117272166
Analysis of Hadronic Properties at SPS energies from a Statistical Model
Using a statistical model of multiparticle production by Chou, Yang and Yen, which looks similar to the thermal model and is known to account for the single particle distributions in e$^+$ e$^-$ collisions, we fit the rapidity and transverse mass spectra of pions and kaons measured in Pb+Pb collisions by NA49 collaboration. This model nicely fits both the rapidity and the transverse mass spectra of each particle species with a few parameters. However, fitting all the particles with a single value of $T_p$ is not possible. This analysis shows that the success of the thermal models does not necessarily mean the thermalization of the system in collision.
122648978
Strangeness and hadronization from a quark-gluon plasma☆
Abstract From a phenomenological equation of state, the role of strangeness in the hadronizing QGP is studied. Even though strangeness abundance of the QGP is similar to that of an equilibrium hadron gas, the characteristic change in the slope of energy spectra of K + and K − mesons can serve as a signature of QGP.
124365920
A statistical model analysis of the rapidity distribution of hadrons
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.
122366381
Collective flow model for the pion transverse momentum spectra from relativistic nuclear collisions at CERN
The transverse momentum spectra for pions observed by WA80 and NA35 collaborations are analysed within a fireball model with collective isentropic expansion and a realistic freeze-out criterion. By varing the initial state of the fireball, an excellent fit to the data is achieved for the whole measured range ofPT. Slight differences in the data for the spectral slopes from central and pheripheral collisions originate in our model from the difference in the size of the fireball and in the number of participating nucleons in central and peripheral collisions. Using additional information from two-pion correlations, we can extrapolate our model back from the freeze-out point (determined from the spectra) to the initial state; we find that an initial energy density of 1.5–2GGeV/fm3 is sufficient to explain the data from central O+Au collisions at 200A GeV.
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.
12063647
Vortex string dynamics in an external antisymmetric tensor field
Abstract We study the Lund–Regge equation that governs the motion of strings in a constant background antisymmetric tensor field by using the duality between the Lund–Regge equation and the complex sine-Gordon equation. Similar to the cases of vortex filament configurations in fluid dynamics, we find various exact solitonic string configurations which are the analogue of the Kelvin wave, the Hasimoto soliton and the smoke ring. In particular, using the duality relation, we obtain a completely new type of configuration which corresponds to the breather of the complex sine-Gordon equation.
119433922
New Precision Electroweak Tests in Supergravity Models
We update the analysis of the precision electroweak tests in terms of four epsilon parameters, e1,2,3,b, to obtain more accurate experimental values of them by taking into account the new LEP data released at the 28th ICHEP (Poland, 1996). We also compute e1 and eb in the context of the no-scale SU(5)×U(1) supergravity model to obtain the updated constraints by imposing the correlated constraints in terms of the experimental ellipses in the e1–eb plane and also by imposing the new conservative bound on the lightest chargino mass, . Upon imposing these new experimental results, we find that the situations in the no-scale model are much more favorable than those in the standard model, and if mt≳ 170 GeV, then the allowed regions at the 95% C.L. in the no-scale model are tan β≳ 4 and for μ>0 (μ< 0), which are in fact much more stringent than in our previous analysis. Therefore, assuming that mt≳ 170 GeV, if the lightest chargino mass bound were to be pushed up to 82 GeV, the sign on the Higgs mixing term μ in the no-scale model could well be determined from the e1–eb constraint to be positive at the 95% C.L. At any rate, better accuracy in the measured mt from the Tevatron in the near future combined with the LEP data is most likely to provide a decisive test of the no-scale SU(5)×U(1) supergravity model.
13904218
Janus and multifaced supersymmetric theories. II
We explore the physics of supersymmetric Janus gauge theories in four dimensions with spatial dependent coupling constants e{sup 2} and {theta}. For the 8 supersymmetric case, we study the vacuum and Bogomol'nyi-Prasad-Sommerfield spectrum, and the physics of a sharp interface where the couple constants jump. We also find less supersymmetric cases either due to additional expressions in the Lagrangian or to the fact that coupling constants depend on additional spatial coordinates.
118524475
$B_d$ - $\bar{B}_d$ mixing versus $B_s$ - $\bar{B}_s$ mixing with the anomalous $Wtb$ couplings
We explore the effects of the anomalous $tbW$ couplings on the $\bd$ mixing and recently measured $\bs$ mixing. The combined analysis of mixings via box diagrams with penguin decays provides strong constraints on the anomalous top quark couplings. We find the bound from the $\bd$ mixing data is stronger than that from the $\bs$ mixing.
12913086
Singlet fermionic dark matter
We propose a renormalizable model of a fermionic dark matter by introducing a gauge singlet Dirac fermion and a real singlet scalar. The bridges between the singlet sector and the standard model sector are only the singlet scalar interaction terms with the standard model Higgs field. The singlet fermion couples to the standard model particles through the mixing between the standard model Higgs and singlet scalar and is naturally a weakly interacting massive particle (WIMP). The measured relic abundance can be explained by the singlet fermionic dark matter as the WIMP within this model. Collider implication of the singlet fermionic dark matter is also discussed. Predicted is the elastic scattering cross section of the singlet fermion into target nuclei for a direct detection of the dark matter. Search of the direct detection of the dark matter provides severe constraints on the parameters of our model.