We present an analysis of the net-proton kurtosis on the crossover side of the critical point within the model of nonequilibrium chiral fluid dynamics (NχFD). The chiral order parameter is propagated ...explicitly and coupled to an expanding fluid of quarks and gluons to describe the dynamical situation in a heavy-ion collision. After implementing a particlization routine into this model, we study the behavior of the net-proton kurtosis as driven by the characteristic structure of the net-baryon number susceptibility in the critical region.
The Bergen proton CT system Aehle, M.; Alme, J.; Barnaföldi, G.G. ...
Journal of instrumentation,
02/2023, Letnik:
18, Številka:
2
Journal Article
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Abstract
The Bergen proton Computed Tomography (pCT) is a prototype detector under construction. It aims to have the capability to track and measure ions’ energy deposition to minimize uncertainty in ...proton treatment planning. It is a high granularity digital tracking calorimeter, where the first two layers will act as tracking layers to obtain positional information of the incoming particle. The remainder of the detector will act as a calorimeter. Beam tests have been performed with multiple beams. These tests have shown that the ALPIDE chip sensor can measure the deposited energy, making it possible for the sensors to distinguish between the tracks in the Digital Tracking Calorimeter (DTC).
To classify clusters of hits in the electromagnetic calorimeter (EMC) of ANDA (antiProton ANnihilation at DArmstadt), one has to match these EMC clusters with tracks of charged particles ...reconstructed from hits in the tracking system. Therefore the tracks are propagated to the surface of the EMC and associated with EMC clusters which are nearby and below a cut parameter. In this work, we propose a helix propagator to extrapolate the track from the Straw Tube Tracker (STT) to the inner surface of the EMC instead of the GEANE propagator which is already embedded within the PandaRoot computational framework. The results for both propagation methods show a similar quality, with a 30% gain in CPU time when using the helix propagator. We use Monte-Carlo truth information to compare the particle ID of the EMC clusters with the ID of the extrapolated points, thus deciding upon the correctness of the matches. By varying the cut parameter as a function of transverse momentum and particle type, our simulations show that the purity can be increased by 3–5% compared to the default value which is a constant cut in the ANDA simulation framework PandaRoot.
Very large Liquid Xenon (LXe) Time Projection Chambers (TPC) are employed to search for Dark Matter (DM). The DM particles are supposed to interact with the whole nucleus, compared to background of ...γ-rays, which interact with the electrons. Therefore, DM signals are caused by Nuclear Recoil (NR) instead of the Electron Recoils (ER). In ER and NR events differ in pulse shape since the ratios of light from direct scintillation and recombination are different. To discriminate against residual ER events would be possible if one can distinguish the differences in decay times. This method can be successfully applied in Liquid Argon TPCs. In LXe, however, it is generally assumed that these differences are too small to be distinguished at low energies. The easiest algorithm of Pulse Shape Discrimination (PSD) distinguishes the event type based on the number of photons emitted much later than the longest decay time. At low energies too much of the timing information is lost, and this method does not perform well. However, the timing of all photons does contain sufficient information. If we use sufficiently fast PMTs, have a large enough bandwidth in the Front End electronics, and avoid reflections then we should reach a background rejection better than 10−2 even at 2 keVee. In our Decay Time Measurement (DTM) method the decay curves are compared with a model on an event by event basis. Statistically this is independent from the charge over light (`S2/S1') cut normally applied in Dual Phase detectors. Applying both rejection mechanisms a LXeTPC can become `quasi background free'.
Abstract
We reconsider the chiral Lagrangian with three-flavor baryon fields. A systematic analysis of all low-energy constants (LEC) that contribute to the axial-vector and pseudoscalar currents in ...the baryon octet and decuplet fields at next-to-leading order in the inverse number of colors (
$$1/N_c$$
1
/
N
c
) of QCD is performed. We study the correlation function consisting of axial-vector and scalar currents as well. While there are 4 LEC relevant at leading chiral order, the number of relevant LEC at subleading order is 23. For those a leading order large-
$$N_c$$
N
c
analysis predicts 3 and 18 sum rules respectively. At the next accuracy level the number of sum rules is reduced to 2 and 8. Our results are illustrated by a tree-level analysis of available axial-vector coupling constants and strong decay widths of the baryon decuplet states.
We consider the chiral Lagrangian for baryon fields with JP = 1/2+ or JP = 3/2+ quantum numbers as constructed from QCD with up, down and strange quarks. The specific class of counterterms that are ...of chiral order Q3 and contribute to meson-baryon interactions at the two-body level is constructed. Altogether, we find 24 terms. In order to pave the way for realistic applications, we establish a set of 22 sum rules for the low-energy constants as they are implied by QCD in the large-Nc limit. Given such a constraint, there remain only two independent unknown parameters that need to be determined by either lattice QCD simulations or directly from experimental cross section measurements. At subleading order, we arrive at five parameters.
We reconsider the chiral Lagrangian with three-flavor baryon fields. A systematic analysis of all low-energy constants (LEC) that contribute to the axial-vector and pseudoscalar currents in the ...baryon octet and decuplet fields at next-to-leading order in the inverse number of colors (
1
/
N
c
) of QCD is performed. We study the correlation function consisting of axial-vector and scalar currents as well. While there are 4 LEC relevant at leading chiral order, the number of relevant LEC at subleading order is 23. For those a leading order large-
N
c
analysis predicts 3 and 18 sum rules respectively. At the next accuracy level the number of sum rules is reduced to 2 and 8. Our results are illustrated by a tree-level analysis of available axial-vector coupling constants and strong decay widths of the baryon decuplet states.
We perform an analysis of the QCD lattice data on the baryon octet and decuplet masses based on the relativistic chiral Lagrangian. The baryon self-energies are computed in a finite volume at ...next-to-next-to-next-to-leading order (N super(3)LO), where the dependence on the physical meson and baryon masses is kept. The number of free parameters is reduced significantly down to 12 by relying on large-N sub(c) sum rules. Altogether we describe accurately more than 220 data points from six different lattice groups, BMW, PACS-CS, HSC, LHPC, QCDSF-UKQCD and NPLQCD. Values for all counterterms relevant at N super(3)LO are predicted. In particular we extract a pion-nucleon sigma term of 39 super(+2) sub(-1) MeV and a strangeness sigma term of the nucleon of isigma sub(s)N = 84 super(+28) sub(-4) MeV. The flavor SU(3) chiral limit of the baryon octet and decuplet masses is determined with (802 + or - 4) and (1103 + or - 6). Detailed predictions for the baryon masses as currently evaluated by the ETM lattice QCD group are made.
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