The NICA (Nuclotron-based Ion Collider fAcility) project is under realization at the Joint Institute for Nuclear Research (JINR, Dubna). The main goal of the project is a study of hot and dense ...strongly interacting matter in heavy ion collisions (up to Au) in the energy range up to sNN=11 GeV. Two modes of operation are foreseen, collider and extracted beam operations, with two detectors: MPD and BM@N. In the Au + Au collider mode the expected average luminosity is L=1027cm−2s−1. The proposed experimental program allows one to search for possible manifestations of the phase transitions and critical phenomena.
The Multi-Purpose Detector (MPD) is under construction to investigate heavy ion collisions at the NICA collider in the energy range sNN=4−11GeV. The MPD physics purpose is to get a better ...understanding of the QCD matter under extreme conditions of high baryonic density by studying collective phenomena, Λ polarization, dilepton yields, multi-strange hyperons and hypernuclei production. The MPD construction is progressing in accordance with the schedule.
The accelerator Nuclotron is one of the most important installations of the NICA accelerator complex in Dubna, which also includes a booster synchrotron and a collider. The superconducting booster ...synchrotron was put into operation at the end of 2020, the superconducting collider is in the final stage of assembly. Its launch is scheduled for late 2022. The magnetic system of the superconducting synchrotron Nuclotron has been in operation since 1993 and will require upgrade in the coming years. One of the possible options for upgrading the Nuclotron is to replace its magnets with magnets made of HTS material. A model superconducting quadrupole magnet with a winding of HTS material has been developed and manufactured at Veksler and Baldin Laboratory of High Energy Physics of Joint Institute for Nuclear Research. The design features and the first results of cryogenic tests of the magnet are discussed.
A precision measurement of the ratio RK of the rates of kaon leptonic decays K±→e±ν and K±→μ±ν with the full data sample collected by the NA62 experiment at CERN in 2007–2008 is reported. The result, ...obtained by analysing ∼150000 reconstructed K±→e±ν candidates with 11% background contamination, is RK=(2.488±0.010)×10−5, in agreement with the Standard Model expectation.
The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003–2004. A new upper limit on the rate of the lepton number ...violating decay K±→π∓μ±μ± is reported: B(K±→π∓μ±μ±)<8.6×10−11 at 90% CL. Searches for two-body resonances X in K±→πμμ decays (such as heavy neutral leptons N4 and inflatons χ) are also presented. In the absence of signals, upper limits are set on the products of branching fractions B(K±→μ±N4)B(N4→πμ) and B(K±→π±X)B(X→μ+μ−) for ranges of assumed resonance masses and lifetimes. The limits are in the (10−11,10−9) range for resonance lifetimes below 100 ps.
Abstract
The NICA facility is under active realization at the Joint Institute for Nuclear Research (JINR, Dubna). Its main goal includes experimental studies of hot and dense baryon rich matter ...forming in heavy ion collisions to search for possible manifestations of phase transitions and critical phenomena, as well as investigation of nucleon spin structure with polarized proton and deuteron beams. The NICA general design, construction status, and prospects for physics program are presented.
The project NICA (Nuclotron-based Ion Collider fAcility) is aimed to study hot and dense baryonic matter in heavy ion collisions in the energy range up to √sNN=11 GeV at the Nuclotron extracted beams ...and at the NICA collider with average luminosity of L = 1027 cm-2s-1 (for 197Au79). This study will be performed with two experiments, BM@N (Baryonic Matter at Nuclotron) and MPD (MultiPurpose Detector) at the NICA collider.
We report results from a new measurement of the K
e4
decay K
±
→π
+
π
-
e
±
ν by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670 000 K
e4
decays in both charged ...modes collected in 2003. The form factors of the hadronic current (F,G,H) and ππ phase difference (δ=δ
s
-δ
p
) have been measured in ten independent bins of the ππ mass spectrum to investigate their variation. A sizeable acceptance at large ππ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the ππ scattering lengths a
0
0
and a
0
2
. Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (a
0
0
,a
0
2
): a
0
0
=0.233±0.016stat±0.007syst,a
0
2
=-0.0471±0.011stat±0.004syst. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory.
The NA62 experiment at the CERN SPS reports the first search for K+→π+νν¯ using the decay-in-flight technique, based on a sample of 1.21×1011K+ decays collected in 2016. The single event sensitivity ...is 3.15×10−10, corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of 14×10−10 on the K+→π+νν¯ branching ratio at 95% CL.
The NA48/2 experiment at CERN reports the first observation of the K±→π±π0e+e− decay from an exposure of 1.7×1011 charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% ...background contamination allows the determination of the branching ratio in the full kinematic region, BR(K±→π±π0e+e−)=(4.24±0.14)×10−6. The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.
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