Anastasia Merzlaya

• Merzlaya, Anastasia & Collaboration, the NA61/SHINE (2025). First D0 + D0 measurement in nucleus-nucleus collisions at SPS energies with NA61/SHINE. The European Physical Journal Conferences. ISSN 2101-6275. 316. doi: 10.1051/epjconf/202531604004. Full text in Research Archive Show summary

  The measurement of open charm meson production provides a tool for the investigation of the properties of the hot and dense matter created in nucleus-nucleus collisions at relativistic energies. In particular, charm mesons are of vivid interest in the context of the study of the nature of the phasetransition between confined hadronic matter and the quark-gluon plasma. Recently, the NA61/SHINE experimental setup was upgraded with a high spatial resolution Vertex Detector which enables the reconstruction of secondary vertices from open charm meson decays. The first direct neutral D meson yields at the SPS energy regime will be shown. The analysis used the 20% most central Xe+La collisions at 150A GeV/c from the data set collected in 2017. It allowed the estimation of the mid-rapidity yields (dN/dy) of D0 + D¯0 using their π± + K∓ decay channels and phase space corrections derived from the three models AMPT, PHSD, and PYTHIA/Angantyr. The results will be compared and discussed in the context of several model calculations including statistical and dynamical approaches.

• Adhikary, H.; Adrich, P.; Allison, K. K.; Amin, N.; Andronov, E. V. & Arsene, Ionut Cristian [Show all 140 contributors for this article] (2025). Measurements of hadron production in 90 GeV=c proton-carbon interactions. Physical Review D. ISSN 2470-0010. 112(1). doi: 10.1103/42nk-jbvm. Full text in Research Archive
• Zviagina, A.; Zimmerman, E. D.; Zherebtsova, E.; Zaitsev, A.; Wyszyński, O. & Wójcik, K. [Show all 132 contributors for this article] (2025). Multiplicity and net-electric charge fluctuations in central Ar+Sc interactions at 13A, 19A, 30A, 40A, 75A, and 150AGeV/c beam momenta measured by NA61/SHINE at the CERN SPS. European Physical Journal C. ISSN 1434-6044. 85(8). doi: 10.1140/epjc/s10052-025-14621-z. Full text in Research Archive Show summary

  This paper presents results on multiplicity fluctuations of positively and negatively charged hadrons as well as net-electric charge fluctuations measured in central Ar+Sc interactions at beam momenta 13A, 19A, 30A, 40A, 75A, and 150. The fluctuation analysis is one of the tools to search for the predicted critical point of strongly interacting matter. Results are corrected for the experimental biases and quantified using cumulant ratios. In most instances, multiplicity and net-charge distributions appear narrower than the corresponding Poisson or Skellam distributions. Cumulant ratios are compared with the Epos1.99 model predictions, which provide a qualitative description that aligns with observations for positively and negatively charged particles. The obtained results are also compared to earlier NA61/SHINE results from inelastic p+p interactions in the same analysis acceptance.

• Unger, Michael; Adhikary, H.; Adrich, P.; Allison, K. K.; Amin, N. & Andronov, E. V. [Show all 132 contributors for this article] (2025). Fragmentation Cross Sections for the Understanding of Cosmic-Ray Transport in the Galaxy: Results and Prospects from NA61/SHINE. Proceedings of Science (PoS). 501. doi: 10.22323/1.501.0146. Full text in Research Archive Show summary

  Accurate measurements of cosmic-ray fragmentation cross sections are essential for maximizing the physics potential of precise measurements of secondary and primary cosmic-ray fluxes from current balloon and space-borne experiments. NA61/SHINE, operating at the CERN SPS H2 beamline, is uniquely suited to studying these interactions at energies above 10 GeV/c per nucleon. In this contribution, we present the fragmentation cross sections for the breakup of carbon into 10B, 11B and 11C at 13.5 GeV/c per nucleon that are needed for interpreting the cosmic-ray boron-to-carbon ratio. These results are based on data from a pilot run conducted in 2018. We also give an overview of the high-statistics data-taking campaign in 2024, which covered projectile nuclei from lithium to silicon. With over 40 million recorded beam triggers, this data set will enable the reconstruction of the full reaction network required to study light secondary cosmic rays. Furthermore, we report on data collected in 2025 with a primary oxygen beam at 150 GeV/c per nucleon, aimed at verifying the expected flattening of fragmentation cross sections at high energies.

• Shukla, Anirvan; Adhikary, H.; Adrich, P.; Allison, K. K.; Amin, N. & Andronov, E. V. [Show all 145 contributors for this article] (2025). First measurements of deuteron production spectra in p+p collisions at beam momentum of 158 GeV/c at the NA61/SHINE spectrometer at the CERN SPS. Proceedings of Science (PoS). 501. doi: 10.22323/1.501.0397. Full text in Research Archive Show summary

  The NA61/SHINE spectrometer at the CERN Super Proton Synchrotron (SPS) scans particle production in collisions of nuclei with various sizes at a set of energies covering the SPS energy range towards various physics goals. This paper presents the first differential production measurements of deuterons at energies relevant for cosmic-ray studies, produced in inelastic p+p interactions at incident projectile momentum of 158~GeV/c (√s = 17.3 GeV). The double-differential spectra are presented as functions of rapidity and transverse momentum and are compared to predictions of the thermal and coalescence models. These measurements are essential for improving our understanding of cosmic (anti)nuclei production, as detecting cosmic antinuclei can be a breakthrough approach to identifying dark matter. The primary source of cosmic antinuclei background is interactions between cosmic-ray protons and interstellar hydrogen gas. Gaining a deeper insight into the deuteron production mechanism in p+p interactions is an essential first step in modeling cosmic antinuclei production.

• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Arsene, Ionut Cristian [Show all 142 contributors for this article] (2025). Measurement of the mass-changing, charge-changing, and production cross sections of C 11, B 11, and B 10 nuclei in C 12 + p interactions at 13.5 GeV/c per nucleon. Physical Review C. ISSN 2469-9985. 111(5). doi: 10.1103/PhysRevC.111.054606. Full text in Research Archive
• Zwaska, R.; Zviagina, A.; Zimmerman, E.D.; Zherebtsova, E.; Zaitsev, A. & Wyszyński, O. [Show all 154 contributors for this article] (2025). Evidence of isospin-symmetry violation in high-energy collisions of atomic nuclei. Nature Communications. 16(1). doi: 10.1038/s41467-025-57234-6. Full text in Research Archive
• Abgrall, N.; Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N. & Andronov, E.V. [Show all 158 contributors for this article] (2024). KS0 meson production in inelastic p+p interactions at 31, 40 and 80 GeV/c beam momentum measured by NA61/SHINE at the CERN SPS. European Physical Journal C. ISSN 1434-6044. 84(8). doi: 10.1140/epjc/s10052-024-13056-2. Full text in Research Archive
• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 154 contributors for this article] (2024). Measurements of π±, K±, p and p¯ spectra in 40Ar+45Sc collisions at 13A to 150A GeV/c. European Physical Journal C. ISSN 1434-6044. 84(4). doi: 10.1140/epjc/s10052-024-12602-2. Full text in Research Archive Show summary

  The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive doubledifferential spectra, transverse momentum and rapidity distributions and mean multiplicities of π ±, K±, p and ¯ p produced in 40Ar+45Sc collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A GeV/c. The analysis uses the 10% most central collisions,where the observed forward energy defines centrality. The energy dependence of the K±/π ± ratios as well as of inverse slope parameters of the K± transversemass distributions are placed in between those found in inelastic p + p and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.

• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 159 contributors for this article] (2024). Search for a critical point of strongly-interacting matter in central 40Ar + 45Sc collisions at 13 A–75 A GeV/c beam momentum. European Physical Journal C. ISSN 1434-6044. 84(7). doi: 10.1140/epjc/s10052-024-13012-0. Full text in Research Archive Show summary

  The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central \(^{40}\)Ar + \(^{45}\)Sc collisions at 13 A, 19 A, 30 A, 40 A, and 75 A GeV/c. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency index is obtained based on a comparison with the Power-law Model.

• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Arsene, Ionut Cristian [Show all 149 contributors for this article] (2024). Measurements of higher-order cumulants of multiplicity and net-electric charge distributions in inelastic proton–proton interactions by NA61/SHINE. European Physical Journal C. ISSN 1434-6044. 84(9). doi: 10.1140/epjc/s10052-024-13076-y. Full text in Research Archive Show summary

  This paper presents the energy dependence of multiplicity and net-electric charge fluctuations in p+p interactions at beam momenta 20, 31, 40, 80, and 158 \(\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c\). Results are corrected for the experimental biases and quantified with the use of cumulants and factorial cumulants. Cumulant ratios are an essential tool in the search for the critical point of strongly interacting matter in heavy ion collisions. Measurements performed in p+p interactions provide a vital baseline estimation in these studies. The measured signals are compared with the string hadronic models Epos1.99 and FTFP-BERT.

• Aduszkiewicz, A.; Bajda, M.; Baszczyk, M.; Bryliíski, W.; Brzychczyk, J. & Deveaux, M. [Show all 26 contributors for this article] (2023). A high-resolution pixel silicon Vertex Detector for open charm measurements with the NA61/SHINE spectrometer at the CERN SPS. European Physical Journal C. ISSN 1434-6044. 83(6). doi: 10.1140/epjc/s10052-023-11624-6. Full text in Research Archive Show summary

  Abstract The study of open charm meson production provides an efficient tool for the investigation of the properties of hot and dense matter formed in nucleus–nucleus collisions. The interpretation of the existing di-muon data from the CERN SPS suffers from a lack of knowledge on the mechanism and properties of the open charm particle production. Due to this, the heavy-ion programme of the NA61/SHINE experiment at the CERN SPS has been extended by precise measurements of charm hadrons with short lifetimes. A new Vertex Detector for measurements of the rare processes of open charm production in nucleus–nucleus collisions was designed to meet the challenges of track registration and high resolution in primary and secondary vertex reconstruction. A small-acceptance version of the vertex detector was installed in 2016 and tested with Pb + Pb collisions at 150 $$A\,\text{ GeV }\!/\!c$$ A GeV / c . It was also operating during the physics data taking on Xe + La and Pb + Pb collisions at 150 $$A\,\text{ GeV }\!/\!c$$ A GeV / c conducted in 2017 and 2018. This paper presents the detector design and construction, data calibration, event reconstruction, and analysis procedure.

• Adhikary, H.; Allison, K.K.; Amin, N.; Andronov, E.V.; Antićić, T. & Arsene, Ionut Cristian [Show all 154 contributors for this article] (2023). Measurements of K S0, Λ, and Λ ¯ production in 120 GeV/c p+ C interactions. Physical Review D. ISSN 2470-0010. 107(7). doi: 10.1103/PhysRevD.107.072004. Full text in Research Archive
• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 155 contributors for this article] (2023). Measurements of π+, π-, p, p ¯, K+ and K- production in 120 GeV/c p+ C interactions. Physical Review D. ISSN 2470-0010. 108(7). doi: 10.1103/PhysRevD.108.072013. Full text in Research Archive
• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 159 contributors for this article] (2023). Search for the critical point of strongly-interacting matter in ⁴⁰Ar + ⁴⁵Sc collisions at 150A Ge V /c using scaled factorial moments of protons. European Physical Journal C. ISSN 1434-6044. 83(9). doi: 10.1140/epjc/s10052-023-11942-9. Full text in Research Archive Show summary

  The critical point of dense, strongly interacting matter is searched for at the CERN SPS in 40Ar  + 45Sc collisions at 150A  Ge V /c. The dependence of second-order scaled factorial moments of proton multiplicity distribution on the number of subdivisions of transverse momentum space is measured. The intermittency analysis is performed using both transverse momentum and cumulative transverse momentum. For the first time, statistically independent data sets are used for each subdivision number. The obtained results do not indicate any statistically significant intermittency pattern. An upper limit on the fraction of correlated proton pairs and the power of the correlation function is obtained based on a comparison with the Power-law Model developed for this purpose.

• Adhikary, H.; Adrich, P.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 156 contributors for this article] (2023). Two-pion femtoscopic correlations in Be+Be collisions at √sNN=16.84 GeV measured by the NA61/SHINE at CERN. European Physical Journal C. ISSN 1434-6044. 83(10). doi: 10.1140/epjc/s10052-023-11997-8. Full text in Research Archive Show summary

  This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150A GeV/c (energy available in the center-of-mass system for nucleon pair √sNN = 16.84 GeV) by the NA61/SHINEexperiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent α is approximately constant as a function of mT , and far from both the Gaussian case of α = 2 or the conjectured value at the critical endpoint, α = 0.5. The radius scale parameter R shows a slight decrease in mT , which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter λ as a function of mTwas observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results).

• Adhikary, H.; Allison, K.K.; Amin, N.; Andronov, E.V.; Antićić, T. & Arsene, Ionut Cristian [Show all 157 contributors for this article] (2023). Measurement of hadron production in π - C interactions at 158 and 350 GeV/c with NA61/SHINE at the CERN SPS. Physical Review D. ISSN 2470-0010. 107(6). doi: 10.1103/PhysRevD.107.062004. Full text in Research Archive Show summary

  We present a measurement of the momentum spectra of π±, K±, p±, Λ, ¯Λ, and K0S produced in interactions of negatively charged pions with carbon nuclei at beam momenta of 158 and 350  GeV/c. The total production cross sections are measured as well. The data were collected with the large-acceptance spectrometer of the fixed target experiment NA61/SHINE at the CERN SPS. The obtained double-differential p−pT spectra provide a unique reference dataset with unprecedented precision and large phase-space coverage to tune models used for the simulation of particle production in extensive air showers in which pions are the most numerous projectiles.

• Acharya, A.; Adhikary, H.; Allison, K.K.; Amin, N.; Andronov, E.V. & Antićić, T. [Show all 147 contributors for this article] (2022). K^∗(892) meson production in inelastic p+p interactions at 40 and 80 GeV/c beam momenta measured by NA61/SHINE at the CERN SPS. European Physical Journal C. ISSN 1434-6044. 82(4). doi: 10.1140/epjc/s10052-022-10281-5. Full text in Research Archive Show summary

  Measurements of K∗ (892)0 resonance production via its K+ π − decay mode in inelastic p+p collisions at beam momenta 40 and 80 GeV/c (√sNN = 8.8 and 12.3 GeV) are presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template methodwas used to extract the K∗ (892)0 signal. Transversemomentum and rapidity spectra were obtained. The mean multiplicities of K∗ (892)0 mesons were found to be (35.1 ± 1.3(stat) ± 3.6(sys)) · 10−3 at 40 GeV/c and (58.3±1.9(stat)±4.9(sys))·10−3 at 80 GeV/c. The NA61/SHINE results are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data. The transverse mass spectra of K∗ (892)0 mesons and other particles previously reported byNA61/SHINEwere fitted within the Blast-Wave model. The transverse flow velocities are close to 0.1–0.2 of the speed of light and are significantly smaller than the ones determined in heavy nucleusnucleus interactions at the same beam momenta.

• Merzlaya, Anastasia; Wrońska, A.; Magiera, A. & Przygoda, W. (2019). Open charm measurements at CERN SPS energies with the new Vertex Detector of the NA61/SHINE experiment. The European Physical Journal Conferences. ISSN 2101-6275. 199, p. 04012–04012. doi: 10.1051/epjconf/201919904012. Full text in Research Archive Show summary

  The study of open charm meson production provides an efficient tool for detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. The interpretation of the existing data from the CERN SPS suffers from a lack of knowledge on the total charm production rate. To overcome this limitation the heavy-ion programme of the NA61/SHINE experiment at CERN SPS has been expanded to allow for precise measurements of particles with a short lifetime. A new Small Acceptance Vertex Detector (SAVD) was designed and constructed to meet the challenges of open charm measurements in nucleus-nucleus collisions. SAVD was installed in December 2016 for data taking with Pb+Pb collisions at 150A GeV/c. An exploratory set of collected data allowed to validate the general concept of the D 0 mesons detection via its D 0 → π + +K - decay channel and delivered the first direct observation of open charm at SPS energies. In October and November of 2017 a large statistic data set has been taken for Xe+La at 150A, 75A, and 40A GeV/c, these data are currently under intense analysis. The physics motivation behind the open charm measurements at the SPS energies will be discussed. Moreover, the concept of the SAVD hardware and status of the analysis will be shown. Also, the future plans of open charm measurements in the NA61/SHINE experiment related to the upgraded Vertex Detector will be presented.

• Merzlaya, Anastasia (2018). Open Charm Measurements at CERN SPS Energies with the New Vertex Detector of the NA61/SHINE Experiment. KnE Energy. ISSN 2413-5453. 3(1), p. 154–154. doi: 10.18502/ken.v3i1.1738. Full text in Research Archive Show summary

  The heavy-ion programme of the NA61/SHINE experiment at the CERN SPS has been expanded to allow precise measurements of exotic particles with short lifetime. The study of open charm meson production is a sensitive tool for new detailed investigations of the properties of hot and dense matter formed in nucleus-nucleus collisions. In particular, it offers new possibilities for studies of such phenomena as in- medium parton energy loss and quarkonium dissociation and possible regeneration, thus providing new information to probe deconfinement. A new high resolution Vertex Detector was designed for the NA61/SHINE experiment for measurements of the very rare processes of open charm production in nucleus- nucleus collisions at the SPS. It will meet the challenges of track registration and of very precise spatial resolution in primary and secondary vertex reconstruction required for the identification of

• Larsen, Dag Toppe & Merzlaya, Anastasia (2018). Open charm measurements with the NA61/SHINE experiment at the CERN SPS. Journal of Physics: Conference Series (JPCS). ISSN 1742-6588. 1137, p. 012048–012048. doi: 10.1088/1742-6596/1137/1/012048. Full text in Research Archive
• Larsen, Dag Toppe; Volkova, V.E.; Merzlaya, Anastasia; Zhezher, Y.V.; Levkov, D.G. & Rubakov, V.A. [Show all 7 contributors for this article] (2018). Open Charm measurements at the NA61 experiment at CERN SPS. The European Physical Journal Conferences. ISSN 2101-6275. 191, p. 05003–05003. doi: 10.1051/epjconf/201819105003. Full text in Research Archive Show summary

  The strong interactions programme of the NA61/SHINE experiment at CERN SPS has been extended through the use of new silicon Vertex Detector which provides precise measurements of exotic particles with short lifetime. The detector was designed to meet the challenges of primary and secondary vertexes reconstruction at high spatial resolution. An initial version of the Vertex Detector called SAVD (Small Acceptance Vertex Detector) was installed last end of 2016, and data was from Pb+Pb collisions was collected in 2016, for Xe+La in 2017, as well as further Pb+Pb collisions this year. First indication of a D 0 peak at SPS energies has been observed. The physics motivation behind the open charm measurements will be discussed, as well as the analysis of collected data on open charm production and the future plans of open charm measurements in NA61/SHINE experiment related to the upgraded version of the vertex detector.

• Deveaux, M.; Mischke, A.; Aduszkiewicz, A.; Kuijer, P.; Ali, Y. & Baszczyk, M. [Show all 27 contributors for this article] (2018). The Small Acceptance Vertex Detector of NA61/SHINE. The European Physical Journal Conferences. ISSN 2101-6275. 171, p. 21001–21001. doi: 10.1051/epjconf/201817121001. Full text in Research Archive Show summary

  Charmonium production in heavy ion collisions is considered as an important diagnostic probe for studying the phase diagram of strongly interacting matter for potential phase transitions. The interpretation of existing data from the CERN SPS is hampered by a lack of knowledge on the properties of open charm particle production in the fireball. Moreover, open charm production in heavy ion collisions by itself is poorly understood. To overcome this obstacle, the NA61/SHINE was equipped with a Small Acceptance Vertex Detector (SAVD), which is predicted to make the experiment sensitive to open charm mesons produced in A-A collisions at the SPS top energy. This paper will introduce the concept and the hardware of the SAVD. Moreover, first running experience as obtained in a commissioning run with a 150 AGeV/c Pb+Pb collision system will be reported.

• Deveaux, M.; Mischke, A.; Aduszkiewicz, A.; Kuijer, P.; Ali, Y. & Baszczyk, M. [Show all 27 contributors for this article] (2018). The Small Acceptance Vertex Detector of NA61/SHINE. The European Physical Journal Conferences. ISSN 2101-6275. 171, p. 10003–10003. doi: 10.1051/epjconf/201817110003. Full text in Research Archive Show summary

  Charmonium production in heavy ion collisions is considered as an important diagnostic probe for studying the phase diagram of strongly interacting matter for potential phase transitions. The interpretation of existing data from the CERN SPS is hampered by a lack of knowledge on the properties of open charm particle production in the fireball. Moreover, open charm production in heavy ion collisions by itself is poorly understood. To overcome this obstacle, the NA61/SHINE was equipped with a Small Acceptance Vertex Detector (SAVD), which is predicted to make the experiment sensitive to open charm mesons produced in A-A collisions at the SPS top energy. This paper will introduce the concept and the hardware of the SAVD. Moreover, first running experience as obtained in a commissioning run with a 150 A GeV/ c Pb+Pb collision system will be reported.

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• Merzlaya, Anastasia (2024). First D0+bar(D0) measurement in heavy-ion collisions at SPS energies with NA61/SHINE. Full text in Research Archive
• Merzlaya, Anastasia (2024). First D0 + anti-D0 measurement in heavy-ion collisions at SPS energies with NA61/SHINE. Full text in Research Archive

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