$ MeV) with large transverse flow and thus resonance contribution is very small. The difference in the shape of $m_t$ spectra of the oppositely charged pions are found to be due to the Coulomb interaction of the pions.
17539215
Implications of the recent CERN LEP data on nonuniversal interactions with the precision electroweak tests
We explore the nonuniversal interaction effects in terms of the precision variables epsilons with the recent CERN LEP data reported by the Electroweak Working Group. The epsilon variables with the nonuniversal interactions are calculated and constrained by the experimental ellipses in the {epsilon}{sub 1}{endash}{epsilon}{sub b}, {epsilon}{sub 2}{endash}{epsilon}{sub b}, and {epsilon}{sub 3}{endash}{epsilon}{sub b} planes. We find that the new data enable us to make a stringent test on the correction to Z{r_arrow}b{bar b} vertex. The {epsilon}{sub b} variable is sensitive to the Zb{bar b} couplings and thus plays a major role to give constraints on the nonuniversal interaction effects. Upon imposing the new data on {epsilon}{sub b}, we have the allowed range of the model parameter {kappa}{sub L}=0.0063{plus_minus}0.0030 at 1-{sigma} level with m{sub t}=175 GeV. Along with the minimal contact term, we predict the new physics scale {Lambda}{approximately} 1.6 TeV. By combining the experimental results from all planes we obtain the allowed range of {kappa}{sub L}: 0.003{lt}{kappa}{sub L}{lt}0.010 at 95{percent} C.L. {copyright} {ital 1997} {ital The American Physical Society}
119542713
The parton model approach to inclusive B meson decays
Abstract We test the parton model approach to inclusive B → γXs and B → e ν X u processes by calculating a few moments of the distribution function. The 1 m Q expansion of the b-quark distribution function is discussed. We show that Peterson's fragmentation function is useful as the distribution function of the b-quark but requires some improvements. By extension of Peterson's arguments, we obtain the refined form for the distribution function and with the refined function, we obtain the consistent results with the HQET.
1381801
Probing the messenger of supersymmetry breaking by the muon anomalous magnetic moment
Motivated by the recently measured muon's anomalous magnetic moment $a_{\mu}$, we examine the supersymmetry contribution to $a_{\mu}$ in various mediation models of supersymmetry breaking which lead to predictive flavor conserving soft parameters at high energy scale. The studied models include dilaton/modulus-mediated models in heterotic string/$M$ theory, gauge-mediated model, no-scale or gaugino-mediated model, and also the minimal and deflected anomaly-mediated models. For each model, the range of $a^{SUSY}_{\mu}$ allowed by other experimental constraints, e.g. b --> s\gamma and the collider bounds on superparticle masses, is obtained together with the corresponding parameter region of the model. Gauge-mediated models with low messenger scale can give any $a^{SUSY}_{\mu}$ within the $2\sigma$ bound. In many other models, b --> s\gamma favors $a^{SUSY}_{\mu}$ smaller than either the $-1\sigma$ value ($26\times 10^{-10}$) or the central value ($42\times 10^{-10}$).
51543374
Unitarity violation of the CKM matrix in a nonuniversal gauge interaction model
We explore the unitarity violation of the Cabibbo-Kobayashi-Maskawa (CKM) matrix in the model where the third generation fermions are subjected to the separate SU(2){sub L} gauge interaction. With the recent LEP and SLAC linear collider (SLC) data at Z-pole and low-energy neutral current interaction data, the analysis on the parameter space of the model is updated, and the unitary violation is predicted under the constraint.
15490488
A Family of N=2 gauge theories with exact S duality
We study an infinite family of N = 2 Sp(2n) gauge theories that naturally arise from the D3-brane probe dynamics in F-theory. The matter sector consists of four fundamental and one antisymmetric tensor hypermultiplets. We propose that, in the limit of vanishing bare masses, the theory has exact SO(8) ⋉ SL(2, Z) duality. We examine the semiclassical BPS spectrum in the Coulomb phase by quantizing various monopole moduli space dynamics, and show that it is indeed consistent with the exact S-duality.