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Dihadron correlations in small- DIS at NLO: transverse momentum dependent fragmentation
No full textInternational audienceWe compute inclusive dihadron cross-section in Deep Inelastic Scattering at next-to-leading order (NLO) and small in the Color Glass Condensate. We focus on the kinematic limit where the hadrons are produced at forward rapidities (in the direction of the virtual photon) and back-to-back in the transverse plane. Our calculation demonstrates that the coefficient of the Sudakov double logarithm for this process is instead of when back-to-back jets are measured in the final state. To preserve the universality of the Sudakov soft factor associated with the Weizsäcker-Williams transverse momentum dependent (TMD) gluon distribution, we promote the collinear fragmentation functions into TMD fragmentation functions. We then perform the resummation of the Sudakov logarithms through Collins-Soper-Sterman evolution of the TMD fragmentation functions and the Weizsäcker-Williams TMD gluon distribution. Finally, analytic expressions are obtained for the NLO coefficient functions in the -scheme. These results pave the way towards numerically calculating dihadron correlations at small at the future Electron-Ion Collider with full NLO accuracy
Model Independent Approach of the JUNO B Solar Neutrino Program
No full textInternational audienceThe physics potential of detecting B solar neutrinos is exploited at the Jiangmen Underground Neutrino Observatory (JUNO), in a model independent manner by using three distinct channels of the charged-current (CC), neutral-current (NC) and elastic scattering (ES) interactions. Due to the largest-ever mass of C nuclei in the liquid-scintillator detectors and the potential low background level, B solar neutrinos would be observable in the CC and NC interactions on C for the first time. By virtue of optimized event selections and muon veto strategies, backgrounds from the accidental coincidence, muon-induced isotopes, and external backgrounds can be greatly suppressed. Excellent signal-to-background ratios can be achieved in the CC, NC and ES channels to guarantee the B solar neutrino observation. From the sensitivity studies performed in this work, we show that one can reach the precision levels of 5%, 8% and 20% for the B neutrino flux, , and , respectively, using ten years of JUNO data. It would be unique and helpful to probe the details of both solar physics and neutrino physics. In addition, when combined with SNO, the world-best precision of 3% is expected for the B neutrino flux measurement
Observation of medium-induced yield enhancement and acoplanarity broadening of low- jets from measurements in pp and central PbPb collisions at TeV
No full textInternational audienceThe ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high ) hadron trigger in protonproton and central PbPb collisions at TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central PbPb collisions. Recoil jet distributions are reported for jet resolution parameter , 0.4, and 0.5 in the range GeV and triggerrecoil jet azimuthal separation . The measurements exhibit a marked medium-induced jet yield enhancement at low and at large azimuthal deviation from . The enhancement is characterized by its dependence on , which has a slope that differs from zero by 4.7. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation
Exploring the strong interaction of three-body systems at the LHC
No full textInternational audienceDeuterons are atomic nuclei composed of a neutron and a proton held together by the strong interaction. Unbound ensembles composed of a deuteron and a third nucleon have been investigated in the past using scattering experiments and they constitute a fundamental reference in nuclear physics to constrain nuclear interactions and the properties of nuclei. In this work Kd and pd femtoscopic correlations measured by the ALICE Collaboration in protonproton (pp) collisions at TeV at the Large Hadron Collider (LHC) are presented. It is demonstrated that correlations in momentum space between deuterons and kaons or protons allow us to study three-hadron systems at distances comparable with the proton radius. The analysis of the Kd correlation shows that the relative distances at which deuterons and proton/kaons are produced are around 2 fm. The analysis of the pd correlation shows that only a full three-body calculation that accounts for the internal structure of the deuteron can explain the data. In particular, the sensitivity of the observable to the short-range part of the interaction is demonstrated. These results indicate that correlations involving light nuclei in pp collisions at the LHC will also provide access to any three-body systems in the strange and charm sectors
Back-to-back inclusive dijets in DIS at small : Complete NLO results and predictions
No full textInternational audienceWe compute the back-to-back dijet cross-section in deep inelastic scattering (DIS) at small to next-to-leading order (NLO) in the Color Glass Condensate effective field theory. Our result can be factorized into a convolution of the Weizsäcker-Williams gluon transverse momentum dependent distribution function (WW gluon TMD) with a universal soft factor and an NLO coefficient function. The soft factor includes both double and single logarithms in the ratio of the relative transverse momentum of the dijet pair to the dijet momentum imbalance ; its renormalization group (RG) evolution is resummed into the Sudakov factor. Likewise, the WW TMD obeys a nonlinear RG equation in that is kinematically constrained to satisfy both lifetime and rapidity ordering of the projectile. Exact analytical expressions are obtained for the NLO coefficient function of transversely and longitudinally polarized photons. Our results allow for the first quantitative separation of the dynamics of Sudakov suppression from that of gluon saturation. They can be extended to other final states and provide a framework for precision tests of novel QCD many-body dynamics at the Electron-Ion Collider
polarization in relativistic heavy ion collisions
No full textInternational audienceUnderstanding the polarization property of is critical to constrain its production mechanism. In addition, the polarization of can reveal the impact of strong electromagnetic and vorticity fields in relativistic heavy ion collisions. In this study, we analyzed the yield and polarization of in relativistic heavy ion collisions at different centrality and transverse momentum regions, using three different reference frames: the Collins-Soper frame, the helicity frame, and the event plane frame. The polarization of initially produced is determined by the NRQCD calculation and is similar to that of collisions. However, both unpolarization and transverse polarization are considered for the regenerated . Our results indicate that the polarization at high is similar to that observed in collisions. However, at low , where regenerated dominates, it is likely that the polarized charm quarks in the rotational QGP medium are responsible for this phenomenon. Our study supplies a baseline for future research on the effects of strong electromagnetic and vorticity fields on polarization
Emergence of long-range angular correlations in low-multiplicity proton-proton collisions
No full textInternational audienceThis Letter presents the measurement of near-side associated per-trigger yields, denoted ridge yields, from the analysis of angular correlations of charged hadrons in proton-proton collisions at = 13 TeV. Long-range ridge yields are extracted for pairs of charged particles with a pseudorapidity difference of and a transverse momentum of GeV/, as a function of the charged-particle multiplicity measured at midrapidity. This study extends the measurements of the ridge yield to the low multiplicity region, where in hadronic collisions it is typically conjectured that a strongly-interacting medium is unlikely to be formed. The precision of the new results allows for the first direct quantitative comparison with the results obtained in collisions at = 91 GeV, where initial-state effects such as pre-equilibrium dynamics and collision geometry are not expected to play a role. In the multiplicity range where the results have good precision, the measured ridge yields in pp collisions are substantially larger than the limits set in annihilations. Consequently, the findings presented in this Letter suggest that the processes involved in annihilations do not contribute significantly to the emergence of long-range correlations in pp collisions
Dense nuclear matter equation of state from heavy-ion collisions
No full textInternational audienceThe nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS
Ultralight vector dark matter search using data from the KAGRA O3GK run
No full textInternational audienceAmong the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM
“Invisible” radioactive cesium atoms revealed: Pollucite inclusion in cesium-rich microparticles (CsMPs) from the Fukushima Daiichi Nuclear Power Plant
No full textInternational audienceUnderstanding radioactive Cs contamination has been a central issue at Fukushima Daiichi and other nuclear legacy sites; however, atomic-scale characterization of radioactive Cs in environmental samples has never been achieved. Here we report, for the first time, the direct imaging of radioactive Cs atoms using high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). In Cs-rich microparticles collected from Japan, we document inclusions that contain 27 – 36 wt% of Cs (reported as Cs2O) in a zeolite: pollucite. The compositions of three pollucite inclusions are (Cs1.86K0.11Rb0.19Ba0.22)2.4(Fe0.85Zn0.84X0.31)2.0Si4.1O12, (Cs1.19K0.05Rb0.19Ba0.22)1.7(Fe0.66Zn0.32X0.41)1.4Si4.6O12, and (Cs1.27K0.21Rb0.29Ba0.15)1.9(Fe0.60Zn0.32X0.69)1.6Si4.4O12 (X includes other cations). HAADF-STEM imaging of pollucite, viewed along the [111] zone axis, revealed an array of Cs atoms, which is consistent with a simulated image using the multi-slice method. The occurrence of pollucite indicates that locally enriched Cs reacted with siliceous substances during the Fukushima meltdowns, presumably through volatilization and condensation. Beta radiation doses from the incorporated Cs are estimated to reach 106 – 107 Gy, which is more than three orders of magnitude less than typical amorphization dose of zeolite. The atomic-resolution imaging of radioactive Cs is an important advance for better understanding the fate of radioactive Cs inside and outside of nuclear reactors damaged by meltdown events