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Journal articleAhmed A, Bhattacharya A, Das I, 2025,
Anomalous and large topological Hall effects in β-Mn chiral compound Co<inf>6.5</inf>Ru<inf>1.5</inf>Zn<inf>8</inf>Mn<inf>4</inf>: electron electron interaction facilitated quantum interference effect
, Journal of Physics Condensed Matter, Vol: 37, ISSN: 0953-8984β-Mn-type chiral cubic CoxZnyMnz (x + y + z = 20) alloys present a intriguing platform for exploring topological magnetic orderings with promising spintronic potential. This study examines the magnetotransport properties of Co6.5Ru1.5Zn8Mn4, a skyrmion-hosting β-Mn-type chiral compound. The longitudinal resistivity (ρxx) exhibits field-insensitive low-temperature minima due to quantum interference effects, driven by T 1 / 2 -dependent electron-electron interactions. We observe a substantial intrinsic anomalous Hall conductivity, unaffected by quantum interference. Additionally, a pronounced topological Hall effect is observed at the metastable skyrmionic state, persisting up to T C and achieving notable magnitudes for stoichiometric compounds. These results position the CoxZnyMnz family favourably to leverage the rich pallete of emergent magnetotransport properties for spintronic applications.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Pseudorapidity distributions of charged hadrons in lead-lead collisions at s<inf><inf>NN</inf></inf>=5.36TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 861, ISSN: 0370-2693The pseudorapidity (η) distributions of charged hadrons are measured using data collected at the highest ever nucleon-nucleon center-of-mass energy of sNN=5.36TeV for collisions of lead-lead ions. The data were recorded by the CMS experiment at the LHC in 2022 and correspond to an integrated luminosity of 0.30±0.03μb−1. Using the CMS silicon pixel detector, the yields of primary charged hadrons produced in the range |η|<2.6 are reported. The evolution of the midrapidity particle density as a function of collision centrality is also reported. In the 5% most central collisions, the charged-hadron η density in the range |η|<0.5 is found to be 2032±91(syst), with negligible statistical uncertainty. This result is consistent with an extrapolation from nucleus-nucleus collision data at lower center-of-mass energies. Comparisons are made to various Monte Carlo event generators and to previous measurements of lead-lead and xenon-xenon collisions at similar collision energies. These new data detail the dependence of particle production on the collision energy, initial collision geometry, and the size of the colliding nuclei.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Constraints on the Higgs boson self-coupling from the combination of single and double Higgs boson production in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 861, ISSN: 0370-2693The Higgs boson (H) trilinear self-coupling, λ3, is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at s=13TeV. The combination of event categories enriched in single-H and HH events is used to measure κλ, defined as the value of λ3 normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of κλ outside the interval −1.2<κλ<7.5 are excluded at 2σ confidence level, which is compatible with the expected range of −2.0<κλ<7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) κλ interval is constrained to be within −1.4<κλ<7.8 (−2.3<κλ<7.8) at 2σ confidence level.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Girth and groomed radius of jets recoiling against isolated photons in lead-lead and proton-proton collisions at s<inf><inf>NN</inf></inf>=5.02 TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 861, ISSN: 0370-2693This Letter presents the first measurements of the groomed jet radius Rg and the jet girth g in events with an isolated photon recoiling against a jet in lead-lead (PbPb) and proton-proton (pp) collisions at the LHC at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The observables Rg and g provide a quantitative measure of how narrow or broad a jet is. The analysis uses PbPb and pp data samples with integrated luminosities of 1.7 nb−1 and 301 pb−1, respectively, collected with the CMS experiment in 2018 and 2017. Events are required to have a photon with transverse momentum pTγ>100 GeV and at least one jet back-to-back in azimuth with respect to the photon and with transverse momentum pTjet such that pTjet/pTγ>0.4. The measured Rg and g distributions are unfolded to the particle level, which facilitates the comparison between the PbPb and pp results and with theoretical predictions. It is found that jets with pTjet/pTγ>0.8, i.e., those that closely balance the photon pTγ, are narrower in PbPb than in pp collisions. Relaxing the selection to include jets with pTjet/pTγ>0.4 reduces the narrowing of the angular structure of jets in PbPb relative to the pp reference. This shows that selection bias effects associated with jet energy loss play an important role in the interpretation of jet substructure measurements.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Measurement of inclusive and differential cross sections for W<sup>+</sup>W<sup>−</sup> production in proton-proton collisions at s=13.6 TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 861, ISSN: 0370-2693Measurements at s=13.6TeV of the opposite-sign W boson pair production cross section in proton-proton collisions are presented. The data used in this study were collected with the CMS detector at the CERN LHC in 2022, and correspond to an integrated luminosity of 34.8fb−1. Events are selected by requiring one electron and one muon of opposite charge. A maximum likelihood fit is performed on signal- and background-enriched data categories defined by the flavor and charge of the leptons, the number of jets, and number of jets originating from b quarks. The overall sensitivity is significantly better than that of previous results with a similar integrated luminosity. The improvement comes from a more refined control of experimental uncertainties and an improved fit strategy. An inclusive W+W− production cross section of 125.7±5.6 pb is measured, in agreement with standard model predictions. Cross sections are also reported in a fiducial region close to that of the detector acceptance, both inclusively and differentially, as a function of the jet multiplicity in the event. For the first time in proton-proton collisions, WW events with zero, one, and at least two jets are studied simultaneously and compared with recent theoretical predictions.
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Journal articleAalbers J, Akerib DS, Al Musalhi AK, et al., 2025,
Two-neutrino double electron capture of <sup>124</sup>Xe in the first LUX-ZEPLIN exposure
, Journal of Physics G: Nuclear and Particle Physics, Vol: 52, Pages: 015103-015103, ISSN: 0954-3899<jats:title>Abstract</jats:title> <jats:p>The broad physics reach of the LUX-ZEPLIN (LZ) experiment covers rare phenomena beyond the direct detection of dark matter. We report precise measurements of the extremely rare decay of <jats:sup>124</jats:sup>Xe through the process of two-neutrino double electron capture, utilizing a 1.39 kg × yr isotopic exposure from the first LZ science run. A half-life of <jats:inline-formula> <jats:tex-math></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mi>T</mml:mi> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mi>ν</mml:mi> <mml:mn>2</mml:mn> <mml:mi>EC</mml:mi> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:mo>=</mml:mo> <mml:mo stretchy="false">(</mml:mo> <mml:mn>1.09</mml:mn> <mml:mo>±</mml:mo> <mml:mn>0.1</mml:mn> <mml:msub> <mml:mn>4</mml:mn> <mml:mrow> <mml:mspace width="0.1em&
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Journal articleBarbone M, Tapper A, Luk W, et al., 2025,
Application of computational modelling to particle physics
, Communications in computational physics, ISSN: 1991-7120 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Measurement of multidifferential cross sections for dijet production in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$
, The European Physical Journal C, Vol: 85<jats:title>Abstract</jats:title> <jats:p>A measurement of the dijet production cross section is reported based on proton–proton collision data collected in 2016 at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\sqrt{s}=13\,\text {Te}\hspace{-.08em}\text {V} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mspace/> <mml:mi>Te</mml:mi> <mml:mspace/> <mml:mi>V</mml:mi> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of up to 36.3<jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\,\text {fb}^{-1}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mspace/> <mml:msup> <mml:mrow> <mml:mi>fb</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula>. Jets
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for charged-lepton flavor violation in the production and decay of top quarks using trilepton final states in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>13</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>
, Physical Review D, Vol: 111, ISSN: 2470-0010<jats:p>A search is performed for charged-lepton flavor violating processes in top quark (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>t</a:mi></a:math>) production and decay. The data were collected by the CMS experiment from proton-proton collisions at a center-of-mass energy of 13 TeV and correspond to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mn>138</c:mn><c:mtext> </c:mtext><c:mtext> </c:mtext><c:msup><c:mi>fb</c:mi><c:mrow><c:mo>−</c:mo><c:mn>1</c:mn></c:mrow></c:msup></c:math>. The selected events are required to contain one opposite-sign electron-muon pair, a third charged lepton (electron or muon), and at least one jet of which no more than one is associated with a bottom quark. Boosted decision trees are used to distinguish signal from background, exploiting differences in the kinematics of the final states particles. The data are consistent with the standard model expectation. Upper limits at 95% confidence level are placed in the context of effective field theory on the Wilson coefficients, which range between <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:mn>0.024</e:mn><e:mi>–</e:mi><e:mn>0.424</e:mn><e:mtext> </e:mtext><e:mtext> </e:mtext><e:msup><e:mrow><e:mi>TeV</e:mi></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>2</e:mn></e:mrow></e:msup></e:mrow></e:math> depending on the flavor of the associated light quark and the Lorentz structure of the interaction. These limits are converted to upper limits on branching fractions involving up (
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Journal articleHori M, 2025,
Antihydrogen’s more than fine spectrum
, Nature Physics, ISSN: 1745-2473 -
Journal articleAbe K, Abe S, Bronner C, et al., 2025,
First Joint Oscillation Analysis of Super-Kamiokande Atmospheric and T2K Accelerator Neutrino Data
, Physical Review Letters, Vol: 134, ISSN: 0031-9007The Super-Kamiokande and T2K Collaborations present a joint measurement of neutrino oscillation parameters from their atmospheric and beam neutrino data. It uses a common interaction model for events overlapping in neutrino energy and correlated detector systematic uncertainties between the two datasets, which are found to be compatible. Using 3244.4 days of atmospheric data and a beam exposure of 19.7(16.3)×1020 protons on target in (anti)neutrino mode, the analysis finds a 1.9σ exclusion of CP conservation (defined as JCP=0) and a 1.2σ exclusion of the inverted mass ordering.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Measurement of the double-differential inclusive jet cross section in proton-proton collisions at $$ \sqrt{s} $$ = 5.02 TeV
, Journal of High Energy Physics, Vol: 2025<jats:title>A<jats:sc>bstract</jats:sc> </jats:title> <jats:p>The inclusive jet cross section is measured as a function of jet transverse momentum <jats:italic>p</jats:italic> <jats:sub>T</jats:sub> and rapidity <jats:italic>y</jats:italic>. The measurement is performed using proton-proton collision data at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math> </jats:alternatives> </jats:inline-formula> = 5<jats:italic>.</jats:italic>02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb<jats:sup> <jats:italic>−</jats:italic>1</jats:sup>. The jets are reconstructed with the anti-<jats:italic>k</jats:italic> <jats:sub>T</jats:sub> algorithm using a distance parameter of <jats:italic>R</jats:italic> = 0<jats:italic>.</jats:italic>4, within the rapidity interval <jats:italic>|y| <</jats:italic> 2, and across the kinematic range 0<jats:italic>.</jats:italic>06 <jats:italic>< p</jats:italic> <jats:sub>T</jats:sub> <jats:italic><</jats:italic> 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonpertur
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Journal articleBhattacharya A, Sreeparvathy PC, Ahmed A, et al., 2025,
Giant Topological Hall Effect in Magnetic Weyl Metal Mn<inf>2</inf>Pd<inf>0.5</inf>Ir<inf>0.5</inf>Sn
, Advanced Functional Materials, ISSN: 1616-301XThe synergy between real and reciprocal space topology is anticipated to yield a diverse array of topological properties in quantum materials. This pursuit is addressed by achieving topologically safeguarded magnetic order in novel Weyl metallic Heusler alloy, Mn2Pd0.5Ir0.5Sn. The system possesses non-centrosymmetric D2d crystal symmetry with notable spin-orbit coupling effects. The first principles calculations confirm the topological non-trivial nature of band structure, including 42 pairs of Weyl nodes at/near the Fermi level, offering deeper insights into the observed anomalous Hall effect mediated by intrinsic Berry curvature. A unique canted magnetic ordering facilitates such rich topological features, manifesting through an exceptionally large topological Hall effect at low fields. The latter is sustained even at room temperature and compared with other known topological magnetic materials. Detailed micromagnetic simulations demonstrate the possible existence of an antiskyrmion lattice. These results underscore the D2d Heusler magnets as a possible platform to explore the intricate interplay of non-trivial topology across real and reciprocal spaces to leverage a plethora of emergent properties for spintronic applications.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Measurement of D0- D ¯ 0 mixing and search for CP violation with D0 →k+π- decays
, Physical Review D, Vol: 111, ISSN: 2470-0010A measurement of the time-dependent ratio of the D0→K+π- to D¯0→K+π- decay rates is reported. The analysis uses a sample of proton-proton collisions corresponding to an integrated luminosity of 6 fb-1 recorded by the LHCb experiment from 2015 through 2018 at a center-of-mass energy of 13 TeV. The D0 meson is required to originate from a D∗(2010)+→D0π+ decay, such that its flavor at production is inferred from the charge of the accompanying pion. The measurement is performed simultaneously for the K+ π- and K- π+ final states, allowing both mixing and CP-violation parameters to be determined. The value of the ratio of the decay rates at production is determined to be RKπ=(343.1±2.0)×10-5. The mixing parameters are measured to be cKπ=(51.4±3.5)×10-4 and cKπ′=(13±4)×10-6, where RKπcKπ is the linear coefficient of the expansion of the ratio as a function of decay time in units of the D0 lifetime, and cKπ′ is the quadratic coefficient, both averaged between the K+ π- and K- π+ final states. The precision is improved relative to the previous best measurement by approximately 60%. No evidence for CP violation is found.
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Journal articleZunica G, Zuliani D, Zou Q, et al., 2025,
Long-lived particle reconstruction downstream of the LHCb magnet
, European Physical Journal C, Vol: 85, ISSN: 1434-6044Charged-particle trajectories are usually reconstructed with the LHCb detector using combined information from the tracking devices placed upstream and downstream of the 4 T m dipole magnet. Trajectories reconstructed using only information from the tracker downstream of the dipole magnet, which are referred to as T tracks, have not been used for physics analysis to date. The challenges of the reconstruction of long-lived particles with T tracks for physics use are discussed and solutions are proposed. The feasibility and the tracking performance are studied using samples of long-lived Λ and KS0 hadrons decaying between 6.0 and 7.6 m downstream of the proton–proton collision point, thereby traversing most of the magnetic field region and providing maximal sensitivity to magnetic and electric dipole moments. The reconstruction can be expanded upstream to about 2.5 m for use in direct searches of exotic long-lived particles. The data used in this analysis have been recorded between 2015 and 2018 and correspond to an integrated luminosity of 6 fb-1. The results obtained demonstrate the possibility to further extend the decay volume and the physics reach of the LHCb experiment.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for a standard model-like Higgs boson in the mass range between 70 and 110 GeV in the diphoton final state in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 860, ISSN: 0370-2693The results of a search for a standard model-like Higgs boson decaying into two photons in the mass range between 70 and 110 GeV are presented. The analysis uses the data set collected by the CMS experiment in proton-proton collisions at s=13TeV corresponding to integrated luminosities of 36.3fb−1, 41.5fb−1 and 54.4fb−1 during the 2016, 2017, and 2018 LHC running periods, respectively. No significant excess over the background expectation is observed and 95% confidence level upper limits are set on the product of the cross section and branching fraction for decays of an additional Higgs boson into two photons. The maximum deviation with respect to the background is seen for a mass hypothesis of 95.4 GeV with a local (global) significance of 2.9 (1.3) standard deviations. The observed upper limit ranges from 15 to 73 fb.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Study of WH production through vector boson scattering and extraction of the relative sign of the W and Z couplings to the Higgs boson in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 860, ISSN: 0370-2693A search for the production of a W boson and a Higgs boson through vector boson scattering (VBS) is presented, using CMS data from proton-proton collisions at s=13TeV collected from 2016 to 2018. The integrated luminosity of the data sample is 138fb−1. Selected events must be consistent with the presence of two jets originating from VBS, the leptonic decay of the W boson to an electron or muon, possibly also through an intermediate τ lepton, and a Higgs boson decaying into a pair of b quarks, reconstructed as either a single merged jet or two resolved jets. A measurement of the process as predicted by the standard model (SM) is performed alongside a study of beyond-the-SM (BSM) scenarios. The SM analysis sets an observed (expected) 95% confidence level upper limit of 14.3 (9.9) on the ratio of the measured VBS WH cross section to that expected by the SM. The BSM analysis, conducted within the so-called κ framework, excludes all scenarios with λWZ<0 that are consistent with current measurements, where λWZ=κW/κZ and κW and κZ are the HWW and HZZ coupling modifiers, respectively. The significance of the exclusion is beyond 5 standard deviations, and it is consistent with the SM expectation of λWZ=1.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for bottom quark associated production of the standard model Higgs boson in final states with leptons in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 860, ISSN: 0370-2693This Letter presents the first search for bottom quark associated production of the standard model Higgs boson, in final states with leptons. Higgs boson decays to pairs of tau leptons and pairs of leptonically decaying W bosons are considered. The search is performed using data collected from 2016 to 2018 by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138fb−1. Upper limits at the 95% confidence level are placed on the signal strength for Higgs boson production in association with bottom quarks; the observed (expected) upper limit is 3.7 (6.1) times the standard model prediction.
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Journal articleKarikar A, Das K, Das I, 2025,
Magnetoresistive and magnetocaloric properties of polycrystalline Sm<inf>0.50</inf>Sr<inf>0.50</inf>MnO<inf>3</inf> compound with short range magnetic ordering
, Journal of Materials Science: Materials in Electronics, Vol: 36, ISSN: 0957-4522In this study, the magnetic and magneto-transport properties of polycrystalline Sm0.50Sr0.50MnO3 have been investigated. The presence of short-range magnetic order plays a crucial role in influencing electron transport, making it a promising pathway for tuning magnetoresistive properties for specific applications. This research focuses on the effects of magnetic nanoclusters on spin-dependent scattering and their impact on magneto-transport and magnetocaloric properties in polycrystalline Sm0.50Sr0.50MnO3. Experimental results reveal a significant magnetocaloric effect and notable magnetoresistance within the liquid nitrogen temperature range. At 100 K, the magnetoresistance reaches approximately 70% under an external magnetic field of 20 kOe. The magnetocaloric entropy change is calculated to be 3.5 J/kg-K for a 70 kOe magnetic field, with the entropy change curve exhibiting a broadened peak, leading to a substantial Relative Cooling Power (RCP). These findings enhance our understanding of the material’s behavior and highlight its potential for various technological applications.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurement of Λ_{b}^{0}, Λ_{c}^{+}, and Λ Decay Parameters Using Λ_{b}^{0}→Λ_{c}^{+}h^{-} Decays.
, Phys Rev Lett, Vol: 133A comprehensive study of the angular distributions in the bottom-baryon decays Λ_{b}^{0}→Λ_{c}^{+}h^{-}(h=π,K), followed by Λ_{c}^{+}→Λh^{+} with Λ→pπ^{-} or Λ_{c}^{+}→pK_{S}^{0} decays, is performed using a data sample of proton-proton collisions corresponding to an integrated luminosity of 9 fb^{-1} collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The decay parameters and the associated charge-parity (CP) asymmetries are measured, with no significant CP violation observed. For the first time, the Λ_{b}^{0}→Λ_{c}^{+}h^{-} decay parameters are measured. The most precise measurements of the decay parameters α, β, and γ are obtained for Λ_{c}^{+} decays and an independent measurement of the decay parameters for the strange-baryon Λ decay is provided. The results deepen our understanding of weak decay dynamics in baryon decays.
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Journal articleChatterjee S, Das I, 2024,
Desertion of anomalous magnetic transition and emergence of metallic state in Cu doped Eu2Ru2O7 pyrochlore.
, J Chem Phys, Vol: 161In this paper, we present a detailed investigation of the structural, magnetic, and electrical transport properties of Eu2-xCuxRu2O7 (x = 0, 0.2, 0.4) pyrochlores. X-ray diffraction measurements confirm the single-phase nature of all samples and also manifest the reduction of lattice parameters with the increase in copper doping concentration. The experimental results of the magnetic measurements indicate that an anomalous magnetic transition around 23 K arises due to the contribution of non-magnetic Eu3+ ions. The strength of this unnatural magnetic transition reduces with decreasing Eu concentration [i.e., with increasing copper doping (x)] and finally disappears for x = 0.4. Moreover, electrical transport measurements reveal a considerable decrease in resistivity for Cu doped samples compared to undoped samples, which indicates the increase in charge carrier concentration with increasing Cu content.
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Journal articlePal K, Dey S, Alam A, et al., 2024,
Revealing exchange bias in spin compensated systems for spintronics applications.
, Sci Rep, Vol: 14Antiferromagnetic materials offer potential for spintronic applications due to their resilience to magnetic field perturbations and lack of stray fields. Achieving exchange bias in these materials is crucial for certain applications; however, discovering such materials remains challenging due to their compensated spin structure. The quest for antiferromagnetic materials with exchange bias became a reality through our experimental study and theoretical simulation on Sr 2 FeIrO 6 and Sr 2 CoIrO 6 . This study also unveils the impact of ionic disorder and lattice distortion on magnetic properties. The presence of exchange bias in both materials, given their antiferromagnetic nature, is intriguing. This study opens up new avenues for achieving exchange bias in spin-compensated systems, offering potential for low power and ultra fast antiferromagnetic spintronic applications in future research endeavors.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Model-independent search for pair production of new bosons decaying into muons in proton-proton collisions at $$ \sqrt{s} $$ = 13 TeV
, Journal of High Energy Physics, Vol: 2024<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>The results of a model-independent search for the pair production of new bosons within a mass range of 0<jats:italic>.</jats:italic>21 <jats:italic>< m <</jats:italic> 60 GeV, are presented. This study utilizes events with a four-muon final state. We use two data sets, comprising 41<jats:italic>.</jats:italic>5 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> and 59<jats:italic>.</jats:italic>7 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> of proton-proton collisions at <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> = 13 TeV, recorded in 2017 and 2018 by the CMS experiment at the CERN LHC. The study of the 2018 data set includes a search for displaced signatures of a new boson within the proper decay length range of 0 <jats:italic>< cτ <</jats:italic> 100 mm. Our results are combined with a previous CMS result, based on 35<jats:italic>.</jats:italic>9 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup> of proton-proton collisions at <jats:inline-formula><jats:alternatives><jats:tex-math>$$ \sqrt{s} $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> </mml:math></jats:alternatives></jats:inline-formula> =
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurement of CP Violation Observables in D^{+}→K^{-}K^{+}π^{+} Decays.
, Phys Rev Lett, Vol: 133A search for violation of the charge-parity (CP) symmetry in the D^{+}→K^{-}K^{+}π^{+} decay is presented, with proton-proton collision data corresponding to an integrated luminosity of 5.4 fb^{-1}, collected at a center-of-mass energy of 13 TeV with the LHCb detector. A novel model-independent technique is used to compare the D^{+} and D^{-} phase-space distributions, with instrumental asymmetries subtracted using the D_{s}^{+}→K^{-}K^{+}π^{+} decay as a control channel. The p value for the hypothesis of CP conservation is 8.1%. The CP asymmetry observables A_{CP|S}^{ϕπ^{+}}=(0.95±0.43_{stat}±0.26_{syst})×10^{-3} and A_{CP|S}^{K[over ¯]^{*0}K^{+}}=(-0.26±0.56_{stat}±0.18_{syst})×10^{-3} are also measured. These results show no evidence of CP violation and represent the most sensitive search performed through the phase space of a multibody decay.
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Journal articleMazumdar D, Das K, Das I, 2024,
Magnetic exchange coupled composite behavior in the doped manganite nanoparticles: A proposed phenomenological model
, Physica B: Condensed Matter, Vol: 695, ISSN: 0921-4526In this paper, we comprehensively investigate the isothermal magnetization behavior of doped perovskite manganite nanoparticles. The focus is on understanding the impact of variation of particle sizes on the soft and hard magnetic phases with respect to the changes in the coercive field and remanent magnetization, both theoretically and experimentally. The study seeks to correlate experimental findings with the proposed phenomenological model to gain deeper insights into the underlying mechanisms governing exchange coupling and anisotropy effects in the nanocrystalline composites. The proposed phenomenological model beautifully demonstrates how the values of saturation magnetization and coercive field changes with changing the particle size in the nanocrystalline La0.48Ca0.52MnO3 (LCMO48) and La0.46Ca0.54MnO3 (LCMO46) compounds. In addition, the model provide an insights into the limitations of critical radius, size and shape of the nanocrystalline particle. This investigation looks into how the size of particles affects their magnetic properties, specifically coercive field and remanent magnetization.
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Journal articleDas K, Mazumdar D, Das I, 2024,
Structural distortion driven polaronic transport and table-like magnetocaloric properties in polycrystalline Tb0.7Sr0.3MnO3 compound.
, Phys Chem Chem Phys, Vol: 26, Pages: 29987-30001This research mainly explores the structural, magnetic, magneto-transport, and magnetocaloric properties of the polycrystalline Tb0.7Sr0.3MnO3 compound. The results reveal a significant modification of the compound's ground state with increasing the strength of the magnetic field. The strong distortion in the crystal structure highly controls the magnetic and magneto-transport properties of the system. Along with this, a prominent 'table-like' nature in the temperature-dependent magnetic entropy change has been noticed, showcasing the potential application of the compound in the field of Ericsson refrigeration technology. Notably, a substantial low-field magnetoresistance is noticed around T ∼ 60 K. The temperature dependent electrical resistivity data can be well explained with the help of polaronic transport conduction mechanisms namely small-polaron hopping and variable-range hopping models. Various significant parameters are calculated and the system possesses a non-adiabatic polaron hopping mechanism with a large electron-phonon coupling constant. This investigation contributes valuable insights into the intricate dynamics of the 3d-4f exchange interaction and crystallographic distortion, shedding light on the underlying mechanisms governing the magnetic and electrical transport properties of the Sr-doped TbMnO3 compound.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for CP violation in $${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$ decays in proton–proton collisions at $$\sqrt{s} = 13\,\text {Te}\hspace{-.08em}\text {V} $$
, The European Physical Journal C, Vol: 84<jats:title>Abstract</jats:title> <jats:p>A search is reported for charge-parity <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$CP$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>CP</mml:mi> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> violation in <jats:inline-formula> <jats:alternatives> <jats:tex-math>$${{{\textrm{D}}}^{{0}}} \rightarrow {{\textrm{K}} _{\text {S}}^{{0}}} {{\textrm{K}} _{\text {S}}^{{0}}} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mtext>D</mml:mtext> </mml:mrow> <mml:mn>0</mml:mn> </mml:msup> <mml:mo>→</mml:mo> <mml:msubsup> <mml:mtext>K</mml:mtext> <mml:mrow> <mml:mtext>S</mml:mtext> </mml:mrow> <mml:mn>0</mml:mn> </mml:msubsup> <mml:msubsup> <mml:mtext>K</mml:mtext> <mml:mrow> <mml:mtext>S</mml:mtext> </mml:mrow> <mml:mn>0</mml:mn> </mml:msubsup> </mml:mrow> </mml:math> </jats:alternati
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurements of polarization and spin correlation and observation of entanglement in top quark pairs using (Formula presented) events from proton-proton collisions at (Formula presented)
, Physical Review D, Vol: 110, ISSN: 2470-0010Measurements of the polarization and spin correlation in top quark pairs ((Formula presented)) are presented using events with a single electron or muon and jets in the final state. The measurements are based on proton-proton collision data from the LHC at (Formula presented) collected by the CMS experiment, corresponding to an integrated luminosity of (Formula presented). All coefficients of the polarization vectors and the spin correlation matrix are extracted simultaneously by performing a binned likelihood fit to the data. The measurement is performed inclusively and in bins of additional observables, such as the mass of the (Formula presented) system and the top quark scattering angle in the (Formula presented) rest frame. The measured polarization and spin correlation are in agreement with the standard model. From the measured spin correlation, conclusions on the (Formula presented) spin entanglement are drawn by applying the Peres-Horodecki criterion. The standard model predicts entangled spins for (Formula presented) states at the production threshold and at high masses of the (Formula presented) system. Entanglement is observed for the first time in events at high (Formula presented) mass, where a large fraction of the (Formula presented) decays are spacelike separated, with an expected and observed significance of above 5 standard deviations.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurement of boosted Higgs bosons produced via vector boson fusion or gluon fusion in the H →bb¯ decay mode using LHC proton-proton collision data at s = 13 TeV
, Journal of High Energy Physics, Vol: 2024A measurement is performed of Higgs bosons produced with high transverse momentum (pT) via vector boson or gluon fusion in proton-proton collisions. The result is based on a data set with a center-of-mass energy of 13 TeV collected in 2016–2018 with the CMS detector at the LHC and corresponds to an integrated luminosity of 138 fb−1. The decay of a high-pT Higgs boson to a boosted bottom quark-antiquark pair is selected using large-radius jets and employing jet substructure and heavy-flavor taggers based on machine learning techniques. Independent regions targeting the vector boson and gluon fusion mechanisms are defined based on the topology of two quark-initiated jets with large pseudorapidity separation. The signal strengths for both processes are extracted simultaneously by performing a maximum likelihood fit to data in the large-radius jet mass distribution. The observed signal strengths relative to the standard model expectation are 4.9−1.6+1.9 and 1.6−1.5+1.7 for the vector boson and gluon fusion mechanisms, respectively. A differential cross section measurement is also reported in the simplified template cross section framework.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurement of the effective leptonic weak mixing angle
, Journal of High Energy Physics, Vol: 2024Using pp collision data at s = 13 TeV, recorded by the LHCb experiment between 2016 and 2018 and corresponding to an integrated luminosity of 5.4 fb−1, the forward-backward asymmetry in the pp → Z/γ* → μ+μ− process is measured. The measurement is carried out in ten intervals of the difference between the muon pseudorapidities, within a fiducial region covering dimuon masses between 66 and 116 GeV, muon pseudorapidities between 2.0 and 4.5 and muon transverse momenta above 20 GeV. These forward-backward asymmetries are compared with predictions, at next-to-leading order in the strong and electroweak couplings. The measured effective leptonic weak mixing angle is (Formula presented.) where the first uncertainty is statistical, the second arises from systematic uncertainties associated with the asymmetry measurement, and the third arises from uncertainties in the fit model used to extract sin2θeffℓ from the asymmetry measurement. This result is based on an arithmetic average of results using the CT18, MSHT20, and NNPDF31 parameterisations of the proton internal structure, and is consistent with previous measurements and with predictions from the global electroweak fit.
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