17726542
Formation and collapse of false vacuum bubbles in relativistic heavy-ion collisions
Abstract It is possible that under certain situations, in a relativistic heavy-ion collision, partons may expand out forming a shell like structure. We analyze the process of hadronization in such a picture for the case when the quark–hadron transition is of first order, and argue that the inside region of such a shell must correspond to a supercooled (to T=0 ) deconfined vacuum. Hadrons from that region escape out, leaving a bubble of pure deconfined vacuum with large vacuum energy. This bubble undergoes relativistic collapse, with highly Lorentz contracted bubble walls, and may concentrate the entire energy into extremely small regions. Eventually different portions of bubble wall collide, with the energy being released in the form of particle production. Thermalization of this system can lead to very high temperatures. With a reasonably conservative set of parameters, at LHC, the temperature of the hot spot can reach as high as 3 GeV, and well above it with more optimistic parameters. Such a hot spot can leave signals like large P T partons, dileptons, and enhanced production of heavy quarks. We also briefly discuss a speculative possibility where the electroweak symmetry may get restored in the highly dense region resulting from the decay of the bubble wall via the phenomenon of non-thermal symmetry restoration (which is usually employed in models of pre-heating after inflation). If that could happen then the possibility may arise of observing sphaleron induced baryon number violation in relativistic heavy-ion collisions.
121968392
Observing B-violation in relativistic heavy-ion collisions
Under certain situations, partons formed in heavy-ion collision experiments may expand out forming a shell-like structure. The partons in the outer shell subsequently hadronize, leaving a bubble of pure deconfined vacuum for a first-order quark-hadron phase transition. The bubble collapses and may eventually decay into particles which may thermalize to temperatures exceeding the electroweak transition temperature (100 GeV) at LHC. This will lead to the possibility of unsuppressed electroweak baryon number violating processes.
99532809
QCD phase diagram using PNJL model with eight-quark interactions
Abstract We present the phase diagram and the fluctuations of different conserved charges like quark number, charge and strangeness at vanishing chemical potential for the 2+1 flavor Polyakov Loop extended Nambu-Jona-Lasinio model with eight-quark interaction terms using three-momentum cutoff regularisation. The main effect of the higher order interaction term is to shift the critical end point to the lower value of the chemical potential and higher value of the temperature. The fluctuations show good qualitative agreement with the lattice data.
17004831
Taylor expansions in chemical potential
Properties of QCD at finite chemical potential (µ) are extracted using Taylor series expansions. The continuum limits of lattice results are presented. The result of expanding the free energy density, i.e., the pressure, to 6th order in the expansion is shown. The Taylor coefficients of the chiral condensate are also shown. Relations between various Taylor coefficients are demonstrated. All this information is utilised to remove various lattice artifacts from the determination of the Wroblewski parameter in strangeness production.
119102585
Thermodynamic properties of strongly interacting matter in a finite volume using the Polyakov–Nambu–Jona-Lasinio model
We present the thermodynamic properties of strongly interacting matter in finite volume in the framework of Polyakov loop enhanced Nambu$-$Jona-lasinio model within mean field approximation. We considered both the 2 flavor and 2+1 flavor matter. Our primary observation was a qualitative change in the phase transition properties that resulted in the lowering of the temperature corresponding to the critical end point. This would make it favorable for detection in heavy-ion experiments that intend to create high density matter with considerably small temperatures. We further demonstrate the possibility of obtaining chiral symmetry restoration even within the confined phase in finite volumes.
119158093
The consequences of SU (3) colorsingletness, Polyakov Loop and Z (3) symmetry on a quark–gluon gas
Based on quantum statistical mechanics we show that the SU(3) color singlet ensemble of a quark-gluon gas exhibits a Z(3) symmetry through the normaized character in fundamental representation and also becomes equivalent, within a stationary point approximation, to the ensemble given by Polyakov Loop. Also Polyakov Loop gauge potential is obtained by considering spatial gluons along with the invariant Haar measure at each space point. The probability of the normalized character in SU(3) vis-a-vis Polyakov Loop is found to be maximum at a particular value exhibiting a strong color correlation. This clearly indicates a transition from a color correlated to uncorrelated phase or vise-versa. When quarks are included to the gauge fields, a metastable state appears in the temperature range 145 T(MeV) 170 due to the explicit Z(3) symmetry breaking in the quark-gluon system. Beyond T 170 MeV the metastable state disappears and stable domains appear. At low temperature a dynamical recombination of ionized Z(3) color charges to a color singlet Z(3) confined phase is evident along with a confining background that originates due to circulation of two virtual spatial gluons but with conjugate Z(3) phases in a closed loop. We also discuss other possible consequences of the center domains in the color deconfined phase at high temperature.
126084521
Measurements of the widths of charmonium states at the Fermilab anti-p accumulator ring
118620496
Observation of narrow lines in the spectra of charged mesons produced in antiproton-proton annihilation at rest
123588442
A search for structure in charged meson spectra from proton-antiproton annihilations at rest
The charged meson momentum spectra from pp annihilation at rest have been measured with high statistics. A search is made for structures between 150 and 300 MeV/c which indicate narrow baryonium states. We find four narrow lines which are identified with the absorption and decay processes of kaons stopping in the target. No other narrow structures are seen, giving limits of 2−6×10−4 p (90% CL) for the yield of a narrow state in the mass range 1510–1660 MeV.
116328057
The KTeV Pure CsI Calorimeter
KTeV is currently building a state-of-the-art pure CsI electromagnetic calorimeter with a sophisticated digital readout. The CsI array is expected to have better than 1% resolution over a dynamic range of 2--64 GeV. The design of the CsI array is driven by the difficult physics goal of attempting to measure the CP violation parameter Re({epsilon}{prime}/{epsilon}) to 1 part in 10000 in a high-rate neutral beam environment. The physics requirements and their impact on the final design will be discussed.
123205836
The E760 lead-glass central calorimeter: design and initial test results
The central calorimeter in Fermilab experiment E760++ has been designed to measure the topology and energies of electrons and photons in the decay of charmonium formed in pp annihilation. The calorimeter is composed of 1280 lead-glass Cherenkov counters read out with photomultiplier tubes. This paper discusses design criteria for the calorimeter and describes how these criteria were met. Data from tests in low energy (10–84 MeV) and medium energy (1–4 GeV) beams are presented showing a spatial resolution of 9 mm, an energy resolution of (3.0 ± 0.3)%√E[GeV] + (1.5 ± 0.5)%, and an effective energy threshold below 10 MeV.